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Biomedical subjects

C G Smith

Publications and source records attributed to C G Smith.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

The role of endogenous opioid peptides in the control of androgen levels in the male nonhuman primate.

Plasma androgen levels studied following the injection of the opioid agonists morphine sulfate (0.5-1.0 mg/kg), beta-endorphin (10-20 mg/kg), and [D-Ala2, D-Leu5]-enkephalin (DADLE; 5-20 micrograms/kg), and the opioid receptor antagonist naloxone (0.5-2.0 mg/kg) in nonrestrained adult male rhesus monkeys. Drugs were administered and blood samples were collected through indwelling jugular catheters. Morphine (1.0 mg/kg) and DADLE (10.0 micrograms/kg) decreased androgen levels by 70% and 34%, respectively. Significant decreases occurred 80 minutes after drug injections, and levels remained depressed for 180 minutes; beta-endorphin (20 micrograms/kg) produced no effect on androgen levels. Treatment with naloxone (0.5 mg/kg-2.0 mg/kg) alone produced marked increases in androgen levels. Peak hormone levels occurred 80 minutes after naloxone administration and remained elevated for up to 2 hours. The depressant effects of morphine and DADLE on androgen levels were completely reversed by the administration of naloxone (1.0 mg/kg). In monkeys pretreated with hCG, neither morphine (1.0 mg/kg) nor DADLE (20 micrograms-kg) had any effect on androgen levels for up to 3 hours after opioid administration. Administration of morphine or endogenous opioid peptides exerts negative effects on androgen levels, whereas antagonism or endogenous or exogenous opiates by naloxone results in increases in circulating androgens. These results support a physiologic role of the endogenous opioid peptides in primate reproductive function.

Androgens↗
PubMedDate not supplied

Tropical ulcer.

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Humans↗
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Ultrastructural localisation and further biochemical characterisation of prolyl 4-hydroxylase from Phaseolus vulgaris: comparative analysis.

Prolyl 4-hydroxylase (EC 1.14.11.2), the enzyme responsible for the post-translational hydroxylation of peptide proline, has been well described in animals but has been little studied in plants. The best characterised example is the enzyme from French bean (Phaseolus vulgaris). In this study, the biochemical properties of this plant enzyme were examined in more detail and, using specific polyclonal antibodies, the localisation of the enzyme was determined. Both alpha- and beta-subunits did not show multiple forms, suggesting a relatively broad specificity of the enzyme complex with respect to the target hydroxylated amino acid sequences. Antibodies to the mammalian and Chlamydomonas enzymes cross-react with the higher plant subunits, indicating that some epitopes are highly conserved. The P. vulgaris enzyme was inhibited by analogues of oxoglutarate, but was not susceptible to doxorubicin. Inhibition of the bean enzyme by an oxaloglycine derivative resulted in the retention of the target (hydroxy)proline-rich protein in the endomembrane system. Immunolocalisation of the enzyme showed close association with the endoplasmic reticulum and Golgi apparatus in root tip cells of P. vulgaris or Tropaeolum majus. This localisation was particularly pronounced in Golgi-associated vesicles of young root tip cells of T. majus, cell types where rapid synthesis and deposition of wall material was observed. These data are consistent with the hypothesis, proposed by Bolwell [G.P. Bolwell, Dynamic aspects of the plant extracellular matrix, Int. Rev. Cytol. 146 (1993) 261-324], that protein hydroxylation must be completed before the glycosylation of the target (hydroxy)proline-rich glycoproteins in the Golgi stack.

Blotting, Western↗
PubMedDate not supplied

Herpes zoster in childhood: case report and review of the literature.

Herpes zoster in childhood is uncommon even in the setting of known risk factors such as primary varicella zoster infection before 12 months of age and immunocompromised states. We report a 7-year-old, otherwise healthy girl with shingles, and review the risk factors, prognosis, and treatment of pediatric zoster.

Child↗
PubMedDate not supplied

Impedance screening for preschool children. State of the art.

As a test for detecting middle ear disease among preschool children, tympanometry -- as opposed to audiometry -- has three advantageous attributes: a high degree of sensitivity, minimal need for subject cooperation, and total objectivity. For these reasons interest has arisen in tympanometry as a method for screening, i.e., identifying children with previously undetected middle ear disease. However, uncertainty persists concerning the importance of detecting apparently asymptomatic middle ear effusions, and concerning optimal methods, or even the advisability, of treating them. Further, the sensitivity and specificity of tympanometry depend on how the pass-fail cutoff point is defined. Defining this cutoff point so as to achieve high sensitivity may result in excessively low specificity, with the production of large numbers of false-positives who then become overreferrals. Data are presented to show how the validity of the test may be increased to some extent by attention to the gradient of "negative-pressure" tympanograms. At the present time, given the various aforementioned uncertainties, and with adequate validation as to the presence or absence of disease often lacking in reported studies of impedance screening in preschool populations, the cumulative results of these studies do not warrant embarking on large-scale screening programs. What is needed instead is additional research to explore the issue further.

Acoustic Impedance Tests↗