Search PubMed⌕ Search

Biomedical subjects

R E Davis

Publications and source records attributed to R E Davis.

At least 217 records · Page 12Linked to original sources
PubMed1983

A microbiological assay for the measurement of methotrexate in biological fluids.

A microbiological assay for the measurement of methotrexate has been designed, using a chloramphenicol resistant mutant of Lactobacillus casei as the test organism. The method is simple, precise and inexpensive. Results are not significantly different from those obtained using a methotrexate radioassay kit employing a competitive protein binding technique. However, where patients are being treated with co-trimoxazole, the competitive protein binding technique is unsuitable for measuring methotrexate levels due to the cross reactivity of the binder. This is not a problem with the microbiological assay described here, which is able to measure methotrexate in the presence of large doses of trimethoprim. The methods were not affected by the presence of seven commonly encountered antibiotics. These had negligible effect on either method up to concentrations of 100 mg/l.

Anti-Bacterial Agents↗
PubMed1983

A unique T-cell monoclonal antibody with potential uses in autologous bone marrow transplantation.

A monoclonal antibody reactive with an antigen expressed by a T-cell subset has been produced. The antibody designated RPH-1 reacts with a subset of normal T-cells and thymocytes. The antibody was strongly reactive with blast cells from 3 patients with T-acute lymphoblastic leukemia (T-ALL) and also reacted with cells of 2 patients with non-T-ALL. The antibody did not react with leukemic cells from patients with acute myeloid leukemia (AML) or B-chronic lymphocytic leukemia (B-CLL)). RPH-1 reacted with 2 T-cell lines, no B-cell lines and no myeloid cell lines. Absence of toxicity to granulocyte macrophage colony forming units (CFU-GM) by RPH-1 in the presence of complement was demonstrated, and in view of strong reactivity with certain leukemic cells, potential application of RPH-1 as an immunological means of selectively removing tumour cells is indicated.

Adolescent↗
PubMed1983

A simplified colorimetric method for the measurement of glycosylated hemoglobin.

A colorimetric method for the measurement of glycosylated hemoglobin is described. The method is based on the detection of hydroxymethylfurfural liberated from the ketoamine-linked hexose of glycosylated hemoglobin. Rapid hydrolysis is achieved by heating at 120-124 degrees C under pressure, and simplification of the procedure enables the test to be performed in one disposable test tube. Standardization is by means of easily prepared lyophilized human hemoglobin preparations. The test has proven to be reliable and economical in routine use.

Chromatography↗
PubMed1983

Task and cost analysis of integrated clinical pharmacy services in private family practice centers.

Costs and activities required for the provision of integrated clinical pharmacy services were examined in private family medicine centers in rural South Carolina. Work sampling and financial data for a one-year period were merged, yielding an average clinical service cost of $1.65 per center patient visit. Pharmacists in family medicine environments spent almost twice the amount of time in clinical activities as has been shown in studies of their colleagues in chain store environments, and one half as much time in prescription-dispensing activities. A greater proportion of the former's workday was also spent in communication with patients. Costs for prescriptions dispensed in these rural centers combined with the average national net profit per prescription yielded a total cost that was within a few cents of the national average. Hence, costs can be controlled to the extent that maintenance of a competitive prescription-pricing policy is possible. Integration of clinical pharmacy services in family practice centers appears to be an economically viable practice model.

Ambulatory Care Facilities↗
PubMed1982

Picrotoxin-induced disruption of bidirectional active avoidance behavior and locomotor activity.

The effects of picrotoxin (0.75 and 1.5 mg/kg), an antagonist of GABA mediated chloride ion conductance changes, were examined on the acquisition and performance of a bidirectional active avoidance (BAA) response and on locomotor activity. Treatment with this agent disrupted both the acquisition and performance of this task and decreased locomotor activity. This picrotoxin-induced suppression of BAA was reversed by pretreatment with diazepam (2 mg/kg), d-amphetamine (d-AMP, 2.0 mg/kg) and lysergic acid diethylamide (LSD, 10 micrograms/kg) and was reversed partially by cinanserin (5 mg/kg) and methysergide (5 mg/kg). Picrotoxin-induced activity decreases in locomotor activity were antagonized by d-AMP, were partially reversed by LSD but were not reversed by methysergide. It is proposed that picrotoxin disrupts bidirectional active avoidance behavior by increasing the response suppressive effects of aversive stimuli and by inducing a general depression of motility.

Animals↗
PubMed1982

High serum thiamine and the sudden infant death syndrome.

Serum thiamine concentrations in 233 infants dying from the sudden infant death syndrome were compared with those found in 46 infants dying from other explicable causes. The levels in the sudden infant death group ranged from 22- greater than 500 micrograms/1 (mean 144.3 micrograms/1) and in the controls less than 1.0-95 micrograms/1 (mean 26.5 micrograms/1). The difference was highly significant (p less than 0.001). Only 13 (5.6%) of the sudden infant death group had a serum thiamine concentrations below 50 micrograms/1 whereas four (8.7%) of the control infants had a level above 50 micrograms/1. Thiamine was measured in nine samples of human breast milk and was present in concentrations ranging from 55-366 micrograms/1 (mean 178 micrograms/1); manufactured milk based formulae contained up to 2160 micrograms/1. Absorption of thiamine in man is rate limited but it appears that in infants dying from the sudden death syndrome the vitamin may be freely absorbed leading to very high serum levels.

