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Biomedical subjects

Z Y Hu

Publications and source records attributed to Z Y Hu.

At least 37 records · Page 2Linked to original sources
PubMed1995

Stimulation of group II phospholipase A2 mRNA expression and release in an immortalized astrocyte cell line (DITNC) by LPS, TNF alpha, and IL-1 beta. Interactive effects.

Astrocytes are immunoactive cells in brain and have been implicated in the defense mechanism in response to external injury. Previous studies using cultured glial cells indicated the ability of astrocytes to respond to bacteria endotoxin and cytokines, resulting in the release of phospholipase A2. In this study, we examined the interactive effects of lipopolysaccharides (LPS), interleukin 1 beta (IL-1 beta) and tumor necrosis factor (TNF alpha) to stimulate phospholipase A2 (PLA2) in an immortalized astrocyte cell line (DITNC) with many properties of type I astrocytes. Northern blot analysis using oligonucleotide probes derived from the cDNA encoding the rat spleen group II PLA2 indicated the ability of DITNC cells to respond to all three factors in the induction of gene expression and the release of PLA2. After an initial lag time of 2 h, PLA2 release was proportional to time, reaching a plateau by 12 h. This event occurred at a time period preceding any signs of cell death. Cycloheximide at 1.25 microM completely inhibited cytokine-induced PLA2 release. When suboptimal amounts of TNF alpha were added to the DITNC culture together with IL-1 beta or LPS, a synergistic increase in the induction of PLA2 release could be observed. On the other hand, combination of IL-1 beta and LPS resulted only in an additive increase in PLA2 release. Antibodies to IL-1 beta and TNF alpha completely neutralized the effects of these two agents on PLA2 release. However, neither antibody was able to inhibit the PLA2 release induced by LPS, suggesting that the effect of LPS was not complicated by the release of IL-1 beta or TNF alpha. Taken together, results show that the immortalized astrocyte cell line (DITNC) can be used for studies to elucidate the molecular mechanism underlying the cytokine signaling cascade and subsequent induction of PLA2 synthesis.

Animals↗
PubMed1995

Hormonal regulation of tissue-type plasminogen activator and plasminogen activator inhibitor type-1 in cultured monkey Sertoli cells.

Sertoli cells play a central role in the control and maintenance of spermatogenesis. Isolated Sertoli cells of mouse and rat testes have been shown to secrete plasminogen activator (PA) and a plasminogen activator inhibitor type-1 (PAI-1) in culture. In this study, we have investigated the hormonal regulation of PA and PAI-1 activities in cultured monkey Sertoli cells. Sertoli cells (5 x 10(5) cells/well) isolated from infant rhesus monkey testes were preincubated at 35 degrees C for 16 h in 24-well plates precoated with poly(D-lysine) (5 micrograms/cm2) in 0.5 ml McCoy's 5a medium containing 5% of fetal calf serum and further incubated for 48 h in 0.5 ml serum-free medium with or without various hormones or other compounds. PA as well as PAI-1 activities in the conditioned media were assayed by fibrin overlay and reverse fibrin autography techniques respectively. The Sertoli cells in vitro secreted only tissue-type PA (tPA), no detectable amount of urokinase-type PA (uPA) could be observed. Monkey Sertoli cells were also capable of secreting PAI-1. Immunocytochemical studies indicated that both tPA and PAI-1 positive staining localized in the Sertoli cells, spermatids and residual bodies of the seminiferous epithelium; Northern blot analysis further confirmed the presence of both tPA and PAI-1 mRNA in monkey Sertoli cells. Addition of follicle-stimulating hormone (FSH) or cyclic adenosine monophosphate (cAMP) derivatives or cAMP-generating agents and gonadotrophin-releasing hormone (GnRH) agonist or phorbol ester (PMA) to the cell culture significantly increased tPA activity.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗
PubMed1995

Stimulation of phospholipase A2 expression in rat cultured astrocytes by LPS, TNF alpha and IL-1 beta.

Results from this study are in good agreement with those reported by Oka and Arita (1991) who demonstrated induction of PLA2 mRNA expression in primary astrocytes in response to LPS, TNF alpha and IL-1 beta. In general, the increase in PLA2 mRNA correlated well with the extent of PLA2 secretion into the culture medium. Using the immortalized astrocyte cell line (DITNC), similar induction of PLA2 mRNA expression and secretion of the enzyme into the culture medium could be observed. The lack of hydrolysis of labeled PI to DG further confirmed the specificity of cytokine induction of PLA2 release into the culture medium. By comparing the time course for PLA2 release with that for LDH release, it can be concluded that cytokine induction of PLA2 release is not related to events accompanying cell death due to serum deprivation. Although it has been well demonstrated that exposure of astrocytes to LPS can induce the synthesis and release of TNF alpha and IL-1 beta, the mechanism underlying this event has not been elucidated (Lieberman et al., 1989). Furthermore, how LPS as well as other cytokines induce the mRNA expression and secretion of PLA2 remains to be investigated. The availability of the immortalized astrocyte cell line (DITNC) will be a useful tool for this type of study. These cells are easy to culture and large preparations can be obtained. In addition, these cells will be useful as a model to relate the effects of cytokines on other cellular and metabolic events that may be directly or indirectly linked to the PLA2 cascade.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Effect of prolactin on gonadotropin-induced ovarian estrogen and progesterone production in mouse].

