Search PubMed⌕ Search

Biomedical subjects

H E Smith

Publications and source records attributed to H E Smith.

At least 109 records · Page 6Linked to original sources
PubMed1977

Agonist effects of beta-phenethylamines on the noradrenergic cyclic adenosine 3',5'-monophosphate generating system in rat limbic forebrain. Stereoisomers of p-hydroxynorephedrine.

Significant agonist activity for the specific noradrenergic cyclic adenosine 3',5'-monophosphate (cAMP) generating system in rat limbic forebrain requires a beta-3,4-dihydroxyphenethylamine with a beta-hydroxyl group in the R configuration. Thus, neither of the enantiomers of p-hydroxynorephedrine nor of p-hydroxynorpseudoephedrine mimics the agonist activity of (R)-norepinephrine. It has yet to be established whether or not one of the p-hydroxynorephedrines exhibits antagonist activity in this same system.

Animals↗
PubMed1975

Possible formation and development of spirochaete attachment sites found on the surface of symbiotic polymastigote flagellates of the termite Reticulitermes flavipes.

We propose that spirochaete attachment sites arise from peripheral protrusions which appear on the surface of polymastigote flagellates. These protrusions develop into bracket-shaped structures which then form the mature attachment site. Next the site becomes detached from the surface of the cell; this latter process may be facilitated by the fusion of vesicles located in the region immediately beneath the spirochaete attachment site. This theory could explain the variability in the number and distribution of attachment sites on the surface of the flagellates.

Animals↗
PubMed1975

Correlation between brain levels and biochemical effects of the optical isomers of p-chloroamphetamine.

The biochemical effects of d- and l-p-chloroamphetamine (PCA) were compared with the brain levels of the unchanged drug at various times after a single injection. Initially both isomers produced rapid and pronounced decreases in the whole brain levels of serotonin and 5-hydroxyindoleacetic acid, tryptophan hydroxylase activity and the synaptosomal uptake of 3-H-serotonin. At later times (e.g., 2 weeks), the effects of the d-isomer were much more pronounced than were those of the l-isomer. At intermediate times (2-4 days), a variable and dose-dependent recovery of synaptsomal uptake activity and tryptophan hydroxylase activity occurred after d-PCA. In both whole brain and forebrain, long-term reductions in these activities were found. However, in the midbrain, an area containing the cell bodies of serotonergic neurons, only a slight initial decrease in tryptophan hydroxylase activity occurred. The whole brain levels of the two isomers were equal from 4 to 96 hours after injection and declined exponentially in a single monophasic manner monophasic decine of the levels of PCA was found in forebrain and midbrain samples. Thus, the initial and long-term effects of PCA are apparently mediated by different mechanisms. The former is correlated with the brain levels of the unchanged drug; the latter is not. The lack of any indication of a biphasic decay curve after 10 half-lives and the intermediate recovery of serotonergic function do not support a reserpine-like mechanism for the long-term effects of PCA. Instead, a mechanism related to neurotoxicity is proposed.

Amphetamines↗
PubMed1972

Ampicillin and tetracycline in the treatment and prophylaxis of chronic bronchitis.

Ampicillin and tetracycline, in doses of 2 g a day, were compared in the treatment of acute exacerbations of chronic bronchitis. Seventy-nine patients were followed for 3 to 29 months and were treated for 118 exacerbations. Clinical improvement occurred after 10 days of treatment with either drug in over 80% of the cases. Haemophilus influenzae and Diplococcus pneumoniae were eradicated from the sputum more than 60% of the time, but in general there was a poor correlation between bacteriological clearing and clinical response. The effect of chemoprophylaxis with ampicillin and tetracycline in doses of 1 g a day on the frequency of acute exacerbations of bronchitis was compared with that of a placebo. Seven hundred eighty prophylactic regimens, consisting of one capsule every 12 hr for 5 days beginning with the first sign of a cold, were prescribed for 76 patients. Irrespective of the regimen, an acute exacerbation of bronchitis was encountered at approximately 13% of the follow-up visits to the clinic.

Ampicillin↗