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Biomedical subjects

H Zheng

Publications and source records attributed to H Zheng.

At least 145 records · Page 8Linked to original sources
PubMed2000

Regulation of the UNC-5 netrin receptor initiates the first reorientation of migrating distal tip cells in Caenorhabditis elegans.

Cell migrations play a critical role in animal development and organogenesis. Here, we describe a mechanism by which the migration behaviour of a particular cell type is regulated temporally and coordinated with over-all development of the organism. The hermaphrodite distal tip cells (DTCs) of Caenorhabditis elegans migrate along the body wall in three sequential phases distinguished by the orientation of their movements, which alternate between the anteroposterior and dorsoventral axes. The ventral-to-dorsal second migration phase requires the UNC-6 netrin guidance cue and its receptors UNC-5 and UNC-40, as well as additional, UNC-6-independent guidance systems. We provide evidence that the transcriptional upregulation of unc-5 in the DTCs is coincident with the initiation of the second migration phase, and that premature UNC-5 expression in these cells induces precocious turning in an UNC-6-dependent manner. The DAF-12 steroid hormone receptor, which regulates developmental stage transitions in C. elegans, is required for initiating the first DTC turn and for coincident unc-5 upregulation. We also present evidence for the existence of a mechanism that opposes or inhibits UNC-5 function during the longitudinal first migration phase and for a mechanism that facilitates UNC-5 function during turning. The facilitating mechanism presumably does not involve transcriptional regulation of unc-5 but may represent an inhibition of the phase 1 mechanism that opposes or inhibits UNC-5. These results, therefore, reveal the existence of two mechanisms that regulate the UNC-5 receptor that are critical for responsiveness to the UNC-6 netrin guidance cue and for linking the directional guidance of migrating distal tip cells to developmental stage advancements.

Animals↗
PubMed2000

mab-20 encodes Semaphorin-2a and is required to prevent ectopic cell contacts during epidermal morphogenesis in Caenorhabditis elegans.

The Semaphorins are a family of secreted and transmembrane proteins known to elicit growth cone repulsion and collapse. We made and characterized a putative null mutant of the C. elegans gene semaphorin-2a (Ce-sema-2a). This mutant failed to complement mutants of mab-20 (Baird, S. E., Fitch, D. H., Kassem, I. A. A. and Emmons, S. W. (1991) Development 113, 515-526). In addition to low-frequency axon guidance errors, mab-20 mutants have unexpected defects in epidermal morphogenesis. Errant epidermal cell migrations affect epidermal enclosure of the embryo, body shape and sensory rays of the male tail. These phenotypic traits are explained by the formation of inappropriate contacts between cells of similar type and suggest that Ce-Sema-2a may normally prevent formation or stabilization of ectopic adhesive contacts between these cells.

Amino Acid Sequence↗
PubMed2000

Role of mast cells in early and delayed radiation injury in rat intestine.

Mast cell hyperplasia is a characteristic feature of many inflammatory and fibrotic conditions, including intestinal radiation injury (radiation enteropathy). This study used mast cell-deficient rats to define the role of mast cells in the mechanisms underlying early radiation-induced mucosal injury and delayed intestinal wall fibrosis. Mast cell-deficient (Ws/Ws) mutant rats and mast cell-competent (+/+) littermates were used. A 4-cm loop of ileum was exposed to 21 Gy single-dose radiation. Irradiated and unirradiated intestine were examined at 2 or 26 weeks using quantitative histology and morphometry. Quantitative immunohistochemistry was used to assess transforming growth factor beta (Tgfb), myeloperoxidase, and epithelial and smooth muscle cell proliferation. Collagen content was measured colorimetrically, and steady-state Tgfb1 mRNA was determined with fluorogenic probe RT-PCR. Compared to +/+ rats, Ws/Ws animals exhibited strikingly exacerbated mucosal injury but minimal reactive intestinal wall fibrosis. Ws/Ws rats exhibited less radiation-induced intestinal smooth muscle cell proliferation and collagen accumulation than +/+ littermates. Tgfb expression increased to a similar extent in Ws/Ws and +/+ rats. Unirradiated intestine from Ws/Ws and +/+ rats did not differ significantly. Mast cells protected the intestinal mucosa during the early phase of radiation enteropathy and promoted intestinal fibrosis after the breakdown of the mucosal barrier. Mast cells may be required for Tgfb to exert its full fibrogenic effect in radiation enteropathy.

Animals↗
PubMed2000

Conservative management for an extensive type A aortic dissection complicating coronary angioplasty.

Aortic dissection is a recognized, though rare complication of percutaneous revascularization procedures. We report a case of an extensive type A dissection that occurred during an attempt to recanalize a chronic total occlusion of a right coronary artery. The patient was treated conservatively and was followed for 36 months, during which he remained well. We conclude that, even though surgery remains the preferred option, conservative management could also be considered in certain patients.

