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Biomedical subjects

R Glass

Publications and source records attributed to R Glass.

At least 19 recordsLinked to original sources
PubMed2002

P2X4 and P2X6 receptors associate with VE-cadherin in human endothelial cells.

We investigated the expression of P2X4 and P2X6 receptors on human umbilical vein endothelial cells (HUVECs) and found that both P2X receptor subtypes on plasma membranes are largely restricted to areas of cell-cell contact. Co-labelling experiments at the confocal and electron microscopy levels revealed that P2X4 and P2X6 receptors are strongly co-localised with the cell adhesion molecule VE-cadherin. The P2X4 and P2X6 receptors on plasma membranes at cellular junctions are rapidly (within 5 min) internalised specifically after decreasing extracellular [Ca2+]. Disruption of microfilaments, microtubules and integrin-mediated adhesion or stimulation of P2 receptors with ATP did not alter P2X4 and P2X6 receptor expression on HUVEC plasma membranes. Membraneous P2X4 and P2X6 receptors resisted extraction with Triton-X 100, whereas cytoplasmic P2X receptors were Triton-X 100 soluble. P2X4 receptors, but not P2X6 receptors, could be co-immunoprecipitated with VE-cadherin and vice versa. We conclude that P2X4 and P2X6 receptors are associated with VE-cadherin at HUVEC adherens junctions.

Antigens, CD↗
PubMed2002

P2 receptors in the murine gastrointestinal tract.

The actions of adenosine, adenosine 5'-triphosphate (ATP), 2-methylthio adenosine diphosphate ADP (2-MeSADP), 2-methylthio ATP (2-MeSATP), alpha,beta-methylene ATP (alpha,beta-meATP) and uridine triphosphate (UTP) on isolated segments of mouse stomach (fundus), duodenum, ileum and colon were investigated. The localization of P2Y(1), P2Y(2), P2Y(4), P2X(1) and P2X(2) receptors and neuronal nitric oxide synthase (NOS) were examined immunohistochemically, and P2Y(1) mRNA was examined with in situ hybridization. The order of potency for relaxation of longitudinal muscle of all regions was: 2-MeSADP>/=2-MeSATP>alpha,beta-meATP>ATP=UTP=adenosine. This is suggestive of P2Y(1)-mediated relaxation and perhaps a further P2Y receptor subtype sensitive to alpha,beta-meATP. As ATP and UTP are equipotent, the presence of a P2Y(2) receptor is indicated. ATP responses were inhibited by the P2Y(1)-selective antagonist MRS 2179, and suramin. P2Y(1) receptors were visualized immunohistochemically in the smooth muscle of the ileum and in a subpopulation for myenteric neurones, which also stained for NOS. P2Y(1) mRNA was localized in neurones in both myenteric and submucosal ganglia in the ileum. Taken together, these results suggest that ATP was acting on non-adrenergic, non-cholinergic inhibitory neurons, which release both nitric oxide (NO) and ATP. Reduced relaxations to 2-MeSADP by tetrodotoxin and N(omega)-nitro-L-arginine methyl ester, are consistent with this possibility. Adenosine acts via P1 receptors to relax smooth muscle of the mouse gut. Segments of mouse colon (in contrast to the stomach and small intestine) were contracted by nucleotides with the potency order: 2-MeSATP>alpha,betameATP>ATP; the contractions showed no desensitization and were antagonized by suramin and PPADS, consistent with responses mediated by P2X(2) receptors. Immunoreactivity to P2X(2) receptors was demonstrated on both longitudinal and circular muscle of the colon, but not in the other regions of the gut, except for a small subpopulation of myenteric neurones. In summary, neuronal P2Y(1) receptors appear to mediate relaxation, largely through NO in all regions of the mouse gut, and to a lesser extent by P2Y(1), P2Y(2) and a novel P2Y receptor subtype responsive to alpha,beta-meATP in smooth muscle, while P2X(2) receptors mediate contraction of colonic smooth muscle.

