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Biomedical subjects

B Koch

Publications and source records attributed to B Koch.

At least 19 recordsLinked to original sources
PubMed2007

Intracranial infantile hemangiomas associated with PHACE syndrome.

BACKGROUND AND PURPOSE: Head and neck infantile hemangiomas are common lesions that are rarely observed in an intracranial location. We report 4 patients with orbital infantile hemangiomas and ipsilateral enhancing intracranial lesions, presumed to be infantile hemangiomas. METHODS: Imaging studies and medical records of 4 infants with orbital hemangiomas and enhancing intracranial lesions were reviewed. The intracranial lesions were evaluated in terms of their location, signal intensity characteristics, enhancement pattern, and degree of involution following treatment. Additional findings associated with PHACE syndrome were also noted and a literature review of intracranial infantile hemangiomas and PHACE syndrome was also performed. RESULTS: The intracranial masses were primarily in or adjacent to the internal auditory canal and demonstrated imaging characteristics and treatment response similar to the ipsilateral orbital lesions. Ipsilateral internal carotid artery hypoplasia, ipsilateral cerebellar hemisphere hypoplasia, and/or other head and neck hemangiomas were present in all patients. CONCLUSION: These cases collectively support the diagnosis of intracranial infantile hemangiomas and suggest a unique radiographic association between PHACE syndrome and intracranial infantile hemangiomas.

Administration, Oral↗
PubMed2006

Skin tumors among employees of a tar refinery: the current data and their implications.

OBJECTIVE: Skin tumors and their preliminary stages may be recognized and compensated as an occupational disease only after exposure to soot, raw paraffin, tar, anthracene, pitch or similar substances. The presented study was carried out in one of the world's largest tar refineries and special attention was paid to the dermatological long-term effects and today's relevance of tar-induced skin lesions. METHODS: The data were generated by means of a standardized questionnaire based on occupational disease records and dermatological reports that have been carried out on a regular basis retrospectively. Among other things, the localization, the number and type of skin tumor, the date of diagnosis and the histological evaluation, where available, were taken into account. RESULTS: In a longitudinal analysis from 1946 to 2002, a total of n = 618 employees were examined. Squamous cell carcinomas n = 393, basal cell carcinomas n = 298, keratoacanthomas n = 194 and melanomas n = 6 were diagnosed. Latency periods for keratoacanthomas (median 29.5 years) and squamous cell carcinomas (median 28.0 years) were almost identical and could possibly imply that the pathomechanisms for both types of skin tumor might be comparable. Of the persons diagnosed, the skin tumors were mainly localized in the head region (n = 1,662). A remarkable divergence in the localization and distribution of the lesions was found when compared to the general population, for example the relative susceptibility of the upper lip (n = 67) compared to the lower lip (n = 31) as well as the less sun-exposed forearms (n = 381) compared to the back of the hand (n = 331), being typically preferred sites of squamous cell carcinomas. Furthermore, a discrepancy between the distribution of premalignant nonmelanoma skin tumors and carcinomas on the back of the nose, which is more exposed to the sun (n = 56) and those in the nostrils (n = 89), which are less exposed to the sun, but are in the act of breathing more exposed to tar, could be found. CONCLUSIONS: Tar-induced skin lesions are still of importance nowadays, which is reflected in the incidence of new cases and in the relapses of skin tumors. As a consequence, intensified measures are necessary, in the form of primary and secondary prevention. In view of the high incidence of malignant skin tumors in the general public, it is urgently necessary to take occupational hazards into consideration as well.

Adult↗
PubMed2006

Demonstration of a nanoparticle-based optical diode.

We present the operation of an optical device that exhibits diodelike properties based on two adjacent layers of quantum dots (QDs) encased in a fiber-optic jacket. The possibility of a multilayered device is also discussed. A significant change in the emission spectrum of CdSe/ZnS core-shell QDs was observed when excited by the input laser and the fluorescence of other CdSe/ZnS core-shell QDs. The output of the diode can be taken to be either the incoming laser wavelength of light similar to a conventional diode, or the output may be considered to be one of the QD fluorescence wavelengths. Current work has applications in biological fluorescence monitors and sensors as well as in telecommunications applications.