Aortic Dissection↗
PubMed2000

Organization of transport from endoplasmic reticulum to Golgi in higher plants.

In plant cells, the organization of the Golgi apparatus and its interrelationships with the endoplasmic reticulum differ from those in mammalian and yeast cells. Endoplasmic reticulum and Golgi apparatus can now be visualized in plant cells in vivo with green fluorescent protein (GFP) specifically directed to these compartments. This makes it possible to study the dynamics of the membrane transport between these two organelles in the living cells. The GFP approach, in conjunction with a considerable volume of data about proteins participating in the transport between endoplasmic reticulum and Golgi in yeast and mammalian cells and the identification of their putative plant homologues, should allow the establishment of an experimental model in which to test the involvement of the candidate proteins in plants. As a first step towards the development of such a system, we are using Sar1, a small G-protein necessary for vesicle budding from the endoplasmic reticulum. This work has demonstrated that the introduction of Sar1 mutants blocks the transport from endoplasmic reticulum to Golgi in vivo in tobacco leaf epidermal cells and has therefore confirmed the feasibility of this approach to test the function of other proteins that are presumably involved in this step of endomembrane trafficking in plant cells.

Amino Acid Sequence↗
PubMed2000

DNA analysis of a pedigree with myotonic dystrophy in Songjiang county, Shanghai.

OBJECTIVE: To make the molecular analysis of a pedigree with myotonic dystrophy (DM) in Songjiang county, Shanghai, and to observe the connection between CTG repeat number and clinical features. METHODS: In twenty-three individuals of a pedigree with DM, CTG trinucleotide repeat numbers located in the 3' untranslated region of a protein kinase gene (MTPK) on chromosome 19q13.2-3 were analyzed by using Long Expand TM Template PCR system. RESULTS: Four of eight clinical patients had expanded DM allele, the other four had no expanded CTG copies. Seven of eight suspicious DM cases had expanded CTG repeat numbers and were therefore genetically diagnosed as DM, and an asymptomatic individual was diagnosed as a doubted DM patient by DNA analysis. High risk of DM in six of seven individuals was ruled out, and a clinical doubted DM individual was ascertained a normal person by molecular analysis. A positive correlation was found beween early onset and expanded CTG repeat number in six parents (or grandparents)/child pairs, but in the pair II 2 /IV 7 CTG repeat numbers were reduced from 3100 in the grandmother to 175 in her grandson and there was no anticipation phenomenon. CONCLUSION: The measurement of CTG repeat number can help to ascertain the diagnosis of DM in clinical and preclinical patients, but some clinically- diagnosed DM patients might have normal CTG repeat numbers. Anticipation phenomena were common in the pedigree.

Adolescent↗
PubMed2000

[Detection of impurities in DNA samples by using the convolution spectrum method].

AIM: To detect the presence of phenol, amino acids and endotoxin in DNA preparations. METHODS: By using the convolution curve transformation technology, correlation coefficient discriminant which was put forward by spectrum space theory and computer information process technology, impurities in DNA samples were detected. RESULTS: The convolution spectrum method compared with A260/A280 ratio method and second-derivative absorption spectrum method could be used for the semiquantitative determinations of impurities in DNA samples and the results were satisfactory. CONCLUSION: The method was simple, convenient, fast and valuable to the biochemical analysis.

Amino Acids↗
PubMed2000

Effects of 2-[3-estrone-N-ethyl-piperazine-methyl]tetracycline (XW630) on osteoporosis in ovariectomized rats.

AIM: To study the effects of 2-[3-estrone-N-ethyl-piperazine-methyl]tetracycline (XW630) on experimental osteoporosis in ovariectomized (OVX) rats. METHODS: Serum estradiol (E2) content and bone 1-carboxyglutamic acid-containing protein (BGP) content were measured by radioimmunoassay. With undecalcified bone section and tetracycline intraperitoneal labeling, the bone static and dynamic data were studied in right femur samples. RESULTS: After treatment with XW630 2.5 mg.kg-1, serum BGP content increased by 75.7% but there was no change in serum E2 content and uterus weight compared with OVX rats. Compared with OVX rats, the static data of trabecular bone volume/total tissue volume, trabecular bone volume/sponge bone volume, and mean trabecular plate density were enhanced after treatment with XW630 for 13 wk. The dynamic data of single-labeled surface, double-labeled surface, trabecular osteoid surface, and bone formation rate in tissue level in XW630 group were increased and osteoid maturation period was shortened. CONCLUSION: XW630 enhanced bone activation frequency and increased trabecular connectivity, stability, and strength. XW630 stimulated bone formation and inhibited bone resorption with no effect on reproductive system.

