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Biomedical subjects

R Schaffer

Publications and source records attributed to R Schaffer.

66 records · Page 4Linked to original sources

Levodopa-enhanced recovery from paralysis induced by air embolism.

In this study levodopa was chosen as an agent that might ameliorate the clinical manifestations of paralysis induced by air embolism because of reported effects of this drug on muscle spasticity and locomotion. In order to induce air embolism, the aorta of rats was cannulated chronically. Fifteen days later, after full recovery of the animals, air was administered through the chronic cannula into the descending aorta of each rat (0.35 ml. of air per 100 Gm. during 4 seconds). The paralysis of both hind legs was observed one to 10 minutes later. Only animals that had total paralysis of both hind legs, without any sensation, were used in the experiments. levodopa was administered 2 minutes after experimentally induced paralysis. The levodopa treatment was repeated every day for 6 days. After 6 days, six levodopa-treated (intraperitoneally) animals in a group of eight and ten levodopa-treated (intra-arterially) animals in a group of 12 recovered fully from the paralysis. Only three animals in a group of 13 (untreated) or two animals in 12 (solvent administration) recovered without the levodopa treatment.

Animals↗

Purification and analysis of the purity of NADH.

We developed an analytical reverse-phase high-performance liquid chromatographic procedure for rapid assessment of the purity of NADH. The method completely separates adenosine monophosphate and adenosine diphosphoribose from NADH. By use of this analytical technique we found that preparative chromatography on DEAE-cellulose gives NADH that is free from adenine nucleotides as well as other impurities that commonly are present in NADH. The absorbance ratio at 260 and 340 nm of the purified NADH in 1.8 mmol/liter ammonium carbonate is 2.261 +/- 0.002 (+/- 1 SD).

Bicarbonates↗

Detection of inhibitors in reduced nicotinamide adenine dinucleotide by kinetic methods.

Methods are described for detection of lactate dehydrogenase (LDH) inhibitors in preparations of reduced nicotinamide adenine dinucleotide. They are (a) comparison of values by kinetic methods with those measured for highly purified NADH and (b) examination of Lineweaver-Burk plots. Chromatographic inhomogeneities are correlated with deviant values for the kinetic constants of NADH preparations. Lineweaver-Burk plots that curve upward at the high concentrations or have a larger or smaller than normal slope may indicate the presence of inhibitor. As determined in bicarbonate buffer (0.11 mol/liter, pH 7.9) by use of 0.600 mmol/liter pyruvate and NADH freshly separated from impurities by chromatography on diethyl-aminoethyl-cellulose, the Km (apparent) of NADH at 25 degrees C has the value 8.11 +/- 0.71 mumol/liter (SD, n = 28) with LDH-1 (pig heart, 2.48 +/- 0.05 U per milliliter of reaction mixture, or 41.3 +/- 0.8 nmol/liter per second). Under similar conditions, the Km (apparent) of NADH has the value of 8.57 +/- 1.58 mol/liter (SD, n = 21) with LDH-5 (pig muscle, 1.77 +/- 0.03 U/ml of reaction mixture), or 29.4 +/- 0.6 nmol/liter per second). At infinite substrate concentrations with the same pH, buffer, and temperature, the Km (apparent) for NADH was 26.0 +/- 0.63 mumol/liter with LDH-1 and 23.2 +/- 4.6 mumol/liter with LDH-5.

Chromatography, High Pressure Liquid↗

Techniques for induction of neutropenia and granulocytosis in rats.

After a single administration of vinblastine, rats develop profound neutropenia. The agranulocytosis lasts 3 days, and it is observed on the third, fourth and fifth day after vinblastine administration. The granulocytosis that develops on days 7-14 after vinblastine administration was significantly increased when androgenic steroids were administered. Deca-Durabolin induced greater granulocytosis than testosterone. The peak values were observed 10 and 12 days, respectively, after drug administration. All values of WBC's, granulocytes and hematocrit ratios were obtained in unanesthetized, unrestrained rats from an aortic cannula implanted at least 10 days prior to the experiment.

Agranulocytosis↗

Injectable agent for the treatment of air emboli-induced paraplegia in rats.

Rats with air emboli-induced paraplegia were treated with dialy levodopa injections (intra-arterially or intraperitoneally). Of the control animals, 20% fully recovered from paraplegia during a period of 7 d. Of the levodopa treated animals, 85% fully recovered during the same period. It appears, therefore, that levodopa might be one of the few injectable agents enhancing recovery from air-induced paraplegia, suggesting its possible use in decompression sickness.

Animals↗

Standardization of diagnostic materials. 1. Diagnostic materials for clinical analysis.

Standardization of diagnostic materials has lagged behind their development and application. The need to improve the accuracy of the results obtained with them has stimulated collaborative efforts to upgrade the quality of the reagents, control materials, and standards used, with the result that specifications for reagents and standards and authoritative standard materials are now available for a number of clinical tests. Achievements thus far and the efforts now in progress are reviewed.

Chemistry, Clinical↗

Renal cyclosporine clearance in marrow transplant recipients: age-related variation.

Cyclosporine is extensively metabolized in the liver and is subject to biliary elimination. Although only a small amount of the drug is eliminated unchanged in the urine, urine concentrations of the drug are much higher than blood or serum concentrations known to be associated with renal toxicity. Renal clearance (CL) of cyclosporine may be a sensitive correlate of nephrotoxicity, but renal CL studies of cyclosporine have not been reported in transplant patients. Therefore, we studied the renal CL of cyclosporine in 21 patients (median age, 27 yr) with hematologic malignancies undergoing allogeneic bone marrow transplantation. All patients received cyclosporine for prophylaxis or treatment of acute graft vs host disease. At the time of the study, all patients had normal renal function, as determined by serum creatinine concentration. Urine and serum cyclosporine concentrations were measured by high-performance liquid chromatography. Renal cyclosporine CL in different patients ranged from 1.8 to 79.8 mL/min. However, serial renal CL studies performed one week apart in two patients showed minimal intrapatient variability. Patients 25 years old or younger had a higher mean renal cyclosporine CL (39.7 mL/min) than older patients (17.9 mL/min) (P less than .05). These data show that renal cyclosporine CL is related to age and that renal CL in marrow transplant recipients is higher than the reported mean value in non-marrow-transplant patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