Comparison of the COBAS TaqMan HBV test with the COBAS Amplicor monitor test for measurement of hepatitis B virus DNA in serum

Quantitation of low hepatitis B virus (HBV) DNA levels in patients with chronic hepatitis B is important for monitoring natural history of disease and treatment efficacy. This study aimed to compare the quantitation range and analytical sensitivity of the newly developed COBAS TaqMan HBV test (TaqMan test) with the COBAS Amplicor HBV Monitor Test (Amplicor test), using the Eurohep HBV reference plasma and serum samples from patients. Serial dilutions (2.7x10(1)-2.7x10(8) copies/ml) of the Eurohep HBV reference plasma and 50 serum samples from chronic hepatitis B patients were tested by both assays. The TaqMan test could detect seven (2.7x10(2)-2.7x10(8) copies/ml) of eight dilutions of the reference plasma, while the Amplicor test could only detect three of them (2.7x10(3)-2.7x10(5) copies/ml). The HBV DNA values measured by the TaqMan test correlated very well with the theoretical Eurohep standard values (r=0.998, P<0.001). There were good correlations between the HBV DNA levels measured by the two assays on both the Eurohep reference plasma (r=0.993, P<0.001) and serum samples from patients (r=0.904, P<0.001). Compared to the Amplicor test, the TaqMan test had a higher sensitivity (50 vs. 300 copies/ml), shorter assay time (6 vs. 10 hr), and wider dynamic range (8 vs. 3 logs), and was more cost-effective in a clinical setting. These data indicate that the TaqMan test is an excellent tool for HBV DNA quantitation.     

Septal unit activity and hippocampal EEG during the sleep-wakefulness cycle of the rat

The functional relationship between septal unit activity and hippocampal EEG was studied during the sleep-wakefulness cycle in chronically implanted unrestrained rats. Results were statistically analyzed in order to obtain the time interval and auto and crosscorrelation histograms. During REM sleep and restless wakefulness the hippocampal EEG showed a theta rhythm of 4–8 cps and the septal unit activity was characterized by the presence of rhythmic bursts with a frequency in every single instance similar to that of the hippocampus. The septal units showed a bimodal time interval histogram. Their autocorrelation histogram exhibited a sinusoidal pattern of decreasing amplitude. The crosscorrelation histogram of septal units and the hippocampal EEG also showed a sinusoidal pattern suggestive of the functional relationship between both neural structures. During slow wave sleep and quiet wakefulness there was a disappearance of the hippocampal theta rhythm and rhythmic septal unit bursts. The second mode was missing in the time interval histogram and the auto and crosscorrelation histograms showed an irregular pattern. It is concluded that medial septal nucleus and hippocampal temporal patterns of activity are similar during REM sleep and restless wakefulness.     

Mental fatigue and task control: planning and preparation

The effects of mental fatigue on planning and preparation for future actions were examined, using a task switching paradigm. Fatigue was induced by "time on task," with subjects performing a switch task continuously for 2 hr. Subjects had to alternate between tasks on every second trial, so that a new task set was required on every second trial. Manipulations of response-stimulus intervals (RSIs) were used to examine whether subjects prepared themselves for the task change. Behavioral measurements, event-related potentials (ERPs), and mood questionnaires were used to assess the effects of mental fatigue. Reaction times (RTs) were faster on trials in which no change in task set was required in comparison with switch trials, requiring a new task set. Long RSIs were used efficiently to prepare for the processing of subsequent stimuli. With increasing mental fatigue, preparation processes seemed to become less adequate and the number of errors increased. A clear poststimulus parietal negativity was observed on repetition trials, which reduced with time on task. This attention-related component was less pronounced in switch trials; instead, ERPs elicited in switch trials showed a clear frontal negativity. This negativity was also diminished by time on task. ERP differences between repetition and switch trials became smaller with increasing time on task.     

