Biomedical subjects

K Fuchs

Publications and source records attributed to K Fuchs.

At least 19 recordsLinked to original sources

PubMed2006

Dielectric properties of glycerol/water mixtures at temperatures between 10 and 50 degrees C.

At six temperatures T between 10 and 50 degrees C and at mole fractions x(g) of glycerol (0<x(g)<or=0.9) the complex (electric) permittivity epsilon(nu) of glycerol/water mixtures has been measured as a function of frequency nu between 1 MHz and 40 GHz. The spectra of the glycerol/water mixtures can be well represented by a Davidson-Cole [J. Chem. Phys. 18, 1417 (1950)] relaxation function that reveals an unsymmetric relaxation time distribution. The effective dipole orientation correlation factor derived from the static permittivity displays an unspectacular behavior upon mixture composition. The dielectric relaxation time reveals a simple relation to the shear viscosity of the mixtures, but both quantities are not proportional to one another. The relaxation times at high temperatures nicely complement previously determined low temperature data, following a Vogel-Fulcher-Tammann-Hesse [Z. Phys. 22, 645 (1925); J. Am. Chem. Ceram. Soc. 8, 339 (1923); Z. Anorg. Allg. Chem. 156, 245 (1926)] (VFTH) temperature dependence. When the Eyring behavior is assumed a limiting high temperature form of the VFTH relation, enthalpy, and entropy of activation values are found which adopt significantly higher values in the glycerol rich mixtures than in the water rich liquids. The relaxation time distribution parameter at high water content indicates a dynamically heterogeneous structure of the liquids. Likely there exist glycerol rich and water rich microphases.

Journal Article↗

PubMed2006

Serological, bacteriological and molecularbiological survey of paratuberculosis (Johne's disease) in Austrian cattle.

Paratuberculosis (Johne's disease) is a chronic infectious disease of ruminants, caused by Mycobacterium avium subspecies paratuberculosis (MAP). Because of its long incubation period, high economic losses, difficulties in diagnosis and possible links to Morbus Crohn in humans, paratuberculosis is one of the most important diseases of ruminants today. An abattoir-based nationwide survey on the occurrence of MAP in the Austrian cattle population was performed using serology (SVANOVIR-ELISA) as well as culture, ZN-stain and IS900-PCR on faeces and lymph node samples. A total of 756 Austrian slaughter cattle were serologically, bacteriologically and molecularbiologically tested for the occurrence of MAP and specific antibodies respectively. Samples were collected following a statistical plan to obtain balanced specimens from the whole country. Nineteen per cent of the animals tested were serological positive, 10.1% gave an inconclusive result and 70.9% showed no specific antibodies against MAP. Only in four individuals MAP could be detected by stain, bacteriology or Polymerase Chain Reaction. The calculated prevalence of 19.0% positive cattle, each representing one farm, showing specific antibodies against MAP is rather high in terms of animal-level but low in herd level prevalence compared with other countries. When this study is compared with a similar study performed in Austria 1999, a significant increase of positive cattle and farms could be seen in Austria.

Abattoirs↗

PubMed2005

Chlorhexidine-induced ultrastructural alterations in oral biofilm.

Chlorhexidine, the most used biocide in periodontology, alters the permeability of the bacterial cell membrane. However, the chlorhexidine-induced morphological alterations in the oral biofilm have not been studied. To examine the effects of chlorhexidine on oral biofilm on an electron microscopic level, gingival epithelial cells with attached biofilm were collected from 10 volunteers, subjected to 0.1% chlorhexidine for 1 or 5 min, stained with ruthenium red-tetroxide, and analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM visualized the bacterial glycocalyces and the biofilm matrix on the biofilm surface; however, no chlorhexidine-induced alterations were observed. TEM revealed loss of bacterial membrane integrity and fimbrial disintegration in a few bacteria. In the proximity of these alterations, a restricted matrix disintegration was also observed. However, the chlorhexidine-induced alterations only effected a minor part of the oral biofilm and did not cause its disintegration. These findings suggest the insufficient efficiency of chlorhexidine against oral biofilm.

Adolescent↗

PubMed2005

No association of clock gene T3111C polymorphism and affective disorders.

CLOCK was hypothesised to be related to susceptibility of affective disorders. To test subsamples of affectively disordered patients, we examined age of onset (AoO), numbers of episodes and melancholic type of clinical manifestation. Using PCR and RFLP, we investigated in patients with unipolar depression and bipolar disorder (BP) whether the CLOCK T3111C SNP is associated with affective disorders (n=102) compared to healthy controls (n=103). No differences were found either in genotype or allele frequency distributions of T3111C polymorphism between patients compared to healthy controls (p>0.2). No deviations from Hardy-Weinberg Equilibrium (HWE) were detected either in patients, or healthy controls. Results suggest that there is no association between the T3111C SNP and affective disorders in general. Data of our sample replicate prior findings of Desan et al. [Am. J. Med. Genet. 12 (2000) 418]. Subsamples of patients with high numbers of affective episodes did show some deviations in genotypes (p=0.0585).

