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Biomedical subjects

J Doucet

Publications and source records attributed to J Doucet.

At least 91 records · Page 5Linked to original sources
PubMed1994

Does age play a role in clinical presentation of hypothyroidism?

OBJECTIVE: To determine if aging modifies the clinical presentation of hypothyroidism. DESIGN: Comparison of 24 clinical signs of hypothyroidism between elderly patients (> or = 70 years of age) and younger patients (< or = 55 years of age). SETTING: Prospective study of patients with chemically confirmed overt hypothyroidism. PATIENTS: Sixty seven elderly patients (79.3 +/- 6.7 years) and 54 younger patients (40.8 +/- 9 years) were included in the study. RESULTS: Neither mean duration of evolution nor mean thyroid-stimulating hormone (TSH) level were different between the 2 groups. Two signs were found in more than 50% of the elderly patients (fatigue and weakness). Four signs were significantly less frequent in elderly patients (chilliness, paresthesiae, weight gain, and cramps). Mean number of clinical signs in the elderly (6.6 +/- 4) was significantly smaller than in young patients (9.3 +/- 4.7) (P < 0.01). CONCLUSIONS: Our results suggest that the presentation of hypothyroidism is altered in the elderly in comparison with young patients in that there are (1) fewer signs or symptoms and (2) diminished frequency of some classical signs. Our results underline the importance of TSH measurement in the elderly.

Adult↗
PubMed1994

Psychophysical and physiological forward masking studies: probe duration and rise-time effects.

To determine if the amount of forward masking observed in single auditory-nerve fibers of the chinchilla was sufficient to account for the amount of masking observed behaviorally in humans, thresholds for the detection of several types of probe signals following a forward masker were measured in both behavioral and physiological experiments. It is necessary to use the same probe stimulus characteristics in both behavioral and physiological experiments to make valid comparisons between the two measures of forward masking. Experiment 1 was behavioral and used human listeners. Two types of probe signals were used, differing in overall duration and rise/fall times. The two probes yielded different growth of masking functions. These results further demonstrate that forward masking characteristics in behavioral experiments are critically dependent upon the parameters of the probe signal used. Experiment 2 was physiological and used chinchillas. The amount of masking for high-level maskers using the same two probe types in a physiological "forced-choice" experiment are presented. In contrast with the behavioral results, there was little or no difference in the amounts of masking observed for the two probes. In addition, the amounts of masking observed in some auditory-nerve fibers were considerably smaller than those observed behaviorally. These experiments further demonstrate that the amount of forward masking observed in single auditory-nerve fibers is inconsistent with that observed behaviorally.

Acoustic Stimulation↗
PubMed1994

[Renal metastases from cancer. Apropos of 9 cases and review of the literature].

We report 9 cases of secondary carcinomas of the kidney. The primary source of cancer was found in the lungs (7 cases), in the larynx (one case) and in the pyriform sinus. Clinical or radiologic signs of these renal metastases were comparable to primary carcinomas of kidney. The mean survival outlook for these patients was 8.1 months. Radical nephrectomy was performed in five cases. In a patient previously treated for a primary carcinoma and especially for a lung carcinoma, when a solid renal mass of kidney is discovered the hypothesis of a renal metastasis must be kept in mind. Because of lack of specific feature of these tumours and because of their often poor prognosis further investigations such as percutaneous fine needle aspiration for cytopathologic study must be considered.

Adult↗
PubMed1993

Protein binding of digitoxin, valproate and phenytoin in sera from diabetics.

Chronic hyperglycaemia results in glycation of serum albumin and might affect the binding of drugs. The aim of the present study was to compare, using an equilibrium dialysis method, the protein binding of therapeutic concentrations digitoxin, valproate and phenytoin in sera from 70 insulin-dependent diabetics and 25 controls. Drug concentrations were measured by fluorescence immunopolarisation. Glycated albumin was measured by laser nephelometry after affinity chromatography. In sera from diabetics, protein binding of digitoxin (88.8 versus 89.9%) was unchanged; the protein binding of valproate (75.2 versus 80.7%) and phenytoin (67.9 versus 75.3%) was significantly decreased, but with no correlation with the concentration of glycated albumin. We conclude that the difference in protein binding between diabetic and control sera is due to glucose-independent modification of albumin in diabetics.

Adult↗
PubMed1993

[Increase of aminotransferases].

Elevated aminotransferases activities are frequent in medical practice. In acute elevations, the mains causes are generally easily found (viral, drug-induced, toxic, ischemic). In moderate or prolonged elevations, the most frequent causes are steatosis (alcoholic, diabetes, obesity) and chronic hepatitis (viral B, D, C, drug-induced and auto-immune diseases.

