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Biomedical subjects

Z X Yao

Publications and source records attributed to Z X Yao.

11 recordsLinked to original sources
PubMed2001

Identification, localization, and function in steroidogenesis of PAP7: a peripheral-type benzodiazepine receptor- and PKA (RIalpha)-associated protein.

Peptide hormones and cAMP acutely stimulate steroid biosynthesis by accelerating the transport of cholesterol into the mitochondria. The peripheral-type benzodiazepine receptor (PBR) has been shown to be an indispensable element of the cholesterol transport machinery. Using the yeast two-hybrid system and PBR as bait, we identified a protein that interacts with PBR, the PBR-associated protein PAP7. Using the regulatory subunit RIalpha of PKA as bait, we also isolated PAP7. Glutathione-S-transferase -PAP7 interacted with both the mitochondrial PBR and cytosolic PKA-RIalpha in MA-10 Leydig cells. PAP7 is a novel 52-kDa protein present in mouse, rat, and human tissues, and it has a major 3-kb mRNA transcript in all tissues examined. Immunohistochemical and in situ hybridization studies indicated that PAP7 is highly expressed in the gonads, adrenal, hippocampus, and distinct brain neuronal and glial populations. Overexpression of the full length PAP7 increased the hCG-induced steroid production. However, overexpression of a partial PAP7, which includes the PBR- and PKA-RIalpha-binding domains, inhibited the hormone-stimulated cholesterol transport and steroid synthesis. Treatment of MA-10 cells with oligonucleotides antisense to PAP7 also inhibited the hCG-stimulated steroid formation, suggesting that PAP7 is a functional element of the hormone-induced signal transduction cascade leading to steroidogenesis. PAP7 may function by targeting the PKA isoenzyme to organelles rich in PBR, i.e. mitochondria, where phosphorylation of specific protein substrates may induce the reorganization of PBR topography and function.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Free radicals and lipid peroxidation do not mediate beta-amyloid-induced neuronal cell death.

"beta Amyloid (Abeta)-induced free radical-mediated neurotoxicity" is a leading hypothesis as a cause of Alzheimer's disease (AD). Abeta increased free radical production and lipid peroxidation in PC12 nerve cells, leading to increased 4-hydroxy-2-nonenal (HNE) production and modification of specific mitochondrial target proteins, apoptosis and cell death. Pretreatment of the cells with isolated ginkgolides, the anti-oxidant component of Ginkgo biloba leaves, or vitamin E, prevented the Abeta-induced increase of reactive oxygen species (ROS). Ginkgolides, but not vitamin E, inhibited the Abeta-induced HNE modification of mitochondrial proteins. However, treatment with these anti-oxidants did not rescue the cells from Abeta-induced apoptosis and cell death. These results indicate that free radicals and lipid peroxidation may not mediate Abeta-induced neurotoxicity.

Aldehydes↗
PubMed1998

[The biological characteristics of endothelial cells of human umbilical vein and the mechanism of intracellular signal transduction].

We observed the synthesis and release of vasoactive polypeptides (VPs) in the endothelial cells of human umbilical blood vessels (HUVEC). The results showed: (1) The content of VPs in the endothelial cells of non-innervated human umbilical vessels is higher than that of mesenteric vessels. (2) These VPs are synthesized by endothelial cells and released into the outside of cell bodies. (3) VIP and SP can stimulate the proliferation of HUVEC, but somatostatin (SOM) inhibits it. (4) VIP and SP increase opening probability of the Ca2+ channel in the membrane of HUVEC, while SOM decrease it, but VIP, SP and SOM result in the increase of concentrations of intracytosolic free Ca2+ and cAMP, while decreasing that of cGMP in HUVEC. In conclusion, we proved that there are local regulatory mechanisms in non-innervated human umbilical blood vessels, and VPs within endothelial cells may play an important role.

Calcium↗
PubMed1994

Purification and characterization of DNA methylase from HL-60 cells.

A solid leukemia sarcoma has been successfully developed after subcutaneous inoculation of the cultured human promyelocytic leukemia cells (HL-60 cells) into nude mice. The solid leukemia sarcoma is a more plentiful source than the cultured cells for enzymatic study and its growing environment is closer to that of the human body than the cultured cells. We established an efficient procedure of purifying HL-60 cells DNA methylase which includes: disruption of HL-60 cells by homogenization and sonication, removing the cell fragments and cellular particles by centrifuge and ultracentrifuge (105,000 g); removing endogenous DNA by streptomycin sulfate, salting out by (NH4)2SO4, ion exchange chromatography on DEAE-cellulose (DE-52), gel filtration over Sephadex G-100 column. The DNA methylase from HL-60 cells has been purified 204 fold by this procedure. The purified enzyme shows a single-band on PG-PAGE. A 479-kD molecular weight of this enzyme is measured by PG-PAGE. The enzyme properties of HL-60 DNA methylase are also studied.

