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Biomedical subjects

J Winter

Publications and source records attributed to J Winter.

At least 91 records · Page 5Linked to original sources
PubMed1998

Characterization of Aquamicrobium defluvii gen. nov. sp. nov., a thiophene-2-carboxylate-metabolizing bacterium from activated sludge.

A gram-negative bacterium was isolated from activated sewage sludge with thiophene-2-carboxylate as the sole source of carbon and with nitrate as an electron acceptor. The isolate, strain NKK, was a motile, oxidase- and catalase-positive, rod-like bacterium with a G+C content of 61.7 mol%. Besides nitrate, oxygen could serve as a terminal electron acceptor. Among many carbon sources tested, only a few sugars, fatty acids, and thiophene-2-carboxylate supported growth. Other heterocyclic compounds were not used. The sulfur atom of thiophene-2-carboxylate was oxidized to thiosulfate when cells were grown aerobically, or to elemental sulfur when cells were grown anaerobically with nitrate. Nitrate was reduced to nitrite. Growth on thiophene-2-carboxylate was dependent on the addition of molybdate to the medium. Tungstate, a specific antagonist of molybdate, inhibited growth on thiophene-2-carboxylate at concentrations > 10(-7) M. Three inducible enzymes involved in the metabolism of thiophene-2-carboxylate were detected: an ATP-, CoA-, thiophene-2-carboxylate- and Mg2+-dependent thiophene-2-carboxyl-CoA ligase (AMP-forming), a molybdenum-containing thiophene-2-carboxyl-CoA dehydrogenase, and a thiophene-2-carboxyl-CoA thioesterase. The sequence of the 16S rRNA gene suggested a classification of strain NKK within the alpha-subgroup of the Proteobacteria as a new genus and species, Aquamicrobium defluvii gen. nov. sp. nov. (DSM 11603), closely related to Mesorhizobium sp. and Phyllobacterium sp., but representing a distinct lineage equal in depth to those of the two mentioned genera. Aquamicrobium defluvii can be distinguished from both genera by a distinct spectrum of substrates, the maximal growth temperature, and a different salt tolerance.

Carboxylic Acids↗
PubMed1998

Treatment of cyanide-containing wastewater from the food industry in a laboratory-scale fixed-bed methanogenic reactor.

During the process of producing cassava starch from Manihot esculenta roots, large amounts of cyanoglycosides were released, which rapidly decayed to CN- following enzymatic hydrolysis. Depending on the varying cyanoglycoside content of the cassava varieties, the cyanide concentration in the wastewater was as high as 200 mg/l. To simulate anaerobic stabilization, a wastewater with a chemical oxygen demand (COD) of about 20 g/l was prepared from cassava roots and was fermented in a fixed-bed methanogenic reactor. The start-up phase for a 99% degradation of low concentrations of cyanide (10 mg/l) required about 6 months. After establishment of the biofilm, a cyanide concentration of up to 150 mg CN-/l in the fresh wastewater was degraded during anaerobic treatment at a hydraulic retention time of 3 days. All nitrogen from the degraded cyanide was converted to organic nitrogen by the biomass of the effluent. The cyanide-degrading biocoenosis of the anaerobic reactor could tolerate shock concentrations of cyanide up to 240 mg CN-/l for a short time. Up to 5 mmol/l NH4Cl (i.e. 70 mg N/l = 265 mg NH4Cl/l) in the fresh wastewater did not affect cyanide degradation. The bleaching agent sulphite, however, had a negative effect on COD and cyanide removal. For anaerobic treatment, the maximum COD space loading was 12 g l-1 day-1, equivalent to a hydraulic retention time of 1.8 days. The COD removal efficiency was around 90%. The maximum permanent cyanide space loading was 50 mg CN- l-1 day-1, with tolerable shock loadings up to 75 mg CN- l-1 day-1. Under steady-state conditions, the cyanide concentration of the effluent was lower than 0.5 mg/l.

Ammonia↗
PubMed1998

Degradation of cyanide in agroindustrial or industrial wastewater in an acidification reactor or in a single-step methane reactor by bacteria enriched from soil and peels of cassava.