Immature mice (21-23 days old) were injected with 8 IU PMSG to stimulate follicle growth and followed 24 h later by either injection of 8 IU hCG alone or hCG plus 100 micrograms of prolactin (PRL). The animals were killed at 3, 12 and 24 h after hCG treatment. The ovaries and blood samples were collected. Granulosa cells were prepared for incubation. Progesterone and estrogen concentrations in both the serum and the culture medium were determined. The results showed that PRL significantly enhanced hCG-induced mouse serum progesterone content, while serum estrogen concentrations were considerably decreased by the co-injection of PRL. Prolactin was also capable of stimulating gonadotropin-induced progesterone secretion in the cultured GC. However, the aromatase activity induced by FSH and hCG was remarkably inhibited by the presence of PRL. These data suggest that PRL inhibition of hCG-induced ovulation may be due to its interference with the gonadotropin-induced estrogen production by the follicular granulosa cells.

Animals↗
PubMed1994

[Stereotactic radiosurgery by isocentric linear accelerator].

Stereotactic radiosurgery by isocentric linear accelerator, new technique developed in neurosurgery, was used to treat 92 patients with deeply localized cerebral tumors. Its indications and the techniques of improving its effect, preventing its complication were underlined.

Adenoma↗
PubMed1993

Effects of chlorpromazine on phosphatidylserine biosynthesis in rat pup brain exposed to ethanol in utero.

Phosphatidylserine biosynthesis in rat pup brain was examined by assaying the serine base-exchange enzyme activity in the microsomal and plasma membrane fractions, and by measuring the incorporation of [3H]serine into phosphatidylserine in brain slices and in the intact brain. Chlorpromazine, either added in vitro into the incubation system or administered to animals via i.p. injection or feeding a liquid diet, gave rise to an increase in the phosphatidylserine biosynthesis activity. Ethanol administered in the form of a liquid diet to pregnant rats (day 11 birth) resulted in a decrease in phosphatidylserine biosynthesis in the newborn and developing brain. The ethanol-induced decrease in phosphatidylserine biosynthetic activity could be reversed by adding chlorpromazine to the ethanol diet. Results demonstrate that phosphatidylserine biosynthesis in the neonatal brain is affected in opposite directions by chlorpromazine and ethanol. This poses the possibility that chlorpromazine administration may be effective in alleviating the deleterious effects caused by the decreased phosphatidylserine biosynthesis in brain due to in utero ethanol exposure.

Animals↗
PubMed1993

[Prolactin inhibits gonadotropin-induced increase in ovarian plasminogen activator activity and ovulation in mouse].

We have demonstrated in this study that prolactin inhibits hCG-induced ovulation in PMSG-primed mice. At 18 h after the hormone treatment the number of ova in the oviducts was found to be 31.7 +/- 6.7 (mean +/- SE) in hCG treated group. The number was significantly decreased (19.7 +/- 4.9) when 100 micrograms of prolactin was injected simultaneously. The same effect of PRL on hCG induced ovulation could be also observed at 24 h after the hormone treatment; the values reached respectively to 32.3 +/- 10.8 and 20.3 +/- 5.4. Both in vivo and in vitro experiments further showed that the inhibition of the gonadotropin-induced ovulation by PRL is mediated through decreasing in the ovarian plasminogen activator activity.

Animals↗
PubMed1993

The possible involvement of tissue type plasminogen activator in luteolysis of rhesus monkey.

Changes of plasminogen activators (PA) during different stages of development of the corpus luteum, and their possible physiological role in luteolysis were studied in rhesus monkeys. It was demonstrated for the first time that monkey corpus luteal cells not only produce PA, but that the function of the corpus luteum is also closely related to the activity of this enzyme system. Generally, the life span for a corpus luteum in monkey is approximately 14-16 days, its demise beginning thereafter. In the present study, we found that urokinase in the corpus luteum is higher on day 5 and day 10 after human chorionic gonadotrophin injection, while the tissue type (t) PA is mainly produced on day 13 when luteolysis may take place. Progesterone production remained high on day 5 and day 10 and decreased dramatically from day 13, indicating the important role of tPA but not urokinase (u) PA in suppressing luteal function. When purified tPA (but not uPA) monoclonal antibody was added to luteal cell culture to neutralize endogenously produced tPA activity, progesterone production in the cells was increased significantly. Interestingly, prolactin alone was capable of increasing PA production by luteal cells; prolactin together with luteinizing hormone, however, had a synergistic luteotrophic effect.

