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Biomedical subjects

C Machado

Publications and source records attributed to C Machado.

At least 37 records · Page 2Linked to original sources
PubMed1997

Torsade de pointes as a complication of subarachnoid hemorrhage: a critical reappraisal.

Subarachnoid hemorrhage is widely accepted as a potential cause of torsade de pointes (TdP), yet this putative etiologic relationship has never been systematically evaluated. We therefore undertook a MEDLINE search from 1966 through 1993, with relevant back referencing, and identified 20 cases of TdP in the setting of subarachnoid hemorrhage. It was impossible in any of these cases (usually because of insufficient data) to completely exclude one or more alternative explanations for TdP, including congenital long QT syndrome, hypokalemia, hypomagnesemia, or drug-induced QT prolongation. Furthermore, of a total of 1,139 patients in 16 prospective series of subarachnoid hemorrhage with electrographic analyses, there were only five reported cases of TdP, all in patients with hypokalemia. Thus, extremely limited scientific data exist to support the notion that subarachnoid hemorrhage can be a distinct cause of TdP. Until more definitive evidence is available, the development of TdP in patients with subarachnoid hemorrhage is probably better characterized as a multifactorial phenomenon occurring in an acute, typically intensive care, setting.

Electrocardiography↗
PubMed1997

[Role of bones in the physiopathology of idiopathic hypercalciuria: effect of amino-bisphosphonate alendronate].

Previous studies from our laboratory demonstrated that bone mineral content is affected in patients with idiopathic hypercalciuria and that there is a correlation between bone mineral loss and in-vitro cytokine production. At the same time we found that short term treatment with alendronate decreased urinary calcium in these subjects. In the present study we have examined the long-term effects of alendronate treatment (10 mg/day for one year) on urinary calcium, urinary hydroxyproline and bone mineral content in 18 idiopathic hypercalciuric and 8 normocalciuric stone formers. Clinical characteristics, as well as gender and age distribution were similar in both groups. Urinary calcium and hydroxyproline, were measured monthly. Calcium excretion decreased significantly at the end of the first month, and remained lower thereafter (277 +/- 28, before vs. 202 +/- 26 mg/g creatinine, after 12 months on alendronate, p < 0.01). Urinary hydroxyproline decreased significantly during the study (125.5 +/- 32.1 vs. 39.66 +/- 17.5 mg/g creatinine, p < 0.05). Serum calcium, glomerular filtration rate, and urinary sodium, did not change during the study. Lumbar spine bone density (trabecular bone) obtained with X ray absorptiometry revealed a significant increase from 1.162 +/- 0.231 to 1.197 +/- 0.248 g/cm2 (p < 0.01). These changes were associated with a significant decrease in IL-1 alpha mRNA transcription by unstimulated and lipopolysaccharide stimulated blood mononuclear cells, as tested by the reverse transcriptase polymerase chain reaction. No changes were observed in bone cortical sites (femoral neck). Normocalciuric subjects showed no significant changes in urinary calcium. In summary, the changes observed in urinary calcium excretion and different bone metabolic parameters, suggest a role of bone in the pathophysiology of idiopathic hypercalciuria.

Alendronate↗
PubMed1996

Probucol-associated tachyarrhythmic events and QT prolongation: importance of gender.

From published articles and adverse reactions reports filed with the FDA (available through the Freedom of Information Act), we analyzed occurrences of tachyarrhythmias and the magnitude of QTc prolongation associated with probucol therapy. Of 16 cases of tachyarrhythmic events reported in association with probucol, 15 (94%) occurred in women (p < 0.01 vs expected value of 58%). Tachyarrhythmias were specifically described as TdP in 11 (63%) cases, all women; additional potential contributory QT-prolonging factors (besides probucol) were not identifiable in 2 of the 11 cases. We also analyzed QTc responses in 359 probucol-treated patients, all having baseline QTc < or = 0.44 sec1/2. At doses of 500 to 1000 mg/day, probucol-associated prolongation of QTc to values > or = 0.45 sec1/2 was observed in 22% of women versus 7% of men (p < 0.001) and to values > or = 0.47 sec1/2 in 8% of women versus 2% of men (p < 0.03). Multivariate analysis identified baseline QTc (p < 0.0001) and female gender (p < 0.03), but neither age nor dose, as significant independent predictors of QTc prolongation to > or = 0.45 sec1/2 with probucol. These findings have relevance to the clinical use of probucol, provide further evidence that women have a relatively greater predisposition to development of acquired long QT syndrome, and carry implications for the design of trials involving QT-prolonging drugs.

