Biomedical subjects

Y H Bai

Publications and source records attributed to Y H Bai.

7 recordsLinked to original sources

PubMed1999

Peripheral mononeuropathy induced by loose ligation of the sciatic nerve in the rat: behavioral, electrophysiological and histopathologic studies.

The relationship between clinical parameters and pathological changes was investigated in an animal model of mononeuropathy, by behavioral, electrophysiological and histopathological methods. Mononeuropathy was induced in rats by loosely tying ligatures around the sciatic nerve. Eighty-four rats were used, and these were divided into fourteen groups to determine chronological changes in the withdrawal reflex latency, nerve conduction velocity and ultrastructure of the nerve from 1 to 84 days after nerve ligation surgery. Pathological changes around the ligated nerves were divisible in three phases: the first week was an inflammatory phase, when axonal degeneration, phagocyte infiltration and interstitial edematous changes were observed. The second and third weeks were a nerve-sprouting phase, when numerous axonal sprouts and remyelination were seen. The fourth to twelfth weeks were a recovery phase in which maturing myelination and interstitial fibrosis were characteristic. In the inflammatory phase, withdrawal reflex latencies were shortened, and sensory nerve conduction velocities (SCV) and motor nerve conduction velocities (MCV) gradually decreased. In the nerve-sprouting phase, the latency values remained low, and SCV and MCV were minimal. The parameters examined gradually returned to control levels during the recovery phase. In conclusion, these findings increase the knowledge of disease progression in mononeuropathy with hyperalgesia in human and animal models.

Animals↗

PubMed1998

Pathology study of rabbit calf muscles after repeated compression.

: To elucidate the pathogenesis of chronic compartment syndrome, we examined pathological changes in the soleus (red) and extensor digitorum longus (EDL; white) muscles in Japanese white rabbits after repeated compression with a pneumatic tourniquet. Repeated tourniquet compression via cuff inflation was carried out on the rabbits, calves daily, for 2 h, then stopped for 30 min, and then applied for another 2 h. The contralateral hindlimb, which was not compressed, served as a control. Animals were allocated to 15 groups, with pressures of 40, 80, and 120 mmHg for periods of 1 day, 3 days, 1 week, 2 weeks, and 4 weeks. Skeletal muscle specimens in each group were studied by histopathological and histochemical (ATPase) methods. After compression for 1 day, regardless of pressure, and compression for 3 days in the 40-mmHg pressure group, edematous changes in regions with mild inflammation and increases in fiber diameter were observed in the muscles. After compression for 3 days in the 80- and 120-mmHg pressure groups, and after 1, 2, or 4 weeks in the 40-mmHg pressure group, a few necrotic fibers and scattered fibers with some mononuclear cell infiltrates indicative of early-stage necrosis were detected. In the groups with 80 or 120 mmHg pressure for 1, 2, or 4 weeks, muscle fibers exhibited marked degenerative changes, which were more pronounced in the 120-mmHg group than in the 80-mmHg group. The pathological changes were more pronounced in the soleus than in the EDL muscles, indicating that these two muscles differed in sensitivity to repeated compression. Additionally, average muscle wet weight and average fiber diameter for both types of muscle were increased in the 1-day and 3-day compression groups and decreased in the 1-week, 2-week, and 4-week compression groups. These findings clearly differ from those of previously reported single-compression experiments. Our findings indicate that repeated compression may cause serious muscle degeneration, particularly in red muscles.

Adenosine Triphosphatases↗

PubMed1998

Selective induction of apoptosis of NB4 cells from G2+M phase by sodium arsenite at lower doses.

