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Biomedical subjects

M Ros

Publications and source records attributed to M Ros.

At least 37 records · Page 2Linked to original sources
PubMed1998

Desensitization of adenosine A1 receptor-mediated inhibition of adenylyl cyclase in cerebellar granule cells.

Agonist-induced desensitization of adenosine A1 receptor-mediated inhibition of adenylyl cyclase has been studied in cerebellar granule cells. Exposure of cells to the adenosine A1 receptor agonist R-phenylisopropyl adenosine (R-PIA) from 2 to 48 h brings about desensitization of this signal transduction pathway. Associated with the desensitization process, a decrease in radioligand binding performed in intact cells with the adenosine A1 receptor agonist [3H]cyclohexyladenosine (CHA) has been detected. Simultaneously, an increase of adenosine A1 radioligand binding has also been detected in microsomes. A decrease in the steady-state level of alpha-Gi in both, plasma membrane and microsomes also has been detected during the desensitization process. These data may account for the desensitization of the inhibitory pathway of the adenylyl cyclase in cerebellar granule cells described herein. After a transient increase in adenosine A1 receptor mRNA, no changes were observed in this parameter after 12 hr of treatment with the adenosine A1 agonist R-PIA, suggesting a post-transcriptional regulation of this receptor during long-term desensitization.

Adenosine↗
PubMed1998

The federated healthcare record to support shared diabetes care.

In this paper the conception of the federated healthcare record server to support shared diabetes care is described. Business process modelling is applied to describe the shared care for diabetes patients. Typical dialogues between the different users (patient, internist, GPs, and diabetic nurses) are analysed and described in terms of use cases. Next to this modelling three incremental steps are defined to realise the record server based upon results of standardisation. It proves to be successful to design and build this record server on modern technologies like CORBA and JAVA.

Computer Communication Networks↗
PubMed1997

Rapid determination of p-aminohippuric acid in serum and urine by high-performance liquid chromatography.

We report a simple and rapid HPLC procedure for measuring p-aminohippuric acid in serum and urine. After deproteinization with acetonitrile and addition of p-aminobenzoic acid as an internal standard, the chromatographic run is performed on a C18 column with the absorbance detector set at 275 nm. The separation is carried out in 10 min at a flow-rate of 1.0 ml/min with a mobile phase composed of 7 mmol/l 1-decanesulfonic acid, pH 3.70, and acetonitrile (82:18, v/v). The relationship between p-aminohippuric acid concentration and the p-aminohippuric acid/internal standard peak area is linear up to 100 microg/ml. Within-run precision measured at three different p-aminohippuric acid concentrations ranges from 1.73 to 1.98% in serum and from 0.72 to 1.32% in urine. Between-run precision varies from 1.80 to 4.06% in serum and from 1.05 to 2.66% in urine. Analytical recovery is between 98.26 and 99.44% in serum and from 99.57 to 100.45% in urine. The method is very simple, sensitive, and requires small volumes of sample for the assay (100 microl). Therefore, it could be a useful tool for the analysis of p-aminohippuric acid in the evaluation of renal plasma flow.

Adult↗
PubMed1997

Characterization of metabotropic glutamate receptors in rat C6 glioma cells.

Metabotropic glutamate receptors in rat C6 glioma cells have been characterized by pharmacological and kinetic binding experiments, using both L-[3H]glutamate and [3H(+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid ([3H](+/-)-trans-ACPD) radioligands. Saturation experiments revealed a single binding site with a Kd = 1250 +/- 101 nM and Bmax = 12.1 +/- 1.8 pmol/mg protein when the assays were performed with L-[3H]glutamate as radioligand in the presence of AMPA, kainate, NMDA and DL-threo-beta-hydroxyaspartic acid. When [3H](+/-)-trans-ACPD was used as radioligand, the kinetic parameters obtained were Kd = 2605 +/- 1042 nM and Bmax = 13.66 +/- 5.01 pmol/mg protein. Pharmacological characterization indicated that specific binding of L-[3H]glutamate was sensitive to different agonists of mGlu receptors, showing a rank order of affinity L-glutamate > L-quisqualic acid > (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD) > ibotenic acid >>> (2S, 'S,2'S)-2-(carboxycyclopropyl)glycine (L-CCG-I). Specific binding of L-[3H]glutamate to mGlu receptors is regulated by guanine nucleotides. Guanylyl imidodiphosphate (Gpp(NH)p) causes an affinity shift on the L-glutamate dose-response curve, increasing the IC50 value. These results support the evidence that metabotropic glutamate receptors are present in rat C6 glioma cells and they are coupled to a G-protein.

