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Biomedical subjects

R Thomas

Publications and source records attributed to R Thomas.

At least 631 records · Page 35Linked to original sources
PubMed1982

Circulatory dynamics during surface-induced hypothermia under halothane-ether azeotrope anesthesia.

Circulatory dynamics during surface- induced deep hypothermia using the halothane-diethyl ether azeotrope in 100% oxygen (O2) without circulatory arrest and 95% O2 and 5% carbon dioxide (CO2) with and without 60 minutes of arrest were evaluated in 15 adult mongrel dogs. Mean arterial pressure was lower in animals given 5% CO2 than in animals given 100% O2 during cooling. Cardiac output in the 5% CO2 groups increased until 30 degrees C cooling and then gradually decreased to 29% of control at 20 degrees C. Cardiac output in the 100% O2 group progressively decreased to 16% of control at 20 degrees C cooling and was 51 to 77% of the output in the 5% CO2 animals at comparable temperatures throughout the hypothermia procedure. The differences in cardiac output were attributed primarily to changes in stroke volume since heart rates were not significantly different. These changes were probably secondary to differences in systemic vascular resistance, which had increased sixfold in the animals given 100% O2 and had only doubled in the 5% CO2 groups at 20 degrees C during cooling. Hemodynamic variables in animals given 5% CO2 did not reveal significant differences in arrested versus nonarrested animals during early rewarming. However, with further warming, cardiac output, stroke volume, left ventricular stroke work, and mean pulmonary arterial and pulmonary artery wedge pressures were lower, and systemic and pulmonary vascular resistances were higher in the arrest group. We conclude that the improved results with halothane-diethyl ether azeotrope in 95% O2 and 5% CO2 during surface hypothermia are due to a greater cardiac output and reduced peripheral vascular resistance.

Anesthesia, Inhalation↗
PubMed1982

Vesicoureteral reflux in the primate IV: does reflux harm the kidney?

It has been said that vesicoureteral reflux causes renal scarring because of intrarenal reflux. We studied reflux in the monkey because of its similarity to man, especially in regard to the incidence of vesicoureteral reflux and chronic pyelonephritis. High pressure moderate grade reflux was produced and renal function followed by means of quantitative renal camera studies using 131I hippuran. There was no change in renal function from sterile reflux even when intrarenal reflux occurred. When, however, infection was introduced, renal function decreased. We concluded that sterile moderate vesicoureteral or intrarenal reflux does not harm the kidney.

Animals↗
PubMed1982

Aid to accurate clinical staging-histopathologic grading in prostatic cancer.

Recently, pathologic staging systems have been used to aid in accurate clinical assignment of prostatic disease. With this in mind, we reviewed retrospectively 130 patients who were diagnosed as having prostatic cancer either by needle biopsy or by study of transurethral resection chips. These specimens were graded by the Gleason and Roswell Park histopathologic grading systems. Grading was done by 2 pathologists independently and without knowledge of the results of final surgical staging. All patients were without evidence of metastases by standard diagnostic studies, and all underwent pelvic lymphadenectomy and radical prostatectomy if nodes were grossly negative. The surgical specimens were examined and the final clinical stage was correlated with the histopathologic grading. Independently, the Gleason rather than the Roswell Park system was slightly more accurate and was a more reliable predictor of the surgical stage of the disease. Of the patients with a Gleason sum of 7 or above 86 per cent had at least stage C disease, whereas the disease had been staged preoperatively as A or B. All patients with a Gleason sum of 2 to 5 had stage A or B disease.

Adenocarcinoma↗
PubMed1982

Cardenolide analogues. 14. Synthesis and biological activity of glucosides of C17 beta-modified derivatives of digitoxigenin.

An improved method for the synthesis of cardiac glycosides was used to prepare 3 beta-glucosides of digitoxigenin derivatives in which the 17 beta side chain was CH=CHX (X = COOH, CONH2, COCH3, CN, or COOR). We compared the inotropic activity of the compounds with that of digitoxigenin glucoside using guinea pig left atria. All compounds were active except for the acid (7) and the amide (8). The inactivity of the amide, in spite of its favorable shape and high capacity for forming intermolecular hydrogen bonds, is incompatible with some previous structure-activity relationship theories. Of the active genins, glucosidation enhanced activity by a factor of about 2. All glucosides, including those with high potency, showed rapid onset and offset of action. The stepwise fall in potency that occurred when the ester group (CH=CHCOOR) was increased in bulk supported previous suggestions that the portion of the digitalis receptor that interacts with the C17 side chain lies within a cleft.

Animals↗
PubMed1981

The renal quantitative scintillation camera study for determination of renal function after anatrophic nephrolithotomy.

The effect of hypothermic anatrophic nephrolithotomy was evaluated in 13 patients by comparing preoperative and postoperative renal quantitative scintillation camera studies. Total renal function as measured by effective renal plasma flow remained normal postoperatively. However, the operated kidney had a significant loss of function with a proportionate compensatory hypertrophy of the contralateral kidney. This finding explains the normal total renal function, the good end results of the operation being stable renal function if stones do not recur.

Blood Urea Nitrogen↗
PubMed1981

Modified Pereyra procedure for stress incontinence.

