Biomedical subjects

Xi Ma

Publications and source records attributed to Xi Ma.

8 recordsLinked to original sources

PubMed2006

A novel stealth liposomal topotecan with amlodipine: apoptotic effect is associated with deletion of intracellular Ca2+ by amlodipine thus leading to an enhanced antitumor activity in leukemia.

The objectives of the present study were to define whether amlodipine induces apoptosis and what mechanism is involved in the process in human resistant and non-resistant leukemia cells following co-administration of stealth liposomal topotecan with amlodipine, a novel antiresistant liposomes developed by our institution. In three leukemias, K562, HL-60, and multidrug resistant (MDR) HL-60, cytotoxicity of topotecan was potentiated by amlodipine, while topotecan alone was resistant to MDR HL-60 cells. In two selected K562 or MDR HL-60 cells, the apoptotic effects were increased by addition of amlodipine, showing a dose-dependent manner. The activities of caspase 3 and 7 (marked as caspase 3/7), and caspase 8 were significantly activated by topotecan with amlodipine co-treated as the stealth liposomes. The deletions of intracellular Ca2+ stores induced by amlodipine correlated with the activated activities of caspase 3/7, or 8, respectively. In xenograft model with MDR HL-60 in nude mice, antitumor activity of stealth liposomal topotecan with amlodipine was significantly enhanced as compared to that of stealth liposomal topotecan or topotecan alone. In conclusion, apoptotic effect is associated with deletion of intracellular Ca2+ by amlodipine through activation of caspase 8 and then 3/7 activities. The enhanced antitumor activities by stealth liposomal topotecan with amlodipine are mainly due to the potentiating apoptotic effect and reversing the resistance by amlodipine. Stealth liposomal encapsulation of anticancer agent with a modulator may provide a novel strategy for improving the chemotherapeutic effects.

Amlodipine↗

PubMed2006

Abnormal expression of the programmed cell death 5 gene in acute and chronic myeloid leukemia.

To clarify whether expression of the programmed cell death 5 (PDCD5) gene in leukemic cells is abnormal, real-time quantitative reverse transcription polymerase chain reaction (RQ-RT-PCR) was used to examine its expression in marrow cells from leukemia patients. We found lower PDCD5 in both AML and CML marrow cells than in normal donor marrow cells. A negative correlation was found between relative levels of PDCD5 and BCR/ABL expression in all CML patients and in CML patients in the advanced phase. Treatment with the ABL tyrosine kinase inhibitor Imatinib mesylate increased PDCD5 expression in K562 and MEG-01 cells. These findings suggest that abnormal expression of PDCD5 in leukemia may be involved in the pathomechanism of AML and CML.

Adult↗

PubMed2005

Two single-nucleotide polymorphisms with linkage disequilibrium in the human programmed cell death 5 gene 5' regulatory region affect promoter activity and the susceptibility of chronic myelogenous leukemia in Chinese population.

PURPOSE: Chronic myelogenous leukemia (CML) is a disease characterized cytogenetically by the presence of the Philadelphia chromosome. Recent studies suggested that altered PDCD5 expression may have significant implications in CML progression. The aim of this study was to identify single-nucleotide polymorphisms (SNP) within the programmed cell death 5 (PDCD5) promoter region and show their functional relevance to PDCD5 expression as well as their genetic susceptibility to CML. EXPERIMENTAL DESIGN: One hundred twenty-nine CML subjects and 211 healthy controls were recruited for identification of SNPs and subsequent genetic analysis. Luciferase reporter assays were carried out to show the functional significance of the SNPs located in the promoter region to PDCD5 expression. Real-time quantitative PCR and Western blot analysis were done to determine the expression differences of PDCD5 in CML patients with different genotypes. RESULTS: Two SNPs were identified within the PDCD5 promoter. They are -27A>G and -11G>A (transcription start site as position 1), respectively. The complete linkage disequilibrium was found between these two polymorphisms. The frequencies of -27G+/-11A+ genotype and -27G/-11A allele were significantly higher in CML patients than in healthy controls (genotype: 26.36% versus 11.85%, chi2=11.75, P<0.01; allele: 13.57% versus 6.40%, chi2=9.48, P<0.01). Luciferase reporter assays revealed that the promoter with -27G/-11A had significantly lower transcriptional activity and could not be up-regulated after apoptotic stimulations compared with the promoter with -27A/-11G. PDCD5 expression analysis in mononuclear cells derived from CML patients and cell lines with different -27/-11 genotypes showed consistent results with the reporter assays. CONCLUSIONS: These data suggest that -27G/-11A is associated with reduced PDCD5 promoter activity and increased susceptibility to CML.

5' Flanking Region↗

PubMed2005

[Differential display technique and its progress].

Differential display technique is an important method to isolate differentially expressed gene. Comparing to other methods like representational difference analysis, suppression subtractive hybridization and serial analysis of gene expression, differential display technique is used in higher frequency. Since it was established in 1992, it has overcome many disadvantages and widened its practical fields through improvements and enhancements by global researchers. In this paper the principle and the main advantages and disadvantages of differential display technique were briefly introduced. Meanwhile, the four progressed aspects in designing primer, reducing false positives, identifying differentially expressed gene and techniques derived from DD were introduced in detail.

Blotting, Northern↗

PubMed2005

[Study on the current situation and influential factors of child neglect among aged 3-6 year-olds in the urban areas of China].

