QT interval and QT dispersion before and after diet therapy in patients with simple obesity

To evaluate whether a disordered QT interval and its dispersion in obese patients, if any, may be improved by therapeutic weight reduction, 36 obese patients admitted to our university hospital were examined over a 5-year period from April 1, 1992 to March 31, 1997. Participants included 18 males and 18 females whose mean age +/- SD was 28 +/- 9 and 33 +/- 14 years, respectively, and whose mean body mass index +/- SD was 35 +/- 5 and 38 +/- 6 kg/m2, respectively. Thirty-six control patients were matched in age and gender with the obese patients. All the obese patients were treated with behavioral therapy together with very-low-calorie conventional Japanese diet (VLCD: 370 kcal/day). A standard 12-lead electrocardiogram (ECG) revealed longer maximum (445 +/- 32 msec, mean +/- SD) and minimum (388 +/- 29 msec) heart rate corrected QT intervals (QTc intervals) in the obese group than in the control group (P < 0.0001 for each). QTc dispersion, defined as the difference between maximum and minimum QTc intervals derived from 12-lead ECG, was greater in the obese group (57 +/- 19 msec) than in the control group (32 +/- 13 msec) (P < 0.0001). Both the maximum and minimum QTc intervals in the obese patients were shortened, respectively, to 434 +/- 28 msec and 377 +/- 29 msec (P < 0.05 for each) with no significant change in either QTc dispersion, QRS voltage, or QRS duration following weight reduction. The coefficient value from the linear regression line between QT interval and RR interval in the obese group was less than in the control group. Together, the results show that obesity per se causes both a prolongation of QTc interval and an increase in QTc dispersion, and that weight reduction improves the prolonged QTc interval observed in obese patients.     

Proteins recognized by antibodies against isolated cytological heterochromatin from rat liver cells change their localization between cell species and between stages of mitosis (interphase vs metaphase)

Heterochromatin in the cell nucleus seems to concentrate various proteins, such as Drosophila heterochromatin protein 1, which maintain the repressed state of gene expression. However, it still remains obscure how protein composition related to chromatin structure is different between heterochromatin and euchromatin in interphase nuclei. We isolated cytological heterochromatin from sonicated interphase nuclei obtained from rat liver cells and prepared antisera against it. The dense heterochromatic bodies seen in the preparation of intact nuclei were duplicated in a relatively pure form during the preparation of heterochromatin. In the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, differences between the fractions of heterochromatin and euchromatin were noted by their protein composition. Isolated heterochromatin was then digested by DNase after partial digestion with trypsin and its dense structure changed to become highly sensitive to DNase. The prepared antibodies reacted with the heterochromatin region of rat liver cell nuclei and isolated cytological heterochromatin; however, they did not react with euchromatin. Using immunohistochemistry, the antibodies bound to each cell nucleus in all tissues observed; some cell types were distinguished by their differential stainability (e.g. staining in the cytoplasm). Staining of the mitotic cells showed that the proteins recognized by the antibodies were localized in the cytoplasm and, in part, on the chromosomes. Based on the results of molecular cloning from rat liver cDNA library using the antibodies as a probe, it seemed that the antibodies mainly recognized two proteins similar to arginase and general vesicular transport factor p115, respectively. The results obtained from these experiments reveal that some proteins located in the heterochromatin of interphase liver cell nuclei seem to play important roles in condensing a portion of the chromatin structure during interphase and suggest that proteins composing heterochromatin might be changed according to cell types or the stage of the cell cycle.     

PKC signaling mediates global enhancement of excitatory synaptogenesis in neurons triggered by local contact with astrocytes

Here we provide evidence that astrocytes affect neuronal synaptogenesis by the process of adhesion. Local contact with astrocytes via integrin receptors elicited protein kinase C (PKC) activation in individual dissociated neurons cultured in astrocyte-conditioned medium. This activation, initially focal, soon spread throughout the entire neuron. We then demonstrated pharmacologically that the arachidonic acid cascade, triggered by the integrin reception, is responsible for the global activation of PKC. Local astrocytic contact also facilitated excitatory synaptogenesis throughout the neuron, a process which could be blocked by inhibitors of both integrins and PKC. Thus, propagation of PKC signaling represents an underlying mechanism for global neuronal maturation following local astrocyte adhesion.     

