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Biomedical subjects

C C Smith

Publications and source records attributed to C C Smith.

258 records · Page 15Linked to original sources
PubMedDate not supplied

Changes in transmitter release patterns in vitro induced by tremorgenic mycotoxins.

The neurochemical effects of the tremorgenic mycotoxins Verruculogen and Penitrem A, which produce a neurotoxic syndrome characterized by sustained tremors, were studied using sheep and rat synaptosomes. The toxins were administered in vivo, either by chronic feeding (sheep) or ip injection 45 min prior to sacrifice (rat). Synaptosomes were subsequently prepared from cerebrocortical and spinal cord/medullary regions of rat, and corpus striatum of sheep. Penitrem A (400 mg mycelium/kg) increased the spontaneous release of endogenous glutamate, GABA, and aspartate by 213%, 455%, and 227%, respectively, from cerebrocortical synaptosomes. Verruculogen (400 mg mycelium/kg) increased the spontaneous release of glutamate and aspartate by 1,300% and 1,200% respectively, but not that of GABA, from cerebrocortical synaptosomes. The spontaneous release of the transmitter amino acids or other amino acids was not increased by the tremorgens in spinal cord/medullary synaptosomes. Penitrem A pretreatment reduced the Veratrine (75 microM) stimulated release of glutamate, aspartate and GABA from cerebrocortical synaptosomes by 33%, 46%, and 11% respectively, and the stimulated release of glycine and GABA from spinal cord/medulla synaptosomes by 67% and 32%, respectively. Verruculogen pretreatment did not alter the Veratrine-induced release of transmitter amino acids from cerebrocortex and spinal cord/medulla synaptosomes. Penitrem A pretreatment increased the spontaneous release of aspartate, glutamate and GABA by 68%, 62%, and 100%, respectively, from sheep corpus striatum synaptosomes but did not alter the synthesis and release of dopamine in this tissue. Verruculogen was shown to cause a substantial increase (300-400%) in the miniature-end-plate potential frequency at the locust neuromuscular junction. The response was detectable within 1 min, rose to a maximum within 5-7 min, and declined to the control rate over a similar period. No change in the amplitude of the m.e.p.p.s was observed. These effects of the tremorgens on transmitter release are interpreted in terms of their mode of action.

Amino Acids↗
PubMedDate not supplied

Comparative metabolism of 1,2,4-trichlorobenzene in the rat and rhesus monkey.

1,2,4-Trichloro[14C]benzene (TCB) was administered po (10 mg/kg) and iv (10 mg/kg) to rats and rhesus monkeys. Urine was collected at 24 hr and the major urinary metabolites were quantified and identified. By 24 hr, the monkey had excreted 22% of the iv dose and roughly 40% of the po dose in the urine. Less than 1% of the radioactivity was found in the monkey's feces. An isomeric pair of 3,4,6-trichloro-3,5-cyclohexadiene-1,2-diol glucuronides accounted for between 48 and 61% of the urinary metabolites. Glucuronides of 2,4,5- and 2,3,5-trichlorophenol (TCP) accounted for 14 to 37%, and unconjugated TCP's accounted for 1-37% of the monkey's urinary metabolites. For the rat, 84% of the po dose and 78% of the iv dose were collected in the urine by 24 hr; 11% and 7%, respectively, were the amounts collected in the feces. Two isomers, 2,4,5- and 2,3,5-, of N-acetyl-S-(trichlorophenyl)-L-cysteine accounted for 60-62% of the rat's urinary metabolites. Free 2,4,5- and 2,3,5-isomers of trichlorothiophenol amounted to 33% of the urinary metabolites in the po dosed rats and 28% in the iv dosed rats; free 2,4,5- and 2,3,5-TCP's amounted to 1% and 10%, respectively. These results show that there is a sharp division in the types of conjugates formed in the metabolism of 1,2,4-TCB by the rat and rhesus monkey.

Acetylcysteine↗
PubMedDate not supplied

Correlation of human hepatotoxicants with hepatic damage in animals.

Substances that cause liver damage in humans were identified through a literature search conducted on Toxline and Medline. Using the same search strategy, species other than man were selected, in whom hepatic injury could be attributed to exposure to the identified substances. A total of 38 substances were identified as producing liver damage, manifested by either clinical chemistry or histopathology. The substances included 24 drugs, 9 industrial chemicals, 3 environmental agents, 1 pesticide, and ethanol. Twelve of the 36 compounds have been toxicologically evaluated in man, rodent, and non-rodent. Histopathologic liver damage was reported in all three species for 11 of these compounds. Only carbencillin produced histopathologic damage in man but not in either the rodent or non-rodent. Where clinical chemistry changes were reported for all three species categories, only eight substances induced similar reactions in all three species. Only with two substances did man and rodent react similarly (both positive), while the non-rodent was negative. The two substances were polychlorinated biphenyl (PCB) and tetrachlorethane. In the majority of the cases in which either or both histopathologic or clinical chemistry changes were reported for man or for the rodent or non-rodent, the changes that occurred were qualitatively similar. The rodent was as sensitive a predictor for hepatic effects as the non-rodent. Although it is impossible to predict how liver damage observed in a laboratory animal is correlated with human liver damage, hepatotoxicity in the rodent must be considered as indicative of potential hepatic damage in man.

Animals↗
PubMedDate not supplied

Fluorescence-activated separation of cervical abnormal cells using herpesvirus antigenic markers.

Antisera to total HSV-2 (G) viral antigens (Ra-2) and to increasingly purified viral antigenic fractions ("crude" and "pure" AG-e) specifically stain HSV-2-(G)- or HSV-1-(F)-infected HEp-2 cells in indirect immunofluorescence. Anti-"crude" AG-e sera induced by HSV-1 (F) or HSV-2 (G) produce a single precipitin band of identity when reacted in gel immunodiffusion against soluble antigenic mixtures from HSV-2-infected cells (HSV-2 (G) SAM). These reactivities are lost following adsorption of the sera with HSV-1 or HSV-2-infected cells or with pelleted or dextran gradient purified virions. Ra-2 and anti-"crude" or "pure" AG-e sera stain exfoliated cervical cells from patients with herpetic cervicitis as well as atypical cells from patients with atypia, carcinoma in situ or invasive cancer. Normal squamous cells do not stain. HSV-2 viral antigens recognized by the Ra-2 and anti-AG-e sera appear to constitute specific and sensitive markers for the separation of atypical cells in a fluorescence-activated cell sorter.

Antigens, Viral↗