摘要:

The widespread use of caffeine is most commonly linked to the stimulatory action it has on the central nervous system. Generally, adverse effects include gastrorrhea, insomnia, and diuresis. Tolerance and withdrawal symptoms have been observed and excessive consumption can lead to an anxiety neurosis condition (caffeinism). The actions of caffeine may involve its effects on neurotransmitter turnover and metabolism; its promotion of the cellular messenger, cAMP; its sensitization of the calcium releasing mechanisms of cellular reticulum; or its antagonism of the autacoid, adenosine. Caffeine lethality is rare in man but caffeine poisoning with its gastrointestinal, CNS, and cardiovascular stimulation could especially be hazardous to children. Most of the mutagenicity work has been performed in organisms whose cellular DNA synthesis and repair mechanism vary significantly from those found in man. The work in human cell lines suggests that caffeine‐induced chromosomal breakage, with its lack of chromatid exchange would promote cell lethality, not muta‐genticity. Nothing but circumstantial evidence implicates caffeine as a human carcinogen or teratogen. Involvement of caffeine as a cocarcinogen or a coteratogen (which includes effects on gamete production or fetal development) appears far more likely, but neither has even begun to be truly evaluated. Basic metabolism of caffeine involves the processes of N‐demethylation, hydration, and oxidation; and most likely requires the cytochrome P1‐450 system. Though various metabolites of caffeine are pharmacologically active, the extent of involvement of individual metabolites in the pharmacological or toxicological responses of caffeine in man is still

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00435.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

A depuration chamber was used to study the persistence of marine vibrios in the hardshell clam, Mercenaria mercenaria. Specimens of M. mercenaria were incubated for two h in artificial seawater containing 103cells/ml each of the following bacterial species; Vibrio parahaemolyticus, Vibrio harveyi and Escherichia coli, and then transferred to the depuration chamber (a tank through which U. V.‐sterilized artificial seawater was continually flowing). Numbers of the three bacterial species in tissues of M. mercenaira removed from the chamber at various times were determined by differential plating techniques. The number of each species ranged from 102to 103colony‐forming units/gram tissues immediately after transfer to the depuration chamber. After 24 h at 25°C the number of E coli cells detected had decreased over 100‐fold. Generally, V. parahaemolyticus and V. harveyi were found in increased abundance after 24 h. The abundance of V. parahaemolyticus and V. harveyi in clams that had been incubated in the depuration chamber for 72 h at 25°C was approximately 10% of the abundance of these species immediately after transfer to the chamber. Similar results were obtained when the incubation temperature was 8 or 15°C and when initial cell concentrations were altered. Thus, V. harveyi and the potential human pathogen, V. parahaemolyticus which are both of marine origin were not removed from M. mercenaria at a rate comparable to the rate at which M. mercenaria depurated cells of

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00436.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1982.tb00437.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY