Biomedical subjects
D Lacoste
Publications and source records attributed to D Lacoste.
A possible association between Chlamydiae psittacci infection and temporal arteritis.
Some arguments are in favor of the role of Chlamydia in the pathogenesis of atherosclerosis and some vasculitis. Illustrating this possible relation, we report the case of a patient developing consecutively a Chlamydia psittacci infection and a temporal arteritis. A 73-year-old woman, with no significant medical history, was hospitalized for constitutional symptoms. Three weeks before, she had described fever and sore throat of two days' duration. Since that time, she had remained exhausted and developed a mild intermittent claudication of the jaws. Clinical examination was poor. A biological inflammatory syndrome was noticed. Chest X-ray revealed bilateral interstitial opacities. The titer of anti-C. psittaci antibodies was significant (positive 1g G at 1/2048). Soon after initiation of doxycycline, a temporal arteritis biopsy was performed, due to the persistence of clinical symptoms and high inflammatory syndrome, conclusive for the diagnosis of temporal arteritis. Corticotherapy was added to antibiotic therapy, resulting in the decrease of inflammatory syndrome and an improvement in the general status of the patient. X-ray opacities decreased in three weeks. Serological control after three months showed a decrease of the titer of anti-C. psittacci antibodies to 1/256, confirming the initial diagnosis of Chlamydia pneumopathy. Our observation could provide one more argument for the role of bacteria-like Chlamydia in the pathogenesis of vascular diseases. Prospective seroepidemiological and molecular biology studies could allow us to clarify the association between Chlamydia infections and inflammatory vasculitis-like temporal arteritis.
Coherent backscattering of light in a magnetic field
This paper describes how coherent backscattering is altered by an external magnetic field. In the theory presented, magneto-optical effects occur inside Mie scatterers embedded in a nonmagnetic medium. Unlike previous theories based on pointlike scatterers, the decrease of coherent backscattering is obtained in a leading order of the magnetic field using rigorous Mie theory. This decrease is strongly enhanced in the proximity of resonances, which cause the path length of the wave inside a scatterer to be increased. Also presented is an analysis of the shape of the backscattering cone in a magnetic field.
Photonic hall effect in ferrofluids: theory and experiments
An experimental and theoretical study on the photonic Hall effect (PHE) in liquid and gelled samples of ferrofluids is presented. The ferrofluids are aqueous colloidal suspensions of Fe2CoO4 particles, which can be considered as anisotropic and absorbing Rayleigh scatterers. The PHE is found to be produced by the orientation of the magnetic moments of the particles, as is also the case for the Faraday effect. The dependence of the PHE with respect to the concentration of the scatterers, the magnetic field, and the polarization of the incident light is measured in liquid and in gelled samples, and is compared to a simple model based on the use of a scattering matrix and the single scattering approximation.
Photonic hall effect in absorbing media
We describe an experimental and theoretical study of the effect of optical absorption on the photonic Hall effect in a passive matrix containing magnetoactive scatterers. We find that for the case of absorbing scatterers, the magnetotransverse light current changes sign and increases with increasing absorption. Good agreement is obtained with numerical calculations. For the case of an absorbing matrix, no effect was observed.
Prevalence and underestimation of pain in HIV-infected patients by physicians: a cross-sectional study in a day care hospital.
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Increase in CD3+ CD4- T lymphocytes in patients with AIDS and disseminated Mycobacterium avium-intracellulare complex infection: a prospective study. GECSA. Groupe d'Epidemiologie Clinique du SIDA en Aquitaine.
In a retrospective study, an increase in double-negative (CD3+ CD4- CD8-) (DN) T lymphocytes has been shown to be an independent predictor of disseminated Mycobacterium avium complex (D.MAC) infection in patients with less than 100 CD4+ T cells per mm3. To better characterize this cell expansion, a prospective study was designed. From July 1995 to April 1997, 206 HIV-infected patients with less than 100 CD4+ T cells per mm3 were prospectively followed up and immunophenotyped. The median followup was 1.1 year (+/-0.5 year), and 14 new D.MAC infections were diagnosed among 84 first AIDS-defining events. In univariate and multivariate analyses, D.MAC infections were the only opportunistic infection with a significant increase in DN T-cell percentage (median = 6.6; range = 1.7 to 24.5, P = 0.004) compared with patients without any opportunistic infection. This alteration in T-lymphocyte count could constitute a predictor for D.MAC infection in clinical practice.
