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Glucagon was discovered about a hundred years ago and its role in health and disease is under continuous investigation. Glucagon is a counter regulatory hormone secreted by alpha cells of the pancreas in response to multiple stimuli. Although some of glucagon's actions and its clinical application have been described, clinical experience with glucagon has been historically overshadowed by that of insulin. To date, the role of glucagon's actions in pharmacotherapy has been under explored. Glucagon plays a considerable role as a hormonal regulator via its known actions on the liver. The rise in obesity and diabetes mellitus prevalence is bringing focus to glucagon's known physiological roles and possible clinical applications. Six glucagon products and a glucagon analog are approved for use in the United States. Clinical pharmacology studies provide crucial support of glucagon's actions as evident from comprehensive pharmacokinetics and pharmacodynamics evaluations in humans. Here, we briefly describe the established physiological role of glucagon in humans and its known relationship with disease. We later summarize the clinical pharmacology of available glucagon products with different routes of administration., (© 2024 The Author(s). Clinical Pharmacology & Therapeutics © 2024 American Society for Clinical Pharmacology and Therapeutics.)

Background: As the ongoing public health crisis from Coronavirus Disease 2019 (COVID-19) pandemic puts strains on current models of cancer care, many health care centers had to adapt to minimize the risk of exposure and infection. The effects of the COVID-19 pandemic in a comprehensive cancer center were determined., Aims: To measure the impact of the COVID-19 pandemic on care delivery at a comprehensive cancer center., Methods: The number of on-site and telehealth visits (TH) were obtained from scheduling software. Multiple factors including total visits, telehealth visits, screenings for cancer diagnosis, and cancer treatments were tracked from 2 years before the pandemic onset through 2022. The length of stay (LOS) and Case Mix Index (CMI) were calculated using hospital database., Results: In the third quarter of FY 2020, telehealth visits (TH) represented a fifth of total patient encounters. Cancer treatments, such as chemotherapy, radiation therapy, and surgery, decreased during the pandemic with number of surgeries being most affected (23% decrease in 2020 compared to the previous fiscal year). The average length of stay (LOS) was also longer with less discharges per given time during the pandemic. The increased LOS was related to increased severity of patient illnesses since CMI was higher. Screening mammograms decreased to a nadir of 58% in 2021 as compared to those screened in pre-pandemic fiscal years., Conclusion: The COVID-19 pandemic impacted many aspects of care, such as treatment and screenings. Many of these factors had to be postponed due to the fear of acquiring COVID-19 and access to care. The findings presented implicate that the delays and changes in cancer care during the pandemic resulted in less screening and treatment of more advanced disease., (© 2023 The Authors. Cancer Reports published by Wiley Periodicals LLC.)

Fragile X syndrome (FXS), a leading monogenic cause of autism spectrum disorders (ASDs), typically occurs as the result of a mutation silencing the Fmr1 gene, preventing production of the fragile X messenger ribonucleoprotein (FMRP). FXS is characterized, in part, by hyperactivity, impaired behavioral flexibility, and the development of repetitive, or stereotyped, behaviors. While these phenotypes are influenced by striatal activity, few studies have examined FXS or FMRP in the context of striatal function. Here, we report enhanced repetitive behaviors in Fmr1 knockout (KO) compared to wild type (WT) mice according to multiple measures, including quantity and intensity of stereotypic behaviors in an open field and nose poking activity in an unbaited hole board test. However, using a baited version of the hole board assay, we see that KO mice do show some behavioral flexibility in that they make changes in their nose poking behavior following familiarization with an appetitive bait. By contrast, repeated exposure to cocaine (15 mg/kg) promotes repetitive behavior in both WT and KO mice, in a manner mostly independent of genotype. Branch length alterations in medium spiny neurons (MSNs) of the dorsolateral striatum (DLS) are similar between WT cocaine-treated and KO saline-treated mice, possibly suggesting shared synaptic mechanisms. Overall, we suggest that scoring open field behavior is a sensitive measure for repetitive sensory-motor behaviors in Fmr1 KO mice. In addition, our findings show that synaptic contacts onto MSNs in the DLS should be examined in conjunction with measures of stereotypical behavior., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Purpose: Gastric cancer is a frequent cancer in the tropics. The objective was to review a decade of gastric cancer data, and to study its spatial and temporal trends., Methods: The cancer registry of French Guiana compiled exhaustive data on gastric cancer throughout French Guiana between 2005 and 2014. Age-standardized incidence and mortality rates were computed., Results: With 187 new cases recorded, gastric cancer ranked 6th (4.3%). It was more frequent in men than in women. The median age at diagnosis was 62 years for men and 65 years for women. The incidence rate standardized to the world population over the period 2005-2014 was 14.3 cases of gastric cancer per 100,000 man-years and 7.3 per 100,000 woman-years. The death rate from gastric cancer, standardized to the world population over the period 2005-2014, was 8.6 deaths from gastric cancer per 100,000 man-years and 3.4 per 100,000 women-years. These measures were lower than what is reported in Latin America, similar to Martinique and Guadeloupe-two tropical French territories-and higher than in France., Conclusions: Gastric cancer affected more males and the median age was younger than in France. Standardized incidence and mortality rates for gastric cancer in French Guiana were between those of France and those of Latin America, and they were comparable to those of the French West Indies. The downward trend in a context of rapid economic growth suggests further gains that could be achieved by improving electricity, water, and sanitation coverage throughout the territory despite challenging geography, and better access to care and Helicobacter pylori eradication., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature.)

Objective: Two decades of research has examined within-person associations between negative emotion states and ambulatory blood pressure (ABP) using ecological momentary assessment (EMA), but no meta-analysis has been conducted. We conducted this systematic review and meta-analysis to quantify the magnitude of this association and identify moderators, review strengths and weaknesses in conceptual and measurement approaches, and provide recommendations., Methods: We searched databases (PsycINFO, PubMed), identified 15 studies, and obtained data from 13 studies (n = 2511; 142,307 observations)., Results: Random-effects meta-analyses demonstrated small effect r values between momentary negative emotions and systolic ABP (r = 0.06) and diastolic ABP (r = 0.05; p values < .001). Meta-regressions found that effects were larger among studies focused on anxiety, multidimensional negative emotions, predominantly female samples, or less observations of each participant (p values from .003 to .049). A qualitative review found that few studies examined moderators contributing to the substantial interindividual differences in this association., Conclusions: The small association between momentary negative emotion and ABP extends laboratory findings on the association between the experiential and physiological aspects of emotion to the daily, natural emotional experiences of individuals. This literature could be strengthened by determining interindividual and intraindividual moderators of this association (e.g., trait negative emotion and state positive emotion), examining differential associations of different negative emotions with ABP, and standardizing EMA protocols. Although the effect is small, to the extent that repeated emotion-related cardiovascular reactivity may contribute to cardiovascular disease risk, identifying daily life triggers of emotion is important., (Copyright © 2021 by the American Psychosomatic Society.)

Objectives: Cervical cancer is the second most frequent cancer among women in French Guiana. The objective was to review a decade of cervical cancer data, and to study spatial and temporal trends., Study Design: The design was retrospective and descriptive., Methods: The cancer registry of French Guiana compiled exhaustive data on cervical cancer throughout French Guiana between 2005 and 2015. Age-standardized incidence and mortality were computed and mapped to identify priority areas., Results: With 232 new cases recorded in French Guiana between 2005 and 2014 (23 annual cases), cervical cancer ranked 5th among all incident cancers (11%) and was the 2nd most frequent cancer in women (12% of cancers among women). The standardized incidence rate over the period 2005-2014 was 23.8 cases of cervical cancer per 100 000 woman-years. Between 2005-2009 and 2010-2014 the incidence of cervical cancer decreased from 26.26 cases per 100 000 to 22.66 cases per 100 000 and the mortality rate from cervical cancer decreased from 6 deaths per 100 000 to 3.2 deaths per 100 000.Within French Guiana, the standardized incidence rates were very heterogenous with the highest rates in remote areas. The standardized death rate from cervical cancer over the 2005-2014 decade was 4.4 cases per 100 000 woman-years., Conclusions: The present results suggest there has been progress in French Guiana, but there are still areas where screening is challenging and should be expanded. The recent authorization of HPV testing is an opportunity that could help health professionals achieve this goal. HPV vaccination -with a nonavalent vaccine-is also an important public health endeavor that could alleviate the burden of cervical cancer among the cohorts of women benefitting from it., (© 2021 The Author(s).)

