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Biomedical subjects

X Lu

Publications and source records attributed to X Lu.

At least 127 records · Page 7Linked to original sources
PubMed2001

[Treatment of syphilis in pregnancy and its perinatal prognosis].

OBJECTIVE: To investigate the effects of treatment of syphilis in pregnancy on perinatal prognosis. METHODS: Patients of syphilis in pregnancy from Hainan Provincial People's Hospital and Haikou Municipal Maternal and Child Health Center during 1995.1 to 2001.1 were collected for retrospective analysis. Pregnant women with syphilis were divided into treated group and untreated group according to whether they received penicillin anti-syphilis treatment or not during pregnancy. RESULTS: The total number of deliveries in the 2 hospitals during that period was 18,701, and 61 out of 9,805 women screened for syphilis were positive, giving an incidence of 6.2/1000. The perinatal mortality rates were 11.2% in treated group and 83.3% in untreated group, and incidences of congenital syphilis were 17.6% and 72.7% respectively. CONCLUSION: Syphilis in pregnancy is a serious complication to harm the fetus. Screening of syphilis during pregnancy is necessary, and penicillin treatment is effective which may reduce the perinatal mortality rate and the birth of congenital syphilis baby.

Adult↗
PubMed2001

[Influence of art of changes on the thinking of traditional Chinese medicine].

The most important influence of art of changes on traditional Chinese medicine (TCM) was reflected in the formation of the basic theory of TCM. Some innovations were achieved by using the theory of art of changes to research medicine in later ages. However, the specific therapies and the prognostication of diseases inferred by using the art of mathematics were mostly unreliable. Though the researches on the art of changes were helpful to the exploration of the cause and effect of TMC, yet, its practical significance should be evaluated properly.

Art↗
PubMed2001

Detailed deletion mapping on chromosome region 9p21 in human periampullary neoplasms.

OBJECTIVE: To further define the extent of chromosome 9p21 deletion in periampullary neoplasms. METHODS: The loss of heterozygosity at 5 microsatellite polymorphic markers on chromosome 9p21 was detected by polymerase chain reaction (PCR), polyacrylamide gel electrophoresis (PAGE) and silver staining in 35 specimens of periampullary neoplasms and their matching blood samples. RESULTS: Fifty percent (4/8) of pancreatic cancer cases showed the loss of heterozygosity at one or more microsatellite loci, with the more frequent sites of D9S974 (37.5%) and D9S942 (28.6%), and some showing consecutive allelic loss. Sixty-two point five percent (5/8) of ampullary carcinoma cases showed loss of heterozygosity at one or more of the loci, frequent site of loss being D9S942 (42.9%) and the next most frequent being IFNA (37.5%) and D9S171 (37.5%). Loss of one locus was observed in 14.2% (1/7) of insulinoma. CONCLUSION: The minimal common region of chromosome deletion in periampullary neoplasms is defined between the D9S974 and D9S942 loci within a 15 kb interval in 9p21, suggesting the involvement of a novel tumor suppressor gene in their carcinogenesis.

Adolescent↗
PubMed2001

[Biocompatibility of HA/TCP biphasic ceramics with co-cultured human osteoblasts in vitro].

The biocompatibility of HA/TCP ceramic was evaluated by investigation of attachment and growth of osteoblasts on biomaterial, as well as monitoring the effects of biomaterial on expression of functional phenotypes of co-cultured osteoblasts in vitro. When co-cultured with HA/TCP ceramics, osteoblasts firstly attached to the surface of HA/TCP disk, then attached to notches and grew into the micropores of biomaterial during further culture period. At last, the ceramics were almost packed with osteoblasts. Additionally, osteoblasts co-cultured with HA/TCP were similar to osteoblasts cultured under normal condition in osteoblastic phenotypes; the secreted lots of collagen type I, possess strong activity of Alkaline Phosphatase and mineralized extracellular matrix. The fact that osteoblasts could grow well on HA/TCP ceramics and the biomaterial did not affect their physiological function suggest that HA/TCP ceramic is biocompatible with human osteoblasts.

