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Biomedical subjects

D W Ramey

Publications and source records attributed to D W Ramey.

14 recordsLinked to original sources
PubMed2001

Look before you leap.

Learning to critically evaluate therapeutic claims is vital to the success of the practicing veterinarian and the veterinary profession as a whole. Until such time as good scientific data in support of therapies are obtained, veterinarians should be careful in their advocacy and employment of new and unproved practices. They should also be aware of the many reasons why therapeutic "success" may be the result of a variety of factors unrelated to the treatment modality itself. Only by relying on rigorous standards of evidence can equine veterinarians prevent a return to the sincere but misguided ways of yesteryear.

Animals↗
PubMed2000

Effect of a static magnetic field on blood flow to the metacarpus in horses.

OBJECTIVE: To determine the effect of a static magnetic field on relative blood flow to the metacarpus of horses. DESIGN: Randomized controlled clinical trial. ANIMALS: 6 healthy adult horses. PROCEDURE: Red blood cells were radiolabeled in vivo by administration of technetium Tc 99m (pyro- and trimeta-) phosphates, and scintigraphic images were obtained 30 minutes later. A magnetic wrap that emitted a static magnetic field was applied to 1 metacarpus and a control wrap was applied to the contralateral metacarpus. Forty-eight hours later, the wraps were removed, and scintigraphy was repeated. Relative perfusion ratios were calculated by dividing mean count per pixel for the portion of the metacarpus under the wrap by mean count per pixel for a portion of the distal aspect of the antebrachium that was not in the magnetic field. RESULTS: The difference between the relative perfusion ratio prior to application of the wrap and the ratio after application of the wrap for limbs that received the magnetic wrap was not significantly different from the difference in ratio for limbs that received the control wrap. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in horses, the static magnetic field associated with application of commercially available magnetic wraps for 48 hours does not increase blood flow to the portion of the metacarpus underneath the wrap.

Animals↗
PubMed1990

Chemistry for commercial scale production of yttrium-90 for medical research.

Studies were initiated at Oak Ridge National Laboratory (ORNL) in 1982 for the radiolabeling of resin microspheres with yttrium-90 (90Y) for liver cancer therapy. Yttrium-90 is the decay product of strontium-90 (90Sr). Subsequently, 90Y became a major radioisotope of choice for labeling antibodies for therapeutic trials in the treatment of other forms of cancer. A 25-Ci 90Y 90Y generator or 90Sr cow was placed in service to supply the anticipated needs of customers. In vivo use of 90Y required that the 90Sr contamination levels be kept below 10 muCi/Ci 90Y (corrected to preparation time). Also, it was necessary to remove trace metals that interfered in the 90Y antibody radiolabeling process, giving low radiolabeling yields. Di-(2-ethylhexyl) phosphoric acid (HDEHP) in dodecane has been used routinely at ORNL to extract 90Y and thereby give a product that meets the radiochemical purity required with respect to 90Sr. Methods were also developed to remove interfering trace elements to provide acceptable labeling yields.

Isotope Labeling↗
PubMed1985

Tracheal compression secondary to abscessation of cranial mediastinal lymph nodes in a horse.

Respiratory distress and laryngeal paralysis were found to be caused by a Streptococcus equi abscess of cranial mediastinal lymph nodes, putting pressure on the trachea at the thoracic inlet. Surgical drainage was required to relieve the compression, and long-term antibiotic therapy was used to treat the bacterial infection. The trachea returned to normal diameter but left laryngeal hemiplegia persisted. Peritracheal abscesses should be considered in the differential diagnosis of inspiratory dyspnea of the horse.

Abscess↗
PubMed1984

Sand-induced diarrhea in a foal.

A diagnosis of sand enteropathy was made in a 3 1/2-month-old Quarter Horse filly. Clinical signs included diarrhea and weight loss of 2 1/2 months' duration. Abdominal radiographs were useful in diagnosis of the condition and in evaluating response to therapy. The filly responded to treatment with psyllium hydrophilic mucilloid although full recovery took 2 months. Diagnosis and treatment of sand enteropathy is discussed.

Animals↗
PubMed1981

Analytical and biological analyses of test materials from the synthetic fuel technologies. III. Use of sephadex LH-20 gel chromatography technique for the bioassay of crude synthetic fuels.

To determine the health effects associated with newly emerging energy technologies, we have subjected a group of synthetic fuels to mutagenicity evaluation, using the Ames Salmonella assay. Coupling of chemical fractionation to the mutagenicity assays was necessary. Fractions obtained by use of Sephadex LH-20 gel chromatography on crude-coal-derived oils and shale oil were tested for mutagenicity with strain TA98 (with Aroclor S9 mix). Mutagenicity results obtained with synthetic fuels were compared with those from a mixture of natural petroleum crude oils. Merits of the Sephadex LH-20 separation technique and precautions in interpreting experimental results are discussed.

Chromatography, Gel↗
PubMed1979

Mutagenicity of cyclic nitrosamines in Salmonella typhimurium: effect of ring size.

Mutagenicity of cyclic nitrosamines with varying carcinogenic potentials was assayed in the Salmonella histidine-reversion system. Mutagenicity in the pour-plate assay was compared with that in the liquid pre-incubation test. The smaller ring compounds (nitrosoazetidine, nitrosopyrrolidine, and nitrosopiperidine) exhibited a similar effect in both assays. The large ring compounds (nitrosohexamethyleneimine, nitrosoheptamethyleneimine, nitrosooctamethyleneimine, and nitrosododecamethyleneimine) were more effective in the liquid pre-incubation test. Our results suggest a reasonable relationship between their mutagenic and carcinogenic activities.

Drug Evaluation, Preclinical↗
PubMed1978

Mutagenicity of methylated N-nitrosopiperidines in Saccharomyces cerevisiae.

N-Nitrosopiperidine (NP) and a number of methylated derivatives were examined for mutagenicity in Saccharomyces cerevisiae. NP, 2-methyl-NP, 3-methyl-NP, 4-methyl-NP and 3,5-dimethyl-NP were mutagens when metabolic activation (rat-liver microsomes) was provided. 2,6-Dimethyl-NP was not a mutagen. The NPs giving a positive response stimulated forward mutation to canavanine resistance (CAN1 leads to can1) and reversion of the his1-7 missense marker. Neither locus revertants nor suppressors of the lys1-1 ochre marker were induced, nor were revertants of the putative frameshift hom3-10.

Animals↗