Biomedical subjects
Publications and source records attributed to D Lévy.
Photokeratoscopy analysis of the anterior curve of the cornea can detect keratoconus, particularly in the early stages of the disease. Nevertheless, all irregular astigmatisms are not related to keratoconus. We report here several cases of patients presenting high asymmetric astigmatism with features of keratoconus, although the clinical examination suggests corneal disease related to rosacea.
The position of the lateral branch of the accessory nerve in relation to the internal jugular vein is given variously by different authors. In surgery of the neck, and especially in conservative cervical lymph node clearances, the lateral branch of the accessory nerve is protected when it is situated lateral to the vein. However, when the nerve is medial to the vein there is a risk of damage to the internal jugular vein. A prospective preoperative study of 123 cervical lymph node clearances, as well as a dissection study of 5 fresh subjects, was carried out to determine the position of the lateral branch of the accessory nerve in relation to the internal jugular vein. The surgical study showed that the lateral branch of the nerve was anterior and lateral to the vein in 122 of the 123 clearances, while the cadaveric study found the nerve always anterior and lateral to the vein. Thus the risk of injuring the internal jugular vein during cervical lymph node clearances is very small. The differences observed by authors may be explained by collapse of the internal jugular vein observed during cadaveric dissections.
Explore the source record for details and available documents.
A considerable interest exists currently in designing innovative strategies to produce two-dimensional crystals of membrane proteins that are amenable to structural analysis by electron crystallography. We have developed a protocol for crystallizing membrane protein that is derived from the classical lipid-layer two-dimensional crystallization at the air/water interface used so far for soluble proteins. Lipid derivatized with a Ni(2+)-chelating head group provided a general approach to crystallizing histidine-tagged transmembrane proteins. The processes of protein binding and two-dimensional crystallization were analyzed by electron microscopy, using two prototypic membrane proteins: FhuA, a high-affinity receptor from the outer membrane of Escherichia coli, and the F(0)F(1)-ATP synthase from thermophilic Bacillus PS3. Conditions were found to avoid solubilization of the lipid layer by the detergent present with the purified membrane proteins and thus to allow binding of micellar proteins to the functionalized lipid head groups. After detergent removal using polystyrene beads, membrane sheets of several hundreds of square micrometers were reconstituted at the interface. High protein density in these membrane sheets allowed further formation of planar two-dimensional crystals. We believe that this strategy represents a new promising alternative to conventional dialysis methods for membrane protein 2D crystallization, with the additional advantage of necessitating little purified protein.
After describing the results of BIV research during the past years experimental data are presented which indicate that BIV does not cause any clinical symptoms after infection and that no correlation exists with the other widely spread retrovirus in the bovine, the bovine leukosis virus (BLV). Since contact obviously did not lead to a horizontal transmission it is suggested that transmission occurs, as in the cat, vertically from dam to offspring. It was also found that a long period of time after infection can elapse before antibodies against BIV can be detected. It is also quite clear that HIV and BIV do not have much in common except that both are lentiviruses.
We report herein on the first serologic detection of antibodies to bovine immunodeficiency virus (BIV) in France. Serum samples from dairy and beef cattle from southwestern and western France (Landes and Vendée) were tested using a western blot assay with a recombinant 53 kDa gag precursor derived from the Louisiana BIV R29 isolate. We performed our study on the oldest animals from 37 different herds that were under serologic follow up for previous bovine leukemia virus infection. Overall, 398 selected bovine sera were assayed and 15 serum samples from 8 herds reacted with the recombinant 53 kDa BIV R29 gag. Interestingly, reactions obtained with French sera were weaker than with positive Louisiana sera, a finding that may indicate the occurrence of distinct French and Louisiana BIV variants.
Bovine immunodeficiency virus (BIV) is a lentivirus whose serologic prevalence is worldwide. Little is known about its impact on animal health status, pathogenesis and mode of transmission. Understanding BIV biology implies isolation of new viral strains and long-term studies on experimentally-infected cows and surrogate hosts such as rabbits.
Application of 1H 2D NMR methods to solubilized membrane proteins and peptides has up to now required the use of selectively deuterated detergents. The unavailability of any of the common biochemical detergents in deuterated form has therefore limited to some extent the scope of this approach. Here a 1H NMR method is described which allows structure determination of membrane peptides and small membrane proteins by 1H 2D NMR in any type of non-deuterated detergent. The approach is based on regioselective excitation of protein resonances with DANTE-Z or spin-pinging pulse trains. It is shown that regioselective excitation of the amide-aromatic region of solubilized membrane proteins and peptides leads to an almost complete suppression of the two orders of magnitude higher contribution of the protonated detergent to the 1H NMR spectrum. Consistently TOCSY, COSY and NOESY sequences incorporating such regioselective excitation in the F2 dimension yield protein 1H 2D NMR spectra of quality comparable to those obtained in deuterated detergents. Regioselective TOCSY and NOESY spectra display all through-bond and through-space correlations within amide-aromatic protons and between these protons and aliphatic and alpha-protons. Regioselective COSY spectra provide scalar coupling constants between amide and alpha-protons. Application of the method to the membrane-active peptide mastoparan X, solubilized in n-octylglucoside, yields complete sequence-specific assignments and extensive secondary structure-related spatial proximities and coupling constants.(ABSTRACT TRUNCATED AT 250 WORDS)
This study was designed to investigate the lymphoid tissue distribution of a new BoLA class II molecule defined by a unique monoclonal antibody H42A. We immunostained various lymphoid organs of 4-month-old Holstein calves with this monoclonal antibody and compared its tissue distribution to the BoLA-DR and BoLA-DQ expressions. Our results demonstrate a unique tissue distribution of the H42A-defined molecules, restricted to epithelial cells of the thymic medulla but extending in the periphery to the different cells involved in antigen presentation (B-cells, macrophages and dendritic cells). The peculiar distribution of this new BoLA class II molecule suggests that it has a specific function.
