Amino acid sequences of porcine fast and slow troponin T isoforms

In this study, 10 troponin T isoforms from adult porcine skeletal muscle messenger RNA were clarified. These were eight fast- and two slow-type isoforms. Fast-type isoforms had three and two variable exons in the N-terminal and the C-terminal region respectively. Slow-type isoforms had one variable exon in the N-terminal region.     

Activation of mitogen activated protein kinase (MAPK) during D-galactosamine intoxication in the rat liver

A significant increase in plasma glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase was observed 6 h after intraperitoneal administration of D-galactosamine (D-Galn). Three hours after administration of D-Galn, the vitamin C concentration in the liver decreased significantly compared to that in a control group and thereafter the hepatic vitamin C concentration remained at a significantly lower level. Phosphorylated JNK (c-Jun NH2-terminal kinase) and phosphorylated ERK (extracellular signal-regulated kinase) started increasing 3 h after D-Galn treatment and remained at a high level for 6-12 h after the treatment, while phosphorylated p38 MAPK increased significantly 6 h after D-Galn administration. These results indicated that oxidative stress and the activation of JNK and ERK took place almost simultaneously, followed by the activation of p38 MAPK.     

Fasting enhances p-Cresol production in the rat intestinal tract.

p-Cresol is a metabolite of aromatic amino acid metabolism produced by intestinal microflora, and its formation is influenced by intestinal conditions. Fasting drastically changes intestinal conditions. However, the effect of fasting on p-cresol production is unclear. In this study, serum and cecal p-cresol levels were determined in non-fasted rats and in rats fasting for either 12 or 18 h. Serum p-cresol increased significantly with 12-h fasting (3.44 +/- 2.15 nmol/ml; P<0.05) and 18-h fasting (5.40 +/- 2.20; P<0.001) as compared to the level in the non-fasted rats (1.02 +/- 0.50). Cecal p-cresol levels of the 12-h fasted (272.6 +/- 313.2 nmol/cecum) and 18-h fasted rats (436.6 +/- 190.8; P<0.01) were higher than those in non-fasted rats (27.1 +/- 21.9). The total cecal protein in content did not change with 18-h fasting. However, the cecal protein concentration increased significantly with fasting (P<0.001), and correlated closely with total cecal p-cresol contents (P<0.001). These results indicate that fasting enhances p-cresol production in the rat cecum, resulting in accumulation of serum p-cresol. We presume that the increase in p-cresol produced by fasting is related to the enhancement of bacterial nitrogen metabolism via an increased concentration of endogenous protein in the cecum.     

Study of drug effects of calcium channel blockers on retinal degeneration of rd mouse

In the present study, we studied drug effects of Ca(2+) antagonists on the retinal degeneration of rd mouse to evaluate their efficacy. Several kinds of Ca(2+) antagonists, diltiazem, nicardipine, nilvadipine or nifedipine were administrated intraperitoneally and thereafter retinal morphology and functions were analyzed. In addition, we performed DNA microarray analysis both in nilvadipine treated and control retinas to understand their drug effects at molecular levels. We found that nilvadipine caused significant preservation of retinal thickness in rd mouse during the initial stage of the retinal degeneration, and nicardipine showed also significant but lesser preservation than nilvadipine. However, we recognized no preservation effects of diltiazem and nifedipine. In the total 3774 genes, the expressions of 27 genes were altered upon administration of nilvadipine, including several genes related to the apoptotic pathway, neuro-survival factor, Ca(2+) metabolisms, and other mechanisms. It is suggested that some types of Ca(2+) channel blockers, such as nilvadipine and nicardipine, are able to preserve photoreceptor cells in rd mouse and can potentially be used to treat some RP patients.     

Disruption of the human pathogenic yeast Candida albicans catalase gene decreases survival in mouse-model infection and elevates susceptibility to higher temperature and to detergents

Catalase-deficient strains of the human pathogenic yeast Candida albicans were constructed using the URA-blaster method. The disruptant was viable and grew normally in an ordinary culture condition, but became extremely sensitive to treatment with hydrogen peroxide. No catalase activity was observed in a catalase (CCT)-gene-disrupted strain, 1F5-4-1, suggesting that there were no other catalase or catalase-like enzymes in this yeast. The disruptant was shown to be sensitive to higher temperature and to low concentrations of SDS, NP-40, or Triton X-100. After a wild-type CCT gene was reintroduced into the disruptant, catalase activity was restored and the strain became moderately sensitive to treatment with hydrogen peroxide. However, neither the temperature sensitivity nor the susceptibility to SDS observed in the disruptant was restored in the CCT-reintroduced strain. A model infection experiment using wild-type and dCCT strains showed that the disruptants disappeared more rapidly than the wild-type strain in mouse liver, lung, and spleen. These results suggest that the catalase plays a significant role in survival in the host immune system and thus leads this organism to establish infection in the host.     

Tyrosinase inhibitors from galls of Rhus javanica leaves and their effects on insects

As a defense mechanism of the leaves of Rhus javanica (Anacardiaceae) against the aphid Melaphis chinensis (Aphididae) attack, tannic acid is rapidly accumulated and forms galls along the midrib of the leaves resulting in a unique natural medicine Gallae Rhois. Tannic acid was found to inhibit the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) catalyzed by tyrosinase (EC 1.14.18.1) with an IC50 of 22 microM. The aphid would detoxify the ingested toxic tannic acid to relatively nontoxic gallic acid, whereas the non-adapted pink bollworm Pectinophora gossypiella larvae are sensitive to the ingested tannic acid.     

