Search PubMed⌕ Search

Biomedical subjects

G L Wang

Publications and source records attributed to G L Wang.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Bilateral progressive obliterative retinal vasculitis].

10 cases were reported with a special type of retinal vasculitis which was characterized by progressive obliteration of retinal blood vessels from peripheral retinas to the posterior poles in both eyes. In the late stage of the disease, it was complicated by vitreous hemorrhage in 5 eyes, neovascular glaucoma in 5 eyes, etc. The visual acuities of 10 eyes (50%) were < or = 0.05. It seems that argon laser photocoagulation can delay its natural course. Its fundus changes, fluorescein angiographic findings, differential diagnosis and treatment were discussed.

Adult↗
PubMed1994

[Relation of effects of matrine on rat vasa deferens to activation of calcium channels].

Effective mechanisms of matrine (Mat) in contraction were observed in isolated rat vasa deferens. Mat caused a strong concentration-dependent contraction of vasa deferens, and this contraction was competitively inhibited by prazosin (Pra, 10 mumol.L-1) and nifedipine (Nif, 50 nmol.L-1), with depression of maximal responses. Their pA2 value was 5.1 and 9.29, respectively. The contraction was also inhibited by verapamil (Ver, 1 mumol.L-1) with depression of maximal responses; but this antagonism was noncompetitive. Its pD2 value was 6.07. Mat promoted CaCl2-induced contraction of vas deferens. The effect of Mat was enhanced in proportion to increase in concentrations of CaCl2. Mat markedly strengthened KCl-induced contraction of vas deferens. The results suggest that one of the mechanisms of the contractive effects of Mat within a certain range of concentrations was related to the activation of the calcium channel.

Alkaloids↗
PubMed1993

Desferrioxamine induces erythropoietin gene expression and hypoxia-inducible factor 1 DNA-binding activity: implications for models of hypoxia signal transduction.

Erythropoietin (EPO) gene transcription is activated in kidney cells in vivo and in Hep3B cells exposed to hypoxia or cobalt chloride. Hypoxia-inducible factor 1 (HIF-1) is a nuclear factor that binds to the hypoxia-inducible enhancer of the EPO gene at a site that is required for transcriptional activation. HIF-1 DNA-binding activity is induced by hypoxia or cobalt chloride treatment of Hep3B cells. We report that treatment of Hep3B cells with desferrioxamine (DFX) induced HIF-1 activity and EPO RNA expression with kinetics similar to the induction of HIF-1 by hypoxia or cobalt chloride. Induction by each of these stimuli was inhibited by cycloheximide, indicating a requirement for de novo protein synthesis. DFX appears to induce HIF-1 by chelating iron as induction was inhibited by coadministration of ferrous ammonium sulfate. DFX administration to mice transiently increased EPO RNA levels in the kidney. As previously shown for hypoxia and cobalt treatment, DFX also induced HIF-1 activity in non-EPO-producing cells, suggesting the existence of a common hypoxia signal-transduction pathway leading to HIF-1 induction in different cell types.

Base Sequence↗
PubMed1993

An AP-1 binding site in the upstream region of Deb-A is part of a developmentally regulated negative element.

The Deb-A gene from Drosophila melanogaster encodes a small membrane-associated protein, regulated during development, with peak abundance at 12-15 h of embryogenesis. The cis-acting regulatory elements that control expression of Deb-A during embryogenesis were localized using a somatic transformation assay. The Adh gene of D. melanogaster was used as a 'reporter' gene. The promoterless ADH coding sequence was fused to the 5'-upstream control region of Deb-A. Deletions were introduced into the 5'-region using various restriction sites and Bal31 deletion mutagenesis. A negative regulatory element, or silencer, was localized to a segment 47 base pairs long, between -395 and -442. It is responsible for 80% of the repression of gene expression during late development and reduces levels of Deb-A RNA nearly 5-fold. This negative element is temporally functional. It becomes active after 15 h of embryogenesis and it has no effect on gene expression prior to that. Within this negative element of 47 base pairs, two footprint regions were protected from DNase I digestion by embryonic nuclear extracts: one region contains an AP-1 binding site, but the other footprint is due to unknown element(s). High molecular weight DNA-protein complexes on an oligonucleotide probe spanning the AP-1 binding site were identified in gel retardation assays using partially purified bacterially expressed Djun protein or nuclear extracts from Drosophila embryos. These data suggest that the AP-1 site may be partly responsible for decreasing Deb-A expression during the late embryonic developmental stages of D. melanogaster.