Biocompatible Materials↗
PubMed2001

[Changes of soft tissue profile in operated unilateral cleft lip and palate patients after maxillary protraction].

OBJECTIVE: The aim of this study is to investigate effects of maxillary protraction on soft tissue profile in operated operated unilateral cleft lip and palate (UCLP) patients. METHODS: A total of 10 growing UCLP patients (male 7, female 3), age from 8.2 to 12 years old (Average: 10.4 years old), were selected to be treated with maxillary protraction using head gear-chin cap-long hook protraction appliance. The appliance was worn 12-14 hours per day, and the protraction force was 400-500 g each side. The protraction direction was forward and slightly downward. The treatment period was 4.7 months (Average: 5.8 months). Cephalometrics were taken before and after treatment. The changes of soft-tissue profile were studied using the computer-aid X-ray cephalometric analysis. RESULTS: After protraction, the points of Prn, Sn and Ls moved forward significantly. The distance from points Ls to E plane changed significantly from 0.46 mm before treatment to 1.18 mm after treatment. The angle G-Prn-Pg' decreased significantly, and G-Sn-Pg' changed significantly from -0.30 before treatment to 6.260 after treatment. The anterior-posterior position of mandible and lower lip did not change significantly, the changes of angles Cm-Sn-Ls, A'ls/SiLi had no statistical significance. The results indicated that maxillary protraction could make maxilla and upper lip move forward, and the convexity of soft tissue profile improve significantly. CONCLUSION: Maxillary protraction is an effective way to improve the facial deformity of operated UCLP patients. UCLP patients should have early interrupted treatment.

Cephalometry↗
PubMed2001

[Technique and advance of comprehensive two-dimensional gas chromatography].

Many analytical problems require more resolution than the conventional single column chromatographic technique can provide. In such cases the separation power can be enhanced by using more than one separation technique or mechanism. The sample is then dispersed in different time dimensions. The resolution obtained depends strongly on the difference between these dimensions. The highest resolution is gained when there is no correlation between the separations, the dimensions being orthogonal to each other. Comprehensive two-dimensional gas chromatography (GC x GC) provides a true orthogonal separation system in which a modulator serially couples two columns containing dissimilar stationary phases. It focuses and subsequently reinjects components eluting from the first column into the second one. The system generates a peak capacity that is approximately equal to the product of the peak capacities of the two individual separation systems. In this paper, technique and instrumental considerations of GC x GC are discussed. The three designs of contemporary GC x GC systems are presented and compared. A number of typical applications on complex samples such as petroleum products and environmental pollutants are also cited. Finally, the future perspectives of GC x GC are simply discussed.

Chromatography, Gas↗
PubMed2001

[Development of a gas chromatographic column system for the on-line analysis of trace tetrahydrofuran in hexane].

A gas chromatographic system using home-made 7 microns thick cross-linked dimethylpolysiloxane columns for the on-line analysis of trace tetrahydrofuran in hexane in a rubber production facility was developed. The experimental parameters of the column system, including the temperature, flow rate as well as the back-flushing and heart-cutting program were investigated. The total column-switching program was suggested. The system has been successfully operated for more than one year with good resolution, stability and precision (RSD < 5%) in analyzing trace tetrahydrofuran (0-250 x 10(-6), V/V) for industrial process control in the rubber production facility.

Chromatography, Gas↗
PubMed2001

[Synthesis and ultraviolet-visible spectrum of two new symmetrical porphyrins].

