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Biomedical subjects

Michael Schmid

Publications and source records attributed to Michael Schmid.

At least 19 recordsLinked to original sources
PubMed2007

Isolation and characterization of 1,2,4-trichlorobenzene mineralizing Bordetella sp. and its bioremediation potential in soil.

A soil which has been polluted with chlorinated benzenes for more than 25 years was used for isolation of adapted microorganisms able to mineralize 1,2,4-trichlorobenzene (1,2,4-TCB). A microbial community was enriched from this soil and acclimated in liquid culture under aerobic conditions using 1,2,4-TCB as a sole available carbon source. From this community, two strains were isolated and identified by comparative sequence analysis of their 16S-rRNA coding genes as members of the genus Bordetella with Bordetella sp. QJ2-5 as the highest homological strain and with Bordetella petrii as the closest related described species. The 16S-rDNA of the two isolated strains showed a similarity of 100%. These strains were able to mineralize 1,2,4-TCB within two weeks to approximately 50% in liquid culture experiments. One of these strains was reinoculated to an agricultural soil with low native 1,2,4-TCB degradation capacity to investigate its bioremediation potential. The reinoculated strain kept its biodegradation capability: (14)C-labeled 1,2,4-TCB applied to this inoculated soil was mineralized to about 40% within one month of incubation. This indicates a possible application of the isolated Bordetella sp. for bioremediation of 1,2,4-TCB contaminated sites.

Biodegradation, Environmental↗
PubMed2007

Attenuated induction of epithelial and leukocyte serine antiproteases elafin and secretory leukocyte protease inhibitor in Crohn's disease.

Elafin (or skin-derived antileukoprotease) and secretory leukocyte protease inhibitor (SLPI) are serine antiproteases antagonizing human neutrophil elastase (HNE), thereby preventing tissue injury from excessive release of proteolytic enzymes by inflammatory cells. Furthermore, elafin and SLPI are "defensin-like" molecules with broad antimicrobial activity. The balance between proteases and antagonists may critically determine inflammatory processes in Crohn's disease (CD) and ulcerative colitis (UC). Real-time PCR was performed to quantitate colonic, proinflammatory cytokine IL-8, protease (HNE), and antiprotease mRNA (elafin and SLPI) in a total of 340 biopsies from 117 patients (47 CD, 45 UC, 25 controls). Histological inflammation was scored, and HNE, elafin, and SLPI were localized and semiquantified by immunostaining in 51 colonic paraffin sections (23 CD, 11 UC, 17 controls). Proinflammatory IL-8, degree of histological inflammation, and granulocyte content were similar in UC and CD. Elafin stained predominantly in the epithelium and SLPI in mucosal inflammatory cells. HNE mRNA levels and immunostaining were increased equally in both forms of inflammatory bowel disease. Levels of mRNA and immunostaining of the antiproteases elafin and SLPI were enhanced strongly in inflamed versus noninflamed UC. It is surprising that comparing inflamed versus noninflamed CD, this increase was significantly less pronounced for elafin and even lacking for SLPI. Despite comparable degrees of inflammation and protease levels, the induction of both antiproteases was attenuated in CD. This could contribute to the transmural depth of tissue destruction in CD. Elafin and SLPI may be added to the list of defensin-like peptides with diminished induction in CD versus UC.

Adult↗
PubMed2006

The DNA sequence of medaka chromosome LG22.

