Biomedical subjects

E Melo

Publications and source records attributed to E Melo.

At least 19 recordsLinked to original sources

PubMed2003

Pulmonary function, cholinergic bronchomotor tone, and cardiac autonomic abnormalities in type 2 diabetic patients.

This prospective study analyzed the involvement of the autonomic nervous system in pulmonary and cardiac function by evaluating cardiovascular reflex and its correlation with pulmonary function abnormalities of type 2 diabetic patients. Diabetic patients (N = 17) and healthy subjects (N = 17) were evaluated by 1) pulmonary function tests including spirometry, He-dilution method, N2 washout test, and specific airway conductance (SGaw) determined by plethysmography before and after aerosol administration of atropine sulfate, and 2) autonomic cardiovascular activity by the passive tilting test and the magnitude of respiratory sinus arrhythmia (RSA). Basal heart rate was higher in the diabetic group (87.8 +/- 11.2 bpm; mean +/- SD) than in the control group (72.9 +/- 7.8 bpm, P<0.05). The increase of heart rate at 5 s of tilting was 11.8 +/- 6.5 bpm in diabetic patients and 17.6 +/- 6.2 bpm in the control group (P<0.05). Systemic arterial pressure and RSA analysis did not reveal significant differences between groups. Diabetes intragroup analysis revealed two behaviors: 10 patients with close to normal findings and 7 with significant abnormalities in terms of RSA, with the latter subgroup presenting one or more abnormalities in other tests and clear evidence of cardiovascular autonomic dysfunction. End-expiratory flows were significantly lower in diabetic patients than in the control group (P<0.05). Pulmonary function tests before and after atropine administration demonstrated comparable responses by both groups. Type 2 diabetic patients have cardiac autonomic dysfunction that is not associated with bronchomotor tone alterations, probably reflecting a less severe impairment than that of type 1 diabetes mellitus. Yet, a reduction of end-expiratory flow was detected.

Adult↗

PubMed2001

Molecular mechanism of lateral diffusion of py(10)-PC and free pyrene in fluid DMPC bilayers.

From the study of the kinetics of the fluorescence self-quenching of pyrene in multilamellar vesicles of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in the fluid phase we obtain the molecular diffusion parameters, diffusion coefficients, and activation energies for lateral diffusion for three probes: 1-palmitoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphocholine (py(10)-PC), pyrene, and 1-pyrenebutanoic acid (py-but). The experiments are done in a range of temperatures for which the reversibility of excimer formation is negligible and the probe/phospholipid ratios used are low, avoiding non-ideal mixing of the probe. The time-resolved fluorescence decays are, in all cases, accurately and consistently described by the two-dimensional (2D) formalism for bimolecular diffusion-controlled reactions. From the parameters obtained in this way we conclude that the primary step of the diffusion of the pyrene-labeled phospholipid involves the simultaneous jump of phospholipid and fluorophore moieties, and also that although in the case of py(10)-PC the pyrene from molecules pertaining to different layers may interact during the lifetime of the exited state, this is not the case for free pyrene.

Biophysical Phenomena↗

PubMed2001

The genetic organization of Desulfovibrio desulphuricans ATCC 27774 bacterioferritin and rubredoxin-2 genes: involvement of rubredoxin in iron metabolism.

The anaerobic bacterium Desulfovibrio desulphuricans ATCC 27774 contains a unique bacterioferritin, isolated with a stable di-iron centre and having iron-coproporphyrin III as its haem cofactor, as well as a type 2 rubredoxin with an unusual spacing of four amino acid residues between the first two binding cysteines. The genes encoding for these two proteins were cloned and sequenced. The deduced amino acid sequence of the bacterioferritin shows that it is among the most divergent members of this protein family. Most interestingly, the bacterioferritin and rubredoxin-2 genes form a dicistronic operon, which reflects the direct interaction between the two proteins. Indeed, bacterioferritin and rubredoxin-2 form a complex in vitro, as shown by the significant increase in the anisotropy and decay times of the fluorescence of rubredoxin-2 tryptophan(s) when mixed with bacterioferritin. In addition, rubredoxin-2 donates electrons to bacterioferritin. This is the first identification of an electron donor to a bacterioferritin and shows the involvement of rubredoxin-2 in iron metabolism. Furthermore, analysis of the genomic data for anaerobes suggests that rubredoxins play a general role in iron metabolism and oxygen detoxification in these prokaryotes.

Amino Acid Sequence↗

PubMed2000

Partitioning of amphiphiles between coexisting ordered and disordered phases in two-phase lipid bilayer membranes.

