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Biomedical subjects

M Young

Publications and source records attributed to M Young.

At least 415 records · Page 23Linked to original sources
PubMed1976

Basal lamina of human seminiferous tubule- its role in material transport. I. In presence of tunica vaginal hydrocele.

Electron microscopy of testicular biopsies obtained from two adult males with tunica vaginal hydrocele revealed some protrusions from the basal lamina to the germinal epithelium in the seminiferous tubule. The protrusions were of three types: some between the spermatogonia and Sertoli cells, some directly within the Sertoli cell cytoplasm and others inside the spermatogonia. The protrusions inside the spermatogonia were only 0.5 mum deep whereas the other types were from 1-11 mum deep. Occasionally some cut off portions of these protrusions were seen inside the ground cytoplasm of the Sertoli cell without an apparent connection with the original stalk. The matrix of the protrusions contained a homogenous component (composed of a fine filamentous element) and granular and membranous components. These components closely resemble the materials found in the basal lamina of the seminiferous tubule. It has been suggested that under mild pathological conditions, i.e., hydrocele, the junctions between the seminiferous tubule epithelium and the basal lamina become somewhat more flexible. As a result, the protrusions become longer and a passage might be formed to allow the flow of raw materials in or out of the seminiferous tubule.

Adult↗
PubMed1976

Molecular size of nerve growth factor in dilute solution.

Nerve growth factor (NGF) is a protein composed of two identical chains of mass 13,259. An analysis of the sedimentation equilibrium, sedimentation velocity, and gel filtration behavior of dilute solutions of NGF indicates the existence of a rapidly reversible monomer in equilibrium dimer equilibrium and that the association constant K for the reaction at neutral pH is 9.4 X 10(6)M-1. Reaction mixtures consist of equal concentrations of monomer and dimer at a total protein concentration as high as 1.4 mug/ml, and at 1 ng/ml, monomer accounts for greater than 99% of the total. The latter concentration is 20 to 30 times that required for the biological activity of NGF. Several lines of evidence suggest that the dimerization reaction is highly stereospecific, although its biological significance is not known.

Animals↗
PubMed1976

Tables in text.

Tables were inserted into a four page article, and subjects were asked to scan the text which was printed in a two-column or a single-column format. The single-column format was scanned significantly faster than the double-column layout, and there were marked reader preferences for the single-column layout.

Journal Article↗
PubMed1976

Use of temperature-sensitive mutants to study gene expression during sporulation in Bacillus subtilis.

Two temperature-sensitive sporulation mutants have been characterized. One mutant, which is blocked at stage II, has a short temperature-sensitive period that occurs at about the time when the spore septum is formed. Cells can escape the sporulation block, if incubated for a short period at the permissive temperature, but are prevented from doing so by inhibitors of transcription and translation; this suggests that the product of the defective gene is a protein and that the messenger ribonucleic acid which codes for this protein is short-lived. The other mutant is blocked at stage IV to V and has a long temperature-sensitive period that starts during stage III and precedes the stage at which the mutational defect is phenotypically expressed. The behavior of this mutant in temperature-shift experiments suggests that synthesis of the product of the defective gene commences long before it assumes its physiological function.

Bacillus subtilis↗
PubMed1976

Resporulation of outgrowing Bacillus subtilis spores.

Germinated spores of Bacillus subtilis were incubated in outgrowth medium and tested periodically for capacity to sporulate when suspended in sporulation medium. Concurrent measurements were made of deoxyribonucleic acid (DNA) content and numbers of cell division septa and nucleoids. Sporulation potential is shown to reach a peak at about 110 min at which time the chromosomes are probably well into the second round of replication. Experiments with nalidixic acid show that sporulation potential can be generated in the outgrowth medium even when DNA synthesis is largely prevented. Further experiments show that nalidixic acid apparently does not prevent the formation of DNA initiation complexes, which can subsequently function after resuspension in the sporulation medium. The results support those previously obtained with a temperature-sensitive DNA mutant which indicated that sporulation could only be induced at a specific stage of chromosome replication, and then only if the cells are in a state of nutritional "step-down".

Bacillus subtilis↗
PubMed1975

Secretion of a nerve growth factor by primary chick fibroblast cultures.

Normal primary chick embryo fibroblast cultures product a nerve growth-promoting factor which cross-reacts with monospecfic antibody to pure male mouse submaxillary gland nerve growth factor (NGF). When taken together with the earlier demonstration that mouse L2 CELLS AND 3T3 cells also produce an NGF-like protein, these findings suggest that secretion of this factor may be a general property of fibroblast.

Animals↗
PubMed1975

On the typing of tables.

This paper argues the case for left-ranging rather than centred tables and reports the time taken by a typist to type left-ranging and centred tables at three levels of complexity complexity. Considerable savings are shown for left-ranging tables at each level.

Journal Article↗
PubMed1975

Muscarinic receptors in rat intestinal muscle: comparison with the guinea pig.

The properties of muscarinic receptors in rat intestinal muscle have been investigated by examining the binding of 3H-propylbenzilylcholine mustard, 3H-PrBCM, a specific and virtually irreversible muscarinic antagonist. It is shown that the properties of these muscarinic receptore correspond in general closely to those observed in the guinea pig, in particular the binding curve inferred for carbachol shows the same apparent negative cooperativity, but there is a notable difference in the rate of binding 3H-PrBCM.

Animals↗
PubMed1975

Secretion of a nerve growth factor by mouse neuroblastoma cells in culture.

Analyses of supernatant solutions from mouse C1300 neuroblastoma cultures by two independent immunoassays reveal that these cells secrete a factor which is immunochemically similar to mouse submaxillary gland nerve growth factor. The neuroblastoma factor is also biologically active in inducing neurite outgrowth from embryonic sensory ganglia-an effect that is completely blocked by specific antibody to nerve growth factor. Neuroblastoma cells are known to be functionally responsive to nerve growth factor, and the observation that they secrete a molecule like it may mean that these cells require or utilize the factor during growth in culture.

Animals↗
PubMed1975

Tumor growth: suppression in mice by submanidibular gland extirpation.

Transplanted A-10 breast adenocarcinomas grew more slowly in young-adult male A/HeJ mice from which the submandibular glands had been extirpated than in sham-operated or unoperated control mice of the same strain. The mitotic index was lower in tumors from experimental animals than in those from controls. Vascularization about the tumor margins was also less prominent. The C1300 neuroblastoma grew more slowly in sialoadenectomized mice than in controls. Modulation of tumor growth by factors of salivary gland origin may have been responsible for these effects.

Animals↗