417 results on '"Mark Feldman"'
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2. Clinical Laboratory Perspective on Streptococcus halichoeri, an Unusual Nonhemolytic, Lancefield Group B Streptococcus Causing Human Infections
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Salika M. Shakir, Rahul Gill, Jonathan Salberg, E. Susan Slechta, Mark Feldman, Thomas Fritsche, Jill Clarridge, Susan E. Sharp, and Mark A. Fisher
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antimicrobial resistance ,bacteria ,underlying health conditions ,grey seals ,streptococci ,Streptococcus halichoeri ,Medicine ,Infectious and parasitic diseases ,RC109-216 - Abstract
Streptococcus halichoeri is a relatively newly identified species of pyogenic streptococci that causes zoonotic infection in humans. S. halichoeri was first described in 2004 as indigenous to seals, and only 8 reports of human S. halichoeri infection have been published. S. halichoeri grows as small, white, nonhemolytic colonies and may be strongly catalase-positive on routine blood agar media, which can lead to isolates being misidentified as coagulase-negative staphylococci. S. halichoeri tests positive for Lancefield group B antigen, like S. agalactiae, but can be identified with matrix-assisted laser desorption/ionization time of flight mass spectrometry or partial 16S rRNA sequencing. We describe 3 cases of S. halichoeri bone and joint infections in patients in the United States with underlying health conditions. In addition, we examine the microbiologic characteristics of S. halichoeri and discuss the importance of fully identifying this organism that might otherwise be disregarded as a skin commensal.
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- 2021
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3. Anandamide alters the membrane properties, halts the cell division and prevents drug efflux in multidrug resistant Staphylococcus aureus
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Shreya Banerjee, Ronit Vogt Sionov, Mark Feldman, Reem Smoum, Raphael Mechoulam, and Doron Steinberg
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Medicine ,Science - Abstract
Abstract Antibiotic resistance is a serious public health problem throughout the world. Overcoming methicillin and multidrug-resistant Staphylococcus aureus (MRSA/MDRSA) infections has become a challenge and there is an urgent need for new therapeutic approaches. We have previously demonstrated that the endocannabinoid Anandamide (AEA) can sensitize MRSA to antibiotics. Here we have studied the mechanism of action using a MDRSA clinical isolate that are sensitized by AEA to methicillin and norfloxacin. We found that AEA treatment halts the growth of both antibiotic-sensitive and antibiotic-resistant S. aureus. The AEA-treated bacteria become elongated and the membranes become ruffled with many protrusions. AEA treatment also leads to an increase in the percentage of bacteria having a complete septum, suggesting that the cell division is halted at this stage. The latter is supported by cell cycle analysis that shows an accumulation of bacteria in the G2/M phase after AEA treatment. We further observed that AEA causes a dose-dependent membrane depolarization that is partly relieved upon time. Nile red staining of the bacterial membranes indicates that AEA alters the membrane structures. Importantly, 4′-6-diamidino-2-phenylindole (DAPI) accumulation assay and ethidium bromide efflux (EtBr) assay unveiled that AEA leads to a dose-dependent drug accumulation by inhibiting drug efflux. In conclusion, our study demonstrates that AEA interferes with cell division, alters the membrane properties of MDRSA, and leads to increased intracellular drug retention, which can contribute to the sensitization of MDRSA to antibiotics.
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- 2021
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4. Acute Sterile Meningitis as a Primary Manifestation of Pituitary Apoplexy
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Gayane Tumyan, MD, Yogamaya Mantha, MD, Rahul Gill, MD, and Mark Feldman, MD
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pituitary apoplexy ,pituitary adenoma ,sterile meningitis ,pituitary tumor ,macroadenoma ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Objective: We report a case of pituitary apoplexy (PA) with negative radiographic findings for PA and cerebrospinal fluid (CSF) analysis consistent with neutrophilic meningitis. PA is a rare endocrinopathy requiring prompt diagnosis and treatment. Presentation with acute neutrophilic meningitis is uncommon. Methods: The diagnostic modalities included pituitary function tests (adrenocorticotropic hormone, thyroid-stimulating hormone, luteinizing hormone, prolactin), brain computed tomography and magnetic resonance imaging (MRI), and CSF analysis. Results: A 67-year-old man presented with worsening headache, nausea, and retching. He was somnolent with an overall normal neurologic examination other than a peripheral vision defect in the left eye. MRI showed a pituitary mass bulging into the suprasellar cistern with optic chiasm elevation, consistent with pituitary macroadenoma. Laboratory evaluation revealed decreased levels of adrenocorticotropic hormone, random cortisol, thyroid-stimulating hormone, thyroxine, luteinizing hormone, and testosterone. He had worsening encephalopathy with left eye ptosis and decreased vision, prompting a repeat computed tomography and MRI, showing no interval change in the pituitary adenoma or evidence of bleeding. CSF analysis revealed a leukocyte count of 1106/mm3 (89% neutrophils), a total protein level of 138 mg/dL, red blood cell count of 2040/mm3 without xanthochromia, and glucose level of 130 mg/dL. The CSF culture result was negative. Transsphenoidal resection revealed a necrotic pituitary adenoma with apoplexy. Conclusions: Including PA in the differential diagnosis of acute headache is important, particularly in patients with visual disturbances. PA can present with sterile meningitis, mimicking acute bacterial meningitis. While neuroimaging can help detect PA, the diagnosis of PA remains largely clinical.
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- 2021
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5. Masson Tumor in the Left Atrial Appendage Presenting as Cardioembolic Cerebral Infarction
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Yogamaya Mantha, MD, Rakushumimarika Harada, MD, Michinari Hieda, MD, MS, PhD, Andrew Assaf, MD, Uday Tatiraju, MS, Mark Feldman, MD, and Darryl Kawalsky, MD
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cardio-oncology ,cardioembolic disease ,echocardiography ,left atrial appendage ,Masson tumor ,multimodality imaging ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
A 70-year-old woman presented with aphasia caused by acute infarction in the left middle cerebral artery. Cardiac investigation revealed progressively increasing mobile mass in the left atrial appendage over 2 months (from 9 to 15 mm). Decision was made to proceed with mass resection, and pathological evaluation confirmed Masson tumor. (Level of Difficulty: Advanced.)
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- 2020
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6. Anomalous Origin of a Right Coronary Artery from the Pulmonary Artery in a Middle-Aged Woman
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Yogamaya Mantha, MD, Mark Feldman, MD, Andrew Assaf, MD, Rakushumimarika Harada, MD, David Musselman, MD, Michinari Hieda, MD, MS, PhD, and Darryl Kawalsky, MD
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adult congenital heart disease ,anomalous origin of right coronary artery from pulmonary artery ,echocardiography ,imaging ,right coronary artery anomalous origin ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
A 53-year-old female patient presented for evaluation of a murmur. The examination revealed a 2/6 systolic ejection murmur in the left upper sternal border. Transthoracic echocardiography with color Doppler showed increased blood flow around the apex of the right ventricle. Further imaging revealed the right coronary artery emerging from the pulmonary artery. (Level of Difficulty: Beginner.)
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- 2020
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7. Prolonged Inhibition of Streptococcus mutans Growth and Biofilm Formation by Sustained Release of Chlorhexidine from Varnish Coated Dental Abutments: An in Vitro Study
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Mark Feldman, Walid Shaaban Moustafa Elsayed, Michael Friedman, Irith Gati, Doron Steinberg, and Hesham Marei
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Dentistry ,RK1-715 - Abstract
Background. It has been confirmed that bacterial biofilm covering dental implants is the main microbial source causing preimplant infectious and inflammatory diseases. The purpose of this study was to evaluate the antibacterial/antibiofilm effect of chlorhexidine, incorporated into a sustained-release varnish of chlorhexidine (SRV-CHX) coating, on dental abutments. Materials and Methods. Three kinds of dental abutments were used: a high-performance semi-crystalline engineering thermoplastic polyetheretherketone (PEAK) healing abutment, a titanium healing abutment, and a titanium permanent abutment. These abutments were coated with SRV-CHX or SRV-placebo and exposed daily to fresh cultures of Streptococcus mutans. The effect of SRV-CHX on S. mutans growth on agar plates was studied by measuring the zone of inhibition (ZOI) around each tested abutment every day for a period of 36 days. Biofilm formation on the SRV-CHX/placebo-coated abutments was detected using confocal laser scanning microscopy (CLSM) and high-resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), and monitored by crystal violet (CV) staining. Results. SRV-CHX-coated abutments 2 and 3 were able to inhibit S. mutans growth for 34 days, while abutment 1 inhibited growth for 32 days. Abutment-associated biofilm formation was notably inhibited by SRV-CHX coating after 13 days of incubation with S. mutans. Finally, the biofilm formed around SRV-CHX-coated abutments was completely inhibited up to 12 days of abutment exposure to S. mutans. Conclusion. Coating of dental abutments with SRV-CHX demonstrated long-term effective inhibition of S. mutans growth and biofilm formation on the abutment surface.
