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Biomedical subjects

R E Miller

Publications and source records attributed to R E Miller.

At least 217 records · Page 12Linked to original sources
PubMed1981

Glucose and cyclic AMP as stimulators of somatostatin and insulin secretion from the isolated, perfused rat pancreas: a quantitative study.

The secretory responses of beta and delta cells were compared in the isolated, perfused, rat pancreas. Insulin release was stimulated 50-fold and somatostatin (SRIF) secretion twofold when the glucose concentration was increased from 100 mg/dl to 300 mg/dl. When islet cyclic AMP (cAMP) was raised by 3-isobutyl-1-methylxanthine (IBMX), the secretion of SRIF was stimulated in a glucose-dependent manner (300 mg/dl greater than 100 mg/dl greater than 25 mg/dl). As expected, insulin release was also potentiated in a similar fashion. A difference in the glucose dependency of the cAMP effect was seen at 25 mg/dl glucose, where 0.25 mM IBMX enhanced the release of SRIF but not that of insulin. In contrast, at 300 mg/dl glucose, IBMX caused a greater potentiation of insulin release than of SRIF release. The release of insulin, when expressed in absolute terms, was stimulated more markedly than that of SRIF under most conditions tested. However, the expression of total hormone released during 30 min of stimulation as a percentage of tissue hormone content allowed a different interpretation of the results. For example, 2.1% and 1.8% of tissue insulin and SRIF contents, respectively, was released during exposure to 300 mg/dl glucose. Surprisingly, under basal conditions (100 mg/dl glucose), 1.0% of total SRIF content was released during 30 min compared with the release of only 0.04% of insulin.

1-Methyl-3-isobutylxanthine↗
PubMed1981

Effect of D-Val1, D-Trp8-somatostatin on the motility of the stomach, duodenum and jejunum.

D-Val1, D-Trp8-somatostatin was given to seven volunteers to relax the gastrointestinal tract. Doses of drug ranging from 1-250 mcg. were given intravenously, single blind, as one bolus. The seven subjects had a total of 23 studies. The stomach never became hypotonic in any subject. The onset of drug effect on the duodenum and jejunum of moderate hypotonicity after 10-100 mcg. was 4.8 minutes and at 150-250 mcg., was 10.1 minutes. Onset of atonicity after 10-100 mcg. wa 5.7 minutes and at 150-2509 mcg., was 13.0 minutes. Duration of moderate hypotonicity after 10-100 mcg. was 20.9 minutes and at 150-250 mcg., was 22.4 minutes. Duration of atonicity at 10-100 mcg. was 11.5 minutes and at 50-250 mcg., was 14.1 minutes. Preliminary results suggest that the onset and duration of effect, relative to dose, were so variable that the drug appeared to be an unsatisfactory hypotonic agent for upper gastrointestinal radiography.

Adult↗
PubMed1980

Dibutyryl cyclic AMP decreases glutamine synthetase in cultured 3T3-L1 adipocytes.

Glutamine synthetase specific activity increases greater than 100-fold during the insulin-mediated differentiation of confluent 3T3-L1 cells into adipocytes. Incubation of the adipocytes for 22 h with 0.5 mM dibutyryl cyclic AMP plus 0.5 mM theophylline, 0.2 mM 8-bromo-cyclic AMP, 10 micro M epinephrine, or 1 microgram of alpha 1-24 adrenocorticotropic hormone/ml decreased glutamine synthetase by greater than 60%. During the same incubation period, there was no effect of these compounds on protein or on the specific activities of glucose-6-P dehydrogenase or hexokinase. In the presence of 0.5 mM theophylline, the dibutyryl cyclic AMP-mediated decrease in glutamine synthetase activity was half-maximal at 50 micro M dibutyryl cyclic AMP. Furthermore, between 10 micro M and 5 mM dibutyryl cyclic AMP, the dibutyryl cyclic AMP-mediated decrease in glutamine synthetase was similar in the absence or presence of 1 microgram of insulin/ml. Immunotitration of glutamine synthetase activity from 3T3 adipocytes indicates that the dibutyryl cyclic AMP-mediated decrease in the activity is due to a decrease in the cellular content of glutamine synthetase molecules. We studied the effects of dibutyryl cyclic AMP on the synthesis and degradation of glutamine synthetase. Synthesis rate was estimated from the incorporation of L-[35S]methionine into glutamine synthetase during a 60-min incubation period. Degradation rate was estimated from the first order disappearance of radioactivity from glutamine synthetase in 3T3 adipocytes previously incubated with L-[35S]methionine. Glutamine synthetase was isolated by immunoprecipitation followed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Incubation of 3T3 adipocytes with dibutyrl cyclic AMP resulted in a rapid decline in the apparent synthesis rate of glutamine synthetase. In addition, dibutyryl cyclic AMP treatment increased the initial rate of glutamine synthetase degradation. The half-life of glutamine synthetase was 24.5 h in control cultures and 16 h in dibutyryl cyclic AMP-treated cultures. In contrast, dibutyryl cyclic AMP had little effect on the synthesis or degradation of soluble protein. Our data indicate that the dibutyryl cyclic AMP-mediated decrease in 3T3 adipocyte glutamine synthetase activity results from a decrease in the synthesis rate and an increase in the initial degradation rate of the enzyme.

Adipose Tissue↗
PubMed1980

Pharmacology of verapamil. II. Impairment of glucose tolerance by verapamil in the conscious dog.