Adult↗

PubMed2005

Ex vivo gingival-biofilm consortia.

AIMS: To develop a protocol for harvesting ex vivo samples of gingival-biofilm consortia and to investigate their basic characteristics. METHODS AND RESULTS: Gingival epithelial cells with attached biofilm were collected from healthy subjects by taking a smear. The bacterial viability was estimated via the alteration of the membrane permeability and metabolic activity via the double/single-stranded nucleic acid ratio using a confocal laser-scanning microscope. Morphological analysis was performed by scanning and transmission electron microscopy. Additionally, microbiological estimations were made. The electron microscopy revealed fimbriae-mediated adhesion and the formation of a biofilm matrix. Most bacteria were viable and had a high metabolic activity. CONCLUSIONS: The presented study offers an easy to follow approach for harvesting samples of gingival-biofilm consortia. The latter differs considerably from the supragingival plaque in viability and zonal distribution. Related to free-living and in vitro-grown biofilms, the gingiva-associated biofilm revealed an atypically high metabolic activity. SIGNIFICANCE AND IMPACT OF THE STUDY: Biofilm fragments should possess the basic features of the entire gingiva-associated biofilm; which as yet cannot be simulated in vitro. Thus, samples of ex vivo gingival-biofilm consortia can be used to investigate the resistance of oral biofilms against antibiotics and biocides.

Bacteria↗

PubMed2005

A decision-support system for real-time risk assessment of airborne spread of the foot-and-mouth disease virus.

OBJECTIVES: [corrected] The application of epidemic models during the first days following the confirmation of a virus outbreak should significantly contribute to minimize its costs. Here we describe the first version of a decision-support system for the calculation of the airborne spread of a virus and its application to foot-and-mouth disease (FMD). The goal is to provide geographical maps depicting infection risk for various animal species to support the national health authorities. METHODS: The major tool of the decision-support system is a specific epidemic (or atmospheric) model: A so-called Gaussian dispersion model to calculate 3-dimensional virus plumes. Additional tools providing input data and visualizing the output are: A veterinary data base of geo-referenced premises, a geographical information system (GIS), and, as an external part running at the National Weather Service, a numerical weather prediction (NWP) model. To demonstrate the features of the decision-support system a pilot study in Styria, Austria, has been performed simulating an artificial FMD outbreak. RESULTS: One result of this simulation experiment is the determination of neighboring premises at which animals are at risk to be infected. Particular attention has been turned to cattle, sheep and swine. Using actual hourly NWP data from April 25, 2003, and a source of ten swine excreting a virus, cattle have been estimated to be at risk downwind 1,000-12,000 m, sheep 200-1,300 m, and swines 70-330 m. CONCLUSIONS: A system for real-time risk assessment of the airborne spread of a virus, applied to FMD, was introduced. Due to the forcing of the Gaussian dispersion model with NWP data, it is designed to run in both analysis and forecast mode. The system was applied for the first time during the Austrian real-time exercise on FMD, instructed by the European Union, in November 2004.

Air Microbiology↗

PubMed2004

On-line anosognosia: unawareness for chorea in real time but not on videotape delay.

In hemiplegics, anosognosia (unawareness of deficit) rests on a mismatch between expected and actual movement: a feedback hypothesis emphasizes sensory deficits or neglect, a feedforward hypothesis postulates impaired intention to move. Anosognosia for other problems is less studied. The authors report a man without sensory deficits who was unaware of choreiform movements, except on videotape delay. The authors believe that a feed-forward mechanism underlies his "on-line" unawareness.

Agnosia↗

PubMed2004

Kinetics of Ca2+ complexation with some carbohydrates in aqueous solutions.

For solutions of four saccharides in water with alkaline-earth chlorides added ultrasonic attenuation spectra between 100 kHz and 2 GHz are reported and compared to those for carbohydrate solutions without salt. Calcium chloride does not alter the relaxation times in the spectra of D-glucose and D+-maltose solutions, reflecting the exocyclic hydroxymethyl group rotation, a saccharide-saccharide association, and, with the disaccharide, also motions of both rings of a molecule relative to one another. The spectra of D-xylose and D-fructose solutions are substantially changed by the salts. With both saccharides an additional term with relaxation time around some nanoseconds exists which is assigned to a rearrangement of a carbohydrate-cation complex. Other relaxation terms of these saccharide solutions are also subject to noticeable changes by the salt, indicating specific carbohydrate-cation interactions. The ultrasonic spectra show that such interactions may exist also with carbohydrates which do not display the particular hydroxyl group sequences that are considered to promote complexation with cations.

