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Biomedical subjects

J Neumann

Publications and source records attributed to J Neumann.

384 records · Page 22Linked to original sources
PubMedDate not supplied

Detection of the acoustic reflex below 80 dB HL.

A new method for detecting the acoustic reflex that utilizes standard otoacoustic emissions recording techniques is introduced and discussed. Two successive identical tone bursts of 100 ms duration and 10 ms interstimulus interval are presented in the occluded ear canal at a repetition rate of one per second. If the acoustic reflex is elicited, the contraction of the stapedius muscle is delayed with respect to the onset of the first stimulus. Hence, the acoustic compliance in the ear canal decreases primarily during the second stimulus. The difference of the microphone signals produced by the two stimuli is computed and averaged across a certain number of repetitions of the sequence. The presentation level is increased until this difference is larger than -40 dB (with respect to the stimulus level) and if its signal-to-noise ratio exceeds 20 dB. For normal-hearing subjects, the acoustic reflex threshold measured with this method is on average 8 dB lower than in a standard clinical setup. In 5 out of the 10 tested hearing-impaired subjects, the new method could detect an acoustic reflex at one or more frequencies where no reflex was detected in the clinical setup.

Adult↗
PubMedDate not supplied

Comparative study of adenoviruses with monoclonal antibodies.

The obtainment of monoclonal antibodies for adenovirus species 4(Ad4) is described. The specificities of selected monoclonal antibodies were determined by means of viral neutralization test in cell culture, immunofluorescence and Enzyme-Linked Immunosorbent Assay (ELISA), in the presence of the following species of human adenovirus: 1, 2, 5 (subgenus C), 4 (subgenus E), 7 and 16 (subgenus B) and 9 (subgenus D). Two monoclonal antibodies species specific to adenovirus 4 (1CIII and 3DIII) and one monoclonal antibody that cross reacted with adenovirus species 4 and 7 (2HIII) were obtained.

Adenoviruses, Human↗
PubMedDate not supplied

Effects of probenecid on blood levels and tissue distribution of ampicillin in fowls and turkeys.

The effect of probenecid (a benzoic acid derivative which competitively inhibits active secretion of weak organic acids by the renal tubules) on serum ampicillin concentrations and the distribution of ampicillin in body organs was examined in fowls and turkeys. An aqueous solution of probenecid coadministered intramuscularly, at 200 mg/kg, with sodium ampicillin solution, at 25 mg/kg, resulted in peak serum antibiotic concentration of 16.5 microgram/ml. A similar dose of ampicillin administered alone produced a peak level of 4.6 microgram/ml. Subcutaneous injections of sodium ampicillin at 25 mg/kg with aqueous probenecid at 200 mg/kg resulted in a peak serum ampicillin concentration (12.8 microgram/ml) three times as high as the peak produced by the subcutaneous injection of ampicillin alone at 50 mg/kg (4.2 microgram/ml). The elimination half-life (t 1/2) of the drug (30 min) was increased to 1.5 hr by coadministration of probenecid parenterally, and serum antibiotic levels greater than or equal to 5.0 microgram/ml were maintained during 3 hours. Ampicillin seemed to be poorly absorbed from the gastrointestinal tract of fowls. A single oral bolus administration of ampicillin trihydrate aqueous suspension produced a peak of 0.6 microgram/ml, and coadministrations of aqueous probenecid suspension at 20, 50, and 100 mg/kg respectively produced peaks of 0.9, 1.25, and 1.5 microgram/ml. During 4 and 5 days, when ampicillin was added to the drinking water at rates of 200 and 50 mg/liter, serum ampicillin levels were rather low (peaks of 0.20 and 0.12 microgram/ml, respectively), and although these levels were increased by 50% with the coadministration of probenecid they were considered to be of limited clinical value for treating systemic bacterial infections. Probenecid did not change the distribution of ampicillin in the organs.

Administration, Oral↗