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Biomedical subjects

J E Barnett

Publications and source records attributed to J E Barnett.

At least 19 recordsLinked to original sources
PubMed2000

Conditions in grey seal pups (Halichoerus grypus) presented for rehabilitation.

A survey was carried out on the condition of 188 live grey seal (Halichoerus grypus) pups presented for rehabilitation from the coasts of south-west England between 1992 and 1998. The survey was carried out to assess the incidence of malnutrition, hyperthermia, respiratory and gastrointestinal conditions, and also the incidence of traumatic, skin, oral and ocular lesions. Malnutrition was a common finding in pups approaching weaning (mid-moult pups) and those at the point of weaning or postweaning (moulted pups) (62 per cent and 82 per cent, respectively). Separation from the dam, believed to be the main cause of malnutrition in grey seals, was encountered frequently in unweaned pups (91 per cent). Thirty-nine per cent of pups presented with a respiratory condition, 38 per cent with hyperthermia and 9 per cent with diarrhoea. Seven per cent and 14 per cent of pups had confirmed respiratory and gastrointestinal parasitic infestations respectively, although these were probably underestimates. Clinically significant traumatic lesions were seen in 41 per cent, oral ulceration in 26 per cent, ocular conditions in 13 per cent, nail bed infections in 13 per cent and oiling in 10 per cent of pups. Umbilical infections and other skin and oral conditions were also encountered. The incidence of these conditions is compared with data from dead grey seals, and clinical conditions in other pinniped species presented for rehabilitation.

Animals↗
PubMed1997

Reorganizing competency programs.

An ambulatory care educational council was formed to validate competency levels, provide staff education programs and determine individual needs. The council's goals and accomplishment are discussed.

Ambulatory Care↗
PubMed1993

Spongiform encephalopathy in a herd of greater kudu (Tragelaphus strepsiceros): epidemiological observations.

A small herd of greater kudu, derived from three individuals, has been maintained at the Zoological Society of London since 1970. Spongiform encephalopathy has been diagnosed in five out of eight of the animals born in this herd since 1987. With the possible exception of the first confirmed case, none of these is thought to have been exposed to feeds containing ruminant-derived protein. The pattern of incidence suggests that greater kudu are very susceptible to the disease and that natural lateral transmission may have occurred among them.

Animals↗
PubMed1991

Self-regulated learning and achievement by middle-school children.

The relationship of self-regulated learning to the achievement test scores of 62 Grade 6 students was studied. Generally, the metacognitive and affective variables correlated significantly with teachers' grades and standardized test scores in mathematics, reading, and science. Planning and self-assessment significantly predicted the six measures of achievement. Step-wise multiple regression analyses using the metacognitive and affective variables largely indicate that students' and teachers' perceptions of scholastic ability and planning appear to be the most salient factors in predicting academic performance. The locus of control dimension had no utility in predicting classroom grades and performance on standardized measures of achievement. The implications of the findings for teaching and learning are discussed.

Achievement↗
PubMed1982

Bacillus stearothermophilus disc assay for detection of inhibitors in milk: collaborative study.

A 2-part (A and B) collaborative study was conducted on a Bacillus stearothermophilus paper disc (12.7 mm) method to detect residual inhibitors in milk. The 18 participating collaborators assayed raw milk samples spiked with a beta-lactam (penicillin G). Of the 18 collaborators, 14 participated in part A and 16 in part B. Part A demonstrated that either Antibiotic Medium No. 4 or PM Indicator Agar is suitable for use in the assay. The lowest concentration detectable, not significantly different from 100% at the alpha = 0.05 level, was 0.008 unit/mL with either medium. Part B demonstrated that the sensitivity of the method is equal to that of the current AOAC method (16.131-16.136). The concentration of beta-lactam detected by 50% of the analysts was 0.003-0.005 unit/mL in this study, compared with 0.005 unit/mL reported in an earlier collaborative study on the current AOAC method. No false positive results were reported in part A or part B. All samples found positive by the confirmatory test in part B were correctly identified as a beta-lactam with commercial Penase discs. The lowest concentration detectable by the method, not significantly different from 100% at the alpha = 0.05 level, was 0.008 unit/mL. The method was adopted official first action.

Animals↗
PubMed1978

Sub-unit assembly in the biosynthesis of neomycin. The synthesis of 5-O-beta-D-ribofuranosyl and 4-O-beta-D-ribofuranosyl-2,6-dideoxystreptamines.