Amino Acid Sequence↗
PubMed1993

Characterization of hypoxia-inducible factor 1 and regulation of DNA binding activity by hypoxia.

Hypoxia-inducible factor 1 (HIF-1) is a DNA binding activity detected in nuclear extracts from Hep3B cells cultured in 1% O2 but not in extracts from cells cultured in 20% O2. HIF-1 binds to a sequence within the human erythropoietin gene enhancer that is required for hypoxic activation of transcription. Induction of HIF-1 is inhibited by cycloheximide, which also inhibits induction of erythropoietin RNA. We now demonstrate that induction of both HIF-1 and erythropoietin RNA is inhibited by the protein kinase inhibitor 2-aminopurine. HIF-1 binding to DNA was eliminated by phosphatase treatment of nuclear extracts. Actinomycin D also inhibited HIF-1 induction, suggesting that de novo transcription is required. The kinetics of HIF-1 induction by hypoxia paralleled the kinetics of erythropoietin gene transcriptional induction. HIF-1 DNA binding activity decayed rapidly when hypoxic cells were exposed to increased oxygen tension. In vitro, the kinetics of HIF-1 association with, and dissociation from, its binding site were extremely rapid, with a t1/2 for both processes of < 1 min. These findings are consistent with the proposed function of HIF-1 as a physiologic regulator of gene expression that responds to changes in cellular oxygen tension. Methylation interference analysis indicated that HIF-1 makes specific contacts with DNA in the major groove.

2-Aminopurine↗
PubMed1993

General involvement of hypoxia-inducible factor 1 in transcriptional response to hypoxia.

Transcription of the human erythropoietin (EPO) gene is activated in Hep3B cells exposed to hypoxia. Hypoxia-inducible factor 1 (HIF-1) is a nuclear factor whose DNA binding activity is induced by hypoxia in Hep3B cells, and HIF-1 binds at a site in the EPO gene enhancer that is required for hypoxic activation of transcription. In this paper, we demonstrate that HIF-1 DNA binding activity is also induced by hypoxia in a variety of mammalian cell lines in which the EPO gene is not transcribed. The composition of the HIF-1 DNA binding complex and its isolated DNA binding subunit and the mechanism of HIF-1 activation appear to be similar or identical in EPO-producing and non-EPO-producing cells. Transcription of reporter genes containing the EPO gene enhancer is induced by hypoxia in non-EPO-producing cells and mutations that eliminate HIF-1 binding eliminate inducibility. These results provide evidence that HIF-1 and its recognition sequence are common components of a general mammalian cellular response to hypoxia.

Animals↗
PubMed1992

A nuclear factor induced by hypoxia via de novo protein synthesis binds to the human erythropoietin gene enhancer at a site required for transcriptional activation.

We have identified a 50-nucleotide enhancer from the human erythropoietin gene 3'-flanking sequence which can mediate a sevenfold transcriptional induction in response to hypoxia when cloned 3' to a simian virus 40 promoter-chloramphenicol acetyltransferase reporter gene and transiently expressed in Hep3B cells. Nucleotides (nt) 1 to 33 of this sequence mediate sevenfold induction of reporter gene expression when present in two tandem copies compared with threefold induction when present in a single copy, suggesting that nt 34 to 50 bind a factor which amplifies the induction signal. DNase I footprinting demonstrated binding of a constitutive nuclear factor to nt 26 to 48. Mutagenesis studies revealed that nt 4 to 12 and 19 to 23 are essential for induction, as substitutions at either site eliminated hypoxia-induced expression. Electrophoretic mobility shift assays identified a nuclear factor which bound to a probe spanning nt 1 to 18 but not to a probe containing a mutation which eliminated enhancer function. Factor binding was induced by hypoxia, and its induction was sensitive to cycloheximide treatment. We have thus defined a functionally tripartite, 50-nt hypoxia-inducible enhancer which binds several nuclear factors, one of which is induced by hypoxia via de novo protein synthesis.

