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Markus Hess

Publications and source records attributed to Markus Hess.

8 recordsLinked to original sources
PubMed2006

Detection and differentiation of Bordetella spp. by real-time PCR.

Molecular detection of Bordetella pertussis DNA is a sensitive and specific method for the rapid diagnosis of pertussis. In this study, a new molecular assay for the detection and differentiation of Bordetella spp. based on automated DNA extraction and real-time PCR was evaluated. The analytical sensitivity of the new assay was determined by Probit analysis of serial dilutions of both cloned PCR products IS481 and IS1001 and cell suspensions of B. pertussis, B. parapertussis, and B. bronchiseptica. The specificity was analyzed by testing a number of pathogens producing respiratory infections. Moreover, a total of 92 clinical samples were investigated. The results were compared to those obtained by an in-house assay based on manual DNA extraction, followed by real-time PCR and detection of IS481. The analytical sensitivity of the new assay for the detection of IS481 and IS1001 was determined to be 2.2 and 1.2 genome equivalents/mul, respectively. The analytical sensitivity for the detection of B. pertussis, B. parapertussis, and B. bronchiseptica was determined to be 1.6, 1.0, and 2.7 genome equivalents/mul, respectively. When clinical specimens were tested with the new assay, 46 of 92 were found to be positive for Bordetella DNA. With the in-house assay, 45 samples tested positive. The new molecular assay proved to be suitable for the rapid diagnosis of pertussis in the routine diagnostic laboratory.

Bordetella↗
PubMed2006

Artificial neural network-based classification to screen for dysphonia using psychoacoustic scaling of acoustic voice features.

SUMMARY: For diagnosis and classification of dysphonia, voice specialists can choose from an array of diagnostic tools like perceptual tests or acoustic voice analysis. These methods have in common that they require a high level of specialized training and experience, and therefore are mostly reserved to specialized centers. We aimed at developing an acoustic voice analysis system that could be used as a screening device to monitor, document, and diagnose voice problems that are also encountered by non-voice specialists, such as anesthesiologists, head and neck surgeons, and general surgeons before surgery of the thyroid gland and the upper thoracic aperture. An acoustical feature extraction paradigm that focused on jitter, shimmer, standard deviation of fundamental frequency, and the glottal-to-noise excitation ratio was used to reanalyse 120 voice samples previously analyzed by Schönweiler et al (A Novel Approach to Acoustical Voice Analysis Using Artificial Neural Networks. JARO. 2000:1;270-282). An improved artificial neural network (ANN) was used for classification. Building on this preliminary work, we modified the mathematical algorithm to further improve classification accuracy. Eighty percent of all voice samples could be classified correctly as either healthy or hoarse (sensitivity: 63.0%; specificity: 93.9%; area under the curve: 0.854). The adaptation of the ANN-voice analysis system for mobile use may facilitate its use and acceptance by non-voice specialists for the discovery and documentation of preexisting voice disorders, and may thereby lead to a timely initiation of further diagnosis and therapy by voice specialists.

Diagnosis, Differential↗
PubMed2006

The shear modulus of the human vocal fold, preliminary results from 20 larynxes.

Quantification of the elastic properties of the human vocal fold provides invaluable data for researchers deriving mathematical models of phonation, developing tissue engineering therapies, and as normative data for comparison between healthy and scarred tissue. This study measured the shear modulus of excised cadaver vocal folds from 20 subjects. Twenty freshly excised human larynxes were evaluated less than four days post-mortem. They were split along the saggital plane and mounted without tension. Shear modulus was obtained by two different methods. For method 1 cyclical shear stress was applied transversely to the mid-membranous portion of the vocal fold, and shear modulus derived by applying a simple shear model. For method 2 the apparatus was configured as an indentometer, and shear modulus obtained from the stress/strain data by applying an established analytical technique. Method 1 shear model for male larynxes yielded a range from 246 to 3,356 Pa, with a mean value of 1,008 and SD of 380. The range for female larynxes was 286-3,332 Pa, with a mean value of 1,237 and SD of 768. Method 2 indentometer model for male larynxes yielded a range from 552 to 2,741 Pa, with a mean value of 1,000 and SD of 460. The range for female larynxes was 509-1,989 Pa, with a mean value of 1,332 and SD of 428. We have successfully demonstrated two methodologies that are capable of directly measuring the shear modulus of the human vocal fold, without dissecting out the vocal fold cover tissue. The sample size of nine female and 11 male larynxes is too small to validate a general conclusion. The high degree of variability in this small cohort of subjects indicates that factors such as age, health status, and post-mortem delay may be significant; and that there is range of 'normality' for vocal fold tissue.