We report the genomic DNA sequence of a single chromosome (linkage group 22; LG22) of the small teleost fish medaka (Oryzias latipes) as a first whole chromosome sequence from a non-mammalian vertebrate. The order and orientation of 633 protein-coding genes were deduced from 18,803,338 bp of DNA sequence, providing the opportunity to analyze chromosome evolution of vertebrate genomes by direct comparison with the human genome. The average number of genes in the "conserved gene cluster" (CGC), a strict definition of "synteny" at the sequence basis, between medaka and human was 1.6. These and other data suggest that approximately 38.8% of pair-wise gene relationships would have been broken from their common ancestor in the human and medaka lineages and further imply that approx 20,000 (15,520-23,280) breaks would have occurred from the entire genome of the common ancestor. These breaks were generated mainly by intra-chromosomal shufflings at a specific era in the vertebrate lineage. These precise comparative genomics allowed us to identify the pieces of ancient chromosomes of the common vertebrate ancestor and estimate chromosomal evolution in the vertebrate lineage.

Animals↗
PubMed2006

Genomic organization of the sex-determining and adjacent regions of the sex chromosomes of medaka.

Sequencing of the human Y chromosome has uncovered the peculiarities of the genomic organization of a heterogametic sex chromosome of old evolutionary age, and has led to many insights into the evolutionary changes that occurred during its long history. We have studied the genomic organization of the medaka fish Y chromosome, which is one of the youngest heterogametic sex chromosomes on which molecular data are available. The Y specific and adjacent regions were sequenced and compared to the X. The male sex-determining gene, dmrt1bY, appears to be the only functional gene in the Y-specific region. The Y-specific region itself is derived from the duplication of a 43-kb fragment from linkage group 9. All other coduplicated genes except dmrt1bY degenerated. The Y-specific region has accumulated large stretches of repetitive sequences and duplicated pieces of DNA from elsewhere in the genome, thereby growing to 258 kb. Interestingly the non-recombining part of the Y did not spread out considerably from the original duplicated fragment, possibly because of a large sequence duplication bordering the Y-specific fragment. This may have conserved the more ancestral structure of the medaka Y and provides insights into some of the initial processes of Y chromosome evolution.

Animals↗
PubMed2006

Coronary artery bypass graft (CABG) patency: assessment with high-resolution submillimeter 16-slice multidetector-row computed tomography (MDCT) versus coronary angiography.

PURPOSE: To investigate the ability of 16-slice multidetector-row computed tomography (MDCT) to visualize coronary artery bypass graft (CABG) patency and to detect bypass stenoses. MATERIALS AND METHODS: Thirty-two patients with 94 grafts (20 mammary artery grafts, 74 venous grafts) were investigated by 16-slice MDCT using a scan protocol with 12 x 0.75 mm slice collimation (pitch 0.3), 420 ms rotation time and simultaneous electrocardiogram (ECG)-registration. One hundred milliliters iodinated contrast agent were injected with a delay according to the individually determined contrast agent transit time. Patients with heart rates above 60 bpm received oral beta-blockade. Cross-sectional images with a slice width of 1.0 mm (0.5 mm increment) were reconstructed using an ECG-gated half-scan reconstruction or a multisegment reconstruction algorithm depending on the heart rate. Bypass grafts were evaluated concerning patency and presence of stenoses > or = 50% diameter reduction on cross-sectional images, multiplanar reformations and maximum intensity projections by two independent observers. Results were compared to coronary bypass angiography. RESULTS: Sixteen-slice MDCT results were compared to those of invasive coronary angiography concerning absence or presence of bypass graft occlusion or relevant stenosis > or = 50% lumen reduction. Coronary CT angiography (CTA) permitted detection of bypass occlusion with 100% sensitivity (28/28) and 98% specificity (64/65). Seventy-eight percent (observer 1) and 84% (observer 2) of all patent grafts were found to be evaluable concerning presence or absence of stenosis. In 34 of 40 (observer 1) and 38 of 43 (observer 2) bypass grafts, high-grade stenoses were correctly ruled out (specificity 85% versus 88%, sensitivity 80% and 82%). Yet, if all patients with either unevaluable grafts/graft anastomosis or relevant graft stenosis were excluded, only 8/32 patients (25%) had fully diagnostic "negative" graft-CTA. According to Kappa statistics, agreement between the observers was 1.0 and 0.93 concerning occlusion and relevant stenosis, respectively. CONCLUSION: Sixteen-slice coronary CTA with sub-millimeter spatial resolution and premedication with oral beta-blockade permits non-invasive assessment of coronary artery bypass grafts with decreasing numbers of unevaluable graft segments. However, patient-based analysis reveals that only a relatively small number of patients ("negative" and completely evaluable graft-CTA) truly profits from noninvasive work-up and could be spared invasive angiography.

