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Biomedical subjects

C Kunz

Publications and source records attributed to C Kunz.

At least 199 records · Page 11Linked to original sources
PubMed1985

Separation of flavivirus membrane and capsid proteins by multistep high-performance liquid chromatography optimized by immunological monitoring.

Complete separation of the three structural proteins, E, C and M, of an enveloped virus (tick-borne encephalitis virus) was achieved by means of a two-step high-performance liquid chromatography (HPLC) technique in less than 1 h. The hydrophobically associated membrane proteins E and M were successfully separated by high-performance gel permeation chromatography (TSK-3000 SW column) in the presence of sodium dodecyl sulphate (SDS), whereas the separation of M and C as well as desalting and removal of SDS was achieved by subsequent reversed-phase chromatography on a C3 column. With regard to further characterization by peptide mapping, analysis of the amino acid composition and aminoterminal sequencing, the second step was performed with volatile buffer systems. Quality control of the separation was achieved by a combination of HPLC with a highly sensitive dot immunoassay by the use of polyclonal as well as monoclonal antibodies. This method proved extremely sensitive and revealed strong tailing effects and cross-contaminations of peaks well-separated in reversed-phase chromatography, which were neither apparent in the absorbance curve at 214 nm nor in the analysis by SDS-polyacrylamide gel electrophoresis. By visualization of the peak-tailing effect, the chromatographic conditions could be modified in order to achieve an optimum separation of proteins.

Antibodies, Monoclonal↗
PubMed1985

[Delta virus: now also detected in Austria. A defective virus as a pathogenic agent].

delta-virus, first described by Rizzetto, is a defective virus dependent on hepatitis B virus as helper-virus. Superinfection of inactive hepatitis B with delta-virus leads to chronic active or even fulminant hepatitis. It can be detected by RIA or ELISA and its distribution is world-wide. Also in Austria, 4 sera with antibodies to delta-virus have been found among 138 HBsAg-positive sera. No therapy is known, but vaccination against HB virus also prevents the propagation of delta-virus.

Austria↗
PubMed1985

[Vitamin D sterol in human milk, cow's milk and baby food].

A review is given of the results of vitamin D determinations in human and cow's milk using physico-chemical methods. Thereby only parent vitamin D is determined. Further, the results obtained with protein-binding assays are discussed in detail. With the aid of these newer methods the concentrations of hydroxylated vitamin D derivatives can also be measured. A comparison of the concentration of these vitamin D metabolites in human milk and infant formulas based upon cow's milk suggests that the higher anti-rachitic activity of human milk is connected with its higher concentration of 25-hydroxy-vitamin D.

Animals↗
PubMed1985

Tick-borne encephalitis: a simple method for detection of antibody production in the brain.

Antibodies found in c.s.f. of patients with TBE are usually produced in the CNS itself, although their presence might also be due to a leak in the blood brain barrier. In the case of local antibody production the ratio of the TBE specific IgM or IgG to the total immunoglobulin is relatively high in c.s.f., whereas in case of a leak this ratio is lower and corresponds to that of the serum. Local antibody production in the brain can therefore be assumed, if the ratio is higher in c.s.f. than in serum. It is possible to determine this ratio in an anti-mu or anti-gamma capturing antibody ELISA, provided that the concentration of capturing antibodies represents the limiting factor of the test system. Under these conditions the absorbance values obtained are a direct reflection of the TBE reactive to nonreactive antibody ratio, since they compet for the limited binding sites presented on the solid phase. Higher extinction values of c.s.f. compared to that of serum are therefore an indication for local antibody production in the brain. Using the method described, differences were found in the production of IgM and IgG antibodies against TBE in the CNS from patients with different clinical history.

Antibodies, Viral↗
PubMed1985

Carbon-14 discharge at three light-water reactors.

A long-term-sampling evaluation was made of the quantity, discharge pathway, and chemical form of 14C released from 2 pressurized water reactors (PWR) and 1 boiling water reactor (BWR) in the northeastern United States. For the R. E. Ginna PWR the discharge rate of gaseous 14C was 11.6 Ci/GW(e)-yr. Venting of gas decay tanks accounted for 42%, while 35% was discharged through auxiliary building ventilation and 23% through containment venting. The average chemical composition was 10% as 14CO2, 90% as 14CH4 and other hydrocarbon gases. For the Indian Point Unit 3 PWR, the discharge rate was 9.6 Ci/GW(e)-yr, primarily by pressure-relief venting and purging of the containment air. Venting of gas decay tanks accounted for about 7% of the total released. The chemical species were 26% 14CO2, 74% 14CH4 and other hydrocarbon gases. For the J. A. FitzPatrick BWR, the discharge rate was 12.4 Ci/GW(e)-yr. Approximately 97% of the release was via off-gas discharge, which was about 95% 14CO2. For all 3 reactors the quantity of 14C released with liquid and solid wastes was less than 5% of the gaseous release.