Changes in CD4+ cell count and the risk of opportunistic infection or death after highly active antiretroviral treatment. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine.
OBJECTIVE: To study the relationship between the CD4+ cell response after initiation of protease inhibitors and the occurrence of opportunistic infections and survival. DESIGN: Prospective observational cohort study. METHODS: HIV-1-seropositive subjects followed-up in HIV centres of Bordeaux University Hospital, Southwest France who were prescribed at least one available protease inhibitor between January and December 1996 were included in this analysis. A Cox model estimated the independent effect of baseline covariates and CD4+ cell response, considered as a time-dependent covariate, on the occurrence of new AIDS-defining opportunistic infection, new AIDS-defining events, new AIDS-defining opportunistic infection or death. RESULTS: A total of 556 HIV-positive patients were prescribed at least one protease inhibitor: 34% saquinavir, 52% indinavir, and 14% ritonavir. Median CD4+ cell count at baseline was 95 x 10(6)/l and mean plasma HIV RNA was 5.0 log10 copies/ml. After a median follow-up of 230 days, 65 patients experienced a new episode of opportunistic infection, 79 patients experienced at least one AIDS-defining event, and 24 had died. On average, the increase in CD4+ cell count was 42 x 10(6)/l (SD, 74) after a median of 49 days. In the multivariate analysis of opportunistic infection or death, each 50% higher CD4+ cell count at baseline was associated with a 23% reduction [95% confidence interval (CI), 14-30] of risk. Each 50% increase in CD4+ cell count during follow-up was associated with a 9% reduction (95% CI, 2-15) of risk, adjusted for the presence of AIDS prior to protease inhibitor therapy (hazard ratio, 3.76 versus absence of AIDS; P < 0.01) and haemoglobin level (hazard ratio, 0.48 if > 11 g/dl versus <11 g/dl; P < 0.01). CONCLUSION: Our results show, at least indirectly, how protease inhibitors might produce clinical stabilization. This result may be due to improved functionality of CD4+ cells in patients started on protease inhibitors.
Rapid change in the use of antiretroviral agents and improvement in a population of HIV-infected patients: France, 1995-1997. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine (GECSA).
PURPOSE: To describe the recent evolution of antiretroviral prescriptions and to look for clinical and biological changes among a population of HIV-infected patients. SUBJECTS: Patients received follow-up in the hospital-based information system of the Groupe d'Epidémiologie Clinique du SIDA en Aquitaine (GECSA), Southwestern France, from 1995 to 1997. METHODS: Quarterly evolution of the prescriptions of antiretroviral treatments and of the population clinical and biological indicators were studied in this observational survey of computerized records obtained after each hospital contact. RESULTS: Overall numbers of patients who received follow-up and of hospital contacts remained stable. The proportion of untreated patients decreased from 38.5% to 10.5%. Monotherapies were progressively abandoned. Double combination therapies with two nucleoside analogues were used for 55% of the patients by early 1996 and then decreased, whereas triple combination therapies with one protease inhibitor (PI) rapidly increased to comprise up to 40% of the prescriptions in 1997. PIs were prescribed earlier and earlier in the course of HIV infection. Overall incidence of AIDS diagnoses and mortality rate decreased by 18% and 22%, respectively, in the first 9 months of use of PIs compared with the preceding 9 months, and by 47% and 56%, respectively, in the following 9 months (p<.001). The number of hospitalizations and the proportion of patients with a CD4 cell count <200/mm3 decreased. AIDS cases diagnosed after introduction of PIs had rarely been treated with PIs. CONCLUSION: Over this 3-year period, physicians prescribed antiretroviral treatments more and more frequently, and triple combination therapy with PI is now common practice in France. Patients clinical and biological patterns have improved 18 months after the introduction of PIs.
CD4+ lymphocyte count and plasma HIV RNA levels in a survey of 1602 HIV-infected patients in Bordeaux, France, 1996-1997. Groupe d'Epidemiologie Clinique da SIDA en Aquitaine.
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Cancer incidence in a cohort of human immunodeficiency virus seroconverters.
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Evolution of case management of patients with HIV infection in France, 1995-1996. Groupe d'Epidemiologie Clinique du SIDA en Aquitaine (GECSA)
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[Prevalence of clinical manifestations of allergic reactions in HIV infection. Cross sectional study of 115 subjects].