Purpose: Pulp and nail atrophy and asymmetry are commonly seen in thumb duplication. In hypoplasia of both digits, conventional reconstruction or Bilhaut-Cloquet procedure and its modifications may not be possible or may lead to a poor cosmetic outcome. The purpose of the study was to review a reconstruction technique with a neurovascular island flap developed to improve the aesthetic and functional results of treatment., Methods: Fourteen patients with thumb duplication aged 8 to 18 months were operated between 2002 and 2013 in our center. All patients had significant hypoplasia and asymmetry of the pulp and nail of the digit planned to be retained. A neurovascular island flap including part of the pulp tissue, nail bed, with or without the associated phalangeal bone, was raised from the planned ablated digit base on its single neurovascular bundle. The nail bed, nail fold, and pulp tissue from the 2 digits were apposed with fine sutures under magnification. All patients were followed to monitor the aesthetic, functional, and radiological outcome., Results: The mean follow-up period was 7 years, 11 months. Thirteen patients underwent the flap procedure and all flaps survived. In 1 patient, the flap procedure was aborted because the vascular pedicle was not well formed. The nail width and pulp circumference were restored to a similar size as the contralateral thumb., Conclusions: In selected cases of thumb duplication with significant pulp hypoplasia and nail asymmetry, the neurovascular island flap is a safe and effective means to restore size and symmetry., Type of Study/level of Evidence: Therapeutic IV., (Copyright © 2021 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

The dominant belief is that science progresses by testing theories and moving towards theoretical consensus. While it's implicitly assumed that psychology operates in this manner, critical discussions claim that the field suffers from a lack of cumulative theory. To examine this paradox, we analysed research published in Psychological Science from 2009-2019 (N = 2,225). We found mention of 359 theories in-text, most were referred to only once. Only 53.66% of all manuscripts included the word theory, and only 15.33% explicitly claimed to test predictions derived from theories. We interpret this to suggest that the majority of research published in this flagship journal is not driven by theory, nor can it be contributing to cumulative theory building. These data provide insight into the kinds of research psychologists are conducting and raises questions about the role of theory in the psychological sciences., Competing Interests: The authors have declared that no competing interests exist.

The emergence of the COVID-19 pandemic has severely affected medical treatment protocols throughout the world. While the pandemic does not affect hand surgeons at first glance, they have a role to play. The purpose of this study was to describe the different measures that have been put in place in response to the COVID-19 pandemic by hand surgeons throughout the world. The survey comprised 47 surgeons working in 34 countries who responded to an online questionnaire. We found that the protocols varied in terms of visitors, health professionals in the operating room, patient waiting areas, wards and emergency rooms. Based on these preliminary findings, an international consensus on hand surgery practices for the current viral pandemic, and future ones, needs to be built rapidly., (Copyright © 2020 SFCM. Published by Elsevier Masson SAS. All rights reserved.)

In vitro cell-based assays are common screening tools used for the identification of new VDR ligands. For 25-hydroxyvitamin D 3 [25(OH)D 3 ] and 1α-hydroxyvitamin D 3 [1α(OH)D 3 ], protein expressions of CYP2R1 and CYP27B1, respectively, that form the active 1α,25-dihydroxyvitamin D 3 [1,25(OH) 2 D 3 ] ligand were detected in human embryonic kidney (HEK293) cells expressing the GAL4-hVDR, the human brain microvessel endothelial (hCMEC/D3) and adenocarcinoma colonic (Caco-2) cells. The impact of bioactivation enzymes was shown upon the addition of ketoconazole (10 μM KTZ), a pan-CYP inhibitor, which reduced the apparent potency of 25(OH)D 3 and increased the EC 50 from 272 to 608 nM in HEK293 cells. EIA assays verified that 1,25(OH) 2 D 3 was formed and contributed to VDR activity independently of its precursors. In hCMEC/D3 cells where enzyme protein levels were lowest, changes in MDR1/P-gp expression with KTZ were minimal. In Caco-2 cells, the induction of TRPV6 (calcium channel), CYP24A1, CYP3A4, OATP1A2 and MDR1 mRNA expression was 1,25(OH) 2 D 3  > 1α(OH)D 3  > 25(OH)D 3 , with the magnitude of change being blunted by KTZ. Upon inclusion of KTZ in the cell-based assays, high transcriptional activities were observed for synthetic VDR activators from Teijin Pharma. Cyclopentanone derivatives: TPD-003, TPD-005, TPD-006, TPD-008 and TPD-009 (EC 50 s 0.06 to 67 nM, unchanged with KTZ) were found more potent over straight chain and lactone derivatives (antagonists). Most TPD compounds activated OATP1A2, CYP24A1, CYP3A4, and MDR1 (28-67%) and TRPV6 transcriptionally in Caco-2 cells. The results identified that cell-based assays with added KTZ could accurately identify new VDR activators, although these may be hypercalcemic with strong TRPV6 inducing properties., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Despite advances in genomic analysis, the molecular origin of neuroendocrine tumors (NETs) is complex and poorly explained by described oncogenes. The neurotrophic TRK family, including NTRK 1, 2, and 3, encode the proteins TRKA, TRKB, TRKC, respectively, involved in normal nerve development. Because NETs develop from the diffuse neuroendocrine system, we sought to determine whether NTRK alterations occur in NETs and whether TRK-targeted therapy would be effective. A patient with metastatic well-differentiated NET, likely of the small intestine, was enrolled on the STARTRK2 trial (ClinicalTrials.gov identifier: NCT02568267) and tissue samples were analyzed using an RNA-Seq next-generation sequencing platform. An ETV6:NTRK3 fusion was identified and therapy was initiated with the investigational agent entrectinib, a potent oral tyrosine kinase inhibitor of TRKA, TRKB, and TRKC. Upon treatment with entrectinib, the patient experienced rapid clinical improvement; his tumor response was characterized by initial tumor growth and necrosis. This is the first report of an NTRK fusion in NETs. Our patient's response to entrectinib suggests that NTRK fusions can be important in the pathogenesis of NETs. Recent DNA-based genomic analyses of NETs may have missed NTRK fusions due its large gene rearrangement size and multiple fusion partners. The tumor's initial pseudoprogression may represent a unique response pattern for TRK-targeted therapies. An effort to characterize the prevalence of NTRK fusions in NETs using optimal sequencing technology is important., (Copyright © 2017 by the National Comprehensive Cancer Network.)

Purpose: To evaluate the efficacy of apalutamide before or after treatment with abiraterone acetate and prednisone (AAP) in patients with progressive metastatic castration-resistant prostate cancer (mCRPC). Experimental Design: Two cohorts were studied: AAP-naïve and post-AAP patients who had received ≥6 months of AAP. Patients had progressive mCRPC per rising prostate-specific antigen (PSA) and/or imaging, without prior chemotherapy exposure. All received apalutamide 240 mg/day. Primary endpoint was ≥50% decline in 12-week PSA according to Prostate Cancer Working Group 2 criteria. Secondary endpoints included time to PSA progression and time on treatment. Results: Forty-six patients enrolled in the AAP-naïve ( n = 25) and post-AAP ( n = 21) cohorts. The 12-week PSA response rate was 88% (22/25) and 22% (4/18), median time to PSA progression was 18.2 months [95% confidence interval (CI), 8.3 months-not reached) and 3.7 months (95% CI, 2.8-5.6 months), and median time on treatment 21 months (range, 2.6-37.5) and 4.9 months (range, 1.3-23.2), for the AAP-naïve and post-AAP cohorts, respectively. Eighty percent (95% CI, 59-93) and 64% (95% CI, 43-82) of AAP-naïve and 43% (95% CI, 22-66) and 10% (95% CI, 1-30) of post-AAP patients remained on treatment for 6+ and 12+ months, respectively. Common treatment-emergent adverse events in both cohorts were grade 1 or 2 fatigue, diarrhea, nausea, and abdominal pain. Conclusions: Apalutamide was safe, well tolerated, and demonstrated clinical activity in mCRPC, with 80% of AAP-naïve and 43% of post-AAP patients, remaining on treatment for 6 months or longer. Clin Cancer Res; 23(14); 3544-51. ©2017 AACR ., (©2017 American Association for Cancer Research.)