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- 2022
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8. Improved Anti-Biofilm Effect against the Oral Cariogenic Streptococcus mutans by Combined Triclosan/CBD Treatment
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Maayan Avraham, Doron Steinberg, Tamar Barak, Miriam Shalish, Mark Feldman, and Ronit Vogt Sionov
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anti-bacterial ,anti-biofilm ,cannabidiol ,dental caries ,Streptococcus mutans ,triclosan ,Biology (General) ,QH301-705.5 - Abstract
Streptococcus mutans is a Gram-positive bacterium highly associated with dental caries, and it has a strong biofilm-forming ability, especially in a sugar-rich environment. Many strategies have been undertaken to prevent dental caries by targeting these bacteria. Recently, we observed that a sustained-release varnish containing triclosan and cannabidiol (CBD) was more efficient than each compound alone in preventing biofilm formation by the fungus Candida albicans, which is frequently involved in oral infections together with S. mutans. It was therefore inquiring to study the effect of this drug combination on S. mutans. We observed that the combined treatment of triclosan and CBD had stronger anti-bacterial and anti-biofilm activity than each compound alone, thus enabling the use of lower concentrations of each drug to achieve the desired effect. The combined drug treatment led to an increase in the SYTO 9low, propidium iodide (PI)high bacterial population as analyzed by flow cytometry, indicative for bacteria with disrupted membrane. Both triclosan and CBD induced membrane hyperpolarization, although there was no additive effect on this parameter. HR-SEM images of CBD-treated bacteria show the appearance of elongated and swollen bacteria with several irregular septa structures, and upon combined treatment with triclosan, the bacteria took on a swollen ellipse and sometimes oval morphology. Increased biofilm formation was observed at sub-MIC concentrations of each compound alone, while combining the drugs at these sub-MIC concentrations, the biofilm formation was prevented. The inhibition of biofilm formation was confirmed by CV biomass staining, MTT metabolic activity, HR-SEM and live/dead together with exopolysaccharide (EPS) staining visualized by spinning disk confocal microscopy. Importantly, the concentrations required for the anti-bacterial and anti-biofilm activities toward S. mutans were non-toxic to the normal Vero epithelial cells. In conclusion, the data obtained in this study propose a beneficial role of combined triclosan/CBD treatment for potential protection against dental caries.
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- 2023
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9. Potential Combinatory Effect of Cannabidiol and Triclosan Incorporated into Sustained Release Delivery System against Oral Candidiasis
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Mark Feldman, Irith Gati, Ronit Vogt Sionov, Sharonit Sahar-Helft, Michael Friedman, and Doron Steinberg
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C. albicans ,CBD ,triclosan ,SRV ,biofilm ,Pharmacy and materia medica ,RS1-441 - Abstract
Candida albicans is a common fungal pathogen. Biofilm formation on various surfaces is an important determinant of C. albicans pathogenicity. Our previous results demonstrated the high potential of cannabidiol (CBD) to affect C. albicans biofilms. Based on these data, we investigated the possibility of incorporating CBD and/or triclosan (an antimicrobial agent that is widely utilized in dentistry) in a sustained-release varnish (SRV) (SRV-CBD, SRV-triclosan) to increase their pharmaceutical potential against C. albicans biofilm, as well as that of the mixture of the agents into SRV (SRV-CBD/triclosan). The study was conducted in a plastic model, on agar, and in an ex vivo tooth model. Our results demonstrated strong antibiofilm activity of SRV-CBD and SRV-triclosan against C. albicans in all tested models. Both formulations were able to inhibit biofilm formation and to remove mature fungal biofilm. In addition, SRV-CBD and SRV-triclosan altered C. albicans morphology. Finally, we observed a dramatic enhancement of antibiofilm activity when combined SRV-CBD/triclosan was applied. In conclusion, we propose that incorporation of CBD or triclosan into SRV is an effective strategy to fight fungal biofilms. Importantly, the data demonstrate that our CBD/triclosan varnish is safe, and is not cytotoxic for normal mammalian cells. Furthermore, we propose that CBD and triclosan being in mixture in SRV exhibit complementary antibiofilm activity, and thus can be explored for further development as a potential treatment against fungal infections.
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- 2022
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10. Potential combinations of endocannabinoid/endocannabinoid-like compounds and antibiotics against methicillin-resistant Staphylococcus aureus.
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Mark Feldman, Reem Smoum, Raphael Mechoulam, and Doron Steinberg
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Medicine ,Science - Abstract
Infections caused by antibiotic-resistant strains of Staphylococcus aureus have reached epidemic proportions globally. Our previous study showed antimicrobial effects of anandamide (AEA) and arachidonoyl serine (AraS) against methicillin (MET)-resistant S. aureus (MRSA) strains, proposing the therapeutic potential of these endocannabinoid/endocannabinoid-like (EC/EC-like) agents for the treatment of MRSA. Here, we investigated the potential synergism of combinations of AEA and AraS with different types of antibiotics against MRSA grown under planktonic growth or biofilm formation. The most effective combinations under planktonic conditions were mixtures of AEA and ampicillin (AMP), and of AraS and gentamicin (GEN). The combination with the highest synergy in the biofilm formation against all tested bacterial strains was AEA and MET. Moreover, the combination of AraS and MET synergistically caused default of biofilm formation. Slime production of MRSA was also dramatically impaired by AEA or AraS combined with MET. Our data suggest the novel potential activity of combinations of EC/EC-like agents and antibiotics in the prevention of MRSA biofilm formation.
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- 2020
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11. A Nonpediatric Extraosseous Ewing Sarcoma of the Pancreas: Differential Diagnosis and Therapeutic Strategies
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Binoy Yohannan and Mark Feldman
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Extraosseous Ewing’s sarcoma is a rare and aggressive malignant tumor with a poor prognosis. The pancreas is an extremely uncommon primary site, with only 27 cases that have been published worldwide. We report a 26-year-old female who presented with 5 days of left upper quadrant pain, nausea, and vomiting. On examination, she was anicteric and had epigastric and left upper quadrant tenderness without guarding, rebound tenderness, or a palpable mass. She had slightly elevated serum aminotransferase and lipase levels. Abdominal computerized tomography revealed a multilobulated tumor arising from the body and tail of the pancreas. A biopsy confirmed a small round cell tumor, and immunohistochemistry was positive for CD99 in approximately 70% of the tumor cells. A fluorescence in situ hybridization (FISH) assay showed a 22q12 rearrangement. She was diagnosed with extraosseous Ewing sarcoma of the pancreas and underwent multiagent neoadjuvant chemotherapy followed by surgical resection, but subsequent imaging revealed evidence of systemic disease progression. She chose to go on hospice care and died a few weeks later.
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- 2020
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12. Impact of Treatment with Direct Acting Antiviral Drugs on Glycemic Control in Patients with Hepatitis C and Diabetes Mellitus
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Pradeep Kumar Mada, Matthew E. Malus, Arvin Parvathaneni, Bing Chen, Gabriel Castano, Sharon Adley, Maureen Moore, Michinari Hieda, Mohammed J. Alam, Mark Feldman, and John William King
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Diseases of the digestive system. Gastroenterology ,RC799-869 - Abstract
Aim. To assess the effect of treating chronic hepatitis C virus (HCV) infection with direct acting antiviral drugs (DAAs) on glycemic control in patients with concomitant diabetes mellitus (DM). Methods. We performed a retrospective case-control study in a viral hepatitis ambulatory clinic in Shreveport, Louisiana, during the period 11/01/2014 to 12/31/2017. All the clinic patient ages 18 years and above with treatment-naïve/biopsy-proven chronic hepatitis C and DM (hemoglobin A1C level≥6.5%) who were eligible for treatment were included in the study. Of 118 such patients, 59 were treated with oral DAAs for 8-12 weeks with the goal of achieving a sustained virologic response (SVR). A control group of 59 patients did not receive treatment for their hepatitis C and was followed in the clinic. Patients in the control group did not receive treatment either due to insurance issues or refusal of hepatitis C treatment. Results. Fifty-five of the 59 patients treated with DAAs (93%) achieved a SVR. Six months after treatment completion, their mean±SEM HbA1C level had decreased by 1.1±0.03% (P
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- 2020
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13. Entecavir-Associated Thrombocytopenia: A Case Report and Review of the Pathophysiology, Diagnosis, and Treatment of a Rare but Reversible Cause of Thrombocytopenia
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Binoy Yohannan, Dai Chu N. Luu, and Mark Feldman
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Diseases of the blood and blood-forming organs ,RC633-647.5 - Abstract
Drug-associated thrombocytopenia is often unrecognized. We report a 76-year-old female with lymphoma who presented with easy bruising and oral bleeding. She had undergone screening for hepatitis B virus (HBV) prior to starting rituximab and was found to have hepatitis B core serum antibody (IgG anti-HBc). She was therefore treated with prophylactic entecavir 0.5 mg daily to prevent reactivation of HBV. Her initial platelet count was 136,000/mm3. Five days after starting entecavir, she presented with bruising and oral bleeding and was found to have a platelet count of 7,000/mm3. A coagulation profile and the rest of the blood parameters (RBC and WBC counts) were normal. Entecavir was stopped, and she was given 3 units of apheresed platelets followed by intravenous immunoglobulin (1 g/kg) for 5 consecutive days. Her platelet counts improved and normalized in one week. She was diagnosed with entecavir-induced thrombocytopenia based on the temporal relationship and after carefully excluding alternate causes of thrombocytopenia. This case highlights the importance of recognizing drug-induced thrombocytopenia (DITP) as a reversible cause of thrombocytopenia.
