PubMed Health⌕ Search

Biomedical subjects

N Schmeer

Publications and source records attributed to N Schmeer.

At least 19 recordsLinked to original sources
PubMed2000

Poxvirus-induced immunostimulating effects on porcine leukocytes.

The prophylactic application of inactivated parapox ovis viruses (Baypamun; Bayer AG, Leverkusen, Germany) has been shown to reduce efficiently the outbreak of stress-mediated diseases in different species. However, little is known about the basic mechanism behind this observed stimulatory property. We therefore tested eight inactivated poxvirus strains belonging to three different genera (Orthopoxvirus, Avipoxvirus, and Parapoxvirus) for their capacity to activate cells of the porcine innate and specific immune systems in vitro. The results indicated that poxviruses failed to induce increased phagocytosis, oxidative burst, or natural killer cell activity in swine. In contrast, enhanced release of interleukin-2, alpha interferon, and gamma interferon, as well as strong proliferation, could be measured. Flow cytometric analyses and cell sorting experiments identified T-helper cells as the main target responding to inactivated poxviruses: the activated cells had a CD4(high) CD25(+) major histocompatibility complex type II-positive phenotype and were the major source of secreted cytokines. Together, the results demonstrated that all tested poxviruses possessed immunostimulating capacity. These in vitro poxvirus-induced effects may be responsible at least in part for the in vivo immunostimulating capacity of inactivated poxviruses.

Animals↗
PubMed1998

Synthesis and antibacterial in vitro activity of novel analogues of nematophin.

The synthesis and in vitro antibacterial activity of new derivatives and analogues of nematophin are described. It was shown that the unsubstituted amide NH-group is essential for bioactivity. Alkyl- or arylsubstitution at the 1-position results in a distinct increase of antibacterial activity. Addition of protein (blood or serum) to the culture media reduces the inhibitory activity on bacteria.

Anti-Bacterial Agents↗
PubMed1998

Compensation of preliminary blood phagocyte immaturity in the newborn calf.

To estimate the functional maturity of the phagocytic defence in neonatal calves, we analyzed the characteristics of blood phagocytes from calves (n = 10) 1 h post partum (p.p.) and 4 h p.p. At 1 h p.p., all calves were colostrum-deprived, while 5 calves had received colostrum before the 4 h p.p. sampling. The results were compared to those obtained from 3-9-week-old calves (n = 10). Phagocytic and oxidative burst activity of polymorphonuclear leukocytes (PMNL) and monocytes were determined in whole blood and separately analyzed by flow cytometry. In neonates prior to colostrum ingestion (1 h p.p.), phagocytic activity of PMNL against non-preopsonized E. coli was lower when compared to PMNL of 3-9-week-old calves. Opsonization of bacteria with pooled plasma from adult animals only partially restituted this lower PMNL phagocytic activity, indicating that humoral as well as cellular aspects of PMNL phagocytosis are altered in neonatal calves. In contrast to PMNL, monocytes of neonates exhibited an enhanced phagocytic activity. The oxidative burst activity of PMNL, as well as of monocytes was higher in newborn calves. During the first 4 h of life, the activities of blood phagocytes changed. Colostrum ingestion was accompanied by an increase in the percentage of phagocytizing PMNL and monocytes. This increase was absent in colostrum-deprived calves. In contrast, the oxidative burst activity of phagocytes decreased with age. In monocytes, the decrease of oxidative burst activity was only observed in colostrum-fed calves. In conclusion, some blood phagocyte functions in calves were found to be immature at birth, but these functions are presumably compensated by high absolute PMNL numbers and by other the more active mechanisms.

Aging↗
PubMed1998

Isolation of a cytopathogenic virus from a case of porcine reproductive and respiratory syndrome (PRRS) and its characterization as parainfluenza virus type 2.

From a lung of a fetus of a breeding sow showing PRRS-like symptoms a viral agent could be isolated. It was characterized as an enveloped, hemagglutinating RNA virus. Ultrastructural examination of purified virus revealed paramyxovirus-like pleomorphic virions of approx. 200 nm in diameter. The helical nucleocapsids were about 18 nm in diameter. The virus was found to be antigenically related to simian virus 5 (SV5) a prototype strain of parainfluenza virus type 2, but not to bovine respiratory syncytial virus, parainfluenza virus type 1, parainfluenza virus type 3, and Newcastle disease virus as determined by western blot analysis.

