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Biomedical subjects

Y Xu

Publications and source records attributed to Y Xu.

At least 253 records · Page 14Linked to original sources
PubMed2001

Synergistic effect of photodynamic therapy with hypericin in combination with hyperthermia on loss of clonogenicity of RIF-1 cells.

Hypericin is a natural photosensitizer produced in plants of the genus Hypericum. The compound exhibits a potent phototoxicity both in vitro and in vivo. In the present study we investigated the effect of hypericin-mediated PDT on hyperthermia (43 degrees C) in RIF-1 cell line. Our results demonstrated a synergistic effect on loss of cell clonogenicity when PDT exposure was followed immediately by hyperthermia. This synergistic effect was diminished by introducing an interval (at 37 degrees C) between the two treatments. Furthermore, it was found that combining PDT treatment with hyperthermia could significantly enhance the cell death by necrosis as indicated by morphological examination and significant loss of membrane integrity. Our data suggest that the common cell membrane damage by both PDT and hyperthermia is likely to be responsible for this synergistic effect.

Animals↗
PubMed2001

The effect of selective serotonin reuptake inhibitor treatment of panic disorder on emergency room and laboratory resource utilization.

BACKGROUND: While it has been well documented that patients with untreated panic disorder frequently utilize emergency room (ER) and laboratory services, no published data evaluate whether selective serotonin reuptake inhibitor (SSRI) treatment of patients with panic disorder is associated with decreased use of these services in the managed care organization setting. METHOD: A medical and pharmacy claims database representing individuals from several managed care organizations was used to analyze ER and laboratory resource utilization and cost for 120 patients with panic disorder (ICD-9-CM criteria) who received SSRI treatment. RESULTS: SSRI treatment was associated with a reduction in the mean number of ER and laboratory visits and costs in the 6-month period following therapy initiation compared with the 6-month period prior to therapy initiation (sertraline: visits, -79.5%; costs, -85.2%; p < .05; fluoxetine: visits, -25.0%; costs, -69.5%; p = NS; and paroxetine: visits, -8.6%; costs, -30.8%; p = NS). CONCLUSION: The results of the current study suggest that appropriate treatment of panic disorder may decrease unnecessary resource utilization for the medical symptoms associated with panic disorder.

Adolescent↗
PubMed2001

Protection of mammalian cells against chemotherapeutic agents thiotepa, 1,3-N,N'-bis(2-chloroethyl)-N-nitrosourea, and mafosfamide using the DNA base excision repair genes Fpg and alpha-hOgg1: implications for protective gene therapy applications.

Chemotherapeutic agents used in the treatment of cancer often lead to dose-limiting bone marrow suppression and may initiate secondary leukemia. N,N',N"-triethylenethiophosphoramide (thiotepa), a polyfunctional alkylating agent, is used in the treatment of breast, ovarian, and bladder carcinomas and is also being tested for efficacy in the treatment of central nervous system tumors. Thiotepa produces ring-opened bases such as formamidopyrimidine and 7-methyl-formamidopyrimidine, which can be recognized and repaired by the formamidopyrimidine glycosylase/AP lyase (Fpg) enzyme of Escherichia coli. Using this background information, we have created constructs using the E. coli fpg gene along with the functional equivalent human ortholog alpha-hOgg1. Although protection with the Fpg protein has been previously observed in Chinese hamster ovary cells, we demonstrate significant (100-fold) protection against thiotepa using the E. coli Fpg or the human alpha-hOgg1 cDNA in NIH3T3 cells. We have also observed a 10-fold protection by both the Fpg and alpha-hOgg1 transgenes against 1,3-N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU) and, to a lesser extent, mafosfamide (2-fold), an active form of the clinical agent cyclophosphamide. These latter two findings are novel and are particularly significant since the added protection was in an O(6)-methylguanine-DNA methyltransferase-positive background. These results support our general approach of using DNA base excision repair genes in gene therapy for cellular protection of normal cells during chemotherapy, particularly against the severe myelosuppressive effect of agents such as thiotepa, BCNU, and cyclophosphamide.

3T3 Cells↗
PubMed2001

Influences of metal concentration in phytoplankton and seawater on metal assimilation and elimination in marine copepods.