Comparative effect of repeated ingestion of difructose anhydride III and palatinose on the induction of gastrointestinal symptoms in humans

We evaluated the safety and change in fermentability from repeated ingestion of difructose anhydride III (DFAIII) in humans. A randomized controlled single-blind crossover study with thirteen subjects was conducted. Each subject ingested 5 g of DFAIII or palatinose daily for 12 days, before and after which the subject was loaded with 10 g of DFAIII and had breath hydrogen measured from 0 to 9 h (DL test) to evaluate the fermentability of DFAIII. The defecation frequency and abdominal symptom score were the same between each ingestion period. Moreover, DFAIII ingestion had no influence on blood test results. Only the breath hydrogen excretion in post-DFAIII ingestion was slightly higher at h 8 than the pre-ingestion. Consequently, repeated ingestion of DFAIII for 12 days was as safe as palatinose ingestion, especially with respect to abdominal symptoms and blood test results, and its high resistance to enterobacterial fermentation in humans was not impaired.     

Purification and characterization of a co(II)-sensitive alpha-mannosidase from Ginkgo biloba seeds

An alpha-mannosidase was purified from developing Ginkgo biloba seeds to apparently homogeneity. The molecular weight of the purified alpha-mannosidase was estimated to be 120 kDa by SDS-PAGE in the presence of 2-mercaptoethanol, and 340 kDa by gel filtration, indicating that Ginkgo alpha-mannosidase may function in oligomeric structures in the plant cell. The N-terminal amino acid sequence of the purified enzyme was Ala-Phe-Met-Lys-Tyr-X-Thr-Thr-Gly-Gly-Pro-Val-Ala-Gly-Lys-Ile-Asn-Val-His-Leu-. The alpha-mannosidase activity for Man(5)GlcNAc(1) was enhanced by the addition of Co(2+), but the addition of Zn(2+), Ca(2+), or EDTA did not show any significant effect. In the presence of cobalt ions, the hydrolysis rate for pyridylaminated Man(6)GlcNAc(1) was significantly faster than that for pyridylaminated Man(6)GlcNAc(2), suggesting the possibility that this enzyme is involved in the degradation of free N-glycans occurring in developing plant cells (Kimura, Y., and Matsuo, S., J. Biochem., 127, 1013-1019 (2000)). To our knowledge, this is the first report showing that plant cells contain an alpha-mannosidase, which is activated by Co(2+) and prefers the oligomannose type free N-glycans bearing only one GlcNAc residue as substrate.     

Dietary branched-chain amino acids suppress the expression of pancreatic amylase mRNA in rats

Regulators for pancreatic amylase were examined. Rats were fed ad libitum a 20% amino acid (AA) mixture diet (Con), a 60% AA diet (HA), a branched-chain amino acid (BCAA)-rich diet (BC), or a diet supplemented with AA other than BCAA (OA) for 7 d, or fed the Con, HA, BC diets or diets supplemented with individual BCAA. Activity and mRNA levels of pancreatic amylase in the BC and HA groups were lower than those in the Con and OA groups. Leucine and isoleucine contributed to these effects of the BC diet. The mRNA levels correlated with individual pancreatic BCAA concentrations but not with plasma insulin level. In conclusion, dietary BCAA, especially leucine and isoleucine, may reduce amylase mRNA and activity in rats.     

Reducing effect of ingesting tannic acid on the absorption of iron, but not of zinc, copper and manganese by rats

