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Biomedical subjects

C Kunz

Publications and source records attributed to C Kunz.

At least 55 records · Page 3Linked to original sources
PubMed1999

The msh2 gene of Schizosaccharomyces pombe is involved in mismatch repair, mating-type switching, and meiotic chromosome organization.

We have identified in the fission yeast Schizosaccharomyces pombe a MutS homolog that shows highest homology to the Msh2 subgroup. msh2 disruption gives rise to increased mitotic mutation rates and increased levels of postmeiotic segregation of genetic markers. In bandshift assays performed with msh2Delta cell extracts, a general mismatch-binding activity is absent. By complementation assays, we showed that S. pombe msh2 is allelic with the previously identified swi8 and mut3 genes, which are involved in mating-type switching. The swi8-137 mutant has a mutation in the msh2 gene which causes a truncated Msh2 peptide lacking a putative DNA-binding domain. Cytological analysis revealed that during meiotic prophase of msh2-defective cells, chromosomal structures were frequently formed; such structures are rarely found in the wild type. Our data show that besides having a function in mismatch repair, S. pombe msh2 is required for correct termination of copy synthesis during mating-type switching as well as for proper organization of chromosomes during meiosis.

Alleles↗
PubMed1999

Nutritional and biochemical properties of human milk, Part I: General aspects, proteins, and carbohydrates.

Human milk provided by healthy and well-nourished mothers is believed to cover the infant's nutrient requirements during the first half year of life. It is composed of a mixture of nutritive components as well as other bioactive factors with relevant physiologic effects in the neonate infant. Human milk composition has a dynamic nature and varies with time postpartum, during a nursing, and with the mother's diet and certain diseases. The changes of human milk composition with time of lactation seem to match the changing needs of the growing infant over time. Human milk proteins are a source of peptides, amino acids, and nitrogen for the infant, but also in the protein fraction reside other properties of human milk that may benefit the breastfeeding infant. Specific whey proteins are involved in the development of the immune response (immunoglobulins), whereas others participate in the nonimmunologic defense (lactoferrin). In addition, human milk contains a complex mixture of oligosaccharides that are present only in minute amounts in other mammal's milk. They may act as inhibitors of bacterial adhesion to epithelial surfaces, and thus play an important role in preventing infectious diseases in the newborn infant. Oligosaccharides may also promote the development of a so-called bifidus flora. In the next years, future research will lead to improved characterization of human milk components and elucidation of their individual mechanisms of action, which will increase our knowledge about the properties of human milk and the benefits of breastfeeding for the infant.

Female↗
PubMed1999

Nutritional and biochemical properties of human milk: II. Lipids, micronutrients, and bioactive factors.

Human milk lipids contain preformed LCPUFA in considerable amounts, which serve as precursors for the formation of prostaglandins, prostacyclins, and other lipid mediators, as well as essential components in membrane-rich tissues (such as the brain and the retina), thus affecting functional outcomes. Besides a balanced nutrient composition and a number of conditionally essential nutrients, human milk provides different types and classes of bioactive factors, such as enzymes, hormones, and growth factors, many of which appear to have a role in supporting infantile growth and development. The bioactive agents include antimicrobial factors (e.g., secretory IgA, oligosaccharides, FA); anti-inflammatory agents; transporters (e.g., lactoferrin); and digestive enzymes (e.g., BSSL). Several nonpeptide hormones (thyroid hormones, cortisol, progesterone, pregnanediol, estrogens, and artificial contraceptive) and peptide hormones and growth factors (erythropoietin, hHG, gonadotropin-releasing hormone, epidermal growth factor insulin, insulin-like growth factor-I, nerve growth factor, transforming growth factor-alpha, gastrointestinal regulatory peptides and thyroid-parathyroid hormones) have been isolated and quantitated in human milk. Some of these components are also involved in the maturation of the gastrointestinal tract of the infant. In addition to the passive benefits provided by human milk, several data support the hypothesis that breastfeeding promotes the development of the infant's own immune system, which might confer long-term benefits for the newborn infant. The risk of IDDM, Crohn's disease, and atopic disease is lower in individuals who had been breastfed during infancy. Areas of major interest in human milk research include the study of human milk synthesis and the contributions of dietary composition and maternal metabolism to human milk composition, infantile utilization of human milk components, and the study of bioactive components, such as oligosaccharides, proteins and peptides, and lipids and their in vivo fate and biologic effects in the recipient infant.

