40,114 research outputs found
The lipid composition and its alteration during the growth stage in pathogenic fungus, epidermophyton floccosum
Qualitative and quantitative changes of lipid components during the growth stages were studied in E. floccosum. The acyl group components of total lipids of Trichophyton rubrum and Microsporum cookei were also examined. The lipids of E. floccosum amounted to approximately 4% of the dry cell weight. Neutral lipids mainly consisted of triglycerides and sterols, and major polar lipids were phosphatidylcholine, phosphatidylethanolamine, and an unknown lipid X. The fatty acids in tryglycerides and phospholipids were palmitic, palmitoleic, stearic, oleic, and linoleic acids. The unknown polar lipid X which appeared between phosphatidylethanolamine and cardiolipin on thin layer chromatography plates contained no phosphorus. There was no significant change in the fatty acid components of E. floccosum and T. rubrum during the cell growth, whereas profound changes occurred in M. cookei. The sterol components of E. floccosum showed striking changes depending on the growth stage
Superconducting Gap Function in Antiferromagnetic Heavy-Fermion UPd_2Al_3 Probed by Angle Resolved Magnetothermal Transport Measurements
The superconducting gap structure of heavy fermion UPd_2Al_3, in which
unconventional superconductivity coexists with antiferromagnetic (AF) order
with atomic size local moments, was investigated by the thermal conductivity
measurements in a magnetic field rotating in various directions relative to the
crystal axes. The results provide strong evidence that the gap function
\Delta(k) has a single line node orthogonal to the c-axis located at the AF
Brillouin zone boundary, while \Delta(k) is isotropic within the basal plane.
The determined nodal structure is compatible with the resonance peak in the
dynamical susceptibility observed in neutron inelastic scattering experiments.
Based on these results, we conclude that the superconducting pairing function
of UPd_2Al_3 is most likely to be d-wave with a form \Delta(k)=\Delta_0
cos(k_zc)Comment: 10 pages, 9 figure
Amplification of Quantum Meson Modes in the Late Time of Chiral Phase Transition
It is shown that there exists a possibility of amplification of amplitudes of
quantum pion modes with low momenta in the late time of chiral phase transition
by using the Gaussian wave functional approximation in the O(4) linear sigma
model. It is also shown that the amplification occurs in the mechanism of the
resonance by forced oscillation as well as the parametric resonance induced by
the small oscillation of the chiral condensate. These mechanisms are
investigated in both the case of spatially homogeneous system and the spatially
expanded system described by the Bjorken coordinate.Comment: 17 pages, 16 figure
Analysis of Voltage-Contrast Decay on Passivated Devices under Electron Beam Probing
Voltage-contrast decay on passivated devices under electron beam probing has been reported. The dependence of the decay time constant of the voltage contrast on the primary electron current, the passivation thickness, and the dielectric constant of the passivation has been analyzed with a recently developed theory of capacitive-coupling voltage contrast. It is found that the theory can be used to estimate the time constant under various observation conditions. Deviation of the time constant from the prediction, depending on the size of the electron beam irradiated area, has been observed and interpreted as being due to secondary electron charging on the surface above the electrode area during electron irradiation of the surrounding surface
Intestinal Metaplasia —The Effect of Acid on the Gastric Mucosa and Gastric Carcinogenesis—
This review concerns stem cells and their relation to intestinal metaplasia. When
gastric regions of mice, Mongolian gerbils or several strains of rats were
irradiated with a total dose of 20 Gy of X-rays given in two fractions,
intestinal metaplasia was only induced in rats. In addition, it was greatly
influenced by rat strain and sex. Alkaline phosphatase (ALP) positive
metaplastic foci were increased by administration of ranitidine (H2
receptor antagonist), crude stomach antigens or subtotal resection of the fundus
and decreased by cysteamine (gastric acid secretion stimulator), histamine or
removal of the submandibular glands. Recent studies have shown that
Cdx2 transgenic mice with gastric achlorhydria develop
intestinal metaplasia and that in men and animals, Helicobacter
pylori (H. pyrlori) infection can cause intestinal metaplasias
that are reversible on eradication. Our results combined with findings for
H. pylori infection or eradication and transgenic mice
suggest that an elevation in the pH of the gastric juice due to disappearance of
parietal cells is one of the principal factors for development of reversible
intestinal metaplasia. When different organs were transplanted into the stomach
or duodenum, they were found to transdifferentiate into gastric or duodenal
mucosae, respectively. Organ-specific stem cells in normal non-liver tissues
(heart, kidney, brain and skin) also differentiate into hepatocytes when
transplanted into an injured liver. Therefore, stem cells have a multipotential
ability, transdifferentiating into different organs when transplanted into
different environments. Finally, intestinal metaplasia has been found to
possibly increase sensitivity to the induction of tumors by colon carcinogens of
the 1,2-dimethylhydrazine (DMH), azoxymethane (AOM) or
2-amino-1-methyl-6-phenylimidazo[4.5-b]pyridine (PhIP) type. This carcinogenic
process, however, may be relatively minor compared with the main gastric
carcinogenesis process induced by N-methy1-N’-nitro-N-nitrosoguanidine (MMNG) or
N-methylnitrosourea (MNU), which is not affected by the presence of intestinal
metaplasia. The protocol used in these experiments may provide a new approach to
help distinguish between developmental events associated with intestinal
metaplasia and gastric tumors
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