PubMed Health⌕ Search

Biomedical subjects

A García

Publications and source records attributed to A García.

At least 235 records · Page 13Linked to original sources
PubMed1997

[Beta-blockers in cardiac insufficiency: should they always be considered in the therapeutic strategy? Arguments against].

The evidence supporting the use of beta-adrenergic blockers in the treatment of heart failure secondary to systolic dysfunction is reviewed. Up to date, seven controlled trials of carvedilol in patients with heart failure have been published. It has been concluded that the use of the non-selective, third generation beta-adrenergic blockers, with alpha-adrenergic (vasodilator) and antioxidant properties, carvedilol, is only justified in patients with mild or moderate heart failure without contraindications to beta-adrenergic blockers. There are not data to support the use of carvedilol in patients with severe or unstable heart failure. It seems logical to wait for the results of the ongoing trials (BEST Trial, CIBIS II Trial, COMET Trial, and MERIT Trial) to more precisely define the role that beta-adrenergic blockers should play in the treatment of patients with heart failure. The information presently available suggests that carvedilol should be considered a therapeutic agent for the prevention of progressive clinical heart failure rather than for the treatment of refractory heart failure.

Adrenergic beta-Antagonists↗
PubMed1997

[Endocrine function of the testicle in the Mexican crossbred ram at different times of the year and its opioidergic control during anoestrus].

This work was carried out with the objective of studying the endocrine function of the testes in the Mexican Crossbred Ram (Suffolk x Hampshire) during the different seasons of the year in a latitude of 19 degrees 13' N. Also studied was the opioidergic control of this gland during anoestrus. For this purpose 8 rams were used, from which 3 ml of jugular blood were obtained three times a week to study the seasonal fluctuations in plasma testosterone. The experiment was carried out from May 1993 until June 1994. The androgen was determined by radioimmunoassay. To study the opioidergic control of androgen secretion during seasonal anoestrous (May-June) four of the rams were selected at random and treated with 0.5 mg naloxone at 12 h intervals during 3 continuous weeks. It was observed that blood testosterone was lowest during long days, and concentration was highest during the breeding season. Chronic naloxone medication during anoestrus resulted in a significant increase in blood testosterone (P < 0.001), an effect that was evident after the first week of treatment. When naloxone administration was discontinued, blood testosterone levels returned to basal. With this experiment it was demonstrated that an opioid antagonist such as naloxone administered in low doses, is capable of altering plasma testosterone concentration in the anoestrus ram, giving further support to endogenous opioids as important modulators of reproduction in seasonal breeders such as sheep.

Anestrus↗
PubMed1997

[Solid ovarian tumors in childhood].

We evaluate our experience in solid ovarian tumors at the Children's Hospital La Fe. The main aims of the study were finding out relevant clinical data for a correct clinical approach, and the optimal surgical attitude in order to obtain tumor relieving with preservation of fertility when possible. A review of 28 girls under 14 years with solid ovarian tumors was carried out. Previous history, initial symptoms and signs, analytical and radiological explorations, treatment and evolution were analysed. 17 benign and 11 malignant tumors were found. Main clinical data were acute abdominal pain and palpation of a mass. Surgery was performed in all of them: salpyngo-oophorectomy in 23 and oophorectomy in 5, with tumoral resection. All patients survive, with periodic follow-up. We remark the frequency of acute abdominal pain as initial symptom of an ovarian tumor, and the importance of a surgical attitude that, intending to be curative, would preserve fertility.

Adolescent↗
PubMed1997

[The obtaining of neural cell suspensions. Their application in neurobiological studies].

