Intermediary steps in cellulose synthesis in Acetobacter xylinum were studied with resting cells and particulate-membranous preparations of the wild-type strain and of a celluloseless mutant. Exogenously supplied [1-'4C]glucose was rapidly converted by resting cells of both types into glucose 6-phosphate, glucose 1-phosphate, and uridine glucose 5'-diphosphate (UDP)-glucose and incorporated into lipid-, water-, and alkali-soluble cellular fractions. The decrease in the level of labeled hexose-phosphates and UDP-glucose upon depletion of the exogenous substrate was accounted for by a continuous incorporation of ['4C]glucose into cellulose in the wild type and into the above-mentioned cellular components in the mutant. ['4C]glucose retained in the alkali-and water-soluble fractions of pulse-labeled wild-type cells was quantitatively chased into cellulose. Sonic extracts of both strains catalyzed the transfer of glucose from UDP-glucose into lipid-, water-, and alkali-soluble materials, as well as into an alkali-insoluble cellulosic f-1,4-glucan. The results strongly support the sequence glucose -* glucose 6-phosphate -* glucose 1-phosphate -. UDP-glucose --cellulose and indicate that lipidand protein-linked cellodextrins may function as intermediates between UDP-glucose and cellulose in A. xylinum.

The activities of a number of enzymes, extracted from Acetobacter xylinum, that are involved in carbohydrate metabolism may be accounted for in situ in permeabilized cells. The kinetic properties of citrate synthase and glycerokinase observed in vitro are also retained in situ. So is the regulatory sensitivity of these enzymes. Both in vitro and in situ, (a) citrate synthase, in contrast with the enzyme for other Gram-negative bacteria, is inhibited by ATP and is insensitive to NADH, and (b) glycerokinase is inhibited by fructose diphosphate and the ratio of its activities towards glycerol and dihydroxyacetone is the same.

The citrate synthase activity of Acetobacter xylinum cells grown on glucose was the same as of cells grown on intermediates of the tricarboxylic acid cycle. The activity of citrate synthase in extracts is compatible with the overall rate of acetate oxidation in vivo. The enzyme was purified 47-fold from sonic extracts and its molecular weight was determined to be 280000 by gel filtration. It has an optimum activity at pH 8.4. Reaction rates with the purified enzyme were hyperbolic functions of both acetyl-CoA and oxaloacetate. The Km for acetyl-CoA is 18pM and that for oxaloacetate 8.71uM. The enzyme is inhibited by ATP according to classical kinetic patterns. This inhibition is competitive with respect to acetyl-CoA (K, = 0.9mM) and non-competitive with respect to oxaloacetate. It is not affected by changes in pH and ionic strength and is not relieved by an excess of Mg2+ ions. Unlike other Gram-negative bacteria, the A. xylinum enzyme is not inhibited by NADH, but is inhibited by high concentrations of NADPH. The activity of the enzyme varies with energycharge in a manner consistent with its role in energy metabolism. It is suggested that the flux through the tricarboxylic acid cycle in A. xylinum is regulated by modulation of citrate synthase activity in response to the energy state of the cells.Organic acids and related substrates are oxidized in

Background Coronary artery disease (CAD) is the leading cause of diastolic dysfunction. Diastolic dysfunction is associated with adverse outcomes. Renal insufficiency is also associated with adverse outcomes in CAD patients. The interaction between diastolic dysfunction and renal insufficiency is not completely elucidated. Aims We evaluated the prognostic value of diastolic function assessed by echocardiography in patients with and without renal failure undergoing coronary angiography. Patients and methods An observational prospective study of 547 consecutive patients undergoing coronary angiography. The median follow up was 30 months. Significant diastolic dysfunction was defined as elevated LV filling pressure with e/e'>12. Renal insufficiency was defined as adjusted GFR<60 ml/min. One hundred seventy-nine patients (32.7%) had significant diastolic dysfunction and 259 (47.3%) had renal insufficiency. Patients were categorized into 4 groups according to the presence of both significant diastolic dysfunction and renal insufficiency (Table 1). Results Significant diastolic dysfunction and renal insufficiency had additive effect on mortality (Table 1). A significant association was observed between diastolic dysfunction and mortality in patients with and without renal insufficiency (p<0.0001 & p=0.005, respectively). The presence of either diastolic dysfunction or renal insufficiency was associated with mortality (Figure 1), with the combination of both leading to the highest mortality (p<0.0001). In Cox regression model which combined diastolic dysfunction, presence of AF, LVEF, obstructive coronary disease on angiography, presence of acute coronary syndrome and renal insufficiency, both elevated filling pressure and renal insufficiency were independently associated with higher mortality (HR 2.65, CI 1.65–4.24, p<0.001 and HR 2.92, CI 1.72–4.98, p<0.0001, respectively). Table 1. Patients divided into 4 groups according to the presence of the significant diastolic dysfunction and renal insufficiency Patients' group N (%) Mortality Normal LV filling pressure / Normal renal function 230 (42.0%) 4.8% Elevated LV filling pressure / Normal renal function 58 (10.6%) 15.5% Normal LV filling pressure / Renal insufficiency 138 (25.2%) 15.9% Elevated LV filling pressure / Renal insufficiency 121 (22.1%) 38.8% P<0.0001 in Pearson Chi-Square. Fugure 1 Conclusions In patients undergoing coronary angiography, significant diastolic dysfunction with elevated filling pressure is associated with mortality in patients both with and without renal insufficiency. Both significant diastolic dysfunction and renal insufficiency are independent predictors of mortality.