Animals↗
PubMed1982

Cholesterol and lipoprotein-cholesterol levels in Western Australian rural diabetics.

Total cholesterol, high-density lipoprotein-cholesterol (HDL-C) and non-HDL-cholesterol (non-HDL-C) were measured in the serum of diabetics from four country regions in Western Australia in order to document the levels and to examine the relationships between treatment mode, degree of diabetic control and lipid concentrations. In most age groups total cholesterol and non-HCL-C did not differ from levels in a large reference population, but HDL-C levels were generally lower. Male NIDDM patients on insulin had greater HDL-C levels than patients on oral hypoglycaemics, but their degree of control as determined by the level of glycosylated haemoglobin was poorer, and amongst female patients on insulin those with higher HDL-C levels had poorer control. These results confirm previous reports of higher HDL-C levels in patients on insulin, but are contrary to reports suggesting that better control is associated with higher HDL-C levels.

Adult↗
PubMed1982

Technique for human bone marrow harvest.

The usual technique of harvesting bone marrow for allogeneic or autologous transplantation involves passage of the marrow suspension through discs of stainless steel mesh of increasingly small diameter. We describe a sterile technique which is much less messy and produces a single cell suspension. Potter-Elvehjem homogenizers are used to break up the marrow particles. This procedure has been used successfully in 6 patients where allogeneic transplantation was performed and in 6 harvests of autologous marrow. Marrow cryopreserved in this way contains viable committed stem cells and is not subject to agglutination following subsequent thawing.

Bone Marrow Cells↗
PubMed1981

High-dose co-trimoxazole and its penetration through uninflamed meninges.

Normal doses of co-trimoxazole (two ampoules or two tablets twice a day) gave low cerebrospinal fluid concentrations of trimethoprim and sulphamethoxazole in neurosurgical patients. For two years, four ampoules of co-trimoxazole twice a day, followed by four tablets twice a day, which were administered to neurosurgical patients and to patients admitted to hospital with skull fractures, produced no toxicity and this regimen has not been associated with postoperative meningitis. After the high-dose regimen in patients with uninflamed meninges, trimethoprim concentrations in the cerebrospinal fluid ranged from 2.6 mumol/L to 12.4 mumol/L (0.75 mg/L to 3.6 mg/L), and in the serum from 9.6 mumol/L to 42.7 mumol/L (2.8 mg/L to 12.4 mg/L). However, the bacteriostatic and bactericidal activities of the spinal fluids and sera were very variable, some with high concentrations appearing to have negligible antibacterial activity in vitro. We have treated a few patients with serious infections with dosages of 12 ampoules or 12 tablets twice a day with successful results. Studies of serum folate, 5-methyltetrahydrofolate and granulocyte dihydrofolate reductase levels showed no toxic effects from the high-dose regimen.

Adolescent↗
PubMed1981

Behavioral effects of unilateral dopamine injection into dorsal or ventral striatum.

Dopamine or its vehicle saline was injected unilaterally into dorsal striatum, ventral striatum, or sites outside the striatum in adult male rats. Direction, duration and frequencies of ongoing behaviors were measured. Dopamine injected into any site within the striatum immediately elicited more contralaterally directed behavior than the vehicle injected into the same site. The contralaterally directed behaviors were no longer duration when injected into the dorsal than into the ventral striatum, a result which might reflect regional differences in numbers of dopamine receptors or distribution of efferents. At the doses employed (25 and 100 microgram), dopamine injected unilaterally into the striatum did not induce rotation, stereotyped behavior, or even a significant change in the frequencies of ongoing behaviors; rather, all ongoing behaviors were expressed in a contralateral direction. Thus, the behavioral effects of dopamine in the striatum are best understood as a change in sensory-motor responsiveness.

Animals↗
PubMed1981

Glyoxalase phenotypes in patients with diabetes mellitus.

Caucasian diabetic patients in Australian surveys showed a significant difference in the distribution of glyoxalase phenotypes. Insulin dependent diabetic patients with age of onset less than 40 years had a relative excess of glyoxalase homozygote 1-1 and a deficiency of types 2-1 and 2-2. Non-insulin dependent diabetic patients were not significantly different from non-diabetic subjects in the distribution of glyoxalase phenotypes. Insulin dependent diabetic patients without the complications of retinopathy or neuropathy also showed a significant excess of glyoxalase type 1-1 in relation to the control group. Genes controlling glyoxalase polymorphism appear to be associated with the variations of diabetes and its complications.

Australia↗
PubMed1981

Antibiotic sensitivities in vitro of diverse spiroplasma strains associated with plants and insects.

Fifteen spiroplasma strains, representing five serological subgroups classified in three distinct serogroups, and four strains unassigned to serogroups were examined for sensitivity to antibiotics. The data contribute to the characterization of spiroplasmas and enlarge comparisons between plant pathogenic strains and strains that are evidently a part of the normal epiphytic microflora.

Journal Article↗