Phosphatidylethanol (Peth) formation catalyzed by the transphosphatidylation activity of phospholipase D was demonstrated to occur in a rat brain synaptosomal enriched preparation. The optimal pH was determined to be 6.5, and the optimal ethanol concentration was determined to be 0.3-0.4 M with an apparent Km of 0.2 M. Peth formation was barely detectable in the absence of an appropriate activator and several unsaturated fatty acids were found to be effective activators. The concentrations of oleic acid required for maximum activation varied with the concentration of exogenous phosphatidylcholine present in the incubation mixtures. All detergents tested were significantly less active than the unsaturated fatty acids and divalent ions were not required for Peth formation. Phosphatidylcholine was the most effective phosphatidyl donor of the phospholipids tested. Peth forming activity was greatest in the synaptic membrane fraction of the various brain subfractions examined. The 12,000 g-100,000 g particulate fraction of lung, heart, and adipose tissue had activities similar to that of brain.

Secondary ion mass spectrom6try has been applied for measuring the tracer diffusivity of oxygen in the c direction of singlecrystal rutile for a temperature range of 1150 to 1450 K at 6000 Pa pressure of oxygen gas. Specimens diffusion-annealed in oxygen gas containing l H 0 were subsequently continuously sputtered and analyzed for ' ' 0 and "0. The tracer diffusivity was determined from the depth profile of lH0, taking into account a surface exchange reaction of oxygen. The tracer diffusivity in CrpOs-doped rutile was 3 to 8 times larger than that in pure rutile. For pure rutile, the diffusivity is expressed by D(m2/ s ) = 3 . 4 x lo-' exp[ -25l(kJ/mol)/RT], and for 0.08 mol% Cr,O,,-doped rutile, by D(m2/s)=2.0x lo-' exp[ -204(kJ/ mol)/RT]. The Cr,O, doping had a catalytic effect on the rate constant of the surface exchange reaction on the c surface. The rate constant is represented, for pure rutile, by k(m/ s ) = 2 . 4~ lo-' exp[ -246(kJ/mol)/RT], and for 0.08 mol% Cr,O,,-doped rutile, k ( d s ) = 3 . 5~ exp[ -13l(kJ/mol)/RT].

Insulin sensitivity has been determined in primary nonobese diabetics and subjects with borderline glucose intolerance by a newly devised technique using glucose, insulin, and somatostatin infusion. Insulin sensitivity for glucose utilization was decreased in both adult- and juvenile-onset diabetics. Eight out of 88 diabetics had normal insulin sensitivty and were free from microvascular complications. In lean subjects with borderline glucose intolerance, insulin sensitivity was decreased, although an overlap with normal was noted. All obese subjects with borderline glucose intolerance had reduced insulin sensitivity. An inverse relationship was observed between insulin sensitivity and fasting plasma glucose (FPG), and a significant correlation was observed between FPG and steady state plasma glucose levels (SSPG; r = 0.57; P less than 0.001). Improvement of diabetic control in eight diabetics with sulfonylureas decreased SSPG in all (P less than 0.05), although normalization of SSPG was observed in only one. These results indicate that decreased sensitivity of insulin for peripheral glucose utilization may play an important role in the pathogenesis of diabetes. Elevated FPG levels reflect the presence of decreased insulin sensitivity in diabetes mellitus. Although decreased sensitivity is difficult to normalize, it can be enhanced by improving the diabetic control. An effort to maintain or enhance tissue insulin sensitivity in diabetes mellitus may be more important than attempts to stimulate the deteriorating pancreatic beta-cells to secrete more insulin.

Extraction of rat kidney cytosol with 10% charcoal at 4 C inactivated specific T3 binding. The decreased T3 binding in extracted cytosol could be restored by addition of boiled kidney cytosol. Three different factors (a, b, and c) which could increase T3 binding were identified by Sephadex G-50 column chromatography of boiled cytosol. Two factors (b and c) were eluted as relatively small molecules. Factor a was present in small amounts. Factor c was neutralized by incubation with EDTA, but factor b was not. Factor b was not destroyed by trypsin, protease, DNase, or RNase, but was destroyed by alkaline phosphatase. Factor b was destroyed by incubation with nicotinamide adenine dinucleotide phosphate (NADPH)-dependent glutathione reductase in the presence of oxidized glutathione. Although T3 binding to charcoal-extracted cytosol protein was not influenced by reduced glutathione or dithiothreitol, it was markedly increased by NADPH. Maximal activation induced by 50 microM NADPH was not further increased by further addition of endogenous factor b. The elution position of NADPH in gel chromatography corresponded to the elution position of factor b. Factor b or NADPH increased maximal binding capacity without changes in affinity constant. These observations suggest that T3-binding protein in cytosol is present in inactive and active forms and that the active form is generated by NADPH, which is present as one of the activators in cytosol. The effect of these cytosolic T3-binding proteins on nuclear T3 binding in vitro was also studied. In the absence of cytosolic T3-binding protein, [125I]T3 binding to nuclear receptor was decreased by unlabeled T3 in a concentration-dependent manner. In the presence of inactive form of cytosolic T3-binding protein, nuclear [125I]T3 binding was slightly diminished. In the presence of NADPH and cytosolic T3-binding protein, however, the amount of [125I]T3 bound to nuclei markedly decreased, which was associated with an increase of cytosolic [125I]T3 binding. NADPH alone did not influence nuclear T3 binding. These results suggest that T3 binding to nuclear receptor is regulated by an active form of cytosolic T3-binding protein in vitro.

