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Biomedical subjects

Y Shi

Publications and source records attributed to Y Shi.

At least 307 records · Page 17Linked to original sources
PubMed1999

Causes of childhood blindness in the People's Republic of China: results from 1131 blind school students in 18 provinces.

AIMS: To determine the anatomical site and underlying causes of blindness and severe visual impairment in children under 16 years of age in special education in the People's Republic of China with a view to determining potentially preventable and treatable causes. METHODS: A national study of children attending schools for the blind in China was conducted between April and June 1998 using the WHO Prevention of Blindness Programme (WHO/PBL) eye examination record for children with blindness and low vision. Eight Chinese ophthalmologists attended a training workshop before conducting the study. 36 blind schools in 18 provinces of China were included. RESULTS: 1245 children aged between 5 and 15 years were examined, of whom 1131 (91%) were blind or severely visually impaired (visual acuity less than 6/60 in the better eye). The commonest anatomical sites of visual loss were whole globe (mainly microphthalmos) 25.5% and retina (mainly dystrophies) 24.9%. Lens was the major site in 18. 8%, optic nerve in 13.6%, and glaucoma in 9%. Corneal scarring was not a major cause of visual loss. The aetiology was unknown in 52.9%, hereditary factors were responsible in 30.7%, and childhood causes in 14%. 15% of cases were considered potentially preventable and 22. 5% potentially treatable. CONCLUSION: The pattern of childhood blindness seen in this study is likely to reflect the improved health and socioeconomic status of China but may partly reflect bias in admission to, and location of, blind schools, with higher socioeconomic groups overrepresented. Nutritional and infective causes of blindness are uncommon, and hereditary and unknown factors are now the predominant causes.

Adolescent↗
PubMed1999

Threonine phosphorylations induced by RX-871024 and insulin secretagogues in betaTC6-F7 cells.

Treatment of the pancreatic beta-cell line betaTC6-F7 with an imidazoline compound, RX-871024, KCl, or tolbutamide resulted in increased threonine phosphorylation of a 220-kDa protein (p220) concurrent with enhanced insulin secretion, which can be partially antagonized by diazoxide, an ATP-sensitive potassium (K(ATP)) channel activator. Although phosphorylation of p220 was regulated by cytoplasmic free calcium concentration ([Ca(2+)](i)), membrane depolarization alone was not sufficient to induce phosphorylation. Phosphorylation of p220 also was not directly mediated by protein kinase A, protein kinase C, or insulin exocytosis. Analysis of subcellular fractions indicated that p220 is a hydrophilic protein localized exclusively in the cytosol. Subsequently, p220 was purified to homogeneity, sequenced, and identified as nonmuscle myosin heavy chain-A (MHC-A). Stimulation of threonine phosphorylation of nonmuscle MHC-A by KCl treatment also resulted in increased phosphorylation of a 40-kDa protein, which was coimmunoprecipitated by antibody to MHC-A. Our results suggest that both nonmuscle MHC-A and the 40-kDa protein may play roles in regulating signal transduction, leading to insulin secretion.

Amino Acid Sequence↗
PubMed1999

Attenuation of renal ischemia-reperfusion injury in inducible nitric oxide synthase knockout mice.

Renal ischemia-reperfusion (I/R) injury was investigated in inducible nitric oxide synthase (iNOS) knockout mice. After a 26-min bilateral renal pedicle clamp, serum creatinine concentrations (in mg/dl) in wild-type mice after a 24-h reperfusion were 0.25 +/- 0.03 in sham-operated controls and 2.3 +/- 0.38 in ischemic mice (P < 0. 01); after 48 h, concentrations (in mg/dl) were 0.25 +/- 0.03 in controls and 2.0 +/- 0.18 in ischemic mice (P < 0.01). iNOS knockout mice demonstrated an attenuation of serum creatinine concentration after renal I/R injury. Serum creatinine concentrations (mg/dl) after a 24-h reperfusion were 2.3 +/- 0.22 in wild-type ischemic and 1.21 +/- 0.25 in iNOS knockout ischemic mice (P < 0.05); after 48 h, concentrations were 2.0 +/- 0.18 in wild-type ischemic and 0.96 +/- 0.25 in iNOS knockout ischemic mice (P < 0.01). Histological scoring of acute tubular necrosis in iNOS knockout mice was decreased compared with that in wild-type controls (0.88 +/- 0.2 vs. 3.3 +/- 0. 3, P < 0.05). iNOS protein in the renal cortex of wild-type mice subjected to renal I/R injury was undetectable up to 48 h. However, a strong upregulation of heat shock protein 72 expression was observed in renal cortex of iNOS knockout mice under basal conditions. In conclusion, kidneys of iNOS knockout mice were protected against ischemic acute renal failure. This protective effect may be related to a compensatory upregulation of heat shock protein 72.

