Biomedical subjects

M A Hayes

Publications and source records attributed to M A Hayes.

94 records · Page 6Linked to original sources

PubMedDate not supplied

Traction at home for infants with developmental dysplasia of the hip.

Early treatment of developmental dysplasia of the hip in infants is essential for optimal development of the hip joint. Orthopaedists commonly use a period of preliminary traction before hip reduction to stretch the soft tissues and reduce the risk of avascular necrosis. A program developed at the University of Michigan Medical Center allows the infant to receive traction at home instead of the traditional admission to the hospital. This program has been found to be clinically effective as well as cost effective, and less of an inconvenience to the infant and family than the traditional admission. Intensive involvement by the clinical nurse specialist in teaching and follow-up of each patient is essential for success.

Hip Dislocation, Congenital↗

PubMedDate not supplied

Influences of dietary deoxycholic acid on progression of hepatocellular neoplasms and expression of glutathione S-transferases in rats.

Serial magnetic resonance imaging (MRI) was used to evaluate the influences of dietary deoxycholic acid (DCA) on the rate of progression of chemically induced hepatocellular neoplasms in rats. Male Fischer-344 rats with established persistent hepatocellular nodules generated by the Solt-Farber protocol were exposed to dietary DCA (0.3%) between 6 and 12 mo of age. Growth of nodules and carcinomas in vivo was measured by morphometric quantification of tumor images obtained every 6 wk. The final stages of neoplastic progression were determined by terminal histopathological examination and by expression and functional evaluation of glutathione S-transferase (GST) isoenzyme phenotypes. Dietary DCA increased the number of hepatocellular neoplasms per rat, accelerated the rate of growth of persistent nodules, and increased the histological progression of liver tumors. Expression of immunoreactive GST subunits Yf, Ya, and Yb1 was induced in early persistent nodules, a pattern that was maintained throughout the study in both basal diet and DCA-fed groups. However, 5% of early nodules and about 75% of advanced neoplasms were partially or completely deficient in GST Yb2 expression in both groups. DCA did not alter the cytosolic activity for the GST substrates 1-chloro-2,4-dinitrobenzene (CDNB) or trans-4-phenyl-3-buten-2-one (tPBO) in tumors or surrounding liver. However, in both groups, CDNB activity was increased in the tumors relative to the surrounding nonneoplastic tissue, whereas activity for tPBO, a substrate more specific for the Yb2 subunit, was reduced in the tumors. All advanced neoplasms were similarly more resistant than surrounding liver to DNA-binding metabolites of aflatoxin B1 or benzo[a]pyrene. These data demonstrate that DCA can increase the progression of established hepatocellular nodules to larger, more advanced neoplasms but does not preferentially select for a specific GST phenotype. Preferential loss of constitutively expressed GST Yb2 in both basal diet and DCA-fed groups may be an important aspect of progression from resistant nodules to advanced cancers in this model. These studies also demonstrate that serial MRI is a useful tool for measuring the rates of enlargement and patterns of growth in established hepatocellular neoplasms.

Animals↗

PubMedDate not supplied

Synergistic effects of T-2 toxin and a low protein diet on erythropoiesis in mice.

Young male Swiss mice fed on a semipurified diet containing 8% protein and 10 ppm of T-2 toxin developed erythroid hypoplasia within 2 weeks. Red blood cell counts declined to 36% of control values by 6 weeks but had risen to 45% of control values by 8 weeks. Between 4 and 8 weeks, erythropoietic tissues regenerated and reticulocyte counts became greatly elevated. The toxin-free semipurified diet was adequate for normal growth and did not cause anemia in control mice fed either ad lib, or at a restricted rate. Anemia did not occur in mice fed the 10-ppm level to T-2 toxin in either a semipurified diet containing 16% protein, or in a balanced natural-ingredient mouse diet. These observations demonstrated that the inhibitory effect of T-2 toxin in erythropoiesis in mice was transient, and depended on the nutritional composition of the diet.

Animals↗

PubMedDate not supplied

A method for accurate measurement of cutaneous irritancy of trichothecenes.

Conventional skin irritation bioassays for trichothecenes are semiquantitative because test animals vary in sensitivity, and the intensity of cutaneous inflammation is poorly correlated with dose. A quantitative bioassay was therefore devised for toxicological studies on the irritancy of trichothecenes. A graded series of six standard solutions of T-2 toxin (10-60 micrograms/mL) in 2 microL volumes was applied to the shaved skin of young female Wistar rats. Each test sample was applied at least twice to each of five rats. After 48 hours, reactions were rated in units of equivalent concentrations of T-2 toxin, so that measurements were independent of the intensity of inflammatory reaction. Mean concentrations of replicate measurements of test solutions of T-2 toxin between 10 and 60 micrograms/mL were precise (SEM less than 1.6 micrograms/mL) and accurate (within 13% of actual concentrations).

Animals↗