Activation and cell cycle antigens in CD4+ and CD8+ T cells correlate with plasma human immunodeficiency virus (HIV-1) RNA level in HIV-1 infection

gamma-Sarcoglycan is a transmembrane, dystrophin-associated protein expressed in skeletal and cardiac muscle. The murine gamma-sarcoglycan gene was disrupted using homologous recombination. Mice lacking gamma-sarcoglycan showed pronounced dystrophic muscle changes in early life. By 20 wk of age, these mice developed cardiomyopathy and died prematurely. The loss of gamma-sarcoglycan produced secondary reduction of beta- and delta-sarcoglycan with partial retention of alpha- and epsilon-sarcoglycan, suggesting that beta-, gamma-, and delta-sarcoglycan function as a unit. Importantly, mice lacking gamma-sarco- glycan showed normal dystrophin content and local- ization, demonstrating that myofiber degeneration occurred independently of dystrophin alteration. Furthermore, beta-dystroglycan and laminin were left intact, implying that the dystrophin-dystroglycan-laminin mechanical link was unaffected by sarcoglycan deficiency. Apoptotic myonuclei were abundant in skeletal muscle lacking gamma-sarcoglycan, suggesting that programmed cell death contributes to myofiber degeneration. Vital staining with Evans blue dye revealed that muscle lacking gamma-sarcoglycan developed membrane disruptions like those seen in dystrophin-deficient muscle. Our data demonstrate that sarcoglycan loss was sufficient, and that dystrophin loss was not necessary to cause membrane defects and apoptosis. As a common molecular feature in a variety of muscular dystrophies, sarcoglycan loss is a likely mediator of pathology.     

Enhancement by hyperthermia of the in vitro cytotoxicity of mitomycin C toward hypoxic tumor cells

Mitomycin C and hyperthermia are both toxic to chronically hypoxic EMT6 tumor cells. Combinations of this drug and heat were tested in vitro in normally aerated and chronically hypoxic EMT6 mouse mammary tumor cells to establish whether greater than additive cytotoxicity could be achieved by combined treatment. Cell survival was measured at four concentrations of mitomycin C (0.01, 0.1, 1.0, and 10 microM) at 37 degrees or at elevated temperatures (41, 42, and 43 degrees) for durations of 1, 2, 3, and 6 hr. At 42 degrees, exposure to mitomycin C for 3 and 6 hr produced a 2- to 3-fold increase in hypoxic tumor cell kill at all drug concentrations over that expected for strict additivity. A 15-fold enhancement in the kill of hypoxic tumor cells was obtained at 1.0 and 10 microM mitomycin C at 43 degrees for 6 hr of exposure. Under most conditions, additivity was observed for the antibiotic and heat in oxygenated cells, except at 43 degrees with 0.01 and 0.1 microM mitomycin C following 3 and 6 hr of treatment, conditions under which a 5- to 10-fold potentiation of tumor cell kill was obtained. The rate of formation of reactive metabolites from mitomycin C under anaerobic conditions in EMT6 cell-free preparations was measured. A 30 to 50% increase in alkylating activity was observed at elevated temperatures, suggesting that the enhanced cytotoxicity of mitomycin C with heat toward hypoxic cells may, in part, be due to an increase in activation of the drug.     

Logistic regression analysis of twin data: estimation of parameters of the multifactorial liability-threshold model

This study with the rat evaluated the contribution of omega-conotoxin GVIA-(omega-CgTx) and verapamil-sensitive Ca2+ channels in behavioural, antinociceptive and thermoregulatory responses to intracerebroventricular (i.c.v.) injection of [D-Ala2,NMePhe4,Gly-ol5]enkephalin (DAMGO), [D-Pen2,D-Pen5]enkephalin (DPDPE) and dynorphin A-(1-17), which are selective agonists for putative mu, delta and kappa-opioid receptors, respectively. The rats treated with omega-CgTx (8-32 pmol i.c.v.) showed transient, dose-dependent shaking behaviour, hyperalgesia and hypothermia which gradually disappeared within 4 h. The behaviour of the rats was normal by 24 h. Histological examination of brain sections showed morphological alterations of neurons in the hippocampus, medial-basal hypothalamus and pyriform cortex. antinociception, catalepsy and thermoregulatory responses elicited by DAMGO (0.4 and 2.0 nmol) were significantly prolonged and potentiated by verapamil (20 pmol i.c.v. 15 min before) or omega-CgTx (8 pmol 24 h before). Antinociception and hypothermia induced by DPDPE were antagonized by verapamil and omega-CgTx, whereas only omega-CgTx prevented the behavioural arousal observed after DPDPE. Similarly, hypothermia induced by dynorphin A-(1-17) (5.0 nmol) and by the kappa-opioid receptor agonist U50,488H (215 nmol) was antagonized by the two Ca2+ channel blockers but only omega-CgTx prevented the barrel rolling and bizarre postures caused by the opioid peptide.     

