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Biomedical subjects

R C Miller

Publications and source records attributed to R C Miller.

At least 289 records · Page 16Linked to original sources
PubMed1975

Surgical management of infantile ulcerative enteritis.

Infantile transmural ulcerative enteritis is a disorder of early infancy characterized by feeding difficulties, intermittent and progressive diarrhea, cachexia, anemia, abdominal distention, and small-bowel dilation which may progress to intestinal obstruction. The pathologic process, of unknown etiology, involves a transmural enteritis with deep undermining mucosal ulceration, not unlike that seen in Crohn's disease, except that granulomas are usually not present. The early stages of the diseases may be reversible if the bowel is simply placed at rest by use of intravenous nutrition. In the later stages of the illness, there is progressive mechanical and functional intestinal obstruction due to inflammatory constriction of the distal small bowel and lack of effective peristalsis through the inflammed segments. The terminal stages are characterized by marked abdominal distention, complete obstruction, septicemia, and death. It is during the period of abdominal distention due to progressive intestinal obstruction that surgical intervention is of benefit. A cutaneous enterostomy proximal to the involved segments of small intestine serves to decompress the bowel, to minimize bacteremia, and to allow the distal inflamed intestine to heal. Total intravenous nutrition is mandatory for a period of several weeks until there is healing of the distal small bowel and closure of the enterostomy. In all surviving infants, bowel function has returned to normal and there have been no long-term sequelae or recurrences.

Biopsy↗
PubMed1975

Comparison of the beta-adrenoceptors in the myocardium and coronary vasculature of the kitten heart.

The relative potencies of (minus) noradrenaline, (minus)-adrenaline, (plus or minus)-isoprenaline and (plus or minus)-salbutamol have been assessed for their positive inotropic and chronotropic actions on kitten isolated atria. These relative potencies have been compared with those obtained for the relative coronary dilator potencies in two preparations. These were intact hearts perfused by Langendorff's method and isolated perfused coronary arteries from the kitten. The relative molar potencies for inotropic effects were noradrenaline 1: adrenaline1: iso-prenaline 7: salbutamol 0.6. The observed ratios for chronotropic effects were not significantly different from those for inotropic effects. The relative potencies of noradrenaline, adrenaline and isoprenaline as myocardial stimulants were similar to their relative potencies as coronary dilators in the intact heart. Similar relative potencies for noradrenaline and isoprenaline were also found in the isolated coronary artery but adrenaline was only one third as active as noradrenaline on this preparation. In both the intact heart and in the isolated coronary artery salbutamol was about one tenth as active as noradrenaline. It was therefore less active relative to noradrenaline as a coronary dilator than as a myocardial stimulant. In spite of these differences in relative potency ratios for myocardial and coronary dilator effects, similar dissociation constants (Kb values) for practolol against isoprenaline were found in driven atria and in isolated coronary arteries. Myocardial and coronary vascular beta-adrenoceptors thus can both be placed in the general classification of beta1-adrenoceptors.

Adrenergic beta-Antagonists↗
PubMed1975

T4 DNA polymerase (gene 43) is required in vivo for repair of gaps in recombinants.

Experiments with a mutant of T4, tsL97, temperature sensitive for gene 43, showed that T4 DNA polymerase was necessary in vivo to repair gaps in recombinant molecules. CsCl density gradient experiments showed that molecular recombinants were not repaired when the T4tsL97-infected cells were shifted to 42 C after replication and recombination had taken place. Repair was almost complete when the same procedure was followed with the wild-type T4, or when the T4tsL97-infected cells were incubated at the permissive temperature, 36 C. Long-single-strand production was also affected similarly by the T4tsL97 mutation. All the results were consistent with the theory that gaps exist in many recombinant molecules at the recombinant joint, that T4 DNA polymerase is the enzyme that repairs these gaps in vivo, and that covalent repair of the recombinants leads to extensive long-single-strand production.

Centrifugation, Density Gradient↗
PubMed1975

Alkali lability of bacteriophage phi W-14 DNA.

The molecular weight of bacteriophage phi W-14 DNA, determined by velocity sedimentation in neutral sucrose gradients, was 92 +/- 6 X 10(6). The DNA showed marked fragmentation in alkaline sucrose gradients. This fragmentation was not a consequence of preexisting single-strand interruptions in the DNA, since thermal denaturation of DNA yielded intact single strands. The alpha-putrescinylthymine groups in phi W-14 DNA appeared to be labile; some, or parts of some, of these groups were cleaved from the DNA in alkali.

Bacteriophages↗
PubMed1975

The potential of localized heating as a adjunct to radiation therapy.

Experimental studies have shown that (a) tumor cells may be more sensitive to heat than normal cells; (b) hyperthermia inactivates cellular repair mechanisms for radiation damage; and (c) heat may lower the OER for ionizing radiation (anoxic cells are at least as sensitive to hyperthermia as oxygenated cells). Localized hyperthemia produced by localized current fields in the range of 100 kHz-10 MHz by direct contact electrodes offers two major advantages: the eletrode configurations may be manipulated to obtain desired thermal dose distributions, and, since the mode of heating is essentially instantaneous, accurate temperature control can be maintained during treatment.

Adolescent↗