DAMBE: software package for data analysis in molecular biology and evolution

DAMBE (data analysis in molecular biology and evolution) is an integrated software package for converting, manipulating, statistically and graphically describing, and analyzing molecular sequence data with a user-friendly Windows 95/98/2000/NT interface. DAMBE is free and can be downloaded from http://web.hku.hk/~xxia/software/software.htm. The current version is 4.0.36.

Epidemiological investigation of Histoplasma capsulatum infection in China

OBJECTIVE

To provide reliable information concerning the presence or the absence of Histoplasma capsulatum (H. capsulatum) infection in China, and data concerning this respect.

METHODS

Three hundred normal people and 435 hospitalized patients, who lived in Hunan and Jiangsu provinces, and the Xinjiang Autonomous Region, were tested with yeast-phase histoplasmin (ALK/Berkerley Biologicals Laboratories, USA) and human pure protein derivative of tuberculin (PPD) on the volar surface of the forearm. Any reaction to the antigens over 5.0 mm in diameter of induration at 48-72 hours was considered positive.

RESULTS

A total of 138 subjects (18.8%) in 735 patients reacted to histoplasmin with 5.0-45.0 (9.1 +/- 4.3) mm indurations. Significant differences of positive skin reaction rates in normal subjects were found in Hunan, Jiangsu and Xinjiang (8.9% vs 15.1% vs 2.1%). The overall positive rate of patients was 25.5%. Patients with tuberculosis [31.7% (78/246)] had a significantly higher positive skin reaction rate in comparison with those suffering from pneumonia [17.7% (11/62)], lung cancer [20.9% (9/43)], chronic obstructive pulmonary disease [17.3% (9/52)] and other diseases [12.5% (4/32)] (P < 0.01). Of 562 cases, 292 cases (52.0%) reacted to PPD with indurations of 5-50 (13.7 +/- 4.9) mm in diameter, 63 cases (11.2%) reacted to both histoplasmin and PPD, while 38 cases (6.9%) reacted to histoplasmin but not to PPD.

CONCLUSIONS

The data suggest that there is H. capsulatum herd infection in China. The infection rate in Southeast China is higher than that in the Northwest, and the infection rate of patients with pulmonary tuberculosis is higher than that of normal persons and other pneumonopathy patients.

Microscopic theory of heterogeneity and nonexponential relaxations in supercooled liquids

Recent experiments show that supercooled liquids around the glass transition temperature are "dynamically heterogeneous" [H. Sillescu, J. Non-Cryst. Solids 243, 81 (1999)]. Such heterogeneity is expected from the random first order transition theory of the glass transition. Using a microscopic approach based on this theory, we derive a relation between the departure from Debye relaxation as characterized by the beta value of a stretched exponential response function, phi(t) = e(-(t/tau(KWW))beta), and the fragility of the liquid. The beta value is also predicted to depend on temperature and to vanish as the ideal glass transition is approached at the Kauzmann temperature.

The interaction of trichosanthin with supported phospholipid membranes studied by surface plasmon resonance

Trichosanthin (TCS) is a toxic protein isolated from a Chinese herbal medicine, the root tuber of Trichosanthes kirilowii Maximowicz of the Curcurbitaceae family. It is now used in China to terminate early and mid-trimester pregnancies. The ribosome inactivating property is thought to be account for its toxicity; it can inactivate the eukaryotic ribosome through its RNA N-glycosidase activity. The interactions of TCS with biological membrane is thought to be essential for its physiological effect, for it must get across the membrane before it can enter the cytoplasm and exert its RIP function. In the present work, the interaction of TCS with supported phospholipid monolayers is studied by surface plasmon resonance. The results show that electrostatic forces dominate the interaction between TCS and negatively charged phospholipid containing membranes under acid condition and that both the pH value and the ionic strength can influence its binding. It is proposed that, besides electrostatic forces, hydrophobic interaction may also be involved in the binding process.

[The Immunophenotypical features of t (8; 21) (q22; q22) acute myeloid leukemia]

OBJECTIVE

To study the predictive value of immunophenotypical features in t (8; 21) (q22; q22) acute myeloid leukemia (AML).

METHODS

Morphological/cytochemical, flow cytometric immunophenotyping, cytogenetic analyses (MIC) and RT-PCR were performed in 294 previously untreated AML.

