Ultrastructural localisation of substance P and choline acetyltransferase in endothelial cells of rat coronary artery and release of substance P and acetylcholine during hypoxia

Substance P and choline acetyltransferase have been localised in a small proportion of endothelial cells of rat coronary arteries using electron microscopic immunocytochemistry. During a hypoxic period of 1 min, coronary vasodilatation was produced in the Langendorff heart preparation and increased levels of substance P and acetylcholine were released into the perfusate. The possibility that these substances are released from endothelial cells during hypoxia and contribute to the hyperaemic response is discussed.     

In situ demonstration of the activity of 3 beta-hydroxysteroid dehydrogenase on steroid hormone secreting cells within the paraaortic lymph nodes of golden hamster

The in situ activity of 3 beta-hydroxysteroid dehydrogenase was detected in clustered cells which showed steroid-producing morphology, within the capsule of the paraaortic lymph node. In light and electron microscopic studies, the positive reaction products were detected on intracapsular cell clusters. This result indicates that these unique cells may have a steroid secreting function within the lymph nodes.     

Default Priors for Neural Network Classification

Feedforward neural networks are a popular tool for classification, offering a method for fully flexible modeling. This paper looks at the underlying probability model, so as to understand statistically what is going on in order to facilitate an intelligent choice of prior for a fully Bayesian analysis. The parameters turn out to be difficult or impossible to interpret, and yet a coherent prior requires a quantification of this inherent uncertainty. Several approaches are discussed, including flat priors, Jeffreys priors and reference priors.     

Construction of chimaeric processed immunoglobulin genes containing mouse variable and human constant region sequences

The specificity of monoclonal antibodies provides a powerful diagnostic and therapeutic tool in investigating human neoplasia. Radiological scanning and immunotherapy with mouse tumour-specific monoclonal antibodies have been applied to patients with some success, but a major problem is the neutralization of the mouse antibody induced by repeated administration of heterologous antibodies. To avoid or reduce such immune reactions, chimaeric immunoglobulins consisting of mouse variable (V) and human constant (C) regions can be synthesized. We have constructed a recombinant retrovirus DNA carrying genomic heavy-chain (H) variable-diversity joining (VH-D-JH) and C gamma 1 genes from different species and show here that the chimaeric intervening sequences are spliced out precisely. This procedure provides a useful method to construct the chimaeric mouse-human immunoglobulin gene to be expressed in Escherichia coli, yeast and animal cells. Unexpectedly, a hidden splice donor site in the 5'-flanking region of a human VH gene is used in place of the donor site of the leader sequence exon, resulting in the formation of the V region without the leader sequence.     

A new anatomy of the prestalk zone in Dictyostelium

The characteristic structure of the mature Dictyostelium culminant is created by the regionalized cellular differentiation and directed movement of prestalk cells. The front prestalk zone of the migratory slug has previously been considered to be a homogeneous tissue. Here we demonstrate, however, the existence of multiple classes of prestalk cells located in different parts or the slug anterior. The pDd56 and pDd63 genes encoding closely related extracellular matrix proteins are dependent for their expression upon DIF-1, the specific stalk-cell inducer. We have fused the promoters of the two genes to a modified chloramphenicol acetyltransferase (cat) gene to produce immunologically detectable proteins which localize to the cell nucleus. These two markers define three distinct kinds of 'prestalk' cells. One class, which we term 'prestalk A' cells, expressed the pDd63 gene. 'Prestalk B' cells express pDd56 and may also express the pDd63 gene. A third class, which we term 'prestalk 0' cells, expresses neither marker.     

Porcine diacylglycerol kinase sequence has zinc finger and E-F hand motifs

Cell stimulation causes diacylglycerol kinase (DGK) to convert the second messenger diacylglycerol into phosphatidate, thus initiating the resynthesis of phosphatidylinositols and attenuating protein kinase C activity. Of the DGK isoforms so far reported, only porcine DGK from lymphocytes has been characterized in detail. Here we report the isolation and sequencing of complementary DNA clones that together cover the entire region encoding porcine DGK (relative molecular mass 80,000 (80K)). The deduced primary structure of this DGK contains the putative ATP-binding sites, two cysteine-rich zinc finger-like sequences similar to those found in protein kinase C, and two E-F hand motifs, typical of Ca2(+)-binding proteins like calmodulin. Indeed, we find that the activity of this DGK isoform is enhanced by micromolar concentrations of Ca2+ in the presence of deoxycholate or sphingosine. These properties of 80K DGK indicate that its action is probably linked with both of the second messengers diacylglycerol and inositol 1,4,5-trisphosphate.     

Restoration of normal function in genetically defective myotubes by spontaneous fusion with fibroblasts

Muscular dysgenesis in mice is a genetic disease of skeletal muscle caused by the recessive mutation mdg. Muscle fibres in affected mice are paralysed because of the failure of excitation-contraction coupling. Unlike normal myotubes in primary culture, dysgenic myotubes do not contract, either spontaneously or in response to electrical stimulation. The deficiency results from mutation of the gene for the skeletal muscle dihydropyridine receptor, an essential sarcolemmal component both of excitation-contraction coupling and of the slow calcium-ion channel. It has recently been shown that the addition of fibroblasts from normal (but not dysgenic) mice to cultures of dysgenic myotubes can restore spontaneous contractions in a small fraction of these myotubes, but the mechanism for this 'rescue' was not determined. In principle, if fibroblast nuclei were able to incorporate into myotubes, such nuclei could then supply the missing muscle-specific gene product. We have now investigated this possibility using nuclear, cytoplasmic and plasmalemmal markers. We report that the rescue to contractile ability in genetically paralysed dysgenic muscle is mediated by the previously unrecognized ability of fibroblasts to fuse spontaneously with developing myotubes.     

Dopamine-induced relaxation in human pulmonary arteries

Dose-dependent relaxations were induced by dopamine in human pulmonary arteries that had been contracted with prostaglandin F2 alpha without alpha-adrenergic blocking agents. The dopamine-induced relaxation was inhibited by haloperidol and fluphenazine, but not by domperidone, suggesting that this relaxation was mediated via DA1 receptors.     

Performance of an activated carbon made from waste palm shell in simultaneous adsorption of SO_x and NO_x of flue gas at low temperature

This study examined the individual and simultaneous adsorption of SOx(SO2)and NOx(NO-NO2)on activated carbon prepared from waste palm shell.The adsorption process was examined in a fixed bed reactor at low temperatures(100 300°C).For individual adsorption without any catalytic activation,SOx showed good adsorption whereas NOx was very much poor.In the simultaneous adsorption of SOx and NOx,SOx showed greater adsorption affinity than NOx.For palm shell activated carbon(PSAC)impregnated with metal catalyst(Ni and Ce)the concentration adsorbed profile showed that the amount of SOx adsorbed decreased regularly,while the amount of the adsorbed NOx increased irregularly.The properties of the pure and impregnated PSAC were analyzed by BET,SEM and EDX.These investigations indicated that PSAC impregnated with metal catalyst is the determining factor in the adsorption of SOx and NOx simultaneously.