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S Southon

Publications and source records attributed to S Southon.

60 records · Page 4Linked to original sources
PubMed1985

Differences in intestinal protein synthesis and cellular proliferation in well-nourished rats consuming conventional laboratory diets.

Male Wistar rats (100 g) were given a commercial pellet feed or a semi-synthetic diet ad lib. Although the pellet-fed group grew slightly faster than the other group during the early part of the feeding period, there was no significantly difference between the final weights of the groups. The fractional rates of protein synthesis in jejunum, proximal ileum and liver were measured by a technique based on the determination of L-[4-3H]phenylalanine incorporation over a short time period. Protein synthesis was higher in both jejunum and ileum of the pellet-fed rats compared with those eating the semi-synthetic diet, but there was no difference between the rates of protein synthesis measured in the livers of the groups. The rate of mucosal cell division was significantly faster in the ileal mucosa of the pellet-fed group compared with the other group, and there were significant differences in some aspects of mucosal morphology. The maintenance of higher rates of cell turnover and protein synthesis in animals given a commercial pellet feed is unexplained, but it may be related to the presence of non-absorbable polysaccharides or other complex plant materials in the pellet feed.

Animal Feed↗
PubMed1985

Intestinal cellular proliferation and protein synthesis in zinc-deficient rats.

Immature male Wistar rats were given a low-zinc semi-synthetic diet (2 mg Zn/kg) for 28 d. Control groups received a similar diet supplemented with 58 mg Zn/kg either ad lib. or in amounts matched to the consumption of the Zn-deficient group. Rates of growth, food consumption and small intestinal length were significantly reduced in the Zn-depleted rats. Zn deficiency in the rat was associated with a reduction in the ratio, crypt: villus and a lower rate of crypt cell division in the jejunum. This resulted in a substantial decrease in the net influx of new cells into the villi of the Zn-deficient animals compared with controls. The fractional rates of protein synthesis in jejunal mucosa were measured by a technique based on the determination of L-[4-3H]phenylalanine incorporation. There was no evidence of a decline in the protein synthetic rate in total mucosa from Zn-deficient rats. It is suggested that a reduction in cell influx into the villi may be responsible for the morphological and functional changes observed in the small intestine of rats fed on a low-Zn diet.

Animals↗
PubMed1984

Hexose transport and mucosal morphology in the small intestine of the zinc-deficient rat.

Immature male Wistar rats were given a zinc-depleted semi-synthetic diet (2 mg Zn/kg diet) for 4 weeks. Control groups received a similar diet containing 60 mg Zn/kg diet, either ad lib. or in amounts matched to the consumption of the Zn-deficient group. Rates of growth and food conversion efficiency were markedly lower in the Zn-deficient group compared to controls. The phloridzin-sensitive uptake of galactose and 3-O-methyl glucose by everted jejunal rings from each group was measured over a range of concentrations. Kinetic analysis revealed that the maximum transport rate (Vmax) for the uptake of both sugars was significantly higher in the Zn-deficient group than in the control groups. The villi, microdissected from samples of proximal jejunum, were significantly shorter and narrower across the base in the Zn-deficient group than those of the control groups, but were present in greater numbers per unit serosal area. The present study shows that Zn deficiency leads to significant morphological changes in rat small intestine, which are accompanied by an increase in the capacity of the tissue to take up sugars across the mucosal membrane.

3-O-Methylglucose↗
PubMed1982

Changes in cellular and subcellular composition during potassium deficiency.

1. A specific dietary deficiency of potassium in young rats reduced the potassium concentration in thigh muscle by 48%, and in heart and kidney by 18%, but did not significantly affect the concentration in liver or brain. Conversely the sodium concentration rose in liver, heart and thigh muscle, and thigh muscle also accumulated increased amounts of magnesium. Apart from an increase in the water content of many tissues, no consistent changes in the composition of major cell constituents were observed. 2. The loss of potassium and accumulation of sodium and magnesium occurred predominantly in the supernatant fraction of the cell. The supernatant of all tissues studied contained about 80% of the total cellular potassium and sodium, and the potassium was present entirely in the ionic form. 3. Potassium and magnesium are the two most abundant intracellular metals, but their deficiencies have very different effects on the cell. The relationship between them is more complex than the inverse relationship between potassium and sodium.

Animals↗