RESULTS

(1) In 294 AML patients, t (8; 21) AML were 21.8% (64); in AML-M(2), t (8; 21) AML were 54.7%; and in t (8; 21) AML, AML-M(2) were 81.3%. (2) Compared with control group, CD(19) and CD(34) expressions were higher, and CD(33) expression was lower (P < 0.001) in t (8; 21) AML. (3) If the cut-off value of CD(19) positive was >or= 20%, CD(19) positive rate was 13.6% (40/294) in AML, and 50% (32/64) and 3.5% (8/230) (P < 0.001) in t (8; 21) AML and control group. (4) CD(19)(+) and/or CD(34)(+) t (8; 21) AML accounted for 90.6% (58/64) of t (8; 21) AML and CD(19)(-)/CD(34)(-) for 9.6% (6/64).

CONCLUSION

In t (8; 21) AML, especially M(2)/t (8; 21), CD(19) and CD(34) expressions were high. CD(19) was one of predictive markers of t (8; 21) AML.

[Cloning and sequence analysis of truncated S gene from circulation of patients with chronic hepatitis B virus infection]

OBJECTIVE

To find different mutated status of HBV DNA in circulation from chronic HBV patients.

METHODS

Specially designed primers and polymerase chain reaction method were applied to amplify the whole S gene of HBV from the serum of 2 patients. After being sequenced, 4 clones were compared with HBV adr subtype (China strain) to identify the mutant sites.

RESULTS

Sequencing results implied that there was a truncated large/middle S gene in the serum of the patients. Besides that, HBsAg and HBV DNA polymerase defective clones were also detected.

CONCLUSIONS

Truncated middle S gene is found in the circulation of patients with chronical HBV infection, suggestive of a poor prognosis.

AMADA: analysis of microarray data

SUMMARY

AMADA is a Windows program for identifying co-expressed genes from microarray data. It performs data transformation, principal component analysis, a variety of cluster analyses and extensive graphic functions for visualizing expression profiles.

Ebp1, an ErbB-3 binding protein, interacts with Rb and affects Rb transcriptional regulation

Ebp1, an ErbB-3 binding protein, inhibits the proliferation and induces the differentiation of human breast cancer cells. The mechanisms of these effects are unknown. Rb, the product of the retinoblastoma gene, is an important modulator of cell cycle progression and cellular differentiation. We report that Rb is a binding target for Ebp1. Ebp1 was localized to both the nucleus and the cytoplasm of logarithmically growing AU565 breast cancer cells and HeLa cells as determined by confocal immunofluorescent microscopy. Ebp1 was present in Rb immunoprecipitates derived from AU565 breast cancer cells. GST-Rb also bound endogenous Ebp1. Using GST-Ebp1 constructs, we determined that the 72 C-terminal amino acids of Ebp1 were sufficient to bind Rb. Dephosphorylation of Ebp1 enhanced the interaction of Ebp1 with Rb. The overexpression of Ebp1 in MCF-7 and AU565 (Rb(+)) cells inhibited the activity of the E2F1 regulated cyclin-E promoter. Ebp1 bound E2F1 indirectly via Rb in lysates of MCF-7 cells. The interaction of Ebp1 with Rb may prove to be an important mechanism of Ebp1 induced changes in cell proliferation and differentiation.

[Microbial degradation of polychlorinated dibenzo-p-dioxins]

PCDDs-degrading bacterial strains were isolated from soil and oxic-sediments polluted by PCDDs. One of them was identified as Pseudomonas sp. EE41. They are capable of growing on and degrade mono- and di-chlorinated dibenzo-p-dioxins as a sole carbon source. The biodegradability of TrCDD and TCDD can be enhanced through primary nutrient of co-metabolism of o-CDB, thus, 1,2,3-TrCDD and 2,3,7,8-TCDD were degraded by 33% (at the concentration of 1.2 mg/L, within 3 weeks) and 37.8% (at the concentration of 0.1 mg/L, within 3 weeks) respectively. Most highly chlorinated dibenzo-p-dioxins (P-CDD, H6-, H7-CDD and OCDD) tested in this study were accumulated in bacterial cells, but could not be degraded.

