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Biomedical subjects

Y Zhao

Publications and source records attributed to Y Zhao.

At least 901 records · Page 50Linked to original sources
PubMed1995

Characterization of the sequences of the human CYP19 (aromatase) gene that mediate regulation by glucocorticoids in adipose stromal cells and fetal hepatocytes.

The biosynthesis of estrogens is catalyzed by aromatase P450 (P450arom), the product of the CYP19 gene. The tissue-specific expression of the CYP19 gene is regulated by means of tissue-specific promoters through the use of alternative splicing mechanisms. Thus, transcripts containing various 5'-untranslated termini are present in human placenta and other fetal tissues, ovary, brain, and adipose stromal cells. Sequence corresponding to untranslated exon 1.4 is present in 5'-termini of transcripts expressed in adipose tissue and fetal liver, as well as adipose stromal cells in primary culture in the presence of dexamethasone and fetal calf serum (FCS). Identification of hormone-responsive, tissue-specific promoter regions, as well as growth factor-response elements upstream of exon 1.4, may provide insight into the regulation of estrogen biosynthesis in adipose tissue, which is implicated in the development of breast and endometrial cancer. The goals of the present study were to define the 1.4 promoter region with respect to the start of transcription and to characterize the region(s) responsible for conferring glucocorticoid responsiveness on aromatase expression. The transcription initiation site was identified by means of primer extension and S1 nuclease protection analyses. No TATA-like sequence was evident upstream of this site. Various deletion mutations of the upstream flanking region of exon 1.4 and including part of exon 1.4 were made using polymerase chain reaction or restriction enzyme digestion. The genomic fragments were fused upstream of the chloramphenicol acetyltransferase (CAT) reporter gene. These constructs were transfected into adipose stromal cells and fetal hepatocytes in primary culture in medium containing FCS with or without dexamethasone. The -560/+10 base pair (bp) construct expressed CAT activity after a putative silencer element was deleted, and expression was induced by dexamethasone about 3-fold. Transfection of the -330/+170 bp construct, which contains an upstream glucocorticoid response element (GRE) as well as an Sp1-like sequence in untranslated exon 1.4, resulted in an 8-fold stimulation of expression of CAT activity by dexamethasone. The upstream GRE as well as the Sp1-like sequence in untranslated exon 1.4 were mutated separately, and together, to further confirm whether the GRE or Sp1 binding site play a role in the regulation of promoter 1.4-driven transcription. Mutation of either the GRE or Sp1 binding site, or both, in the -330/+170 bp construct, resulted in loss of dexamethasone-induced CAT reporter gene expression.(ABSTRACT TRUNCATED AT 400 WORDS)

Adipose Tissue↗
PubMed1995

Gene expression and protein distribution of collagen, fibronectin and laminin in bovine follicles and corpora lutea.

The aim of this study was to locate sites of expression and deposition of collagen, fibronectin and laminin in the bovine ovary. RNA from the granulosa and basement membrane/theca fractions of maturing follicles and from corpora lutea of the early, middle and late luteal phase was probed with cDNAs for collagen types I and IV, fibronectin and laminin. Antisera against collagens I and IV were used in western analysis of protein from follicular fluid, granulosa, basement membrane/theca and corpus luteum. Collagen subunits alpha 1(I) and alpha 2(I) were expressed in the basement membrane/theca but not in the granulosa of the follicle. They were also expressed in all luteal extracts, especially those from the early phase. Collagen alpha 2(IV) was highly expressed in the basement membrane/theca and to a lesser extent in corpora lutea. Collagen alpha 3(IV) was expressed in the granulosa, basement membrane/theca and early corpus luteum. Fibronectin 1 and laminin B2 were expressed in all tissues. Laminin B1 was expressed in all tissues except the granulosa. Collagen IV was immunodetected in all follicle extracts, with the strongest signal in the basement membrane/theca. Collagen I occurred in all luteal extracts and in the basement membrane/theca but not in follicular fluid or the granulosa. These results demonstrate tissue-specific expression of ovarian structural proteins and suggest that changes occur during the progression from follicle to corpus luteum. The production of collagen IV in the follicle wall and of collagen I in the corpus luteum is consistent with previous biochemical studies. Evidence for collagen IV in the follicular antrum suggests that the follicle wall originates from granulosa as well as theca cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Antioxidant activity of Chinese ant extract preparations.

Chinese ant extract preparations (CAEP) are a Chinese traditional medicine which is mainly used as a health food or drink for the treatment of rheumatism, rheumatoid arthritis, chronic hepatitis, sexual hypofunction, and antiaging in China. The effects on free radicals were examined by electron spin resonance spectrometry using the spin trapping agent 5.5-dimethyl-1-pyrroline-1-oxide (DMPO). Superoxide radicals (3.35 x 10(15) spins/ml) were quenched 50% by the extract at 0.5 mg/ml. The CAEP extract at 0.7 mg/ml inhibited 50% of hydroxyl radicals (52.0 x 10(15) spins/ml) generated by the Fenton reaction. Against DPPH radical, the scavenging action of CAEP was observed at 1.8 mg/ml of the extract and 50% of the DPPH radicals (8.14 x 10(15) spins/ml) were quenched. In vitro tests showed that CAEP inhibited the production of thiobarbituric acid-reactive substances, an index of lipid peroxidation, in rat brain homogenate.