Meso-tetra(p-benzoylaminophenyl) porphyrin or meso-tetra (o-benzoylaminophenyl) porphyrin are synthesized by condensation of meso-tetra (p-aminophenyl) porphyrin or meso-tetra (o-aminophenyl) porphyrin and benzoyl chloride in DMF using NaOH as catalyst, these porphyrins and the method have not been reported previously. Their structures are ascertained by elemental analysis, ultraviolet-visible spectrum, IR and 1H-NMR measurements. The ultraviolet-visible spectrum of the two porphyrins is discussed in detail.

Molecular Structure↗
PubMed2000

Mdm2 inhibits the apoptotic function of p53 mainly by targeting it for degradation.

The ability of Mdm2 to inhibit the activities of a C-terminal truncated p53 mutant, p53-Delta30, which can bind Mdm2 but is resistant to Mdm2-mediated protein degradation was investigated. The inhibitory function of an Mdm2 mutant, Mdm2-Delta(222-437), which can bind p53 but is defective in targeting p53 for degradation was also studied. We have demonstrated that targeting p53 for degradation is the most effective way for Mdm2 to inhibit the apoptotic function of p53. However, we have also shown that Mdm2 can inhibit the transactivation function of p53 without targeting it for degradation, although Mdm2 releases the transrepression ability of p53 mainly by targeting it for degradation. The ability of Mdm2 to inhibit the apoptotic function of p53 was linked to its ability to inhibit the transrepression but not the transactivation function of p53. Furthermore, we have demonstrated that the transrepression function of p53 was specific to p53-induced apoptosis and was not simply a result of cell death.

Animals↗
PubMed2000

Study on the fluorescence spectra and electrochemical behavior of ZnL2 and Morin with DNA.

The interactions of Morin (2', 3, 4', 5, 7-pentahydroxyflavone) and its Zn-complex, ZnL2.3H2O [L = Morin (2'-OH group deprotonated)], with calf thymus DNA have been studied using fluorimetric and electrochemical methods. ZnL2.3H2O has different spectral characteristics and electrochemical behavior from that of Morin in the presence of DNA. Increasing fluorescence is seen for ZnL2.3H2O with DNA addition whereas decreased fluorescence is observed for Morin. An isosbestic point appears at 560 nm for the DNA-ZnL2.3H2O system with ethidium bromide (EB) addition while no isosbestic point is detectable for Morin. Quenching fluorescence is observed for DNA-EB system when ZnL2.3H2O is added whereas no quenched fluorescence is seen for DNA-EB system with Morin addition. The above results suggest that Morin and ZnL2.3H2O can both bind to DNA, but the binding mode is different. The complex binds to DNA mainly by intercalation, while Morin binds in a non-intercalating mode. The binding constant and binding site sizes are derived from electrochemical methods. For ZnL2.3H2O, the binding constant is 5.0 x 10(4) l mol(-1) at 20 degrees C, and the binding site size n(s) is 5.

DNA↗
PubMed2000

Speciation of key arsenic metabolic intermediates in human urine.

Biomethylation is the major human metabolic pathway for inorganic arsenic, and the speciation of arsenic metabolites is essential to a better understanding of arsenic metabolism and health effects. Here we describe a technique for the speciation of arsenic in human urine and demonstrate its application to the discovery of key arsenic metabolic intermediates, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), in human urine. The study provides a direct evidence in support of the proposed arsenic methylation pathway in the human. The finding of MMAIII and DMAIII in human urine, along with recent studies showing the high toxicity of these arsenicals, suggests that the usual belief of arsenic detoxification by methylation needs to be reconsidered. The arsenic speciation technique is based on ion pair chromatographic separation of arsenic species on a 3-micron particle size column at 50 degrees C followed by hydride generation atomic fluorescence detection. Speciation of MMAIII, DMAIII, arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) in urine samples is complete in 6 min with detection limits of 0.5-2 micrograms/L. There is no need for any sample pretreatment. The capability of rapid analysis of trace levels of arsenic species, which resulted in the findings of the key metabolic intermediates, makes the technique useful for routine arsenic speciation analysis required for toxicological and epidemiological studies.

