Biomedical subjects

C Kunz

Publications and source records attributed to C Kunz.

At least 145 records · Page 8Linked to original sources

PubMed1990

A single amino acid substitution in envelope protein E of tick-borne encephalitis virus leads to attenuation in the mouse model.

We have determined the virulence characteristics of seven monoclonal antibody escape mutants of tick-borne encephalitis virus in the mouse model. One of the mutants with an amino acid substitution from tyrosine to histidine at residue 384 revealed strongly reduced pathogenicity after peripheral inoculation of adult mice but retained its capacity to replicate in the mice and to induce a high-titered antibody response. Infection with the attenuated mutant resulted in resistance to challenge with virulent virus. Assessment of nonconservative amino acid substitutions in other attenuated flaviviruses suggests that a structural element including residue 384 may represent an important determinant of flavivirus virulence in general.

Amino Acid Sequence↗

PubMed1989

[Results of rubella prevention in Austria (1988 status)].

The aim of any rubella eradication programme is the prevention of rubella embryopathy. In Austria, every girl aged 13 years is vaccinated without prior antibody testing. In addition, all pregnant women are tested for antibodies and vaccinated post partum, if necessary. As in other European countries, this policy has not (yet) led to the elimination of rubella embryopathies. In 1987 and 1988, 3 embryopathies as well as 16 and 17, respectively, rubella infections in pregnant women were diagnosed. In order to monitor the effectiveness of the vaccination in 13 years old girls, we tested 325 sera from student nurses (mean age 15.6 years) as well as 895 sera from pregnant women (mean age 23.1 years). In the 1st group, only 2.2% had a titer of less than or equal to 16 in hemagglutination inhibition test and therefore were not unequivocally protected. In the pregnant women, this ratio was 6.1%. We therefore draw the conclusion that in some cases the protection afforded by the vaccination begins to decrease after 10 years. At the same time, we also tested the sera of 4186 pregnant women who claimed they never had been vaccinated. Their mean age was higher (26 years) and 11.1% were not unequivocally protected. In addition, we tested 28 women who had been vaccinated 3 to 6 months previously due to negative serology. Of these, 6 (21.4%) did not produce antibodies with a titer of at least 32. Many European countries had the same experience and therefore began vaccinations of all children in the 2nd year, using the trivalent vaccine (mumps, measles, rubella) instead of the bivalent one (without rubella).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1989

[Comparison of virus isolation and antigen enzyme immunoassay in the detection of HIV].

Virus isolation from peripheral blood lymphocytes and antigen detection in serum by ELISA were compared in 75 patients with a serologically confirmed HIV infection. 25 per cent of the lymphocyte cultures were HIV positive, but only 2 of the 14 patients were also antigen positive. In addition, infectious virus was not detected in 15 antigen positive patients, thus revealing only a low degree of correlation between the two assay systems.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Immunoglobulin-class-specific immune response to respiratory syncytial virus structural proteins in infants, children, and adults.

The protein specificities of IgG, IgM, and IgA antibodies induced during respiratory syncytial virus (RSV) infection in 74 patients (4 weeks to 81 years of age) were investigated using the technique of immunoblotting. Although the pattern of antibody reactivity varied among patients, most of the humoral immune response in all age groups was directed against the 48, 42, 35, and 27 K proteins. An infant's own antibody response was discernible in 55 of the 57 children below 1 year of age, despite the presence of maternally derived antibodies. Antibody against the 90 K surface glycoprotein was not detectable in those less than 1 year of age. Primary RSV infection induced antibodies only against a subset of RSV proteins. Although a broadening of the antibody response occurred with increasing age and in the course of reinfection, an immune response to all the viral structural proteins was observed rarely.

Adolescent↗

PubMed1989

Efficiency of the polymerase chain reaction for the detection of human immunodeficiency virus type (HIV-1) DNA in the lymphocytes of infected persons: comparison to antigen-enzyme-linked immunosorbent assay and virus isolation.

Seventy-one human immunodeficiency virus type (HIV-1)-positive patients were investigated by polymerase chain reaction (PCR), virus isolation, and antigen detection for the existence of HIV in blood. The identification of HIV DNA by PCR, using three different pairs of primers, yielded a clearly higher detection rate (86%) than with two primer pairs (75%) and was far more sensitive than virus isolation (45%) and antigen ELISA (14%). The PCR-negative results were clearly correlated to asymptomatic clinical stages. However, there was a limited correlation between the clinical stage of disease and the amount of HIV DNA that could be detected in equal numbers of CD4+ cells from different patients, which might be due to their treatment with azido-thymidine (AZT).

Acquired Immunodeficiency Syndrome↗

PubMed1989

A trial of RIT-4237 rotavirus vaccine in 1-month-old infants.

