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Biomedical subjects

S A Norton

Publications and source records attributed to S A Norton.

10 recordsLinked to original sources
PubMed1992

Relationships between the thyroid and somatotropic axes in steers. I: Effects of propylthiouracil-induced hypothyroidism on growth hormone, thyroid stimulating hormone and insulin-like growth factor I.

The effects of propylthiouracil (PTU)-induced thyroid hormone imbalance on GH, TSH and IGF-I status in cattle were examined. In the first study, four crossbred steers (avg wt 350 kg) were fed a diet dressed with PTU (0, 1, 2 or 4 mg/kg/d BW) in a Latin square design with four 35-d periods. On day 29 in each period, steers were challenged with an intrajugular bolus of thyrotropin releasing hormone (TRH, 1.0 microgram/kg). Blood samples were obtained to assess the change in plasma GH and TSH as affected by PTU. Plasma IGF-I was measured from blood samples obtained before and after (every 6 hr for 24 hr) intramuscular injection of bovine GH (0.1 mg/kg, day 31). Doses of 1 and 2 mg/kg PTU increased plasma T4 (P < .01). At 4 mg/kg, PTU depressed T4 concentrations to 30% of control (P < .01). Plasma T3 linearly decreased with increasing doses of PTU (P < .01). Plasma TSH increased when PTU was fed at 4 mg/kg (P < .05) while the TSH response to TRH declined with increasing PTU (P < .02). Neither basal nor TRH-stimulated plasma concentration of GH was affected by PTU; the IGF-I response to GH tended to increase at the 1 and 2 mg/kg PTU (P < .01). In a second study 24 crossbred steers were fed PTU (1.5 mg/kg) for 119 d in a 2 x 2 factorial design with implantation of the steroid growth effector, Synovex-S (200 mg progesterone + 20 mg estradiol), as the other main effect. Basal plasma GH and IGF-I were not affected by PTU treatment. Synovex increased plasma concentration (P < .01) of IGF-I without an effect on plasma GH. The data suggest that mild changes in thyroid status associated with PTU affects regulation of T3, T4 and TSH more than GH or IGF-I in steers.

Animals↗
PubMed1992

Influence of thyroid status regulation and Synovex-S implants on growth performance and tissue gain in beef steers.

The separate and combined effects of Synovex-S (SYN) ear implants and thyroxine (T4)-5'-monodeiodinase inhibition (Trial 1) and T3 injection to create a mild elevation in circulating T3 concentrations (Trial 2) on BW gain and composition of gain were studied. Trial 1 used 24, 285-kg Angus steers in two experimental phases. Low-level feeding of propylthiouracil (PTU, 1.5 mg/kg BW daily) was used to achieve inhibition of T4-5'-monodeiodinase activity (TMA). Twelve steers received neither treatment (control) and 12 received SYN+PTU (hypothesized to maximize weight gain) from 0 to 56 d (phase 1) in a single factor treatment comparison. Subsequently, PTU was fed to six control steers and not fed to six of the original SYN+PTU steers from 56 to 175 d (phase 2) in a 2 x 2 arrangement of treatments. Trial 2 used 24, 302-kg Angus-Hereford steers. Treatments were without or with SYN and without or with sc injections of T3 in polyethylene glycol (2 micrograms/kg BW every 48 hr) in a 2 x 2 factorial arrangement of treatments. In both trials, all steers were individually fed a diet of a corn-based concentrate and silage mixture at an equal metabolizable energy intakes per unit of metabolic body weight (.25 Mcal/kg BW.75). Measurements of daily dry matter intakes, weekly BW, 28-d estimates of empty body components (measured by urea dilution), final TMA (trial 1) and plasma thyroid hormone concentrations were obtained. In both trials, SYN increased BW gain and protein accretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cutaneous leishmaniasis acquired during military service in the Middle East.

BACKGROUND: Cutaneous leishmaniasis is endemic in much of the Middle East. Personnel from more than 55 nations are currently participating in Middle East peacekeeping and military activities. OBSERVATIONS: Twenty-three Fijian members of a military observational force in Sinai, Egypt, acquired cutaneous leishmaniasis. They were treated successfully with 1-month courses of ketoconazole. CONCLUSIONS: Soldiers who acquire cutaneous leishmaniasis may return home to nations where cutaneous leishmaniasis is unknown or rarely diagnosed. Cutaneous leishmaniasis, caused by Leishmania major, may be treated with ketoconazole rather than antimonials.

Adult↗
PubMed1991

Scar sarcoidosis in pseudofolliculitis barbae.