Animals↗
PubMed2002

Ultrastructural identification of P2Y2 receptor mRNA in the rat thymus.

In situ hybridisation to identify P2Y(2) receptor mRNA was performed for the first time at the ultrastructural level on the thymus of adult male rats. These studies revealed transcripts for P2Y(2) receptors in cortical T cells and endothelial cells of thymic blood vessels. These transcripts are likely to be linked with the production of functional P2Y(2) receptors in these cells. In the T cells, transcripts for the P2Y(2 )receptor were localised in the cytoplasm as well as on the smooth endoplasmic reticulum and cell membrane. Dividing T cells also expressed P2Y(2 )receptor mRNA, mostly in the cytoplasm around chromosomal material. Endothelial cells displaying labels for P2Y(2 )receptor transcripts were of cortical arteries/arterioles and capillaries and of postcapillary venules in the corticomedullary junction. P2Y(2) mRNA transcripts were localised in the cytoplasm of endothelial cells, although they did not appear to be specifically associated with subcellular organelles or structures. In postcapillary venules, T cells displaying labelling for the P2Y(2) receptor were seen migrating across the P2Y(2) receptor mRNA-positive endothelium. Our findings are discussed in terms of the relationship between thymic immune cells and the endothelium. This includes the issue of immune cell trafficking into the circulation, and the ATP-related regulatory role and involvement of P2Y(2) receptors in the rat thymus.

Animals↗
PubMed2001

Immunohistochemical identification of cells expressing ATP-gated cation channels (P2X receptors) in the adult rat thyroid.

We carried out immunohistochemistry and western blotting of fresh frozen sections and crude extracts from adult rat thyroids. The histochemical and immunoblotting studies were performed with P2X receptor antibodies from 2 different sources. P2X-immunopositive cells were identified by fluorescence double labelling and confocal microscopy. Results of the western blotting experiments showed double bands of approximately 70 kDa and 140 kDa for all 7 P2X receptor subtypes with both sets of antibodies. Histochemical stains with antibodies from both sources also gave essentially identical results. P2X1, P2X, and P2X6 receptors were detected exclusively in vascular smooth muscle; P2X5 and P2X7 receptors were also present on vascular smooth muscle. Endothelial cells stained for P2X3, P2X4 and P2X7 receptors. Thyroid follicular cells displayed immunoreactivity for P2X3, P2X4 and P2X5 receptors. No immunostaining for P2X receptors was observed on C-cells. Possible roles for the broad expression of P2X receptor subtypes in the rat thyroid are discussed.

Animals↗
PubMed2001

Expression of nucleotide P2X receptor subtypes during spermatogenesis in the adult rat testis.

The expression of ATP-gated ion channels (P2X receptors) was investigated in testes of adult rats by immunohistochemistry and Western blotting with antibodies against all seven P2X receptor subtypes. Immunoreactive cells were identified and monitored during germ cell maturation. Results of immunohistochemical and Western blotting experiments showed the expression of P2X(1), P2X(2), P2X(3), P2X(5) and P2X(7) receptors, while P2X(4) and P2X(6) receptors were absent from the testis. Blood vessels displayed immunostaining for P2X(1) and P2X(2) receptors; the P2X(1) receptors were present exclusively in blood vessels. P2X(2), P2X(3) and P2X(5) receptors were found to be expressed differentially in the various germ cell types throughout the different stages of the cycle of the seminiferous epithelium; P2X(2) and P2X(3) receptors were always observed together in the same cell types and at the same stages. Sertoli cells also showed differential staining for P2X(2) and P2X(3) receptors during the cycle of the seminiferous epithelium, whereas P2X(7) receptor expression was present throughout all stages. No immunostaining for P2X receptors was detected on Leydig cells. The possible roles of purinergic signalling in the control of germ cell maturation are discussed. In particular, it is suggested that purinergic signalling may play a role in controlling the maturation of germ cell subsets of different developmental ages that exist alongside each other in the adult testis.

