PubMed Health⌕ Search

Biomedical subjects

S Austin

Publications and source records attributed to S Austin.

At least 127 records · Page 7Linked to original sources
PubMed1980

Influence of maternal diet on plasma-prolactin levels during lactation.

An improvement in maternal diet produced significant reductions in plasma-prolactin concentration at all stages of lactation. The prolonged high prolactin concentrations found in undernourished mothers may ensure milk synthesis when food intake is limited, by preferentially channelling nutrients towards the breast. The lower hormonal levels associated with improved maternal nutrition may shorten the period of post-partum infertility despite prolonged breast-feeding.

Amenorrhea↗
PubMed1979

The relationship between hormonal balance and growth in malnourished children and rats.

Plasma concentrations of insulin, cortisol and growth hormone, and growth velocities have been measured in a group of Gambian village children up to 3 years of age. All three hormones showed changes in concentration with age, as did rates of growth. 2. Plasma insulin concentrations in the children were directly correlated with velocity of growth in height and weight, whereas cortisol concentrations showed inverse relationships. The values for insulin:cortisol concentration correlated more closely with growth velocity than did either hormone individually. Growth hormone values in plasma exhibited only marginal correlations with growth in height or weight, and these were negative. 3. Similar relationships between these hormones and growth were obtained from an animal experiment in which the rates of growth of rats were altered by restricting dietary intake of protein or energy or both. 4. Possible mechanisms for these observations are discussed in the light of recent knowledge concerning the hormonal control of growth rates.

Animals↗
PubMed1978

Analysis of bacteriophage P1 immunity by using lambda-P1 recombinants constructed in vitro.

We describe the dissection and reconstruction of a complex control circuit, the P1 immunity system, by a method that involves inserting EcoRI-generated fragments of P1 DNA into lambda vectors that can then be sequentially inserted into a bacterial cell. Using these techniques we have isolated lambda-P1 hybrid phages that express the products of P1 genes c1, c4, ant, and ban and, in appropriately constructed lysogens, confirmed the roles played by the first three of these products in phage immunity. In addition we have localized to particular P1 fragments the sites requisite for expression and repression of these gene products. The analysis leads to the conclusion that gpant acts in trans to antagonize repression mediated by gpc1, in support of one of two proposed models for gpant action. Moreover, two features of the immunity system are revealed: (i) a hitherto unknown component that effects gpc1 repression; and (ii) an unexpected ability of gpc4 to channel a superinfecting c1+ phage into the lysogenic state, which suggests that gpc4 activity regulates the establishment phase of lysogeny.

Alleles↗
PubMed1976

Home culturing program for children with recurrent bacteriuria.

One hundred forty-one children were selected from a clinic for children with recurrent bacteriuria to participate in a home culturing program. The parent was taught to employ a semiquantitative method to test the child's urine for bacteria. The degree and persistence of bacteriuria as detected by the parent strongly correlated with results obtained in the clinic, although there was a significant incidence of false-positive results as detected by the parent. Home culturing proved to be an inexpensive, reliable technique for following up children with recurrent urinary tract infections.

Bacteria↗
PubMed1976

Biparietal diameter: a comparison of real time and conventional B scan techniques.

Real time multitransducer B scanners can greatly facilitate obstetrical ultrasound examination. To assess the accuracy and reproducibility of biparietal diameter (BPD) measurement with the real time scanner, we compared the BPD using the real time scanner with the results obtained by conventional bistable leading edge and gray scale measurements. The results show that 73 to 90 per cent of the results with the real time scanner are within 1 mm of the other measurement and 94 per cent are within 2 mm. The variance of measurements on each case with the real time scanner is not significantly greater than the variance using the other two methods. We feel that the real time scanner can be a useful tool for obstetrical examinations and is accurate in the measurement of the biparietal diameter.

Cephalometry↗
PubMed1976

The effect of cortisone acetate on the course of development of experimental protein-energy malnutrition in rats.

