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Biomedical subjects

P A Sanford

Publications and source records attributed to P A Sanford.

At least 19 recordsLinked to original sources
PubMed1983

Breast consciousness in American society and it's effect on the American woman's adaptation to mastectomy.

The American Cancer Society estimates that more than a hundred thousand American women develop breast cancer every year. Mastectomy is the treatment of choice. While this surgery performs a gratifying service by saving a woman's life, her appreciation is muted by the price she must pay--the loss of a breast and permanent disfigurement. Within the value system of American culture, that price is a considerable one. This paper will attempt to interpret that cost.

Adaptation, Psychological↗
PubMed1978

The effect of bradykinin on the electrical activity of rat jejunum.

Bradykinin increased the potential difference across both the jejunum and colon of the rat. This effect was significantly reduced by indomethacin, suggesting that it was mediated by prostaglandins. The possibility that bradykinin may contribute to the diarrhoea of the carcinoid syndrome by inducing a net secretory state in the intestine is discussed.

Animals↗
PubMed1978

Effect of actively transported hexoses on afferent nerve discharge from rat small intestine.

1. The afferent discharge of mesenteric nerves has been recorded while perfusing salines of different composition through the lumen of rat ileum. The p.d. across the ileum and hexose absorption have also been measured. 2. The ileal mesenteric nerves were sensitive to actively transported hexoses. The discharge recorded increased dramatically on perfusion with 10 or 50 mM-glucose, quietening within 3 min of returning to glucose-free saline. A similar response was obtained with galactose. 3. No change in afferent discharge could be detected on perfusion of mannitol or the slowly transferred hexose, mannose. It is concluded that the response to glucose and galactose is not dependent on the stimulation of non-specific luminal osmoreceptors. 4. Phlorhizin prevented glucose from increasing the afferent nerve discharge. Subsequent perfusion with saline removed the phlorhizin and an afferent nerve response to glucose was restored. It is concluded that this response requires glucose transfer beyond the phlorhizin-sensitive glucose entry mechanism at the luminal side of the mucosal epithelial cell. 5. Very small amounts of glucose or galactose were absorbed under the conditions employed. The time course for the change in p.d. correlated well with that described for the alteration in afferent nerve discharge. 6. Electron micrographs show that ileal nerves consist of bundles of small non-myelinated fibres of approximately 1 micron diameter. 7. The significance of the findings is discussed remembering that carbohydrate absorption is considered to be completed normally in the jejunum.

Action Potentials↗
PubMed1977

The role of acetylcholine in the regulation of ion transport by rat colon mucosa.

1. Acetylcholine increases the potential difference across rat proximal colon both in vivo and in vitro.2. There is a sigmoid relationship between the change in potential difference and the logarithm of the dose of acetylcholine. The dose-response curve is shifted to the left by neostigmine and to the right by atropine, suggesting that the action of acetylcholine is mediated by a muscarinic type of receptor.3. The dose-response curve for acetylcholine in vivo is not altered by the ganglion-blocking agents hexamethonium and pentolinium, suggesting a direct effect of this transmitter on the colon.4. Acetylcholine causes an increase in potential difference, a small decrease in resistance and hence a rise in the current generated by both normal and stripped everted sacs of rat colon.5. In the absence of sodium, the calculated current change produced by acetylcholine is reduced, and the removal of chloride has a similar inhibitory effect. The absence of bicarbonate does not significantly affect the response.6. Acetylcholine virtually abolished net sodium movement and induced net chloride secretion and these changes accounted for the increased short-circuit current.7. Acetylcholine had no effect on oxygen consumption by rings of colon.8. Tracts staining for acetylcholinesterase were observed running from the submucous plexus towards the mucosal epithelium.9. This study shows that acetylcholine can influence ion movement by rat colonic mucosa and suggests that the autonomic nervous system might be involved in the regulation of transport mechanisms in this tissue.

Acetylcholine↗
PubMed1975

Extracellular polysaccharide from the black yeast NRRL Y-6272: improved methods for preparing a high-viscosity, pigment-free product.