Animals↗
PubMed1993

[Synthesis of N-substituted polymethylene dicarboxamides as inducers of differentiation].

N-Alkyl polymethylene dicarboxamides are known potent inducers of erythroid differentiation in murine erythroleukemia cells. The most active inducer N,N,N',N'-tetramethyl-1, 6-hexane-dicarboxamide has the same effectiveness as HMBA which has entered clinical trials as a differentiating agent. These compounds also have inducing activity in HL-60 human promyelocytic leukemia cells. In this paper, the synthesis of a series of N,N'-bis[2-(2-thiazolinyl)], N,N'-bis[5-(1-methyl-2-pyridonyl)], N,N'-bis[3-(1-phenyl-5-pyrazolonyl)] polymethylene dicarboxamides and 3,3'-(polymethylene dicarbonyl)bis(1-methyl-2-imidazolidine-thiones) is reported. The inducing activities of the compounds were evaluated in vitro with HL-60 human promyelocytic leukemia cell line. Among them, N,N'-bis[2-(2-thiazolinyl)]-1,8-octamethylene- dicarboxamide (I4) and N,N'-bis[5-(1-methyl-2-pyridonyl)]-1,6-hexamethylenedicarboxami de (II3) were shown to be relatively effective inducers of differentiation.

Animals↗
PubMed1993

Hormonal regulation of tissue-type plasminogen activator and plasminogen activator inhibitor type-1 gene expression in cultured mouse Sertoli cells.

We have demonstrated for the first time that (i) mouse Sertoli cells predominantly secrete tPA under the action of FSH and cAMP-generating agents, whereas Leydig cells mainly produce uPA; (ii) Sertoli cells are also capable of secreting PAI-1, as well as FSH, growth factors and GnRH increase PAI-1 gene expression; (iii) the increases in tPA and PAI-1 activities by different hormones in the conditioned media of Sertoli cells correspond to the increases in the levels of tPA and PAI-1 mRNA in the cultured cells, suggesting that the synthesis of the activator-inhibitor in mouse Sertoli cells is regulated at a transcriptional level and the tPA secreted by Sertoli cells may be involved in the spermatogenesis.

Animals↗
PubMed1992

Interaction of berbamine compound E6 and calmodulin-dependent myosin light chain kinase.

The interaction of the berbamine compound E6 and calmodulin (CaM)-dependent myosin light chain kinase (MLCK) has been studied. The experimental results showed that the inhibition of MLCK activity was increased with increasing amounts of E6 and was overcome completely by the addition of excessive CaM. The stimulatory activity of MLCK induced by CaM was gradually inhibited by the increasing concentrations of compound E6, showing that the inhibition of MLCK activity by compound E6 was concentration dependent; and the Ki was 0.95 microM. Compound E6 diminished the fluorescence intensity of dansyl-labeled CaM and the intensity was increased gradually by the addition of different amounts of CaM. Compound E6 had no effect on the activity of MLCK fragments produced by limited trypsinization, and it is a novel and considerably potent calmodulin antagonist.

Alkaloids↗
PubMed1992

An experimental study of trachea anastomosis in rabbits using carbon dioxide laser.

A technique of sutureless trachea anastomosis in rabbits using carbon dioxide laser was reported herein. In 6 rabbits with laser-assisted trachea anastomoses, only one was found to have slight anastomotic stenosis after operation, whereas 6 rabbits with conventional sutures all were found to have anastomotic stenosis. Results show that laser-assisted trachea anastomosis has certain advantages over the conventional suturing technique, thereby finding wide application in clinical tracheal reconstruction and lung transplantation.

Anastomosis, Surgical↗
PubMed1992

In utero ethanol exposure decreases the biosynthesis of phosphatidylserine in rat pup cerebrum.

Phosphatidylserine is enriched in the brain and has been implicated to play a role in regulating neuronal membrane functions. In this study, three experimental protocols were used to examine the effects of in utero ethanol exposure on phosphatidylserine biosynthesis in rat pup brain, namely, (1) assay of the serine base-exchange enzyme activity in brain microsomes, (2) incubation of brain slices with [3H] serine, and (3) incorporation in vivo of [3H]serine into phosphatidylserine as well as serine-related phospholipids in brain. Results from all three protocols point to a decrease in phosphatidylserine biosynthesis in newborn rat pup cerebrum on exposure to ethanol in utero compared with the pair-fed controls. When in utero ethanol-exposed pups were nursed by mothers given a chow diet, the differences gradually returned to control levels by 17 days of age. The decrease in phosphatidylserine biosynthesis may be important in explaining some of the neuronal deficits associated with in utero ethanol exposure.

