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Y Xu

Publications and source records attributed to Y Xu.

At least 1,027 records · Page 57Linked to original sources
PubMed1995

Calcium pyrophosphate dihydrate (CPPD) crystal dissolution by alkaline phosphatase: interaction of alkaline phosphatase on CPPD crystals.

OBJECTIVE: As alkaline phosphatase (ALP) can dissolve calcium pyrophosphate dihydrate (CPPD) crystals, and as dissolution is facilitated when the enzyme is proximate to the crystals, we studied the mechanism of ALP interaction with CPPD crystals in vitro. METHODS: ALP was incubated with CPPD crystals in an in vitro model system. Fluorescein isothiocyanate conjugated alkaline phosphatase (FITC-ALP), alkaline phosphatase product staining of calcium pyrophosphate dihydrate (CPPD) crystals and scanning electron microscopy were used to visualize ALP-CPPD crystal interactions. RESULTS: ALP preferentially binds to the small end faces (optical 010 faces) of CPPD crystals. Etch pits indicative of dissolution were demonstrated coexistent with ALP crystal binding and ALP pyrophosphohydrolytic activity. CONCLUSION: ALP binding to CPPD crystals is preferential for the smallest end faces (optical 010 faces). As ALP crystal binding is altered by ions but not by heat inactivation of ALP, ALP-CPPD crystal binding is considered a nonenzymatic mechanism distinct from ALP pyrophosphohydrolytic activity. Our study demonstrates that ALP binds and dissolves CPPD crystals in a stereoselective manner. This suggests that the CPPD crystal dissolution rate is limited by the availability of surface area on the crystal faces most susceptible to ALP binding.

Alkaline Phosphatase↗
PubMed1995

[Clinical observation of labor of induction with nutritional food].

386 pregnant women in 3rd trimester having indications of induction labor were induced with nutritional food. The success rate was 77.92% (301/386) and correlated with the cervical Bishop score. Furthermore the success rate increased significantly in term with premature rupture of the membrane (90.54%). This method, which was found to be safe and effective can significantly shorten the first and total stage of labor.

Adult↗
PubMed1995

[Effects of tetrandrine on cardiac hemodynamics of hypertrophied left ventricle from deoxycorticosterone-salt hypertensive rats].

Effects of tetrandrine (Tet) on cardiac mass and hemodynamic parameters were studied in deoxycorticosterone-salt (DOCA-salt) hypertensive rats. Treatment with Tet (50 mg.kg-1, qd x 9 wk) markedly lowered systolic blood pressure and left ventricular (LV) weight. Study on isolated working heart demonstrated that the Tet group compared with the LVH group, AP, LVSP, +/- dp/dtmax, LVDP, coronary blood flow and cardiac output were increased while LVEDP and T were decreased. Studies on LV pressure-volume relation showed that Tet can markedly improve the LV compliance and the LV stiffness constant of LVH rat. These findings suggest that the regression of LVH in DOCA-salt hypertensive rats with Tet is associated with improvement of the contraction, relaxation and pump function, especially relaxation function and hemodynamics.

Alkaloids↗
PubMed1995

Beneficial effects of NTG on left ventricular volumes and systolic function in patients with myocardial infarction.