Female↗
PubMed1999

Repair of complex orbital fractures: technical problems, state-of-the-art solutions and future perspectives.

Within the wide range of severity of orbital fractures, the small group of complex fractures causes most of the sequelae. Therefore identification of severe injuries and adequate treatment is of major importance. The introduction of craniofacial techniques made possible a wide exposure of even large orbital wall defects and their reconstruction by grafts. In spite of significant progresses, repair of complex orbital wall defects remains a difficult surgical problem even for the experienced. This paper outlines the specific technical problems concerning surgical anatomy, exposure and defect reconstruction of this type of injuries. A number of new developments providing interesting future perspectives for orbital wall reconstruction such as intraoperative navigation, endoscopic techniques and new materials are discussed.

Animals↗
PubMed1998

The high mobility group domain protein Cmb1 of Schizosaccharomyces pombe binds to cytosines in base mismatches and opposite chemically altered guanines.

The mismatch-binding activity Cmb1 of Schizosaccharomyces pombe was enriched from wild type cells, and N-terminal sequencing enabled cloning of the respective gene. The deduced amino acid sequence of cmb1(+) contains a high mobility group domain, a motif that is common to a heterogeneous family of DNA-binding proteins. In crude protein extracts of a cmb1 gene-disruption strain, specific binding to C/T, C/A, and C/Delta was abolished. Weak binding to C/C revealed the presence of a second mismatch-binding activity, Cmb2. Cmb1, enriched from S. pombe and purified from Escherichia coli, bound specifically to C/C, C/T, C/A, T/T, and C/Delta but showed little or no affinity to other mismatches and small loops. Cmb1 recognizes 1,2 GpG intrastrand cross-links, produced by the chemotherapeutic drug cisplatin, when two cytosines are opposite the cross-linked guanines but not when other bases are present. Consistently, O6-methylguanine:C but not O6-methylguanine/T lesions were bound. Thus, cytosines in mismatches and opposite chemically modified guanines are the preferred target of Cmb1 recognition. cmb1 mutant cells are more sensitive to cisplatin than wild type cells, indicating a role of Cmb1 in repair of cisplatin-induced DNA damage.

Amino Acid Sequence↗
PubMed1998

Introduction of HIV-1 subtypes C, E and A into Austria.

BACKGROUND: Different subtypes of HIV-1 are prevalent in various geographical regions. Knowledge of their distribution is of importance with respect to possible differences in biological properties (such as reported for subtype E) as well as to diagnostic problems that may arise when specific subtypes are not recognized by standard serological assays. OBJECTIVES: The objectives of this study were to investigate the presence of the five major subtypes of HIV-1 (A-E) in the Austrian population and to estimate the prevalence of the individual subtypes in different risk groups. STUDY DESIGN: Serum samples from 88 HIV-1 positive patients were tested for the presence of subtype-specific antibodies using a peptide ELISA. RESULTS: The majority of the patients were shown to be infected with HIV-1 subtype B, but infections with subtypes A, C, and E were also detected in the Austrian population, primarily in the heterosexual transmission group. While subtypes A and C were probably imported from different African countries, subtype E appears to have been introduced by sex tourists returning from Thailand. CONCLUSION: Introduction of HIV subtypes other than B from Africa and Asia into Austria has already occurred and will certainly increase within the next few years.

Antibodies, Viral↗
PubMed1998

Glycosylphosphatidylinositol-anchored proteins in human and pig's milk.

Glycosylphosphatidylinositols (GPIs) are a recently discovered class of glycoconjugates that anchor either proteins, polysaccharides or small oligosaccharides to cellular membranes via a covalent linkage. To investigate the presence of soluble GPIs, individual human milk samples and mature pig's milk were defatted and casein removed by acid precipitation and ultracentrifugation. Soluble proteins were subjected to FPLC gel filtration (Superdex 200) and high molecular weight proteins were separated into fractions I-V. Immunological studies have been performed using Western blotting of whole milk, casein and whey fractions, and Superdex fractions I-V followed by incubation with a monoclonal antibody against the purified GPI anchor of the variant surface glycoprotein from Trypanosoma brucei brucei. We found that significant amounts of GPI-anchored proteins are secreted into human milk and pig's milk. The antibody which reacted only with components in the whey fractions bound to 5 different human milk proteins with a molecular weight of >/=200 (at least 3 components), 90 and 80 kD. In pig's milk, the staining pattern was found to be different from human milk. Similar to other GPI-anchored cell structures the functions of GPI-containing proteins in human milk and pig's milk as well as the specific components carrying these anchors remain to be investigated.