The preparation of the deoxy- analogues of two pseudodisaccharide fragments of neomycin, 5-O-beta-D-ribofuranosyl-2,6-dideoxy-streptamine and 6-deoxyneamine is described. When added to the growth medium of a deoxystreptamine-idiotroph of Streptomyces rimosus forma paromomycinus only the latter was incorporated into antibiotic, suggesting an obligatory order for the assembly of sub-units. 4-O-beta-D-Ribofuranosyl-2,6-dideoxystreptamine was also prepared. When added to the growth medium of a deoxystreptamine-idiotroph of Streptomyces fradiae it was converted into the 6-deoxyneomycins, apparently after hydrolysis to 2,6-dideoxystreptamine. The structure of the protected derivatives of the ribofuranosyl 2,6-dideoxystreptamines, potentially useful intermediates for the synthesis of novel antibiotics, was shown by using 15C NMR spectroscopy.

Hexosamines↗
PubMed1976

The role of the pseudo-disaccharide neamine as an intermediate in the biosynthesis of neomycin.

By using wild-type and deoxystreptamine-negative mutants of Streptomyces fradiae grown in media containing [6(-3)H]glucose or [U-14C]glucose, and by subsequent hydrolysis of the labelled neomycin produced, neamines labelled with 3H in both rings I and II, but with 14C in ring I only, were prepared. A mixture of these two forms of neamine was converted by deoxystreptamine-negative Streptomyces rimosus forma paromomycinus into neomycin (not paromomycin) with a 30% yield. The3H: 14C ratio in this neomycin was the same as the measured in neamine produced by hydrolysis of the neomycin, and in unused neamine reisolated from the incubation medium. The 3H:14C ratio in the neomycin was not affected by the presence of unlabelled deoxystreptamine during the incubation. The radioactivity in the neomycin was associated with rings I and II only. It is concluded that the added neamine is incorporated into antibiotic intact, without initial hydrolysis, and that the probable first step in the subunit assembly of neomycin is the formation of neamine.

Disaccharides↗
PubMed1976

Colorectal carcinoma: a prospect clinicopathological study.

The clinical and pathological findings in 200 consecutive cases of colorectal carcinoma treated by surgical resection have been recorded and subjected to computer analysis. This is the initial report from a long-term prospective survey of this disease. The two most frequent presenting symptoms were altered bowel habit (51.5%) and bleeding (49.5%). Symptoms due to anaemia occurred in 16% of cases and acute obstruction in 13.5% of cases. The value of the various investigations in establishing the diagnosis is discusses. At the time of resection the disease had already reached an advanced stage in a majority of the patients. In 26% of cases it was known that complete resection of tumour tissue had not been achieved. A direct relationship between stage of spread and histological grade of malignancy was noted. The incidence of advanced stage, high histological grade and mucinous tumours was greatest in the right side of the colon. A study of early carcinomas has confirmed that many have arisen from benign epithelial neoplastic polyps. The significance of these observations is discussed.

Adenocarcinoma, Mucinous↗
PubMed1976

Closure of colostomy.

A retrospective review of 110 patients who had their colostomies closed during the period from 1963 to 1973 has been undertaken. Their average age was 64 years. Diverticular disease and colorectal cancer had been the most frequent indications for the colostomy. Wound infection occurred in 36.4% and faecal fistula in 7.3%. These complications occurred less frequently in patients who had antibiotic bowel preparation. The overall mortality rate was 4.5%. Measures to reduce the morbidity and mortality are discussed.

Adult↗
PubMed1975

Evidence for two asymmetric conformational states in the human erythrocyte sugar-transport system.

6-O-methyl-, 6-O-propyl-, 6-O-pentyl- and 6-O-benzyl-D-galactose, and 6-O-methyl-, 6-O-propyl- and 6-O-pentyl-D-glucose inhibit the glucose-transport system of the human erythrocyte when added to the external medium. Penetration of 6-O-methyl-D-galactose is inhibited by D-glucose, suggesting that it is transported by the glucose-transport system, but the longer-chain 6-O-alkyl-D-galactoses penetrate by a slower D-glucose-insensitive route at rates proportional to their olive oil/water partition coefficients. 6-O-n-Propyl-D-glucose and 6-O-n-propyl-D-galactose do not significantly inhibit L-sorbose entry or D-glucose exit when present only on the inside of the cells whereas propyl-beta-D-glucopyranoside, which also penetrates the membrane slowly by a glucose-insensitive route, only inhibits L-sorbose entry or D-glucose exit when present inside the cells, and not when on the outside. The 6-O-alkyl-D-galactoses, like the other nontransported C-4 and C-6 derivatives, maltose and 4,6-O-ethylidene-D-glucose, protect against fluorodinitrobenzene inactivation, whereas propyl beta-D-glucopyranoside stimulates the inactivation. Of the transported sugars tested, those modified at C-1, C-2 and C-3 enhance fluorodinitrobenzene inactivation, where those modified at C-4 and C-6 do not, but are inert or protect against inactivation. An asymmetric mechanism is proposed with two conformational states in which the sugar binds to the transport system so that C-4 and C-6 are in contact with the solvent on the outside and C-1 is in contact with the solvent on the inside of the cell. It is suggested that fluorodinitrobenzene reacts with the form of the transport system that binds sugars at the inner side of the membrane. An Appendix describes the theoretical basis of the experimental methods used for the determination of kinetic constants for non-permeating inhibitors.