Background: Dissociative attentional stimuli (e.g., music, video) are effective in decreasing ratings of perceived exertion (RPE) during low-to-moderate intensity exercise, but have inconsistent results during exercise at higher intensity. The purpose of this study was to assess attentional focus and RPE during high-intensity exercise as a function of being exposed to music, video, both (music and video), or a no-treatment control condition., Methods: During the first session, healthy men ( n  = 15) completed a maximal fitness test to determine the workload necessary for high-intensity exercise (operationalized as 125% ventilatory threshold) to be performed during subsequent sessions. On 4 subsequent days, they completed 20 min of high-intensity exercise in a no-treatment control condition or while listening to music, watching a video, or both. Attentional focus, RPE, heart rate, and distance covered were measured every 4 min during the exercise., Results: Music and video in combination resulted in significantly lower RPE across time (partial η 2  = 0.36) and the size of the effect increased over time (partial η 2  = 0.14). Additionally, music and video in combination resulted in a significantly more dissociative focus than the other conditions (partial η 2  = 0.29)., Conclusion: Music and video in combination may result in lower perceived exertion during high-intensity exercise when compared to music or video in isolation. Future research will be necessary to test if reductions in perceived exertion in response to dissociative attentional stimuli have implications for exercise adherence.

The humanized liver mouse model is being exploited increasingly for human drug metabolism studies. However, its model stability, intercommunication between human hepatocytes and mouse nonparenchymal cells in liver and murine intestine, and changes in extrahepatic transporter and enzyme expressions have not been investigated. We examined these issues in FRGN [fumarylacetoacetate hydrolase (Fah-/-), recombination activating gene 2 (Rag2-/-), and interleukin 2 receptor subunit gamma (IL-2rg -/-) triple knockout] on nonobese diabetic (NOD) background] and chimeric mice: mFRGN and hFRGN (repopulated with mouse or human hepatocytes, respectively). hFRGN mice showed markedly higher levels of liver cholesterol, biliary bilirubin, and bile acids (liver, bile, and plasma; mainly human forms, but also murine bile acids) but lower transforming growth factor beta receptor 2 (TGFBR2) mRNA expression levels (10%) in human hepatocytes and other proliferative markers in mouse nonparenchymal cells (Tgf-β1) and cholangiocytes [plasma membrane-bound, G protein-coupled receptor for bile acids (Tgr5)], suggestive of irregular regeneration processes in hFRGN livers. Changes in gene expression in murine intestine, kidney, and brain of hFRGN mice, in particular, induction of intestinal farnesoid X receptor (Fxr) genes: fibroblast growth factor 15 (Fgf15), mouse ileal bile acid binding protein (Ibabp), small heterodimer partner (Shp), and the organic solute transporter alpha (Ostα), were observed. Proteomics revealed persistence of remnant murine proteins (cyotchrome P450 7α-hydroxylase (Cyp7a1) and other enzymes and transporters) in hFRGN livers and suggest the likelihood of mouse activity. When compared with normal human liver tissue, hFRGN livers showed lower SHP mRNA and higher CYP7A1 (300%) protein expression, consequences of tβ- and tα-muricholic acid-mediated inhibition of the FXR-SHP cascade and miscommunication between intestinal Fgf15 and human liver fibroblast growth factor receptor 4 (FGFR4), as confirmed by the unchanged hepatic pERK/total ERK ratio. Dysregulation of hepatocyte proliferation and bile acid homeostasis in hFRGN livers led to hepatotoxicity, gallbladder distension, liver deformity, and other extrahepatic changes, making questionable the use of the preparation for drug metabolism studies., (Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.)

Drug solubility, effective permeability, and intestinal metabolism and transport are parameters that govern intestinal bioavailability and oral absorption. However, excipients may affect the systemic bioavailability of a drug by altering these parameters. Thus, parameter sensitivity analyses using physiologically based pharmacokinetic (PBPK) models were performed to examine the potential impact of excipients on oral drug absorption of different Biopharmaceutics Classification System (BCS) class drugs. The simulation results showed that changes in solubility had minimal impact on C max and AUC 0-t of investigated BCS class 1 and 3 drugs. Changes in passive permeability altered C max more than AUC 0-t for BCS class 1 drugs but were variable and drug-specific across different BCS class 2 and 3 drugs. Depending on the drug compounds for BCS class 1 and 2 drugs, changes in intestinal metabolic activity altered C max and AUC 0-t . Reducing or increasing influx and efflux transporter activity might likely affect C max and AUC 0-t of BCS class 2 and 3 drugs, but the magnitude may be drug dependent. Changes in passive permeability and/or transporter activity for BCS class 2 and 3 drugs might also have a significant impact on fraction absorbed and systemic bioavailability while changes in intestinal metabolic activity may have an impact on gut and systemic bioavailability. Overall, we demonstrate that PBPK modeling can be used routinely to examine sensitivity of bioavailability based on physiochemical and physiological factors and subsequently assess whether biowaiver requirements need consideration of excipient effects for immediate release oral solid dosage forms.

Chimeric mouse liver models are useful in vivo tools for human drug metabolism studies; however, liver integrity and the microcirculation remain largely uninvestigated. Hence, we conducted liver perfusion studies to examine these attributes in FRGN [Fah(-/-), Rag2(-/-), and Il2rg(-/-), NOD strain] livers (control) and chimeric livers repopulated with mouse (mFRGN) or human (hFRGN) hepatocytes. In single-pass perfusion studies (2.5 ml/min), outflow dilution profiles of noneliminated reference indicators ((51)Cr-RBC, (125)I-albumin, (14)C-sucrose, and (3)H-water) revealed preservation of flow-limited distribution and reduced water and albumin spaces in hFRGN livers compared with FRGN livers, a view supported microscopically by tightly packed sinusoids. With prograde and retrograde perfusion of harmol (50 µM) in FRGN livers, an anterior sulfation (Sult1a1) over the posterior distribution of glucuronidation (Ugt1a1) activity was preserved, evidenced by the 42% lower sulfation-to-glucuronidation ratio (HS/HG) and 14% higher harmol extraction ratio (E) upon switching from prograde to retrograde flow. By contrast, zonation was lost in mFRGN and hFRGN livers, with HS/HG and E for both flows remaining unchanged. Remnant mouse genes persisted in hFRGN livers (10%-300% those of FRGN). When hFRGN livers were compared with human liver tissue, higher UGT1A1 and MRP2, lower MRP3, and unchanged SULT1A1 and MRP4 mRNA expression were observed. Total Sult1a1/SULT1A1 protein expression in hFRGN livers was higher than that of FRGN livers, consistent with higher harmol sulfate formation. The composite data on humanized livers suggest a loss of zonation, lack of complete liver humanization, and persistence of murine hepatocyte activities leading to higher sulfation., (Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.)

1α,25-Dihydroxyvitamin D3 [1,25(OH)2D3] concentrations are regulated by renal CYP27B1 for synthesis and CYP24A1 for degradation. Published plasma and tissue 1,25(OH)2D3 concentrations and mRNA fold change expression of Cyp24a1 and Cyp27b1 following repetitive i.p. injections to C57BL/6 mice (2.5 μg × kg(-1) every 2 days for 4 doses) were fitted with a minimal and full physiologically-based pharmacokinetic-pharmacodynamic models (PBPK-PD). The minimal physiologically-based pharmacokinetic-pharmacodynamic linked model (mPBPK-PD) related Cyp24a1 mRNA fold changes to linear changes in tissue/tissue baseline 1,25(OH)2D3 concentration ratios, whereas the full physiologically-based pharmacokinetic-pharmacodynamic model (PBPK-PD) related measured tissue Cyp24a1 and Cyp27b1 fold changes to tissue 1,25(OH)2D3 concentrations with indirect response, sigmoidal maximal stimulatory effect/maximal inhibitory effect functions. Moreover, the intestinal segregated flow model (SFM) that describes a low and partial intestinal (blood/plasma) flow to enterocytes was nested within both models for comparison with the traditional model for intestine (TM) where the entire flow perfuses the intestine. Both the mPBPK(SFM)-PD and full PBPK(SFM)-PD models described the i.p. plasma and tissue 1,25(OH)2D3 concentrations and fold changes in mRNA expression significantly better than the TM counterparts with F test comparisons. The full PBPK(SFM)-PD fits showed estimates with good precision (lower percentage of coefficient of variation), and the model was more robust in predicting data from escalating i.v. doses (2, 60, and 120 pmol) and the rebound in 1,25(OH)2D3 tissue concentrations after dosing termination. The full PBPK(SFM)-PD model performed the best among the tested models for describing the complex pharmacokinetic-pharmacodynamic interplay among Cyp27b1, Cyp24a1, and 1,25(OH)2D3., (Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.)