Electrochemical nanostructuring with ultrashort voltage pulses

The application of nanosecond voltage pulses to electrodes provides three ways to conduct local electrochemistry on the micro- to nanometer scale. (1) The finite charging time of the double-layer capacity allows the machining of three-dimensional microstructures. (2) In an electrochemical scanning tunneling microscope, reactions are confined to the tunneling region, due to the depletion of the electrolyte in the tip--surface gap. (3) Ordering processes, following very fast electrochemical reactions, lead to unconventional island patterns on a surface.

Mitomycin C Reduces Haze Formation in Rabbits After Excimer Laser Photorefractive Keratectomy

PURPOSE

To investigate the effects of mitomycin C on haze after photorefractive keratectomy (PRK).

METHODS

Twenty of 24 rabbits underwent bilateral 193-nm excimer laser PRK to correct -10.00 D of myopia; the remaining four rabbits were not operated (no PRK group). The right eyes of the 20 rabbits were treated with 0.02% mitomycin C during surgery (PRK+MMC group) and the left eyes did not receive 0.02% mitomycin C (PRK alone group). Clinical and histopathologic examinations were performed.

RESULTS

The most severe haze in the PRK alone group after PRK reached grade 3; the PRK+MMC group did not exceed grade 1 haze. Statistically significant differences were found between the PRK+MMC and PRK alone groups from week 2 to week 26 after treatment (P<.01). Epithelial thickening appeared for 26 weeks in both PRK groups; no statistically significant differences were found between the two PRK groups (P>.05). A marked reduction of keratocytes in the anterior stroma of the PRK+MMC group was observed. At week 1, 2, and 4 after PRK, keratocytes of the PRK+MMC group were only 3.1+/-2.6, 6.8+/-4.7, and 12.4+/-5.7 keratocytes x 10(4)/microm2, respectively, while those of the PRK alone group were 41.2+/-80, 42.3+/-7.8, and 40.0+/-3.3 keratocytes x 10(4)/microm2, respectively. There were statistically significant differences between the two groups (P<.001).

CONCLUSION

A single intraoperative application of topical mitomycin C during PRK in rabbits reduced corneal haze by inhibiting the proliferation of keratocytes.

[Improvement of combination chemotherapy tolerance of human umbilical cord blood CD(34)(+) cells transducted with double drug resistance genes by a bicistronic retroviral vector]

OBJECTIVE

To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human aldehyde dehydrogenase class 3 (ALDH3) and multidrug resistance gene (MDR1) could increase resistance to 4-hydroxycyclophosphamide (4-HC) and P-glycoprotein effluxed drugs.

METHODS

A bicistronic retroviral vector G1Na-ALDH3-IRES-MDR1 cDNA was constructed and transfected the packaging cell lines GP + E86 and PA317 by LipofectAMINE method, using the medium containing VCR and 4-HC for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, cord blood CD(34)(+) cells were enriched with a high-gradient magnetic cell sorting system (MACS), and then repeatedly transfected with supernatant of retrovirus containing human ALDH3 and MDR1 cDNA under stimulation of hematopoietic growth factors. PCR, RT-PCR, Southern blot, Northern blot, FACS and MTT assay were used to evaluate the transfection and expression of the double genes.

RESULTS

The purity of cord blood CD(34)(+) cells was approximately 91% and the recovery rate was 72%. The highest titer of recombinant amphotropic retrovirus in the supernatant was up to 6.5 x 10(5) CFU/ml. The efficiency of gene transduction was 18%, 20% and 16.7% tested by colony formation, PCR and FACS, respectively. Rhodamine 123 efflux showed 16% transduced cells with P-gp function. No helper virus was found by both nested PCR and rescue assay. The MTT analysis showed a 3.5 to 6.8-fold increase of resistance of transducted cells to cyclophosphamide and P-glycoprotein effluxes drug as compared with the nontransduced cells.

CONCLUSION

The efficiency and co-expression of this dual genes transfer system provided a foundation for ameliorating combination chemotherapy toxicity in clinical trial.

