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S Butcher

Publications and source records attributed to S Butcher.

27 records · Page 2Linked to original sources
PubMed1991

Class-3 porin protein of Neisseria meningitidis: cloning and structure of the gene.

The gene coding for the class-3 protein of Neisseria meningitidis was cloned and sequenced. The deduced amino acid (aa) sequence was highly homologous (50-78%) to those of other neisserial porin proteins. Alignment of the aa sequence of five neisserial porin proteins pinpointed several regions of identity or near identity. These are assumed to be membrane-spanning beta-strands. A comparison of the homologies between these neisserial porins showed that the class-3 protein is most closely related to the Neisseria gonorrhoeae P1A protein.

Amino Acid Sequence↗
PubMed1990

Changes in extracellular glutamate concentration after acute subdural haematoma in the rat--evidence for an "excitotoxic" mechanism?

Using a rat model of subdural haematoma which is associated with ischaemic damage in the ipsilateral hemisphere, we have measured cerebral blood flow and release of excitatory amino acids after the haematoma. A more than sevenfold rise in glutamate and aspartate, persisting for forty minutes occurred in the severely ischaemic cortex (CBF less than 5 ml 100 gm-1 min-1) and a threefold, sustained rise was seen in hippocampus, although CBF was preserved (85 ml/100 g/-1 min-1). Excitotoxic mechanisms may, therefore, be involved in the ischaemic damage associated with subdural haematoma.

Acute Disease↗
PubMed1987

Extracellular adenosine, inosine, hypoxanthine, and xanthine in relation to tissue nucleotides and purines in rat striatum during transient ischemia.

Extracellular (EC) adenosine, hypoxanthine, xanthine, and inosine concentrations were monitored in vivo in the striatum during steady state, 15 min of complete brain ischemia, and 4 h of reflow and compared with purine and nucleotide levels in the tissue. Ischemia was induced by three-vessel occlusion combined with hypotension (50 mm Hg) in male Sprague-Dawley rats. EC purines were sampled by microdialysis, and tissue adenine nucleotides and purine catabolites were extracted from the in situ frozen brain at the end of the experiment. ATP, ADP, and AMP were analyzed with enzymatic fluorometric techniques, and adenosine, hypoxanthine, xanthine, and inosine with a modified HPLC system. Ischemia depleted tissue ATP, whereas AMP, adenosine, hypoxanthine, and inosine accumulated. In parallel, adenosine, hypoxanthine, and inosine levels increased in the EC compartment. Adenosine reached an EC concentration of 40 microM after 15 min of ischemia. Levels of tissue nucleotides and purines normalized on reflow. However, xanthine levels increased transiently (sevenfold). In the EC compartment, adenosine, inosine, and hypoxanthine contents normalized slowly on reflow, whereas the xanthine content increased. The high EC levels of adenosine during ischemia may turn off spontaneous neuronal firing, counteract excitotoxicity, and inhibit ischemic calcium uptake, thereby exerting neuroprotective effects.

Adenosine↗
PubMed1986

Blockade of N-methyl-D-aspartate-sensitive acidic amino acid receptors inhibits ischemia-induced accumulation of purine catabolites in the rat striatum.

The effect of blocking N-methyl-D-aspartate (NMDA)-sensitive excitatory amino acid (EAA) receptors during brain ischemia was studied in order to test a link between EAAs and neuronal energy metabolism. The receptors were blocked unilaterally in the rat striatum before, during and after an ischemic insult. The receptor blocker, D-2-amino-5-phosphonovalerate (D-APV) was administered by dialysis perfusion, which also allowed continuous sampling for analysis of adenosine triphosphate degradation products, i.e. purine catabolites, in control and D-APV-treated striata. Purine catabolites were analysed with reversed-phase liquid chromatography. Hypoxanthine, xanthine, inosine and adenosine increased dramatically in the striatum during ischemia and reached maximum levels during early reperfusion. D-APV reduced the extracellular accumulation of all measured purine catabolites during ischemia/reflow and improved to some extent the recovery of the striatal electroencephalographic activity in the majority of the animals. The results suggest that NMDA receptor blockade attenuates acute changes in energy metabolism during ischemia.

