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Biomedical subjects

J Muñiz

Publications and source records attributed to J Muñiz.

At least 37 records · Page 2Linked to original sources
PubMed2000

Absence of enteroviral RNA in hearts explanted from patients with dilated cardiomyopathy.

BACKGROUND: The role of enterovirus infection in the pathogenesis of dilated cardiomyopathy (DCM) remains unclear. The objective of this study was to determine the prevalence of enterovirus in hearts explanted from patients with DCM and to compare it with enterovirus prevalence in hearts explanted from patients with other etiologies and in healthy donor hearts. METHODS: A total of 138 cardiac samples were analyzed, 70 from heart donors and 68 from transplant recipients (22 with DCM). A highly sensitive enterovirus-specific nested RT-PCR was used to test for enterovirus. RESULTS: All tests were negative except for one positive result that was attributed to carryover because sequencing of the amplification product showed it to be identical to the positive control. CONCLUSIONS: In this study the sample of explanted hearts nested RT-PCR showed no evidence of the presence of enteroviral RNA. This suggests that if enterovirus had a role in the genesis of DCM, it does not require or lead to the persistence of the virus in myocardial tissue.

Adolescent↗
PubMed2000

[Sudden cardiac death out of the hospital and early defibrillation].

Since most sudden cardiac death victims show neither symptoms before the event nor other signs or risk factors that would have identified them as a high risk population before their cardiac arrest, emergency out-of-hospital medical services must be improved in order to obtain a higher survival in these patients. Early defibrillation is an essential part of the chain of survival that also includes the early identification of the victim, activation of the emergency medical system, immediate arrival of trained personnel who can perform basic cardiopulmonary resuscitation and early initiation of advanced cardiac life support that would raise the survival rate for sudden cardiac arrest victims. Many studies have demonstrated the enormous importance of early defibrillation in patients with a cardiac arrest due to ventricular fibrillation. The most important predictor of survival in these individuals is the time that elapses until electric defibrillation, the longer the time to defbrillation the lower the number of patients who are eventually discharged. Multiple studies have demonstrated that automatic external defibrillation will reduce the time elapsed to defibrillation and thus improve survival. For these reason, public access defibrillation to allow the use of automatic external defibrillators by minimally trained members of the lay public, has received increasing interest on the part of a groving number of companies, cities or countries. The automatic external defibrillaton, as performed by a lay person is being investigated. The liberalization of its application, if is demonstrated to be effective, will need to be accompanied by legal measures to endorse it and appropriate health education, probably during secondary education.

Cardiopulmonary Resuscitation↗
PubMed2000

[Guidelines of the Spanish Society of Cardiology for cardiovascular disease prevention and cardiac rehabilitation].

The priorities for the prevention of cardiovascular diseases should be focused on patients with established disease and high risk subjects, with individual global risk always being taken into account. The current evidence on the influence of the main risk factors are unanimous (dyslipemia, tobacco, hypertension and diabetes mellitus), being somewhat less so in cases of sedentarism, obesity and the metabolic syndrome. The evidence concerning other risk factors still remains controversial. Guidelines for the control of the different risk factors should be based on the evidence derived from both epidemiological or clinical trials. The recommendations published by several scientific societies should also be followed. There are, at present, important evidence on the efficacy of smoking cessation, the treatment of arterial hypertension and particularly on the successful control of lipid levels with lipid-lowering drugs, especially with statins. There is also evidence on the need for rigorous control of diabetic patients not only in relation to the glucose levels but also to dyslipemia. The most efficient measures for a reduction in morbidity and mortality are cessation of smoking, appropriate hypertensive therapy, a comprehensive program of cardiac rehabilitation and overall the successful control of lipid levels with statins.

Cardiac Rehabilitation↗
PubMed1999

Inhibition of vacuolar ion channels by polyamines.

