On the local warming potential of urban rooftop photovoltaic solar panels in cities.

Understanding and evaluating the implications of photovoltaic solar panels (PVSPs) deployment on urban settings, as well as the pessimistic effects of densely populated areas on PVSPs efficiency, is becoming incredibly valuable. Thus, the deployment of low-efficiency, low-cost, and widely available PVSPs may diminish total solar reflectance, raising the risks of PVSPs-based urban heating, particularly during the summertime heatwaves. This study employs and assesses physical parameterizations that account for the impact of PVSPs on Sydney's urban environment in the context of the mesoscale model weather research and forecasting (WRF). To account for the impacts of PVSPs, the parameterization presented in this paper assumes that PVSP arrays are parallel, detachable from roofs, and consist of a single layer. Results showed that increasing PVSPs can raise peak summer ambient temperatures by up to 1.4 °C and surface temperatures by up to 2.3°C at city-scale. Temperature variability was found between the city's eastern and western parts due to the presence of PVSPs. In addition, local warming effects of PVSP were observed at urban district-scale as well. The large-scale deployment of PVSPs at local district-scale of the Sydney during a typical hot day caused air temperature to rise by 1.5 °C during the daytime and decrease by 2.7 °C at nighttime. The patterns of the city's ambient temperature distribution were found to be strongly dependent on synoptic meteorological conditions and advection flow strength. The maximum increases in sensible heat flux and latent heat flux were 245.5 Wm-2 and 11.5 Wm-2, respectively. Wind speed may be raised by up to 1.2 ms-2 due to regional low effect over city domain. As a result, large-scale deployment of PVSPs promotes advective flow between the city and its environs. Modification of the PVSPs in Sydney results in an increase in planetary boundary layer (PBL) heights of up to 537.9 m above the city and may lower pollutant concentrations at ground level. The advent of sea breeze in the city's eastern parts, which reduces the temperature of the coastal zone, along with inland westerly winds, which heat the city's western zones, lessened the intensity of the urban heat island (UHI) phenomenon induced by PVSPs warming. The findings of this study can be used to help policymakers make informed decisions about the use of PVSPs systems. PVSPs with a high solar reflectance in wavelengths that do not convert solar energy to electricity can be considered as an alternative solution to reduce local warming in urban environments.

Focal Cryoablation of the Prostate: Primary Treatment in 163 Patients With Localized Prostate Cancer.

Objective Whole gland treatment of the prostate has known efficacy in treating many grades of prostate cancer. However, it is often associated with increased morbidity, including erectile dysfunction and urinary incontinence. Focal ablative therapies, including focal cryoablation (FC), are utilized to minimize the risk of tumor progression and preserve erectile and urinary function. There is little to no consensus on whether intermediate or high-risk prostate cancer should be treated with focal therapy. However, there is a growing body of literature on the effectiveness of FC as an effective means of prostate cancer control. We characterize our experience with 163 patients who underwent FC with a median follow-up of 39 months (IQR: 24-60). Methods A 163-patient retrospective cohort underwent FC of the prostate at a single clinic by a physician from November 2008 to December 2020. Each of these T1c patients in this single-tail study was monitored for biochemical recurrence (BCR) and oncologic outcomes. American Society for Radiation Oncology (ASTRO) definition of BCR is three consecutive prostate-specific antigens (PSA) increases of more than 0.5 ng/mL or, along with the utilization of the Phoenix definition, a PSA greater than nadir by 2 ng/mL was used to define BCR. This study's primary endpoint includes BCR or biochemical disease-free survival rates. Secondary endpoints include patient side effects, such as measuring for urinary incontinence and outcomes of salvage treatments. Cox proportional hazard analyses defined univariate HRs and 95% CIs for pre-operative PSA (POPSA), Decipher, and Gleason Grade Groups (GGGs) to determine the prognostic impact of pathologic factors. Statistical analysis and BCR timeline analysis also included logistic regression and the Kaplan-Meier method, with significance considered at p < 0.05. Select focal cryotherapy patients were monitored utilizing genomic sequencing tests. Results Our cohort included 27 patients (16.5%) with D'Amico low, 115 patients (70.5%) with intermediate, and 23 patients (14.1%) with high-risk prostate cancers. One month after FC, a 73% reduction in PSA resulted in a median post-operative PSA of 1.39 ng/mL (IQR: 0.46-2.80 ng/mL). At five years, our cohort yielded biochemical disease-free recurrence rates of 78%, 74%, and 55% for low, intermediate, and high-grade cancers, respectively. Genetic risk stratification results showed very similar BCR rates to patients whose tissues did not undergo genomic testing, at 27%, 26%, and 46% for low, intermediate, and high-grade cancers, respectively. Log-rank tests to map for BCR and HRs for pathologic factors did not yield any statistically significant predictive results. Urinary incontinence and erectile dysfunction were reported in 1.8% and 3.1% of patients in the focal cohort. Conclusions Our results add to the expanding body of literature around the efficacy of focal ablative therapies in contrast to whole gland treatment. The definitive extent of FC's efficacy still remains to be explored, but our conclusions demonstrate favorable PSA kinetics at five years follow-up.

