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Biomedical subjects

J Schüpbach

Publications and source records attributed to J Schüpbach.

At least 55 records · Page 3Linked to original sources
PubMed1992

Epidemiology of vertically transmitted HIV-1 infection in Switzerland: results of a nationwide prospective study. Swiss Neonatal HIV Study Group.

A nationwide study involving 286 children of human immunodeficiency virus (HIV)-infected mothers living in Switzerland has been performed with the participation of all paediatricians interested in HIV infection in the country. Of these children 201 could be followed up prospectively from birth up to a median age of 22 months. Prevalence of HIV infection in Swiss parturients was estimated at 0.1% and apparently remained stable from 1986 to 1989. Vertical transmission rate was estimated at 14%-20%. Variables of maternal or perinatal history were not associated with transmission rate. Transmission to pairs of siblings of the same mothers was discordant in 33% (6 of 18), with always the elder sibling being infected. Postneonatal mortality in infants of HIV-infected mothers followed up from birth was increased 15-fold over the general population with a very high incidence (2 in 100) of sudden infant death apparently unrelated to HIV infection.

Child↗
PubMed1991

A universal method for two-dimensional polyacrylamide gel electrophoresis of membrane proteins using isoelectric focusing on immobilized pH gradients in the first dimension.

Two-dimensional gel electrophoresis with immobilized pH gradients in the first dimension, initially applied for the separation of soluble and total cellular proteins, has been extended to the analysis of membrane proteins. We show that the usual procedures lead to artifacts and irreproducible results due to aggregation and precipitation of proteins and protein-phospholipid complexes during isoelectric focusing (first dimension) and sodium dodecyl sulfate (SDS) gel electrophoresis (second dimension). Optimized solubilization procedures for hydrophobic membrane proteins are presented and the use of dilute samples is shown to be essential to overcome the major problems in isoelectric focusing. Increased volumes of samples dissolved in rehydration buffer are applied by direct rehydration of dry immobilized pH gradient (IPG) gels. Isoelectric focusing in 2% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) without urea gives good results as does 2% Nonidet-P40 with 8 M urea. Heat denaturation should be avoided. An optimized equilibration procedure for IPG gel strips in SDS sample buffer prior to separation in the second dimension was developed that minimizes loss of proteins and results in high-resolution two-dimensional electropherographic maps with a minimum of streaking. The gel strips are partially dehydrated at 40 degrees C and shortly reswollen in situ on the SDS slab gel in SDS-sample buffer containing agarose.

Animals↗
PubMed1990

Three-dimensional electron microscopy of entire cells.

The digital processing of serial electron-microscope sections containing laser-induced topographical references allows a three-dimensional (3-D) reconstruction of entire cells at a depth resolution of 40-60 nm by the use of novel image analysis methods. The images are directly processed by a video-camera placed under the electron microscope in TEM mode or by the electron counting device in STEM mode. The deformations associated with the cutting of embedded cells are back-calculated by new computer algorithms developed for image analysis and treatment. They correct the artefacts caused by serial sectioning and automatically reconstruct the third dimension of the cells. Used in such a way, our data provide definitive information on the 3-D architecture of cells. This computer-assisted 3-D analysis represents a new tool for the documentation and analysis of cell ultrastructure and for morphometric studies. Furthermore, it is now possible for the observer to view the contents of the reconstructed tissue volume in a variety of different ways using computer-aided display techniques.

Cell Line↗
PubMed1989

Detection of high concentrations of HTLV-1 p24 and a novel gag precursor, p45, in serum immune complexes of a healthy seropositive individual.

Circulating immune complexes from sera of 6 patients with adult T-cell leukemia and 8 asymptomatic carriers infected with the human T-cell leukemia virus type 1 (HTLV-1) were precipitated with polyethylene glycol, and the precipitates were tested for the presence of viral antigen p24 by Western blot, using affinity-purified radiolabelled goat antibody to p24 as a probe. p24 and a larger protein of Mr 45,000 immunologically related to p24 were detected at concentrations of up to 100-200 ng/ml in one of the carriers, while all other samples were negative. The concentration of the Mr 45,000 protein in the immune complexes was considerably higher than that of p24. Analysis of an HTLV-1 producer cell line, G-11/MJ, by competition Western blots and gag-specific antibodies, showed the presence of a hitherto unrecognized viral protein p45 which contains both p19 and p24 and probably represents an intermediate precursor of these proteins. The results present direct evidence of production of HTLV-1 proteins in an asymptomatically infected individual.

Antigen-Antibody Complex↗
PubMed1989

Stable human immunodeficiency virus encephalopathy in two infants receiving early intravenous gammaglobulin plus antimicrobial prophylaxis.

