695 research outputs found

    Effects of prolactin and growth hormone on growth and metamorphosis of tadpoles of the frog, Rana pipiens

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    Mammalian prolactin at doses of 1-50 [mu]g/day promoted growth (increased wet weight, dry weight and body length) in Rana pipiens tadpoles. Mammalian growth hormone (GH) promoted growth only at the higher doses (50 [mu]g/day and above) and was not so effective as prolactin.Prolactin also inhibited metamorphosis (at doses of 5 [mu]g/day and above). Inhibition of metamorphosis did not appear to be due to reduction in tissue sensitivity to thyroxine since prolactin-treated tadpoles metamorphosed in response to exogenously administered thyroxine (4-100 [mu]g/liter) to the same extent as controls. Prolactin promoted further growth in tadpoles in which the thyroid level had been reduced with thiouracil or by thyroidectomy. This indicates that growth promotion caused by prolactin is not just the result of thyroid inhibition, although it is possible that a portion of the growth stimulation is due to the antithyroid action of prolactin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32919/1/0000301.pd

    Effects of hypophysectomy, prolactin, and growth hormone on growth of postmetamorphic frogs

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    Hypophysectomy of juvenile postmetamorphic frogs (Rana pipiens) reduced growth (wet weight and length) compared to sham hypophysectomized controls. Mammalian growth hormone at doses of 10-50 [mu]g/day promoted growth in intact frogs during a 2-month period. However, 5 [mu]g/day of GH for 1 month did not promote growth. Mammalian prolactin did not promote growth in postmetamorphic frogs over a 2-month period at doses between 5 and 50 [mu]g/day.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32921/1/0000303.pd

    Effects of prolactin and somatotropin on growth and metamorphosis of amphibians

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    Mammalian prolactin stimulates growth and inhibits metamorphosis of larvae of several species of amphibians. Mammalian somatotropin has little or no effect upon larval growth or metamorphosis unless used in high concentrations. The evidence behind these statements and some of the implications are critically evaluated. Growth of postmetamorphic amphibians is stimulated by somatotropin but not by prolactin. The possible biological significance of this apparent transition from prolactin to somatotropin regulation of growth in the pre- and postmetamorphic stages of development is discussed in terms of possible mechanisms involved in the transition, and in terms of the adaptive significance of the change.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34198/1/0000487.pd

    Better Health While You Wait: A Controlled Trial of a Computer-Based Intervention for Screening and Health Promotion in the Emergency Department

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    Study objective: We evaluate a computer-based intervention for screening and health promotion in the emergency department and determine its effect on patient recall of health advice. Methods: This controlled clinical trial, with alternating assignment of patients to a computer intervention (prevention group) or usual care, was conducted in a university hospital ED. The study group consisted of 542 adult patients with nonurgent conditions. The study intervention was a self-administered computer survey generating individualized health information. Outcome measures were (1) patient willingness to take a computerized health risk assessment, (2) disclosure of behavioral risk factors, (3) requests for health information, and (4) remembered health advice. Results: Eighty-nine percent (470/542) of eligible patients participated. Ninety percent were black. Eighty-five percent (210/248) of patients in the prevention group disclosed 1 or more major behavioral risk factors including current smoking (79/248; 32%), untreated hypertension (28/248; 13%), problem drinking (46/248; 19%), use of street drugs (33/248; 13%), major depression (87/248; 35%), unsafe sexual behavior (84/248; 33%), and several other injury-prone behaviors. Ninety-five percent of patients in the prevention group requested health information. On follow-up at 1 week, 62% (133/216) of the prevention group patients compared with 27% (48/180) of the control subjects remembered receiving advice on what they could do to improve their health (relative risk 2.3, 95% confidence interval 1.77 to 3.01). Conclusion: Using a self-administered computer-based health risk assessment, the majority of patients in our urban ED disclosed important health risks and requested information. They were more likely than a control group to remember receiving advice on what they could do to improve their health. Computer methodology may enable physicians to use patient waiting time for health promotion and to target at-risk patients for specific interventions

    Effects of hypophysectomy and thyroidectomy on salt balance in the plethodontid salamanders, Desmognathus fuscus and Desmognathus monticola

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    Hypophysectomy significantly reduced serum sodium levels in Desmognathus fuscus and D. monticola . Prolactin, corticosterone or aldosterone replacement failed to restore serum sodium to control levels. Hypophysectomy also led to decreases in in vitro integumental potential difference and shortcircuit current, which were not restored to control levels by prolactin or corticosterone. Thyroidectomy significantly reduced the level of serum sodium in D. monticola , but it increased in vitro potential difference and short-circuit current. Thyroxine treatment of either hypophysectomized or thyroidectomized D. monticola completely restored serum sodium, potential difference and short-circuite current to control levels.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47122/1/360_2004_Article_BF00799050.pd

    Fungal Origins of the Bicyclo[2.2.2]diazaoctane Ring System of Prenylated Indole Alkaloids

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    Over eight different families of natural products, consisting of nearly seventy secondary metabolites, which contain the bicyclo[2.2.2]diazaoctane ring system, have been isolated from various Aspergillus, Penicillium, and Malbranchea species. Since 1968, these secondary metabolites have been the focus of numerous biogenetic, synthetic, taxonomic, and biological studies, and, as such, have made a lasting impact across multiple scientific disciplines. This review covers the isolation, biosynthesis, and biological activity of these unique secondary metabolites containing the bridging bicyclo[2.2.2]diazaoctane ring system. Furthermore, the diverse fungal origin of these natural products is closely examined and, in many cases, updated to reflect the currently accepted fungal taxonomy
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