Animals↗
PubMed1999

Role of matrix metalloproteinases and their tissue inhibitors in the regulation of coronary cell migration.

The migration of vascular cells is regulated by matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). Because the activation of adventitial fibroblasts has been implicated in coronary repair, we have examined regional differences in cell outgrowth and the synthesis of MMPs/TIMPs in different layers of porcine coronary arteries. Coronary medial explants demonstrated significantly slower cell outgrowth than coronary adventitia in culture (P<0.001). These observations were paralleled by the predominant expression of TIMP-1 and -2 in the media (14-fold and 37-fold higher than in adventitia, respectively, P<0.001), whereas higher gelatinolytic activities (MMP-2 and -9) were released from adventitial explants. Smooth muscle cell outgrowth from the media was regulated by endogenous TIMPs, since TIMP inhibition (recombinant MMP-2 or neutralizing anti-TIMP antibodies) facilitated cell outgrowth (P<0.001). In contrast, the addition of recombinant TIMP-1 or -2 decreased adventitial cell outgrowth. In the coculture experiments, the presence of coronary media retarded adventitial cell outgrowth, whereas medial damage abrogated these effects, allowing for fibroblast migration (P<0.001). In conclusion, this study demonstrated differential migratory properties and distinct MMP/TIMP synthesis by coronary fibroblasts and smooth muscle cells. Endogenous TIMPs in the media may play an important role in maintaining coronary arterial wall homeostasis, whereas high levels of matrix-degrading activities confer the "invasive" characteristics of adventitial fibroblasts.

Animals↗
PubMed1999

Calcium-induced modification of protein conformation demonstrated by immunohistochemistry: What is the signal?

A recent study by Morgan et al. on the mechanism of the heating antigen retrieval (AR) has raised an interesting issue concerning calcium-induced modification of protein conformation demonstrated by immunohistochemistry (IHC). The current study is based on calcium-induced modification of thrombospondin (TSP) and Ki-67, as demonstrated by IHC using seven monoclonal antibodies (MAbs) to TSP and an MAb MIB1. Experiments were carried out on frozen tissue sections of bladder carcinoma and lymph node. Frozen sections were incubated with solutions of 50 mM CaCl2 and/or 10 mM EDTA at 4C overnight before formalin or acetone fixation for TSP and Ki-67, respectively. Sections were then fixed in 10% neutral buffered formalin or acetone before immunostaining. Seven MAbs to TSP, named Ab1 to 7 representing clone numbers of A4.1, D4.6, C6.7, A6.1, B5.2, A2.5, and HB8432, respectively, and MIB1 were utilized as primary antibodies. ABC was used as the detection system and AEC as the chromogen for immunohistochemical staining. An extracellular immunostaining pattern represented a positive result for TSP, and nuclear staining for MIB1. Frozen sections preincubated in 50 mM CaCl2 overnight at 4C showed significant loss of staining and/or altered staining pattern for six of the seven antibodies to TSP and MIB1 compared to positive controls not exposed to CaCl2. Lack of immunostaining of TSP and MIB1 attributable to exposure to CaCl2 could be partially recovered by incubating the frozen sections in EDTA. Calcium-induced modification of protein structure was demonstrated more than 10 years ago on the basis of immunochemical techniques. In this study, similar calcium-induced modification of protein was detectable by IHC in frozen tissue sections, suggesting that calcium-induced modification of protein structure may occur independently of fixation-induced modification. The fact that calcium binding may affect IHC staining is not surprising in view of the fact that antibody/antigen interactions are protein structure-dependent. However, in this experiment the change occurred before and independent of formalin fixation and does not necessarily imply a role for calcium in AR. There may be a valuable role for the use of chemical modification in visualization of protein structure changes in tissue sections by IHC. (J Histochem Cytochem 47:463-469, 1999)

Calcium↗
PubMed1999

Molecular and cellular basis of tissue remodeling during amphibian metamorphosis.