Two infants with human immunodeficiency virus (HIV) infection, encephalopathy, intrathecal anti-HIV IgG antibody production and (in one case) the presence of HIV antigen received monthly doses of intravenous gammaglobulin (IVGG) and daily antimicrobial prophylaxis starting at the ages of 6 and 9 months respectively. The follow-up over 15 and 12 months revealed a favourable course with remarkable improvement in visuo-spatial functions, receptive language, play behaviour and fine motor skills, as well as in muscle tone, pyramidal tract signs and vigilance in case 1, and near normalization in case 2. Viability of HIV in peripheral blood mononuclear cells, antigen in serum and cellular immunodeficiency, however, all remained unchanged. We suggest that neurological complications of encephalopathy in paediatric acquired immunodeficiency syndrome may have a slower progression when IVGG treatment plus antimicrobial prophylaxis is started early.

Acquired Immunodeficiency Syndrome↗
PubMed1989

First documented case of human immunodeficiency virus type 2 infection in an asymptomatic Swiss subject.

Few cases of human immunodeficiency virus type 2 (HIV-2) infection have been reported in individuals other than of West African origin. The first well documented case of HIV-2 infection observed in a Swiss subject is presented here. The 50-year-old woman had a sexual relationship with a Senegalese man, who was later shown to be HIV seropositive. Initially, the subject's serum was tested using a routine screening assay for the detection of HIV-1 antibodies. This assay elicited a borderline positive result. A confirmatory competitive EIA and a Western blot test for anti-HIV-1 antibodies showed a positive reaction with gag and pol proteins of HIV-1, but not with env proteins. Thus, HIV-2 infection was suspected and subsequently confirmed by three different methods, including Western blot analysis and an HIV-1/HIV-2 differentiation test. This case emphasizes the need for screening with combined HIV-1/HIV-2 tests.

Blotting, Western↗
PubMed1989

Immunological evaluation in the early diagnosis of prenatal or perinatal HIV infection.

A longitudinal evaluation was carried out of the clinical, infective, and immunological progress of 34 children (who were aged 6 to 68 months--mean 25 months at the time of writing) born to 31 mothers infected with human immunodeficiency virus (HIV), over a mean observation period of 13.4 months. Clinical symptoms, not always clearly related to HIV became apparent in 11 children, and preceding immune abnormalities were documented in two of them. In eight children culture for HIV was positive, and six of these were symptomatic. No cancers were diagnosed and none of the children died. Immune abnormalities including hypergammaglobulinaemia, IgG subclass deficiency, low serum IgA concentration, antibody deficiency, a decrease in the number of CD4+(T helper) cells, and defective cellular responses to antigens, were found in seven of the children in whom culture for HIV was positive; in two of four who had symptoms and in all four who were symptom free and in whom culture was negative for HIV but in whom HIV antibodies persisted and who were older than 15 months; and in three of nine who were symptom free and in whom culture was negative with loss of HIV antibodies. We conclude that serological diagnosis alone may be misleading and that additional immunological assessment may help to identify affected children. Analysis of humoral and cellular responses to antigens used for vaccination such as tetanus toxoid by measurement of specific antibodies and skin testing are simple and helpful in clinical practice.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[New test systems in HIV diagnosis].

Knowledge of the biologic properties of HIV infections, mainly the existence of alternating cycles of latency and active virus replication, is the basis for a sensible use of diagnostic tests. The newly developed polymerase chain reaction (PCR) is capable of demonstrating the presence of HIV genomes in active as well as latent phases of infection. In contrast, the successful use of serologic tests is based on the preceding, or continued, expression of viral proteins. The article reviews procedure and preliminary results of the PCR, and presents newly developed serologic tests with interesting prospective applications.

AIDS Serodiagnosis↗
PubMed1989

Frequent detection of HIV- and IgG-specific IgM and IgA antibodies in HIV-positive cord-blood sera: fine analysis by western blot.

Cord-blood sera of 36 babies born to HIV-positive mothers in Switzerland were tested for immunoglobulin (Ig) M or IgA by HIV Western blot. IgM was found in 28, and IgA in 19 of unabsorbed sera. Preabsorption with immobilized protein A or G was used to remove IgG, which allowed differentiation between HIV-specific and IgG-specific IgM or IgA. Protein G proved superior and showed that 30% of 23 sera had HIV-specific IgM, while 48% had HIV-specific IgA. HIV-specific IgM and/or IgA was found in 13 out of 21 cases (62%); four out of 21 (19%) had both. HIV-specific IgM reacted most frequently with pol or env proteins, while HIV-specific IgA reacted more frequently with gag than pol; no IgA were directed against env proteins. IgG-specific IgM and IgA, mostly at gag bands, were present in 83 and 38%, respectively. Thus, a large percentage of children born to HIV-positive mothers have HIV-specific IgA and/or IgM which can be distinguished from IgG-specific IgA or IgM, which is also present in the majority of such children. Future studies will have to show whether these antibodies are of diagnostic relevance.

