The effect of erythropoetin on doxorubicin-induced oxidative stress in rat kidney

The early nephrotoxicity manifestations (oxidative stress) caused by a single administration of doxorubicin in rats and the therapeutic effect of erythropoietin have been studied. The introduction of doxorubicin leads to a decrease in the concentration of glutathione and the activity of glutathione reductase in rat kidneys, which is indicative of the development of oxidative stress. Erythropoietin restores glutathione content on the normal level. The pretreatment with erythropoietin reduces the doxorubicin induced damage in rat kidneys.     

COX-2 expression in the guinea pig cochlea is partly altered by moderate sound exposure

The cyclooxygenase-2 isoform (COX-2) was found recently to be constitutively expressed in the guinea pig inner ear. To gain knowledge about its role in sound perception, alterations in the COX-2 level of moderate noise-stimulated cochleae were determined. Staining intensities were quantified in different regions using an immunohistochemical staining procedure and computer-assisted system. After 70 dB and 90 dB noise exposure for 1 h at 8000 Hz, COX-2 downregulation was observed in the organ of Corti, which was most prominent in Deiters' cells near Hensen cells and outer hair cells. In pillar cells, COX-2 levels were only slightly reduced after 70 dB but strongly diminished after 90 dB exposure. In Hensen cells, COX-2 was downregulated after 70 dB stimulation, revealing a decreasing COX-2 content from the third to the first turn of the cochlea and a homogeneously reduced enzyme expression in all three turns after 90 dB. The COX-2 content in inner hair cells was nearly identical to unexposed cochleae after 70 dB exposure but significantly reduced after 90 dB stimulation. In spiral ganglion cells, stria vascularis, spiral ligament and limbus, COX-2 expression was unchanged after 70 dB and 90 dB. We suggest that alterations in COX-2 expression might contribute to diminished sensitivity at the cochlea after noise exposure to reduce subsequent noise distress, termed sound conditioning.     

Pharmacokinetics and pharmacodynamics of rosiglitazone in relation to CYP2C8 genotype

OBJECTIVES: Rosiglitazone is metabolically inactivated predominantly via the cytochrome P450 (CYP) enzyme CYP2C8. The functional impact of the CYP2C8*3 allele coding for the Arg139Lys and Lys399Arg amino acid substitutions is controversial. The purpose of this was to clarify the role of this polymorphism with regard to the pharmacokinetics and clinical effects of rosiglitazone. METHODS: From a large sample of healthy volunteers, 14 carriers of the CYP2C8*1/*1 allele, 13 carriers of the *1/*3 allele, and 4 carriers the *3/*3 allele were selected for a clinical study. Rosiglitazone (8 mg) single-dose and multiple-dose pharmacokinetics and its effects on glucose level and body weight were monitored. Plasma and urine concentrations of rosiglitazone and desmethylrosiglitazone were measured, and kinetics was analyzed by noncompartmental and population-kinetic compartmental methods. RESULTS: Mean total clearance values were 0.033 L x h(-1) x kg(-1) (95% confidence interval [CI], 0.030-0.037 L x h(-1) x kg(-1)), 0.038 L x h(-1) x kg(-1) (95% CI, 0.033-0.044 L x h(-1) x kg(-1)), and 0.046 L x h(-1) x kg(-1) (95% CI, 0.033-0.058 L x h(-1) x kg(-1)) in carriers of CYP2C8 genotypes *1/*1, *1/*3, and *3/*3, respectively, on day 1 (P = .02, ANOVA [F test]). Rosiglitazone kinetics could be adequately described by a 1-compartmental model with first-order absorption. Besides CYP2C8 genotype, body weight was a significant covariate (P < .001, log-likelihood ratio test). Elimination half-lives were 4.3, 3.5, and 2.9 hours in CYP2C8*1/*1, *1/*3, and *3/*3 carriers, respectively. Clearance of desmethylrosiglitazone was also higher in CYP2C8*3 allele carriers, with mean values of 1.96 L/h (95% CI, 1.42-2.69 L/h), 2.22 L/h (95% CI, 1.61-3.04 L/h), and 2.47 L/h (95% CI, 1.80-3.39 L/h), respectively (P = .03). The plasma glucose area under the concentration curve was significantly lower after 14 days of taking rosiglitazone compared with day 1 (P = .01, paired t test), but no relationship of the glucose-lowering effect of rosiglitazone with CYP2C8 genotype was observed. CONCLUSIONS: This study showed that the CYP2C8*3 allele confers higher in vivo metabolic capacity than the wild-type CYP2C8*1 allele but the pharmacokinetic differences resulting from CYP2C8*3 were quantitatively moderate.     