Adult↗
PubMed1996

Pacemaker patient-triggered event recording: accuracy, utility, and cost for the pacemaker follow-up clinic.

Many pacemaker patients have vague symptoms following implantation. It is often difficult for the physician to ascertain if they are cardiac in origin. A new pacemaker feature has been introduced, Patient-Triggered Event Records (PTER), to help the physician with this diagnosis. The PTER is a continuously running event record which stores the cardiac rhythm and rate. Brief application of a magnet will transfer the record into the device's memory. The data recorded will be the 97 events prior to the magnet application and the 30 events following magnet removal. The exact state of pacing (atrial and ventricular sensing/pacing, or premature ventricular events) and the rate of the ventricular events will be graphically displayed by the programmer for all 127 events. Thus, the exact pacer and cardiac rhythm can be determined during the period of the symptomatic episode. A total of three PTER's can be stored within the device. If a fourth is recorded, it will replace the oldest record. Three pacemakers with the PTER feature were tested in vitro with five different simulated cardiac rhythms. A beat-by-beat comparison between the PTER and the 15 simulated test rhythms revealed a 100% accurate documentation by PTER. Sixteen pacemaker patients which have the PTER feature were monitored using a King of Hearts for a total of 43 symptomatic events. The PTER records produced clinically relevant information 98% of the time while the King of Hearts produced clinically relevant information 81% of the time. A comparison of costs of the two different methods of monitoring these patients, was $2,432 versus $4,480 for the PTER and loop event monitor respectively. The PTER is an accurate, lower cost method for monitoring and diagnosing symptomatic pacemaker patients. The PTER can be used as the first diagnostic tool in troubleshooting patients with paroxysmal symptoms in the pacemaker clinic population.

Adult↗
PubMed1996

Nocturnal and respiratory disturbances in Steele-Richardson-Olszewski syndrome (progressive supranuclear palsy).

Respiratory and sleep disturbances may be important causes of morbidity in Steele-Richardson-Olszewski syndrome but the frequency and character of nocturnal abnormalities remains uncertain. A prospective study of 11 patients with Steele-Richardson-Olszewski syndrome and age-matched control subjects was undertaken using clinical assessments, a structured sleep questionnaire, spirometry, static maximum inspiratory and expiratory pressures and nocturnal oximetry. The mean age of the Steele-Richardson-Olszewski syndrome patients was 63.2 (52-70) years and mean disease duration was 4.0 (2-6) years. There was moderate to severe motor disability in nine and mild to moderate dementia in eight. In the patients with Steele-Richardson-Olszewski syndrome the following abnormalities contributed to sleep disturbances significantly more frequently than in normal controls: depression, dysphagia, frequent nocturnal awakenings (usually associated with urinary frequency), immobility in bed, difficulty with transfers, impaired dressing and feeding. There was profound impairment of voluntary respiratory control whilst automatic and limbic control were well maintained. Nocturnal respiratory abnormalities were not present even in the most severely disabled. In Steele-Richardson-Olszewski syndrome sleep abnormalities are common; they relate to the cognitive, pseudobulbar and extrapyramidal disturbances and may therefore be amenable to symptomatic control.

Aged↗
PubMed1995

T-cell malignancies in Brazil. Clinico-pathological and molecular studies of HTLV-I-positive and -negative cases.

