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Biomedical subjects

M A Lewis

Publications and source records attributed to M A Lewis.

At least 217 records · Page 12Linked to original sources
PubMed1985

A comparative study of the resonance Raman spectra of bacterial cytochromes.

Resonance Raman spectra were obtained for two newly isolated bacterial cytochromes, Alcaligenes faecalis (ATCC 8750) c554 and Alcaligenes faecalis c556. Their spectra were compared with those of mammalian cytochrome c and two other bacterial cytochromes, Paracoccus denitrificans c550 and Pseudomonas aeruginosa c551. The positions of the Raman bands indicated that, while Al. c554 and Al. c556 were c-type cytochromes with two thioether linkages, several common features found in their Raman spectra were anomalous. These features suggest that the electronic charge density of the porphyrin macrocycle of Al. c554 and Al. c556 is more asymmetric than that of other bacterial and mammalian c-type cytochromes. The Raman evidence indicates that the electronic properties of the heme are controlled by the protein in these two Alcaligenes cytochromes.

Alcaligenes↗
PubMed1985

Benign metastatic islet cell tumour of the pancreas.

A nine-year-old girl was fortuitously found to have a symptomless metastatic islet cell tumour (apudoma) of the head of the pancreas, the first to be described in a child. The tumour has not changed in size over 3 years and the patient has shown normal growth and development. Initial chemotherapy had no effect.

Adenoma, Islet Cell↗
PubMed1985

The immediate and subsequent outcomes of nursing home care.

To determine the relationship between admission status and subsequent outcomes, 563 patients discharged during 1980 from 24 nursing homes were followed through 1982. Only 28 per cent of patients were discharged to their homes. Reconstructed life histories of 529 discharges for the two-year follow-up revealed only 38 persons (7.2 per cent) were alive and at home; of these, 36 had been initially discharged to their homes. Four hundred and one persons (75.8 per cent) were dead. Mental orientation, urinary continence, functional status, hip fracture, and diagnoses associated with dementia were found to be significant predictors of outcome status after discharge and at follow-up. Social support had only a modest effect on the former outcomes.

Activities of Daily Living↗
PubMed1985

Comparison of memory skills in learning disabled, low-reading, and nondisabled adolescents.

Concerns are raised regarding the samples used in studies of learning disabled children. In this study, subjects were 56 high school students; 10 exhibited perceptual or processing difficulties ("learning disabled"), 15 performed poorly on reading achievement tests ("low readers"), and 31 showed no scholastic problems ("nondisabled"). Scores of the three groups were compared on nine memory tasks involving either auditory or visual input and encompassing a wide variety of content (digits, pictures, related and unrelated words, paired-associates, or sentences). The nondisabled group performed significantly better than the learning disabled group on all but one of the tasks. The low readers' performance was similar to that of the learning disabled group for some tasks, but significantly different on other tasks, most notably on tasks involving visual factors. Implications for research with learning disabled populations are discussed.

Adolescent↗
PubMed1985

Molecular heterogeneity of leukotriene receptors: correlation of smooth muscle contraction and radioligand binding in guinea-pig lung.