Spatial patterns of health vulnerability to heatwaves in Vietnam.

The increasing frequency and intensity of heat events have weighty impacts on public health in Vietnam, but their effects vary across regions. In this study, we have applied a vulnerability assessment framework (VAF) to systematically assess the spatial pattern of health vulnerability to heatwaves in Vietnam. The VAF was computed as the function of three dimensions: exposure, sensitivity, and adaptive capacity, with the indicators for each dimension derived from the relevant literature, consultation with experts, and available data. An analytic hierarchy process (AHP) was used to determine the weight of indicators. Each province in Vietnam's vulnerability to the health impacts of heatwaves was evaluated by applying the vulnerability index, computed using 13 indicators (sensitivity index, 9; adaptive capacity index, 3; and exposure index, 1). As a result of this analysis, this study has identified heatwave vulnerability 'hotspots', primarily in the Southeast, Central Highlands, and South Central Coast of Vietnam. However, these hotspots are not necessarily the same as the area most vulnerable to climate change, because some areas that are more sensitive to heatwaves may have a higher capacity to adapt to them due to a host of factors including their population characteristics (e.g. rates of the elderly or children), socio-economic and geographical conditions, and the availability of air-conditioners. This kind of information, provided by the vulnerability index framework, allows policymakers to determine how to more efficiently allocate resources and devise appropriate interventions to minimise the impact of heatwaves with strategies tailored to each region of Vietnam.

Identification, isolation and characterization of dolutegravir forced degradation products and their cytotoxicity potential.

Dolutegravir was approved by USFDA, Canada and European regulatory authorities as antiretroviral medication. In this article, DLG forced degradation studies as per the International Council for Harmonization (ICH) prescribed stress conditions was conducted and the resulting degradants were fully characterized. DLG was stable in basic, thermal and photolytic stress conditions, whereas DLG was found to unstable in acidic and oxidative conditions. One degradant each from acid and peroxide treated solutions was resolved on LC-MS and labelled as DP-1 and DP-2 with RT 1.80 min and 1.41 min, respectively. DP-1 and DP-2 were isolated by preparative HPLC with C18 column using gradient elution method. Subsequently DP-1 and DP-2 peaks were subjected to HRMS for accurate mass. Molecular mass of DP-1 and DP-2 were m/z 420.1379 (positive mode) and m/z 214.0319 (negative mode), respectively. Further, DP-1 & DP-2 were subjected to NMR spectroscopic analysis (including 2D) for structural confirmation. DP-1 was identified as N-(2,4-difluorobenzyl)-9-hydroxy-2-(4-hydroxybutan-2-yl)-1,8-dioxo-2,8-dihydro-1H-pyrido[1,2-a]pyrazine-7-carboxamide and it is earlier reported by Gudisela et al. [19] as DLG process impurity. DP-2 was identified as 2-(2,4difluorobenzylamino)-2-oxoacetic acid which is novel DLG degradant and not reported earlier to the best of our knowledge. DLG along its forced degradation products were found to be non-cytotoxic in in vitro assay conditions using HepG2 cells.

Real-World Evidence of Prostatic Urethral Lift Confirms Pivotal Clinical Study Results: 2-Year Outcomes of a Retrospective Multicenter Study.