In a double blind placebo-controlled study rotavirus vaccine RIT 4237 was offered to young infants after the fourth week of life. The vaccine was very well tolerated. Fifty-seven out of 100 vaccine recipients and 10 out of 103 placebo recipients developed rotavirus-IgM-antibodies during the 1 month follow-up period. During a 6 month follow-up, stool samples from 2 out of 12 vaccinees and from 5 out of 12 placebo recipients contained rotavirus.

Antibody Formation↗

PubMed1989

In vitro drug sensitivity test for Trypanosoma brucei subgroup bloodstream trypomastigotes.

An in vitro test has been developed to determine drug sensitivities of bloodstream trypomastigotes of Trypanosoma (T.) brucei isolates. The incorporation of [14C]leucine, [3H]thymidine and [3H]hypoxanthine into bloodstream forms in vitro was compared and different sensitivity test procedures with trypanocidal drugs were evaluated. Bloodstream forms were added to a microtiter plate with serial dilutions of trypanocidal drugs containing a cell-free culture medium supplemented with a mammalian serum, which allows continuous cultivation of the bloodstream stages. After a preincubation period of 16 h, [3H]hypoxanthine was added, and after another 8 h, the cells were harvested with a cell harvester. The glass fiber filters on which the cells were collected were counted in a liquid scintillation counter and the percent inhibition determined as percentage of the control counts. This method gave accurate, reproducible results for T. (T.) brucei isolates tested with the trypanocidal drugs suramin, berenil, samorin, lomidine and Mel W.

Animals↗

PubMed1989

In vitro drug sensitivity of Trypanosoma gambiense isolates.

Drug sensitivities of seven Trypanosoma b. gambiense isolates from patients in the Ivory Coast were measured for Mel B, suramin and lomidine using an in vitro incorporation test. Bloodstream forms were isolated from Mastomys natalensis, incubated in serial drug dilutions in a microtiter plate, after 24 h, radiolabeled hypoxanthine was added, and the plate incubated for another 15 h. Trypanosomes were then harvested onto glass fiber filters with a cell harvester and incorporation of label was determined in a liquid scintillation counter. From the incorporation inhibition curves IC50 and IC75 values were calculated. IC50 values for Mel B ranged from 0.5 to 4.6 ng/ml, for suramin from 7.2 to 30.5 micrograms/ml, and for lomidine from 2.1 to 7.0 ng/ml. Isolate TH-1/78E(031) was the least sensitive to all three drugs while TH-1/78E(020), TH-64/78E(020) and TH-31/78E(025) were the most sensitive to the drugs used. THDAL 1030R, an isolate from a patient who relapsed after three consecutive Mel B treatments, showed an IC50 value for Mel B of 1.20 ng/ml. The in vitro drug sensitivity test gave reproducible results for the T b. gambiense isolates tested.

Animals↗

PubMed1989

Epitope model of tick-borne encephalitis virus envelope glycoprotein E: analysis of structural properties, role of carbohydrate side chain, and conformational changes occurring at acidic pH.

A panel of monoclonal antibodies (MAbs) was prepared to analyze the antigenic structure of the tick-borne encephalitis (TBE) virus glycoprotein E. Nineteen different epitopes were identified and characterized with respect to serological specificity, functional activity, structural properties, and topological relationships. Except for 3 isolated epitopes (i1, i2, and i3), these cluster to form three non-overlapping domains termed A, B, and C. The structural properties of epitopes were assessed by analyzing the effect of different treatments (SDS denaturation, reduction and carboxymethylation, performic acid oxidation, exposure to pH 5.0, CNBr, and trypsin cleavage) on the antigenic reactivities of each epitope. Only 3 epitopes of domain A as well as i2 were sensitive to SDS alone, whereas all others were SDS resistant. Reduction and carboxymethylation, however, destroyed the antigenic reactivity of all epitopes of domain B and also that of two SDS-resistant epitopes of domain A, indicating the role of disulfide bridges in stabilizing the conformation of these epitopes. Deglycosylation by N-Glycanase abolished the SDS resistance of domain C, providing evidence of the role of the carbohydrate side chain in stabilizing these epitopes. A conformational change induced by acid pH was revealed by differences in protease (proteinase K) cleavage maps before and after acid pH treatment. The conformational change involved the epitopes of domain A and occurred between pH 6.0 and 5.5 with the the threshold at pH 7.0.

Animals↗

PubMed1989

Genome sequence of tick-borne encephalitis virus (Western subtype) and comparative analysis of nonstructural proteins with other flaviviruses.