When the extracellular polysaccharide from the black yeast NRRL Y-6272, composed of two parts N-acetyl-D-glucosamine and one part N-acetyl-D-glucosaminuronic acid, is isolated at maximum culture viscosity, adhering black pigment gives the polysaccharide preparations a gray-to-black appearance. Precipitation of the polysaccharide from cell-free culture supernatants with either ethanol of hexadecyltrimethylammonium bromide failed to remove the pigment. Various other methods were therefore tried for obtaining a high-viscosity polysaccharide product free of pigment. By systematically varying ingredients of defined and semidefined media, an improved medium was found that not only gave polysaccharide preparations of increased viscosity, but also increased yield. A key ingredient in this medium is L-asparagine. Also, adding autoclaved bovine serum albumin or egg albumin to this medium at the time of inoculation allowed a pigment-free polysaccharide to be isolated by standard procedures. None of several other proteins of synthetic polyamides tested were as effective as bovine serum albumin or egg albumin. In an alternate approach, pink mutants obtained by irradiation of the parent black strain with ultraviolet light, apparently produce the same extracellular polysaccharide free of any pigment but in lower yields or inferior in quality.

Acetylglucosamine↗
PubMed1974

The effect of fasting on hexose transfer in rat intestine.

1. A technique has been developed whereby accurately defined segments of rat intestine can be isolated in vivo, and this technique was used to study the influence of fasting on hexose transport.2. In the distal ileum the transport of glucose and galactose was stimulated by fasting. The effect was specific as neither amino acid transport nor the permeability of the luminal membrane of the absorbing epithelium was altered by fasting. The increased hexose transport was accompanied by a reduced accumulation of hexose in the gut wall. In the proximal jejunum hexose transport was not stimulated by fasting.3. The results of in vitro experiments show the relative importance of hexose metabolism in providing energy for transport in different regions of the small intestine in both fed and fasted animals. In conditions where hexose metabolism was reduced, e.g. by fluoride, the proximal jejunum behaved more like the distal ileum and a stimulation of hexose transport in response to fasting was demonstrable in vivo.4. Motility studies showed that phenol red introduced into the stomach reached the ileum sooner, achieved a higher concentration and remained there for a longer period of time in the fasted animal.5. The changes in carbohydrate metabolism, hexose transport capacity and gastrointestinal motility are discussed in relation to adaptations of the rat to fasting.

Animals↗
PubMed1972

Metabolism and transfer of choline in hamster small intestine.

1. The transfer and metabolism of choline was studied with sacs of everted intestine of hamster.2. Approximately half the choline transferred from the mucosal fluid may be metabolized. High voltage electrophoresis, paper chromatography and ion exchange chromatography have been used to identify this meta bolite as betaine.3. The concentration of choline and betaine together accumulating in the gut wall and serosal fluid are greater than that of choline present initially in the mucosal fluid indicating some kind of specific mechanism for choline transport.4. A detailed analysis of choline transfer suggests that the movement of choline cannot be accounted for by simple diffusion. The concentration of choline accumulating in the gut wall and serosal fluid, the inhibitory effects of hemicholinium-3 and alpha-methylglucoside on choline transfer, and the insensitivity of betaine transfer to hemicholinium-3 suggest a specific active transport process for choline independent of active betaine transport.

Animals↗
PubMed1971

Intestinal transfer of choline in rat and hamster.

1. The transfer of choline was studied with sacs of everted intestine of rat and hamster.2. The choline transfer can be divided into two components, a diffusion process and a saturable process. The latter plays a relatively greater part at low concentrations of choline, which include the physiological concentration in the plasma. The saturable process is better seen in the hamster than in the rat.3. Intestinal transfer of choline is influenced by substances altering the availability of energy in the cell, and by some substances chemically or pharmacologically related to choline. These findings are consistent with some kind of specific mechanism for choline transfer.4. Part of the choline taken up by the cell appears as a metabolite not yet identified. The formation of the metabolite is a saturable process and is abolished by anaerobic conditions and by homogenization.5. The results are also discussed in relation to parameters of transfer.

Air↗
PubMed1970

Effects of fasting on intestinal transfer of sugars and amino acids in vitro.

1. Transfer of sugars, amino acids and fluid and metabolism of glucose were studied with everted sacs of small intestine prepared from fed and 3-day fasted rats.2. In the absence of glucose there was some evidence for increased intestinal transfer of sugars and amino acids in fasted animals. In the presence of glucose there was in general decrease in transfer of amino acids and fluid.3. In fasted animals glucose transfer was reduced except in the lower ileum, and there was a general reduction in glucose metabolism.4. Because of the large reduction in gut weight in fasted animals, expressing transfer on a weight basis is considered not to be a valid procedure in studying the effects of fasting on intestinal transfer.5. The results have been discussed in relation to effects of fasting on energy availability, efficiency of transfer mechanisms, permeability of the intestine and the value of in vitro methods in the study of physiological absorption.

Amino Acids↗