Theophylline disrupts diurnal rhythms of humoral factors with loss of meal cyclicity

To test the possibility that theophylline induced circadian disappearance of food intake might depend upon rhythmic disruption of blood glucose, insulin and free fatty acids (FFA), theophylline was administered chronically. This markedly lengthened postprandial intermeal intervals during the dark, and induced approximately identical intermeal intervals and identical meal sizes in the light and dark periods. In contrast to the clear light-dark dependent oscillations of serum glucose, insulin and FFA in the controls, the theophyllinized rats lost circadian fluctuation of each of these three chemical substances. Further, theophyllinized rats, unlike controls, had no time-dependent fluctuation in the levels of these substances at ? 120, ?60 or ?15 min preceding the onset of the first meal before the dark. These findings, together with previous reports, explain the disappearance of nocturnal feeding rhythm in theophyllinized rats in terms of functional destruction of circadian regulation in the hypothalamus which modulate the production of chemical determinants of food intake.     

CD8+T-bet+ cells as a predominant biomarker for inclusion body myositis

Background

Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.

Effects of sino-aortic denervation on spectral characteristics of blood pressure and pulse interval variability: a wide-band approach

Sino-aortic denervation (SAD) is employed in cats to evaluate the baroreflex influence on blood pressure (BP) and pulse interval (PI) spectral components from 0·00008 to 0·9 Hz as assessed by FFT wide-band spectra and their 1/f modelling; and the linear coupling between BP and PI and between systolic and diastolic BP as assessed by coherence analysis. Specific procedures have been developed to obtain an effective smoothing of spectra and coherence functions. SAD induced an increase in BP powers from 0·03 to 0·0006 Hz and a power reduction of most of the remaining BP components; a reduction of PI powers at all frequencies; marked deviations of BP spectra from the 1/f trend; a reduction of the coherence between BP and PI from 0·12 to 0·5 Hz and a coherence enhancement at lower frequencies. These findings indicate that the arterial baroreflex modulates both fast and slow spectral components of BP and PI; homogeneously enhances PI fluctuations at all frequencies; produces differentiated effects on BP fluctuations along the frequency axis; and at low frequencies exerts the buffering action on BP through strategies which reduce the BP-PI linear link.     

Factors affecting the size of the detour effect in the kinaesthetic perception of Euclidean distance

Three experiments investigated the mechanisms by which we estimate Euclidean distances on the basis of kinaesthetic cues. In all experiments, blindfolded participants followed straight and curvilinear paths with a stylus. Then, with a straight response movement, they estimated the distance between the end-points of the previously explored path. Experiment 1 was designed to validate the hypothesis—made on the basis of results from a previous study—that errors in the kinaesthetic estimations of distances (detour effect) originate from the difficulty to decompose the displacement vector into relevant and irrelevant components, which would become more severe at points of inflection. Using elliptic paths (no inflections), we demonstrated that errors are indeed reduced considerably. The role of the orientation of the work plane was investigated in Experiment 2 in which the same paths used in our previous study were oriented in the frontal rather than the horizontal plane. The results indicate that the detour effect is independent of the orientation. Moreover, despite the asymmetry that gravity introduces between upward and downward movements, errors in the two directions are almost identical. Experiment 3 addressed two issues. First, we demonstrated that introducing a delay between the exploration of the path and the response did not alter significantly the pattern of errors. By contrast, we demonstrated that errors are severely reduced when the number of paths to be explored is reduced by half. The results of the three experiments are discussed within the context of current theories of sensori-motor coding.     

Target-to-target interval versus probability effects on P300 in one- and two-tone tasks

The P3(00) is an electrophysiological index of neural processing that varies with such stimulus parameters as interstimulus interval (ISI) and target probability, with a common view being that it reflects an endogenous form of memory update. Building on previous research, we argue that relations between P3 amplitude and both ISI and probability may be attributable to the target-to-target interval (TTI). Employing between-subject (Experiment 1; N = 24) and within-subject (Experiment 2; N = 10) designs, the present paper addresses this by testing subjects on a standard two-tone auditory oddball task as well as a one-tone task. In both studies, P3 amplitude increased and latency decreased linearly with TTI, and these relations were relatively unaffected by ISI or probability. This suggests that ISI and probability per se do not independently affect P3 amplitude, and that TTI offers a strong explanation of the reported relations between P3 amplitude and both ISI and probability.