Journal Article↗
PubMed2006

Evolution of filament structures during edge-localized modes in the MAST Tokamak.

Edge-localized modes (ELMs) are repetitive instabilities that occur in the outer region of tokamak plasmas. This Letter provides new information on and the implications of the evolution of the filament structures observed during ELMs in the MAST tokamak. The filaments exist for the time over which particles are being released into the scrape off layer. They start off at the plasma edge rotating at the velocity of the pedestal, and then decelerate toroidally and accelerate radially outwards. As the filaments propagate radially they remain aligned with the local magnetic field line.

Journal Article↗
PubMed2005

The role of the human thalamus in processing corollary discharge.

Corollary discharge signals play an important role in monitoring self-generated movements to guarantee spatial constancy. Recent work in macaques suggests that the thalamus conveys corollary discharge information of upcoming saccades passing from the superior colliculus to the frontal eye field. The present study aimed to investigate the involvement of the thalamus in humans by assessing the effect of thalamic lesions on the processing of corollary discharge information. Thirteen patients with selective thalamic lesions and 13 healthy age-matched control subjects performed a saccadic double-step task in which retino-spatial dissonance was induced, i.e. the retinal vector of the second target and the movement vector of the second saccade were different. Thus, the subjects could not rely on retinal information alone, but had to use corollary discharge information to correctly perform the second saccade. The amplitudes of first and second saccades were significantly smaller in patients than in controls. Five thalamic lesion patients showed unilateral deficits in using corollary discharge information, as revealed by asymmetries compared with the other patients and controls. Three patients with lateral thalamic lesions including the ventrolateral nucleus (VL) were impaired contralaterally to the side of damage and one patient with a lesion in the mediodorsal thalamus (MD) was impaired ipsilaterally to the lesion. The largest asymmetry was found in a patient with a bilateral thalamic lesion. The results provide evidence for a thalamic involvement in the processing of corollary discharge information in humans, with a potential role of both the VL and MD nuclei.

Adult↗
PubMed2005

Multi-frequency high-field EPR studies on metal-substituted xylose isomerase.

The bacterial enzyme D-xylose isomerase (XI) catalyses the conversion of D-xylose to D-xylulose. Each subunit of the homotetrameric protein contains a bimetallic active centre requiring divalent metal ions such as Mg2+, Mn2+ or Co2+ for catalytic activity. We report here on XI in which the metal binding site 1 is specifically loaded with EPR active Mn2+, while binding site 2 is occupied by Co2+ or Cd2+, rendering a catalytically active or inactive species respectively. The Q-band (34 GHz) EPR spectra of these mixed-metal samples (Co2+/Mn2+ and Cd2+/Mn2+ XI) show a clear influence of the metal in site 2 on the Mn2+ EPR parameters. Likewise, a systematic increase of the zero field splitting parameters (zfs) of Mn2+ in site 1 upon incubation with the inhibitor xylitol or substrates for both mixed-metal samples is found. For Co2+/Mn2+ XI complexed with substrate, a drastic line broadening of the central -1/2 <--> +1/2 transition is observed in Q-band EPR, which was not amenable to analysis so far. By means of a multi-frequency approach at frequencies beyond Q-band, the relevant zfs parameters were derived from spectral simulations of EPR spectra measured at 94, 285 and 670 GHz. It is shown that parallel to the increase of the D-value its distribution also grows considerably in going from free Co2+/Mn2+ XI to the species complexed with inhibitor or substrate. For XI with bound substrate, D-values in the range of 70-90 mT and a distribution of about 30 mT were found from simulation trials. The large distribution in zfs values is thought to be correlated to the structural disorder induced by the shift of the metal ion of site 2 into a location necessary for the isomerisation reaction. The results are discussed with respect to high-resolution crystal data.

Aldose-Ketose Isomerases↗
PubMed2005

Patterns of interaction between Populus Esch5 and Piriformospora indica: a transition from mutualism to antagonism.

