Formation and electrical transport properties of pentacene nanorod crystal.

The monophasic formation of an uncharted pentacene crystal, the pentacene nanorod, has been investigated. The restricted formation of the pentacene nanorod on a bare mica surface reveals a peculiar surface catalytic crystal growth mode of the pentacene. We demonstrated the charge transport measurements through a single pentacene nanorod and analyzed the data using a periodic hopping conduction model. The results revealed that the pentacene nanorod has a periodic conductive node within their one-dimensional crystal.

The value of LYM-1 cells for examining vacuole formation and loss of cell viability induced by culture supernates of Helicobacter pylori.

Some strains of Helicobacter pylori are known to produce an extracellular cytotoxin that causes vacuolation in cultured mammalian cells. Screening for such strains makes use of HeLa cells which may not be sensitive enough to detect minimal changes. The aim of this study was to develop a more sensitive cell line. Vacuole formation was examined in HeLa cells, as well as four other cell lines established in this laboratory by ammonium chloride induction. Among five cell lines tested, LYM-1 cells were most sensitive for the detection of intracellular vacuolation with this agent. Loss of cell viability of LYM-1 and HeLa cells induced by H. pylori culture supernates was also examined: LYM-1 were more sensitive than HeLa cells. Cell death was not always accompanied by vacuole formation. This suggests that the mechanism whereby cell death occurs must be different from that for vacuole formation. LYM-1 cells may be useful when measuring vacuole formation and cell death of the cultured cells induced by culture supernates of clinical isolates of H. pylori.

Metabolism of gamma-linolenic acid in primary cultures of rat hepatocytes and in Hep G2 cells.

Incorporation and metabolism of gamma-linolenic acid (GLA) in both rat hepatocytes and Hep G2 cells were compared to those of oleic (OA), linoleic (LA), alpha-linolenic (LLA), and dihomo-gamma-linolenic (DGLA) acids. The incorporation of GLA into both types of cells was higher than LLA and DGLA, but lower than OA and LA. It was efficiently converted into DGLA in both types of cells and increased the concentration of DGLA. LLA was converted to a small amount of C20:4 (n-3) only in Hep G2 cells. Incubation with LA, GLA, LLA, and DGLA did not increase the concentration of arachidonic acid (AA) in both types of cells. LA. GLA, LLA, and their metabolites were incorporated into phosphatidylcholine, but only GLA and its metabolite, DGLA, were also incorporated into phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol. The coexistence of GLA and LLA during their catabolism diminished the amounts of respective metabolite in Hep G2 cells. The presence of GLA inhibited completely the formation of C20:4(n-3) from LLA. The results indicate that GLA is more effective in raising the ratio of DGLA/AA. Also, polyunsaturated fatty acids of n-3 and n-6 series have competitively catabolized in both types of hepatocytes.

Airway hyperresponsiveness after endotoxin inhalation depends on leukocyte infiltration.

We have investigated the relationship between acute airway hyperresponsiveness and polymorphonuclear cell (PMN) migration in airways following saline or endotoxin (ET) aerosol inhalation in 63 guinea pigs. In 20 of these animals, granulocytopenia was induced by prior treatment with hydroxyurea (HU). Airway responsiveness (AR) to inhaled methacholine, together with leukocyte counts in bronchoalveolar lavage fluid (BALF) and in tracheal epithelium, was also examined before and at 30 min, 1, 3 and 6 hr after saline or ET inhalation. In saline inhalation groups, AR and PMN counts in BALF and in tracheal epithelium did not differ from control animals at any time points. However, in ET inhalation groups AR increased significantly at 1 and 3 hr and returned to the pre-exposure level at 6 hr. This period of hyperresponsiveness was associated with an increment of PMN migration into tracheal epithelium. However, the increment of PMN counts in BALF was delayed to 3 and 6 hr after ET. In HU treated animals, AR and PMN counts in BALF and in tracheal epithelium did not change during 6 hr after ET inhalation. These results suggest that the hyperresponsiveness induced by ET inhalation either depends upon PMN migration into the tracheal epithelium.

[Peripheral airway obstruction and treatment].

The effect of medication on peripheral airway obstruction was examined in cases of bronchial asthma. Subjects were 1) patients with exercise-induced asthma, 2) an animal model of hyperventilation-induced asthma and 3) patients with chronic asthma. Peripheral airway obstruction was induced in 30 of 51 patients with exercise-induced asthma. Induction of peripheral airway obstruction was protected significantly by procaterol. Cromoglycate was effective in 12 of 17 patients but ipratropium was not effective against induction of peripheral airway obstruction. In the animal model, humid air inhalation, procaterol and ipratropium completely prevented hyperventilation-induced bronchoconstriction, but cromoglycate caused only partial prevention. In cases of chronic asthma with peripheral airway obstruction, beclomethasone inhalation reduced the symptom rating rapidly, but no changes were observed in pulmonary function and threshold of airway responsiveness. Cromoglycate was started in patients with chronic asthma who had been treated with beclomethasone. After cromoglycate administration, therapeutic rating decreased, but increased again after 8 weeks of cromoglycate therapy. Peripheral airway obstruction induced by exercise or hyperventilation could be prevented by adequate premedication, but chronic peripheral airway obstruction was difficult to treat.