BACKGROUND Cigarette smoking and cocaine use may be risk factors for spontaneous abortion, but data supporting such a link are limited. METHODS We studied the associations between cocaine and tobacco use and spontaneous abortion among pregnant adolescents and women (age range, 14 to 40 years) who sought care at an inner-city emergency department. A total of 400 adolescents and women had spontaneous abortions either at study entry or during follow-up (which lasted until 22 weeks' gestation), and 570 adolescents and women remained pregnant past 22 weeks' gestation. Cocaine use was measured at base line by self-reports and analysis of urine and hair samples. Cigarette smoking was measured by self-reports and urine analysis. RESULTS The adolescents and women in both groups were predominantly black and of lower socioeconomic status. Among those who had spontaneous abortions, 28.9 percent used cocaine on the basis of hair analysis and 34.6 percent smoked on the basis of a urine cotinine assay, as compared with 20.5 percent and 21.8 percent, respectively, of the adolescents and women who did not have spontaneous abortions. The presence of cocaine in hair samples was independently associated with an increase in the occurrence of spontaneous abortion (odds ratio, 1.4; 95 percent confidence interval, 1.0 to 2.1) after adjustment for demographic and drug-use variables. However, the use of cocaine as measured by self-reports and by urine analysis was not. The presence of cotinine in urine was also independently associated with an increased risk of spontaneous abortion (odds ratio, 1.8; 95 percent confidence interval, 1.3 to 2.6). Twenty-four percent of the risk of spontaneous abortion could be related to cocaine or tobacco use. CONCLUSIONS Cocaine and tobacco use were common in our study population and were associated with a significant risk of spontaneous abortion.

Glutamate and aspartate are excitatory neurotransmitters in both central and peripheral nervous systems, acting on ionotropic and metabotropic receptors. In our study we have examined the effects of glutamate, aspartate, N-methyl-d-aspartate (NMDA), kainic acid and (+/-)-1-aminocyclopentane-cis-1,3-dicarboxylic acid (ACPD) on tone and spontaneous activity of isolated rat gastric fundus, jejunum, ileum, ascending colon and rectum. Both glutamate and aspartate produced concentration-dependent tonic contractions of rat fundus and rectum; the other gut segments used in the study were not responsive. While only NMDA and kainic acid produced concentration-dependent tonic contractions of isolated rat gastric fundus, all three type-selective agonists of glutamate receptors (NMDA, kainic acid and ACPD) produced tonic contractions of isolated rat rectum. The results of our study suggest that glutamate and aspartate in rat gastric fundus activate excitatory intrinsic neurons through only ionotropic receptors (NMDA and non-NMDA receptors), while the same action in rat rectum is mediated through both ionotropic and metabotropic receptors.

There are many, often relatively anecdotal, observations suggesting that agricultural activities affect lichens. However, the nature of the ' agricultural effect' involved is much less clear. Agriculture practices can involve anything from the use of pesticides, to inorganic fertilisers, to ammonia volatilised from animal waste, or pollution from farm vehicles. The nature, scale and extent of the effect will depend on the differential sensitivity of lichens to the cocktail of chemicals involved and the extent of their dispersal under the particular conditions. The result is a fascinating field of research to separate the different factors involved. Surprisingly little has been written on this subject. Currently, much of the published work has sought to demonstrate the impact of farms or farming without identifying the agents responsible. This is a necessary prelude to further investigation. Valuable advances have been made by categorising lichen species as ' acidophilous ' or ' nitrophilous ', even though the nature of the chemicals responsible are still unknown. Moreover, there is little comparative work reported. In northern Europe, the assemblage of epiphytic species observed around an active farm may, superficially, resemble that of a dust-impregnated mediterranean tree. But how close is the resemblance, and is it related to nitrogen enrichment? In order to try to develop this field of study further, Dennis Brown and Han van Dobben organised a small international workshop that met in Wageningen, the Netherlands, between 16th and 18th April 1993. The meeting was supported by the European Environmental Research Organisation and attended by researchers from ten countries. Although judged a successful exchange of ideas, for various reasons, no proceedings were produced. Some speakers' work was already in press, while others appeared, for example, in publications linked to the IAL symposium ' Progress and Problems in Lichenology in the Nineties ', held in Sweden. More recently, it was proposed that, to further develop this field of study, the original participants at the Wageningen workshop should be invited to submit manuscripts to form the nucleus of an issue of The Lichenologist devoted to ' agricultural effects '. This issue is the result and shows part of the range of studies and approaches reported at the earlier meeting. Some articles have been developed further than the original reports, whereas others remain relatively preliminary studies but ones that were judged to have the potential to stimulate further research. If this issue stimulates more discussion, debate and even disagreement, which finally helps clarify how farming may influence lichens, then the original workshop will be judged to have had a wider influence than just an enjoyable meeting, skilfully organised by Han van Dobben.

The contractile effect of benzylpenicillin on isolated rings of human gallbladder was studied using preparations taken from surgical specimens after gallbladderectomy. The gallbladder was cut into two pieces and one ring was cut from each piece; one ring was mounted in a 100 ml organ bath containing Krebs solution and the isotonic changes of the preparation were recorded for each experiment. Benzylpenicillin (1 x 10(4) to 1 x 10(8) IU/l) was shown to exert a dose-dependent contractile effect on isolated human gallbladder rings which was blocked by atropine (1 x 10(-8) M). The benzylpenicillin-induced contractile effect was analogous to contraction observed with acetylcholine (1 x 10(-7) to 1 x 10(-2) M). The effect of benzylpenicillin on isolated human gallbladder may reflect a possible decrease in gallbladder emptying time in vivo, suggesting a beneficial effect of benzylpenicillin in antimicrobial treatment of gallbladder infections.