In this work, direct effects of cytosolic polyamines on the two principle vacuolar ion channels were studied by means of patch-clamp technique. Fast and slow activating vacuolar channels were analyzed on membrane patches isolated from vacuoles of the red beet taproot. The potency of the fast and of the slow vacuolar channel blockage by polyamines decreased with a decrease of the polycation charge, spermine4+ > spermidine3+ > putrescine2+. In contrast to the inhibition of the fast vacuolar channel, the blockage of the slow vacuolar channel by polyamines displayed a pronounced voltage-dependence. Hence, in the presence of high concentration of polyamines the slow vacuolar channel was converted into a strong inward rectifier as evidenced by its unitary current-voltage characteristic. The blockage of the slow vacuolar channel by polyamines was relieved at a large depolarization, in line with the permeation of polyamines through this channel. The voltage-dependence of blockage was analyzed in terms of the conventional model, assuming a single binding site for polyamines within the channel pore. Taking advantage of a simple linear structure of naturally occurring polyamines, conclusions on a possible architecture of the slow vacuolar channel pore were drawn. The role of common polyamines in regulation of vacuolar ion transport was discussed.

Chenopodiaceae↗
PubMed1999

Asymmetric block of the plant vacuolar Ca(2+)-permeable channel by organic cations.

In this work we have analysed the voltage-dependent block of the slow activating channel from red beet vacuoles by Tris, quaternary ammonium ions and the natural polyamines putrescine, spermidine and spermine. All these organic cations when applied from the cytosolic side blocked the channel by binding apparently deep (zdelta values in the range of 0.65-1.35) within the pore. Tetraethylammonium ion did not pass the selectivity filter, whereas the cations with a smaller cross-section and Tris could pass across the entire pore, as evidenced by a relief of block at high positive voltages. Voltage dependence of the establishment of block from cytosolic side and of its relief was anomalously strong in the sense that the total charge moved across the pore for all blockers tested, with a notable exception of spermine, was in excess of their actual valence. This behaviour is consistent with the existence of multiple binding sites within a long pore, their simultaneous occupancy and interaction between different ions. In contrast, binding of blockers from the vacuolar (lumenal) side appears to follow a single-ion handling rule, with a common binding site for all amines located at approximately 30% of the electrical distance from the lumenal side.

Calcium Channels↗
PubMed1999

Cooperative block of the plant endomembrane ion channel by ruthenium red.

Effects of ruthenium red (RR) on the slow Ca(2+)-activated Ca(2+)-permeable vacuolar channel have been studied by patch-clamp technique. Applied to the cytosolic side of isolated membrane patches, RR at concentrations of 0.1-5 microM produced two distinct effects on single channel kinetics, long lasting closures and a flickering block of the open state. The first effect was largely irreversible, whereas the second one could be washed out. The extent of flickering block steeply increased (zdelta = approximately 1.35) with the increase of cytosol-positive voltage, dragging RR into the channel pore. At least two RR ions are involved in the block according to Hill coefficient n = approximately 1.30 for the dose response curves. The on-rate rate of the drug binding linearly depended on the RR concentration, implying that one RR ion already plugged the pore. The blocked state was further stabilized by binding of the second RR. This stabilization was in excess of that predicted by independent binding as the dependence of unblocking rate on RR concentration revealed. A cooperative model was therefore employed to describe the kinetic behavior of RR binding. At zero voltage the half-blocking RR concentration of 36 microM and the bimolecular on-rate constant of 1.8 x 10(8) M(-1) s(-1) were estimated.

Binding Sites↗
PubMed1999

Passive forces in mammalian skeletal muscle: a freely-jointed and worm-like chain.

The passive mechanical properties of whole muscle in active and nonactive states are compared. The experimental results are presented as stress-strain curves, which are analyzed in the framework of the current theoretical background [viz. the freely-jointed chain model (FJCM) and the worm-like chain model (WLCM)] in a semi-quantitative fashion. This analysis shows that both models can explain the mechanical behavior of whole muscle in non-active state. In the active state, the presence of crossbridges alters the mechanical response, leading to a markedly different behavior, as expected. A discussion of the mechanisms involved and the interpretation of the parameters required for the fitting of the stress-strain curves is also presented.