Introduction: This study expands results from recent prostatic urethral lift (PUL) clinical trials by examining outcomes within a large unconstrained multicenter data set. Methods: Retrospective chart review and analysis of 1413 consecutive patients who received PUL in North America and Australia was performed. International Prostate Symptom Score (IPSS), quality of life (QoL), and maximum urinary flow rate (Qmax) were evaluated at 1, 3, 6, 12, and 24 months post-procedure for all nonurinary retention subjects (Group A) and retention subjects (Group B). Within Group A outcomes were further analyzed using paired t-tests and 95% mean confidence intervals under the following parameters: IPSS baseline ≥13, age, prostate size, site of service, prostate cancer treatment, and diabetic status. Adverse events, surgical interventions, and catheterization rates were summarized in detail. Results: Compared with the randomized controlled prosatic urethral lift (L.I.F.T.) study, subjects in this retrospective study were older and less symptomatic. After PUL, mean IPSS for Group A improved significantly from baseline by at least 8.1 points throughout follow-up. No significant differences were observed between Group A and B follow-up symptom scores. Within Group A, subjects with an IPSS baseline ≥13 behaved similarly to L.I.F.T. subjects. Age, prostate volume, site of service, prior cancer treatment, and diabetic status did not significantly affect PUL outcomes. When completed in a clinic office, PUL resulted in less side effects and catheter placement compared to other sites of service. Previous prostate cancer treatment did not elevate adverse events of high concern such as incontinence and infection. Conclusion: PUL performs well in a real-world setting in terms of symptom relief, morbidity, and patient experience for all studied patient cohorts.

Simulating micro-scale thermal interactions in different building environments for mitigating urban heat islands.

Tropical cities are more susceptible to the suggested fall outs from projected global warming scenarios as they are located in the Torrid Zone and growing at rapid rates. Therefore, research on the mitigation of urban heat island (UHI) effects in tropical cities has attained much significance and increased immensely over recent years. The UHI mitigation strategies commonly used for temperate cities need to be examined in the tropical context since the mechanism of attaining a surface energy balance in the tropics is quite different from that in the mid-latitudes. The present paper evaluates the performance of four different mitigation strategies to counterbalance the impact of UHI phenomena for climate resilient adaptation in the Kolkata Metropolitan Area (KMA), India. This has been achieved by reproducing the study sites, selected from three different urban morphologies of open low-rise, compact low-rise and mid-rise residential areas, using ENVI-met V 4.0 and simulating the effects of different mitigation strategies- cool pavement, cool roof, added urban vegetation and cool city (a combination of the three former strategies), in reducing the UHI intensity. Simulation results show that at a diurnal scale during summer, the green city model performed best at neighborhood level to reduce air temperature (Ta) by 0.7 °C, 0.8 °C and 1.1 °C, whereas the cool city model was the most effective strategy to reduce physiologically equivalent temperature (PET) by 2.8° - 3.1 °C, 2.2° - 2.8 °C and 2.8° - 2.9 °C in the mid-rise, compact low-rise and open low-rise residential areas, respectively. It was observed that (for all the built environment types) vegetation played the most significant role in determining surface energy balance in the study area, compared to cool roofs and cool pavements. This study also finds that irrespective of building environments, tropical cities are less sensitive to the selected strategies of UHI mitigation than their temperate counter parts, which can be attributed to the difference in magnitude of urbanness.

Characterization of 1-Aminobenzotriazole and Ketoconazole as Novel Inhibitors of Monoamine Oxidase (MAO): An In Vitro Investigation.