The role of fat tissue in development of metabolic disorders in patients with diabetes mellitus type 2 and obesity

AIM: To specify changes in clinicolaboratory parameters in reduction of obesity in patients with diabetes mellitus type 2 (DM-2). MATERIAL AND METHODS: Antropometry, densitometry of fat tissue (FT) were made and parameters of fat and carbohydrate metabolism (lipidogram, glycated hemoglobin, immunoreactive insulin), FT secretory activity (leptin, adiponectin, TNF-alpha) were studied in 75 obese DM-2 patients. After the above primary examination all the patients were randomized into 2 groups: group 1 (n = 55) received xenical (120 mg 3 times a day) and kept moderate hypocaloric diet; group 2 (n = 20) received only the above diet therapy. Active treatment lasted 24 weeks. RESULTS: In addition to symptoms of metabolic syndrome (MS) the patients were found to have secretory disturbances of FT activity: elevation of leptin and TNF-alpha levels, subnormal adiponectin. These alterations directly correlated with body mass, FT mass gain, increase in waist circumference. Hyperleptinemia, hyperinsulinemia and hypoadiponectinemia were considered as markers of insulin resistance (IR) and related conditions. Xenical promoted a significant weight loss resulting in a positive trend in the parameters of adipokines, fat and carbohydrate metabolism, in reduction of IR. CONCLUSION: Xenical is beneficial for patients with DM-2 and obesity because it improves metabolic processes.     

Gender effect on vascular responsiveness after bariatric surgery

Obesity, particularly abdominal obesity, is associated with increased risks of arterial hypertension, diabetes mellitus, hyperlipidemia, sleep apnea, coronary artery disease, stroke and mortality. Weight loss surgery is the most effective treatment for morbid obesity, mainly because medical and dietary treatments have been proven insufficient in the long run. Our primary end point was to study the gender effect on vascular responsiveness (endothelial function and the ankle brachial index [ABI]) 3 months post bariatric surgery. Our secondary end points were to study the effect of gender on antropometric parameters (BMI, waist circumference) and chronic diseases (diabetes mellitus type II, arterial hypertension) 3 months following bariatric surgery, and to find independent variables that may affect and predict the post-operative clinical outcome. Methods: In this prospective study, patients were evaluated one day before surgery and 3 months afterwards. Ankle brachial index was measured while the patient was supine after 15 minutes rest and measurement of the systolic blood pressure in all four extremities was done. The brachial artery method was used to measure endothelial function expressed as flow mediated diameter percent change (FMD %). FMD% more than 10% is considered a normal response. Results: Compared with diabetic females, diabetic males had a higher postoperative BMI (men with diabetes mellitus did not lose weight as much as diabetic women) (β=-0.299; P=0.04), while women with diabetes mellitus had a more significant reduction in BMI postoperatively (β=+0.287; P=0.04). Following bariatric surgery, 12 of the 21 patients with diabetes mellitus type II did not need any medications for diabetes (kept HbA1c% less than 6.5%). All other diabetic patients improved their diabetes mellitus status. Women significantly improved their ABI (average increase of 0.07, p=0.04) and their endothelial function (FMD% change was improved from -3.5±9.0% to 14.8±8.1%, an improvement of 18.3%, p<0.001). Systolic blood pressure was decreased significantly (by 6.6 mmHg, p=0.04). Men improved their endothelial function (FMD% change was improved from -1.3±10.1% to 11.7±6.2%, p<0.001), but no significant change was observed in systolic blood pressure (p=0.29) nor in ABI (P=0.8). A linear regression analysis found that a higher baseline FMD% significantly predicted a higher postoperative FMD% (β=0.294, P=0.03). In obese males, the higher the baseline BMI the worse the post operative endothelial function (β=-0.921, Pd<0.001) and the same adverse effect was documented for hypertensive men (β=-0.380, P=0.05). For females, the higher the baseline FMD% the higher the postoperative FMD% (β=+0.397; P=0.01) [a favorable outcome]. Discussion: Our study has demonstrated a possible mechanistic insight into gender effects observed in epidemiological studies through improvement in vascular response in females undergoing this operation including a better reduction in systolic blood pressure and a better weight reduction in diabetic women with improvement in ABI; unlike males, who did not improve their ABI and did not decrease systolic blood pressure, and the finding that obese diabetic males and obese hypertensive males did the worst.     

