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Biomedical subjects

X Yang

Publications and source records attributed to X Yang.

At least 487 records · Page 27Linked to original sources
PubMed2000

[Effects of 1 alpha(OH)D3 on trabecular and cortical bone in ovariectomized rats].

OBJECTIVE: To study the pharmaceutical effects of 1 alpha(OH)D3 on trabecular and cortical bone in ovariectomized (OVX) rats. METHODS: 41 female Wistar rats of six months old were randomly divided into 5 groups: (1) Baseline control; (2) Sham control; (3) 6 weeks after OVX (OVXb); (4) 14 weeks after OVX (OVXe); (5) OVX + 0.1 microgram/(kg.d) 1 alpha(OH)D3 (O + VD), treatment started 6 weeks after OVX and lasted 8 weeks. Histomorphometry analysis of tibia, peripheral quantitative computed tomography (pQCT) scanning of femur, bone biomechanical test and serum and urinary biochemical parameters were determined. RESULTS: The levels of bone turnover indexes increased in OVX rats, OVX also resulted in reducing of trabecular, bone mass and biomechanical properties. The ratio of urinary deoxypyridinoline crosslink/creatinine was decreased by 67.0% in O + VD group compared with OVXe group 67.0% [(43.50 +/- 11.20) nmol.L-1/mmol.L-1 vs(131.80 +/- 14.90) nmol.L-1/mmol.L-1, P < 0.01]. Percent trabecular area (Cn-BV/TV) was increased by 89.8% in O + VD group compared with OVXe group (11.03 +/- 0.73 vs 5.81 +/- 1.29, P < 0.05). Trabecular bone mineral content and density were increased by 77.3% and 91.3% compared with OVXe respectively (P < 0.05). Although cancellous maximal load and stiffness increased in O + VD group, but no statistical significance. 1 alpha(OH)D3 also enhanced polar moment of inertia (PMI) and maximal load of cortical bone in femur compared with OVXe (23.70 +/- 1.63 vs 18.23 +/- 1.41, P < 0.01 and 171.69 +/- 9.92 vs 147.58 +/- 11.29, P < 0.05 respectively). CONCLUSION: 1 alpha(OH)D3 inhibited the higher bone turnover induced by OVX, increased trabecular bone in proximal tibia and bone mass in distal femur. 1 alpha(OH)D3 also improved the mechanical properties of cortical bone in femur.

Animals↗
PubMed2000

[Expression of epidermal growth factor receptor in gestational trophoblastic tumours].

OBJECTIVE: To investigate the expression of epidermal growth factor receptor (EGFR) in gestational trophoblastic tumours and its clinical significance. METHODS: Placentas of 10 normal early pregnancies, 20 molar pregnancies, 10 samples from invasive mole and 8 samples of choriocarcinoma were used for the study. EGFR expression was evaluated by immunohistochemistry using monoclonal antibody. RESULTS: EGFR was expressed both in normal chorionic villi and tissues of trophoblastic tumours. EGFR was expressed more strongly in normal chorionic villi and non-malignant transformed hydatidiform mole than in malignant transformed molar pregnancies and malignant trophoblastic tumours (P < 0.05). Univariate and multivariate analysis indicated that EGFR immunostaining intensity was significantly related to the clinical stage in malignant trophoblastic tumours (P = 0.026, OR = 9.874). CONCLUSION: EGFR expression could be used as an index for prediction of malignant transformation of hydatidiform mole and staging of malignant trophoblastic tumours.

Adult↗
PubMed2000

[An experiment of gut barrier function damage following multiple firearm injuries in a porcine model].