BACKGROUND AND OBJECTIVES: 1-Aminobenzotriazole, a known time-dependent inhibitor of cytochrome P450 (CYP) enzymes, and ketoconazole, a strong inhibitor of the human CYP3A4 isozyme, are used as standard probe inhibitors to characterize the CYP and/or non-CYP-mediated metabolism of xenobiotics. In the present investigation, 1-Aminobenzotriazole and ketoconazole are characterized as potent monoamine oxidase (MAO) inhibitors in vitro using mouse, rat and human liver microsomes and S9 fractions. METHODS: Inhibition potential of 1-aminobenzotriazole and ketoconazole was studied in mice, rat and human liver microsomes, S9 fractions, MAO-A and MAO-B expressed enzymes by monitoring the formation of 4-hydroxyquinoline (4-HQ) from kynuramine, a specific substrate of MAO by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mechanism of MAO inhibition was studied by incubating varying concentration of kynuramine with mouse, rat and human S9 fractions at varying concentration of 1-aminobenzatriazole and ketoconazole and monitoring the formation of 4-HQ. RESULTS: 1-aminobenzotriazole and ketoconazole inhibited both MAO isozymes (MAO-A and MAO-B) with more specificity towards MAO-B. Kynuramine substrate kinetics in mouse, rat and human S9 fractions with varying 1-aminobenzotriazole and ketoconazole concentrations showed decreased maximum rate (V max) for 4-HQ formation without affecting the Michaelis-Menten constant (K m). A non-competitive inhibition model was constructed and inhibition constants (K i) for 1-aminobenzotriazole (7.87 ± 0.61, 8.61 ± 0.92, 65.2 ± 1.61 µM for mice, rat and humans, respectively) and ketoconazole (0.12 ± 0.01, 2.04 ± 0.08, 5.52 ± 0.47 µM for mice, rat and humans, respectively) were determined. CONCLUSIONS: 1-Aminobenzotriazole and ketoconazole are characterized as non-competitive inhibitors of mice, rat and human MAO in vitro and the extent of their MAO inhibition potential is species specific. 1-Aminobenzotriazole or ketoconazole can be used as a probe inhibitor in vitro for screening the involvement of MAO-dependent metabolism of new chemical entities (NCE) in early drug discovery.

Altered pharmacokinetics of rosiglitazone in a mouse model of non-alcoholic fatty liver disease.

BACKGROUND: Severe forms of non-alcoholic fatty liver disease (NAFLD) adversely affect the liver physiology and hence the pharmacokinetics of drugs. Here, we investigated the effect of NAFLD on the pharmacokinetics of rosiglitazone, an insulin sensitizer used in the treatment of type 2 diabetes. METHODS: Male C57BL/6 mice were divided into two groups. The first group (n=14) was fed with normal chow feed and the second group (n=14) was fed with 60% high-fat diet (HFD) and 40% high fructose liquid (HFL) for 60 days to induce NAFLD. The development of NAFLD was confirmed by histopathology, liver triglyceride levels and biochemical estimations, and used for pharmacokinetic investigations. Rosiglitazone was administered orally at 30 mg/kg dose. At predetermined time points, blood was collected and rosiglitazone concentrations were determined using LC/MS/MS. Plasma concentrations were subjected to non-compartmental analysis using Phoenix WinNonlin (6.3), and the area under the plasma concentration-time curve (AUC) was calculated by the linear-up log-down method. RESULTS: HFD and HFL diet successfully induced NAFLD in mice. Rosiglitazone pharmacokinetics in NAFLD animals were altered significantly as compared to healthy mice. Rosiglitazone exposure increased significantly in NAFLD mice (2.5-fold higher AUC than healthy mice). The rosiglitazone oral clearance was significantly lower and the mean plasma half-life was significantly longer in NAFLD mice as compared to healthy mice. CONCLUSIONS: The NAFLD mouse model showed profound effects on rosiglitazone pharmacokinetics. The magnitude of change in rosiglitazone pharmacokinetics is similar to that observed in humans with moderate to severe liver disease. The present animal model can be utilized to study the NAFLD-induced changes in the pharmacokinetics of different drugs.

Bioanalytical method development, validation and quantification of dorsomorphin in rat plasma by LC-MS/MS.

The present investigation describes the development and validation of a sensitive liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method for the estimation of dorsomorphin in rat plasma. A sensitive LC-MS/MS method was developed using multiple reaction monitoring mode, with the transition of m/z (Q1/Q3) 400.2/289.3 for dorsomorphin and m/z (Q1/Q3) 306.2/236.3 for zaleplon. Chromatographic separation was achieved on a reverse phase Agilent XDB C18 column (100 × 4.6 mm, 5 µm). The mobile phase consisted of acetonitrile and 5 mm ammonium acetate buffer (pH 6.0) 90:10 v/v, at a flow rate of 0.8 mL/min. The effluence was ionized in positive ion mode by electrospray ionization (ESI) and quantitated by mass spectrometry. The retention times of dorsomorphin and internal standard were found to be 2.13 and 1.13 min, respectively. Mean extraction recovery of dorsomorphin and internal standard in rat plasma was above 80%. Dorsomorphin calibration curve in rat plasma was linear (r(2) ≥ 0.99) ranging from 0.005 to 10 µg/mL. Inter-day and intra-day precision and accuracy were found to be within 85-115% (coefficient of variation). This method was successfully applied for evaluation of the oral pharmacokinetic profile of dorsomorphin in male Wistar rats.