INTRODUCTION: Techniques of intracranial grafting have become powerful tools used in the study of the mechanisms of regeneration and plasticity taking place in the central nervous system (CNS). Suspensions of foetal neural cells have been successfully used as intracerebral grafts in deep regions of the brain. OBJECTIVE: The objective of this paper is to describe the methodology used by our group to obtain and prepare suspensions of cells from different parts of rat embryo brain (midbrain, striatum and septum) used for experimental transplants in animal models. MATERIAL AND METHODS: We give a detailed description of the steps involved in the preparation of tissue in the form of a suspension of cells. These steps include the obtention of tissue at the optimum stage of development, dissection of the donor tissue, enzymatic treatment and mechanical dissociation until a suspension of cells is obtained. Viability counts showed a high percentage (more than 95%) of viable cells in the suspensions thus obtained. Cellular viability is affected by different factors and is a prerequisite for good survival of the graft. CONCLUSION: The methodology described permits obtention of suspensions of foetal neural cells which are optimal for use in studies both in vitro and in experimental transplants.

Animals↗
PubMed1997

[Clinical and epidemiological study of blood donors seropositive for Trypanosoma cruzi].

BACKGROUND: The prevalence of positive antibodies for Chagas disease in a blood bank of a public hospital in Santiago is 1.2%. These positive individuals should be informed about their condition and further studied. AIM: To perform a serological confirmation, an epidemiological and clinical assessment of blood donors seropositive for Chagas disease in a blood bank of Santiago. SUBJECTS AND METHODS: One hundred eleven seropositive donors, detected between 1994 and 1996, were studied. Serological reactions were confirmed with ELISA and indirect immunofluorescence reactions. Those confirmed as positive were subjected to a clinical-epidemiological questionnaire, physical examination, EKG and barium enema or swallow according to symptoms. RESULTS: Seventy individuals were confirmed as positive for Chagas disease. Most of them lived at least once in an endemic zone for Chagas disease or in a sun-dried clay brick house. Forty-percent of individuals knew reduviid bugs and 14% had been bitten by these insects. Twenty six percent of these subjects had an abnormal EKG (61% with bradycardia). No digestive diseases attributable to Chagas disease were detected. CONCLUSIONS: The high prevalence of problems attributable to Chagas disease among seropositive blood donors underscores the need of an epidemiological follow up of these individuals.

Adult↗
PubMed1996

Methylated CpG points identified within MAGE-1 promoter are involved in gene repression.

The MAGE-1 gene, expressed in some tumors of different histological origins, codes for a tumor antigen recognized by cytotoxic T lymphocytes. The gene is not expressed in normal tissues with the exception of testes. The present study was designed to investigate the relationship between methylation of the MAGE-1 promoter and inactivation of the MAGE-1 gene. We examined the extent to which MAGE-1 B'B promoter sequences are methylated in tumor-cell lines, in order to determine whether methylation correlates with MAGE-1 expression. Using methylation-sensitive restriction analysis followed by polymerase chain reaction (PCR), we found an inverse correlation between methylation of the MAGE-1 B'B region and MAGE-1 expression. An unmethylated state was identified in DNA from sperm and some tumor-cell lines of different origins. In contrast, a hypermethylation state was found in leukocytes and other MAGE-1 non-expressing cells. Furthermore, treatment with 5-aza-2'-deoxycytidine, a demethylating agent, induced MAGE-1 expression in tumor-cell lines in which we found no direct relation between transcriptional activity of the B'B region and MAGE-1 expression. Binding of the nuclear factors to the B'-methylated probe was strongly inhibited, indicating that methylation of cytosine interferes directly in the binding of transcriptional factors.

Antigens, Neoplasm↗
PubMed1996

Critical role of Ras in the proliferation and prevention of apoptosis mediated by IL-2.

Activation of the Ras small guanine nucleotide-binding proteins upon IL-2 stimulation of T lymphocytes has been described previously. However, the relevance of the Ras molecules in the cellular events triggered by IL-2 still remained to be clarified. To analyze the effects of Ras inhibition in early proliferative responses to IL-2, we have transiently expressed a Ras dominant negative mutant carrying a point mutation in codon 17 (Ser17Asn or N17) under a tetracycline-controlled expression system. We have found that Ras has a crucial role in both proliferation and prevention of apoptosis through IL-2R, while IL-4 promotes proliferation and inhibits apoptosis by Ras-independent signals. The use of flow cytometry has allowed us to correlate the effects in proliferation and apoptosis with the expression level of the Ras mutant among the transfected population. Furthermore, the availability of a murine T cell line that can be maintained independently in the presence of IL-2 or IL-4 has provided specificity controls, since IL-4 does not trigger Ras activation.

