Search PubMed⌕ Search

Biomedical subjects

Y P Xu

Publications and source records attributed to Y P Xu.

At least 19 recordsLinked to original sources
PubMed2006

Structure determination and relative properties of novel noncentrosymmetric borates MM'4(BO3)3 (M = Na, M' = Ca and M = K, M' = Ca, Sr).

A series of novel noncentrosymmetric borates, MM'4(BO3)3 (M = Na, M' = Ca; M = K, M' = Ca, Sr), have been successfully synthesized via a standard solid-state reaction. The crystal structures have been determined by the SDPD (structure determination from powder diffraction) method. They crystallize in the noncentrosymmetric space group Ama2 with the following lattice parameters: a = 10.68004(11) A, b = 11.28574(11) A, c = 6.48521(6) A for NaCa4(BO3)3; a = 10.63455(10) A, b = 11.51705(11) A, c = 6.51942(6) A for KCa4(BO3)3; and a = 11.03843(8) A, b = 11.98974(9) A, c = 6.88446(5) A for KSr4(BO3)3. The fundamental building units are isolated BO3 anionic groups. Their second harmonic generation (SHG) coefficients were one-half (NaCa4(BO3)3), one-third (KCa4(BO3)3), and two-thirds (KSr4(BO3)3) as large as that of KH2PO4 (KDP). The infrared and UV-vis spectra of the three compounds are discussed. Moreover, a comparison of the structures of these novel compounds and three other novel cubic compounds with the same formula, MM'4(BO3)3 (M = Li, M' = Sr; M = Na, M' = Sr, Ba), is presented here.

Journal Article↗
PubMed2005

Structure determination and relative properties of novel cubic borates MM'4(BO3)3 (M = Li, M' = Sr; M = Na, M' = Sr, Ba).

A series of novel borates, MM'4(BO3)3 (M = Li, M' = Sr; M = Na, M' = Sr, Ba), have been successfully synthesized by standard solid-state reaction. The crystal structures have been determined from powder X-ray diffraction data. They crystallize in the cubic space group Iad with large lattice parameters: a = 14.95066(5) A for LiSr4(BO3)3, a = 15.14629(6) A for NaSr4(BO3)3, and a = 15.80719(8) A for NaBa4(BO3)3. The structure was built up from 64 small cubic grids, in which the M' atoms took up the corner angle and the BO3 triangles or MO6 cubic octahedra filled in the interspaces. The isolated [BO3]3- anionic groups are perpendicular to each other, distributed along three 100 directions. The anisotropic polarizations were counteracting, forming an isotropic crystal. Sr and Ba atoms were found to be completely soluble in the solid solution NaSr(4-)xBax(BO3)3 (0 < or = x < or = 4). The photoluminescence of samples doped with the ions Eu2+ and Eu3+ was studied, and effective yellow and red emission was detected, respectively. The results are consistent with the crystallographic study. The DTA and TGA curves of them show that they are chemically stable and congruent melting compounds.

Journal Article↗
PubMed2005

Synthesis and ab initio X-ray powder diffraction structure of the new alkali and alkali earth metal borate NaCa(BO3).

A sodium calcium borate, NaCaBO3, has been synthesized by the solid-state reaction method and the structure solved from X-ray powder diffraction data. The compound crystallizes in space group Pmmn and has a desired structure type containing isolated planar BO3(3-) anions. Mixed occupancy is found to exist in the Ca site, with partial replacement by Na. One Ca/Na mixed atom and one Na atom are at sites with mm2 symmetry, and a second Ca/Na mixed atom, an Na atom, two B and two O atoms are on mirror planes.

Journal Article↗
PubMed2004

Syntheses, thermal stability, and structure determination of the novel isostructural RBa3B9O18 (R = Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb).

A novel borate compound YBa(3)B(9)O(18) has crystallized in a melt of BaYB(9)O(16). Single-crystal X-ray diffraction measurements reveal that YBa(3)B(9)O(18) adopts a hexagonal space group P6(3)/m with cell parameters of a = 7.1761(6) A and c = 16.9657(6) A. The structure is made up of the planar B(3)O(6) groups parallel to each other along the (001) direction, regular YO(6) octahedra, and irregular BaO(6) and BaO(9) polyhedra to form an analogue structure of beta-BaB(2)O(4). A series of isostructural borate compounds RBa(3)B(9)O(18) (R = Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) were prepared by powder solid-state reactions. The DTA and TGA curves of YBaB(9)O(16) show an obvious weight loss at about 955 degrees C associated with a decomposition into YBO(3), B(2)O(3), and YBa(3)B(9)O(18) due to its incongruent melting behavior. The DTA and TGA curves of YBa(3)B(9)O(18) show that it is chemically stable and a congruent melting compound. A comparison of the structures of YBa(3)B(9)O(18) and beta-BaB(2)O(4) is presented.