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- 2019
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14. Fatal Balamuthia mandrillaris Encephalitis
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Binoy Yohannan and Mark Feldman
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Infectious and parasitic diseases ,RC109-216 - Abstract
Balamuthia mandrillaris is a rare cause of granulomatous meningoencephalitis associated with high mortality. We report a 69-year-old Caucasian female who presented with a 3-day history of worsening confusion and difficulty with speech. On admission, she was disoriented and had expressive dysphasia. Motor examination revealed a right arm pronator drift. Cerebellar examination showed slowing of finger-nose testing on the left. She was HIV-negative, but the absolute CD4 count was low. Neuroimaging showed three cavitary, peripherally enhancing brain lesions, involving the right frontal lobe, the left basal ganglia, and the left cerebellar hemisphere. She underwent right frontal craniotomy with removal of tan, creamy, partially liquefied necrotic material from the brain, consistent with granulomatous amoebic encephalitis on tissue staining. Immunohistochemical studies and PCR tests confirmed infection with Balamuthia mandrillaris. She was started on pentamidine, sulfadiazine, azithromycin, fluconazole, flucytosine, and miltefosine. The postoperative course was complicated by an ischemic stroke, and she died a few weeks later.
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- 2019
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15. Anti-Biofilm Activity of Cannabidiol against Candida albicans
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Mark Feldman, Ronit Vogt Sionov, Raphael Mechoulam, and Doron Steinberg
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C. albicans ,CBD ,biofilm ,virulence ,cell stress ,gene expression ,Biology (General) ,QH301-705.5 - Abstract
Candida albicans is a common fungal pathogen in humans. Biofilm formation is an important virulence factor of C. albicans infections. We investigated the ability of the plant-derived cannabidiol (CBD) to inhibit the formation and removal of fungal biofilms. Further, we evaluated its mode of action. Our findings demonstrate that CBD exerts pronounced time-dependent inhibitory effects on biofilm formation as well as disruption of mature biofilm at a concentration range below minimal inhibitory and fungicidal concentrations. CBD acts at several levels. It modifies the architecture of fungal biofilm by reducing its thickness and exopolysaccharide (EPS) production accompanied by downregulation of genes involved in EPS synthesis. It alters the fungal morphology that correlated with upregulation of yeast-associated genes and downregulation of hyphae-specific genes. Importantly, it represses the expression of C. albicans virulence-associated genes. In addition, CBD increases ROS production, reduces the intracellular ATP levels, induces mitochondrial membrane hyperpolarization, modifies the cell wall, and increases the plasma membrane permeability. In conclusion, we propose that CBD exerts its activity towards C. albicans biofilm through a multi-target mode of action, which differs from common antimycotic agents, and thus can be explored for further development as an alternative treatment against fungal infections.
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- 2021
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16. Polyphenols Inhibit Candida albicans and Streptococcus mutans Biofilm Formation
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Yosi Farkash, Mark Feldman, Isaac Ginsburg, Doron Steinberg, and Miriam Shalish
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Streptococcus mutans ,Candida albicans ,Padma hepaten ,polyphenon from green tea ,polyphenols ,caries ,Dentistry ,RK1-715 - Abstract
Background: Streptococcus mutans (S. mutans) and Candida albicans (C. albicans) are two major contributors to dental caries. They have a symbiotic relationship, allowing them to create an enhanced biofilm. Our goal was to examine whether two natural polyphenols (Padma hepaten (PH) and a polyphenol extraction from green tea (PPFGT)) could inhibit the caries-inducing properties of S. mutans and C. albicans. Methods: Co-species biofilms of S. mutans and C. albicans were grown in the presence of PH and PPFGT. Biofilm formation was tested spectrophotometrically. Exopolysaccharides (EPS) secretion was quantified using confocal scanning laser microscopy. Biofilm development was also tested on orthodontic surfaces (Essix) to assess biofilm inhibition ability on such an orthodontic appliance. Results: PPFGT and PH dose-dependently inhibited biofilm formation without affecting the planktonic growth. We found a significant reduction in biofilm total biomass using 0.625 mg/mL PPFGT and 0.16 mg/mL PH. A concentration of 0.31 mg/mL PPFGT and 0.16 mg/mL PH inhibited the total cell growth by 54% and EPS secretion by 81%. A reduction in biofilm formation and EPS secretion was also observed on orthodontic PVC surfaces. Conclusions: The polyphenolic extractions PPFGT and PH have an inhibitory effect on S. mutans and C. albicans biofilm formation and EPS secretion.
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- 2019
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17. Modeling Commercial Freshwater Turtle Production on US Farms for Pet and Meat Markets.
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Ivana Mali, Hsiao-Hsuan Wang, William E Grant, Mark Feldman, and Michael R J Forstner
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Medicine ,Science - Abstract
Freshwater turtles are being exploited for meat, eggs, traditional medicine, and pet trade. As a response, turtle farming became a booming aquaculture industry in the past two decades, specifically in the southeastern states of the United States of America (US) and across Southeast Asia. However, US turtle farms are currently producing turtles only for the pet trade while commercial trappers remain focused on catching the largest individuals from the wild. In our analyses we have created a biological and economic model that describes farming operations on a representative turtle farm in Louisiana. We first modeled current production of hatchling and yearling red-eared slider turtles (Trachemys scripta elegans) (i.e., traditional farming) for foreign and domestic pet markets, respectively. We tested the possibility of harvesting adult turtles from the breeding stock for sale to meat markets to enable alternative markets for the farmers, while decreasing the continued pressures on wild populations (i.e., non-traditional farming). Our economic model required current profit requirements of ~$13/turtle or ~$20.31/kg of meat from non-traditional farming in order to acquire the same profit as traditional farming, a value which currently exceeds market values of red-eared sliders. However, increasing competition with Asian turtle farms and decreasing hatchling prices may force the shift in the US toward producing turtles for meat markets. In addition, our model can be modified and applied to more desirable species on the meat market once more knowledge is acquired about species life histories and space requirements under farmed conditions.
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- 2015
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18. Therapeutic potential of thiazolidinedione-8 as an antibiofilm agent against Candida albicans.
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Mark Feldman, Abed Al-Quntar, Itzhak Polacheck, Michael Friedman, and Doron Steinberg
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Medicine ,Science - Abstract
Candida albicans is known as a commensal microorganism but it is also the most common fungal pathogen in humans, causing both mucosal and systemic infections. Biofilm-associated C. albicans infections present clinically important features due to their high levels of resistance to traditional antifungal agents. Quorum sensing is closely associated with biofilm formation and increasing fungal pathogenicity. We investigated the ability of the novel bacterial quorum sensing quencher thiazolidinedione-8 (S-8) to inhibit the formation of, and eradication of mature C. albicans biofilms. In addition, the capability of S-8 to alter fungal adhesion to mammalian cells was checked. S-8 exhibited specific antibiofilm and antiadhesion activities against C. albicans, at four- to eightfold lower concentrations than the minimum inhibitory concentration (MIC). Using fluorescence microscopy, we observed that S-8 dose-dependently reduces C. albicans-GFP binding to RAW macrophages. S-8 at sub-MICs also interfered with fungal morphogenesis by inhibiting the yeast-to-hyphal form transition. In addition, the tested agent strongly affected fungal cell wall characteristics by modulating its hydrophobicity. We evaluated the molecular mode of S-8 antibiofilm and antiadhesion activities using real-time RT-PCR. The expression levels of genes associated with biofilm formation, adhesion and filamentation, HWP1, ALS3 and EAP1, respectively, were dose-dependently downregulated by S-8. Transcript levels of UME6, responsible for long-term hyphal maintenance, were also significantly decreased by the tested agent. Both signaling pathways of hyphal formation-cAMP-PKA and MAPK-were interrupted by S-8. Their upstream general regulator RAS1 was markedly suppressed by S-8. In addition, the expression levels of MAPK cascade components CST20, HST7 and CPH1 were downregulated by S-8. Finally, transcriptional repressors of filament formation, TUP1 and NRG1, were dramatically upregulated by our compound. Our results indicate that S-8 holds a novel antibiofilm therapeutic mean in the treatment and prevention of biofilm-associated C. albicans infections.
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- 2014
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19. Multiple coinfections and Guillain Barré syndrome following outdoor travel to the American Northeast
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William Farrington, Farzam Farahani, Kevin Garrett Tayon, Jaclyn Rudzinski, Mark Feldman, and Kartavya Sharma
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Case Studies ,General Medicine - Abstract
A 66-year-old immunocompetent man with preceding travel through the Northeastern United States developed Guillain-Barré syndrome. A broad search for infections revealed intraerythrocytic parasites on blood smear and positive polymerase chain reaction for Babesia microti; elevated IgM/IgG serologies for Ehrlichia chaffeensis; elevated IgM/IgG serologies and qualitative polymerase chain reaction for Epstein-Barr virus; and fecal culture growth of Arcobacter butzleri. In this report, we discuss the known or suspected association of these infectious agents with Guillain-Barré syndrome. This case also highlights the importance, in the setting of endemic exposure, of screening for multiple coinfections that can be transmitted by the same arthropod vector.