Biomechanical Phenomena↗
PubMed2006

In vivo measurement of the elastic properties of the human vocal fold.

The ability to measure the biomechanical properties of the vocal fold in vivo is both an aid to diagnosis and enhances our knowledge of how the vocal folds operate. This paper details a new instrument that is capable of taking readings of the spring rate of the vocal fold in a repeatable manner. We also present three sets of readings taken from two volunteer patients. Patient 1 was suffering from polyp growth, and the data presented are taken from both the damaged vocal fold and the healthy vocal fold. The third set of readings was obtained from a similar volunteer and taken from a healthy vocal fold. It can be seen that the data obtained from the healthy vocal folds are similar and that the data obtained from the diseased vocal fold is at variance.

Biomechanical Phenomena↗
PubMed2004

Impaired calmodulin binding of myosin-7A causes autosomal dominant hearing loss (DFNA11).

Both myosin 7A (MYO7A) and calmodulin (CaM) are required for transduction and adaptation processes in inner ear hair cells. We identified a novel heterozygous missense mutation (c.2557C>T; p.R853C) in a family with autosomal dominant non-syndromic hearing loss that changes an evolutionarily invariant residue of the fifth IQ motif (IQ5), a putative calmodulin (CaM) binding domain, of MYO7A. Functional effects of the p.R853C mutation were investigated in a physiological cellular environment by expressing MYO7A IQ5-containing peptides in smooth muscle cells of microarteries, in which overexpression of wildtype IQ5 (with intact calmodulin binding) would be expected to compete with myosin light chain kinase (MLCK) for CaM binding. Indeed, analysis of calmodulin-dependent vasoconstriction suggests constitutive binding of CaM to the wildtype, but not the p.R853C-mutated IQ5 motif at all physiologically relevant Ca2+ concentrations. Thus our data suggest a disturbed CaM/MYO7A binding of the p.R853C mutant, this amino acid change may result in impaired adaptation to environmental stimuli and progressive deterioration of hearing transduction in heterozygotes. A defect in CaM/MYO7A interaction represents a novel pathomechanism for genetic hearing loss. It provides an attractive molecular target for therapeutic interventions aimed to delay or prevent the onset of hearing loss in families with mutations in myosin IQ domains.

Adolescent↗
PubMed2004

Phenotypic variability of non-syndromic hearing loss in patients heterozygous for both c.35delG of GJB2 and the 342-kb deletion involving GJB6.

Mutations in GJB2, encoding the gap junction protein connexin 26, are the most common cause of inherited non-syndromic hearing loss (NSHL), with a broad spectrum of mutations leading to recessive as well as dominant forms. It has been shown that patients who are compound heterozygous for a 342-kb deletion (Delta(GJB6-D13S1830)) involving a large portion of the 5'-part of GJB6, encoding connexin 30, and a GJB2 mutation develop NSHL due to a trait with a digenic pattern of inheritance. We have used a mutation-specific polymerase chain reaction assay to screen NSHL patients for the presence of Delta(GJB6-D13S1830) and identified two families segregating both c.35delG in GJB2 and Delta(GJB6-D13S1830). Remarkably, the severity of hearing loss due to heterozygosity for c.35delG in GJB2 in conjunction with Delta(GJB6-D13S1830) is considerably different in members of the two families, ranging from congenital deafness in one to moderate/severe hearing loss with congenital onset in the other case.

Adolescent↗
PubMed2002

A first-generation EST RH comparative map of the porcine and human genome.

We have constructed a first-generation EST radiation hybrid comparative map of the porcine genome by assigning 1,058 markers to the IMpRH(7000) panel. Chromosomal localization was determined with a 2pt LOD of 4.8 for 984 markers, using the IMpRH mapping tool. Annotated ESTs represent 46.2% or 489 of the markers. Marker distribution was not stochastic and ranged from 0.41 for SSC8 to 1.77 for SSC12, respectively. Two hundred fifty-one markers assigned to the physical map of the pig did not find a homologous sequence in V22 of the human genome assembly, indicative of gaps in the assembled human genome sequence. The comparative porcine/human map covers 3,290 MB, or 98.3% of the presumed size of the human genome. However, 60 breakpoints were identified between chromosomes, as well as 90 micro-rearrangements within synteny groups. Six porcine chromosomes-SSC2, 5, 6, 7, 12, and 14-correspond to the three gene-richest human chromosomes, HSA17, 19, and 22, and show above average marker density. Porcine Chrs 1, 8, 11, and X display a low DNA/marker ratio and correspond to the 'genome deserts' on HSA 18, 4, 13, and X.

Animals↗