Background and Purpose: Concentrations of 1α,25-dihydroxyvitamin D3 [1,25(OH)2 D3 ], the active ligand of the vitamin D receptor, are tightly regulated by CYP27B1 for synthesis and CYP24A1 for degradation. However, the dose-dependent pharmacokinetic (PK)-pharmacodynamic (PD) relationship between these enzymes and 1,25(OH)2 D3 concentrations has not been characterized., Experimental Approach: The pharmacokinetics of 1,25(OH)2 D3 were evaluated after administration of single (2, 60 and 120 pmol) and repeated (2 and 120 pmol q2d ×3) i.v. doses to male C57BL/6 mice. mRNA expression of CYP27B1 and CYP24A1 was examined by quantitative PCR and 1,25(OH)2 D3 concentrations were determined by enzyme immunoassay., Key Results: CYP27B1 and CYP24A1 changes were absent for the 2 pmol dose and biexponential decay profiles showed progressively shorter terminal half-lives with increasing doses. Fitting with a two-compartment model revealed decreasing net synthesis rates and increasing total clearances with dose, consistent with a dose-dependent down-regulation of renal CYP27B1 and the induction of renal/intestinal CYP24A1 mRNA expression. Upon incorporation of PD parameters for inhibition of CYP27B1 and induction of CYP24A1 to the simple two-compartment model, fitting was significantly improved. Moreover, fitted estimates for the 2 pmol dose, together with the PD parameters as modifiers, were able to predict profiles reasonably well for the higher (60 and 120 pmol) doses. Lastly, an indirect response model, which considered the synthesis and degradation of enzymes, adequately described the PK and PD profiles., Conclusions and Implications: The unique PK of exogenously administered 1,25(OH)2 D3 led to changes in PD of CYP27B1 and CYP24A1, which hastened the clearance of 1,25(OH)2 D3 ., (© 2015 The British Pharmacological Society.)

We applied physiologically based pharmacokinetic (PBPK) modeling to study the dose-dependent metabolism and excretion of verapamil and its preformed metabolite, norverapamil, to unravel the kinetics of norverapamil formation via N-demethylation. Various initial verapamil (1, 50, and 100 μM) and preformed norverapamil (1.5 and 5 μM) concentrations, perfused at 12 ml/min, were investigated in the perfused rat liver preparation. Perfusate and bile were collected over 90 minutes, and livers were harvested at the end of perfusion for high-performance liquid chromatography analysis. After correction for the adsorption of 10%-25% dose verapamil and norverapamil onto Tygon tubing and binding to albumin and red blood cell, fitting of verapamil and formed and preformed norverapamil data with ADAPT5 revealed nonlinearity for protein binding, N-demethylation (V(max,met1)(VER --> NOR) = 96.6 ± 33.4 nmol/min; K(m,met1)(VER --> NOR) = 10.4 ± 4.1 μM), formation of other metabolites (V(max,met2(VER -->others) 288 ± 51 nmol/min; K(m.met2)(VER -->others )= 14.1 ± 4.9 μM), as well as biliary excretion (V(max,sec)(VER)= 0.911 ± 0.505 nmol/min; K(m,sec)(VER) = 4.75 ± 2.29 μM). The hepatic clearance of verapamil (CL(L)(VER) decreased with the dose (8.16-10.2 ml/min), with values remaining high relative to perfusate blood flow rate among the doses. The hepatic clearance of preformed norverapamil (11 ml/min) remained unchanged for the concentrations studied and approximated perfusate blood flow rate, suggesting a high norverapamil extraction ratio. The fractional formation of norverapamil and biliary excretion of verapamil based on fitted constants were 31.1% and 0.64% of CL(L)(VER), respectively. Enantiomeric disposition and auto-inhibition of verapamil failed to perturb these estimaties according to PBPK modeling, due to the low values of the Michaelis-Menten constant, Km, and inhibition parameter, kI., (Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.)

We report a case of digital ischaemia in a 31-year-old man who presented with sudden hand numbness, swelling, and cyanosis 4 days after a jellyfish sting. This is a rare complication of jellyfish sting, characterised by a delayed but rapid downhill course. Despite serial monitoring with prompt fasciotomy and repeated debridement, he developed progressive ischaemia in multiple digits with gangrenous change. He subsequently underwent major reconstructive surgery and aggressive rehabilitation. Although jellyfish stings are not uncommon, no severe jellyfish envenomation has been reported in the past in Hong Kong and there has not been any consensus on the management of such injuries. This is the first local case report of jellyfish sting leading to serious hand complications. This case revealed that patients who sustain a jellyfish sting deserve particular attention to facilitate early detection of complications and implementation of therapy.

We demonstrate a role of the vitamin D receptor (VDR) in reducing cerebral soluble and insoluble amyloid-β (Aβ) peptides. Short-term treatment of two human amyloid precursor protein-expressing models, Tg2576 and TgCRND8 mice, with 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], the endogenous active ligand of VDR, resulted in higher brain P-glycoprotein (P-gp) and lower soluble Aβ levels, effects negated with coadministration of elacridar, a P-gp inhibitor. Long-term treatment of TgCRND8 mice with 1,25(OH)2D3 during the period of plaque formation reduced soluble and insoluble plaque-associated Aβ, particularly in the hippocampus in which the VDR is abundant and P-gp induction is greatest after 1,25(OH)2D3 treatment, and this led to improved conditioned fear memory. In mice fed a vitamin D-deficient diet, lower cerebral P-gp expression was observed, but levels were restored on replenishment with VDR ligands. The composite data suggest that the VDR is an important therapeutic target in the prevention and treatment of Alzheimer's disease., (Copyright © 2014 the authors 0270-6474/14/347091-11$15.00/0.)

Background & Aims: Little is known about the effects of the vitamin D receptor (VDR) on hepatic activity of human cholesterol 7α-hydroxylase (CYP7A1) and cholesterol metabolism. We studied these processes in mice in vivo and mouse and human hepatocytes., Methods: Farnesoid X receptor (Fxr)(-/-), small heterodimer partner (Shp)(-/-), and C57BL/6 (wild-type control) mice were fed normal or Western diets for 3 weeks and were then given intraperitoneal injections of vehicle (corn oil) or 1α,25-dihydroxyvitamin D3 (1,25[OH]2D3; 4 doses, 2.5 μg/kg, every other day). Plasma and tissue samples were collected and levels of Vdr, Shp, Cyp7a1, Cyp24a1, and rodent fibroblast growth factor (Fgf) 15 expression, as well as levels of cholesterol, were measured. We studied the regulation of Shp by Vdr using reporter and mobility shift assays in transfected human embryonic kidney 293 cells, quantitative polymerase chain reaction with mouse tissues and mouse and human hepatocytes, and chromatin immunoprecipitation assays with mouse liver., Results: We first confirmed the presence of Vdr mRNA and protein expression in livers of mice. In mice fed normal diets and given injections of 1,25(OH)2D3, liver and plasma concentrations of 1,25(OH)2D3 increased and decreased in unison. Changes in hepatic Cyp7a1 messenger RNA (mRNA) correlated with those of Cyp24a1 (a Vdr target gene) and inversely with Shp mRNA, but not ileal Fgf15 mRNA. Similarly, incubation with 1,25(OH)2D3 increased levels of Cyp24a1/CYP24A1 and Cyp7a1/CYP7A1 mRNA in mouse and human hepatocytes, and reduced levels of Shp mRNA in mouse hepatocytes. In Fxr(-/-) and wild-type mice with hypercholesterolemia, injection of 1,25(OH)2D3 consistently reduced levels of plasma and liver cholesterol and Shp mRNA, and increased hepatic Cyp7a1 mRNA and protein; these changes were not observed in Shp(-/-) mice given 1,25(OH)2D3 and fed Western diets. Truncation of the human small heterodimer partner (SHP) promoter and deletion analyses revealed VDR-dependent inhibition of SHP, and mobility shift assays showed direct binding of VDR to enhancer regions of SHP. In addition, chromatin immunoprecipitation analysis of livers from mice showed that injection of 1,25(OH)2D3 increased recruitment of Vdr and rodent retinoid X receptor to the Shp promoter., Conclusions: Activation of the VDR represses hepatic SHP to increase levels of mouse and human CYP7A1 and reduce cholesterol., (Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Previous studies have shown that 1α,25-dihydroxyvitamin D3 [1,25(OH)2 D3 ] treatment in mice resulted in induction of intestinal and renal Cyp24a1 and Trpv6 expression, increased hepatic Cyp7a1 expression and activity, as well as higher renal Mdr1/P-gp expression. The present study compared the equimolar efficacies of 1α-hydroxyvitamin D3 [1α(OH)D3 ] (6 nmol/kg i.p. q2d × 4), a lipophilic precursor with a longer plasma half-life that is converted to 1,25(OH)2 D3 , and 1,25(OH)2 D3 on vitamin D receptor (VDR) target genes. To clarify whether changes in VDR genes was due to VDR and not secondary, farnesoid X receptor (FXR)-directed effects, namely, lower Cyp7a1 expression in rat liver due to increased bile acid absorption, wildtype [fxr(+/+)] and FXR knockout [fxr(-/-)] mice were used to distinguish between VDR and FXR effects. With the exception that hepatic Sult2a1 mRNA was increased equally well by 1α(OH)D3 and 1,25(OH)2 D3 , 1α(OH)D3 treatment led to higher increases in hepatic Cyp7a1, renal Cyp24a1, VDR, Mdr1 and Mrp4, and intestinal Cyp24a1 and Trpv6 mRNA expression in both fxr(+/+) and fxr(-/-) mice compared to 1,25(OH)2 D3 treatment. A similar induction in protein expression and microsomal activity of hepatic Cyp7a1 and renal P-gp and Mrp4 protein expression was noted for both compounds. A higher intestinal induction of Trpv6 was observed, resulting in greater hypercalcemic effect following 1α(OH)D3 treatment. The higher activity of 1α(OH)D3 was explained by its rapid conversion to 1,25(OH)2 D3 in tissue sites, furnishing higher plasma and tissue 1,25(OH)2 D3 levels compared to following 1,25(OH)2 D3 -treatment. In conclusion, 1α(OH)D3 exerts a greater effect on VDR gene induction than equimolar doses of 1,25(OH)2 D3 in mice., (Copyright © 2013 John Wiley & Sons, Ltd.)