Sustained therapeutic effects of percutaneous tibial nerve stimulation: 24-month results of the STEP study.

AIMS: To evaluate the safety, sustained effectiveness, and treatment interval for percutaneous tibial nerve stimulation (PTNS) for overactive bladder (OAB) therapy through 24 months. METHODS: A prospective study following treatment success after 12 weekly PTNS treatments, subjects were prescribed a 14-week tapering protocol, followed by ongoing therapy with a Personal Treatment Plan determined by the investigator and subject to sustain subject OAB symptom improvement. Questionnaires were completed every 3 months, voiding diaries every 6 months; adverse events were reported throughout. RESULTS: Of 50 subjects enrolled, 35 remained in the study at 24 months. During the 24 months following initial treatment success and a 14-week tapering protocol, mean treatments per month was 1.3. Voiding diary and OAB-q data demonstrate sustained improvement reported at 13 weeks through 24 months. Improvements in frequency, urge incontinence episodes, night-time voids and moderate-to-severe urgency episodes from voiding diaries at 6, 12, 18, and 24 months were statistically significant compared to baseline (prior to initial 12 weekly treatments). Compared to baseline, OAB-q symptom severity scores and health related quality of life scores were statistically significant for improvement at each tested time point. Five mild adverse events of unknown relation to treatment were reported. CONCLUSION: Sustained safety and efficacy of PTNS were demonstrated over 24 months with initial success after 12 weekly treatments, followed by a 14-week prescribed tapering protocol and a Personalized Treatment Plan. With an average of 1.3 treatments per month, PTNS therapy is a safe, durable, and valuable long-term OAB treatment option to sustain clinically significant OAB symptom control.

Expression of leukemia/lymphoma related factor (LRF/Pokemon) in human benign prostate hyperplasia and prostate cancer.

Leukemia/lymphoma related factor (LRF), also known as Pokemon, is a protein that belongs to the POK family of transcriptional repressors. It has an oncogenic role in many different solid tumors. In this study, the expression of LRF was evaluated in benign prostate hyperplastic (BPH) and prostate cancer (PC) tissues. The functional expression of LRF was studied using multiple cellular and molecular methods including RT-PCR, western blotting, immunohistochemistry, and immunofluorescence. Paraffin-embedded human tissues of BPH and PC were used to examine LRF expression. Histological staining of the BPH and PC tissue sections revealed nuclear expression of LRF with minimal expression in the surrounding stroma. The semi-quantitative RT-PCR and western immunoblot analyses demonstrated significantly higher mRNA transcripts and protein expression in PC than BPH. High expression of LRF suggests that it may have a potential role in the pathogenesis of both BPH and prostate cancer. Further studies will help elucidate the mechanisms and signaling pathways that LRF may follow in the pathogenesis of prostate carcinoma.

The role of lithocholic acid in the regulation of bile acid detoxication, synthesis, and transport proteins in rat and human intestine and liver slices.

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.

A cribriform urothelial neoplasm of the renal pelvis: an adenoid cysticlike variant of inverted urothelial papilloma or florid ureteritis cystica?

Tumors with cribriform appearance, similar to that of salivary gland adenoid cystic carcinoma, have been described at various anatomic sites. We present an unusual polypoid tumor, discovered incidentally, in the renal pelvis of an elderly man. The mass displayed a prominent cribriform architecture, akin to adenoid cystic carcinoma with an immunophenotype that supported a urothelial origin. Because of its lack of significant invasive growth and other adverse morphologic features, this lesion will likely behave in a banal fashion. This cribriform urothelial neoplasm of the renal pelvis may, in fact, represent a variant of an inverted urothelial neoplasm with a prominent cystic component or florid ureteritis cystica. It is important for pathologists to recognize this growth pattern as a possible variant of urothelial tumors.

Simple melanosis of the bladder: a rare entity.