AIDS Serodiagnosis↗
PubMed1988

HTLV-1 in Switzerland: low prevalence of specific antibodies in HIV risk groups, high prevalence of cross-reactive antibodies in normal blood donors.

Sera from various Swiss population groups were tested for antibodies against the human T-cell leukemia virus type I (HTLV-I). Particle agglutination and ELISA were performed for screening; Western blot was done for confirmation. True-positive sera were found at a prevalence of 0.12% in a cohort of 846 individuals at risk for AIDS tested in 1984-1985. Prevalences of 0.35% were found among 575 HIV-I positives tested in 1987, and of 1.3% among 292 HIV-I positives of a different group tested in 1988. The 6 positives found in our study represent the first cases of HTLV-I infection, or HIV-I/HTLV-I double infection, diagnosed in Switzerland. In addition, high proportions of sera, regardless of whether they were from normal blood donors, HIV-positives, or individuals at risk for AIDS, had antibodies that reacted weakly with one or several proteins of the size of viral gag proteins. The prevalence of such antibodies in normal donors was in the range of 10 to 40%, depending on the strictness of interpretation. Competition Western blots performed with some of these sera showed that these antibodies reacted with HTLV-I, but not with HIV-I or cellular antigens, and had a lower affinity to HTLV-I proteins than the antibodies of human or goat antisera. The results indicate that these antibodies may be induced by agents immunologically related to, but different from, HTLV-I, which are highly prevalent in the Swiss population. Oligopeptide stretches with sequence homology to HTLV-I are known to exist in various normal body proteins, several infectious agents including common viruses and protozoa, but the results might also indicate the existence of additional human retroviruses. Screening of blood donors with sensitive tests for antibodies to HTLV-I might produce an unacceptably high rate of false-positive results, if stringent rules of interpretation analogous to those common in HIV screening are not used.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Evaluation of diagnostic tests for HIV infection in infants born to HIV-infected mothers in Switzerland.

Children born to HIV-infected women in Switzerland were tested every 3 months for HIV-reactive serum immunoglobulin (Ig) G, IgM and IgA antibodies by Western blot, viral antigen, virus replicating in T-lymphocyte cultures, and immunologic and clinical parameters. At birth, 27% were isolation-positive, 68% had IgM, 48% IgA and 10% circulating antigen. The proportion of IgM and IgA declined to about 18 and 27%, respectively, during the first 2 years. Detection of circulating antigen was less frequently positive than virus isolation in all age and disease groups. Clinical symptoms were only seen in infants or children who were or had been positive for IgM and/or IgA, but only 39% of children positive for these markers have developed disease so far. Clinical symptoms combined with signs of immunodeficiency were seen only in children who were isolation-positive or had evidence of HIV-reactive IgA or child-produced IgG. Absorption studies showed that Western blot-detected IgM and IgA antibodies were of two types: 42% were directed against various HIV proteins, while the rest represented rheumatoid-factor-like IgM or IgA binding to HIV-specific IgG. HIV-specific IgG antibodies were detected in all samples up to the age of 12 months and were still found in 83% of infants 13-18 months old. We observed weak HIV-specific IgG above the age of 15 months with no other signs of HIV infection, suggesting that the demonstration of antibodies in children beyond this age does not necessarily indicate HIV infection.

AIDS Serodiagnosis↗
PubMed1987

Anti-HIV IgM antibody analysis during early manifestations of HIV infections.

In a prospective study we tested the appearance of IgG and IgM positive viral protein bands in Western blots from six people who seroconverted for anti-HIV antibody. Quantification of the immunoblotted bands was performed by reading the Western blot stripes in Camag scanner and analysed on a 350 computer (digital equipment). In the first serum, all people were negative for anti-HIV antibodies. In the second serum, after 16 to 122 days, all people showed IgM HIV-antibodies to p24. IgG HIV-antibodies were detectable in all people after 18 to 114 days after the second collection. Our data clearly demonstrated that for early analysis of HIV infection only the detection of IgM antibodies to viral protein bands of the Western blot technique provides reliable results and that scanning and advanced integration analysis of the Western blot peaks offer the advantage of direct quantitative comparison of the results, not just qualitative description. Further, this direct quantitative comparison of antibodies to HIV virus protein bands can be used as a prognostic marker for disease states.

Adult↗