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Z Xiao

Publications and source records attributed to Z Xiao.

At least 73 records · Page 4Linked to original sources
PubMed1997

Identification of detergent-resistant plasma membrane microdomains in dictyostelium: enrichment of signal transduction proteins.

Unlike most other cellular proteins, the chemoattractant receptor, cAR1, of Dictyostelium is resistant to extraction by the zwitterionic detergent, CHAPS. We exploited this property to isolate a subcellular fraction highly enriched in cAR1 by flotation of CHAPS lysates of cells in sucrose density gradients. Immunogold electron microscopy studies revealed a homogeneous preparation of membrane bilayer sheets. This preparation, designated CHAPS-insoluble floating fraction (CHIEF), also contained a defined set of 20 other proteins and a single uncharged lipid. Cell surface biotinylation and preembedding immunoelectron microscopy both confirmed the plasma membrane origin of this preparation. The cell surface phosphodiesterase (PDE) and a downstream effector of cAR1, adenylate cyclase (ACA), were specifically localized in these structures, whereas the cell adhesion molecule gp80, most of the major cell surface membrane proteins, cytoskeletal components, the actin-binding integral membrane protein ponticulin, and G-protein alpha- and beta-subunits were absent. Overall, CHIFF represents about 3-5% of cell externally exposed membrane proteins. All of these results indicate that CHIFF is derived from specialized microdomains of the plasma membrane. The method of isolation is analogous to that of caveolae. However, we were unable to detect distinct caveolae-like structures on the cell surface associated with cAR1, which showed a diffuse staining profile. The discovery of CHIFF facilitates the purification of cAR1 and related signaling proteins and the biochemical characterization of receptor-mediated processes such as G-protein activation and desensitization. It also has important implications for the "fluid mosaic" model of the plasma membrane structures.

Animals↗
PubMed1997

Serum uric acid and its correlates in Chinese adult populations, urban and rural, of Beijing. The PRC-USA Collaborative Study in Cardiovascular and Cardiopulmonary Epidemiology.

BACKGROUND: Reports on serum uric acid (SUA) levels in Chinese populations are sparse, but there is evidence that hyperuricaemia and gout are not uncommon. This paper characterizes SUA levels, their correlates, and their relationship to blood pressure (BP) and prevalent high blood pressure (HBP) for urban and rural adult population samples in north China. METHODS: In 1987-1988, a cross-sectional study was carried out, using standardized methods, on men and women aged 40.58 in a Beijing area urban steel mill (N = 2013) and on rural farms (1507). Main outcome measures were SUA, systolic and diastolic blood pressure (SBP, DBP), and prevalent HBP (SBP > or = 140 or DBP > or = 90 mmHg or receiving an antihypertensive drug). RESULTS: Mean SUA levels for men were 5.75 mg/dl in urban and 5.58 mg/dl in rural settings; for women, 4.67 and 4.48 mg/dl. Mean values were higher with age in women, but not in men. Age-standardized prevalence rates of HBP were significantly higher in upper SUA strata (men > or = 7.00, women > or = 6.00 mg/dl) than lower SUA strata both with and without inclusion of those on antihypertensive drugs. Mean SUA levels were correspondingly higher in hypertensive than non-hypertensive people. In multiple regression analyses, body mass index and serum triglycerides were strongly associated with SUA. Also SBP, DBP, and HBP were generally associated with SUA for the whole population sample, with smaller coefficients after excluding those on antihypertensive drugs. However, in these multivariate analyses the strength of the association was low order. CONCLUSION: In addition to its strong association with body mass index, SUA is independently related to serum lipids, particularly triglycerides, and to serum glucose. While some of the univariate relation of SUA to BP is apparently due to the strong relation of body mass to both SUA and BP, a low order significant relation between SUA and BP remains with control for BMI.

Adult↗
PubMed1997

Preclinical assessment of hypocrellin B and hypocrellin B derivatives as sensitizers for photodynamic therapy of cancer: progress update.

