[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.

von Willebrand disease in China

PURPOSE

To review the molecular pathogenesis in Chinese patients with von Willebrand disease (vWD) and polymorphisms of von Willebrand factor (vWF) in Chinese population.

DATA SOURCES

Both Chinese and English language literature search using MEDLINE (1985-1998), and original articles published in main Chinese and international journals.

STUDY SELECTION AND DATA EXTRACTION

After reviewing of the literature, 19 articles of them were selected that specifically addressed the stated purpose.

RESULTS

The molecular pathogenesis of vWD was variant. Six cases of point mutation have been found in Chinese patients with vWD. The system of site-directed mutagenesis and expression of vWF gene was constructed. The polymorphisms of vWF gene are very different between Chinese and Gaucasians.

CONCLUSION

Combining to gene mutant in vWD patients, the use of site- directed mutagenesis and expression of vWF will help to understand the vWF function. The polymorphisms of vWF gene are useful marker in Chinese for carrier detection and prenatal diagnosis of vWD.

[Study on genetic mutations of the vWF in type 2A von Willebrand disease]

OBJECTIVE

To study the molecular pathological mechanism of the type 2A von Willebrand disease(vWD) and the relationship of the phenotypes with genotypes.

METHODS

A total of 126 patients with the hereditary hemorrhagic disease were examined using bleeding time, vWF:Ag, FVIII:CAg, ristocentin induced platelet agglutination assay(RIPA) and multimer analysis of plasma. The exon 28 of authenticity vWF gene was studied by PCR, denaturing gradient gel electrophoresis(DGGE) and sequencing in the type 2A vWD.

RESULTS

Fourteen cases were diagnosed as type 2A vWD. Four cases of point mutations resulting in single animo acid substitutions, Arg611His, Ala737Glu, Arg834Trp, were identified in 3 families of type 2A vWD. Ala737Glu substitution in vWF is caused by a novel missense mutation.

CONCLUSION

The molecular pathological mechanism of the type 2A vWD is very variant.

[Intraperitoneal lymphatic chemotherapy for colonic cancer]

OBJECTIVES

To evaluate the effect of intraperitoneal lymphatic chemotherapy with carboplatin and sandostatin on colonic carcinoma and abdominal lymphatic metastasis in patients after radical resection.

METHODS

Patients with colonic cancer were divided into two group: abdominal lymphatic chemotherapy group and control group. The lymphatic chemotherapy group was treated at the introduction stage of anesthesia with carboplatin (200 mg) injected intraperitoneally and sandostatin (0.1 mg x 2) injected subcutaneously, whereas the control group was just treated with carboplatin (200 mg) injected intraperitoneally. The platinum levels in abdominal lymphatic nodes were monitored during operation. The two groups were uninterruptedly given intraperitoneal lymphatic chemotherapy or intraperitoneal chemotherapy. Retroperitoneal lymphatic metastasis was evaluated in each patient by abdominal CT scan after operation.

RESULTS

The platinum levels in abdominal lymphatic nodes increased more significantly at 2, 3 hours in the lymphatic chemotherapy group than in the control group (P < 0.01). There was no difference in the platinum levels of the portal vein between the two groups, and also no difference in the platinum levels between the lymphatic nodes with or without metastasis. The rates of retroperitoneal lymphatic metastasis after resection were significantly lower in the lymphatic chemotherapy group control group (P < 0.01).

CONCLUSION

Intraperitoneal administration of carboplatin combined with sandostatin may elevate the platinum levels in the abdominal lymphatic nodes and reduce the abdominal lymphatic metastasis after radical resection of colonic cancer. It is an effective method for intraperitoneal lymphatic chemotherapy.

[Construction and transient expression of an Ala 737-->Glu mutant of vWF]

OBJECTIVE

To study the functional change of an Ala737-->Glu substitution mutant of vWF and the molecular pathological mechanism of this mutant in the type 2A vWD.

METHODS

The expression plasmid pSVvWF containing full-length cDNA of vWF was used to site direct mutagenesis by polymerase chain reaction (PCR) and transitorily expressed in the COS-7 cells, vWF: Ag in the supernatant and the cell lysate between wild type and pSVAla737Glu vWF were measured. vWF polymers of the platelet of the patient with the mutation and response to DDAVP treatment of the patient were observed.

RESULTS

vWF: Ag level of pSVAla 737Glu vWF was 76.4% and 98.8% of the wild types in the supernatant and cell lysate, respectively. The polymer pattern of extracellular pSVAla737Glu vWF was indistinguishable from that of the wild type, containing all kinds of molecular weight. Increased vWF antigen levels was observed in the patients after DDAVP treatment.

CONCLUSION

This mutant did not change the assembly and secretion of vWF. The mutant of vWF Ala737-->Glu resulted in Group II type 2A vWD.

Spectroelectrochemical investigation of direct electron transfer between resting horseradish peroxidase and its oxidation states promoted by DNA

Direct electron transfer between resting horseradish peroxidase (HRP) and its oxidation states was observed at a gold mesh electrode in a spectroelectrochemical cell in the presence of DNA. The conversion between HRP and the oxidized species induced electrochemically was found to be reversible and parallel to that initiated chemically. DNA played an important role as electron carrier and promoted the electron transfer between HRP and the electrodes. Voltammetric results and CD spectra indicated an interaction between HRP and DNA. Moreover, the secondary structure of HRP was slightly disturbed upon mixing with DNA. The direct spectroelectrochemistry of HRP at a gold mesh electrode presented new information on its bioelectrochemical characteristics.