OBJECTIVE: To study the characteristics and pathogenesis of gut barrier damage following multiple firearm injuries in porcine models. METHODS: 24 small pigs were divided into 4 groups (n = 6 each): control group(group C), group H (gunshot-induced tangential fracture of parietal bone), group L (gunshot-induced comminuted fracture of bilateral femora) and group M (combined group H + L). Gastric intramucosal pH (pHi), plasma endotoxin in portal vein, and plasma D-lactic acid were measured and blood samples were cultured at different time intervals after trauma. The animals were sacrificed at 72 h and ileum tissues were harvested for pathological examination and DAO measurement. RESULT: In group M at 72 h, pHi was significantly lower than that of group H and L(P < 0.01), plasma endotoxin level was significantly higher than that of group H(P < 0.01) and group L(P < 0.05), D-lactic acid level was significantly higher than that of group H(P < 0.01), and bacterial isolation rate in blood was much higher than that of group H and L(P < 0.05). Necrosis and peeling off were revealed at ileum villus top in all trauma groups, especially in group M, in which ileum DAO content also declined in most cases. CONCLUSION: Multiple traumas were prone to gastrointestinal ischemia even when hemorrhagic shock did not take place. The damage of gut barriers in multiple traumas were more severe than that in one-site trauma, which enhanced the incidence of intestinal endotoxin and bacterial translocation and trend to cause enterogenous infection.

Amine Oxidase (Copper-Containing)↗
PubMed2000

[Re-evaluation of an embolic material for aneurysm cellulose acetate polymer].

OBJECTIVE: To re-evaluate the safety, effect, and pathological reactions of cellulose acetate polymer (CAP). METHODS: 30 right carotid arteries of rats were embolized and got two embolized vessels for histological study in each of the seven stages within four months. Fifteen canine aneurysmal models were created by transplantation of venous pouches. Twelve of them were occluded with CAP. Digital Subtraction Angiography (DSA) follow-ups of occluded aneurysmal models were carried out 1, 2 and 8 weeks after occlusion. One animal was sacrificed randomly at each stage for pathological study. RESULTS: Only five of the 12 aneurysmal models were completely or partially occluded within the patency of parent arteries within two months of observation after embolization with CAP. Stenosis of one branch of aneurysmal parent artery was occurred. The residual cavity of one partially occluded model artery was enlarged. Two models ruptured on four and five days after embolization. Three embolized models and their parent arteries were all occluded. PATHOLOGICAL FINDINGS: acute pathological reaction occurred within vessels embolized with CAP. Endothelial cell and basal membrane were damaged and vanished. Elastic lamina was exposed to arterial lumen and attached by thrombus layer. Fibrous cells and smooth muscle cells showed obvious degeneration. CAP and thrombus were gradually organized in two months after thrombosis. The orifices of aneurysmal models were covered with newly developed fibrous tissue and endothelial cells in two months after thrombosis. CONCLUSIONS: We think that acute chemical erosive effect of CAP was evident. A strong effect could lead to rupture of some of the CAP thrombosed aneurysmal models. Besides, stenosis or occlusion of the parent arteries could be induced in some cases after embolization with CAP. For the above shortcomings and limitations, it should be improved carefully before it is applied in clinic.

Aneurysm↗
PubMed2000

[Parent artery occlusion for the treatment of vertebral artery aneurysm].

OBJECTIVE: To describe the endovascular treatment of posterior aneurysm with balloon occlusion of ipsilateral vertebral artery. METHODS: 10 patients aging from 12 to 52 years old with mean age 41 were performed occlusion of unilateral vertebral artery after 30 minutes test occlusion. The whole procedure was under systemic anticoagulation. The Willi's Circle was evaluated by MRA before treatment. RESULTS: No immediate complication occurred after the treatment. 10 patients were followed up for 3 months to 5 years. 8 of the 10 cases accepted MR or DSA examination. Focal infarction was found in one patient. The aneurysm was filling in contralateral vertebral artery angiography in one patient, but there was no symptom. CONCLUSION: Vertebral artery occlusion is an effective treatment to some complicated posterior circulation aneurysms, which is difficult to be clipped and coiled.

