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Biomedical subjects

F Denis

Publications and source records attributed to F Denis.

At least 109 records · Page 6Linked to original sources
PubMed1994

Major expansion of CD8+ T cells with a predominant V beta usage during the primary immune response to HIV.

A SIGNIFICANT proportion (up to 70%) of individuals experience an acute clinical syndrome of varying severity associated with primary infection with the human immunodeficiency virus (HIV). We report here studies on six individuals who showed an acute HIV syndrome which generally resolved within four weeks, concomitant with a dramatic downregulation of viraemia. To characterize the T-cell-mediated primary immune response to HIV, we used combined semiquantitative polymerase chain reaction assay and cytofluorometry to analyse the T-cell antigen receptor repertoire in sequential peripheral blood mononuclear cells from the patients. We found major oligoclonal expansions in a restricted set of variable-domain beta-chain (V beta) families. Cells expressing the expanded V beta s predominantly expressed the CD8 T-cell differentiation antigen and mediated HIV-specific cytotoxicity. Major oligoclonal expansions of these CD8+ T lymphocytes may represent an important component of the primary immune response to viral infections and may help to clarify both the immunopathogenic and the protective mechanisms of HIV infection.

Adolescent↗
PubMed1994

HIV infection and leprosy: a four-year survey in Ethiopia.

Between 1988 and 1992 three cross-sectional surveys for antibodies to HIV were done in 644 Ethiopian patients with histologically proven leprosy. Whereas the frequency of HIV-1 infection gradually increased from 3.2% to 6.5%, the clinical presentation, number of new patients, and frequency of relapse did not differ between HIV negative and positive patients. Thus HIV appears unlikely to have a significant impact on the incidence of leprosy in sub-Sahelian populations.

Adult↗
PubMed1994

Primary sequence of the chitosanase from Streptomyces sp. strain N174 and comparison with other endoglycosidases.

A 1.6-kb DNA fragment from the soil actinomycete, Streptomyces sp. strain N174, containing the gene (csn) encoding an extracellular chitosanase (CSN), has been isolated and its complete nucleotide sequence determined. The gene was expressed in Escherichia coli and Streptomyces lividans using appropriate vectors. The sequence was found to contain one large ORF which encodes a protein of 238 amino acids (aa). The deduced aa sequence begins with a signal peptide which has an unusual C-terminal segment, well recognized by the Streptomyces secretion system, but poorly in Escherichia coli. The strain N174 CSN aa sequence was compared with those of other proteins and significant homology was found only with the Bacillus circulans MH-K1 CSN but not with known chitinases or lysozymes. This suggests that CSN form a new enzyme family distinct from other endoglycosidases.

Amino Acid Sequence↗
PubMed1994

Binding sites for bacterial and endogenous retroviral superantigens can be dissociated on major histocompatibility complex class II molecules.

Bacterial and retroviral superantigens (SAGs) interact with major histocompatibility complex (MHC) class II molecules and stimulate T cells upon binding to the V beta portion of the T cell receptor. Whereas both types of molecules exert similar effects on T cells, they have very different primary structures. Amino acids critical for the binding of bacterial toxins to class II molecules have been identified but little is known of the molecular interactions between class II and retroviral SAGs. To determine whether both types of superantigens interact with the same regions of MHC class II molecules, we have generated mutant HLA-DR molecules which have lost the capacity to bind three bacterial toxins (Staphylococcus aureus enterotoxin A [SEA], S. aureus enterotoxin B [SEB], and toxic shock syndrome toxin 1 [TSST-1]). Cells expressing these mutated class II molecules efficiently presented two retroviral SAGs (Mtv-9 and Mtv-7) to T cells while they were unable to present the bacterial SAGs. These results demonstrate that the binding sites for both types of SAGs can be dissociated.

Animals↗
PubMed1994

Prevalence of antibodies to hepatitis C virus among patients with leprosy in several African countries and the Yemen.

The prevalence of anti-HCV was determined in 1,309 leprosy patients and a control group of 1,469 subjects from 6 sub-Saharan African countries and the Yemen. Sera found positive by an initial second generation ELISA were subjected to 3 additional confirmatory tests. The anti-HCV prevalence in leprosy patients (7.1%) was significantly higher than in the control group (2.6%). HCV seroprevalence increased with age in both the control and leprosy groups. No statistically significant difference could be found between anti-HCV prevalence and the several clinical forms of leprosy among patients. The results of this study indicate a high degree of exposure or chronic carriage of hepatitis C among leprosy patients.

Adult↗
PubMed1994

Multicenter evaluation of a fully automated screening test, VIDAS HIV 1 + 2, for antibodies to human immunodeficiency virus types 1 and 2.

