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Biomedical subjects

D Robert

Publications and source records attributed to D Robert.

At least 127 records · Page 7Linked to original sources
PubMed1992

Sleep apnea syndromes (SAS) of specific etiology: review and incidence from a sleep laboratory.

Sleep apnea syndrome (SAS) results from modification in the control of respiration and of upper airway caliber during sleep. Although there is some overlap between central (CSAS) and obstructive (OSAS) sleep apnea syndromes, each syndrome has specific pathological associations. The first part of this review concerns the pathophysiology of OSAS, including periodic breathing and upper airway collapse. In the second part, each specific etiology is examined, and the respective contribution of anatomic narrowing and neuromuscular dysfunction of the upper airway is mentioned. Our experience with about 375 patients with sleep-related breathing disorders is also reported, with regard to the specific etiologies of CSAS and OSAS.

Arousal↗
PubMed1992

[A multiparameter method of computer-assisted objective vocal evaluation].

The aim of this study is to validate an aid for the evaluation of dysphonia with objective measurements. We recorded exhaled airflow, fundamental frequency and sound level pressure, for a sustained vowel "a", with 51 dysphonic subjects and 15 normal subjects. The following measurements are made on these three parameters: mean value, standard deviation and coefficient of variation. The exhaled airflow volume was also computed for a duration of 2 seconds. A principal components analysis of the measurements indicated that it is possible to recognise the classes of vocal evaluation and vocal pathology. These findings reinforce on objective aid for the vocal evaluation of dysphonia.

Diagnosis, Computer-Assisted↗
PubMed1992

An acquired hemorrhagic disorder from long-acting rodenticide ingestion.

A 62-year-old man who presented with gross hematuria was found to have a severe and prolonged coagulopathy. The workup involved mixing studies, which suggested an acquired factor deficiency, and specific factor assays, which demonstrated isolated defects in vitamin K-dependent factors. With vitamin K deficiency excluded, and serum warfarin levels undetectable, so-called superwarfarin ingestion was suspected. This diagnosis was subsequently proved by biochemical evidence (an increase in the serum vitamin K epoxide-vitamin K ratio) and compatible history. This case illustrates how a logical workup can lead to a diagnosis of superwarfarin ingestion, even without a history of such an ingestion. New serum assays for specific superwarfarins are also mentioned. This case report should increase clinicians' awareness of long-acting rodenticide ingestions.

4-Hydroxycoumarins↗
PubMed1991

[Long-term effects of home mechanical ventilation with positive pressure using a nasal mask].

Home mechanical ventilation (HMV) is an efficient alternative in the treatment of patients with chronic respiratory failure secondary to restrictive mechanical disorders (neuromuscular disease, such as Duchenne's disease, thorax deformities due to kyphoscoliosis or tuberculosis sequelae). The case of a patient with severe kyphoscoliosis in the phase of chronic respiratory failure (PaO2 34 mmHg and PaCO2 61 mmHg, breathing ambient air) is presented in which, following the failure of negative pressure mechanical ventilation ("poncho"), positive pressure ventilation was tested with a silicon made-to-measure nasal mask as the access via. Adaptation to HMV was good with the patient using the ventilation nightly. Following 12 months of treatment the patient is able to carry out everyday activities and arterial gasometry breathing ambient air is PaO2 77 mmHg and PaCO2 43 mmHg.

Female↗
PubMed1991

[Converting enzyme inhibitors and acute renal insufficiency--precautions to be taken].

Inhibitors of angiotensin-converting enzyme are used commonly nowadays for the treatment of hypertension and cardiac failure. Over the past two years, shortly after the introduction of this type of drug the occurrence of acute renal failure mainly in elderly patients has been reported. The authors have insisted that strict control of renal function and electrolytes are necessary before and after administration of an ACE inhibitor. Particular caution is needed in patients with severe atherosclerotic disease, especially if bilateral (or unilateral in patients with a single kidney) renal arterial stenosis is present or suspected. Considering these limitations ACE inhibitors remain well tolerated and beneficial cardiovascular drugs.

Acute Kidney Injury↗
PubMed1991

Isolation from wheat mitochondria of a membrane-associated high molecular weight complex involved in DNA synthesis.

A high molecular weight mitochondrial DNA (mtDNA) replication complex, associated with the mitochondrial membrane, was isolated by sucrose gradient centrifugation from purified wheat embryo mitochondria. This complex comprised the mtDNA as well as enzyme activities involved in the replication and transcription of the organelle genome, such as DNA polymerase, RNA polymerase and topoisomerase type I. The isolated complex is active in mtDNA and mtRNA synthesis in vitro. Electron microscopy and lipid analysis confirmed the membrane origin of this complex. Enzyme activities are resistant to physiological ionic strengths, 0.1-0.2 M KC1, while the membrane-mtDNA association is resistant up to 1 M KC1. DNase treatment of the complex released the DNA polymerase activity while protease treatment solubilized mtDNA, suggesting the direct interaction of mtDNA with membrane protein(s). The use of a novel approach to detect mtDNA fragments specifically retained by the mitochondrial membranes after Sal I digestion of the complex suggests that specific mtDNA sequences anchor mtDNA to mitochondrial membranes.