A novel alternative approach for prediction of radiation response of squamous cell carcinoma of head and neck

Accurate prediction of human tumor response to radiation therapy and concomitant chemoradiation would be an important tool to assist the physician in making recommendations for tumor treatment. Most of the studies that define the molecular markers for prediction of radiation response are based on the observation of gene expression using immunostaining, Northern blot, or Western blot analysis of a single or several genes. The results vary among different studies, and some results are contradictory. However, the studies agree that the change in expression of the tumor-related gene affects the radiation response. In this study, we explored a novel approach to predict the radiation response of human tumor using Atlas human cancer 1.2 cDNA array to analyze the expression profile of 1187 tumor-related genes in radiation-resistant and radiation-sensitive tissues. Sixty tumor-related genes were selected as predictors of radiation response of squamous cell carcinoma of the head and neck. Using the expression intensity of these 60 tumor-related genes, in combination with cluster analysis, we successfully predicted the radiation identity of two tumor samples.

Intramuscular electroporation delivery of IFN-alpha gene therapy for inhibition of tumor growth located at a distant site

Although electroporation has been shown in recent years to be a powerful method for delivering genes to muscle, no gene therapy via electro-injection has been studied for the treatment of tumors. In an immunocompetent tumor-bearing murine model, we have found that delivery of a low dose of reporter gene DNA (10 microg) to muscle via electroporation under specific pulse conditions (two 25-ms pulses of 375 V/cm) increased the level of gene expression by two logs of magnitude. Moreover, administration of 10 microg of interferon (IFN)-alpha DNA plasmid using these parameters once a week for 3 weeks increased the survival time and reduced squamous cell carcinoma (SCC) growth at a distant site in the C3H/HeJ-immunocompetent mouse. IFN-alpha gene therapy delivered to muscle using electroporation demonstrated statistically significant (P < 0.05) therapeutic efficacy for treating SCC located at a distant site, compared with interleukin (IL)-2 or endostatin gene, also delivered by electro-injection. The increased therapeutic efficacy was associated with a high level and extended duration of IFN-alpha expression in muscle and serum. We also discovered that the high level of IFN-alpha expression correlated with increased expression levels of the antiangiogenic genes IP-10 and Mig in local tumor tissue, which may have led to the reduction of blood vessels observed at the local tumor site. Delivery of increasing doses (10-100 microg) of IFN-alpha plasmid DNA by injection alone did not increase antitumor activity, whereas electroporation delivery of increasing doses (10-40 microg) of IFN-alpha plasmid DNA did increase the survival time. Our data clearly demonstrate the potential utility of electroporation for delivery of gene therapy to muscle for the treatment of residual or disseminated tumors.

A chromosome 15 quantitative trait locus controls levels of radiation-induced jejunal crypt cell apoptosis in mice

Jejunal crypt cells undergo apoptosis in response to ionizing radiation exposure. In mice the number of cells deleted by apoptosis is determined by several factors including the dose of radiation, the time of day the apoptosis level is quantified, and the strain of mouse irradiated. We previously found that the difference in radiation-induced apoptosis levels between C57BL/6J (B6) and C3Hf/Kam (C3H) mice is controlled by multiple genes, and this set of genes is distinct from that controlling thymocyte apoptosis levels in the same strain combination. Here, we report that a new quantitative trait locus on chromosome 15, Rapop5, partly accounts for the murine strain difference in susceptibility to radiation-induced jejunal crypt cell apoptosis. In addition, we show sexual dimorphism in the extent of radiation-induced jejunal crypt cell apoptosis, with female mice having higher levels.

[Study on drug resistance of Mycobacterium tuberculosis in different age group]

OBJECTIVE

To investigate drug resistance of Mycobacterium tuberculosis in different age group in recent five years, and to analyze the trends of drug resistance at present.

METHODS

1 948 cases of pulmonary tuberculosis with culture-positive were divided into youth group (18 approximately 39 years), middle age group (40 approximately 59 years) and old age group (>/=60 years). All of the strains of Mycobacterium tuberculosis were tested for resistance to INH, RFP, SM and EMB by the absolute concentration method.

RESULTS

The rate of primary drug resistance in youth group was 36.1%, in middle age group 46.8%, in old age group 40.2%, there were no significant differences among them (P > 0.05). The rate of acquired drug resistance was higher in youth group than that in old age group (P = 0.019 6). The primary resistance rate to RFP in middle age group was 10.6%, much higher than that in youth group and in old age group. The acquired resistance rate to RFP in youth group was 63.6%, higher than that in middle age group and in old age group. The rate of primary multi-drug resistance in middle age group was 5.3%, higher than that in youth group (P = 0.011 2) and in old age group (P = 0.008 5). The rate of acquired multi-drug resistance in youth group was 55.2%, higher than that in middle age group (P = 0.031 9) and in old age group (P < 0.001). The drug resistance rate in using drugs 1 approximately 3 months group was 58.7%, higher than that in never using drug group (P < 0.001) and in using drugs < 1 month group (P = 0.047 2). The drug resistance rate had no significant difference between never using drug group and using drugs < 1 month group. The emergency of drug resistance in youth group was fastest in all age groups.