OBJECTIVE: Children aged 3 - 6 years in the urban areas of China were surveyed for the first time to find out the state of child neglect (CN) as well as the major relevant risk factors so as to provide evidence for developing intervention measures. METHODS: 1163 children (of whom 49.6% were males and 4.5% were minority nationality) were randomly sampled under multistage stratification, from 25 cities which representing 15 provinces of China. Based on the Child Neglect Norms used by China, prevalence of CN was identified and SPSS-Windows 11.0 was employed for statistical analysis. Scores, frequency/degrees, age, sex and 5 types (physical, emotional, educational, medical and safety) of CN on every group of the regions, were calculated. Multifactorial analysis was conducted through Binary Logistic Regression and multiple linear regression to determine the relevant risk factors. RESULTS: (1) The average degree of CN for the 3 - 6 year-olds was 42.2, with its prevalence as 28.0%. Degrees of CN for the groups of 3, 4, 5, 6-year-olds were 41.7, 42.2, 42.1 and 43.1 (F = 0.988, P > 0.05), with frequencies of 25.0%, 25.3%, 27.9% and 35.4% (chi(2) = 4.798, P > 0.05), respectively. Degrees for CN in males and females were 42.7 and 41.8 (F = 2.502, P > 0.05) with the frequencies as 32.6% and 23.7% (chi(2) = 6.585, P < 0.05), respectively. Degrees of CN for the five types were 39.4-43.4 with the frequencies as 5.1%-12.9%, respectively. No significant difference was found in the frequency of the types (with an exception on 'physical neglect') between males and females (P > 0.05). The highest frequency (42.9%) of CN was seen in the single-parent families and the lowest in large family with three generations (25.5%). (2) According to monofactorial chi(2) test, the possible risk factors of CN would include: educational background, occupation and decrease of income of the parents during last year, etc. (3) Binary Logistic regression analysis showed that the influential factors to the occurrence of CN would include: father's educational background, sex of the child and mother's occupation, etc. (4) Multiple linear regression showed that the influential factors to the degree of CN were: family structure, number of supporting family members, relationship between parents and children, etc. CONCLUSION: The degree and frequency of CN among children aged 3 to 6 in the urban areas of China were high but similar among the four age groups. Male children had a higher frequency of neglect than females, but with similar degree. Children in single-parent families had the highest frequency. The major influential factors of CN would include: educational background, occupation, family structure, family income of the parents which were similar to the results reported from foreign literature.

Child↗

PubMed2005

[Breeding of high-yield strain of taxol by mutagensis of protoplast and primary discussion of genetic differences between mutants and their parent strain].

The breeding of high-yield strain of taxol was performed by protoplast mutagenesis of strain NCEU-1 using ultraviolet radiation and combined treatment of UV and LiCl. The mutants UV40-19 and UL50-6 were obtained, which raised the taxol yield from 314.07 microg/L to 376.38 microg/L and 392.63 microg/L respectively. Genetic differences between the mutants UV40-19, UL50-6 and their parent strain were primarily compared through random amplified polymorphic DNA (RAPD) and isozyme technique. The results showed that the genetic differences were very obviously between the parent strain and its mutants and between the two mutants, which laid foundation of molecular mechanism for the study of genes related to the taxol biosynthesis and mutants for raising the taxol yield.

Ascomycota↗

PubMed2005

[Study on breeding up high-yield strain of taxol by protoplast mutagensis].

In order to obtain resistant mutants to nystatin, ultraviolet radiation and LiCl were used to mutagenize the protoplasts of taxol-producing fungi NCEU-1, and four positive mutants with high yield of taxol were screened out on nystatin flat. After further screening experiments on fermentation, a mutant strain--UL04-5 which was able to produce taxol with high yield and could be stably passed on in genetics was eventually found, it's ability to produce taxol was improved from 314.07 microg/L (strain NCEU-1) to 418.24 microg/L (strain U04-5).

Ascomycota↗

PubMed2002

Procoagulant effects of thrombolytic therapy in acute myocardial infarction.

OBJECTIVE: To examine the procoagulant effects of thrombolytic agent on hemostasis and study the role of hemostatic markers as predictors of clinical outcomes. METHODS: In the present study, eighteen patients with acute myocardial infarction (AMI) received 1.5 or 2.0 million U nonspecific urokinase (UK), or 70 approximately 80 mg fibrin-specific recombinant tissue plasminogen activator (rt-PA) and did not use heparin until 8 hours after intravenous injection of the above agents. Eight patients with AMI and without thrombolytic therapy were enrolled as controls. Coagulant and thrombolytic activity markers included thrombin-antithrombin III complex (TAT), D-dimer, fibrinogen (Fg), FMPV/Amax. All markers were determined before, immediately, 1, 2, 4 and 8 hours after the administration of thrombolytic agents respectively. RESULTS: Molecular marker of thrombin generation--TAT showed an activated coagulant state immediately after thrombolytic therapy. Level of TAT showed no significant changes between every two observed phases in controls. However, level of TAT increased significantly from 4.95 +/- 1.75 microg/L ( 4.63 +/- 1.37 microg/L) to 14.71 +/- 3.31 microg/L (14.25 +/- 2.53 microg/L) before and immediately after administration of thrombolytic agents UK (or rt-PA). There was significant difference between level of serum TAT of patients with and without thrombolytic therapy (P < 0.05). Patients achieving clinical reperfusion had lower TAT level than those failing in thrombolytic therapy, and higher FMPV/Amax level than controls. D-dimer, a surrogate of thrombolytic activity increased markedly and Fg significantly declined after thrombolytic therapy (P < 0.05). CONCLUSIONS: Thrombin generation occurred in plasma in response to excess fibrinolysis induced by thrombolytic therapy. Both urokinase and rt-PA had procoagulant action. This transient activation of the coagulant system might contribute to early reocclusion. These data provided the theoretical support for simultaneous administration of anticoagulant therapy with thrombolytic agents. These results also suggested that TAT might be useful in predicting clinical outcomes of patients treated with thrombolytic therapy for AMI.

Aged↗