Animals↗
PubMed1997

Cooperation of two PEA3/AP1 sites in uPA gene induction by TPA and FGF-2.

We have previously shown in NIH 3T3 fibroblasts that treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) or fibroblast growth factor-2 (FGF-2) activates the Ras/Erk signaling pathway in NIH 3T3 fibroblasts, leading to the induction of the urokinase-type plasminogen activator (uPA) gene. In this study, we characterize cis-acting elements involved in this induction. DNase I hypersensitive (HS) site analysis of the uPA promoter showed that two regions were enhanced after TPA and FGF-2 treatment. One was located 2.4kb upstream of the transcription start site (-2.4kb), where a known PEA3/AP1 (AGGAAATGAGGTCAT) element is located. The other was located in a previously undefined far upstream region. Sequencing of this region revealed a similar AP1/PEA3 (GTGATTCACTTCCT) element at -6.9 kb corresponding to the HS site. Deletion analysis of the uPA promoter in transient transfection assays showed that both PEA3/AP1 elements are required for full inducibility, suggesting a synergism between the two elements. When the two sites were inserted together upstream of a minimal promoter derived from the thymidine kinase gene, expression of the reporter gene was more strongly induced by TPA and FGF-2 than with either of the two elements alone. Alone, the -6.9 element was more potent than the -2.4 element. The involvement of AP1 as well as Ets transcription factors was confirmed by examining different promoter constructs containing deletions in either the AP-1 or the PEA3 element, and by using an expression plasmid for dominant negative Ets-2. Electromobility shift analyses using specific antibodies showed that c-Jun and, JunD bind to both elements with or without induction. In addition, ATF-2 binds to the -2.4-kb element even without induction and c-Fos to the -6.9-kb element only after induction. Accordingly, overexpression of c-Fos caused induction from the -6.9-kb element, but reduced induction from the -2.4-kb element. The involvement of the Ets-2 transcription factor was shown by using expression plasmids for wild-type and dominant negative Ets-2.

3T3 Cells↗
PubMed1997

Silencing of transgenes introduced into leaves by agroinfiltration: a simple, rapid method for investigating sequence requirements for gene silencing.

Agroinfiltration--the infiltration of Agrobacterium tumefaciens into intact plant levels--provides a rapid and simple way of screening large numbers of transgene constructs for silencing in response to a resident transgene. Transgenic Nicotiana sylvestris plants homozygous for the tobacco class I chitinase A gene CHN48 under the control of the cauliflower mosaic virus 35S RNA promoter (P35S) show a high incidence of postranscriptional gene silencing. We forced suspensions of A. tumefaciens, carrying P35S-CHN48 in a binary Tiplasmid vector, into wild-type and transgenic N, sylvestris leaves with a blunt-tipped plastic syringe. The infiltrated CHN48 transgene was expressed in leaves transformed with the vector alone, but not in CHN48-transformed leaves showing the silent phenotype. In contrast, expression of a chimeric P35S-E. coli beta-glucuronidase gene (uidA) infiltrated into leaves was not affected by the presence of the CHN48 transgene stably integrated in the host genome. These results show that extra copies of CHN48 are silenced by resident, silent copies of the same gene and confirm that CHN48 silencing is not the result of promoter interactions. The results also suggest that silencing of the additional CHN48 copies does not require their integration into chromosomes.

Agrobacterium tumefaciens↗
PubMed1997

[EMLA for anesthesia of puncture sites for large lumen indwelling venous catheters for autologous plasma and erythrocyte concentrate donation].