Radiotracer experiments were conducted to examine the influence of the concentration of Cd, Se, and Zn in ingested phytoplankton (dinoflagellate Prorocentrum minimum and diatom Thalassiosira weissflogii) and in ambient seawater on metal assimilation and elimination efficiencies of three marine copepods, Acartia spinicauda, Paracalanus aculeatus, and Calanus sinicus. The assimilation efficiencies (AEs) decreased by 1.7 to 2.0 times, 1.4 to 4.1 times, and 1.3 to 2.2 times in the copepods with an increase in metal concentration in ingested algae by 16 to 84 times, 14 times, and 45 to 153 times, for Cd, Se, and Zn, respectively. However, the physiologic turnover rate constant was relatively independent of the metal concentration in copepods. No evidence was found of any interaction between Cd and Zn in their assimilation by copepods. Assimilation efficiencies of Cd were higher in copepods feeding on the dinoflagellate P. minimum, whereas the AEs of Zn were higher in copepods feeding on the diatom T. weissflogii. Differences in metal distribution in algal cytoplasm at different ambient metal concentrations may be partially responsible for the observed influence of metal concentration in algal cells on metal assimilation in copepods. However, metal desorption within the gut of the copepod may have little influence on metal assimilation, as a result of the short gut residence time of food particles and the neutral gut pH. Our study also indicated that the ingestion rate of copepods was reduced by a higher concentration of Cd and Se, but was not affected by Zn concentration in the food particles. Consequently, partial regulation of metal trophic transfer in response to increasing metal contamination may be achieved by a change in metal assimilation efficiency and the ingestion activity of the copepod, but not by changes in metal turnover rates from the animals.

Animals↗
PubMed2001

Comparison of global brain gene expression profiles between inbred long-sleep and inbred short-sleep mice by high-density gene array hybridization.

BACKGROUND: Inbred long-sleep (ILS) and short-sleep (ISS) mice show significant central nervous system-mediated differences in sleep time for sedative dose of ethanol and are frequently used as a rodent model for ethanol sensitivity. In this study, we have used complementary DNA (cDNA) array hybridization methodology to identify genes that are differentially expressed between the brains of ILS and ISS mice. METHODS: To carry out this analysis, we used both the gene discovery array (GDA) and the Mouse GEM 1 Microarray. GDA consists of 18,378 nonredundant mouse cDNA clones on a single nylon filter. Complex probes were prepared from total brain mRNA of ILS or ISS mice by using reverse transcription and 33P labeling. The labeled probes were hybridized in parallel to the gene array filters. Data from GDA experiments were analyzed with SQL-Plus and Oracle 8. The GEM microarray includes 8,730 sequence-verified clones on a glass chip. Two fluorescently labeled probes were used to hybridize a microarray simultaneously. Data from GEM experiments were analyzed by using the GEMTools software package (Incyte). Differentially expressed genes identified from each method were confirmed by relative quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: A total of 41 genes or expressed sequence tags (ESTs) display significant expression level differences between brains of ILS and ISS mice after GDA, GEM1 hybridization, and quantitative RT-PCR confirmation. Among them, 18 clones were expressed higher in ILS mice, and 23 clones were expressed higher in ISS mice. The individual gene or EST's function and mapping information have been analyzed. CONCLUSIONS: This study identified 41 genes that are differentially expressed between brains of ILS and ISS mice. Some of them may have biological relevance in mediation of phenotypic variation between ILS and ISS mice for ethanol sensitivity. This study also demonstrates that parallel gene expression comparison with high-density cDNA arrays is a rapid and efficient way to discover potential genes and pathways involved in alcoholism and alcohol-related physiologic processes.

Alternative Splicing↗
PubMed2001

Nuclear- and chloroplast-microsatellite variation in A-genome species of rice.