Hypocrellins are perylenequinone pigments with substantial absorption in the red spectral region and high singlet oxygen yield. They are available in pure monomeric form and may be derivatized to optimize properties of red light absorption, tissue biodistribution and toxicity. In vitro screening of synthetic derivatives of the naturally occurring compound, hypocrellin B (HB), for optimal properties of cyto-(dark) toxicity and phototoxicity resulted in selection of three compounds for preclinical evaluation: HBEA-R1 (ethanolaminated HB), HBBA-R2 (butylaminated HB) and HBDP-R1 [2-(N,N-dimethylamino)-propylamine-HB]. Extinction coefficients at 630 nm (epsilon 630) are 6230, 6190 and 4800, respectively; and 1O2 quantum yields, phi, 0.60, 0.32 and 0.42. Intracellular uptake is essentially complete within 2 h (HBEA-R1, HBBA-R2) and 20 h (HBDP-R1). Greatest uptake is associated with lysosomes and Golgi. The HBEA-R1 and HBBA-R2 elicit phototoxicity in vitro primarily via the type II mechanism, with some type I activity under stringently hypoxic conditions. Transcutaneous phototherapy with HBEA-R1 permanently ablates EMT6/Ed tumors growing in the flanks of Balb/c mice, with minimal cutaneous effects. The HBBA-R2 does not elicit mutagenic activity in strains TA98 and TA100 of Salmonella typhimurium. Further development of selected hypocrellin derivatives as photosensitizers for photodynamic therapy is warranted.

Animals↗
PubMed1997

[Local administration of drug during tissue expansion].

In order to shorten the expansion time and reduce complications in tissue expansion, we developed a new method using local delivery of drug during tissue expansion. The procedure commenced with placing an implant syringe between the skin and the expander. While the skin was expanded, the drugs such as prednisolone and procaine were injected under the skin from the implant syringe. We have used the method in 23 cases and compared the results with the control group of 11 cases. It was found that the new method shortened the expansion time and reduced complications. The method had definite effect and the manipulation was simple and convenient. We conclude that the method is of value to assist tissue expansion and is worth employing routinely.

Adolescent↗
PubMed1997

[Mineral medicinal material cinnabar in Hunan Province].

Presenting the distribution characteristics and formation types of the mineral medicinal material cinnabar in Hunan Province, this paper expounds in detail the mineralogical features of the material through chemical analysis, X ray diffraction analysis etc.

Conservation of Natural Resources↗
PubMed1997

[Liquid chromatographic separation of pepsinogens].

In this work, we reported a method for the purification of pepsinogens from human gastric mucosa with high pressure gel filtration chromatography (HPLC) and medium pressure anion exchange chromatography (MPLC). First, the two fractions of Pg1 and mixture of PGI and PGII were separated from pepsinogens with HPLC on a Bio-Sil SEC-125 column within 50min. Then the mixture of fractions of PGI and PGII was further separated with MPLC on a Bio-Scale Q2 column within 30min.

Chromatography, High Pressure Liquid↗
PubMed1997

[Experimental study of skin expansion of the grafted free vascularized skin flap].

By using retro-auricular skin after skin expansion to reconstruct auricle, often-times, the retro-auricular skin could not be expanded because of certain reasons such as having burn scar. For this purpose, a new operative technique was designed. The experiment consisted of using 15 rabbits, on one side of the back, a free vascularized skin flap was obtained. Following the anastomosis of the vessels of the flap with that of the back the flap was sutured back in situ. Two weeks after the removal of the sutures, the grafted skin flap was expanded as usual. The routine skin expansion was carried out on the contralateral side as control. The volume of expansion, change of subcutaneous blood vessels, complications from operation, and histological observation were used to compare the results of skin expansion of the two sides. The result showed that there was no significant difference between the types of skin expansion. It was concluded the grafted free vascularized skin flap had no adverse effect on skin expansion.

