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Blood transfusion services maintain quality practice through adherence to guidelines but are faced with blood component wastage due to multiple factors. One factor, in particular, is poor ordering and utilization practices followed by physicians who may not be familiar with the indications and the optimal conditions for the handling of blood products. This study evaluates whether an educational intervention would help reduce ordering of plasma and improve wastage rates after thawing. The study followed a quasi-experimental pre-test post-test design. A multifaceted educational intervention was introduced at a tertiary hospital-based combining predisposing, enabling, and reinforcing activities, based on the literature of effective continuous professional development. The activities included a brief survey to evaluate participant knowledge about indications of plasma and its storage condition, a lecture, and periodic reports and reminders sent to all department heads in the hospital. Respondents to the survey and lecture attendees included physicians in adult critical care and anesthesia departments. Monthly plasma utilization and wastage rates were compared before and after introducing the intervention. Sixty physicians participated in the survey. The questions were answered correctly by less than half. After introducing the intervention, monthly plasma transfusion rates decreased; however, wastage rates did not improve. There is a knowledge gap among physicians who order plasma. The educational intervention resulted in lower plasma transfusion rates but did not affect wastage rates. Future interventions would benefit from including physicians in other departments as well as nurses.

aiman M Bayuomi,3 Talal Qadah11Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia; 2Hematology Department, King Salman Bin Abdulaziz Medical City, Medinah, Saudi Arabia; 3Blood Transfusion Services Unit, King Abdulaziz University Hospital, Jeddah, Saudi Arabia; 4Clinical Chemistry Laboratory, King Abdulaziz University Hospital, Jeddah, Saudi Arabia Correspondence: Nora Y Hakami, Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, 21589, Saudi Arabia, Email [email protected] Background: Platelets are a commonly used blood component to prevent or treat bleeding in patients with thrombocytopenia or platelet dysfunction. They are stored at room temperature (22– 24°C) for five days unless specific measures are taken to extend the shelf life to seven days or more. After five days, this study evaluated platelet units' biochemical changes and bacterial growth. Study Design and Methods: Platelet concentrate was collected from 30 random donors: 8 females and 22 males. The collected samples were then placed on an agitator at room temperature and tested for their pH, protein content, and glucose levels using Roche Combur 100 Test® Strips. The Haemonetics eBDS™ System was used for bacterial detection. The measurements were taken on day five as the control and then repeated on days 7, 9, and 11 to observe any changes. On days 5 and 7, all parameters remained unchanged. However, glucose levels significantly changed (p=< 0.0001) on days 9 and 11. Regarding pH, a significant change was observed on day 9 (p=0.033) and day 11 (p=0.0002). Results: There were no significant changes in all parameters on days 5 and 7. However, glucose was substantially changed (p=< 0.0001) on days 9 and 11. For pH, there was a significant change in pH on day 9 (p=0.033) and day 11 (p=0.0002). Discussions: Our study found that platelet concentrate extension is possible for up to seven days. However, further studies are needed to evaluate platelet function during expiry time and to assess the stability of platelet morphology and function. [ABSTRACT FROM AUTHOR]

Blood transfusion services maintain quality practice through adherence to guidelines but are faced with blood component wastage due to multiple factors. One factor, in particular, is poor ordering and utilization practices followed by physicians who may not be familiar with the indications and the optimal conditions for the handling of blood products. This study evaluates whether an educational intervention would help reduce ordering of plasma and improve wastage rates after thawing. The study followed a quasi-experimental pre-test post-test design. A multifaceted educational intervention was introduced at a tertiary hospital-based combining predisposing, enabling, and reinforcing activities, based on the literature of effective continuous professional development. The activities included a brief survey to evaluate participant knowledge about indications of plasma and its storage condition, a lecture, and periodic reports and reminders sent to all department heads in the hospital. Respondents to the survey and lecture attendees included physicians in adult critical care and anesthesia departments. Monthly plasma utilization and wastage rates were compared before and after introducing the intervention. Sixty physicians participated in the survey. The questions were answered correctly by less than half. After introducing the intervention, monthly plasma transfusion rates decreased; however, wastage rates did not improve. There is a knowledge gap among physicians who order plasma. The educational intervention resulted in lower plasma transfusion rates but did not affect wastage rates. Future interventions would benefit from including physicians in other departments as well as nurses. [ABSTRACT FROM AUTHOR]

