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Biomedical subjects

J Bader

Publications and source records attributed to J Bader.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Bacterial regrowth in drinking water. III. Reasons for regrowth with oligocarbotolerant bacteria].

Investigations have been undertaken into the bacterial regrowth in a Zurich drinking water plant and over a distance of 12 km along the drinking water distribution system. This required installation of eleven chromium steel dead-end water pipes. Counts of oligocarbotolerant bacteria were carried out in 7 or 8 repetitions in fresh water and water left to stagnate for 7 and 14 days respectively (7,8). Additionally ten different biological, chemical and physical parameters were determined in the fresh water samples. Multiple linear regression analysis was used to determine what influence the different parameters had on the bacterial regrowth during stagnation. Two regression models were evaluated, one for the data obtained during treatment, and the other for the data obtained along the distribution system. In both models the content of DOC (Dissolved Organic Carbon) and the content of phosphate was correlated with the growth of oligocarbotolerant bacteria. Further, a relationship between the contents of organic matter and bacterial regrowth was discovered during two measuring series conducted in different seasons. The model of data obtained during treatment generated two additional parameters correlated with aftergrowth: Firstly the initial colony content, which probably resulted because the stagnation period was only half that of the model. Secondly, the oxygen content which resulted because of ozonization. Under the given test conditions the following parameters did not appear in the regression model (Cp-statistics according to Daniel and Wood, 5): AOC (Assimilatible Organic Carbon) and UV-absorption used for measuring organic matter, nitrate content, content of chlorine/chlorine dioxide, electrical conductivity, pH-values and the room temperature during the 14 days stagnation in the distribution system model.

Acids↗
PubMed1987

Neoadjuvant chemotherapy in the combined modality approach of locally advanced nonmetastatic breast cancer.

We have treated 76 patients with locally advanced breast cancer, 31 with stage IIIA, 41 with stage IIIB, and 4 with stage IV disease, with primary induction chemotherapy including an attempted hormonal synchronization in 70 patients. All were treated to maximum objective clinical response before proceeding to any local therapy. Patients achieving a complete response with a negative repeat biopsy generally received radiation therapy while patients with residual disease, partial response (PR) or no change (NC) status received debulking surgery prior to radiation therapy. Regardless of response to induction chemotherapy, patients received at least 6 additional months of chemotherapy following local therapy. Initial doses of combination chemotherapy were escalated to targeted myelosuppression. The objective response rate to induction chemotherapy was 93% with 49% complete response (CR), 44% PR, and 7% NC. The median numbers of cycles of chemotherapy to achieve a CR, PR, or NC were 5, 3, and 5, respectively. Three patients who currently have PRs are still on chemotherapy with continued tumor regression. Of 37 patients achieving a CR to chemotherapy, 35 were assessed by biopsies to determine pathological evidence of response. Twenty-three of the 37 patients (62%) were proven to be complete responders with negative biopsies. Twenty-four patients have relapsed, 6 with stage IIIA, 16 with stage IIIB, and 2 with stage IV. Five patients have had locoregional relapses alone, 4 locoregional and distant, and 15 distant alone. Median time to progression is 35.9 months for stage IIIA and 34.2 months for stage IIIB. Median survival is 35.3 months for stage IIIB and is indeterminate for stage IIIA. This aggressive primary chemotherapy regimen with hormonal synchronization followed by local therapy appears to provide excellent local control and encouraging early results on systemic disease control.

Adult↗
PubMed1987

Mitochondria catalyze the reduction of NAD by reduced methylviologen.

Mitochondria from beef heart and yeast catalyze the reduction of NAD to NADH at the expense of reduced methylviologen (MV+). Based on protein the specific activity of mitochondria for this reaction is about 10 20-times higher than the consumption of oxygen in the presence of succinate or NADH. In 2H2O buffer (4S)-[4-2H]NADH is formed in high enantiomeric excess if the reduced methylviologen is electrochemically regenerated.

Animals↗
PubMed1985

Chiral products from non-pyridine nucleotide-dependent reductases and methods for NAD(P)H regeneration.

Enoate reductase (EC 1.3.1.31) from a Clostridium tyrobutyricum strain catalyses the stereospecific reduction of many different alpha, beta-unsaturated carboxylates, aldehydes and even some ketones. The enzyme accepts electrons from NADH and, 1.5 times faster, from reduced methyl viologen (1,1'-dimethyl-4,4'-bipyridinium). Another new type of non-pyridine nucleotide-dependent reductase has an extremely broad substrate specificity for 2-oxo-carboxylates and 2-oxo-dicarboxylates. In crude extracts from Proteus mirabilis and Proteus vulgaris, specific activities of 2-12 mumol product formed per mg protein per min can be found when reduced methyl or benzyl viologen is used as electron donor. The products are (2R)-hydroxy acids. Enoate reductase and 2-oxo-carboxylate reductase are suitable for electro-enzymic reductions in which catalytic amounts of viologens are continuously reduced in an electrochemical cell. This procedure has three advantages: (1) regeneration of NAD(P)H by a second enzyme and substrate is not required, (2) the unstable pyridine nucleotides are not required in the reaction mixture, and (3) the rate of the reaction can be observed continuously by measuring an electric current. Several yeasts, as well as aerobic and anaerobic bacteria, catalyse the reduction of NAD(P)+ by reduced methyl viologen. Such cells can be used for electro-microbial reductions when only pyridine nucleotide-dependent reductases are present. Information about the enzymes which catalyse the reduction of NAD(P)+ at the expense of reduced methyl viologen is given.

