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Biomedical subjects

F Simon

Publications and source records attributed to F Simon.

At least 73 records · Page 4Linked to original sources
PubMed2001

Ex-vivo hemoperfusion (eHPS) of pig-lungs with whole human blood: effects of complement inhibition with a soluble C1-esterase-inhibitor.

OBJECTIVES: Xenotransplantation could be a future alternative to allotransplantation due to increasing organ shortage. Complement activation plays a major role in hyperacute rejection (HAR) in pig-to-human combinations. We developed an ex-vivo hemoperfusion (EHP) system to investigate pathophysiology of HAR in the lung. After standardizing the model, the effect of a soluble complement inhibitor (C1-INH, Berinert) was investigated. METHODS: Pig lungs were harvested following cold perfusion with Celsior preservation solution. EHP was performed using fresh heparinized human blood plus C1-INH (n = 6) or heparinized human blood as control (n = 4). Bloodgas analyses (BGA), pulmonalarterial pressure (PAP) were monitored. P-selectin and L-selectin were measured. Tissue samples were taken and microscopic changes evaluated. RESULTS: BGA, PAP, macroscopic and microscopic changes in the control group showed HAR, while the C1-INH group showed significantly longer function. Leucocytes and platelets were markedly activated in the control, whereas in the treated group L-selectin and P-selectin values indicated lower activation. HE stainings showed maintained lung architecture after perfusion of pig-lungs with human blood plus C1-INH. Immunohistochemistry showed less C1q, C3, C5b-9 activation in the C1-INH group. CONCLUSIONS: Investigation of interaction of human blood with pig lung endothelium could be done in this model. C1-INH attenuates HAR in a pig-to-human lung transplantation model by decreasing the activation of adhesion molecules. C1-INH could play a role in induction therapy of future lung xenotransplantation.

Animals↗
PubMed2001

[Thoracic nocardiasis associated with macrophage activation syndrome].

Nocardiasis is an uncommon bacterial disease often observed in immunodepressed patients. Its interactions with the immune system remain poorly known. We report a case of Nocardia asteroides thoracic nocaridiasis in an African subject who also had macrophage activation syndrome. We recall the classic data on nocardiasis in Africa and emphasize the importance of emergence in HIV-infected subjects. The association between nocardiasis and macrophage activation syndrome suggest a possible pathogenic mechanism involving the immune system (lymphocytes and macrophages) and Nocardia asteroides.

AIDS-Related Opportunistic Infections↗
PubMed2000

Magnetic-field-induced low-energy spin excitations in YBa(2)Cu(4)O(8) measured by high field Gd(3+) electron spin resonance.

We have measured the spin susceptibility, chi(s), of the CuO(2) planes in the underdoped high T(c) superconductor, YBa(2)Cu(4)O(8) by Gd(3+) electron spin resonance (ESR) in single crystals and aligned powders in fields up to 15.4 T. At low temperatures and high fields, chi(s) is enhanced slightly in the B parallel c orientation with respect to the B perpendicular c orientation. The enhancement at 15.4 T (approximately equal to 0.15H(c2)) at 16 K (0.2 T(c)) is small: approximately 10% of chi(s)(T(c)), suggesting that the second critical field of superconductivity, H(c2) approximately equal to 100 T, would not suppress the pseudogap. This work demonstrates the potential of high field ESR in single crystals for studying high T(c) superconductors.

Journal Article↗
PubMed2000

Detection of diverse variants of human immunodeficiency virus-1 groups M, N, and O and simian immunodeficiency viruses from chimpanzees by using generic pol and env primer pairs.

Human immunodeficiency virus type 1 (HIV-1) infection of humans is the result of independent cross-species transmissions of simian immunodeficiency viruses (SIVcpz) from naturally infected chimpanzees (Pan troglodytes troglodytes) to man. To develop a polymerase chain reaction-based assay capable of detecting members of all major phylogenetic SIVcpz and HIV-1 lineages (groups M, N, and O), primer pairs in conserved pol and env regions were designed. Both primer sets amplified </=10 copies of selected group M reference clones (subtypes A-H), proviral DNA or RNA of group N (YBF30), and group O of HIV-1 and also amplified divergent SIVcpz from cultured isolates (SIVcpzGAB1 and SIVcpzANT), uncultured spleen tissue (SIVcpzUS), and plasma (SIVcpzANT and SIVcpzUS). Sequences of the 2 amplicons (445 bp for gp41 and 261 bp for integrase) are of sufficient length for phylogenetic analyses, allowing both group and subtype classifications of the human viruses. Finally, both primer pairs are highly sensitive (>99%) in amplifying viral sequences from plasma taken from patients infected with HIV-1 group M (n=226) and O (n=17) viruses.