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- 2023
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20. International Arbitration and Transparency
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Mark Feldman
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- 2023
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21. Anti-Bacterial Effect of Cannabidiol against the Cariogenic Streptococcus mutans Bacterium: An In Vitro Study
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Tamar Barak, Eden Sharon, Doron Steinberg, Mark Feldman, Ronit Vogt Sionov, and Miriam Shalish
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Inorganic Chemistry ,Organic Chemistry ,General Medicine ,Physical and Theoretical Chemistry ,anti-bacterial ,anti-biofilm ,cannabidiol ,dental caries ,Streptococcus mutans ,Molecular Biology ,Spectroscopy ,Catalysis ,Computer Science Applications - Abstract
Dental caries is caused by biofilm-forming acidogenic bacteria, especially Streptococcus mutans, and is still one of the most prevalent human bacterial diseases. The potential use of cannabidiol (CBD) in anti-bacterial therapies has recently emerged. Here we have studied the anti-bacterial and anti-biofilm activity of CBD against S. mutans. We measured minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC). The bacterial growth and changes in pH values were measured in a kinetic study. The biofilm biomass was assessed by Crystal Violet staining and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) metabolic assay. Spinning Disk Confocal Microscopy (SDCM) was used to assess biofilm structure, bacterial viability and extracellular polysaccharide (EPS) production. CBD inhibited S. mutans planktonic growth and biofilm formation in a dose-dependent manner, with similar MIC and MBIC values (5 µg/mL). CBD prevented the bacteria-mediated reduction in pH values that correlated with bacterial growth inhibition. SDCM showed a decrease of 50-fold in live bacteria and EPS production. CBD significantly reduced the viability of preformed biofilms at 7.5 µg/mL with an 80 ± 3.1% reduction of metabolic activity. At concentrations above 20 µg/mL, there was almost no bacterial recovery in the CBD-treated preformed biofilms even 48 h after drug withdrawal. Notably, precoating of the culture plate surfaces with CBD prior to incubation with bacteria inhibited biofilm development. Additionally, CBD was found to induce membrane hyperpolarization in S. mutans. Thus, CBD affects multiple processes in S. mutans including its cariogenic properties. In conclusion, we show that CBD has a strong inhibitory effect against cariogenic bacteria, suggesting that it is a potential drug adjuvant for reducing oral pathogenic bacterial load as well as protecting against dental caries.
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- 2022
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22. Emerging powers and the world trading system: The past and future of international economic law
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Mark Feldman
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Law - Published
- 2022
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23. Clinical Laboratory Perspective on Streptococcus halichoeri, an Unusual Nonhemolytic, Lancefield Group B Streptococcus Causing Human Infections
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Jill E. Clarridge, Mark Feldman, Thomas R. Fritsche, Susan E Sharp, Rahul Gill, Mark A. Fisher, E. Susan Slechta, Salika M. Shakir, and Jonathan Salberg
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Microbiology (medical) ,Epidemiology ,030231 tropical medicine ,underlying health conditions ,Infectious and parasitic diseases ,RC109-216 ,medicine.disease_cause ,Group B ,Microbiology ,Agar plate ,03 medical and health sciences ,0302 clinical medicine ,Antibiotic resistance ,Antigen ,RNA, Ribosomal, 16S ,Streptococcal Infections ,medicine ,grey seals ,Humans ,030212 general & internal medicine ,antimicrobial resistance ,Streptococcus halichoeri ,bacteria ,Original Research ,biology ,Zoonotic Infection ,Streptococcus ,16S ribosomal RNA ,biology.organism_classification ,Clinical Laboratory Perspective on Human Infections Caused by Unusual Nonhemolytic Lancefield Group B Streptococcus halichoeri ,zoonoses ,Infectious Diseases ,streptococci ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Synopsis ,Medicine ,Laboratories ,Bacteria - Abstract
Streptococcus halichoeri is a relatively newly identified species of pyogenic streptococci that causes zoonotic infection in humans. S. halichoeri was first described in 2004 as indigenous to seals, and only 8 reports of human S. halichoeri infection have been published. S. halichoeri grows as small, white, nonhemolytic colonies and may be strongly catalase-positive on routine blood agar media, which can lead to isolates being misidentified as coagulase-negative staphylococci. S. halichoeri tests positive for Lancefield group B antigen, like S. agalactiae, but can be identified with matrix-assisted laser desorption/ionization time of flight mass spectrometry or partial 16S rRNA sequencing. We describe 3 cases of S. halichoeri bone and joint infections in patients in the United States with underlying health conditions. In addition, we examine the microbiologic characteristics of S. halichoeri and discuss the importance of fully identifying this organism that might otherwise be disregarded as a skin commensal.
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- 2021
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24. Acute Sterile Meningitis as a Primary Manifestation of Pituitary Apoplexy
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Mark Feldman, Rahul Gill, Gayane Tumyan, and Yogamaya Mantha
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medicine.medical_specialty ,Case Report ,pituitary adenoma ,030209 endocrinology & metabolism ,Adrenocorticotropic hormone ,pituitary tumor ,CSF, cerebrospinal fluid ,Gastroenterology ,Diseases of the endocrine glands. Clinical endocrinology ,03 medical and health sciences ,PA, pituitary apoplexy ,0302 clinical medicine ,Xanthochromia ,Pituitary adenoma ,Internal medicine ,medicine ,sterile meningitis ,pituitary apoplexy ,business.industry ,Pituitary tumors ,Pituitary apoplexy ,General Medicine ,RC648-665 ,medicine.disease ,Prolactin ,CT, computed tomography ,macroadenoma ,030220 oncology & carcinogenesis ,Luteinizing hormone ,business ,MRI, magnetic resonance imaging ,Meningitis - Abstract
Objective We report a case of pituitary apoplexy (PA) with negative radiographic findings for PA and cerebrospinal fluid (CSF) analysis consistent with neutrophilic meningitis. PA is a rare endocrinopathy requiring prompt diagnosis and treatment. Presentation with acute neutrophilic meningitis is uncommon. Methods The diagnostic modalities included pituitary function tests (adrenocorticotropic hormone, thyroid-stimulating hormone, luteinizing hormone, prolactin), brain computed tomography and magnetic resonance imaging (MRI), and CSF analysis. Results A 67-year-old man presented with worsening headache, nausea, and retching. He was somnolent with an overall normal neurologic examination other than a peripheral vision defect in the left eye. MRI showed a pituitary mass bulging into the suprasellar cistern with optic chiasm elevation, consistent with pituitary macroadenoma. Laboratory evaluation revealed decreased levels of adrenocorticotropic hormone, random cortisol, thyroid-stimulating hormone, thyroxine, luteinizing hormone, and testosterone. He had worsening encephalopathy with left eye ptosis and decreased vision, prompting a repeat computed tomography and MRI, showing no interval change in the pituitary adenoma or evidence of bleeding. CSF analysis revealed a leukocyte count of 1106/mm3 (89% neutrophils), a total protein level of 138 mg/dL, red blood cell count of 2040/mm3 without xanthochromia, and glucose level of 130 mg/dL. The CSF culture result was negative. Transsphenoidal resection revealed a necrotic pituitary adenoma with apoplexy. Conclusions Including PA in the differential diagnosis of acute headache is important, particularly in patients with visual disturbances. PA can present with sterile meningitis, mimicking acute bacterial meningitis. While neuroimaging can help detect PA, the diagnosis of PA remains largely clinical.
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- 2021
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25. To sim or not to sim—choosing wisely for procedural skills training in paediatrics
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Ali Al Maawali, Harish Amin, Krista Baerg, Mark Feldman, Fabian Gorodzinksy, Allan Puran, Adam Dubrowski, and Zia Bismilla
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education ,Pediatrics, Perinatology and Child Health ,Original Articles - Abstract
Objectives Simulation is a commonly used modality to teach paediatric procedural skills, however, it is resource intensive. Which paediatric skills are best taught using simulation is not known. This study aims to examine what skills to simulate, allowing for the best use of resources in ever expanding curricula. Method We administered a questionnaire to community and hospitalist general paediatricians in Canada asking them to rate the importance of maintaining competency in each paediatric procedural skill and the frequency with which they perform the skill in their practice. Results Skills that were rated as highly important and also high frequency were: bag-mask ventilation (BMV), lumbar puncture, neonatal cardiopulmonary resuscitation (CPR), specimen procurement for infectious diseases, immunization, and ear curettage. Skills that were rated as highly important but low frequency were: paediatric CPR, intraosseous needle insertion, neonatal intubation, defibrillation, gathering specimens for evidence of child maltreatment, paediatric intubation, cervical spine immobilization, and oral/nasogastric tube placement. Conclusion Paediatric procedural skills are rated variably in terms of importance and frequency of use in general paediatric practice. Eight skills of high importance are infrequently performed and should be targeted for teaching via simulation.
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- 2022
26. To the Question of the Use of Climatic-Oceanological Predictors to Forecast Pacific Salmon Stock Abundance in Kamchatka
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Alexander Bugaev, Mark Feldman, Oleg Tepnin, Svetlana Esenkulova, and Vladimir Radchenko
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- 2022
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27. Hardening COTS Software with Generic Software Wrappers.