Base Sequence↗
PubMed1992

Ultrastructural study on extrahepatic infection of duck hepatitis B virus in ducks.

Kidney and pancreas tissues from congenitally infected Ma ducks with duck hepatitis B virus (DHBV) were examined by immunohistochemical staining technique and electron microscopy. The immunostaining showed that DHBV antigen was localized in the cytoplasm of tubular epithelial cells of kidney and acinar cells of pancreas of infected ducks. Under electron microscope, we found that complete and incomplete DHBV particles existed in the dilated cisternae of rough endoplasmic reticulum of both the cells. The size of complete and incomplete virus particles was nearly uniform in both the cells, 50-65 nm and 40-50 nm in diameter respectively. Therefore, extrahepatic infection and replication of DHBV were directly demonstrated ultrastructurally.

Animals↗
PubMed1992

[A study of the effect of fish oils on the risk factors of cardiovascular and cerebrovascular diseases].

In this study 22 normotensive (NT) and 12 essential hypertensive (EHT) subjects were included to test the possibility that fish oils might influence the blood pressure, plasma lipids and fibrinogen as well as the erythrocytic membrane lipid composition and pump activity. Each EHT subject was given capsules containing fish oils (6 g/d) for 18 days. At the end of the study, SBP fell (P < 0.05) and plasma fibrinogen level decreased (P < 0.05), while DBP, TG, TC, and HDL-C showed no significant change. The fatty acid composition of erythrocyte phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) showed the following changes: in PE, C22:6, C20:5 increased (P < 0.05; P < 0.01), CI18:1 decreased (P < 0.01); in PC C22:6, C22:4 increased (P < 0.05; P < 0.01). The activity of Na+, Ca2+ max, CaM-stimulated Ca2+ pumps increased (P < 0.05; P < 0.01; P < 0.01). As compared to NT, EHT subjects had higher C20:4 in both PE (P < 0.05) and PC (P < 0.01) and lower C18:2 in PC. It is also shown in this study that EHT subjects have higher C20:4 in both PE (P < 0.05) and PC (P < 0.01) and lower C18:2 in PC as compared to NT ones.

Adult↗
PubMed1992

[Preliminary report of the treatment of luteal phase defect by replenishing kidney. An analysis of 53 cases].

53 patients with Luteal phase defect (LPD) were treated with different Chinese medicinal herbs at different phases of menstrual cycle. On the 5th day of the menstrual cycle, the treatment was implemented with the rationale of "nourishing the Kidney Yin, invigorating the Spleen and replenishing the Qi, promoting the blood circulation and enriching the Blood" which might promote follicular development. The principle for the postovulatory treatment was that "invigorating the Kidney and strengthening the Yang" might enhance the development of corpus luteum and maintain its function. The patients were treated for three menstrual cycles. There were significant improvement in the luteal phase of endometrium, and prolonged basal body temperature elevation in progestational stage with a tendency for normalization of the wave forms and its amplitude after the treatment. In the mid-progestational stage, the level of serum LH and PRL were reduced (P < 0.05) and that of serum progestin (P) rose significantly (P < 0.01), as compared with those before the treatment. The findings suggested that Chinese herbal medicines capable of replenishing the Kidney could regulate the hypothalamus-pituitary-ovarian axis and thus improve the luteal function. Among the 53 cases, 22 (41.5%) conceived but 68.18% of them required other measures to preserve the pregnancy.

Adult↗
PubMed1991

Effects of thyrotropin-releasing hormone on acute experimental traumatic head injury in cats.

The effects of thyrotropin-releasing hormone (TRH) on early acute traumatic head injury in cats were evaluated by continuous intravenous infusion of TRH (2 mg/kg/h) or saline (2 ml/kg/h) for four hours, beginning one hour after injury. The results showed that TRH, administered intravenously, significantly increased the mean arterial pressure and cerebral perfusion pressure, decreased intracranial pressure, alleviated brain edema, and reduced the mortality rate. These effects promoted the recovery of neurologic function following traumatic head injury. Because of the significant central action and the ability to antagonize many pathophysiological effects of endogenous opioids or exogenous opiates except their analgesic effects, TRH and its analogues have broad prospects in the treatment of patients with CNS injuries or shock.

