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Biomedical subjects

L Davis

Publications and source records attributed to L Davis.

At least 253 records · Page 14Linked to original sources
PubMed1980

Drug therapy assessments by pharmacists.

Drug therapy assessments made for ambulatory patients by pharmacists and those made by the patients' primary physicians were compared. Using refill assessment guidelines, pharmacists evaluated the drug therapy regimens of patients attending a general medicine clinic before they were seen by their physicians. At the end of each clinic day, the pharmacists compared their assessments with the physician evaluations. Of the 155 drug regimens reviewed, the study pharmacists would have continued 104 (67.1%) without alteration, changed 48 (31.0%), and referred three patients (1.9%) with new problems for physician evaluation. The differences between pharmacist assessment and physician agreement were not significant (p greater than 0.2), but there was a significant difference between pharmacist assessment and physician actions (p less than 0.005), because the physicians actually changed only 52% of the drugs they agreed could be changed. The study suggests that the pharmacist is able to detect drug therapy problems and to recommend appropriate actions for resolving them.

Drug Prescriptions↗
PubMed1979

Enhanced 5-fluorouracil nucleotide formation after methotrexate administration: explanation for drug synergism.

Exposure of L1210 leukemia cells first to 0.1 to 100 micromolar methotrexate and then to 10 micromolar 5-fluorouracil produces a synergistic effect on the number of cells killed in culture. Methotrexate dose-related increases occur in the concentrations of intracellular 5-fluorouracil ribonucleotides and 5-fluoro-2'-deoxyuridylate and in the incorporation of 5-fluorouracil into RNA. These increases are correlated with increased concentrations of intracellular phosphoribosylpyrophosphate. It is proposed that the enhanced formation of ribonucleotides of 5-fluorouracil and the subsequent incorporation of these compounds into RNA in methotrexate-treated cells may account for synergism between these agents.

Animals↗
PubMed1979

Serine hydroxymethylase. Specificity of bond cleaveage to form quinonoid intermediates and rate of holoenzyme formation.

L-Serine transhydroxymethylase (5,10-methylenetetrahydrofolate:glycine hydroxymethyltransferase, EC 2.1.2.1) a pyridoxal phosphate-dependent enzyme, has been obtained as a homogeneous preparation with a specific activity of 6.7 mumol benzaldehyde per minute at 30 degrees C at pH 7.5 in N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (Hepes) buffer, with DL-threo-beta-phenylserine as a substrate. This enzyme has been used to study the specificity of bond cleavage in forming quinonoid intermediates from DL and non-asymmetric amino acids. The ability of the generated quinonoids to react with formaldehyde and acetaldehyde has also been studied and evidence obtained for formation of the corresponding beta-hydroxymethyl and beta-hydroxyethyl amino acid derivaties. Apotranshydroxymethylase has been prepared and the rate of holoenzyme formation was found to be 0.52 min-1 by measuring Schiff base formation at 425 nm and 0.66 min-1 as determined from restoration of enzymic activity. A requirement for the presence of mercaptoethanol for complete reactivation was also established by these studies.

Aldehydes↗
PubMed1979

Clozapine induced increase of human plasma norepinephrine.

Four psychotic patients and 5 controls were treated with clozapine (200--400 mg/day during 30 days, patients, respectively 100 mg/day during 7 days, controls) and plasma norepinephrine (NE) concentration was measured. In the morning, shortly after end of sleep, plasma NE concentration was significantly increased under clozapine treatment in both populations. The effects of clozapine were explained with a direct pharmacological action of the drug on NE receptors.

Adult↗
PubMed1979

Properties of extracellular neuraminidase produced by group A streptococcus.

Extracellular neuraminidase production by group A streptococci was examined in 92 strains. Fourteen of these strains produced appreciable amounts of enzyme; 12 of the neuraminidase-producing strains belonged to T types 1, 4, and 12. Production of the enzyme paralleled bacterial growth in culture and was maximal in medium containing 0.2% glucose. The enzyme produced by one of these strains was partially purified by ammonium sulfate fractionation and filtration on G-200 Sephadex. Its molecular weight was estimated at 90,000. Activity was optimal at pH 5.7 and in the presence of 0.01 to 0.03 M calcium and magnesium cations. The enzyme was stable at temperatures of 4 and 37 degrees C for at least 24 h but was inactivated within 10 min at temperatures of 50 and 65 degrees C. The enzyme hydrolyzed 40% of the sialic acid in bovine submaxillary mucin, but was inactive on sialyl-lactose, porcine submaxillary mucin, oligosaccharides derived from porcine mucin, or human orosomucoid. The Km value for this enzyme with bovine submaxillary mucin as substrate was in the order of 3.6 x 10(-4) M.

Calcium↗
PubMed1979

Isaacs syndrome with laryngeal involvement: an unusual presentation of myokymia.

A woman with widespread myokymia presented initially at age 19 with hoarseness and mild dyspnea on exertion. The diagnosis of Isaacs syndrome was suggested by the clinical findings of widespread continuous muscle activity and depressed tendon reflexes, although she lacked the usually prominent increased muscle tone. The diagnosis was confirmed by the electromyographic demonstration of continuous spontaneous muscle action potentials that were abolished by neuromuscular blockade but not by local nerve blockade. Pulmonary function tests were consistent with fixed extrathoracic obstruction. The vocal cords were closely approximated. Electromyographic studies of the laryngeal muscles under general anesthesia revealed continuous muscle activity, which accounted for the hoarseness and much of the exertional dyspnea. The patient responded well to treatment with phenytoin and carbamazepine. This unusual syndrome should be considered in the differential diagnosis of patients with respiratory complaints and muscle fasciculations, even though they have normal muscle tone.