Unlabelled: Despite the impressive clinical activity of the second-generation antiandrogens enzalutamide and ARN-509 in patients with prostate cancer, acquired resistance invariably emerges. To identify the molecular mechanisms underlying acquired resistance, we developed and characterized cell lines resistant to ARN-509 and enzalutamide. In a subset of cell lines, ARN-509 and enzalutamide exhibit agonist activity due to a missense mutation (F876L) in the ligand-binding domain of the androgen receptor (AR). AR F876L is sufficient to confer resistance to ARN-509 and enzalutamide in in vitro and in vivo models of castration-resistant prostate cancer (CRPC). Importantly, the AR F876L mutant is detected in plasma DNA from ARN-509-treated patients with progressive CRPC. Thus, selective outgrowth of AR F876L is a clinically relevant mechanism of second-generation antiandrogen resistance that can potentially be targeted with next-generation antiandrogens., Significance: A missense mutation in the ligand-binding domain of the androgen receptor F876L confers resistance to the second-generation antiandrogens enzalutamide and ARN-509 in preclinical models of AR function and prostate cancer and is detected in plasma DNA from ARN-509-treated patients with progressive disease. These results chart a new path for the discovery and development of next-generation antiandrogens that could be coupled with a blood-based companion diagnostic to guide treatment decisions., (©2013 AACR.)

Background Focal chondral lesion is a common cause of chronic wrist pain. The best treatment remains unknown. We have developed a technique of arthroscopic transplantation of an osteochondral autograft from the knee joint to the distal radius with satisfactory clinical results. Materials and Methods Between December 2006 and December 2010, four patients (average age 31 years) with posttraumatic osteochondral lesions over the dorsal lunate fossa were treated with arthroscopic osteochondral grafting. Pre- and postoperative motion, grip strength, wrist functional performance score, pain score, and return to work status were charted. Postoperative computed tomography (CT) scan, magnetic resonance imaging (MRI), and second-look arthroscopy were performed to assess graft incorporation. Description of Technique With the arthroscope in the 3-4 portal, synovitis over the dorsal lunate fossa was débrided to uncover the underlying osteochondral lesion. We employed the 6-mm trephine of the Osteoarticular Transfer System (OATS) to remove the osteochondral defect. Osteochondral graft was harvested from the lateral femoral condyle and delivered into the wrist joint arthroscopically. Results In all cases, grafts incorporation was completed by 3-4 months postoperative. All patients showed improvement in the wrist performance score (preoperative 27.5, postoperative 39 out of 40) with no pain on final follow-up at average 48.5 months (range 24-68 months). Grip strength improved from 62.6 to 98.2% of the contralateral side. Motion improved from 115.5 to 131.3°. X-ray images showed preserved joint space. Patient satisfaction was high with no complication. Conclusion An arthroscopic-assisted transfer of an osteochondral graft is a viable treatment option for chondral defects of the distal radius.

The vitamin D receptor (VDR) maintains a balance of plasma calcium and 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], its natural active ligand, by directly regulating the calcium ion channel (TRPV6) and degradation enzyme (CYP24A1), and indirectly regulating the parathyroid hormone (PTH) for feedback regulation of the synthetic enzyme CYP27B1. Studies that examined the intricate relationships between plasma and tissue 1,25(OH)2D3 levels and changes in VDR target genes and plasma calcium and PTH are virtually nonexistent. In this study, we investigated temporal correlations between tissue 1,25(OH)2D3 concentrations and VDR target genes in ileum and kidney and plasma calcium and PTH concentrations in response to 1,25(OH)2D3 treatment in mice (2.5 μg/kg ip, singly or q2d × 4). After a single ip dose, plasma 1,25(OH)2D3 peaked at ∼0.5 h and then decayed biexponentially, falling below basal levels after 24 h and then returning to baseline after 8 days. Upon repetitive ip dosing, plasma, ileal, renal, and bone 1,25(OH)2D3 concentrations rose and decayed in unison. Temporal profiles showed increased expressions of ileal Cyp24a1 and renal Cyp24a1, Mdr1/P-gp, and VDR but decreased renal Cyp27b1 mRNA after a time delay in VDR activation. Increased plasma calcium and attenuated PTH levels and increased ileal and renal Trpv6 expression paralleled the changes in tissue 1,25(OH)2D3 concentrations. Gene changes in the kidney were more sustained than those in intestine, but the magnitudes of change for Cyp24a1 and Trpv6 were lower than those in intestine. The data revealed that 1,25(OH)2D3 equilibrates with tissues rapidly, and VDR target genes respond quickly to exogenously administered 1,25(OH)2D3.

Intestinal transporters and enzymes are factors that can influence the absorption of orally administrated drugs. Compartmental models are no longer adequate to describe the sequential handling of drugs and metabolites by the intestine and liver during oral drug absorption, especially when intestinal removal is substantial relative to the liver, and when induction/inhibition elicits different extents of change for identical intestinal and hepatic enzymes or transporters. In this review, we described PBPK models for the intestine (with differential flow patterns: traditional model, TM, and segregated flow model, SFM, and QGut model) as well as semi- or whole bodyphysiological- based pharmacokinetic (PBPK) models to describe the impact of the flow pattern, and the intestinal transporters and enzymes and their attendant heterogeneities on intestinal (FI or FG) and oral (Fsys) bioavailability. The modeling efforts have led to a refinement in providing mechanistic insight on the accurate prediction of drug and metabolite profiles for DDI, pharmacogenomics, age factors and disease conditions.

Induction of the multidrug resistance protein 1 (MDR1)/P-glycoprotein (P-gp) by the vitamin D receptor (VDR) was investigated in isolated rat brain capillaries and rat (RBE4) and human (hCMEC/D3) brain microvessel endothelial cell lines. Incubation of isolated rat brain capillaries with 10 nM of the VDR ligand, 1α,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] for 4 h increased P-gp protein expression fourfold. Incubation with 1,25(OH)(2)D(3) for 4 or 24 h increased P-gp transport activity (specific luminal accumulation of NBD-CSA, the fluorescent P-gp substrate) by 25-30%. In RBE4 cells, Mdr1b mRNA was induced in a concentration-dependent manner by exposure to 1,25(OH)(2)D(3). Concomitantly, P-gp protein expression increased 2.5-fold and was accompanied by a 20-35% reduction in cellular accumulation of the P-gp substrates, rhodamine 6G (R6G), and HiLyte Fluor 488-labeled human amyloid beta 1-42 (hAβ(42)). In hCMEC/D3 cells, a 3 day exposure to 100 nM 1,25(OH)(2)D(3) increased MDR1 mRNA expression (40%) and P-gp protein (threefold); cellular accumulation of R6G and hAβ(42) was reduced by 30%. Thus, VDR activation up-regulates Mdr1/MDR1 and P-gp protein in isolated rat brain capillaries and rodent and human brain microvascular endothelia, implicating a role for VDR in increasing the brain clearance of P-gp substrates, including hAβ(42), a plaque-forming precursor in Alzheimer's disease., (© 2012 International Society for Neurochemistry.)