T-cell malignancies in Brazil have a high seroprevalence rate of HTLV-I antibodies. We have analyzed the disease features in 188 Brazilian patients with a T-cell disorder. These included 40 with T-lymphoblastic leukaemia or lymphoma (T-ALL/T-LbLy) and 148 with mature T-cell diseases: 5 T-prolymphocytic leukaemia, 53 adult T-cell leukaemia/lymphoma (ATLL), 54 cutaneous T-cell lymphomas, 29 pleomorphic T-cell lymphomas and 7 large granular lymphocyte leukaemia. The diagnosis was based on clinical, morphological and immunological features and HTLV-I serology. ATLL in Brazil has the same diseases features as in other endemic regions, the only apparent differences being: age, Brazilian patients being younger than Japanese, and ethnic grouping, one third of Brazilians being white Caucasians of European descent. We applied a scoring system based on the presence or absence of typical features associated with ATLL; hypercalcaemia, cell morphology, immunophenotype, histopathology and HTLV-I status, to see whether it may help in diagnosing cases of ATLL. All had high scores, whereas all other T-cell diseases scored low. Only 5 ATLL cases were HTLV-I-negative by serology, but they had otherwise typical features of ATLL, and their cells did not have HTLV-I proviral sequences by DNA analysis. Such cases suggest that ATLL may develop in a minority of individuals living in regions where it is endemic, without evidence of HTLV-I infection, and that other factors may contribute to the pathogenesis of the disease.

Adolescent↗
PubMed1995

Increased propensity of women to develop torsades de pointes during complete heart block.

INTRODUCTION: To determine whether an increased female gender susceptibility to torsades de pointes (TdP) may exist in a clinical model of bradycardia-induced long QT syndrome, we investigated reported cases of TdP associated with acquired complete heart block. METHODS AND RESULTS: Seventy-two cases reported in the medical literature dating from 1941 through 1993 were identified, all describing TdP or "transient ventricular tachycardia/fibrillation" (to include those cases reported prior to the use of TdP terminology) in the setting of acquired complete heart block unassociated with QT prolonging drugs. Expected female prevalence in complete heart block was estimated at 52%, based on projections derived from 206,016 hospital discharges in the National Inpatient Profile (Commission on Professional and Hospital Activities, Ann Arbor, MI), over the years 1985 through 1992. During complete heart block, mean heart rate was 37 beats/min in both sexes (combined n = 43), and absolute QT interval ranged from 0.52 to 0.88 seconds, with a mean of 0.68 seconds (n = 25). Female prevalence among patients with TdP during complete heart block was greater than expected: 72% for all studied cases (P < 0.001); 70% (P < 0.04) and 74% (P < 0.02) among those reported prior to (n = 35) and during or after (n = 37) 1980, respectively; 73% (P < 0.03) among those with documented normokalemia (n = 26); and 68% (P = 0.2) among those with a prolonged QT interval and known polymorphic VT (i.e., unequivocal TdP; n = 25). CONCLUSION: Despite inherent limitations of this retrospective study, the data are consistent in suggesting a greater than expected female prevalence among patients with TdP related to complete heart block. This finding lends support to a broadening concept of increased susceptibility of women to the development of TdP in various settings of QT prolongation.

Adult↗
PubMed1994

Death on neurological grounds.

During centuries, the loss of spontaneous cardio-pulmonary function was found to predict permanent non-functioning of the "organism as a whole", therefore serving adequately as a criterion of death, but during the era of Intensive Care, there was a shift to brain-oriented definitions of death, ie, the irreversible cessation of brain functions, started to be considered as the main reason for cessation of functioning of the "organism as a whole". A concept or definition of death is related to the question: What is it "about human life, which is irreplaceable by any artifice, and that its loss is so essential, that the individual who loses it ought to be called dead?" Further work has been centered on how much of the brain needs to be dead, before a person can be declared dead on neurological grounds: "whole brain", "brainstem death" ("brain as a whole") and "higher brain" formulations of death. These brain-oriented formulations of death are discussed and criticized, with the conclusion that although there is only one function, irreplaceable, which characterizes the human being: the "content" of consciousness, society is not yet prepared to define, diagnose and accept a "content" of consciousness-based standard of death, when this function is lost in isolation in PVS, advanced forms of dementia and anencephalics. I propose a concept of death that excludes those states taking in consideration the basic mechanisms of consciousness generation in human beings: "The irreversible loss of consciousness, considering both its capacity and its content". This definition of human death takes consideration as hallmarks, both components of consciousness which are essentially significant to the nature of man, to provide the functioning of the "organism as a whole".