Adolescent↗
PubMed2000

[Diagnosis and management of gestational trophoblastic tumor with liver metastases].

OBJECTIVE: To evaluate management options and clinical prognosis for women presenting gestational trophoblastic tumor (GTT) with liver metastases. METHODS: We retrospectively analyzed sixteen GTT patients with liver metastases treated in the Peking Union Medical College (PUMC) hospital from 1985 to 1998. All were treated with 5-FU combined chemotherapy or EMA/CO regimen. Eight of them received hepatic artery infusion chemotherapy. Treatment outcome was measured by beta subunit human chorionic gonadotropin assay (beta-hCG) and by imaging studies which included ultrasound and computerized tomography. RESULTS: Of 16 cases, 4 achieved complete remission; biochemical remission was obtained in 2 patients who were alive with residual tumor; 10 patients died of the disease. The overall survival rate was 37.5% (6/16). CONCLUSIONS: The outcome for women presenting with liver metastases from GTT is poor. Early diagnosis and prompt initiation with vigorous multi-agent chemotherapy given through multi-routes are emphasized for improving the treatment outcome.

Adult↗
PubMed2000

Closed reduction and percutaneous K-wires fixation of displaced supracondylar humerus fractures in children.

OBJECTIVE: To observe the effects of closed reduction and percutaneous K-wires fixation of displaced supracondylar humerus fracture in children. METHODS: Retrospective review of fourteen patients who sustained displaced supracondylar fracture of distal humerus treated by closed reduction and percutaneous K-wires fixation. RESULTS: All patients' K-wires were removed at 4 weeks post-operation. Their elbow function regained at weeks. The average period of followed up was 10 month (varies from 6 to 18 month), all fractures healed without any permanent complications. Two transient nerves palsy, ulnar and radial nerve each, recovered 12 weeks and 16 weeks post-operation respectively. CONCLUSION: Closed reduction and percutaneous K-wires fixation is a safe and efficient treatment for humerus surpracondylar fracture in children.

Adolescent↗
PubMed2000

[Quantitative analysis of rutin and vitamin C by NIR FTIR].

In this paper, near-infrared diffuse reflectance spectroscopy(NIRDRS) method was used as a quantitative tool to measure the solid mixture of rutin and vitamin C by collecting NIR spectra in the range 7,000-3,900 cm-1. The quantitative mathematics model was established with partial least squares(PLS) method. The correlation coefficient was 99.75%, the standard error of Rutin was 0.363%, and the standard error of Vitamin C was 1.078%. The methods are rapid, exact and nondestructive to samples. The components of the samples can be individually analyzed with high accuracy and precision, so NIRDRS can be a useful method of quality control of pharmaceuticals in the future.

Ascorbic Acid↗
PubMed2000

[Studies on spectral interferences and correction in simultaneous determination of multi-elements in sediments with ICP-AES].

Spectral interferences in the simultaneous determination of multi-elements in sediments and soil by ICP-AES were investigated and the multicomponent spectral fitting (MSF) method was used for the correction. Several factors affecting the MSF method such as the signal integration time and the spectra shift were studied. The comparison between MSF and off-peak background correction were made by analyzing national standard reference material: sediment GBW07306. The detection limit and the precision could be improved by a factor of 1.3-9.0 and 1.1-4.9 respectively and the results agreed better with those of the certified values when using MSF correction.

Aluminum↗
PubMed2000

[Relation between theoretical atomization efficiency and atomization temperature in GFAAS].

In this work, the relationship between the theoretical atomization efficiencies (EA') and atomization temperature (T) in graphite furnace atomic absorption spectrometry (GFAAS) for 18 elements were studied in detail. The results showed that a linear relationship between the EA' and the atomization temperature existed at a definite atomization temperature range. The correlation coefficient was within 0.9940-0.9993 for 18 elements. The slope was in the range of 0.06-0.07. The theoretical atomization efficiency was about 65% for all elements at optimized atomization temperature. This indicated that some factors should be taken into account in the L'vov modified model of characteristic mass.

