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Biomedical subjects

S L Davis

Publications and source records attributed to S L Davis.

At least 73 records · Page 4Linked to original sources
PubMed1984

Serial evoked potential studies in patients with definite multiple sclerosis. Clinical relevance.

Twelve patients with clinically definite multiple sclerosis were examined both clinically and electrophysiologically at repeated intervals over one year to determine the clinical relevance of data obtained by serial multimodality evoked potential studies. We frequently found a disparity between the clinical and electrophysiologic changes, and also an excessive variability between test sessions of the responses to stimulation of a clinically involved afferent pathway even when the clinical deficit was stable. Our findings indicate that though evoked potential studies may provide information of diagnostic relevance, their role in monitoring disease progression has not been established.

Adult↗
PubMed1983

Treatment of small cell lung cancer with VP-16, vincristine, doxorubicin (Adriamycin), cyclophosphamide (EVAC), and high-dose chest radiotherapy.

Seventy-one previously untreated patients with small cell lung cancer (SCLC) received a combination of VP-16, vincristine, doxorubicin (Adriamycin), and cyclophosphamide (EVAC) repeated every three weeks. Limited-disease (LD) patients and extensive-disease (ED) patients achieving a complete response (CR) or partial response (PR) after four to six cycles of EVAC received 4,000 rads over four weeks whole-brain radiotherapy (RT) and 5,000 rads over five weeks RT to the original pulmonary primary and mediastinum. ED patients with persisting disease outside the chest after six cycles of EVAC continued chemotherapy and did not receive RT. After RT was completed, EVAC was continued for a total treatment duration of 24 months. Of 65 patients evaluable for response 76% (25 of 33) of LD patients and 34% (11 of 32) of ED patients achieved a CR prior to RT; two additional ED patients achieved a CR after RT. Median survival for all 71 patients was 48 weeks (range, one to 207 weeks); median survival for 33 LD patients was 92 weeks and for 38 ED patients it was 36 weeks. Nine of 25 LD patients and 10 of 13 ED patients have relapsed from CR. The EVAC-RT protocol is promising in view of the high CR rate and long remission duration achieved, especially among patients with LD.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1983

Temporal patterns of growth hormone, prolactin and thyrotropin secretion in Targhee rams selected for rate and efficiency of gain.

Thirteen Targhee rams selected for rate and efficiency of gain for 4 yr (1.5 generations) were compared with 10 rams from a Targhee line with no selection for over 20 yr to determine if selection for these traits would be associated with changes in the secretion of growth hormone (GH), thyrotropin (TSH) and(or) prolactin (PRL). Selected rams exhibited greater birth weight, average daily gain (ADG) and feed consumed/day during a 6-wk individual feeding regimen, and exhibited greater overall ADG during a 16-wk feeding trial as compared with the unselected rams. Temporal blood plasma samples were collected at 15-min intervals for 8 h from each of the 23 rams for hormone analysis. Selected rams exhibited greater overall mean GH (6.1 +/- .4 vs 4.6 +/- .5 ng/ml), overall mean TSH (8.6 +/- 1.2 vs 6.2 +/- .7 ng/ml) and baseline mean TSH (8.0 +/- 1.1 vs 5.6 +/- .5 ng/ml) than the unselected rams. Although the adjusted GH spike amplitude value was higher in the selected line (12.1 +/- 3.0 vs 7.4 +/- .8 ng/ml), this difference was not significant. No differences were observed with any of the variables of PRL secretion. In addition, there were no significant correlations between any of the hormone variables and any of the feed or gain data. These data support the hypothesis that Targhee rams selected for rate and efficiency of gain exhibit higher plasma levels of GH and TSH than unselected rams of the same breed.

Animals↗
PubMed1983

Continuous elevation of blood growth hormone concentrations by beeswax implant.

We examined constancy of release of purified ovine growth hormone from an implant containing soybean oil and beeswax. Implants contained an amount of growth hormone that was sufficient to increase concentrations in blood plasma by 20 and 40 ng/ml and to maintain those concentrations over 1 wk. Growth hormone in plasma increased to approximately 65 ng/ml in lambs receiving low dose implants the 1st day after implantation, returned to 31 ng/ml on day 2, and remained near this concentration for the remainder of the week. Pulse release of growth hormone was not similiar in the high dose lambs where growth hormone concentration in plasma averaged 45 ng/ml 1 day after implantation, then gradually increased to 60 ng/ml on day 6. Unimplanted control lambs had mean growth hormone concentrations of 2.9 to 3.9 ng/ml throughout the 6-day observation. This approach should interest investigators studying the chronic influence of purified or synthetic growth hormone on dairy cows, beef steers, or lambs.

Animals↗
PubMed1981

Hypothalamic control of endocrine thermogenesis.

