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Biomedical subjects

B Weimer

Publications and source records attributed to B Weimer.

13 recordsLinked to original sources
PubMed2006

Comparative genomics of the lactic acid bacteria.

Lactic acid-producing bacteria are associated with various plant and animal niches and play a key role in the production of fermented foods and beverages. We report nine genome sequences representing the phylogenetic and functional diversity of these bacteria. The small genomes of lactic acid bacteria encode a broad repertoire of transporters for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities that indicate both prototrophic and auxotrophic strains. Phylogenetic analyses, comparison of gene content across the group, and reconstruction of ancestral gene sets indicate a combination of extensive gene loss and key gene acquisitions via horizontal gene transfer during the coevolution of lactic acid bacteria with their habitats.

Animals↗
PubMed1999

Isolation and characterization of acid- and bile-tolerant isolates from strains of Lactobacillus acidophilus.

Lactic acid bacteria have been reported to be useful as a health adjunct and are commonly added to food as the delivery mechanism. The literature contains many conflicting observations for their proposed benefits, and the mechanism of action is undefined. One source of variation is the large number of strains used without proper controls supplemented. Additionally, many of the organisms are not characterized for their acid shock response or the acid-tolerance response, which are known to vary among bacterial species. Our objective was to isolate acid-resistant and bile-resistant variants of Lactobacillus acidophilus and to determine the phenotypic changes. The acid- and bile-tolerant isolates were obtained using natural selection techniques after sequential exposure to hydrochloric acid (pH 3.5 to 7.0) and mixed bile salts. The acid- and bile-tolerant isolates retained their ability to grow at pH 3.5 with 0.3% bile after the selective pressure was removed and reapplied. Isolates varied from their parents for stability in freezing, lactose utilization, protease activity, aminopeptidase activity, plasmid profile, and cell-wall fatty acid profile. These data suggest that the isolated acid- and bile-tolerant isolates possess growth advantages over that of the parents under stress conditions and may be considered as candidates for probiotic strains after further characterization with animal models.

Aminopeptidases↗
PubMed1999

[Reference values of hemosiderin-laden alveolar macrophages in bronchoalveolar lavage in children].

Pulmonary haemosiderosis is a rare disease of unknown etiology, mainly affecting children and adolescents. Pulmonary haemosiderosis may occur in association with several respiratory or other disease (Lupus erythematosus, Goodpastures syndrome). Delay in diagnosing can lead to fatal complications. BAL appears to be the method of choice to detect haemosiderin-laden macrophages. No reference values are available for children to date. 64 bronchoalveolar lavages were performed to establish reference values of haemosiderin-laden macrophages in children. Less haemosiderin was found in children compared to adults, and hence a new haemosiderin score was established for paediatric patients. Compared to healthy children, no elevated haemosiderine levels were found in children with chronic pulmonary disease such as bronchiectasis or chronic aspiration caused by gastro-oesophageal reflux. Therefore even a mildly increased amount of haemosiderin-laden macrophages in children requires medical attention.

Adolescent↗
PubMed1999

[Severe interstitial lung disease from pathologic gastroesophageal reflux in children].

Interstitial lung diseases comprise a heterogeneous group of pulmonary conditions that cause restrictive lung disease of poor prognosis, especially if growth failure, pulmonary hypertension and fibrosis appears. We report on the case of a girl of 11 years of age who suffered from severe nonallergic asthma in early childhood and who developed severe interstitial pulmonary disease caused by gastro-oesophageal reflux at the age of 8 years. This diagnosis was established by lung biopsy, bronchoalveolar lavage and a high amount of lipid-laden alveolar macrophages, 2-level pH measurement and oesophageal biopsy. Because therapy with oral and inhaled steroids failed and Omeprazol showed benificial effects, hemifundoplication according to THAL was performed. At present the lung function is clearly normal and there is no need of any medicaments. Following the history, we can assume the pathological gastro-oesophageal reflux to be the cause of the disease. It is important to state that there were no typical symptoms at any time pointing to gastro-oesophageal reflux disease. The development of pulmonary disease by pathological reflux is very often caused by "silent aspiration". Very typically there are no symptoms such as vomiting, heartburn and pain but only signs of chronic lung disease.

