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Biomedical subjects

M Daniels

Publications and source records attributed to M Daniels.

At least 127 records · Page 7Linked to original sources
PubMed1980

Size heterogeneity of rat pituitary prolactin.

The occurrence of multiple forms of rat prolactin with different molecular weights (size heterogeneity) was studied with anterior pituitary extracts, purified rat prolactin and 125I-labelled rat prolactin. In each case, three main forms of the hormone were detected by gel filtration on Sephadex G-100: a major one (80--90%) corresponding to monomeric prolactin (mol.wt. 22000--25000), a peak (8--20%) that could be a dimer (mol.wt. 45000--50000) and a small quantity (1--5%) of a component of much greater molecular weight. On freezing and thawing of 125I-labelled rat prolactin, there was little interconversion of monomer and 'dimer' peaks, but both were converted substantially to very high-molecular-weight material. All three peaks of 125I-labelled rat prolactin could be precipitated by anti-(rat prolactin) serum and all three gave similar patterns of radioactive peptides after digestion with chymotrypsin followed by high-voltage paper electrophoresis. On sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the monomer peak of 125I-labelled prolactin migrated as a single component of mol.wt. 22000, the very high-molecular-weight peak largely dissociated to a component running in the same position as the monomer, and the 'dimer' peak migrated partly as a component of mol.wt. 45000 and partly as a component migrating with monomeric prolactin. No treatment was found that could dissociate the 'dimer' peak completely to monomeric prolactin.

Animals↗
PubMed1979

The physician assistant in rural primary care practices: physician assistant activities and physician supervision at satellite and non-satellite practice sites.

Nineteen practice sites in Iowa were studied to determine the differences in the types of physician (MD) supervision the physician assistant (PA) received at work at satellite (separate from the major practice site of the supervising MD) and non-satellite practice sites. The MDs supervised PA functions in 12.9 per cent of the patients seen by the PAs at non-satellite and 15.9 per cent of patients they saw at satellite practice sites. All patients with presenting manifestations that suggested life-threatening conditions were seen by MDs at satellite and non-satellite sites. The MD spent 9.2 minutes per patient at satellite clinics, compared to 4.4 minutes per patient at non-satellite clinics. PAs working at satellite sites appeared to receive as much supervision as PAs working at non-satellite clinics.

Clinical Competence↗
PubMed1978

Experimental group B streptococcal infection in the rhesus monkey. I. Disease production in the neonate.

Group B streptococci (GBS) are responsible for serious infections of newborn infants. An experimental model for GBS infection was developed in the newborn rhesus monkey in order to obtain more information concerning the pathogenesis of such infections. A series of 29 newborn monkeys were inoculated with either type Ic or type III GBS or sterile broth. Fatal neonatal meningitis without associated pneumonia was produced consistently following intracerebral inoculation with either type Ic or type III; intracerebral inoculation with sterile broth produced no apparent disease. Variable disease production followed intravenous or intra-amniotic GBS inoculation, and clinical manifestations ranged from no apparent disease to fatal meningitis and pneumonia. This monkey model may be useful for further investigation of treatment and prevention of neonatal GBS infection.

Animals↗
PubMed1978

Preparation of internally labelled rat pituitary somatotropin (growth hormone).

Rat somatotropin (growth hormone) was labelled biosynthetically by incubating anterior pituitary lobes with radioactive amino acids for 24 h in a simple buffered salts medium containing glucose. The labelled hormone was isolated by preparative polyacrylamide-gel electrophoresis or by chromatography on Sephadex G-100 and then DEAE-cellulose. The labelled material was pure by several criteria and cross-reacted immunologically with unlabelled rat somatotropin. When a mixture of 14C-labelled amino acids was used for labelling the protein, label could be introduced into these same amino acids of somatotropin, though relative specific radioactivities varied considerably. Somatotropin labelled by the procedures described in the present paper was suitable for structural studies and could be used for a variety of other biochemical experiments.

Amino Acids↗
PubMed1977

Variation among physicians in use of laboratory tests. II. Relation to clinical productivity and outcomes of care.

Previous studies from this institution have shown extreme variation in laboratory and x-ray use among comparably trained physicians caring for similar patients. In addition, essentially no correlation (r = --.13) existed between a physician's lab use profile and subjective estimates of clinical competence. This study compares variations in lab use with both clinical productivity and outcome of care. Costs of lab tests of 149 long-term ambulatory hypertensive patients cared for by 13 faculty internists during one year were computed. Variation in mean annual lab costs per patient among the internists was great (range, $8-$161; standard deviation, $42). Outcomes of care were estimated using hypertension as an indicator condition. The physicians were scored according to percentage of hypertensive patients with systolic and diastolic pressures below specified levels. Correlation between lab use profiles and outcomes was negative (r = --.42) but not significant. Clinical productivity was estimated by two methods: adjusted panel size and subjective estimates of efficiency by the clinic administrator. Correlations between lab use behavior and each estimate of productivity were negligible (.13 and --.16 respectively). These data indicate that in this setting there is no positive association between a physician's frequency of lab use and either clinical productivity or outcomes of care.

Adolescent↗
PubMed1976

Antenatal sex determination in Macaca arctoides.

Transabdominal amniocentesis was performed on 11 Macaca arctoides, between the 10th and 20th weeks of gestation, for the purpose of antenatal sex determination. The technique employing Y-chromatin fluorescence was unsuccessful in predicting sex, but the sexes were differentiated with complete accuracy by examining amniotic cells stained by a modified Papanicolaou technique. Of the cells from male fetuses, fewer than 10% contained X-chromatin (Barr bodies); of those from females, more than 45% contained X-chromatin.

Amniocentesis↗
PubMed1972

Tautomerism of uracil and thymine in aqueous solution: spectroscopic evidence.

Excitation spectra for triplet state formation and fluorescence emission from uracil and thymine in neutral aqueous solution at room temperature are anomalous when compared to the absorption spectra of uracil and thymine. The experimental data are critically examined with respect to three molecular models; Model 1, which is characterized by increased intersystem crossing from higher vibrational levels of S(1); Model 2, in which fluorescence is attributed to a (pi,pi(*)) state, whereas intersystem crossing occurs from an (npi(*)) state; and Model 3, in which fluorescence is attributed to a tautomer I, while triplet yields originate from tautomer II. Reasons are presented for discarding Models 1 and 2, and it is demonstrated that the observed excitation spectra complement each other with respect to the absorption spectrum, such that the quantum yields of triplet formation and fluorescence emission become independent of exciting wavelength. It is suggested that the fluorescing tautomer I has the N(3)-C(4) enol structure, while the triplet-forming tautomer II is most likely the predominant diketo form.

Isomerism↗
PubMed1971

Fluorescence of the purine and pyrimidine bases of the nucleic acids in neutral aqueous solution at 300 degrees K.

Fluorescence of adenine, guanine, cytosine, and uracil at room temperature in neutral aqueous solution has been detected by means of a digital signal accumulation technique. Corrected emission and excitation spectra are presented and compared with low-temperature data. The quantum yields are, respectively, 2.6 x 10(-4), 3.0 x 10(-4), 0.8 x 10(-4), and 0.5 x 10(-4) when the bases are excited at their low-energy absorption maxima.

Adenine↗