During cassava starch production, large amounts of cyanoglycosides were released and hydrolysed by plant-borne enzymes, leading to cyanide concentrations in the wastewater as high as 200 mg/l. For anaerobic degradation of the cyanide during pre-acidification or single-step methane fermentation, anaerobic cultures were enriched from soil residues of cassava roots and sewage sludge. In a pre-acidification reactor this culture was able to remove up to 4 g potassium cyanide/l of wastewater at a hydraulic retention time (tHR) of 4 days, equivalent to a maximal cyanide space loading of 400 mg CN- 1(-1) day-1. The residual cyanide concentration was 0.2-0.5 mg/l. Concentrated cell suspensions of the mixed culture formed ammonia and formate in almost equimolar amounts from cyanide. Little formamide was generated by chemical decay. A concentration of up to 100 mmol ammonia/l had no inhibitory effect on cyanide degradation. The optimal pH for cyanide degradation was 6-7.5, the optimal temperature 25-37 degrees C. At a pH of 5 or lower, cyanide accumulated in the reactor and pre-acidification failed. The minimal tHR for continuous cyanide removal was 1.5 days. The enriched mixed culture was also able to degrade cyanide in purely mineralic wastewater from metal deburring, either in a pre-acidification reactor with a two-step process or in a one-step methanogenic reactor. It was necessary to supplement the wastewater with a carbon source (e.g. starch) to keep the population active enough to cope with any possible inhibiting effect of cyanide.

Aerobiosis↗
PubMed1998

Effect of ammonia on the anaerobic degradation of protein by a mesophilic and thermophilic biowaste population.

The influence of ammonia on the anaerobic degradation of peptone by mesophilic and thermophilic populations of biowaste was investigated. For peptone concentrations from 5 g l-1 to 20 g l-1 the mesophilic population revealed a higher rate of deamination than the thermophilic population, e.g. 552 mg l-1 day-1 compared to 320 mg l-1 day-1 at 10 g l-1 peptone. The final degree of deamination of the thermophilic population was, however, higher: 102 compared to 87 mg NH3/g peptone in the mesophilic cultures. If 0.5-6.5 g l-1 ammonia was added to the mesophilic biowaste cultures, deamination of peptone, degradation of its chemical oxygen demand (COD) and formation of biogas were increasingly inhibited, but no hydrogen was formed. The thermophilic biowaste cultures were most active if around 1 g ammonia l-1 was present. Deamination, COD degradation and biogas production decreased at lower and higher ammonia concentrations and hydrogen was formed in addition to methane. Studies of the inhibition by ammonia of peptone deamination, COD degradation and methane formation revealed a Ki (50%) for NH3 of 92, 95 and 88 mg l-1 at 37 degrees C and 251, 274 and 297 mg l-1 at 55 degrees C respectively. This indicated that the thermophilic flora tolerated significantly more NH3 than the mesophilic flora. In the mesophilic reactor effluent 4.6 x 10(8) peptone-degrading colony-forming units (cfu)/ml were culturable, whereas in the thermophilic reactor effluent growth of only 5.6 x 10(7) cfu/ml was observed.

Amines↗
PubMed1998

Effect of implantable cardioverter/defibrillator lead placement in the right ventricle on defibrillation energy requirements. A combined experimental and clinical study.

OBJECTIVES: The effect of implantable cardioverter/defibrillator (ICD) lead placement in the right ventricle (RV) on defibrillation efficacy has not been thoroughly investigated. Therefore, the goal of this combined experimental and clinical study was to evaluate the effect of a septal and a non-septal position of the right ventricular endocardial spring lead on defibrillation energy. METHODS: In 12 isoflurane-anaesthetized swine and subsequently in 8 patients who underwent ICD implantation, two different positions of the distal spring lead in the RV were investigated in randomized order: non-septal position (free wall of the RV) and septal position (interventricular septum). For each position, separate 50% probability determinations of energy (E50), peak voltage (V50) and peak current (A50) were calculated using the three reversal up/down defibrillation procedure. The E50, V50, A50 and impedance (I) were averaged and compared using the two-sided t-test for paired samples. RESULTS: Both the experimental study and the clinical study demonstrated that placing the distal defibrillation lead near to the septum rather than near to the ventricular free wall resulted both in the swine and in the patients in significantly lower E50-31.6%/ - 37.1%, V50-16.1%/-20.9% and A50 -10.0%/ - 24.2%, respectively. Defibrillation impedances were significantly reduced only in the experimental study. CONCLUSIONS: Defibrillation efficacy depends on the position of the distal spring electrode in the RV. A septal position significantly reduces the energy requirements compared to a non-septal position. The decrease in energy requirements might be explained by an increase in current flow through the septum and the posterolateral wall of the left ventricle. reserved

Animals↗
PubMed1998

Differential regulation of SHC proteins by nerve growth factor in sensory neurons and PC12 cells.