Cell Fractionation↗
PubMed1991

Severe falciparum malaria (21 cases).

The incidence of severe falciparum malaria is increasing in the developed countries and mortality remains high despite progress in intensive care management and schizonticide treatment. Many authors emphasize the importance of exchange transfusion (EXT) in the most severe cases. We studied 21 cases (34 +/- 12 years, 6 females; SAPS: 8.4 +/- 3.7) of severe malaria (according to WHO criteria) consecutively admitted to ICU between 1985 and 1990: 3 patients underwent EXT. Twenty were febrile above 39 degrees C, 10 had cerebral malaria, 14 hepatic impairment, 8 acute renal failure, 5 pulmonary oedema. Nine patients required mechanical ventilation, 1 haemodialysis, 1 intracranial pressure monitoring. Mean parasitemia was 13%, 16 patients had thrombocytopenia less than 50 x 10(9)/l, 3 anemia less than 7 g/dl and 3 leucopenia less than 2.8 x 10(9)/l. Nineteen received quinine i.v., 1 mefloquine, 1 chloroquine. Sixteen patients received blood products transfusion, 3 were treated by EXT in addition. Twenty were cured and discharged from hospital without sequelae (mean stay: 14 days); 4 had nosocomial infection, 1 a splenic infarction. One patient (17-years-old; SAPS: 17; parasitemia: 7.8%) died 12 h after admission from non-cardiogenic pulmonary oedema with multi-organ failure. The literature and this study lead us to propose EXT in patients with unfavourable evolution after conventional treatment rather than in all the patients with a parasitemia above 10% at admission. A randomized study to compare conventional treatment in ICU with or without EXT is necessary.

Adolescent↗
PubMed1991

Short- and long-term prognosis, functional outcome following ICU for elderly.

Among 1532 ICU patients we analysed 295 elderly patients (19%) aged more than 70-years-old. We determined prospectively the immediate and subsequent one-year outcome with a study of the predictive value of their ICU admission parameters. Then we followed the ICU survivors over the year after discharge (1, 6, 12 months) by quality of life questionnaires. ICU mortality was 26.7%; SAPS was the only predictor of short term mortality. On ICU discharge, 216 elderly were followed at 1, 6, 12 months; the one-year cumulative mortality was 49% from ICU discharge, majority of deaths occurring over the first month. Age, previous health status and SAPS had a predictor value of one-year mortality for ICU survivors. 103 patients were alive at one year: 88% returned to home, 72% had a relatively good functional status allowing an independent life, and 82% had the same or improved functional status.

Activities of Daily Living↗
PubMed1991

Prognostic significance of early intracranial and cerebral perfusion pressures in post-cardiac arrest anoxic coma.

The prognosis of prolonged cardiac arrests is generally related to brain damage due to the cerebral anoxia. A neurological worsening leading to irreversibility is sometimes associated with an increase in intracranial pressure. We studied for 5 years the early intracranial and cerebral perfusion pressures in 84 patients with deep anoxic coma after cardiac arrest. Intracranial pressure monitoring was set up as soon as possible with an extradural screw over a period of 6 days. No complications occurred using this technique. We recorded the percentage of patients suffering from intracranial pressure peaks over 15 mmHg (a), over 25 mmHg (b) or cerebral perfusion pressures drops under 50 mmHg (c). We obtained during the 1st day of monitoring: (a) 46.4%, (b) 21.4%, (c) 39%; during the 2nd day: (a) 73.6%, (b) 26.3%, (c) 55.9%. Eight patients (9.5%) were still alive after a couple of months, 4 of whom had no neurological sequelae; among the 76 non-survivors 63 (82.9%) had died because of cerebral anoxic damage. A daily comparison between survivors and non-survivors points out that the survivors' intracranial pressures were always lower than in the non-survivors and the survivors' cerebral perfusion pressures higher than in the non-survivors. Moreover, none of the patients showing intracranial peak pressures over 25 mmHg survived without after-effects. It is clear that many patients suffer early periods of high intracranial pressures and low cerebral perfusion pressures leading to a bad neurological prognosis. Intracranial pressure monitoring may allow assessment of patients' neurological status and prognosis after cardiac resuscitation.

Adolescent↗
PubMed1991

[Comparative trials of fluid gelatins on hemostasis in heart surgery in adults].

The purpose of this study was to compare, in adult cardiac surgery, the results of two gelatin substitutes (Plasmion and Haemaccel) especially for haemostasis and coagulation factors. Patients showing before operation any perturbation of blood parameters (anaemia, coagulation troubles) as well as patients suffering from serious complications or deceased in the postoperative period have been excluded. This study was realised with 54 patients randomised in two groups: group P (Plasmion); group H (Haemaccel). Anaesthesia was a diazanalgesia. Hemodilution was used in combination with autologous peroperative blood transfusion and reinfusion of residual blood from ECC after ultrafiltration. The two groups were statistically similar. In average, patients received the same gelatins quantity. The only remarkable findings were: a lesser decrease of platelets number per-ECC: a lesser fibrinogen level in postoperative period with Haemaccel.