Animals↗
PubMed2000

Effects of XW630 on cell proliferation, iNOS activity, and cGMP content in human osteoblast-like cell line TE85.

AIM: To study the effects of 2-[3-estrone-N-ethyl-piperazine-methyl] tetracycline (XW630) in human osteoblast-like cell line TE85. METHODS: [3H]Thymidine incorporation and cell count for cell proliferation, radioimmunoassay for cyclic GMP (cGMP) content, and monitoring the conversion of [3H]arginine for inducible nitric-oxide synthase (iNOS) activity assay. RESULTS: After treatment with XW630 for 48 h, [3H]thymidine incorporation and cell numbers increased by 62.7% and 96.9%, respectively. NG-monomethyl-L-arginine (L-NMMA, an NOS inhibitor) induced a concentration-dependent inhibitory effect on the proliferation after treatment for 48 h. The inhibitory effect was prevented partially by XW630 (1.0 nmol.L-1). After treatment with XW630 for 12-48 h, iNOS activity and cGMP concentration increased in time-dependent manners. CONCLUSION: XW630 stimulated cell proliferation, enhanced iNOS activity and cGMP content in human osteoblast-like cell line TE85.

Bone Neoplasms↗
PubMed2000

[Studies on clinical trials and immune effect of a new purified rabies vaccine prepared from Vero cells].

OBJECTIVE: To observe the safety and neutralizing antibody response of a new purified rabies vaccine prepared from Vero cells. METHODS: The vaccine used was manufactured in Hainan Institute of Biologicals and licensed by the Ministry of Health for clinical trials. The vaccine was administrated in 30 and 318 volunteers during phase I and II clinical trials with preexposure (day 0, 7, and 28) or post exposure (day 0,3,7,14 and 28) vaccination schedules. The "Verorab (PVRV)", a rabies vaccine made in France was used as control. RESULTS: The results showed that the new purified vaccine did not cause any severe and moderate side reactions, the slight side reaction rate was 12% including those complained by vaccines themselves. The immunological effect was determined by detecting neutralizing antibody with mouse neutralization test (NIH). The positive seroconversion rates of neutralizing antibody were 100% (n= 27, GMT 2.89 IU/ml) and 100% (n= 30, GMT 5.29 IU/ml) respectively by pre- exposure and post exposure schedules. No significant difference was found when compared with France "Verorab" vaccine by preexposure schedule (n= 24, GMT 2.13 IU/ml). CONCLUSIONS: The clinical trials indicated that the purified rabies vaccine prepared from Vero cells only showed slight side reaction and had good neutralizing antibody response. Therefore this new vaccine is safe and protective for the prevention of rabies in human.

Animals↗
PubMed2000

Gonadotropin-releasing hormone agonists and laparoscopy in the treatment of adenomyosis with infertility.

OBJECTIVE: To study the role and value of gonadotropin-releasing hormone agonists (GnRH-a) and laparoscopy for the treatment of adenomyosis with infertility. METHODS: Four cases were seen with adenomyosis and infertility, 3 of these cases also presented local adenomyomata in the posterior uterine wall. GnRH-a Triptorelin (decapeptyl) or Goserelin (Zoladex) therapy was instituted for six months before laparoscopic surgery for coexisting pelvic pathologic infertility factors in one case and after laparoscopic surgery in three cases. RESULTS: All cases remained amenorrheic during GnRH-a therapy. After the GnRH-a therapy, all enlarged uterus (7-10 weeks gestation size) all decreased to normal or near normal size; menstruation returned in 80-90 days and three cases conceived within four menstrual periods after cessation of treatment. In the 4 cases one pregnancy resulted in the birth of a healthy 3150 g male newborn at 38 weeks gestation by cesarean section; one pregnancy was terminated after adenomyomectomy by emergency cesarean section at 30 weeks gestation because of threatened rupture of uterus; one case was then normal at 28 weeks pregnancy; the last case had 2 resumptive menstrual periods and was still being followed up. CONCLUSIONS: GnRH-a is markedly efficient in reducing adenomyotic uterine size, facilitates uterine or endometrial receptivity for embryos and enhances uterine ability to maintain pregnancy. For adenomyomata associated with infertility, GnRH-a instead of surgical removal of lesions, which are deep in the myometrium, may avoid uterine rupture when pregnancy occurs. For infertility, GnRH-a treatment before laparoscopic surgery greatly decreases surgical difficulties and blood loss in certain cases.

Adult↗
PubMed2000

[Prevalence of prostatic hyperplasia and its relative factors in six cities of China in 1997].