We have characterized some of the nerve growth factor (NGF) stimulated receptor tyrosine kinase (TrkA) signalling cascades in adult rat primary dorsal root ganglia (DRG) neuronal cultures and compared the pathways with those found in PC12 cells. TrkA receptors were phosphorylated on tyrosine residues in response to NGF in DRG neuronal cultures. We also saw phosphorylation of phospholipase Cgamma1 (PLCgamma1). We used recombinant glutathione-S-transferase (GST)-PLCgamma1 SH2 domain fusion proteins to study the site of interaction of TrkA receptors with PLCgamma1. TrkA receptors derived from DRG neuronal cultures bound preferentially to the amino terminal Src homology-2 (SH2) domain of PLCgamma1, but there was enhanced binding with tandemly expressed amino- and carboxy-terminal SH2 domains. The most significant difference in NGF signalling between PC12 cells and DRG was with the Shc family of adapter proteins. Both ShcA and ShcC were expressed in DRG neurons but only ShcA was detected in PC12 cells. Different isoforms of ShcA were phosphorylated in response to NGF in DRG and PC12 cells. NGF phosphorylated only one whereas epidermal growth factor phosphorylated both isoforms of ShcC in DRG cultures. Activation of the downstream mitogen-activated protein (MAP) kinase, p42Erk2 was significantly greater than p44Erk1 in DRG whereas both isoforms were activated in PC12 cells. Blocking the MAP kinase cascade using a MEK1/2 inhibitor, PD98059, abrogated NGF dependent capsaicin sensitivity, a nociceptive property specific to sensory neurons.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Methanoculleus palmolei sp. nov., an irregularly coccoid methanogen from an anaerobic digester treating wastewater of a palm oil plant in north-Sumatra, Indonesia.

Strain INSLUZT (= DSM 4273T) was isolated from a biogas-producing bioreactor treating wastewater of a palm oil mill on North-Sumatra (Indonesia). Cells of strain INSLUZT were highly irregularly coccoid, 1.25-2.0 microns in diameter, had a cell envelope consisting of the cytoplasmic membrane and an S-layer of hexagonally arranged glycoprotein subunits with an M(r) of 120,000, and were flagellated (motility was not observed). Cells were mesophilic and grew most rapidly at 40 degrees C on H2/CO2' formate, 2-propanol/CO2 2-butanol/CO2 and cyclopentanol/CO2 to give methane. Tungstate promoted growth on H2/CO2 with acetate as the solely required organic medium supplement. The G + C content of DNA was 59 mol% (Tm method) and 59.5 mol% (HPLC method). 16S rDNA analysis revealed a phylogenetic relationship to Methanoculleus species; the name Methanoculleus palmolei sp. nov. is therefore proposed for strain INSLUZT (= DSM 4273T).

Anaerobiosis↗
PubMed1997

Expression of tenascin in lymphocytic autoimmune thyroiditis.

AIMS: To study the distribution of tenascin by immunocytochemistry in autoimmune diseases of the thyroid. METHODS: Thyroids from patients with inflammatory lesions of the thyroid (lymphocytic thyroiditis Hashimoto, Grave's disease, thyroiditis DeQuervain) were studied by immunocytochemistry using antibodies against tenascin, collagen III, and collagen IV. RESULTS: In autoimmune lymphocytic thyroiditis Hashimoto there was a characteristic corona-like staining pattern of tenascin around all activated lymph follicles with germinal centres. This staining pattern contrasted with the immunoreactions for collagen III and IV, which were not enhanced in the perilymphofollicular interstitium. In cases of thyroiditis DeQuervain the areas of early and ongoing fibrosis showed some diffuse staining for tenascin and for collagen III. Enhanced diffuse immunostaining for collagen IV in the perivascular and interfollicular interstitium was present in cases of Grave's disease. In Grave's disease no characteristic immunoreaction was detectable for tenascin. CONCLUSIONS: The corona-like expression of tenascin around lymphofollicular infiltrates is distinctive of cases of lymphocytic thyroiditis. A similar staining pattern for tenascin has been reported in lymphoid hyperplasia of the thymus associated with myasthenia gravis, another autoimmunological disorder. There are good arguments that the activation and infiltration of lymph follicles in the thyroid during the course of autoimmune diseases lead to stimulation and activation of the surrounding mesenchyme producing tenascin as part of the extracellular matrix.

Biomarkers↗
PubMed1997

Brain docosahexaenoate accretion in fetal baboons: bioequivalence of dietary alpha-linolenic and docosahexaenoic acids.

The dietary bioequivalence during the brain growth spurt of alpha-linolenic (LNA) and docosahexaenoic acids (DHA) as substrates for brain and retinal n-3 fatty acid accretion is reported for the fetal baboons, whose mothers consumed a long chain polyunsaturate-free diet with a n-6/n-3 ratio of 10:1. Pregnant baboons received i.v. doses of U-13C-labeled fatty acids (LNA or DHA), plasma was collected from mother and fetus, and fetal brain (occipital cortex), retina, and liver were analyzed at various times post-dose. Fetal brain DHA plateaued 15-35 d post-dose with 1.6% of the preformed [U-13C-]DHA dose recovered in the brain. In contrast, LNA-derived DHA accretion also plateaued but was 20-fold lower. Liver and retinal results were of the same order of magnitude, but showed evidence of peaks and decline. Conversion products to n-3 long chain polyunsaturate were observed in the maternal circulation at 1 h after administration, as was transfer of both fatty acids to the fetus. From these measurements we estimate that a dietary level of about 0.45% of energy as LNA is sufficient to meet the requirements of the growing fetal brain, whereas 0.03% of energy as DHA would suffice. These data are the first direct measurements of the bioequivalence of DHA and LNA in developing primates and imply that n-3 fatty acid requirements for the developing fetal brain can be met by attainable dietary LNA for diets low in long chain polyunsaturates.