Animals↗
PubMed1997

Genomic (5'UTR) and serological differences among German BVDV field isolates.

Isolates of bovine viral diarrhoea virus (BVDV) collected in Germany were examined for their genomic heterogeneity in sequences from the 5'untranslated region (UTR) of the viral genome. Polymerase chain reaction (PCR) tests based on the 5'UTR and the region coding for the NS2-3/4A polypeptide were used to differentiate between BVDV I and BVDV II genotypes. Eleven out of 96 BVDV-isolates were identified as BVDV II. Virus neutralization tests with BVDV I- or II-specific antisera raised in cattle were done. The mean titers were reduced by 7.2-fold (BVDV I-antiserum versus type II-isolates) or 35-fold (BVDV II-antiserum versus type I-isolates) when using the respective heterologous virus.

Animals↗
PubMed1997

Analysis of immunoglobulin classes and subclasses in response to infection of Balb/cJ and C57BL/6J mice with Coxiella burnetii.

In order to establish defined immunological parameters for Q fever infection models, a microtitre enzyme-linked immunosorbent fluorescence assay (ELISA) was used for the first time to analyse the humoral immune response of Balb/cJ and C57BL/6J mice after experimental infection with Coxiella burnetii strain 'Nine Mile' in phase I. The experimental infection evoked a seroconversion in all mice within 10 days. Typically, the immune response measured against the whole-cell antigen showed an early increase of immunoglobulin (Ig) M followed by a later increase of the IgG subclasses. The IgA was low during the entire investigation period. Within the IgG subclasses only IgG2a and IgG2b gained higher values, whereby C57BL/6J mice produced high IgG2b titres and significantly lower IgG2a titres. In contrast, Balb/cJ mice developed IgG2a and IgG2b at equal levels. The use of partial antigens of C. burnetii demonstrated that the dominating IgG2b reaction of the C57BL/6J mice was directed against the lipopolysaccharide (LPS) of C. burnetii. This reaction was almost absent in Balb/cJ mice. In contrast, the SP27 protein antigen did not evoke different IgG2b reactions within the two breeds. No significant influence was observed within the two breeds in regard to sex or between hormone synchronized and non-hormone synchronized animals.

Animals↗
PubMed1997

The use of Baypamun N in crowding-associated infectious respiratory disease: efficacy of Baypamun N (freeze dried product) in 2-week-old veal calves.

The efficacy of an immunomodulator, Baypamun N, was tested in 10-20-day-old veal calves from different farms, which were exposed to stress by transport and commingling (crowding). Verum and placebo animals (n = 50, each group) received three intramuscular injections of the investigational products (days 0, 2, 4) starting the day of arrival on the farm. Data from 49 calves in each group could be used for statistical evaluation. The incidence of acute bovine respiratory disease was anticipated to be high during the first 2 weeks after arrival on farm based on experience from other years. The clinical scores in the Baypamun N group were significantly reduced by 52.7% (P < 0.001) compared to the placebo group. The number of antibiotic treatments was significantly reduced by 53.8% (P < 0.001) in the Baypamun N group. Of the calves treated with Baypamun N, 51.02% remained untreated with antibiotics during the first 2 weeks after arrival on the farm compared with only 16.3% of the placebo treated control calves (P < 0.001).

Adjuvants, Immunologic↗
PubMed1997

The use of Baypamun N in crowding associated infectious respiratory disease: efficacy of Baypamun N (freeze dried product) in 4-10 month old horses.