Journal Article↗

PubMed2004

Multiple sclerosis gender issues: clinical practices of women neurologists.

Substantially more women than men develop multiple sclerosis (MS), but information about the effects of MS and gender-specific issues such as pregnancy, breastfeeding, menstruation and hormone use is lacking. A survey study of neurologists' practice patterns was undertaken to elicit information about gender-specific topics and the use of disease-modifying MS therapies (DMT) including the interferons and glatiramer acetate (GA). A total of 147 surveys were returned. Half of respondents require patients to discontinue DMT during pregnancy, while 35% encourage discontinuation. Among those who allow patients to continue therapy, half consider GA to be safer during pregnancy than the interferons. Nearly 86% of respondents do not use DMT in patients who are breastfeeding. Among the 11% who actually prescribe during breastfeeding, most recommend GA. Neurologists generally leave the decision to breastfeed up to patients, and most refer patients to obstetrician/gynaecologists for counselling about contraception or hormone replacement therapy. The survey results described here provide insight into how neurologists manage reproductive health issues among women with MS.

Breast Feeding↗

PubMed2003

Serum amyloid A in the serum and milk of ewes with mastitis induced experimentally with Staphylococcus epidermidis.

Mastitis was induced experimentally in ewes with Staphylococcus epidermidis, and the concentrations of serum amyloid A (SAA) in milk and serum, and the somatic cell counts and bacteria in the milk were determined for up to 10 weeks in two experiments, each examining five infected and five control ewes. The somatic cell counts peaked eight hours after infection and preceded an increase in SAA in milk. A maximum concentration of 6460 microg/ml SAA was recorded in milk from the infected sheep, compared with a mean concentration of 1.4 microg/ml in the control sheep. The mean peak concentration of SAA in serum (206.8 microg/ml) occurred earlier (one day after infection) than in milk. The serum concentration of SAA in the healthy animals ranged from 0 to 29.4 microg/ml. There was no correlation between the concentrations of SAA in serum and milk.

Animals↗

PubMed2003

A polymorphism (5-HTTLPR) in the serotonin transporter promoter gene is associated with DSM-IV depression subtypes in seasonal affective disorder.

Serotonergic mechanisms are thought to play an important role in the pathogenesis of seasonal affective disorder (SAD). The expression of the serotonin transporter (5-HTT) is regulated in part by an insertion/deletion polymorphism in the serotonin transporter gene promoter region (5-HTTLPR). The 5-HTTLPR short allele (s) has been associated with anxiety-related personality traits and depression, and one study observed an association between the 5-HTTLPR s-allele and SAD and the trait of seasonality. We genotyped 138 SAD patients and 146 healthy volunteers with low seasonality for 5-HTTLPR. No difference between patients and controls was found for genotype distribution and s-allele frequency. However, genotype distribution and allele frequencies were strongly associated with DSM-IV depression subtypes. Melancholic depression was associated with the 5-HTTLPR long (l) allele and atypical depression with the 5-HTTLPR s-allele (two-sided Fisher's exact test: genotype distribution: P=0.0038; allele frequencies: P=0.007). Our data are compatible with the hypothesis of a disease process that is not causally related to 5-HTTLPR, but involves 5-HT neurotransmission and 5-HTTLPR somewhere on its way to phenotypic disease expression.

Bipolar Disorder↗

PubMed2003

The utility of computerized neuropsychological assessment of cognitive dysfunction in patients with relapsing-remitting multiple sclerosis.

Traditional paper-and-pencil neuropsychological batteries used to document cognitive deficits in multiple sclerosis (MS) patients lack timing precision. This makes it difficult to accurately measure psychomotor slowing, a central cognitive symptom of MS. Additionally, traditional batteries lack multiple alternate forms necessary to control for practice effects when assessing cognition over time. Finally such batteries are lengthy and expensive. Computerized neuropsychological batteries address many of these shortcomings. They measure response time more precisely, require less administration time, include alternate forms, and are ideal for rapid screening/triage. Although there are normative data on the reliability and validity of computerized measures, there have been no controlled validation studies with MS patients. The current study was designed to validate a computerized neuropsychological battery (ANAM) for use with relapsing-remitting (RR) MS patients. Prior to initiation of interferon-beta-1a (Avonex) treatment, subjects participated in a neuropsychological evaluation consisting of traditional and computerized measures. Moderate-to-high correlations were found between computerized and traditional measures. Computerized tests accurately predicted performance on key traditional tests. The battery was also concordant with traditional measures in identifying RR MS patients with and without neurocognitive impairment. Findings are discussed with respect to increased accuracy and accessibility of neuropsychological evaluations for MS patients.

