High prevalence of mixed genotype infections in hepatitis B virus infected intravenous drug users

The clinical relevance of hepatitis B virus (HBV) genotypes has been documented; however, the prevalence of mixed HBV genotype infections in at-risk groups remains controversial. The HBV genotypes were determined in 325 HBV-infected intravenous drug users (IVDU) who were at a greater risk of multiple exposures to different HBV genotypes by using a newly developed line probe assay. The distribution of HBV genotype was as follows: genotype A alone in 2 (0.6%); genotype B alone in 256 (78.8%); genotype C alone in 10 (3.1%); mixed genotype A and B in 18 (5.5%); genotype B and C in 30 (9.2%); genotype B and D in 1 (0.3%); genotype A and C in 1 (0.3%); and mixed infections of genotype A, B, and C in 3 (0.9%). Clonal analysis confirmed further the existence of mixed genotype infection and recombination between different genotypes. Compared with our previous data, the line probe assay seemed more sensitive than polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay in identifying HBV genotype (98.8% vs. 65.0%) and detecting mixed genotype infections (16.3% vs. 0%). In conclusion, the prevalence of mixed HBV infections is substantially higher in IVDU in endemic areas, and the line probe assay is a useful method for rapid genotyping of HBV, with particular reference to the detection of mixed genotype infections.     

The effects of ZD6169 on the ATP-dependent K(+) current (I(K)(ATP)) in isolated cat ventricular myocytes

The effect of the K(ATP) channel opener ZD6169 [(S)-N-(4-benzoyl-phenyl)-3,3, 3-trifluoro-2-hydroxy-2-methyl-propionamide] currently under development for the treatment of urinary incontinence was explored in acutely isolated adult feline ventricular myocytes. ZD6169 activated a current over a wide range of concentrations (0.1-100 microM) that is completely blocked by 10 microM glyburide thereby identifying it as I(K(ATP)). The maximum activation of K(ATP) current was observed at 10 microM; higher concentrations decreased current activation. In contrast, the standard K(ATP) channel opener cromakalim showed a more usual concentration-response relationship, with increasing current for increased concentrations and no signs of saturation or reversal. The bell-shaped dose-response relationship for ZD6169 activation of I(K(ATP)) has also been seen in bladder myocytes, albeit at a lower concentration, and it has been proposed to contribute to the reported lack of in vivo cardiovascular side effects. We compared the effects of ZD6169 to cromakalim and showed that both compounds dramatically shorten cardiac myocyte action potential duration and that ZD6169 does so in spite of the bell-shaped concentration-response relationship for activation of K(ATP) current.     

Immunogenicity and safety of a trivalent tetanus, low dose diphtheria, inactivated poliomyelitis booster compared with a standard tetanus, low dose diphtheria booster at six to nine years of age. Munich Vaccine Study Group

OBJECTIVE: To compare the immunogenicity and safety of a trivalent tetanus-diphtheria (low toxoid content)-inactivated poliomyelitis vaccine, Td-IPV (Revaxis; Pasteur Merièux), with a tetanus-diphtheria (low toxoid content) vaccine, Td (Td-Impfstoff Mérieux; Pasteur Merièux), when administered as a booster to children age 6 to 9 years. METHODS: A group of 301 children were randomized and vaccinated with Td-IPV (n = 150) or Td (n = 151) in this open, controlled, multicenter trial. Serum specimens were obtained before and 28 days after vaccination. Safety was assessed for up to 28 days postvaccination by parental diary cards. Solicited local and systemic reactions were recorded for 7 days after vaccination. RESULTS: Seroprotection (enzyme-linked immunosorbent assay titer, > or =0.10 IU/ml) against tetanus and diphtheria was induced by either Td-IPV or Td in all subjects. Tetanus and diphtheria geometric mean titer were higher after Td (34.0 and 5.74 IU/ml) than after Td-IPV (15.9 and 4.38 IU/ml). All subjects boosted with Td-IPV were seroprotected against each type of poliovirus (neutralizing antibody titer, > or =5/dilution). The most frequently reported solicited local and systemic symptoms were pain triggered by movement of the arm (54% vs. 39.1%) and headache (17.3% vs. 7.3%), after Td-IPV and Td, respectively. All other events were similar between the two groups. Reactions were generally mild and all were temporary. CONCLUSIONS: A booster dose of Td-IPV induced in all children seroprotection against tetanus, diphtheria and poliomyelitis. The overall safety profile of the two vaccines was acceptable.     

Renal oncocytoma: long-term follow-up and flow cytometric DNA analysis

We report a retrospective study on the clinicopathologic features and flow cytometric DNA analysis of ten renal oncocytomas compared with a control group of ten randomly selected renal cell carcinomas. Among the oncocytoma patients, no recurrences or metastases were noted over an average follow-up of 6.7 years (range = 6 months to 16 years). Reproducible, high-quality DNA histograms were obtained on the paraffin-embedded specimens by using our modified flow cytometric procedure. One aneuploid (10%) and two hyperdiploid tumors (20%) were found in the oncocytoma group. There was no correlation between these abnormal DNA histographic patterns and survival or tumor stages. On the contrary, a good correlation was found between tumor grades and DNA ploidy in the controls. We conclude that renal oncocytoma is a clinically benign tumor, yet it may exhibit varying degrees of flow cytometric DNA abnormalities, which have no predictive value on survival and probably reflect the characteristics of oncocytes rather than its malignant potential.     