Alcohol Oxidoreductases↗
PubMed1983

[Analysis of contemporary and future respiratory therapy].

Up to now there are no systematics of respiratory therapy, although those procedures of "conservative" respiratory therapy are well known since the last century. As ventilation will take over a part or the whole work of breathing of a patient this kind of respiratory therapy must be separated from the conservative therapy procedure, which is the focal point of respiratory therapy. This has been demonstrated by an analysis of respiratory therapy made on two different ICU's. From this analysis a system has been developed encompassing the whole range of respiratory therapy.

Germany, West↗
PubMed1981

Stereospecific reductions of 2-en-1-ols catalyzed by Clostridium kluyveri.

With ethanol as electron donor, resting cells of Clostridium kluyveri reduced (E)-2-methyl-2-buten-1-ol, (E)-3-methyl-2-penten-1-ol and (E)-2-methyl-3-phenyl-2-propen-1-ol to (R)-2-methyl-1-butanol, (R)-3-methyl-1-1-pentanol and (R)-2-methyl-3-phenyl-1-propanol, respectively. Within the experimental errors of ORD measurements the products were optically pure. That means that only one of the two possible trans additions to the carbon-carbon double bond of these derivatives of allyl alcohol took place. The reduction of (E)-2-methyl-3-phenyl-2-propen-1-ol was carried out in 2H2O buffer. Assuming tha all 3 substrates bind in an identical manner to the enzyme, the product should be (2R,3S)-2-methyl-3-phenyl-[2,3-2H2]-1-propanol. The optimal pH and ethanol concentration for the reduction have been determined. Under an atmosphere of hydrogen the reduction of the unsaturated alcohols proceeded incompletely and slower than in the presence of ethanol under an atmosphere of nitrogen.

Alcohols↗
PubMed1981

The reduction of allyl alcohols by Clostridium species is catalyzed by the combined action of alcohol dehydrogenase and enoate reductase.

Cells, as well as crude extracts of Clostridium kluyveri or Clostridium spec. La 1, catalyze the hydrogenation of (E)- or (Z)-2-butenol to n-butanol. No single enzyme could be detected which directly accomplishes this reaction. It turned out that the reduction occurs as follows: 2-butenol leads to 2-butenal leads to n-butanal leads to n-butanol. The first step is catalyzed by the NAD-dependent alcohol dehydrogenase in C. kluyveri, the second by the recently detected enoate reductase which reduces not only nonactivated alpha, beta-unsaturated acylates but also alpha, beta-unsaturated aldehydes in a NADH-dependent reaction and the third step is again catalyzed by alcohol dehydrogenase. In Clostridium La 1 the alcohol dehydrogenase is NADP-dependent. The rate of the reduction of 2-butenol to n-butanol depends not only on the enzymes, but also on the ratio NAD(P)/NAD(P)H. In the presence of methylviologen cation radical which is formed by the reduction of methylviologen by the system H2/hydrogenase, the ratio NAD(P)/NAD(P)H is too small for the dehydrogenation of 2-butenol to 2-butenal. This explains the antagonistic effect of methylviologen in the hydrogenation of allyl alcohols and 2-enoates by both Clostridium species. Furthermore, the mechanism explains the finding that from a preparative point of view ethanol is a better electron donor than hydrogen for the stereospecific reduction of allyl alcohols.

1-Propanol↗
PubMed1980

Utilization of (E)-2-butenoate (crotonate) by Clostridium kluyveri and some other Clostridium species.

Clostridium La 1 obtained from a Clostridium kluyveri culture was compared with a typical C. kluyvery strain (DSM 555). The former grows on cortonate and is unable to use ethanol-acetate as carbon sources. The latter grows on crotonate only after long adaptation periods. Resting cells of both strains show also pronounced differences in the fermentation of crotonate. This holds even for C. kluyveri grown on crotonate. Besides several other differences the most striking is that there is no hybridization between the DNA of both strains. Crotonate seems not to be a very special carbon source since C. butyricum and C. pasteurianum grow on crotonate medium supplemented by peptone and yeast extract.

Acetates↗
PubMed1979

Flasking technique for large facial prostheses.

By utilizing the giant press and the plastic pipe flask, large facial prostheses can be flasked and processed to allow thin, well-adapted margins without distortion. The plastic flask is easily stored for a remake of the prosthesis at a future date if it should be necessary.

Humans↗
PubMed1979

Purification and some properties of a hitherto-unknown enzyme reducing the carbon-carbon double bond of alpha, beta-unsaturated carboxylate anions.