Animals↗
PubMed1996

[The blood sample as viral marker of cytomegalovirus infection in patients with liver and heart transplantation].

BACKGROUND: To evaluate the utility of blood, saliva and urine samples as virological markers of cytomegalovirus infection in liver and heart transplant recipients. PATIENTS AND METHOD: Patients (68 liver, 21 heart) with a minimum follow up of two months after the transplant date, were included. We performed tube and shell vial cultures in all types of samples. In addition, cytomegalovirus antigenemia assay was carried out on blood specimens. RESULTS: A 97.2% of 36 patients with cytomegalovirus active infection were detected by using blood samples, in comparison with the 86.1% by saliva and 63.9% by urine, but differences were only statistically significant when considering the liver transplant patients subgroup. Moreover, blood samples allowed to detect the infection a mean of 19 days earlier than detection in saliva and/or urine. The most sensitive technique in blood was the antigenemia assay (94.7% of infected patients), followed by the shell vial method (85.3%) and conventional culture (73.3%). The former yields earlier results than culture methods, with a mean of 5 days. CONCLUSIONS: Cytomegalovirus detection in blood samples showed a higher sensitivity in comparison with detection in urine and/or saliva, and was an earlier marker of infection in these patients. We recommended the antigenemia assay and the shell vial culture in blood samples because of their sensitivity, rapidity, and simplicity.

Blood↗
PubMed1996

Characteristics of nitric oxide synthase type I of rat cerebellar astrocytes.

We have previously reported that stimulation of astrocyte cultures by particular agonists and calcium ionophores induces cyclic GMP formation through activation of a constitutive nitric oxide synthase (NOS) and that astrocytes from cerebellum show the largest response. In the present work we have used rat cerebellar astrocyteenriched primary cultures to identify and characterise the isoform of NOS expressed in these cells. The specific NOS activity in astrocyte homogenates, determined by conversion of [3H]arginine to [3H]citrulline, was ten times lower than in homogenates from cerebellar granule neurons. Upon centrifugation at 100,000 g, the astroglial activity was recovered in the supernatant, whereas in neurons around 30% of the activity remained particulate. The cytosolic NOS activities of both astrocytes and granule neurons displayed the same Km for L-arginine, dependency of calcium, and sensitivity to NOS inhibitors. Expression of NOS-I in astrocyte cytosolic fractions was revealed by Western blot with a specific polyclonal antiserum against recombinant NOS-I. Double immunofluorescence labelling using anti-glial fibrillary acidic protein (GFAP) and anti-NOS-I antibodies revealed that a minor population of the GFAP-positive cells, usually in clusters, presented a strong NOS-I immunostaining that was predominantly located around the nuclei and had a granular appearance, indicating association with the endoplasmic reticulum-Golgi system. Astrocytes of stellate morphology also showed immunoreactivity in the processes. Similar staining was observed with the avidin-biotin-peroxidase complex using different anti-NOS-I antisera. With this method the majority of cells showed a weak NOS-I immunoreactivity around the nuclei and cytosol. A similar pattern was observed with the NADPH-diaphorase reaction. These results demonstrate that the NOS-I expressed in astrocytes presents the same biochemical characteristics as the predominant neuronal isoform but may differ in intracellular location.

Animals↗
PubMed1996

Prediction of in-hospital cardiac events using dipyridamole-thallium scintigraphy performed very early after acute myocardial infarction.

