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Biomedical subjects

J McMurtry

Publications and source records attributed to J McMurtry.

10 recordsLinked to original sources
PubMed2005

Effects of lysine deficiencies on plasma levels of thyroid hormones, insulin-like growth factors I and II, liver and body weights, and feed intake in growing chickens.

Adequate (1.10%) and deficient (0.88, 0.66, and 0.53%) levels of Lys were fed to broiler chicks from 9 to 23 d of age. Groups fed the control diet (1.10% Lys) were also pair-fed daily with each deficient group. Compared with the free-fed control, graded decreases in feed intake occurred as the deficiency worsened, and these were significantly different with 0.66 and 0.53% Lys. Growth decreased significantly with each deficient level of Lys compared with the free-fed control and was always significantly lower than in the pair-fed control groups in each set. Plasma triiodothyronine (T3) was elevated in chicks fed 0.88 and 0.66% lysine but not with 0.53% when compared with the full-fed control treatment. However, in deficient chicks receiving 0.66 and 0.53% Lys, T3 levels were significantly higher compared with their pair-fed controls. Plasma T4 was not significantly different between any treatments. Liver weights decreased significantly at each level of Lys deficiency, but most of the differences disappeared when expressed relative to body weight. Plasma insulin-like growth factor (IGF)-I decreased significantly with the most severe Lys deficiency. However, it decreased to a similar degree in the pair-fed controls, showing that this effect was primarily due to the lower feed intake. Plasma IGF-II levels did not differ between any treatments. No correlations were evident between thyroid hormones and IGF-I or IGF-II values. We concluded that the primary effect of Lys deficiency was an elevation in plasma T3 levels without accompanying changes in plasma T4. No effect of the Lys deficiency per se on plasma IGF-I and IGF-II and liver weights relative to body weights was found.

Animals↗
PubMed1998

Insulin-like growth factor-1 is a radial cell-associated neurotrophin that promotes neuronal recruitment from the adult songbird edpendyma/subependyma.

In the adult songbird forebrain, neurons continue to be produced from precursor cells in the forebrain ependymal/subependymal zone (SZ), from which they migrate upon radial guide fibers. The new neurons and their radial cell partners may coderive from a common SZ progenitor, which may be the radial cell itself. On this basis, we asked whether radial cells might provide trophic support for the migration or survival of newly generated neurons. We focused upon the insulin-like growth factors (IGFs) IGF-1 and IGF-2, which have previously been shown to support the survival and differentiation of neural progenitor cells. We found that IGF-1 immunoreactivity was expressed heavily by adult zebra finch radial cells and their fibers, with little expression otherwise. IGF-2, in contrast, was expressed by parenchymal astrocytes and exhibited little radial cell expression. Despite their distinct distributions, IGF-1 and IGF-2 exerted similar trophic effects on finch SZ cells in vitro; both greatly increased the number of neurons migrating from explants of the adult finch SZ, relative to explants raised in low-insulin, IGF-1-deficient media. However, neither factor extended neuronal survival. These results suggest that in neurogenic regions of the adult avian forebrain, IGF-1 acts as a radial cell-associated neuronal differentiation and/or departure factor, which may serve to regulate neuronal recruitment into the adult brain.

Animals↗
PubMed1991

Serum corticosterone concentrations in developing shell-less and shelled turkey embryos.

1. Turkey embryos grown in shell-less culture (EO) display normal development to day 14 of incubation, after which growth rate is reduced and mortality increases, compared to age-matched in ovo (IO) embryos (Richards 1982. Long term shell-less culture of turkey embryos. Poultry Sci. 61, 2089-2096). 2. In this study serum corticosterone concentrations were monitored in normally incubated embryos and embryos maintained in shell-less culture. 3. On days 14 and 16 of incubation, corticosterone levels were greater (P less than 0.05) in EO than IO embryos, whereas during the later stages corticosterone increased dramatically in the shelled embryos, and remained relatively constant in the EO embryos. 4. EO embryos do not exhibit a pattern of adrenal hormonal secretion that would indicated a stressful condition. 5. The absence of a normal increase in corticosterone in shell-less embryos may contribute to the abnormal embryological development in the later stages of incubation.

Animals↗
PubMed1989

Comparison between constant-protein, calorie-restricted and protein-restricted, calorie-restricted diets on growth, in vitro lipogenesis and plasma growth hormone, thyroxine, triiodothyronine and somatomedin-C (Sm-C) of young chickens.

1. We studied the effects of calorie-restricted, constant-protein and calorie-restricted, protein-restricted diets on growth and in vitro metabolism of male chickens from select (Cobb Line 500) and byproduct (Cobb female line) lines of broiler chickens. 2. Chickens consumed 40, 60, 80 or 100% of a prescribed formula for dietary energy (body weight in g0.70 x 16.7 kJ) in the presence of set (CEP) or varied dietary protein (VEP). 3. Chickens fed VEP were heavier (P less than 0.05) at all energy intakes than chickens fed CEP. Slope analysis of data for in vitro lipogenesis showed a significant difference between the two treatment series. 4. Plasma growth hormone was inversely related (P less than 0.05) to Sm-C. Growth hormone levels were greater in chickens on a low plane of energy nutrition (40%) than on the maximum plane (100%). 5. Plasma Sm-C levels (pooled across energy series) were greater in the select than in the byproduct line. There were no differences in plasma T3 between the two lines. There was a significant increase (P less than 0.05) in T3 and a decrease in the T4/T3 ratio accompanying an increase in dietary energy. 6. Restricting dietary carbohydrate and protein compromises anabolic processes more than restricting carbohydrate alone.

