Biomedical subjects

H Yin

Publications and source records attributed to H Yin.

At least 109 records · Page 6Linked to original sources

PubMed1998

Trichlorfon exposure, spindle aberrations and nondisjunction in mammalian oocytes.

Consumption of trichlorfon-poisoned fish by women in a small Hungarian village has been associated with trisomy resulting from an error of meiosis II in oogenesis. We therefore examined mouse oocytes exposed for 3 h during fertilization to 50 microg/ml trichlorfon. Spindle morphology was not visibly altered by the pesticide. Chromosomes segregated normally at anaphase II with no induction of aneuploidy. However, formation of a spindle was disturbed in many oocytes resuming meiosis I in the presence of trichlorfon. In spite of the spindle aberrations and the failure of bivalents to align properly at the equator, oocytes did not become meiotically arrested but progressed to metaphase II. At this stage, spindles were highly abnormal, and chromosomes were often totally unaligned, unattached or dispersed on the elongated and disorganized spindle. By causing spindle aberrations and influencing chromosome congression, trichlorfon appears, therefore, to predispose mammalian oocytes to random chromosome segregation, especially when they undergo a first division and develop to metaphase II during exposure. This is the first case in which environmentally induced human trisomy can be correlated with spindle aberrations induced by chemical exposure. Our observations suggest that oocytes may not possess a checkpoint sensing displacement of chromosomes from the equator at meiosis I and may therefore be prone to nondisjunction.

Anaphase↗

PubMed1998

Women of reproductive age with endometriosis are not osteopenic.

OBJECTIVE: To determine whether women of reproductive age with endometriosis are osteopenic and whether bone density decreases with higher stages of endometriosis. DESIGN: A multicenter cross-sectional study was performed. SETTING: Thirty-nine gynecological clinics in the United States, Canada, and Puerto Rico. PATIENT(S): Two hundred forty-one women of reproductive age with laparoscopically proved endometriosis. INTERVENTION(S): Diagnostic laparoscopy, bone densitometry. MAIN OUTCOME MEASURE(S): Endometriosis stages according to the criteria of the American Society for Reproductive Medicine, lumbar spine bone mineral density (L2-L4) as measured by dual-energy x-ray absorptiometry. RESULT(S): The mean lumbar spine bone mineral density, as well as the distribution of bone mineral density, of the women with endometriosis was similar to that of a normal population. There were no significant differences between endometriosis stage groups I-IV regarding bone mineral density as well as body weight, body mass index, and height. CONCLUSION(S): Women of reproductive age with endometriosis are not osteopenic. More advanced stages of endometriosis are not associated with a decrease in lumbar spine bone mineral density.

Adolescent↗

PubMed1998

Goserelin acetate (Zoladex) with or without hormone replacement therapy for the treatment of endometriosis.

OBJECTIVE: To determine whether hormone replacement therapy (HRT) plus goserelin (Zoladex) is as effective as goserelin alone for the relief of pelvic symptoms of endometriosis and to determine whether it reduces both the loss of bone mineral density (BMD) and the physiologic side effects associated with goserelin therapy. DESIGN: Prospective, placebo-controlled study, open label for goserelin therapy and double-blind for HRT. SETTING: Forty-two teaching or community hospitals. PATIENT(S): Premenopausal women with symptomatic endometriosis. RESULT(S): Statistically significant mean decreases from baseline in the total pelvic symptom score and total subjective score were observed by week 24 for all three groups. There were no statistically significant treatment differences for change in total symptom score. Some degree of BMD loss occurred in the three groups; however, the percentage loss was consistently greater in the HRT0 group than in the HRT1 or HRT2 groups. When analyzed separately, no overall age effect on BMD change was seen in women >30 years of age versus women < or = 30 years. The HRT1 and HRT2 groups had fewer occurrences of hot flushes and vaginal dryness than did the HRT0 group. CONCLUSION(S): Goserelin plus HRT is as effective as goserelin alone in relieving pelvic symptoms of endometriosis and attenuates both the loss of BMD and the physiologic side effects of hot flushes and vaginal dryness associated with goserelin therapy.

