Monocyte-platelet aggregates affect local inflammation in patients with acute myocardial infarction.

The local inflammatory response following acute myocardial infarction (AMI) is increasingly being recognized as a central factor determining infarct healing. Myocardial inflammation can be visualized in patients using fasting F-FDG PET/MRI. Although this novel biosignal correlates with long-term functional outcome, the corresponding cellular substrate is not well understood.

Quantitative cardiovascular magnetic resonance: extracellular volume, native T1 and 18F-FDG PET/CMR imaging in patients after revascularized myocardial infarction and association with markers of myocardial damage and systemic inflammation.

Background: Characterization of tissue integrity and inflammatory processes after acute myocardial infarction (AMI) using non-invasive imaging is predictive of patient outcome. Quantitative cardiovascular magnetic resonance (CMR) techniques such as native T and extracellular volume (ECV) mapping as well as F-FDG positron emission tomography (PET) imaging targeting inflammatory cell populations are gaining acceptance, but are often applied without assessing their quantitative potential. Using simultaneously acquired PET/CMR data from patients early after AMI, this study quantitatively compares these three imaging markers and investigates links to blood markers of myocardial injury and systemic inflammatory activity.

Prospective Evaluation of 18F-Fluorodeoxyglucose Uptake in Postischemic Myocardium by Simultaneous Positron Emission Tomography/Magnetic Resonance Imaging as a Prognostic Marker of Functional Outcome.

Background: The immune system orchestrates the repair of infarcted myocardium. Imaging of the cellular inflammatory response by (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/magnetic resonance imaging in the heart has been demonstrated in preclinical and clinical studies. However, the clinical relevance of post-MI (18)F-FDG uptake in the heart has not been elucidated.

Selenium increases hydrogenase expression in autotrophically cultured Bradyrhizobium japonicum and is a constituent of the purified enzyme.

We have investigated the effect of added selenite on autotrophic growth and the time course of hydrogen oxidation derepression in Bradyrhizobium japonicum 122DES cultured in a medium purified to remove selenium compounds. In addition, hydrogenase was purified to near homogeneity and examined for the specific incorporation of Se into the enzyme. The addition of Se at 0.

Purification, properties, and distribution of ascorbate peroxidase in legume root nodules.

All aerobic biological systems, including N(2)-fixing root nodules, are subject to O(2) toxicity that results from the formation of reactive intermediates such as H(2)O(2) and free radicals of O(2). H(2)O(2) may be removed from root nodules in a series of enzymic reactions involving ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase. We confirm here the presence of these enzymes in root nodules from nine species of legumes and from Alnus rubra.

Symbiotic Expression of Cosmid-Borne Bradyrhizobium japonicum Hydrogenase Genes.

The expression of cosmid-borne Bradyrhizobium japonicum hydrogenase genes in alfalfa, clover, and soybean nodules harboring Rhizobium transconjugants was studied. Cosmid pHU52 conferred hydrogen uptake (Hup) activity in both free-living bacteria and in nodules on the different plant hosts, although in nodules the instability of the cosmid resulted in low levels of Hup activity. In contrast, cosmid pHU1, which does not confer Hup activity on free-living bacteria, gave a Hup phenotype in nodules on alfalfa and soybean.

Enzymatic reactions of ascorbate and glutathione that prevent peroxide damage in soybean root nodules.

The critical problem of oxygen toxicity for nitrogen-fixing organisms may be related to damage caused by oxygen radicals and peroxides. An enzymatic mechanism is described for removal of peroxides in root nodules of soybean (Glycine max). The system utilizes ascorbate as an antioxidant and glutathione as a reductant to regenerate ascorbate.

Further evidence that two unique subunits are essential for expression of hydrogenase activity in Rhizobium japonicum.

Eight strains of Rhizobium lacking hydrogenase uptake (Hup) activity and 17 transconjugant strains carrying the hup cosmids pHU1, pHU52, or pHU53 (G. R. Lambert, M.

Determination of the hydrogenase status of individual legume nodules by a methylene blue reduction assay.

We adapted a method for the rapid screening of colonies of free-living Rhizobium japonicum for hydrogenase activity to determine the hydrogenase status of individual soybean nodules. Crude bacteroid suspensions from nodules containing strains known to be hydrogen uptake positive (Hup) caused a localized decolorization of filter paper disks, whereas suspensions from nodules arising from inoculation with hydrogen uptake-negative (Hup) mutants or strains did not decolorize the disks. The reliability of the method was demonstrated by its successful application to 29 slow-growing rhizobia.

Intra- and interspecies transfer and expression of Rhizobium japonicum hydrogen uptake genes and autotrophic growth capability.