Journal Article↗
PubMed2004

Effect of cardiopulmonary bypass on leukocyte activation: changes in membrane-bound elastase on neutrophils.

BACKGROUND: Neutrophil elastase is known to be released from the activated leukocytes as a result of cardiopulmonary bypass (CPB). However, its biological effect on organ injury is questionable because it is quickly bound by natural proteinase inhibitors (PIs). Recently, membrane-bound elastase (MBE) was found to be able to resist the PIs' process and, thus, is biologically more active. This paper studies the effect of CPB on the kinetic change of MBE and its possible link to postoperative inflammation and organ function. METHOD: Ten consecutive patients undergoing elective coronary artery bypass grafting (CABG) surgery with CPB were recruited into the study. Blood samples were taken before sternotomy, after aortic declamping, at the end of CPB, three and six hours after CPB and on the first postoperative day. MBE was determined by substrate assay from isolated neutrophils. Inflammation and organ function markers methods. RESULTS: MBE slightly increased after aortic declamping, while it significantly increased and reached its peak at the end of CPB; it returned to its preoperative level on the first postoperative day. In contrast to lung sequestration of neutrophils, there was no transpulmonary gradient of MBE between left and right atria after aortic declamping. Neither MBE nor total MBE activity was positively correlated with postoperative inflammation markers such as blood lactate and C-reactive protein and organ function markers such as creatine phosphokinase and alanine aminotransferase. CONCLUSIONS: CPB induces increased MBE expression on neutrophils with its peak at the end of CPB. Lack of association between neutrophil MBE and clinical markers suggests that multiple systems might be involved in the post-CPB inflammatory reaction and organ dysfunction.

Aged↗
PubMed2000

[Study on stepwise regression of risk factors in patients with sudden deafness].

OBJECTIVE: To explore the affected factors of sudden deafness. METHOD: To analyse the stepwise regression of various factors in age, systolic pressure/diastolic pressure, immunoglobulin G, A, M, KPTT, PT, Fbg, FDP, ELT and auditory threshold. RESULT: There was significant correlation (positive straightline relativity) between the auditory threshold and KPTT in patients with sudden hearing loss, and between the auditory threshold and PT in the analysis of coagulogram. CONCLUSION: The state of blood circulation didn't show hypercoagulability in some patients with sudden hearing loss. We must be very careful in therapy of anticoagulation and the increment of blood volume.

Adolescent↗
PubMed1998

Nuclear proteins from liver and kidney bind a 37 bp sequence in the 5' upstream region of the mGAT1 gene.

The mouse GABA transporter (mGAT1) gene has been shown to be exclusively expressed in brain by Northern and Western blot analyses. The interactions between the 5' flanking region of the mGAT1 gene and nuclear proteins from different mouse tissues were studied by means of gel-shift assay. Our results show that nuclear protein factors from non-nervous tissues can specifically recognize a 37 bp sequence that is conserved in the 5' flanking region between the human and mouse GAT1 genes. Similar nuclear protein factors were also found to exist in rat, rabbit and pig.

Animals↗
PubMed1998

[Changes of airway responsiveness, and relative factors in asthmatics with remission at puberty].

OBJECTIVE: To study the airway responsiveness and relative factors in asthmatics with natural remission at puberty. METHOD: The airway responsiveness was evaluated by challenge of methacholine (PC20), blood sIL-2R, eosinophil count, basophil count and basophil releasability were detected in 18 asthmatics with remission at puberty (group I), in 20 asthmatics without remission at puberty (group II), and in 30 healthy controls (group III). RESULT: The mean value of PC20 in the group I was significantly lower than that of the group III (P < 0.01), but still higher than that of the group II (P < 0.01). The blood sIL-2R and eosinophil values were droped almost to those of the group III, significantly lower than those of the group II. The basophil value and positive rate of human basophil degranulation test stimulated by mannitol with hyperosmolarity were still abnormal, significantly higher than those of the group III, and the basophil level was significantly related to the airway responsiveness. CONCLUSION: The asthmatics with remission at puberty have a certain degree of airway hyperresponsivenes that is related to the abnormal of basophil.

