Oxidative stress and toxicity induced by the nucleoside reverse transcriptase inhibitor (NRTI)--2',3'-dideoxycytidine (ddC): relevance to HIV-dementia

Human immunodeficiency virus dementia (HIVD) is the most common form of dementia occurring among young adults. In HIVD, neuronal cell loss occurs in the absence of neuronal infection. With the advent of highly active anti-retroviral therapy (HAART), the incidence of HIVD has drastically reduced, though prevalence of milder forms of HIVD continues to rise. Though these agents have been used successfully in suppressing viral production, they have also been associated with a number of side effects. Here we examine the possible role of NRTIs, in particular 2',3'-dideoxycytidine (ddC), in the neuropathology of HIVD. Synaptosomes and isolated mitochondria treated and incubated for 6 h with CSF-achievable concentrations of ddC, i.e., 6-11 ng/ml, were found to show a significant increase in oxidative stress with 40 nM ddC as measured by protein carbonyls and 3-nitrotyrosine (3NT), effects that were not observed in the more tolerable NRTI, 3TC. Protection against protein oxidation induced by ddC was observed when brain mitochondria were isolated from gerbils 1 h after injection i.p. with the brain accessible antioxidant and glutathione mimetic, tricyclodecan-9-yl-xanthogenate (D609). In addition, there is a significant reduction in the levels of anti-apoptotic protein Bcl-2 and a significant increase in cytochrome c release and also a significant increase in the expression of pro-apoptotic protein caspase-3 after mitochondria were treated with 40 nM ddC. The results reported here show that ddC at 40 nM can induce oxidative stress, cause the release of cytochrome c, and in addition, reduce the levels of anti-apoptotic proteins, increase the levels of pro-apoptotic proteins, thereby increasing the possibility for induction of apoptosis. These findings are consistent with the notion of a possible role of the NRTIs, and in particular, ddC, in the mechanisms involved in HIVD.     

When the worst headache becomes the worst heartache!

BACKGROUND AND PURPOSE: Although a great deal of literature has been generated regarding left ventricular wall abnormalities, ECG changes and cardiac enzyme leaks associated with subarachnoid hemorrhage (SAH), there have been only a few reports of true transient left ventricular apical ballooning syndrome in patients with SAH. Several pathophysiological mechanisms have been proposed to explain the unusual features of this syndrome, such as multivessel coronary vasospasm, abnormalities in coronary microvascular function, and catecholamine-mediated cardiotoxicity. Summary of Case- A previously healthy 64-year-old woman with no history of vascular disease was found unresponsive at home. She was taken to the emergency room where a CT head revealed an SAH due to a ruptured aneurysm of the posterior communicating artery. On admission, an ECG showed deeply inverted T-waves and QT prolongation, typical of SAH. Cardiac troponin was measured at 1.2 ng/mL, and later increased to 3.7 ng/mL. A transthoracic echocardiogram on the next day revealed a large left ventricular wall abnormality, characteristic of apical ballooning with an ejection fraction of 25% to 30%. The patient remained hemodynamically stable and was started on low dose beta-blocker and angiotensin-converting enzyme inhibitor. She had an uneventful cardiac recovery within 5 days at which time a repeat transthoracic echocardiogram revealed a normal ejection fraction with no wall motion abnormality. CONCLUSIONS: This report adds to the growing list of "stressors" for Takotsubo cardiomyopathy. Clinicians should be aware of the existence and the typical clinical manifestations of this syndrome, which is increasingly recognized in various populations. In particular, neurologists should consider this syndrome in the differential diagnosis of ECG changes and apical wall motion abnormalities in patients with SAH. Prognosis is generally very good with full recovery in most patients; however, there may be increased morbidity associated in patients with SAH.     