The efficacy of an immunomodulator, Baypamun N, was tested in 4-10-month-old horses which were exposed to stress by weaning, transport and commingling with yearlings from different breeders (crowding). Verum (n = 26) and placebo animals (n = 27) received three intramuscular injections of the investigational preparations (days 0, 2, 9) starting at the day of commingling in one stable. The incidence of acute respiratory disease was high during the first 4 weeks after commingling. Approximately 50% of all horses showed seroconversion due to field infection by EHV1 and EHV4 during the observation period. The clinical scores in the Baypamun N group were significantly reduced by 40.3% (P < 0.05) compared to the placebo group. The proportion of horses with purulent nasal discharge during the observation period (4 weeks) was also significantly reduced by 58.7% (P < 0.01) in the Baypamun N group. Fifty per cent of the horses injected with Baypamun N showed no purulent nasal discharge and therefore no signs of complicated disease of the upper respiratory airways in contrast to only 14.8% in the non-protected placebo group. The challenge conditions studied in this investigation were rather severe because of the permanent exposure of Baypamun N treated individuals to the non-separated and untreated horses (n = 51). This indicates that treatment with Baypamun N is a successful tool to avoid severe clinical consequences of stress in young horses.

Acute Disease↗
PubMed1997

Comparative susceptibilities of various animal-pathogenic mycoplasmas to fluoroquinolones.

The in vitro activities of six antimicrobial agents were tested against 162 mycoplasma strains of eight species isolated from poultry and livestock at different geographic sites. Tiamulin was most active (MICs at which 90% of the isolates were inhibited [MIC90s], 0.025 to 0.25 microg/ml); enrofloxacin and danofloxacin had near equivalent activities (MIC90s, 0.05 to 1.0 microg/ml), but were much more active than flumequine (MIC90s, 1 to 50 microg/ml). The MIC90s of tylosin and oxytetracycline were 0.25 to > 100 microg/ml and 0.25 to 100 microg/ml, respectively.

Animals↗
PubMed1997

Degradation of the fluoroquinolone enrofloxacin by the brown rot fungus Gloeophyllum striatum: identification of metabolites.

The degradation of enrofloxacin, a fluoroquinolone antibacterial drug used in veterinary medicine, was investigated with the brown rot fungus Gloeophyllum striatum. After 8 weeks, mycelia suspended in a defined liquid medium had produced 27.3, 18.5, and 6.7% 14CO2 from [14C]enrofloxacin labeled either at position C-2, at position C-4, or in the piperazinyl moiety, respectively. Enrofloxacin, applied at 10 ppm, was transformed into metabolites already after about 1 week. The most stable intermediates present in 2-day-old supernatants were analyzed by high-performance liquid chromatography combined with electrospray ionization mass spectrometry. Eight of 11 proposed molecular structures could be confirmed by 1H nuclear magnetic resonance spectroscopy or by cochromatography with reference compounds. We identified (i) 3-, 6-, and 8-hydroxylated congeners of enrofloxacin, which have no or only very little residual antibacterial activity; (ii) 5,6- (or 6,8-), 5,8-, and 7,8-dihydroxylated congeners, which were prone to autoxidative transformation; (iii) an isatin-type compound as well as an anthranilic acid derivative, directly demonstrating cleavage of the heterocyclic core of enrofloxacin; and (iv) 1-ethylpiperazine, the 7-amino congener, and desethylene-enrofloxacin, representing both elimination and degradation of the piperazinyl moiety. The pattern of metabolites implies four principle routes of degradation which might be simultaneously employed. Each route, initiated by either oxidative decarboxylation, defluorination, hydroxylation at C-8, or oxidation of the piperazinyl moiety, may reflect an initial attack by hydroxyl radicals at a different site of the drug. During chemical degradation of [4-14C]enrofloxacin with Fenton's reagent, five confirmatory metabolites, contained in groups i and iv, were identified. These findings provide new evidence in support of the hypothesis that brown rot fungi may be capable of producing hydroxyl radicals, which could be utilized to degrade wood and certain xenobiotics.

Anti-Infective Agents↗
PubMed1997

Evidence for numerous omp1 alleles of porcine Chlamydia trachomatis and novel chlamydial species obtained by PCR.