The effect of sublingual administration and intravenous drip of nitroglycerin (SLNTG and IVNTG) on left ventricular volumes (LVVs) were studied and systolic function was quantitatively assessed with two-dimensional echocardiography (2DE) in 28 patients with myocardial infarction (MI), including 13 cases without heart failure (MI-NHF) in one group and 15 with heart failure (MI-HF) in another. The results showed that after SLNTG and IVNTG in both groups the heart rate (HR) increased significantly (P < 0.05-0.001); the systolic blood pressure (SBP) decreased significantly (P < 0.05-0.001); the diastolic blood pressure (DBP) was not significantly changed (all P > 0.05); the left ventricular end-diastolic and end-systolic volumes (EDV and ESV) both significantly reduced [EDV: decreased by 5.8-11.6% (-13.2-19.0 ml), P < 0.05-0.001; ESV: decreased by 9.6-16.6% (-8.6-17.3 ml), P < 0.05-0.001)]; the left ventricular ejection fraction (LVEF) all significantly elevated (increased by 6.6%-9.4% (3.2%-3.4%), P < 0.05-0.001] except in MI-NHF group after IVNTG; the segmental EF of normal and hypokinetic segments also significantly increased (P < 0.05-0.001). The results suggest that NTG could beneficially reduce left ventricular EDV and ESV; and improve or strengthen its global and segmental systolic function in MI patients, particularly noticeable in patients with heart failure.

Blood Pressure↗
PubMed1995

Constitutive expression and modulation of the functional thrombin receptor in the human kidney.

Thrombin exerts procoagulant effects and has also many cellular effects mediated by cell surface receptors. A functional thrombin receptor from human platelets has been cloned and sequenced. In the present study, by reverse transcription and polymerase chain reaction, using specific primers designed from the thrombin receptor cDNA sequence, we show that the mRNA encoding for this receptor can be amplified from freshly isolated human glomeruli obtained by microdissection of normal kidney cortex. By immunohistochemistry using a specific monoclonal antibody, ATAP2, directed against the extracellular N-terminus of this receptor, we find that this functional thrombin receptor is constitutively expressed in the normal human kidney. The three glomerular cell types, endothelial, mesangial, and epithelial cells, were positively stained, as were the endothelial cells of renal arteries, arterioles, venules, and peritubular capillaries. Occasionally, interstitial cells and smooth muscle cells in the media of renal arteries were also stained. Proximal and distal tubular cells were not stained. By in situ hybridization, using a digoxigenin-labeled cDNA probe specific for thrombin receptor, the thrombin receptor mRNA was found to have the same distribution as the thrombin receptor protein detected by immunohistochemistry. A lighter staining of glomerular endocapillary cells was observed in cases of thrombotic microangiopathy and extracapillary glomerulonephritis, two renal diseases associated with in situ thrombin generation and fibrin formation. In one case of thrombotic microangiopathy, we observed an increase in thrombin receptor mRNA. This suggests that thrombin receptor protein is not always correlated with thrombin receptor mRNA level. Internalization and degradation of thrombin receptor protein have been demonstrated in vitro and could also occur after activation in vivo. This is the first demonstration of the constitutive expression of the functional thrombin receptor in the human kidney. These results suggest that thrombin may exert glomerular and vascular effects within the kidney in normal and in pathological conditions.

Amino Acid Sequence↗
PubMed1995

The crystal structure of deshexapeptide (B25-B30) insulin at 0.25 nm resolution.

The determination of deshexapeptide (B25-B30) insulin (DHI) was divided into two steps. At the first step, the rough structure model of DHI molecule was determined by using the molecular replacement method associated with the molecular close-packing method at 0.30 nm resolution based on the reflection data collected on four-cycle diffractometer. At the second step, the DHI model was adjusted and refined at 0.25 nm resolution based on the data collected on Area Detector. 40 water molecules were determined during the refinement, the final R-factor is 0.185 with R.M.S. deviation of 0.002 nm for bond lengths and 1.9 degrees for bond angles. The differences in conformation and function of DHI with other insulin analogues were compared and discussed.

Insulin↗
PubMed1995

Radiologic manifestations of osteopetrosis.

The clinical radiologic manifestations of 8 patients with osteopetrosis (4 males and 4 females) are analyzed. Six of the cases are benign. The pathologic basis for the radiologic manifestations is discussed, and a classification is suggested. "Broom-like" metaphyses, metaphyses containing three or four dense layers of bone, and ossification of soft tissues around joints were found and differential diagnosis was made.

Adolescent↗
PubMed1995

[Effects of some physical and chemical factors on both human hair DNA and results of sex determination by PCR].

