Association of anti-topoisomerase I with cancer.
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Aged↗
Biomedical subjects
L Daniels
Publications and source records attributed to L Daniels.
Effect of temperature on the spectral properties of coenzyme F420 and related compounds.
The uv-visible spectra of 7,8-didemethyl-8-hydroxy-5-deazaflavin-5'-phosphoryllactyl glutamate (coenzyme F420), a naturally occurring 5-deazaflavin derivative, in three different buffers changed with a rise in temperature; the effect on the extinction coefficient at 420 nm (epsilon 420) was as follows: In phosphate-buffered solutions at pH less than 7.5, the epsilon 420 increased (at pH 5.0 for a temperature shift from 15 to 60 degrees C, delta epsilon 420 was +87%), but between pH 7.5 and 8, epsilon 420 changed very little. At pH greater than 8.0 in phosphate- or borate-buffered solutions, epsilon 420 decreased slightly. In morpholineethanesulfonic acid (Mes)-buffered F420 solutions at pH 5 and 5.5, epsilon 420 changed very little, whereas at pH 6-8, the epsilon 420 decreased. Absorbance of F420 at 401 nm in phosphate buffer at pH 5 to 9 was not significantly affected by temperature. Changes in epsilon 420 due to temperature change corresponded to changes in the pKa of 8-OH of the deazaflavin molecule; studies with adenylated F420 showed that the 8-OH of F420 was responsible for these changes.(ABSTRACT TRUNCATED AT 250 WORDS)
Algorithms↗
Empowering the clinical nurse through quality assurance in a shared governance setting.
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Decision Making, Organizational↗
Biotechnological potential of methanogens.
Methane produced microbiologically is currently used as an energy source, especially by cities and industries, albeit at a level far below its potential; the incentive is currently to save money on disposal costs for waste problems. Anaerobic digestion can be helpful in degrading several halogenated hydrocarbon wastes, and methanogens are partly responsible. Ethane instead of methane may be a future product of interest. Some pure cultures of methanogens may be suitable for production of B-12, or perhaps the speciality biochemical F420, a 5-deazaflavin of interest to both methanogen and streptomyces researchers. Methanogens can cause a variety of problems, including biocorrosion, increased atmospheric methane, and ruminant nutrition loss. Studies of tropical wetlands, including rice paddies and swamps, and the study of a variety of ruminants in the tropics are particularly interesting and appropriate at this time, with respect to methane produced in these ecosystems. In some cases, it may be possible to control methane production by the use of inhibitors or ecological control mechanisms.
Euryarchaeota↗
Prognostic significance of anticentromere antibodies and anti-topoisomerase I antibodies in Raynaud's disease. A prospective study.
Seventy-seven patients with Raynaud's disease were studied for a mean of 4 years (range 1-11 years) to determine the relationship between autoantibodies and long-term clinical outcome. Anticentromere antibodies (ACA) were assayed by indirect immunofluorescence and by immunoblotting of HeLa cell chromosome extracts. Antibodies to topoisomerase I (anti-topo I) were assayed by immunodiffusion and immunoblotting. Antibodies to the major centromeric protein, CENP-B, and anti-topo I were studied by enzyme-linked immunosorbent assay (ELISA). Eight patients developed telangiectasias, 4 developed skin tightening, and 4 developed a connective tissue disease other than scleroderma. The presence of ACA at the start of the study was associated with the development of telangiectasias (P less than 0.003). An initial 100-kd band on immunoblot in conjunction with a positive anti-topo I ELISA result was associated with the development of tight skin (P less than 0.0025), while a 100-kd band with a negative anti-topo I ELISA result was associated with the subsequent development of a connective tissue disease other than scleroderma (P less than 0.0073). Patients who were initially ACA positive, had the 100-kd band on immunoblot, or had positive ELISA results for anti-topo I or for anti-CENP-B were 63-fold more likely to develop signs of connective tissue disease by the end of the study (P less than 0.000009). The presence of any of these autoantibodies was more sensitive (100%), although less specific (75%), than were findings from nailfold capillaroscopy (sensitivity 67% and specificity 95%) in predicting subsequent clinical progression. We conclude that findings of assays for anti-topo I and ACA complement the findings from nailfold capillaroscopy in providing useful prognostic information in Raynaud's disease.
Antibodies↗
Pattern of organotin inhibition of methanogenic bacteria.