Animals↗
PubMed1999

Folding-unfolding of immunoglobulin domains in titin: a simple two-state model.

The folding-unfolding reaction rate process in the giant protein titin is studied within a simple two-state model. The molecule is assumed to be stretched by an external force which modulates the potential barrier associated with the folded state. A two-state model for this process is assumed (i.e., the immunoglobulin domains are considered to be either folded or unfolded, with no intermediate states at all). Simple calculations yield a relation between the force and the pulling speed that agrees fairly well with data from experiments and Monte Carlo simulations performed recently. Moreover, in a regime involving ultrafast pulling, the results show that the detailed form of the potential barrier is irrelevant, a conclusion that agrees with the current theoretical work on molecular dynamics.

Amino Acid Sequence↗
PubMed1998

[The evidence for higher blood pressures in children and adolescents of the rural interior of Galicia than in other locations in Spain].

AIM: To analyze differences in blood pressure levels in children and adolescents in Galicia with those of peers living in other parts of Spain. DESIGN: Cross-sectional study done in a rural area in Galicia. PARTICIPANTS: 870 boys and girls 6 to 16 years old. They are compared with published data from the RICARDIN study, that includes 10,042 participants selected at the schools in nine centers of Spain (one was the center in Galicia). MEASUREMENTS: Standardized methodology and certification procedures were used in Galicia and Spain to measure weight, height, Quételet index, systolic (SBP) and fifth-phase diastolic blood pressure (DBP5) and sexual maturation. Data are presented by sex and age group (1 year) both in Galicia and Spain. RESULTS: From 11 years and above, girls in Galicia present higher SBP than in Spain. In boys, the difference appears later. Galicia shows higher DBP5 levels than Spain in every age-sex group. In relation to obesity, the differences are of a small magnitude in the Quételet index, again, higher values in Galicia. CONCLUSIONS: This is the first population-based study available that rules out the possibility that the observed differences, previously already suggested, could be attributed to methodological problems. The differences in blood pressure and obesity between Galicia and other areas of Spain, already previously suggested in adults, can be the reflection of differences present from childhood.

Adolescent↗
PubMed1998

[Brain abscess. Clinicomicrobiologic study and prognostic analysis of 59 cases].

INTRODUCTION: Clinical, microbiological, therapeutic and prognostic characteristics of brain abscesses were analyzed as well as the influence of CT in their evolution. MATERIALS AND METHODS: Retrospective study of 59 patients with the diagnosis of brain abscess of bacterial source before (group A) and after (group B) the introduction of CT (25 and 34 patients, respectively). RESULTS: The most common symptom was headache (76.3%) and the most common abnormality in physical examination was a decrease in the level of consciousness (61%) and this abnormality was associated with a higher mortality rate (13% versus 41.6%; p < 0.05) and also a higher proportion of neurologic sequelae (50% versus 85.7%; p < 0.05). The diagnosis was obtained earlier in group B. The hematogenous source predominated (32.2%); an adjacent source was identified in 28.8% and an apparent source was not recognized in 27.2% (40% in group A versus 17.6% in group B). Anaerobic and microaerophilic streptococci were the bacteria recovered most frequently. Gram-negative aerobic bacteria were the most common in otogenic abscesses. The use of corticosteroids had no influence upon mortality, but it was associated with a lower percentage of neurological sequelae (40% versus 14%; p < 0.05). The introduction of CT decreased mortality (40% in group A versus 23.5% in group B, although this difference was not significant) and also sequelae (86.6% in group A versus 57.6% in group B; p < 0.05). Leaving apart cases of bacterial endocarditis, in which death was due to the underlying heart disease and a systemic sepsis picture, mortality attributed to brain abscess was 20.3%. CONCLUSIONS: The introduction of CT has meant a significant breakthrough for the diagnosis, treatment and follow-up of these patients and has contributed to improvement in survival. In our series, the diagnosis of brain abscess was obtained earlier and the number of brain abscesses with no apparent source has decreased since the introduction of CT. Moreover, CT sensitivity is really good for locating multiple abscesses. Overall, the prognosis of these patients has improved since the introduction of this technique. Nevertheless, brain abscess is still associated with a relevant morbi-mortality rate.