English Abstract↗
PubMed2000

[Real time monitor of rutin stability during heating by Fourier transform infrared spectroscopy].

The thermal stability of the natural product of rutin was studied by Fourier Transform Infrared Spectroscopy (FTIR) in this paper for the first time. To monitor the changing of rutin in real time, the temperature-control accessory was also used to in-situ follow the thermal behavior. It is demonstrated that as the temperature increased from 25 degrees C to 270 degrees C, the thermally-induced denaturation of rutin was accompanied by the oxidation and thermal discomposed procedure. The structure of rutin changed at a lower temperature (75 degrees C). This is not only indicating the existence of an intermediate state, but also approved that the stability of rutin is poor. While at the higher temperature (270 degrees C), rutin discomposed into two results. It is proved that this method is fast, accurate and having no solvent effect. Samples can thus be examined undestroyed.

Computer Systems↗
PubMed2000

[Spectra on the influence of grinding to kaolinite structure].

Kaolinite clay is one of important ceramic materials. In this paper, the kaolinite clay was ground by dry grinding and wet grinding. The powder samples ground for different time were measured by FTIR spectra and XRD, and the changing rules of the IR absorption frequency and XRD were respectively discussed. The results indicated that wet grinding was superior to dry one. Kaolinite structure began to change while it was ground by dry mothed for 12 h, and the layer structure was destroyed completely till 42 h. However, the day structure didn't change much until 54 h at the condition of wet grinding. The mechanism of the kaolinite structure changed were also discussed in detail.

English Abstract↗
PubMed2000

[Application of spectral analysis on atmosphere corrosion research].

This paper applied two methods of spectrum analysis to measure the rusty layer of samples atmosphere corrosion from Qingdao and Chengdu. The main component elements and rust phase of rusty layer are obtained. It showed that the relative content of the elements and rust phase varies with the change of corroded environment and time. The result, relative content of each rust phase of A3(1) rusty layer sample have following relation: gamma-Fe00H > alpha-Fe00H > delta-Fe00H, and, relative content of other rusty layer samples have relation: gamma-Fe00H > delta-Fe00H > alpha-Fe00H, in the rusty layer of low-alloy steel, there are the alloy elements of rest body.

English Abstract↗
PubMed1999

Site-directed mutagenesis of diphosphoinositol polyphosphate phosphohydrolase, a dual specificity NUDT enzyme that attacks diadenosine polyphosphates and diphosphoinositol polyphosphates.

Diphosphoinositol polyphosphate phosphohydrolase (DIPP) hydrolyzes diadenosine 5',5"'-P(1),P(6)-hexaphosphate (Ap(6)A), a Nudix (nucleoside diphosphate attached-moiety "x") substrate, and two non-Nudix compounds: diphosphoinositol pentakisphosphate (PP-InsP(5)) and bis-diphosphoinositol tetrakisphosphate ((PP)(2)-InsP(4)). Guided by multiple sequence alignments, we used site-directed mutagenesis to obtain new information concerning catalytically essential amino acid residues in DIPP. Mutagenesis of either of two conserved glutamate residues (Glu(66) and Glu(70)) within the Nudt (Nudix-type) catalytic motif impaired hydrolysis of Ap(6)A, PP-InsP(5), and (PP)(2)-InsP(4) >95%; thus, all three substrates are hydrolyzed at the same active site. Two Gly-rich domains (glycine-rich regions 1 and 2 (GR1 and GR2)) flank the Nudt motif with potential sites for cation coordination and substrate binding. GR1 comprises a GGG tripeptide, while GR2 is identified as a new functional motif (GX(2)GX(6)G) that is conserved in yeast homologues of DIPP. Mutagenesis of any of these Gly residues in GR1 and GR2 reduced catalytic activity toward all three substrates by up to 95%. More distal to the Nudt motif, H91L and F84Y mutations substantially decreased the rate of Ap(6)A and (PP)(2)-InsP(4) metabolism (by 71 and 96%), yet PP-InsP(5) hydrolysis was only mildly reduced (by 30%); these results indicate substrate-specific roles for His(91) and Phe(84). This new information helps define DIPP's structural, functional, and evolutionary relationships to Nudix hydrolases.

