Biomedical subjects

Norbert Weiss

Publications and source records attributed to Norbert Weiss.

33 records · Page 2Linked to original sources

PubMed2003

Characterization of novel psychrophilic clostridia from an Antarctic microbial mat: description of Clostridium frigoris sp. nov., Clostridium lacusfryxellense sp. nov., Clostridium bowmanii sp. nov. and Clostridium psychrophilum sp. nov. and reclassification of Clostridium laramiense as Clostridium estertheticum subsp. laramiense subsp. nov.

Taxonomic studies were performed on four strains (D-1/D-an/IIT, C/C-an/B1T, A-1/C-an/C1T and A-1/C-an/IT) of anaerobic, gram-positive, spore-forming bacteria originally isolated from a mat sample retrieved from a shallow, moated area around Lake Fryxell, an Antarctic freshwater lake. Phylogenetic analyses based on 16S rRNA gene sequence data indicated that these strains are affiliated with cluster I clostridia and form a coherent group with Clostridium estertheticum and Clostridium laramiense. Similarity values among 16S rRNA gene sequences within this assemblage ranged between 96.7 and 99.8%. Despite the close phylogenetic relationship, several distinguishing phenotypic traits were found among the novel strains using a polyphasic approach. All strains were psychrophilic, but the temperature optimum for growth differed markedly, ranging from 4 to 16 degrees C. In addition, substrate utilization patterns, fermentation end products, cellular fatty acid profiles and morphological traits enabled a clear differentiation between the strains. DNA-DNA hybridization experiments revealed that each of the four novel strains represents a distinct species, with DNA-DNA similarity values to related strains in the range 16-62%. In contrast, the type strains of C. estertheticum and C. laramiense shared 79% DNA-DNA similarity, indicating a close relationship at the species level. On the basis of genetic and phenotypic properties, it is proposed to designate four novel species of the genus Clostridium to harbour the newly isolated strains: Clostridium frigoris sp. nov. (type strain D-1/D-an/IIT=DSM 14204T=ATCC BMAA-579T), Clostridium lacusfryxellense sp. nov. (type strain C/C-an/B1T=DSM 14205T=ATCC BAA-580T), Clostridium bowmaniisp. nov. (type strain A-1/C-an/C1T=DSM 14206T=ATCC BAA-581T) and Clostridium psychrophilum sp. nov. (type strain A-1/C-an/IT=DSM 14207T=ATCC BAA-582T). It is also proposed to unite C. laramiense and C. estertheticum under C. estertheticum. The subspecies C. estertheticum subsp. laramiense subsp. nov. is established, represented by strain ATCC 51254T (=DSM 14884T). The type strain of C. estertheticum subsp. estertheticum remains NCIMB 12511T (=DSM 8809T).

Antarctic Regions↗

PubMed2003

Planococcus maritimus sp. nov., isolated from sea water of a tidal flat in Korea.

Two Gram-positive, motile cocci, strains TF-9(T) and TF-16, were isolated from sea water of a tidal flat in Korea. Phylogenetic analysis based on 16S rDNA sequences showed that the strains fall within the radiation of the cluster comprising Planococcus citreus and Planococcus kocurii, and this cluster joined the clade comprising Planomicrobium species and Planococcus alkanoclasticus and Planococcus psychrophilus with a high bootstrap resampling value. Strains TF-9(T) and TF-16 contained MK-8, MK-7 and MK-6 as the predominant menaquinones. The major fatty acid was anteiso-C(15 : 0). The DNA G+C contents of strains TF-9(T) and TF-16 were respectively 48 and 49 mol%. The level of 16S rDNA identity between strains TF-9(T) and TF-16 was 98.9 %. Strain TF-9(T) and TF-16 respectively exhibited levels of 16S rDNA identity of 97.2-98.4 and 96.9-99.5 % to the type strains of Planococcus kocurii, Planococcus citreus and Planococcus antarcticus. The mean level of DNA-DNA relatedness between strains TF-9(T) and TF-16 was 36.7 %. Strains TF-9(T) and TF-16 respectively exhibited levels of DNA-DNA relatedness of 7.1-43.4 and 3.5-80.9 % to Planococcus citreus DSM 20549(T), Planococcus kocurii DSM 20747(T) and Planococcus antarcticus DSM 14505(T). On the basis of the phenotypic, phylogenetic and genomic data, strain TF-9(T) (=KCCM 41587(T)=JCM 11543(T)) should be placed as a novel species of the genus Planococcus, for which the name Planococcus maritimus sp. nov. is proposed, and strain TF-16 should be classified as a member of Planococcus citreus.

