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Biomedical subjects

S Xiao

Publications and source records attributed to S Xiao.

At least 163 records · Page 9Linked to original sources
PubMed1992

Interaction between activin and follicle-stimulating hormone-suppressing protein/follistatin in the regulation of basal inhibin production by cultured rat granulosa cells.

There is evidence that FSH-suppressing protein (FSP) antagonizes the action of activin on the differentiation of rat granulosa cells by binding activin in vitro. We tested the interaction of activin and FSP in this in vitro system by examining the effects of FSP on activin dose-related stimulation of immunoreactive inhibin release by rat granulosa cells. Granulosa cells (2 x 10(5) viable cells/well) from diethylstilbestrol-treated immature rats were cultured for 48 h in McCoy's 5a serum-free medium with additives and increasing doses of bovine FSP (0-30 nM) and human recombinant activin (0-20 nM). Inhibin was measured in the medium by RIA. Activin caused a dose-related increase in basal inhibin production, which was maximal between 4-10 nM activin (ED50, 0.6 nM). With the addition of FSP, an apparent increase in the ED50 of the activin dose-response curves was observed, but there were no changes in the maximum response. This pattern closely resembled that of chemical antagonism of an agonist by an agent that binds with relatively high affinity to form a biologically inactive complex. Based on this premise, apparent high affinity activin binding to FSP was determined by Scatchard analysis to have a Kd of 0.13 +/- 0.07 nM (mean +/- SD) and to occur in a 2:1 or greater FSP/activin molar ratio. These data support the proposition that the antagonistic effect of FSP on activin is due to the formation of an inactive complex.

Activins↗
PubMed1992

Modulation of differentiation of rat granulosa cells in vitro by interferon-gamma.

The effects of recombinant rat interferon-gamma (rRaIFN-gamma) and rat IFN (RaIFN, a mixture of IFN-gamma and -alpha) on basal and FSH-induced ovarian granulosa cell function were studied. Granulosa cells were harvested from diethylstilboestrol-treated immature rats and cultured (2 x 10(5) viable cells/well per 0.5 ml) in serum-free medium with or without treatment for 48 h. In the presence of FSH (20 ng/ml), rRaIFN-gamma (10-1000 U/ml) significantly inhibited FSH-stimulated aromatase activity (76.4 +/- 2.3% maximum inhibition compared with FSH treatment alone), inhibin (40.4 +/- 3.7%), progesterone (47.7 +/- 8.6%) and 20 alpha-hydroxypregn-4-en-3-one (20 alpha-OHP) (51.8 +/- 1.7%) production in a dose-dependent manner. Furthermore, rRaIFN-gamma inhibited FSH- and forskolin (FSK; 30 mumol/l)-induced extracellular cAMP accumulation (46.0 +/- 6.6% and 29.1 +/- 7.3% respectively). The inhibitory effect of rRaIFN-gamma on FSK-induced cAMP was accompanied by decreased FSK-induced aromatase activity, inhibin, progesterone and 20 alpha-OHP production. rRaIFN-gamma had no detectable effect on aromatase activity, progesterone production and 20 alpha-OHP production in the absence of FSH, but significantly stimulated basal inhibin production by 1.5-fold. rRaIFN-gamma alone also caused a small but significant increase in basal levels of cAMP. The time-course studies showed that FSH-induced aromatase activity and inhibin production were consistently suppressed by rRaIFN-gamma, FSH-induced progesterone and 20 alpha-OHP were inhibited at 1 and 2 days and then stimulated on days 3, 4 and 5 relative to FSH alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Cytogenetic studies of five primary esophageal cancers.

In direct preparation of five primary esophageal cancers, chromosomes 1, 3, and 12 were most frequently involved in structural abnormalities; 12p- was consistently seen in all five cases and, thus, could be considered as one of the characteristic chromosome changes in esophageal cancer. Moreover, 2p-, 4p-, and 7q- were seen in three cases.

China↗
PubMed1991

Interactions between activin and follicle-stimulating hormone-suppressing protein and their mechanisms of action on cultured rat granulosa cells.