Adult↗
PubMed1997

Effects of GH on IGF-II-induced progesterone accumulation by cultured porcine granulosa cells.

A total of seven experiments were conducted to investigate the potential facilitative interaction of growth hormone (GH) and insulin-like growth factor II (IGF-II) in stimulating steroidogenesis by cultured porcine granulosa cells and to examine the possible nature of this action. Porcine granulosa cells were cultured in serum-free medium in the presence or absence of GH or prolactin, with or without IGF-II or IGF-I. IGF-II by itself dose (with peak progesterone production of 498 ng/mg DNA/24 h being observed at 100 ng of IGF-II/mL) and time- (with minimum time requirement of 24-48 h) dependently increased progesterone accumulation (P < 0.01). Neither GH (dose range 0, 5, 10, 50, 100, and 150 ng/mL) nor prolactin (dose range 0, 0.01, 0.1, 1, 5, 10 micrograms/mL) alone stimulated progesterone accumulation when compared with the control (P > 0.05). However, in the presence of IGF-II, GH proved to be a potent amplifier of IGF-II in progesterone production (P < 0.01) with a minimum GH time requirement of 24-48 h. In contrast, prolactin did not influence IGF-II-induced progesterone accumulation (P > 0.05). An inhibitory study showed that the presence of cycloheximide (3 micrograms/mL) or actinomycin D (1 microgram/mL) blocked both the stimulatory effect of IGF-II on progesterone accumulation and the amplification of GH on IGF-II induced production (P > 0.01), suggesting GH amplification of IGF-II-induced progesterone accumulation is a process involving gene transcription and translation. Northern blot analysis further demonstrated that GH amplification of IGF-II-induced steroidogenesis can be attributed, at least partially, to enhanced IGF-II-induced cytochrome P450 cholesterol side-chain cleavage mRNA by GH.

Animals↗
PubMed1997

Growth hormone as an amplifier of insulin-like growth factor-I action: potentiated oestradiol accumulation.

The interaction between GH and IGF-I in modulating oestradiol biosynthetic capacity was examined in cultured porcine granulosa cells. Granulosa cells (2 x 10(6) viable cells/culture) were initially cultured for 96 h (treatment period) in an androstenedione-free medium in the absence or presence of IGF-I (0 or 50 ng/ml), with or without GH at 100 ng/ml. At the conclusion of this period, culture media were discarded and the cells were washed twice with the androstenedione-free medium and reincubated for an additional 24 h (test interval) in an androstenedione (10(-7) M)-supplemented medium for oestradiol accumulation. GH alone induced no stimulation (P > 0.05) of basal oestradiol accumulation. In contrast, concurrent treatment with IGF-I produced a 4.3-fold increase (26 vs 112 ng/ 2 x 10(6) cells per 24 h, P < 0.001) in oestradiol accumulation. GH amplified IGF-I-induced oestradiol production in a dose (minimal dose requirement of 0.3 ng/ml)- and time (minimal time requirement of 24-48 h)-dependent manner. Studies on the site(s) of action indicated that GH exerts its amplifying effects on IGF-I-induced oestradiol production both proximal and distal to cAMP generation. As the specificity study and the inhibitory study indicated, GH amplification of IGF-I-induced oestradiol production is a process involving gene transcription and/or translation and the synergism is not solely specific to IGF-I as IGF-II-induced oestradiol production was also amplified in the presence of GH.

Androstenedione↗
PubMed1995

Growth hormone amplifies insulin-like growth factor I induced progesterone accumulation and P450scc mRNA expression.

The interaction of growth hormone (GH) and insulin-like growth factor I (IGF-I) in the acquisition of progesterone biosynthetic capacity were examined in cultured porcine granulosa cells. Basal progesterone production was not affected (P > 0.05) by GH treatment. However, concurrent treatment with GH produced a 4.1-fold increase (539 versus 2214 ng/culture) in the IGF-I-stimulated accumulation of progesterone. GH potentiated IGF-I induced progesterone production in a dose and time dependent manner, with a time requirement of 48 h or less. The amplified effect of GH was not attributable to changes in cellular protein, DNA content, cell number, plating efficiency or cell viability. Moreover, Northern blot analyses revealed that GH enhanced IGF-I induced expression of the gene encoding cytochrome P450 side chain cleavage. These observations provide further evidence to support the role of GH in the regulation of ovarian steroidogenesis.

Animals↗
PubMed1994

[A clinical study 39 cases of ovarian pregnancy].