The genome sequence of tick-borne encephalitis (TBE) virus (Western subtype vaccine strain Neudoerfl) was determined. This extends the previously published sequence of the structural proteins to the nonstructural protein region and noncoding sequences at the 5'- and 3'-termini. The amino-termini of the individual proteins were assigned by comparison with other flavivirus sequences. Amino acid homology calculations between TBE virus and mosquito-borne flaviviruses were performed for all nonstructural proteins. An evolutionary tree based on protein NS1 is presented that reveals the molecular basis of relationships among flaviviruses. Tick-borne and mosquito-borne flaviviruses share a common hydrophilicity profile and also other features of their primary sequences, such as the presumably functional Gly-Asp-Asp sequence element within protein NS5. Other characteristics, such as the potential N-glycosylation sites of protein NS1 and a potential proteolytic cleavage site within protein NS4B, are conserved within the mosquito-borne group, but differ in the TBE virus sequence.

Amino Acid Sequence↗

PubMed1989

Human milk proteins: separation of whey proteins and their analysis by polyacrylamide gel electrophoresis, fast protein liquid chromatography (FPLC) gel filtration, and anion-exchange chromatography.

Human milk proteins are of nutritional and physiological significance to the newborn infant. To further study these proteins, a rapid procedure to separate and analyze human milk whey proteins was developed using fast protein liquid chromatography (FPLC). First, to separate whey proteins from casein, different variables such as low- or high-speed centrifugation at different temperatures with or without adjustment of pH to 4.6 or 4.3 and with or without addition of calcium to whole milk or skim milk were tested. Each variable was evaluated by gel filtration, anion-exchange chromatography, sodium dodecyl sulphate (SDS)-polyacrylamide gradient gel electrophoresis, immunoelectrophoresis, and immunodiffusion. The optimum method for a discrete separation of whey and casein is the adjustment of whole milk to pH 4.3 with addition of 60 mmol calcium/L, followed by ultracentrifugation. Rapid and sensitive separation and analysis of whey proteins was achieved by FPLC gel filtration and anion-exchange chromatography.

Chromatography, Gel↗

PubMed1989

Identification of transferrin as the major plasma carrier protein for manganese introduced orally or intravenously or after in vitro addition in the rat.

It is known that the metabolic handling of manganese (Mn) introduced via the diet or by intravenous injection is quite different. We hypothesized that this difference could be due in part to different proteins carrying Mn in plasma that could affect tissue uptake and retention. To test this idea, 54Mn was administered orally or intravenously to rats, and blood samples were taken by cardiac puncture at various time points postdosing. Plasma proteins were separated using fast protein liquid chromatography with a combination of anion exchange and gel filtration columns. Using these methods, independent of the route of 54Mn administration, transferrin was identified as the major Mn-binding protein in plasma. The identity was further confirmed by SDS-polyacrylamide gradient gel electrophoresis and Western blotting. These results conclusively show that 54Mn in plasma is carried by transferrin, regardless of route of administration and time postdosing.

Administration, Oral↗

PubMed1989

Inhibitory effects of phytic acid and other inositol phosphates on zinc and calcium absorption in suckling rats.

While it is known that phytic acid, inositol hexaphosphate, has a negative effect on zinc and calcium absorption, the effects of inositol which is phosphorylated to a lesser extent are less known. We have prepared inositol triphosphate (IP-3), tetraphosphate (IP-4), pentaphosphate (IP-5) and hexaphosphate (IP-6) by hydrolysis of sodium phytate and separation by ion-exchange chromatography and have studied their effect on zinc and calcium absorption. Using a suckling rat pup model, we found that liver uptake of 65Zn after 6 h was 5% of the total dose from solutions of IP-6, 19% from IP-5, 28% from IP-4, 29% from IP-3 and 31% from ZnCl2 (control). Non-absorbed calcium was 17%, 1.4%, 0.5%, 0.5% and 0.5% of the given dose of 45Ca, respectively. Thus, at a high degree of phosphorylation (IP-6, IP-5), zinc and calcium uptake was inhibited, while no effect was observed for the other phosphates. Consequently, total "phytate" analysis, which includes inositol phosphates with varying degrees of phosphorylation, can give misleading information with regard to mineral availability. In addition, even limited dephosphorylation of inositol hexaphosphate can have a positive effect on mineral absorption.

Animals↗

PubMed1989

Characterization of antigenic variants of tick-borne encephalitis virus selected with neutralizing monoclonal antibodies.

Antigenic variants of tick-borne encephalitis virus were selected by the use of six neutralizing monoclonal antibodies (MAbs), each defining a different epitope of the envelope glycoprotein E. These variants were characterized with respect to antigenic changes by analysing the binding of each of 18 precisely mapped MAbs in ELISA and haemagglutination inhibition tests. The results yielded information about interrelations between epitopes exceeding that obtained previously from competitive binding studies. In addition, variants were tested for their specific haemagglutination activities, which revealed a significant reduction of this functional activity in one of the variants.