A cross sectional survey was set up to study the relation between the prevalence of allergic-type reactions during HIV infection course. For each patient, a standardized interview about recent allergic-type manifestations (RATM), skin prick-tests to six common airborne allergens, IgE serum level were done. Among the 115 included patients, the mean CD4 lymphocyte count (CD4) was 214.7/mm3 (range: 0-1328/mm3). RATM were found in 8.8% of patients with CD4 < 50, in 30% of patients with CD4 between 51 and 200, in 36% of patients with CD4 between 201 and 350 and in 11.5% of patients with CD4 < 350 (p = 0.03). The risk of presenting RATM was 4.8 times (95% confidence interval = 1.7-13.5) higher in patients with CD4 between 51 and 350 than in other patients (p = 0.003). The proportion of positive prick-tests did not significantly vary according to the level of CD4. The increased frequency of RATM in patients with CD4 between 51 and 350/mm3 could be due to an allergic predisposition acquired during the course of HIV infection. The mechanisms explaining the reduced frequency of allergic manifestations when immunodeficiency is profound (CD4 < 50/mm3) remain to be explained.
[Rectal lymphomas and human immunodeficiency virus].
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[Progressive multifocal leukoencephalopathy. Study of the demyelination by magnetization transfer].
PURPOSE: magnetization transfer imaging (MT) has been used to study the degree of demyelination in progressive multifocal leukoencephalopathy (PML). MATERIAL AND METHOD: two groups were studied: a group of 10 HIV + patients with clinical, MR features, biological and/or biopsy proven PML, and a group of 11 normal volunteers with matched age. MT ratio (MTR) were obtained from the center of the PML lesions and 11 areas of normal appearing white matter (NAWM) in the control group. RESULTS: the mean MTR of NAWM in the control group was 46.6% (SD = 2,3). PML lesions demonstrated a strong and significant (p = 0) decreased of the MTR with mean MTR value of 22.4% (SD = 2,3). CONCLUSION: MT characterized the demyelinating process in PML, and can be used to improve diagnosis. Furthermore, MT allowed a quantification of the degree of demyelination which can be helpful in other demyelinating process of CNS such as multiple sclerosis.
[Appearance of antiphospholipid antibodies in patients with hepatitis C treated with interferon-alpha].
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Magnetization transfer study of HIV encephalitis and progressive multifocal leukoencephalopathy. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine.
PURPOSE: To ascertain whether the use of magnetization transfer (MT) in MR imaging can characterize tissue destruction in human immunodeficiency virus (HIV)-positive patients with presumed progressive multifocal leukoencephalopathy (PML) or HIV encephalitis. METHODS: Brain MR studies that included MT were obtained in three groups: 11 healthy control subjects, 10 HIV-positive patients with clinical and radiologic findings of PML, and 13 HIV-positive patients with HIV encephalitis. MT ratios (MTRs) were calculated in PML and HIV encephalitis lesions and in normal-appearing white matter in the patients and control subjects. RESULTS: PML lesions revealed a dramatic decrease in MTR (22% +/- 2.3). HIV encephalitis lesions had statistically significantly higher MTR values (40% +/- 3.8) than PML lesions. The MTR of normal-appearing white matter was significantly higher in the control subjects (47% +/- 2.3) than in the PML group (46% +/- 3.3) or the HIV encephalitis group (44% +/- 2.6). CONCLUSION: MTR determinations suggest the possibility of distinguishing PML from HIV encephalitis and of indicating whether HIV encephalitis is involved in white matter that appears normal on conventional MR images.
[Isolated involvement of the trigeminal nerve of sarcoidosis origin].
Sarcoidosic neurological manifestations are uncommon. Isolated cranial nerve's injury is exceptional. The authors report the case of a 29 year-old woman with a trigeminal nerve tumor. Surgery and anatomopathology led to the diagnosis of sarcoidosic infiltration. No other neurological or extra-neurological localization was found. Cranial fifth nerve injury was observed in 14 cases of the literature. In all cases, trigeminal nerve injury was described as associated with another disease's localization (neurological and/or extra-neurological). This observation seems unusual due to isolated nature of the presentation and complete resolution after surgery. This case illustrated the diagnosis and nosologic difficulties raised by granulomatous lesions, symptomatic or not, in the absence of systemic localization.