DNA, Bacterial↗

PubMed2003

Emended description of Janibacter terrae, including ten dibenzofuran-degrading strains and Janibacter brevis as its later heterotypic synonym.

Ten Gram-positive strains that degraded dibenzofuran belonged to one homogeneous cluster with common biochemical and chemotaxonomic properties. The strains included the previously described strains [Terrabacter sp.] DPO 360 and DPO 1361 and were isolated from different locations in central Europe. They all shared menaquinone MK-8(H(4)) and meso-diaminopimelic acid in the cell wall and showed the same cellular fatty acid, polar lipid and RiboPrint patterns. Chemotaxonomic properties, as well as DNA G+C content (72.8 mol%), were consistent with those described for the genus Janibacter. Analysis of 16S rDNA sequences suggested a close relationship to Janibacter terrae and Janibacter brevis. DNA-DNA hybridization of two dibenzofuran-degrading strains (DPO 360 and DPO 1361) and the type strains of J. terrae and J. brevis revealed that these strains belong to the same species. An emended description of the species J. terrae is given. J. brevis is a later heterotypic synonym of J. terrae.

Actinomycetales↗

PubMed2003

Influence of hyperhomocysteinemia on the cellular redox state--impact on homocysteine-induced endothelial dysfunction.

Hyperhomocysteinemia is an independent risk factor for the development of atherosclerosis. An increasing body of evidence has implicated oxidative stress as being contributory to homocysteine's deleterious effects on the vasculature. Elevated levels of homocysteine may lead to increased generation of superoxide by a biochemical mechanism involving nitric oxide synthase, and, to a lesser extent, by an increase in the chemical oxidation of homocysteine and other aminothiols in the circulation. The resultant increase in superoxide levels is further amplified by homocysteine-dependent alterations in the function of cellular antioxidant enzymes such as cellular glutathione peroxidase or extracellular superoxide dismutase. One direct clinical consequence of elevated vascular superoxide levels is the inactivation of the vasorelaxant messenger nitric oxide, leading to endothelial dysfunction. Scavenging of superoxide anion by either superoxide dismutase or 4,5-dihydroxybenzene 1,3-disulfonate (Tiron) reverses endothelial dysfunction in hyperhomocysteinemic animal models and in isolated aortic rings incubated with homocysteine. Similarly, homocysteine-induced endothelial dysfunction is also reversed by increasing the concentration of the endogenous antioxidant glutathione or overexpressing cellular glutathione peroxidase in animal models of mild hyperhomocysteinemia. Taken together, these findings strongly suggest that the adverse vascular effects of homocysteine are at least partly mediated by oxidative inactivation of nitric oxide.

Animals↗

PubMed2002

Taxonomic study of Weissella confusa and description of Weissella cibaria sp. nov., detected in food and clinical samples.

A taxonomic study was conducted to clarify the relationships of two bacterial populations belonging to the genus Weissella. A total of 39 strains originating mainly from Malaysian foods (22 strains) and clinical samples from humans (9 strains) and animals (6 strains) were analysed using a polyphasic taxonomic approach. The methods included classical phenotyping, whole-cell protein electrophoresis, 16S and 23S rDNA RFLP (ribotyping), determination of 16S rDNA sequence homologies and DNA-DNA reassociation levels. Based on the results, the strains were considered to represent two different species, Weissella confusa and a novel Weissella species, for which the name Weissella cibaria sp. nov. is proposed. Weisella confusa possessed the highest 16S rDNA sequence similarity to Weisella cibaria, but the DNA-DNA reassociation experiment showed hybridization levels below 49% between the strains studied. The numerical analyses of Weisella confusa and Weisella cibaria strains did not reveal any specific clustering with respect to the origin of the strains. Based on whole-cell protein electrophoresis, and ClaI and HindIII ribotyping patterns, food and clinical isolates were randomly located in the two species-specific clusters obtained.

Animals↗

PubMed2002

Isobaculum melis gen. nov., sp. nov., a Carnobacterium-like organism isolated from the intestine of a badger.