Animals↗
PubMed1996

Analogues of capsaicin with agonist activity as novel analgesic agents: structure-activity studies. 4. Potent, orally active analgesics.

Structural features of three regions of the capsaicin molecule necessary for agonist properties were delineated by a previously reported modular approach. These in vitro agonist effects were shown to correlate with analgesic potency in rodent models. Combination of optimal structural features from each of these regions of the capsaicin molecule have led to highly potent agonists (eg., 1b). Evaluation in vivo established that 1b had analgesic properties but poor oral activity, short duration of action, and excitatory side effects which precluded further development of this compound. Preliminary metabolism studies had shown that the phenol moiety of 1b was rapidly glucuronidated in vivo, providing a possible explanation for the poor pharmacokinetic profile. Subsequent specific modification of the phenol group led to compounds 2a-j, which retained in vitro potency. The in vivo profiles of two representatives of this series, 2a,h, were much improved over the "parent" phenol series, and they are candidates for development as analgesic agents.

Administration, Oral↗
PubMed1996

Asymmetric interactions between phosphorylation pathways regulating ciliary beat frequency in human nasal respiratory epithelium in vitro.

1. The effects of the sequential stimulation of ciliary beat frequency (CBF) via two different phosphorylation cascades (dependent on protein kinase A (PKA) and calmodulin, respectively) were determined using video microscopy applied to a perfused preparation of human nasal respiratory epithelium in vitro. Dibutyryl cyclic AMP (db-cAMP) (10(-3) M) was used to stimulate PKA and the calcium ionophore 4-Br-A23187 (10(-5) M) was used to stimulate calmodulin-dependent phosphorylation. 2. Perfusion with db-cAMP (10(-3) M) alone showed an early rise in CBF (15.0 +/- 4%, mean +/- S.E.M., P < 0.05) by 10 min which remained elevated for 35 min; in contrast, the highest CBF response to 4-Br-A23187 (10(-5) M) alone was not achieved until 35 min (16.1 +/- 1.8%, P < 0.05). 3. When a db-cAMP stimulus was applied to cells which had been pre-incubated with 4-Br-A23187 for 30 min, a further rise in CBF (maximal at 20 min, 14.3 +/- 2%, P < 0.05) was observed. Reversing the sequence of perfusions, cells pre-incubated with db-cAMP showed no further rise in response to stimulation with 4-Br-A23187. 4. We hypothesized that PKA inhibited the response to the 4-Br-A23187. This notion was supported by the restoration of the CBF response (22.8 +/- 4%, P < 0.05) to 4-Br-A23187 when the cells were pre-incubated with the protein kinase inhibitor 1-(5-isoquinolinyl-sulphonyl)-2-methylpiperazine (10(-3) M), before the sequential perfusions with db-cAMP and 4-Br-A23187. We conclude that the A23187-dependent pathway, which regulates intrinsic CBF, is inhibited by db-cAMP but not vice versa.

Adolescent↗
PubMed1996

Similarities and differences in the structure-activity relationships of capsaicin and resiniferatoxin analogues.

Structure-activity relationships in analogues of the irritant natural product capsaicin have previously been rationalized by subdivision of the molecule into three structural regions (A,B, and C). The hypothesis that resiniferatoxin (RTX), which is a high-potency ligand for the same receptor and which has superficial structural similarities with capsaicin, could be analogously subdivided has been investigated. The effects of making parallel changes in the two structural series have been studied in a cellular functional assay which is predictive of analgesic activity. Parallel structural changes in the two series lead to markedly different consequences on biological activity; the 3- and 4-position aryl substituents (corresponding to the capsaicin 'A-region') which are strictly required for activity in capsaicin analogues are not important in RTX analogues. The homovanillyl C-20 ester group in RTX (corresponding to the capsaicin 'B-region') is more potent than the corresponding amide, in contrast to the capsaicin analogues. Structural variations to the diterpene moiety suggest that the functionalized 5-membered diterpene ring of RTX is an important structural determinant for high potency. Modeling studies indicate that the 3D position of the alpha-hydroxy ketone moiety in the 5-membered ring is markedly different in the phorbol (inactive) analogues and RTX (active) series. This difference appears to be due to the influence of the strained ortho ester group in RTX, which acts as a local conformational constraint. The reduced activity of an analogue substituted in this region and the inactivity of a simplified analogue in which this unit is entirely removed support this conclusion.

Analgesics↗