Inhibition of increasing effect of vanadate on glycogen content and lipoprotein lipase activity in fat pads by 5-N,N-hexamethylene amiloride.

Sodium orthovanadate (vanadate) increased the glycogen content in isolated rat fat pads in a dose-dependent manner up to 2 mM. Biochanin A, a specific inhibitor of tyrosine kinases, inhibited the increasing effect of vanadate or insulin on both glycogen content and lipoprotein lipase (LPL) activity in fat pads. The increasing effect of vanadate on glycogen content was not decreased by the replacement of Na+ with choline ion in the incubation medium. 5-N,N-Hexamethylene amiloride, a potent inhibitor of the Na+/H+ exchange system, showed a 50%-inhibition of the vanadate-increased LPL activity and glycogen content at 25 and 80 microM, respectively, suggesting that mechanisms of the inhibition differ in part between the vanadate actions. Furthermore, a similar inhibitory profile of the vanadate-increased glycogen content was observed with incubation in the presence of absence of Na+ in the medium. These results suggest that the activation of the Na+/H+ exchange system by vanadate is not involved in an increase in the glycogen content in fat pads.     

Hydrogen bonding structure and stability of alpha-chitin studied by 13C solid-state NMR

The structure and stability of hydrogen bonds in alpha-chitin were investigated by (13)C solid-state NMR measurements at different temperatures. Splitting of the carbonyl carbon signal for alpha-chitin was interpreted as two types of hydrogen bonding; the peaks at 173.5 and 175.8 ppm were assigned, respectively, to a carbonyl carbon hydrogen bonded exclusively to the NH group and a carbonyl carbon hydrogen-bonded to both NH and C(6)-OH groups. Approximately 60% of carbonyl groups exclusively contributed to the intermolecular hydrogen bonding and ca. 40% of them to the combination of intermolecular and intramolecular hydrogen bonding. Internal rotation around the C(5)-C(6) bond was detected at 55 degrees C.     

Rapid separation of barbiturates and benzodiazepines by capillary electrochromatography with 3-(1,8-naphthalimido)propyl-modified silyl silica gel

A capillary electrochromatographic (CEC) method was applied to the simultaneous separation of barbiturates (barbital, phenobarbital, secobarbital and thiopental) and benzodiazepines (nitrazepam, diazepam and triazolam). The separation was performed in a 75 microm i.d. capillary, packed with 3-(1,8-naphthalimido)propyl-modified silyl silica gel (NAIP), studying the effects of buffer pH and mobile phase composition. Using an applied voltage of 20 kV and the short-end injection method (9 cm capillary effective length), the mobile phase of 1.0 mM citrate buffer (pH 5.0) containing 45% methanol provided the baseline separation of seven toxic drugs in less than 9 min. In CEC with NAIP, the benzodiazepines were separated by the combination of hydrophobic and pi-pi interactions, whereas the separation of the barbiturates was based on the hydrophobic interaction.     

Gene transfer into mammalian cells by use of a nanosecond pulsed laser-induced stress wave

Plasmid DNA has been successfully delivered to mammalian cells by applying a nanosecond pulsed laser-induced stress wave (LISW). Cells exposed to a LISW were selectively transfected with plasmids coding for green fluorescent protein. It was also shown that transient, mild cellular heating (approximately 43 degrees C) was effective in improving the transfection efficiency.     

Capturing of acidic macromolecules from biological samples using a temperature-responsive polymer modified with poly-l-lysine

We synthesized a temperature-responsive polymer, N-(isopropylacrylamide)-methacrylic acid copolymer, to which poly-l-lysine was introduced. The synthesized polymer as well as the parent polymer showed reversible soluble-insoluble changes in response to temperature changes across the lower critical solution temperature at 32 degree C in an aqueous solution. We found that the polymer efficiently captured acidic bio-macromolecules such as RNA, glycosaminoglycans and mucin-type glycoproteins in biological samples, and the captured molecules were recovered using aqueous NaCl solutions at high concentration. The target acidic molecules thus obtained will be employed for further studies such as structural analysis after brief desalting procedure. The proposed method does not require any chromatographic separations, but only needs a small volume of an aqueous salt solution for releasing captured molecules. Overall procedures are quite easy and simple, and are completed at least within 1 h. We show a few examples for capturing RNA and glycosaminoglycans from cultured cells using the polymer.     

Synthesis,absolute configuration and conformation of optically active 1,2-homoheptafulvalene

An optically active 1,2-homoheptafulvalene was successfully synthesized and subjected to spectroscopic investigation. The cycloaddition of the optically active hydrocarbon with tetracyanoethylene (TCNE) and 4-phenyl-1,2,4-triazoline-3,5-dione(PTAD) gave a [4 + 2] cycloadduct and a mixture of [8 + 2] cycloadducts, respectively, which are both optically active.     

Enhanced terrace stability for preparation of step-free Si(001)-(2 x 1) surfaces

We show that depositing Si while annealing patterned Si(001)-(2 x 1) substrates at sublimation temperatures enhances terrace stability, permitting larger step-free areas to be produced in a given time than possible by annealing alone. We confirm this enhanced terrace stability using real-time low-energy electron microscopy observations, and quantitative microscopic modeling of step dynamics. Our measurements can be used to estimate the lateral variation in adatom concentration across large terraces, and to estimate an adatom diffusion length lambda approximately 10-30 microm at 1000 degrees C.