Direct roles of follicle-stimulating hormone (FSH)-suppressing protein (FSP) and activin in regulation of ovarian granulosa cell differentiation have been reported recently. The present study further investigated the effects of these peptides on steroidogenesis and inhibin production as well as cAMP generation in cultured granulosa cells from immature, diethylstilbestrol (DES)-treated rats. In the presence of FSH (20 ng/ml) and activin (30 ng/ml), which enhanced FSH-induced aromatase activity, progesterone production and inhibin production, FSP (1-100 ng/ml) reversed the stimulating activities of activin in a dose-dependent manner. In addition, activin reversed the inhibitory effects of FSP on FSH-induced aromatase activity and inhibin production. In the presence of FSH, activin enhanced FSH-stimulated extracellular cAMP accumulation, and FSP caused a reduction in extracellular cAMP. Activin but not FSP also stimulated basal cAMP level. In the presence of forskolin, a potent stimulant of adenyl cyclase activity which stimulated extracellular cAMP, aromatase activity, progesterone production and inhibin production, activin augmented the effect of forskolin on all four parameters, whereas FSP significantly enhanced progesterone production without changing the other three parameters. Our findings suggest that activin action on rat granulosa cells may be mediated via regulation of cAMP generation. The action of FSP and FSH and/or activin-dependent, consistent with either an action as an activin binding protein or by a direct action of FSP on the granulosa cells.

Activins↗
PubMed1991

[Psychologic correlates in peptic ulcer].

Psychological correlates of peptic ulcer were assessed in a group of volunteer patients whose ulcers were identified by endoscopy. Logistic regression analysis and "t" test indicates that the peptic ulcer patients studied had higher "neuroticism" scores on EPQ, more life events experienced in the year previous to the investigation (on the revised Holmes' Social Readjustment Rating Scale), more severe symptoms on SCL-90, and lower social support scores on the Social Support Rating Scale than matched controls. The most frequently reported SCL-90 symptoms were anxiety, depression, somatization and obsession. The relationship between the occurrence of peptic ulcer and the characteristics of personality, life events, social support and psychological health level is discussed.

Adolescent↗
PubMed1991

[Methanogens from feces of patients with intestine disorder].

Fecal specimens from 10 colorectal cancer, 1 duodenum diverticulosis and 2 healthy adults were examined. Nine fecal enrichments contained Methanobrevibacter. The percentage of methanogen positive individuals was 69% Methanobrevibacter were isolated from fecal enrichments of 4 colorectal cancer and 1 duodenum diverticulosis. The percentage of breath methane positive individuals and methane production had significantly increased in colorectal cancer patients. It will be hopeful that methane production in breath samples at the end of exhalation will became a rapid, simple and non-penetrative method for monitoring precancerous colonic or rectal carcinogenesis and monitoring the relapse of individuals with carcinosectomy.

Breath Tests↗
PubMed1991

Histological classification of schistosomal egg induced polyps of colon and their clinical significance. An analysis of 272 cases.

272 cases of schistosomal egg induced polyps collected from mass-screening for colorectal carcinoma in Jiashan County were divided into 3 types: fibrous type (FT), mixed type (MT) and epithelial proliferative type (ET). The ET was characterized by crypt elongation, hypertrophy, variation in size, disorderly arrangement, as well as the high percentage of atypical hyperplasia (64.9%). The coexistence and transition between inflammatory reactive hyperplastic and neoplastic crypts were noticed. By HID/AB staining, sialomucins were increased in ET, CEA and PNA receptors detected by the ABC method were present in 18/20 and 6/18 of ET respectively. The mucin expression of ET was similar to that of adenomas. It is likely that a spectrum of ET, atypical hyperplasia and adenoma may exist. We suggest that the patients with ET, especially those with atypical hyperplasia, should be regarded as "risk group", and close follow-up is needed.

Adenoma↗
PubMed1990

The effect of bovine activin and follicle-stimulating hormone (FSH) suppressing protein/follistatin on FSH-induced differentiation of rat granulosa cells in vitro.

The time- and dose-dependent effects of bovine activin A and bovine follicle stimulating hormone (FSH) suppressing protein (FSP) or follistatin on basal and FSH-induced steroidogenesis and inhibin production were studied in granulosa cells from immature, diethylstilbestrol (DES)-treated rats. In the presence of rat FSH (20 ng/ml) which stimulates aromatase activity and the production of progesterone and inhibin, activin (0.3-100 ng/ml) augmented all three parameters, whereas FSP (0.3-100 ng/ml) enhanced progesterone production and attenuated the other two parameters. In the absence of FSH, the basal parameters were unaffected by treatment with either activin or FSP alone, except for a statistically significant increase in basal inhibin in the presence of activin alone (P less than 0.05, at doses of 30 and 100 ng/ml). Neither activin nor FSP influenced the timing of the maxima of FSH-induced activities over 5 days. These findings suggest that activin and FSP, both present in follicular fluid, may play an important role in the local regulation of granulosa cell differentiation.

