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Biomedical subjects

C Machado

Publications and source records attributed to C Machado.

At least 19 recordsLinked to original sources
PubMed2005

Juvenile localized scleroderma: clinical and epidemiological features in 750 children. An international study.

OBJECTIVE: Juvenile localized scleroderma (JLS) includes a number of conditions often grouped together. With the long-term goal of developing uniform classification criteria, we studied the epidemiological, clinical and immunological features of children with JLS followed by paediatric rheumatology and dermatology centres. METHODS: A large, multicentre, multinational study was conducted by collecting information on the demographics, family history, triggering environmental factors, clinical and laboratory features, and treatment of patients with JLS. RESULTS: Seven hundred and fifty patients with JLS from 70 centres were enrolled into the study. The disease duration at diagnosis was 18 months. Linear scleroderma (LS) was the most frequent subtype (65%), followed by plaque morphea (PM) (26%), generalized morphea (GM) (7%) and deep morphea (DM) (2%). As many as 15% of patients had a mixed subtype. Ninety-one patients (12%) had a positive family history for rheumatic or autoimmune diseases; 100 (13.3%) reported environmental events as possible trigger. ANA was positive in 42.3% of the patients, with a higher prevalence in the LS-DM subtype than in the PM-GM subtype. Scl70 was detected in the sera of 3% of the patients, anticentromere antibody in 2%, anti-double-stranded DNA in 4%, anti-cardiolipin antibody in 13% and rheumatoid factor in 16%. Methotrexate was the drug most frequently used, especially during the last 5 yr. CONCLUSION: This study represents the largest collection of patients with JLS ever reported. The insidious onset of the disease, the delay in diagnosis, the recognition of mixed subtype and the better definition of the other subtypes should influence our efforts in educating trainees and practitioners and help in developing a comprehensive classification system for this syndrome.

Adolescent↗
PubMed2003

Predicting outcome in acute stroke: a comparison between QEEG and the Canadian Neurological Scale.

OBJECTIVE: To determine and compare the predictive value of quantitative EEG (QEEG) and the Canadian Neurological Scale (CaNS), in patients with an acute cerebral stroke. METHODOLOGY: Twenty-eight patients were studied with the diagnosis of acute ischemic middle cerebral artery stroke, within the first 72 hours of clinical evolution. Thirty-seven EEGs and clinical evaluations were collected: 13 during the first 24 hours after stroke onset, 9 between 24-48 hours and 15 between 48-72 hours. The QEEG studied variables were: the Z values (maximum, minimum and the Z medians from the 5 nearest points to each one) of absolute energies (AE) from the 4 classic frequencies bands. The clinical scale showed a smaller percent of correct prognosis than QEEG variables. CONCLUSIONS: QEEG was demonstrated to be a powerful tool to predict the degree of residual functional disabilities after an acute ischemic stroke and showed a higher prognostic value than CaNS when they are performed within the first 72 hours of brain infarct.

Aged↗
PubMed2001

Shock reduction using antitachycardia pacing for spontaneous rapid ventricular tachycardia in patients with coronary artery disease.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) can terminate some ventricular tachycardias (VTs) painlessly with antitachycardia pacing (ATP). ATP has not routinely been applied for VT >188 bpm because of concerns about efficacy, risk of acceleration, and delay of definitive shock therapy. This prospective, multicenter study evaluated the efficacy of empirical ATP to terminate fast VT (FVT; >188 bpm). METHODS AND RESULTS: Two hundred twenty coronary artery disease patients received ICDs for standard indications. Empirical, standardized therapy was programmed so that all FVT episodes (average cycle length [CL] 240 to 320 ms, 250 to 188 bpm) were treated with 2 ATP sequences (8-pulse burst pacing train at 88% of the FVT CL) before shock delivery. A total of 1100 episodes of spontaneous ventricular tachyarrhythmias occurred during a mean of 6.9+/-3.6 months of follow-up. Fifty-seven percent were classified as slow VT (CL>/=320 ms), 40% as FVT (240 ms</=CL<320 ms), and 3% as ventricular fibrillation (CL<240 ms). A total of 446 FVT episodes, mean CL=301+/-24 ms, occurred in 52 patients (median 2 episodes per patient). ATP terminated 396 FVT episodes (89%), with an adjusted efficacy of 77% (95% CI 68% to 83%). VT acceleration caused by ATP occurred in 10 FVT episodes (4%). FVT arrhythmic syncope occurred on 9 occasions (2%) in 4 patients. CONCLUSIONS: FVT (CL<320 ms) is common in ICD patients. ATP can terminate 3 of 4 of these episodes with a low incidence of acceleration and syncope. ATP for FVT may safely reduce the morbidity of painful shocks.

