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Biomedical subjects

L Tian

Publications and source records attributed to L Tian.

140 records · Page 8Linked to original sources
PubMed1992

Relative pre- and postjunctional effects of a new vecuronium analogue, Org 9426, at the rat neuromuscular junction.

We have studied the relative pre- and postjunctional neuromuscular blocking effects of Org 9426 in the isolated rat hemidiaphragm muscle using twitch tension and electrophysiological recording techniques. Postjunctional effects were assessed from decreases in twitch height and from end-plate current amplitude and time constant of decay. Prejunctional effects were assessed from the fade of tetanic twitch tension and end-plate current amplitude rundown. There were no significant differences between the relative pre- and postjunctional effects of Org 9426 and those of previously studied steroidal neuromuscular blocking compounds. It is concluded, therefore, that the rapid onset and short duration of Org 9426 seen in vivo is not a consequence of a strong prejunctional, relative to postjunctional, blocking effect of the compound.

Androstanols↗
PubMed1992

[Effect of gossypol on the proliferation of rat prostate cells studies in vivo and in vitro].

The effect of gossypol on prostate cells of rat was studied both in vitro and in vivo. For in vivo study, mature male Sprague Dawley rats were given gossypol orally, 5 mg/day, 5 times a week for one month. Then the prostates were examined histologically. By adding gossypol to the culture system directly, NbE-1 cells were used in vitro study. Several parameters, including histological structure, cell growth, DNA synthesis and mitotic cycle of cells were measured by different methods. The prostate size and weight in experimental rats decreased and significant differences between acini in controls and gossypol treated animals were noted. Acini of control prostate were full of protruding folds constituted by columnar epithelial cells, whereas, the most of the acini in treated animals were composing of cubic or square epithelial cells and epithelial folds were rarely seen. Thus, acini with normal appearance were about 14% less than that in controls. In the in vitro experiments, both cell proliferation and DNA synthesis decreased from 0 to 80% and from 0 to 90% respectively, when the concentrations of gossypol were increased from 0 to 20 micrograms/ml. It seems that 10 micrograms/ml of gossypol could cause the most significant inhibition in these two cellular functions. The cell mitotic assay showed that in treated groups, the cell number of S phase was decreased from 43 to 31%, this fact indicated that the inhibition on cell proliferation caused by gossypol might be due to preventing cells to enter S phase. Besides, inhibition effect on the proliferation of prostatic epithelial cells was dosage dependent and related to the duration of treatment.

Animals↗
PubMed1991

[Influence of experimental varicocele on the junctions of seminiferous epithelium].

Experimental varicoceles were created in adult male Wistar rats by partially occluding the left renal vein. The affect of the varicocele on ipsilateral testis was studied at intervals over 15 weeks via ultrathin sections and freeze-etching replica technique examined under electron microscope. Observations showed that varicocele resulted in injuries of Sertoli-Sertoli cell and Sertoli cell-spermatid junctional complexes. Abnormal changes of Sertoli cell-spermatid junctional complexes might lead to spermiogenic arrest and spermatids slough, while those of Sertoli-Sertoli cell junctional complexes to dysfunction of barrier and abnormal alteration of microenvironment of seminiferous tubule. Probably, this is one of the reasons that the fertility was not improved in some patients even after high level ligation of the internal spermatic vein.

Animals↗
PubMed1990

[Changes in platelet aggregation, TXB2 and 6-keto-PGF1 alpha in surgical shock].

Platelet aggregation rate (PAR), plasma concentration of TXB2 and 6-Keto-PGF1 alpha were measured in 26 patients with shock (hypovolumic shock 10 and septic shock 16) and 10 controls. PAR, plasma TXB2 and 6-Keto-PGF1 alpha were increased during shock, with TXB2 increased more significantly than 6-Keto-PGF1 alpha, accordingly the TXB2/6-Keto-PGF1 alpha ratio were raised during shock, especially in the septic cases. PAR, plasma TXB2 and 6-Keto-PGF1 alpha will decrease while shock become subsiding, and elevate while shock become irreversible. As a rule, the change of PAR is parallel with the concentration of plasma TXB2. The speed of platelet aggregation and plasma TXB2 concentration were higher in eleven mortal cases.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Electron microscopic observations of the effects of gossypol on the human endometrium.

Gossypol treatment of endometriosis and uterine myomas in 15 cases was started with a daily dose of 20 mg of gossypol-acetic acid twice a day for 20 days as a loading dose, followed by 40 mg (20 mg twice weekly). A maintenance dose of 20 mg was given weekly. The total course of treatment lasted about 6 months. Light and electron microscopic examination of the endometrium was carried out before treatment and 2, 3, 4, and 6 months after gossypol treatment. After gossypol treatment three different characteristics of the endometrium were noted: (1) irregular secretory activity, (2) proliferative activity, and (3) atrophy. On electron microscopic examination it was shown that there were important changes of the organelles, indicating suppressed secretory activity. Based on the above results, the nature and significance of the ultrastructural changes of the endometrium induced by gossypol were analyzed and the possibility of developing a new field of research in female contraception with gossypol was considered.

Endocrine Glands↗
PubMedDate not supplied

Age-dependent increase of indigenous DNA adducts in rat brain is associated with a lipid peroxidation product.

Indigenous DNA adducts (I-compounds) are considered to be a biomarker of aging tissues. Thus far, few studies have been conducted to investigate the accumulation patterns of I-compounds in the brain during aging. Particularly, identities of age-dependent I-compounds have largely remained unknown. In the current study, we have determined the amounts of I-compounds in the brains of male Fischer 344 rats at ages 1, 6, 12, 18, and 24 months using a 32P-postlabeling technique. The results indicate that I-compounds increase in the rat brain age dependently from 6 to 24 months of age. Total I-adduct levels (central and upper cutouts) increase 3.5-fold from 6 to 24 months. Contrary to the results of other investigators, brains of 1-month-old rats contain the highest level of I-compounds, which may be due to the hypermetabolic status during the infant period. In an effort to characterize I-compounds, different deoxynucleosides were coincubated with malondialdehyde (MDA). The results show that only deoxyguanosine (dGMP)-MDA adducts overlap with I-compounds of the rat brain DNA adducts map. A total of five dGMP-MDA adducts have been identified as responsible for I-compounds in brain tissues. It is known that brain tissue contains high levels of lipids that are susceptible to oxygen free radicals and that MDA is the most abundant and genotoxic product of lipid peroxidation. The present study provides supporting evidence that lipid peroxidation and its product (MDA) may play an important role in endogenous brain DNA modification, which may partly contribute to cerebral aging and age-related degenerative disorders of the brain. The accumulation of I-compounds with aging may serve as an index of indirect oxidative damage to DNA as evidenced by the presence of MDA-DNA adducts.

Aging↗