Adolescent↗

PubMed1998

Expression of the messenger RNA for gonadotropin-releasing hormone and its receptor in human cancer cell lines.

The presence of gonadotropin-releasing hormone (GnRH) binding sites in biopsy samples of human epithelial ovarian cancer and ovarian tumor cell lines as well as the demonstration of the inhibitory effects of GnRH analogues on the growth of these cells raised the possibility that GnRH is produced locally by ovarian cancer cells. In order to investigate an autocrine/paracrine regulatory mechanism in human carcinomas, we have studied the expression of GnRH and GnRHR mRNA in human ovarian epithelial cell lines (OVCAR-3 and SKOV-3), human choriocarcinoma cell line (JEG-3) and human hepatocarcinoma cell line (HepG 2). Using primers corresponding to published human GnRH and GnRHR cDNA sequences, predicted PCR products were obtained from these cell lines by reverse transcription-polymerase chain reaction (RT-PCR) and confirmed by Southern hybridization. Sequencing analysis of GnRH PCR products showed that their sequences have 100% identity to the published human GnRH cDNA sequence. These results indicated that GnRH and GnRHR genes are expressed in all the cell lines tested in the present study, and strengthen the concept that GnRH may act as an autocrine regulator on the growth of cancer cells.

Blotting, Southern↗

PubMed1998

Temporal coding in Pavlovian conditioning: Hall-Pearce negative transfer.

The Hall-Pearce (1979) negative transfer effect in rats was used to examine whether temporal relationships are coded as part of the informational content of associations that results from CS-US pairings. The transfer effect consists of a deficit in conditioned responding following CS-USstrong pairings in Phase 2 that results from prior CS-USweak pairings in Phase 1. Using conditioned bar-press suppression, we found that gaps of different duration between CS termination and US onset in the two training phases resulted in less of a Hall-Pearce negative transfer effect than did an equivalent gap in the two training phases. The results are discussed with respect to the temporal coding hypothesis (Matzel, Held, & Miller, 1988), the Pearce and Hall (1980) model, and Bouton's (1993) interference model.

Animals↗

PubMed1998

Diazepam induces meiotic delay, aneuploidy and predivision of homologues and chromatids in mammalian oocytes.

The tranquilizer and anti-convulsant diazepam (DZ) is a suspected aneugen. In order to assess its aneugenic potential in mammalian oogenesis we exposed in vitro maturing mouse oocytes to the drug. Spindle formation and cell cycle progression, the behaviour of chromosomes and the distribution of mitochondria were characterized with respect to induction of numerical chromosomal aberrations. A concentration of 25 microg/ml DZ induced a pronounced delay in maturation and blocked a high percentage of oocytes in meiosis I. This arrest was partly reversible. Hyperploidy was slightly increased in oocytes matured in the presence of 5 microg/ml DZ and became significantly elevated in oocytes matured with 25 microg/ml DZ, relative to controls. Concomitantly, DZ induced spindle aberrations and displacement of chromosomes from the equator, but unlike in mitosis and in male meiosis most oocytes still possessed bipolar spindles. A significant fraction of meiotically delayed, metaphase I-blocked oocytes exposed to 25 microg/ml DZ contained univalents. Some DZ-treated oocytes progressing to meiosis II exhibited one or multiple single chromatids. Precocious chiasma resolution and equational segregation of chromatids from functional univalents in first anaphase (predivision) may be responsible for this condition, a mechanism also discussed in the aetiology of maternal age-related aneuploidy. DZ disturbed the spatio-temporal distribution of mitochondria during oocyte maturation, possibly by binding to peripheral-type benzodiazepine receptors on mitochondria, thus affecting the availability of ATP and calcium homeostasis. Blocks in maturation may also relate to binding of DZ to calmodulin. Data suggest that DZ exposes mammalian oocytes to predivision and aneuploidy. Thresholds, long lasting effects of DZ in vivo and sex-specific sensitivities in chemically induced aneuploidy of mammalian germ cells are critically evaluated.

Aneuploidy↗

PubMed1998

Chemoprevention of N-nitroso-N-methylurea-induced rat mammary carcinogenesis by soy foods or biochanin A.