Brain Death↗
PubMed1993

Hypothyroid cardiac tamponade presenting with severe systemic hypertension.

Hemodynamic data are presented which not only depict typical tamponade physiology, but demonstrate that hypotension may not necessarily be present with slow accumulation of pericardial fluid in myxedema patients. This case is unique in that severe hypertension, as part of the presentation of hypothyroid tamponade, has never been reported.

Cardiac Tamponade↗
PubMed1993

Visual evoked potentials and electroretinography in brain-dead patients.

Visual evoked potentials and electroretinograms were elicited by light-emitting diode stimulation and recorded simultaneously, with cephalic and noncephalic references, in 30 normal subjects and in 30 brain-dead patients. A characteristic pattern was found in the group of patients: when a cephalic reference was used for both visual evoked potentials and the electroretinogram, the a- and b-waves of the electroretinogram were recognized in all patients, and visual evoked responses consisted of waves with inverse polarity, similar morphologic characteristics, the same latency, and less amplitude than those of the electroretinogram. When a noncephalic derivation was chosen for the electroretinogram and visual evoked potentials, electroretinogram did not change in either morphologic features or latency, whereas the visual evoked potential channel showed no response. Only in two cases was it possible to record waves in the visual evoked potential lead with a noncephalic reference, showing a spread of the electroretinogram to the occipital area, with a considerably reduced amplitude. These results suggest that, although contamination of visual evoked potential records by the spread of the electroretinogram to the occipital area could occur, it is easy to confirm the absence of a true cortical visual response in brain-dead patients by means of a noncephalic reference. This pattern clearly confirms that in the visual pathways of brain-dead patients, electrical activity is confined to the retina.

Adolescent↗
PubMed1993

Confirmation of anomalous origin of the right coronary artery from the left sinus of Valsalva with magnetic resonance imaging.

Anomalous origin of the right coronary artery from the left sinus of Valsalva is a rare but clinically significant congenital abnormality, difficult to diagnose angiographically. We describe a patient in whom magnetic resonance imaging was used to delineate the anomalous course of the right coronary artery following angiographic demonstration limited by technical considerations.

Cardiac Catheterization↗
PubMed1993

Multimodality evoked potentials and electroretinography in a test battery for an early diagnosis of brain death.

A test battery conformed by multimodality evoked potentials (MEP) and electroretinography (ERG) was applied to 30 brain-dead patients. Three patterns of brainstem auditory evoked potentials (BAEPs) were observed: (1) No identifiable waves (73.34%); (2) an isolated bilateral wave I (16.66%) and (3) an isolated unilateral wave I (10%) (Fig. 1,2,3). Waves II, III, IV, and V were not observed in any of the cases. Whenever wave I was recorded, it was always significantly delayed. For short latency evoked potentials (SSEPs) a characteristic pattern was found: absence of cortical N20 and later responses in scalp-cephalic records and preservation of the so-called subcortical components in the rest of the derivations. For visual evoked potentials (VEPs) and electroretinography (ERG) the same pattern was found in all cases: when a cephalic reference was used for both, VEPs and the ERG, waves a and b of the ERG were recognized in all cases. The visual evoked responses consisted of waves with less amplitude but very similar in latency and morphology to the ERG. When a non-cephalic channel was chosen for the ERG and VEPs, the ERG waves showed no changes either in morphology or in latency, while the VEP lead showed no response. It is discussed that the consideration of MEP and ERG in a battery test to evaluate brain-dead patients increase diagnostic reliability, which is fundamental for an early diagnosis of brain death.