Studies were conducted to determine the reactivity of six monoclonal antibodies specific for major histocompatibility complex class II molecules expressed on a bovine B cell line homozygous for BoLA-DR and BoLA-DQ alleles. Direct immunoprecipitation, serial immunodepletion experiments, and two-dimensional gel electrophoresis revealed that these antibodies reacted with three different molecules. Bovine orthologues of HLA-DR were recognized by three monoclonal antibodies--H34A, TH12A, and TH14B. Orthologues of HLA-DQ were characterized by two other monoclonal antibodies, TH22A and TH81A. A third BoLA class II antigen, neither DR nor DQ was revealed by the last monoclonal antibody H42A. The relation of this molecule to known molecules in humans and other species remains to be established. However, cumulative data suggest that the determinant is expressed on a molecule related to HLA-DP.
Bovine leukemia virus (BLV) is a retrovirus similar to the human T-cell leukemia virus (HTLV). Most BLV infected animals (70%) develop a B-cell lymphoproliferative syndrome with altered productive traits and 1 to 5% die with B-cell lymphosarcomas. Although BLV infection is world-wide, western European countries have almost eradicated it by slaughtering the seropositive animals. BLV infection remains endemic in many countries including the United States and prophylactic strategies involving recombinant vaccine vectors, genetically modified BLV and transgenic animals resistant to the infection are under study.
Feline immunodeficiency virus (FIV) is a typical lentivirus that preferentially replicates in feline T lymphoblastoid cells and is the causative agent of a cat disease with features similar to the HIV-induced human AIDS. Its overall genetic organization is similar to human immunodeficiency virus (HIV) but the reduced complexity of the regulatory open reading frames renders FIV closer to ungulate than to primate lentiviruses. On the other hand, FIV infects both CD4+ and CD8+ T lymphocytes as well as feline B lymphocytes and macrophages. In addition, the FIV cellular receptor does not appear to be mostly constituted by the feline CD4 differentiation antigen. Nevertheless, the cat model may provide invaluable insight into the determinants of the immunodeficiency viruses pathogenesis. In addition, this model may help define novel approaches to eliciting protective immunity against HIV.
The Ca(2+)-ATPase from skeletal muscle sarcoplasmic reticulum was reconstituted into sealed phospholipid vesicles using the method recently developed for bacteriorhodopsin (Rigaud, J.L., Paternostre, M.T. and Bluzat, A. (1988) Biochemistry 27, 2677-2688). Liposomes prepared by reverse-phase evaporation were treated with various amounts of Triton X-100, octyl glucoside, sodium cholate or dodecyl octa(oxyethylene) glycol ether (C12E8) and protein incorporation was studied at each step of the liposome solubilization process by each of these detergents. After detergent removal by SM-2 Bio-Beads the resulting vesicles were analyzed with respect to protein incorporation by freeze-fracture electron microscopy, sucrose density gradients and Ca2+ pumping measurements. The nature of the detergent used for reconstitution proved to be important for determining the mechanism of protein insertion. With octyl glucoside, direct incorporation of Ca(2+)-ATPase into preformed liposomes destabilized by saturating levels of this detergent was observed and gave proteoliposomes homogeneous in regard to protein distribution. With the other detergents, optimal Ca(2+)-ATPase pumping activities were obtained when starting from Ca(2+)-ATPase/detergent/phospholipid micellar solutions. However, the homogeneity of the resulting recombinants was shown to be dependent upon the detergent used and in the presence of Triton X-100 or C12E8 different populations were clearly evidenced. It was further demonstrated that the rate of detergent removal drastically influenced the composition of resulting proteoliposomes: upon slow detergent removal from samples solubilized with Triton X-100 or C12E8, Ca(2+)-ATPase was found seggregated and/or aggregated in very few liposomes while upon rapid detergent removal compositionally homogeneous proteoliposomes were obtained with high Ca2+ pumping activities. The reconstitution process was further analyzed by centrifugation experiments and the results demonstrated that the different mechanisms of reconstitution were driven predominantly by the tendency for self-aggregation of the Ca(2+)-ATPase. A model for Ca(2+)-ATPase reconstitution was proposed which accounted for all our results. In summary, the advantage of the systematic studies reported in this paper was to allow a rapid and easy determination of the experimental conditions for optimal detergent-mediated reconstitution of Ca(2+)-ATPase. Proteoliposomes prepared by the present simple method exhibited the highest Ca2+ pumping activities reported to date in Ca(2+)-ATPase reconstitution experiments performed in the absence of Ca2+ precipitating agents.