Aged↗
PubMed1990

Interactions with tRNA(Lys) induce important structural changes in human immunodeficiency virus reverse transcriptase.

Retroviral RNA-dependent DNA polymerase (reverse transcriptase or RT) uses the 3'OH end of a cellular tRNA as primer to initiate DNA synthesis. Previous work with avian retrovirus has shown that reverse transcriptase is implicated in the selection of cellular virion-encapsidated tRNAs and has shown that the primer tRNA is positioned on the primer binding site near the 5' end of the viral RNA. These mechanisms support the idea that the retroviral polymerase should form complexes with primer tRNA and the specific encapsidated ones. The genomic sequence of human immunodeficiency virus (HIV) allows the prediction that tRNA(Lys3) is the natural primer. In this article we show, using the mobility shift assay, that recombinant HIV reverse transcriptase is able to form a complex with bovine tRNA(Lys.) By fluorescence studies and alpha-chymotrypsin analysis we have observed a modification of the enzyme conformation when reverse transcriptase is bound to the putative primer tRNA. This structural change is specific for tRNA(Lys) although the retroviral polymerase is able to interact with other tRNAs.

HIV↗
PubMed1990

[Current modalities of mechanical ventilation for acute respiratory failure in chronic respiratory insufficiency].

Acute respiratory failure in patients with chronic obstructive lung disease is a frequent and serious complication, with a mortality rate of 20 p. 100 and 57 p. 100 of the patients kept under mechanical ventilation for more than two weeks. The main problem with mechanical ventilation is an unavoidable intrinsic positive expiratory pressure and a hyperinflation that can be increased by the different modes of ventilation. All the classical modes of mechanical ventilation may be used, including control-mode ventilation, assist/control-mode ventilation, intermittent mandatory ventilation and ventilation with inspiratory assistance. Another major problem is weaning from mechanical ventilation as it may take a long time or even be impossible, so that the patients stay in intensive care units for ages or require long-term home ventilation. At the moment, there is no way of predicting the outcome of weaning in each individual subjects, and none of the various ventilation procedures has proved superior to the others. Nasal ventilation has recently been introduced in intensive care where it constitutes a major step forward being less invasive; it avoids intubation in 60 p. 100 of the patients but is more exacting for the physicians and nursing staff; finally, it makes it possible to treat acute respiratory failure at an earlier stage than previously.

Acute Disease↗
PubMed1990

[Prognosis of acute pneumococcal respiratory insufficiency requiring mechanical ventilation].

A retrospective study was carried out between 1980 and 1988 in an attempt to determine the prognostic factors in pneumococcal pneumonia requiring mechanical ventilation. Thirty-six of the 57 patients studied died (63 per cent). The initial severity of the lung disease, was the same in the patients who died and in those who survived. The risk of death was associated with the severity of the septic syndrome, as evaluated by the presence of septic shock, acute renal failure and disseminated intravascular coagulation.

Acute Disease↗
PubMed1990

Inhibition of the p66/p51 form of human immunodeficiency virus reverse transcriptase by tRNA(Lys).

Human immunodeficiency virus (HIV) reverse transcriptase (RT) uses host tRNA(Lys) partially annealed to the primer binding site (PBS) as primer for the initiation of cDNA synthesis. When assaying cDNA synthesis with a template-primer complex formed by an RNA fragment carrying the PBS site and bovine tRNA(Lys) we noticed that an excess of primer tRNA inhibited strongly the DNA polymerase activity of a recombinant HIV RT (p66-p51 heterodimeric form) produced in transformed yeast cells. The same inhibitory effect was observed with animal DNA polymerase alpha, while avian retrovirus RT was neither affected by tRNA(Lys) nor by its specific primer tRNA(Trp). Although the strongest inhibition was observed with tRNA(Lys), other tRNas like tRNA(Phe) and tRNA(Trp) inhibited also the HIV RT, whereas tRNAs specific for valine, proline and glycine had no effect on enzyme activity. Digestion of tRNA(Lys) with pancreatic RNase abolished the inhibition; on the other hand T1 RNase digestion had no effect on the inhibition suggesting a role of the anticodon region in this effect. The 12- and 14-mers corresponding to the anticodon regions of the three bovine tRNA(Lys) isoacceptors inhibited RT activity, indicating that at least an important part of the inhibitory effect could be ascribed to this tRNA region. A strong stimulation of DNA polymerase activity was observed when the effect of tRNA(Lys) was assayed on a recombinant HIV reverse transcriptase produced in a protease deficient yeast strain, which leads to the production of an active p66 enzyme. The same tRNAs that inhibited strongly the heterodimeric form stimulated the p66 form of HIV reverse transcriptase. The results suggest that although both enzymatic forms are able to interact with tRNA(Lys) the topography, as well as the functional implications of the interaction between the precursor and the mature form of HIV reverse transcriptase with the tRNA(Lys) primer, are different.

Base Sequence↗