Piriformospora indica (Sebacinaceae, Basidiomycota) is an axenically cultivable, plant growth promoting root endophyte with a wide host range, including Populus. Rooting of Populus Esch5 explants started within 6 days after transfer to WPM medium. If such plantlets with roots were inoculated with P. indica, there was an increase in root biomass, and the number of 2nd order roots was increased significantly. A totally different observation was recorded when the explants were placed into WPM with pre-grown P. indica. The interaction led to complete blocking of root production and severely inhibited plant growth. Additionally, branched aerial roots appeared which did not penetrate the medium. On contact with the fungal colony or the medium, the ends of the aerial roots became inflated. Prolonged incubation stimulated the fungus to colonize aerial parts of the plant (stem and leaves). Mycelium not only spread on the surface of the aerial parts, but also invaded the cortical tissues inter- and intracellularly. Detached Populus leaves remained vital for 4 - 5 weeks on sterile agar media or on AspM medium with pre-grown P. indica. When the fungus was pre-grown on culture media such as WPM, containing ammonium as the main source of nitrogen, leaves in contact with the cultures turned brownish within 4 - 12 h. Thereafter, the leaves bleached, and about one day later had become whitish. Thus, cultural conditions could alter the behaviour of the fungus drastically: the outcome of the interaction between plant and fungus can be directed from mutualistic to antagonistic, characterized by fungal toxin formation and extension of the colonization to Populus shoots.

Basidiomycota↗
PubMed2005

The LuxR receptor: the sites of interaction with quorum-sensing signals and inhibitors.

The function of LuxR homologues as quorum sensors is mediated by the binding of N-acyl-L-homoserine lactone (AHL) signal molecules to the N-terminal receptor site of the proteins. In this study, site-directed mutagenesis was carried out of the amino acid residues comprising the receptor site of LuxR from Vibrio fischeri, and the ability of the L42A, L42S, Y62F, W66F, D79N, W94D, V109D, V109T and M135A LuxR mutant proteins to activate green fluorescent protein expression from a P(luxI) promoter was measured. X-ray crystallographic studies of the LuxR homologue TraR indicated that residues Y53 and W57 form hydrogen bonds to the 1-carbonyl group and the ring carbonyl group, respectively, of the cognate AHL signal. Based on the activity and signal specificity of the LuxR mutant proteins, and on molecular modelling, a model is suggested in which Y62 (corresponding to Y53 in TraR) forms a hydrogen bond with the ring carbonyl group rather than the 1-carbonyl group, while W66 (corresponding to W57 in TraR) forms a hydrogen bond to the 1-carbonyl group. This flips the position of the acyl side chain in the LuxR/signal molecule complex compared to the TraR/signal molecule complex. Halogenated furanones from the marine alga Delisea pulchra and the synthetic signal analogue N-(sulfanylacetyl)-L-homoserine lactone can block quorum sensing. The LuxR mutant proteins were insensitive to inhibition by N-(propylsulfanylacetyl)-L-homoserine lactone. In contrast, the mutations had only a minor effect on the sensitivity of the proteins to halogenated furanones, and the data strongly suggest that these compounds do not compete in a 'classic' way with N-3-oxohexanoyl-L-homoserine lactone for the binding site. Based on modelling and experimental data it is suggested that these compounds bind in a non-agonist fashion.

4-Butyrolactone↗
PubMed2004

Correlation between BMI, leisure habits and motor abilities in childhood (CHILT-project).