Asthma↗
PubMed1998

Conversion of methionine to thiols by lactococci, lactobacilli, and brevibacteria

Methanethiol has been strongly associated with desirable Cheddar cheese flavor and can be formed from the degradation of methionine (Met) via a number of microbial enzymes. Methionine gamma-lyase is thought to play a major role in the catabolism of Met and generation of methanethiol in several species of bacteria. Other enzymes that have been reported to be capable of producing methanethiol from Met in lactic acid bacteria include cystathionine beta-lyase and cystathionine gamma-lyase. The objective of this study was to determine the production, stability, and activities of the enzymes involved in methanethiol generation in bacteria associated with cheese making. Lactococci and lactobacilli were observed to contain high levels of enzymes that acted primarily on cystathionine. Enzyme activity was dependent on the concentration of sulfur amino acids in the growth medium. Met aminotransferase activity was detected in all of the lactic acid bacteria tested and alpha-ketoglutarate was used as the amino group acceptor. In Lactococcus lactis subsp. cremoris S2, Met aminotransferase was repressed with increasing concentrations of Met in the growth medium. While no Met aminotransferase activity was detected in Brevibacterium linens BL2, it possessed high levels of L-methionine gamma-lyase that was induced by addition of Met to the growth medium. Met demethiolation activity at pH 5.2 with 4% NaCl was not detected in cell extracts but was detected in whole cells. These data suggest that Met degradation in Cheddar cheese will depend on the organism used in production, the amount of enzyme released during aging, and the amount of Met in the matrix.

Journal Article↗
PubMed1998

Purification and characterization of L-methionine gamma-lyase from brevibacterium linens BL2

L-Methionine gamma-lyase (EC 4.4.1.11) was purified to homogeneity from Brevibacterium linens BL2, a coryneform bacterium which has been used successfully as an adjunct bacterium to improve the flavor of Cheddar cheese. The enzyme catalyzes the alpha,gamma elimination of methionine to produce methanethiol, alpha-ketobutyrate, and ammonia. It is a pyridoxal phosphate-dependent enzyme, with a native molecular mass of approximately 170 kDa, consisting of four identical subunits of 43 kDa each. The purified enzyme had optimum activity at pH 7.5 and was stable at pHs ranging from 6.0 to 8.0 for 24 h. The pure enzyme had its highest activity at 25 degreesC but was active between 5 and 50 degreesC. Activity was inhibited by carbonyl reagents, completely inactivated by DL-propargylglycine, and unaffected by metal-chelating agents. The pure enzyme had catalytic properties similar to those of L-methionine gamma-lyase from Pseudomonas putida. Its Km for the catalysis of methionine was 6.12 mM, and its maximum rate of catalysis was 7.0 &mgr;mol min-1 mg-1. The enzyme was active under salt and pH conditions found in ripening Cheddar cheese but susceptible to degradation by intracellular proteases.

Journal Article↗
PubMed1998

[Pulmonary hemosiderosis and gastroesophageal reflux in an infant].

Pulmonary hemosiderosis (PH) has been described in association with a variety of immunological and non-immunological diseases. It is characterised by iron-deficiency anaemia, hemoptysis and diffuse pulmonary infiltrates based on recurrent intraalveolar hemorrhages. We present the case of a child with pulmonary hemosiderosis and a pathological gastroesophageal reflux activity. The child suffered from recurrent anaemic episodes the age of three months (hemoglobin level up to 5.4 g/dl). The symptoms decreased after removal of the gastroesophageal reflux and accompanying steroid therapy. There has been one relapse of pulmonary hemorrhage seven months later (hemoglobin level 6.1 g/dl). Since then the patient has been in good general condition and the steroid was slowly reduced. No more anaemic episodes occurred. We discuss a possible association of pathological gastroesophageal reflux activity in pulmonary hemosiderosis.

Bronchoalveolar Lavage Fluid↗
PubMed1992

Structure and chromosomal localization of the human gene for a brain form of prostaglandin D2 synthase.