1. The role of corticosteroids in determining which clinical features of protein-energy malnutrition develop on a deficient diet has been studied by the administration of cortisone acetate to experimentally malnourished rats fed ad lib. on a mixture containing 31 g protein/kg. 2. Daily administration of 1-25 mg cortisone acetate did not affect dietary intake, which remained the same as in saline (9 g sodium chloride/l)-injected controls. Plasma albumin concentrations, however, increased from a low value of 25-7 g/l to 47-2 g/l and this was accompanied by an increase both in liver weight and protein content. On the other hand, the protein content of muscle decreased. 3. These changes in the protein contents of liver and muscle were associated with alterations in the corresponding free amino acid pools. The free amino acid content of muscle generally decreased, but in liver many amino acids were increased.

Adrenal Cortex Hormones↗
PubMed1976

Wild-type and mutant in vitro products of an operon for ribonucleic acid polymerase subunits.

An in vitro protein-synthesizing system can synthesize two ribonucleic acid (RNA) polymerase subunits of Escherichia coli, beta and beta', when a transducing phage deoxyribonucleic acid (DNA) template containing the rpoB region of the bacterial chromosome is added. Recombinant rpoB transducing phages were isolated that carry "nonsense" mutations of the class rpo-rifampin zero amber (formally referred to as rifoam). DNA was extracted from two of these phages. These DNAs are unable to direct the synthesis of beta subunits, whereas beta' synthesis is unaffected. Both mutations can be efficiently suppressed in vitro by the addition of suppressor transfer RNA. One of the mutations (rpoB115) produces a detectable nonsense (or restart) fragment of the beta protein in the absence of suppression. It is concluded that rpoB115 is an amber mutation within the structural gene for the beta subunit of RNA polymerase.

Cell-Free System↗
PubMed1973

The synthesis in vitro of RNA polymerase subunits of Escherichia coli.

DNA from transducing bacteriophage that carry the structural gene for the beta subunit of RNA polymerase has been used to direct protein synthesis in a cell-free transcription-translation system. A polypeptide species has been detected which appears to be beta-subunit material made in vitro.

Cell-Free System↗
PubMed1973

Isolation and characterization of phi80 transducing bacteriophage for a ribonucleic acid polymerase gene.

A new method for isolating specialized transducing phages is described. It was used to isolate a group of phi80 transducing phages which carry various bacterial markers from the metB region of the Escherichia coli chromosome. Some of the phages selected for transduction of the supA36 marker were also shown to carry rif, a locus known to specify the beta subunit of ribonucleic acid polymerase. Expression of the prophage rif(r) gene in lysogens was demonstrated by its ability to confer rifampin resistance on part of the cellular ribonucleic acid polymerase pool.

Chromosome Mapping↗
PubMed1966

Fluorescent-antibody and histological study of vaccinated and control monkeys challenged with Shigella flexneri.

Formal, Samuel B., (Walter Reed Army Institute of Research, Washington, D.C.), T. H. Kent, S. Austin, and E. H. LaBrec. Fluorescent-antibody and histological study of vaccinated and control monkeys challenged with Shigella flexneri. J. Bacteriol. 91:2368-2376. 1966.-Groups of monkeys were fed four doses of a living Escherichia coli-Shigella flexneri 2a hybrid strain, and, together with control animals, were challenged with virulent S. flexneri 2a. Two experiments were carried out; in the first, the animals were challenged 10 days after and in the second, 1 month after the last vaccine dose was administered. At 48 hr after challenge, tissues were removed from the vaccinated and control animals, and examined by use of histological and fluorescent-antibody techniques. The results of this study demonstrate that the animals receiving the vaccine were protected from the tissue damage ordinarily observed after experimental challenge with virulent dysentery bacilli. The virulent challenge strain appeared to be unable to penetrate into the intestinal mucosa of immunized animals.

Animals↗