Amphibian metamorphosis involves systematic transformations of various tadpole organs/tissues. Three major types of changes take place during this process. These are remodeling, resorption, and de novo development, all of which appear to involve both cell proliferation and apoptosis (programmed cell death). All metamorphic changes are controlled by thyroid hormone (T3) and are organ-autonomous. Recent studies using primary cell cultures and a stably transformed cell line from tadpole tissues have implicated that T3 induces apoptosis cell-autonomously. This T3-induced, metamorphosis-associated apoptosis is similar to cell death in other animal species and involves similar cell death executioners. Both the activation of these executioners and the pathways leading to cell proliferation and differentiation are believed to be through transcriptional regulation by T3 receptors (TRs). TRs can activate or repress target gene transcription depending upon the presence or absence of T3, respectively. Many direct T3-response genes have been isolated and found to encode a variety of proteins that can affect both intra- and extra-cellular events. The determinations of the identities of these response genes through sequence analyses and studies on their expression profiles during development have provided strong clues toward their roles in metamorphosis. However, future studies using organ and cell culture systems and/or transient or stable transgenic technologies are required to understand how these genes transduce the T3 signal to activate the downstream cell death and proliferation/differentiation pathways.

Amphibians↗
PubMed1999

Role of caspases in hypoxia-induced necrosis of rat renal proximal tubules.

The role of the caspases, a newly discovered group of cysteine proteases, was investigated in a model of hypoxia-induced necrotic injury of rat renal proximal tubules. An assay for caspases in freshly isolated rat proximal tubules was developed. There was a 40% increase in tubular caspase activity after 15 min of hypoxia in association with increased cell membrane damage as indicated by a threefold increase in lactate dehydrogenase release. The specific caspase inhibitor Z-Asp-2,6-dichlorobenzoyloxymethylketone (Z-D-DCB) attenuated the increase in caspase activity during 15 min of hypoxia and markedly decreased lactate dehydrogenase release in a dose-dependent manner. In the proximal tubules, Z-D-DCB also inhibited the hypoxia-induced increase in calpain activity, another cysteine protease. In contrast, when Z-D-DCB was added to purified calpain in vitro, there was no inhibition of calpain activity. The calpain inhibitor (2)-3-(4-iodophenyl)-2-mercapto-2-propenoic acid (PD150606) also inhibited the hypoxia-induced increase in caspase activity in proximal tubules, but did not inhibit the activity of purified caspase 1 in vitro. In these experiments, caspase activity was detected with the fluorescence substrate Ac-Tyr-Val-Ala-Asp-7-amido-4-methyl coumarin (Ac-YVAD-AMC), which is preferentially cleaved by caspase 1. However, minimal caspase activity was detected with the fluorescence substrate Ac-Asp-Glu-Val-Asp-7-amido-4-methyl coumarin (Ac-DEVD-AMC), which is cleaved by caspases 2, 3, and 7. The present study in proximal tubules demonstrates that (1) caspase inhibition protects against necrotic injury by inhibition of hypoxia-induced caspase activity; and (2) caspase 1 may be the caspase involved. Thus, although the role of caspases in apoptotic cell death is well established, this study provides new evidence that caspases contribute to necrotic cell death as well.

Animals↗
PubMed1999

A double blind observation for therapeutic effects of the tong luo kai bi tablets on rheumatoid arthritis.

The therapeutic effects of the Tong Luo Kai Bi Tablets [symbol: see text] in 120 patients with rheumatoid arthritis were observed in this clinical trial by the randomized double blind method. Both the observed group and the control group each had 60 patients. In the observed group treated with the Tong Luo Kai Bi Tablets, 1 case (1.7%) was cured clinically, 27 cases (45.0%) improved markedly, 26 cases (43.3%) improved, with a total effective rate of 90.0%. In the control group treated with Rheumatic Semen Strychni Tablets [symbol: see text], no case was cured, 16 cases (26.7%) improved markedly, 33 cases (55.0%) improved, with a total effective rate of 81.7%. Statistical data showed the Tong Luo Kai Bi Tablets had much better therapeutic effectiveness clinically than the Rheumatic Semen Strychni Tablets (P < 0.05).

Adult↗
PubMed1999

[The effect of insulin-like growth factor I and insulin on intrauterine fetal growth retardation].

OBJECTIVE: To evaluate the role of insulin-like growth factor I (IGF-I) and insulin (Ins) in the occurrence of intrauterine fetal growth retardation (IUGR). METHODS: The study group included 17 women with IUGR, and 38 normal third trimester pregnant women were served as control. Maternal venous blood samples were collected from all cases before cesarean section. Umbilical venous blood and amniotic fluid were collected at the time of operation. The concentrations of Ins were measured by radioimmunoassay and concentrations of IGF-I were assayed by ELISA. RESULTS: The maternal serum IGF-I in IUGR group (117.29 micrograms/L) was significantly lower than that in the control group (207.07 micrograms/L) (P < 0.002). The umbilical serum IGF-I in IUGR group (16.73 micrograms/L) was significantly lower than that in the control (44.89 micrograms/L) (P < 0.001). There was no significant difference of maternal serum Ins between IUGR group (12.18 mIU/L) and control group (7.13 mIU/L). CONCLUSIONS: The change of IGF-I and Ins levels in maternal and umbilical serum may play an important role in the pathophysiological changes in IUGR.