Aims:The purpose of this study was to identify the cephalometric features of bimaxillary protrusion in adolescents. Materials and Methods: Ninty four students were selected aged (12-15) years from secondary schools in Mosul City.Fourty four with class I biprotrusion which were chosen to have an inte-rincisal angle less than 110o, and 50 with class I normal occlusion. Astandardized lateral cephalometric radiograph was taken for each student, sixteen variables, (9 angular and 7 linear) were used in this study. Results: Significant differences were seen in the majority of the linear and angular measure-ments used in this study, the total anterior facial height, lower anterior facial height, upper anterior den-tal height , lower anterior dental height, the angle defines the anteroposterior position of maxilla in re-lation to anterior cranial base, the angle indicates the anteroposterior position of the mandible in rela-tion to the anterior cranial base, mandibular plane angle, palatomandibular plane angle, gonial angle, the angulation of upper central incisor to anterior cranial base and the angulation of lower central inci-sor to mandibular plane were significantly higher in bimaxillary protrusion than normal occlusion in both sexes and total sample.No significant differences were seen in other measurements : upper ante-rior facial height, posterior facial height, ramus height and the angle of palatal plane inclination in rela-tion to anterior cranial base.Interincisal angle was significantly smaller in bimaxillary protrusion than normal occlusion. Conclusions: Most of the anterior facial measurements were significantly higher in bimaxillary protrusion than normal occlusion if compared to posterior facial height and ramus height due to the downward and backward rotation of the mandible in bimaxillary protrusion.

Aims: . To investigate the rates of space closure achieved by elastomeric chain and nickel titanium coil springs with the evaluation of the effects of using different bracket types on the rate of space closure during its retraction along different sizes of orthodontic arch wires using typodont simulation system (Ormco). Materials and Methods: The standardization criteria were all typodont teeth situated in well aligned position, covered and immobilized by the acrylic bite except canine, elastic chain and nickel – titanium closed coil spring exerting 180 gm of force on canine measured carefully by tension gauge. The available space was 13.5mm (the rate of space closure). Results: The present study showed that when using elastic chain as a method of canine retraction gave rise to a a significant decrease in the rate of space closure as compared with nickel – titanium closed coil spring also sliding the canine using ceramic brackets gave rise significant reduction in the rate of space closure than when using stainless steel brackets. Another finding of the present study showed that sliding the canine on large rectangular arch wire (0.019x0.025 inch) gave rise to a significant reduction in the rate of space closure when com-pared with 0.018 inch and 0.018x0.022 inch arch wires were used. Conclusions: It was concluded that the canine retraction with 0.018 inch wire on Roth stainless steel bracket by closed coil spring gave rise a large amount of space closure rate. While the opposite is true for canine retraction with 0.019x0.025 inch wire on standard ceramic bracket by elastic chain retraction method.

Objectives: The study aimed to explore the spectrum and trend of causative microbial agents and to identify management challenges and the risk factors for poor outcomes in patients with confirmed otogenic skull base osteomyelitis., Methods: A retrospective observational study was conducted at a tertiary-care academic center from 1999 through 2019 and included 28 adult patients with confirmed otogenic skull base osteomyelitis. Relevant data was extracted from electronic and hard patient medical files. The microbial spectrum of involved microbes was identified and correlated to management options. Deterioration risk factors were investigated using suitable statistical analysis tests., Results: Twenty-eight patients with confirmed skull base osteomyelitis were included; most were males (78.6%) and Saudis (78.6%). All patients were ≥50 years of age (mean ± SD is 69.0±10.2.4). Of 41 identified microbial isolates, 56% were bacterial, 44% were fungal. 32.1% of patients had polymicrobial infections, most patients (92.8%) had received ≥2 systemic antibiotics, 57.1% received systemic antibiotic combinations, and 32.1% underwent surgical interventions. The mean antibiotic and antifungal therapy duration was 58.3 and 45.8 days, respectively. The identified risk factors of deterioration were advanced age and concomitant cardiac failure, with P-values of .006 and .034, respectively., Conclusions: The study findings highlight the microbiological spectrum and trend of otogenic skull base osteomyelitis-causative microbes over two decades, present the management challenges, identify deterioration risk factors, and suggest tissue biopsy as the golden standard for accurately identifying causative microbes., Competing Interests: Competing interests: There are no conflicts of competing interest to be disclosed regarding this paper.