Phenotypic and phylogenetic studies were performed on a hitherto undescribed facultatively anaerobic, catalase-negative, gram-positive rod-shaped organism, strain M577-94T, isolated from the small intestine of a dead badger. It resembled carnobacteria in terms of its long-chain cellular fatty acid composition, but differed markedly from the latter in possessing a cell-wall murein based on L-lysine (type L-Lys-L-Thr-Gly). Comparative 16S rRNA gene sequencing showed that the unknown bacterium represents a new line closely related to, albeit distinct from, the genera Carnobacterium and Desemzia. On the basis of phylogenetic and phenotypic evidence, it is proposed that strain M577-94T be classified as Isobaculum melis gen. nov., sp. nov. The type strain of Isobaculum melis is CCUG 37660T (= DSM 13760T).

Anaerobiosis↗

PubMed2002

Arthrobacter nasiphocae sp. nov., from the common seal (Phoca vitulina).

An unknown gram-positive, catalase-positive, strictly aerobic, rod-shaped bacterium was isolated from the nasal cavities of two common seals. Chemical analysis revealed the presence in the bacterium of a hitherto unknown cell-wall murein [type: L-Lys-L-Ala2-Gly(2-3)-L-Ala (Gly)]. Comparative 16S rRNA gene sequencing showed that the unidentified rod was related to the Arthrobacter group of organisms, although sequence divergence values of >3% from established members of this genus indicated that it represents a novel species. On the basis of phenotypic and phylogenetic considerations, it is proposed that the unknown bacterium from seals (Phoca vitulina) be classified as a novel species, Arthrobacter nasiphocae sp. nov. The type strain of Arthrobacter nasiphocae is CCUG 42953T.

Animals↗

PubMed2002

Reclassification of Clostridium hydroxybenzoicum as Sedimentibacter hydroxybenzoicus gen. nov., comb. nov., and description of Sedimentibacter saalensis sp. nov..

Strain ZF2T, isolated from freshwater sediment, is a motile, rod-shaped, gram-positive, endospore-forming, amino acid- and pyruvate-utilizing, anaerobic bacterium. It requires yeast extract for growth. Carbohydrates are not utilized. The optimal temperature and pH for growth are 37 degrees C and 6.8-7.3, respectively. The G+C content of the DNA is 34.0 mol %. A 16S rDNA sequence analysis of strain ZF2T revealed that the highest similarity (94.4%) was shared with Clostridium hydroxybenzoicum JW/Z-1T. Strain ZF2T, however, was not able to carboxylate phenol or to decarboxylate 4-hydroxybenzoate, which are characteristic properties of strain JW/Z-1T. The degree of 16S rDNA relatedness, together with the physiological and chemotaxonomic properties, suggest that strain ZF2T represents a novel species that is clearly distinct from Clostridium hydroxybenzoicum JW/Z-1T. In a phylogenetic dendrogram, both strains form a separate cluster that is peripherally associated with the Peptostreptococcus group (cluster XIII) of the clostridia and the lineage of Helcococcus kunzii. Strains ZF2T and JW/Z-1T show a somewhat deeper branching from the cluster XII clostridia Clostridium purinolyticum and Clostridium acidiurici. The latter strains possessed the closest 16S rDNA similarity (between 88.4 and 90.7%), but were clearly separated by phenotypic markers. Therefore, a new genus, Sedimentibacter gen. nov., is described, comprising Sedimentibacter hydroxybenzoicus gen. nov., comb. nov., as the type species of the genus, with JW/Z-1T (= ATCC 51151T = DSM 7310T) as the type strain, and the novel species Sedimentibacter saalensis sp. nov., with strain ZF2T (= DSM 13558T = ATCC BAA-283T) as the type strain.

Bacterial Typing Techniques↗

PubMed2002

Bifidobacterium scardovii sp. nov., from human sources.

Five strains of an unusual catalase-negative Gram-positive asporogenous rod-shaped bacterium from human sources were subjected to a polyphasic taxonomic study. The presence of fructose-6-phosphate phosphoketolase, a key enzyme of bifidobacterial hexose metabolism, indicated the strains were members of the genus Bifidobacterium but they did not correspond to any of the recognized species of this genus on the basis of biochemical profiles and whole-cell protein analyses. Comparative 16S rRNA gene sequencing confirmed the placement of the isolates in the genus Bifidobacterium, and demonstrated they represent a hitherto unknown subline within the genus displaying > 5% sequence divergence with recognized species. Based on both phenotypic and phylogenetic criteria, it is proposed that the isolates recovered from human sources be classified as a new species, Bifidobacterium scardovii sp. nov.; the type strain is CCUG 13008T (= DSM 13734T).

