Search PubMed⌕ Search

Biomedical subjects

G Zheng

Publications and source records attributed to G Zheng.

At least 109 records · Page 6Linked to original sources
PubMed1996

Glycoprotein 330/megalin: probable role in receptor-mediated transport of apolipoprotein J alone and in a complex with Alzheimer disease amyloid beta at the blood-brain and blood-cerebrospinal fluid barriers.

A soluble form of Alzheimer disease amyloid beta-protein (sA beta) is transported in the blood and cerebrospinal fluid mainly complexed with apolipoprotein J (apoJ). Using a well-characterized in situ perfused guinea pig brain model, we recently obtained preliminary evidence that apoJ facilitates transport of sA beta (1-40)-apoJ complexes across the blood-brain barrier and the blood-cerebrospinal fluid barrier, but the mechanisms remain poorly understood. In the present study, we examined the transport process in greater detail and investigated the possible role of glycoprotein 330 (gp330)/megalin, a receptor for multiple ligands, including apoJ. High-affinity transport systems with a Km of 0.2 and 0.5 nM were demonstrated for apoJ at the blood-brain barrier and the choroid epithelium in vivo, suggesting a specific receptor-mediated mechanism. The sA beta (1-40)-apoJ complex shared the same transport mechanism and exhibited 2.4- to 10.2-fold higher affinity than apoJ itself. Binding to microvessels, transport into brain parenchyma, and choroidal uptake of both apoJ and sA beta (1-40)-apoJ complexes were markedly inhibited (74-99%) in the presence of a monoclonal antibody to gp330/megalin and were virtually abolished by perfusion with the receptor-associated protein, which blocks binding of all known ligands to gp330. Western blot analysis of cerebral microvessels with the monoclonal antibody to gp330 revealed a protein with a mass identical to that in extracts of kidney membranes enriched with gp330/megalin, but in much lower concentration. The findings suggest that gp330/megalin mediates cellular uptake and transport of apoJ and sA beta (1-40)-apoJ complex at the cerebral vascular endothelium and choroid epithelium.

Amino Acid Sequence↗
PubMed1996

Norepinephrine levels in discrete brain nuclei in borderline hypertensive rats exposed to compound stressors.

The borderline hypertensive rat (BHR) appears to be an appropriate model for investigating the role of the environment in producing hypertension. Previous studies have demonstrated that the BHR shows chronic blood pressure elevations to both stress and high salt intake. Other studies suggest that interactions between the brain and kidney play an important role in initiating this hypertension. The central noradrenergic system has been implicated in these effects, especially in the hypothalamus. Because exercise has been found to attenuate stress-induced hypertension in the BHR, the current study sought to examine the impact of stressors paired with exercise (salt intake or stress) with those combining stress and high salt. Male BHR were exposed to either control, salt plus stress, salt plus exercise, or stress plus exercise conditions for either 2 or 6 months, beginning at 2 months of age. Following sacrifice, brain nuclei in the brain stem and hypothalamus were removed using the Palkovits micropunch technique. Punches were analyzed for NE content via liquid chromatography with electrochemical detection. Compared with the control condition, chronic salt plus stress led to reductions in NE content, especially in the hypothalamus. Compared with salt plus stress, the exercise conditions were associated with elevated NE levels, especially in the early phases of exposure to the treatment. The possible role of exercise training in preventing a central nervous system trigger from inducing hypertension in the BHR is discussed.

Animals↗
PubMed1996

[Observation of the invasion of retinoblastoma cells to ocular tissues in vitro].

PURPOSE: To study the invasion of retinoblastoma cells to ocular tissues. METHODS: The SO-Rb50 cells of retinoblastoma and various ocular tissue cells were co-cultured. The morphological change of the SO-Rb50 cells adherent to ocular tissue cells was observed. RESULTS: SO-Rb50 cells can adhere to the various ocular tissues. The adherent ability of SO-Rb50 cell to different ocular tissue cells was different. Tumor cells could be adhesive to keratocyte, scleral fibrocyte, the fibrocyte and the melanocyte of iris and choroid, the epithelial cells of lens, and the astrocyte of optic nerve and grow, but can not be adhesive to the corneal epithelial cell and retinal pigment epithelial cell. CONCLUSIONS: We consider that the interactions of tumor cells with host cells, as with extracellular matrix, also play an important role in the selective growth of organ and tissue of tumor cell metastasis. Retinoblastoma cells can not adhere to retinal pigment epithelial cell, which may serve as a barrier to obstruct the invasion of tumor cell to the choroid. Being adherent to the glial cells of optic nerve, tumor cells grow in flat and the shape of tumor cell changes, which may be the cause of tumor cell migrate rapidly and grow in the brain while the optic nerve was invaded by tumor cells.