Electro/Magneto-EncephaloGraphy (EEG/MEG) source imaging (EMSI) of epileptic activity from deep generators is often challenging due to the higher sensitivity of EEG/MEG to superficial regions and to the spatial configuration of subcortical structures. We previously demonstrated the ability of the coherent Maximum Entropy on the Mean (cMEM) method to accurately localize the superficial cortical generators and their spatial extent. Here, we propose a depth-weighted adaptation of cMEM to localize deep generators more accurately. These methods were evaluated using realistic MEG/high-density EEG (HD-EEG) simulations of epileptic activity and actual MEG/HD-EEG recordings from patients with focal epilepsy. We incorporated depth-weighting within the MEM framework to compensate for its preference for superficial generators. We also included a mesh of both hippocampi, as an additional deep structure in the source model. We generated 5400 realistic simulations of interictal epileptic discharges for MEG and HD-EEG involving a wide range of spatial extents and signal-to-noise ratio (SNR) levels, before investigating EMSI on clinical HD-EEG in 16 patients and MEG in 14 patients. Clinical interictal epileptic discharges were marked by visual inspection. We applied three EMSI methods: cMEM, depth-weighted cMEM and depth-weighted minimum norm estimate (MNE). The ground truth was defined as the true simulated generator or as a drawn region based on clinical information available for patients. For deep sources, depth-weighted cMEM improved the localization when compared to cMEM and depth-weighted MNE, whereas depth-weighted cMEM did not deteriorate localization accuracy for superficial regions. For patients' data, we observed improvement in localization for deep sources, especially for the patients with mesial temporal epilepsy, for which cMEM failed to reconstruct the initial generator in the hippocampus. Depth weighting was more crucial for MEG (gradiometers) than for HD-EEG. Similar findings were found when considering depth weighting for the wavelet extension of MEM. In conclusion, depth-weighted cMEM improved the localization of deep sources without or with minimal deterioration of the localization of the superficial sources. This was demonstrated using extensive simulations with MEG and HD-EEG and clinical MEG and HD-EEG for epilepsy patients., (© 2024 The Author(s). Human Brain Mapping published by Wiley Periodicals LLC.)

Objective: The use of electrical source imaging (ESI) in assessing the source of interictal epileptic discharges (IEDs) is gaining increasing popularity in presurgical work-up of patients with drug-resistant focal epilepsy. While vigilance affects the ability to locate IEDs and identify the epileptogenic zone, we know little about its impact on ESI., Methods: We studied overnight high-density electroencephalography recordings in focal drug-resistant epilepsy. IEDs were marked visually in each vigilance state, and examined in the sensor and source space. ESIs were calculated and compared between all vigilance states and the clinical ground truth. Two conditions were considered within each vigilance state, an unequalized and an equalized number of IEDs., Results: The number, amplitude, and duration of IEDs were affected by the vigilance state, with N3 sleep presenting the highest number, amplitude, and duration for both conditions (P < 0.001), while signal-to-noise ratio only differed in the unequalized condition (P < 0.001). The vigilance state did not affect channel involvement (P > 0.05). ESI maps showed no differences in distance, quality, extent, or maxima distances compared to the clinical ground truth for both conditions (P > 0.05). Only when an absolute reference (wakefulness) was used, the channel involvement (P < 0.05) and ESI source extent (P < 0.01) were impacted during rapid-eye-movement (REM) sleep. Clustering of amplitude-sensitive and -insensitive ESI maps pointed to amplitude rather than the spatial profile as the driver (P < 0.05)., Interpretation: IED ESI results are stable across vigilance states, including REM sleep, if controlled for amplitude and IED number. ESI is thus stable and invariant to the vigilance state., (© 2023 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Background: Magnetoencephalography (MEG) is a widely used non-invasive tool to estimate brain activity with high temporal resolution. However, due to the ill-posed nature of the MEG source imaging (MSI) problem, the ability of MSI to identify accurately underlying brain sources along the cortical surface is still uncertain and requires validation., Method: We validated the ability of MSI to estimate the background resting state activity of 45 healthy participants by comparing it to the intracranial EEG (iEEG) atlas (https://mni-open-ieegatlas., Research: mcgill.ca/). First, we applied wavelet-based Maximum Entropy on the Mean (wMEM) as an MSI technique. Next, we converted MEG source maps into intracranial space by applying a forward model to the MEG-reconstructed source maps, and estimated virtual iEEG (ViEEG) potentials on each iEEG channel location; we finally quantitatively compared those with actual iEEG signals from the atlas for 38 regions of interest in the canonical frequency bands., Results: The MEG spectra were more accurately estimated in the lateral regions compared to the medial regions. The regions with higher amplitude in the ViEEG than in the iEEG were more accurately recovered. In the deep regions, MEG-estimated amplitudes were largely underestimated and the spectra were poorly recovered. Overall, our wMEM results were similar to those obtained with minimum norm or beamformer source localization. Moreover, the MEG largely overestimated oscillatory peaks in the alpha band, especially in the anterior and deep regions. This is possibly due to higher phase synchronization of alpha oscillations over extended regions, exceeding the spatial sensitivity of iEEG but detected by MEG. Importantly, we found that MEG-estimated spectra were more comparable to spectra from the iEEG atlas after the aperiodic components were removed., Conclusion: This study identifies brain regions and frequencies for which MEG source analysis is likely to be reliable, a promising step towards resolving the uncertainty in recovering intracerebral activity from non-invasive MEG studies., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2023. Published by Elsevier Inc.)