Adult↗

PubMed2002

Re-evaluation of the status of the genus Oerskovia, reclassification of Promicromonospora enterophila (Jáger et al. 1983) as Oerskovia enterophila comb. nov. and description of Oerskovia jenensis sp. nov. and Oerskovia paurometabola sp. nov.

Phylogenetic analysis of Promicromonospora enterophila indicates that this taxon clusters with Cellulomonas species, adjacent to Cellulomonas turbata (basonym Oerskovia turbata). 16S rDNA analysis, DNA-DNA reassociation, riboprinting, peptidoglycan analysis and determination of phenotypic properties of various strains of P. enterophila and C turbata reveal that they form a cluster that can be distinguished unambiguously from other Cellulomonas species by morphology, amino acid composition of the cell wall and 16S rDNA signatures. As a result of thispolyphasic study, it appears taxonomically reasonable to re-establish the genus Oerskovia for C turbata and to reclassify P. enterophila as Oerskovia enterophila comb. nov.; two novel species, Oerskovia jenensis sp. nov. (type strain DSM 46000T = CIP 100330T) and Oerskovia paurometabola sp. nov. (type strain DSM 14281T = LMG 20385T), are also proposed.

Actinomycetales↗

PubMed2002

Emended description of the genus Trichococcus, description of Trichococcus collinsii sp. nov., and reclassification of Lactosphaera pasteurii as Trichococcus pasteurii comb. nov. and of Ruminococcus palustris as Trichococcus palustris comb. nov. in the low-G+C gram-positive bacteria.

Analyses of 165 rRNA gene sequences, restriction endonuclease digestion fingerprints of 16S-23S intergenic regions, DNA base compositions, fatty-acid profiles, cell-wall chemistry, cell physiology and fermentation end-product composition, along with other biochemical and phenotypic properties, supported the view that Trichococcus flocculiformis EchtT (DSM 2094T), Lactosphaera pasteurii KoTa2T (DSM 2381T), Ruminococcus palustris Z-7189T (DSM 9172T) and an isolate named 'Carnococcus allantoicus' NDP were all very similar and should be merged into a single genus. Detailed characterization of strains Ben 77, Ben 200 and Ben 201 described previously as 'Nostocoida limicola' I, a filamentous bacterium which causes bulking in activated sludge systems, revealed that these strains also belonged to the same genus as T. flocculiformis EchtT, L. pasteurii KoTa2T, R. palustris Z-7189T and 'C allantoicus' NDP. In fact, their shared properties suggested that these strains all belonged to a single species. However, DNA-DNA hybridization data indicated that T. flocculiformis EchtT, all of the 'N. limicola' I isolates and 'C allantoicus' NDP belonged to the same species, whereas L. pasteurii KoTa2T, R. palustris Z-7189T and two new isolates, 37AN3*T and 45AN2, represented three distinct species within the same genus. The priority of the genus name Trichococcus is established and since its validation predates the description of the genus Lactosphaera this name should take precedence. Under certain culture conditions, all of the strains mentioned above could produce chains of cocci. Furthermore, the morphology of T. flocculiformis EchtT could change to a non-filamentous form on certain media. This study proposes that the above strains be reclassified as members of the genus Trichococcus as four species, namely Trichococcus flocculiformis emend. (type strain EchtT = DSM 2094T), Trichococcus pasteurii comb. nov. (type strain KoTa2T = DSM 2381T = ATCC 35945T), Trichococcus collinsii sp. nov. (type strain 37AN3*T = DSM 14526T = ATCC BAA-296T, and Trichococcus palustris comb. nov. (type strain Z-7189T = DSM 9172T).

Bacteria↗

PubMed2002

Propionimicrobium gen. nov., a new genus to accommodate Propionibacterium lymphophilum (Torrey 1916) Johnson and Cummins 1972, 1057AL as Propionimicrobium lymphophilum comb. nov.

Based upon significant differences in chemotaxonomic properties, i.e., amino acid composition of peptidoglycan, fatty acids and base composition of DNA, and supported by the phylogenetic position of the 165 rDNA sequence the species Propionibacterium lymphophilum was reclassified as Propionimicrobium lymphophilum comb. nov.

Amino Acids↗

PubMed2002

Cellular glutathione peroxidase deficiency and endothelial dysfunction.