Animals↗
PubMed1995

[A study of errors of radiography in 10000 intraoral periapical radiographs]

A total of 10000 full-mouth radiographs (10000 periapical radiographs were evaluated for radiographic errors.The result showed that four major types of errors were found in this study,They are cone cutting(5.59%),incorrect vertical angulation(38.84%),incorrect horizontal angulation(37.16%),and incorrect film placement (14.16%).The incidence of radiographic technique errors was 0.096%.Most errors were caused by incorrect vertical angulation and incorrect horizontal angulation(76%).Most errors were found in the cuspid premolar regions(70.6%)

Journal Article↗
PubMed1995

[Radiographic image analysis of root canal in anterior teeth.].

The aim of this study was to determine the number and morphology of anterior dental root canals,and their different types.1200 permanent anterior teeth were examined with radiographs.Each tooth was radiographed with two methods.The results showed there were four types of canals configulation in these teeth,two canals were present in less than one canal,the incidence of two canals was 9.6%.Author indicated that good quality of radiograph get an obvious value in determining both external and internal anatomy of teeth.The radiographs should be taken from two of several different angles.If a radiolucent line was located at mesial to distal of main canal,two canals should be suspected.

English Abstract↗
PubMed1995

Absorptive function of segmental allotransplanted small intestines in pigs.

Ten outbred pigs were each operated on for three times. First, a 130 cm length of terminal ileum of each pig was isolated on its vascular pedicle as a Thirty-Vella loop. One week later, the solitary ileal segments were transplanted heterotopically in two pigs. And after 28 days of heterotopic transplantation, the transplanted intestine was interposed into continuity of host intestine as orthotopic transplant. During the experiment, tests were made on 6th day after the first operation (period I), the 14th (II), 28th (III) day after heterotopic transplantation, and 3 weeks after interposition (IV) respectively for the levels of glucose, palmitate and leucine. Additionally, at period I, III, and IV, a 3 cm length of intestinal mucosa was excised for morphologic observation and determination of DNA, RNA and protein contents. After heterotopic transplantation, the absorptive function of transplanted intestine was severely impaired for two weeks. The absorption of glucose and palmitate was partially recovered by period III, at which time leucine level had return to normal. At period IV, the absorptive function of glucose and leucine had surpassed normal levels, while palmitate had risen to the level of pretransplantation. After transplantation, at period III, DNA, RNA and protein contents were well below normal. Three weeks after orthotopic transplantation, RNA and protein had risen to normal level, while DNA content remained below normal. The morphologic changes during the experiment were correlated with the changes of contents in RNA, protein and DNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The optic tract and tectal ablation influence the composition of neurofilaments in regenerating optic axons of Xenopus laevis.

Neurofilaments have been proposed to regulate axonal stability and diameter through changes in number and subunit composition. We have found that pathway and target innervation directly influence the molecular composition of neurofilaments within regenerating optic axons of Xenopus laevis. Immunocytochemistry was used to examine neurofilaments within two abnormal visual pathways. The first was an aberrant, transient retinoretinal projection, which formed when some axons entered the contralateral optic nerve at the chiasm. The second was formed by regenerating axons deprived of their normal targets by surgical ablation of both optic tecta. Distal to an orbital nerve crush, the neurofilament proteins NF-L, NF-M, NF-H, and XNIF disappear from degenerating fibers. In normally regenerating axons, these neurofilament proteins emerge in a progression reminiscent of development. In the aberrant retinoretinal projection, levels of XNIF, NF-L, and -M remained lower than in normally regenerating axons, whereas NF-H and a phosphorylated form of NF-M were undetectable for at least 35 d after nerve crush. Normally, these two latter forms reappear between 15 and 21 d after surgery. Thus, this transient, incorrect axonal projection expressed neurofilaments in a very different pattern from correctly regenerating axons. In tecta-ablated frogs, staining of phosphorylation independent epitopes of XNIF, NF-L, and -M increased normally after axons entered the tract, but that of NF-H and phosphorylated NF-M remained low for at least 42 d after axotomy. Thus, separate parts of the visual pathway influence the complexity of neurofilaments.

Animals↗
PubMed1995

[Liposculpture with tumescent technique].

This article summarized our experiences in using the tumescent technique to treat 18 patients with local fat deposit. The tumescent technique is a new technique for liposuction. It is atraumatic, less blood loss during operation, and more radical suction of local fat deposit. It is safe and effective. A new set of instrument for liposuction that was designed by us is also introduced.

Adipose Tissue↗
PubMed1995

[Effects of stellate ganglion block on coronary circulation during acute coronary occlusion].