Animals↗
PubMed1997

Supporting shared care for diabetes patients. The synapses solution.

In this paper we discuss the construction of a Federated Health Care Record server within the context of the European R&D project Synapses. We describe the system using the five ODP viewpoints. From an analysis of the business process to be supported by the distributed system (the shared care for diabetes patients) requirements for the server are derived.

Computer Communication Networks↗
PubMed1996

[Tuberculosis in recent immigrants in Barcelona].

BACKGROUND: The aim of the present was to study the prevalence of infection and tuberculous disease as well as the fulfillment of secondary antituberculin chemoprophylaxis in immigrants according to their geographic origin. PATIENTS AND METHODS: A descriptive study was carried out of 1,489 immigrants under the age of 35 years attended in the Tropical and Imported Disease Unit Drassanes in Barcelona, Spain from 1989 to 1994. RESULTS: The patients were from 79 countries, with 81.7% being males and 18.3% females (p < 0.001) of a mean age 26.1 +/- 5.7 and 23.4 +/- 7.5 years, respectively. Forty-three percent of the cases presented Mantoux test response > or = 10 mm of induration. The highest percent of positivity was observed in patients from Subsaharian Africa (52%) followed by Eastern Europeans and Asians (44%), South and Central Americans (38%) and Middle East and Northern Africa (34%) (p < 0.001). Thirty-nine percent of the 359 patients who initiated secondary antituberculin chemoprophylaxis completed the 6 months of treatment with the highest fulfillment being found in Africans (49%) followed by Americans (42%) and Asians (39%). The lowest rate was observed in the Eastern Europeans (20%) (p < 0.001). Fifty-six percent of the patients abandoned secondary antituberculin prophylaxis within the first three months. Eighteen cases of active tuberculosis were diagnosed. CONCLUSIONS: The prevalence of tuberculous infection and disease is high immigrants in Barcelona, Spain. The fulfillment of chemoprophylaxis is low and abandoned early. These facts should be evaluated when designing prevention and control programs.

Adult↗
PubMed1996

Desensitization and internalization of adenosine A1 receptors in rat brain by in vivo treatment with R-PIA: involvement of coated vesicles.

Chronic treatment of rats with R-PIA 'in vivo' desensitized adenosine A1 receptor-mediated inhibition of adenylyl cyclase in brain plasma membranes and increased basal and forskolin-stimulated adenylyl cyclase. The adenosine A1 receptor agonist CHA (cyclohexyl adenosine) inhibited forskolin-stimulated adenylyl cyclase in synaptic plasma membranes from control rats but failed to do so in membranes isolated from rats treated with R-PIA. This loss of response was accompanied with a significant decrease in both, total number of adenosine A1 receptors and steady-state level of alpha-Gi in synaptic plasma membranes. An increase in the steady-state level of alpha-Gs in synaptic plasma membranes was also observed by R-PIA treatment. Concurrently, a significant increase of adenosine A1 receptors was observed in microsomes and coated vesicles. These results demonstrate adenosine A1 receptor desensitization in rat brain by 'in vivo' treatment with R-PIA and suggest a role for coated vesicles in the internalization of G-protein coupled receptors.

Adenosine↗
PubMed1996

Adenosine A1 receptors in cultured cerebellar granule cells: role of endogenous adenosine.

Adenosine A1 receptors as well as other components of the adenylate cyclase system have been studied in cultured cerebellar granule cells. No significant changes in adenosine A1 receptor number, assayed by radioligand binding in intact cells, were detected from 2 days in vitro (DIV) until 7 DIV. Nevertheless, a decline in this parameter was detected at 9 DIV. The steady-state levels of alpha-Gg and alpha-Gi, detected by immunoblotting, showed similar profiles, increasing from 2 to 5 DIV and decreasing afterward. Forskolin-stimulated adenylate cyclase levels also showed an increase until 5 DIV, decreasing at 7 and 9 DIV. The adenosine A1 receptor analogue cyclopentyladenosine (CPA) was able to inhibit cyclic AMP accumulation at 2, 5, and 7 DIV but failed to do so at 9 DIV. This inhibition was prevented by the specific adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. The presence of adenosine deaminase in the culture increased adenosine A1 receptor number during the period studied and induced recovery of the inhibitory effect of CPA, lost after 7 DIV. These data suggest that functional expression of adenosine A1 receptors and the other components of the adenylate cyclase system is subjected to regulation during the maturation of cultured cerebellar granule cells and demonstrates a key role for endogenous adenosine in the process.