We examined the effects of soybeans, a soy product (miso) and biochanin A, an isoflavone derivative, on N-nitroso-N-methylurea (MNU)-induced rat mammary carcinogenesis. Seven-week-old female CD/Crj rats received a single i.v. dose (40 mg/kg body weight) of MNU. After administration of MNU, rats were fed diet containing 0% (control), 2% or 10% soybeans, or 10% miso as a soy-supplemented diet, or 10 or 50 mg/kg biochanin A. All rats were observed for 18 weeks after MNU administration. At 18 weeks, the multiplicity (mean tumors/rat) of palpable mammary tumors was significantly decreased in the 10% soybean (1.1) and 10% miso (1.2) diet groups compared to the control (2.2) (P<0.05, respectively). In the biochanin A-supplemented diet groups, the incidence (percentage of rats with tumors) was significantly decreased in the 50 mg/kg (32%) diet group compared to the control (80%) (P<0.01), and the multiplicity was significantly decreased in both the 10 mg/kg (0.7) and 50 mg/kg (0.5) diet groups compared to the control (2.2) (P<0.01 and P<0.001, respectively). The proliferative cell nuclear antigen labeling index of mammary tumors was significantly decreased in both biochanin A-supplemented diet groups compared to the control. The present results indicate that soybeans, miso, and biochanin A are useful for the prevention of mammary cancer.

Animals↗

PubMed1998

Chemoprevention of N-nitroso-N-methylurea-induced rat mammary cancer by miso and tamoxifen, alone and in combination.

We examined the effects of a Japanese fermented soybean product, miso, and tamoxifen (TAM), alone and in combination, on N-nitroso-N-methylurea (MNU)-induced rat mammary cancer. Seven-week-old female CD/Crj rats received a single i.v. dose (50 mg/kg body weight) of MNU. After administration of MNU, the rats were divided into 4 groups: regular diet (control), 10% miso diet, regular diet + TAM, and 10% miso diet + TAM. TAM was implanted s.c. in the form of pellets containing 2.5 mg at the same time as MNU was administered. All rats were observed for 18 weeks after MNU administration. Incidence (percentage of rats with tumors) and multiplicity (mean tumors/rat) of mammary tumors were 91% and 4.5 in the control, 77% and 2.4 (P < 0.05) in the 10% miso group, 68% and 1.4 (P <0.01) in the TAM group, and 10% (P < 0.0001 or less) and 0.2 (P < 0.0001) in the 10% miso + TAM group. In the second experiment, the effect of the combination of miso and TAM on established rat mammary tumors was investigated. When the mammary tumors induced by MNU reached 10 to 25 mm, the rats were divided into 3 treatment groups: regular diet, regular diet + TAM, and 10% miso diet + TAM. At 6 weeks after the start of treatment, the mean tumor size in the control and TAM groups was 160% and 141% of the pretreatment value, but a decrease of 85% of the pretreatment value was produced by the combination of miso and TAM, and this was significantly different from both the control and TAM groups (P < 0.01) and P < 0.05, respectively). These results indicate that miso is useful in protecting against mammary cancer and it can be expected to have a potent antitumor effect, especially when used in combination with TAM.

Animals↗

PubMed1998

Analysis of immunodominant piroplasm surface protein genes of benign Theileria parasites distributed in China and Korea by allele-specific polymerase chain reaction.

Benign Theileria species distributed in China and Korea were characterized by allele-specific polymerase chain reaction (PCR), based on the sequences of major immunodominant piroplasm surface protein genes. In China, all the isolates contained Chitose (C) type parasites. One out of 5 isolates tested was a mixed population of Ikeda (I), C and B-2 types, whereas, all the isolates from Korea consisted of I type parasites. Except for 4 isolates, 29 isolates from Korea consisted of more than two types of parasites. The present data showed that benign Theileria species distributed in these countries were mixed parasite populations.

Alleles↗

PubMed1998

[Inhibition effect of Swainsonine on the growth and metastasis of gastric cancer in vivo].