Simple sequence length polymorphism analysis was carried out to reveal microsatellite variation and to clarify the phylogenetic relationships among A-genome species of rice. Total DNA from 29 cultivars (23 Oryza sativa and 6 O. glaberrima) and 30 accessions of wild A-genome species (12 O. rufipogon, 5 O. glumaepatula, 2 O. longistaminata, 6 O. meridionalis, and 5 O. barthii) was used as a template for PCR to detect 24 nuclear and 10 chloroplast microsatellite loci. Microsatellite allelic diversity was examined based on amplified banding patterns. Microsatellites amplified clearly in all 59 accessions, with an average of 18.4 alleles per locus. The polymorphism information content (PIC) value ranged from 0.85 to 0.94, with an average of 0.89. At the species level, high average PIC values were observed in O. sativa (0.79) and O. rufipogon (0.80). For chloroplast microsatellites, the average number of alleles per locus and the average PIC value were 2.9 and 0.38, respectively. While the magnitude of diversity was much greater for nuclear microsatellites than for chloroplast microsatellites, they showed parallel patterns of differentiation for each taxonomic group. Using the ratio of common alleles (estimated as size of amplified fragments) as a similarity index, the average percentages of common microsatellite alleles were calculated between taxa. For both nuclear and chloroplast microsatellites, O. sativa showed the highest similarity values to O. rufipogon, and O. glaberrima was most similar to O. barthii. These data support previous evidence that these cultivars originated from the corresponding wild ancestral species.

Alleles↗
PubMed2001

Integrating medical applications in an open architecture through generic and reusable components.

Allowing exchange of information and cooperation among network-wide distributed and heterogeneous applications is a major need of current health care information systems. It forces the development of open and modular integration architectures. Major issues in the development include defining a flexible and robust federation model, developing interaction and communication facilities as well as the mechanism insuring semantic interoperability. We developed generic and reusable software components to ease the construction of any integration platform. The Pilot and the Mediator Service components facilitate the execution of services and the meaningful transformation of information. They have been tested in the context of the SynEx European project to construct a multi-agents based integration architecture. The possibility of such architectures to take into account the issue of semantic interoperability is further discussed.

Computer Communication Networks↗
PubMed2001

Computerization of guidelines: towards a "guideline markup language".

Medical decision making is one of the most difficult daily tasks for physicians. Guidelines have been designed to reduce variance between physicians in daily practice, to improve patient outcomes and to control costs. In fact, few physicians use guidelines in daily practice. A way to ease the use of guidelines is to implement computerised guidelines (computer reminders). We present in this paper a method of computerising guidelines. Our objectives were: 1) to propose a generic model that can be instantiated for any specific guidelines; 2) to use eXtensible Markup Language (XML) as a guideline representation language to instantiate the generic model for a specific guideline. Our model is an object representation of a clinical algorithm, it has been validated by running two different guidelines issued by a French official Agency. In spite of some limitations, we found that this model is expressive enough to represent complex guidelines devoted to diabetes and hypertension management. We conclude that XML can be used as a description format to structure guidelines and as an interface between paper-based guidelines and computer applications.

Decision Making, Computer-Assisted↗
PubMed2001

[Determination of sarsasapogenin in "tian dong" by TLCS].

This paper reported the determination of sarsasapogenin in 12 samples from 7 species and varieties of Asparagus genus whose commercial name is "Tian-Dong"(Radix Asparagi), Asparagus cochichinensis(Lour.) Merr, A. cochichinensis (lour.) Merr. var. gaudichaudianus (Kunth) X. D. Luo and G. J. Xu, A. taliensis Wang et Tang, A. munitus Wang et Tang, A. myriacanthus Wang et S. C. Chen, A. meioclados Levl and A. trichoclados (Wang et Tang) Wang et S. C. Chen by TLCS. The results showed that it was no pertinence between content of sarsaspogenin with the species, and the content of sarsasapogenin in the tuberous roots was inverse ratio with the commercial grande in same species.

Aspalathus↗
PubMed2001

[The association of methylenetetrahydrofolate reductase gene polymorphism with nephropathy in type 2 diabetes mellitus in Chinese].