Adult↗
PubMed1996

Induction of Heymann nephritis with a gp330/megalin fusion protein.

There is considerable evidence that glomerular deposits in Heymann nephritis, a rat model of membranous nephritis, result from shedding of immune complexes formed on podocytes and that the principal antigen is part of the extracellular domain of a cell surface glycoprotein receptor called gp330 or megalin. It has also been reported that the immunogen that induces Heymann nephritis is a complex formed between gp330 and the receptor-associated protein RAP. The recent elucidation of the primary structure of gp330 makes it possible to investigate the ability of defined portions of gp330, devoid of RAP, to induce Heymann nephritis. In the present study we show that a gp330-glutathione-S-transferase fusion protein, containing 137 amino acid residues (1114 to 1250) of the ectodomain, induces active Heymann nephritis and that heterologous antibodies against this fusion protein produce passive Heymann nephritis. By immunofluorescence, typical glomerular immunoglobulin deposits were found, but complement components were lacking and the rats did not develop proteinuria. In the active model, we obtained evidence indicating that the deposits contained portions of the ectodomain of gp330, including regions other than those of the fusion protein. Thus, the deposits were stained by polyclonal antibodies to gp330 and to the gp330 fusion protein, as well as by two monoclonal antibodies reactive with portions of the ectodomain of gp330, only one of which reacted with the fusion protein in vitro. Antibodies against the cytoplasmic domain of gp330 did not stain. Furthermore, we found that RAP was able to bind to gp330 in the glomerular deposits but not to the gp330 fusion protein in vitro. The results show that the region of gp330 spanning amino acid residues 1114 to 1250 contains peptides capable of inducing pathogenic antibodies of Heymann nephritis without a contributory role of RAP.

Amino Acids↗
PubMed1996

[Phacoemulsification aspiration and intraocular lens implantation].

OBJECTIVE: To investigate the characteristics of phacoemulsification of cataract in our country and management and prevention of its complications. METHODS: The procedure of phacoemulsification with small incision (6 mm) intraocular lens implantation was improved and was performed on 40 eyes of 40 cases. They had been followed up for 3-6 months postoperatively and their follow-up results were summarized. RESULTS: The uncorrected visual acuity 1.0 or better was in 57.5%, 0.8 or better in 82.5% and 0.5 or better in 97.5%. The postoperative mean astigmatism was 0.50 +/- 0.25 D, which was less than that in the large incision group (9-12 mm) performed on 40 cases in the same period (P < 0.001). Cataract with hard nucleus can be successfully taken out by the technique of peripheral rotation engraving method. CONCLUSION: The operation is a safe reliable one for restoration of visual acuity in patients with cataract, and is superior to extracapsular cataract extraction.

Adult↗
PubMed1995

[An experimental study on homoharringtonine and glaucoma surgery].

PURPOSE: To test the inhibiting effect of a Chinese herbal drug. Homoharringtonine (HH) on the wound healing process at the filtering site in an experimental model. METHODS: Posterior sclerectomies were performed in 20 rabbits. Postoperatively one eye of each rabbit received subconjunctival injections of HH and fellow eye received saline injections in a randomized masked fashion. RESULTS: 14 days after operation, intraocular pressure decreased significantly compared with that of control (P < 0.05). The number of filtration blebs was greater than that of control (14/6). On pathological examination, the number of fibroblasts per square measure of cross section of tissue cut from filtration region that was diminished significantly compared with that of control (P < 0.01). There were no serious and permanent ocular toxic and side effects. CONCLUSIONS: The study suggests that the HH can inhibit cicatrization at the glaucoma filtering site, promote the formation of filtering blebs and provide a sufficient evidence for the further clinical use of HH.

Animals↗
PubMed1994

Organ distribution in rats of two members of the low-density lipoprotein receptor gene family, gp330 and LRP/alpha 2MR, and the receptor-associated protein (RAP).