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Timothy Fraser, Lee Badger, and Mark Feldman
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- 1999
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28. Masson Tumor in the Left Atrial Appendage Presenting as Cardioembolic Cerebral Infarction
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Mark Feldman, Andrew Assaf, Michinari Hieda, Yogamaya Mantha, Darryl Kawalsky, Uday Tatiraju, and Rakushumimarika Harada
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0301 basic medicine ,medicine.medical_specialty ,cardio-oncology ,cardioembolic disease ,AF, atrial fibrillation ,left atrial appendage ,Infarction ,LAA, left atrial appendage ,030105 genetics & heredity ,LA, left atrium ,multimodality imaging ,03 medical and health sciences ,0302 clinical medicine ,Left middle cerebral artery ,Left atrial ,Internal medicine ,Aphasia ,medicine ,IPEH, intravascular papillary endothelial hyperplasia ,Diseases of the circulatory (Cardiovascular) system ,echocardiography ,Pathological ,Stroke ,Appendage ,TEE, transesophageal echocardiogram ,Masson tumor ,Cerebral infarction ,business.industry ,vascular stasis ,medicine.disease ,stroke ,Mini-Focus Issue: Clinical Cardiology ,RC666-701 ,Cardiology ,cardiovascular system ,Case Report: Clinical Case ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,030217 neurology & neurosurgery - Abstract
A 70-year-old woman presented with aphasia caused by acute infarction in the left middle cerebral artery. Cardiac investigation revealed progressively increasing mobile mass in the left atrial appendage over 2 months (from 9 to 15 mm). Decision was made to proceed with mass resection, and pathological evaluation confirmed Masson tumor. (Level of Difficulty: Advanced.), Graphical abstract
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- 2020
29. Anomalous Origin of a Right Coronary Artery from the Pulmonary Artery in a Middle-Aged Woman
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Mark Feldman, Michinari Hieda, Yogamaya Mantha, Rakushumimarika Harada, Darryl Kawalsky, Andrew Assaf, and David Musselman
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congenital, hereditary, and neonatal diseases and abnormalities ,medicine.medical_specialty ,animal structures ,anomalous origin of right coronary artery from pulmonary artery ,right coronary artery anomalous origin ,education ,TTE, transthoracic echocardiogram ,Case Report ,Clinical Case ,CMR, cardiac magnetic resonance ,LCA, left coronary artery ,Internal medicine ,medicine.artery ,Female patient ,adult congenital heart disease ,Medicine ,echocardiography ,Diseases of the circulatory (Cardiovascular) system ,Systolic ejection murmur ,cardiovascular diseases ,LV, left ventricular ,ALCAPA, anomalous left coronary artery from pulmonary artery ,business.industry ,imaging ,PA, pulmonary artery ,MSCT, multi-slice computed tomography ,Right coronary artery ,RC666-701 ,Pulmonary artery ,Cardiology ,cardiovascular system ,Cardiology and Cardiovascular Medicine ,business ,RCA, right coronary artery ,ARCAPA, anomalous right coronary artery from pulmonary artery - Abstract
A 53-year-old female patient presented for evaluation of a murmur. The examination revealed a 2/6 systolic ejection murmur in the left upper sternal border. Transthoracic echocardiography with color Doppler showed increased blood flow around the apex of the right ventricle. Further imaging revealed the right coronary artery emerging from the pulmonary artery. (Level of Difficulty: Beginner.), Graphical abstract, A 53-year-old woman presented for evaluation of a murmur. The examination revealed a 2/6 systolic ejection murmur in the left upper sternal border…
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- 2020
30. Prolonged Inhibition of
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Mark, Feldman, Walid Shaaban, Moustafa Elsayed, Michael, Friedman, Irith, Gati, Doron, Steinberg, and Hesham, Marei
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It has been confirmed that bacterial biofilm covering dental implants is the main microbial source causing preimplant infectious and inflammatory diseases. The purpose of this study was to evaluate the antibacterial/antibiofilm effect of chlorhexidine, incorporated into a sustained-release varnish of chlorhexidine (SRV-CHX) coating, on dental abutments.Three kinds of dental abutments were used: a high-performance semi-crystalline engineering thermoplastic polyetheretherketone (PEAK) healing abutment, a titanium healing abutment, and a titanium permanent abutment. These abutments were coated with SRV-CHX or SRV-placebo and exposed daily to fresh cultures ofSRV-CHX-coated abutments 2 and 3 were able to inhibitCoating of dental abutments with SRV-CHX demonstrated long-term effective inhibition of
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- 2022
31. Comments on China's Draft Revised Arbitration Law
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Mark Feldman
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- 2022
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32. The AIIB as a Site of Governance
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Mark Feldman
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- 2022
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33. Enterprise Wrappers for Information Assurance.
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Mark Feldman
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- 2003
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34. Mechanism by which immune complexes are deposited in hosts tissue
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Isaac Ginsburg and Mark Feldman
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Pharmacology ,Histones ,Neutrophils ,Immunology ,Humans ,Pharmacology (medical) ,Antigen-Antibody Complex ,Extracellular Traps - Abstract
We offer an explanation how immune complexes are deposited in tissues of auto-immune disorders in humans. These disorders are characterized by the accumulation in tissues of large numbers of neutrophils, which can shed out long extracellular traps (NETs) rich in a nucleosome and in highly opsonic poly cations, histone, LL37, defensins and elastase possessing properties similar to antibodies. These can bind by strong electrostatic forces to negatively charged domains in immune globulins, thus facilitating their deposition and internalization by tissue cells. However, the main cause for tissue damage in auto-immune patients is inflicted by the plethora of toxic pro-inflammatory agents released by activated neutrophils. To ameliorate tissue damage and the cytokine storms, it is recommended to administer to patients highly anionic heparins accompanied by steroids, methotrexate, colchicine, copaxone, and also by additional agents which retarded neutrophil functions.
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- 2021
35. Frequency of metastasis to the gastrointestinal tract determined by endoscopy in a community-based gastroenterology practice
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Donna J. Lager, Rajeev Jain, Pamela Jensen, Mark Feldman, and Vishal Kaila
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medicine.medical_specialty ,Gastrointestinal tract ,medicine.diagnostic_test ,business.industry ,Stomach ,General Medicine ,medicine.disease ,Gastroenterology ,Primary tumor ,Endoscopy ,Metastasis ,medicine.anatomical_structure ,Breast cancer ,Pancreatic cancer ,Internal medicine ,medicine ,Lung cancer ,business - Abstract
Metastasis to the gastrointestinal tract is rare. We performed a retrospective analysis to identify patients with metastatic disease to the gastrointestinal tract using two databases containing pathology results from all endoscopic procedures conducted by nearly 200 gastroenterologists in a community setting over a 14-year period. Forty-nine patients were diagnosed with metastasis to the gastrointestinal tract by endoscopy during the study period. Most were women (71%). The most common metastases to the gastrointestinal tract identified by endoscopy were breast cancers (n = 18), followed by melanomas (n = 12), ovarian cancers (n = 7), kidney cancers (n = 5), prostate cancers (n = 2), lung cancer (n = 1), and pancreatic cancer (n = 1). Three patients had unknown primary sites. Among women, the three leading known primary tumor sites were breast, ovary, and melanoma. Among men, the three leading primary tumor sites were melanoma, kidney, and prostate. The stomach was the most common portion of the gastrointestinal tract involved by metastases. Most affected women and were most frequently encountered in the stomach.
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- 2021
36. Assessing nephrology competence in general paediatrics-A survey of general paediatricians, paediatric nephrologists, residents, and program directors
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Damien Noone, Natasha A. Jawa, Charushree Prasad, Amrit Kirpalani, Justin Jeffers, Mark Feldman, and Adelle Atkinson
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Nephrology ,medicine.medical_specialty ,business.industry ,Internal medicine ,Family medicine ,Pediatrics, Perinatology and Child Health ,medicine ,Original Articles ,business ,Competence (human resources) - Abstract
Objective The objective of this study was to identify nephrology topics of lowest perceived competency and importance for general paediatricians. Methods Surveys were distributed to general paediatricians, paediatric residents, paediatric residency program directors, and paediatric nephrologists. Perceived importance and competence were rated on a 5-point Likert scale. Means and 95% confidence intervals were calculated. Results Mean perceived competency from general paediatricians across all nephrology domains was 3.0, 95%CI (2.9 to 3.1) and mean importance was 3.2, 95%CI (3.1 to 3.3). Domains scoring below the means for competence and importance, respectively were kidney stones (2.5, 95%CI [2.2 to 2.7]) and 2.6, 95%CI [2.3 to 2.8]), acute kidney injury (2.5, 95%CI [2.2 to 2.8] and 2.4, 95%CI [2.1 to 2.8]), chronic kidney disease (1.9, 95%CI [1.7 to 2.2] and 2.1, 95%CI [1.8 to 2.4]), tubular disorders (1.8, 95%CI [1.6 to 2.0] and 2.0, 95%CI [1.8 to 2.3]), and kidney transplant (1.6, 95%CI [1.4 to 1.8] and 1.7, 95%CI [1.4 to 1.9]). Residents, program directors, and paediatric nephrologists agreed that stones, chronic kidney disease, tubular disorders, and transplant were of lower importance. However, acute kidney injury was the domain with the largest discrepancy in perceived importance between residents (4.4, 95%CI [4.2 to 4.6]), nephrologists (4.2, 95%CI [3.8 to 4.6]), and program directors (4.2, 95%CI [3.7 to 4.7]) compared to general paediatricians ([2.4, 95%CI [2.1 to 2.8]; P Conclusion Paediatricians did not believe acute kidney injury was important to their practice, despite expert opinion and evidence of long-term consequences. Educational interventions must address deficits in crucial domains of renal health in paediatrics.