Acute Disease↗
PubMed1992

Isolation and characterization of hamster brain polyribosome-cytomatrix complexes.

We have developed a method for the isolation of a brain subcellular fraction enriched in both highly aggregated polyribosomes and cytoskeletal proteins. This method is based on gentle dispersion of brain tissue and low speed centrifugation. This fraction is enriched in typical cytoskeletal proteins as glial fibrillary protein, neurofilament proteins and actin. Messenger RNA did not seem to be involved in the polyribosome association to the cytomatrix as shown by the effect of exposure to micrococcal nuclease. On the other hand, in vivo disruption of protein synthesis by acute experimental phenylketonuria, hypothermia or heat-shock did not cause the release of ribosomes from the cytomatrix.

Actins↗
PubMed1991

Oriented structure in human stratum corneum revealed by X-ray diffraction.

Various types of human stratum corneum (sheets or callus) were exposed, in parallel and perpendicular geometry, to the high flux of X rays produced by a synchrotron radiation source. Under these conditions, very clear and rich diffraction patterns, corresponding to the supramolecular organization of stratum corneum proteins and lipids, were obtained. The comparative study of normal or delipidized stratum corneum sheets and membrane couplets allows one to attribute certain diffraction features to lipids. Our results in the 3-7-nm range show two different distances for lipid bilayers. Concerning the protein nature of normal stratum corneum, the results show that keratin would occur in the beta form, whereas for callus it is in the alpha form. Indeed, normal stratum corneum sheets never display the 0.514-nm characteristic of alpha keratin. This result means that the supramolecular organization of keratin could depend on the keratinization process. Finally, our studies also confirm the presence of a still-unknown protein component existing in the beta form that would be located either inside the corneocytes or in some dilatated zones of the intercellular spaces.

Humans↗
PubMed1991

[Prognostic value of exercise angioscintigraphy in coronary disease].

Multivariate survival analysis (MSA) was applied to 97 patients with coronary disease using the Cox model and a stepwise regression procedure. Seventeen variables including data based upon clinical examination, exercise testing (ET), and exercise angioscintigraphy (EAS) as well as coronary arteriography were studied in each patient. During the monitoring period (interval: 1-57 months), 38 patients sustained a cardiac event (recurrence of coronary disease or death). Neither resting left ventricular ejection fraction, nor coronary anatomy were significant prognostic variables. The only two variables identified by MSA were a variable of EAS: corrected ejection fraction at maximum exercise (p less than 0.008), and a variable of ET: maximum heart rate during exercise (p less than 0.03). This study shows that the prognosis of a coronary disease patient can best be assessed by two variables which are both exercise parameters.

Adult↗
PubMed1991

[Doppler echocardiographic evaluation of the efficacy of fibrinolytic treatment of pulmonary embolism].

The efficacy of the fibrinolytic therapy in pulmonary embolism was studied by Doppler echocardiography: the evolution of the cardiac and angiographic changes could be studied in parallel. Thirty patients with severe pulmonary embolism and vascular obstruction greater than 40% (67.2 +/- 9.9%) were examined prospectively by Doppler echocardiography before and after thrombolysis. The following parameters were studied: systolic pulmonary artery pressure calculated from the jet of tricuspid regurgitation and left and right ventricular diameters for the calculation of the ratio of the ventricular dimensions. All patients underwent Doppler echocardiography and pulmonary angiography immediately after thrombolysis. The average improvement of the percentage vascular obstruction was 37%. The hemodynamic and echocardiographic changes were globally favourable. The pulmonary artery systolic pressure fell from 51 +/- 10 to 33 +/- 6.7 to 25.3 +/- 6.3 mm and the ratio of ventricular dimension from 0.87 +/- 0.3 to 0.60 +/- 0.16 (p less than 0.001). Only 4 patients had pulmonary artery systolic pressures over 40 mmHg after therapy compared with 26 before therapy. However, the hemodynamic and angiographic correlations were poor (r = 0.37; p less than 0.001). In the 6 patients in whom treatment was ineffective according to angiographic criteria (less than 20% improvement of vascular obstruction), the echocardiographic changes were small or absent, the improvement in the ratio of ventricular dimensions being less than 20%. However, a satisfactory correlation was observed between the percentage improvement of the ratio of ventricular dimensions and that of vascular obstruction (r = 0.59; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Therapeutic value of esophageal stimulation. Factors influencing the results in flutter and atrial tachysystole].