CONCLUSIONS

Primary drug resistance or acquired drug resistance varies in different age group. It is suggested that the surveillance of drug resistance in different age group should be taken seriously, so as to provide an important basis for revising National Tuberculosis Programme (NTP).

Enhancement of biodegradability of polychlorinated dibenzo-p-dioxins

Enhancement of biodegradability of polychlorinated dibenzo-p-dioxins (PCDDs) was studied with new isolated bacterial strains from soil and oxic-sediments contaminated by PCDDs. The results indicated that mono- and di-chlorinated dibenzo-p-dioxins could be utilized as a sole carbon source and degraded by isolated bacterial strains, but tri-chlorinated dibenzo-p-dioxin (TrCDD) was hardly degraded. The biodegradability of TrCDD and tetra-chlorinated dibenzo-p-dioxin (TCDD) by the strain Pseudomonas sp. EE41, a new isolated one, could be enhanced through primary nutrient of co-metabolism of o-dichlorobenzene (o-DCB). In this case, TrCDD (1.2mg/l for 3 weeks) was degraded by 33.1% and the degradation rate enhanced more than 2 fold; also TCDD (0.1 mg/l for 3 weeks) biodegraded by 37.8%. Most highly chlorinated, Penta-, Hexa-, Hepta-, and Octa-chlorinated, dibenzo-p-dioxins (P-CDD, H6, H7-CDD and OCDD) tested in this study could not be degraded while accumulated in bacterial cells.

A bicistronic retroviral vector to introduce drug resistance genes into human umbilical cord blood CD34+ cells to improve combination chemotherapy tolerance

OBJECTIVE

To study whether human umbilical cord blood CD34+ cells transduced with human aldehyde dehydrogenase class-1 (ALDH-1) and multidrug resistance gene (MDR1) have increases resistance to 4-Hydroperoxycyclo-phosphamide (4-HC) and P-glycoprotein effluxed drugs.

METHODS

A bicistronic retroviral vector G1Na-ALDH1-IRES-MDR1 was constructed and used to transfect the packaging cell lines GP + E86 and PA317 by LipofectAMINE method, using the medium containing VCR and 4-HC agents for cloning selection and ping-ponging supernatant infection between the ecotropic producer clone and the amphotropic producer clone, we obtained high titer amphotropic PA317 producing cells with high titers up to 5.6 x 10(5) CFU/ml. Cord blood CD34+ cells were transfected repeatedly with supernatant of retrovirus containing human ALDH-1 and MDR1cDNA under the stimulation of hemopoietic growth factors.

RESULTS

Bicistronic retroviral vector construction was verified by restriction endonuclease analysis. Polymerase chain reaction (PCR), reverse transcription (RT)-PCR, Southern blot, Northern blot, fluorescenceactivated cell sorting (FACS) method and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analyses showed that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The transgenes recipient cells confered 4-fold stronger resistance to 4-HC and 5.5 to 7.2-fold P-glycoprotein effluxed drug than untransduced cells.

CONCLUSION

The bicistronic retroviral vector-mediated transfer of two different types of drug resistance genes into human cord blood CD34+ cells and co-expression provided an experimental foundation for improving combination chemotherapy tolerance in tumor clinical trial.

2,4-dichlorophenoxyacetate/alpha-ketoglutarate dioxygenases from Burkholderia cepacia 2a and Ralstonia eutropha JMP134