Physiologically based pharmacokinetic (PBPK) models for the intestine, comprising of different flow rates perfusing the enterocyte region, were revisited for appraisal of flow affects on the intestinal availability (F(I)) and, in turn, the systemic availability (F(sys)) and intestinal versus liver contribution to the first-pass effect during oral drug absorption. The traditional model (TM), segregated flow model (SFM), and effective flow (Q(Gut)) model stipulate that 1.0, ∼0.05 to 0.3, and ≤0.484× of the total intestinal flow, respectively, reach the enterocyte region that houses metabolically active and transporter-enriched enterocytes. The fractional flow rate to the enterocyte region (f(Q)), when examined under varying experimental conditions, was found to range from 0.024 to 0.2 for the SFM and 0.065 to 0.43 for the Q(Gut) model. Appraisal of these flow intestinal models, when used in combination with whole-body PBPK models, showed the ranking as SFM < Q(Gut) model < TM in the description of F(I), and the same ranking existed for the contribution of the intestine to first-pass removal. However, the ranking for the predicted contribution of hepatic metabolism, when present, to first-pass removal was the opposite: SFM > Q(Gut) model > TM. The findings suggest that the f(Q) value strongly influences the rate of intestinal metabolism (F(I) and F(sys)) and indirectly affects the rate of liver metabolism due to substrate sparing effect. Thus, the f(Q) value in the intestinal flow models pose serious implications on the interpretation of data on the first-pass effect and oral absorption of drugs.

Arthroscopic surgery has become the gold standard for the diagnosis and treatment of major joint disorders. With advancement in arthroscopic technique, arthroscopy has become feasible in most human joints, even those as small as the finger joints. The metacarpophalangeal joint (MCPJ) can become spacious with simple traction, the intra-articular anatomy is simple, and its major structures can be easily visualized and identified. However, MCPJ arthroscopy has never been popular. This article describes our experience with MCPJ arthroscopy and seeks to establish its role in clinical practice., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Secondary farnesoid X receptor (FXR) effects, in addition to vitamin D receptor (VDR) effects, were observed in the rat liver after treatment with 1α,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], the natural ligand of VDR, caused by increased bile acid absorption as a consequence of apical sodium-dependent bile acid transporter induction. To investigate whether the increased multidrug resistance protein 1 (Mdr1)/P-glycoprotein (P-gp) expression in the rat liver and kidney was caused by the VDR and not the FXR, we examined changes in Mdr1/P-gp expression in fxr(+/+) and fxr(-/-) mice after intraperitoneal dosing of vehicle versus 1,25(OH)(2)D(3) (0 or 2.5 μg/kg every other day for 8 days). Renal and brain levels of Mdr1 mRNA and P-gp protein were significantly increased in both fxr(+/+) and fxr(-/-) mice treated with 1,25(OH)(2)D(3), confirming that Mdr1/P-gp induction occurred independently of the FXR. Increased P-gp function was evident in 1,25(OH)(2)D(3)-treated fxr(+/+) mice given intravenous bolus doses of the P-gp probe, [(3)H]digoxin (0.1 mg/kg). Decreased blood (24%) and brain (29%) exposure, estimated as reduced areas under the curve, caused by increased renal (74%) and total body (34%) clearances of digoxin, were observed in treated mice. These events were predicted by physiologically based pharmacokinetic modeling that showed increased renal secretory intrinsic clearance (3.45-fold) and brain efflux intrinsic clearance (1.47-fold) in the 1,25(OH)(2)D(3)-treated mouse, trends that correlated well with increases in P-gp protein expression in tissues. The clearance changes were less apparent because of the high degree of renal reabsorption of digoxin. The observations suggest an important role of the VDR in the regulation of P-gp in the renal and brain disposition of P-gp substrates.

Effects of 1.28 nmol/kg doxercalciferol [1α(OH)D₂], a synthetic vitamin D₂ analog that undergoes metabolic activation to 1α,25-dihydroxyvitamin D₂, the naturally occurring, biologically active form of vitamin D₂, on rat transporters and enzymes were compared with those of 1α,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃, active form of vitamin D₃; 4.8 and 6.4 nmol/kg] given on alternate days intraperitoneally for 8 days. Changes were mostly confined to the intestine and kidney where the vitamin D receptor (VDR) was highly expressed: increased intestinal Cyp24 and Cyp3a1 messenger RNA (mRNA) and a modest elevation of apical sodium-dependent bile salt transporter (Asbt) and P-glycoprotein (P-gp) protein; increased renal VDR, Cyp24, Cyp3a9, Mdr1a, and Asbt mRNA, as well as Asbt and P-gp protein expression; and decreased renal PepT1 and Oat1 mRNA expression. In comparison, 1α(OH)D₂ treatment exerted a greater effect than 1,25(OH)₂D₃ on Cyp3a and Cyp24 mRNA. However, the farnesoid X receptor -related repressive effects on liver Cyp7a1 were absent because intestinal Asbt, FGF15 and portal bile acid concentrations were unchanged. Rats on the alternate day regimen showed milder changes and lessened signs of hypercalcemia and weight loss compared with rats receiving daily injections (similar or greater amounts of 0.64-2.56 nmol/kg daily ×4) described in previous reports, showing that the protracted pretreatment regimen was associated with milder inductive and lesser toxic effects in vivo., (Copyright © 2010 Wiley-Liss, Inc.)

Previous studies have shown that 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) treatment (2.56 nmol/kg i.p. daily×4) increased PepT1, Mrp2, Mrp4, Asbt, but not Mdr1/P-gp in the rat small intestine. In this study, the intestinal everted sac technique, together with various select probes: mannitol (paracellular transport), glycylsarcosine (PepT1), 5(and 6)-carboxy-2',7'-dichlorofluorescein (CDF) diacetate (precursor of CDF for Mrp2), adefovir dipivoxil (precursor of adefovir for Mrp4) and digoxin (P-gp) was used to examine the functional changes of these transporters. After establishing identical permeabilities (Papp) of mannitol for the apical-to-basolateral (A-to-B) and basolateral-to-apical (B-to-A) directions at 20 min in 1,25(OH)2D3-treated vs. vehicle-treated duodenal, jejunal and ileal everted sacs, a significant enhancement of net A-to-B transport of glycylsarcosine in the duodenum, increased B-to-A transport of CDF and A-to-B and B-to-A transport of adefovir in the jejunum were observed with 1,25(OH)2 D3 treatment. However, the A-to-B and B-to-A transport of digoxin in the ileum was unchanged. These changes in transporter function in the rat intestinal everted sac corresponded well to changes in proteins that were observed previously. This study confirms that the rat intestinal PepT1, Mrp2 and Mrp4, but not P-gp are functionally induced by 1,25(OH)2D3 treatment via the vitamin D receptor (VDR)., (Copyright © 2011 John Wiley & Sons, Ltd.)

The effects of the secondary bile acid, lithocholic acid (LCA), a VDR, FXR and PXR ligand, on the regulation of bile acid metabolism (CYP3A isozymes), synthesis (CYP7A1), and transporter proteins (MRP3, MRP2, BSEP, NTCP) as well as nuclear receptors (FXR, PXR, LXRα, HNF1α, HNF4α and SHP) were studied in rat and human precision-cut intestine and liver slices at the mRNA level. Changes due to 5 to 10 μM of LCA were compared to those of other prototype ligands for VDR, FXR, PXR and GR. LCA induced rCYP3A1 and rCYP3A9 in the rat jejunum, ileum and colon, rCYP3A2 only in the ileum, rCYP3A9 expression in the liver, and CYP3A4 in the human ileum but not in liver. LCA induced the expression of rMRP2 in the colon but not in the jejunum and ileum but did not affect rMRP3 expression along the length of the rat intestine. In human ileum slices, LCA induced hMRP3 and hMRP2 expression. In rat liver slices, LCA decreased rCYP7A1, rLXRα and rHNF4α expression, induced rSHP expression, but did not affect rBSEP or rNTCP expression; whereas in the human liver, a small but significant decrease was found for hHNF1α expression. These data suggests profound species differences in the effects of LCA on bile acid transport, synthesis and detoxification. An examination of the effects of prototype VDR, PXR, GR and FXR ligands showed that these pathways are all intact in precision cut slices and that LCA exerted VDR, PXR and FXR effects. The LCA-induced altered enzymes and transporter expressions in the intestine and liver would affect the disposition of drugs., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Experimental strategies have long been applied for in vitro or in vivo evaluation of the effect of transporters and/or enzymes on the bioavailability. However, the lack of specific inhibitors or inducers of transporters and enzymes and the multiplicity of nuclear receptors in gene regulation and cross talk have led to compromised assessment of these effects in vivo. These and other causes have resulted in confusion and controversy in transporter-enzyme interplay. In this review, physiologically-based pharmacokinetic (PBPK) intestinal and liver models are utilized to predict the contributions of enzymes and transporters on intestinal availability (F(I)) and hepatic availability (F(H)), with the aim to fully understand the impact of these variables on bioavailability (F(sys)) in vivo. We emphasize the often overlooked impact of influx and efflux clearances, and apply the PBPK models and their solutions to examine individual organ clearances of the intestine and the liver. In order to accurately predict oral bioavailability, these organ models are incorporated into the whole body PBPK model, and additional complicated scenarios such as segmental differences and zonal heterogeneity of transporters and enzymes in the intestine and liver and segregated blood flow patterns of the intestine are further discussed. The sequential metabolism of a drug to form primary and secondary metabolites in the first-pass organs is considered in PBPK modeling, revealing that the segregated flow model (SFM) of the intestine is more appropriate than the traditional PBPK intestinal model (TM). Examples are included to highlight the potential application of these PBPK models on the quantitative prediction of bioavailability.