OBJECTIVE: To study crude prevalence and distribution of the elderly prostatic hyperplasia. METHODS: Three thousand three hundred and sixty-one elderly aged 60 years and above in the urban and rural areas of Beijing, Shanghai, Guangzhou, Chengdu, Xi'an and Shenyang were investigated, using clustered random sampling methods. RESULTS: The crude prevalence of prostatic hyperplasia was found to be 43.68% with an increase with ageing (P < 0.01). The crude prevalence rates of prostatic hyperplasia among the elderly of 60-, 65-, 70-, 75-, 80-, 85- years old were 34.48%, 40.27%, 46.77%, 51.44%, 57.32% and 60.19% respectively (P < 0.01). Rates in the urban and rural areas were 46.79%and 39.64% respectively. The crude prevalence of urban areas was higher than that of rural areas (P < 0.01) and was found higher in Beijing (63.28%) and Guangzhou (54.28%), (P < 0.01). The crude rates prevalence of managers (54.88%), teachers and business men (55.17%) were in general higher than the prevalence of the workers (41.29%) and peasant (37.26%). Logistic regression analysis showed that the crude prevalence was related to ageing, profession and residential areas (P respective < 0.01). CONCLUSION: The prevalence of prostatic hyperplasia was higher in the elderly and became a common disease of the male elderly in China. Prevention and treatment of prostatic hyperplasia in the elderly should be strengthened.

Age Distribution↗
PubMed2000

[Immobilization osteoporosis and fracture in children].

This study was intended to enhance the diagnostic vigilance of immobilization osteoporosis with fracture and explore its prevention and treatment. Thirteen children with the hip disease underwent one to nine months of plaster cast after operation. A retrospective analysis was made on these 13 patients with fracture and immobilization osteoporosis. The result showed that disuse fracture occurred in fifteen places of their femora. All of these cases were cured by non-operative and drug treatment. These data suggest that for the cases of immobilization osteoporosis it is important to prevent fracture by means of early diagnosis, proper drugs, early function exercise, appropriately shorter period of fixation and the avoidance of trauma.

Child↗
PubMed2000

[p27 protein expression and its significance in human laryngeal carcinoma].

OBJECTIVE: To determine clinical significance and expression of p27 protein in human laryngeal carcinoma tissue. METHOD: To measure p27 protein expression in 50 cases laryngeal carcinoma tissue by immunohistochemical LSAB (labelled streptavidin biotin) method, 15 cases vocal cord polyps used as control. RESULT: There was significant difference between p27 protein expression in laryngeal carcinoma and in vocal cord polyps, among pathological staging of laryngeal carcinoma (G1-G2 and G3), between the survived and the dead laryngeal carcinoma patients 3 years after operation, but no significant difference among clinical staging and between the patients with and without lymph node metastases. There was significant difference between the survival rate curves (Kaplan-meier curve) in p27 protein expression positive group and that in p27 protein expression negative group. CONCLUSION: p27 Protein expression is related to malignant degree of laryngeal carcinoma, so it can be an important marker of identifying the malignancy and prognosis of laryngeal carcinoma.

Adult↗
PubMed2000

[Experimental observation on anaphylaxis induced by Echinococcus infection in Meriones unguiculatus].

OBJECTIVE: To observe the anaphylaxis induced by Echinococcus granulosus or E. multilocularis (E. g. and E. m.) infection in Meriones unguiculatus. METHODS: 56 and 48 gerbils were intraperitoneally inoculated with E. g. protoscoleces and E. m. tissue homogenate. After three months, the anaphylactic responses initiated by intraperitoneal challenge injection with E. g. cystic fluids or partially purified antigen or E. m. metacestode homogenate antigen were observed. IgE antibody and direct eosinophilic leukocyte count (DELC) were detected at pre-postchallenge. RESULTS: The infection rates for E. g and E. m. in 56 and 48 gerbils were 89.3% and 97.9%, respectively. Among these groups, the lowest rate of anaphylaxis was 62.5%, the highest was 100%. The lowest rate of anaphylactic shock was 12.5%, and the highest 16.7%. After the gerbis were infected with E. g. and E. m., both IgE antibody and DELC increased gradually. At 60 min post challenge, IgE antibody level were significantly decreased, while DELC showed a sharp increase. CONCLUSION: Anaphylaxis could be induced in gerbils by Echinococcus infection followed by a challenge injection. Different antigens lead to different and degrees among the anaphylactic responses in the gerbils, however, there were no significant differences between E. g. and E. m. infections in gerbils.

Anaphylaxis↗
PubMed2000

[Morphological and commercial identification on semen torreyae].

The morphological characters and commercial identification on Semen Torreyae has been reported. The results of identification of commercial samples indicated that Torreya grandis was mainly used; T. fargesii, T. yunnanensis and T. jackii were used in their producing areas.

Pharmacognosy↗