Rat brain serotonin receptors in Xenopus oocytes are coupled by intracellular calcium to endogenous channels.

Serotonin activates chloride currents in Xenopus oocytes injected with a subfraction of rat brain poly(A)+ mRNA. Patch-clamp recordings from cell-attached patches showed that serotonin, applied locally outside the patch, caused the opening of channels of approximately equal to 3 pS conductance and an average lifetime of approximately equal to 100 msec. The extrapolated reversal potential indicated that the channels are chloride-selective. Single-channel currents with similar characteristics were observed in inside-out patches from native oocytes in response to elevated calcium concentrations on the cytoplasmic side. Measurements of intracellular calcium concentration ([Ca2+]i) by fura-2 fluorescence showed approximately equal to 10-fold increases in [Ca2+]i in response to serotonin application in both normal and calcium-free Ringer solution in mRNA-injected oocytes. Little or no response to serotonin was observed in native oocytes. These results suggest that serotonin activation of receptors that are inserted into the oocyte membrane following injection of rat brain poly(A)+ mRNA can induce calcium release from intracellular stores. The increase in [Ca2+]i subsequently activates calcium-dependent chloride channels. Because calcium-dependent chloride channels and a receptor-controlled mechanism of internal calcium release have been shown to exist in native oocytes, we conclude that the newly inserted serotonin receptors utilized the endogenous second-messenger-mediated calcium release to activate endogenous calcium-dependent chloride channels.     

HELICOBACTER PYLORI-SPECIFIC TUMOUR-INFILTRATING T CELLS PROVIDE CONTACT DEPENDENT HELP FOR THE GROWTH OF MALIGNANT B CELLS IN LOW-GRADE GASTRIC LYMPHOMA OF MUCOSA-ASSOCIATED LYMPHOID TISSUE

Previous studies have shown that tumour cells from low-grade B-cell gastric lymphomas of mucosa-associated lymphoid tissue (MALT) type proliferate in vitro in response to heat-killed whole cell preparations of Helicobacter pylori , but only in the presence of tumour-infiltrating T cells. This response is strain-specific in that the tumours studied responded optimally to different strains of H. pylori . It was unclear from these studies, however, whether the ability to recognize the specific stimulating strains of H. pylori was a property of the tumour cells or the tumour-infiltrating T cells. This study shows that whereas the tumour cells do not respond to H. pylori , both freshly isolated tumour-infiltrating T cells and a T cell line derived from these cells proliferate in response to stimulating strains of H. pylori . T cells from the spleen of one of the patients do not share this property. These results suggest that B-cell proliferation in cases of low-grade gastric lymphoma of MALT type in vitro in response to H. pylori is due to recognition of H. pylori by tumour-infiltrating T cells, which in turn provide help for tumour cell proliferation. The observations provide an explanation for properties of gastric MALT-type lymphoma, such as regression following eradication of H. pylori and the tendency of the tumour to remain localized to the primary site.     

Zinc and Vitamin A in Liver of Foetuses and Infants

ABSTRACT. The association of zinc and vitamin A levels was studied in liver of foetuses and infants which were stillborn or died of various causes between the age of 26 weeks of gestation up to 16 weeks post-partum. No correlation between zinc and vitamin A was observed ( r =0.07). Although smaller infants had more hepatic vitamin A than larger infants no significant difference was observed between these groups for liver zinc values.     

Aetiology of chronic suppurative lung disease

Forty one (1%) of 4000 children referred for respiratory disease had chronic suppurative lung disease not due to cystic fibrosis. Further investigations showed congenital malformations in six (15%), primary ciliary dyskinesia syndrome in seven (17%), 11 had immunological abnormalities (27%), and two bronchiectasis due to aspiration (5%). Therefore the underlying cause for the disease was found in 63%. Identification of predisposing causes may facilitate prevention of further bronchial damage.     

Acute otitis externa: efficacy and tolerability of N-chlorotaurine, a novel endogenous antiseptic agent

OBJECTIVE: The study's objective was to test the tolerability and efficacy of the endogenous antiseptic N-chlorotaurine (NCT) in comparison with a standard clinical treatment according to a phase IIb clinical trial protocol. STUDY DESIGN: The antimicrobial agent NCT was compared with the antibiotic component drops Otosporin (containing neomycin, polymyxin B, and hydrocortisone) for topical treatment of acute otitis externa in a randomized and rater-blinded clinical study. METHODS: Fifty patients suffering from acute otitis externa were divided into two groups according to a randomized list. The test group was treated with 1 mL of 1% aqueous NCT solution, the reference group with 1 mL of Otosporin. The substances were applied to the external ear canal at one daily session until the signs of infection disappeared. Efficacy and tolerability were evaluated daily by visual analogue scale and a six-step infection score. In addition, smears were analyzed to identify the causative pathogens. RESULTS: Both medications were equally well tolerated by the patients. The treatment was successful for all patients of the NCT group, whereas in one patient from the reference group, the infection did not disappear. The inflammation score improved more rapidly in the NCT group, which resulted in an earlier termination of the therapy. This difference became highly significant on days 4 to 7 (P <.01 each). Time needed for disappearance of inflammation (score 0) was 5.6 +/- 1.6 (mean +/- SD, range 3-9) days in the NCT group and 7.4 +/- 1.6 (range 4-10) days in the Otosporin group (P <.001). As expected, microbiologic cultures from ear swabs revealed Pseudomonas aeruginosa (58%) followed by Staphylococcus aureus (18%) as the main causative pathogens. CONCLUSIONS: NCT appears to be well tolerated and more effective than the therapy using antibiotic component drops. Because of its endogenous nature and its higher efficacy, NCT appears to be a good choice for topical treatment of acute otitis externa.