2,4-Dichlorophenoxyacetate (2,4-D)/alpha-ketoglutarate (alpha-KG) dioxygenase has been purified to apparent homogeneity from Burkholderia cepacia strain 2a, which utilizes 2,4-D as sole carbon source. The enzyme required ferrous ions, and was a homodimer composed of subunits having an Mr of approximately 32,000. The reaction catalysed consumed one mol each of 2,4-D, alpha-KG and dioxygen, with the production of one mol each of succinate, 2,4-dichlorophenol and glyoxylate. Maximum activity was exhibited at pH 7.8 and 25 degrees C, and reactivity was enhanced by the presence of ascorbate and cysteine. Mn2+, Zn2+, Cu2+, Fe3+ and Co2+ were inhibitory, and chemical modification of the dioxygenase revealed that thiol groups were essential for activity. The enzyme was active towards other substituted phenoxyacetates, but reacted most rapidly with 2,4-D. The apparent Michaelis constants for 2,4-D and alpha-KG were 109 and 8.9 microM, respectively. The properties of this enzyme are compared with those of the 2,4-D/alpha-KG dioxygenase from Ralstonia eutropha JMP134, which exhibits a differing N-terminal amino-acid sequence, and a different temperature 'optimum', pH optimum, substrate specificity and sensitivity to thiol-binding reagents.

[Studies on the subgenomic RNAs of hepatitis E virus]

Through labeling HEV RNAs with [32P]-phosphate, two subgenomic RNAs at 6.5 to 7.5 h post-infection, one subgenomic RNA at 8.5 to 10.5 h post-infection and none subgenomic RNAs were detected at 21 post-infection or in purified virus. Hybridization results illustrated that the HEV subgenomic RNAs form a 3' nested set which is situated at the 3' end of genome, but their 5' ends do not share a common leader sequence. UV transcription results showed that the HEV subgenomic RNAs were transcribed independently from its promote. Primer extension analysis suggested that the 5' end of large subgenomic RNA was mapped to the initiative region within RNA polymerase region, and the small subgenomic RNA was mapped to the intergenic region between ORF1 and ORF2.

[mRNA expression of keratoepithelin in cornea after photorefractive keratectomy in rabbits]

OBJECTIVE

To investigate the roles of keratoepithelin(KE) during healing after photorefractive keratectomy (PRK).

METHODS

20 of 24 rabbits underwent bilateral 193 nm excimer laser photorefractive keratectomy to correct 10 diopters of myopia, and the other 4 rabbits as normal group. The mRNA levels of KE in corneas of the rabbits were determined by the in situ hybridization technique with a Digoxigenin labled probe.

RESULTS

In normal group, there was no mRNA expression of KE in cornea. on 7, 14 days after operation, mRNA expression of KE was observed in epithelium and stroma of operation group, while on 28 days mRNA expression of KE was observed only in epithelium.

CONCLUSION

KE was involved in the synthesis of extracellular matrix during healing after PRK and may play an important role in the development of haze by maintaining proper spacing among collagen fibrils.

[Multiple factors analysis of myopic regression after photorefractive keratectomy]

PURPOSE

To investigate myopic regression after excimer laser photorefractive keratectomy(PRK) in patients with myopia.

METHODS

PRK was performed to correct myopia errors from 1.00 D to 16.00 D diopters on 214 myopia eyes(121 patients). All eyes were divided into two groups: group I--1.00 D(-)-6.00 D (124 eyes), group II--6.25 D(-)-16.00 D(90 eyes). All the patients were followed up for two years.

RESULTS

A Significant positive correlation was found between the regression and the extents of attempted correction. The rate of regression in mild to moderate myopia group was 9.7% while in highter group it was 27.8% (P < 0.005). The rate of regression of older age group in lighter myopia group was highter than that in younger case (P < 0.005). Relatively severe haze under the corneal epithelium often accompanies the regression.

CONCLUSION

The main factors which caused the myopia regression after PRK was the extent of attempted correction, patients' age and corneal haze.

[In vitro study on transduction of human O(6)-methylguanine-DNA-methyltransferase cDNA into human umbilical cord blood CD34(+) cells]

OBJECTIVE

To explore human umbilical cord blood hematopoietic progenitor cells transduced with human O(6)-methylguanine-DNA-methyltransferase (MGMT) gene increase resistance to 1,3-Bis(2-Chloroethyl)-1-Nitrosourea(BCNU).

METHODS

The present authors obtained a full length cDNA fragment encoding the human MGMT from a patient with cholelithiasis liver tissue by RT-PCR method and confirmed by DNA sequencing. The fragment was cloned into pGEM-T vector and further subcloned into G1Na retrovirus vector. Then the G1Na-MGMT was transfected into the packaging cell lines GP+E86 and PA317 by LipofectAMINE method; using the medium containing BCNU for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, the authors obtained high titer amphotropic PA317 producer clone with the highest titer up to 1.6x10(6) CFU/ml. Cord blood CD34(+) cell were transfected repeatedly with supernatant of retrovirus containing human MGMT cDNA under stimulation of hemopoietic growth factors.