Air Pollutants↗
PubMed1985

Proteins and peroxidase in callus and suspension cultures of apple : a study using ultrathin-layer isoelectric focusing, sensitive silver staining of proteins, and peroxidase isozyme visualization.

Different methods for the isolation of soluble proteins were applied to cell cultures of three apple cultivars (Malus sylvestris Mill.), best results being obtained with a rapid technique based on freezing and thawing. Ultrathin-layer isoelectric focusing followed by an improved silver staining method has shown that proteins from apple callus cultures consist of some 60 to 80 zones, with isoelectric points mainly between pH 4 to 7. Depending on protein content, adequate silver staining is achieved with 50 to 500 cells. Protein patterns of callus cultures allowed clear discrimination of cultivars. Protein and peroxidase isozyme patterns in cell saps of suspension cultures show striking differences during the growth cycle, whereas the protein patterns from the nutrient media were constant over the entire cultivation period and closely resembled the patterns of stationary phase and callus cells.

Journal Article↗
PubMed1984

[Early prognosis of the course of hepatitis B using radioimmunoassay of HBA/IgM complexes].

By other authors complexes of HBsAg and nonspecific gammaglobulin of the IgM class were found in the serum in the early stages of hepatitis B. These complexes were detected by radioimmunoassay. They persisted in chronic hepatitis, but disappeared from the serum within one month in acute cases. Our own data also confirm these findings. From our figures it can be calculated that the prognosis of acute hepatitis in any one patient can be stated with a probability of 98.8% as early as 4 weeks after onset of the disease. Two weeks later a chronic course can be predicted with a probability of 82%. HBsAg/IgM-complexes occur almost exclusively in sera positive for HBsAg. Their disappearance, however, is independent of the presence of HBeAg, as well as of the amount of HBsAg. They represent a new marker which is recognizable at an early stage of infection and gives a reliable prognosis of the course of hepatitis B.

Antigen-Antibody Complex↗
PubMed1984

[Experiences with vaccination against hepatitis B].

In a field study conducted with the Hepatitis B vaccine HB-Vax 375 persons were vaccinated and the sera were assayed for the formation of HBs antibodies 1 to 3 months after completing the three-dose schedule. Seroconversion was demonstrated in 94.7% of the subjects. Immune response was poorer after 40 years of age as compared with younger age groups. The vaccine was very well tolerated and induced hardly any side effects. 49 persons who had received 3 of the 4 doses suggested for vaccination with Hevac B responded in 86% of cases with the formation of antibodies. Patients undergoing dialysis developed antibodies in 48% of cases after the third dose and in 77% after the fourth dose, the seroconversion rate thus being considerably lower than in healthy persons.

Antibody Formation↗
PubMed1984

Antibody-induced conformational changes result in enhanced avidity of antibodies to different antigenic sites on the tick-borne encephalitis virus glycoprotein.

By the use of monoclonal antibodies we have recently defined eight distinct epitopes on the structural glycoprotein of tick-borne encephalitis (TBE) virus which differ with respect to location, function, or serological specificity (Heinz et al, Virology 126, 525-537, 1983). The present investigation reveals a complex network of interactions between antibodies directed against distinct nonoverlapping epitopes leading to enhanced binding of certain antibodies in the presence of bound second antibodies. The enhancement between antibody pairs can be either unidirectional or bidirectional. In addition, there are domains of predilection, which bind enhanceable antibodies (domain A) whereas others bind antibodies which preferentially induce enhancement (domain B). These domains represent structurally unrelated entities, domain A being sensitive to denaturation and fragmentation and domain B being resistant. Quantitative evaluation of binding data by Scatchard analysis revealed that the observed enhancement phenomenon is due to a two- to sixfold increase of antibody avidity. In the system described, enhancement of antibody binding is not dependent on antibody bivalency since it could also be demonstrated with purified Fab fragments acting either as enhanced or as enhancing antibody. It is therefore concluded that binding of antibodies to certain epitopes on the TBE virus glycoprotein induces conformational changes in distant parts of the molecule which can result in increased avidity of antibodies directed to conformationally changed epitopes. A possible explanation for the origin of this enhancement phenomenon is presented.

Antibodies, Monoclonal↗
PubMed1984

Immunogenicity of tick-borne encephalitis virus glycoprotein fragments: epitope-specific analysis of the antibody response.

