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Biomedical subjects

Hermann Müller

Publications and source records attributed to Hermann Müller.

At least 19 recordsLinked to original sources
PubMed2006

Generation of virus-like particles consisting of the major capsid protein VP1 of goose hemorrhagic polyomavirus and their application in serological tests.

Goose hemorrhagic polyomavirus (GHPV) is the causative agent of hemorrhagic nephritis and enteritis of geese (HNEG), a fatal disease of young geese with high mortality rates. GHPV cannot be efficiently propagated in tissue culture. To provide antigens for diagnostic tests and vaccines, its major structural protein VP1 was recombinantly expressed in Sf9 insect cells and in the yeast Saccharomyces cerevisiae. As demonstrated by density gradient centrifugation and electron microscopy, GHPV-VP1 expressed in insect cells formed virus-like particles (VLPs) with a diameter of 45 nm indistinguishable from infectious polyomavirus particles. However, efficiency of VLP formation was low as compared to the monkey polyomavirus SV-40-VP1. In yeast cells, GHPV-VP1 alone formed smaller VLPs, 20 nm in diameter. Remarkably, co-expression of GHPV-VP2 resulted in VLPs with a diameter of 45 nm. All three types of GHPV-VLPs were shown to hemagglutinate chicken erythrocytes. ELISA and hemagglutination inhibition tests using the VLPs as antigen detected GHPV-specific antibodies in up to 85.7% of sera derived from flocks with HNEG but in none of the sera of a clinically healthy flock. However, GHPV-specific antibodies were also detected in sera from two other flocks without HNEG indicating a broad distribution of GHPV due to subclinical or unrecognised infections.

Animals↗
PubMed2006

Genome of a novel circovirus of starlings, amplified by multiply primed rolling-circle amplification.

The genus Circovirus comprises small non-enveloped viruses with a circular single-stranded DNA genome. By using PCR with degenerate primers, a novel circovirus (starling circovirus, StCV) was detected in spleen samples of wild starlings (Sturnus vulgaris and Sturnus unicolor) found dead during an epidemic outbreak of septicaemic salmonellosis in northeastern Spain. Using a specific PCR, StCV was also detected in apparently healthy birds from the same population. The genome was amplified using multiply primed rolling-circle amplification and cloned. Open reading frames (ORFs) with similarities to the replication-associated protein and the capsid protein of circoviruses as well as an additional ORF encoding a protein of 106 aa were evident from the sequence. Phylogenetic analysis of circovirus genomes revealed the highest degree of similarity (67.1 %) between StCV and canary circovirus. A similar analysis of the evolutionarily conserved cytochrome b gene of the circovirus host species revealed a strict co-evolution of circoviruses with their hosts; however, the circoviruses showed about a threefold higher genetic divergence than their hosts.

Amino Acid Sequence↗
PubMed2006

Characterization of two novel polyomaviruses of birds by using multiply primed rolling-circle amplification of their genomes.

Polyomaviruses are small nonenveloped particles with a circular double-stranded genome, approximately 5 kbp in size. The mammalian polyomaviruses mainly cause persistent subclinical infections in their natural nonimmunocompromised hosts. In contrast, the polyomaviruses of birds--avian polyomavirus (APV) and goose hemorrhagic polyomavirus (GHPV)--are the primary agents of acute and chronic disease with high mortality rates in young birds. Screening of field samples of diseased birds by consensus PCR revealed the presence of two novel polyomaviruses in the liver of an Eurasian bullfinch (Pyrrhula pyrrhula griseiventris) and in the spleen of a Eurasian jackdaw (Corvus monedula), tentatively designated as finch polyomavirus (FPyV) and crow polyomavirus (CPyV), respectively. The genomes of the viruses were amplified by using multiply primed rolling-circle amplification and cloned. Analysis of the FPyV and CPyV genome sequences revealed a close relationship to APV and GHPV, indicating the existence of a distinct avian group among the polyomaviruses. The main characteristics of this group are (i) involvement in fatal disease, (ii) the existence of an additional open reading frame in the 5' region of the late mRNAs, and (iii) a different manner of DNA binding of the large tumor antigen compared to that of the mammalian polyomaviruses.

Amino Acid Sequence↗
PubMed2005

A disease complex associated with pigeon circovirus infection, young pigeon disease syndrome.