Animals↗
PubMed1996

Distinct effects of recombinant tenascin-C domains on neuronal cell adhesion, growth cone guidance, and neuronal polarity.

Using a set of recombinantly expressed proteins, distinct domains of the mouse extracellular matrix glycoprotein tenascin-C, hereafter called tenascin, have been identified to confer adhesion, anti-adhesion, and changes in morphology of neuronal cells. In short-term adhesion assays (1 hr), cerebellar and hippocampal neurons adhered to several domains, encompassing the fibronectin type III-like (FN III) repeats 1-2 and 6-8, as well as to the alternatively spliced FN III repeats and to tenascin itself. Although no short-term adhesion to the EGF repeats containing fragment could be detected under the conditions used, it was anti-adhesive for neuronal cell bodies and repellent for growth cone advance and neuritogenesis. FN III repeats 3-5 were repellent only for growth cones but not for neuronal cell bodies. Neurite outgrowth promoting activities at early stages and induction of a polarized neuronal morphology at later stages of differentiation were associated with the EGF repeats and the FN III repeats 6-8. These observations suggest differential effects of particular domains of the tenascin molecule on distinct cellular compartments, i.e., cell body, axon and dendrite, and existence of multiple neuronal receptors with distinct intracellular signaling features.

Animals↗
PubMed1996

[Determination of urea in milk by enzyme coupled electrode method].

An Enzyme coupled electrode method for the determination of urea content in milk was studied systematically. The linear range of the method, the detection limit, recovery and relative standard deviation are 2.1-2.1 x 10(3) micrograms/ml, 2 micrograms/ml, 95.3%-101.0% and 1.5%-3.9%, respectively. The reliability of the method was confirmed by comparison with colorimetry (0.2 < P < 0.05). Using this method, we determined the content of urea in seven milk samples from Chengdu. The values range from 152.2-288.5 micrograms/ml and agree with those reported by other authors. This method is simple, rapid, accurate and inexpensive.

Animals↗
PubMed1995

Constitutive NOS expression in cultured endothelial cells is elevated by fluid shear stress.

The role of chronic fluid shear stress on endothelial constitutive nitric oxide synthase (cNOS) levels may have an important role in vessel diameter control. We subjected primary human umbilical vein endothelial cells (HUVEC) or bovine aortic endothelial cells (BAEC, passages 2-14) to steady laminar shear stress. In both cell types, the intracellular level of cNOS was elevated within 3 h of flow exposure at 25 dyn/cm2 and remained elevated at 6 and 12 h of flow exposure, compared with stationary controls, as indicated by digital immunofluorescence microscopy. Shear stress exposure for 6 h caused a 2.2 +/- 0.3- and 2.8 +/- 0.3-fold elevation of cNOS protein levels in BAEC (n = 3, P < 0.01) and HUVEC (n = 3, P < 0.01), respectively, in the presence or absence of 1 microM dexamethasone. Dexamethasone suppresses induction of the inducible NOS gene, indicating that cNOS was elevated by fluid shear stress. Flow exposure at 4 dyn/cm2 caused no enhancement of cNOS levels in either cell type. The flow induction of the cNOS protein levels was not blocked by preincubation of BAEC with 100-400 microM of NG-nitro-L-arginine methyl ester, indicating that flow-induced NO (or guanosine 3',5'-cyclic monophosphate) was not involved in the elevation of cNOS levels. Protein kinase C inhibitor H-7 (10 microM) had no effect on induction of NOS protein in BAEC exposed to 25 dyn/cm2. The cNOS mRNA levels were found to be elevated by two- to threefold in BAEC after 6 or 12 h of flow exposure at either 4 or 25 dyn/cm2, and this induction of NOS mRNA occurred in the presence of dexamethasone. The elevation of cNOS levels by chronic flow exposure may provide a mechanism for chronic regulation of vessel diameter by endothelial response to prevailing blood flow.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