Adenosine↗
PubMed1995

Metabotropic glutamate receptor analogues inhibit p[NH]ppG-stimulated phospholipase C activity in bovine brain coated vesicles: involvement of a pertussis toxin-sensitive G-protein.

Guanosine 5'-[beta gamma-imido]triphosphate (p[NH]ppG)-stimulated phospholipase C (PLC) activity in bovine brain coated vesicles is inhibited by glutamate agonists. In the present study we show that quisqualic acid (QA), (+/-)-trans-1-aminocyclopentane-1,3-dicarboxylate (trans-ACPD), glutamic acid and ibotenic acid inhibited p[NH]ppG-stimulated PLC by 44, 41, 36 and 25% respectively. Carbachol also produced an inhibition of p[NH]ppG-stimulated PLC by 45%. The inhibition caused by trans-ACPD and QA was dose-dependent. DL-2-Amino-3-phosphonopropionic acid and (RS)-alpha-methyl-4-carboxyphenylglycine, specific antagonists of metabotropic glutamate receptors (mGluRs), abolished these inhibitory effects. trans-ACPD inhibition of p[NH]ppG-stimulated PLC was also observed in the presence of ionotropic glutamate receptor antagonists. When carbachol and QA or trans-ACPD were combined, additive inhibitory effects were observed. Preincubation of bovine brain coated vesicles with pertussis toxin abolished the inhibitory effects of mGluR analogues and carbachol on p[NH]ppG-stimulated PLC activity. The presence of Gs alpha and pertussis toxin substrates, Gi alpha and Go alpha subunits as well as PLC beta 1 in bovine brain coated vesicles has been confirmed by immunoblot. These results support the coupling of mGluRs to a PLC in an inhibitory manner through a pertussis toxin-sensitive G-protein in bovine brain coated vesicles.

Animals↗
PubMed1994

Bromocriptine treatment increases lipolysis and steady-state levels of G proteins in adipocytes from lactating rats.

An increase in the rate of lipogenesis and a decrease in the lipolytic response to catecholamines can be observed in adipocytes after weaning or litter removal. Bromocriptine treatment of lactating rats also produces an increase in lipogenesis but fails to decrease the lipolytic response of adipocytes to catecholamines seen after weaning or litter removal. No changes in total number or affinity of beta-adrenergic receptors or adenosine A1 receptors were detected by bromocriptine treatment using radioligand binding assays. However, we observed an increase in the amount of radioactivity from [32P]NAD+ incorporated into alpha-Gs (192 +/- 26%) and alpha-Gi (178 +/- 33%) by cholera- and pertussis-toxin-catalyzed ADP-ribosylation, respectively, with the same treatment, Immunoblotting using RM/1 and AS/7 antisera, which specifically recognize alpha-Gs and alpha-Gi 1,2, respectively, confirmed the increase in the steady-state levels of these G-protein alpha-subunits. The increase in the steady-state levels of alpha-Gs may account, at least in part, for the increased lipolytic response of adipocytes to catecholamines in bromocriptine-treated rats.

Adenosine↗
PubMed1994

The prevalence of respiratory disorders in panic disorder, major depressive disorder and V-code patients.

Point prevalence and lifetime prevalence of respiratory disorders were assessed in 100 panic disorder (PD), 100 major depressive disorder (DD) and 100 V-code (VC) patients. Both current and past frequency of respiratory diseases were significantly higher in PD patients in comparison to VC patients, while no significant differences in point and lifetime prevalence between PD and DD or DD and VC patients were observed. It is hypothesized that a disturbed respiratory physiology may have differential effects depending upon the nature of the disorder and the appraisal by the patient.

Adult↗
PubMed1992

Time-resolved ultraviolet resonance Raman studies of protein structure: application to bacteriorhodopsin.