OBJECTIVE: To evaluate the role of methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms in Chinese patients with type 2 diabetes mellitus and diabetic nephropathy(DN). METHODS: 85 type 2 diabetes mellitus patients and 57 controls were recruited in the study. MTHFR genetic C677T polymorphism was determined with PCR-restriction fragment length polymorphisms (RFLP). Plasma total homocysteine level was measured using high-performance liquid chromatography (HPLC) with fluorescence detection. RESULTS: The frequency of MTHFR TT homogenetic type and CT heterogenetic type and allele T(28.21%, 51.28%, 53.85%) was significantly higher in type 2 diabetes mellitus with diabetic nephropathy group than those without nephropathy (19.57%, 28.26%, 33.70%) or normal controls (17.54%, 28.07%, 31.58%). However, there was no significant difference of MTHFR genotype and allele frequency between type 2 diabetes mellitus without nephropathy and normal controls. The presence of T allele appeared to have a stronger association with the development of diabetic nephropathy. The odds ratio was 2.30 and the 95% confidence interval was 1.24-4.26. Moreover, plasma homocysteine levels were markedly higher in patients with TT or CT genotype than those in patients with CC genotype. CONCLUSIONS: MTHFR gene C677T mutation associated with a predisposition to increased plasma homocysteine levels may represent a genetic risk factor for diabetic nephropathy in Chinese type 2 diabetes mellitus.

Adult↗
PubMed2001

Effects of dexamethasone on Flt3 receptor expression and proliferation induced by recombinant human Flt3 ligand in malignant hematopoietic cells.

AIM: To investigate the effect of dexamethasone (DXM) on the expression of Flt3 receptor and the proliferation mediated by recombinant human Flt3 ligand (rhFL) in leukemia cells. METHODS: Eighteen malignant hematopoietic cell lines and 10 leukemia blasts from leukemia patients were examined by flow cytometry for the expression of Flt3 receptor before and after incubation with DXM 0.1 micromol/L for 24 h. The effect of DXM on the proliferation of malignant hematopoietic cells was measured by MTT assay. RESULTS: (1) Expression of the Flt3 receptor in malignant hematopoietic cell lines and leukemia blasts was widespread and extremely heterogeneous; (2) The presence of receptor on the surface of malignant hematopoietic cell didn't necessarily imply a significant ligand-induced response, at least in terms of proliferation. Conversely, some Flt3 receptor-negative malignant hematopoietic cells responded to rhFL; (3) DXM down-regulated the expression of Flt3 receptor and inhibited the proliferation induced by rhFL in some malignant hematopoietic cell lines and fresh leukemia cells. CONCLUSION: DXM may down-regulate the expression of Flt3 receptor on the surface of malignant hematopoietic cells and inhibit the proliferation induced by rhFL. A combination of rhFL and DXM may serve to control hematopoietic defects in malignant hematopoietic diseases.

Antineoplastic Agents, Hormonal↗
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

[Association of beta 3-adrenergic receptor gene with obesity in patients with type 2 diabetes mellitus].

OBJECTIVE: To investigate the association between the mutation of beta 3-adrenergoc receptor gene and obesity in patients with type 2 diabetes. METHODS: Body mass, waist-hip ratio, blood pressure and blood lipids were measured in 154 type 2 diabetic patients. Polymerase chain reaction and the restriction fragment length polymorphism analysis were used to determine the wild, heterozygous and homozygous forms of beta 3-adrenergoc receptor gene. RESULTS: The frequency of the Trp64Arg mutation was 42.5% and the frequency of Arg64 allele was 22.6%. The mutation frequency of the genetic types was significantly different between the obese and non-obese type 2 diabetes mellitus patients. The body mass, systolic blood pressure, diastolic blood pressure, HDL-cholesterol were significantly different, when those with Trp64Arg heterozygous were compared with those with Trp64 homozygous. CONCLUSIONS: The genetic mutation of beta 3-adrenegoc receptor in patients with type 2 diabetes is probably related to obesity.

Adult↗
PubMed2001

[Clinicopathological and molecular genetic analysis in Chinese typical hereditary nonpolyposis colorectal cancer pedigrees].

OBJECTIVE: To investigate the clinicopathological and molecular genetic characteristics of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) pedigrees. METHODS: Four Chinese HNPCC pedigrees were studied using microdissection, microsatellite instability analysis, immunohistochemistry staining and direct DNA sequencing for hMSH2 and hMLH1 genes. RESULTS: All five tumor tissues from 4 probands showed high level of microsatellite instability at more than 2 loci(RER + phenotype). Three of 4 cases lost hMSH2 protein expression and one case showed no hMLH1 protein expression. Three pathological germline mutations (2 on hMSH2 and 1 on hMLH1) were identified. CONCLUSIONS: Chinese typical HNPCC kindreds showed relatively frequent germline mutations of mismatch repair genes. Microsatellite instability analysis and immunohistochemistry staining might be the effective screening methods before direct DNA sequencing for the detection of mismatch repair genes. It is necessary to establish clinical criteria and molecular diagnostic strategies more suitable for Chinese HNPCC kindreds.