Growth arrest by octanoate is required for porcine preadipocyte differentiation

A preadipocyte clonal line has been established from porcine subcutaneous tissue. This line, designated PSPA, showed a fibroblastic phenotype and kept on growing under a preadipose condition even after reaching confluence. When confluent cultures were stimulated with insulin, dexamethasone, biotin, pantothenate, and octanoate, growth was arrested, and the cells exhibited a marked increase in lipogenesis. However, adipose conversion was not induced upon exposure of PSPA cells to a standard hormonal mixture of mouse 3T3-L1 cells, and they continued dividing as did the preadipocytes in growth medium. By serially omitting each individual adipogenic agent from the PSPA differentiation medium, it was determined that octanoate was one of the most essential but the only factor able to induce growth arrest. Octanoate supplementation to 3T3-L1 medium increased the triglyceride accumulation of PSPA cells accompanied by growth arrest. Both RT-PCR and Western blot analysis supported the idea of octanoate as a potential agent with the antiproliferative activity requisite for porcine preadipocytes to enter terminal differentiation.     

Positive effect of collagen V and VI on triglyceride accumulation during differentiation in cultures of bovine intramuscular adipocytes

Ethyl-3,4-dihydroxybenzoate (EDHB), a specific inhibitor of collagen synthesis, was used to study the role of collagen in the differentiation of bovine intramuscular preadipocytes (BIP). Triglyceride (TG) accumulation levels of BIP cells were dose-dependently inhibited by EDHB and were reduced to 50 % at a 0.1 mM concentration. EDHB addition prevented the accretion of collagens (types I-VI) on the cell surface, which generally increases during adipose conversion. Western blotting and immunofluorescence studies showed in detail that triple-helical conformation of procollagen molecules was drastically interrupted by EDHB, and as a result, their matrix assembly was not performed in the extracellular space of adipocytes. Particularly, the development of collagen types IV, V and VI during differentiation was severely damaged. When exogenous collagens were supplied to make up for the lack of endogenous products, cultured EDHB-treated cells on type V and VI collagen-coated dishes were the only ones among six collagens to accumulate more TG, although their TG content did not reach that of normal adipocytes. This result implies the importance and the active role of collagens V and VI for adipogenesis. However, these findings also indicate that collagen newly synthesized and organized by the adipocyte itself during differentiation is still necessary for the growth of adipose tissue.     

S(G), S(I), and EGP of exercise-trained middle-aged men estimated by a two-compartment labeled minimal model

To examine the effects of physical training on glucose effectiveness (S(G)), insulin sensitivity (S(I)), and endogenous glucose production (EGP) in middle-aged men, stable-labeled frequently sampled intravenous glucose tolerance tests (FSIGTT) were performed on 11 exercise-trained middle-aged men and 12 age-matched sedentary men. The time course of EGP during the FSIGTT was estimated by nonparametric stochastic deconvolution. Glucose uptake-specific indexes of glucose effectiveness (S(2*)(G) x 10(2): 0.81 +/- 0.08 vs. 0.60 +/- 0.05 dl. min(-1). kg(-1), P < 0.05) and insulin sensitivity [S(2*)(I) x 10(4): 24.59 +/- 2.98 vs. 11.89 +/- 2.36 dl. min(-1). (microU/ml)(-1). kg(-1), P < 0.01], which were analyzed using the two-compartment minimal model, were significantly greater in the trained group than in the sedentary group. Plasma clearance rate (PCR) of glucose was consistently greater in the trained men than in sedentary men throughout FSIGTT. Compared with sedentary controls, EGP of trained middle-aged men was higher before glucose load. The EGP of the two groups was similarly suppressed by approximately 70% within 10 min, followed by an additional suppression after insulin infusion. EGP returned to basal level at approximately 60 min in the trained men and at 100 min in the controls, followed by its overshoot, which was significantly greater in the trained men than in the controls. In addition, basal EGP was positively correlated with S(2*)(G) . The higher basal EGP and greater EGP overshoot in trained middle-aged men appear to compensate for the increased insulin-independent (S(2*)(G)) and -dependent (S(2*)(I)) glucose uptake to maintain glucose homeostasis.     

Electrophoretic Karyotypes of Candida Yeasts Recurrently Isolated from Single Patients

Candida strains were isolated repeatedly from single patients during recurrent episodes of Candida infection in a hospital, and their electrophoretic karyotypes were analyzed by pulsed-field gel electrophoresis using CHEF system. When only C. albicans (in 6 patients) or C. glabrata (in 1 patient) were recurrently isolated, their karyotypes from each patient were almost identical to one another, suggesting that they carried single type of the yeast. When multiple species were recovered from single patients (6 cases), the karyotypes of the most frequently recovered yeast species were almost identical with respect to each patient. The electrophoretic karyotype analysis has been proved to be useful for epidemiological studies because the method can tell not only the species identification but also the differences among the strains of the same species.