The effect of verapamil on glucose tolerance and insulin release in conscious, healthy dogs was studied at plasma drug concentrations which produce therapeutic cardiovascular effects. Plasma glucose and immunoreactive insulin were measured serially in each animal for 90 min after an intravenous glucose challenge (400 mg/kg), both during a control study and again during administration of verapamil. The drug was given by infusion protocols to produce plasma concentrations at low (84 +/- 9 ng/ml), intermediate (161 +/- 30 ng/ml), and high (367 +/- 51 ng/ml) ranges. Insulin release was impaired and glucose levels elevated at both the intermediate and the high verapamil concentrations, and to a similar degree. The reduction in insulin release and subsequent increase in plasma glucose is a pharmacologic effect of verapamil which occurs at drug concentrations likely to be achieved during clinical use.

Animals↗
PubMed1980

Detection of pneumoperitoneum: optimum body position and respiratory phase.

Experimental studies of pneumoperitoneum in left lateral decubitus and erect positions were made in various phases of respiration to evaluate the visibility of small amounts of free intraperitonel air. Films were also made with various positions of the central ray of the x-ray beam. The expiratory left lateral decubitus film nd the mid-inspiratory chest film demonstrated the small pneumoperitoneums best. Both inspiration and expiration chest films are recommended inm the refilming and expiration chest films are recommended in the refilming sequence if a clinically suspected pneumoperitoneum is not visualized initially. In all cases the central ray of the x-ray beam should be at the highest level fo the peritoneal cavity.

Humans↗
PubMed1980

Tegument-associated antigen modulation by adult male Schistosoma mansoni.

Adult Schistosoma mansoni from mice were incubated in rabbit anti-mouse immunoglobulin class or subclass-specific sera. The rabbit antibody binding was then visualized by incubation of the labeled worms in fluoresceinated Staphylococcus aureus, which associated with the Fc portion of the rabbit antibody molecule by means of bacterial cell wall Protein A. The assay system was found to be simple, inexpensive, specific, repeatable, and rapidly accomplished. By using this technique, previous work documenting the presence of mouse IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM on the tegumental surface of adult worms of mouse origin was confirmed. It was further confirmed that the complexing of rabbit antibody to the mouse antigen led to the shedding of that antigen from the parasite's surface membrane within 20 min at 37 degrees C. This shedding phenomenon was specific for only those antigens interacting with the ligand and was inhibited by incubation with sodium fluoride, 2-deoxy-D-glucose, cytochalasin B, cytochalasin D, caffeine, or at 4 degrees C. These data indicate a sophisticated control mechanism exercised by the parasite over its interface with the host and may indicate a complexity of the host-parasite relationship not heretofore recognized.

Animals↗
PubMed1980

Incarcerated obturator hernia: two case reports and review of the literature.

Two patients were recently treated for incarcerated obturator hernias. Although the entity is unusual, the consequences of strangulation obstruction magnify its importance. Awareness of the natural history of the disease and the pathognomonic Howship-Romberg sign should reduce the incidence of gangrenous bowel and its resultant complications. The pitfalls encountered in the care of two patients and a review of the literature form the basis for this report.

Aged↗
PubMed1980

[The colon examination (author's transl)].

The examination of the colon in its entirety is accomplished best and most economically by roentgenologically. The author stresses the two most common but separate methods for colon examinations: the full column method of low density barium sulfate suspension and the air contrast examination. The contraindications to the examination are discussed as well as the preparation for the examination, the drugs that are used, the equipment, plain films, the full column technique, the air contrast technique, barium suspensions, drainage of the rectum, other details, and an evaluation of selecting the best radiographic method. Also, discussed is the critical review of the radiograms, fluororscopy, and the high risk group of patients that should have a primary air contrast colon examination. This latter group of patients are those with the following findings: 1) rectal bleeding for any reason or a history of bleeding; 2) polyps on endoscopic examination; 3) previous history of polyps or carcinoma; 4) a strong family history of polyps or carcinoma; 5) patients over 40 years of age; 6) a change in bowel habits, weight loss, unexplained anemia, previous uretero-sigmoid anastomosis, long standing inflammatory bowel disease, hemoccult positive stools, or other signs, on the basis of which the clinician or radiologist should have an index of suspicion for carcinoma.

Air↗
PubMed1979

Enterocylsis: the small bowel enema. How to succeed and how to fail.

Enteroclysis, the infusion of contrast medium directly into the small bowel, is a precise, rapid method for thorough small bowel examination. This technique demonstrates far more pathology than any other method when it is properly executed. However, the examination is sure to fail with poor techniques, thereby discrediting a superb method. Experience has shown that failures are usually due to inadequate technique or poor judgment or both during the examination. This article covers the proper and improper techniques of the examination and gives examples of each. The most common problems that arise during the examination are discussed in the order in which they usually develop.

Adult↗
PubMed1979

Gastrointestinal radiography with glucagon.

This report summarizes the results of nine diagnostic radiographic studies done double blind crossover comparing glucagon to placebo and to anticholinergic drugs in volunteers. In seven studies the subjects were administered drug intramuscularly and in two studies intravenously. There were five diagnostic studies of the upper gastrointestinal tract, one for esophageal varices and three of the colon. The results indicate that glucagon can be given intramuscularly and intravenously. When given intravenously it has a rapid onset and predictable length of action depending on the dose given. Reports of side effects were few consisting primarily of nausea and or vomiting. These results indicate that glucagon is the drug of choice for hypotonic diagnostic examinations.

Atropine↗
PubMed1979

Automated cervical cytology screening: performance requirements and instrument evaluation.

Continuing progress towards automation of cervical cancer screening requires that criteria for clinical acceptability of automated systems be defined, and that methods be devised for effectively evaluating new technology. The potential roles of automation in cervical cancer detection, performance requirements, instrument evaluation and useful contributions from tuberculosis screening, automated white blood cell differential counting, signal detection theory and decision theory are discussed.

Automation↗