2-Amino-5-phosphonovalerate↗
PubMed1986

An analysis of the effects of excitatory amino acid receptor antagonists on evoked field potentials in the olfactory bulb.

The effects of excitatory amino acid antagonists on extracellular field potentials in the olfactory bulb produced by lateral olfactory tract stimulation were analysed in vivo. The compounds tested D-2-amino-5-phosphonovalerate, L-(+)2-amino-4-phosphonobutyrate, gamma-D-glutamylglycine, L-glutamic acid diethylester and cis-2,3-piperidine dicarboxylic acid, were administered by brain dialysis. Of the compounds tested, only cis-2,3 piperidine-dicarboxylic acid and gamma-D-glutamylglycine were able to suppress the synaptic excitation of granule cells. This pharmacological profile suggests the involvement of non-N-methyl-D-aspartate receptors. However, the suppression was accompanied by a reduction in the amplitude of the presynaptic volley. A second finding was that D-2-amino-5-phosphono-valerate and gamma-D-glutamyl glycine attenuated granule cell mediated inhibition of mitral cells, suggesting the involvement of N-methyl-D-aspartate-sensitive receptors. The possibility that mitral cells and that either centrifugal fibres, or an intrinsic olfactory bulb feedback loop might use an excitatory amino acid as its neurotransmitter is therefore discussed.

2-Amino-5-phosphonovalerate↗
PubMed1977

Serum prolactin and oestradiol levels at different stages of puberty.

Serum prolactin and oestradiol levels were measured in 183 children who were staged for pubertal development. Mean serum prolactin levels are higher in girls than in boys at stage 3 of pubertal development. In girls prolactin levels rise at stage 2, and are higher after menarche; in boys there is no change in prolactin levels. In this study serum oestradiol correlates with prolactin in the girls, but not in the boys.

Adolescent↗
PubMedDate not supplied

Changes in plasma inorganic phosphorus and alkaline phosphatase activity during the adolescent growth spurt.

Longitudinal data on changes in the concentrations of plasma inorganic phosphorus and plasma alkaline phosphatase activity in 23 girls and 44 boys during the adolescent growth spurt are reported together with the height velocities, ages and sexual maturity ratings. The average age at the peak of the growth spurt was 12.5 years in the girls and 14.1 years in the boys with mean annual height gains of 7.0 and 9.7 cm/year respectively. In both sexes, plasma alkaline phosphatase activity rose and fell with the growth velocity during the growth spurt. Plasma inorganic phosphorus rose to reach a peak in the 4 months before the peak of the growth spurt in height; this rise was statisically significant in the boys but not in the girls. Values subsequently fell rapidly towards the normal adult concentrations. Plasma calcium, total protein, and albumin concentrations were also followed during this time, but were not at any point significantly different from normal adult values. These findings provide a guide for the interpretation of plasma biochemistry in adolescent patients.

Adolescent↗
PubMedDate not supplied

Department deployment: integrating quality improvement into day-to-day management.

Despite the time and resources that The George Washington University Medical Center (GWUMC) put into training and forming QI teams, QI staff found that CQI was not being used to carry out critical day-to-day departmental functions. In other words, CQI didn't affect the way staff did "real work." In response, the medical center developed an approach that integrates CQI with departmental leadership, structure, culture, and work routine. With the help of a coach, willing departments at GWUMC choose from a series of 155 activities that they complete at their own pace (eg, setting departmental CQI goals, developing a departmental mission). The department deployment process moves staff through three levels of increasing sophistication and maturity with CQI methods: awareness, understanding, and bonding. It is intended to make quality a habit for staff, or a part of the organizational mind set, rather than an isolated "project." This article will describe how the department deployment approach was developed, its philosophical underpinnings, and its methodology and tools. Then, an example will illustrate how one hospital department--social work and utilization case management--successfully used this approach.

District of Columbia↗