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Biomedical subjects

A C Brown

Publications and source records attributed to A C Brown.

At least 91 records · Page 5Linked to original sources
PubMed1978

Synchronous, sustained oscillation of C-peptide and insulin in the plasma of fasting monkeys.

The previously reported synchronous oscillations in plasma glucose and insulin levels have been further studied to determine whether the phenomenon can be attributed to cyclic secretion or degradation of the hormone. Plasma C-peptide concentrations were measured and found to cycle with the same period as plasma insulin suggesting that the oscillations of insulin arise from changing secretion rather than degradation. The amplitude of C-peptide oscillation was 50 percent that of insulin. Assuming first order kinetics and the same relative rates of disappearance as in humans, this difference in amplitudes in consistent with equal secretion rates for the two peptides.

Animals↗
PubMed1977

Insulin, glucagon, and glucose exhibit synchronous, sustained oscillations in fasting monkeys.

In overnight fasted rhesus monkeys, synchronous, regular oscillations occurred in the plasma concentrations of glucose, insulin, and glucagon. The oscillations displayed a period averaging 9 minutes. The amplitudes for insulin and glucagon were ten and five times greater than for glucose. Insulin cycled in and glucagon out of phase with glucose. In baboons, oscillations of glucose and insulin were smaller than in rhesus monkeys, while in man, regular oscillations were not observed.

Animals↗
PubMed1977

Graphic digitizer analysis of the myelinated axon spectrum in the inferior alveolar nerve of the cat.

The diameter spectrum and other parameters indicating size and shape of myelinated axons were established in a cross-section of the inferior alveolar nerve obtained at the mandibular foramen. The spectrum is bimodal with approximately equal numbers of axons in the Aalpha and Adelta-range, in contrast to unimodal spectra of certain branches contributing to the inferior alveolar nerve.

Animals↗
PubMed1975

Graphic-digitizer analysis of axon spectra in ethmoidal and lingual branches of the trigeminal nerve.

Sections were removed from the lingual and ethmoidal nerves of cats and histologically prepared, and the fibers were analyzed under the light microscope. Neural dimensions were measured by a new technique, employing a graphic digitizer and computer. The outline of a neural structure was traced with the digitizer pen, and the total number of axons, their cross-sectional areas, shapes, diameter spectra, and locations within the nerve were calculated. Both nerves had unimodal axon spectra with the peak between 2 and 6 mum diameter. Differences in axon composition occurred over the diameter range of 9 to 20 mum; the lingual nerve had many axons in this range, the ethmoidal nerve only a few. The total number of myelinated axons was near 4000 in the lingual nerve, near 1400 in the ethmoidal nerve; only the latter had many large-sized Remak bundles (containing C-fibers). Most myelinated axons were not perfectly circular but exhibited various degrees of distortion.

Analog-Digital Conversion↗
PubMed1975

A technique for obtaining scanning electron micrographs in colour.

A digital electronic unit is described which, by modifying the video signal of the scanning electron microscope (SEM), permits the selection of images in separate tonal or grey-scale levels. By the sequential exposure of these grey levels onto colour film with the intervention of colour filters, coloured scanning electron micrographs have been obtained. Full details of the procedure are given. The process is applicable to any normal image capable of being displayed at the scanning electron microscope.

Animals↗
PubMed1974

The REEDS syndrome.

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Abnormalities, Multiple↗
PubMed1971

Observations of isolated enterocytes and of their subcellular components using transmission and scanning electron microscopy.

Isolated epithelial cells and their subcellular organelles were examined both by transmission and by scanning electron microscopy. It was shown that scanning electron microscopy is particularly useful for displaying the three-dimensional structure of the brush border. Furthermore, it has been possible to observe the basal aspect of separated epithelium for the first time. Studies on the scanning electron microscopic appearance of isolated nuclei, mitochondria, and lysosomes did not reveal any evidence of surface structure.

Animals↗