Genomic analysis reveals Mycoplasma pneumoniae repetitive element 1-mediated recombination in a clinical isolate

Mycoplasmas are cell wall-less bacteria that evolved by drastic reduction of the genome size. Complete genome analysis of Mycoplasma pneumoniae revealed the presence of numerous copies of four distinct large M. pneumoniae repetitive elements (RepMPs). One copy each of RepMP2/3, RepMP4, and RepMP5 are localized within the P1 operon (MPN140 to MPN142 loci), and their involvement in sequence variation in adhesin P1 and adherence-related protein B/C has been documented. Here we analyzed a clinical strain of M. pneumoniae designated S1 isolated from a 1993 outbreak of respiratory infections in San Antonio, TX. Based on the type of RepMPs within the P1 operon, we classified clinical isolate S1 as type 2 with unique minor sequence variations. Hybridization with oligonucleotide arrays revealed sequence divergence in two previously unsuspected hypothetical genes (MPN137 and MPN138 loci). Closer inspection of this region revealed that the MPN137 and MPN138 loci harbored previously unrecognized unique RepMP1 sequences found only in M. pneumoniae. PCR and sequence analyses revealed a recombination event involving three RepMP1-containing genes that resulted in fusion of MPN137 and MPN138 reading frames and loss of all but a short fragment of another RepMP1-containing locus, MPN130. The multiple copies of unique RepMP1 elements spread throughout the chromosome could allow vast numbers of sequence variations in clinical strains. Comparisons of amino acid sequences showed the presence of leucine zipper motifs in MPN130 and MPN138 proteins in reference strain M129 and the absence of these motifs in the fused protein of S1. The presence of tandem leucine and other repeats points to possible regulatory functions of proteins encoded by RepMP1-containing genes.     

TRESK-like potassium channels in leukemic T cells

In this study, we present patch-clamp characterization of the background potassium current in human lymphoma (Jurkat cells), generated by voltage-independent 16 pS channels with a high ( approximately 100-fold) K(+)/Na(+) selectivity. Depending on the background K(+) channels density, from few per cell up to approximately 1 open channel per mum(2), resting membrane potential was in the range of -40 to -83 mV, approaching E (K) = -88 mV. The background K(+) channels were insensitive to margotoxin (3 nM), apamine (3 nM), and clotrimazole (1 muM), high-affinity blockers of the lymphocyte Kv1.3, SKCa2, and IKCa1 channels. The current depended weakly on external pH. Arachidonic acid (20 muM) and Hg(2+) (0.3-10 muM) suppressed background K(+) current in Jurkat cells by 75-90%. Background K(+) current was weakly sensitive to TEA(+) (IC(50) = 14 mM), and was efficiently suppressed by externally applied bupivacaine (IC(50) = 5 muM), quinine (IC(50) = 16 muM), and Ba(2+) (2 mM). Our data, in particular strong inhibition by mercuric ions, suggest that background K(+) currents expressed in Jurkat cells are mediated by TWIK-related spinal cord K(+) (TRESK) channels belonging to the double-pore domain K(+) channel family. The presence of human TRESK in the membrane protein fraction was confirmed by Western blot analysis.     

Cytomorphological analysis of remodeling of the bronchial wall in different types of bronchial asthma

The objective of the present work was to search for the tissue and cellular markers of remodeling of bronchial mucosa in the patients with different clinical forms of bronchial asthma (BA). The use of up-to-date morphometric techniques has demonstrated that mild and moderately severe forms of bronchial asthma are accompanied by the development of Th2-immune response associated with increased production of interleukin-4 and marked degranulation of eosinophilic granulocytes resulting in desquamation of epithelium and goblet cell hyperplasia. The severe BA phenotype of "chronic asthma with fixed obstruction" is associated with the development of non-atopic inflammation in the bronchial mucous membrane that manifests itself as the increased concentration of interleukin-8 in bronchial mucosa and its neutrophilic infiltration leading to the development of pronounced subepithelial fibrosis, thickening of the basal membrane, and atrophy of epithelium. Specific structural changes in bronchial mucosa of the patients presenting with BA underlie functional disturbances that cause severe bronchial obstructive syndrome.