BACKGROUND AND HYPOTHESIS: Ischemic complications occur frequently during hospitalization after acute myocardial infarction. Dipyridamole-thallium scintigraphy performed early after admission can detect residual ischemia, may have additional prognostic value and be useful in the management of these patients. METHODS: Dipyridamole infusion and 201thallium imaging were performed on the third day of infarction in 114 consecutive patients. Coronary angiography was performed before hospital discharge in 90% of patients and exercise testing was performed at the time of discharge in patients without contraindications. RESULTS: Side effects occurred in 28 patients, but they were mild and transient or rapidly reversed with intravenous aminophylline. During hospitalization, three patients died and four had a nonfatal reinfarction. Patients with these major cardiac events had previously shown a higher prevalence of reversible perfusion defects during testing (71 vs. 31%, p < 0.05). In addition, 19 patients had early recurrent ischemia requiring early in-hospital revascularization. Overall, cardiac events defined as death, reinfarction, or early myocardial revascularization occurred in 22 patients. Of the patients with these events, 68% had thallium redistribution on initial myocardial scanning compared with 25% of patients without events (p = 0.0001). Patients with cardiac events also showed a higher number of myocardial segments with reversible perfusion defects (1.8 +/- 2.2 vs. 0.6 +/- 1.3, p = 0.001). Logistic regression analysis revealed that among all the other clinical, scintigraphic, and angiographic variables, the presence of thallium redistribution on the dipyridamole-thallium scan was the only independent predictor of cardiac events, increasing the risk by sixfold. Furthermore, during a 1-year follow-up, 14 other patients had ischemic events. Of these, 64% had previously shown thallium redistribution during early dipyridamole testing compared with 19% of patients without cardiac events (p < 0.001). CONCLUSIONS: Intravenous dipyridamole-thallium-scintigraphy performed very early after myocardial infarction is safe and useful to predict in-hospital ischemic events.

Aged↗
PubMed1996

Association of phosphatidylinositol 3 kinase to protein kinase C zeta during interleukin-2 stimulation.

Interleukin-2 induces a serine-phosphorylated phosphatidylinositol 3 kinase activity in the mouse T cell line TS1 alpha beta. Moreover, protein kinase C (PKC) zeta directly or indirectly associates with the phosphatidylinositol 3 kinase and the association appears to be necessary for the serine-phosphorylated phosphatidylinositol 3 kinase activity, since release of zeta PKC by competition of binding with peptides spanning the p110 sequence from amino acids 907 to 925 abolishes the serine-phosphorylated phosphatidylinositol 3 kinase activity. This kinase activity is also blocked when zeta PKC expression is inhibited by antisense oligonucleotide. Inhibition of phosphatidylinositol 3 kinase activity by wortmannin does not abolish zeta PKC association.

Amino Acid Sequence↗
PubMed1996

Association of quantitative cytomegalovirus antigenemia with symptomatic infection in solid organ transplant patients.

A prospective virologic follow-up of solid organ transplant patients was designed to determine the usefulness of antigenemia and viremia as virologic markers for the diagnosis of cytomegalovirus (CMV) infections, and also for monitoring CMV disease and therapy control. A total of 629 blood samples from 127 patients (60 liver, 47 kidney, and 20 heart transplant recipients) were studied by tube and shell vial cultures, and by antigenemia assay. This later was carried out by an indirect immunofluorescent assay method for formalin-fixed cytospin slides containing 2 x 10(5) leukocytes, using a monoclonal antibody directed against the CMV pp65 antigen. CMV was detected by at least one of the three methods in 238 specimens (37.8%) from a total of 63 patients. The antigenemia assay was positive in 215 (90.3% of positive samples). A total of 94 samples were detected only by this marker, which occurred either in samples with low positive counts (70.2% with antigenemia counts < 10 positive cells/10(5) leukocytes) or in specimens from treated patients. There were 30 episodes of CMV disease in 23 patients. Antigenemia was positive in all these episodes, 27 of them with counts > 20 positive cells/10(5) leukocytes. With this cut-off, positive and negative predictive values for symptomatic CMV infection were 100% and 97.2%, respectively. The antigenemia assay is a rapid, sensitive, specific, and early marker of CMV infection in transplantees. Cultures became negative with antiviral therapy while remaining antigenemia detectable. There was an association between highest quantitative antigenemia test results and clinical symptoms in our patients. In its quantitative version, the assay is useful to detect symptomatic infection and appears to be a helpful tool in managing patients at risk and in guiding antiviral therapy.

Antigens, Viral↗