The [3H]leukotriene C4 ([3H]LTC4) and [3H]leukotriene D4 ([3H] LTD4) specific binding sites in guinea-pig lung membranes were characterized and correlated with smooth muscle contractile activities of a series of LTC-, D- and E-type analogs. [3H]LTC4 bound to the specific sites with high affinity (dissociation constant Kd = 15 +/- 5 nM), saturable capacity (maximum binding = 68 +/- 15 pmol/mg of membrane protein), stereoselectivity and specificity. The [3H]LTC4 specific binding sites were detected in the membranes isolated from leukotriene sensitive (e.g., lung and heart) or insensitive (e.g., brain and red blood cells) tissues. [3H] LTD4 also bound to specific sites with high affinity (Kd = 0.20 +/- 0.05 nM), low capacity (maximum binding = 1.1 +/- 0.2 pmol/mg of membrane protein) stereoselectivity and specificity. The [3H] LTD4 specific binding sites were detected in the membranes isolated from lung and trachea. [3H]LTC4 specific binding was inhibited by treatment of the membranes with the sulfhydryl alkylating agent N-ethylmaleimide. [3H]LTD4 specific binding was more sensitive to heat treatment and p-hydroxymercuribenzoate than the [3H]LTC4 specific binding. Radioligand competition activities of the LTD- and LTE-type analogs correlated well with the agonist and antagonist smooth muscle contractile activities. In contrast, the radioligand competition activity of the LTC-type analogs did not correlate with smooth muscle contractile activities. These results indicate that the [3H]LTC4 and [3H]LTD4 specific binding sites in guinea-pig lung membranes are chemically and physically distinct. The [3H]LTD4 specific binding sites represent physiologically and pharmacologically important receptors, and the smooth muscle contraction induced by LTD-, and possible LTE-, type analogs are mediated through the LTD4 receptors.

Animals↗
PubMed1984

Identification of specific binding sites for leukotriene C4 in human fetal lung.

Specific leukotriene C4 (LTC4)1 binding sites were identified in membrane preparations from human fetal lung. Specific binding of [3H]-LTC4 represented 95 percent of total binding, reached steady-state within 10 minutes and was rapidly reversible upon addition of excess unlabeled LTC4. Binding assays were performed at 4 degrees C under conditions which prevented metabolism of [3H]-LTC4 (80 mM serine-borate, 10 mM cysteine, 10 mM glycine). Under these conditions, greater than 95 percent of the membrane bound radioactivity, as analyzed by high performance liquid chromatography, co-eluted with the LTC4 standard. Computer-assisted analyses of saturation binding data showed a single class of binding sites with a dissociation constant (Kd) of 26 + 6 nM and a density (Bmax) of 84 + 18 pmol/mg protein. Pharmacological specificity was demonstrated by competition studies in which specific binding of [3H]-LTC4 was displaced by LTC4 and its structural analogs with inhibition constants (Ki) of 10 to 30 nM, whereas LTD4, diastereoisomers of LTD1, LTE4 and the end organ antagonist FPL 55712 were 150 to 700 fold less potent competitors than LTC4. These results provide evidence for specific, reversible, saturable, high affinity binding sites for [3H]-LTC4 in human fetal lung membranes.

Binding Sites↗
PubMed1984

High volume milk feeds for preterm infants.

Fifty nine preterm infants of between 1.0 and 2.0 kg birthweight who were fed 250 ml/kg/day of breast milk or standard formulas gained weight at the intrauterine rate without complications. It is suggested that high volume feeding is a satisfactory alternative to low birthweight formula milks and is more desirable in infants who are to be breast fed.

Animals↗
PubMed1984

Feeling bad: exploring sources of distress among pre-adolescent children.

Previous studies of stress in childhood have used instruments containing items describing events/conditions thought by adults to be stressful for children. In interviews with 5th- and 6th-grade children, we asked them to describe circumstances that would make or had made them feel bad, nervous, or worried. After pretesting this children's list of items, we administered it to 2,480 5th graders. Subjects ranked how bad they would/did feel if each item happened and, also, how often each had occurred. Children also self-rated their mental health status. There were significant associations between children's ratings of mental health and "Feel Bad" scores. Girls rates most items significantly higher (more bad) than boys. While there were some sex and racial differences in ratings, the rank orders of items by different subgroups were highly correlated. Factor analysis revealed three dimensions, containing items related to: 1) anxieties surrounding conflict with parents; 2) self-image and peer-group relationship; and 3) geographic mobility. Only five or six of the 20 items represent discrete events (changing schools); the rest represent chronic role strains (being left out of a group, being pressured to get good grades). The consequences of these strains are yet to be determined.

Analysis of Variance↗