Background and Aim: Video gaming has witnessed tremendous growth in recent years. Video games have been associated with various negative effects on players, such as aggressive behavior and reduced apathy. The present review aims to investigate the association between video games and violence among children and adolescents in the Arab world, while highlighting the influence of the type of video games played, time spent playing, and other possible associated factors., Methods: A literature search was performed on PubMed and Web of Science electronic databases. All studies assessing video games and violence among children and adolescents written in English were eligible for inclusion in the review. A total of 9 studies were included in this systematic review., Results: Six studies investigated the relationship between video games and aggression, five of which found a significant association. Several factors have been studied to assess their role in mediating the association between the two. A statistically significant association was found between aggression and age and sex of the players, with a predominance among early adolescents and males. Longer durations spent playing video games were found in three studies to be significantly associated with a greater risk of aggression., Conclusions: In the Arab world, studies addressing this subject are limited. The discrepancy of reported results between video games and amount of violence could be attributed to the lack of standardization across studies. Therefore, it becomes imperative to further explore the association through conclusive studies with standardized measures.(www.actabiomedica.it).

Rationale: Future optimization of computed tomography (CT) lung cancer screening (CTLS) algorithms will depend on clinical outcomes data. Objectives: To report the outcomes of positive and suspicious findings in a clinical CTLS program. Methods: We retrospectively reviewed results for patients from our institution undergoing lung cancer screening from January 2012 through December 2018, with follow-up through December 2019. All exams were retrospectively rescored using Lung-RADS v1.1 (LR). Metrics assessed included positive, probably benign, and suspicious exam rates, frequency/nature of care escalation, and lung cancer detection rates after a positive, probably benign, and suspicious exam result and overall. We calculated time required to resolve suspicious exams as malignant or benign. Results were broken down by subcategories, reason for positive/suspicious designation, and screening round. Results: During the study period 4,301 individuals underwent a total of 10,897 exams. The number of positive (13.9%), suspicious (5.5%), and significant incidental (6.4%) findings was significantly higher at baseline screening. Cancer detection and false-positive rates were 2.0% and 12.3% at baseline versus 1.3% and 5.1% across subsequent screening rounds, respectively. Baseline solid nodule(s) 6 to <8 mm were the only probably benign findings resulting in lung cancer detection within 12 months. New solid nodules 6 to <8 mm were the only LR category 4A (LR4A) findings falling within the LR predicted cancer detection range of 5-15% (12.8%). 38.5% of LR4A cancers were detected within 3 months. Conclusions: Modification of the definition and suggested workup of positive and suspicious lung cancer screening findings appears warranted.