Animals↗
PubMed1991

[Fetal breast estrogen receptor (ER) and breast cancer].

The estrogen receptor in bilateral breasts of 36 6 to 10-month fetuses (17 male, 19 female) were examined. All fetal breasts had ER positive cells (greater than 50-90%). The ER levels were similar regardless of sex and age. When the ER status of 84 female breast cancer patients was analysed, ER was considered as an essential but not the only etiologic factor in mammary carcinogenesis. A positive correlation between the degree of differentiation and the ER level of breast cancer cells was demonstrated and the ER level did not correlate with the clinical staging of breast cancer. The results are briefly discussed in relation to the rationale of hormonal therapy of breast cancer.

Breast↗
PubMed1990

[Studies on constituents of ganoderma capense IV. The chemical structures of ganoine, ganodine and ganoderpurine].

Two novel pyrrole alkaloids--ganoine and ganodine and a novel purine alkaloid ganoderpurine have been isolated from the mycelium of Ganoderma capense (Lloyd)Teng (Polyporaceae) obtained by submerged fermentation. On the basis of spectroscopic data their structures were elucidated, ganoine is N-isopentyl-5-hydroxymethyl-pyrryl alldehyde. Ganodine is N-phenylethyl-5-hydroxymethyl-pyrryl aldehyde and ganoderpurine is N9-(alpha, alpha dimethyl-gamma-oxobutyl) adenine.

Adenine↗
PubMed1989

[Diagnostic criteria and their relation to prognosis in acute pancreatitis].

Investigations were carried out in 1041 consecutive patients of acute pancreatitis, to correlate the prognosis with their symptoms and signs. It has been found that there were 15 symptoms and signs may be related to their prognosis; that is age over 60, high intake of fatty food immediately before attack, severe upper abdominal pain with vomiting, pulse rate over 100/min, pulse pressure below 2.6 kPa, peritoneal irritation, absence of peristaltic sounds, bloody ascites, serum electrolytes disorder, acidosis, more than 4000 ml of fluid were needed in first 24 h, serum calcium level below 1.9 mmol/L, blood glucose over 8.3 mmol/L, BUN over 7.0 mmol/L, and poor liver functions. If there are less than 4 positive signs, edematous pancreatitis may be present, 5 to 8 positive signs may be necrotizing pancreatitis with high risk of mortality and early operation is indicated, and more than 8 positive signs the prognosis will be very poor.

Acute Disease↗
PubMed1985

Artificial encapsulation of joint prostheses.

The great success of total joint replacement in surgery has been disturbed mainly by later loosening and wear-out of the plastic components. In an attempt to improve long term performance of joint prostheses and eliminate the adverse effects of wear debris, polymeric encapsulation as a main design feature has been proposed. The benefits of having an encapsulated and artificially lubricated joint prosthesis have been evaluated in tribological terms with particular reference to the UMIST shoulder joint. The selection of a number of biopolymers involved in this research project described. The possible interactions arising from the coexistence of these materials have been mechanically investigated. Much attention and a great deal of practical work has been focussed on the sealing of the capsule and on the relevant liquid permeability.

Humans↗
PubMed1983

Clinical and histological observations on the application of intermingled auto- and porcine-skin heterografts in third degree burns.

Escharectomy and skin grafting with both homograft and porcine skin has become an effective method in treating massive third degree burns. Seventeen patients and 21 operations of intermingled transplantation of auto- and fresh porcine skin heterografts after escharectomy of the severe burn wounds have been carried out since March 1973. Clinical and histological data are summarized, among which we observed the 'fusing phenomena' of auto- and porcine skin heterografts in 6 patients. Vascularization, 'turning red', viability and rejection as well as ways to improve the results of the grafting method are discussed. No vascular communication between fresh porcine skin and the host wound has been observed during the early postoperative period. The cause of 'turning red' is a reddish transudation between the graft and the host wound seen through the thin porcine skin. Based on histological observations, porcine skin is viable after transplantation. With nutritional support apparently coming from the underlying plasma and tissue fluid. Eventually the process of rejection is similar to that of homograft Better results are found with porcine skin grafts 0.4-0.5 mm in thickness placed 0.5-0.75 cm apart. In order to avoid large sloughing wound surfaces less than 20 per cent area of porcine skin coverage is advisable.

Adolescent↗