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- 2021
37. Impact of the COVID-19 pandemic on the provision of routine childhood immunizations in Ontario, Canada
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Shaun K. Morris, Daniel S. Farrar, Jeremy N Friedman, Pierre Philippe Piché-Renaud, Mark Feldman, Sharon Burey, Ian Kitai, and Catherine Ji
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Vaccination ,medicine.medical_specialty ,Immunization ,business.industry ,Family medicine ,Health care ,Pandemic ,Medicine ,Vaccine-preventable diseases ,Odds ratio ,business ,Logistic regression ,Personal protective equipment - Abstract
BackgroundThe COVID-19 pandemic has a worldwide impact on all health services, including childhood immunizations. In Canada, there is limited data to quantify and characterize this issue.MethodsWe conducted a descriptive, cross-sectional study by distributing online surveys to physicians across Ontario. The survey included three sections: provider characteristics, impact of COVID-19 on professional practice, and impact of COVID-19 on routine childhood immunization services. Multivariable logistic regression identified factors associated with modification of immunization services.ResultsA total of 475 respondents answered the survey from May 27thto July 3rd2020, including 189 family physicians and 286 pediatricians. The median proportion of in-person visits reported by physicians before the pandemic was 99% and dropped to 18% during the first wave of the pandemic in Ontario. In total, 175 (44.6%) of the 392 respondents who usually provide vaccination to children acknowledged a negative impact caused by the pandemic on their immunization services, ranging from temporary closure of their practice (n=18; 4.6%) to postponement of vaccines in certain age groups (n=103; 26.3%). Pediatricians were more likely to experience a negative impact on their immunization services compared to family physicians (adjusted odds ratio [aOR]=2.64, 95% CI: 1.48-4.68), as well as early career physicians compared to their more senior colleagues (aOR=2.69, 95% CI: 1.30-5.56), whereas physicians from suburban settings were less impacted than physicians from urban settings (aOR=0.62, 95% CI: 0.39-0.99). The most frequently identified barriers to immunizations during the pandemic were parental concerns around COVID-19 (n=305; 77.8%), lack of personal protective equipment (PPE; n=123; 31.3%) and healthcare workers’ concerns of contracting COVID-19 (n=105; 26.8%).ConclusionsCOVID-19 has caused substantial modifications to pediatric immunization services across Ontario. Strategies to mitigate barriers to immunizations during the pandemic need to be implemented in order to avoid immunity gaps that could lead to an increase in vaccine preventable diseases.HIGHLIGHTSWe have conducted a descriptive, cross-sectional study by distributing online surveys to pediatricians and family physicians across Ontario to assess the impact of the COVID-19 pandemic on their immunization practices.The COVID-19 pandemic has caused a substantial decrease in in-person visits and a related disruption to routine childhood immunization services during the first wave of the pandemic.The main barriers to immunizations during the pandemic included parents’ and healthcare providers’ concerns of contracting COVID-19, and lack of appropriate personal protective equipment (PPE).Solutions to maintain childhood immunizations during the pandemic included assistance in providing PPE to clinical practices, dedicated centers for vaccination, and parental education.
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- 2021
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38. Anandamide alters the membrane properties, halts the cell division and prevents drug efflux in multidrug resistant Staphylococcus aureus
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Raphael Mechoulam, Reem Smoum, Mark Feldman, Ronit Vogt Sionov, Shreya Banerjee, and Doron Steinberg
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0301 basic medicine ,Staphylococcus aureus ,Polyunsaturated Alkamides ,medicine.drug_class ,Science ,030106 microbiology ,Antibiotics ,Arachidonic Acids ,medicine.disease_cause ,Microbiology ,Article ,03 medical and health sciences ,chemistry.chemical_compound ,Medical research ,Drug Resistance, Multiple, Bacterial ,medicine ,DAPI ,Multidisciplinary ,Cell Membrane ,Anandamide ,Anti-Bacterial Agents ,Multiple drug resistance ,030104 developmental biology ,Mechanism of action ,chemistry ,Medicine ,lipids (amino acids, peptides, and proteins) ,Efflux ,medicine.symptom ,Intracellular ,Endocannabinoids - Abstract
Antibiotic resistance is a serious public health problem throughout the world. Overcoming methicillin and multidrug-resistant Staphylococcus aureus (MRSA/MDRSA) infections has become a challenge and there is an urgent need for new therapeutic approaches. We have previously demonstrated that the endocannabinoid Anandamide (AEA) can sensitize MRSA to antibiotics. Here we have studied the mechanism of action using a MDRSA clinical isolate that are sensitized by AEA to methicillin and norfloxacin. We found that AEA treatment halts the growth of both antibiotic-sensitive and antibiotic-resistant S. aureus. The AEA-treated bacteria become elongated and the membranes become ruffled with many protrusions. AEA treatment also leads to an increase in the percentage of bacteria having a complete septum, suggesting that the cell division is halted at this stage. The latter is supported by cell cycle analysis that shows an accumulation of bacteria in the G2/M phase after AEA treatment. We further observed that AEA causes a dose-dependent membrane depolarization that is partly relieved upon time. Nile red staining of the bacterial membranes indicates that AEA alters the membrane structures. Importantly, 4′-6-diamidino-2-phenylindole (DAPI) accumulation assay and ethidium bromide efflux (EtBr) assay unveiled that AEA leads to a dose-dependent drug accumulation by inhibiting drug efflux. In conclusion, our study demonstrates that AEA interferes with cell division, alters the membrane properties of MDRSA, and leads to increased intracellular drug retention, which can contribute to the sensitization of MDRSA to antibiotics.
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- 2021
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39. Sustained release varnish containing chlorhexidine for prevention of Streptococcus mutans biofilm formation on voice prosthesis surface: an in vitro study
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Irith Gati, Michael Friedman, Ronit Vogt Sionov, Fadi Ashqar, Menachem Gross, Doron Steinberg, Ron Eliashar, Mark Feldman, Danielle Duanis-Assaf, and Batya Zaks
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Microbiology (medical) ,biology ,Chemistry ,Chlorhexidine ,Biofilm ,macromolecular substances ,Bacterial growth ,biology.organism_classification ,Microbiology ,Streptococcus mutans ,Staining ,chemistry.chemical_compound ,In vivo ,Biofilms ,Delayed-Action Preparations ,medicine ,Crystal violet ,Larynx, Artificial ,Bacteria ,medicine.drug - Abstract
In this study, we aimed to develop a novel, sustained release varnish (SRV) for voice prostheses (VP) releasing chlorhexidine (CHX), for the prevention of biofilm formation caused by the common oral bacteria Streptococcus mutans on VP surfaces. This study was performed in an in vitro model as a step towards future in vivo trials. VPs were coated with a SRV containing CHX (SRV-CHX) or SRV alone (placebo-SRV) that were daily exposed to S. mutans. The polymeric materials of SRV were composed of ethylcellulose and PEG-400. Biofilm formation was assessed by DNA quantification (qPCR), crystal violet staining, confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and kinetics experiments. The amount of DNA in the biofilms formed by S. mutans on VP surfaces coated once with SRV-CHX (1.024 ± 0.218 ng DNA/piece) was 58.5 ± 8.8% lower than that of placebo-SRV-coated VPs (2.465 ± 0.198 ng DNA/piece) after a 48-h exposure to S. mutans (p = 0.038). Reduced biofilm mass on SRV-CHX-coated VPs was visually confirmed by CLSM and SEM. CV staining of SRV-CHX single-coated VPs that have been exposed to S. mutans nine times showed a 98.1 ± 0.2% reduction in biofilm mass compared to placebo-SRV-coated VPs (p = 0.003). Kinetic experiments revealed that SRV-CHX triple-coated VPs could delay bacterial growth for 23 days. Coating VPs with SRV-CHX has an inhibitory effect on biofilm formation and prevents bacterial growth in their vicinities. This study is a proof-of-principle that paves the way for developing new clinical means for reducing both VPs’ bacterial biofilm formation and device failure.
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- 2021
40. A Pacific Rim Consensus on International Investment Law
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Mark Feldman
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International investment ,Pacific Rim ,Political science ,Law ,Commercial law - Abstract
Remarks delivered as international public lecture organized by the Transnational Business Law Department of the Faculty of Law, Universitas Padjadjaran.
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- 2021
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41. A Free Trade Area of the Asia-Pacific for the Asian Century
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Mark Feldman
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- 2021
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42. The role of neutrofiles and by macrophages in the pathogenesis of inflammatory and I post inflammatory episodes : Major tissue damage may be inflicted by a synergy among their toxic pro inflammatory agents
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Isaac Ginsburg and Mark Feldman
- Abstract
In his manuscript we summarize the role played by the variety of pro inflammatory agents generated by neutrofiles and by macrophages and how these cells may act in synergy to injure human and tissues in various inflammatory and in post inflammatory conditions. Screening the vast published literature, we found that most of papers published on inflammation, tend to stress only the role played by a very few pro inflammatory agents as key agents in inflammation. This is unreasonable to try to understand how leukocytes kill microbial cells and injure mammalian cells in various medical conditions. This is since the PMNs and macrophages produce numerous inflammatory agents.