Animals↗
PubMed2001

Where children sit in cars: the impact of Rhode Island's new legislation.

OBJECTIVES: This study evaluated the impact of Rhode Island's legislation requiring children younger than 6 years to sit in the rear of motor vehicles. METHODS: Roadside observations were conducted in Rhode Island and Massachusetts in 1997 and 1998. Multivariate regression was used to evaluate the proportion of vehicles carrying a child in the front seat. RESULTS: Data were collected on 3226 vehicles carrying at least 1 child. In 1998, Rhode Island vehicles were less likely to have a child in the front seat than in 1997 (odds ratio = 0.6; 95% confidence interval = 0.5, 0.7), whereas no significant changes in child passenger seating behavior occurred in Massachusetts during that period. CONCLUSIONS: Rhode Island's legislation seems to have promoted safer child passenger seating behavior.

Age Factors↗
PubMed2001

Characterization of house dust mite and scabies mite allergens by use of canine serum antibodies.

OBJECTIVE: To identify the major allergenic proteins from the 3 main species of dust mites to which dogs react (Dermatophagoides farinae, D. pteronyssinus, and Euroglyphus maynei) and evaluate the potential cross-reactivity of dust mite allergens with antigens from the ectoparasitic mite Sarcoptes scabiei var canis. SAMPLE POPULATION: Sera from 83 dogs with atopic dermatitis. PROCEDURE: Sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting using serum from atopic dogs was used to identify IgE-binding proteins in extracts of the 4 mite species. RESULTS: Sera of atopic dogs contained IgE against 23, 17, 25, and 17 allergens from D. farinae, D. pteronyssinus, E. maynei, and S. scabiei, respectively. Unlike the situation for humans, the major allergens for dogs are mostly proteins that are larger than 90 kd molecular weight. Dermatophagoides farinae and E. maynei appear to be more allergenic for dogs than is D. pteronyssinus. Some dogs with serum IgE against dust mites also had IgE against antigens of S. scabiei var canis. CONCLUSIONS AND CLINICAL RELEVANCE: Multiple dust mite allergens induce an IgE response in dogs. These allergens are mostly greater than 90 kd molecular weight.

Animals↗
PubMed2000

Rhesus rotavirus-based quadrivalent vaccine is efficacious despite age, socioeconomic conditions and seasonality in Venezuela.

This report describes the results of additional analyses of the trial carried out with the rhesus rotavirus-based quadrivalent vaccine in Venezuela. In the present study, we re-examined the data from this previous rotavirus vaccine trial to assess the statistical interaction between vaccine efficacy and (i) the duration of efficacy into the second year of life, (ii) socioeconomic conditions, and (iii) rotavirus seasonality. We found that among Venezuelan children, the rotavirus vaccine confers protection against severe diarrhea during the first 2 years of life independently of socioeconomic conditions and seasonality.

Age Factors↗
PubMed2000

P2 receptors in the thymus: expression of P2X and P2Y receptors in adult rats, an immunohistochemical and in situ hybridisation study.

The expression of the seven P2X receptor subtypes and of two P2Y receptors was examined immunohistochemically and by in situ hybridisation in thymi of adult male rats. P2X4, P2Y2 and 4 receptor mRNA colocalisation studies combining in situ hybridisation and immunohistochemistry were also carried out. P2X and P2Y receptors were found on thymocytes. P2X receptors were also abundant in cells of the thymic microenvironment, involved in control of T-cell maturation in vivo. We are the first to describe the expression of P2X4 receptors on thymocytes and confirm the finding of P2X1 and P2Y2 receptors on subpopulations of lymphocytes. P2X1,2,3,4 and 5 receptors were present in blood vessels of the thymus. P2X1,2 and 4 receptors were detected in vascular smooth muscle, while P2X3 receptors appeared to be associated with endothelial cells; some small arteries were positive for P2X5, possibly labelling vascular smooth muscle or fibroblasts in the adventitia. P2X2,3,6 and 7 receptors were found on thymic epithelial cells. P2X2 and 3 receptors were abundant on medullary epithelial cells, whilst P2X6 receptors were prominent in Hassall's corpuscles. P2X2 receptors were found on subcapsular and perivascular epithelial cells. P2X2,6 and 7 receptors were detected in epithelial cells along the thymic septa. Expression of P2X receptors was also investigated by Western blotting of crude thymic tissue extracts under reducing conditions. All seven P2X receptor subtypes were found to be dimers of approximately 70 kDa and 140 kDa molecular weight. ATP-mediated apoptosis and cell proliferation of thymocytes are discussed.

