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Biomedical subjects

G Böhm

Publications and source records attributed to G Böhm.

At least 37 records · Page 2Linked to original sources
PubMed1999

Multiple endometrial stromal nodules with sparse cysts and glands in the lung--a nodular variation of endometriosis that may mimic metastases of sarcoma.

We report an unusual case of a nodular variation of pulmonary endometriosis. To our knowledge, there is no previous report on a morphological investigation of this entity. The etiology of this rare condition is still a matter of discussion. The well-circumscribed nodular mass is composed of cells identical to, or closely resembling, those of endometrial stroma containing sparse cysts and glands. Immunohistochemically, the cells showed an extensive co-expression of cytokeratin AE1/AE3 and vimentin and were highly positive for progesterone receptor (PRICA) and estrogen receptor (ERICA). Cells lining the cysts and glands as a monolayer were reactive for Ber-Ep4, cytokeratin Pan and cytokeratin AE1/AE3 and negative to all other markers used including PRICA and ERICA. The differential diagnosis of this entity included fibrous tumor of the pleura and metastatic low-grade-endometrial-stromal-sarcoma. The morphological findings are correlated with immunohistochemical studies and results of cell image analysis. This study details the clinicopathological features of the nodular variation of pulmonary endometriosis.

Adult↗
PubMed1999

Closure of bronchopleural fistula after pneumonectomy with a pedicled intercostal muscle flap.

OBJECTIVES: The value of the pedicled intercostal muscle flap for the closure of postpneumonectomy bronchopleural fistulas was studied retrospectively. METHODS: Bronchopleural fistula was suspected in case of fever, cough, putrid or haemorrhagic expectoration, in combination with a rise of WBC and CRP. Fistula diagnosis was established bronchoscopically. Two patients underwent an initial trial of bronchoscopic sealing, the rest were reoperated immediately after fistula diagnosis. Immediately after operation antibiotic irrigation according to culture sensitivity was started via a single chest tube drainage twice a day. After instillation of antibiotics the drain was kept clamped for 3 h. Culture samples were obtained twice a week. Empyema was considered eradicated, if three subsequent cultures showed no bacterial growth. After drain removal the patients were kept in hospital for another week and observed for clinical signs of infection, WBC and CRP were controlled. Age, side, sex, histology, TNM-stage, duration of hospital stay after fistula diagnosis (days), duration of treatment (defined as the duration of chest tube drainage in days after operation), total hospital stay (including the initial hospital stay for primary resection and the hospital stay for fistula treatment in case of readmission), fistula size (mm), interval (days) between primary operation and fistula formation, and bacteriology were recorded. RESULTS: Eight patients (seven male) were treated. Age ranged from 46 to 70 years (mean 57.86). Six fistulas were located on the right side. All patients had non small cell lung cancer. Interval ranged from 2 to 72 days (mean 26.9 days). Fistula size ranged from 1 to 7 mm (mean 3.43). Seven fistulas were successfully closed. Duration of treatment lasted from 15 to 28 days in those patients treated successfully (mean 17). Hospital stay ranged from 15 to 31 days (mean 24.4). In one patient the flap became necrotic, he was successfully treated with total thoracoplasty. One patient died on the 38th day after rethoracotomy due to aspiration pneumonia. At postmortem examination the bronchial stump was closed. CONCLUSION: The use of the pedicled intercostal muscular flap is an efficient method for the closure of bronchopleural fistula after pneumonectomy.

Aged↗
PubMed1999

Cloning, overexpression, purification, and physicochemical characterization of a cold shock protein homolog from the hyperthermophilic bacterium Thermotoga maritima.