Animal Nutritional Physiological Phenomena↗
PubMed1989

Dietary propylthiouracil and 17 beta-estradiol benzoate implant effects on liver carbohydrate and lipid metabolism in chicks.

1. Forty-eight chicks (21 days old) were implanted (+/- 50 mg 17-beta estradiol; EBI) and fed diets containing +/- 0.1% propylthiouracil (PTU) for 7 days to determine the role of gonadal hormones in the regulation of energy metabolism in the hypothyroid chick. 2. In vitro lipogenesis (IVL) and glucose production (NGP) were measured in liver explants. 3. Liver glycogen (GLY) metabolism was studied in particulate fractions (50,000 x g) of liver. 4. Glycogen synthetase activity (GLYSYN) was assayed in the presence of glucose-6-phosphate (G-6P; 0, 0.15 and 10 mM) to determine activation states. 5. PTU and EBI increased (P less than 0.05) both GLY concentration and GLYSYN activity in chicks but, did not increase G-6P activity ratios or the in vitro activation of GLYSYN. 6. Both PTU and EBI increased (P less than 0.05) IVL and NGP. 7. Estradiol magnifies the effects of PTU in chicks suggesting an interaction between thyroid status and gonadal function.

Animals↗
PubMed1988

Neuropeptide Y: brain localization and central effects on plasma insulin levels in chicks.

A rich network of NPY-like immunoreactive fibers was found in the paraventricular nucleus and the ventromedial region of the hypothalamus juxtapositioned to the third ventricle, including the median eminence. Brain regions, areas or nuclei found densely innervated by NPY-like immunoreactive fibers included the olfactory bulb region, septal area, organum vasculosum of the lamina terminalis, preoptic periventricular nucleus, hypothalamic periventricular nucleus, medial suprachiasmatic nucleus, subseptal (subfornical) organ, ventromedial hypothalamic nucleus, infundibular nucleus and nucleus tractus solitarius. NPY-like containing perikarya were localized within the hippocampus, bed nucleus of the stria terminalis and surrounding the nucleus rotundus and nucleus of the basal optic root. Since the immunocytochemical study showed that NPY was localized in brain structures known to alter food intake and the compound is a member of the pancreatic polypeptide family, a second study was designed to determine if the neuropeptide altered plasma concentrations of insulin, glucagon and glucose following intracerebroventricular administration. It was found that NPY significantly increased plasma concentration of insulin. It is proposed that two reasons why NPY is such a potent orexigenic agent is that the paraventricular nucleus and structures surrounding the third ventricle throughout the ventromedial hypothalamic region show high levels of NPY-like immunoreactivity. Secondly, NPY effects an increase in plasma insulin in the periphery.

Animals↗
PubMed1987

Energy and protein relations in the broiler. 5. Lipogenesis, glucose production and metabolic hormone levels as functions of age and dietary protein levels.

Both a decrease in the dietary carbohydrate level and an increase in the protein level decrease lipogenesis in chicks. Interpreting results of previous experiments can be confounded by alterations in the quantity of carbohydrate because as protein was added to the diets used in these studies, carbohydrate was decreased. In the present study, diets containing 13, 16, 19 or 23% protein and 70% carbohydrate calories were fed to Ross male chicks from 1 to 4 weeks of age to determine the effect of dietary protein level (% crude protein) on growth and intermediary metabolism in 2, 3, and 4-wk old chicks. All treatment groups were limited to that amount of feed consumed by the 23% protein group. There were no significant differences in body weights among the treatment groups at 4 wk of age. An increase in dietary protein (23 vs. 13%) increased (P less than 0.05) in vitro glucose production by liver slices from 4-wk old chicks. In contrast, the same increase in dietary protein decreased (P less than 0.05) in vitro lipogenesis by liver slices from 2, 3, and 4-wk old chicks. The same increase in dietary protein increased (P less than 0.05) both insulin (INS) and thyroxine (T4) and decreased (P less than 0.05) triiodothyronine (T3). Serum T3 and T4 concentrations were less (P less than 0.05) and INS concentrations were greater (P less than 0.05) in 4-wk old chicks compared to 2-wk old chicks.

Aging↗
PubMed1983

Villous adenocarcinoma of the male urethra.

We report on 2 men with multifocal papillary adenocarcinoma arising in the bulbous urethra proximal to a urethral stricture. Histologically, the tumors appeared similar to villous adenocarcinomas of the colon and rectum. Both patients were treated with segmental urethrectomy. Villous adenocarcinoma of the male urethra is a distinctive clinicopathologic entity. Although uncommon it should be added to squamous cell carcinoma and transitional cell carcinoma on the list of tumor types causing cancer of the male urethra.

Adenocarcinoma↗