A man with hilar adenopathy had smooth firm purplish papules (lupus pernio) on his face and pseudofolliculitis barbae (PFB) in his beard area. Biopsies of papules of both the lupus pernio and the PFB revealed non-caseating granulomas consistent with sarcoidosis. This is the first case report of sarcoidosis infiltrating lesions of PFB and the first of lupus pernio co-existing with scar sarcoidosis. In persons with suspected sarcoidosis, enlarged lesions of PFB are sites suitable for confirmatory biopsy. In addition, persons who develop keloid-like papules within their PFB may be providing an early cutaneous clue to undiagnosed systemic sarcoidosis.

Adult↗
PubMed1990

Evidence that bovine growth hormone treatment increases the rate of extrathyroidal 5'-monodeiodinase activity in cattle.

This study examined the influence of bovine growth hormone (bGH) on liver and kidney thyroxine-5'-monodeiodinase activity (TMA) in growing beef cattle. In a preliminary trial (trial 1), tissue samples were obtained at slaughter from two placebo-injected and two bGH-injected (29.2 IU/day for 14 days before slaughter) Hereford heifers (398 kg avg slaughter wt), with one heifer on each treatment fed at either 1.0 or 2.0 times maintenance energy requirement. In a second trial, tissue and plasma samples were obtained from six placebo-injected and six bGH-injected (29.2 IU/day for 19 days) Hereford steers (331 kg avg slaughter wt) fed at 1.8 times maintenance energy requirement. In a third trial, liver tissue and plasma samples were obtained from 14 Angus X Hereford steers (270 kg avg wt) fed either an 8% protein, 1.96 Mcal-metabolizable energy/kg diet (8 steers) or a 14% protein, 2.67 Mcal-metabolizable energy/kg diet (6 steers) in association with acute administration of bGH. Half the steers in each group were given two injections per steer of either placebo or 37.8 IU bGH at 24-hr intervals and slaughtered 24 hr after the second injection. Units of tissue TMA in all trials were measured at slaughter; one unit defined as 1 ng T3 generated/hr/mg protein during incubation with T4 (1.3 fM). In trial 1, TMA in liver and kidney was 2.86 and 1.21 times greater, respectively, for bGH than for placebo treatments. In trial 2, units of TMA in liver homogenates were higher (P less than .05) for bGH (4.14) than for placebo (2.83) treatments and higher (P less than .02) in liver microsomal preparations for bGH (32.7) than for placebo (27.3) treatments. Units of TMA in kidney homogenates were also higher (P less than .10) for bGH (1.48) than for placebo (.87) treatments and higher (P less than .02) in kidney microsomal preparations for bGH (23.0) than for placebo (16.4) treatments. Following acute injection of bGH (trial 3), units of TMA in liver homogenates were higher (P less than .01) for bGH (2.5) than for placebo (1.8) treatments. Plasma T4 (70.0 vs 73.5 ng/ml) and T3 (1.08 vs 1.18 ng/ml) concentrations appeared slightly higher in bGH-treated steers (trial 2) and increased by 20 and .5 ng/ml, respectively, (P less than .01) within 6 to 12 h after acute injection of bGH (trial 3). Concurrently, plasma TSH concentration increased following acute GH injection (trial 3).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Insulin, growth hormone, glucose, and fatty acids in gilts selected for rapid vs. slow growth rate.

Twelve-hour plasma profiles of growth hormone (GH), insulin, glucose, and nonesterified free fatty acids (NEFA), as well as GH, insulin, and glucose responses to saline, glucose, arginine, and human pancreatic growth hormone-releasing factor (GRF) infusion were examined in 15 crossbred gilts, selected for rapid vs. slow growth. For experiment 1 GH and insulin patterns differed (P less than 0.05) between the rapid growth line (RGL) and slow growth line (SGL). Mean GH concentrations in SGL and RGL gilts were 4.1 and 3.2 ng/ml, respectively (P less than 0.05). Plasma GH profile area was greater (P less than 0.08) for SGL than RGL gilts. Glucose level, glucose area, and insulin level were higher (P less than 0.05) for RGL than SGL gilts. Plasma NEFA levels and area were greater (P less than 0.05) for SGL gilts. In experiment 2 responses of GH, insulin, and glucose to saline, glucose, arginine, and GRF infusions varied (P less than 0.05) between and within lines relative to control values. These results indicate that selection for growth rate results in concomitant changes in endocrine and metabolic status.

Aging↗
PubMed1989

Raw mung beans as a protein source for bred gilts.

