Biomedical subjects

Heinrich Neubauer

Publications and source records attributed to Heinrich Neubauer.

33 records · Page 2Linked to original sources

PubMed2005

Identification of brucella species and biotypes using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

Brucellosis is a worldwide zoonosis causing reproductive failures in livestock and a severe multi-organ disease in humans. The genus Brucella is divided into seven species and various biotypes differing in pathogenicity and host specificity. Although Brucella spp. represent a highly homogenous group of bacteria, RFLPs of selected genes display sufficient polymorphism to distinguish Brucella species and biovars. PCR-RFLP analysis shows excellent typeability, reproducibility, stability, and epidemiological concordance. Consequently, PCR-RFLP assays of specific gene loci can serve as tools for diagnostic, epidemiological, taxonomic, and evolutionary studies. Various PCR-RFLPs used for the identification of Brucella species and biotypes are reviewed.

Bacterial Outer Membrane Proteins↗

PubMed2005

Yersinia aleksiciae sp. nov.

Yersinia kristensenii consists of phenotypically heterogeneous strains. This is reflected by the existence of strains with various multilocus enzyme electrophoresis and 16S rRNA gene sequence types. Strains originally phenotyped as members of Y. kristensenii were studied using 16S rRNA gene sequencing, DNA-DNA hybridization, determination of the DNA base composition and various phenotypic tests. The results were compared to those of Yersinia type strains. Based on levels of DNA-DNA relatedness, a specific 16S rRNA gene sequence type and the presence of lysine decarboxylase activity, a novel species, Yersinia aleksiciae sp. nov., is proposed. The type strain is Y159(T) (=WA758(T)=DSM 14987(T)=LMG 22254(T)).

Animals↗

PubMed2004

Evaluation of a standardized F1 capsular antigen capture ELISA test kit for the rapid diagnosis of plague.

Rapid detection of soluble F1 capsular antigen in serum, bubo fluid or urine of patients proved to be a valuable tool in the presumptive diagnosis of plague. We evaluated a F1 capsular antigen capture ELISA resembling a commercially available test kit. The minimal detectable concentration was 4 ng/ml. The specificity was 100% when investigating 47 sera from healthy Malagasy subjects and 98.4% when 365 sera from German blood donors were studied. Sensitivity was determined on sera (n=11) and buboes (n=18) from bacteriologically confirmed Malagasy plague patients. Sensitivity was 90.1% for serum and 100% for buboes. A standardized F1 capsular antigen capture ELISA test kit might be well suited for the early detection of plague particularly in non-endemic areas where clinical microbiological laboratories have only limited access to alternative techniques for rapid identification of Yersinia pestis.

Antibodies, Monoclonal↗

PubMed2004

Towards a unifying basis of auditory thresholds: the effects of hearing loss on temporal integration reconsidered.

For signal detection and identification, the auditory system needs to integrate sound over time. It is frequently assumed that the quantity ultimately integrated is sound intensity and that the integrator is located centrally. However, we have recently shown that absolute thresholds are much better specified as the temporal integral of the pressure envelope than of intensity, and we proposed that the integrator resides in the auditory pathway's first synapse. We also suggested a physiologically plausible mechanism for its operation, which was ultimately derived from the specific rate of temporal integration, i.e., the decrease of threshold sound pressure levels with increasing duration. In listeners with sensorineural hearing losses, that rate seems reduced, but it is not fully understood why. Here we propose that in such listeners there may be an elevation in the baseline above which sound pressure is effective in driving the system, in addition to a reduction in sensitivity. We test this simple model using thresholds of cats to stimuli of differently shaped temporal envelopes and durations obtained before and after hearing loss. We show that thresholds, specified as the temporal integral of the effective pressure envelope, i.e., the envelope of the pressure exceeding the elevated baseline, behave almost exactly as the lower thresholds, specified as the temporal integral of the total pressure envelope before hearing loss. Thus, the mechanism of temporal integration is likely unchanged after hearing loss, but the effective portion of the stimulus is. Our model constitutes a successful alternative to the model currently favored to account for altered temporal integration in listeners with sensorineural hearing losses, viz., reduced peripheral compression. Our model does not seem to be at variance with physiological observations and it also qualitatively accounts for a number of phenomena observed in such listeners with suprathreshold stimuli.

Animals↗

PubMed2004

Development of 5' nuclease real-time PCR assays for the rapid identification of the burkholderia mallei//burkholderia pseudomallei complex.