A nested PCR for genus-specific amplification of the Chlamydia omp1 locus was established. This PCR detected single template molecules in 200-microl specimen aliquots. Amplified chlamydial omp1 alleles were typed by heminested species PCRs and allele PCRs. We applied this method to 407 specimens from several host animals with various clinical conditions, and we detected prevalences of chlamydiae from 6 to 50%. Amplicons from peacock enteritis and equine infertility specimens were not typeable according to present omp1 allelic criteria for the chlamydial species. DNA sequencing revealed novel omp1 alleles which were 29.9 and 47.6% divergent in the deduced peptide sequences from the most closely related chlamydiae. Phylogenetic reconstruction indicated segregation of these alleles from the current four chlamydial species (90 and 97% bootstrap support), thus strongly suggesting the existence of additional chlamydial species. Allele typing of amplicons from swine with intestinal, urogenital, and respiratory infections demonstrated several unique omp1 allelic variants of Chlamydia trachomatis. These novel alleles had deduced peptide sequences which were 11.6 to 19% divergent from porcine C. trachomatis S45. Mutations were clustered in the C-terminal region of variable segment IV of the omp1 locus encoding subspecies and serovar determinants of the chlamydial major outer membrane protein, thus implying that there are numerous serovars of porcine C. trachomatis. These results demonstrate the need for routine application of sensitive genus-specific detection of chlamydiae in animal specimens and suggest a more prominent role than anticipated for chlamydiae in animal diseases.

Alleles↗
PubMed1997

Use of synthetic antigens improves detection by enzyme-linked immunosorbent assay of antibodies against abortigenic Chlamydia psittaci in ruminants.

Synthetic peptide antigens were prepared for use in enzyme-linked immunosorbent assays (ELISAs) to detect serum antibodies against abortigenic strains of Chlamydia psittaci in livestock. Peptide antigens were identified with C. psittaci B577-immune sera by solid-phase scanning of overlapping octapeptides of variable domains (VDs) of the major outer membrane protein of C. psittaci serovar 1 (omp1 type C. psittaci B577). Two VD 4 regions and one VD 2 region were strongly reactive with all C. psittaci B577 antisera. Peptides encompassing these regions were synthesized with biotin and a serine-glycine-serine-glycine spacer at the N terminus and were attached to streptavidin-coated microtiter plates. In direct ELISAs with these plates, the synthetic peptides reacted with C. psittaci B577 antisera, but not with sera from specific-pathogen-free animals. Serum specimens from 40 sheep and 40 cattle, obtained from herds with abortion problems, were screened for antibodies by these C. psittaci B577 peptide ELISAs and an ELISA with recombinant, genus-specific Chlamydia lipopolysaccharide (LPS) antigen. Results from these newly developed ELISAs were compared to those from the reference C. psittaci B577 elementary body (EB) ELISA and the Chlamydia complement fixation test (CFT). The C. psittaci B577 peptide ELISAs, the LPS ELISA, and the EB ELISA correctly identified the presence or absence of antibodies against chlamydiae in all sheep and bovine sera. The Chlamydia CFT, which is the most widely accepted serodiagnostic method for chlamydial infections in animals, correctly identified the presence or absence of antibodies against chlamydiae in only 78 and 4.9% of sheep and bovine sera, respectively. These results suggest that the C. psittaci B577-peptide and Chlamydia LPS ELISAs are superior for the serodiagnosis of ruminant infections with abortigenic chlamydiae, since they are more sensitive than the CFT, they are easy to standardize, and they use readily available synthetic antigens instead of organism-derived CFT antigen.

Animals↗
PubMed1997

Chlamydiae in porcine abortion.

Formalin-fixed, paraffin-embedded fetal livers and lungs from 139 cases of swine abortion were investigated retrospectively for chlamydiae by means of immunohistochemistry. Using a genus-specific antibody, chlamydial antigen was found in eight livers obtained from five (3.6%) abortion cases from different herds. All lung sections were negative. Chlamydiae were also labeled in five of the eight positive livers using a monoclonal antibody against immunotype 1 of Chlamydia psittaci; the remaining three livers were negative. No reactivity was seen using an antibody specific for C. trachomatis. Chlamydiae should be considered a cause of abortion in sows in Switzerland. Porcine abortigenic strains identified in this study differed immunologically from intestinal strains (known to be mainly C. trachomatis) but shared similarities with abortigenic chlamydiae of ruminants.

Abortion, Septic↗
PubMed1996

A gE deleted infectious bovine rhinotracheitis marker vaccine for use in improved bovine herpesvirus 1 control programs.