Animals↗
PubMed2000

HIV-1 diversity in France, 1996-1998. The AC 11 laboratory network.

OBJECTIVE: To study the distribution of HIV-1 subtypes in France and to describe the characteristics of patients infected with non-B subtypes. METHODS: All adults who tested HIV-1 positive on Western blot for the first time in one of the participating laboratories between September 1996 and March 1998 were eligible, whether or not they had been diagnosed previously elsewhere. Data on age, sex, country of birth, HIV-transmission group, dates of the last negative and first positive HIV test and clinical stage were collected. Serotyping was performed with a peptide subtype-specific enzyme immunoassay on each plasma sample and genotyping with heteroduplex mobility assay on each non-B serotype-infected patient. Patients characteristics were compared in B and non-B subtypes. RESULTS: Of the 2168 HIV-positive patients included by 32 laboratories, subtype,results were available for 2042. Among those, 73.4% were men, 12.2% born in sub-Saharan Africa, 41.5% infected through heterosexual contact and 67.6% in CDC stage A. Among the 2042 patients, 1 725 (84.5%) were infected with B subtype. Among the 317 non-B subtypes, subtype A was predominant (66.9%); all other subtypes (C, D, E, F, G, H, O) were present. Factors independently associated with a non-B subtype were to be included in the Paris area [adjusted odds ratio (aOR), 1.6; 95% confidence interval (CI), 1.1-2.3], to be born in sub-Saharan Africa (aOR, 26.0; 95% CI, 17.5-37.8) and to be infected through heterosexual contact (aOR, 4.2; 95% CI, 2.8-6.4). CONCLUSIONS: In France, although B subtype is still predominant, all non-B subtypes are now present. The diversity of HIV strains may affect diagnostic tests and clinical practice, especially viral load measurements. Moreover, the decreased susceptibility of non-B subtypes to antiretroviral drugs emphasizes the importance of surveillance of HIV diversity.

Adult↗
PubMed2000

Shortening of the diagnostic window with a new combined HIV p24 antigen and anti-HIV-1/2/O screening test.

Because antibodies to the human immunodeficiency virus (HIV) are absent in the very early phase of HIV infection, there remains a slight residual risk for HIV transmission by blood donations by viremic but antibody negative donations. To shorten the diagnostic window between infection and the detection of antibodies, Enzygnost HIV Integral (Dade Behring, Germany) was developed. With this new test, HIV p24 antigen and HIV antibodies can be detected simultaneously in a single test. In a multicenter study the new screening assay has been compared with various tests that detect only HIV antibodies or HIV p24 antigen and with assays which permit a simultaneous detection of HIV antigen and HIV antibodies. The new assay showed 100% sensitivity for the detection of antibodies to HIV-1, groups M (n=1102) and O (n=55), and HIV-2 (n=289). In 23 out of 52 seroconversion panels, seroconversion was detected 2-18 days earlier with the new combined antigen/antibody test compared to single antibody tests. All samples from a viral load panel (n=451), all samples containing p24 antigen (n=302), and all but one of the cell culture supernatants (n=38) infected with various HIV-1 subtypes or HIV-2 were identified reliably by the new test. The specificity of the assay for 4002 unselected blood donors was 99.78% initially and 99.80% after retesting. Potentially interfering factors had no systematic influence on specificity. By testing for p24 antigen, which is present prior to the onset of antibody production in some cases of recent HIV infection, the new assay reduces the diagnostic window as compared to third generation screening assays, thus permitting an earlier diagnosis of HIV infection.

AIDS Serodiagnosis↗
PubMed2000

Characterization and developmental expression of xSim, a Xenopus bHLH/PAS gene related to the Drosophila neurogenic master gene single-minded.

We have isolated a novel gene from Xenopus, denominated xSim, which encodes a protein of 760 amino acids containing a basic helix-loop-helix (bHLH) motif contiguous to a PAS domain characteristic of an emerging family of transcriptional regulators so called bHLH/PAS. xSim shares a strong amino acid sequence identity with the Drosophila Single-minded (dSim) and with the murine Sim1 and Sim2 proteins. Phylogenetic analysis reveals that xSim gene is an ortholog gene of the mSim2 gene. Spatio-temporal analysis shows a maternal and a zygotic expression of xSim throughout early Xenopus development. In situ hybridization assays reveal that the transcripts are enriched in the animal hemisphere until blastula stage and extend to the marginal zone at early gastrula stage. As development proceeds, xSim is mainly restricted to the central nervous system.

Amino Acid Sequence↗
PubMed2000

SIVcpz from a naturally infected Cameroonian chimpanzee: biological and genetic comparison with HIV-1 N.