Interest in the beneficial effects of polyphenols, including tannic acid (TA), is increasing, although, these compounds also have adverse effects; for example, on the absorption of iron (Fe), and possibly other trace minerals. We examined the effect of a graded dose of TA on the absorption of Fe and compared with that of zinc (Zn), copper (Cu) and manganese (Mn) in rats. We also investigated the effect of TA on cecal fermentation which plays a role in absorption. In Experiment 1, to set the optimum dose of Fe, male Sprague-Dawley rats (weighing 70-90 g) after acclimatization were fed with different levels of dietary Fe (5, 10, 20, 30 and 35 mg/kg). We observed that the hematocrit (Ht), serum Fe concentration and transferrin saturation (%) were each reduced in those rats fed less than 20 mg/kg Fe in a dose-dependent manner. In Experiment 2, the rats were fed with test diets containing the minimum required level of Fe, 30 mg/kg diet, with (5, 10, 15 and 20 g/kg diet) or without TA for a period of three weeks. Feeding a diet containing more than 10 g TA/kg diet, but not 5 g TA/kg diet, reduced the hemoglobin concentration (Hb), Ht and serum Fe concentration due to decreased Fe absorption. In contrast, the Zn, Cu and Mn absorption was not affected by TA feeding. It is also demonstrated that liver Fe, but not the Zn, Cu and Mn contents, were lower in the TA groups than in the TA-free control group. Feeding TA slightly decreased the pH value of the cecal contents with an increase in the major short-chain fatty acid pool. About 15% of the ingested TA were recovered in the feces of each TA-fed group. Our results demonstrate that more than 10 g TA/kg diet induced anemia by reducing the Fe absorption, although there was no effect on the absorption of other important trace minerals. Our findings suggest that the usual intake of polyphenols is relatively safe, but that a high intake by supplementation or by dietary habit of tannin affects only the Fe level.     

Rectified photocurrent in a protein based molecular photo-diode consisting of a cytochrome b562-green fluorescent protein chimera self-assembled monolayer

We fabricated a self-assembled monolayer (SAM) of a chimeric protein created as a novel model protein for an artificial light-harvesting complex (LHC) composed of two proteins, cytochrome b(562) (cytb(562)) mutated for SAM fabrication (cytb(562), N22C, G82C) and enhanced green fluorescent protein (EGFP). The SAM formation of chimeric protein on a single-crystalline Au(111) substrate was confirmed by atomic force microscopy (AFM) measurement. The rectified photocurrent of the chimeric protein SAM on a gold substrate was detected by light-illumination scanning tunneling microscopy (LI-STM) co-operated with a lock-in technique. The photocurrent generation of the chimeric protein SAM was wavelength-specific to the light-illumination (488 nm), which indicated that the EGFP part of the chimera plays a role as a sensitizer in the photo-induced electron transfer process.     

Geranyl chalcone derivatives with antifungal and radical scavenging properties from the leaves of Artocarpus nobilis

Antifungal activity guided fractionation of the n-butanol extract from the methanol extract of the leaves of Artocarpus nobilis furnished 2',4',4-trihydroxy-3'-geranylchalcone (1), 2 ',4',4-trihydroxy-3'-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]chalcone (2), 2',4',4-trihydroxy-3'-[2-hydroxy-7-methyl-3-methylene-6-octaenyl]chalcone (3), 2',3,4,4'-tetrahydroxy-3'-geranylchalcone (4), 2',3,4,4'-tetrahydroxy-3'-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]chalcone (5). The chalcones 3 and 5 are new natural products whereas 1 and 2 are reported first time from the family Moraceae. All these compounds showed good fungicidal activity against Cladosporium cladosporioides and high radical scavenging activity towards the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical in TLC bio-autography method.     

Target proteins of the cytosolic thioredoxins in Arabidopsis thaliana

Possible target proteins of cytosolic thioredoxin in higher plants have been investigated in the cell lysate of dark-grown Arabidopsis thaliana whole tissues. We immobilized a mutant of cytosolic thioredoxin, in which an internal cysteine at the active site was substituted with serine, on CNBr activated resin, and used the resin for the thioredoxin-affinity chromatography. By using this resin, the target proteins for thioredoxin in the higher plant cytosol were efficiently acquired. The obtained proteins were separated by two-dimensional gel electrophoresis and analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Thus we have identified proteins of the anti-oxidative stress system proteins (ascorbate peroxidase, germin-like protein, and monomeric type II peroxiredoxin), proteins involved in protein biosynthesis (elongation factor-2 and eukaryotic translation initiation factor 4A), proteins involved in protein degradation (the regulatory subunit of 26S proteasome), and several metabolic enzymes (alcohol dehydrogenase, fructose 1,6-bis phosphate aldolase-like protein, cytosolic glyceraldehyde 3-phosphate dehydrogenase, cytosolic malate dehydrogenase, and vitamin B(12)-independent methionine synthase) together with some chloroplast proteins (chaperonin 60-alpha and 60-beta, heat shock protein 70, and glutamine synthase). The results in this study and recent proteomics studies on the target proteins of chloroplast thioredoxin indicate the versatility and the physiological significance of thioredoxin as reductant in plant cell.