A multicenter study was done to evaluate the sensitivity, specificity, and efficiency of a new screening test for the simultaneous detection of human immunodeficiency virus type 1 and 2 (HIV-1 and HIV-2) antibodies. The VIDAS HIV 1 + 2 (bioMérieux, Marcy l'Etoile, France) is a fully automated enzyme-linked fluorescent immunoassay that uses synthetic peptides from immunodominant regions of gp41 of HIV-1 and gp36 of HIV-2 as antigens. A total of 2,984 samples were evaluated with this system in six different laboratories, and the results were compared to those obtained with other enzyme-linked immunosorbent assays. The VIDAS HIV 1 + 2 assay showed a very good performance in terms of sensitivity (100%) and specificity (99.6%), requiring minimal manipulation and short incubation time (32 min) to give results similar to or better than those of the other enzyme-linked immunosorbent assays used for screening.

Enzyme-Linked Immunosorbent Assay↗
PubMed1994

Hyperextension injuries of the thoracic spine in diffuse idiopathic skeletal hyperostosis. Report of four cases.

Four patients who had multisegmental ankylosis of the thoracic and lumbar spine due to diffuse idiopathic skeletal hyperostosis sustained a hyperextension fracture-dislocation. The patients had a mean age of sixty-four years (range, fifty-eight to sixty-nine years); all four patients were men. All injuries occurred between the seventh and eleventh thoracic vertebrae. All patients had intact neurological function at the time of admission to the hospital. Three patients were managed with posterior spinal arthrodesis with Cotrel-Dubousset segmental instrumentation; one patient was managed non-operatively with a molded thoracolumbosacral orthosis. At a minimum duration of follow-up of twenty-two months (mean, twenty-seven months), the three patients who had been managed operatively had healing of the fracture with anatomical alignment of the spine and without postoperative complications. The one patient who had been managed non-operatively with a brace had severe neurological deterioration and non-anatomical alignment of the spine.

Aged↗
PubMed1994

Pathophysiology of spinal deformities in neurofibromatosis. An analysis of seventy-one patients who had curves associated with dystrophic changes.

The findings in seventy-one patients who had previously untreated spinal deformities associated with dystrophic changes and who had neurofibromatosis were reviewed to identify the risk factors for progression of the curve as well as the natural history of the dystrophic changes and curve patterns. Four different types of curves were evaluated. Two of them had the most severe progression: (1) kyphoscoliosis with angular kyphosis (gibbus) and marked dystrophic changes and (2) so-called kyphosing scoliosis (a scoliosis that has so much rotation [90 degrees] that progression is evident only on the lateral roentgenogram) with a round kyphosis. Risk factors for substantial progression of the curve were an early age of onset, a high Cobb angle at the first examination, an abnormal kyphosis, vertebral scalloping, severe rotation at the apex of the curve, location of the apex of the curve in the middle to caudal thoracic area, penciling of one rib or more on the concave side or on both sides of the curve, and penciling of four ribs or more.

Adult↗
PubMed1994

Deep venous thrombosis and pulmonary embolism after major reconstructive operations on the spine. A prospective analysis of three hundred and seventeen patients.

We performed a prospective study of 317 patients in order to determine the prevalence of deep venous thrombosis after reconstructive operations on the spine; 126 of the patients were examined with duplex ultrasound assessments of the lower extremities to ensure that no asymptomatic thrombi were being missed. Thigh-high stockings and sequential pneumatic compression of the lower extremities were used, in all patients, for prophylaxis against venous thrombosis. No antiplatelet agents or anticoagulant medications were administered. There was no evidence of thrombosis on any of the duplex ultrasound studies. Subsequently, venous thrombosis developed and was treated successfully in one of the 126 tested patients and in one of the 191 untested patients, and a fatal pulmonary embolus developed in one of the untested patients. The over-all clinical prevalence of thrombotic complications was 0.9 per cent (three complications in 317 patients). All three of the patients who had clinical evidence of thrombosis had had an anterior lumbar procedure because of a degenerative disorder or trauma; however, we could not prove that this approach or these diagnoses were significant risk factors for thrombosis (p < 0.05). While it is possible that some thrombi may have escaped both clinical and ultrasonic detection, such thrombi apparently were not enough of a danger to warrant the use of intensive prophylactic procedures that are associated with more risk. On the basis of this prospective study, therefore, we think that routine screening for the detection of asymptomatic thrombosis in patients who have had a procedure on the spine is unwarranted.

Adolescent↗
PubMed1994

[Antibacterial activity of clarithromycin and its hydroxylated derivative and two other macrolides against thirty strains of Streptococcus pneumoniae].