Arsenic↗
PubMed2000

Ecotropic murine leukemia virus receptor is physically associated with caveolin and membrane rafts.

We used a Sindbis virus expression system to stably express a chimeric ecotropic murine leukemia virus (MLV) receptor gene, CAT1, fused to green fluorescent protein (gfp) in BHK cells. The chimeric gene was expressed on the cell surface and functioned as an MLV receptor. Using gfp as an epitope tag, we found that CAT1 cross-immunoprecipitated with caveolin, a cellular protein associated non-clathrin-coated endocytic vesicles. Biochemical studies showed that CAT1 copurified with caveolin in a detergent-insoluble membrane fraction that forms cholesterol-rich "rafts" on the cell surface. Disruption of rafts by methyl-beta-cyclodextrin, a drug that extracts cholesterol, reduced susceptibility to MLV without decreasing surface CAT1. The results indicate that association of the MLV receptor with cholesterol-rich rafts is important for an early step in virus infection.

Animals↗
PubMed2000

Palladium(II)-catalyzed tandem intramolecular aminopalladation of alkynes and conjugate addition. Synthesis of oxazolidinones, imidazolidinones, and lactams

[reaction: see text]Under the catalysis of a divalent palladium species, oxazolidinones, imidazolidinones, or lactams were conveniently obtained with high chemo- and stereoselectivity from the tandem intramolecular aminopalladation of alkynes, followed by insertion of alkenes, and protonolysis of the newly formed carbon-palladium bond.

Journal Article↗
PubMed2000

Structure-based design of an osteoclast-selective, nonpeptide src homology 2 inhibitor with in vivo antiresorptive activity.

Targeted disruption of the pp60(src) (Src) gene has implicated this tyrosine kinase in osteoclast-mediated bone resorption and as a therapeutic target for the treatment of osteoporosis and other bone-related diseases. Herein we describe the discovery of a nonpeptide inhibitor (AP22408) of Src that demonstrates in vivo antiresorptive activity. Based on a cocrystal structure of the noncatalytic Src homology 2 (SH2) domain of Src complexed with citrate [in the phosphotyrosine (pTyr) binding pocket], we designed 3',4'-diphosphonophenylalanine (Dpp) as a pTyr mimic. In addition to its design to bind Src SH2, the Dpp moiety exhibits bone-targeting properties that confer osteoclast selectivity, hence minimizing possible undesired effects on other cells that have Src-dependent activities. The chemical structure AP22408 also illustrates a bicyclic template to replace the post-pTyr sequence of cognate Src SH2 phosphopeptides such as Ac-pTyr-Glu-Glu-Ile (1). An x-ray structure of AP22408 complexed with Lck (S164C) SH2 confirmed molecular interactions of both the Dpp and bicyclic template of AP22408 as predicted from molecular modeling. Relative to the cognate phosphopeptide, AP22408 exhibits significantly increased Src SH2 binding affinity (IC(50) = 0.30 microM for AP22408 and 5.5 microM for 1). Furthermore, AP22408 inhibits rabbit osteoclast-mediated resorption of dentine in a cellular assay, exhibits bone-targeting properties based on a hydroxyapatite adsorption assay, and demonstrates in vivo antiresorptive activity in a parathyroid hormone-induced rat model.

Adsorption↗
PubMed2000

A facile highly regio- and stereoselective preparation of N-tosyl allylic amines from allylic alcohols and tosyl isocyanate via Palladium(II)-catalyzed aminopalladation-beta-heteroatom elimination

The high regio- and stereoselectivity have been obtained from the allylic substitution reaction catalyzed by palladium(II) species. From allylic alcohols, one-pot reaction with tosyl isocyanate followed by palladium(II)-catalyzed allylic substitution gives N-tosyl (E)-allylic amines in high yield. The substitution occurs only at the gamma-position of the 1- or 3-substituted allylic alcohols.

Journal Article↗