Adult↗
PubMed2001

[A study of the effect of protein kinase C on the expression of nitric oxide synthase mRNA in pulmonary artery smooth muscle in hypoxia].

OBJECTIVE: To investigate the effect of PKC on the expression of NOS mRNA in pulmonary artery smooth muscle cell(PASMC) in hypoxia. METHODS: RT-PCR was used to detect the expression of PKC alpha mRNA in PASMC of procine, and the effect of activator and inhibitor of PKC on the expression of cNOS mRNA in PASMC. RESULTS: The expression of PKC-alpha mRNA was higher in the PASMC in 48 and 72 h of hypoxia(P < 0.01), and the expression of cNOS mRNA was lower(P < 0.01). The expression of cNOS mRNA was significantly negatively correlated with the expression of PKC-alpha mRNA(P < 0.001). PMA, an agonist of PKC could reduce the expression of cNOS mNRA in hypoxia, while RO 31-8220, an inhibitor of PKC could inhibit it and enhance the expression of NOS mRNA(P < 0.01). The activator of NO, L-Arg and inhibitor, L-NAME had no effect on expression of PKC-alpha mRNA. CONCLUSION: The PKC can inhibit the expression of cNOS mRNA in PASMC in hypoxia. The effect of PKC in hypoxic pulmonary hypertension may be made by inhibiting the expression of cNOS mRNA and modulating NO. The site of the effect of PKC may be in upstream of NO. The mechanism of it needs to be studied further.

Animals↗
PubMed2001

Allogeneic peripheral blood stem cell transplantation for leukemia.

OBJECTIVE: To observe engraftment kinetics, the incidence and severity of graft-versus-host disease (GVHD), and clinical outcome on 40 recipients undergoing allogeneic peripheral blood stem cell transplantation (allo-PBSCT). METHODS: From June 1997 to May 1999, forty leukemia patients with a median age of 35 years underwent allo-PBSCT. PBSC were mobilized with G-CSF at a dose of 5 micrograms/kg s.c. every 12 hours for 5 days. A median of 7.7 (2.0-16.8) x 10(6) CD34+ cells/kg was infused into the recipients. Busulfan-cyclophosphamide (BU-CY) was used as the conditioning regimen. All patients received cyclosporine A and either methotrexate (n = 34) or methylprednisolone (n = 6) for GVHD prophylaxis. RESULTS: Engraftment of neutrophils and platelets was achieved at a median of 13 days (9-28 days) and 12 days (7-60 days) respectively. Patients receiving > or = 4 x 10(6) CD34+ cells/kg or given G-CSF post transplant had significantly accelerated neutrophil and platelet engraftment. Acute GVHD occurred in 17 of 40 patients (42.5%), with grade II-IV acute GVHD in 10 patients (25%). Chronic GVHD developed in 21 (9 extensive, 12 limited) out of 30 evaluable patients (21/30, 70%) with a median follow up of 380 days (180-900 days). Transplant related mortality was 17.5% and the relapse rate was 10%. The probability of leukemia free survival at 3 years was 72.5%. CONCLUSION: Allo-PBSCT can provide rapid hematopoietic reconstitution without an increased incidence of acute GVHD, but may be associated with a high risk of chronic GVHD.

Adult↗
PubMed2001

Cordotomy for bilateral cord abductal paralysis.

OBJECTIVE: To investigate the clinical effects of cordotomy on bilateral cord abductal paralysis. METHODS: With unilateral cordotomy, we treated 4 patients with bilateral cord paralysis whose glottis size was about 2.0 mm to 2.5 mm. They were followed up for over one year. RESULTS: One week after surgery, the tracheotomy tubes of all 4 patients were plugged and no dyspnea occurred during rest and mild action. Their voices were more hoarse than before surgery. After 3 months, the tracheotomy tubes were successfully decannulated, and in the following one year, their respiration was normal and then speech was clear, although their voices were still a little hoarse. CONCLUSION: We suggest that cordotomy be one option in the treatment of bilateral cord abductal paralysis.

Adult↗