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Biomedical subjects

G Barnes

Publications and source records attributed to G Barnes.

At least 109 records · Page 6Linked to original sources
PubMed1984

Asparagine-linked glycosylation in Saccharomyces cerevisiae: genetic analysis of an early step.

Asparagine-linked glycosylation is a form of covalent modification that distinguishes proteins that are either membrane bound or are in cellular compartments topologically outside of the cell from those proteins that remain soluble in the cytoplasm. This type of glycosylation occurs stepwise, with core oligosaccharide added in the endoplasmic reticulum and subsequent modifications occurring in the golgi. We used tunicamycin, an inhibitor of one of the earliest steps in the synthesis of N-linked oligosaccharide, to select for mutants that are resistant to this antibiotic. Genetic, biochemical, and physiological experiments led to the following conclusions. The synthesis of N-linked oligosaccharide is an essential function in cells. In contrast to mammalian cells, yeast cells do not transport tunicamycin by a glucosamine transport function. We identified a gene, ALG7, that is probably the structural gene for UDP-N-acetylglucosamine-1-P transferase, the enzyme inhibited by tunicamycin. Dominant mutations in this gene result in increased activity of the transferase and loss of the ability of the cell to sporulate. In addition, we identified another gene, TUN1, in which recessive mutations result in resistance to tunicamycin. The ALG7 and TUN1 genes both map on chromosome VII.

Asparagine↗
PubMed1983

Oxygen requirement for cupric ion induced hemolysis.

The Cu(II) induced lysis of rabbit erythrocytes occurs in two phases. First there is a lag period of 60 min where few cells lyse, followed by a period of rapid lysis where most of the remaining cells undergo hemolysis. Lysis is effectively inhibited if the incubation is conducted in nitrogen or if the erythrocytes are pre-saturated with carbon monoxide. These results suggest that oxygenated hemoglobin is necessary for lysis. It has been reported that copper binds to oxyhemoglobin and releases superoxide ion. This additional oxidative stress can initiate lipid peroxidation which leads to cell hemolysis.

Albumins↗
PubMed1983

Ceruloplasmin and the reactions forming diferric transferrin.

The rate of formation of diferric-transferrin has been studied using various combinations of Fe(II), Tf, Cp and h serum. When the reactants were added in a correct physiological sequence, ceruloplasmin and diluted human serum showed the fastest rate of saturation of transferrin.

Blood↗
PubMed1983

Cryptosporidiosis in hospital patients with gastroenteritis.

Among 884 hospital patients with gastroenteritis, 36 (4.1%) were excreting Cryptosporidium oocysts in their stools; only 5 of the 36 patients were also excreting other enteropathogens, while none of 320 hospital patients without gastroenteritis were excreting Cryptosporidium oocysts. Children were more commonly infected with Cryptosporidium (4.8%) than were adults (1.6%). The prevalence of infection was higher (7%) during the summer period of February-May 1981 than in the remainder of the observation period to the beginning of June 1982 (1.9%). The most common clinical manifestation of gastroenteritis in Cryptosporidium-infected patients was diarrhea, lasting from 3 to over 14 days, accompanied by vomiting, anorexia, and abdominal pain. The results show that a small proportion of patients with gastroenteritis are infected with Cryptosporidium, and the importance of the infection needs to be examined.

Adolescent↗
PubMed1982

Development of polyamine and biogenic amine systems in brains and hearts of neonatal rats given dexamethasone: role of biochemical alterations in cellular maturation for producing deficits in ontogeny of neurotransmitter levels, uptake, storage and turnover.

Excessive levels of glucocorticoids are thought to interfere with synaptic development in the central nervous system. In the present study, dexamethasone given to newborn rats produced deficits in brain growth associated with shifts in the developmental pattern of the ornithine decarboxylase/polyamine system consistent with delays in cellular maturation. The effects on the brain were of smaller magnitude and shorter duration than those on the heart or on general growth and were indicative of "brain sparing." Although some biochemical indices of synaptic development of central noradrenergic systems ([3H]norepinephrine uptake into synaptosomes) were quantitatively deficient on a whole-brain basis, the reductions never exceeded the magnitude of effect on brain weight; for other indices (transmitter levels, [3H]norepinephrine into synaptic vesicles), there were little or no apparent developmental deficits. Thus, the effects of dexamethasone on synaptic development in the brain may not reflect a specific action of glucocorticoids over and above their more general effects on cellular maturation. In contrast to the lack of specific action on biochemical indices of synaptic outgrowth, neonatal dexamethasone did cause alterations in norepinephrine synthesis and turnover in both central and peripheral sympathetic neurons which could contribute to the physiological and behavioral abnormalities associated with glucocorticoid treatment during development.

Animals↗
PubMed1982

Wrongful dismissal--an expensive mistake.

A contract of employment is based on implied terms (a nurse can be expected to work shifts while the same does not apply to a secretary in the purchasing department), on conduct (unacceptable tardiness or laxity can become an accepted term of the contract if it is not corrected by the employer), and on agreements either express (a signed contract) or implied (the acceptance of personnel manual terms during a probationary period). An employee's service can not be terminated without reasonable notice except for cause. To determine if summary dismissal (cause) is warranted, apply the test described in Stilwell v. Audio Pictures Ltd.

Absenteeism↗