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Biomedical subjects

C M Davis

Publications and source records attributed to C M Davis.

At least 91 records · Page 5Linked to original sources
PubMed1981

Rapid microanalysis of anticonvulsants by high-performance thin-layer chromatography.

A rapid microanalytical method is described for phenobarbital, phenytoin, primidone and carbamazepine utilizing high-performance thin-layer chromatography (HPTLC). This procedure incorporates a single extraction of a 50-microliter plasma sample. One tenth of the extract is concentrated and applied to the HPTLC plate by a Contact Spotter, chromatographically separated and quantitated by in situ ultraviolet reflectance densitometry. The coefficient of variation is less than 4% (n = 8), the extraction efficiency is approximately 95% and the minimum detectable amount of pure drug standards applied to and developed on the HPTLC plate is 5 ng or less for all four anticonvulsants.

Anticonvulsants↗
PubMed1981

Analysis of bone-composite interfacial strengths.

The strength characteristics of the interface between bone and a bone/porous metal composite were analyzed. The metal was 316L stainless steel. The average tensile strength of bone spicules ingrown to the porous metal was 46.5 MPa. This compares to a control bone sample strength of 89.7 MPa. The difference could be due to bone location and bone immaturity. The overall intefacial tensile strength (9.59 MPa) is necessarily lower since the spicules cover only a fraction of the interfacial cross-section. The overall interfacial strength had a wide range of scatter (s = +/- 4.11 MPa). This was probably due to inherent variations in bone strength with location. A population of samples using porous metal with average pore diameters under 100 micrometers exhibited measurably lower tensile strengths.

Animals↗
PubMed1981

Thiothixene plasma levels and clinical response in acute schizophrenia.

Plasma levels of cis and trans thiothixene were compared to clinical response in 8 acutely schizophrenic inpatients. While absolute plasma levels did not appear to correlate with clinical condition, the data did suggest that increases or decreases in cis plasma levels correlated with corresponding improvements or deteriorations in clinical condition in thiothixene responsive patients. While the results are very preliminary, the authors suggest that future studies differentiate the cis and trans isomers, and analyze relative as well as absolute changes in plasma levels as compared to clinical changes.

Acute Disease↗
PubMed1980

A drug dispenser to measure individual drinking in rat colonies.

This article describes an automated device which substantially facilitates the measurement of oral drug consumption by individual rats housed in a colony with a common drinking source. To drink, each animal enters a Plexiglas runway, triggering a video system which records the rat's identifying dye mark, and its consumption of each of two liquids. Rats learn to operate the device easily and rapidly. Data for 24 hours can be collected on a one-hour videotape.

Animals↗
PubMed1980

Comparison of standard chelating agents for acute mercuric chloride poisoning in mice.

A comparison in mice has been made of the effectiveness of five chelating agents used clinically for acute mercuric chloride poisoning, or recommended for such use. The compounds examined were N-Acetyl-D,L-penicillamine (NAPA), D-penicillamine (DPA), 2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercaptopropanesulfonate (DMPS), and 2,3-dimercaptopropanol-1 (BAL). The test of effectiveness was their ability to reduce the mortality of acute mercuric chloride poisoning when administered 20 minutes after the mercury at chelate:mercury mole ratios of 10, 15, 20, and 30. All except BAL were found to be effective at the highest mole ratio tested, but N-Acetyl-D,L-penicillamine and sodium 2,3-dimercaptopropanesulfonate were significantly more effective than DMSA and BAL at mole ratios of 10:1. The relative effectiveness does not correlate with available data on stability constants. The toxicity of BAL itself becomes apparent at mole ratios of 20:1 and above.

Animals↗
PubMed1979

Competency: the what, why, and how of it.

Competency is a frequently used term in the physical therapy profession, but many physical therapists are unclear about its definition and its meaning in professional activity. This article describes the operational definition of competency as used in the practice of physical therapy by members of the Association; describes the development of the manual, Competencies in Physical Therapy: An Analysis of Practice; offers direction in possible uses of the manual; and suggests future uses for the manual in Association activity.

Clinical Competence↗
PubMed1979

Evaluation of a commercial, porous stainless steel as a prosthetic implant material.