Adult↗
PubMed2006

[Morphology and function of the intrinsic cardiac nervous system].

Access to the intrinsic cardiac autonomic nervous system can now be achieved via percutaneous catheter stimulation techniques. Thereby, cardiac functions like atrioventricular nodal conduction, sinus cycle length and ventricular inotropy can be dynamically regulated. The present article provides examples of this new technique in acute and chronic models but also first human applications.

Animals↗
PubMed2006

Herbaspirillum hiltneri sp. nov., isolated from surface-sterilized wheat roots.

The genus Herbaspirillum of the Betaproteobacteria mainly comprises diazotrophic bacteria with a potential for endophytic and systemic colonization of a variety of plants. The plant-associated bacterial isolates N3(T), N5 and N9 were derived from surface-sterilized wheat roots. After phylogenetic analysis of 16S rRNA gene sequence data the isolates could be allocated to the genus Herbaspirillum, and 99.9 % similarity to the sequence of Herbaspirillum lusitanum P6-12(T) was found. A set of 16S rRNA gene-targeted oligonucleotide probes was developed for the identification of the three novel isolates and H. lusitanum (Hhilu446), and for the specific detection of several other Herbaspirillum species described recently. For higher phylogenetic resolution, the 23S rRNA gene sequences of all members of the genus was sequenced and used to construct a phylogenetic tree. Isolates N3(T), N5 and N9 formed a group that was distinct from all other Herbaspirillum species. In addition, isolate N3(T) and H. lusitanum P6-12(T) exhibited a DNA-DNA hybridization value of only 25 %. The value for DNA-DNA hybridization between N3(T) and other members of the genus Herbaspirillum was between 14 and 32 %; DNA-DNA hybridization between strain N3(T) and isolates N5 and N9 produced values above 95 %. This places the three isolates as representatives of a novel species within the genus Herbaspirillum. A Biolog GN2 assay supported this conclusion. The major fatty acids were C(16 : 1)omega7c, C(16 : 0) and C(18 : 1)omega7c, and the DNA G+C content ranged from 60.9 to 61.5 mol%. Therefore these three isolates should be classified within a novel species, for which the name Herbaspirillum hiltneri sp. nov. is proposed. The type strain is N3(T) (=DSM 17495(T)=LMG 23131(T)).

DNA, Bacterial↗
PubMed2006

Induction of systemic resistance in tomato by N-acyl-L-homoserine lactone-producing rhizosphere bacteria.

N-acyl-L-homoserine lactone (AHL) signal molecules are utilized by Gram-negative bacteria to monitor their population density (quorum sensing) and to regulate gene expression in a density-dependent manner. We show that Serratia liquefaciens MG1 and Pseudomonas putida IsoF colonize tomato roots, produce AHL in the rhizosphere and increase systemic resistance of tomato plants against the fungal leaf pathogen, Alternaria alternata. The AHL-negative mutant S. liquefaciens MG44 was less effective in reducing symptoms and A. alternata growth as compared to the wild type. Salicylic acid (SA) levels were increased in leaves when AHL-producing bacteria colonized the rhizosphere. No effects were observed when isogenic AHL-negative mutant derivatives were used in these experiments. Furthermore, macroarray and Northern blot analysis revealed that AHL molecules systemically induce SA- and ethylene-dependent defence genes (i.e. PR1a, 26 kDa acidic and 30 kDa basic chitinase). Together, these data support the view that AHL molecules play a role in the biocontrol activity of rhizobacteria through the induction of systemic resistance to pathogens.