Burkholderia pseudomallei is the causative agent of melioidosis and was classified as a biologic agent by the Centers for Disease Control and Prevention (Atlanta, GA). Acute melioidosis has a case fatality rate of >40%, and septicemia is fatal in up to 90%. The aim of the study was to design 5'-nuclease real-time PCR assays for the rapid and reliable identification of the B. mallei/B. pseudomallei complex. Real-time PCR assays using TaqMan probes targeting the 16S rDNA and fliC were developed on an ABI Prism 7000 sequence detection system (Applied Biosystems, Foster City, CA). Specificity was assessed with 64 B. pseudomallei, nine B. mallei, 126 other Burkholderia strains of 29 species, and 45 clinically relevant non-Burkholderia organisms. Sensitivity, specificity, and positive and negative predictive value of the assays were 100%. Discrimination between B. pseudomallei and B. mallei, an organism which can be regarded as a clone of B. pseudomallei, could not be achieved. A probit analysis revealed that 7.5 and 52 genome equivalents (GE) of B. pseudomallei could be detected using the fliC and the 16S rDNA assays (P = .05), respectively. In spiked blood samples, the detection limit was approximately 300 and 3.000 GE for fliC and the 16S rDNA, respectively. In conclusion, we recommend the simultaneous use of the 16S rDNA and fliC real-time PCR assays for the rapid and specific identification of the B. mallei/B. pseudomallei complex in positive blood cultures or from suspicious bacterial colonies allowing the early onset of appropriate antibiotic therapy.

Animals↗

PubMed2004

Structural organization of the pFra virulence-associated plasmid of rhamnose-positive Yersinia pestis.

The 137,036-bp plasmid pG8786 from rhamnose-positive Yersinia pestis G8786 isolated from the high mountainous Caucasian plague focus in Georgia is an enlarged form of the pFra virulence-associated plasmid containing genes for synthesis of the antigen fraction 1 and phospholipase D. In addition to the completely conserved genes of the pFra backbone, pG8786 contains two large regions consisting of 4,642 and 32,617 bp, designated regions 1 and 2, respectively. Region 1 retains a larger part of Salmonella enterica serovar Typhi plasmid pHCM2 resembling the backbone of pFra replicons, while region 2 contains 25 open reading frames with high levels of similarity to the transfer genes of the F-like plasmids. Surprisingly, region 1 is also present in the pFra plasmid of avirulent Y. pestis strain 91001 isolated in Inner Mongolia, People's Republic of China. Despite the fact that some genes typically involved in conjugative transfer of the F-like replicons are missing in pG8786, we cannot exclude the possibility that pG8786 might be transmissive under certain conditions. pG8786 seems to be an ancient form of the pFra group of plasmids that were conserved due to the strict geographical isolation of rhamnose-positive Y. pestis strains in the high mountainous Caucasian plague locus.

Base Composition↗

PubMed2004

The detection of Brucella spp. using PCR-ELISA and real-time PCR assays.

Brucellosis is a worldwide 're-emerging' zoonosis causing high economic losses and severe human disease. Consequently, rapid and reliable, sensitive and specific, easy to perform and automated detection systems for Brucella spp. are urgently needed to allow early diagnosis and adequate antibiotic therapy in time. Real-time PCR assays using hybridization probes meet all these requirements. In 2003 various assays have been developed and evaluated for use in human and animal brucellosis. Genus-specific real-time PCR assays e.g. based on the bcsp31 gene will lead to an early diagnosis but for the purpose of epidemiological surveillance a species-specific real-time PCR deriving from the conventional AMOS (AbortusMelitensisOvisSuis)-PCR is necessary. Advantages and disadvantages of the different methods for real-time detection of Brucella spp. and a newly developed PCR-ELISA system for the high throughput of clinical samples will be discussed.

Brucella↗

PubMed2003

Rapid detection of Yersinia pestis with multiplex real-time PCR assays using fluorescent hybridisation probes.

The objective of the present study was to establish a system of real-time polymerase chain reactions (PCRs) for the specific detection of Yersinia pestis using the LightCycler (LC) instrument. Twenty-five strains of Y. pestis, 94 strains of other Yersinia species and 33 clinically relevant bacteria were investigated. Assays for the 16S rRNA gene target and the plasminogen activator gene (resides on the 9.5-kb plasmid) and for the Y. pestis murine toxin gene and the fraction 1 antigen gene (both on the 100-kb plasmid) were combined for the use in two multiplex assays including an internal amplification control detecting bacteriophage lambda-DNA. Applying these multiplex assays, Y. pestis was selectively identified; other bacteria yielded no amplification products. The lower limit of detection was approximately 0.1 genome equivalent. Rat or flea DNA had no inhibitory effects on the detection of Y. pestis. The results obtained using the multiplex real-time assays showed 100% accuracy when compared with combinations of conventional PCR assays. We developed and evaluated a highly specific real-time PCR strategy for the detection of Y. pestis, obtaining results within 3 h including DNA preparation.