Cosmids containing hydrogen uptake genes have previously been isolated in this laboratory. Four new cosmids that contain additional hup gene(s) have now been identified by conjugal transfer of a Rhizobium japonicum 122DES gene bank into a Tn5-generated Hup(-) mutant and screening for the acquisition of Hup activity. The newly isolated cosmids, pHU50-pHU53, contain part of the previously isolated pHU1 but extend as far as 20 kilobases beyond its border.

Some properties of the nickel-containing hydrogenase of chemolithotrophically grown Rhizobium japonicum.

The uptake hydrogenase of chemolithotrophically grown Rhizobium japonicum was purified to apparent homogeneity with a final specific activity of 69 mumol of H2 oxidized per min per mg of protein. The procedure included Triton extraction of broken membranes and DEAE-cellulose and Sephacryl S-200 chromatographies. The purified protein contained two polypeptides separable only by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Characterization of Rhizobium japonicum hydrogen uptake genes.

Recombinant cosmids from a gene library of the DNA from Hup+ Rhizobium japonicum 122DES previously have been shown to restore hydrogenase activity when transferred by conjugation into certain Hup- mutants of R. japonicum. We generated a restriction map covering 32.

Nickel: A micronutrient element for hydrogen-dependent growth of Rhizobium japonicum and for expression of urease activity in soybean leaves.

Soybean plants and Rhizobium japonicum 122 DES, a hydrogen uptake-positive strain, were cultured in media purified to remove Ni. Supplemental Ni had no significant effect on the dry matter or total N content of plants. However, the addition of Ni to both nitrate-grown and symbiotically grown plants resulted in a 7- to 10-fold increase in urease activity (urea amidohydrolase, EC 3.

Rapid Colony Screening Method for Identifying Hydrogenase Activity in Rhizobium japonicum.

A method has been developed for the rapid screening of Rhizobium japonicum colonies for hydrogenase activity based on their ability to reduce methylene blue in the presence of respiratory inhibitors and hydrogen. Hydrogen uptake-positive (Hup) colonies derepressed for hydrogenase activity were visualized by their localized decolorization of filter paper disks impregnated with the dye. Appropriate responses were seen with a number of Hup and Hup wild-type strains of R.

Chemoautotrophic growth of hydrogen-uptake-positive strains of Rhizobium japonicum.

Recently reported research from this laboratory has demonstrated the autotrophic growth of certain hydrogen-uptake-positive strains of Rhizobium japonicum and defined minimal conditions for such growth. Ribulose 1,5-bisphosphate carboxylase has been detected in autotrophically growing cells, but at low specific activity. Moreover, growth rates were low, and growth ceased at low cell densities.

Autotrophic growth of H2-uptake-positive strains of Rhizobium japonicum in an atmosphere supplied with hydrogen gas.

Previous research from this laboratory has demonstrated CO(2)-fixing and H(2)-uptake capacities of certain strains of Rhizobium japonicum. In this report we have shown that SR, a H(2)-uptake-positive (Hup(+)) strain of R. japonicum, is capable of autotrophic growth with H(2) as the energy source.

Hydrogenase in Rhizobium japonicum Increases Nitrogen Fixation by Nodulated Soybeans.

Some Rhizobium strains synthesize a unidirectional hydrogenase system in legume nodule bacteroids; this system participates in the recycling of hydrogen that otherwise would be lost as a by-product of the nitrogen fixation process. Soybeans inoculated with Rhizobium japonicum strains that synthesized the hydrogenase system fixed significantly more nitrogen and produced greater yields than plants inoculated with strains lacking hydrogen-uptake capacity. Rhizobium strains used as inocula for legumes should have the capability to synthesize the hydrogenase system as one of their desirable characteristics.

Regulation of hydrogenase in Rhizobium japonicum.

Factors that regulate the expression of an H2 uptake system in free-living cultures of Rhizobium japonicum have been investigated. Rapid rates of H2 uptake by R. japonicum were obtained by incubation of cell suspensions in a Mg-phosphate buffer under a gas phase of 86.

Expression of hydrogenase activity in free-living Rhizobium japonicum.

A medium is described on which selected Rhizobium japonicum strains express hydrogenase (H(2) uptake) activity under free-living conditions. Low concentrations of carbon substrates, decreased oxygen tension, and the quantity of combined nitrogen in the medium were major factors influencing hydrogenase expression. Hydrogenase activity was dependent upon a preincubation period in the presence of H(2) under conditions such that the cells did not exhibit nitrogenase activity.

Survival of human enteric and other sewage microorganisms under simulated deep-sea conditions.

The survival of pure cultures of Escherichia coli, Streptococcus faecalis, Clostridium perfringens, and Vibrio parahaemolyticus under simulated deep-sea conditions of low temperature (4 C), seawater, and hydrostatic pressures ranging from 1 to 1,000 atm was determined over a period exceeding 300 h. The viability of E. coli and total aerobic bacteria in seawater-diluted raw sewage subjected to these deep-sea conditions was also measured.