The unsolved puzzle of neuropathogenesis in glutaric aciduria type I

Glutaric aciduria type I (GA-I) is a cerebral organic aciduria caused by deficiency of glutaryl-Co-A dehydrogenase (GCDH). GCDH deficiency leads to accumulation of glutaric acid (GA) and 3-hydroxyglutaric acid (3-OHGA), two metabolites that are believed to be neurotoxic, in brain and body fluids. The disorder usually becomes clinically manifest during a catabolic state (e.g. intercurrent illness) with an acute encephalopathic crisis that results in striatal necrosis and in a permanent dystonic-dyskinetic movement disorder. The results of numerous in vitro and in vivo studies have pointed to three main mechanisms involved in the metabolite-mediated neuronal damage: excitotoxicity, impairment of energy metabolism and oxidative stress. There is evidence that during a metabolic crisis GA and its metabolites are produced endogenously in the CNS and accumulate because of limiting transport mechanisms across the blood-brain barrier. Despite extensive experimental work, the relative contribution of the proposed pathogenic mechanisms remains unclear and specific therapeutic approaches have yet to be developed. Here, we review the experimental evidence and try to delineate possible pathogenetic models and approaches for future studies.     

Neuropsychological performance in OCD: a study in medication-naïve patients

Background

Obsessive-compulsive disorder (OCD) is associated with impairments in multiple neuropsychological domains but the findings are rather inconsistent across studies. One potential reason for poor replication is the confounding influence of medications. There is limited research on neuropsychological performance in medication-naïve, never treated OCD patients.

Methods

In this study, we assessed 31 medication-naïve, never-treated, DSM-IV OCD patients free of comorbid major depression and 31 healthy controls individually matched for age, gender and years of education, with tests of attention, executive function, memory reasoning and visuo-spatial function.

Results

Medication-naïve OCD patients did not significantly differ from healthy controls on most neuropsychological tests. Patients performed somewhat poorly only on the highest goal hierarchy of the Tower of London (TOL) test (p = 0.001, effect size = 0.68).

Conclusions

It is intriguing to find that symptomatic, drug-naïve OCD patients did not significantly differ from healthy controls on most neuropsychological tests. Our finding of medium effect size on TOL highest goal hierarchy test suggests that brain regions outside the affective orbitofrontal loop may also be perhaps involved in OCD. This finding however needs replication because of modest effect size. Future studies should focus on studying medication-naïve, co-morbidity-free patients and relatives using symptom dimensions for consistent and robust findings.     

Clinical trials update from the American Heart Association 2006: OAT, SALT 1 and 2, MAGIC, ABCD, PABA-CHF, IMPROVE-CHF, and percutaneous mitral annuloplasty

This article provides information and a commentary on trials presented at the American Heart Association meeting held in November 2006, relevant to the pathophysiology, prevention and treatment of heart failure. All reports should be considered as preliminary data, as analyses may change in the final publication. The OAT study failed to show a benefit of PCI over optimal medical therapy in patients with persistent total occlusion of the infarct related artery following a myocardial infarction. In SALT 1 and 2, tolvaptan was found to correct hyponatraemia of various aetiologies; however, whether this has an impact on heart failure prognosis requires further evaluation. A placebo controlled study of myocardial implantation of skeletal myoblasts in patients with moderate to severe LVSD (MAGIC) showed equivocal/uncertain effects, long term follow-up data are awaited. The ABCD study which compared the ability of an invasive and a non-invasive test to identify patients at risk of arrhythmic events prior to ICD implantation, suggested that the two strategies were comparable, although the practical value of either test remains uncertain and the study had many major flaws. The PABA-CHF study hinted that pulmonary vein antrum isolation might be more effective than AV node ablation with bi-ventricular pacing for the treatment of patients with heart failure in atrial fibrillation. In IMPROVE-CHF, an NT-pro BNP guided treatment strategy was found to reduce the cost of managing patients with acute breathlessness.     

Prothrombin complex concentrate (Octaplex) in patients requiring immediate reversal of oral anticoagulation