To evaluate effects of stellate ganglion block (SGB) on coronary circulation under coronary occlusion, the changes in cardiac function and tissue blood flow in the myocardial ischemic area after right and left SGB were observed in the dogs. Tissue blood flow in the myocardial ischemic area measured with laser doppler flowmeter showed no significant change after right or left SGB. In the right SGB group, heart rate, circumflex branch blood flow and rate pressure product decreased significantly (P < 0.01); end-diastolic pressure increased slightly (P < 0.05); myocardial oxygen extraction rate showed no significant change. On the other hand, in the left SGB group, heart rate, circumflex branch blood flow and rate pressure product showed no significant changes, while end-diastolic pressure and myocardial oxygen extraction rate increased significantly (P < 0.05). These data suggest that although right SGB might be useful to improve the oxygen demand-supply relation, left SGB does not improve the oxygen demand-supply relation and might increase the risk of myocardial ischemia.

Animals↗
PubMed1995

An association study between essential hypertension and HLA-DRB1 alleles.

It is well established that genetic and environmental factors are involved in the etiology of essential hypertension (EH). Previous studies have suggested that at least one of the HLA genes is responsible for the genetic susceptibility to EH. Our aim in the present study was to investigate this issue in China by the PCR-SSP HLA-DRB1 typing method. The results showed an increased frequency of HLA-DR2 and a decreased frequency of HLA-DR7 with EH patients compared with controls. We consider that HLA-DR2 may represent a marker for susceptibility to EH in the North Chinese population.

Alleles↗
PubMed1995

[Influence of radioimmunoimaging on the survival rate of ovarian carcinoma patients].

Two groups of patients suffered from ovarian carcinoma were studied retrospectively after similar treatments; in one group of 22 patients radioimmunoimaging (RII) had been used, which was not used in the other group of 15 patients. Other factors were similar in the two group such as hospitalization period, courses of surgical treatment and regimes of chemotherapy after surgery. The staging according to FIGO was also similar in the two groups except that the number of patients in stage III was 14 in the RII group but 8 in the non-RII group. Neither the age distribution nor the histopathological diagnosis was of much difference. 131I labeled monoclonal antibody against ovarian serous adenocarcinoma, generated in our laboratory, was given to all patients intraperitoneally either before or after the surgery; 7 cases before the initial operation, 9 cases before the second look operation and 6 cases for follow up after surgery and chemotherapy. The death rates of stage III were 42.9% and 75.0% in the RII group and non-RII group respectively. By means of Kaplain Meir's life table calculation the 3 year survival rates for the two groups were 63.5% and 25.0% respectively. The RII group was obviously higher than the non-RII group even though not statistically significant. These results were similar to those reported in the literature. Three very late cases of ovarian carcinoma were reported, in whom RII had been used, are still living after follow-up for more than 5 years. The beneficial role of induction of the idiotypic network was discussed, and the possibility of innoculation is under investigation.

Antibodies, Monoclonal↗
PubMed1995

[Hemodynamic effects of inhaled nitric oxide in patients with pulmonary hypertension].

12 patients with pulmonary hypertension, primary pulmonary hypertension 3, secondary to recurrent pulmonary embolism 4, chronic obstructive pulmonary disease 2, and complicated with congenital heart disease 3, inhaled nitric oxide (NO). The NO concentration was adjusted in the range between 20-160 ppm to get a maximum hemodynamic effects. On inhaling NO, pulmonary artery pressure decreased in all patients. The maximum hemodynamic effects showed that pulmonary systolic, diastolic and mean artery pressure dropped by 22.9%, 21.0% and 20.3% (P < 0.001) respectively. Total pulmonary resistance decreased by 32.7% (P < 0.01). Cardiac index and oxygen delivery increased by 33.2% and 24.8% (P < 0.01) respectively. The ratio of pulmonary systolic artery pressure and systemic systolic artery pressure changed from the baseline 0.73 to 0.54. It is indicated that NO dilated pulmonary artery selectively in patients with hyperkinetic, obliterative and hypoxic pulmonary hypertension.

Administration, Inhalation↗
PubMed1995

Rapid HLA-DRB1 generic typing by PCR-SSP method.

We report a simple and rapid HLA-DRB1 generic typing method, PCR-SSP, which is practical and inexpensive. We use 9 sequence-specific primers and 2 group specific primers to define the HLA-DRB1 specificities DR1, DR2, DR3, DR4, DR5, DR6, DR7, DR8, DR9 and DR10. The HLA DR3, DR5, DR6 and DR8 can be amplified by the two primers of DR3568 and DRB1. The DR6 specificity can be identified by excluding the DR3, DR5 and DR8 when the DR3568 are positive. Any individuals can be typed with some exception: the three pairs of phenotype DR3/DR3 and DR3/DR6, DR5/DR5 and DR5/DR6, DR8/DR8 and DR8/DR6 cannot be discriminated from each other. We typed 106 unrelated healthy people from Beijing locations in two weeks. We think this typing method is suitable to replace the error-prone serologic HLA-DR tests in routine clinical practice, including the prospective typing of cadaveric organ donors.

Base Sequence↗