We investigated immunohistochemically the distribution in rats of the homologous proteins gp330 and the LDL receptor-related protein (LRP/alpha 2MR), and a receptor-associated protein (RAP), and the sites to which soluble exogenous RAP binds. We found gp330 in a restricted group of epithelial cells, including renal proximal tubule cells, podocytes, Type II pneumocytes, cells of the parathyroid, thyroid, epididymis, lining of the uterus, ependyma, retina, ciliary body, yolk sac, and placenta. In these cells gp330 was detected mainly at the cell surface, except for parathyroid and retinal epithelial cells, where diffuse cell staining was found. LRP/alpha 2MR was widely distributed in interstitial cells, notably in fibroblasts and macrophages, and was also present in a selected group of epithelial or specialized cells, including hepatocytes, adrenal cortical cells, follicular cells of the ovary, cells of the choroid plexus, ciliary body, mesangial cells, and some neurons. In certain cells, notably hepatocytes and adrenal cortical cells, LRP/alpha 2MR was detected mainly on the surface, but in others, including macrophages, fibroblasts, and epithelial cells of the choroid plexus and ciliary body, staining throughout the cell was seen. The only cells that clearly expressed both LRP/alpha 2MR and gp330 were retinal and ciliary epithelial cells. RAP was found in intracellular vesicles in all cells that expressed gp330 or LRP/alpha 2MR. RAP was not definitely detected on the cell surface. Binding sites for RAP were found on the surface of those cells with surface gp330 or LRP, and also throughout the cytoplasm in cells with diffuse cellular LRP/alpha 2MR or gp330. Because of their different locations, we conclude that gp330 and LRP/alpha 2MR serve distinct functions in vivo, despite similarities in ligand-binding properties observed in vitro. Since RAP is found largely within cells, its major physiological function may be concerned with intracellular assembly or trafficking of the receptors to which it binds.

Amino Acid Sequence↗
PubMed1994

[Epidemiology and control of hookworm infection in Fujian province].

Fujian province has been known to be endemic for mixed hookworm infection with Ancylostoma duodenale as the predominant species. The infection rate was 50% before 1980. As a result of mass treatment starting from 1980, the infection rate was decreased in most areas. And, infection foci were changed from sweet potato fields to the banana, sweatcane and asparagus fields where the infection rate tended to increase. It is stressed that the current endemic characteristics of hookworm infection should be paid more attention in implementing the control programme of hookworm infection.

Adolescent↗
PubMed1993

Location of gp330/alpha 2-m receptor-associated protein (alpha 2-MRAP) and its binding sites in kidney: distribution of endogenous alpha 2-MRAP is modified by tissue processing.

The alpha 2-macroglobulin receptor-associated protein (alpha 2-MRAP) is a 39 to 44 kDa protein that copurifies with the alpha 2-macroglobulin receptor (alpha 2-MR/LRP) and also with gp330, a highly glycosylated protein located within kidney proximal tubules and glomerular podocytes. Both gp330 and the alpha 2-macroglobulin receptor are members of the low density lipoprotein receptor family but the physiological ligands for gp330 are unknown. In order to understand potential functions of the alpha 2-MRAP, specific anti-alpha 2-MRAP antibodies were used for immunocytochemical studies on paraformaldehyde lysine periodate (PLP)-fixed rat kidneys and on snap-frozen/acetone-fixed tissue. Conflicting results were obtained. After PLP fixation, alpha 2-MRAP was detected almost exclusively in rough endoplasmic reticulum (RER) cisternae; cell surface staining was virtually absent. In snap-frozen tissue, intense staining of the proximal tubule brush border was found, with little or no cytoplasmic staining. A series of experiments showed that during incubation of snap-frozen tissues, endogenous alpha 2-MRAP is released in soluble form from its intracellular location (i.e., the RER) and binds to gp330 on the brush border of proximal tubules. The location of binding sites for alpha 2-MRAP in rat kidney was also examined, using an alpha 2-MRAP-IgG fusion protein. In both snap-frozen and PLP-fixed tissues, this probe bound exclusively to brush borders, and not to intracellular sites. Our results demonstrate: a) that in renal proximal tubule cells, alpha 2-MRAP is located predominantly in the RER, b) that alpha 2-MRAP-binding sites are present on gp330, which is on the proximal tubule brush border, and c) that the apparent brush border localization of alpha 2-MRAP detected in snap-frozen sections is due to an artifactual redistribution of endogenous alpha 2-MRAP that occurs during tissue processing.

Animals↗
PubMed1993

[Analysis on postoperative prognosis in relation to blood ketone body ratios in surgical patients with liver disease].