Animals↗
PubMed2000

Expression of P2 receptors in bone and cultured bone cells.

Extracellular nucleotides acting through P2 receptors elicit a wide range of responses in many cell types. There is increasing evidence that adenosine triphosphate (ATP) may function as an important local messenger in bone and cartilage. In this study, we used immunocytochemistry, employing novel polyclonal antibodies against P2X(1-7) receptors, and in situ hybridization, using oligonucleotide probes corresponding to P2X(2,4) and P2Y(2,4) messenger RNAs (mRNAs), to localize P2 receptors on undecalcified bone sections and on cultured osteoblasts and osteoclasts. We provide the first direct evidence that the P2X(2) receptor subtype is expressed on osteoclasts, osteoblasts, and chondrocytes. We also obtained evidence for the expression of P2X(5) and P2Y(2) receptors on osteoblasts and chondrocytes, and for P2X(4) and P2X(7) receptors on osteoclasts. Our results confirm earlier reports of P2Y(2) and P2X(4) expression in human osteoclastoma and rabbit osteoclasts, respectively, and are consistent with ATP responses observed on bone cells using electrophysiological techniques. Our novel finding that P2X(2) is expressed by osteoclasts is of particular interest. P2X(2) is the only P2 receptor subtype that requires extracellular acidification to show its full sensitivity to ATP, and our recent functional studies have shown that the stimulatory action of ATP on resorption pit formation by mature osteoclasts is amplified greatly at low pH. These findings point to fundamental new mechanisms for the local modulation of bone resorption.

Adenosine Triphosphate↗
PubMed2000

Lactulose-mannitol intestinal permeability test in children with diarrhea caused by rotavirus and cryptosporidium. Diarrhea Working Group, Peru.

BACKGROUND: The relationship between intestinal permeability and acute secretory diarrheal syndromes caused by rotavirus and Cryptosporidium parvum in infants less than 36 months of age was studied using the lactulose-mannitol excretion assay. METHODS: An oral solution containing 0.4 g/kg lactulose and 0.1 g/kg mannitol was administered to 15 infants with rotavirus, 7 with Cryptosporidium infection and a control group of 7 with secretory diarrhea admitted to the Oral Rehydration Unit of the National Children's Hospital in Lima, Peru. Urinary sugar excretion was measured using an enzymatic spectrophotometric method. The ratio of urinary excretion of lactulose to mannitol was used to measure intestinal mucosal permeability, with higher ratios indicative of increased intestinal permeability. Infants in all three groups were retested 20 days after the initial test. RESULTS: The (mean +/- SE) lactulose:mannitol (L:M) excretion ratios during the acute phase (day 1) of diarrhea in infants with rotavirus or Cryptosporidium and control infants were 0.67 +/- 0.1, 0.76 +/- 0.16, and 0.26 +/- 0.04, respectively. In the convalescent phase (day 20) the ratios were 0.19 +/- 0.02, 0.28 +/- 0.05, and 0.29 +/- 0.07, respectively. Significant reductions in L:M ratios were noted in rotavirus patients between days 1 and 20 (paired t-test; P < 0.01), Cryptosporidium patients between days 1 and 20 (paired t-test; P < 0.05), and between control subjects on day 1 and rotavirus patients on day 1 and Cryptosporidium patients on day 1 (unpaired t-tests; P < 0.05 for both). There were no significant differences in control subjects between days 1 and 20, control subjects and rotavirus patients on day 20, or control subjects and Cryptosporidium patients on day 20. CONCLUSIONS: The results indicate that increased intestinal permeability caused by rotavirus or cryptosporidium infections in Peruvian infants less than 36 months of age is a significant but reversible phenomenon. The temporal relationship observed in the current study and the contribution of such alterations in intestinal mucosal integrity to the burden of diarrheal disease and the development of malnutrition in developing countries is discussed.