OBJECTIVE: To study the immunomodulating effect of Swainsonine (SW), an inhibitor of alpha-mannosidase II, and the inhibiting effect on the growth and metastasis of gastric cancer. METHODS: Nude mice with human gastric cancer xenograft orthotopically implanted into the gastric wall were fed with drinking water containing 3 mg/L SW for two days alternating with that containing no SW for two days until sacrificed eight weeks after tumor implantation. RESULTS: The mean tumor volume in the SW-treated group was significantly smaller than that of the control group (0.42 +/- 0.26 cm3 vs 1.60 +/- 0.36 cm3). Calculated by volume, the tumor growth was inhibited by 73.8%. Metastasis to the liver was observed in 20% and 80% of the SW-treated and control mice, while metastasis to the peritoneum was seen in 30% and 90% of SW-treated and control mice, respectively. The total number of splenic cells, and the NK cell activity both of PBL and splenic cells were all elevated. CONCLUSION: SW is effective in inhibiting tumor growth and metastasis of human gastric cancer in nude mice. Enhanced immune response, among other things, may be involved in the anti-tumor effect.

Adenocarcinoma↗

PubMed1998

[Experimental study of the effect of angiogenesis inhibitor TNP-470 on the growth and metastasis of gastric cancer in vivo].

OBJECTIVE: To study the effect of angiogenesis inhibitor TNP-470 on the growth and metastasis of gastric cancer in vivo. METHODS: Metastatic model simulating human gastric cancer was established by orthotopic implantation of histologically intact human tumor tissue into gastric wall of nude mice. TNP-470 was administered s.c. at doses of 0 mg/kg, 15 mg/kg, 30 mg/kg, 60 mg/kg every other day for eight weeks. Ten weeks after implantation, the mice were sacrificed and the tumor size measured and the presence of metastasis recorded. The microvascular density was examined by immunohistochemical staining with anti-human factor VIII antibody. RESULTS: Compared to the untreated controls, growth of the orthotopically implanted tumor was significantly reduced in size in mice treated with TNP-470 with an inhibition rate of 59.9%, 77. 0% and 84.9% at the dosage of 15 mg/kg, 30 mg/kg and 60 mg/kg, respectively. Tumor metastasis to the liver and peritoneaum was also significantly inhibited in a dose-dependent manner. The microvascular density was also decreased significantly in the treated mice. CONCLUSION: Angiogenesis inhibitor TNP-470 has strong inhibitory effect both on tumor growth and metastasis of human gastric cancer in nude mice.

Animals↗

PubMed1998

[Detection of TCR gamma gene in acute lymphoblastic leukemia after remission and its clinical significance].

OBJECTIVES: To investigate the quantitative evaluation of chemotherapy efficiency in patients with acute leukemia and its clinical significance. METHODS: Clonal rearrangement of T-cell receptor gamma gene in ALL was detected quantitatively by using competitive PCR. RESULTS: One handred and fifty-eight samples were collected from 54 childhood ALL. The median follow-up duration was 33.5 months. At remission, the amount of leukemic cells in 36 cases was less than 1 x 10(-5), and in 18, was (354 +/- 327) x 10(-5). The efficiency of induction therapy was related significantly to the amount of the detectable residual leukemic cells in the early remission phase and to clinical relapse. In some patients in remission, the amount of leukemic cells persistently under 1 x 10(-5) without clinical relapse. CONCLUSION: Quantitative evaluation of the chemotherapy efficiency is helpful for individualized treatment.

Child↗

PubMed1998

[Placental site trophoblastic tumor: a study of clinicopathologic features and differential diagnosis].

OBJECTIVE: To study the clinicopathologic features and differential diagnosis of placental site trophoblastic tumor (PSTT). METHODS: 5 PSTT cases were studied and compared with 10 choriocarcinoma cases and 2 exaggerated placental site (EPS) cases by light and electron microscope examination and immunohistochemical staining. RESULTS: PSTT occurs in reproductive women and often following term deliveries. Amenorrhea and or vaginal bleeding are common presenting symptoms. The serum levels of hCG are often slightly or moderately elevated. Microscopically, PSTT is composed of only one kind of trophoblast cell, displaying extensive invasion of myometrium and vessels without obvious hemorrhage and necrosis. Mitotic figures are not common. Ultrastructure shows that the tumor cells contain prominent paranuclear filaments. Immunohistochemical reaction reveals positive staining for hPL and mostly negative staining for hCG. CONCLUSION: PSTT is a rare trophoblastic tumor with unique microscopic, ultrastructural and immunohistochemical features which can help to differentiate them from other trophoblastic diseases.