The aim of this prospective study was to identify factors predicting the efficacy of atrial stimulation by esophageal route in 57 nonselected patients between 37 and 88 years of age and admitted for intensive care due to flutter or atrial tachycardia. It was impossible to perform the procedure correctly in 4 patients. The restoration of sinus rhythm was achieved in 28.3% of cases at the end of the procedure and in 47.2% of cases after 24 hours. These results were influenced by the duration of the arrhythmia, the underlying cardiopathy and the diameter of the left atrial, but were not affected by the stimulation parameters.

Adult↗
PubMed1990

[Malignant histiocytofibroma of the heart simulating myxoma of the left atrium].

The authors report a case of malignant fibrous histiocytoma of the left atrium which was excised but rapidly recurred in a 47-year-old woman. Clinical examination, echocardiography and the absence of biochemical abnormalities were in favour of the diagnosis of left atrial myxoma. This report illustrates the clinical similarity between myxoma and sarcoma of the left atrium. Very careful anatomopathological examination of multiple sections of the tumour are necessary to distinguish it from benign tumours, especially myxomas.

Diagnosis, Differential↗
PubMed1990

[Cysts of the parathyroid glands. Apropos of 6 cases].

Parathyroid cysts are rare lesions. Pathological examination distinguishes the "true" parathyroid cysts (non functional) most often present and cystic degeneration of a parathyroid adenoma (rare) with clinical or biochemical evidence of hyperparathyroidism. With the increased use of ultrasound and fine needle aspiration biopsies, the diagnosis of these cysts can be confirmed by an elevated parathyroid hormone (PTH) assay. The non-functioning parathyroid cysts can be successfully treated by total aspiration of the cyst fluid. Surgical exploration of all parathyroid glands is the treatment of choice for hyperparathyroidism. The different proposed etiologies for parathyroid cysts are discussed.

Aged↗
PubMed1990

[Differential analysis of mitral and tricuspid regurgitation by continuous Doppler].

The following parameters have been measured by continuous Doppler in 40 patients with both mitral failure (MF) and tricuspid failure (TF): effusion time (ET), peak time (PT), maximum effusion speed (S. max), maximum anterograde speed (S. ant), taking into account the cardiac rate and the ejection fraction. Only the S. max. and the S. ant. are significantly different and enable the determination of the effusion origin with a percentage error of about 4%. When a straight line is drawn to joint 3.7 m/s on the ordinate (S. ant) and 5 m/s on the abcissa (S. max), the TF lie below the line and the MF above it. The selection of the sub-groups with low ejection fraction (less or equal to 30%) or with arterial pulmonary hypertension (S. max MF higher or equal to 3 m/s) does not modify the precision of the discrimination. The graph suggested seems therefore to be a rapid and reliable means of characterizing TF in order to assess the arterial pulmonary hypertension of dilated hypokinetic cardiomyopathies.

Adult↗
PubMed1989

The highly concentrated liquid-crystalline phase of DNA is columnar hexagonal.

The DNA molecule is extremely compacted in bacteria, in cell nuclei, sperm heads and virus capsids. These interactions between DNA molecules are important to our understanding of chromatin condensation. DNA forms multiple liquid-crystalline phases whose nature depends on the polymer concentration, and it has been suggested that the highly concentrated phase of 50-nm DNA molecules is two-dimensionally ordered and smectic-like. We rule out this smectic hypothesis and demonstrate by polarizing microscopy, electron microscopy and X-ray diffraction that this phase is characterized by a columnar longitudinal order and a hexagonal lateral order, with intermolecular distances ranging from 2.8 to 4.0 nm depending on the DNA concentration.

Crystallization↗
PubMed1989

Coexistence of A- and B-form DNA in a single crystal lattice.

It is well known that DNA can exist in a variety of conformations which can be interconverted by relatively mild changes in conditions. The in vivo conformation of DNA is usually thought to be the B form, but there is recent evidence that other conformations may be important in DNA-protein recognition. Different fragments of DNA crystallized under virtually identical conditions can form A, B or Z helices. A fragment that adopted an A conformation in a crystal was found in the B conformation in solution, whereas NMR spectroscopy of A-DNA films revealed the presence of a substantial amount of disordered B-DNA. Until now, however, a DNA fragment of a given sequence has not been crystallized in more than one global conformation. We report here an X-ray diffraction study of crystals of the DNA octamer dGGBrUABrUACC. In addition to a 'framework' of A-DNA, which gives discrete X-ray reflections, there are partially disordered B-DNA helices, recognized by their diffuse scattering features.

Bromodeoxyuridine↗