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide and within the United States. Liver transplant or partial liver resection is the definitive treatment of choice for HCC; however, the majority of cases are detected in advanced stages due to its early-stage asymptomatic nature, often precluding surgical treatment. Locoregional therapy plays an essential role in HCC management, including curative intent, as a bridge to transplant, or in some cases palliative therapy. Radiologists play a critical role in assessing tumor response following treatment to guide further management that may potentially impact transplantation eligibility; therefore, it is important for radiologists to have an understanding of different locoregional therapies and the variations of imaging response to different therapies. In this review article, we outline the imaging response to ablative therapy (AT), transarterial chemoembolization (TACE), selective internal radiation therapy (SIRT), and stereotactic body radiation therapy (SBRT). We will also briefly discuss the basic concepts of these locoregional therapies. This review focuses on the imaging features following locoregional treatment for hepatocellular carcinoma following AT, TACE, SIRT, and SBRT., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background and Objectives: Accurate delineation of the seizure-onset zone (SOZ) in focal drug-resistant epilepsy often requires stereo-EEG (SEEG) recordings. Our aims were to propose a truly objective and quantitative comparison between EEG/magnetoencephalography (MEG) source imaging (EMSI), EEG/fMRI responses for similar spikes with primary irritative zone (PIZ) and SOZ defined by SEEG and to evaluate the value of EMSI and EEG/fMRI to predict postsurgical outcome., Methods: We identified patients with drug-resistant epilepsy who underwent EEG/MEG, EEG/fMRI, and subsequent SEEG at the Epilepsy Service from the Montreal Neurological Institute and Hospital. We quantified multimodal concordance within the SEEG channel space as spatial overlap with PIZ/SOZ and distances to the spike-onset, spike maximum amplitude and seizure core intracerebral channels by applying a new methodology consisting of converting EMSI results into SEEG electrical potentials (EMSIe-SEEG) and projecting the most significant fMRI response on the SEEG channels (fMRIp-SEEG). Spatial overlaps with PIZ/SOZ (AUC PIZ , AUC SOZ ) were assessed by using the area under the receiver operating characteristic curve (AUC). Here, AUC represents the probability that a randomly picked active contact exhibited higher amplitude when located inside the spatial reference than outside., Results: Seventeen patients were included. Mean spatial overlaps with the PIZ and SOZ were 0.71 and 0.65 for EMSIe-SEEG and 0.57 and 0.62 for fMRIp-SEEG. Good EMSIe-SEEG spatial overlap with the PIZ was associated with smaller distance from the maximum EMSIe-SEEG contact to the spike maximum amplitude channel (median distance 14 mm). Conversely, good fMRIp-SEEG spatial overlap with the SOZ was associated with smaller distances from the maximum fMRIp-SEEG contact to the spike-onset and seizure core channels (median distances 10 and 5 mm, respectively). Surgical outcomes were correctly predicted by EEG/MEG in 12 of 15 (80%) patients and EEG/fMRI in 6 of 11(54%) patients., Discussion: With the use of a unique quantitative approach estimating EMSI and fMRI results in the reference SEEG channel space, EEG/MEG and EEG/fMRI accurately localized the SOZ and the PIZ. Precisely, EEG/MEG more accurately localized the PIZ, whereas EEG/fMRI was more sensitive to the SOZ. Both neuroimaging techniques provide complementary localization that can help guide SEEG implantation and select good candidates for surgery., (© 2022 American Academy of Neurology.)

Novel anticancer agents have replaced conventional chemotherapy as first line agents for many cancers, with continued new and expanding indications. Small molecule inhibitors act on cell surface or intracellular targets and prevent the downstream signaling that would otherwise permit tumor growth and spread. Anticancer antibodies can be directed against growth factors or may be immunotherapeutic agents. The latter act by inhibiting mechanisms that cancer cells use to evade the immune system. Hormonal agents act by decreasing levels of hormones that are necessary for the growth of certain cancer cells. Cancer therapy protocols often include novel anticancer agents and conventional chemotherapy used successively or in combination, in order to maximize survival and minimize morbidity. A working knowledge of anti-cancer drug classification will aid the radiologist in assessing response on imaging., (© 2022 The Authors.)