Eighty-one patients with liver disease were studied for the postoperative changes in the arterial blood ketone body ratio (KBR) and routine liver function tests. The postoperative patients were classified into three groups-according to the postoperative changes in KBR. In the 54 patients of group A, KBR did not decrease to below 0.7, only 2 cases with complications (3.7%); in the 25 patients of group B, KBR decreased transiently to 0.4-0.7 and then increased to over 0.7, 9 cases with complications (36.0%), but they were ameliorated concomitantly with the restoration of KBR; in the 2 cases of group C, KBR decreased irreversibly to below 0.4, and a variety of complications occurred, so the patients finally died of multiple organ failure (MOF). It was found that routine liver function tests were less reliable direct indicators for the onset of postoperative hepatic insufficiency than KBR, which reflected the oxidoreduction state of liver mitochondria.

Adult↗
PubMed1993

Detection of two forms of GP330. Their role in Heymann nephritis.

Heymann nephritis is characterized by glomerular immune deposits that contain a glycoprotein called gp330. The deposits are believed to result from shedding of immune complexes formed on podocytes. Complexes are also shed from proximal tubule cells, when antibodies combine with gp330 on the cell surface. We performed the present study to investigate what portion of the gp330 molecule is shed, using a rabbit antiserum against a peptide deduced to be in the cytoplasmic domain of gp330, as well as a rabbit antiserum and two monoclonal antibodies that recognize extracellular epitopes of gp330. The anti-cytoplasmic peptide antiserum precipitated from Fx1A (a crude renal cortical membrane preparation), a protein with a mass of about 440 kd that was reactive with two monoclonal anti-gp330 antibodies. (In our experiments, the protein called gp330 generally has a mass estimated to be about 440 kd.) The anti-cytoplasmic peptide antiserum also reacted with a truncated gp330 protein produced in transfected COS cells. Immunohistochemical studies showed that all the antibodies recognized the same group of epithelial cells. However, as seen in immunoultrastructural studies of proximal tubules, the anti-cytoplasmic peptide antiserum reacted only with components at the base of microvilli, whereas the anti-gp330 ectodomain antibodies identified material not only at the base, but over the surface of microvilli as well. In rats with Heymann nephritis, glomerular deposits and material shed into tubule lumens reacted with antibodies against extracellular epitopes of gp330, but not with the anti-cytoplasmic peptide antiserum. We propose that there are two forms of gp330 on the cell surface of proximal renal tubules. One form is restricted to coated pit regions at the base of microvilli and has a cytoplasmic domain containing a sequence deduced from a partial complementary DNA encoding gp330. The other form is present over microvilli (and possibly at the base of microvilli as well) and lacks the cytoplasmic domain deduced from the complementary DNA. The complexes that are shed in Heymann nephritis contain either a portion of gp330 cleaved from the full-length molecule or a form of gp330 that lacks the cytoplasmic domain.

Amino Acid Sequence↗
PubMed1992

Quantitation and mapping of integrated human papillomavirus on human metaphase chromosomes using a fluorescence microscope imaging system.

Integrated human papillomavirus type 16 (HPV-16) DNA was directly visualized on metaphase chromosomes in the two human cervical carcinoma cell lines SiHa and CaSki by fluorescence in situ hybridization with a biotinylated DNA probe (7.9 kb). The fluorescence intensities of hybridization signals from single copies and dispersed clusters of integrated HPV-16 DNA were quantified using a microscope equipped with a cooled-CCD camera that was interfaced to an image processor and host computer. Hybridization signals were localized on chromosomes using separate, registered images of 4',6-diamidino-2-phenylindole (DAPI) or propidium iodide stained metaphase chromosome spreads. In both SiHa and CaSki spreads, a single fluorescein signal was observed on one or both chromatids of chromosome 13, which was identified by simultaneous hybridization with a biotinylated centromere probe specific for chromosomes 13 and 21. Ratios of the distance from 13pter to the HPV-16 signals to the entire chromosome length were approximately 0.63 +/- 0.05 in both SiHa and CaSki cells, indicating the possibility of a common integration domain on chromosome 13. In SiHa cells, no additional signals were observed on other chromosomes. This observation, taken together with literature reports that SiHa cells contain 1 to 2 copies of the HPV-16 genome in this region of chromosome 13, suggests that each fluorescein signal on chromosome 13 represents one equivalent of the HPV-16 genome. The total integrated fluorescence intensity in isolated CaSki metaphase chromosome spreads was approximately two orders of magnitude greater than that of a single copy of HPV-16 DNA in SiHa cells, indicating an increase in HPV-16 copy number.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