A study involving 546 crossbred gilts from six seasons was conducted to evaluate raw mung beans as a partial replacement for soybean meal in diets for gilts during gestation. Gilts were randomly allotted to either a control sorghum grain-soybean meal diet or a diet in which a portion of the soybean meal was replaced with mung beans. In the first three seasons, gilts were fed diets in which the protein supplement was totally soybean meal or 89% mung beans (high level) and 11% soybean meal. In the last three seasons the level of mung beans in the supplemental protein was reduced to 61% mung beans with 39% soybean meal (moderate level). Feeding the high level of mung beans decreased (P less than .05) weight gain during gestation and reduced (P less than .05) weight loss during lactation compared with gilts fed the control diet or the moderate level of mung beans. Little difference was noted in litter size at birth, but litter size at 21 d for gilts fed moderate levels of mung beans was less (P less than .05) than for gilts fed the control diet or the high level of mung beans. Little difference was noted in survival rate to 21 or 42 d or individual and litter weights at birth and 21 d. Pig and litter weights at 42 d, however were reduced in gilts fed the high level of mung beans (P less than .05 and P less than .10, respectively) compared with the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1986

Use of injectable vitamin E and selenium-vitamin E emulsion in ewes and suckling lambs to prevent nutritional muscular dystrophy.

Forty-eight Blackbelly X Dorset, 27 Finnish, 26 Finnish X Dorset, 28 Rambouillet and 8 Dorset Suffolk-sired lambs were used in this experiment. Three weeks before lambing, one-half of the ewes received a selenium emulsion (Se-E) containing .05 mg selenium and 3.7 IU of vitamin E/kg body weight (BW). A 2 X 3 X 2 factorial arrangement was used; lambs from either treated or nontreated ewes were randomly assigned irrespective of breed to one of six treatment combinations consisting of 0 or .025 mg/kg BW selenium (Se) injected at birth or two .025 mg/kg BW Se injections, one at birth and one 2 to 3 wk later, and two levels of injectable Vitamin E (E; 0 and 100 IU) given at birth. Both lambs and ewes were provided access to 75% concentrate diets supplemented with Se and E at recommended NRC levels. Plasma activity of creatine phosphokinase (CPK) was highest at 1 d of age and exhibited decreases (P less than .001) over time. In lambs, the E injection tended to decrease plasma activity of CPK. Plasma glutathione peroxidase activity was lowest at 1 d of age and increased over the course of the experiment but was unaffected by treatments (P less than .05). Plasma tocopherol concentration decreased (P less than .01) with time, with E therapy tending to increase tocopherol concentration. Differences in mean plasma tocopherol concentrations among breeds were also observed (P less than .01). Selenium concentration increased over time and with the E injection (P less than .01). An interaction between ewe and lamb Se-E treatments also was observed (P less than .10), with nontreated lambs from nontreated ewes exhibiting lower Se concentrations than treated lambs from injected ewes. An increase in lamb plasma Se concentration was noted in response to Se-E treatments (P less than .001). In the ewes, plasma tocopherol concentration was lower while Se concentration was higher at 18 d than at 1 d postpartum (P less than .01 and P less than .001, respectively). Milk Se concentration was lower at 18 d than at 1 d (P less than .001) and was higher (P less than .10) in Se-E-treated ewes.

Animal Feed↗
PubMed1983

Environmental radon and cancer correlations in Maine.

The distribution of 222Rn has been measured in the sixteen counties of Maine, U.S.A. by liquid scintillation counting of water samples from more than two thousand public and private wells. Three hundred and fifty of these wells have been characterized for geology and hydrology. Airborne radon has been measured in seventy houses with grab samples and in eighteen houses for 5-7 days each with continuously recording diffusion-electrostatic radon detectors. Concentrations of radon in water ranged from 20 to 180,000 pCi/l. Granite areas yielded the highest average levels (mean = 22,100 pCi/l.; n = 136), with considerable intra-granite variation. Metasedimentary rocks yielded levels characteristic of the lithology for metamorphic grades ranging from chlorite to andalusite. Sillimanite and higher-grade rocks yielded higher 222Rn levels, probably due to the intrusion of uranium-bearing pegmatites in these terranes. Airborne 222Rn in homes ranged from 0.05 to 210 pCi/l. At the high end of this range, doses will exceed recommended industrial limits. In some homes only a small fraction of the airborne 222Rn was due to the water supply. Average 222Rn levels in domestic water supplies for each of the 16 counties, calculated by areally averaging rock types and their associated 222Rn levels, were found to be significantly correlated with rates for all cancers combined and rates for lung and reproductive cancers in the counties. Although numerous factors other than cancer induction by indoor daughter exposures may be responsible for the observed correlations, these have not been investigated in detail.

Air↗