1alpha,25-Dihydroxyvitamin D3 (1,25(OH)2D3), the natural ligand of the vitamin D receptor (VDR), was found to regulate bile acid related transporters and enzymes directly and indirectly in the rat intestine and liver in vivo. The kidney is another VDR-rich target organ in which VDR regulation on xenobiotic transporters and enzymes is ill-defined. Hence, changes in protein and mRNA expression of nuclear receptors, transporters and enzymes of the rat intestine and kidney in response to 1,25(OH)2D3 treatment (0 to 2.56 nmol/kg/day intraperitoneally in corn oil for 4 days) were studied. In the intestine, protein and not mRNA levels of Mrp2, Mrp3, Mrp4 and PepT1 in the duodenum and proximal jejunum were induced, whereas Oat1 and Oat3 mRNA were decreased in the ileum after 1,25(OH)2D3 treatment. In the kidney, VDR, Cyp24, Asbt and Mdr1a mRNA and protein expression increased significantly (2- to 20-fold) in 1,25(OH)2D3-treated rats, and a 28-fold increase of Cyp3a9 mRNA but not of total Cy3a protein nor Cyp3a1 and Cyp3a2 mRNA was observed, implicating that VDR played a significant, renal-specific role in Cyp3a9 induction. Additionally, renal mRNA levels of PepT1, Oat1, Oat3, Ostalpha, and Mrp4, and protein levels of PepT1 and Oat1 were decreased in a dose-dependent manner, and the approximately 50% concomitant reduction in FXR, SHP, HNF-1alpha and HNF-4alpha mRNA expression suggests the possibility of cross-talk among the nuclear receptors. It is concluded that the effects of 1,25(OH)2D3 changes are tissue-specific, differing between the intestine and kidney which are VDR-rich organs.

1alpha,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), a natural ligand of the vitamin D receptor (VDR), was found to increase the rat ileal Asbt and bile acid absorption. The effects of VDR, whose expression is low in liver, on hepatic transporters and enzymes are unknown. Protein and mRNA levels of target genes in the small intestine, colon and liver after intraperitoneal dosing of 1,25(OH)(2)D(3) (0-2.56 nmol/kg/day for 4 days) to the rat were determined by Western blotting and qPCR, respectively. The 1,25(OH)(2)D(3) treatment increased total Cyp3a protein and Cyp3a1 mRNA expressions in the proximal small intestine, and the short heterodimer partner (SHP), the fibroblast growth factor 15 (FGF15), organic solute transporter (Ostalpha and Ostbeta) mRNA and Asbt protein expressions in the ileum. About 50% higher portal bile acid concentration (65.1+/-14.9 vs 41.9+/-7.8 microm, p<0.05) and elevated expressions of the hepatic farnesoid X receptor (FXR) and SHP mRNA resulted with 1,25(OH)(2)D(3) treatment. Increased Bsep and Ostalpha mRNA expressions in liver and a>50% reduction in the Cyp7a1 protein level (p<0.05) and cholesterol metabolism in rat liver microsomes (p=0.002), likely consequences of the bile acid-FXR-SHP cascade and activation of the signaling pathway for Cyp7a1 inhibition by FGF15, were found. Increased hepatic multidrug resistance-associated protein (Mrp3) and multidrug resistance protein 1a (Mdr1a) mRNA and P-gp protein were also observed. It was concluded that the changes in hepatic transporters and enzymes in the rat were indirect, secondary effects of the liver FXR-SHP cascade due to increased intestinal absorption of bile acids and elevated levels of FGF15, events that led to the activation of FXR.

Purpose: Sunitinib has demonstrated antitumor activity in metastatic renal cell carcinoma (mRCC) when given at 50 mg/d on a 4-weeks-on 2-weeks-off regimen. Herein, we report results of an open-label, multicenter phase II mRCC study of sunitinib administered on a continuous once-daily dosing regimen., Patients and Methods: Eligibility criteria included histologically proven mRCC with measurable disease, failure of one prior cytokine regimen, and good performance status. Patients were randomly assigned to a sunitinib starting dose of 37.5 mg/d in the morning (AM) or evening (PM). RECIST-defined objective response rate (ORR) was the primary end point. Secondary end points included progression-free survival (PFS), overall survival (OS), adverse events (AEs), and quality-of-life measures., Results: One hundred seven patients were randomly assigned to AM (n = 54) or PM (n = 53) dosing and on study for a median 8.3 months. Eighty-three patients discontinued, 65 due to disease progression and 16 because of AEs; two patients withdrew consent. Dosing was reduced to 25 mg/d in 46 patients (43%) due to grade 3/4 AEs. The most common grade 3 treatment-related AEs were asthenia/fatigue (16%), diarrhea (11%), hypertension (11%), hand-foot syndrome (9%), and anorexia (8%). ORR was 20% with a 7.2-month median response duration. Median PFS and OS were 8.2 and 19.8 months, respectively, at median follow-up of 26.4 months. Efficacy, tolerability, and quality-of-life results were similar between patients dosed in the AM or PM., Conclusion: Sunitinib 37.5 mg, administered on a continuous once-daily dosing regimen, has a manageable safety profile as second-line mRCC therapy, providing flexible dosing, which can be explored in combination studies.

The regulation of the OSTalpha and OSTbeta expression was studied in the rat jejunum, ileum, colon and liver and in human ileum and liver by ligands for the farnesoid X receptor (FXR), pregnane X receptor (PXR), vitamin D receptor (VDR) and glucocorticoid receptor (GR) using precision cut tissue slices. The gradient of protein and mRNA expression in segments of the intestine for rOSTalpha and rOSTbeta paralleled that of rASBT. OSTalpha and OSTbeta mRNA expression, quantified by qRT-PCR, in rat jejunum, ileum, colon and liver, and in human ileum and liver was positively regulated by FXR and GR ligands. In contrast, the VDR ligand, 1,25(OH)2D3 decreased the expression of rOSTalpha-rOSTbeta in rat intestine, but had no effect on human ileum, and rat and human liver slices. Lithocholic acid (LCA) decreased the expression of rOSTalpha and rOSTbeta in rat ileum but induced OSTalpha-OSTbeta expression in rat liver slices, and human ileum and liver slices. The PXR ligand, pregnenolone-16alpha carbonitrile (PCN) had no effect. This study suggest that, apart from FXR ligands, the OSTalpha and OSTbeta genes are also regulated by VDR and GR ligands and not by PXR ligands. This study show that VDR ligands exerted different effects on OSTalpha-OSTbeta in the rat and human intestine and liver compared with other nuclear receptors, FXR, PXR, and GR, pointing to species- and organ-specific differences in the regulation of OSTalpha-OSTbeta genes., (Copyright 2009 John Wiley & Sons, Ltd.)