Simple melanosis of the bladder is an uncommon condition with fewer than 15 reported cases characterized by multifocal, diffuse melanin pigmentation of the urothelial mucosa. It is frequently associated with urinary incontinence or urgency. Histologically, melanin granules are present within urothelial cells or lamina propria macrophages with or without bland-appearing mucosal melanocytes. Although considered a benign entity, the rarity of the lesion warrants regular follow-up cystoscopic evaluation with biopsies to screen for the development of malignancy, especially malignant melanoma. This study presents a "typical" case with light, cytochemical, immunohistochemical, and ultrastructural characterization.

Randomized trial of percutaneous tibial nerve stimulation versus Sham efficacy in the treatment of overactive bladder syndrome: results from the SUmiT trial.

PURPOSE: The Study of Urgent PC vs Sham Effectiveness in Treatment of Overactive Bladder Symptoms (SUmiT) was a multicenter, double-blind, randomized, controlled trial comparing the efficacy of percutaneous tibial nerve stimulation to sham through 12 weeks of therapy. The improvement in global response assessment, voiding diary parameters, and overactive bladder and quality of life questionnaires was evaluated. MATERIALS AND METHODS: A total of 220 adults with overactive bladder symptoms were randomized 1:1 to 12 weeks of treatment with weekly percutaneous tibial nerve stimulation or sham therapy. Overactive bladder and quality of life questionnaires as well as 3-day voiding diaries were completed at baseline and at 13 weeks. Subject global response assessments were completed at week 13. RESULTS: The 13-week subject global response assessment for overall bladder symptoms demonstrated that percutaneous tibial nerve stimulation subjects achieved statistically significant improvement in bladder symptoms with 54.5% reporting moderately or markedly improved responses compared to 20.9% of sham subjects from baseline (p <0.001). All individual global response assessment subset symptom components demonstrated statistically significant improvement from baseline to 13 weeks for percutaneous tibial nerve stimulation compared to sham. Voiding diary parameters after 12 weeks of therapy showed percutaneous tibial nerve stimulation subjects had statistically significant improvements in frequency, nighttime voids, voids with moderate to severe urgency and urinary urge incontinence episodes compared to sham. No serious device related adverse events or malfunctions were reported. CONCLUSIONS: This pivotal multicenter, double-blind, randomized, sham controlled trial provides level I evidence that percutaneous tibial nerve stimulation therapy is safe and effective in treating overactive bladder symptoms. The compelling efficacy of percutaneous tibial nerve stimulation demonstrated in this trial is consistent with other recently published reports and supports the use of peripheral neuromodulation therapy for overactive bladder.

Regulation of VDR expression in rat and human intestine and liver--consequences for CYP3A expression.

The vitamin D receptor (VDR) regulates the expression of drug metabolizing enzymes and transporters in intestine and liver, but the regulation of VDR expression in intestine and liver is incompletely understood. We studied the regulation of VDR mRNA expression by ligands for VDR, farnesoid X receptor (FXR), glucocorticoid receptor (GR) and protein kinase C alpha (PKCalpha) in rat and human ileum and liver using precision-cut slices. 1,25(OH)(2)D(3) induced VDR expression in rat ileum and liver, and human ileum but not in liver. Chenodeoxycholic acid (CDCA), but not lithocholic acid (LCA) and GW4064 induced VDR mRNA expression in rat ileum and liver. The PKCalpha activator, phorbol-12-myristate-13-acetate (PMA) induced the expression of VDR in the rat liver, and the induction of VDR by 1,25(OH)(2)D(3) and CDCA was inhibited by the PKCalpha inhibitor, bisindolyl maleimide I (Bis I). These results show that the expression of VDR is likely to be regulated by PKC but not by FXR or VDR activation at least in the rat liver. The VDR mediated induction of its target genes CYP3A1 and CYP3A2 by 1,25(OH)(2)D(3) or LCA in the rat ileum was strongly reduced in the presence of CDCA despite the higher VDR expression. Thus, CDCA might potentiate the toxicity of LCA by inhibiting its metabolism.

Effects of 1alpha,25-dihydroxyvitamin D3 on transporters and enzymes of the rat intestine and kidney in vivo.

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) triggered vitamin D receptor and farnesoid X receptor-like effects in rat intestine and liver in vivo.

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.

Expression and regulation of the bile acid transporter, OSTalpha-OSTbeta in rat and human intestine and liver.

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.