Adolescent↗
PubMed1993

Short latency somatosensory evoked potentials in brain-dead patients using restricted low cut filter setting.

This paper describes the SSEP patterns in BD when using restricted filter bandpass setting, with special emphasis on the dissociation of some SSEP components when cephalic and non-cephalic references are used. A characteristic SSEP pattern was found: absence of N20 and later responses in the Cc'-Fpz lead and preservation of all or some of the so-called subcortical components in the rest of the derivations. We noted an interesting dissociation in which some SSEP components were not recorded in the scalp-non cephalic derivations, but they were still present in the neck-cephalic and spine channels, with inverse polarity. We selected a restricted bandpass for the scalp-non cephalic, the neck-cephalic and the spine derivations, and we found this dissociation not only for P13-N13 and P14-N14, but for Nm-Pm' and Pm-Nm' components. It is likely that components Nm-Pm' and Pm-Nm' are "far-field potentials" that appear when the slow wave N18 is filtered out by the use of a restricted low filter setting. Our data further suggest that all components after N14-P14, recorded with restricted filter bandpass also recognize two distinct generator sources. Rostral generators are located probably in the brainstem and/or thalamus, but at least a significant part of these SSEP components are generated at the very lower part of the medulla oblongata (dorsal column nuclei) and/or at the upper cervical spine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Systemic lupus erythematosus murine monoclonal DNA-binding antibodies recognize cytoplasmic and nuclear phosphorylated antigens that display cell cycle redistribution in HEp-2 cells.

The immunological basis for the production of autoantibodies characteristic of systemic lupus erythematosus (SLE) against a wide range of antigens remains obscure. The specificity of (NZB x NZW)F1 (BWF1) or MRL/Mp-lpr/lpr (MRL/lpr) mouse monoclonal antibodies (mAb) was examined by immunofluorescence, immunoblotting and immunoprecipitation techniques. Using non-synchronized HEp-2 cells as substrate, the murine mAb were classified by indirect immunofluorescence into five groups on the basis of their staining patterns of subcellular components in interphase and mitotic stages of the cell cycle. The nature of the antigens recognized by the murine lupus was assessed by immunoblotting experiments in total, cytoplasmic and nuclear cell extracts from HEp-2 cells. The six antibodies used recognized in total cell extracts a range of polypeptides with apparent molecular weights from 25,000 to 210,000. Three polypeptides of 130,000, 110,000 and 45,000 MW were recognized by all six antibodies in both nuclear and cytoplasmic extracts. Immunoprecipitation of total cellular extracts labelled with [35S]methionine showed almost the same pattern as obtained in the immunoblotting assay. The labelling in vivo of HEp-2 cells with [32P], followed by the immunoprecipitation of the [32P]cell lysate showed that these mAb recognized phosphorylated proteins. The progressive decrease in reactivity of these mAb following treatment with higher concentrations of alkaline phosphatase in both [32P]cell lysate or nitrocellulose membranes indicates that these mAb recognize phosphorylated epitopes.

Animals↗
PubMed1990

Brain electrical field measurements unaffected by linked earlobes reference.

Recent theoretical analysis supports the possibility that using a linked earlobe reference in EEG studies might appreciatively distort the measured electrical field due to current flow over a low resistance path across the wire joining both ears. Such an effect would invalidate published quantitative EEG norms. Evidence for the balancing effect of this distortion was sought for in the EEG of 4 patients with well localized unilateral lesions, a situation in which this distortion would be most apparent. Statistical tests failed to reveal significant differences between EEGs recorded when ears were linked or unlinked. An analysis of the equivalent circuit reveals that a high skin/electrode impedance effectively makes the linked ear reference behave as an ordinary reference.

Brain↗