Aneurysmal bone cysts (ABCs) are benign, expansile, blood-filled, osteolytic lesions with internal septations that may be intraosseous or extraosseous. The cysts may cause local mass effect, and changes in the regional vascular supply necessitating intervention. A case of an intracranial, intradural ABC in a young male patient with progressively severe headaches is presented. This is only the third recorded intradural case, the majority of these rare lesions being extracranial and only a minute fraction intracranial., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Celiac disease is now recognized as a common disease, occurring in about one in every 200 Americans. However, less than 10% of cases are currently diagnosed, with a diagnostic delay of more than 10 years from onset of symptoms. In the past, barium examination of the small bowel demonstrated a pattern of abnormal findings caused by the pathophysiologic changes induced by malabsorption, thus leading to diagnosis of celiac disease and other diseases of malabsorption. Although not specific, that pattern prompted further patient evaluation. The number of barium examinations performed and the skill necessary to interpret their results are both in decline. Abdominal pain in celiac disease is a common early complaint that often leads to computed tomography (CT). Improved CT resolution now permits better depiction of the small bowel, colon, and mesenteric lymph nodes, all of which are affected by celiac disease. Detection of celiac disease with CT will allow treatment to be initiated to prevent the significant morbidity and increased mortality associated with a delay in diagnosis. The abnormal CT findings seen over the past decade during review of more than 200 cases of celiac disease demonstrate that CT depicts more features of celiac disease than did barium examination. Pattern recognition for the diagnosis of small bowel diseases that create structural changes in the bowel wall is well accepted. Because it demonstrates features of celiac disease not detected with barium examination, CT may be more sensitive than barium examination for diagnosis of this disease.

Murine reperfusion injury follows binding of specific IgM natural antibodies to neo-antigens exposed in ischemic tissue. Peptides that mimic the site of antibody binding in the injury prevent IgM binding when administered intravenously before reperfusion. To determine whether this pathogenic sequence is restricted to mice, we have tested the ability of the peptide to prevent reperfusion injury in a dissimilar species, the rat. Sprague-Dawley rats were subjected to 40 min of mesenteric ischemia followed by 180 min of reperfusion. The peptide mimic was administered intravenously prior to reperfusion. Gut injury was quantified using a scoring system based on the hematoxylin-and-eosin section. (125)I-labeled albumin was used to assess local (gut) and remote (lung) injury. The macroscopic appearance of bowel from peptide-treated animals was less edematous and hemorrhagic. Microscopic analysis showed a significantly reduced injury score in peptide-treated animals. Permeability data indicated a significant reduction in local and remote injury in peptide-treated animals. The data demonstrate attenuation of rat gut microvillus injury, of gut edema, and of remote injury following mesenteric ischemia-reperfusion due to administration of an intravenous peptide mimic of a murine ischemia neo-antigen, indicating a second species uses a similar ischemia neo-antigen and corresponding natural antibody specificity to amplify reperfusion injury to the point of necrosis. This mechanism of inflammation is potentially applicable to higher species.

Successful and accurate imaging of prostate cancer is integral to its clinical management from detection and staging to subsequent monitoring. Various modalities are used including ultrasound, computed tomography, and magnetic resonance imaging, with the greatest advances seen in the field of magnetic resonance., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Background: Ischemia and reperfusion (I/R) of tissue provokes an inflammatory process that is highly dependent on circulating natural immunoglobulin M (IgM) and the complement cascade. In mice, a single IgM specificity produced by peritoneal B cells can initiate reperfusion injury. It is unknown whether humans express natural IgM with a similar specificity. It is also unknown whether pathogenic IgM is produced solely from peritoneal B cells or can also be made by circulating B cells., Methods: Immunodeficient mice lacking endogenous immunoglobulin were used. Mice were reconstituted with 0.9% normal saline, human serum, or xenografted human peripheral blood lymphocytes (PBLs) and then subjected to tourniquet-induced hindlimb I/R. Serum human IgM and immunoglobulin G (IgG) were measured by enzyme-linked immunosorbent (ELISA) assay. Skeletal muscle was harvested for injury assessment by histology and for immunohistochemistry., Results: Immunodeficient mice were protected from skeletal muscle injury after hindlimb I/R. Transfer of human serum restored skeletal muscle damage. Rag2/gammaR-/- mice that were engrafted with human PBL (huPBL-SCID) had high levels of human IgM. huPBL-SCID mice developed significantly more skeletal muscle injury than control saline-treated mice (P < or = .01) and human serum-reconstituted Rag2/gammaR-/- mice (P < or = 0.01). Sham-treated huPBL-SCID mice had no muscle injury, demonstrating that human lymphocyte engraftment did not cause injury in the absence of ischemia. Deposition of human IgM was observed on injured but not sham-injured muscle., Conclusion: Human serum can initiate murine skeletal muscle I/R injury. Circulating human PBL may be a source of pathogenic IgM. The huPBL-SCID mouse may be a useful model to define the specificity of pathogenic human IgM and to test therapeutics for I/R injury.