Hypothalamic and ruminal cooling raised serum thyrotropin (TSH), adrenocorticotropin (ACTH), norepinephrine (NE), and glucose in conscious goats in 20 degree C ambient temperature. Cooling of the preoptic anterior hypothalamus (POAH) for 2 h initially evoked shivering and vasoconstriction, leading to 1.5 degree C rise in rectal temperature (Tr). Pituitary-thyroid activation by POAH cooling was shown by peak rises in TSH of 60% at 40 min, in triiodothyronine (T3) of 54% at 80 min, and in thyroxine (T4) of 40% at 140 min. At 60 min, ACTH and NE peaked at 57 and 65%, respectively. TSH, ACTH, and NE declined during the 2nd h of POAH cooling as Tr plateaued; when POAH cooling was stopped, these hormones fell below basal level as vasodilation and panting restored Tr to normal. In contrast to the core hyperthermia evoked by POAH cooling, ruminal intubation with O degree C water (1 liter/10 kg) led to general hypothermia, Tpoah and Tr falling 1.6 degree C at 40 min. Pituitary-thyroid responses were less but ACTH and NE more, compared with POAH cooling. TSH peaked at 37% at 20 min, T3 at 55% at 60 min, and T4 at 18% at 200 min. ACTH peaked at 250% at 30 min and NE at 120% at 20 min. Thermosensitive neurons in the POAH seem to mediate more sensitive and complete control over TSH than over ACTH, or NE release, whereas extrahypothalamic core thermosensitivity (e.g., brain stem, spinal cord, abdomen) may influence ACTH and NE more than TSH release.

Adrenocorticotropic Hormone↗
PubMed1981

Use of active immunization against prolactin to study the influence of prolactin on growth and reproduction in the ram.

An experiment was conducted to determine whether prolactin (PRL) is involved in the maintenance of reproductive tissue weights and body growth in yearling rams. Suppression of circulating PRL was achieved by active antibody production against bovine PRL. Free plasma PRL concentrations in immunized rams were decreased (P less than .05) by 73% after 3 months of treatment and 91% after 10 months of treatment in relation to concentrations in control rams. Average daily gain and final body weight were lower (P less than .05) for rams with suppressed circulating PRL (.042 kg/day and 67.0 kg for treatment rams and .060 kg/day and 72.7 kg for control rams). Although testes weights were 32% lower for the treated rams, antibody treatment did not affect (P greater than .05) the weights of the testes or accessory sex glands. No treatment effect was noted on plasma luteinizing hormone (LH), growth hormone (GH) or thyrotropin (TSH). Seasonal differences were observed in some variables of LH, GH and TSH secretion. Mean baseline LH for all animals was higher (P less than .01) in December than in March, June or September. Overall and baseline concentration of GH and TSh were highest (P less than .01) in December. These data suggest that (1) PRL is involved in body growth of the yearling ram, and (2) PRL may have a role in the maintenance of reproductive tissue weights in the yearling ram.

Animals↗
PubMed1981

Plasma growth hormone, prolactin and thyrotropin secretory patterns in Hereford and Simmental calves.

An experiment was conducted to test the hypothesis that bull calves of a larger, faster growing breed of cattle exhibit greater secretory activity of anabolic pituitary hormones than bull calves of a smaller, slower growing breed. Calves of both breeds were raised under similar conditions and maintained on the same diet for approximately 4 weeks before the blood sampling period. Simmental bull calves had higher (P less than .01) average daily gains and a heavier (P less than .01) mean body weight than Hereford bull calves. Overall plasma growth hormone (GH) concentrations were higher (P less than .01) in Simmental bull calves than in Hereford bull calves. Mean baseline GH was also higher (P less than .05) in Simmentals. Overall and baseline concentrations of prolactin (PRL) were similar for both breeds. Mean amplitude of PRL secretory spikes was higher (P less than .05) for Simmental than for Hereford bull calves. There was no breed effect on any variable of thyrotropin secretion. These data suggest that representatives of a larger, faster growing breed of cattle (Simmental) exhibit greater secretory activity of GH and PRL than do representatives of a smaller, slower growing breed (Hereford).

Animals↗
PubMed1980

Prediction of outcome in metastatic breast cancer treated with adriamycin combination chemotherapy.

Univariate and multivariate regression methods were used to analyze 17 potential clinical prognostic factors among 138 patients with advanced breast cancer who received Adriamycin-cyclophosphamide combination chemotherapy between 1973 and 1977 at the University of Arizona. Follow-up of patients was through September 1979, and survival data were nearly complete. Different factors varied in the relationship to outcome, but age, treatment, and response were important. Selecting the three most strongly related factors, predictive regression equations were developed, which described three types of possible outcome: 1) objective response (age, treatment, and liver involvement), 2) freedom from relapse (age, lung involvement, and response), and 3) survival (age, the number of involved sites [less than or equal to 2 or > 2], and treatment). Since use of the regression equations is cumbersome for clinical practice, three simplified tables were constructed to readily predict response, duration of response, and survival before the initiation of treatment.

Adult↗
PubMed1979

Comparison of luteinizing hormone and prolactin levels in cycling and anestrous ewes.

Concentrations of luteinizing hormone (LH) and prolactin (Prl) in the serum of anestrous and cycling ewes were compared. The concentration of LH in serum and the frequency of episodic releases of LH were lower in anestrous than in cycling ewes. Concentrations of LH in serum rose as rapidly after ovariectomy of anestrous ewes as after ovariectomy of cycling ewes. Prl levels were higher during anestrus than at any stage of the estrous cycle; however, high Prl levels were not necessarily associated either with low LH levels or the absence of episodic release of LH. These data suggest: (1) that anestrus is not due to a reduction in the intrinsic ability of the hypothalamo-hypophyseal system to secrete LH, and (2) that high Prl levels may be a symptom rather than a cause of seasonal anestrus.

Animals↗