Molecular genetic analysis of BAX and cyclin D1 genes in patients with malignant glioma

INTRODUCTION AND OBJECTIVES: Brain tumorigenesis is a complex process involving multiple genetic alterations. Cyclin D1 and BAX genes are two of the most important regulators in controlling the normal proliferation and apoptosis of cells, respectively. In this study, we analysed the possibilities of involvement of cyclin D1 and BAX genes in the gliomagenesis. METHODS AND RESULTS: In determining gene alterations of exon 4 of cyclin D1 gene and exon 6 of BAX gene, all samples were amplified by polymerase chain reaction (PCR) and subsequently by direct sequencing. Our results showed a frameshift mutation (G base deletion) at nucleotide 82 of codon 28 in exon 4 of the cyclin D1 gene and another frameshift mutation with a deletion of C base at nucleotide 153 of exon 6 of the BAX gene in two separate cases of a glioblastoma multiform (WHO Grade IV) sample. CONCLUSION: These findings suggest that both cyclin D1 and BAX genes alteration are rarely found in brain tumors. However, the alteration might cause a significant effect of the normal protein production and this might contribute to the development of brain tumorigenesis in Malaysian patients.     

Drug Discovery for Overcoming Chronic Kidney Disease (CKD): Pharmacological Effects of Mineralocorticoid-Receptor Blockers

There is increasing evidence demonstrating that the renoprotective effects of mineralocorticoid receptor (MR) blockade are independent of the effects exerted by renin-angiotensin inhibitors. MR is expressed not only in tubular cells but also in other renal cells including glomerular mesangial cells, podocytes, and renal interstitial fibroblasts. Animal experiments have shown that MR blockers prevent aldosterone-induced proteinuria, glomerular injury, and tubulointerstitial fibrosis. In vitro studies have also demonstrated that MR blockers inhibit aldosterone-induced renal cell damage. Recent clinical studies have shown that treatment with MR blockers attenuates the development of proteinuria in patients with chronic kidney disease (CKD) and hypertension, independent of changes in blood pressure. In some cases, MR blockers elicit potent renoprotective effects in conditions where aldosterone levels are not elevated. These data suggest that treatment with MR blockers may possibly present an effective therapeutic strategy for patients with CKD.     

Genotoxicity of wastewaters used for irrigation of food crops

In most towns of India, wastewater coming from both industrial and domestic sources and without any treatment is used to irrigate the agricultural crops. This practice has been polluting the soil, and pollutants could possibly reach the food chain. For the above reasons, the wastewaters of Ghaziabad City (India), which is used for irrigation, were sampled (at two different sites) and monitored for the presence of genotoxic agents from January 2005 to June 2007. Gas chromatographic analysis showed the presence of certain OC (DDE, DDT, Dieldrin, Aldrin, and Endosulfan) and OP (Dimethoate, Malathion, Methlyparathion, and Chlorpyrifos) pesticides in both the sampling sites. Wastewater samples were concentrated using XAD resins (XAD-4 and XAD-8) and liquid-liquid extraction procedures, and the extracts were assayed for genotoxic potential by Ames Salmonella/microsome test, DNA repair defective mutants, and bacteriophage lambda systems. The test samples exhibited significant mutagenicity with TA98, TA97a, and TA100 strains with the probable role of contaminating pesticides in the wastewater. However, XAD-concentrated samples were more mutagenic in both sites as compared to liquid-liquid-extracted samples. The damage in the DNA repair defective mutants in the presence of XAD-concentrated water samples were also found to be higher to that of liquid-liquid-extracted water samples at the dose level of 20 muL/mL culture. All the mutants invariably exhibited significant decline in their colony-forming units as compared to their isogenic wild-type counterparts. The survival was decreased by 81.7 and 75.5% in polA(-) strain in site I, and 76.0 and 73.5% in site II in polA(-) under the same experimental conditions after 6 h of treatment with XAD-concentrated and liquid-liquid-extracted samples, respectively. A significant decrease in the survival of bacteriophage lambda was also observed when treated with the test samples.     

Purunusides A-C, α-glucosidase inhibitory homoisoflavone glucosides from <Emphasis Type="Italic">Prunus domestica</Emphasis>

Purunusides A-C (1–3), new homoisoflavone glucosides together with the known compounds β-sitosterol (4) and 6,7-methylenedioxy-8-methoxycoumarin (5) have been isolated from n-butanol and ethyl acetate soluble fractions of Prunus domestica. Their structures were assigned on the basis of spectral studies. The compounds 1–3 showed potent inhibitory activity against the enzyme α-glucosidase.