Results of the modified Pereyra cystourethropexy for stress incontinence are presented. The technique prevents a suprapubic suture from entering the bladder because of a vaginal approach into the space of Retzius. The surgeon's vaginal finger guides the suprapubic needle as it passes through the rectus. Thus, a non-absorbable suture may be used and the urogenital diaphragm is brought superiorly to raise and to support the floor of the pelvis. Results are continence in 97 to 100 per cent of 30 women.

Adult↗
PubMed1981

Toxicity with intravenous injection of crude marijuana extract.

Intravenous injection of crude marijuana extract led to development of an acute illness with multisystem involvement. Gastrointestinal manifestations consisted of severe vomiting, diarrhea, and crampy abdominal pain. Hypotension, tachycardia, and peripheral vasodilation constituted the main cardiovascular manifestations of the disease. Moderate azotemia and oliguria, presumed to be of prerenal origin, were present and rapidly resolved with administration of intravenous fluids. Hematologic manifestations consisted of leukocytosis with a left shift, thrombocytopenia, prolonged partial thromboplastin time, increased fibrin degradation products, and positive protamine sulfate test. The observed coagulation abnormalities may suggest intravascular coagulation. C3, C4, and total hemolytic complement were reduced, suggesting possible activation of the complement system. Hyperventilation, hypoxemia, pulmonary edema, obstructive, and restrictive pulmonary function abnormalities and bilateral pleural effusions highlighted the pulmonary manifestations of the disease. Rhadbomyolysis and mild hepatic function abnormalities were also present. All observed abnormalities reversed in a few days with no significant sequelae.

Adult↗
PubMed1981

Cardenolide analogues. 11. Improved method for the use of Fétizon's reagent in the synthesis of cardiac glycosides.

An improved procedure has been developed for preparing glycosides of cardenolide genins. The method uses specially prepared Fétizon's reagent as catalyst, combined, in most cases, with mercuric cyanide and mercuric bromide. In the presence of this catalyst, genins react readily, at room temperature, with per-acetylated 1-bromo-sugars to give the acetylated glycosides in high yield with little or no side reaction. The reaction proceeds almost to completion in 30 to 60 min. The free glycoside is obtained by mild deacetylation using triethylamine/methanol/water (20:20:1) at room temperature for 72 h. Proof of structure was obtained using chemical ionization mass spectrometry, NMR spectroscopy and comparison of physical constants with published data. The compounds were tested for inotropic activity using the isolated guinea pig atrium.

Animals↗
PubMed1981

Ineffectiveness of intravenous ascorbic acid as an acidifying agent in man.

The acidifying effect of intravenous (IV) ascorbic acid was studied in seven healthy adult volunteers. After obtaining baseline urine and blood samples, 2-g IV doses of ascorbic acid were administered to each subject during a 20-minute period. Venous blood samples were obtained at times 0.5, 1, and 2 hours, and urine was collected at times 0.5, 1, 2, and 3 hours. Our results show that venous blood pH, plasma bicarbonate concentration, urine PCO2, and urine bicarbonate excretion did not change significantly during the study period. Urinary titratable acidity, ammonium excretion, and net hydrogen ion excretion decreased, and urinary pH actually showed a significant rise at two hours. We therefore conclude that IV ascorbic acid administered in recommended doses does not effectively acidify urine.

Acid-Base Equilibrium↗
PubMed1980

A study of induced hyponatremia in the prevention and treatment of sickle-cell crisis.

Because the formation of sickle cells is dependent on the intracellular concentration of deoxyhemoglobin S, we investigated the possibility of altering or preventing sickle-cell crises by reducing serum sodium so as to cause red cells to swell. In three patients with sickle-cell anemia who had been disabled by recurrent painful crises, sustained dilutional hyponatremia was induced by 1-desamino-8-D-arginine vasopressin (DDAVP) in combination with a high fluid intake. Mean corpuscular hemoglobin concentration fell, and the degree of sickling at low partial oxygen pressure was reduced, as determined by morphologic criteria and by increased oxygen affinity of blood. Chronic hyponatremia (serum sodium, 120 to 125 mmol per liter) reduced the frequency of painful crises, whereas acutely induced hyponatremia abbreviated the duration of crises. These results, although preliminary, are encouraging enough to warrant further study of the safety and effectiveness of induced hyponatremia in the prevention and treatment of sickle-cell crises.

Adult↗
PubMed1980

Evaluation of the surgical management of Peyronie's disease.

Our experience in the management of patients with Peyronie's disease is reviewed. The cure rate with conservative treatment was insignificant and the results of dermal graft procedures were disappointing. Best results and sexual rehabilitation were achieved in patients treated with a penile prosthesis.

Adult↗
PubMed1980

The role of equipment having accidental or indirect contact with the carcase in the spread of Salmonella in an abattoir.

Counts of salmonellae were performed by the most probable number technique on steels, aprons, scabbards and on structures within the abattoir with which carcases made accidental contact. Counts on steels ranged from 0-153 salmonellae per steel; aprons from 0-14 per 100 cm2; scabbards from 0-greater than 3667 per scabbard; and carcase bump points from 0-40 per 100 cm2. Contamination rates were highest for the equipment of workers whose job functions brought them in contact with the hide.

Abattoirs↗