Animals↗
PubMed2000

Development of fiber optic and electrochemical pH sensors to monitor brain tissue.

This article describes fiber optic and electrochemical pH sensors that could become part of a therapeutic arsenal to quickly and aggressively treat stroke victims as well as people who have suffered brain trauma. The fiber optic sensor design was based on the immobilization of a pH-sensitive dye, seminaphthorhodamine-1 carboxylate (SNARF-1C), onto the end of a 125-microm-diameter silica optical fiber using the sol-gel method. A miniature bench-top fluorimeter system was developed for use with the optical fiber to obtain pH measurements. The electrochemical sensor was based on sputter-coated iridium oxide thin films. Linear and reproducible responses for both sensors were obtained in human blood with pH varying between 6.8 ato 8.0, which encompasses the clinically relevant range. In vivo studies were also performed and results indicated that both types of sensors tracked pH with very little drift.

Animals↗
PubMed1999

Structure of branched DNA molecules: gel retardation and atomic force microscopy studies.

DNA heteroduplexes as models for slipped strand DNA have been analyzed by polyacrylamide gel migration and atomic force microscopy (AFM). All heteroduplexes containing one hairpin or loop have reduced electrophoretic mobilities compared with that expected for their molecular weights. The retarded gel mobility correlates with the formation of a sharp kink detected by AFM. Increasing the hairpin length from 7 bp to 50 bp results in a monotonous decrease in gel mobility of heteroduplexes. This secondary retardation effect appears to depend only on the hairpin size since the AFM data show no dependence of the kink angle on the hairpin length. Heteroduplex isomers with a loop or hairpin in opposite strands migrate with distinct mobilities. Analysis of gel migration of heteroduplexes with altered hairpin orientations as well as of truncated heteroduplexes indicates that the difference in mobility is due to an inherent curvature in one of the long arms. This is confirmed by the end-to-end distance measurements from AFM images. In addition, significant variation of the end-to-end distances is consistent with a dynamic structure of heteroduplexes at the three-way junction. Double heteroduplexes containing one hairpin in each of the complementary strands also separate in a gel as two isomers. Their appearance in AFM showed a complicated pattern of flat representations of the three-dimensional structure and may indicate a certain degree of interaction between complementary parts of the hairpins that are several helical turns apart.

Base Sequence↗
PubMed1999

Social capital and self-rated health: a contextual analysis.

OBJECTIVES: Social capital consists of features of social organization--such as trust between citizens, norms of reciprocity, and group membership--that facilitate collective action. This article reports a contextual analysis of social capital and individual self-rated health, with adjustment for individual household income, health behaviors, and other covariates. METHODS: Self-rated health ("Is your overall health excellent, very good, good, fair, or poor?") was assessed among 167,259 individuals residing in 39 US states, sampled by the Behavioral Risk Factor Surveillance System. Social capital indicators, aggregated to the state level, were obtained from the General Social Surveys. RESULTS: Individual-level factors (e.g., low income, low education, smoking) were strongly associated with self-rated poor health. However, even after adjustment for these proximal variables, a contextual effect of low social capital on risk of self-rated poor health was found. For example, the odds ratio for fair or poor health associated with living in areas with the lowest levels of social trust was 1.41 (95% confidence interval = 1.33, 1.50) compared with living in high-trust states. CONCLUSIONS: These results extend previous findings on the health advantages stemming from social capital.

Adult↗