INTRODUCTION: The prevalence of childhood obesity is increasing with its negative medical and psychosocial consequences. This paper examines the association between body mass index (BMI), motor abilities and leisure habits of 668 children within the CHILT (Children's Health InterventionaL Trial) project. METHOD: A total of 668 children (51.0% boys; 49.0% girls) and their parents were questioned on sport and leisure behaviour of the children. The anthropometric data were measured. Motor abilities were determined by a body gross motor development test for children (Köperkoordinationstest für Kinder; KTK) and a 6-min run. RESULTS: The children were 6.70 +/- 0.42 y old, 122.72 +/- 5.36 cm tall and weighed 24.47 +/- 4.59 kg, the average BMI was 16.17 +/- 2.27 kg/m2. KTK showed an average motor quotient (MQ) of 93.49 +/- 15.01, the 6-min run an average of 835.24 +/- 110.87 m. Both tests were inversely correlated with BMI (KTK and BMI r=-0.164 (P<0.001); 6-min run and BMI r=-0.201 (P<0.001)); the group of overweight/obese children showed poorer results than the normal/underweight ones, even after adjustment for gender and age (in each case P<0.001). Children with the greatest extent of exercise achieve the highest MQ (P=0.035). SUMMARY: Overweight/obesity is associated with a poorer body gross motor development and endurance performance. On the other hand, an active lifestyle is positively correlated with a better gross motor development in first-grade children. Therefore, to prevent the negative consequences of physical inactivity and overweight/obesity early intervention to support exercise and movement is recommended.

Analysis of Variance↗
PubMed2004

Treatment of advanced Hodgkin's disease with COPP/ABV/IMEP versus COPP/ABVD and consolidating radiotherapy: final results of the German Hodgkin's Lymphoma Study Group HD6 trial.

BACKGROUND: The purpose of this study was to compare the efficacy of the hybrid chemotherapeutic regimen COPP/ABV/IMEP (cyclophosphamide-vincristine-procarbazine-prednisone-doxorubicin-bleomycin-vinblastine-ifosfamide-methotrexate-etoposide) (CAI) with that of the standard regimen COPP/ABVD (COPP/ABV, dacarbacine) (CA) in the treatment of advanced-stage Hodgkin's disease (HD). PATIENTS AND METHODS: Between January 1988 and January 1993, 588 eligible patients with HD in stages IIIB and IV were randomly assigned to a treatment or control group. The treatment group received four cycles of CAI over a complete cycle duration of 43 days. The control group received four cycles of CA over 57 days. Both groups then received consolidating radiotherapy. RESULTS: Five hundred and eighty-four patients were suitable for arm comparison. Patients in each group were similar in age, sex, histological subtype and clinical risk factors. Complete remission rates, overall survival and freedom from treatment failure at 7 years were similar for the two groups: 77% versus 78%, 73% versus 73% and 54% versus 56% for CAI and CA, respectively. Differences in acute chemotherapy-related toxicity were significant, however. Prognostic factor analysis confirmed the relevance of the International Prognostic Index and revealed that stage IVB, low hemoglobin, low lymphocyte count, high age and male gender were associated with a poor prognosis CONCLUSION: The rapidly alternating hybrid CAI did not give superior results when compared with the standard regimen CA in advanced-stage HD.

Adolescent↗
PubMed2003

An integrated gene annotation and transcriptional profiling approach towards the full gene content of the Drosophila genome.

BACKGROUND: While the genome sequences for a variety of organisms are now available, the precise number of the genes encoded is still a matter of debate. For the human genome several stringent annotation approaches have resulted in the same number of potential genes, but a careful comparison revealed only limited overlap. This indicates that only the combination of different computational prediction methods and experimental evaluation of such in silico data will provide more complete genome annotations. In order to get a more complete gene content of the Drosophila melanogaster genome, we based our new D. melanogaster whole-transcriptome microarray, the Heidelberg FlyArray, on the combination of the Berkeley Drosophila Genome Project (BDGP) annotation and a novel ab initio gene prediction of lower stringency using the Fgenesh software. RESULTS: Here we provide evidence for the transcription of approximately 2,600 additional genes predicted by Fgenesh. Validation of the developmental profiling data by RT-PCR and in situ hybridization indicates a lower limit of 2,000 novel annotations, thus substantially raising the number of genes that make a fly. CONCLUSIONS: The successful design and application of this novel Drosophila microarray on the basis of our integrated in silico/wet biology approach confirms our expectation that in silico approaches alone will always tend to be incomplete. The identification of at least 2,000 novel genes highlights the importance of gathering experimental evidence to discover all genes within a genome. Moreover, as such an approach is independent of homology criteria, it will allow the discovery of novel genes unrelated to known protein families or those that have not been strictly conserved between species.

