Occurrence of somatostatin and insulin immunoreactivities in the stomach of sea bass (Dicentrarchus labrax L.): light and electron microscopic studies

Somatostatin (SST)- and insulin (INS)-immunoreactive (ir) cells were identified in the gut of sea bass (Dicentrarchus labrax) by immunofluorescence double staining and peroxidase-antiperoxidase (PAP) techniques for light microscopy and by immunogold method for electron microscopy using antisera to mammalian and fish peptides. SST-14 and SST-25 immunoreactivities coexisted in cells mainly located among the mucous neck cells of the gastric glands. Preabsorption controls showed that some SST-25- and, possibly, some SST-14-like peptides appeared in these cells. Immunoreactivity to fish INS, but not to mammalian INS (mINS) or insulin-like growth factor I (mIGF-I), was observed in all the SST-ir cells. The preabsorption controls suggest a cross-reaction of the fish INS antisera with SST-containing or type I cells. These cells displayed ovoid or round secretory granules with fibrous, medium electron-dense or homogeneous osmiophilic materials. Some gastric cells (type II) with round secretory granules of variable electron density, which were gold immunolabeled with bonito INS but not with mINS, mIGF-I, or SST antisera, were also found. INS-related peptide in type II cells of the sea bass stomach is suggested.     

Role of the Rab3A-binding domain in targeting of rabphilin-3A to vesicle membranes of PC12 cells

Rab3A is a small GTPase implicated in the docking of secretory vesicles in neuroendocrine cells. A putative downstream target for Rab3A, rabphilin-3A, is located exclusively on secretory vesicle membranes. It contains near its C terminus two C2 domains that bind Ca2+ in a phospholipid-dependent manner and an N-terminal, Rab3A-binding domain that includes a Cys-rich region. We have determined that the Cys-rich domain binds two Zn2+ ions and is necessary but not sufficient for efficient binding of rabphilin to Rab3A. A minimal Rab3A-binding domain consists of residues 45 to 170 of rabphilin. HA1-tagged Rab3A and a green fluorescent protein (GFP)-rabphilin fusion were used to examine the roles of Rab3A and of rabphilin domains in the subcellular localization of these proteins. A Rab3A mutant (T54A) that does not bind rabphifin in vitro colocalized with the GFP-rabphilin fusion, indicating that Rab3A targeting is independent of its interaction with rabphilin. Deletion of the C2 domains of rabphilin reduced membrane association of GFP-rabphilin but did not cause mistargeting of the membrane-associated fraction. However, disruption of the zinc fingers, which drastically reduced Rab3A binding, did not reduce membrane association. These results suggest that the C2 domains are required for efficient membrane attachment of rabphilin in PC12 cells and that Rab3A binding may act to target the protein to the correct membrane.     

Influenza virus hemagglutinin: hydrodynamic properties and molecular weight

Following acute alcohol administration (80-160 mg/100 g body weight) histamine levels of rat brain cortex and thalamus were elevated and histidine decarboxylase activity was decreased. The effect was less pronounced after chronic alcohol treatment (15% v/v in drinking water for 4 weeks). In the striatum there was no change in the metabolic pattern of histamine. Histamine-N-methyltransferase was unaffected in either case. Depolarisation-induced release of histamine was inhibited by alcohol in the hypothalamus, thalamus and cortex. The results indicate that ethanol affects the histamine metabolism and release processes in the histaminergic pathway of the brain.     

Cytotoxic activity of platelets and peripheral blood mononuclear cells from oncology patients and healthy donors

Testicular germ cell tumour is said to be a model for curable neoplasm. However, the prognosis of primary extragonadal germ cell tumour does not appear to be as promising. Though similar in histology, the biology of primary extragonadal germ cell tumour is different as exemplified by the patients in this review. Eight patients with primary mediastinal germ cell tumours were treated with intensive cisplatin-based chemotherapy. All, except one, had non-seminomatous components. The poor prognosis of mediastinal germ cell tumour is due to a combination of poor treatment results with the cisplatin-based regimen and the development of non-germ cell and haematological malignancies.     

Bound-abrasive polishers for optical glass

Polishing abrasives that have been bound in a solid matrix can offer several potential advantages over loose-abrasive processes with pitch or polyurethane laps for finishing of optics. These advantages include polishing efficiency, temperature stability, cost of consumables, and compatibility with computer numerically controlled generating machines. Unfortunately, little has been published on bound-abrasive polishers, and very few commercially available products exist. We have developed several compositions and manufacturing techniques that show promise for polishing a variety of optical glasses. We establish the various criteria for a successful bound-abrasive polisher. The numerous variables to be considered in designing these polishers are identified, and the results of screening experiments are used to find successful compositions. Polishing experiments with bound abrasives in arrays of pellets, as ring tools, and as full-contact laps are described.     

Effect of pH on tobacco anionic peroxidase stability and its interaction with hydrogen peroxide

The dendritic localization of mRNAs has been proposed to underlie the structural and functional polarity of neurons, as well as certain aspects of synaptic plasticity. Even though there is no conclusive evidence that such a localization is a physiological requirement, studies of mRNA localization in relation to function in other cell types and recent experiments on synaptic plasticity suggest that this proposal may be correct.     

BRCA1 mutations in southern England

If genetic testing for breast and ovarian cancer predisposition is to become available within a public health care system there needs to be a rational and cost-effective approach to mutation analysis. We have screened for BRCA1 mutations in 230 women with breast cancer, all from the Wessex region of southern England, in order to establish the parameters on which to base a cost-effective regional mutation analysis strategy. Truncating mutations were detected in 10/155 (6.5%) consecutive cases selected only for diagnosis under the age of 40 (nine of these ten women had a strong family history of breast or ovarian cancer), 3/61 (4.9%) bilateral-breast cancer cases (all three mutations occurring among women for whom the first cancer was diagnosed under 40 years) and 8/30 (26.6%) breast cancer cases presenting to the genetics clinic (for whom a strong family history of breast and/or ovarian cancer was present). Ten different mutations were detected in 17 families, but three of these accounted for 10/17 (59%) of the families. The cost of screening the population for mutations in the entire BRCA1 gene is unacceptably high. However, the cost of screening a carefully selected patient cohort is low, the risk of misinterpretation much less and the potential clinical benefits clearer.