Adult↗
PubMed1999

[The immunohistochemical studies on estradiol and progesterone receptors in human decidua after terminating early pregnancy by mifepristone].

OBJECTIVE: To investigate the effects of mifepristone on decidua at the cellular level of estrogen receptor (ER) and progesterone receptor (PR) and the mechanism of prolonged uterine bleeding after terminating early pregnancy by mifepristone. METHODS: Thirty decidua specimens were obtained from pregnant women with amenorrhea of 6-7 week duration, 20 women were treated with mifepristone and 10 given mifepristone plus misoprostol respectively. Immunocytochemical reactions of PR nad ER in decidua were compared among three groups using computer image analysis technology. RESULTS: In the control group, the nuclei of the decidual cells were stained positively for ER and PR. Their integral values of receptor level were 5,860,790 +/- 311,691 for ER and 4,905,970 +/- 157,319 for PR. Mifepristone treatment reduced ER and PR staining. The integral values were 3,547,180 +/- 191,858 for ER and 3,700,750 +/- 188,322 for PR in this group, and it was more apparent in the group treated with mifepristone plus misoprostol: 2,021,721 +/- 145,281 for ER and 2,528,580 +/- 240,535 for PR. CONCLUSIONS: The ER and PR level in human decidua decreased after mifepristone or/and misoprostol treatment. This may be related to prolonged uterine bleeding after terminating early pregnancy by mifepristone.

Abortifacient Agents, Nonsteroidal↗
PubMed1999

[Comparison of endometrial histology and ultrastructure during different ovarian stimulation protocols in hamsters].

OBJECTIVE: To evaluate the influence of ovarian stimulation by pregnant mare's serum gonadotropin(PMSG) with or without gonadotropin releasing hormone agonist (GnRH-a) on endometrial histology and ultrastructure in hamsters. METHODS: Thirty hamsters were randomly allocated into 3 groups. (1) LA + PMSG group: Leuprolide acetate (LA) was given first for desensitizing the pituitary, then PMSG added for ovarian stimulation. (2) PMSG group was injected with PMSG only. (3) Control group was given with saline of same volume as groups LA + PMSG and PMSG on the same time schedule. Endometrial histology and ultrastructure were investigated by light microscope and electron microscope. RESULTS: Comparing to the controls, the changes of endometrial histology in group of LA + PMSG was not significantly different, but its ultrastructure had marked atterations: mitochondria swelling, undifferentiated crista and no basket-like structure. Delayed endometrial maturation was frequently found in group PMSG (P < 0.01), and the ultrastructure showed poorly developed mitochondria. CONCLUSION: The degree of endometrial maturation varied considerably with different ovarian stimulation protocols. Ovarian stimulation with GnRH-a was better than PMSG alone, because the protocol LA + PMSG, in hamsters, facilitated the formation of a physiologic endometrium. But the protocol with GnRH-a still had a negative effect on endometrial ultrastructure.

Animals↗
PubMed1999

[Analyses of the factors affecting the occurrence of polypronuclear embryos in in-vitro fertilization and embryo transfer].

OBJECTIVE: To investigate the factors affecting the occurrences of the polypronuclear embryos in in-vitro fertilization and embryo transfer (IVF-ET). METHODS: The data from 145 IVF-ET cycles and 1,168 oocytes were analyzed by logistic regression for multiple factors. The influences of the couple's age, the superovulation stimulation protocols, the number of the follicles punctured and the oocytes obtained, the preinseminational interval, the quality and quantity of seminal and inseminational sperms, and the oocyte fertilization ratio on the incidences of the polypronuclear embryos from the matured, and immature oocytes were examined respectively. RESULTS: The incidence of the polypronuclear embryos from matured oocytes was significantly negatively correlated with the women age and the number of the follicles punctured, and the incidence from immature oocytes was significantly positively correlated with the density of sperms at grade a and b and the oocyte fertilization ratio. CONCLUSIONS: The woman's age and the number of follicles are the main factors which influence the occurrence of polypronuclear embryos from matured oocytes, while the density of the seminal sperm with high motility and the fertilization ratio play important roles in the occurrence of polypronuclear embryos in immature oocytes. Stimulating greater number of follicles might be benefit for the reduction of occurrence of polypronuclear embryos.

Embryo Transfer↗
PubMed1999

Expression of endothelial cell IgG Fc receptors and markers on various cultures.

