Normal and pathological aspects of mass transport across the vascular wall.

The rapid progress in cardiovascular surgery during the past 10 years has been matched by a complementary increase in the understanding of underlying cellular and molecular aspects of normal and pathological physiology of blood vessels. This review focuses on one aspect of vascular biology, namely the transport of macromolecules and water across the vascular wall, with particular attention to the role of endothelial permeability, and offers a bridge between the basic biological sciences and clinical care.

Parallel patterns of cell-specific gene expression during enterocyte differentiation and maturation in the small intestine of the rabbit.

Enterocytes are the major epithelial cell type of the small intestine. Their capacity to secret, absorb and digest specific ions and nutrients is dependent on their position along the length of the small intestine as well as their stage of development as they migrate and differentiate along the crypt-villus axis. In order to further understand the molecular processes that regulate enterocyte differentiation and function, this study has compared the levels of six mRNA species produced by genes expressed in rabbit enterocytes; specifically, the multidrug resistance (MDR1) gene encoding the 170-kDa P-glycoprotein, CaBP 9k, which encodes a putative intracellular calcium buffer, calbindin, LPH, APN, and AP which encode the brush-border hydrolases lactase-phlorizin hydrolase, aminopeptidase N and alkaline phosphatase, respectively, and SGLT1, encoding the brush border Na(+)-glucose cotransporter.

Effects of the 5-HT1A agonist 8-OH-DPAT on operant feeding in pigs.

The effect of intravenous (i.v.) injection of 8-OH-DPAT on operant food intake in pigs has been examined in animals with food available ad lib and in pigs feeding after 4 h deprivation of food.

Insulin and insulin-like growth factor I stimulate expression of the primary response gene cMG1/TIS11b by a wortmannin-sensitive pathway in RIE-1 cells.

The addition of insulin or insulin-like growth factor I (IGF-I) to RIE-1 cells increased the expression of the primary response gene cMG1; dose-response analysis suggested that this effect was mediated largely through type 1 IGF receptors. Insulin/IGF-I did not affect the expression of the cMG1-related genes TIS11 and TIS11d, whereas epidermal growth factor, angiotensin II or 12-O-tetradecanoyl phorbol-13-acetate stimulated the expression of all three genes. Incubation with wortmannin (WM) prevented the insulin/IGF-I-induced elevation of cMG1 mRNA, but not that induced by the other mitogens or the stimulation of mitogen-activated protein kinase by insulin.

Characterisation of Ca(2+)-dependent inwardly rectifying K+ currents in HeLa cells.

The whole-cell configuration of the patch-clamp technique was used to examine K+ currents in HeLa cells. Under quasi-physiological ionic gradients, using an intracellular solution containing 10(-7) mol/l free Ca2+, mainly outward currents were observed. Large inwardly rectifying currents were elicited in symmetrical 145 mmol/l KCl.

Cellular localization and differential distribution of GABAA receptor subunit proteins and messenger RNAs within hypothalamic magnocellular neurons.

The inhibitory neurotransmitter GABA plays an important role in regulating the activity of magnocellular oxytocin and vasopressin neurons located in the supraoptic and paraventricular nuclei through occupancy of GABAA receptors. However, the GABAA receptor is a hetero-oligomeric protein comprised of different subunits and the subunit types expressed in a given receptor complex appear critical for its sensitivity to GABA, benzodiazepines and/or steroids. Thus, in order to understand fully the GABAergic control of oxytocin and vasopressin secretion, definition of the GABAA receptors synthesized by magnocellular neurons in the supraoptic and paraventricular nuclei is required.

Differential regulation of vitamin D receptor and intestinal calcium transport occurring during sexual maturation in the fowl (Gallus domesticus).

Quantitative measurements of intestinal vitamin D receptor (VDR) and calcium transport taking place in individual villus-attached enterocytes have been compared during the onset of sexual maturity to test for a direct involvement of VDR in controlling calcium transport across the chick small intestine. Chickens of all ages showed VDR to be present in crypt and villus enterocytes, the amounts of VDR declining only slightly during enterocyte migration from the crypts to the tips of villi. Calcium transport corrected for initial adsorption was lowest in the crypt and highest in villus tip enterocytes.

The CCKA receptor antagonist devazepide inhibits the effect of apomorphine on vasopressin release in pigs.