INTRODUCTION: Rapid reversal of anticoagulant effect from the use of vitamin K antagonists (VKA) is essential when acute bleeding or emergency surgery occurs. Prothrombin complex concentrates (PCCs) produce a more rapid effect with a better clinical outcome, and do not cause volume overload as compared with fresh-frozen plasma (FFP). Octaplex is a modern, double virus safeguarded PCC with balanced content of vitamin K-dependent coagulation factors, which ensures fast onset of action and efficacious treatment, i.e. rapid correction of international normalized ratio (INR). MATERIALS AND METHODS: The main purpose of this study was to demonstrate that Octaplex, when individually dosed, efficiently corrects INR to pre-determined levels in patients under oral anticoagulation who have bleeding complications or are undergoing invasive procedures. To measure the efficacy response, the INR achieved after PCC application per patient was calculated as geometric mean of three measurements within 1 h post-infusion. RESULTS: Sixty patients received a median total Octaplex dose of 41.1 (15.3-83.3) IU/kg body weight (bw). Of 56 patients evaluable in terms of efficacy, 51 (91%) showed a response as pre-defined in the protocol and in 52 (93%) the INR decreased to a value below 1.4 within one hour after dosing. The median INR declined from 2.8 (1.5-9.5) to 1.1 (1.0-1.9) within 10 min. All prothrombin complex coagulation factors recovered in parallel. Three patients had minor adverse drug reactions. One patient showed a non-symptomatic parvovirus B19 seroconversion. No thrombotic side effects were observed. CONCLUSIONS: Octaplex is efficacious and safe in immediate correction of dosage-dependent INR in patients with VKA-related deficiency of prothrombin complex coagulation factors.     

Clinical Trial Updates and Hotline Sessions presented at the Scientific Session 2007 of the American heart association

This article provides information and commentaries on trials which were presented at Clinical Trial Updates and Hotline Sessions presented at the Scientific Sessions 2007 of the American Heart Association in Orlando, Florida. The comprehensive summaries have been generated from the oral presentations and the webcasts of the American Heart Association. Most reports have not been published as full papers and therefore have to be considered as preliminary data, as the analysis may change in the final publications. The following papers are discussed: TRITON TIMI-38, EVA-AMI, BRIEF-PCI, RACE, MASS Stent, HF-ART, STITCH, CORONA, ILLUMINATE, CORE-64, OAT Substudy, AFCHF, MASCOT, RETHINQ, MASTER I, POISE, COUMA-GEN, HIJ-CREATE, PROVIDENCE I, CAUSMIC, IC-BMC, IC/IM BMCs.     

Transmembrane transport of steviol glucuronide and its potential interaction with selected drugs and natural compounds

Steviol glucuronide (SVG) is the major metabolite derived from steviol, the aglycone of stevioside and rebaudioside A. After the ingestion of stevioside and rebaudioside A, SVG is formed and excreted into the urine in humans. In the present study, transporter mediated efflux and uptake of SVG was investigated in order to understand molecular mechanisms underlying its renal clearance. Results showed that SVG was not a substrate of efflux transporters BCRP, MRP2, MATE1 or P-gp. In contrast, OAT3 played a predominant role in the uptake of SVG in comparison to OATP1B1, OATP1B3, or OATP2B1. Quercetin, telmisartan, diclofenac, and mulberrin displayed a relatively strong inhibition against OAT3 mediated uptake of SVG with IC₅₀ values of 1.8, 2.9, 8.0, and 10.0 μM, respectively. Because OAT3 is a major uptake transporter in the kidney, inhibition of OAT3 activity may alter SVG's renal clearance by drugs and natural compounds that are used concomitantly with stevia leaf extracts.     

消石利尿化瘀法降低高尿酸血症大鼠血清尿酸及其机理的研究

目的:研究以消石利尿化瘀法为指导创制的中药复方对高血酸血症大鼠血清尿酸的影响,并对其作用机理进行探讨。方法:雄性Wistar大鼠随机分为空白组、模型组、痛风定胶囊组、苯溴马隆组及中药复方组(6.07 g/kg、3.03 g/kg)共6组。除空白组外,其余各组以腺嘌呤和乙胺丁醇灌胃,同时各给药组灌胃给予相应的药物;空白组和模型组给予等体积蒸馏水,连续10 d。末次给药后,取血,分离血清,以紫外分光光度法测定大鼠血清尿酸(UA)、尿素氮(BUN)的含量及黄嘌呤氧化酶(XOD)的活性;用放射免疫分析法测定大鼠血清中尿酸盐转运蛋白(UAT)、有机阴离子转运蛋白(OAT)的含量。结果:中药复方高、中剂量组大鼠血清UA含量较模型组均降低(P<0.05,P<0.01);中药复方高剂量组大鼠血清XOD活性与模型组比较,明显降低(P<0.01);中药复方中剂量组大鼠血清BUN含量较模型组显著降低(P<0.05);中药复方高剂量组大鼠血清UAT含量与模型组比较,明显升高(P<0.01);中药复方高、中剂量组大鼠血清OAT含量与模型组比较,均明显升高(P<0.01)。结论:以消石利尿化瘀法创制的中药复方能降低高尿酸血症大鼠血清尿酸含量;其降尿酸机理可能与抑制XOD活性、减少尿酸生成,以及保护肾功能、增加UAT、OAT的含量、促进尿酸分泌与排泄有关。