Animals↗
PubMed2003

Does SPM 927 have an analgesic effect in human neuropathic pain? An open label study.

The aim of the study is to establish if the putative anticonvulsant SPM 927 has an analgesic effect in human neuropathic pain and to assess its tolerability. This is an open label study of 25 adult human subjects with resistant neuropathic pain. Subjects were treated with SPM 927 in a dose-escalating scheme to 600 mg daily, if tolerated. Treatment was continued for 4 weeks then withdrawn without tapering. Pain scores were recorded using a 11-point Likert score and a categorical pain-rating scale. Laboratory parameters and, electrocardiographs (ECGs) were collected; side effects were noted. Of the 25 enrolled subjects, 12 completed the study according to the protocol. The remaining subjects dropped out due to adverse events (n=12) or withdrawn consent. Mean daily pain scores (Likert score) fell by 0.83 (95% CI -1.77, +0.11) at the end of maintenance and rose by 0.58 (95% CI -0.23, +1.40) after withdrawal of SPM 927. Similar changes were seen in the categorical pain-rating scores. There were decreases in the mean scores for shooting pain, paraesthesia, and allodynia, but much less change in the numbness and burning-pain scores. The most common side effects were nausea, dizziness, leukocytosis, and increased ALT. No consistent changes in ECG recordings or haemodynamic variables were observed. SPM 927 may have an analgesic effect in human neuropathic pain and was reasonably well tolerated in this study. These data support the continued clinical development of SPM 927 for neuropathic pain.

Adult↗
PubMed2003

The APC E1317Q variant in adenomatous polyps and colorectal cancers.

Genetic susceptibility may play a role in many colorectal cancers (CRCs). Known syndromes such as familial adenomatous polyposis and hereditary nonpolyposis CRC account for <5% of CRCs. The germ-line missense variant of the APC gene, E1317Q, has been proposed to confer a risk for colonic adenomatous polyps (adenomas), but not for CRCs in the general population. These findings are contradictory and controversial. In the present study, 608 cases (377 patients with CRC, 145 patients with 4-100 lifetime adenomas, and 86 with < or =3 lifetime adenomas), and 679 controls (362 spouses and 317 patients with normal colonoscopy) were screened for the APC E1317Q variant. The frequency of heterozygotes for E1317Q among patients with CRC (2.4%), patients with 4-100 adenomas (1.4%), and < or =3 adenomas (3.5%) did not differ from spouse controls (2.8%). When CRC patients were examined by DNA mismatch repair status, age at onset (< or =age 50 versus >50), or family history of CRC, no differences in the frequency of E1317Q were found. The APC variant E1317Q does not appear to be associated with increased risk for colorectal neoplasia in the general population. However, when we used normal colonoscopy controls (E1317Q carrier frequency = 0.3%), the prevalence of E1317Q was significantly increased in CRC patients, in patients with < or =3 adenomas, and in CRC patients with intact mismatch repair status, suggesting a possible role for E1317Q in colorectal tumorigenesis. These results underscore the importance of carefully defining the controls to be used in comparisons of allele frequencies.

Adenoma↗
PubMed2002

A method for the rapid construction of cRNA standard curves in quantitative real-time reverse transcription polymerase chain reaction.

Quantification of nucleic acids, especially of mRNA, is increasingly important in biomedical research. The recently developed quantitative real-time polymerase chain reaction (PCR) - a highly sensitive technology for the rapid, accurate and reproducible quantification of gene expression - offers major advantages over conventional quantitative PCR. Transcript quantification is performed in the exponential phase of the PCR reaction through extrapolation of fluorescence signals from a standard calibration curve which represents the initial copy number for a given fluorescence signal. We have developed a method for gene transcript quantification which is based on a LightCycler - assisted real-time PCR in combination with a simple and rapid approach for the construction of external cRNA standards with identical gene sequences as the target gene. Synthesis of cRNAs was performed by in vitro transcription with T7 RNA polymerase followed by reverse transcription and real-time PCR. We applied this approach for transcript quantification of eukaryotic initiation factor 3 p110 (EIF3S8) mRNA in normal testicular tissue. We also present a rapid and simple strategy for the construction of cRNA standards for use in real-time PCR.