Toluene disrupts synaptogenesis in cultured hippocampal neurons

Prenatal toluene exposure may lead to significant developmental neurotoxicity known as fetal solvent syndrome. Emerging evidence suggests that toluene embryopathy may arise from an elusive deviation of the neurogenesis process. One key event during neural development is synaptogenesis, which is essential for the progression of neuronal differentiation and the establishment of neuronal network. We therefore aim to test the hypothesis that toluene may interfere with synaptogenesis by applying toluene to cultured hippocampal neurons dissected from embryonic rat brains. In the presence of toluene, hippocampal neurons displayed a significant loss of the immunostaining of synapsin and densin-180 punctas. Notably, a dramatic reduction was also discerned for the colocalization of the two synaptic markers. Moreover, Western blotting analyses revealed that toluene exposure resulted in considerable down-regulation of the expression of synapse-specific proteins. None of the preceding observations can be attributed to toluene-induced cell death effects, since toluene treatments failed to affect the viability of hippocampal neurons. Overall, our data are consistent with the idea that toluene may alter the expression and localization of essential synaptic proteins, thereby leading to a disruption of synapse formation and maintenance.     

Sphingosine modulates myocyte electrophysiology, induces negative inotropy, and decreases survival after myocardial ischemia.

Contractility studies in isolated feline myocytes have demonstrated that sphingosine, a metabolite stimulated by tumor necrosis factor (TNF) binding, decreases intracellular calcium release and depresses inotropic activity. This study investigated the electrophysiologic effects of sphingosine in isolated cat myocytes as well as the cardiodynamic consequence of TNF, sphingosine, and its metabolic precursors in vivo. In cat myocytes, sphingosine markedly decreased action potential duration, lowered action potential plateau, and inhibited L-type calcium current (I(Ca-L)). After administration of TNF, sphingomyelin, C2-ceramide, or sphingosine, only C2-ceramide and sphingosine depressed cardiac function in normal rats. Negative inotropic effects of C2-ceramide were attenuated by N-oleoylethanolamine (NOE), a ceramidase inhibitor that blocks sphingosine formation. Rats pretreated with NOE before undergoing 30 min of acute regional myocardial ischemia followed by 150 min of reperfusion exhibited improved survival. Most deaths could be attributed to acute pump failure accompanied by bradycardia. Myocardial infarct size and peak serum TNF were not different between NOE- and vehicle-treated groups (3,908 +/- 1097 pg/ml and 3,027 +/- 846 pg/ml, respectively). These results indicate that sphingosine exerts direct inhibitory effects on the action potential and I(Ca-L) in isolated feline myocytes, consistent with previously reported sphingosine activity on I(Ca-L) in isolated rat myocytes. The in vivo study suggests that reducing sphingosine production with N-oleoylethanolamine attenuates cardiodepression and can improve overall survival after ischemic injury. Clearly, agents that modulate sphingosine production limit cardiodepression and may provide a therapeutic benefit in clinical conditions of myocardial inflammatory injury.     

Deciduomal estrogen and progesterone receptors in unilateral pregnant hamsters

Deciduomal reactions in response to artificial stimuli were induced on the tube-ligated uterine horns of unilateral pregnant hamsters. Serum progesterone levels were determined, and the changes of estrogen and progesterone receptors (ER and PR, respectively) were simultaneously studied in the deciduoma. After stimulation on day 4 of pregnancy (D4), the serum progesterone level rose steadily to about 16 ng/ml on D12 and remained at plateau until D14. A sharp increase followed by a rapid fall in progesterone was observed on D15 and D16. The weight of the deciduoma-bearing horn increased more than 5 times to a maximal level on D10. Both deciduomal and myometrial weights were maintained and remained elevated on D16. Histological observation revealed that the maintenance of decidual cells was heterogenous. Cells at antimesometrial site (AMS) started to regress on D10, whereas cells at mesometrial site (MS) remained recognizable on D16. Cytosol ER was detected during the early stage (D6) of decidualization. The cytosol ER in the deciduoma continuously decreased and became undetectable on D10. Nuclear ER was not detected during the time of study. The nuclear and cytosol PR increased and reached a peak level on D8 and D10, respectively. The concentration of PR declined sharply afterward. The PR levels in deciduomal tissues at MS and AMS were separately studied. PR in AMS decreased gradually after D8 to basal level on D14. PR at MS still remained relatively constant on D12 followed by a precipitous decrease. These data show a prolongation of the deciduomal life span and the heterogeneity of deciduomal maintenance and regression in unilateral pregnant hamsters. This strongly suggests a close relationship between the loss of PR and the regression of the deciduoma.     

Jaw pain and stiffness levels after repeated maximum voluntary clenching

Ten normal male volunteers performed six maximum voluntary isometric jaw-closing muscle contractions within an 80-minute experimental period. Each individual contraction was sustained until maximum pain tolerance was reached. Before and one, two, three, and seven days after the experiment, the following measures were made: (1) superficial masseter and anterior temporalis muscle tenderness (pain threshold), (2) jaw movement (opening and lateral excursion), and (3) current pain level for the right and left sides of the jaw. In this study, measures of current jaw pain, muscle pain threshold, maximum active opening, and maximum lateral excursions showed no significant post-experimental changes. These results challenge the idea that sustained isometric clenching in healthy male subjects could be used as a model for chronic or even subacute muscle pain, as has been suggested by previous investigators.