Time-resolved ultraviolet resonance Raman spectra of bacteriorhodopsin are used to study protein structural changes on the nanosecond and millisecond time scales. Excitation at 240 nm is used to selectively enhance vibrational scattering from tyrosine so that changes in its hydrogen bonding and protonation state can be examined. Both nanosecond and millisecond UV Raman difference spectra indicate that none of the tyrosine residues change ionization state during the BR----K and BR----M transitions. However, intensity changes are observed at 1172 and 1615 cm-1 in the BR----M UV Raman difference spectra. The 1615-cm-1 feature shifts down 25 cm-1 in tyrosine-d4-labeled BR, consistent with its assignment as a tyrosine vibration. The intensity changes in the BR----M UV Raman difference spectra most likely reflect an increase in resonance enhancement that occurs when one or more tyrosine residues interact more strongly with a hydrogen-bond acceptor in M412. The frequency of the v7a feature (1172 cm-1) in the BR----M UV Raman difference spectra supports this interpretation. The proximity of Tyr-185 and Asp-212 in the retinal binding pocket suggests that deprotonation of the Schiff base in M412 causes Tyr-185 to stabilize ionized Asp-212 by forming a stronger hydrogen bond.

Bacteriorhodopsins↗
PubMed1992

Dipyridamole stimulates types II cAMP-dependent protein kinase in vitro.

Dipyridamole activates in vitro type II cAMP-dependent protein kinase. This agent stimulates the autophosphorylation of the regulatory subunit in the presence of cAMP but not so in the absence of the cyclic nucleotide. The activation was also observed with exogenous substrates such as casein, histone 2A and MAP2. This stimulation did not seem to be related to the cAMP binding to the R II subunit of the enzyme. Competition binding experiments showed that dipyridamole does not compete with adenosine for the A1 receptor. The results suggest that the reported regulatory properties of dipyridamole on lipid metabolism (González-Nicolás et al. Int J Biochem 21: 883-888, 1989) might be mediated through a direct action--an activation--on the catalytic subunit of a cAMP-dependent protein kinase.

Adipose Tissue↗
PubMed1992

Effects of litter removal on the lipolytic response and the regulatory components of the adenylate cyclase in adipocytes isolated from lactating rats.

The effects of litter removal on the status of different components of the hormone-sensitive adenylate cyclase system were analysed in plasma membranes of rat adipocytes. These effects were correlated with the decreased lipolytic response of adipose tissue. No changes in total number of A1 adenosine receptors or their affinity were detected in response to litter removal. In contrast, beta-adrenergic receptors showed a decrease (35%) in total number of receptors, without any significant change in their affinity. The status of alpha-GS and alpha-Gi, the alpha-subunits of G proteins which mediate stimulation and inhibition respectively of adenylate cyclase, were probed by cholera- and pertussis-toxin-catalysed ADP-ribosylation respectively and by immunoblot. Associated with litter removal, decreases of 63% and 62% in the incorporation of [alpha 32P]ADP-ribose catalysed by cholera toxin and pertussis toxin into alpha-Gs and alpha-Gi respectively were detected. Immunoblotting using RM/1 (anti-alpha-Gs) and AS/7 (anti-alpha-Gi) antisera also showed decreases in the levels of alpha-Gs (52%) and alpha-Gi (55%) in adipocyte membranes from litter-removed rats compared with lactating rats. Alterations in the status of hormone-sensitive adenylate cyclase components, such as those described herein, may be biochemical mechanism(s) by which adipose tissue shows a decreased lipolytic response during recovery from lactation.

Adenylyl Cyclases↗
PubMed1991

Presence of phospholipase C in coated vesicles from bovine brain. Dual regulatory effects of GTP-analogs.

Bovine brain coated vesicles display free calcium-dependent phospholipase C activity. Gpp(NH)p and GTP gamma S inhibited phospholipase C at nanomolar concentrations. Increasing concentrations of Gpp(NH)p and GTP gamma S reversed the inhibitory effects and stimulated phospholipase C activity. Preincubation of coated vesicles with pertussis toxin blocked the poorly-hydrolyzable GTP-analogs' inhibitory effects on phospholipase C. These data indicate that guanine nucleotides exert a dual regulatory control of phospholipase C in coated vesicles and that the inhibitory pathway is mediated by a pertussis toxin-sensitive G-protein.

Animals↗