Adolescent↗

PubMed2001

Alternate use of distinct intersubunit contacts controls GABAA receptor assembly and stoichiometry.

GABA(A) receptors are the major inhibitory transmitter receptors in the CNS. Recombinant GABA(A) receptors composed of alpha(1)beta(3)gamma(2) subunits have been demonstrated to assemble as pentamers consisting of two alpha(1), two beta(3), and one gamma(2) subunit. Using truncated and chimeric alpha(1) subunits, we identified the alpha(1)(80-100) sequence as a major binding site for gamma(2) subunits. In addition, we demonstrated its direct interaction with gamma(2)(91-104), a sequence that previously has been identified to form the contact to alpha(1) subunits. The observation that the amino acid residues alpha(1)P96 and alpha(1)H101, which can be photolabeled by [(3)H]flunitrazepam, are located within or adjacent to the alpha(1)(80-100) sequence, indicates that the benzodiazepine binding site of GABA(A) receptors is located close to this intersubunit contact. The observation that alpha(1)(80-100) interacts with gamma(2) but not with beta(3) subunits indicates the existence of an additional beta(3) binding site on alpha(1) subunits. The preferred alternate use of the gamma(2) and beta(3) binding sites in two different alpha(1) subunits of the same receptor ensures the incorporation of only a single gamma(2) subunit and thus, determines subunit stoichiometry of alpha(1)beta(3)gamma(2) receptors. Distinct binding sites and their alternate use can therefore explain how subunits of hetero-oligomeric transmembrane proteins assemble into a defined protein complex.

Amino Acid Sequence↗

PubMed2001

Presenilin-dependent gamma-secretase processing of beta-amyloid precursor protein at a site corresponding to the S3 cleavage of Notch.

The presenilin (PS)-dependent site 3 (S3) cleavage of Notch liberates its intracellular domain (NICD), which is required for Notch signaling. The similar gamma-secretase cleavage of the beta-amyloid precursor protein (betaAPP) results in the secretion of amyloid beta-peptide (Abeta). However, little is known about the corresponding C-terminal cleavage product (CTFgamma). We have now identified CTFgamma in brain tissue, in living cells, as well as in an in vitro system. Generation of CTFgamma is facilitated by PSs, since a dominant-negative mutation of PS as well as a PS gene knock out prevents its production. Moreover, gamma-secretase inhibitors, including one that is known to bind to PS, also block CTFgamma generation. Sequence analysis revealed that CTFgamma is produced by a novel gamma-secretase cut, which occurs at a site corresponding to the S3 cleavage of Notch.

Amino Acid Sequence↗

PubMed2001

Fimbria-mediated bacterial adhesion to human oral epithelium.

Oral mucosa biopsies and saliva samples from 12 individuals were processed for transmission (TEM) and scanning (SEM) electron microscopy with and without ruthenium red staining. Additionally performed microbiological estimations indicated in all bacteriological samples a facultative pathogenic flora. SEM and TEM investigation showed a diverse bacterial flora attached to the mucosal surface. Fimbriae comprising the glycocalyx and enabling bacterial attachment to the epithelial cells could be clearly visualised by ruthenium red. The only mode of bacterial attachment to the oral mucosa detected in the present investigation was fimbria-mediated adhesion and co-adhesion. The fimbria-mediated adhesion enables the bacterial persistence in the oral cavity and is the first step in the bacterial colonisation process.

Adult↗

PubMed2001

No evidence for in vivo regulation of midbrain serotonin transporter availability by serotonin transporter promoter gene polymorphism.