In this study, we compared the regulation of CYP3A isozymes by the vitamin D receptor (VDR) ligand 1 alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) against ligands of the pregnane X receptor (PXR), the glucocorticoid receptor (GR) and the farnesoid X receptor (FXR) in precision-cut tissue slices of the rat jejunum, ileum, colon and liver, and human ileum and liver. In the rat, 1,25(OH)(2)D(3) strongly induced CYP3A1 mRNA, quantified by qRT-PCR, along the entire length of the intestine, induced CYP3A2 only in ileum but had no effect on CYP3A9. In contrast, the PXR/GR ligand, dexamethasone (DEX), the PXR ligand, pregnenolone-16 alpha carbonitrile (PCN), and the FXR ligand, chenodeoxycholic acid (CDCA), but not the GR ligand, budesonide (BUD), induced CYP3A1 only in the ileum, none of them influenced CYP3A2 expression, and PCN, DEX and BUD but not CDCA induced CYP3A9 in jejunum, ileum and colon. In rat liver, CYP3A1, CYP3A2 and CYP3A9 mRNA expression was unaffected by 1,25(OH)(2)D(3), whereas CDCA decreased the mRNA of all CYP3A isozymes; PCN induced CYP3A1 and CYP3A9, BUD induced CYP3A9, and DEX induced all three CYP3A isozymes. In human ileum and liver, 1,25(OH)(2)D(3) and DEX induced CYP3A4 expression, whereas CDCA induced CYP3A4 expression in liver only. In conclusion, the regulation of rat CYP3A isozymes by VDR, PXR, FXR and GR ligands differed for different segments of the rat and human intestine and liver, and the changes did not parallel expression levels of the nuclear receptors.

The transport and metabolism of baicalein (Ba) was studied in vitro and in Caco-2 cells. Protein binding of Ba with Caco-2 lysate showed that Ba was bound to two classes of sites: a higher affinity, lower capacity site (K(A1) = 27.6 +/- 4.7 microM(-1), n(1) = 10.6 +/- 0.6 nmol/mg) and lower affinity, higher capacity site (K(A2) = 0.015 +/- 0.0013 microM(-1), n(2) = 413 +/- 21 nmol/mg). Incubation studies of Ba with Caco-2 lysate showed substrate inhibition of both glucuronidation and sulfation, with K(m) values of 0.14 +/- 0.034 and 0.015 +/- 0.0053 microM, and K(I) values of 6.75 +/- 1.70 and 0.37 +/- 0.16 microM, respectively. In the Caco-2 monolayer, Ba (8-47 microM) displayed good apparent permeabilities (P(app)) across the membrane; P(app) was found to be increased with elevated loading concentration in both the absorptive and secretory directions. However, the efflux ratio was less than unity, negating the involvement of apical efflux transporters. The concentration ratios of Ba sulfate (BS) and glucuronide (BG) decreased with increased loading Ba concentration, suggesting that BS and BG are apically excreted via transporters, likely breast cancer resistance protein and multidrug resistance-associated protein 2, respectively. Data fit to the catenary model, composed of basolateral, cellular, and apical compartments, showed a low cellular unbound fraction (0.0019 +/- 0.00018), a high passive diffusion clearance (0.012 +/- 0.00029 ml/min/mg), and substrate inhibition, with sulfation being more readily saturated and inhibited than glucuronidation, as evidenced by smaller K(m) value (0.35 +/- 0.078 versus 1.95 +/- 0.57 microM) and K(I) value (0.58 +/- 0.20 versus 7.90 +/- 1.10 microM); these patterns paralleled those observed in the lysate incubation studies. The results showed that the catenary model aptly predicts substrate inhibition kinetics and offers significant and mechanistic insight into the transport and atypical metabolism of drugs in the Caco-2 monolayer.

The role of haptoglobin in liver cell entry of acellular native hemoglobin, and cross-linked human hemoglobin, a potentially useful oxygen-carrier alternative in transfusion medicine, was examined in the recirculating, perfused rat liver preparation. Doses of tritiated native human or beta-chain [trimesoyl-(Lys82)beta-(Lys82)beta] cross-linked human hemoglobin were preincubated with haptoglobin-containing rat plasma or Krebs Henseleit bicarbonate buffer for 30 min and used for perfusion. Concentrations (dpm/ml) in reservoir, before and after separation of the hemoglobins and metabolites by gel filtration fast protein liquid chromatography column chromatography, were similar, showing mostly the presence of intact hemoglobin. Each hemoglobin species underwent a rapid distribution phase, followed by a protracted elimination phase. The radioactivity in bile at 3 h consisted of low molecular weight metabolites, and cumulative excretion was slightly higher when rat plasma was present: for native hemoglobin, 7.1 +/- 1.6% versus 9.2 +/- 2.1% dose; for cross-linked hemoglobin, 5.0 +/- 1.7% versus 7.2 +/- 0.8% dose. Data fit to a two-compartment model and physiologically based model revealed a significantly faster influx clearance (CL(influx)) over the metabolic intrinsic clearance (CL(int, met)). The ratios of CL(influx)/CL(int, met) were 125 and 535 for native hemoglobin in the absence and presence of rat haptoglobin, respectively, according to compartmental analyses; the ratios were 25 and 53, respectively, according to physiological modeling. The corresponding ratios for cross-linked hemoglobin in the absence and presence of rat haptoglobin were 55 and 81, respectively, and 24 and 70 for compartmental and physiological modeling. Although haptoglobin enhanced the hepatic internalization of the hemoglobins, the impact on the net clearance was lessened since degradation was the rate-limiting step.

Background: The Caco-2 monolayer has been used extensively for the high-throughput screening of drug permeability and identification of substrates, inhibitors, and inducers of intestinal transporters, especially P-glycoprotein (P-gp). Traditionally, the Caco-2 monolayer is viewed as a single barrier rather than a polarized cell monolayer consisting of metabolic enzymes that are sandwiched between two membrane barriers with distinctly different transporters., Objective: This review addressed the usefulness and limitations of the Caco-2 cell monolayer in drug discovery and mechanistic studies., Methods: This mini-review covered applications of the Caco-2 monolayer, clarified misconceptions, and critically addressed issues on data interpretation., Conclusion: The catenary model extends the usefulness of Caco-2 monolayer and provides proper mechanistic insight and data interpretation.

Bis(7)-tacrine was previously demonstrated as an antagonist of gamma-aminobutyric acid type A (GABA(A)) receptors. In this study, the effects of a series of alkylene-linked tacrine dimers on GABA(A) receptors were examined. In radioligand binding assay, the analogues differed in binding affinity for GABA(A) receptors, and potency monotonically increased as the tether was shortened from nine to two methylenes. Bis(2)-tacrine, the shortest tacrine dimer, could displace [(3)H]muscimol from rat brain membranes with an IC(50) of 0.48 microM, which was 11, 13 and 525 times more potent than the GABA(A) receptor antagonist (+)-bicuculline, bis(7)-tacrine and tacrine, respectively. In whole-cell patch-clamp recordings, these dimeric tacrine analogues competitively antagonized GABA-induced inward current with a rank order of potency of bis(2)-tacrine>bicuculline>bis(7)-tacrine>bis(9)-tacrine>tacrine, and the potency of bis(2)-tacrine was 11, 18 and 487 times higher than that of (+)-bicuculline, bis(7)-tacrine and tacrine, respectively. Bis(2)-tacrine shifted the GABA concentration-response curve to the right in a parallel manner, and the inhibition was voltage-independent between -80 and +20 mV. It can be concluded that the shorter the alkylene linkage in tacrine dimers the stronger the binding affinity and higher the antagonistic effect on the GABA(A) receptor will be.

Endochondral ossification is recapitulated during bone morphogenetic protein (BMP)-induced ectopic bone formation. Although BMP and beta-catenin have been investigated in bone development and in mesenchymal cells, how they interact in this process is not clear. We implanted recombinant BMP-2 into the muscle of mice to investigate the effect of beta-catenin signaling on BMP-induced in vivo endochondral bone formation. BMP-2 induced expression of several Wnt ligands and their receptors and also activated beta-catenin-mediated T cell factor-dependent transcriptional activity. An adenovirus expressing Dickkopf-1 (Dkk-1, an inhibitor of canonical Wnt pathway) inhibited beta-catenin signaling and endochondral bone formation. Interestingly, Dkk-1 inhibited both chondrogenesis and osteogenesis. Likewise, mice expressing conditional beta-catenin null alleles also displayed an inhibition of BMP-induced chondrogenesis and osteogenesis. This is in contrast to studies of embryonic skeletogenesis, which demonstrate that beta-catenin is required for osteogenesis but is dispensable for chondrogenesis. These findings suggest that embryonic development pathways are not always recapitulated during post-natal regenerative processes, and the biochemical pathways utilized to regulate cell differentiation may be different. During in vivo ectopic bone formation, BMP-2 induces beta-catenin-mediated signaling through Wnt ligands, and beta-catenin is required for both chondrogenesis and osteogenesis.