1. A transient increase in plasma vasopressin concentrations represents a physiological correlate of nausea in animals that vomit. 2.

Central effects of CCK ligands in pigs making operant responses for food.

The effects, on operant feeding, of intracerebroventricular (ICV) injections of the CCKA receptor agonist A71623, the CCKB receptor agonist A63387, and the CCKA receptor antagonist A70104 were investigated in prepubertal pigs. In overnight starved animals, feeding was inhibited by 20, 5, and 1 micrograms doses of A71623 and by 20, but not 5 or 1 micrograms doses of A63387. In a second experiment, although pigs pretreated centrally with A70104 (20 micrograms) showed a tendency to eat more, the effect was not statistically significant.

Sister chromatid separation and the metaphase-anaphase transition in mouse oocytes.

The paper reports on the effect of experimentally inhibiting chromatid separation on meiotic progression and maturation-promoting factor (MPF) activity in both metaphase I (Experiment 1) and metaphase II mouse oocytes (Experiment 2) subjected to combinations of inhibitors of (a) protein synthesis, (b) topoisomerase II, and (c) cytokinesis-cytoskeleton integrity. The results from Experiment 1 showed that the inhibition of protein synthesis invariably results in the extrusion of the first polar body and the formation of an interphase nucleus. Furthermore, this inhibition induces a rapid decline in MPF activity.

Induction of c-fos expression in hypothalamic magnocellular neurons requires synaptic activation and not simply increased spike activity.

Magnocellular neurons of the hypothalamic supraoptic nucleus have been shown to express the immediate-early gene c-fos in a number of experimental and physiological circumstances. In each case the induction of the immediate-early gene followed the increase in the spike activity of the cells. Since an increase in the intracellular concentration of calcium following influx through voltage-sensitive calcium channels is a known stimulus for c-fos expression and since the action potentials of these neurons have a large calcium component, we hypothesized that c-fos induction in these neurons could be attributed to calcium influx during spike activity.

Stress-induced changes in c-fos immunoreactivity in the porcine brain.

An immunocytochemical method was used to examine expression of c-fos protein in forebrain and brainstem regions of prepubertal pigs (n = 2 per treatment) subjected to various physical stressors (snaring, cold exposure and transport simulation) and of an untreated animal. Each of the stress procedures induced specific nuclear labelling of neurons in the hypothalamus (paraventricular and especially supraoptic nuclei) and small amounts of labelling in some brainstem regions. These results confirm and extend findings obtained in rodents and indicate the potential value of this technique for stress and welfare research in ungulates.

Diacylglycerol and alkylacylglycerol stimulate ram sperm phospholipase A2.

1. We have investigated the susceptibility of ram sperm phospholipase A2 (PLA2) to stimulation by diacyl- and alkylacylglycerols and by monoacyl- and monoalkylglycerols. 2.

Novel plasma membrane action of estrogen and antiestrogens revealed by their regulation of a large conductance chloride channel.

Antiestrogens antagonize many genomic effects of estrogen through binding to the nuclear estrogen receptor. We report here that NIH3T3 fibroblasts grown in the presence of colchicine acquire the activation of a large conductance chloride channel upon exposure to extracellular but not intracellular antiestrogens. This effect can be prevented by extracellular 17 beta-estradiol, but not intracellular 17 beta-estradiol or extracellular 17 alpha-estradiol.

Localization of NADPH cytochrome P450 oxidoreductase in rat brain by immunohistochemistry and in situ hybridization and a comparison with the distribution of neuronal NADPH-diaphorase staining.

An antibody to cytochrome P450 oxidoreductase, purified from rat liver, has been used for the immunohistochemical localization of cytochrome P450 oxidoreductase-like immunoreactivity in the rat central nervous system. The distribution of this immunoreactivity has been confirmed using in situ hybridization with specific cytochrome P450 oxidoreductase antisense DNA probes. Cytochrome P450 oxidoreductase immunoreactivity was detected in neurons and was found in some glial populations.

A functional analysis of imprinting in parthenogenetic embryonic stem cells.