4-Butyrolactone↗
PubMed2006

In situ quantitation of the spatial scale of calling distances and population density-independent N-acylhomoserine lactone-mediated communication by rhizobacteria colonized on plant roots.

We used computer-assisted microscopy at single cell resolution to quantify the in situ spatial scale of N-acylhomoserine lactone (AHL)-mediated cell-to-cell communication of Pseudomonas putida colonized on tomato and wheat root surfaces. The results of this in situ quantification study on close-to-natural surfaces challenge the conventional view of a quorum group requirement of high cell densities for this type of bacterial communication. In situ image analysis indicated that the effective 'calling distance' on root surfaces was most frequent at 4-5 microm, extended to 37 microm in the root tip/elongation zone and further out to 78 microm in the root hair zone. The spatial scale of these calling distances is very long-range in proportion to the size of individual bacteria. Geostatistical modeling analysis implicated the importance of AHL-gradients mediating effective communication between remote cells. We conclude that AHL-mediated cell-to-cell communication occurs not only within dense populations, but also in very small groups and over long ranges between individual bacteria, and therefore this cellular activity is more commonplace and effective than hitherto predicted. We propose that this cell-to-cell communication is governed more by the in situ spatial proximity of cells within AHL-gradients than the requirement for a quorum group of high population density.

4-Butyrolactone↗
PubMed2006

Colonization of barley (Hordeum vulgare) with Salmonella enterica and Listeria spp.

Colonization of barley plants by the food-borne pathogens Salmonella enterica serovar typhimurium and three Listeria spp. (L. monocytogenes, L. ivanovii, L. innocua) was investigated in a monoxenic system. Herbaspirillum sp. N3 was used as a positive control and Escherichia coli HB101 as a negative control for endophytic root colonization. Colonization of the plants was tested 1-4 weeks after inoculation by determination of CFU, specific PCR assays and fluorescence in situ hybridization (FISH) with fluorescently labelled oligonucleotide probes in combination with confocal laser scanning microscopy (CLSM). Both S. enterica strains were found as endophytic colonizers of barley roots and reached up to 2.3 x 10(6) CFU per g root fresh weight after surface sterilization. The three Listeria strains had 10-fold fewer cell numbers after surface sterilization on the roots and therefore were similar to the results of nonendophytic colonizers, such as E. coli HB101. The FISH/CSLM approach demonstrated not only high-density colonization of the root hairs and the root surface by S. enterica but also a spreading to subjacent rhizodermis layers and the inner root cortex. By contrast, the inoculated Listeria spp. colonized the root hair zone but did not colonize other parts of the root surface. Endophytic colonization of Listeria spp. was not observed. Finally, a systemic spreading of S. enterica to the plant shoot (stems and leaves) was demonstrated using a specific PCR analysis and plate count technique.

Hordeum↗
PubMed2005

Visualization of coronary artery anomalies by contrast-enhanced multi-detector row spiral computed tomography.

BACKGROUND: We investigated the potential of 16-slice multi-detector row spiral CT (MDCT) with retrospective ECG-gating for evaluation of coronary artery anomalies. METHODS: A total of 35 patients (23 men, 12 women, 19-81 years) in whom anomalous coronary arteries had been detected by invasive coronary angiography underwent MDCT (Sensation 16, Siemens, Germany). During one breathhold, a contrast-enhanced (90 ml, 5 ml/s) volume data set of the heart was acquired (16x0.75mm collimation, gantry rotation 375 ms). Images were reconstructed with a slice thickness of 1.0 mm in 0.5-mm intervals using retrospective ECG-gated reconstruction. The 35 data sets and 80 data sets of patients with angiographically normal coronary anatomy were analysed in random order concerning the origin and course of the coronary arteries. The results were compared to invasive coronary angiography. RESULTS: All patients with coronary artery anomalies and all controls with normal coronary anatomy were identified by MDCT. In addition, the origins and course concerning their anatomical relationship to adjacent cardiac structures were visualized in all patients, including right-sided origin of the left main (n=10), left anterior descending coronary artery (n=4) or left circumflex coronary artery (n=10); left-sided origin of the right coronary artery (n=6); four coronary fistula to the pulmonary artery (two from the left anterior descending, one from the right coronary artery, one from the left main), and one fistula from the circumflex coronary artery to the left atrium CONCLUSIONS: The study demonstrates that MDCT is a reliable noninvasive technique to identify and define anomalous coronary arteries and their course.