In order to collect more convincing data on the aetiological agent of young pigeon disease syndrome (YPDS), a comprehensive study was performed on pigeons in German lofts with or without outbreaks of YPDS. The investigations included examination of histories, clinical signs and pathology, as well as parasitological and microbiological analysis. Pigeons in their 4th to 12th week of life exhibited clinical signs at higher frequency and with greater severity than pigeons of other ages. Greenish liquid in the crop, proventriculus and ventriculus, and yellow fluid in the small intestine were seen more often in YPDS-affected pigeons. Escherichia coli and Klebsiella pneumoniae were isolated more frequently from these birds. Depletion of splenic and bursal lymphocytes was only seen in pigeons with YPDS. Inclusion bodies were present in various organs, especially the bursa of Fabricius. The genome of pigeon circovirus was detected in lymphoid tissues from all pigeons with YPDS. The results of this study indicate that YPDS is a multifactorial disease in which pigeon circovirus might be a crucial factor, possibly by inducing immunosuppression in infected birds.

Animals↗
PubMed2005

Novel polyomavirus detected in the feces of a chimpanzee by nested broad-spectrum PCR.

In order to screen for new polyomaviruses in samples derived from various animal species, degenerated PCR primer pairs were constructed. By using a nested PCR protocol, the sensitive detection of nine different polyomavirus genomes was demonstrated. The screening of field samples revealed the presence of a new polyomavirus, tentatively designated chimpanzee polyomavirus (ChPyV), in the feces of a juvenile chimpanzee (Pan troglodytes). Analysis of the region encoding the major capsid protein VP1 revealed a unique insertion in the EF loop of the protein and showed that ChPyV is a distinct virus related to the monkey polyomavirus B-lymphotropic polyomavirus and the human polyomavirus JC polyomavirus.

Amino Acid Sequence↗
PubMed2004

Generation of serotype 1/serotype 2 reassortant viruses of the infectious bursal disease virus and their investigation in vitro and in vivo.

Infectious bursal disease virus (IBDV) is the causative agent of acute or immunosuppressive disease in chickens. Serotype 1 strains are pathogenic whereas serotype 2 strains neither cause disease nor protect against infection with the serotype 1 strains. The target organ of serotype 1 strains is the bursa Fabricii (BF). The molecular determinants of this tropism, and therefore pathogenicity, are poorly understood. IBDV is a non-enveloped icosahedral virus particle of 60 nm in diameter, which contains two genome segments of double-stranded RNA. Here, the generation of interserotypic reassortants using the reverse genetics approach is reported. The results of in vitro and in vivo investigations show that genome segment A determines the bursa tropism of IBDV, whereas segment B is involved in the efficiency of viral replication; they further indicate the significance of the interaction of the polymerase (segment B) with the structural protein VP3 (segment A) or the viral genome for efficient virus formation and replication.

Animals↗
PubMed2004

Decomposition of variability in the execution of goal-oriented tasks: three components of skill improvement.

A central ability of the motor system is to achieve goals with great reliability, although never with zero variability. It is argued that variability is reduced with practice by 3 separate means: reduction of stochastic noise (N), exploitation of task tolerance (T), and covariation (C) between central variables. A method is presented that decomposes variability into these components in relation to task space that is defined by the execution variables. Successful variable combinations form the solution manifold. In a virtual skittles task, it is demonstrated that participants' improvement over repetitions, indicated by increasing accuracy, is accounted for by N, T, and, to a lesser degree, C. The relative contribution of these components changes over the course of practice and task variations.

Goals↗
PubMed2004

Nucleotide sequence analysis of a C1 gene fragment of psittacine beak and feather disease virus amplified by real-time polymerase chain reaction indicates a possible existence of genotypes.

To investigate sequence diversity of psittacine beak and feather disease virus, samples collected from 31 psittacine species with or without clinical signs were tested for the presence of the viral genome. A real-time polymerase chain reaction was developed amplifying a 202 base pair fragment of the region encoding the capsid protein C1 and detecting 100 to 1000 genome equivalents. The nucleotide sequences of the polymerase chain reaction products showed 84.1 to 100% identity with no consistent pattern with regard to the infected bird species. Amino acid exchanges were concentrated mainly in five of the 42 deduced positions. Sequences obtained from an outbreak of acute beak and feather disease in lories clustered in a separate branch of a phylogenetic tree. Sequences in samples from African grey parrots with feather disorders grouped together, whereas those from the same species with immunosuppression clustered in other branches. These results indicate the possible existence of beak and feather disease virus genotypes.

Amino Acid Sequence↗
PubMed2004

Recombinant expression of a truncated capsid protein of beak and feather disease virus and its application in serological tests.