BackgroundPrediabetes is an independent risk factor for cardiovascular diseases. Mean platelet volume (MPV) can reflect platelet activity, and high MPV is associated with thrombogenic activation and an increased risk of cardiovascular disease. In diabetic patients, MPV is higher when compared with normal subjects. However, the relationship between MPV and prediabetes is poorly understood. The purpose of the present study was to compare MPV in prediabetic and normoglycemic subjects, and to evaluate the relationship between MPV and fasting plasma glucose (FPG) levels in these two groups.MethodsWe retrospectively studied 1876 Japanese subjects who had undergone health checks at Iida Municipal Hospital. Age, sex, body mass index (BMI), blood pressure, medical history, smoking habits, alcohol intake, lipid profiles, FPG levels, and MPV were evaluated. Subjects were categorized into four groups according to FPG: Q1 (70 mg/dL ≤ FPG < 90 mg/dL, n = 467), Q2 (90 mg/dL ≤ FPG < 95 mg/dl, n = 457), Q3 (95 mg/dL ≤ FPG < 100 mg/dL, n = 442), and Q4 (100 mg/dL ≤ FPG < 126 mg/dL, n = 512). Q1, Q2, and Q3 were defined as normal FPG groups and Q4 was defined as prediabetic group.ResultsThe MPV increased with the increasing FPG levels, in the following order: Q1 (9.89 ± 0.68 fl), Q2 (9.97 ± 0.69 fl), Q3 (10.02 ± 0.72 fl), and Q4 (10.12 ± 0.69 fl). After adjusting for the confounding parameters, MPV of the prediabetic group was higher than that in other groups (P < 0.001 for Q4 vs. Q1 and Q2, and P < 0.05 for Q4 vs. Q3). MPV in the high-normal glucose group (Q3) was significantly higher than in the low-normal glucose group (Q1). MPV was independently and positively associated with FPG, not only in prediabetic subjects but also in normal FPG subjects (β = 0.020 and β = 0.006, respectively).ConclusionsMPV in patients with prediabetes was higher than that in normal subjects, and was positively associated with FPG levels in prediabetic and normal subjects.

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A novel NADPH-dependent cytosolic 3,5,3'-triiodo-L-thyronine (T3)-binding protein (CTBP) was purified by sequential fractionation of rat liver cytosol on Q-Sepharose, phenyl-Sepharose, red-Sepharose, and polyacrylamide gel electrophoresis under nondenaturing conditions. The CTBP had a sedimentation coefficient of 5.1S, a Stokes' radius of 35 A, and a calculated mol wt of 76,000. The apparently homogenous protein consisted of a dimer of a polypeptide chain with a mol wt of 38,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. NADPH increased both the affinity and maximal binding capacity for T3 in the 5.1S CTBP. The maximal activity to bind T3 was obtained by 3.0 x 10(-8) M NADPH. The calculated maximal affinity constant was 2.4 x 10(9) M-1, and the maximal binding capacity was 21,000 pmol T3/mg 5.1S CTBP. The order of affinity of iodothyronine analogs to the 5.1S CTBP was as follows: D-T3 greater than L-T3 greater than L-T4 greater than triiodothyroacetic acid. The optimal pH for T3 binding was 7.2-7.5. Ca2+, Mg2+, and Mn2+ (0.1-10 mM) did not influence T3 binding to CTBP. Zn2+ (1.0 mM), however, inhibited the binding. These results suggested that 5.1S NADPH-dependent CTBP, which is distinct from 4.7S CTBP that had been purified in our laboratory from rat kidney, is present in rat liver.

The administration of thyroxine during antithyroid drug treatment decreases both the production of antibodies to TSH receptors and the frequency of recurrence of hyperthyroidism.