Biomedical subjects

Jorge López

Publications and source records attributed to Jorge López.

6 recordsLinked to original sources

PubMed2006

Effects of estradiol on phenylephrine contractility associated with intracellular calcium release in rat aorta.

The ability of estradiol to affect phenylephrine-induced contraction and the subsequent increase in resting tone, associated with capacitative Ca(2+) entry across the plasma membrane, was evaluated in rat aortic rings incubated in Ca(2+)-free solution. The incubation with estradiol (1-100 nM, 5 min) inhibited both the phenylephrine-induced contraction and the IRT. Neither cycloheximide (1 microM; inhibitor of protein synthesis) nor tamoxifen (1 microM; blocker of estrogenic receptors) modified the effects of estradiol. Estradiol (100 microM) also blocked the contractile response to serotonin (10 microM) but not to caffeine (10 mM). In addition, estradiol (100 microM) inhibited the contractile responses to cyclopiazonic acid (1 microM; selective Ca(2+)-ATPase inhibitor) associated with capacitative Ca(2+) influx through non-L-type Ca(2+) channels. Finally, estradiol inhibited the Ca(2+)-induced increases in intracellular free Ca(2+) (after pretreatment with phenylephrine) in cultured rat aorta smooth muscle cells incubated in Ca(2+)-free solution. In conclusion, estradiol interfered in a concentration-dependent manner with Ca(2+)-dependent contractile effects mediated by the stimuli of alpha(1)-adrenergic and serotonergic receptors and inhibited the capacitative Ca(2+) influx through both L-type and non-L-type Ca(2+) channels. Such effects are in essence nongenomic and not mediated by the intracellular estrogenic receptor.

Animals↗

PubMed2005

Risk factors for hepatitis B and C in multi-transfused patients in Uruguay.

BACKGROUND: In spite of the progress made in the prevention of transfusion-transmitted infections over the last years, these still occur. It was considered that infection by hepatitis B (HBV) and C (HCV) viruses could be a major problem in Uruguay, especially among high-risk individuals, such as multi-transfused patients. OBJECTIVES: To assess the prevalence of HBV and HCV infection among multi-transfused Uruguayan patients and the impact of serological screening; to evaluate the role of number of transfusions and other potential risk factors for the acquisition of HBV and HCV infection. STUDY DESIGN: Cross-sectional study of HCV antibodies, HBV surface antigen (HBsAg) and HBV core antibodies (HBcAc) in 409 multi-transfused patients. RESULTS: Of 409 patients studied, 147 (35.9%) received blood products due to acute bleeding, 118 (28.9%) were hemato-oncological, 75 (18.3%) hemophiliacs, 64 (15.6%) were on hemodialysis and 5 (1.2%) suffered sickle cell anemia. Prevalence of HCV antibody was 12.7%. Of the HCV positive patients, 45 were hemophiliacs, for a prevalence rate of 60.0%. The prevalence rates for hemodialysis and acute bleeding patients were 6.3% and 2.0%, respectively. Prevalence of HBsAg was 1.0%; 16.6% of subjects were positive for HBcAc. The prevalence rates of HBcAc were 48.0%, 15.0% and 3.1% among hemophiliacs, acute bleeding and hemodialysis patients, respectively. There was a direct relationship between the number of products transfused and prevalence of both hepatitis C antibodies and HBcAc. Higher prevalence of HCV and HBcAc was observed among the group of patients who received transfusions before the systematic screening of blood donors. CONCLUSIONS: Exposure to blood transfusions was the main risk factor for HCV and HBV infection. The systematic serological screening of blood donors was highly effective in reducing transfusion transmitted infections.

Adolescent↗

PubMed2004

Use of percutaneous tracheostomy in intensive care units in Spain. Results of a national survey.

OBJECTIVES: To assess the use of percutaneous tracheostomy in Intensive Care Units (ICU) in Spain, its practice, and current opinions on the technique. DESIGN AND SETTING: An e-mail or post survey was sent to 239 Spanish ICU directors. Pediatric ICUs and coronary units were excluded. MEASUREMENTS AND MAIN RESULTS: One hundred ICUs (41.8%) replied. The 44% ( n=44) of the ICUs that answered belonged to university hospitals and 53% ( n=53) had postgraduate teaching. Eighty-two percent ( n=82) used percutaneous tracheostomy. Griggs' Guide Wire Dilating Forceps and Ciaglia Blue Rhino were the most frequent techniques employed. In 30.5% of ICUs ( n=25) endoscopic guidance was used, in 15.7% ( n= 13) it was routine. In 24.4% ( n=20) some kind of long-term follow-up was carried out, but only in 12.2% ( n=10) was follow-up done routinely. In 58.5% of ICUs ( n=48) in which percutaneous tracheostomy is performed is this technique considered safer than surgical tracheostomy and in 86.4% ( n=70) percutaneous tracheostomy is the first choice for tracheostomy in the critically ill patient. CONCLUSIONS: Percutaneous tracheostomy is a well-established technique in ICUs in Spain, and is considered the technique of choice for tracheostomy in critically ill patients. It is mainly performed without endoscopic guidance and follow-up is not usually carried out.

