When nitrous oxide is no laughing matter: nitrous oxide and pediatric anesthesia

Although often felt to be relatively innocuous, nitrous oxide can have significant metabolic effects in settings of abnormal vitamin B12 and B12-related metabolism in children. These conditions can be genetic or environmental. Symptoms may not appear until days to weeks after exposure to nitrous oxide. Although overt genetic diseases are relatively uncommon, the implications of nitrous oxide interactions with much more frequent but less symptomatically obvious single nucleotide polymorphisms are potentially more concerning. In addition, nitrous oxide can have direct and differing neurotoxic effects on both immature and aged brain, the clinical impact of which remains undetermined.     

Modification of primers for GRHPR genotyping: avoiding allele dropout by single nucleotide polymorphisms and homology sequence

Mutation of primer site for genotyping by polymerase chain reaction (PCR) may cause allele dropout and other genotyping failures. Primary hyperoxaluria type 2 (PH2) is a rare inherited disease caused by overproduction of endogenous oxalate due to mutations in the glyoxylate/hydroxypyruvate reductase (GRHPR) gene. Here, to avoid allele dropout and primer annealing to multiple sites, and given the discrepancy in intron length between GRHPR gene data, we updated the primers used in the sequence assay of the GRHPR gene. These redesigned primers show potential in reducing detection failure of GRHPR mutations. In addition, we performed a single nucleotide polymorphism (SNP) linkage analysis of the GRHPR gene using direct sequencing with PCR amplification of specific alleles (DS-PASA). Using this technique, we sequenced four common SNPs between intron E and exon 6, which show linkage disequilibrium (LD) consisting of three types of haplotypes, similar to data from the HapMap SNP database. This article directly relates to material presented at the 11th International Urolithiasis Symposium, Nice, 2–5 September 2008, from which the abstracts were published in the following issue of Urological Research: Urological Research (2008) 36:157–232. doi:.     

A gold(I) phosphine complex selectively induces apoptosis in breast cancer cells: implications for anticancer therapeutics targeted to mitochondria

Bis-chelated gold(I) phosphine complexes have shown great potential as anticancer agents, however, their efficacy has been limited by their high toxicity and lack of selectivity for cancer cells. Here, we have investigated the anticancer activity of a new bis-chelated Au(I) bidentate phosphine complex of the novel water soluble ligand 1,3-bis(di-2-pyridylphosphino)propane (d2pypp). We show that this gold complex [Au(d2pypp)(2)]Cl, at submicromolar concentrations, selectively induces apoptosis in breast cancer cells but not in normal breast cells. Apoptosis was induced via the mitochondrial pathway, which involved mitochondrial membrane potential depolarisation, depletion of the glutathione pool and caspase-3 and caspase-9 activation. The gold lipophilic complex was accumulated in mitochondria of cells, driven by the high mitochondrial membrane potential. To address the molecular basis of the observed selectivity between the two cell lines we investigated the effect of the gold complex on the thioredoxin/thioredoxin reductase system in normal and cancer breast cells. We show that [Au(d2pypp)(2)]Cl inhibits the activities of both thioredoxin and thioredoxin reductase and that this effect is more pronounced in the breast cancer cells. This difference may account for the selective cell death seen in the breast cancer cells but not in the normal cells. Our investigation has led to new insights into the mechanism of action of bis-chelated gold(I) diphosphine complexes and their future development as mitochondria targeted chemotherapeutics.     

Protective effect of Ocimum sanctum on 3-methylcholanthrene, 7,12-dimethylbenz(a)anthracene and aflatoxin B1 induced skin tumorigenesis in mice

