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Biomedical subjects

M Ryan

Publications and source records attributed to M Ryan.

At least 361 records · Page 20Linked to original sources
PubMed1979

The use of stem cell assays to monitor the proliferative potential of bone marrow cells.

A number of assays exist for hematopoietic stem cells in both humans and mice, but the appropriate stem cell assay for the repopulating potential of human marrow is not clear. Two murine models suggest that these assays may not always predict marrow proliferative potential. In vivo diffusion chamber culture growth of CD1 marrow depleted of pluripotent stem cells (CFU-S) by exposure to mouse-brain antisera plus complement was equivalent to or greater than that of normal serum treated control marrow. Furthermore, CF1 mice repeatedly injected with endotoxin had markedly stimulated granulopoiesis with increases in the number of marrow CFU-S and the % in S phase but no changes in the number or proliferative status of marrow CFU-C. However, inbred BDF1 mice chronically injected with endotoxin although also showing striking increases in granulopoiesis had no significant alteration in their marrow CFU-S or CFU-C number or cell cycle status relative to saline injected controls. Both models present examples where conventional stem cell assays do not provide insight into marrow cell production and suggest that in vitro clonal assays of human marrow cells may not always predict for the potential of marrow to repopulate a human transplant recipient.

Animals↗
PubMed1979

Psychologic adjustment of siblings of children with chronic illness.

Although numerous references are made to the stressful, deleterious effects of chronic or terminal illnesses and handicaps on the siblings of pediatric patients, very few studies have been conducted using comparison groups. The present study compared the adjustment of 3- to 13-year-old siblings of pediatric hematology (N = 62), cardiology (N = 57), and plastic surgery patients (N = 37) with healthy siblings (N = 46). The adjustment measure was an objective, paper-and-pencil measure of children's emotional and behavioral problems, the Louisville Behavior Checklist. On analyses of covariance, the patient groups were more likely to show symptoms of irritability and social withdrawal, and the differences between illness groups approached significance on measures of fear and inhibition. Among the younger children, ages 3 to 6, there were significant group differences, with the siblings of patients undergoing plastic surgery showing the highest level of general psychopathology. Among children ages 7 to 13, male siblings of patients with blood disorders were more likely to show signs of emotional disturbance than female siblings. No group differences were noted on measures of aggression or learning problems. Significant interactions between sex and age relationship to the child were noted on scales of social withdrawal, inhibition, immaturity, and irritability.

Adolescent↗
PubMed1978

Lawnmower injuries.

Six cases of lawnmower injury are reported. The management of these injuries is discussed. The incidence of morbidity and mortality are emphasized in an appeal for education in the safe handling of these common domestic appliances.

Accidents, Home↗
PubMed1978

Inhibition of normal murine hematopoiesis by leukemic cells.

Inhibition of normal mouse hemopoietic stem cells by leukemic cells (C1498) was observed with use of in vitro agar and in vivo diffusion-chamber cultures. The C1498 cells were unresponsive to colony-stimulating activity, and, above a critical threshold, they inhibited normal granulocyte progenitors in agar culture. C1498 cells added to normal marrow in diffusion chambers progressively reduced granulocyte progenitors. The larger, more rapidly growing, C1498 cells showed the most inhibitory effect. Transmembrane culture of C1498 cells adjacent to normal marrow in double diffusion chambers for five to 14 days led to reduction of recovery of granulocyte progenitors (72 +/- 7 per cent of control) and pluripotent stem cells (45 +/- 7 per cent of control) from the normal marrow chambers. These results indicate that leukemic mouse cells inhibit normal mouse-marrow stem cells by releasing a diffusible substance, and this inhibition occurs primarily at the level of the pluripotent stem cell.

Animals↗
PubMed1978

Hyperkinesis and diet: a double-blind crossover trial with a tartrazine challenge.

A pilot study was conducted on 22 children (19 boys and three girls) aged between four and eight years, who were selected as hyperactive on the basis of developmental history and clinical judgement. Conners' parent-teacher ratings, objective tests of attention, standard perceptualmotor tests and subtests from the Wechsler Intelligence Scale for Children (WISC), were used as response variables. The children were tested before and after four weeks on the elimination diet, after a tartrazine and placebo challenge, and, finally, after a four-week washout period on the diet. Results showed a statistically significant improvement in the mothers' ratings of the children's behaviour after the first four weeks of the diet. The improvement was maintained in a combined analysis of the initial four-week diet period and four-week washout period. This result was not substantiated by the statistical analysis of the results from objective tests. The rating scales and objective tests for the full sample did not show a statistically significant deterioration in the children's behaviour when they were challenged under double-blind test conditions with the Yellow Dye No. 5, tartrazine, and the tests were conducted the day after a two-week challenge period. A comparison of mother ratings of behaviour during challenge and placebo double-blind trial and in the 24 hours preceding tests, in a subgroup of the children who, while on the diet, showed a 25% reduction of symptoms on the Conner's rating scale, indicated a significant challenge effect (P less than 0.025), with mothers reporting more symptoms during the challenge period. Dietary infringements with suspected trigger substances occurred throughout the trial.

Azo Compounds↗
PubMed1976

Transiently reduced activity of carbamyl phosphate synthetase and ornithine transcarbamylase in liver of children with Reye's syndrome.

Since Reye's syndrome is associated with hyperammonemia, we measured the urea-cycle enzymes in hepatic tissue of 13 patients. Expressed as nanomoles of citrulline per milligram of hepatic protein per minute, mean activity of carbamyl phosphate synthetase (6.27 +/- 2.45 S.D.) and ornithine transcarbamylase (136.19 +/- 41.83) in Reye's syndrome was reduced significantly (P less than 0.005) when compared with that of 25 "normal" controls (11.54 +/- 4.24 and 307.49 +/- 94.15, respectively). Activity was maximally reduced during the first days of clinical symptoms; it returned toward normal during the following week regardless of whether the disease ended in death or recovery. The activity of the two enzymes was normal in patients with salicylate intoxication or heritable argininosuccinic acid synthetase deficiency. The apparent Km of hepatic ornithine transcarbamylase for ornithine was in the normal range in patients with Reye's syndrome (mean 0.24 mM). These observations indicate that Reye's syndrome is associated with acquired and transient dysfunction of hepatic mitochondrial urea-cycle enzymes.

Age Factors↗
PubMed1976

Glucose-6-phosphate dehydrogenase in lichen planus skin.

The apparent Michaelis constant (Km) for glucose-6-phosphate of the enzyme glucose-6-phosphate dehydrogenase has been measured in extracts prepared from biopsies of normal human skin and from both affected and apparently normal skin of patients with lichen planus. No differences of Km were found and starch gel electrophoresis of extracts from lichen planus lesions and normal controls showed similar patterns when stained for glucose-6-phosphate dehydrogenase activity. These results do not support the view that lichen planus is an inborn error of metabolism in which the structure of glucose-6-phosphate dehydrogenase of skin is affected.

Electrophoresis, Starch Gel↗