Choriocarcinoma↗

PubMed1998

[Distribution of B-lymphocyte subgroup CD20 and its clinical significance in patients with myasthenia gravis].

OBJECTIVE: To assess the distribution and clinical significance of B-lymphocyte subgroup CD20 in patients with myasthenia gravis. METHOD: B-lymphocyte subset CD20 was studied in patients with thymomas associated with or without myasthenia gravis using immunohistochemistry technique. RESULT: The moderate and obvious aggregation of CD20 positive cells was found in patients with myasthenia gravis, there was a significant difference when compared with those patients without myasthenia gravis (chi(2) = 26.032, P < 0.01). There was negative correlation between the distribution of CD20 positive cells and the staging of thymomas (gamma = 0.07), and no correlation between the distribution and clinical type of myasthenia gravis (gamma < 0.4). CONCLUSION: The results of this study indicated that pathological changes of thymus are more important than those of thymomas itself in the pathogenesis of myasthenia gravis. The degree of B-lymphocyte subgroup aggregation can not truly reflect clinical status because of the heterogeneity of antibody against acetylcholine receptor.

Adult↗

PubMed1998

[Prognostic value of tumor vascularity in gastric carcinoma].

OBJECTIVE: To determine whether tumor angiogenesis correlates with progression of gastric carcinoma. METHOD: Microvessel counts (MVC) of 131 specimens resected from patients with gastric carcinoma were investigated by immunohistological staining with a monoclonal antibody against F-VIII RAg, counting the mean number of microvessels in the five areas of highest vascular density under 200 times magnification microscopy. Correlation among MVC, various clinicopathologic factors, and prognosis was studied. RESULT: MVC increased with TNM stage, the MVC of patients with advanced stage disease was significantly higher than that of early stage patients (P < 0.01). MVC was significantly higher in tumors with deep penetration (P < 0.05), lymph node metastasis (P < 0.001) and distant metastasis (P < 0.05) than in those without invasion and such metastasis. The recurrence rate after curative resection in hypervascular group (MVC > or 16) was 58.4%, which was significantly higher (P < 0.05) than that in the hypovascular group (MVC < 16). Moreover, the prognosis of patients with a high MVC was significantly poorer than that of those with a low MVC. The probability of 5 year survival rate was estimated by P = e(1.6231-0.1036 x MVC)/1 + e(1.6231-0.1036 x MVC). Multivariate analysis indicated that MVC is an independent prognostic factor in gastric cancer. CONCLUSION: Angiogenesis within gastric cancer is an indicator of tumor behavior and may identify patients at higher risk for recurrence and poorer prognosis.

Adult↗

PubMed1998

[Study on the contents of HBV DNA in sera of patients with hepatic diseases by QPCR technique].

In order to test the content of serum HBV DNA for evaluating the effectiveness of clinical antiviral treatment and the relation of serum HBV DNA level to state of illness and prognosis, a QPCR method of energy transfer in amplification by semi-nested fluorescein labeled primer was established. Serum HBV DNA contents of 63 cases of hepatic diseases with abnormal liver function were detected by QPCR, PCR and ELISA. The positive detectable rate of the three methods were compared. The results showed that the positive detectable rate of QPCR was 82.54%, PCR 71.43% and ELISA 63.50%. The detectable rate of QPCR was compared with PCR, and uniformity rate of the both methods was 88.89%, P < 0.05; the positive results of QPCR were compared with ELISA, and their uniformity rate was 80.95%, P < 0.05; when serum average content (mean +/- s) of HBV DNA by QPCR method was compared with serum average titer of HBV by ELISA method, serum HBV-DNA average content of the group in which both QPCR and ELISA were positive was much higher than that of the group of QPCR(+) and ELISA(-), P < 0.05; serum QPCR-HBV-DNA of 30 cases of healthy persons were all negative. The results indicated that QPCR method is of highest positive detectable rate and more specific in detecting serum HBV DNA and had no nonspecific amplifying reaction. It has the superiority of detecting low level serum HBV DNA.

