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Biomedical subjects

R Stevens

Publications and source records attributed to R Stevens.

At least 181 records · Page 10Linked to original sources
PubMed1982

Modulation of food intake by hypothalamic implants of estradiol benzoate, estrone, estriol and CI-628 in female rats.

ovariectomised rats were implanted unilaterally with cannulae aimed at the ventromedial nucleus-arcuate region of the hypothalamus. Crystalline implants of estradiol benzoate and of the antiestrogenic compound CI-628 over a 72-hour stimulation period caused significantly greater food intake reductions than did implants of cholesterol. More dorsal and lateral placements were generally ineffective in reducing food intake. Implants of estrone and estriol produced equivalent reductions in food intake and body weight to those produced by estradiol benzoate. The possible molecular mode of action is discussed.

Animals↗
PubMed1981

Canine blastomycosis: a review of 47 clinical cases.

In a limited retrospective survey, canine blastomycosis was found to be a disease affecting predominantly young, male dogs of the larger breeds. Clinical signs usually related to weight loss and to respiratory and ocular problems. The agar-gel immunodiffusion test was helpful in establishing a diagnosis. The diagnosis was confirmed by microscopic evaluation of aspiration or excision biopsies. Of 22 dogs treated with amphotericin B, 18 were clinically normal 6 months after initiation of therapy.

Animals↗
PubMed1980

Anti-tetanus toxoid antibody synthesis after booster immunization in systemic lupus erythematosus. Comparison of the in vitro and in vivo responses.

The in vivo and in vitro synthesis of anti-tetanus toxoid antibody (anti-tet) was measured after booster immunization with tetanus toxoid in 9 patients with systemic lupus erythematosus (SLE) and 9 controls. In vitro culture of peripheral blood lymphocytes (PBL) from both patients and controls showed maximal anti-tet synthesis 7 days after booster immunization, and maximal serum titers occurred by day 14. The initial in vitro burst of anti-tet synthesis was not dependent upon pokeweed mitogen (PWM) stimulation, whereas later synthesis was PWM dependent. Two differences between patients and controls were observed: 1) patients with SLE had a lower mean pre-boost serum titer of anti-tet, and 2) one-third of the patients showed a blunted serum anti-tet response. To study whether these abnormalities were a result of altered immune regulation, anti-tet synthesis was measured by the coculture of separated SLE-B or control-B cells and separated SLE-T or control-T cell populations (+/- irradiation to remove suppressor T cell activity). These coculture studies showed that both abnormalities were due to a lack of SLE-B cell response, not to abnormalities of SLE-helper T or SLE-suppressor T cell function.

Adult↗
PubMed1980

New method for large-scale growth; and concentration of the Epstein-Barr viruses.

Efficacious systems are described for the large-scale growth in tissue culture and concentration of infectious (P3HR-1) and transforming (B95-8) Epstein-Barr virus. Also recorded here are our updated procedures for growing stock cultures and protocols to harvest fluids containing biologically active virus which is infectious or transforming. Various methods of concentrating biologically active Epstein-Barr virus have been evaluated. Cellular debris can be removed efficiently and rapidly from culture harvest fluids by clarification through a JCF-Z continuous-flow rotor. Efficient and reliable virus concentration was achieved by molecular filtration with Millipore Pellicon cassettes, using flow rates to 10 liters/h to produce fivefold concentrates followed by pelletization in a fixed-angle rotor. Data from recent production lots showed an average infectivity titer for P3HR-1 virus of 10(4.5) early antigen units per ml (100-fold concentrate) and 10(5.7) transforming units per ml (200-fold concentrate) for B95-9 virus lots.

Animals↗
PubMed1979

Unmyelinated axons in the trigeminal motor root of human and cat.

The fiber composition of the human and cat trigeminal "motor roots" were studied utilizing the electron microscope. Twelve to twenty percent of fibers in the human trigeminal motor root are unmyelinated whereas 9-15% are unmyelinated in the cat. The only previous examination of the fiber composition of the peripheral trigeminal motor nerve utilized the light microscope and indicated that less than 5% of fibers were unmyelinated in cat. No study of the fiber composition of the motor nerve root is available. The present results are similar to those recently obtained by others for spinal ventral roots. The function of unmyelinated fibers in the trigeminal "motor root" is unknown, however indirect evidence, both laboratory and clinical, suggests a potential sensory function for them. The findings question seriously the concept that the functional separation of the nervous system into motor and sensory systems has anatomical correlates in the spinal and cranial nerve roots. The results relate directly to our conceptualization of the nervous system and also to the design of methods for the treatment of intractable pain.

Animals↗
PubMed1978

The sources of rat biliary cholesterol and bile acid.

The precursor sources of bile acid and bile neutral sterol were evaluated in the rat using Triparanol to inhibit the terminal reduction in the synthesis of cholesterol. During the initial period of Triparanol administration, the accumulation of hepatic desmosterol acts to segregate relatively newly synthetic hepatic sterol from the bulk of the equilibrated sterol mass. Biliary excretion of newly synthetic sterol can then be determined in acute studies, assuming no great differences between desmosterol and cholesterol as precursors of biliary neutral sterol or bile acid. It has been determined in this model that newly synthetic sterol comprises a mean of about 28% of the total biliary neutral sterol output. This fraction fell when hepatic cholesterogenesis was suppressed by prior cholesterol feeding. By using this approach in conjunction with the administration of labeled mevalonate to a renal pedicle-ligated rat, it was possible to calculate the amount of bile acid produced from either newly synthesized sterol or the equilibrated sterol pool. It has been estimated that the bulk of bile acid synthesis arises from this equilibrated source when these determinations were made within two hours of creating the fistula. With more prolonged fistula times, more of the bile acid originated from the newly synthesized sterol.

Animals↗