The initial rates and steady-state values of proton uptake by broken chloroplasts have been measured as functions of light intensity at various concentrations of chlorophyll, pyocyanine, supporting electrolyte, buffer, as well as pH and temperature. Kinetics analysis of the data shows that the rate of decay of proton gradient due to backward leakage depends on light intensity. Under steady illumination, the decay constant kL is equal to kD + mR0, where R0 is the initial rate of proton uptake which is a function of light intensity, kD is the decay constant in the dark and m is a parameter which is independent of light intensity. Treatment of chloroplasts with lysolecithin, neutral detergent, 2,4-dinitrophenol, or valinomycin in the presence of K+ increases kD without affecting m. Treatment with N,N'-dicyclohexylcarbodiimide or adenylyl imidodiphosphate under appropriate conditions decreases m without affectsity and hence m = 0. These results suggest that the light-dependent part (mR0) of kL is due to leakage of protons through the coupling factor (CF1-CF0) complex which can open or close depending on light intensity and that the light independent part (kD) of the decay constant kL is due to proton leakage elsewhere.

Adenylyl Imidodiphosphate↗

PubMedDate not supplied

Molecular epidemiology of hepatitis B viral serotypes and genotypes in taiwan.

Subtypes of hepatitis B virus (HBV) have specific geographic distributions and can serve as epidemiological markers. The relationship of HBV serotypes and genotypes in Taiwan and their correlation with the domiciles of origin in 122 patients with chronic HBV infection were investigated. The serotype of HBV was determined by comparing the surface gene encoding amino acids 22-148 of the major surface protein with published sequences. Genotyping of HBV was performed by polymerase chain reaction-restriction fragment length polymorphism. Serotype adw accounted for 70% (85/122) of all HBVs, with the remaining belonging to serotype adr. All adr HBVs were genotype C, regardless of the patient's domicile. Of the 85 adw HBVs, 69 (81%) were genotype B, 10 (12%) were genotype C, 5 (6%) were genotype F and only 1 (1%) was genotype A. In the 31 patients originating from mainland China, the prevalence of adr/genotype C was higher than in the 91 Taiwanese patients (15/31 vs. 22/91; p < 0.05). The distribution of the HBV serotypes and genotypes was not significantly different between 17 patients born in Taiwan (6 adw/genotype B, 2 adw/genotype C, 1 adw/genotype F and 8 adr/genotype C) and 14 patients born in mainland China (5 adw/genotype B, 2 adw/genotype C and 7 adr/genotype C). Our results indicate that in Taiwan, most HBVs of serotype adw are genotype B, and all HBVs of serotype adr are genotype C. Patients with origins in mainland China have a higher proportion of serotype adr/genotype C infection.

Adult↗

PubMedDate not supplied

Reproducibility of visual activation during checkerboard stimulation in functional magnetic resonance imaging at 4 Tesla.

PURPOSE: To investigate the reproducibility of visual activation by checkerboard stimulation, we used functional magnetic resonance imaging (fMRI) at 4 Tesla (T). METHODS: Four subjects were studied with fMRI at 4 T during checkerboard visual stimulation. The functional images were realigned and spatially normalized to the standard brain. For each subject, statistical parametric maps were made for each study, and the reproducibility was determined based on the number of supra-threshold voxels (Z > 3.5, 4.5, and 5.5). RESULTS: The mean ratio for the number of supra-threshold (Z > 4.5) voxels was 0.75, and the mean ratio for the overlapping voxels was 0.61. Restricting the region of interest within the posterior half of the brain improved reproducibility values at the low threshold (Z > 3.5), but did not improve the values at the higher thresholds. CONCLUSIONS: Despite the fact that more than half of the supra-threshold voxels were found to be active for the repeated scans, visual activation with checkerboard stimulation seems to be less reproducible than that by flash stimulation.

Adolescent↗

PubMedDate not supplied

Safety and efficacy of cefpirome in comparison with ceftazidime in Chinese patients with sepsis due to bacterial infections.

BACKGROUND: The safety and efficacy of cefpirome (CPM), a fourth-generation cephalosporin, has not yet been studied in an Asian population. METHODS: Sixty-nine adult Chinese patients with sepsis due to bacterial infections were enrolled in the study and randomly assigned to receive CPM (2 g i.v. every 12 h) or ceftazidime (2 g i.v. every 8 h). RESULTS: Both groups were comparable in terms of demographic, clinical and microbiological features. The causative pathogen was Escherichia coli or Klebsiella pneumoniae in the majority of microbiologically documented cases. The rates of clinical response (94 vs. 94%) and bacteriological response (65 vs. 68%) were similar in both groups. Similar adverse events, including rashes, gastrointestinal upset and asymptomatic elevation of hepatic enzymes, occurred in a minority of patients in both groups. All events were self-limited after discontinuation of the drugs. CONCLUSION: CPM is as safe and effective as ceftazidime in the treatment of sepsis due to bacterial infections in Chinese patients.

Adult↗