Adult↗

PubMed1997

Transcription of human endogenous retroviral sequences related to mouse mammary tumor virus in human breast and placenta: similar pattern in most malignant and nonmalignant breast tissues.

The human genome contains a large variety of sequences related to the mouse mammary tumor virus (MMTV). We have investigated the range of expression of human endogenous retroviral sequences (HERVs) related to MMTV (human MMTV-like; HML) as RNA in 60 breast cancers, 8 nonmalignant breast tissues, and 9 placentas. This was monitored using HML group-specific oligonucleotide probes in hybridizations toward PCR amplificates of HML pol sequences and internal control. The degree of expression of five HML groups varied between individuals and between tissues. On average, all HML groups were less expressed in breast tissues than in placenta. The hybridization signals of some HML RNAs were strongly correlated, indicating a nonstochastic mechanism and a concerted regulation of their expression. The PCR product from one breast cancer (BC 6), which gave an exceptionally high expression with probe hml-6, with a 20 times stronger signal than the rest of the cancers, was cloned and sequenced. The HML-6 transcript sequences were homogeneous in BC 6. The most predominant clone derived from the cancer was used as a probe in Southern hybridizations. The same restriction fragments were detected in human breast tissues, PBMCs (peripheral blood mononuclear cells), and breast cancer cell lines, except for one of the breast cancers and one of the nonmalignant breast tissues, which gave different banding patterns. A comparison of HML expression in normal and malignant breast tissue from the same individual would have been more precise than our comparison of samples from different persons. Bearing this limitation in mind, with a single exception, human MMTV-like sequences were not more actively expressed in malignant than in nonmalignant breast tissues. Nevertheless, an interesting diversity in their expression, especially between individuals, was found.

Adult↗

PubMed1997

Cytochrome P450 2C11: Escherichia coli expression, purification, functional characterization, and mechanism-based inactivation of the enzyme.

The male-specific P450 enzyme CYP 2C11, whose expression is developmentally and hormonally regulated, is the major steroid 16alpha-hydroxylase of the untreated rat liver. The enzyme metabolizes a host of substrates, including mechanism-based inactivators, such as 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine (DDEP) and spironolactone (SPL). Structural and functional characterization of the specific mode of such inactivation, however, requires sufficient quantities of the fully purified enzyme. Although several laboratories including our own have isolated and purified the enzyme from male rats, the yields are typically low and of the order of 1%. For these reasons, we chose to heterologously express the enzyme in Escherichia coli. The full-length cDNA was excised from the yeast vector pD2M1 and cloned into the plasmid vector pCW after appropriate modifications for optimal expression in E. coli. The enzyme was isolated and purified from E. coli membranes in relatively high yields (approximately 60%) and relatively high specific content (19 nmol/mg protein). The purified recombinant enzyme had spectral and functional characteristics comparable to those reported for the native rat liver enzyme, including mechanism-based inactivation by DDEP and SPL. Studies with 14C-heme-labeled enzyme indicated that the major mode of DDEP inactivation was via heme-N-ethylation. On the other hand, studies with radiolabeled SPL-SH (the proximal inactivating deacetylated metabolite of SPL) revealed that although both [22-14C]SPL-SH and SPL-35SH inactivated the enzyme, only SPL-35SH was found to irreversibly radiolabel the 2C11 protein. The latter findings thus suggest that during mechanism-based inactivation of 2C11, the thiol moiety of SPL-SH is oxidatively activated to a species that attacks the 2C11 protein during or after cleavage from the thiosteroid. Thus, these modes of mechanism-based 2C11 inactivation by DDEP and SPL-SH considerably differ from the corresponding modes of P450 3A inactivation by these agents, wherein heme modification of the protein predominates.

Amino Acid Sequence↗