BACKGROUND: The success of a screening program depends on a number of factors, including the validity of the test, its efficacy, its feasibility, and the rate of compliance. Thus, it is important to determine the factors influencing compliance to the screening test in order to obtain a high participation rate. METHODS: A mass screening campaign for colorectal cancer using the Hemoccult test was conducted in Burgundy, France. One year later, a questionnaire was mailed to a random sample of the population to assess the views of the general public (870 persons who had not completed the Hemoccult test, 750 persons who had a negative test, and 100 persons who had a positive test). The compliance rate of this survey was 32.2% among persons who had not completed the screening test, 88.2% among persons with a negative result, and 98.0% among persons with a positive result. RESULTS: The main reason for not participating was not wanting to know more about their health status (34.3%). Of the factors credited with encouraging persons to perform the test, the most important ones were the practitioner's explanations (55.7%) and the leaflet sent by mail (42.5%). The impact of the media campaign was weak. A small portion of the population (4.3%) said that they were very anxious while waiting for the results. Among persons with a positive screening test, only 1.2% regretted having taken it. Among those who took the test, 94.2% said they were ready to do it again; and among those who did not take it, 36.7% would accept it at a second screening. CONCLUSIONS: The data suggest that overall the Hemoccult is well accepted, that the campaign did not upset the population, and that it is worthwhile at the second screening to include those who did not participate in the first screening test.
Equilibrium and kinetic aspects of Triton X-100 adsorption onto hydrophobic Bio-Beads SM2 were investigated in detail using the batch procedure originally described by Holloway, P.W. (1973) Anal. Biochem. 53, 304-308. The results demonstrated the importance of the initial detergent concentration, the amount of beads, the commercial source of the detergent, the temperature and the presence of phospholipids in determining the rates of Triton X-100 adsorption onto Bio-Beads. One of the main findings was that Bio-Beads allowed the almost complete removal of Triton X-100, whatever the initial experimental conditions. It was shown that monomeric as well as micellar detergent could be adsorbed and that a key factor in determining the rate of detergent removal was the availability of the free bead surface. Rates of detergent removal were found to be linearly related to the amount of beads even for bead concentrations above those sufficient to remove all the detergent initially present. Adsorptive capacity of phospholipids onto Bio-Beads SM2 was also analyzed and found to be much smaller (2 mg lipid per g of wet beads) than that of Triton X-100 (185 mg TX 100 per g of wet beads). A more general aspect of this work was that the use of Bio-Beads SM2 provided a convenient way for varying and controlling the time course of Triton X-100 removal. The method was further extended to the formation of liposomes from phospholipid-Triton X-100 micelles and the size of the liposomes was found to be critically dependent upon the rate of detergent removal. A general procedure was described to prepare homogeneous populations of vesicles. Freeze-fracture electron microscopy and permeability studies indicated that the liposomes thus obtained were unilamellar, relatively large and impermeable. Noteworthy, this new procedure was shown to be well suited for the reconstitution of different membrane transport proteins such as bacteriorhodopsin, Ca2(+)-ATPase and H(+)-ATPase.
Recombinant bovine interferon-gamma augments expression of class I and class II histocompatibility antigens on the surface membrane of bovine lymphocytes. Immunofluorescence techniques using a series of monoclonal anti-HLA antibodies demonstrate that this enhancement is detectable as early as 24 h after incubation with rBoIFN, while maximum surface expression is obtained within 3-5 days. A concentration as low as 10 units of rBoIFN is effective. Such results may be useful for characterizing the BoLA gene products.
We report two cases of patients, 12 and 28 years old, suffering from a Budd-Chiari syndrome with a thrombosed inferior vena cava, who were treated by a shunt interposed between the superior mesenteric vein and the left innominate vein. The aim of this shunt was to avoid pericardiotomy in these patients with peroperative ascites, in order to reduce the risk of pericarditis after surgery. A reinforced polytetrafluoroethylene prosthesis (Gore-Tex) was used, associated with an interposition jugular vein graft in the 12-year old child, alone in the other case. The left innominate vein was isolated through a midline sternotomy, and the prosthesis was placed in a retrosternal position. Operation and postoperative course were uneventful. All signs of ascites disappeared. The patients were free of symptoms, 8 and 4 months after surgery respectively. Shunt patency was documented by angiography and magnetic nuclear resonance.
Bovine leukemia virus (BLV) is experimentally infectious for sheep. Virus production does not occur in the animals, but only after in vitro cultivation of infected lymphocytes in the presence of phytohemagglutinin. Lipopolysaccharide or dextran sulfate 500 had no effect. After panning separation, it was possible to demonstrate that, in peripheral blood lymphocytes, BLV was integrated in the B lymphocytes only and that BLV expression took place in a fraction of this population. The ovine leukemia may constitute a good experimental model for understanding the virus-induced leukemias of the BLV-human T cell leukemia virus group.