After digestion with trypsin, alpha-chymotrypsin, or chemical cleavage using CNBr, fragments of the tick-borne encephalitis (TBE) virus glycoprotein were isolated which retained their reactivity with neutralizing monoclonal antibodies defining a denaturation-resistant antigenic domain. Upon immunization of mice, these fragments induced antibodies reactive with the immunizing peptide, the denatured glycoprotein and the native glycoprotein as a constituent of the whole virus. The immune sera revealed the same properties as the monoclonal antibodies that were used to select the fragments for immunization: neutralizing activity; haemagglutination-inhibiting activity; blocking of the binding of antibodies used for selection; enhancement of the binding of other monoclonal antibodies defining a denaturation-sensitive antigenic domain. It was shown that the natural immune response against certain functionally important, denaturation-resistant immunogenic domains on the native protein can be closely mimicked by immunization with defined protein fragments. Antigenic sites present on these fragments may therefore represent essential constituents of a synthetic vaccine. The fine specificities of antibody populations in anti-peptide or anti-protein immune sera were analysed on the basis of single antigenic determinants by blocking assays using radiolabelled monoclonal antibodies that define eight distinct epitopes on the TBE virus glycoprotein. Quantitative differences in the blocking of certain monoclonal antibodies were also observed between human convalescent sera. The establishment of such blocking profiles using a panel of well-characterized monoclonal antibodies may represent a general method for dissecting the specificities of antibody populations present in polyclonal immune sera and could allow investigations on determinant-restricted differences of immune responses and its possible implications for the course of the disease.

Animals↗
PubMed1984

Vitamin D, 25-hydroxy-vitamin D and 1,25-dihydroxy-vitamin D in cow's milk, infant formulas and breast milk during different stages of lactation.

Vitamin D and its metabolites were determined in cow's milk, infant formulas, and colostrum, transitional and mature breast milk by specific protein-binding assays following HPLC (high-pressure liquid chromatography). Cow's milk contains (mean +/- SEM) 50.4 +/- 4.1 pg/ml vitamin D (n = 10), 499 +/- 47 pg/ml 25-OH D (n = 10) and 9.7 +/- 1.0 pg/ml 1,25 (OH)2D (n = 3). 86.6% of the added vitamin D3 was recovered from infant formulas. The mean content (mean +/- SEM) of 25-OH D and 1,25(OH)2D of infant formulas are 299 +/- 35 pg/ml and 5.4 +/- 0.9 pg/ml (n = 9), respectively. Vitamin D concentration of colostrum and mature breast milk is 122 +/- 3.4 pg/ml (n = 7, mean +/- SEM) and 38 +/- 3.3 pg/ml (n = 9) respectively; the 25-OH D content increases from 294 +/- 50.6 pg/ml (n = 10) to 845 +/- 190 pg/ml (n = 14) during lactation. The increase of 1,25-(OH)2D from early to mature breast milk (3.2 +/- 0.6 pg/ml, n = 8 versus 5.3 +/- 0.7 pg/ml, n = 20) is still statistically significant.

Animals↗
PubMed1983

Location of immunodominant antigenic determinants on fragments of the tick-borne encephalitis virus glycoprotein: evidence for two different mechanisms by which antibodies mediate neutralization and hemagglutination inhibition.

A model showing the topological distribution, functions, and serological specificities of eight distinct, monoclonal antibody-defined epitopes on the tick-borne encephalitis (TBE) virus glycoprotein has been presented in a previous publication (F. X. Heinz, R. Berger, W. Tuma, and Ch. Kunz (1983). Virology 126, 525-537.) In the present report the influence of conformational change, chemical modification, and fragmentation on the antigenic reactivity of each epitope has been analyzed by the use of blocking enzyme immunoassays and "Western blotting." One of the two major antigenic domains (A), composed of three different epitopes, completely lost its antigenicity upon incubation at pH 5.0 or by treatment with guanidine-HCl/urea, SDS, reduction and carboxymethylation, as well as by proteolytic (trypsin, alpha-chymotrypsin, thermolysin) and chemical (CNBr) fragmentation. The second major antigenic domain (B), however, defined by four distinct monoclonal antibodies, three of which are hemagglutination (HA)-inhibiting, neutralizing, and protective, was shown to be resistant to low pH, guanidine-HCl/urea treatment, and proteolytic cleavage of the native protein. Also, polyclonal immune sera from mice and rabbits contained antibody populations reactive with antigenic determinants which are resistant and others which are sensitive to conformational change and fragmentation. Glycoprotein fragments with molecular weights of about 9000, generated by proteolysis of the native protein, were immunoreactive with neutralizing and protective monoclonal antibodies (defining domain B) as well as with a polyclonal mouse immune serum. Thus, these fragments appear to contain antigenic determinants which are immunodominant on the native protein and play an important role in the induction of a protective immune response against TBE virus. In addition, these results show that antibody binding to antigenic domains which are topologically and structurally completely unrelated may result in neutralization and/or HA inhibition. As the presence of two receptor-binding sites is unlikely, different effector mechanisms may account for the effects of these antibodies. The antigenic reactivity of domain A is sensitive to the same treatments which also inactivate HA activity of TBE virus, whereas domain B is resistant. These treatments include a change of domain A induced by incubation at slightly acidic pH which also results in inactivation of virus infectivity. Antibodies to domain A therefore presumably block viral activities by direct binding at or near the putative receptor-binding site whereas antibodies to domain B may cause loss of biological activities by inducing a conformational change of the receptor-binding site.

Antibodies, Monoclonal↗