Effects of systemic clonidine on auditory event-related potentials in squirrel monkeys

Event-related potential (ERP), electroencephalographic (BEG), and behavioral data were collected from squirrel monkeys (Saimiri sciureus) in a 90−10 auditory oddball paradigm. Background or target tones were presented once every 2 s, and responses to the targets were rewarded. ERPs were recorded from epidural electrodes following systemic administration of clonidine (0.1 mg/kg) or a saline placebo. EEG power spectra and behavioral performance were assessed simultaneously as indices of behavioral state. Clonidine significantly decreased the area and increased the latency of a P300-like potential. The amplitudes and areas of the earlier P1, N1, and P2 components and a later slow wave-like potential were not reduced, nor were their latencies altered. Clonidine produced increased EEG power in the alpha range (7.5–12 Hz) and decreased power in the upper beta range (20–40 Hz) but did not affect performance in the oddball task. Because two major effects of clonidine are to substantially reduce activity in the noradrenergic nucleus locus coeruleus (LC) and to reduce norepinephrine (NE) release from axons, the present results support the hypothesis that the LC and its efferent projection system are important in modulating the activity of P300-like potentials.     

Rotative agitation RIA: A high sensitivity technique for hepatitis B surface antigen (HBsAg) determinations

With the objective of finding a simpler and more sensitive method than conventional radioimmunoassay testing to detect HBsAg, we have modified the sample volume and first incubation procedure of the Ausria IIA method. There was an up to 9-fold increase in sensitivity without loss of specificity, in different assays, when the first incubation was carried out with a serum sample of 1 ml that was rotatively agitated for 22 h at room temperature. Additionally, 71 samples from which conventional testing had isolated hepatitis B core antibodies were tested with the modified rotative agitation technique and 9 of these specimens (12.67%) were positive for HBsAg. Routine employment of the rotative agitation radioimmunoassay technique to screen HBsAg by blood banks, to detect potential infectious donations that escape conventional testing, could be an effective as well as low-cost procedure to prevent post-transfusion hepatitis B.     

Prospective epidemiological study of invasiveHaemophilus influenzae disease in adults

The incidence and characteristics of invasiveHaemophilus influenzae disease were studied in 43 adult patients admitted to the acute care hospitals in El Vallés County (Barcelona, Spain) between January 1987 and June 1992. The annual incidence ofHaemophilus influenzae disease was 1.2 per 100,000 inhabitants. Pneumonia occurred in 24 patients, meningitis in five, intraabdominal infections in three, obstetric infections in two, epiglottitis in two and cellulitis in one. In six patients the source of infection was unknown. Ten (23 %) of the infections were hospital acquired. Underlying conditions were diagnosed in 30 (70 %) patients. NontypeableHaemophilus influenzae strains predominated in all adult age groups. Sixty-one percent of type b and 34 % of nontypeable strains were ampicillin resistant (p=0.08). Multiple antibiotic resistance was also high among type b (53 %) and nontypeable (18 %) strains. The mortality rate was significantly higher in patients with pneumonia, bactaeremia from an unidentified focus or shock at presentation.