Thirty-nine cases of ovarian pregnancy in our hospital from 1982 to 1992 were analyzed, and compared with the tubal pregnancies admitted during the same period. It showed that the incidence of ovarian pregnancy was 2.6% of all ectopic pregnancies with a trend to increase yearly. The clinical features of ovarian pregnancy revealed that abdominal pain was the major symptom, and history of amenorrhea was obscure. The clinical diagnosis of ovarian pregnancy was more difficult than that of tubal pregnancy. The typical histologic characteristics showed the embryo and chorionic villi surrounded by ovarian tissue or the presence of decidual changes. Ovarian pregnancy was closely related with poor uterine environment, pelvic inflammatory disease and/or endometriosis. The preferred therapeutic procedure was partial ovariectomy or wedge resection, preserving the normal ovarian tissue and tube as much as possible.

Adult↗
PubMed1994

Antitumor effect of alpha isomer of anordrin in vitro and cell cycle arrest at G1 phase.

Alpha isomer of anordrin (2 alpha, 17 alpha-diethyl-A-norandrostane-2 beta, 17 beta-diol dipropionate, alpha-Ano) inhibited mouse hepatoma (Hep A) and P388 cell growth in vitro. alpha-Ano (20 micrograms.ml-1) inhibited the incorporation of [3H]uridine and [3H]thymidine into RNA and DNA within 3 h, but the inhibition of L-[3H]lysine incorporating into protein was not obvious. alpha-Ano had no effect on the DNA-dependent RNA synthesis with purified nuclei of Hep A cells. It is suggested that the inhibition of RNA and DNA syntheses is the major cause of the cytostatic effect. alpha-Ano blocked the P388 cells at G1/G0 phase, and the delay in G1/G0 to S phase transition plays an important role in the inhibition of P388 cell growth.

Animals↗
PubMed1991

Calcium dependency of muscarinic and nicotinic agonist-induced ATP and catecholamine secretion from porcine adrenal chromaffin cells.

The secretion of catecholamines and ATP induced by cholinergic agonists and its dependence on extracellular Ca2+ were studied in cultured porcine adrenal chromaffin cells. Both nicotine and methacholine (a selective muscarinic agonist) induced secretion and increases in cytosolic free Ca2+ concentration ([Ca2+]in), although the activation of nicotinic receptors produced responses that were larger than those produced by activation of muscarinic receptors. The secretion and the increase in [Ca2+]in evoked by nicotine were completely dependent on extracellular Ca2+ and were blocked by prior depolarization of the cells with high extracellular K+ levels. In addition, nicotine induced significant 45Ca2+ influx. In contrast, the secretion and the increase in [Ca2+]in evoked by methacholine were partially dependent on extracellular Ca2+; methacholine also induced 45Ca2+ influx. Prior depolarization of the cells with high extracellular K+ levels did not block methacholine-induced secretion. In general, nicotinic responses were mediated by Ca2+ influx through voltage-dependent pathways. In contrast, muscarinic responses were dependent on both Ca2+ influx through an unknown mechanism that could not be inactivated by high K+ concentration-induced depolarization and presumably also intracellular Ca2+ mobilization.

Adenosine Triphosphate↗
PubMed1989

[P-8502--a new mu selective opioid receptor ligand].

The analgesic potencies of 3-[beta-(p-amino)-phenethyl)-9 beta-methoxy-9 alpha-(m-methoxyphenyl)-3- azabicyclo [3,3,1] nonane (P-8502) and 3-[beta-(p-monoester fumarylamido)-phenethyl]-9 beta-methoxy-9 alpha-(m-methoxyphenyl)-3-azabicyclo [3,3,1] nonane (P-8511) were examined. The analgesic ED50 of P-8502 and P-8511 were 55 and 200 micrograms/kg (mice, ip, hot plate), and 30 and 95 micrograms/kg (rat, sc, tail flick), respectively. The duration of the analgesic action of P-8511 (about 4 h) was longer than that of P-8502 (about 1.5 h, rat, sc, tail flick). Binding assay showed that P-8502 had a high ratio of delta/mu, kappa/mu: IC50 (DPDPE)/IC50 (DAGO) = 399; IC50(DAD-LE)/IC50 (DAGO) = 1498; IC50 (kappa)/IC50 (DAGO) = 159. In conclusion, P-8502 appears to be a new mu selective opioid receptor ligand, whereas P-8511 has no such selectivity.

Analgesics↗