OBJECTIVE: To determine and compare the expression of endothelial cell IgG Fc receptors (Fc gamma R) and markers on various kinds of cultures. METHODS: Human breast microvascular endothelial cells (HMVEC), human aortic endothelial cells (HAEC), human umbilical vein endothelial cells (HUVEC) and canine aortic endothelial cells (CAEC) were stimulated with cytokines tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). The binding of anti-Fc gamma receptor (Fc gamma R) type I, II and III antibodies was measured using an enzyme-linked immunosorbent assay (ELISA). The constitutive expression of endothelial cell markers was examined using anti-von Willebrand factor antibodies, Dil-low density lipoprotein (Dil-Ac-LDL) and fluorescein isothiocyanate (FITC)-labeled ulex europaeus agglutinin-1. RESULTS: The binding of anti-Fc gamma R II was significantly increased by the simultaneous stimulation with TNF-alpha and IFN-gamma on all three types of human endothelial cells (ECs), but not on canine endothelial cells. Enhanced Fc gamma R II expression was most significant when human ECs were cultured in endothelial cell basal medium (ECBM). However, the expression of Fc gamma R II on CAECs could not be induced by human cytokines even after they were cultured in ECBM for 3 passages. Endothelial cells also showed diversity for the constitutive expression of classic markers. CONCLUSIONS: This study demonstrate that cytokines TNF-alpha and IFN-gamma enhance low-affinity Fc gamma R expression on human endothelial cells in vitro. The results indicate that heterogeneity of endothelial cells exists not only on constitutive expression but also on stimulative expression.

Animals↗
PubMed1999

DNA vaccine pCD-Sj32 and its efficacy of protective immunity against infection of Schistosoma japonicum.

OBJECTIVE: To study protective immunity afforded by murine immunization with DNA vaccine of Schistosoma japonicum (S. japonicum) as measured by reduction in worm burden and host antibody, cytokines. METHODS: DNA vaccine pCD-Sj32 was constructed, identified and expressed. pCD-Sj32 could induce substantial protective immunity against infection of S. japonicum in BALB/c mice. The best efficacy can be produced with one injection of 100 micrograms DNA into the quadriceps muscle, combined with challenge for 8 weeks after immunization. T lymphocyte subsets of CD8+, IL-2. TNF and IFN-gamma of experimental animal could play important roles in regulating immune functions of schistosomiasis. RESULTS: High titre of specific antibody IgG could be induced by vaccinated with pCD-Sj32, and antibody can mediate macrophage to produce ADCC effects in vitro. CONCLUSION: pCD-Sj32 may represent a new approach to developing subunit vaccine.

Animals↗
PubMed1999

[Combination of high-dose chemotherapy with autologous hematopoietic stem cell transplantation for recurrent and high-risk breast cancer: a pilot study].

OBJECTIVE: To evaluate the therapeutic effectiveness and safety of combined high-dose chemotherapy (HDC) with autologous hematopoietic stem cell transplantation (AHSCT) for recurrent and high-risk breast cancer. METHODS: Thirteen patients with recurrent or high-risk breast cancer underwent HDC with AHSCT. Seven cases had relapsed metastasis who had failed in the previous chemotherapy. Two cases had stage IV disease who had received palliative excision. Four cases had stage II or III breast cancer with over 10 positive axillary lymph nodes who had received radical surgical resection. Four cases received autologous bone marrow transplantation, and six received autologous peripheral blood stem cell transplantation. The consolidation regimen was Thiotepa 500 (250-604) mg/m2, Cyclophosphamide 4.9 (3.3-6.0) g/m2. Eight cases were also given Carboplatin 800 (400-800) mg/m2, and two received Etoposide 830 (800-830) mg/m2 instead of Thiotepa in the consolidation regimen. Twelve cases underwent endocrinotherapy after HDC with AHSCT, six operated cases underwent radiotherapy in the area of chest wall and regional lymph nodes after HDC with AHSCT. RESULTS: After a median follow-up of 8(1-47) months, four cases achieved complete remission (CR) and 3 achieved partial remission (PR) in the 7 cases with relapsed metastasis after induction of chemotherapy, PR patients achieved CR after HDC with AHSCT. The disease free survival (DFS) was 1-31 months in these 7 cases. One of two stage IV cases achieved CR and the other had progressive disease (PD) after induction chemotherapy, but the PD patient achieved PR after HDC with AHSCT, they underwent local radiotherapy after HDC with AHSCT and DFS was 5 and 22 months, respectively. The DFS was from 1-47 months in 4 cases with stage II or III disease. CONCLUSION: HDC with AHSCT is a highly potential therapeutic means for recurrent and high-risk breast cancer paitents.

Adult↗