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- 2021
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43. Recrudescence of severe polyneuropathy after receiving Pfizer-BioNTech COVID-19 vaccine in a patient with a history of eosinophilic granulomatosis with polyangiitis
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Rahul, Gill, Macym, Rizvi, Muhammad S, Sadiq, and Mark, Feldman
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Male ,Polyneuropathies ,Vaccines, Synthetic ,COVID-19 Vaccines ,Granulomatosis with Polyangiitis ,COVID-19 ,Humans ,mRNA Vaccines ,General Medicine ,Churg-Strauss Syndrome ,Middle Aged ,Neoplasm Recurrence, Local ,BNT162 Vaccine - Abstract
A middle age man with a history of diabetes mellitus type 2, hypertension, migraine and eosinophilic granulomatosis with polyangiitis (EGPA) with polyneuropathy in remission presented with paresthesia and motor weakness soon after receiving the Pfizer-BioNTech COVID-19 messanger RNA (mRNA) vaccine. The patient had polyneuropathy 10 years ago secondary to EGPA, which had resolved. EGPA was diagnosed on the basis of typical symptoms and positive sural nerve biopsy. Five days after receiving the first dose of COVID-19 vaccine, he developed heaviness and reduced dexterity of both the upper extremities, which progressed to patchy and asymmetric motor weakness of all four extremities. Given the lack of clear alternative explanation after a thorough work up, recrudescence of underlying asymptomatic polyneuropathy due to a possible reaction to COVID-19 mRNA vaccine was considered although a temporal association with vaccine dose does not prove causality. He was treated with corticosteroids with slow improvement of his symptoms.
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- 2022
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44. Abstract 14683: Central Nervous System Mediated Cardiac Bradyarrhythmia With Asystole That Required Permanent Pacemaker in a Young Woman With Anti- NMDAR Encephalitis
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Uday Tatiraju, Mark Feldman, Yogamaya Mantha, Azeen Anjum, Macym Rizvi, and Anita G Holtz
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medicine.medical_specialty ,business.industry ,Central nervous system ,Anti-NMDAR Encephalitis ,medicine.disease ,Acute Psychosis ,Autonomic nervous system ,Electrophysiology ,medicine.anatomical_structure ,Physiology (medical) ,Internal medicine ,medicine ,Cardiology ,Permanent pacemaker ,Asystole ,Cardiology and Cardiovascular Medicine ,business ,Encephalitis - Abstract
Background: We report a young woman who presented with acute psychosis and autonomic dysfunction who was diagnosed with Anti-N-Methyl-D-Aspartate Receptor Encephalitis (anti-NMDARE). Her life-threatening autonomic instability was controlled only after the placement of a permanent cardiac pacemaker. Case Presentation: A 29-year-old woman presented with abnormal movements and depersonalization. Vital signs showed BP 132/94 mmHg, HR 110 beats/min, RR 26 cycles/min, temperature of 101 F and spO2 of 80 % on RA. She was emergently intubated. Laboratory evaluation showed elevated CRP 6.98 mg/dL and CK 3329 U/L. Brain MRI revealed an abnormality in the right amygdala and hippocampus. Infectious workup was negative; however, a high titer of CSF NMDAR antibody was present. CT abdomen and pelvis revealed a 1.1 cm cyst within the left ovary. With a diagnosis of anti-NMDARE, she was treated with plasmapheresis, methylprednisolone, and immunoglobulin G therapy and underwent bilateral salpingo-oophorectomy with pathology confirming a teratoma. Despite these treatments, she continued to display autonomic dysfunction. Telemetry showed tachycardia-bradycardia with asystole that remained refractory to treatment and required placement of a permanent pacemaker (PPM). She showed clinical improvement after PPM and treatment ( Figure ). Conclusion: This is a rare case of severe bradyarrhythmia in anti NMDARE that necessitated placement of a permanent cardiac pacemaker. Neural-mapping studies show that the amygdala and hippocampus strongly modulate autonomic control. Disruption of cortical circuitry related to autonomic tone likely lead to arrhythmias in our case. Class I indications for pacemakers in the ICU include asystole, symptomatic bradycardia with hypotension and/or unresponsive to atropine. Early recognition, cardiorespiratory support, multistep pharmacological care and sometimes early electrophysiological support in anti-NMDARE are paramount.
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- 2020
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45. Impact of the COVID-19 pandemic on the provision of routine childhood immunizations in Ontario, Canada
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Pierre-Philippe Piché-Renaud, Catherine Ji, Daniel S. Farrar, Jeremy N. Friedman, Michelle Science, Ian Kitai, Sharon Burey, Mark Feldman, and Shaun K. Morris
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medicine.medical_specialty ,Cross-sectional study ,030231 tropical medicine ,Logistic regression ,03 medical and health sciences ,0302 clinical medicine ,Pandemic ,Medicine ,Humans ,030212 general & internal medicine ,Child ,Personal protective equipment ,Pandemics ,Ontario ,General Veterinary ,General Immunology and Microbiology ,business.industry ,SARS-CoV-2 ,Vaccination ,Public Health, Environmental and Occupational Health ,COVID-19 ,Odds ratio ,Infectious Diseases ,Cross-Sectional Studies ,Immunization ,Family medicine ,Molecular Medicine ,Vaccine-preventable diseases ,business - Abstract
Background The COVID-19 pandemic has a worldwide impact on all health services, including childhood immunizations. In Canada, there is limited data to quantify and characterize this issue. Methods We conducted a descriptive, cross-sectional study by distributing online surveys to physicians across Ontario. The survey included three sections: provider characteristics, impact of COVID-19 on professional practice, and impact of COVID-19 on routine childhood immunization services. Multivariable logistic regression identified factors associated with modification of immunization services. Results A total of 475 respondents answered the survey from May 27th to July 3rd 2020, including 189 family physicians and 286 pediatricians. The median proportion of in-person visits reported by physicians before the pandemic was 99% and dropped to 18% during the first wave of the pandemic in Ontario. In total, 175 (44.6%) of the 392 respondents who usually provide vaccination to children acknowledged a negative impact caused by the pandemic on their immunization services, ranging from temporary closure of their practice (n = 18; 4.6%) to postponement of vaccines in certain age groups (n = 103; 26.3%). Pediatricians were more likely to experience a negative impact on their immunization services compared to family physicians (adjusted odds ratio [aOR] = 2.64, 95% CI: 1.48–4.68), as well as early career physicians compared to their more senior colleagues (aOR = 2.69, 95% CI: 1.30–5.56), whereas physicians from suburban settings were less impacted than physicians from urban settings (aOR = 0.62, 95% CI: 0.39–0.99). Some of the proposed solutions to decreased immunization services included assistance in accessing personal protective equipment, dedicated centers or practices for vaccination, universal centralized electronic immunization records and education campaigns for parents. Conclusions COVID-19 has caused substantial modifications to pediatric immunization services across Ontario. Strategies to mitigate barriers to immunizations during the pandemic need to be implemented in order to avoid immunity gaps that could lead to an eventual increase in vaccine preventable diseases.
- Published
- 2020
46. Predicting Liver Fibrosis in the Hepatitis C Population: Concordance Analysis Between Noninvasive Scoring Systems and Percutaneous Liver Biopsy
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Maureen Moore, Mohammed J. Alam, Matthew E Malus, Sharon Adley, Daniel Alexander Saldaña Koppel, Pradeep Kumar Mada, and Mark Feldman
- Subjects
medicine.medical_specialty ,Cirrhosis ,aspartate aminotransferase-to-platelet ratio index (apri score) ,Population ,Infectious Disease ,030204 cardiovascular system & hematology ,Gastroenterology ,fibrosis-4 (fib-4) score ,03 medical and health sciences ,aspartate aminotransferase-to-alanine aminotransferase ratio (aar) ,0302 clinical medicine ,Internal medicine ,medicine ,Internal Medicine ,hepatitis c ,education ,liver biopsy ,Hepatitis ,education.field_of_study ,Receiver operating characteristic ,medicine.diagnostic_test ,business.industry ,General Engineering ,Hepatitis C ,medicine.disease ,Liver biopsy ,Viral hepatitis ,Hepatic fibrosis ,business ,030217 neurology & neurosurgery - Abstract
Background Due to the slow progression of many chronic liver diseases, including hepatitis C, it is not practical or safe to monitor disease progression by serial liver biopsies. Noninvasive laboratory scoring systems based on routine laboratory tests are appealing surrogate markers of liver fibrosis for the staging and monitoring of chronic liver diseases such as hepatitis C. Methods We explored the accuracy of three scoring systems: the fibrosis-4 score (FIB-4), the aspartate aminotransferase to platelet ratio index (APRI score), and the aspartate aminotransferase to alanine aminotransferase ratio (AAR) in 496 patients with chronic hepatitis C virus (HCV) infection who had undergone percutaneous liver biopsy at a viral hepatitis clinic in Shreveport, Louisiana. Results For FIB-4, the area under the receiver operating characteristic curve (AUROC) for hepatic fibrosis stages ≥ 1, ≥ 2, ≥ 3, and 4 (cirrhosis) ranged from 0.74 (95% CI, 0.678 - 0.802) to 0.802 (95% CI, 0.751 - 0.854). At a cutoff value of 1.45, FIB-4 was 82% sensitive for advanced fibrosis or cirrhosis (stage 3 or 4) but was only 58% specific for these findings. Increasing the FIB-4 cutoff value to 3.25 reduced the sensitivity for detecting advanced fibrosis or cirrhosis to 39%, but this higher cutoff was 92% specific for these findings. Corresponding AUROCs for the APRI and AAR scores were inferior to FIB-4. Conclusion The FIB-4 index outperformed APRI and AAR in our HCV infected population in predicting severe fibrosis or cirrhosis.
