A new solid-phase synthesis of oligoribonucleotides by the phosphoro-p-anisidate method using tetrahydrofuranyl protection of 2''-hydroxyl groups.

Six nonaribonucleotides containing the 5'-splice site, one complementary nonamer and an octadecamer containing the 3'-splice site have been synthesized on a polymer support using the phosphoro-p-anisidate method. A 5'-linked 2'-O-tetrahydrofuranyl-N-protected nucleoside 3'-(o-chlorophenyl)phosphoro-p-anisidate was used as the starting nucleotide, and the chain elongated in the 3'-direction by removing the p-anisidate protecting group with isoamyl nitrite under neutral conditions. The octadecamer has been synthesized using dinucleotide blocks and a 3'-terminal trinucleotide.     

Reduction of glucose uptake through inhibition of hexose transporters and enhancement of their endocytosis by methylglyoxal in Saccharomyces cerevisiae

Diabetes mellitus is characterized by an impairment of glucose uptake even though blood glucose levels are increased. Methylglyoxal is derived from glycolysis and has been implicated in the development of diabetes mellitus, because methylglyoxal levels in blood and tissues are higher in diabetic patients than in healthy individuals. However, it remains to be elucidated whether such factors are a cause, or consequence, of diabetes. Here, we show that methylglyoxal inhibits the activity of mammalian glucose transporters using recombinant Saccharomyces cerevisiae cells genetically lacking all hexose transporters but carrying cDNA for human GLUT1 or rat GLUT4. We found that methylglyoxal inhibits yeast hexose transporters also. Glucose uptake was reduced in a stepwise manner following treatment with methylglyoxal, i.e. a rapid reduction within 5 min, followed by a slow and gradual reduction. The rapid reduction was due to the inhibitory effect of methylglyoxal on hexose transporters, whereas the slow and gradual reduction seemed due to endocytosis, which leads to a decrease in the amount of hexose transporters on the plasma membrane. We found that Rsp5, a HECT-type ubiquitin ligase, is responsible for the ubiquitination of hexose transporters. Intriguingly, Plc1 (phospholipase C) negatively regulated the endocytosis of hexose transporters in an Rsp5-dependent manner, although the methylglyoxal-induced endocytosis of hexose transporters occurred irrespective of Plc1. Meanwhile, the internalization of hexose transporters following treatment with methylglyoxal was delayed in a mutant defective in protein kinase C.     

Calcification process dynamics in coral primary polyps as observed using a calcein incubation method

Calcification processes are largely unknown in scleractinian corals. In this study, live confocal imaging was used to elucidate the spatiotemporal dynamics of the calcification process in aposymbiotic primary polyps of the coral species Acropora digitifera. The fluorophore calcein was used as a calcium deposition marker and a visible indicator of extracellular fluid distribution at the tissue-skeleton interface (subcalicoblastic medium, SCM) in primary polyp tissues. Under continuous incubation in calcein-containing seawater, initial crystallization and skeletal growth were visualized among the calicoblastic cells in live primary polyp tissues. Additionally, the distribution of calcein-stained SCM and contraction movements of the pockets of SCM were captured at intervals of a few minutes. Our experimental system provided several new insights into coral calcification, particularly as a first step in monitoring the relationship between cellular dynamics and calcification in vivo. Our study suggests that coral calcification initiates at intercellular spaces, a finding that may contribute to the general understanding of coral calcification processes.     

Novel polymer biomaterials and interfaces inspired from cell membrane functions

Background

Materials with excellent biocompatibility on interfaces between artificial system and biological system are needed to develop any equipments and devices in bioscience, bioengineering and medicinal science. Suppression of unfavorable biological response on the interface is most important for understanding real functions of biomolecules on the surface. So, we should design and prepare such biomaterials.

Scoop of review

One of the best ways to design the biomaterials is generated from mimicking a cell membrane structure. It is composed of a phospholipid bilayered membrane and embedded proteins and polysaccharides. The surface of the cell membrane-like structure is constructed artificially by molecular integration of phospholipid polymer as platform and conjugated biomolecules. Here, it is introduced as the effectiveness of biointerface with highly biological functions observed on artificial cell membrane structure.

