Effects of Probenecid on Hepatic and Renal Disposition of Hexadecanedioate,an Endogenous Substrate of Organic Anion Transporting Polypeptide 1B in Rats

The aim of the present study was to investigate changes in plasma concentrations and tissue distribution of endogenous substrates of organic anion transporting polypeptide (OATP) 1B, hexadecanedioate (HDA), octadecanedioate (ODA), tetradecanedioate (TDA), and coproporphyrin-III, induced by its weak inhibitor, probenecid (PBD), in rats. PBD increased the plasma concentrations of these four compounds regardless of bile duct cannulation, whereas liver-to-plasma (K_p,liver) and kidney-to-plasma concentration ratios of HDA and TDA were reduced. Similar effects of PBD on plasma concentrations and K_p,liver of HDA, ODA, and TDA were observed in kidney-ligated rats, suggesting a minor contribution of renal disposition to the overall distribution of these three compounds. Tissue uptake clearance of deuterium-labeled HDA (d-HDA) in liver was 16-fold higher than that in kidney, and was reduced by 80% by PBD. This was compatible with inhibition by PBD of d-HDA uptake in isolated rat hepatocytes. Such inhibitory effects of PBD were also observed in the human OATP1B1-mediated uptake of d-HDA. Overall, the disposition of HDA is mainly determined by hepatic OATP-mediated uptake, which is inhibited by PBD. HDA might, thus, be a biomarker for OATPs minimally affected by urinary and biliary elimination in rats.     

Co-administration of low molecular weight heparin enhances the profibrinolytic effect of warfarin through different mechanisms

Background and Objective

Treatment with vitamin K antagonists (VKA) reduces fibrinolytic resistance through the inhibition of thrombin-mediated activation of thrombin activatable fibrinolysis inhibitor (TAFI). Because low-molecular weight heparin (LMWH) is co-administered with VKA during initiation of anticoagulant treatment, we evaluated the effect of dual anticoagulation on fibrinolytic resistance.

Patients and Methods

Two groups of patients were studied: 1) patients on stable warfarin; 2) patients starting oral anticoagulant therapy, who were evaluated during dual anticoagulation and after enoxaparin withdrawal. Only samples with an INR between 2 and 3 were compared. The resistance of clots to t-PA-induced fibrinolysis was evaluated in blood and plasma by thromboelastography (TEG) and turbidimetry, respectively.

Results

In patients on dual anticoagulation, blood fibrinolysis time (TEG) was significantly shorter than in patients on warfarin alone and significantly correlated with LMWH level. The profibrinolytic effect was partly ascribable to a reduction of thrombin-dependent TAFI activation: 1) thrombin and TAFIa generation were significantly reduced by dual anticoagulation; 2) the addition of enoxaparin to warfarin-blood reduced TAFI-mediated fibrinolysis inhibition. Patients on dual anticoagulation also displayed a reduction in clot strength, a phenomenon known to reduce fibrinolytic resistance. The profibrinolytic effect of LMWH co-administration was not seen in plasma, likely because TAFIa generation was below the threshold required to inhibit fibrinolysis.

Conclusions

Co-administration of LMWH in patients under VKA reduces the fibrinolytic resistance of blood clots via TAFI-dependent and TAFI-independent mechanisms. Further studies are warranted to assess the clinical implications of these findings.     

Longitudinal evaluation of cartilage after osteochondral autogenous transfer with delayed gadolinium‐enhanced MRI of the cartilage (dGEMRIC)

The aim was to use repeat delayed gadolinium‐enhanced magnetic resonance imaging of cartilage (dGEMRIC) to estimate glycosaminoglycan (GAG) content in reparative cartilage after osteochondral autogenous transfer (OAT). The study group comprised 7 knees of 7 patients that were examined three times by dGEMRIC, at 3, 6, and 12 months using a 1.5 Tesla MRI system in both OAT operated and nonoperated condyles at 90 min after the injection. The gadolinium diethylene triamine pentaacetic acid (Gd‐DTPA)^2? containing contrast medium (0.2 mmols/kg) was injected intravenously. The mean T1 values of the plug cartilage at 3, 6, and 12 months after OAT was 230 ± 40, 213 ± 31, and 230 ± 23 ms (mean ± SD), respectively. There were differences between the plug and control cartilage at 3 (p < 0.01) and 12 (p < 0.05) months after OAT, but not at 6 months (p = 0.089). No T1 changes were detected between the plug cartilage at the different time points after OAT. The fact that the GAG content of the OAT plugs were maintained for 12‐month study period suggest that no major deterioration of load‐bearing properties occurs in the cartilage after the OAT. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:221–225, 2012     

Plants with neurobiological activity as potential targets for drug discovery

Significant number of studies has been performed to find alternatives or treatments for diseases of the nervous forum by identifying structures with activity at the central nervous system (CNS). However most of the screenings are usually conducted on an ad hoc basis and not systematically.     

Case report: One normal child and a chromosomally balanced/normal twin after intracytoplasmic sperm injection in a male with a de-novo t(Y;16) translocation

A balanced translocation t(Y;16)(q11.21;q24) is described ina male with severe oligoasthenoteratozoospermia (OAT). Beforehaving a chromosome investigation, the patient and his partnerhad undergone intracytoplasmic sperm injection (ICSI) treatmentresulting in the birth of a healthy 46,XX child. After detectionof the t(Y;16) translocation, the couple opted for further ICSItreatment, although they were extensively counselled on therisk of having chromosomally unbalanced offspring. This treatmentresulted in a twin pregnancy, one with a 46,XX karyotype andthe other a 46,X,t(Y;16) (q11.21;q24) karyotype, the same asthe father. After an uncomplicated pregnancy two healthy childrenwere born. We conclude that patients with a Y/autosome translocationas a cause of OAT can have chromosomally normal children afterICSI treatment.     