Macrolides are widely used in the treatment of respiratory infections. Here, the authors compared the activity of different 14-membered macrolides: erythromycin (Ery), roxithromycin (Rox), clarithromycin (Cla) and its 14-hydroxy metabolite 14-OH clarithromycin (14-OH) against 30 strains of Streptococcus pneumoniae isolated at the Dupuytren hospital (Limoges, France) from upper respiratory tract sputum, ophthalmic sputum, blood samples and CSF. Twenty strains were susceptible to macrolides and 10 were resistant. Three strains from the susceptible and 7 from the resistant were resistant to penicillin. Furthermore, for all the macrolides except Rox and 14-OH, susceptibility tests were performed by the disk diffusion method on Mueller-Hinton agar. MICs50 of Cla and Ery were 0.06 mg/l. They were two-fold increased for 14-OH (0.125 mg/l) and four-fold increased for Rox (0.25 mg/l). We noted that for 3 resistant strains, MICs of Cla were four-fold decreased than MICs of Ery. Ery, Cla and 14-OH had bactericidal activity against pneumococcus strains susceptible to these antibiotics at 4 and 8 times the MIC after 6 or 18 h. The difference between MIC and MBC was small (1 or 2 two-fold dilutions) for Ery, Rox and Cla. For 14-OH, this difference was within 2 to 4 two-fold dilutions. The bactericidal activity is similar to that of amoxicillin and cefotaxim. A microdilution chequeboard technique was used against 3 strains and the FIC index did not show synergistic effect of combining Cla and 14-OH. The activity of Cla and 14-OH against 5 strains was not modified in the presence of 50% fresh pooled human serum inactivated at 56 degrees C or not.

Anti-Bacterial Agents↗
PubMed1994

[Concentration of amoxicillin in neonates after infusion to the mother during labor].

Amoxicillin is effective against S. agalactiae (MIC 50 = 0.03 mg/l). Neonatal prophylaxis of GBS infection had already been studied but very few data are available regarding pharmacokinetic of these antibiotics. In this study, 58 pregnant women with GBS colonisation and/or with epidemiologic risk factors received intrapartum antibiotic infusion at the beginning of the labor (1 g amoxicillin every 6 hours until the delivery). At delivery, cord blood and gastric fluid were taken in delay from 0.5 to 6 hours after the beginning of the infusion. Dosages were done in triplicate with a microbiological method using Bacillus subtilis ATCC 6633 as test strain. In cord blood amoxicillin appeared as early as the first half hour. Concentration were from 5 to 7 mg/l between 1 hour and 4 hours after the beginning of the infusion, and from 3 to 4 mg/l after 4 hours. In gastric fluid, concentrations obtained were over 1 mg/l after 1.5 hour and over 3 mg/l after 2.5 hours with good efficiency even after the sixth hour. The protocol using a slow intrapartum amoxicillin infusion (1 g) gave concentrations in gastric fluid and cord blood over S. agalactiae MIC.

Adult↗
PubMed1994

[Prevalence of HBs Ag in about 21,500 pregnant women. Survey at twelve French University Hospitals. The Muticentric Study Group].

The risk of perinatal B virus transmission is estimated in France on results of limited studies carried out during a long period and essentially in metropolitan area. Systematic screening for HBsAg in pregnancy was decided in February 1992 in France. In order to obtain national data on HBsAg prevalence of pregnant women, the authors have summarized the results obtained from twelve French university hospitals during one year. Among the 21,476 pregnant women studied (French: 16,351 and immigrant: 5,125), the total HBsAg prevalence was 0.72% and was significantly higher in the immigrant women group (2.56%) when compared to that of French women (0.15%). The HBsAg prevalence increased from Mediterranean area (1.75%) to SubSaharan Africa (4.61%) and South East Asia (5.45%). Important variations were observed between the centers (from 0.13 to 2.99%). Among the HBsAg carriers, 16.5% were HBeAg and/or HBV-DNA positive in their serum. The only means to prevent each year in France around 850 chronic HBV infections by vaccination of the neonates consist in systematic HBsAg screening.

Africa South of the Sahara↗
PubMed1994

[Transmission of hepatitis C virus from mother to infant].

The transmission of hepatitis C virus (VHC) by percutaneous exposure to blood contamination is well documented but account for only 50 to 60% of hepatitis C cases. The transmission route for sporadic cases remains controversial and transmission by sexual contact and vertical transmission have been implicated. Antibodies to HCV are detected in 0 to 4.3% of pregnant women varying across geographic regions or origins. Passively transmitted maternal anti-HCV are detected in most of the new-born babies and persist during 6 to 18 months. The estimated risk of vertical transmission varies widely in the literature probably because of methodological considerations. But the detection of HCV-RNA in the blood of children has confirmed vertical transmission of HCV from mother to infant in mothers coinfected or not with human immunodeficiency virus type 1. In case of vertical transmission, some children develop an acute hepatitis or a chronic carrier state with or without chronic liver disease. In this case, the course of HCV RNA and transaminases might reflect the fluctuating viral replication. Some other children, infected at birth, seem to clear the HCV virus. The babies' HCV-antibodies are detected in some infected children but not in all. The follow up of HCV-seropositive pregnant women and their offsprings with more reliable methods should clarify the clinical importance, the rate of transmission and the factors which influence it.

Female↗
PubMed1994

Scoliosis secondary to rib resection.

The case histories of 11 patients (five adults and six children) who presented with scoliosis after multiple rib resection for several disorders were reviewed. All 11 cases developed scoliosis with the convexity directed toward the side of the rib resection. The natural history of the scoliosis was progressive, and the younger the age at the time of rib resection, the more severe the progression. The rate of progression was greatest during the first 10 years after rib resection. The five patients who presented as adults were treated in several ways, only one requiring spine fusion. However, five of the six children required spine fusion to prevent progression of scoliosis.

Adolescent↗