RESULTS

PCR, RT-PCR, Southern blot, Northern blot, Western blot and MTT analyses showed that MGMT gene had been integrated into the genomic DNA of cord blood CD34(+) cells and expressed efficiently in the transfected cells. The transgene recipient cells conferred 4 folds stronger resistance to BCNU than that of the non-transduced.

CONCLUSION

The retrovirus vector-mediated transfer of MGMT drug resistance gene into human cord blood CD34(+) cells and expression could confer the resistance of transgene cells to BCNU toxicity.

H(2)O(2)-induced egr-1, fra-1, and c-jun gene expression is mediated by tyrosine kinase in aortic smooth muscle cells

Hydrogen peroxide (H(2)O(2)) has recently been shown to have a dual effect on cell growth by stimulating proliferation and triggering apoptosis. Apoptosis induced by H(2)O(2) is a direct consequence of oxidant injury, while the proliferative response to H(2)O(2) is thought to be a protective mechanism against oxidant injury. Signaling of the H(2)O(2)-induced proliferative effect has been proposed to occur via the activation of mitogen-activated protein kinase (MAPK) and increase in expression of transcription factors. In the present study, H(2)O(2)-induced mitogenic signaling in aortic smooth muscle cells (ASMC) was investigated with a specific focus on the roles of tyrosine kinase and tyrosine phosphatase in the regulation of the H(2)O(2)-stimulated egr-1, fra-1, and c-jun transcription. The results show that H(2)O(2)-induced increases in egr-1, fra-1, and c-jun mRNA levels, as measured by Northern blot analysis, are time and dose dependent with the peak of the response within 2 h. Tyrosine kinase inhibitors (genistein, amino-genistein, and tyrphostin 51) significantly attenuated H(2)O(2)-induced expression of these genes and a tyrosine phosphatase inhibitor (perox-vanadate) stimulated their expression. H(2)O(2) stimulated tyrosine kinase activities and caused protein tyrosine phosphorylation, which was blocked by tyrphostin 51. H(2)O(2) also caused tyrosine phosphorylation of platelet derived growth factor (PDGF) receptor. These data show that H(2)O(2) increases egr-1, fra-1, and c-jun mRNA levels in vascular smooth muscle cells, and the increase in expression of these genes is mediated by activation of tyrosine kinase. Our data also provide evidence that the H(2)O(2)-induced mitogenic response is, in part, mediated through the receptor tyrosine kinase, PDGF receptor.

[Analysis of surface markers of expanded human umbilical cord blood cells in vitro]

OBJECTIVE

To explore the optimal timing for in vitro expansion and transplantation of umbilical cord blood hematopoietic cells.

METHODS

Hematopoietic cells from human umbilical cord blood were cultured with G-CSF, GM-CSF, rIL-3, rIL-6, SCF and Epo in a long term culture system, the cell cycle and cellular markers were analysed dynamically.

RESULTS

CD(3)(+), CD(4)(+)/CD(45RO)(+) and CD(8)(+)/CD(45RO)(+) cells increased at day 3, and reached the highest level at day 7, decreased at day 14, and remained lower level at day 21. CD(4)(+) and CD(8)(+) cells showed no change at day 7, decreased at day 14, and decreased further at day 21. CD(4)(+)/CD(45RA)(+) and CD(8)(+)/CD(45RA)(+) cells decreased after day 3, and decreased further at day 14. HLA-DR(+) cells increased from day 3 to day 7. CD(34)(+) cells increased at day , reached the highest level at day 7, and decreased at day 14. CD(34)(+), CD(34)(+) CD(38)(-), CD(34)(+) CD(38)(+) cells increased 8.8, 7.4 and 8.7 fold at day 7, respectively, as compared with that precultured. The cells in the S phase increased at day 21.

CONCLUSIONS

This culture system is able to expand hematopoietic cells of human umbilical cord blood and keeps them intact. The number of hematopoietic cells reached the highest level in the culture from day 7 to day 14, which is the optimal time for transplantation.