Thus far, simian immunodeficiency virus from chimpanzees (SIVcpz) genomes have been characterized as Pan troglodytes troglodytes and show a strong relation with human immunodeficiency virus (HIV)-1 N in their env genes. We fully characterized another SIVcpz from P. t. troglodytes. This chimpanzee (Cam5) was, as was also the host of SIVcpz-cam3, wild born in Cameroon, a region where all three groups of HIV-1 (M, N and O) co-occur. In contrast to other SIVcpz, SIVcpz-cam5 was isolated immediately after the rescue of the animal. Our data demonstrate that SIVcpz-cam5, like SIVcpz-cam3, grows easily on human peripheral blood mononuclear cells (PBMCs) and uses CCR5 as a co-receptor similar to HIV-1 N YBF30. Phylogenetic analysis based on the entire env gene shows that SIVcpz-cam5 falls into the same unique subcluster as HIV-1 N YBF30, SIVcpz-cam3 and SIVcpz-US. A phylogenetic relationship was also found with the vif gene of HIV-1 N. This study provides proof that HIV-1 N related viruses circulate in wild P. t. troglodytes.

Amino Acid Sequence↗
PubMed2000

[Follow-up of patients suffering from age-related macular degeneration, supplied with visual aids].

BACKGROUND: Age-related macular degeneration (AMD) is at present the major cause of legal blindness in industrialized countries. The results of various treatments are often not satisfactory and follow-up by Low-Vision services is then the only solution for this population. Few studies have been published on this subject. The purpose of this study is to present the use of magnifying systems and the degree of satisfaction obtained for this series of patients 6 months after prescription. PATIENTS AND METHODS: Forty-four patients were examined, 42 of whom were eligible for the study. Lenses, magnifying glasses, visual systems for intermediate distance, and electronic systems were proposed. A low-vision training was given to every patient. RESULTS: The highest degree of use and satisfaction was achieved with the electronic systems. In some cases, however, the other systems were well accepted by the patients. CONCLUSION: The follow-up of patients with age-related macular degeneration is of great social importance. The independence of elderly people can be safeguarded thanks to the help of Low-Vision services with a good equipment and a well-trained team. Sometimes, unsophisticated systems such as magnifying glasses can be proposed, but the best results are mostly obtained through electronic systems (TV).

Aged↗
PubMed2000

env sequences of simian immunodeficiency viruses from chimpanzees in Cameroon are strongly related to those of human immunodeficiency virus group N from the same geographic area.

Human immunodeficiency virus type 1 (HIV-1) group N from Cameroon is phylogenetically close, in env, to the simian immunodeficiency virus (SIV) cpz-gab from Gabon and SIVcpz-US of unknown geographic origin. We screened 29 wild-born Cameroonian chimpanzees and found that three (Cam3, Cam4, and Cam5) were positive for HIV-1 by Western blotting. Mitochondrial DNA sequence analysis demonstrated that Cam3 and Cam5 belonged to Pan troglodytes troglodytes and that Cam4 belonged to P. t. vellerosus. Genetic analyses of the viruses together with serological data demonstrated that at least one of the two P. t. troglodytes chimpanzees (Cam5) was infected in the wild, and revealed a horizontal transmission between Cam3 and Cam4. These data confirm that P. t. troglodytes is a natural host for HIV-1-related viruses. Furthermore, they show that SIVcpz can be transmitted in captivity, from one chimpanzee subspecies to another. All three SIVcpz-cam viruses clustered with HIV-1 N in env. The full Cam3 SIVcpz genome sequence showed a very close phylogenetic relationship with SIVcpz-US, a virus identified in a P. t. troglodytes chimpanzee captured nearly 40 years earlier. Like SIVcpz-US, SIVcpz-cam3 was closely related to HIV-1 N in env, but not in pol, supporting the hypothesis that HIV-1 N results from a recombination event. SIVcpz from chimpanzees born in the wild in Cameroon are thus strongly related in env to HIV-1 N from Cameroon, demonstrating the geographic coincidence of these human and simian viruses and providing a further strong argument in favor of the origin of HIV-1 being in chimpanzees.

Animals↗
PubMed2000

Osteoporotic fractures at presentation of Cushing's disease: two case reports and a literature review.

Osteoporosis is a common complication of Cushing's disease/syndrome. Fractures can be the presenting manifestation. We report two cases and review 28 others from the literature. Clinical, laboratory, and absorptiometry data are reviewed; the vertebrae and ribs were the most common fracture sites, and osteoporosis reversal after treatment varied with age, gender, and symptom duration. The pathophysiology, which remains controversial, is discussed. A search for Cushing's disease/syndrome should be part of the routine evaluation of osteoporosis in children and adults, particularly men.

Absorptiometry, Photon↗
PubMed2000

[Phenicols].

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Anti-Bacterial Agents↗