Adrenal Cortex Hormones↗
PubMed1997

[Research methods in clinical cardiology (VII). Experimental studies in cardiology].

Experimental designs in clinical investigation are discussed in this article. Guideline examples have been used in the area of Cardiology using always the same one only one whenever possible. We have looked for a different perspective from what is generally used in the discussion of the general characteristics of experimental designs, and more specifically of clinical trials and we deal with the aspects of clinical trials which are usually ignored due to their marginal character. We also discuss those characteristics which differentiate clinical trials in respect to other designs and types of questions which are answered by clinical trials. And we finally discuss various aspects such as randomization and its various types (simple, block, stratified, pre-randomized) and variable types of evaluating the answers, masking and the problems in its maintenance, with certain kinds of designs, sample size, etc. There is a brief mention of two particular cases: factorial and cross over designs are both discussed, mentioning their strong and weak points. Likewise, we discuss community trials as another experimental design and examples are provided. Finally, we discuss aspects of criteria: such as, When to stop the trials? or Who are the results applicable to?, and we suggest points to take into consideration when these decisions are made.

Cardiology↗
PubMed1996

Electrostatic forces as a possible mechanism underlying skeletal muscle contraction.

A possible mechanism is put forward to explain the sliding of thin filaments during muscle contraction. In our model, repulsion due to electrostatic forces is the mechanism which triggers crossbridges to cause the thin filaments to slide. The mechanism proposed could operate regardless of whether the myosin heads rotate or bend, although recent experimental evidence seems to confirm the latter action. In spite of its simplicity, the model prediction of the velocity of sliding of the thin filaments agrees well with experimental values from in vitro motility assays.

Actins↗
PubMed1995

Newborn universal immunisation against hepatitis B: immunogenicity and reactogenicity of simultaneous administration of diphtheria/tetanus/pertussis (DTP) and oral polio vaccines with hepatitis B vaccine at 0, 2 and 6 months of age.

The reactogenicity and immunogenicity of the administration of recombinant vaccine against hepatitis B simultaneously (but at separate sites) with diphtheria/tetanus/pertussis (DTP) and oral polio vaccines were examined. Six hundred and twenty-six children (group I) were given hepatitis B vaccine at 0, 2 and 6 months of age; the other vaccines were administered at 2, 4 and 6 months of age. A control group of 731 children (group II) received only DTP and oral polio vaccines. The results showed that 93% of the infants in group I had anti-HBs titres above the protective level ( > or = 10 mIU ml-1) after vaccination. There were no differences in the immune responses for DTP and polio between the two study groups. The vaccine efficacy against poliomyelitis was 96% for serotype I, 100% for serotype II and 97-98% for serotype III. Of the infants in both groups, 97% had antibodies against B. pertussis; all children were positive for tetanus and diphtheria. There were no differences in the incidences of general reactions between groups. Local swelling and redness were reported following 4.2 and 4.4%, respectively, of all injections of hepatitis B vaccine. These reactions were reported following 31 and 33%, respectively, of all doses of DTP vaccine. It can be concluded that the simultaneous administration of hepatitis B vaccine with the DTP and polio vaccines is well-tolerated; hepatitis B vaccine remained highly immunogenic and did not interfere with the immune response to the other antigens.

Diphtheria-Tetanus-Pertussis Vaccine↗