A study on the protective effect of alcoholic extract of the leaves of Ocimum sanctum on 3-methylcholanthrene (MCA), 7,12-dimethylbenzanthracene (DMBA) and aflatoxin B1 (AFB1) induced skin tumorigenesis in a mouse model has been investigated. The study involved pretreatment of mice with the leaf extract prior to either MCA application or tetradecanoyl phorbol acetate (TPA) treatment in a two-stage tumor protocol viz a viz, DMBA/TPA and AFB1/TPA. The results of the present study indicate that the pretreatment with alcoholic extract of the leaves of O. sanctum decreased the number of tumors in MCA, DMBA/TPA and AFB1/TPA treated mice. The skin tumor induced animals pretreated with alcoholic extract led to a decrease in the expression of cutaneous gamma-glutamyl transpeptidase (GGT) and glutathione-S-transferase-P (GST-P) protein. The histopathological examination of skin tumors treated with leaf extract showed increased infiltration of polymorphonuclear, mononuclear and lymphocytic cells, decreased ornithine decarboxylase activity with concomitant enhancement of interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) in the serum, implying the in vivo antiproliferative and immunomodulatory activity of leaf extract. The decrease in cutaneous phase I enzymes and elevation of phase II enzymes in response to topical application of leaf extract prior to MCA, AFB1, DMBA/TPA and AFB1/TPA treatment indicate the possibility of impairment in reactive metabolite(s) formation and thereby reducing skin carcinogenicity. Furthermore, pretreatment of leaf extract in the carcinogen induced animals resulted in elevation of glutathione levels and decrease in lipid peroxidation along with heat shock protein expression, indicating a scavenging or antioxidant potential of the extract during chemical carcinogenesis. Thus it can be concluded that leaf extract of O. sanctum provides protection against chemical carcinogenesis in one or more of the following mechanisms: (i) by acting as an antioxidant; (ii) by modulating phase I and II enzymes; (iii) by exhibiting antiproliferative activity.     

Statins and fracture risk. A systematic review

PURPOSE: To summarize current evidence on statin use and fracture risk and to explore potential sources of heterogeneity among study results. METHODS: A computerized search was conducted on MEDLINE, EMBASE, and the Cochrane databases using the keywords HMG-CoA reductase inhibitor, osteoporosis, and fractures. A meta-analysis was performed to summarize results of studies identified. RESULTS: Statin use was associated with a 23% lower fracture risk (OR = 0.77, 95%CI: 0.66-0.90). An effect of statins was found in case-control (OR = 0.62, 0.45-0.85, n = 6) and cohort (OR = 0.77, 0.59-1.00, n = 8) studies, but not in post hoc analyses of randomized trials (OR = 1.03, 0.91-1.16, n = 4). A reduced risk with statin use was found for fractures of the hip (OR = 0.58, 0.46-0.74, n = 16), spine (OR = 0.65, 0.48-0.88, n = 8) and other sites (OR = 0.77, 0.60-1.00, n = 7), and both in women (OR = 0.80, 0.66-0.96, n = 11) and men (OR = 0.62, 0.36-1.08, n = 3). Among the observational studies that also evaluated the effect of other lipid-lowering drugs, no reduced fracture risk was found for these agents (OR = 0.96, 0.85-1.09, n = 10). The test for heterogeneity was significant for study results of statin use versus no-use (p < 0.01). Meta-regression analyses suggested that study design might partly account for the heterogeneity. There was an indication of publication bias by examining Begg's plot, although Egger's test was not significant (p = 0.13). CONCLUSIONS: Current evidence does not support an effect of statins in preventing fractures given (i) the lack of association in randomized trials, (ii) the heterogeneity among observational studies, (iii) the potential residual confounding, and (iv) the potential publication bias.     

Influence of rosuvastatin on the NAD(P)H oxidase activity in the retina and electroretinographic response of spontaneously hypertensive rats

Background and purpose:

Retinal complications may be encountered during the development of hypertension as a response to oxidative stress. Statins may reduce the risk of developing hypertension and ocular diseases. We evaluate the effects of rosuvastatin (ROSU) on retinal functionality and oxidative stress levels in normotensive and spontaneously hypertensive rats (SHR).

Experimental approach:

Wistar Kyoto (WKY) and SHR were treated for 3 weeks with rosuvastatin (10 mg kg⁻¹ day⁻¹). Electroretinograms (ERG) were recorded before and after rosuvastatin treatment. Reactive oxygen species (ROS) were determined in the retina with dihydroethidium staining and NAD(P)H oxidase activity was evaluated.

Key results:

Retinal ganglion cell ROS and retinal NAD(P)H oxidase activity were higher in SHR than in WKY rats, respectively (17.1±1.1 vs 10.2±1.2 AU, P<0.01; 38095±8900 vs 14081±5820 RLU mg⁻¹; P<0.05). The ERG b-wave amplitude in SHR was significantly lower than that in WKY rats. Rosuvastatin reduced SBP in SHR but did not change plasma lipid levels. Rosuvastatin treatment in SHR significantly decreased ROS levels (11.2±1.3, P<0.01), NAD(P)H activity in retinal ganglion cells (9889±4290; P<0.05), and increased retinal plasmalogen content in SHR, but did not modify the ERG response.

