Age-related changes in chemical composition and physical properties of mucus glycoproteins from rat small intestine.

Mucus glycoproteins from newborn and adult rat small intestine were radiolabelled in vivo with Na2 35SO4 and isolated from mucosal homogenates by using Sepharose 4B column chromatography followed by CsCl-density-gradient centrifugation. Non-covalently bound proteins, lipids and nucleic acids were not detected in the purified glycoproteins. Amino acid, carbohydrate and sulphate compositions were similar to chemical compositions reported for other intestinal mucus glycoproteins, as were sedimentation properties. There were, however, important differences in the chemical and physical characteristics of the mucus glycoproteins from newborn and adult animals. The buoyant density in CsCl was higher for the glycoproteins from newborn rats (1.55 g/ml versus 1.47 g/ml). On sodium dodecyl sulphate/polyacrylamide/agarose-gel electrophoresis, the glycoprotein from newborn rats had a greater mobility than the adult-rat sample. Although both preparations had similar general amino acid compositions, variations were observed for individual amino acids. The total protein content was greater in the glycoprotein from newborn animals (27%, w/w, versus 18%, w/w). The molar ratio of carbohydrate to protein was less in the newborn, primarily owing to a decreased fucose and N-acetylgalactosamine content. Comparison of the molar ratio of fucose and sialic acid to galactose for both glycoproteins demonstrated a reciprocal relationship similar to that described by Dische [(1963) Ann. N.Y. Acad. Sci. 106, 259-270]. The sulphate content was greater in the glycoprotein from newborn rats (5.5%, w/w, versus 0.9%, w/w). Both had similar sedimentation coefficients in a dissociative solvent. These results suggest an age-related difference in the types of mucus glycoproteins synthesized by small intestine.     

Incidence of Dumping after Truncal and Selective Vagotomy with Pyloroplasty and Highly Selective Vagotomy without Drainage Procedure

The incidence of dumping after truncal or selective vagotomy with pyloroplasty and highly selective vagotomy without a drainage procedure was assessed both clinically and experimentally. At a gastric follow-up clinic dumping was found to be significantly less frequent in patients who had undergone highly selective vagotomy without a drainage procedure than in patients who had undergone truncal or selective vagotomy with pyloroplasty (P < 0·05 or < 0·001, respectively). Hypertonic glucose given by mouth provoked the onset of dumping in 20% of patients with duodenal ulcer before operation, in 73% after truncal vagotomy and pyloroplasty, in 80% after selective vagotomy and pyloroplasty, and in 47% after highly selective vagotomy. The test meal also produced significantly greater decreases in blood pressure and increases in pulse rate in patients who had undergone vagotomy with pyloroplasty than in patients who had undergone highly selective vagotomy.     

Fate of Carbon Passing Through the Glucose Pool of Rumen Digesta

The metabolism of the free glucose pool in rumen digesta from sheep fed roughage rations was studied by adding an insignificant quantity of glucose as uniformly labeled (14)C-glucose of high specific activity to in vitro incubation systems. In all experiments wherein only trace quantities of glucose were added to digesta, most of the (14)C-glucose entered acetate. This was true whether label was presented either as a single dose or by continuous addition over a period of 2 hr. Digesta collected at all times after feeding either once daily or at hourly intervals gave similar glucose dissimilation patterns. If, however, a relatively large quantity of carrier glucose was added together with the tracer, the (14)C-acetate: (14)C-propionate ratio was reduced by a factor of about 10. Physical removal of most of the protozoa from digesta generally had little effect on the dissimilation of (14)C-glucose added in tracer amounts, but in one experiment there was a decreased turnover of the free glucose pool and a marked reduction in (14)C entering butyrate. The paucity of (14)C entering propionate when only trace amounts of glucose were added to digesta suggests that this acid was largely formed from substrates whose carbon did not equilibrate with that in free glucose or with that in intermediates of free glucose metabolism.     

Regulation of hepatic l-serine dehydratase and l-serine-pyruvate aminotransferase in the developing neonatal rat

1. The activities of l-serine dehydratase and l-serine–pyruvate aminotransferase were determined in rat liver during foetal and neonatal development. 2. l-Serine–pyruvate aminotransferase activity begins to develop in late-foetal liver, increases rapidly at birth to a peak during suckling and then decreases at weaning to the adult value. 3. l-Serine dehydratase activity is very low prenatally, but increases rapidly after birth to a transient peak. After a second transient peak around the time weaning begins, activity gradually rises to the adult value. Both of these peaks have similar isoenzyme compositions. 4. In foetal liver both l-serine dehydratase and l-serine–pyruvate aminotransferase activities are increased after injection in utero of glucagon or dibutyryl cyclic AMP. Cycloheximide or actinomycin D inhibited the prenatal induction of both enzymes and actinomycin D blocked the natural increase of l-serine dehydratase immediately after birth. Glucose or insulin administration also blocked the perinatal increase of l-serine dehydratase. 5. After the first perinatal peak of l-serine dehydratase, activity is increased by cortisol and this is inhibited by actinomycin D. After the second postnatal peak, activity is increased by amino acids or cortisol and this is insensitive to actinomycin D inhibition. Glucose administration blocks the cortisol-stimulated increase in l-serine dehydratase and also partially lowers the second postnatal peak of activity. 6. The developmental patterns of the enzymes are discussed in relation to the pathways of gluconeogenesis from l-serine. The regulation of enzyme activity by hormonal and dietary factors is discussed with reference to the changes in stimuli that occur during neonatal development and to their possible mechanisms of action.     

Epilepsy and Oral Contraception

A controlled cross-over trial in 20 epileptic women, receiving regular anticonvulsant therapy showed that an oral contraceptive with a low oestrogen/ progestogen content had no significant effect on the average frequency of fits compared with identical dummy tablets.     

Isolation and Partial Characterization of a Staphylococcal Leukocyte Cytotaxin

A factor which attracts rabbit polymorphonuclear leukocytes both in vitro and in vivo was isolated from the culture filtrate of a strain of Staphylococcus aureus. The activity of the chemotactic factor was independent of fresh serum and it was nondialyzable. Incubation of the factor with heat-inactivated human serum markedly inhibited its chemotactic property. The factor was heat-labile (80 C, 10 min) in the crude culture filtrate but was heat-stable when partially purified.