Animals↗

PubMed2003

A unifying basis of auditory thresholds based on temporal summation.

Thresholds of auditory-nerve (AN) fibers and auditory neurons are commonly specified in terms of sound pressure only, implying that they are independent of time. At the perceptual level, however, the sound pressure required for detection decreases with increasing stimulus duration, suggesting that the auditory system integrates sound over time. The quantity commonly believed to be integrated is sound intensity, implying that the auditory system would have an energy threshold. However, leaky integrators of intensity with time constants of hundreds of milliseconds are required to fit the data. Such time constants are unknown in physiology and are also incompatible with the high temporal resolution of the auditory system, creating the resolution-integration paradox. Here we demonstrate that cortical and perceptual responses are based on integration of the pressure envelope of the sound, as we have previously shown for AN fibers, rather than on intensity. The functions relating the pressure envelope integration thresholds and time for AN fibers, cortical neurons, and perception in the same species (cat), as well as for perception in many different vertebrate species, are remarkably similar. They are well described by a power law that resolves the resolution-integration paradox. The data argue for the integrator to be located in the first synapse in the auditory pathway and we discuss its mode of operation.

Animals↗

PubMed2003

Epizootiologic and ecologic investigations of European brown hares (Lepus europaeus) in selected populations from Schleswig-Holstein, Germany.

From 1997-99 European brown hare (Lepus europaeus) population densities were estimated by spotlight surveys within different areas in Schleswig-Holstein, Germany. These areas showed a wide variation in local hare population densities. In addition, red fox (Vulpes vulpes) densities were estimated in 1997 by surveys of fox dens and litters. Sera of 321 hares (shot between 1998-2000) from four study areas were examined for antibodies against European brown hare syndrome virus (EBHSV) by enzyme linked immunosorbent assay (ELISA), Yersinia spp. (n = 299) and Francisella tularensis (n = 299) by western blotting, Brucella spp. by Rose Bengal test, and Toxoplasma gondii by Sabin-Feldman test (n = 318). Tissue samples comprising lung, liver, spleen, kidney, heart, and adrenal glands were collected for histopathology. Liver (n = 201) and spleen (n = 201) samples were processed for the detection of T. gondii-antigen in tissue sections and 321 liver and spleen samples were investigated for EBHSV-antigen by ELISA. Furthermore, 116 hares were examined macro- and microscopically for lungworms. Significant negative correlations between hare and fox densities were found in spring and autumn 1997. Antibodies against EBHSV were detected in 92 of 321 (29%), against Yersinia spp. in 163 of 299 (55%), and against T. gondii in 147 of 318 (46%) hares. We evaluated the potential influence of origin and hunting season on exposure rates of hares using logistic regression analysis. A strong association between hare densities and exposure rates was observed for various agents. One hundred and eight of 201 (57%) hares were positive for T. gondii-antigen. All sera were negative for antibodies against Brucella spp. and F. tularensis and all lung samples were negative for lungworms. In conclusion, variation in red fox densities may have an impact on the hare populations examined and the infectious diseases we studied seem to play a subordinate role in the dynamics of European brown hare populations from Schleswig-Holstein.

Animals↗

PubMed2003

Laboratory-based diagnosis of brucellosis--a review of the literature. Part I: Techniques for direct detection and identification of Brucella spp.

Brucellosis is a world-wide re-emerging zoonosis and the most frequent laboratory-acquired bacterial infection, causing severe disease in humans with unspecific clinical signs affecting numerous organs. Contact with infected animals, ingestion of contaminated animal products and handling of Brucella isolates in laboratories are risk factors. Various other febrile illnesses, e.g. malaria, tuberculosis, typhoid fever and tularemia may present with the same symptoms. Therefore, clinical diagnosis is difficult to establish but effective therapy requires an early diagnosis. Vaccines for humans are still not commercially available. Blood culturing of Brucella is time-consuming and not reliable. Thus diagnosis is usually based on indirect serological tests, i.e. serum agglutination test, complement fixation or the Coombs test. However, these 'conventional' serological tests lack sensitivity and specificity. Hence, a combination of various tests is mandatory for a definite diagnosis. Enzyme-linked immunosorbent assays can be used for screening and confirmation of brucellosis in one step. Molecular techniques like the polymerase chain reaction and restriction fragment length polymorphism are needed to differentiate species and strains within the genus Brucella. This review will summarize advantages and disadvantages of the techniques used in clinical laboratories for direct detection and identification of Brucella spp.