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- 2020
47. Anandamide prevents the adhesion of filamentous Candida albicans to cervical epithelial cells
- Author
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Ronit Vogt Sionov, Mark Feldman, Raphael Mechoulam, Doron Steinberg, and Reem Smoum
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0301 basic medicine ,Hyphal growth ,Hypha ,Polyunsaturated Alkamides ,Morphogenesis ,Hyphae ,lcsh:Medicine ,Arachidonic Acids ,Cervix Uteri ,Article ,Epithelium ,Microbiology ,Fungal Proteins ,03 medical and health sciences ,0302 clinical medicine ,Cell Line, Tumor ,Gene Expression Regulation, Fungal ,Candida albicans ,medicine ,Cell Adhesion ,Humans ,lcsh:Science ,Multidisciplinary ,biology ,Chemistry ,Antimicrobials ,lcsh:R ,fungi ,Biofilm ,Fungi ,Candidiasis ,Epithelial Cells ,biology.organism_classification ,Bacterial adhesin ,Experimental models of disease ,030104 developmental biology ,medicine.anatomical_structure ,Cell culture ,Biofilms ,lcsh:Q ,lipids (amino acids, peptides, and proteins) ,Female ,030217 neurology & neurosurgery ,Endocannabinoids ,HeLa Cells ,Transcription Factors - Abstract
Candidiasis is a fungal infection caused by Candida species that have formed a biofilm on epithelial linings of the body. The most frequently affected areas include the vagina, oral cavity and the intestine. In severe cases, the fungi penetrate the epithelium and cause systemic infections. One approach to combat candidiasis is to prevent the adhesion of the fungal hyphae to the epithelium. Here we demonstrate that the endocannabinoid anandamide (AEA) and the endocannabinoid-like N-arachidonoyl serine (AraS) strongly prevent the adherence of C. albicans hyphae to cervical epithelial cells, while the endocannabinoid 2-arachidonoylglycerol (2-AG) has only a minor inhibitory effect. In addition, we observed that both AEA and AraS prevent the yeast-hypha transition and perturb hyphal growth. Real-time PCR analysis showed that AEA represses the expression of the HWP1 and ALS3 adhesins involved in Candida adhesion to epithelial cells and the HGC1, RAS1, EFG1 and ZAP1 regulators of hyphal morphogenesis and cell adherence. On the other hand, AEA increased the expression of NRG1, a transcriptional repressor of filamentous growth. Altogether, our data show that AEA and AraS have potential anti-fungal activities by inhibiting hyphal growth and preventing hyphal adherence to epithelial cells.
- Published
- 2020
48. A Novel Hypothetical Approach to Explain the Mechanisms of Pathogenicity of Rheumatic Arthritis
- Author
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Isaac Ginsburg and Mark Feldman
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Cartilage ,Autoantibody ,ROS ,Neutrophil extracellular traps ,Diseases of the musculoskeletal system ,RNS ,Phospholipase ,Endocytosis ,medicine.disease ,Short Review ,Cell biology ,chemistry.chemical_compound ,medicine.anatomical_structure ,Rheumatology ,chemistry ,Synovial Cell ,RC925-935 ,Rheumatoid arthritis ,medicine ,Colchicine ,proteinase ,fibrinolysis ,phospholipase ,heparinoid - Abstract
The autoimmune disorder rheumatoid arthritis (RA) is a relapsing and chronic inflammatory disease that affects the synovial cells, cartilage, bone, and muscle. It is characterised by the accumulation of huge numbers of polymorphonuclear neutrophils (PMNs) and macrophages in the synovia. Auto-antibodies are deposited in the joint via the activity of highly cationic histones released from neutrophil extracellular traps (NETs) in a phenomenon termed NETosis. The cationic histones function as opsonic agents that bind to negatively charged domains in autoantibodies and complement compounds via strong electrostatic forces, facilitating their deposition and endocytosis by synovial cells. However, eventually the main cause of tissue damage is the plethora of toxic pro-inflammatory substances released by activated neutrophils recruited by cytokines. Tissue damage in RA can also be accompanied by infections which, upon bacteriolysis, release cell-wall components that are toxic to tissues. Some amelioration of the damaged cells and tissues in RA may be achieved by the use of highly anionic heparins, which can neutralize cationic histone activity, provided that these polyanions are co-administrated with anti-inflammatory drugs such as steroids, colchicine, or methotrexate, low molecular weight antioxidants, proteinase inhibitors, and phospholipase A2 inhibitors.
- Published
- 2020
49. The Combination of Tocilizumab and Methylprednisolone Along With Initial Lung Recruitment Strategy in Coronavirus Disease 2019 Patients Requiring Mechanical Ventilation: A Series of 21 Consecutive Cases
- Author
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Lyndsay Sheperd, Kenney D. Weinmeister, Mark Feldman, Andrew C. Faust, Allison M. Liddell, Munir E. Hazbun, Gary L. Weinstein, Anthony L. Ortegon, and Rebecca L. Doebele
- Subjects
medicine.medical_treatment ,Single-Center Quality Improvement Report ,viral pneumonia ,Artificial respiration ,medicine.disease_cause ,Plateau pressure ,chemistry.chemical_compound ,coronavirus disease 2019 ,Tocilizumab ,Medicine ,Intubation ,artificial respiration ,Coronavirus ,Mechanical ventilation ,glucocorticoids ,business.industry ,cytokine release syndrome ,General Medicine ,medicine.disease ,respiratory distress syndrome ,Methylprednisolone ,chemistry ,Anesthesia ,Viral pneumonia ,business ,medicine.drug - Abstract
Objective: To describe the outcomes with use of a combination of tocilizumab and methylprednisolone administered around the time of endotracheal intubation in patients with confirmed coronavirus disease 2019-associated hypoxemic respiratory failure requiring mechanical ventilation. Data Sources: Retrospective chart review. Study Selection/Data Extraction: Twenty-one consecutive patients with confirmed coronavirus disease 2019-associated hypoxemic respiratory failure requiring mechanical ventilation. Initial ventilator parameters were positive end-expiratory pressure 14 cm H2o and target plateau pressure 29 cm H2o to maximize lung recruitment. Methylprednisolone (125 mg every 6hr for 24 hr with tapering to 60 mg every 12 hr) was administered shortly after patients were intubated (median 11 hr after intubation). Data Synthesis: No patient in the cohort died while hospitalized (mortality, 0%; 95% CI, 0%–18%) and 18 patients have been discharged from the acute care setting. Twenty of 21 patients (95%) have been liberated from mechanical ventilation after a median duration of 8 days (range, 4–30 d). Following 48 hours of methylprednisolone, the A-a o2 gradient decreased from 455 ± 103 to 228 ± 109 mm Hg (difference 227 ± 108 mm Hg; p < 0.01). Conclusions: Our positive experience with tocilizumab in combination with methylprednisolone started early after endotracheal intubation may be one avenue for reducing the morbidity and mortality seen with severe coronavirus disease 2019 and merits further exploration in clinical studies.
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- 2020
50. A novel aspect may explain the mechanisms of pathogenicity of rheumatic fever, a multifactorial, autoimmune, infectious and inflammatory disorder which 'licks the joints and bites the heart': A working hypothesis
- Author
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Mark Feldman and Isaac Ginsburg
- Subjects
0301 basic medicine ,Streptococcus pyogenes ,Endocytosis ,Communicable Diseases ,Macrophage chemotaxis ,Pathogenesis ,03 medical and health sciences ,0302 clinical medicine ,Immune system ,medicine ,Humans ,Cell damage ,Opsonin ,biology ,Virulence ,Chemistry ,Rheumatic Heart Disease ,General Medicine ,medicine.disease ,Heart Valves ,030104 developmental biology ,Immunology ,biology.protein ,Rheumatic fever ,Antibody ,Rheumatic Fever ,030217 neurology & neurosurgery - Abstract
A novel hypothesis is presented to explain the pathogenesis of the multifactorial autoimmune disorder rheumatic fever (RF). It involves a synergistic interaction among streptococcal toxins, their cell wall components, M protein, immune complexes, complement components, cationic histones. These agents can act with cationic histones released by neutrophils during NETosis and bacteriolysis and can function as opsonic agents possessing properties similar to antibodies. Cationic histones can interact by strong electrostatic forces with negatively- charged domains on immune complexes and complement components. This allows their deposition and endocytosis in the myocardium, the heart valves, and in the joints. However, the main cause of cell and tissue damage observed in RF is due to a synergism among the plethora of pro-inflammatory substances released by activated neutrophils and macrophages. Cell damage may be mitigated to some extent by anionic heparins, heparinoids, and by anti-inflammatory drugs such as corticosteroids which counteract neutrophils and macrophage chemotaxis induced by cytokines.
- Published
- 2020
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