Animals↗
PubMed1991

[Combined surgery for complicated retinal detachment].

During 1986-1989, the authors treated 23 cases of complicated retinal detachment with vitrectomy in combination with reattachment surgery and intraocular injection of C3F8 gas. The PVR gradings were C1, 3 cases; C2, 7 cases; C3, 8 cases; D1, 4 cases; and D2, 1 case. Retinal breaks occurred in 16 cases, in whom the rate of surgical success was 65.2%. The visual acuity improved in 66.6% of the cases after operation. The advantages, the actual procedures and the causes of failure of the combined surgery were discussed.

Adolescent↗
PubMed1991

[Treatment of choroidal hemangioma].

Eight (8) cases of choroidal hemangioma, comprising 6 of the solitary type and 2 of the diffuse type, were treated with Argon laser, including 2 cases in combination with cryotherapy. The success rate was 76.5%, with visual acuity improved in 75% of them during an average follow-up of 11.7 months. Tumors with much subretinal fluid were first given cryosurgery before Argon laser treatment for good synergic therapeutic effects.

Adolescent↗
PubMed1991

Changes of immunoreactive TRH in cerebrospinal fluid and plasma after acute head injury and its clinical significance.

Using radioimmunoassay (RIA) concentrations of immunoreactive TRH (TRH-ir) in cerebrospinal fluid (CSF) and plasma were determined after acute head injury in 29 patients. The results showed that the concentrations of TRH-ir (pmol/L) in CSF and plasma on the days when injuries were sustained were 29.25 +/- 8.92 pg/ml and 30.29 +/- 8.26 (1 pg/ml = 2.8 pmol/L) in mildly (n = 12), 57.78 +/- 11.72 and 65.27 +/- 8.57 in moderately (n = 9), and 70.09 +/- 7.58 and 85.65 +/- 7.92 in severely (n = 8), head-injured patients. While the concentrations of TRH-ir in CSF and plasma were 25.11 +/- 11.85 and 27.90 +/- 11.39 in the control group (n = 10). Dynamic observations revealed that the contents of TRH-ir in CSF and plasma were gradually recovered to their control levels when improvement of the head-injured patients took place. But they were significantly decreased and became much lower than the control levels in patients with poor prognosis. These results suggest that the assay of TRH-ir in CSF and plasma has clinical significance in reflecting the severity and prognosis of acute head-injured patients.

Adolescent↗
PubMed1990

[Vitrectomy for non-diabetic vitreous hemorrhage].

45 cases (52 eyes) of non-diabetic vitreous hemorrhage, including 21 cases of Eales' disease, 20 cases of retinal venous obstruction, 4 cases of SMD etc. had visual acuities of 0.05 or less, except 1 eye of 0.4. After pars plana vitrectomy, some in combination with scleral encircling, vision in 62.7% of the eyes reached 0.1 or over, while 80.7% showed improvement. The points of note during operation, the proper timing of the surgery and complications were discussed.

Adolescent↗
PubMed1990

Ultrastructural study of hepatitis B virus in biliary epithelial cells of duck liver.

Liver specimens from the Shanghai Ma ducks congenitally infected with duck hepatitis B virus (DHBV) were examined by immunohistochemical technique and electron microscopy. All the 12 serum DHBV positive ducks showed varying degrees of positive straining in hepatocytes. In 8 of the 12 ducks, DHBV antigen was discovered in the cytoplasm of biliary epithelial cells. Conventional electron microscopy revealed two kinds of virus particles in the biliary epithelial cells: 1. the incomplete virus, 40-50 nm in diameter and spherical in shape with an outer membrane, located mainly in the dilated cisternae of rough endoplasmic reticulum of the cells in large amounts; 2. the complete virions, 55-60 nm in diameter, were spherical with an outer membrane and located mainly in the cytoplasmic vesicles in small amount. We believe the particles found in the biliary epithelial cells in this study were DHBV particles. It is most likely that the infection and replication of DHBV not only take place in the liver cells but also in the biliary epithelial cells.

Animals↗