Based on a glycoprotein E (gE) deleted bovine herpesvirus 1 (BHV1) strain (Kaashoek et al., 1994) a killed virus as well as a modified live virus marker vaccine have been developed that allow differentiation between immunized and BHV1 infected cattle. Safety and efficacy of both vaccines were tested extensively following the current European Union (EU) requirements for the development of bovine vaccines. The minimum vaccine dose, vaccination regimen, route of administration and duration of immunity were evaluated for both vaccines in comprehensive vaccination/challenge trials in cattle. The most potent adjuvant formulation for the killed virus vaccine was also selected by experimental challenge infections. For the modified live virus marker vaccine it could be demonstrated that maternally derived BHV1 specific antibodies did not interfere with vaccination. Safety could be demonstrated for both the killed virus and the modified live virus vaccine in all target animal categories including veal calves, beef cattle, bulls, heifers and dairy cattle, including pregnant animals.

Animals↗
PubMed1996

Degradation of the fluoroquinolone enrofloxacin by wood-rotting fungi.

The veterinary fluoroquinolone enrofloxacin was degraded in vitro by four species of wood-rotting fungi growing on wetted wheat straw containing carbonyl-14C-labeled drug. A maximum 14CO2 production of 17% per week was observed with the brown rot fungus Gloeophyllum striatum, resulting in up to 53% after 8 weeks. However, rates reached at most 0.2 and 0.9% per week, if enrofloxacin was preadsorbed to native or gamma ray-sterilized soil, respectively.

Adsorption↗
PubMed1995

Safety aspects in the development of an infectious bovine rhinotracheitis marker vaccine.

Clinical trials in cattle demonstrated that the IBR marker modified live vaccine based on the gE-deleted IBR strain Difivac is immunogenic and safe for bovines of all ages. Potential effects of the vaccine virus have also been tested in swine and sheep and proved safe for these species as well. For evaluation of other environmental aspects, the spread of the vaccine virus after immunisation was investigated. The data indicated that the vaccine virus may be shed by immunised animals but that it has a limited ability to pass from animal to animal. It was also demonstrated that the attenuated Difivac strain does not revert to virulence during calf passage. Preliminary results indicated that the gE-deleted vaccine virus of the IBR marker vaccine cannot be reactivated after dexamethasone treatment, an important advantage for a vaccine strain. Furthermore, immunisation with the Difivac strain reduced the ability of a superinfecting challenge virus to become latent or to be reactivated.

Animals↗
PubMed1993

Spread and distribution of Coxiella burnetii in C57BL/6J (H-2b) and Balb/cJ (H-2d) mice after intraperitoneal infection.

Spread and distribution of Coxiella burnetii were investigated immunocytochemically and antigen dissemination was correlated with light microscopic alterations in Balb/cJ (H-2d) and C57BL/6J (H-2b) mice. Intraperitoneal inoculation of C. burnetii resulted in a self-limiting systemic infection. Gross findings consisted of hepatosplenomegaly and histological lesions were characterized by microabscesses and granulomas in numerous organs including spleen, liver, mesentery, bone marrow, lymph nodes, pancreas, heart and uterus. In addition, splenic lymphoid depletion, venous microthrombi and reduction of bone marrow cells were observed. Coxiella burnetii antigen was demonstrated immunocytochemically in the aforementioned organs, especially in spleen, liver and most of all in the bone marrow. Coxiella antigen was detected in macrophages, macrophage precursor cells, and occasionally endothelial cells. Numerous C. burnetii antigen-positive cells were observed between 5 and 12 days post-infection; thereafter, the amount of C. burnetii antigen decreased rapidly. Immunopositivity was detectable until 30 and 44 days post-infection in the bone marrow of Balb/cJ and C57BL/6J mice, respectively. Severity of histological lesions was associated with presence and clearance of C. burnetii antigen. Specific IgM antibodies were detected 4 days after infection and IgG seroconversion was noticed 7 to 10 days post-infection. Coxiella burnetii-specific IgM and IgG antibodies were still present 150 days after infection. Significant strain-specific differences in the antibody response were not found. The findings demonstrate systemic spread of C. burnetii, especially to bone marrow, spleen and liver, and antigen distribution was closely correlated with the appearance and degree of histological lesions.

Animals↗