Dilatation↗

PubMed2003

Ultraviolet vision in a bat.

Most mammals, with the exception of primates, have dichromatic vision and correspondingly limited colour perception. Ultraviolet vision was discovered in mammals only a decade ago, and in the few rodents and marsupials where it has been found, ultraviolet light is detected by an independent photoreceptor. Bats orient primarily by echolocation, but they also use vision. Here we show that a phyllostomid flower bat, Glossophaga soricina, is colour-blind but sensitive to ultraviolet light down to a wavelength of 310 nm. Behavioural experiments revealed a spectral-sensitivity function with maxima at 510 nm (green) and above 365 nm (ultraviolet). A test for colour vision was negative. Chromatic adaptation had the same threshold-elevating effects on ultraviolet and visible test lights, indicating that the same photoreceptor is responsible for both response peaks (ultraviolet and green). Thus, excitation of the beta-band of the visual pigment is the most likely cause of ultraviolet sensitivity. This is a mechanism for ultraviolet vision that has not previously been demonstrated in intact mammalian visual systems.

Adaptation, Physiological↗

PubMed2002

Effect of a glutamine-enriched enteral diet on intestinal permeability and infectious morbidity at 28 days in critically ill patients with systemic inflammatory response syndrome: a randomized, single-blind, prospective, multicenter study.

We investigated the effect of a glutamine-enriched enteral diet on intestinal permeability and infectious morbidity and mortality in critically ill patients who developed systemic inflammatory response syndrome after an acute event. Eleven intensive care units in tertiary-care hospitals participated in a prospective, randomized, single blind, multicenter trial. Eighty-four patients with systemic inflammatory response syndrome of any etiology were randomly allocated to receive a glutamine-enriched enteral diet or a control diet without glutamine.Most patients received the planned caloric intake. The number of infected patients was smaller in the glutamine group than in the control group (11 versus 17 patients, P < 0.05), with a relative risk of 0.5 (95% confidence interval = 0.3-0.9). The most frequent infection was nosocomial pneumonia, with 11 (33%) patients in the control group and 6 (14%) in the glutamine group. There were no differences with respect to other infections, mortality, or length of stay. Intestinal permeability as assessed by the lactulose-mannitol test was unchanged in both groups.Glutamine-enriched enteral diets can decrease nosocomial infections in patients with systemic inflammatory response syndrome.

Acute Disease↗

PubMedDate not supplied

[Testosterone inhibits the contractile responses to phenylephrine associated with the release of intracellular calcium in rat aorta].

Using endothelium-denuded rat aortic rings incubated in Ca2+ -free solution, we assessed the ability of testosterone to influence the contractile effect of phenylephrine, and the increase in resting tone (IRT) associated with Ca2+ ability to cross the plasma membrane. The addition of testosterone [10(-5)-10(-4) 5 min before phenylephrine [10(-6) M], inhibited both phenylephrine-induced contraction and IRT. These changes were not affected by cycloheximide (10(-5) M; a protein synthesis inhibitor of), flutamide (10(-5) M; an androgenic receptor antagonist), or by adding aminoglutethimide (10(-5) M; an aromatase inhibitor). Testosterone also blocked the contractile response to serotonin [10(-5) M] but not to caffeine [10(-2) M]. On the other hand, testosterone inhibited the contractile responses to cyclopiazonic acid (10(-6) M; a selective Ca2+ -ATPase inhibitor) or ryanodine (10(-5 M; an activator of sarcoplasmic reticulum Ca2+ -release channels) associated with capacitative Ca2+ influx through non-L-type Ca2+ channels. These data suggest that by acting on the cellular membrane, testosterone interferes with the signal transduction pathway of G(q-11) protein-coupled receptors, and inhibits capacitative Ca2+ influx through both L-type and non-L-type Ca2+ channels. These effects are non-genomic, non-mediated by the intracellular androgen receptor, and not due to the conversion of testosterone to estrogens.

Animals↗