Action Potentials↗
PubMed1978

Blood glucose rise after lactose tolerance testing in infants.

Lactose tolerance tests are used clinically to screen children and infants. It is assumed that absorption of a lactose challenge in infants would occur in a predictable pattern prior to weaning. Twenty-one infants from 3 to 12 months of age were studied. The maximum blood glucose rise over fasting levels ranged from 11.0 to 62.0 mg/100 ml; the mean was 32.6 mg/100 ml. Six infants had a maximum rise of less than 20 mg/100 ml. Eleven infants (52%) had a maximum rise of greater than 30 mg/100 ml. Signs of intolerance were not noted in any subject. Weight and length were normally disturbed. Results indicate the variance in glucose rise existing within a population of infants growing normally and consuming milk. Gastric emptying, digestion, and absorption may influence the blood glucose rise after a lactose test. Established glucose levels used as an index to lactose absorption in older children and adults may not accurately reflect lactase activity in infants.

Blood Glucose↗
PubMed1978

Endemic Serratia marcescens in the Veterans Administration Hospital in Pittsburgh, Pa., 1971--1976.

The incidence of infections due to Serratia marcescens increased steadily at the Veterans Administration Hospital in Pittsburgh, Pennsylvania from 1970 to mid 1975 followed by a decline extending into 1977. One hundred eighty-four Serratia marcescens isolates were collected from 123 patients over a 4-month period in 1975 and were characterized by stereotype and antibiotic sensitivity. Three-fourths of the isolates were clinically significant. Among 24 stereotypes O-:H2 predominated in the urinary tract and O-H12 in respiratory secretions. Clusters of serotypes were on occasion identified in the GU Surgery Ward and the Intensive Care Unit. Uninary isolates showed remarkable resistance to antibiotics; only two thirds were susceptible to amikacin, the most effective agent in vitro. The patients from whom Serratia was isolated were older than the general hospital population (60 vs. 53.6 years of age), were hospitalized longer than the age-corrected controls (62 vs. 34.5 days) and two-thirds of thirds of them acquired the infection in the hospital. Uninary catheterization and prior antibiotic therapy were significant risk factors for urinary infections, and prior surgery contributed to recovery of Serratia from the respiratory tract. Serotype and antibiotype differences between isolates from the urinary and those from the respiratory tract suggest that strains evolved a site specificity.

Anti-Bacterial Agents↗
PubMed1977

Stable long-term recordings from cat peripheral nerves.

A procedure has been developed for the stable long-term recording of nerve signals in unanesthetized mammals, which should have wide application in basic research on the nervous system and also in clinical areas such as the derivation of control signals for powered prostheses. Methods are fully described for constructing devices consisting of (1) Silastic nerve cuffs containing three or more electrodes, (2) coiled leads insulated with Silastic which extend from the cuffs to an integrated circuit socket, (3) a vitreous carbon transcutaneous connector which surrounds the integrated circuit socket and makes a good interface with the skin. Neural activity has been recorded from mammalian nerves for many months during normal behaviour. The peak-to-peak amplitude and latency of the recorded compound action potentials remain stable and may continue at a constant level more or less indefinitely. A tripolar recording configuration between a central lead and the two end leads, which are connected together, permits good rejection of EMG signals from surrounding muscles. The amplitude of single unit potentials increases as the square of the conduction velocity of the nerve fibre. Thus, the largest nerve fibres will dominate the signals recorded during behaviour. The reasons for premature termination of a few experiments are given together with methods for overcoming these problems. For example, platinum-iridium electrodes remain relatively stable, whereas silver wires tend to fracture after being in an animal for several months. This and other relationships are discussed which permit an optimal design of nerve cuffs for a given recording situation.

Action Potentials↗
PubMed1977

Melanin distribution and sensitivity to group therapy.

Student participants in group therapy were hypothesized to improve on three dimensions of behavior as a result of therapy. It was further hypothesized that improvement would be related to participant eye color, with dark-eyed persons demonstrating greatest improvement and lighter-eyed individuals demonstrating lesser improvement. Differences were also expected from Ss by program. Ss were 35 male and female master's level students in clinical, counseling, and educational psychology programs, ranging in age from 23 to 39 years. Dependent measures were collected before and after therapy with the Vriend and Dyer Scale, an instrument yielding three factors: Self Defeating Behaviors, Fully Functioning Behaviors, and Personal Mastery Index. The design utilized a 3 (eye color) X 2 (program) two-way ANOVA, fixed effects model. Significant main effects were found for Fully Functioning Behaviors: by eye color (p less than .002) and by program (p less than .03). No interactions or other main effects were found.

Adult↗
PubMed1977

Lactose malabsorption in preschool black children.

One hundred sixteen healthy black children ages 13 to 59 months, representing high and low socioeconomic deciles, were studied for lactose malabsorption. A fasting lactose tolerance test using 2 g of lactose/kg of body weight was carried out. Glucose was determined at 0, 15, 30, and 60 min. Of the 116 preschoolers 34 (29%) evidenced lactose malabsorption as determined by a blood glucose rise of less than 26 mg/100 ml. Clinical signs of diarrhea, gas, and cramps were noted singly or in combination in 18% of the 34 lactose-malabsorbing children. Of the 82 lactose absorbers, 12% demonstrated similar signs. The nature and length of the initial infant milk feeding failed to show any relationship to the onset of malabsorption. Current milk drinking patterns were reported as being similar. Eight-seven percent of the malabsorbers and 92% of the absorbers report drinking 240 ml or more of milk/day. Socioeconomic status, education, marital status, and medical assistance of the parent is similarly distributed between lactose absorbers and malabsorbers.

Absorption↗