Major conclusions

Reduction of nonspecific protein adsorption is essential for suppression of unfavorable bioresponse and achievement of versatile biomedical applications. Simultaneously, bioconjugation of biomolecules on the phospholipid polymer platform is crucial for a high-performance interface.

General significance

The biointerfaces with both biocompatibility and biofunctionality based on biomolecules must be installed on advanced devices, which are applied in the fields of nanobioscience and nanomedicine.This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine.     

Clinical Significance of IgG Antibody Titer against Helicobacter pylori

Background: We clarified the clinical significance of measurement of IgG antibody titers against Helicobacter pylori using data from a nested case–control study from a large-scale cohort study in Japan.
Method: Participants included 36,745 subjects from the Japan Health Center-based Prospective Study who responded to the baseline questionnaire and provided a blood sample. Subjects were aged 40–69 years and were followed over 15 years after initial sampling. Controls were matched to 511 gastric cancer patients. Plasma surface antigen (Hp)-IgG titer was measured using ELISA, and mucosal atrophy was determined by measuring pepsinogen I and II levels.
Results: Seropositive subjects with low Hp-IgG titer and mucosal atrophy showed a higher risk for gastric cancer than high-titer subjects. Odds ratio (OR) referred to cases with true negative IgG titers and no mucosal atrophy. In moderately atrophic subjects, the low titer OR was 19.0, with a 95% confidence interval (CI) of 7.7–46.9, and 12.5 for high titer, with a 95% CI of 5.2–30.0. In severely atrophic subjects, the low titer OR was almost double that of high-titer subjects (OR = 30.2, 95% CI = 12.4–73.7 and OR = 15.9, 95% CI = 6.3–40.3, respectively). These associations were observed more frequently for differentiated than undifferentiated gastric cancer.
Conclusion: Combination assay with Hp-IgG titer and pepsinogens may help identify groups at high risk for gastric cancer. Subjects with low Hp-IgG titer and mucosal atrophy were at extremely high risk for gastric cancer, particularly differentiated cancer. Subjects with this background may require ongoing observation and periodic endoscopic examination for early cancer detection.     

Developmental expression and intracellular location of P400 protein characteristic of Purkinje cells in the mouse cerebellum

The developmental expression and intracellular localization of a cerebellum-characteristic 250-kDa glycoprotein, P400 protein, were studied by immunohistochemical and immunoblot methods using a monoclonal antibody against P400 protein. In the cerebellum of normal mouse, the expression of P400 protein increased from Postnatal Day 3 to Day 21. This enhancement of P400 protein expression occurred only in the Purkinje cells and proceeded with the growth of their dendritic arborization. Electron microscopic analysis indicated that P400 protein is present at the plasma membrane, the endoplasmic reticulum, and the postsynaptic densities of Purkinje cells. Immunohistochemistry of the cerebella of neurological mutant mice indicated that the Purkinje cells of reeler, weaver, and pcd mutant mice retain the ability to produce a large amount of P400 protein. However, the Purkinje cells of staggerer mutant mouse proved to be incapable of enhanced P400 protein expression. These results indicate that P400 protein is a Purkinje cell-characteristic plasma membrane-associated glycoprotein, which is also present at the postsynaptic density and endoplasmic reticulum and that the expression of P400 protein in Purkinje cells is closely associated with the growth of their dendritic arborization.     

Starvation-induced changes in rat brain corticotropin-releasing factor (CRF) and pituitary-adrenocortical response

Starvation-induced changes in CRF concentration in major brain regions and abnormalities in the pituitary-adrenal axis were examined in rats using rat CRF radioimmunoassay. The CRF concentrations in the hypothalamus and cerebellum were significantly reduced in the completely starved rats, while those in the midbrain, thalamus and neurointermediate lobe of the pituitary were significantly increased in the semi-starved or completely starved rats. No significant changes in the CRF concentrations were found in the pons, medulla oblongata and cerebral cortex. In the completely starved rats, the serum ACTH level was significantly reduced, whereas the serum corticosterone level was markedly elevated. These observations suggest that starvation may stimulate the CRF-ACTH-corticosterone system and that not only hypothalamic CRF but also extrahypothalamic CRF may be discretely related to feeding behavior or starvation. The reduced serum ACTH level in starved rats may be ascribed to the negative feedback effect of the elevated serum corticosterone.