Beak and feather disease virus (BFDV) causes severe disease characterized by irreversible feather disorders and severe immunosuppression in many psittacine species. BFDV cannot be propagated in tissue or cell cultures, rendering virus propagation and thus diagnosis rather difficult. To develop reliable diagnostic methods, the region encoding the BFDV capsid protein C1 was cloned from an infected sulphur-crested cockatoo (Cacatua galerita). Phylogenetic analysis showed this gene had 76.3 to 83.2% amino acid identity to published sequences. No protein was detected after induction of full-length C1 expression in Escherichia coli. However, deletion of an amino-terminal arginine-rich sequence facilitated expression. C1(39-244)-His, a polyhistidine-tailed variant of this protein, was purified and used for immunization of chickens. The immune sera detected C1 with an apparent molecular weight of 27 kDa in western blots of organ homogenates of BFDV-infected birds. Using C1(39-244)-His as antigen, 11 psittacine sera were tested for the presence of BFDV-specific antibodies by enzyme-linked immunosorbent assay and immunoblotting. The results obtained correlated well with the BFDV-specific haemagglutination inhibition activity of the sera, suggesting C1(39-244)-His has value as a recombinant antigen for BFDV-specific serological tests.

Amino Acid Sequence↗
PubMed2004

Does botulinum toxin A make prosthesis use easier for amputees?

Four post-amputation patients (1 with phantom pain, 3 with stump pain) were each treated with 100 IU botulinum toxin A, divided between several trigger points in the distal stump musculature. In 1 female patient (along with a pronounced reduction in phantom pain) hyperhidrosis of the stump ceased completely, probably after diffusion of the drug into the dermal sweat glands, leading to longer and safer use of the prosthesis. Intentional intradermal injection for this issue therefore could be valuable. Another patient was able to use her prosthesis for the whole day again after botulinum toxin A treatment for substantial stump pain, compared with only 4 hours a day before treatment. In 2 male patients, stump pain while wearing the prosthesis subsided to a considerable extent, 1 of the 2 reported an improvement in steadiness of gait. We suggest that stump treatment with botulinum toxin in rehabilitative medicine should be investigated in more detail.

Adult↗
PubMed2004

Effects of botulinum toxin type B on stump pain and involuntary movements of the stump.

Patients who had previously undergone amputation of the arm (n = 2) or leg (n = 2) were treated with botulinum toxin type B injections at several trigger points of their stump musculature. We administered a total dose of 2500 IU of botulinum toxin type B (Neurobloc, Elan Pharma, Munich, Germany) to the arm amputation stumps, 5000 IU for one amputation of the lower leg, and 2500 IU to the other lower leg amputation of a patient with a very low baseline body weight. Two patients reported that the injection was very painful. All patients experienced a reduction in stump pain, which lasted for many weeks. Other reports included a reduction in the frequency of pain attacks, cessation of "balloon feelings," improvement in stump allodynia, and decreased occurrence of involuntary stump movements. In addition, quality of sleep at night significantly improved in one patient. Botulinum toxin type B can therefore be regarded as a new treatment option for possible improvements in the rehabilitation of amputees.

Aged↗
PubMed2004

Nuclear localization of avian polyomavirus structural protein VP1 is a prerequisite for the formation of virus-like particles.

Virions of polyomaviruses consist of the major structural protein VP1, the minor structural proteins VP2 and VP3, and the viral genome associated with histones. An additional structural protein, VP4, is present in avian polyomavirus (APV) particles. As it had been reported that expression of APV VP1 in insect cells did not result in the formation of virus-like particles (VLP), the prerequisites for particle formation were analyzed. To this end, recombinant influenza viruses were created to (co)express the structural proteins of APV in chicken embryo cells, permissive for APV replication. VP1 expressed individually or coexpressed with VP4 did not result in VLP formation; both proteins (co)localized in the cytoplasm. Transport of VP1, or the VP1-VP4 complex, into the nucleus was facilitated by the coexpression of VP3 and resulted in the formation of VLP. Accordingly, a mutant APV VP1 carrying the N-terminal nuclear localization signal of simian virus 40 VP1 was transported to the nucleus and assembled into VLP. These results support a model of APV capsid assembly in which complexes of the structural proteins VP1, VP3 (or VP2), and VP4, formed within the cytoplasm, are transported to the nucleus using the nuclear localization signal of VP3 (or VP2); there, capsid formation is induced by the nuclear environment.

Amino Acid Sequence↗
PubMed2003

Research on infectious bursal disease--the past, the present and the future.

Infectious bursal disease (IBD) virus (IBDV) is the etiological agent of "Gumboro disease". Although first observed about 40 years ago, this disease continues to pose an important threat to the commercial poultry industry. The emergence of antigenic variant as well as very virulent strains in vaccinated flocks considerably stimulated research efforts on both, IBD and IBDV. In this review, some of the recent advances in the understanding of the structure, morphogenesis and molecular biology of the virus as well as in development of new diagnostic approaches and new strategies for vaccination against IBD are briefly summarized.