Adult↗
PubMed2001

Identification and biochemical characterization of Arabidopsis thaliana sulfite oxidase. A new player in plant sulfur metabolism.

In mammals and birds, sulfite oxidase (SO) is a homodimeric molybdenum enzyme consisting of an N-terminal heme domain and a C-terminal molybdenum domain (EC ). In plants, the existence of SO has not yet been demonstrated, while sulfite reductase as part of sulfur assimilation is well characterized. Here we report the cloning of a plant sulfite oxidase gene from Arabidopsis thaliana and the biochemical characterization of the encoded protein (At-SO). At-SO is a molybdenum enzyme with molybdopterin as an organic component of the molybdenum cofactor. In contrast to homologous animal enzymes, At-SO lacks the heme domain, which is evident both from the amino acid sequence and from its enzymological and spectral properties. Thus, among eukaryotes, At-SO is the only molybdenum enzyme yet described possessing no redox-active centers other than the molybdenum. UV-visible and EPR spectra as well as apparent K(m) values are presented and compared with the hepatic enzyme. Subcellular analysis of crude cell extracts showed that SO was mostly found in the peroxisomal fraction. In molybdenum cofactor mutants, the activity of SO was strongly reduced. Using antibodies directed against At-SO, we show that a cross-reacting protein of similar size occurs in a wide range of plant species, including both herbacious and woody plants.

Amino Acid Sequence↗
PubMed2001

Real-time genotyping of cytochrome P4501A1 A4889G and T6235C polymorphisms.

Single nucleotide polymorphisms, such as the cytochrome P450 1A1 (CYP1A1) A4889G and T6235C variants, have been reported to be associated with an increased cancer risk. In order to study their role in molecular-epidemiological studies, we developed a single-step procedure for genotyping these two CYP1A1 polymorphisms using real-time polymerase chain reaction (PCR) and subsequent melting curve analysis. Genotypes of 300 unrelated Caucasians, without prior history of cancer, were determined by real-time PCR and compared to genotypes obtained by restriction fragment length polymorphism PCR. In the population examined, the allele frequency of the CYP1A1 G allele at position 4889 was 0.042, and the frequency of the T allele at position 6235 was 0.10. Five percent of samples disagreed between methods. Sequence analysis of discordant samples revealed that the differences are likely attributed to incomplete digestion of amplicons by the RFLP method. These findings confirm the reliability and utility of real-time PCR as a method for large-scale genotyping.

Adult↗
PubMed2001

The plasminogen activator inhibitor 1 4G/5G polymorphism is not associated with longevity: a study in octogenarians.

Accumulating evidence suggests that plasma levels of the plasminogen activator inhibitor 1 (PAI-1) may modulate the risk of coronary artery disease. The regulation of PAI-1 levels underlies not only environmental but also genetic influences. The 4G/5G polymorphism of the PAI-1 gene has recently gained additional relevance as a possible cardiovascular risk factor, as the 4G allele may be associated with enhanced expression of the PAI-1 gene. This retrospective cohort study examined the effect of the PAI-1 4G/5G genotype on longevity among 205 subjects aged 80 years and older. Such studies in larger cohorts have recently become available along with new methods for the rapid and easy determination of gene polymorphisms. We utilized a light-cycler assisted method which is a fast and flexible method of analyzing the PAI-1 4G/5G polymorphism on the gene level. In these 205 persons the 4G/5G allele was found in 96 persons (47%), the 4G/4G variant in 62 (30%), and the 5G/5G allele in 47 (23%). These data are similar to the allele distribution described in other large cohorts not restricted to old age. Thus the results of this study are not suggestive of an important contribution of the PAI-1 genotype on total mortality.

Aged↗