Search PubMed⌕ Search

Biomedical subjects

S Alexander

Publications and source records attributed to S Alexander.

At least 217 records · Page 12Linked to original sources
PubMed1978

Retroperitoneal neurilemmoma.

The clinical and pathologic features of benign and malignant retroperitoneal neurilemmoma are reviewed, and the pertinence of this tumor to the urologist is stressed. Two additional case reports are added to the literature.

Female↗
PubMed1977

Mitral valve replacement with the modified University of Cape Town (UCT) prosthesis: clinical and hemodynamic results.

Mitral valve replacement with the modified University of Cape Town prosthesis was performed in 42 patients. In 35 the procedure was an isolated one, and the hospital mortality was 6%. The late survival rate was 60%, half of the late deaths being the result of thromboembolism or complications of anticoagulant therapy. The incidence of hemolysis was low, and hemodynamic results demonstrated improvement in cardiac index and lowering of pulmonary artery pressure, pulmonary artery wedge pressure, pulmonary arteriolar resistance, and transvalvular mean gradients. However, the calculated prosthetic valve orifice area was lower than the measured area. Because of complications of thromboembolism, the high incidence of late deaths, and high transvalvular gradients, this prosthetic valve is no longer used in patients requiring mitral valve replacement.

Adult↗
PubMed1977

The interaction of plant alkaloids with DNA. II. Berberinium chloride.

The interaction of berberinium chloride with DNA has been investigated using spectrophotometry, viscometric titrations with sonicated and closed circular superhelical DNA, and flow polarized fluorescence. The binding results for berberinium were found to fit the neighbor exclusion model. The two viscometric titrations and flow polarized fluorescence results exclusion model. The two viscometric titrations and flow polarized fluorescence results also indicated that berberinium binds to DNA by intercalation. Titration of sonicated DNA with berberinium produced viscosity increases which were less than those obtained with quinacrine and the titration of superhelical DNA indicated a significantly smaller unwinding angle for intercalation of berberinium than for quinacrine. These results can be interpreted in terms of a model in which (i) berberinium is partially intercalated into the double helix, or (ii) the alkaloid is more completely intercalated into the double helix, but causes bending of the helix due to the slight nonplanarity of the berberinium ring system, or (iii) a combination of (i) and (22).

Berberine↗
PubMed1977

Comparison of the curative antimalarial activities and toxicities of primaquine and its d and l isomers.

This investigation was undertaken to determine whether either d-primaquine or l-primaquine has sufficient advantage over primaquine to warrant evaluation for curative activity in human volunteers infected with Plasmodium vivax. It was found: (i) that the capacities of the isomers and the racemate to cure infections with Plasmodium cynomolgi in rhesus monkeys were essentially identical; (ii) that the subacute toxicities of the isomers and racemate for this monkey were qualitatively the same, but that l-primaquine was three to five times as toxic as d-primaquine and at least twice as toxic as primaquine; and (iii) that the acute single-dose toxicities of the isomers for mice were not only qualitatively different, but that the d isomer was at least four times as toxic as l-primaquine. Since previous appraisals of curative activity and tolerability of 8-aminoquinolines in rhesus monkeys have correlated well with appraisals in human volunteers, attention was focused on results acquired with these test subjects. The relevant evaluations showed that d-primaquine had a therapeutic index at least twice that of primaquine. If this advantage carries over to man, problems that now complicate routine use of primaquine might be obviated. Therefore, a critical comparison of d-primaquine and primaquine in human volunteers seems indicated.

Animals↗
PubMed1977

Radioimmunoassay of estriol-16-glucuronide.

A specific radioimmunoassay of estriol-16-glucuronide has been developed, using an antiserum obtained by immunization of rabbits against estriol-16-glucuronide-BSA. The assay does not require hydrolysis, extraction and purification, but only a dilution of the crude sample. This constitutes the main advantage of the precedure. Accuracy, precision and sensitivity of the method are similar to those reported for other radioimmunoassays of estriol. Its specificity is good for the measurement of estriol-16-glucuronide in urine and in amniotic fluid, but not in serum of pregnant women, which apparently contains material interfering with the radioimmunoassay, at dilutions of less than 1/100. A significant correlation was observed between estriol-16-glucuronide and total estriol in urine during pregnancy; however, the contribution of the glucuronide to the total increases as pregnancy progresses, rising from 50% for a total of 5 mg/24 h to 85% for a total of 50 mg/24 h. The present radioimmunoassay can be used as a quick and reliable method for the measurement of urinary estriol-16-glucuronide in high risk pregnancies.

Amniotic Fluid↗
PubMed1976

A critical look at incontinence radio-implants.

Indwelling electrical stimulation of the pelvic floor by a radio-implant benefits some cases of problem or recurrent urinary incontinence. It is not possible to predict success or failure with a given patient. The only worthwhile criterion for selection is the presence of contraction of pelvic floor musculature in response to voluntary effort or trial electrical stimulation. The results are not simply explained by postulating electrically induced closure of the urethra. There may be conscious enhancement of the urinary sphincter mechanism. Re-education of voluntary sphincter muscles by electrophysiotherapy may occur. Reflex inhibition of the detrusor may occur. The surgery involved in inserting an implant restores continence in some patients.

Electric Stimulation Therapy↗
PubMed1975

Decreased premature ventricular contractions through use of the relaxation response in patients with stable ischaemic heart-disease.

To determine whether decreased sympathetic-nervous-system activity achieved by the relaxation response could decrease premature ventricular contractions (P.V.C.s), eleven ambulatory patients with proven, stable ischaemic heart-disease and P.V.C.s were investigated. The patients, who were taking no medication for the P.V.C.s, were trained to elicit regularly the relaxation response through a non-cultic psychological technique. The frequency of the P.V.C.s was measured by computer analysis of Holter monitor tapes for 2 complete days before learning the technique, which was learned in approximately 5 minutes after the second day. Patients were instructed to evoke the response for 20 minutes twice daily thereafter. After 4 weeks, a reduced frequency of P.V.C.s was documented in eight of the eleven patients. This effect was especially striking during the sleeping hours and less so during the entire monitoring session. The relaxation response is a simple, no cost, non-pharmacological mechanism without side-effects which seemed to decrease the frequency of P.C.V.s in most patients with ischaemic heart-disease.

Aged↗
PubMed1975

Naproxen and aspirin in rheumatoid arthritis: a multicenter double-blind crossover comparison study.

One hundred nineteen adults with active definite or classical rheumatoid arthritis were studied in a multicenter double-blind crossover study of naproxen (500 mg/day) and aspirin (3.6 Gm/day). Each drug was given in sequence for a six-week study period. Patients already receiving corticosteriod and/or gold therapy were maintained at constant dose throughout the study, but analgesics and other nonsteroidal antiinflammatory agents were discontinued at baseline. Objective and subjective evaluations by both investigator and patient were carried out at two-week intervals. No significant difference in global evaluation of efficacy or individual measures of efficacy was observed between aspirin and naproxen therapy, although physicians' global evaluation tended to favor naproxen. Sedimentation rate was lower on aspirin (naproxen 43.1 mm/hr; aspirin 38.7 mm/hr; P=0.02). Naproxen, 250 mg twice daily, was significantly better tolerated than aspirin, 900 mg four times daily. Mild, moderate, and severe side effects were less frequent with naproxen. The incidence of heartburn was significantly lower on naproxen, and significantly fewer patients terminated their six-week study period on naproxen than on aspirin. There were no significant deviations from baseline values in hematocrit, white cell or differential counts, or in tests of renal and hepatic function during the course of the study.

Anti-Inflammatory Agents↗