The present study aims at observation of the effects of some physical and chemical factors on both human hair DNA and the results of sex determination by PCR. After the hairs were treated with varying pH solutions, the quantity of the DNA extracted was decreased. High-molecular-weight (HMW) DNA was determined in the hairs treated with pH 1, 3, 5 and 7 solutions for 2 hours, but no DNA was demonstrated by agarose gel electrophoresis in the hairs treated with pH 1 and 3 solution for 24 hours, and the quantity of DNA was decreased in the hairs treated with pH 5 for 24 hours. The quantity of DNA was decreased in the hairs treated with pH 9 for 2 hours and no DNA was demonstrated for 24 hours. No DNA was found in the hairs treated with pH 11 for 2 or 24 hours. No changes of DNA were observed in hairs treated with 75% ethanol or methanol for 2 or 24 hours and exposed to UV light for 24 hours. No DNA but RNA was observed in the hairs treated with 10% formalin (pH 7 or pH 5) for 2 or 24 hours. The quantity of DNA was decreased obviously in the hairs treated in 100 degrees C water for 5 or 10 minutes. The quantity of DNA was not decreased in the hairs heated at 50 degrees C for 24 hours, and only little decrease was noted at 100 degrees C for 24 hours. Both fragments of PCR products were obtained in most hairs except the hairs treated with pH 11 solution for 24 hours. Although no DNA was observed in some treated hairs, specific bands were detected after PCR. PCR is a very sensitive and specific technique of DNA amplification, which can be used for sex determination in forensic medicine.

Base Sequence↗
PubMed1995

[Significance of immunohistochemical study in the diagnosis and differential diagnosis of chordoma].

Seven cases of chordoma were studied immunohisto-chemically with antibodies directed to epithelium, nerve, mesenchyme, muscle and histiocyte. Six cases of chondrosarcoma and three cases of mucinous carcinoma of colon were studied as control. The results showed that the chordomas were positive for cyto-K 6/7, EMA 7/7, CEA 6/7, Vim 7/7, S-100 7/7, alpha-AT 7/7, Lyso 4/7, while negative for GFAP and Des in all 7 cases indicating that chordoma, just like notochord, had the potentiality of multidirectional differentiation. In contrast, none of the chondrosarcomas was positive for cyto-K, EMA or CEA, but positive for Vim and S-100 in 6 cases. Three cases of colon mucinous carcinoma were positive for epithelial antibodies, but none reacted with other antibodies. Thus, immunohistochemical studies are of help in the diagnosis and differential diagnosis of chordoma.

Adenocarcinoma, Mucinous↗
PubMed1995

[Left ventricular diastolic dysfunction in patients with angina decubitus].

Our study population consisted of three groups: 1. 24 cases with ejection fraction (EF) > 45% in 26 patients with angina decubitus (AD) were studied as group A. 2. 20 patients had coronary artery disease without AD as group B. Group B and A were matched for age, EF and coronary artery obstructive lesions. 3. 20 cases without cardiovascular diseases as group C. Left ventriculography (LVG) was performed in these patients. The results showed that left ventricular (LV) early 1/3 filling fraction (1/3FF) was significantly reduced in group A as compared with that in group B and C (both P < 0.001). The findings suggest that patients with AD have abnormalities of LV diastolic filling. Left ventricular end diastolic pressure (LVEDP) significantly increased in patients with AD after LVG as compared with before LVG (P < 0.01). However, there was no statistically difference in LVEDP before and after LVG in both group B and C, indicating that the compliance of LV was also decreased in patients with AD. The increase of LV volume after recumbency would cause increase of LV wall tension and myocardial contraction and aggravate the LV diastolic dysfunction, resulting in a progressive increase in myocardial oxygen consumption. Therefore, we consider that on the basis of severe coronary artery obstructive lesions, LV diastolic dysfunction is a significant pathologic factor in the pathogenesis of AD.