2-Enoate-reductase, a previously unknown soluble enzyme is present in Clostridium kluyveri and another Clostridium species growing on (E)-2-butenoate. From the latter the reductase was purified 88-fold with an overall yield up to 74%. The enzyme was pure as judged by polyacrylamide gel electrophoresis with and without sodium dodecyl sulphate as well as by isoelectric focusing. The purification of the enzyme was performed in the presence of (E)-2-methyl-2-butenoate as substrate to keep the enzyme in the oxidized state and under anaerobic conditions. The purification procedure included an ammonium sulphate precipitation, chromatography on DEAE-Sepharose CL-6B, hydroxylapatite and Sepharose CL-6B. The enzyme reduces different alpha,beta-unsaturated carboxylate anions such as (E)-2-butenoate, (E)-2-methyl-2-butenoate, (E)-cinnamate and probably many others in a NADH-dependent reaction to the saturated carboxylate anions. Fumarate, 3-phenyl-2-propinate, 2-enoyl-methyl and CoA esters proved not to be substrates for the purified reductase. NADPH does not act as an electron donor. The enzyme was shown to have a molecular weight of about 450,000 by gel chromatography. It consists of subunits with a molecular weight of 78,000. Per subunit about 1 FAD, 3.5--3.8 atoms of iron and 4.0 labile sulphur atoms have been found indicating a conjugated iron-sulphur flavo-protein. Copper could not be detected. The isoelectric point was 8.4. As shown by absorption spectroscopy the enzyme can be reduced by NADH and reoxidized with dichloroindophenol, hexacyanoferrate III, oxygen and substrates. Addition of 8 mol p-hydroxymercuribenzoate to 1 mol subunit completely destroyed the activity of the reductase. So far no physiological role of the enzyme is known.

Amino Acids↗
PubMed1978

Properties of two Clostridia strains acting as catalysts for the preparative stereospecific hydrogenation of 2-enoic acids and 2-alken-1-ols with hydrogen gas.

A Clostridium strain growing on crotonate/hydrogencarbonate, which is able to hydrogenate stereospecifically 2-enoates as well as other unsaturated compounds with hydrogen gas, has been isolated and methods for its propagation elucidated. For this strain and for Clostridium kluyveri DSM 555 grown on ethanol/acetate/hydrogencarbonate, samples of 200-l batches were assayed to determine the hydrogenation activity for (E)-2-methyl-2-butenoate and (E)-2-buten-1-ol as a function of time during the exponential and stationary growth phases. For the strain growing on crotonate/hydrogencarbonate, the hydrogenation rate as a function of substrate concentration, pH and temperature has been measured. Storage conditions for both strains are given.

Clostridium↗
PubMed1976

Action of polymyxin B on bacterial membranes. Binding capacities for polymyxin B of inner and outer membranes isolated from Salmonella typhimurium G30.

Radioactive mono-N-acetyl-14C-polymyxin B or natural polymyxin B are within 60 s absorbed by isolated inner (cytoplasmic) and outer membranes from Salmonella typhimuriumG30. The sigmoidal binding isotherms indicate saturation of inner and outer membranes with approximately 30 and 60 nmoles polymyxin B bound per mg membrane, respectively. Based on the known content of these membranes in lipopolysaccharide, phosphatidylglycerol, cardiolipin and phosphatidylethanolamine, a calculation of the theoretical binding capacities yields almost identical values if lipopolysaccharide, phosphatidylglycerol and cardiolipin are assumed to function as the actual binding sites for the antibiotic in the isolated membranes. The excellent agreement between theoretical evaluation and experimental determination of polymyxin B-binding capacities leaves little doubt that the named anionic compounds are the chemoreceptors for the cationic antibiotic. This is further substantiated by very similar binding and killing kinetics of polymyxin B.

Binding Sites↗
PubMed1976

Action of polymyxin B on bacterial membranes: phosphatidylglycerol- and cardiolipin-induced susceptibility to polymyxin B in Acholeplasma laidlawii B.

To identify the polymyxin receptor molecules in the membranes of living microorganisms, fusion of intact Acholeplasma laidlawii B with lipid vesicles was investigated according to the procedure of Grant and McConnell (1973). The naturally polymyxin-resistant A. laidlawii B was treated with phospholipid vesicles prepared from purified phospholipids of the polymyxin-susceptible Salmonella typhimurium G30. A. laidlawii B absorbed between 15 and 45% of its own lipid content of the added tritium-labeled phospholipids without loss of viability. Association with the acidic components phosphatidylglycerol and cardiolipin produced a 10- to 30-fold increase in polymyxin susceptibility, which was not obtained with egg-phosphatidylcholine and mixed phosphatidylcholine-phosphatidylethanolamine vesicles. The polymyxin-sensitized cells bound 12 times more radioactive antibiotic than resistant cells. The phosphatidylglycerol-induced susceptibility was abolished by serum fraction V (Cohn) proteins.

Acholeplasma laidlawii↗