Factors influencing the response to interferon therapy in chronic hepatitis C. Studies on viral genotype and induction of 2',5'-oligoadenylate synthetase in the liver and peripheral blood cells

BACKGROUND: The mechanism behind the antiviral action of interferon (IFN) therapy in chronic hepatitis C virus (HCV) infection is not well understood, and, furthermore, few factors have been shown to be good predictors of a favourable response to IFN treatment in chronic HCV infection. METHODS: Freshly explanted liver cells and peripheral blood mononuclear cells (PBMC) from 80 patients with chronic HCV infection were used to study the capacity of IFN to induce the enzyme 2',5'-oligoadenylate synthetase (2'5'-AS) in vitro. The HCV genotype was determined in 53 patients. The induction of 2'5'-AS was correlated to the results of IFN-alpha treatment in 36 patients. RESULTS: Normalization of transaminases during IFN treatment was significantly associated with 2'5'-AS levels in liver cells cultured in the absence of IFN. A similar tendency, although not statistically significant, was found for IFN-induced levels of 2'5'-AS in liver cells. No such associations were found when PBMC were analysed. Six patients showed a sustained biochemical response. These six did not deviate significantly from the remaining patients with regard to base-line or IFN-induced levels of 2'5'-AS in liver cells or PBMC. Eradication of HCV RNA during IFN treatment did not correlate with 2'5'-AS levels in liver cells. Comparison of HCV genotype and clinical response showed that patients with genotype 3a had the most favourable outcome. No association was found between liver histology and treatment outcome. CONCLUSION: These data imply that direct effects of IFN on liver cells are of importance for the response to IFN treatment.     

Brazilian isolates of Trypanosoma cruzi from humans and triatomines classified into two lineages using mini-exon and ribosomal RNA sequences

Traditional molecular and biochemical methods, such as schizodeme analysis, karyotyping, DNA fingerprinting, and enzyme electrophoretic profiles, have shown a large variability among Trypanosoma cruzi isolates. In contrast to those results, polymerase chain reaction (PCR) amplification of sequences from the 24S alpha ribosomal RNA gene and from the mini-exon gene nontranscribed spacer indicated a dimorphism among T. cruzi isolates, which enabled the definition of two major parasite lineages. In the present study, 86 T. cruzi field stocks (68 isolated from humans with defined presentations of Chagas' disease and 18 from triatomines) derived from four Brazilian geographic areas were typed by the PCR assay based on the DNA sequences of the mini-exon and 24S alpha rRNA genes. These stocks were ordered into the two major T. cruzi lineages. Lineage 1 was associated mainly with human isolates and lineage 2 with the sylvatic cycle of the parasite.     

Ocular toxicity from ethambutol: a review of four cases and recommended precautions

AIMS: To document the clinical and demographic features of cases of ethambutol ocular toxicity, to review the literature on this subject and to critically review current guidelines for ethambutol administration. METHODS: Cases of ocular toxicity from ethambutol were sought retrospectively at Green Lane and Wellington Hospitals between 1992 and 1995. The records of cases identified were examined. RESULTS: Four subjects with tuberculosis developed ocular toxicity 2 1/2, 7 1/2, 8 and 12 months after starting ethambutol. Normal visual acuity returned in three cases; one patient has severe, permanent visual impairment. Language difficulties were present in three subjects. CONCLUSIONS: Impaired communication was potentially very important in this series. Special care is needed in educating patients about ethambutol. We propose additional recommendations: 1. the usual daily dose of ethambutol should be 15 mg/kg/day, not 25 mg/kg/day; using 25 mg/kg/day (or lesser doses in the presence of renal impairment) should prompt regular formal ophthalmological evaluation (e.g. monthly) in cases with comprehension or communication difficulties; 3. both ethambutol and isoniazid should be stopped immediately if severe optic neuritis occurs. Isoniazid should be stopped if less severe optic neuritis does not improve within six weeks after stopping ethambutol.     

Glycated hemoglobin reference limits obtained by high performance liquid chromatography in adults and pregnant women

Pentachlorophenol (PCP) and molybdate have been shown to inhibit the sulfoconjugation of various chemicals in rats and therefore are useful to examine the role of sulfoconjugation on the toxicity of a chemical. PCP inhibits sulfation by competing with substrates for phenol-sulfotransferases, but not hydroxysteroid-sulfotransferases. In contrast, molybdate decreases sulfation by limiting sulfate availability and thereby decreasing the synthesis of 3'-phosphoadenosine 5'-phosphosulfate (PAPS), which is the obligate cosubstrate for sulfation. Therefore, it was of interest to determine whether PCP or molybdate is effective in decreasing the in vivo sulfation of dehydroepiandrosterone (DHEA), which is a substrate for hydroxysteroid-sulfotransferases. PCP (40 micromol/kg ip) or molybdate (7.5 mmol/kg po) was given 45 min and 4 h, respectively, prior to the start of DHEA infusion. The effects of these two sulfation inhibitors on DHEA sulfation were dependent on the rate of DHEA infusion in rats. PCP had different effects on the sulfation of various infusion rates of DHEA in rats. PCP had little effect on the sulfation after the two lowest infusion rates of DHEA (12.5 and 25 mg/kg) and actually increased (233%) DHEA-sulfate serum concentrations with the highest DHEA infusion rate (50 mg/kg). Although molybdate had little affect on the sulfation of the lowest DHEA infusion rate, it significantly decreased (50-85%) DHEA-sulfate serum concentrations with the two higher DHEA infusion rates. These data indicate that molybdate, unlike PCP, decreases the sulfation of DHEA and may be a useful tool to decrease the sulfation of other substrates of hydroxysteroid-sulfotransferases.