The partition coefficients (K(P)) of a series of single-chain and double-chain fluorescent amphiphiles, between solid ordered (P(beta') and L(beta)) and liquid disordered (L(alpha) of the type l(d)) lipid phases coexisting in the same lipid bilayer, was studied using steady-state fluorescence emission anisotropy. The single-chain amphiphiles were N-(7-nitrobenzoxa-2, 3-diazol-4-yl)-alkylamines, and the double-chain amphiphiles were N-(7-nitrobenzoxa-2, 3-diazol-4-yl)-phosphatidylethanolamines with chain lengths of 12-18 carbon atoms. Saturated 18-carbon alkyl/acyl chain compounds were also compared with Delta(9)-cis unsaturated chains of the same chain length. The fluorescence anisotropy of the probes was examined in lipid bilayers (multilamellar vesicles) prepared from an equimolar mixture of dilauroylphosphatidylcholine and distearoylphosphatidylcholine and studied as a function of temperature through the entire temperature range of coexistence of ordered gel phases and a disordered fluid phase in this system. The unsaturated chain amphiphiles partitioned exclusively into the fluid phase whenever this phase was present, as did the saturated chain amphiphiles with the shortest chains (C(12:0)), while K(P) ranges between 1 and 2, in favor of the L(beta) solid phase, for the amphiphiles with long saturated (C(18:0)) alkyl/acyl chains, with intermediate behavior for the intermediate chain lengths. All probes appeared to be totally excluded from P(beta') solid (gel) phases. The technique was also used to determine partitioning of some of the probes between coexisting liquid ordered (cholesterol-containing) (l(o)) and liquid disordered (l(d)) L(alpha) phases. In this case the ratio of signal amplitude to noise allowed us to obtain a qualitative, but not quantitative, measure of the phase partitioning of the probes. We conclude that the partitioning behavior of the probes examined between coexisting l(o) and l(d) phases is qualitatively similar to that observed between solid ordered and liquid disordered phases.

Fluorescence Polarization↗

PubMed2000

Quality of life in patients undergoing coronary revascularization.

INTRODUCTION: This study was aimed at the evaluation of the impact of coronary revascularization surgery on the quality of life (QOL) and identification of some variables which may contribute to influence the patients' own perception of their health condition. METHODOLOGY: We prospectively studied 150 consecutive patients subjected to isolated coronary bypass surgery during a 3-month period, with evaluation of their perception of QOL before surgery and 6 months thereafter. The measurement instruments used were the MOS Health Survey (SF-36) and the Nottingham Health Profile (NHP). Additionally, a questionnaire for identification of lifestyles was introduced. RESULTS: The majority of the patients were male (94%), above 50 years of age (81%), with a low educational level (65%), married (90%) and pensioners (44%). About one third (38%) had marked physical limitations (CCS class III/IV), with comorbidity (80%), previous myocardial infarction (49%) and 3-vessel coronary disease (68%). There was no operative mortality, but 29% had postoperative complications, albeit minor in the majority. Admission time was less than 8 days in 88.6% of the cases. Surgery proved beneficial in improving QOL, with better perception after surgery in all dimensions of both measurement instruments (p < 0.001). A higher level of education was related to a better perception of the energy dimension, married patients had a better improvement in the dimensions of physical pain and social isolation. More severe preoperative angina determined less favourable scores in the dimensions of mental health, social function and vitality; comorbidity had a negative impact on vitality and physical mobility; and the number of risk factors and postoperative complications had a negative impact on the dimensions of energy and emotional reactions, and social isolation and physical function, respectively. Six months after surgery, 62% of the patients who were still working before surgery had resumed their professional activity, but about 20% had retired; the majority had adopted healthier lifestyles with a decrease in tobacco and alcohol consumption and a more balanced diet. CONCLUSIONS: Coronary revascularization substantially improves QOL, with a significant impact on the clinical variables of the psycho-social dimensions.

Adult↗

PubMed1997

Phase topology and percolation in two-component lipid bilayers: a monte Carlo approach.

Monte Carlo simulations of fluorescence recovery after photobleaching (FRAP) experiments on two-component lipid bilayers systems in the solid-fluid phase coexistence region were carried out to study the geometry and size of fluid domains in these bilayers. The gel phase was simulated by superposable elliptical domains, which were either of predetermined dimensions, increasing in number with increasing gel phase fraction, or of predetermined number, increasing in dimensions with increasing gel phase fraction. The simulations were done from two perspectives: 1) a time-independent analysis of fractional fluorescence recovery as a function of fractional fluid phase in the system; and 2) a time-dependent analysis of fractional fluorescence recovery as a function of time at a given fraction of fluid phase in the system. The time-dependent simulations result in recovery curves that are directly comparable to experimental FRAP curves and provide topological and geometrical models for the coexisting phases that are consistent with the experimental result.

Fluorescence↗

PubMed1989

[Obstetric factors associated with low birth weight].

An analysis was made of 18,804 of 19,446 consecutive births of the number analysed 15.93% presented low birth-rate. Significant statistical association was found in relation to maternal age, pre-natal care, previous pregnancies, smoking and gestational age at birth. Measures with a view to the attenuation of the problem are proposed, among them being: educational programs for teenagers on human reproduction, programs designed to create awareness of the harm done by smoking, amplification of antenatal assistance, medical programs for the limitation of premature labor, all of these and others, in association with programs of socio-economic support.

Adolescent↗

PubMed1978