OBJECTIVE: The analgetic effect of EMLA-Creme (Lidocaine-Prilocaine-Cream) was studied in 52 patients undergoing preoperative autologous blood and/or plasma donation. METHOD: 95 venous punctures were performed with a 18 G or 16 G cannula. Puncture pain was estimated by the patients using a visual analog painscore (VAS 0-100). The data were evaluated regarding reaction time, puncture spot and cannula diameter. RESULTS: Within 15 minutes we find a clear reduction of puncture pain. The diameter of the cannula does not correlate with the painscore. Puncture of hand-back veins seems to be more painful than cubital vein puncture. CONCLUSION: The application of EMLA-Creme results in an effective analgesia for venous puncture. 37% of our patients were punctured without any pain and 67% felt a tolerable pain (VAS: 0-10).

Anesthetics, Local↗
PubMed1997

Safety and immunogenicity of live oral cholera and typhoid vaccines administered alone or in combination with antimalarial drugs, oral polio vaccine, or yellow fever vaccine.

The effects of concomitant administration of antimalarial drugs, oral polio vaccine, or yellow fever vaccine on the immune response elicited by the Vibrio cholerae CVD103-HgR and Salmonella typhi Ty21a live oral vaccines were investigated. Healthy adults were immunized with CVD103-HgR alone or combined with Ty21a. Subjects were randomized to simultaneously receive mefloquine, chloroquine or proguanil, or oral polio or yellow fever vaccine. The vibriocidal antibody seroconversion rate was significantly reduced (P = .008) only in the group that received chloroquine with the CVD103-HgR. The geometric mean vibriocidal antibody titer was significantly decreased in the groups that received chloroquine (P = .001) or mefloquine (P = .02) compared with titers in groups that received CVD103-HgR alone. However, similar immunosuppressive effects were not observed in the groups immunized with Ty21a and CVD103-HgR. Only the concomitant administration of proguanil effected a significant (P = .013) decline in the anti-S. typhi lipopolysaccharide antibody response. These results indicate that chloroquine and proguanil should not be simultaneously administered with the CVD103-HgR and Ty21a vaccine strains, respectively.

Administration, Oral↗
PubMed1997

Characterization of monoclonal antibody-escape mutants of tick-borne encephalitis virus with reduced neuroinvasiveness in mice.

Escape mutants of tick-borne encephalitis (TBE) virus were selected using neutralizing monoclonal antibodies (MAbs) that react with three different and previously unrecognized epitopes in the envelope protein E of TBE virus. Two of these variants (V-IC3 and V-IE3) exhibited a significantly reduced reactivity with their selecting MAbs, as determined by ELISA, whereas with one variant (V-IO3), reactivity was completely unchanged. Comparative sequence analyses demonstrated that each of the variants differed from the wild-type virus by a single amino acid substitution located at exposed positions within domains I, II and III of protein E. In the mouse model, all three mutants were still neuro-virulent but exhibited a significantly reduced neuro-invasiveness after subcutaneous inoculation. Virus replication, however, was sufficient to induce a specific antibody response. The observed alterations in virulence properties were not associated with reduced growth rates in vertebrate cell cultures, but one variant (V-IE3) exhibited a small plaque phenotype. The mutation of variant V-IO3 resulted in a temperature-sensitive phenotype and a significant elevation of the pH-threshold of the conformational change necessary for fusion activity.

Animals↗
PubMed1997

Infectious cDNA clones of tick-borne encephalitis virus European subtype prototypic strain Neudoerfl and high virulence strain Hypr.

Infectious cDNA clones of two strains of tick-borne encephalitis (TBE) virus, i.e. European subtype prototypic strain Neudoerfl and the closely related but more virulent strain Hypr, were constructed. The recombinant constructs consisted of cDNAs stably inserted into the bacterial plasmid pBR322 under the control of T7 promoter elements. The genome of TBE virus strain Neudoerfl was successfully cloned, both as a full-length cDNA and as two partial cDNAs. In the case of strain Hypr, the genome is represented by two cDNA clones corresponding to the 5'- and 3'-terminal halves of the genome. Highly infectious RNAs can be produced from the full-length cDNA clone or from the partial clones ligated in vitro to form full-length cDNA templates prior to T7 transcription. The biological properties of the recombinant progeny viruses, including virulence characteristics, were indistinguishable from the corresponding parent virus strains. Thus, the described infectious cDNA clones represent a useful and reliable experimental system for the specific mutagenesis of TBE virus.

Animals↗
PubMed1997

Alkali therapy versus sodium chloride supplement in low birthweight infants with incipient late metabolic acidosis.