In the course of evaluating various porous materials as candidates for prosthetic devices, a commercial stainless steel (316L) was found which was designed for porous filtration applications. Small bars (approximately to 3mm x 3mm x 20mm) were implanted in dog extremeties for periods of 10 to 15 weeks. The average tensile strength of the bone/(bone/metal) interface was found to be 0.975 kgf/mm2 (1380 psi) with no indication of variation with time of implantation. Scanning electron microscopy (SEM) combined with X-ray energy dispersive (XRED) analysis indicates production of calcified bone in the bone/metal composite. Inherent strength and porosity characteristic combined with biocompatbility indicate that this commercially available meterial is a viable implant candidate for attachment to the skeletal system.

Animals↗
PubMed1978

The consistent acceleration of lifted objects: implications for kinesthetic illusions and the perception of weight.

In examining films of lifting movements in a study of the size-weight illusion (Davis & Roberts, 1976) a consistency was noted in the values obtained for the maximum accelerations of the objects lifted. While at first surprising, this finding can be embedded significantly in theories relating to kinesthetic illusions and the perception of weight and to theories on the control of general physical movement. This study was designed to confirm its existence. Twenty-four subjects were filmed lifting four objects differing in size, shape, substance, color, and weight. The film was analyzed frame-by-frame and the data were subjected to a two-way analysis of variance. Subjects, while differing from one another, were consistent in the maximum accelerations they applied to the three heaviest of the four objects. The accelerations of the lightest object differed significantly from the accelerations of the other three, but it seems likely that this was due to the experimental task itself.

Journal Article↗
PubMed1978

Determination of drugs in plasma by high-performance thin-layer chromatography.

High-performance thin-layer chromatography was used to determine chlorpromazine, amitriptyline, nortriptyline, imipramine, desipramine, phenobarbital, and phenytoin in plasma, to demonstrate the utility of this technique for routine analysis. We quantitated the separated components by use of ultraviolet reflectance spectrometry with detection limits as low as 1 microgram/liter. Regressions of psychoactive agents extracted from plasma were linear over the range of 0 to 300 microgram/liter. The anti-convulsant drugs, phenobarbital and phenytoin, were determined over a range of 0 to 50 mg/liter. Analyses were rapid, reproducible, and well-suited to large-scale programs. Separated components also can be identified in situ by ultraviolet spectrophotometry.

Amitriptyline↗
PubMed1978

The placental transfer and materno-fetal disposition of methadone in monkeys.

A method is described for the quantitation of levo-methadone[3H] in biological samples which involves sample extraction and thin-layer chromatographic separation. Four pregnant Macaca mulata monkeys, two in early gestation and two in late gestation, were given single i.m. injections of levo-methadone[3H]. Twenty-nine fetal and maternal tissues and fluids were assayed to provide quantities of unchanged methadone and methadone plus metabolites. Little placental transfer of methadone or its metabolites occurred during early gestation, but equivalent concentrations of unchanged methadone were found in maternal and fetal tissues during late gestation (maternal brain, 172 ng/g; fetal brain, 123 ng/g). With few exceptions, tissues or fluids from the late gestation mothers showed higher levels of unchanged methadone than those from early gestation mothers at both 1 hour (P less than .001) and 6 hours (P less than .010) after administration. The late gestation mother had a 40.2% greater concentration of unchanged methadone at 6 hours and a 50.1% greater concentration at 1 hour than the early gestation mothers. These data suggest a slowing of metabolism during advanced pregnancy. At 6 hours after administration the eyes of both early and late gestation mothers and late gestation fetuses showed the highest concentrations of unchanged methadone of any maternal or fetal tissue. This localization of methadone appears to be associated with pigmented epithelium.

Animals↗
PubMed1977

High-performance thin-layer chromatographic determination of psychopharmacologic agents in blood serum.

High-performance thin-layer chromatography affords a rapid, sensitive method for determination of psychopharmacologic agents in blood serum samples. Quantitation of the representative drugs chlorpromazine, amitriptyline, nortriptyline, imipramine, and desipramine at levels as low as 5 ng/ml is demonstrated by scanning the developed thin-layer plates with a chromatographic spectrophotometer in the ultraviolet absorption mode. Neither derivatization prior to, nor color development after chromatographic separation is required to achieve sensitivity and reproducibility of determinations.

Amitriptyline↗