Background: The injury sustained by reperfused skeletal muscle is inflammatory and is initiated by binding of pre-formed IgM to involved tissue, followed by local complement activation and further inflammation. A clone of natural IgM has been described that initiates this injury, suggesting that specific antigens are exposed on ischemic tissues that act as ligands for this pathogenic antibody. In these experiments, we examine the properties of short peptide sequences, and their homologues, that bind to the antigen-combining site of this pathogenic IgM clone., Methods: A 12-mer phage display library was biopanned with the pathogenic IgM clone and then negatively selected against an inactive natural IgM clone. All 8 clones that bound specifically to the pathogenic IgM had closely related amino acid sequences. P8 is the clone that bound most avidly. Tissue lysates from ischemic tissue were reacted with pathogenic IgM, and immune complexes isolated and analyzed on SDS-PAGE. Bands were excised and sequenced, identifying non-muscle myosin as the protein reacting with pathogenic antibody in ischemic gut and glycogen phosphorylase as the counterpart in ischemic skeletal muscle. Both proteins contain sequence homologous to P8; N2 and GP1 are the natural 12-mers homologues that are contained within non-muscle myosin and glycogen phosphorylase, respectively. Wild-type C57/Bl6 mice, divided into groups receiving saline, P8, N2, GP1, or a random peptide at the start of the experiment, were subjected to 2 hours of tourniquet induced hind limb ischemia and 3 hours of reperfusion. Muscle was assessed for injury with histology and for immune activation with histochemistry., Results: Intravenous administration of P8, N2, and GP1 led to significant attenuation of muscle injury (13 +/- 1.8 injured fibers/50 counted, 12 +/- 0.81, 8.0 +/- 0.73 respectively) after reperfusion injury compared to animals receiving saline (26 +/- 2.3) or the same mass of a random peptide (22 +/- 2.3), P less than .05. This level of protection from injury is comparable to that seen in the absence of antibody altogether. As well, P8-treated animals exhibited a marked decrease in deposition of IgM (as well as C3) in comparison to saline treated controls., Conclusions: Specific peptide blockade of an injury-inducing IgM clone decreased the local consequences of skeletal muscle ischemia/reperfusion injury in wild-type animals that have the full repertoire of IgM specificities. This indicates that the antibodies that initiate reperfusion injury have specificity only for P8-related antigens. This could also indicate that the variety of relevant ischemic antigens is quite restricted.

Ischemia with subsequent reperfusion (IR) injury is a significant clinical problem that occurs after physical and surgical trauma, myocardial infarction, and organ transplantation. IR injury of mouse skeletal muscle depends on the presence of both natural IgM and an intact C pathway. Disruption of the skeletal muscle architecture and permeability also requires mast cell (MC) participation, as revealed by the fact that IR injury is markedly reduced in c-kit defective, MC-deficient mouse strains. In this study, we sought to identify the pathobiologic MC products expressed in IR injury using transgenic mouse strains with normal MC development, except for the lack of a particular MC-derived mediator. Histologic analysis of skeletal muscle from BALB/c and C57BL/6 mice revealed a strong positive correlation (R(2) = 0.85) between the extent of IR injury and the level of MC degranulation. Linkage between C activation and MC degranulation was demonstrated in mice lacking C4, in which only limited MC degranulation and muscle injury were apparent. No reduction in injury was observed in transgenic mice lacking leukotriene C(4) synthase, hemopoietic PGD(2) synthase, N-deacetylase/N-sulfotransferase-2 (enzyme involved in heparin biosynthesis), or mouse MC protease (mMCP) 1. In contrast, muscle injury was significantly attenuated in mMCP-5-null mice. The MCs that reside in skeletal muscle contain abundant amounts of mMCP-5 which is the serine protease that is most similar in sequence to human MC chymase. We now report a cytotoxic activity associated with a MC-specific protease and demonstrate that mMCP-5 is critical for irreversible IR injury of skeletal muscle.