Activins↗
PubMed1990

[Demonstration of the presence of Methanobrevibacter in a colon cancer Chinese patient].

A fecal specimen from a Chinese patient (85-year-old man) suffering from colonic cancer was examined for the presence of methane-producing bacteria. As a result, a Methanobrevibacter organism was isolated. Our isolate did not grow in the presence of bile salts, a result different from Methanobrevibacter from healthy Americans' feces by Miller et al.

Aged↗
PubMed1990

[An observation of the anticancer activity of mitoxantrone hydrochloride injection].

Experimental results of anticancer activity of DHAQ.HCl are reported in this paper. It was discovered that DHAQ.HCl, mitoxantrone hydrochloride, had an obvious anticancer effect on the experimental tumor strains:Ehrlich ascites cancer, Sarcoma-180, Leukemia P388, etc., and that it was more effective to Leukemia P388 than to other strains. The anticancer activity of DHAQ.HCl was better than DHAQ (P less than 0.05). No side effect was observed on the local sites (s.c.) of tumor planted or drug injected. And also a good anticancer effect was observed on the sites of tumor planted by local injection. It is suggested that this observation can provide some information on the choice of routes of administration of this drug clinically.

Animals↗
PubMed1989

An improved method of direct chromosome preparation from chorionic villus and high resolution banding technique.

The trophoblast was dissociated from the underlying mesenchymal layer either with acetic acid after short-term prefixation or with mechanical power after fixation twice. The colcemid treatment time was shorted to 16 min and trypsin solution of low pH (6.2) was used for banding. By these steps, the quality of chromosome banding was greatly improved and complete standard chromosome diagnoses were made in 24 of 24 cases. With the modified technique, high resolution banding chromosomes were consistently obtained after short-term incubation.

Acetates↗
PubMed1989

[Changes of hormone levels in follicular fluid in women with normal menstruation].

Levels of estradiol (E2), progesterone (P0), androstenedione (A), testosterone (T), follicle stimulating hormone (FSH), luteinizing hormone (LH) and prolactin (PRL) in ovarian follicles of different sizes and at different phases of normal menstrual cycles were determined and, their relationships with those in peripheral blood were studied. According to the diameters, the follicles were divided into large (greater than 14 mm), median (8-14 mm) and small (less than 8 mm) ones. The results showed that the levels of E2, P0, FSH and LH were lower, whereas those of A and T were higher in small and median follicles, as compared with the large follicles. In the large follicles, particularly at the preovulatory phase, E2, P0, FSH and LH reached maximum levels. The concentration of E2 was 9815 nmol/L, P0, 3316 nmol/L, FSH 1.34 IU/L and LH 3.91 IU/L at the preovulatory phase. The concentrations of A and T were much lower in large follicles, being 280 nmol/L and 137 nmol/L respectively. No significant difference was found in PRL levels in follicles of different sizes. The steroid hormones in the follicular fluid were about 7-20,000 times higher than those in the peripheral blood, while FSH and LH were only about 10-80% and PRL was slightly higher than in peripheral blood.

Adult↗
PubMedDate not supplied

Hypothesis: A recurrent, moderate activation fosters systemic autoimmunity--the apoptotic roles of TCR, IL-2 and Fas ligand.

Studies of several gene knockout mice suggest an interesting association of a moderate T cell response with systemic autoimmune diseases. In addition, CD95 ligand (FasL) expression in some strains of these mice is impaired. Because FasL is critically involved in regulating peripheral tolerance, there may be a link between autoimmune diseases and a moderate T cell response that cannot activate the FasL gene. Here, we propose that there are two thresholds of T cell activation. When moderately stimulated, T cells can be activated to the low (1st) threshold, which permits the induction of CD40L, IL-2, IL-4, and other components that help the immune response. The high (2nd) activation threshold can only be achieved by a strong and concurrent stimulation through TCR and IL-2R. Once the high threshold is reached, FasL is produced to induce apoptosis of the activated T and B cells. In the absence of the FasL-mediated downregulation, the activated B cells become efficient antigen-presenting cells for self-antigens and excellent responders for T cell help. Such an exacerbating condition, induced by recurrent and moderate activation, favors the development of autoreactive T cells and autoantibody production. Evidence supporting this hypothesis and some predictions that can be tested are described.

Animals↗