Animals↗
PubMed1992

[Analysis of the treatment with traditional Chinese medicine in chronic glomerulonephritis based on histopathologic type].

The histopathologic type of 189 cases of chronic glomerulonephritis (GN) were confirmed by renal biopsies, they were subdivided into 3 groups. 77 patients of Western medicine (WM) group was treated by conventional WM (prednison or CTX), and after treatment the total effective rate was 55.8%. The TCM-WM group was treated by the same WM plus treatment according to Syndrome Differentiation with Chinese medicinal herbs, and the total effective rate was 86% in 50 patients. The TCM group was treated by Chinese medicinal herbs, and the total effective rate was 67.3% in 62 cases. There was very significant difference (P < 0.01) between the WM and the TCM-WM group. Among the patients of TCM-WM and TCM groups, 67% of 112 cases were manifested as Dampness-Heat Syndrome, so it suggested that one of the important method for GN treatment is clearing away Dampness-Heat. The effects of TCM-WM group is much better than the WM group in treating mesangio-proliferative GN and membranous GN. It was difficult for WM in treating IgA nephropathy, membrano-proliferative GN and focal glomerulosclerosis, but Chinese medicinal herbs were effective with replenishing Qi and strengthening the Spleen, clearing away Dampness-Heat, promoting blood circulation and relieving Stasis, etc.

Adolescent↗
PubMed1991

Lysophosphatidylserine enhances the transfer of 22:6n3 to lysophosphatidic acid in rat brain microsomes.

Although the acyl groups of phosphatidylserine in brain are uniquely enriched in docosahexaenoic acid (22:6n3), the mechanism for this enrichment is not well understood. When rat brain homogenates and microsomes were incubated in the presence of lysophosphatidylserine (LPS) together with [14C]22:6n3 and cofactors for activation to its acylCoA, very little radioactivity was incorporated into phosphatidylserine (PS). On the other hand, [14C]20:4n6 was more actively incorporated into PS. Addition of LPS (1-10 uM), however, resulted in a 2-5 fold enhancement of the transfer of labeled 22:6n3 and 20:4n6 to phosphatidic acid (PA). Kinetic analysis indicated the ability of LPS to lower the Km and increase the Vmax of the lysophosphatidic acid (LPA) acyltransferase reaction. Among other lysophospholipids tested, lysophosphatidylserine was most effective in enhancing PA biosynthesis. Since PA is an important intermediate for de novo biosynthesis of phospholipids, these results reveal a novel mechanism for promoting synthesis of PA enriched in polyunsaturated fatty acids in brain.

Animals↗
PubMed1991

Neurosteroids: biosynthesis, metabolism and function of pregnenolone and dehydroepiandrosterone in the brain.

Pregnenolone (P) and dehydroepiandrosterone (D) accumulate in the brain as unconjugated steroids and their sulfate (S) and fatty acid (L) esters. The microsomal acyl-transferase activity is highest in immature (1-3 weeks old) male rats. The immunocytochemical and biochemical evidence for P biosynthesis by differentiated oligodendrocytes is reviewed. The importance of P synthesis for its brain accumulation is assessed by the intracysternal injection of the inhibitor aminoglutethimide. Primary glial cell cultures convert P to 20-OH-P, PL, progesterone, 5 alpha-pregnane-3,20-dione and 3 alpha-hydroxy-5 alpha-pregnane-20-one (Polone). Astroglial cell cultures also produce these metabolites, whereas neurons from 17-day mouse embryos only form 20-OH-P. P and D are converted to the corresponding 7 alpha-hydroxylated metabolites by a very active P-450 enzyme from rat brain microsomes. Several functions of neurosteroids are documented. P decreases in olfactory bulb of intact male rats exposed to the scent of estrous females. D inhibits the aggressive behavior of castrated male mice towards lactating female intruders. The D analog 3 beta-methyl-androst-5-en-17-one, which cannot be metabolized into sex steroids and is not demonstrably androgenic or estrogenic is at least as efficient as D. Both compounds elicit a marked decrease of PS in rat brain. The Cl- conductance of gamma-aminobutyric (GABAA) receptor is stimulated by GABA agonists, an effect which is enhanced by Polone and antagonized by PS. Thus, P metabolites in brain as well as steroids of extraencephalic sources may be involved physiologically in GABAA receptor function. The neurosteroids accumulated in brain may be precursors of sex steroid hormones and progesterone receptors have been localized in glial cells. P and D do not bind to any known intracellular receptor. A heat stable P binding protein has been found in brain cytosol with distinct ligand specificity. A binding component specific for steroids sulfates, including Polone S, DS and PS, in the order of decreasing affinity is localized in adult rat brain synaptosomal membranes. Its relationship to the GABAA receptor is under current investigation.

Animals↗