猫须草水提物对痛风性肾病大鼠肾脏URAT1、OAT1及病理的影响

目的探讨猫须草水提物对痛风性肾病大鼠肾脏尿酸盐转运体1(URAT1),有机阴离子转运蛋白1(OAT1)及病理的影响。方法采用酵母粉+腺嘌呤法建立大鼠痛风性肾病模型,测定其血尿酸、血肌酐、血尿素氮、尿尿酸、尿肌酐、24 h尿液排泄量及尿酸分级排泄率,光镜下观察肾组织病理变化,免疫组化法检测肾组织URAT1、OAT1蛋白表达。结果与模型组比较,猫须草水提物高、中剂量组大鼠血尿酸、血肌酐、血尿素氮水平及URAT1蛋白表达降低,而尿尿酸、尿肌酐水平,尿酸分级排泄率,OAT1蛋白表达升高;高、中、低剂量组大鼠24 h尿液排泄量升高程度无明显变化。结论猫须草水提物可能通过上调OAT1蛋白表达促进尿酸排泄、下调URAT1蛋白表达抑制尿酸重吸收的双重调节功能来促进尿酸在肾脏中的排泄,并减轻尿酸对肾脏的病理损伤。     

Lowering and Raising Serum Urate Levels: Off-Label Effects of Commonly Used Medications

Drug-induced hyperuricemia and gout present an increasingly prevalent problem in clinical practice. Herein, we review the urate-lowering or urate-raising effects of commonly used agents. We performed a PubMed search using the terms gout, urate, and medication, along with the specific agents/classes described herein. Reports were reviewed until 2022, and original studies were considered if they primarily or secondarily reported the effects of 1 or more drugs on serum urate level. Previous reviews were assessed for references to additional studies that described urate-altering effects of medications. Urate-changing drugs are summarized regarding their magnitude of effect, mechanism of action, and clinical significance. Potentially urate-lowering drugs include angiotensin II receptor blockers, calcium channel blockers, high-dose aspirin and salicylates, some nonsalicylate nonsteroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, sodium-glucose cotransporter 2 inhibitors, statins, and fenofibrate. Potentially urate-increasing drugs discussed include diuretics, β-blockers, insulin, pyrazinamide, ethambutol, calcineurin inhibitors, low-dose aspirin, testosterone, and lactate. In patients who have or are at risk for hyperuricemia or gout, an increased awareness of drugs that affect serum urate level may allow for prescribing that effectively treats the indicated problem while minimizing adverse effects on hyperuricemia and gout.     

Investigational drugs for hyperuricemia

Introduction: The unmet need and the growing prevalence of hyperuricemia and its complications worldwide have pushed investigators to identify new agents to manage hyperuricemia.

Areas covered: This review discusses the drugs in preclinical and early clinical trials for hyperuricemia, their mechanisms of action and available results. This article reviews a total of 10 novel agents: i) drugs in Phase II/III trials – arhalofenate (MBX201), AC201, RDEA group of drugs (including lesinurad), tranilast, ulodesine (BCX4208); and ii) drugs in Phase I trials, including levotofisopam, UR1102, KX1151, LC350189 and Marine Active.

Expert opinion: The goal of emerging therapies is to address the unsatisfactory control of serum uric acid in patients with symptomatic hyperuricemia such as those with gout, to provide better tolerability compared to traditional agents and minimize the risk of adverse events, especially in patients with comorbidities and the elderly. Some drugs like arhalofenate, ulodesine (BCX-4208) and lesinurad are in or have completed Phase II and Phase III trials. The growing knowledge about the urate transporters in the kidney have advanced our knowledge of pathophysiology of hyperuricemia and have led to the development of several new potential treatment options. Availability of new drugs will lead to better management and address the unmet need in patients with symptomatic hyperuricemia in the coming years.     

Surgical treatments of cartilage defects of the knee: Systematic review of randomised controlled trials

Background

The aim of this systematic review was to identify high quality randomised controlled trials (RCTs) and to provide an update on the most appropriate surgical treatments for knee cartilage defects.

Increased Expression of Renal Drug Transporters in a Mouse Model of Familial Alzheimer's Disease

It is well established that the expression and function of drug transporters at the blood-brain barrier are altered in Alzheimer's disease (AD). However, we recently demonstrated in a mouse model of AD that the expression of key drug transporters and metabolizing enzymes was modified in peripheral organs, such as the small intestine and liver, suggesting that systemic drug absorption may be altered in AD. The purpose of this study was to determine whether the expression of drug transporters in the kidneys differed between 8- to 9-month-old wild-type mice and APPswe/PSEN1dE9 (APP/PS1) transgenic mice, a mouse model of familial AD, using a quantitative targeted absolute proteomics approach. The protein expression of the drug transporters—multidrug resistance-associated protein 2, organic anion transporter 3, and organic cation transporter 2—was upregulated 1.6-, 1.3-, and 1.4-fold, respectively, in kidneys from APP/PS1 mice relative to wild-type mice. These results suggest that in addition to modified oral absorption of certain drugs, it is possible that the renal excretion of drugs that are multidrug resistance-associated protein 2, organic anion transporter 3, and organic cation transporter 2 substrates could be altered in AD. These changes could affect the interpretation of studies conducted during drug development using this mouse model of AD and potentially impact dosage regimens of such drugs prescribed in this patient population.