Thermotoga maritima (Tm) expresses a 7 kDa monomeric protein whose 18 N-terminal amino acids show 81% identity to N-terminal sequences of cold shock proteins (Csps) from Bacillus caldolyticus and Bacillus stearothermophilus. There were only trace amounts of the protein in Thermotoga cells grown at 80 degrees C. Therefore, to perform physicochemical experiments, the gene was cloned in Escherichia coli. A DNA probe was produced by PCR from genomic Tm DNA with degenerated primers developed from the known N-terminus of TmCsp and the known C-terminus of CspB from Bacillus subtilis. Southern blot analysis of genomic Tm DNA allowed to produce a partial gene library, which was used as a template for PCRs with gene- and vector-specific primers to identify the complete DNA sequence. As reported for other csp genes, the 5' untranslated region of the mRNA was anomalously long; it contained the putative Shine-Dalgarno sequence. The coding part of the gene contained 198 bp, i.e., 66 amino acids. The sequence showed 61% identity to CspB from B. caldolyticus and high similarity to all other known Csps. Computer-based homology modeling allowed the conclusion that TmCsp represents a beta-barrel similar to CspB from B. subtilis and CspA from E. coli. As indicated by spectroscopic analysis, analytical gel permeation chromatography, and mass spectrometry, overexpression of the recombinant protein yielded authentic TmCsp with a molecular weight of 7,474 Da. This was in agreement with the results of analytical ultracentrifugation confirming the monomeric state of the protein. The temperature-induced equilibrium transition at 87 degrees C exceeds the maximum growth temperature of Tm and represents the maximal Tm-value reported for Csps so far.

Bacterial Proteins↗
PubMed1999

Site-specific fluorescence labelling of recombinant polyomavirus-like particles.

For the development of gene therapy protocols based on polyomavirus-like particles, we describe a method for fluorescence labelling of virions in order to study virus-cell interactions preceding gene delivery. Site-specific fluorescence labelling of polyomavirus-like particles is achieved via a single cysteine residue and maleimide conjugates of fluorescence dyes (fluorescein, Texas Red). Polyomavirus-like particles can be assembled in vitro from recombinant capsomers produced in E. coli. Since the assembly process is independent of disulfide bond formation, all cysteine residues of the wild-type protein were replaced by serines, and a new unique cysteine residue was introduced for the attachment of the fluorescence marker.

Animals↗
PubMed1998

The stability of proteins in extreme environments.

Three complete genome sequences of thermophilic bacteria provide a wealth of information challenging current ideas concerning phylogeny and evolution, as well as the determinants of protein stability. Considering known protein structures from extremophiles, it becomes clear that no general conclusions can be drawn regarding adaptive mechanisms to extremes of physical conditions. Proteins are individuals that accumulate increments of stabilization; in thermophiles these come from charge clusters, networks of hydrogen bonds, optimization of packing and hydrophobic interactions, each in its own way. Recent examples indicate ways for the rational design of ultrastable proteins.

Archaea↗
PubMed1998

Homo-dimeric recombinant dihydrofolate reductase from Thermotoga maritima shows extreme intrinsic stability.

Dihydrofolate reductase (DHFR) from the hyperthermophilic bacterium Thermotoga maritima was cloned and expressed in Escherichia coli. Sequence determination of the reported dyrA gene was repeated, and a corrected version deposited in the nucleotide sequence databank (accession number Y11021). Ultracentrifugational analysis and gel permeation chromatography prove that the enzyme forms a stable homodimer. The enzyme exhibits long-term stability at physiological temperature (80 degrees C) and in the presence of high denaturant concentrations (half-time in 6 M guanidinium chloride: 24h). Alignments of DHFRS from different species, as well as comparative modeling based on the homology to the crystal structures of the enzyme from prokaryotes and eukaryotes, were used to generate a model of the three-dimensional structure. The apoenzyme was crystallized and a data set was collected to a resolution of about 2 A.

Amino Acid Sequence↗
PubMed1998

[Subjective causal scenarios for global environmental change].

Two studies are presented that investigate the assumptions that risk evaluation is based on subjective causal scenarios, and that the cognitive representation of global environmental risks is structured according to five causal levels: human attitudes, human activities, emissions or pollutions, environmental changes, and negative consequences. In study 1, 30 subjects listed in free-response format causes, consequences, and remedial measures for 14 environmental risks. Differences between predictive and diagnostic inferences were found: whereas subjects tend to assign immediate rather than mediated causes, they predominantly assign negative consequences for humans, irrespective of the length of the causal chain that leads to these consequences. In study 2, 41 subjects judged the overall similarity between 25 environmental risks. A multidimensional scaling analysis of these similarity judgments replicates the theoretically assumed five causal levels. Results of both studies support the assumptions that risk evaluation is based on implicit causal hypotheses and that the proposed five-level structure adequately describes the cognitive representation of environmental risks.