Binding Sites↗
PubMed1974

The reaction of N-acetylneuraminate lyase with chloropyruvate.

Chloropyruvate, like bromopyruvate, rapidly inactivates N-acetylneuraminate lyase at pH7.2. At 5 degrees C, 0.5mm-chloropyruvate reacted with the enzyme about ten times as fast as bromopyruvate. In contrast, at pH6.0 and 9 degrees C, chloropyruvate reacted with N-acetylcysteine seven times more slowly than bromopyruvate. A brief (2min) incubation of the enzyme with 1.0mm-chloro[(14)C]pyruvate gave an inactive enzyme in which 4.5 cysteine residues were alkylated per molecule of enzyme. This corresponded to the number of [(14)C]pyruvate residues (3.7) bound to the enzyme by borohydride reduction of the [(14)C]-pyruvate complex, and confirmed the previous suggestion that there is one ;essential' cysteine residue per active site. It is suggested that, for this enzyme, chloropyruvate can be selectively used to alkylate the active-site residues, whereas bromopyruvate cannot. The apparent molecular weight of the enzyme prepared by two slightly different methods was approx. 100000 or 250000. The latter value has been used to calculate the number of pyruvate residues bound to the enzyme.

Binding Sites↗
PubMed1973

Partial reactions of D-glucose 6-phosphate-1L-myoinositiol 1-phosphate cyclase.

After removal of tightly bound NAD(+) by using charcoal, a preparation of d-glucose 6-phosphate-1 l-myoinositol 1-phosphate cyclase catalysed the reduction of 5-keto-d-glucitol 6-phosphate and 5-keto-d-glucose 6-phosphate by [4-(3)H]NADH to give [5-(3)H]-glucitol 6-phosphate and [5-(3)H]glucose 6-phosphate respectively. The position of the tritium atom in the latter was shown by degradation. Both enzyme-catalysed reductions were strongly inhibited by 2-deoxy-d-glucose 6-phosphate, a powerful competitive inhibitor of inositol cyclase. The charcoal-treated enzyme preparation also converted 5-keto-d-glucose 6-phosphate into [(3)H]myoinositol 1-phosphate in the presence of [4-(3)H]NADH, but less effectively. These partial reactions of inositol cyclase are interpreted as providing strong evidence for the formation of 5-keto-d-glucose 6-phosphate as an enzyme-bound intermediate in the conversion of d-glucose 6-phosphate into 1 l-myoinositol 1-phosphate. The enzyme was partially inactivated by NaBH(4) in the presence of NAD(+). Glucose 6-phosphate did not increase the inactivation, and there was no inactivation in the absence of NAD(+). There was no evidence for Schiff base formation during the cyclization. d-Glucitol 6-phosphate (l-sorbitol 1-phosphate) was a good inhibitor of the overall reaction. It did not inactivate the enzyme. The apparent molecular weight of inositol cyclase as determined by Sephadex chromatography was 2.15x10(5).

Animals↗
PubMed1973

Structural requirements for binding to the sugar-transport system of the human erythrocyte.

The structural requirements for binding to the glucose/sorbose-transport system in the human erythrocyte were explored by measuring the inhibition constants, K(i), for specifically substituted analogues of d-glucose when l-sorbose was the penetrating sugar. Derivatives in which a hydroxyl group in the d-gluco configuration was inverted, or replaced by a hydrogen atom, at C-1, C-2, C-3, C-4 or C-6 of the d-glucose molecule, all bound to the carrier, confirming that no single hydroxyl group is essential for binding to the carrier. The binding and transport of 1-deoxy-d-glucose confirmed that the sugars bind in the pyranose form. The relative inhibition constants of d-glucose and its deoxy, epimeric and fluorinated analogues are consistent with the combination of beta-d-glucopyranose with the carrier by hydrogen bonds at C-1, C-3, probably C-4, and possibly C-6 of the sugar. Both polar and non-polar substituents at C-6 enhance the affinity of d-glucose derivatives relative to d-xylose, and d-galactose derivatives relative to l-arabinose, and it is suggested that the carrier region around C-6 of the sugar may contain both hydrophobic and polar binding groups. The spatial requirements at C-1, C-2, C-3, C-4 and C-6 were explored by comparing the relative binding of d-glucose and its halogeno and O-alkyl substituents. The carrier protein closely approaches the sugar except at C-3 in the d-gluco configuration, C-4 and C-6. d-Glucal was a good inhibitor, showing that a strict chair form is not essential for binding. 3-O-(2',3'-Epoxypropyl)-d-glucose, a potential substrate-directed alkylating agent, bound to the carrier, but did not inactivate it.

Binding Sites↗