Animals↗

PubMed1989

Clinical manifestations of respiratory tract infections due to respiratory syncytial virus and rhinoviruses in hospitalized children.

From September 1984 to May 1986, nasopharyngeal secretions were obtained from 519 children with some form of respiratory tract infection. The nasal secretions were screened for respiratory syncytial virus (RSV), rhinoviruses, adenoviruses, parainfluenza virus types 1, 2, 3, influenza virus types A and B, and enteroviruses by tissue culture virus isolation technique and/or enzyme-linked immunosorbent assay. A uniform questionnaire gave information about age, sex, individual signs and symptoms, findings of the physical examination and clinical diagnosis of the patients. RSV was detected in 119 (23%) specimens and was thus the most frequent causative agent of respiratory infections. After RSV, rhinoviruses were the most frequently recovered pathogens accounting for 60 (12%) cases of acute respiratory disease. A comparison of the individual signs and symptoms, the findings of the physical examination and the clinical diagnosis of RSV and rhinovirus infected children revealed that there was no characteristic clinical pattern associated with either of the two viral respiratory pathogens. According to our results, rhinovirus infections were a major cause of lower respiratory tract infections in hospitalized children less than or equal to 3 years old.

Child, Preschool↗

PubMed1989

Antigenic structure of the flavivirus envelope protein E at the molecular level, using tick-borne encephalitis virus as a model.

A model of the tick-borne encephalitis virus envelope protein E is presented that contains information on the structural organization of this flavivirus protein and correlates epitopes and antigenic domains to defined sequence elements. It thus reveals details of the structural and functional characteristics of the corresponding protein domains. The localization of three antigenic domains (composed of 16 distinct epitopes) within the primary structure was performed by (i) amino-terminal sequencing of three immunoreactive fragments of protein E and (ii) sequencing the protein E-coding regions of seven antigenic variants of tick-borne encephalitis virus that had been selected in the presence of neutralizing monoclonal antibodies directed against the E protein. Further information about variable and conserved regions was obtained by a comparative computer analysis of flavivirus E protein amino acid sequences. The search for potential T-cell determinants revealed at least one sequence compatible with an amphipathic alpha-helix which is conserved in all flaviviruses sequenced so far. By combining these data with those on the location of disulfide bridges (T. Nowak and G. Wengler, Virology 156:127-137, 1987) and the structural characteristics of epitopes, such as dependency on conformation or on intact disulfide bridges or both, a model was established that goes beyond the location of epitopes in the primary sequence and reveals features of the folding of the polypeptide chain, including the generation of discontinuous protein domains.

Amino Acid Sequence↗

PubMed1988

[AIDS in Austria].

AIDS is a notifiable disease in Austria. In 1983, the first 6 cases were recorded. Thereafter, the numbers doubled approximately each year, reaching 182 on May 30, 1988. On the same date, a total of 2433 persons were found to be infected. The highest rates of AIDS patients and seropositive individuals were recorded in Vienna (72/1355), followed by Upper Austria (37/470) and the Tyrol (20/318). For the most part patients with AIDS are members of the classical risk groups (homo- or bisexual men: 49.5%, i.v. drug users: 26.4%). Since autumn of 1987, almost half of those persons who are found to be infected are i.v. drug addicts. Heterosexual transmission of HIV is still rare but appears to be increasing. Judging from the situation in Vienna legal prostitution does not seem to contribute to the spread of the virus.

Acquired Immunodeficiency Syndrome↗

PubMed1988

[Serology in HIV infection: comparison of indirect immunofluorescence, Western blot and enzyme immunoassay].

145.990 sera obtained from AIDS-risks groups, hospitalized patients, blood donors etc. were tested for the presence of antibodies against the AIDS-Virus (HIV:Human Immunodeficiency Virus). All sera were submitted to ELISA screening. Sera with positive and questionable results were submitted to two independent confirmatory tests (Western Blot and immunofluorescence). In case of discordant confirmatory tests sera were additionally tested with the Abbott anti-HIV envelope/anti HIV core ELISA. The results of the present study demonstrate: 1. HIV serology has been definitely improved during the last year due to the development of high quality reagents. 2. Provided skilled and trained personnel the combined use of HIV confirmatory tests (Western Blot and immunofluorescence) does not give false negative or false positive results. 3. The results of both confirmatory assays may not always be interpretable ("problem sera"); this occurs more often with the Western Blot technique than with immunofluorescence. 4. Discrepant results in confirmatory tests necessitate the evaluation of many additional tests as possible. Such persons or patient should be further controlled serologically and clinically. 5. Checking the "problem sera" for antibodies against HTLV I gave only one single positive result in a Japanese.

Acquired Immunodeficiency Syndrome↗