Acid Anhydride Hydrolases↗
PubMed1999

Thermal Conversion of a Helical Coil into a Three-Dimensional Chiral Framework.

Thermal dehydration results in the solid-state supramolecular conversion of the helical coordination polymer [{[Cu(sala)](2)(H(2)O)}(n)] into the chiral three-dimensional covalent open network [{Cu(sala)}(n)] (shown schematically). X-ray crystallography reveals that hydrogen bonding plays a key role in this process. H(2)sala=N-(2-hydroxybenzyl)-L-alanine

Journal Article↗
PubMed1999

Rare interstitial deletion (2)(p11.2p13) in a child with pericentric inversion (2)(p11.2q13) of paternal origin.

An unbalanced 46,XY,der(2)del(2)(p11.2p13) inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child with a de novo interstitial deletion of band 2p12 associated with an inv(2)(p11.2q13) inherited from the father. The inv(2) is generally considered a benign familial variant without significant reproductive consequences. However, our findings led us to consider a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either a deletion or duplication of a segment adjacent to the inverted region in the offspring. This phenomenon has been reported in other inversions of chromosomes 1, 7, 13, 15, and 17 and may explain the origin of the deletion in our patient. Although repetitive sequences might be present around such inversions, which could predispose to de novo deletions independently of the inversion, current evidence including this case favors a proposed causal relationship between the parental inversion and the deletion in the child. Our review and results suggest there could be a small risk for a related imbalance to couples with an inv(2)(p11.2q13). For del(2)(p11.2p13), which is rare, a more distinct phenotype has been proposed herein. Our patient shared several findings with the three previously published cases, namely the broad nasal bridge, abnormal ears, high-arched palate, psychomotor retardation, and micrognathia. However, our patient also had sensorineural hearing loss and significant hypotonia, which have not been previously reported, thereby expanding our understanding of this rare deletion. Am. J. Med. Genet. 87:139-142, 1999. Published 1999 Wiley-Liss, Inc.

Abnormalities, Multiple↗
PubMed1999

Free radical scavenging and antioxidant activities of flavonoids extracted from the radix of Scutellaria baicalensis Georgi.

Free radical scavenging and antioxidant activities of baicalein, baicalin, wogonin and wogonoside, the four major flavonoids in the radix of Scutellaria baicalensis Georgi, were examined in different systems. ESR results showed that baicalein and baicalin scavenged hydroxyl radical, DPPH radical and alkyl radical in a dose-dependent manner, while wogonin and wogonoside showed subtle or no effect on these radicals. Ten micromol/l of baicalein and baicalin effectively inhibited lipid peroxidation of rat brain cortex mitochondria induced by Fe(2+)-ascorbic acid, AAPH or NADPH, while wogonin and wogonoside showed significant effects only on NADPH-induced lipid peroxidation. In a study on cultured human neuroblastoma SH-SY5Y cells system, it was found that 10 micromol/l of baicalein and baicalin significantly protected cells against H(2)O(2)-induced injury. Baicalein was the most effective antioxidant among the four tested compounds in every system due to its o-tri-hydroxyl structure in the A ring. Compared with a well-known flavonoid, quercetin, the antioxidant activity of baicalein was lower in DPPH or AAPH system, but a little higher in those systems which might associate with iron ion. These results suggest that flavonoids in the radix of Scutellaria baicalensis with o-di-hydroxyl group in A the ring, such as baicalein and baicalin, could be good free radical scavengers and might be used to cure head injury associated with free radical assault.

Animals↗