Receptor-receptor interactions as an integrative mechanism in nerve cells

Several lines of evidence indicate that interactions among transmission lines can take place at the level of the cell membrane via interactions among macromolecules, integral or associated to the cell membrane, involved in signal recognition and transduction. The present view will focus on this last subject, i.e., on the interactions between receptors for chemical signals at the level of the neuronal membrane (receptor-receptor interaction). By receptor-receptor interaction we mean that a neurotransmitter or modulator, by binding to its receptor, modifies the characteristics of the receptor for another transmitter or modulator. Four types of interactions among transmission lines may be considered, but mainly intramembrane receptor-receptor interactions have been dealt with in this article, exemplified by the heteroregulation of D2 receptors via neuropeptide receptors and A2 receptors. The role of receptor-receptor interactions in the integration of signals is discussed, especially in terms of filtration of incoming signals, of integration of coincident signals, and of neuronal plasticity.     

Suspected paediatric pesticide poisoning in the UK. II--Home Accident Surveillance System 1989-1991

1. Between 1989 and 1991, 121,708 children less than 10 years old attended 22 Accident and Emergency (A & E) Departments in the UK as a result of an accident at home; 6,478 of these were cases of suspected poisoning. 2. Two hundred and fifty (124 boys and 126 girls) of 6,478 cases involved pesticides. Forty two per cent of these children were thought to have been poisoned by rodenticides, 33% by a different animal poison, 13% by an herbicide or fungicide, 7% by creosote and 5% by mothballs; a pattern similar to that observed in previous years. 3. Fifty-seven of 250 children (23%) were admitted to hospital. The proportion of children admitted to hospital between 1989 and 1991 is smaller than that observed between 1982-1988 (37%). Forty-six per cent of children were discharged home within one day and 95% within 2 days, whereas between 1982 and 1988 only 35% of children were discharged within one day. No child died during the study confirming the low morbidity. 4. Using these data we estimate that between 1989 and 1991 approximately 1,500 children annually attended an A & E Department in the UK with a diagnosis of suspected pesticide poisoning and that some 350 children were admitted each year.     

Association of phosphotyrosine with rapsyn expression in Xenopus embryonic cells

The postsynaptic membrane of the neuromuscular junction is highly enriched in rapsyn, which is thought to interact directly with nicotinic acetylcholine receptors (AChR) and anchor them at the synapse. We expressed rapsyn with or without AChRs in Xenopus embryos by mRNA injection. Co-expression of AChR and rapsyn caused the clustering of these two proteins in cultured cells isolated from the injected embryos. When rapsyn was expressed alone, it also became clustered at the substratum-facing membrane in cultured cells and at cell-cell contacts in whole mount embryos. No clusters were observed in cells that expressed AChRs alone. In rapsyn-expressing cells, proteins that are tyrosine phosphorylated as shown by anti-phosphotyrosine antibody labeling were concentrated at rapsyn clusters. Rapsyn itself does not appear to be a substrate for tyrosine kinase. This suggests that other phosphotyrosine-containing proteins are co-clustered with rapsyn in these cells.     

Regional mapping of the human platelet-activating factor receptor gene (PTAFR) to 1p35-->p34.3 by fluorescence in situ hybridization

The human platelet-activating factor cell-surface receptor (PTAFR) is a G protein-coupled receptor thought to contribute to many atopic and inflammatory diseases and, perhaps, to the growth of some neoplasms. Exploring the possibility that the PTAFR might be involved in the genetic predisposition to any disease requires knowledge of its chromosomal localization. In this paper we have used a 20-kb human genomic fragment containing the coding sequence of the cloned PTAFR to determine the regional chromosomal localization of the gene. Using fluorescence in situ hybridization, the localization of the human PTAFR gene was mapped to 1p35-->p34.3.     

Educational efforts in preventing preterm delivery among inner city adolescents

The present study described the effectiveness of using an educational program for self-detection of premature labor in a group of forty-one indigent pregnant adolescents. Twenty-one of these teens self-detected premature labor and received appropriate medical intervention; only four had low birthweight infants and three delivered before 37 weeks. The overall results showed a significant use of the program and a high success to failure rate for those who received medical intervention. The cost-effectiveness and usefulness of this protocol in improving medical outcome for indigent teens are discussed.     

Prognosis of operable squamous cell carcinoma of the esophagus. Relationship with clinicopathologic features and DNA ploidy

Fluorescence in situ hybridization (FISH) was performed on human interphase sperm nuclei to determine the utility of this technique for aneuploidy detection. Repetitive DNA sequences specific for chromosomes 1, 12 and X were biotinylated and hybridized with mature sperm, which had been treated with cetyltrimethylammonium bromide and dithiothreitol to render them accessible to the probes. Detection of bound probe was accomplished with fluoresceinated avidin and antiavidin. For each of the chromosomes studied, chromosome number was determined by counting the fluorescent signals, representing hybridized regions, within the sperm nuclei. The frequencies for disomy, that is for nuclei containing two signals, for chromosomes 1, 12 and X were 0.06%, 0.04% and 0.03%, respectively. The congruence of these results with those determined by the cross-species hamster oocyte-human sperm assay, and the high efficiency of hybridization indicate that FISH is a sensitive and reliable tool for aneuploidy detection in human sperm.     

Pharmaceutical services in the treatment of hemophiliac patients

Pharmaceutical services in the treatment of hemophiliac patients in Sweden are described. To prevent arthropathy and improve quality of life, patients with severe hemophilia receive prophylactic treatment. Hemophiliac patients are referred for diagnosis, treatment, and follow-up to one of three hemophilia treatment centers. Patients are seen once or twice yearly for routine checkups. A new system for the distribution of antihemophilic factor and factor IX has been implemented to improve availability and reduce risks and costs. Patients registered at a center receive antihemophilic factor or factor IX from the corresponding hospital pharmacy. The number of different manufactured batches to which a patient can be exposed is restricted, and complete distribution data are recorded for each patient, enabling follow-up studies and facilitating withdrawals of faulty batches. Distribution of emergency kits to patients who do not receive supervised home therapy ensures the availability of treatment for bleeding episodes. Two studies performed to explore ways to reduce drug waste led to improvements in patient information, product guidelines, and equipment and a better understanding of the problems associated with product changes. Specialized pharmaceutical services in Sweden contributed to successful hemophilia treatment and reduced its cost.