Adult↗
PubMed1997

Application of computer-assisted morphometry to the analysis of prenatal development of human lung.

Morphometry is well-established in tumour pathology. To evaluate is potential usefulness for description of developmental processes, histological slides from paraffin-embedded specimens of 67 human fetal lungs were Feulgen-stained, and morphometric characteristics of nuclei of epithelial pulmonary cells were analysed with an automated image analysis system. The measured cytometric features comprised of integrated optical density (IOD), S-phase-related IOD fraction, IOD entropy and nuclear area. Histometric features of the specimens were based upon the minimum spanning tree (MST) and included distances between neighboring epithelial cells, between epithelial cells and neighboring lymphocytes, and assessment of MST entropy. Notably, certain parameters revealed a non-uniform level during prenatal development S-phase-related IOD fraction increased from 5% to 8% between 14 and 16 weeks of gestation, then declined to 6% until birth. The IOD entropy steadily increased during development, whereas the extent of nuclear area remained constant. In accordance with an increase of the S-phase-related fraction the MST entropy displayed a singular peak between 14 and 16 weeks of gestation, which is probably associated with development of glandular structures in the lung. Correlation of expression of binding sites for markers, presumably involved in functional aspects of development, with such alterations, is shown for binding capacities of biotinylated fucoidan and the S-phase-related fraction. This may be helpful to infer immuno- or ligando histochemically defined tissue sites with potential physiological significance in morphometrically distinguished periods of development.

Cell Differentiation↗
PubMed1996

New approaches in molecular structure prediction.

In the past years, much effort has been put on the development of new methodologies and algorithms for the prediction of protein secondary and tertiary structures from (sequence) data; this is reviewed in detail. New approaches for these predictions such as neural network methods, genetic algorithms, machine learning, and graph theoretical methods are discussed. Secondary structure prediction algorithms were improved mostly by considering families of related proteins; however, for the reliable tertiary structure modeling of proteins, knowledge-based techniques are still preferred. Methods and examples with more or less successful results are described. Also, programs and parameterizations for energy minimisations, molecular dynamics, and electrostatic interactions have been improved, especially with respect to their former limits of applicability. Other topics discussed in this review include the use of traditional and on-line databases, the docking problem and surface properties of biomolecules, packing of protein cores, de novo design and protein engineering, prediction of membrane protein structures, the verification and reliability of model structures, and progress made with currently available software and computer hardware. In summary, the prediction of the structure, function, and other properties of a protein is still possible only within limits, but these limits continue to be moved.

Chemical Phenomena↗
PubMed1996

Instrumental or emotional evaluations: what determines preferences?

The present study investigated the separability of two evaluative aspects, instrumental and emotional utilities, and tested the hypothesis that situational context influences the relative impact of these evaluations in decision making. Twenty-nine subjects rank ordered eight options according to their preferences. The options were hypothetical prizes the subjects could win, either in a mail lottery (private context) or in a TV show (public context). Subjects rated all options on utility scales and indicated their emotional associations. It was hypothesized that in the private context condition subjects' preferences were more influenced by emotions, whereas due to justification demands, preferences were more influenced by instrumental considerations in the public context condition. A multidimensional preference analysis yielded two dimensions. The second of these dimensions distinguished between experimental conditions. An individual differences scaling analysis yielded significantly higher subject weights for the second dimension in the public context group. The first dimension could be interpreted as mapping positive versus negative emotions, whereas the second dimension reflected instrumental evaluations. Regression analyses indicate that both instrumental and emotional evaluations significantly contribute in predicting preferences, but that the relation between preferences and evaluative dimensions is only indirect.

Affect↗