Adult↗
PubMed1995

Rapid non-empirical approaches for estimating relative binding free energies.

Rapid non-empirical methods for estimating binding free energies are reviewed. A novel approach based on the application of the free energy perturbation formula to a biased ensemble is presented. Preliminary results demonstrating the applicability of this approach in protein systems are shown and the potential of this method in structure-based drug design is discussed.

Models, Theoretical↗
PubMed1995

Elimination of human leukemia by monoclonal antibodies in an athymic nude mouse leukemia model.

A human acute myeloid leukemia model has been developed by i.v. transplantation of HL-60 myeloid leukemia cells into Swiss nude mice pretreated with cyclophosphamide. HL-60 cells disseminated into hematopoietic tissues as determined by flow cytometric analysis, fluorescence microscopy, fluorescence in situ hybridization analysis, and colony formation assay. Passive immunotherapy using murine anti-CD13 (F23) or anti-CD33 (M195) mAbs was able to eliminate completely the HL-60 cells in the mice, as determined by fluorescence in situ hybridization analysis, colony formation assay, and culture of mouse blood and tissue cells in vitro. Although F23 is able to inhibit completely CD13/aminopeptidase N enzymatic activity, actinonin, another potent inhibitor of CD13/aminopeptidase N, was not active as an antileukemic agent. HL-60 cell surface antigens, including CD13 (aminopeptidase N) and CD33 (p67), down-regulated over time, and murine anti-HL-60 antibody was generated while the cells grew in the mice. This response was suppressed by cyclophosphamide. These data suggest that leukemia cell elimination was antibody mediated.

Acute Disease↗
PubMed1995

Characterization of an ovarian cancer activating factor in ascites from ovarian cancer patients.

Ascites from ovarian cancer patients contain potent growth-promoting activity toward human ovarian cancer cells both in vitro and in vivo. This activity is associated with rapid increases in cytosolic free calcium ([Ca2+]i) as a consequence of phosphoinositide hydrolysis. In this study, we describe the purification, characterization, and identification of an ovarian cancer activating factor (OCAF) from ascites of ovarian cancer patients. We have isolated OCAF by a combination of solvent extraction, silica gel chromatography, and TLC. Mass spectral analysis, phospholipase sensitivity, and gas chromatographic behavior of purified OCAF indicate that OCAF is composed of various species of lysophosphatidic acid (LPA), including LPAs with polyunsaturated fatty acyl chains (linoleic, arachidonic, and docosahexaenoic acids). However, OCAF is more potent than sn-1 palmitoyl, oleoyl, or stearoyl LPA in increasing [Ca2+]i in ovarian cancer cells. The ability of OCAF to alter [Ca2+]i is sensitive to the effects of lipoxidase, whereas the activity of sn-1 oleoyl, stearoyl, or palmitoyl LPA is not, suggesting that polyunsaturated bonds in the fatty acyl chain of OCAF may account for its increased ability to activate ovarian cancer cells. Furthermore, a sn-2 linoleoyl LPA generated by phospholipase A1 treatment of synthetic phosphatidic acid is much more active than are sn-1 palmitoyl, stearoyl, or oleoyl LPA in increasing [Ca2+]i in ovarian cancer cells. Taken together, these data suggest that the ability of OCAF to increase cellular calcium may reside in the structure and/or location of the fatty acyl chain of LPA. Purified OCAF, at concentrations similar to those present in ascites from ovarian cancer patients, was sufficient to induce proliferation of ovarian cancer cells, as indicated by thymidine incorporation, reduction of 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, or colony formation. However, even at optimal concentrations of OCAF, proliferation was lower than that induced by FCS or ascites from ovarian cancer patients, indicating that, although OCAF may be a major regulator of ovarian cancer cells in vivo, it is not the sole mediator present in ascites, and it likely functions in concert with other growth factor activities.

Ascites↗