Adult↗
PubMed2005

Selective increase of cardiac neuronal sympathetic tone: a catheter-based access to modulate left ventricular contractility.

OBJECTIVES: This study was designed to develop a technique to selectively increase the sympathetic tone to the heart by cardiac sympathetic nerve stimulation (SNS). BACKGROUND: Access to the cardiac sympathetic neurons may allow modulating the adrenergic tone of the heart while avoiding systemic side effects. METHODS: Cardiac sympathetic nerves course within neural sleeves along the subclavian artery. Because of this proximity, transvascular SNS was attempted with electrode catheters inside the subclavian artery in 16 pigs. RESULTS: Right/left (R-/L-) SNS (20 Hz) during ventricular pacing at 200/min evoked a >100% increase of left ventricular systolic pressure (baseline: 51 +/- 1 mm Hg; L-SNS: 118 +/- 26 mm Hg; R-SNS: 116 +/- 33 mm Hg; p < 0.001) while systemic vascular resistance remained unchanged. There was a sigmoid dose-response curve with rapid on- and offset of the effect during SNS initiation/cessation. Positive inotropic effects persisted for 12 h of continued SNS (n = 4). Besides positive dromotropic effects, L-SNS/R-SNS yielded a 41% and 77% sinus rate increase, respectively. CONCLUSIONS: The neural adrenergic tone to the heart can be selectively increased by catheter stimulation of cardiac efferent sympathetic nerves.

Animals↗
PubMed2005

Structure of the ultrathin aluminum oxide film on NiAl(110).

The well-ordered aluminum oxide film formed by oxidation of the NiAl(110) surface is the most intensely studied metal surface oxide, but its structure was previously unknown. We determined the structure by extensive ab initio modeling and scanning tunneling microscopy experiments. Because the topmost aluminum atoms are pyramidally and tetrahedrally coordinated, the surface is different from all Al2O3 bulk phases. The film is a wide-gap insulator, although the overall stoichiometry of the film is not Al2O3 but Al10O13. We propose that the same building blocks can be found on the surfaces of bulk oxides, such as the reduced corundum (0001) surface.

Journal Article↗
PubMed2005

SKY and genetic fingerprinting reveal a cross-contamination of the putative normal colon epithelial cell line NCOL-1.

In vitro studies addressing the primary prevention of colon carcinoma are preferably conducted using normal colonic cells, because these cells are more likely to represent the potential target for prevention in vivo. Established cell lines of normal colonic origin are mostly lacking; however, this is probably due to the difficulties associated with establishment of such cell lines. Cross-contamination with malignant cells is a frequent event, and so any successfully established cell line of normal origin should be scrutinized prior to further investigation. We performed a cytogenetic (spectral karyotyping) and genetic fingerprint (Promega PowerPlex ES multiplex system and Applied Biosystems AmpFlSTR SGM Plus multiplex system) analysis of the putative normal colon epithelial cell line NCOL-1, derived from two different sources (NCOL-1a and 1b). We show that NCOL-1a and 1b are probably derived from the colon carcinoma cell line LoVo, with a matching probability of 99.9995, most probably through cross-contamination. Karyotypes of LoVo and NCOL-1a were identical; NCOL-1b displayed additional marker chromosomes. Our findings highlight the importance of molecular and cytogenetic characterization of established cell lines to avoid drawing misleading conclusions from the original findings.