Adult↗
PubMed2001

Ion-dipole S(N)2 reaction in acetone-water mixtures. Electrostatic and specific solute-solvent interactions.

The rate constants of the S(N)2 reaction of sodium 4-nitrophenoxide (1) and iodomethane were determined by UV-visible spectrophotometry in acetone-water mixtures at 25, 30, and 35 degrees C. The rate-Xwater (mole fraction of water) profile shows that the reaction depends strongly on the medium. The fastest rate constant was obtained in pure acetone, and a minimum occurred at Xwater= 0.4, whereas the observed second-order rate constants increases again in the water-rich region. In pure acetone, in the presence of dicyclohexano-[18]-crown-6, increases linearly with the concentration of the crown ether as a result of the complexation of the sodium ion (KS = 104.8 M) of the ion-pair and the increase in the effective concentration of free 4-nitrophenoxide ion, which was assumed to be the only reactive species. Ion-pairing was also detected at Xwater= 0.65 with a dissociation constant Kd = 7.82 x 10(-4) M(-1). The solvatochromic behaviors of 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)-1-phenoxide (2), 4-[(1-methyl-4(1H)-pyridinylidene)ethylidene]-2,5-cyclohexadien-1-one (3), and 1-methyl-8-oxy-quinolinium betaine (4) were investigated in the entire range of acetone-water mixtures. The dyes presented an increasing order of hydrophilicity compatible with their chemical structure, i.e., 2 < 3 < 4. Kinetic parameters for the methylation of 1 and the ET values of the dyes show a linear correlation of the polarity in the region of Xwater = 1.0-0.40 for 3 and 4, and it was observed that the more hydrophilic the dye the better the correlation coefficient, because of the structural similarity with 1. The activation parameter-Xwater profile shows extrema at Xwater < 0.4, reflecting an important change in the structure of the solvent that is responsible for the changes in the solvation of the reactive species including ion-pairs. These results suggest that the addition of water to acetone reduces abruptly the rate of substitution due to the preferential solvation (PS) of the phenoxide ion by the hydrogen-bonding donor (HBD) solvent. Nevertheless, the real second-order rate constant is "masked" by the association involving Na+ and 4-nitrophenoxide that extends even to water-rich mixtures. A model, based on the assumption that the free-energy terms involved in the second-order rate constant and the dissociation constant of the ion-pair have two components, is invoked to explain the kinetic data. One of the components depends on electrostatic interactions for which the main variable is the dielectric constant of the solvent mixture, and the other depends on the specific solute-solvent interactions, expressed by the activity coefficients of transfer of the species involved. The model indicates that in the range of Xwater = 1.0-0.40 the interactions are exclusively electrostatic, while for the rest of the acetone-rich region they are specific with a large contribution of the 4-nitrophenoxide ion.

Journal Article↗
PubMed2000

D-Titin: a giant protein with dual roles in chromosomes and muscles.

Previously, we reported that chromosomes contain a giant filamentous protein, which we identified as titin, a component of muscle sarcomeres. Here, we report the sequence of the entire titin gene in Drosophila melanogaster, D-Titin, and show that it encodes a two-megadalton protein with significant colinear homology to the NH(2)-terminal half of vertebrate titin. Mutations in D-Titin cause chromosome undercondensation, chromosome breakage, loss of diploidy, and premature sister chromatid separation. Additionally, D-Titin mutants have defects in myoblast fusion and muscle organization. The phenotypes of the D-Titin mutants suggest parallel roles for titin in both muscle and chromosome structure and elasticity, and provide new insight into chromosome structure.