BACKGROUND: A polymorphism in the serotonin transporter promoter gene region (5-HTTLPR) has been shown to influence the quantity of serotonin transporter expressed in human cell lines: the 5-HTTLPR short allele (s) has been associated with reduced 5-HTT expression when compared to cells carrying the 5-HTTLPR long allele (l). We performed a single photon emission computed tomography (SPECT) study using the ligand [(123)I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)tropane ([(123)I]-beta-CIT) to measure 5-HTT availability in 16 healthy subjects genotyped for 5-HTTLPR. METHODS: SPECT scans were performed 24 hours after tracer injection, regions of interest anatomically corresponding to the thalamus-hypothalamus and mesencephalon-pons areas were compared to the binding in the cerebellum, representing the nondisplaceable [(123)I]-beta-CIT-binding (results expressed as target activity minus cerebellum activity/cerebellum activity). DNA from peripheral nuclear blood cells was genotyped for 5-HTTLPR using standard polymerase chain reaction methods. RESULTS: Specific binding ratios in the thalamus-hypothalamus were 2.65 +/- 0.4 in subjects with the l/l genotype (n = 3), 2.76 +/- 0.5 in subjects with the l/s genotype (n = 9), and 2.77 +/- 0.4 in subjects with the s/s genotype (n = 4). Binding ratios in the mesencephalon-pons were 1.43 +/- 0.3 (l/l; n = 3), 1.37 +/- 0.3 (l/s; n = 9), and 1.28 +/- 0.3 (s/s; n = 4). None of these differences was statistically significant. CONCLUSIONS: Our data provide no evidence for in vivo functional regulation of 5-HTT availability by 5-HTTLPR in the thalamus-hypothalamus and mesencephalon-pons of healthy subjects.

Adult↗

PubMed2001

Distribution of the major gamma-aminobutyric acid(A) receptor subunits in the basal ganglia and associated limbic brain areas of the adult rat.

Within the basal ganglia, gamma-aminobutyric acid (GABA) exerts a fundamental role as neurotransmitter of local circuit and projection neurons. Its fast hyperpolarizing action is mediated through GABA(A) receptors. These ligand-gated chloride channels are assembled from five subunits, which derive from multiple genes. Using immunocytochemistry, we investigated the distribution of 12 major GABA(A) receptor subunits (alpha1-5, beta1-3, gamma1-3, and delta) in the basal ganglia and associated limbic brain areas of the rat. Immunoreactivity for an additional subunit (subunit alpha6) was not observed. The striatum, the nucleus accumbens, and the olfactory tubercle displayed strong, diffuse staining for the subunits alpha2, alpha4, beta3, and delta presumably located on dendrites of the principal medium spiny neurons. Subunit alpha1-, beta2-, and gamma2-immunoreactivities were apparently mostly restricted to interneurons of these areas. In contrast, the globus pallidus, the entopeduncular nucleus, the ventral pallidum, the subthalamic nucleus, and the substantia nigra pars reticulata revealed dense networks of presumable dendrites of resident projection neurons, which were darkly labeled for subunit alpha1-, beta2-, and gamma2-immunoreactivities. The globus pallidus, ventral pallidum, entopeduncular nucleus, and substantia nigra pars reticulata, all areas receiving innervations from the striatum, displayed strong subunit gamma1-immunoreactivity compared to other brain areas. In the substantia nigra pars compacta and in the ventral tegmental area, numerous presumptive dopaminergic neurons were labeled for subunits alpha3, gamma3, and/or delta. This highly heterogeneous distribution of individual GABA(A) receptor subunits suggests the existence of differently assembled, and presumably also functionally different, GABA(A) receptors within individual nuclei of the basal ganglia and associated limbic brain areas.

Animals↗

PubMed2001

Detection and binding properties of GABA(A) receptor assembly intermediates.

Density gradient centrifugation of native and recombinant gamma-aminobutyric acid, type A (GABA(A)) receptors was used to detect assembly intermediates. No such intermediates could be identified in extracts from adult rat brain or from human embryonic kidney (HEK) 293 cells transfected with alpha(1), beta(3), and gamma(2) subunits and cultured at 37 degrees C. However, subunit dimers, trimers, tetramers, and pentamers were found in extracts from the brain of 8-10-day-old rats and from alpha(1)beta(3)gamma(2) transfected HEK cells cultured at 25 degrees C. In both systems, alpha(1), beta(3), and gamma(2) subunits could be identified in subunit dimers, indicating that different subunit dimers are formed during GABA(A) receptor assembly. Co-transfection of HEK cells with various combinations of full-length and C-terminally truncated alpha(1) and beta(3) or alpha(1) and gamma(2) subunits and co-immunoprecipitation with subunit-specific antibodies indicated that even subunits containing no transmembrane domain can assemble with each other. Whereas alpha(1)gamma(2), alpha(1)Ngamma(2), alpha(1)gamma(2)N, and alpha(1)Ngamma(2)N, combinations exhibited specific [(3)H]Ro 15-1788 binding, specific [(3)H]muscimol binding could only be found in alpha(1)beta(3) and alpha(1)beta(3)N, but not in alpha(1)Nbeta(3) or alpha(1)Nbeta(3)N combinations. This seems to indicate that a full-length alpha(1) subunit is necessary for the formation of the muscimol-binding site and for the transduction of agonist binding into channel gating.

Animals↗