Cell Line↗
PubMed2005

Multiple origins of tetraploid taxa in the Eurasian Bufo viridis subgroup.

We used Q-banding and analyzed nucleolar organizing regions (NORs) to study the cytogenetic evolution of tetraploids within the Palearctic Bufo viridis subgroup, the only known amphibian complex comprising di-, tri- and tetraploid bisexually reproducing taxa. We examined three diploid (2n) nominal taxa (Bufo viridis viridis, B. v. turanensis, B. v. kermanensis) from five Eurasian localities and six tetraploid (4n) nominal taxa (B. oblongus, B. o. danatensis, B. pewzowi pewzowi, B. p. taxkorensis, B. p. unicolor, B. p. strauchi) from eight Central Asian localities. Homeologous chromosomes of 2n and 4n toads exhibit a similar morphology. Silver-staining and in situ hybridization revealed terminal NORs in the long arms of chromosomes 6 in all 2n but in only two out of four chromosomes 6 in all 4n taxa. Q-banding and a rapidly evolving mitochondrial marker suggest at least two origination events for Asian 4n toads: "Western Central Asian tetraploids" (B. oblongus Nikolsky, 1896) exhibit distinct differences within some chromosome quartets, which are divisible into pairs of chromosomes and may be allopolyploid. In contrast, "Central Asian tetraploids" (B. pewzowi Bedriaga, 1898) showed homogenous Q-banding patterns within each quartet, suggesting autopolyploidy. In Northeastern Iran, we discovered a zone of either common ancestry or hybridization of 2n and Western Central Asian 4n toads. This raises intriguing questions about how diploid and tetraploid taxa may evolve by exchanging genetic material.

Animals↗
PubMed2005

Chicken orthologues of mammalian imprinted genes are clustered on macrochromosomes and replicate asynchronously.

In the chicken genome, most orthologues of mouse imprinted genes are clustered on macrochromosomes. Only a few orthologues are located in the microchromosome complement. Macrochromosomal and, to a lesser extent, microchromosomal regions containing imprinted gene orthologues exhibit asynchronous DNA replication. We conclude that highly conserved arrays of imprinted gene orthologues were selected during vertebrate evolution, long before these genes were recruited for parent-specific gene expression by genomic imprinting mechanisms. Evidently, the macrochromosome complement provides a better chromatin environment for the establishment of asynchronous DNA replication and imprinted gene expression later in evolution than microchromosomes.

Animals↗
PubMed2005

Comparative in situ analysis of ipdC-gfpmut3 promoter fusions of Azospirillum brasilense strains Sp7 and Sp245.

Inoculation of wheat roots with Azospirillum brasilense results in an increase of plant growth and yield, which is proposed to be mainly due to the bacterial production of indole-3-acetic acid in the rhizosphere. Field inoculation experiments had revealed more consistent plant growth stimulation using A. brasilense strain Sp245 as compared with the strain Sp7. Therefore, the in situ expression of the key gene ipdC (indole-3-pyruvate decarboxylase) was examined in these two strains. Within the ipdC promoter of strain Sp245 a region of 150 bases was identified, which was missing in strain Sp7. Thus, three different translational ipdC promoter fusions with gfpmut3 were constructed on plasmid level: the first contained the part of the Sp245 promoter region homologous to strain Sp7, the second was bearing the complete promoter region of Sp245 including the specific insertion and the third comprised the Sp7 promoter region. By comparing the fluorescence levels of these constructs after growth on mineral medium with and without inducing amino acids, it could be demonstrated that ipdC expression in A. brasilense Sp245 was subject to a stricter control compared with strain Sp7. Microscopic detection of these reporter strains colonizing the rhizoplane documented for the first time an in situ expression of ipdC.

Azospirillum brasilense↗