Animals↗

PubMed2003

Laboratory-based diagnosis of brucellosis--a review of the literature. Part II: serological tests for brucellosis.

Brucellosis is a common zoonotic disease transmittable to humans from infected animal reservoirs. Malta, Rock, Gibraltar, Cyprus or Mediterranean fever, Bang's disease, intermittent typhoid or typho-malarial fever, undulant fever, etc. are just various synonyms for brucellosis. Patients suffering from this disease show unspecific symptoms, e.g. fever, chills, malaise, arthralgia, headache, tiredness and weakness. Human brucellosis may be caused by four of totally six genetically and phenotypically closely related Brucella species, i.e. B. melitensis, B. abortus, B. suis and B. canis. Although many organ systems may be involved, brucellosis is rarely fatal. Therapeutic failure and relapses, chronic courses and severe complications like bone and joint involvement, neurobrucellosis and endocarditis are characteristic for the disease. A definite diagnosis requires the isolation of Brucellae from blood, bone marrow or other tissues. However, cultural examinations are time-consuming, hazardous and not sensitive. Thus, clinicians often rely on the indirect proof of infection. The detection of high or rising titers of specific antibodies in the serum allows a tentative diagnosis. A variety of serological tests has been applied, but at least two serological tests have to be combined to avoid false negative results. Usually, the serum agglutination test is used for a first screening and complement fixation or Coombs' test will confirm its results. As Brucella ELISAs are more sensitive and specific than other serological tests, they may replace them step by step. This review will summarize advantages and disadvantages of the serological techniques used in clinical laboratories for indirect verification of human brucellosis.

Agglutination Tests↗

PubMed2002

A possible pitfall in the identification of Burkholderia mallei using molecular identification systems based on the sequence of the flagellin fliC gene.

Amotile Burkholderia mallei and motile Burkholderia pseudomallei display a high similarity with regard to phenotype and clinical syndromes, glanders and melioidosis. The aim of this study was to establish a fast and reliable molecular method for identification and differentiation. Despite amotility, the gene of the filament forming flagellin (fliC) could be completely sequenced in two B. mallei strains. Only one mutation was identified discriminating between B. mallei and B. pseudomallei. A polymerase chain reaction-restriction fragment length polymorphism assay was designed making use of the absence of an AvaII recognition site in B. mallei. All seven B. mallei, 12 out of 15 B. pseudomallei and 36 closely related apathogenic Burkholderia thailandensis strains were identified correctly. However, in three B. pseudomallei strains a point mutation at gene position 798 (G to C) disrupted the AvaII site. Therefore, molecular systems based on the fliC sequence can be used for a reliable proof of strains of the three species but not for the differentiation of B. mallei and B. pseudomallei isolates.

Base Sequence↗

PubMedDate not supplied

[The prevalence of anti-yersinia outer protein antibodies in Bavarian slaughter pigs].

The aim of the present study was to provide current data on the prevalence of anti-Yersinia-antibodies in Bavarian slaughtering pigs. The recomBlot Westernblot assay based on five recombinantly produced Yersinia Outer Proteins (YopD, YopE, YopH, YopM, V-antigen) is well evaluated for the use in the diagnosis of human yersiniosis and proved to be also a valuable tool for the detection of porcine antibodies. 965 out of 1002 meat juice samples collected in 53 Bavarian pig farms contained anti-Yop/V-Ag-antibodies. Only blots with three or more detectable signals were considered as positive. On the basis of these results a possible previous history of Yersinia infection was detected in 45.4% of the pigs and all of the pig farms. The high prevalence of anti-Yersinia-antibodies found in this investigation demonstrates the need for further epidemiological surveillance and animal studies to assess consumers' endangering.

Animals↗

PubMedDate not supplied

[The prevalence of Yersinia-specific antibodies in cattle in Bavaria].

Yersiniosis is considered to be an emerging infection in humans. It is believed that contaminated pork is the main source of infection for man but also beef and cow milk might cause infection in the consumer. Therefore, a survey was carried out to obtain actual data on the prevalence of anti-Yersinia antibodies within cattle. 600 serum samples were taken form 120 farms located in 43 districts of Bavaria, Germany. Antibodies were detected in 396 animals (65.7%) revealing a distribution of 52.3% of anti-YopD, 40.3% of anti-YopM, 24.0% of anti-YopH, 21.2% of anti-YopE and 3.0% of anti-V-antigen antibodies. 21 reactionpatterns out of 32 possible patterns were identified. Anti-YopD and YopM antibodies were sufficient to detect all Yersinia antibody positive sera. No regional differences in the distribution of antibodies were noted.

Animals↗