A detailed analysis of the developmental potential of parthenogenetic embryonic stem cells (PGES) was made in vivo and in vitro, and a comparison was made with the development of cells from parthenogenetic embryos (PG). In vivo, in chimeras with normal host cells (N), PGES cells showed a restricted tissue distribution consistent with that of PG cells, suggesting faithful imprinting in PGES cells with respect to genes involved in lineage allocation and differentiation. Restricted developmental potential was also observed in teratomas formed by ectopic transfer under the kidney capsule.

Directed expression of simian virus 40 T-antigen in transgenic mice using the epidermal growth factor gene promoter.

A transgenic mouse line (EGF/Tag) has been established in which expression of SV40 T-antigen is directed by a 5.5 kb fragment of the 5'-flanking region of the mouse epidermal growth factor (EGF) gene. Of the two principal sites of EGF expression in mice, submaxillary gland and kidney, T-antigen mRNA and protein were detected in the former but not in the latter tissue of the EGF/Tag animals.

Expression of GABAA receptor alpha 2 sub-unit mRNA by periventricular somatostatin neurones in the rat hypothalamus.

Pharmacological evidence suggests that GABA may play an important role in regulating the secretory and synthetic activity of the hypothalamic periventricular somatostatin (SOM) neurones controlling growth hormone secretion. In this study, we have utilized a dual labelling in situ hybridization technique to examine whether the alpha 2 sub-unit of the GABAA receptor, which is abundant in this region, is expressed by periventricular SOM neurones. Neurones expressing SOM were detected using an alkaline phosphatase-labelled antisense oligonucleotide and the alpha 2 sub-unit with an 35S-labelled antisense oligonucleotide.

Hyperthermia-associated changes in Fos protein in the median preoptic and other hypothalamic nuclei of the pig following intravenous administration of prostaglandin E2.

Changes in body temperature and hypothalamic Fos production were investigated in pigs injected intravenously with prostaglandin E2 (PGE2, 20 micrograms/kg). PGE2 produced a sustained (> 150 min) hyperthermia (0.7-1 degree C) and significant increases in Fos labelling in the supraoptic and paraventricular nuclei.

MPF components and meiotic competence in growing pig oocytes.

Growing pig oocytes (< or = 90 microns in diameter) are unable to resume meiosis in vitro. The objective of our present experiments has been to identify the reasons for meiotic competence in these cells. By comparing histone H1 kinase activity in growing and fully grown oocytes we demonstrate that incompetence is associated with an inability to activate H1 kinase in growing oocytes.

Membrane dynamics during migration of placental cells through trophectodermal tight junctions in sheep and goats.

Binucleate cells in ruminant trophectodermal epithelium are unique in that they form part of the tight junction as they migrate across it, maintaining the ionic barrier seal to the internal milieu of the fetus. Such participation imposes considerable constraints on the cell migration because membrane cannot flow through a tight junction. We report quantitative ultrastructural immunocytochemical evidence for vesicle membrane insertion into the binucleate cell plasmalemma which allows the cells to form a pseudopodium past the tight junction.

Infiltrating gamma delta T-cells and selectin endothelial ligands in the cutaneous phytohaemagglutinin-induced inflammatory reaction.

The 24 h phytohaemagglutinin-induced skin inflammatory site (intradermal and subcutaneous) was studied in inbred MHC-homozygous (SLAb/b) pigs and it was found, by immunohistology, that the predominant lymphocytes in the infiltrate are CD2-CD4-CD8-sIg-T-cells, the Null/gamma delta T-cell family, identified using the monoclonal antibodies (mAbs) MAC320 and MAC319 (which recognises a subset of MAC320+ cells). A large percentage of the infiltrating cells expressed the gamma delta T-cell receptor phenotype identified by binding of the mAb 86D. Fewer CD2+, CD8+ and CD4+ cells were present and surface immunoglobulin positive (sIg+) cells were virtually absent in the infiltrate.

The CD45 tyrosine phosphatase regulates specific pools of antigen receptor-associated p59fyn and CD4-associated p56lck tyrosine in human T-cells.

A newly isolated T-cell line (CB1) derived from a T-acute lymphoblastic leukaemia (T-ALL) patient contained cells (40% of total) which did not express the CD45 phosphotyrosine phosphatase. The cells were sorted into CD45- and CD45+ populations and shown to be clonal in origin. T-cell receptor (TCR) cross-linking or coligation of the TCR with its CD4/CD8 co-receptors induced tyrosine phosphorylation and calcium signals in CD45+ but not in CD45- cells.