Animals↗
PubMed2003

Actively tracking 'passive' stability in a ball bouncing task.

This study investigates the control involved in a task where subjects rhythmically bounce a ball with a hand-held racket as regularly as possible to a prescribed amplitude. Stability analyses of a kinematic model of the ball-racket system revealed that dynamically stable solutions exist if the racket hits the ball in its decelerating upward movement phase. Such solutions are resistant to small perturbations obviating explicit error corrections. Previous studies reported that subjects' performance was consistent with this 'passive' stability. However, some 'active' control is needed to attune to this passive stability. The present study investigates this control by confronting subjects with perturbations where stable behavior cannot be maintained solely from passive stability. Six subjects performed rhythmic ball bouncing in a virtual reality set-up with and without perturbations. In the perturbation trials the coefficient of restitution of the ball-racket contact was changed at every fifth contact leading to unexpected ball amplitudes. The perturbations were compensated for within 2-3 bouncing cycles such that ball amplitudes decreased to initial values. Passive stability was reestablished as indicated by negative racket acceleration. Results revealed that an adjustment of the racket period ensured that the impacts occurred at a phase associated with passive stability. These findings were implemented in a model consisting of a neural oscillator that drives a mechanical actuator (forearm holding the racket) to bounce the ball. Following the perturbation, the oscillator's period is adjusted based on the perceived ball velocity after impact. Simulation results reproduced the major aspects of the experimental results.

Acceleration↗
PubMed2003

The genome of goose hemorrhagic polyomavirus, a new member of the proposed subgenus Avipolyomavirus.

The full-length genome of goose hemorrhagic polyomavirus (GHPV), the ethiologic agent of hemorrhagic nephritis and enteritis of geese, was cloned and sequenced. Transfection of the circular ds DNA with a size of 5256 bp and an organisation typical of polyomaviruses produced viral progeny in cultured goose cells. According to the splicing sites determined by RT-PCR, five open reading frames (ORFs) were found to encode putative proteins with significant similarities to large T antigen and small t antigen as well as VP1, VP2, and VP3 of other polyomaviruses. An additional ORF located in the 5' region of late mRNA, with a coding capacity for 169 amino acids, shows a low degree of homology to VP4 of avian polyomavirus (APV). The alignment of nucleotide sequences and amino acid sequences revealed a relatively close relationship between GHPV and APV. Therefore, grouping of this new polyomavirus into the proposed subgenus Avipolyomavirus is suggested.

Amino Acid Sequence↗
PubMed2003

A randomization method for the calculation of covariation in multiple nonlinear relations: illustrated with the example of goal-directed movements.

A randomization method is developed for the calculation of covariation between multiple variables that are linked nonlinearly to a dependent variable. Covariation is a phenomenon often invoked in the study of movement coordination to capture the fact that in coordinated movement the outcome shows greater than expected consistency from the variability in the component processes. However, in most cases, the problem is that more than two variables covary in a nonlinear fashion, which makes quantification with the bivariate linear covariation and correlation coefficient inapplicable. This paper presents a generalization of the calculation of linear bivariate covariance using a variant of a randomization method that is based on the comparison between the empirically measured variability in the outcome and a covariation-free variability. The latter can be estimated by permuting data sets. A generalized correlation coefficient is derived, and it is shown how errors of estimation can be quantified. The permutation method can also quantify partial multiple nonlinear covariation. The calculations are illustrated in a numerical example of an arm-reaching task. However, the method is applicable to all cases where the internal organization of a nonlinear system of multiple variables needs to be quantified. The relation and applicability of the permutation method compared to other methods using regression and principal component analysis are discussed and illustrated with a numerical example.

Arm↗
PubMed2002

Detection and quantitation of group A rotaviruses by competitive and real-time reverse transcription-polymerase chain reaction.

A competitive reverse transcription-polymerase chain reaction (RT-PCR) was developed to detect and to quantitate the RNA of group A rotaviruses. In the assay, a 433 bp fragment is amplified by a one-tube RT-PCR protocol using primers with binding sites located in a highly conserved region of segment 6 of the rotavirus genome. An in vitro synthesized RNA with a 43-base deletion with respect to the wild-type sequence of this fragment was used as an internal control. Using these transcripts as templates, 10 RNA molecules were amplified reproducibly and detected in ethidium bromide-stained agarose gels or by fluorimetry using the SYBR Green I dye in a real-time RT-PCR assay. The efficiency of the protocol was confirmed by the detection of small amounts of viral RNA of group A rotaviruses in clinical samples obtained from various animal species and man.

Base Sequence↗