Conclusions and implications:

Rosuvastatin, beyond lowering cholesterol levels, was able to lower ROS in the retina induced by hypertension, but without improving retinal function in SHR. These findings point to a complex relationship between ROS in the pathogenesis of retinal disease and hypertension.     

Efficacy and safety of dutasteride in Japanese men with benign prostatic hyperplasia

Objectives:   To assess the efficacy and safety of dutasteride in Japanese men with benign prostatic hyperplasia (BPH).
Methods:   This was a randomized, double-blind, placebo-controlled, parallel-group study. A total of 378 subjects with clinical BPH having an International Prostate Symptom Score (IPSS) of 8 points or greater, a prostate volume of 30 mL or greater, and a maximal urinary flow rate (Qmax) of 15 mL/s or less were randomized to receive placebo or dutasteride once daily for 52 weeks. Subjects were stratified according to tamsulosin use at baseline. The numbers of subjects with and without tamsulosin use were 242 and 136, respectively. IPSS, Qmax, prostate volume and drug safety were evaluated.
Results:   Continued improvement in IPSS was noted in the dutasteride group, and dutasteride significantly decreased IPSS compared with placebo. At week 52, dutasteride significantly improved Qmax and prostate volume compared with placebo. Drug-related sexual function events in the dutasteride group were infrequent and generally were not treatment limiting.
Conclusions:   Dutasteride improves urinary symptoms and flow rate and reduces prostate volume. In Japanese men with BPH, it is effective and generally well tolerated during the one-year treatment period.     

Alteration of xenobiotic metabolizing enzymes by resveratrol in liver and lung of CD1 mice

Conflicting data on the anticancer properties of the polyphenolic natural product resveratrol (RSV) have been reported. Since the inhibition of “bioactivating” Phase-I xenobiotic metabolizing enzymes (XMEs) and/or induction of “detoxifying” Phase-II XMEs have long been considered important cancer chemopreventive strategies, in the current study we investigated the effect of RSV treatment on several Cytochrome P450 (CYP)-dependent oxidations and Phase-II markers in liver and lung subcellular preparations from CD1 male mice. These mice were i.p treated with RSV (25 or 50 mg/Kg b.w.) daily for one or for seven consecutive days. Using either specific probes for different CYPs, or the regio- and stereo-selective metabolism of testosterone, we found that most of the Phase-I XMEs were significantly suppressed (up to ∼61% loss for the CYP3A1/2-linked 6 β-hydroxylation of testosterone in liver and up to ∼97% loss for 2 α-hydroxylase in lung) following RSV treatment for 7 days at 50 mg/kg b.w. Glutathione S-transferase was significantly inhibited, particularly in lung (∼76% loss of activity) after single administration of 25 mg/kg b.w. A different response for the UDP-glucuronosyl transferase was observed, where a significant induction was seen (∼83%) in the liver and a significant reduction was observed in the lung (up to ∼83% loss) following treatment with 25 mg/kg b.w. for seven days. These data indicate that murine XMEs are altered by RSV, and that this alteration is dependent on the RSV dose, duration and way of administration. These results could provide mechanistic explanations for the conflicting chemopreventive results reported for RSV.     

Microscale synthesis and kinetic isotope effect analysis of (4R)‐[Ad‐14C,4‐2H] NADPH and (4R)‐[Ad‐3H,4‐2H] NADPH

We present a one‐pot chemo‐enzymatic microscale synthesis of NADPH with two different patterns of isotopic labels: (4R)‐[Ad‐¹⁴C,4‐²H] NADPH and (4R)‐[Ad‐³H,4‐²H] NADPH. These co‐factors are required by an enormous range of enzymes, and isotopically labeled nicotinamides are consequently of significant interest to researchers. In the current procedure, [Ad‐¹⁴C] NAD⁺ and [Ad‐³H] NAD⁺ were phosphorylated by NAD⁺ kinase to produce [Ad‐¹⁴C] NADP⁺ and [Ad‐³H] NADP⁺, respectively. Thermoanaerobium brockii alcohol dehydrogenase was then used to stereospecifically transfer deuterium from C2 of isopropanol to the re face of C4 of NADP⁺. After purification by HPLC, NMR analysis indicated that the deuterium content at the 4R position is more than 99.7%. The labeled cofactors were then used to successfully and sensitively measure kinetic isotope effects for R67 dihydrofolate reductase, providing strong evidence for the utility of this synthetic methodology. Copyright © 2009 John Wiley & Sons, Ltd.