Seven organotin compounds and tin chloride were tested for their effects on the methanogenic bacteria Methanococcus thermolithotrophicus, Methanococcus deltae delta LH, and Methanosarcina barkeri 227. The methanogens were strongly inhibited by triethyltin, tripropyltin, and monophenyltin compounds, generally at concentrations below 0.05 mM. Less inhibition by tributyltin and diphenyltin was observed at levels below 0.1 mM, but complete inhibition was observed at a 1 mM concentration. Tin chloride inhibited all methanogens, with nearly complete inhibition at a 1 mM concentration. There was no inhibition by tetra-n-butyltin and triphenyltin compounds even at 2 mM, the highest concentration tested. The 50 and 100% inhibitory concentrations of all compounds were estimated; these values varied with both the compound tested and the bacterium tested. The 50% inhibitory concentration estimate generally decreased (i.e., giving a higher toxicity) as the total surface area of the alkyltin molecules decreased. These results differ considerably from those reported previously for aerobic microorganisms (G. Eng, E. J. Tierney, J. M. Bellama, and F. E. Brinckman, Appl. Organometallic Chem. 2:171-175, 1988), where a clear correlation between increasing total molecular surface area and increasing toxicity was documented with a variety of organisms. Using the same procedures as for the methanogens, we examined the effects of organotin compounds on Escherichia coli growing aerobically or anaerobically. The E. coli inhibition pattern clearly resembled that seen in the data of Eng et al., under both aerobic and anaerobic conditions.
Escherichia coli↗
One-carbon metabolism in methanogenic bacteria: analysis of short-term fixation products of 14CO2 and 14CH3OH incorporated into whole cells.
Methanobacterium thermoautotrophicum, M. ruminantium, and Methanosarcina barkeri were labeled with 14CO2 (14CO2 + H14CO3- + 14CO32-) for from 2 to 45 s. Radioactivity was recovered in coenzyme M derivatives, alanine, aspartate, glutamate, and several unidentified compounds. The properties of one important structurally unidentified intermediate (yellow fluorescent compound) displayed UV absorbance maxima at pH 1 of 290 and 335 nm, no absorbance in the visible region, and a fluorescence maximum at 460 nm. Label did not appear in organic phosphates until after 1 min. 14CH3OH was converted by M. barkeri primarily into coenzyme M derivatives at 25 s. [2-14C]acetate was assimilated by M. thermoautotrophicum mainly into alanine and succinate during 2 to 240 s, but not into coenzyme M derivatives or yellow fluorescent compound. Cell-free extracts of M. thermoautotrophicum lacked ribulose 1,5-bisphosphate carboxylase activity. The data indicated the absence of the Calvin, serine, and hexulose phosphate paths of C1 assimilation in the methanogens examined and indicated that pyruvate was an early intermediate product of net CO2 fixation. The in vivo importance of coenzyme M derivatives in methanogenesis was demonstrated.
Alanine↗
How can you improve patient compliance? Nursing grand rounds.
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Adult↗
Carbon monoxide oxidation by methanogenic bacteria.
Different species of methanogenic bacteria growing on CO(2) and H(2) were shown to remove CO added to the gas phase. Rates up to 0.2 mumol of CO depleted/min per 10 ml of culture containing approximately 7 mg of cells (wet weight) were observed. Methanobacterium thermoautotrophicum was selected for further study based on its ability to grow rapidly on a completely mineral medium. This species used CO as the sole energy source by disproportionating CO to CO(2) and CH(4) according to the following equation: 4CO + 2H(2)O --> 1CH(4) + 3CO(2). However, growth was slight, and the growth rate on CO was only 1% of that observed on H(2)/CO(2). Growth only occurred with CO concentrations in the gas phase of lower than 50%. Growth on CO agrees with the finding that cell-free extracts of M. thermoautotrophicum contained both an active factor 420 (F(420))-dependent hydrogenase (7.7 mumol/min per mg of protein at 35 degrees C) and a CO-dehydrogenating enzyme (0.2 mumol/min per mg of protein at 35 degrees C) that catalyzed the reduction of F(420) with CO. The properties of the CO-dehydrogenating enzyme are described. In addition to F(420), viologen dyes were effective electron acceptors for the enzyme. The apparent K(m) for CO was higher than 1 mM. The reaction rate increased with increasing pH and displayed an inflection point at pH 6.7. The temperature dependence of the reaction rate followed the Arrhenius equation with an activation energy (DeltaHdouble dagger) of 14.1 kcal/mol (59.0 kJ/mol). The CO dehydrogenase activity was reversibly inactivated by low concentrations of cyanide (2 muM) and was very sensitive to inactivation by oxygen. Carbon monoxide dehydrogenase of M. thermoautotrophicum exhibited several characteristic properties found for the enzyme of Clostridium pasteurianum but differed mainly in that the clostridial enzyme did not utilize F(420) as the electron acceptor.
Bacteria↗
Improved culture flask for obligate anaerobes.
An improved flask system for the growth of extremely oxygen-sensitive bacteria in liquid culture is described. The improvement described utilizes an all-glass, neoprene-stoppered flask designed for growth of 50- to 1,000-ml cultures of bacteria with continuous gassing.
Anaerobiosis↗