Animals↗
PubMed2000

Titin as a chromosomal protein.

We identified titin as a chromosomal protein using a human autoimmune scleroderma serum. We cloned the corresponding gene in the fruitfly, Drosophila melanogaster. We have demonstrated that titin is not only expressed and localized in striated muscle but is also distributed uniformly on condensed mitotic chromosomes using multiple antibodies directed against different domains of both Drosophila and vertebrate titin. Titin is a giant sarcomeric protein responsible for the elasticity of striated muscle. Titin may also function as a molecular scaffold during myofibril assembly. We hypothesize that titin is a component of chromosomes that may function to determine chromosome structure and provide elasticity, playing a role similar to that proposed for titin in muscle. We have identified mutations in Drosophila Titin (D-Titin) and are characterizing phenotypes in muscle and chromosomes.

Animals↗
PubMed2000

Thrombus formation at the site of radiofrequency catheter ablation.

A 55-year-old woman with a history of resected atrial myxoma with residual patched atrial septal defect (ASD) underwent a successful radiofrequency (RF) ablation of reentry atrial tachycardia. She presented with progressive dyspnea 5 days later. Transesophageal echocardiography revealed a 1-cm right atrial mass attached to the intraatrial septum at the ablation site. Repeat study after anticoagulation for 5 weeks showed complete resolution of the thrombus. Thrombus formation at the site of RF ablation is a potential complication that may require aggressive anticoagulation. Patients with patched ASD might be at higher risk.

Catheter Ablation↗
PubMed1999

Consciousness as a definition of death: its appeal and complexity.

A new formulation of death proposed in this study is based on the basic physiopathological mechanisms of consciousness generation in human beings. Two physiological components control conscious behavior: arousal and awareness (content of consciousness). We cannot simply differentiate and locate arousal as a function of the ascending reticular activating system and awareness as a function of the cerebral cortex. Substantial interconnections among the brainstem, subcortical structures and the neocortex, are essential for subserving and integrating both components of human consciousness. Therefore, consciousness does not bear a simple one-to-one relationship with higher or lower brain structures, because the physical substratum for consciousness is based on anatomy and physiology throughout the brain. This new account of human death is based on the irreversible loss of consciousness because it provides the key human attributes and the highest level of control in the hierarchy of integrating functions within the organism. The notion of consciousness as the ultimate integrative function is more consistent with the biologically-based systems than the more philosophically-based notions of personhood.

Arousal↗
PubMed1999

[Physiologic role of the somatotrophic GH-IGF and others hormones in the domestic animals growth. Influence of the nutritional status].

In this review main hormones involved in development and muscle growth are shown with special emphasis on growth hormone (GH) and insulin-like growth factors (IGF). Chemist composition, synthesis place, action way and main action mechanisms of these hormones are reviewed. Nutritional factors which modified seric metabolites, and their effects on hormone secretion are detailed. It was observed that GH, IGF, thyroid hormones, insulin, glucocorticoids and sexual steroids act in a complex and cordinated way to produce a productive response to different> nutritional strategies.

Animals↗
PubMed1998

Human autoantibodies reveal titin as a chromosomal protein.

Assembly of the higher-order structure of mitotic chromosomes is a prerequisite for proper chromosome condensation, segregation and integrity. Understanding the details of this process has been limited because very few proteins involved in the assembly of chromosome structure have been discovered. Using a human autoimmune scleroderma serum that identifies a chromosomal protein in human cells and Drosophila embryos, we cloned the corresponding Drosophila gene that encodes the homologue of vertebrate titin based on protein size, sequence similarity, developmental expression and subcellular localization. Titin is a giant sarcomeric protein responsible for the elasticity of striated muscle that may also function as a molecular scaffold for myofibrillar assembly. Molecular analysis and immunostaining with antibodies to multiple titin epitopes indicates that the chromosomal and muscle forms of titin may vary in their NH2 termini. The identification of titin as a chromosomal component provides a molecular basis for chromosome structure and elasticity.

Amino Acid Sequence↗
PubMed1998

Sudden darkness induces a high activity-low anxiety state in male and female rats.

