Biomedical subjects

Jesús Marín

Publications and source records attributed to Jesús Marín.

4 recordsLinked to original sources

PubMed2005

Respiratory syncytial virus-related bronchiolitis in Puerto Rico.

BACKGROUND: Respiratory syncytial virus (RSV) is an important cause of respiratory tract disease in infants and young children. Immunoprophylaxis is available for high-risk infants. This study reviews infants with bronchiolitis at three primary care hospitals to describe the epidemiology of RSV infection in Puerto Rico. METHODS: We analyzed data from 2 hospitals by obtaining the number of infants diagnosed with bronchiolitis and estimating the percentage of cases due to RSV. A third hospital included patients with confirmed RSV infection. RESULTS: There were 4,557 patients in the study. RSV infection occurred throughout the year. Data shows a progressive decrease in RSV-positive infections. CONCLUSIONS: Data confirms year-round incidence of RSV in Puerto Rico. A standardized surveillance system in Puerto Rico is imperative to determine RSV epidemiology. The decrease in positive RSV infections may be due to the introduction of immunoprophylaxis to high-risk patients.

Bronchiolitis↗

PubMed2003

Administration of N(omega)-L-arginine methyl ester (L-NAME) impairs endothelium-dependent relaxation in gravid but not nongravid rats.

OBJECTIVE: To characterize the impairment of endothelium-dependent relaxation induced by administration of the nitric oxide synthase (NOS) inhibitor N(omega)-L-arginine methyl ester (L-NAME) to gravid rats and to determine whether L-NAME affects nongravid rats in a similar manner. METHODS: Acetylcholine (ACh; 0.01-10 microM) relaxation was studied in aortic segments (contracted with 10 nM norepinephrine) from Wistar rats that were hypertensive after receiving L-NAME (0.5 mg/mL in drinking water) before gravidity (hypertensive virgin rats [HVR]), during gravidity (hypertensive gravid rats [HGR]), or during the last 10 days of gravidity to 24 hours postpartum (hypertensive puerperal rats [HPR]). We also studied aortic segments from corresponding groups of untreated normotensive rats (normotensive gravid rats [NGR], normotensive puerperal rats [NPR], and normotensive virgin rats [NVR]). The approximate participations of NO and the hyperpolarizing mechanisms in ACh relaxation were calculated from the reduction of relaxation observed, respectively, after incubation with the NOS inhibitor N(G)-monomethyl-L-arginine (L-NMMA, 0.1 mM) or after contraction with 50 mM of potassium chloride. Expression of endothelial NOS protein was studied by Western blot in segments of HGR and NGR. RESULTS: Acetylcholine relaxation was reduced in HGR compared with NGR, and this reduction correlated with the severity of hypertension. In contrast, ACh relaxation in HVR was similar to that in NVR, and that of HPR was similar to that in NPR. The NO component of relaxation was reduced in HGR but preserved in the other groups. Nevertheless, there were no differences in endothelial NOS protein expression between NGR and HGR. The hyperpolarizing component in relaxation was enhanced in HVR and HPR but not HGR. CONCLUSION: Administration of L-NAME induced an impairment of endothelium-dependent relaxation, involving both nitric oxide- and hyperpolarizing-dependent mechanisms in gravid but not virgin rats; this impairment resolved with delivery.

Acetylcholine↗

PubMed2002

Controlling chaos in unidimensional maps using macroevolutionary algorithms.

We introduce a simple search algorithm that explores the parameter of periodically perturbed discrete maps in order to find desired orbits through chaos control. The method has been applied to one-dimensional maps but is easily extendable to higher-dimensional systems. Here, we consider two types of chaos control involving proportional pulses in the system variables [Phys. Rev. Lett. 72, 1455 (1994)] and constant feedback [Phys. Rev. E 51, 6239 (1995)], the first case being presented in detail. It is shown that our method allows a rapid exploration of parameter space and the finding of high-fitness (i.e., controlled) solutions close to the target orbits, even when high periodicities are required.

Journal Article↗

PubMed2002

Alterations in phenylephrine-induced contractions and the vascular expression of Na+,K+-ATPase in ouabain-induced hypertension.

Hypertension development, phenylephrine-induced contraction and Na(+),K(+)-ATPase functional activity and protein expression in aorta (AO), tail (TA) and superior mesenteric (SMA) arteries from ouabain- (25 microg day(-1), s.c., 5 weeks) and vehicle-treated rats were evaluated. Ouabain treatment increased systolic blood pressure (127+/-1 vs 160+/-2 mmHg, n=24, 35; P<0.001) while the maximum response to phenylephrine was reduced (P<0.01) in AO (102.8+/-3.9 vs 67.1+/-10.1% of KCl response, n=12, 9) and SMA (82.5+/-7.5 vs 52.2+/-5.8%, n=12, 9). Endothelium removal potentiated the phenylephrine response to a greater extent in segments from ouabain-treated rats. Thus, differences of area under the concentration-response curves (dAUC) in endothelium-denuded and intact segments for control and ouabain-treated rats were, respectively: AO, 56.6+/-9.6 vs 198.3+/-18.3 (n=9, 7); SMA, 85.5+/-15.4 vs 165.4+/-24.8 (n=6, 6); TA, 13.0+/-6.1 vs 39.5+/-10.4% of the corresponding control AUC (n=6, 6); P<0.05. The relaxation to KCl (1 - 10 mM) was similar in segments from both groups. Compared to controls, the inhibition of 0.1 mM ouabain on KCl relaxation was greater in AO (dAUC: 64.8+/-4.6 vs 84.0+/-5.1%, n=11, 14; P<0.05), similar in SMA (dAUC: 39.1+/-3.9 vs 43.3+/-7.8%, n=6, 7; P>0.05) and smaller in TA (dAUC: 62.1+/-5.5 vs 41.4+/-8.2%, n=12, 13; P<0.05) in ouabain-treated rats. Protein expression of both alpha(1) and alpha(2) isoforms of Na(+),K(+)-ATPase was augmented in AO, unmodified in SMA and reduced in TA from ouabain-treated rats. These results suggest that chronic administration of ouabain induces hypertension and regional vascular alterations, the latter possibly as a consequence of the hypertension.

Animals↗