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Biomedical subjects

G Horn

Publications and source records attributed to G Horn.

211 records · Page 12Linked to original sources
PubMed1966

An analysis of spontaneous impulse activity of units in the striate cortex of unrestrained cats.

1. Recordings were made from sixty-five cells in the visual cortex of unanaesthetized, dark-adapted cats and transferred automatically to computer input paper tape.2. The activity of each cell was measured as a function of time (the running mean). The unit of time used was inversely proportional to the mean firing rate, in order to give comparable results for different cells.3. For sixty-nine sections of discharge from fifty-two cells, the length of time recorded was sufficient to test for the long-term stability of the running mean. In twenty-six sections, various kinds of trend and long-term irregularity were found.4. The interspike interval histogram was computed for the forty-one sections (from thirty-one cells) in which there were more than 2000 discharges. Only eight histograms approximated closely to the exponential form. A test was also made of the distribution of the longer intervals alone and in twenty-five sections they did not deviate significantly from the exponential form.5. There was no significant correlation between the behaviour of the longer interspike intervals and the long-term stability or otherwise of the running mean.

Adaptation, Physiological↗
PubMedDate not supplied

Effect of nicotine on mRNA levels encoding opioid peptides, vasopressin and alpha 3 nicotinic receptor subunit in the rat.

The effect of acute and chronic nicotine treatment of rats on the mRNA levels coding for the three opioid peptide precursors, for provasopressin and for the alpha 3 subunit of nicotinic receptors in brain, pituitary and/or adrenal medulla of rats was investigated. Nicotine was found to increase the levels of proenkephalin mRNA in the adrenal medulla, but did not affect the levels of PENK mRNA in striatum, hypothalamus and hippocampus. The mRNA levels of prodynorphin were increased together with that of provasopressin in the hypothalamus after nicotine, whereas the prodynorphin mRNA levels in the hippocampus and the striatum remained unchanged. Nicotine treatment resulted in an increase in the pro-opiomelanocortin mRNA levels in the anterior pituitary and in a decrease in the intermediate pituitary, but did not change the levels of pro-opiomelanocortin mRNA in the hypothalamus. The levels of mRNA coding for the alpha 3 subunit of nicotinic receptors in the hypothalamus and the adrenal medulla remained unchanged. The increase in the prodynorphin and provasopressin mRNA levels in the hypothalamus was most pronounced 1 day after s.c. application of two doses of 0.4 mg/kg nicotine (about 100% above control). A smaller increase in mRNA concentrations (about 30%) was found after tonic infusion of the drug for 4 days (4 mg/kg per day), whereas no change was observed after tonic infusion of nicotine for 7 and 14 days indicating the development of complete tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMedDate not supplied

Clonal distribution of multiple-drug-resistant Shigella sonnei strains: identification by means of plasmid pattern analysis.

The spread of particular clones of S. sonnei throughout the territory of the German Democratic Republic within one year was evaluated by means of plasmid pattern analysis of the bacterial isolates. Such epidemic clones are described by their "clone formulae" comprising the phage type, biotype, colicinogenotype, antibiogram and the plasmid pattern type. They were not observed before 1982, but potential progenitor strains could be identified as having occurred sporadically in the years before. The additional application of plasmid pattern analysis revealed a better discrimination of the epidemic distribution of distinct bacterial clones than the use of conventional methods such as phage-typing, biotyping and colicinogenotyping only.

Bacteriological Techniques↗
PubMedDate not supplied

Dermatology outpatients in the West Midlands: their nature and management.

There is a lack of routinely available information about dermatology outpatient consultations which form the majority of the clinical work of this specialty. This survey was undertaken to prepare for clinical audit and assist in planning future developments of the service. Data were recorded from 2,940 outpatient consultations held during one week by 20 consultant dermatologists and their staff in the West Midlands Health Region in November 1988. The results show that collection and analysis of Regionwide data for a small specialty is feasible, and have indicated future areas of study for clinical audit.

Data Collection↗