The effects of sudden darkness on spontaneous motor activity in an open field and performance in an elevated plus-maze (EPM) were assessed in adult male and female rats. In the open field test, sudden darkness increased total locomotion, locomotion in central squares, rearing frequency (RF), and diminished defecation units (DU). In the dark, total locomotion remained elevated during the 20-min test period, while in the light total locomotion decreased significantly after the fourth minute, in both sexes. All the effects of sudden darkness in the open field test were more pronounced in female rats. In the EPM, sudden darkness increased the number of entries into the open arms, total entries, percentages of entries into the open arms, and time spent in the open arms. The changes were more significant in female than in male rats. These results show that sudden darkness increases general motor activity and suggest it diminishes habituation, fear, and anxiety. The results also suggest that this behavioral shift is sexually differentiated. Sudden darkness emerges as an experimental tool to simultaneously test physiologically-induced increases in spontaneous motor activity and decreases in anxiety.

Animals↗
PubMed1998

Results of the routine use of a modified endoprosthesis to drain the common bile duct after laparoscopic choledochotomy.

BACKGROUND: One hundred eighty-one patients were submitted to laparoscopic common bile duct exploration. METHODS: A transcystic approach was used in 147 patients, choledochotomy in 14, and both in 20. The indications to perform a choledochotomy included stones larger than 20 mm, stones proximal to the cystic duct entrance, and cases in which the transcystic duct approach proved impossible or unsuccessful. RESULTS: The common bile duct was drained by a T-tube in four patients, by laparoscopic sphincterotomy in one, by laparoscopic choledochoduodenostomy in one, and by a 10 Fr endoprosthesis in 28. The stent placement was technically feasible in all patients but one. The biliary drainage was adequate. Mean hospital stay was 2.1 days. Complication was limited to one umbilical infection and one self-limited biliary leak. CONCLUSIONS: The procedure proved to be technically simple, safe, and efficient, and resulted in a low morbidity rate and short hospital stay.

Adolescent↗
PubMed1998

Candida parapsilosis fungemia associated with implantable and semi-implantable central venous catheters and the hands of healthcare workers.

A cluster of six cases of fungemia among hematology, bone marrow transplant, and oncology patients was investigated in a case-control study (18 controls). The use of implantable and semi-implantable central venous catheters was significantly associated with cases (p = 0.016). The hands of three healthcare workers (HCWs) were positive for Candida parapsilosis. Electrophoretic karyotyping showed two profiles among patients and HCWs, and five among six unrelated strains. The profiles of two HCWs matched the ones of the patients they had handled. The patients' strains were moderate or strong slime producers, whereas none of the HCWs' were strong producers. In conclusion, our results indicated the occurrence of an outbreak C. parapsilosis fungemia related to long-term central venous catheters in which the hands of HCWs were implicated. The amount of slime production might be associated with the pathogenicity of the strains.

Adolescent↗
PubMed1997

Proton magnetic resonance spectroscopy in Steele-Richardson-Olszewski syndrome.

Proton magnetic resonance spectroscopy, localized to the lentiform nucleus, was carried out in nine patients with a clinical diagnosis of Steele-Richardson-Olszewski syndrome (SRO) and in eight healthy age-matched controls. Three of the nine SRO patients had a so-called "eye of the tiger sign" with high signal in the globus pallidus surrounded by a ring of low signal on T2 weighted magnetic resonance imaging previously only reported in Hallervorden-Spatz disease. One of these patients had pathologically proven SRO at postmortem. The SRO group showed a significant reduction in the median concentration from N-acetyl groups (median, 6.87 mM; range, 4.92-10.59 mM; p < 0.015) compared with the control group (median, 9.85 mM; range, 9.26-11.0 mM). The N-acetylaspartate concentration was significantly reduced in seven of the nine patients studied. The reduction of the N-acetylaspartate-creatine ratio from the lentiform nucleus in the SRO group may reflect neuronal loss, occurring predominantly in the globus pallidus. Proton magnetic resonance spectroscopy may be a useful, noninvasive technique to help differentiate the various parkinsonian syndromes.

Adult↗