Apoptosis of NB4 cells induced by sodium arsenite and arsenate was studied using flow cytometry and DNA gel electrophoresis in order to investigate their effects on cell cycle and determine the relationship between apoptosis and cell cycle. In this study, we found that: 1) at low doses, sodium arsenite selectively induced apoptosis of NB4 cells in G2+M phase of cell cycle after its being arrested in G2 phase. With increment of the cells blocked in G2 phase, dUTP-specifically labeling cells in G2+M phase increased without concomitant increment of dUTP-labeling cells in other two phases of cell cycle; 2) at high doses, extensive apoptosis was induced in NB4 cells from all phases of cell cycle without cell cycle preference and cell cycle blockade; 3) sodium arsenite-induced apoptosis of NB4 cells occurred in the presence of bcl-2 expression as the unapoptotic cells; 4) sodium arsenite with As3+ induced apoptosis of NB4 cells more strongly than sodium arsenate with As5+ did although both of them affected NB4 cells in the same pattern. These results not only suggested that both arsenite and arsenate induced apoptosis of NB4 cells through 2 different mechanisms--at low doses, arsenical might directly induce apoptosis through regulation of cell cycle checkpoint, while at high doses they might directly induce it, but also indicated that bcl-2 might not play an important role in arsenite or arsenate-induced apoptosis of NB4 cells, whereas chemical valence of As in a compound might be related to efficiency in arsenical induction of apoptosis.

Apoptosis↗

PubMed1997

Expression of transforming growth factor beta in radiation interstitial pneumonitis.

We investigated the changes in transforming growth factor beta 1 (TGF-beta 1) mRNA and TGF-beta 3 protein expression that occur in radiation interstitial pneumonitis. We used TGF-beta 1-cDNA probe in situ hybridization and TGF-beta 3 polyclonal antibody in immunohistochemical techniques. Our results showed that the distribution of TGF-beta 1 mRNA and TGF-beta 3 protein basically coincided in blood vessels, airways, lung parenchyma, and alveolar macrophages. However, bronchial epithelial cells expressed only TGF-beta 3 proteins and no TGF-beta 1 mRNA. We found an increased expression of TGF-beta 1 mRNA and TGF-beta 3 proteins in radiation interstitial pneumonitis.

Animals↗

PubMed1995

Effect of transmembrane Ca2+ gradient on Gs function.

Gs and adenylate cyclase from bovine brain cortices were co-reconstituted into asolectin liposomes with or without 1000-fold transmembrane Ca2+ gradient. Obtained results showed that Gs activities of both binding GTP gamma S and stimulating adenylate cyclase were the highest in proteoliposomes, with a transmembrane Ca2+ gradient similar to the physiological situation and the lowest while the transmembrane Ca2+ gradient was in the inverse direction. Such a difference could be diminished following the dissipation of the transmembrane Ca2+ gradient by A23187. Time-resolved fluorescence anisotropy of diphenylhexatriene (DPH) has been used to compare the physical state of phospholipids among those proteoliposomes. It is suggested that a proper transmembrane Ca2+ gradient is essential for higher membrane fluidity, which may favor Gs function with higher GTP-binding activity and stimulation of adenylate cyclase.

Adenylyl Cyclases↗

PubMed1994

Collagen gene expression in radiation interstitial pneumonitis.

By using type I and type III collagen cDNA probe and cDNA-mRNA in situ hybridization, we observed the changes of rat lung alpha 1(I) and alpha 1(III) collagen gene expression in radiation interstitial pneumonitis. The results showed that the expressed cell of type I and type III collagen were scattered within the fibroblasts in the thickened interalveolar walls. The type I and type III collagen mRNA content in irradiated animals were higher than those in the controls at 0.5, 1, 2, 3, 6, and 12 months.

Animals↗

PubMedDate not supplied

The role of free radicals in the development of radiation interstitial pneumonitis.

We examined the morphologic changes in the lung tissue of Wistar rats after chest irradiation and determined sequentially the content of free radicals (FR) using electron spin resonance. The activity of superoxide dismutase (SOD) was also assessed using the chemical glow method of xanthine oxidase. After chest irradiation, the content of FR in the lung progressively increased and the activity of SOD progressively decreased. We discuss here the role of the FR in the developing process of radiation interstitial pneumonitis.

Animals↗