Two hundred and eighty-two patients with birthweights below 2.0 kg were routinely screened for spontaneous development of maximum renal acid stimulation (urine-pH < 5.4). Sixty episodes in 53 patients of incipient late metabolic acidosis (urine pH < 5.4 on 2 consecutive days) were randomly allocated to oral therapy with 2 mmol/kg/day of either NaHCO3 or NaCl for 7 days. All 27 patients on NaHCO3 therapy, but only 15 from 26 patients on NaCl therapy, showed an increase in urine pH values, combined with a relatively high gain in body weight and a tendency to increased N-assimilation. Eleven patients on NaCl therapy showed persistent maximal renal acid stimulation on all 7 days with possibly lower weight gain and no clear change in N-assimilation. Thus, in patients with incipient late metabolic acidosis, NaCl therapy is not as beneficial as NaHCO3 therapy.

Acidosis, Renal Tubular↗
PubMed1996

High-pH anion-exchange chromatography with pulsed amperometric detection and molar response factors of human milk oligosaccharides.

A method is described to separate and characterize neutral and acidic lactose-derived oligosaccharides without prior derivatization or reduction by high-pH anion-exchange chromatography and pulsed amperometric detection (HPAEC-PAD). This method has been applied to human milk oligosaccharides from donors with different blood group specificity (A, Le(a) and A, Le(b). Neutral and acidic components were separated from each other by anion-exchange chromatography. A distinct separation of individual components was obtained by size-exclusion chromatography on Fractogel TSK HW 50S (acidic oligosaccharides) or Fractogel TSK HW 40S (neutral oligosaccharides containing up to 6 monomers) and Bio-Gel P-4 size exclusion (neutral oligosaccharides containing more than 6 monomers). Furthermore the moral response factors after HPAEC-PAD have been determined for 28 components.

Carbohydrate Sequence↗
PubMed1996

Correlation between ELISA, hemagglutination inhibition, and neutralization tests after vaccination against tick-borne encephalitis.

The significance of IgG antibody levels determined by a binding assay (ELISA) was investigated as a surrogate marker for the presence of neutralizing and hemagglutination inhibiting antibodies in sera from individuals vaccinated against tick-borne encephalitis (TBE). To assess the extent of interference by flavivirus cross-reactive antibodies, sera from persons with a proven or suspected history of other flavivirus infections and/or vaccinations were also examined. An excellent and highly significant correlation was found between ELISA IgG units and the antibody titers obtained by the hemagglutination inhibition (HI) as well as by the neutralization test (NT), provided that there was no other exposure to flavivirus antigens except TBE vaccination. Yellow fever vaccination and/or dengue virus infections induced significant levels of antibodies reactive in the TBE ELISA and HI test, which did not exhibit, however, neutralizing activity against TBE virus. The phenomenon and problem of "original antigenic sin" was demonstrated in a TBE vaccinee with a history of previous flavivirus infections. TBE vaccination first induced a booster reaction resulting in a rise in the level of cross-reactive antibodies only, whereas TBE virus-neutralizing antibodies became detectable only after the third vaccination. It is concluded that the level of IgG antibodies determined by ELISA is a good marker for predicting the presence of neutralizing antibodies after TBE vaccination, but only in the absence of flavivirus cross-reactive antibodies. Otherwise, a neutralization assay is necessary for assessing immunity.

Animals↗
PubMed1996

[Structural and functional aspects of oligosaccharides in human milk].

About a century ago, pediatricians observed that in feces of breast-fed infants, compared to those of bottle-fed infants, Bifidobacterium bifidum was the predominant microorganism. It was shown thereafter that aminosugar-containing oligosaccharides are growth factors for a specific strain of Bifidobacterium. Meanwhile, more than 130 lactose-derived oligosaccharides have been identified in human milk. Some of these oligosaccharides like Lacto-N-Tetraose and Lacto-N-Fucopentaose I and II do not occur in minute amounts but in concentrations up to 1-2 g/L. As the total amount of complex oligosaccharides is between 3-6 g/L those components have to be considered as major human milk constituents. There is striking evidence that human milk oligosaccharides are potent inhibitors of bacterial adhesion to epithelial surfaces, an initial stage of infective processes. Therefore, these oligosaccharides are considered to be soluble receptor analogues of epithelial cell surfaces participating in the non-immunological defense system of human milk-fed infants.

Bifidobacterium↗