Cellular glutathione peroxidase (GPx-1) is the most abundant intracellular isoform of the GPx antioxidant enzyme family. In this study, we hypothesized that GPx-1 deficiency directly induces an increase in vascular oxidant stress, with resulting endothelial dysfunction. We studied vascular function in a murine model of homozygous deficiency of GPx-1 (GPx-1(-/-)). Mesenteric arterioles of GPx-1(-/-) mice demonstrated paradoxical vasoconstriction to beta-methacholine and bradykinin, whereas wild-type (WT) mice showed dose-dependent vasodilation in response to both agonists. One week of treatment of GPx-1(-/-) mice with L-2-oxothiazolidine-4-carboxylic acid (OTC), which increases intracellular thiol pools, resulted in restoration of normal vascular reactivity in the mesenteric bed of GPx-1(-/-) mice. We observed an increase of the isoprostane iPF(2alpha)-III, a marker of oxidant stress, in the plasma and aortas of GPx-1(-/-) mice compared with WT mice, which returned toward normal after OTC treatment. Aortic sections from GPx-1(-/-) mice showed increased binding of an anti-3-nitrotyrosine antibody in the absence of frank vascular lesions. These findings demonstrate that homozygous deficiency of GPx-1 leads to impaired endothelium-dependent vasodilator function presumably due to a decrease in bioavailable nitric oxide and to increased vascular oxidant stress. These vascular abnormalities can be attenuated by increasing bioavailable intracellular thiol pools.

Animals↗

PubMed2002

Cellular redox state and endothelial dysfunction in mildly hyperhomocysteinemic cystathionine beta-synthase-deficient mice.

Previous in vitro experiments have shown that hyperhomocysteinemia leads to oxidative inactivation of nitric oxide, in part by inhibiting the expression of cellular glutathione peroxidase (GPx-1). To elucidate the role of intracellular redox status on homocysteine-induced endothelial dysfunction and oxidant stress, heterozygous cystathionine beta-synthase-deficient (CBS(-/+)) and wild-type (CBS(+/+)) mice were treated with the cysteine donor L-2-oxothiazolidine-4-carboxylic acid (OTC). CBS(-/+) mice had significantly lower GPx-1 activity compared with their CBS(+/+) littermates, and OTC treatment led to a modest increase in tissue GPx-1 activity and significant increases in total thiols and in reduced glutathione levels in both CBS(+/+) and CBS(-/+) mice. Superfusion of the mesentery with beta-methacholine or bradykinin produced dose-dependent vasodilation of mesenteric arterioles in CBS(+/+) mice and in CBS(+/+) mice treated with OTC. In contrast, mesenteric arterioles from CBS(-/+) mice manifested dose-dependent vasoconstriction in response to both agonists. OTC treatment of CBS(-/+) mice restored normal microvascular vasodilator reactivity to beta-methacholine and bradykinin. These findings demonstrate that mild hyperhomocysteinemia leads to endothelial dysfunction in association with decreased bioavailable nitric oxide. Increasing the cellular thiol and reduced glutathione pools and increasing GPx-1 activity restores endothelial function. These findings emphasize the importance of intracellular redox balance for nitric oxide bioactivity and endothelial function.

Animals↗

PubMed2002

Endothelial dysfunction and atherothrombosis in mild hyperhomocysteinemia.

Mildly elevated plasma homocysteine levels are an independent risk factor for atherothrombotic vascular disease in the coronary, cerebrovascular, and peripheral arterial circulation. Endothelial dysfunction as manifested by impaired endothelium-dependent regulation of vascular tone and blood flow, by increased recruitment and adhesion of circulating inflammatory cells to the endothelium, and by a loss of endothelial cell antithrombotic function contributes to the vascular disorders linked to hyperhomocysteinemia. Increased vascular oxidant stress through imbalanced thiol redox status and inhibition of important antioxidant enzymes by homocysteine results in decreased bioavailability of the endothelium-derived signaling molecule nitric oxide via oxidative inactivation. This plays a central role in the molecular mechanisms underlying the effects of homocysteine on endothelial function. Supplementation of folic acid and vitamin B12 has been demonstrated to be efficient in lowering mildly elevated plasma homocysteine levels and in reversing homocysteine-induced impairment of endothelium-dependent vasoreactivity. Results from ongoing intervention trials will determine whether homocysteine-lowering therapies contribute to the prevention and reduction of atherothrombotic vascular disease and may thereby provide support for the causal relationship between hyperhomocysteinemia and atherothrombosis.

Arteriosclerosis↗