We have cloned and characterized the human gene for the 21-kDa brain form of prostaglandin D2 synthase. The gene was isolated from a human genomic lambda library and spans 3600 base pairs. It consists of seven exons and six introns. Southern blot analysis indicates that there is a single copy of the gene in the haploid genome. The transcriptional start site was mapped to a G residue 74 base pairs 5' of the ATG initiation codon. A TATA box-like element (ATAAATA) is situated 21 base pairs upstream of the mRNA start site. The gene was mapped to chromosome 9 bands q34.2-q34.3. The gene bears close resemblance to the genes for murine major urinary protein and ovine beta-lactoglobulin.

Amino Acid Sequence↗
PubMed1987

[Immunoscintigraphy using 111In-DTPA-labeled monoclonal antibodies: comparison with ECT and planar scintigraphy].

The present study was done in order to examine if the use of 111In-DTPA-labeled MAb fragments in place of 131I-labeled MAb fragments increases the sensitivity of tomographic immunoscintigraphy to reach the level of that of planar imaging techniques. In 11 patients with various primary tumors, local recurrences or metastases [colorectal carcinoma (n = 7), ovarian carcinoma (n = 2), papillary thyroid carcinoma (n = 1), undifferentiated carcinoma of the lung (n = 1)], immunoscintigraphy (IS) was carried out using 111In-DTPA-labeled F(ab')2 fragments of various MAbs (anti-CEA, OC 125, anti-hTG) and planar and tomographic imaging were compared intra-individually. By conventional diagnostic procedures, the presence of a tumor mass was confirmed (transmission computer tomography, ultrasound) or verified (131I whole-body scintigraphy, histology) in all cases. Immunoscintigraphy was positive in 9 out of 11 cases by ECT and in 10 out of 11 cases by planar imaging. When using 111In-labeled MAb fragments, intra-individual comparison of ECT and planar imaging resulted in a similar sensitivity. The increased sensitivity of ECT using this tracer in contrast to 131I-labeled MAb fragments may be attributed to the fact that the physical properties of 111In are much more suitable for the gamma cameras most commonly used (single detector, 3/8'' crystal); using 111In-labeled MAb fragments, count rates sufficient for ECT can be obtained within a reasonable acquisition time. This allows to combine IS with the advantages of ECT regarding tumour localization and prevention of artefacts due to superposition of background.

Adult↗
PubMed1984

Symbolic coordinate anatomy for neurology (SCAN).

Our laboratory is responsible for development and maintenance of CADUCEUS (Formerly INTERNIST-1), a computer program to provide expert advice to the clinician in the realm of medical diagnosis. In order to extend its success in internal medicine into neurology, it was necessary to provide a paradigm for neuroanatomic reasoning. In our anatomic knowledge base (SCAN), the nervous system is partitioned into a hierarchical set of nested cubes. In the computer memory, a symbol for each cube has attached to it lists of structures that are wholly or partially within the cube. The structures may be simple (e.g., right locus ceruleus) or complex (e.g., midbrain). Lists of cubes belonging to particular vascular territories as well as systems (e.g., visual) are also maintained. Thus, computation of anatomic localization from a given symptom or finding is facilitated as well as characterization of consequences of vascular lesions or neighborhood effects from mass lesions.

Anatomy↗
PubMedDate not supplied

Sulfur metabolism in bacteria associated with cheese.

Metabolism of sulfur in bacteria associated with cheese has long been a topic of interest. Volatile sulfur compounds, specifically methanethiol, are correlated to desirable flavor in Cheddar cheese, but their definitive role remains elusive. Only recently have enzymes been found that produce this compound in bacteria associated with cheese making. Cystathionine beta- and gamma-lyase are found in lactic acid bacteria and are capable of producing methanethiol from methionine. Their primary function is in the metabolism of cysteine. Methionine gamma-lyase produces methanethiol from methionine at a higher efficiency than the cystathionine enzymes. This enzyme is found in brevibacteria, bacilli, and pseudomonads. Addition of brevibacteria containing this enzyme improves Cheddar cheese flavor. Despite recent progress in sulfur metabolism more information is needed before cheese flavor associated with sulfur can be predicted or controlled.

Amino Acids, Sulfur↗