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Biomedical subjects

N Evans

Publications and source records attributed to N Evans.

14 recordsLinked to original sources
PubMed1979

Psychological stress, ego defenses, and cortisol production in children hospitalized for elective surgery.

This study was designed to investigate the relationship between the effectiveness of coping mechanisms and physiological indicators of distress in children faced with the experience of hospitalization and surgery. Twenty-five children between the ages of 7 and 11 were studied in the out-patient department, 2 weeks before surgery, and again during their hospital stay. Effectiveness of defenses and defense style was measured by a clinical interview and by the Rorschach test. Cortisol production rates were measured by the analysis of 24-hour urine collections at home and again in the hospital. Ward adjustment was also rated by a ward questionnaire. The results indicated no relationship between defense effectiveness and cortisol production rates in the out-patient department and an inverse relationship between cortisol production and defense effectiveness under the stress of hospitalization. Defense style was found to correlate with coping under stress. Four different groups of children emerged, suggesting four different types of reaction to the hospital experience.

Adaptation, Psychological↗
PubMed1979

Preliminary experience with controlled-release aminophylline in asthmatic children: salivary levels and peak flow following a single dose.

Preliminary experience of a controlled-release aminophylline tablet in twenty-five asthmatic children has been gained by measuring salivary theophylline levels and peak flow after a single dose (11 mg/kg). The results were compared with an oral theophylline preparation. Mean salivary levels remained elevated at eight hours following ingestion of controlled-release aminophylline, at which time 58% of the children continued to show an improvement in peak flow. Individual children showed a wide variation in salivary levels and respiratory response. It is recommended that theophylline levels should be monitored in the saliva to ensure maximum benefit from the drug.

Adolescent↗
PubMed1978

Adherence of an enteropathogenic strain of Escherichia coli to human intestinal mucosa is mediated by a colicinogenic conjugative plasmid.

The capacity of a human enteropathogenic Escherichia coli (EPEC) strain serotype O26:K60:H11, to adhere to the mucosa of the human fetal small intestine was shown to be plasmid mediated. Adherence was transferred at a high frequency in a long-term conjugal mating experiment to E. coli K-12 and was lost by treatment of the EPEC strain with the curing agent ethidium bromide. Analysis of radioactively labeled DNA from lysates of the EPEC, transconjugant, and cured strains indicated that adherence was correlated with the presence of plasmid DNA species with an approximate average molecular weight of 56 X 10(6). Resistance to the antibiotics spectinomycin, streptomycin, sulfonamides, and tetracycline and production of colicin Ib were all transferred in long-term mating and lost upon curing coordinately with the property of adherence. In conjugal mating experiments of limited duration between E. coli K-12 strains, however, segregation of colicin production and mucosal adherence from multiple drug resistance was observed. Analysis of plasmid DNA of segregant transconjugant strains confirmed the presence in the 56 X 10(6)-dalton plasmid species of two previously unresolved components, pLG101 designating the ColIb plasmid which also carries the determinant for mucosal adherence and pLG102 representing the slightly smaller multiple drug resistance plasmid.

Antigens, Bacterial↗
PubMed1977

Hypoglycemia of infancy and nesidioblastosis. Studies with somatostatin.

We treated a two-month-old infant with servere intractable hypoglycemia and nesidioblastosis with continuous glucose infusions (0.75 g per kilogram per hour) via a central venous catheter. Preprandial glucose levels on this regimen were 37+/-2 mg per deciliter (+/-S.E.M.). Basal serum insulin levels were within normal fasting levels for this age group but inappropriately elevated for the blood glucose levels. The beta cells were exquisitely sensitive to infusions of synthetic cyclic somatostatin, with a dose-dependent rise in blood glucose and concomitant suppression of serum insulin levels. There was only minimal suppression of plasma glucagon levels. Single subcutaneous injections of 50 microng of protamine zinc somatostatin raised preprandial blood glucose levels to 83+/-3 mg per deciliter for four to five days although preprandial hormone levels were unchanged. These findings indicate that hypoglycemia of infancy is a hyperinsulin state with abnormal basal regulation of insulin secretion.

Adenoma, Islet Cell↗
PubMed1977

Intestinal damage in rotavirus and adenovirus gastroenteritis assessed by d-xylose malabsorption.

The absorption of D-xylose infused into the duodenum was assessed in infants with acute gastroenteritis. 1-hour blood-xylose levels were low in 6 patients found to harbour rotavirus in the small intestinal aspirate. Normal levels (greater than 1-26 mmol/l) were obtained in the absence of virus particles in the small intestine in a further 6 patients: in 3 of these adenovirus or rotavirus was recovered from the stools. Three patients with adenovirus in the small intestinal juice and ill with acute gastroenteritis also had low xylose levels. This finding supports earlier epidemiological studies that adenovirus may be a causative agent of acute infantile gastroenteritis. The association between virus in the small intestine and xylose malabsorption may indicate mucosal damage. Formal proff of this is awaited.

Adenoviridae Infections↗
PubMed1976

Macrocyclic intermediates in the biosynthesis of porphyrins.

The hepta-, hexa- and penta-carboxylic porphyrins found in the faeces of rats poisoned with hexachlorobenzene have been separated by high-pressure liquid chromatography and characterized largely by spectroscopie methods. Their structures were confirmed by total synthesis, as part of a programme in which eleven of the fourteen hepta-, hexa- and penta-carboxylic porphyrins derived from uroporphyrin III have now been synthesized as their methyl esters. The four isomeric heptacarboxylic and three of the pentacarboxylic porphyrinogens have been incubated with haemolysates of chicken erythrocytes, and they are all converted into protoporphyrin IX but at different rates. On the basis of this and other evidence we conclude that the decarboxylation of uroporphyrinogen III to coproporphyrinogen III is a stepwise process taking place by a preferred pathway (both in normal and abnormal metabolism); the acetic acid groups are decarboxylated in a sequential clockwise fashion starting with that on the D ring and followed by those on the A, B and C rings. In the poisoned rats the uroporphyrinogen decarboxylase enzyme (or group of enzymes) is probably partially inhibited and the pentacarboxylic porphyrinogen with an acetic acid group on ring C accumulates. The latter is then transformed by a side pathway into dehydroisocoproporphyrinogen and thence into dehydroisocoproporphyrin and its congeners.

Animals↗
PubMed1975

Mucosal adherence of human enteropathogenic Escherichia coli.

An in-vitro assay system has been developed to measure bacterial adhesion to the mucosa of human fetal small intestine. Two strains of Escherichia coli that are proven human enteropathogens (E.P.E.C.) have been shown to adhere in large numbers, compared with control organisms. The attachment mechanism is species specific and is not caused by common fimbriae. Mucosal adhesion may be as important as enterotoxin production or invasiveness in determining the virulence of some strains of human E.P.E.C.

Adhesiveness↗