[Detection of trisomy 8 with interphase fluorescence in situ hybridization in myelodysplastic syndromes]

OBJECTIVE

To explore the value of interphase fluorescence in situ hybridization (FISH) in the detection of trisomy 8 in myelodysplastic syndromes (MDS).

METHODS

Conventional cytogenetics (CC) and interphase FISH using SpectrumGreen labelled chromosome 8 centromere specific probe were simultaneously carried out to detect trisomy 8 in 69 MDS and 6 normal individuals.

RESULTS

Two hundred interphase cells were counted and cells with three green hybridization spots > 3% was assigned. Eleven cases displayed trisomy 8 by CC and were confirmed in 10 by FISH. In 7 cases, the percentage of trisomy 8 cells was significantly lower by FISH than by CC. Seven cases displayed trisomy 8 by FISH in 58 cases who did not show trisomy 8 by CC. Of the 7 cases, two had 2 and 3 marker chromosomes respectively, 4 had normal karyotypes.

CONCLUSIONS

Interphase FISH was a useful method for the detection of trisomy 8 in MDS, especially in patients with normal karyotype or marker chromosome. It was a important complement to CC.

Expression of the human multidrug resistance gene mdr1 in leukemic cells and its application in studying P-glycoprotein antagonists

OBJECTIVE

To investigate the retrovirus-mediated transfer and expression of multidrug resistance gene (mdr1) in hematopoietic cells and to develop a model for studying the possible reversal of the MDR-mediated phenotype.

METHODS

A retroviral vector HaMDR expressing the human mdr1 gene was packaged by PA317 cells with a titer of up to 8.5 x 10(5) CFU/ml. K562 leukemia cells were infected with MDR retrovirus, and transfectant K562/MDR cells were generated. The integration and expression of the exogenous mdr1 gene in K562/MDR cells were determined by polymerase chain reaction and flow cytometry. The reversal ability of P-glycoprotein (P-gp) antagonists was analyzed by in vitro drug sensitivity, accumulation and efflux of rhodamine 123 (Rh123) in this model.

RESULTS

Transduction with amphotropic MDR retrovirus resulted in integration and expression of the mdr1 gene in the resistant cells, where an aberrant splicing transcript of the mdr1 gene was found. The K562/MDR cells displayed a classic MDR phenotype with a 41-78 fold resistance to vincristine and colchicine in comparison with parental K562 cells. The drug sensitivity of K562/MDR cells to vincristine can be completely restored by cyclosporin A (CsA, 2 mg/L) and Cremophor EL (CRE 132 mg/L), either individually or in combination (P < 0.05). CsA (3 mg/L) can block the efflux pump function of P-gp shown by the significantly increased accumulation and efflux reduction of Rh123 in K562/MDR cells.

CONCLUSIONS

Retroviral vector HaMDR allows transfection with high-level expression of the mdr1 gene in human myeloid progenitor cells K562. The transfected K562/MDR provides a simple, sensitive model for developing antagonists of P-gp and studying their mechanism of action.

Describing paraspinal EMG findings: inadequacy of the single 0-4+ score

OBJECTIVE

Clinical electrodiagnostic textbooks instruct that lumbar radiculopathies typically have paraspinal abnormalities and that these abnormalities should be recorded using a single 0-4+ scale. Recent work demonstrates that that the innervation of the paraspinal muscles is segmental, not homogenous, and that asymptomatic persons may have reproducible ("1+") positive waves or fibrillation potentials.

DESIGN

To assess current use of the 0-4+ scale, a retrospective study of EMG scores in persons diagnosed with radiculopathy at a university laboratory was performed. No specific paraspinal EMG technique was used. Included were 117 consecutive, qualified S-1 radiculopathies and 33 L-5 radiculopathies.

RESULTS

When radiculopathy was defined by "more than one limb muscle abnormal," paraspinal scores were recorded as 0 to 1+ in 83% of L-5 and 63% of S-1 cases (chi2, L-5 vs. S-1, not significant). For more severe radiculopathies (at least one limb muscle with a "2+" score), 0-1+ paraspinal scores were recorded in 76% of L-5 and 57% of S-1 cases (chi2, not significant). A total of 82% of S-1 radiculopathies with no overlapping L-5 innervation had 0-1+ scores.

CONCLUSIONS

These data demonstrate the common use of equivocal paraspinal scores in patients whom electromyographers believe have radiculopathies. Standardized exploration techniques and a more detailed scoring system for the paraspinal muscles may eliminate this discrepancy.

[Study of platelet membrane glycoproteins and its fibrinogen binding reaction in patients with cerebral infarction and diabetes mellitus]

OBJECTIVE

To investigate the change of platelet membrane glycoproteins and its fibrinogen binding reaction in patients with cerebral infarction and type II diabetes mellitus (DM), and assess their value in the study of thrombosis and pro-thrombosis state.

METHODS

By flow cytometry, the platelet glycoprotein (GP) I b, GP II b, GP III a, GP II b- III a complex and P-selectin expression as well as fibrinogen binding reaction were analyzed in 85 patients with type II DM and 28 with cerebral infarction, and compared with that in 30 normal subjects.

RESULTS

The platelet membrane GP II b- III a complex, P-selectin expression and fibrinogen binding reaction were higher, while the platelet surface GP I b was lower in the patients with cerebral infarction and type II DM with vascular disease than those in normal group. The GP II b and GP III a were not significantly changed. There was no difference of these parameters between the type II DM without vascular disease patients and normal group.

CONCLUSION

The platelet fibrinogen binding reaction, P-selectin and GP II b- III a complex expression were increased while the GP I b decreased in patients with cerebral infarction and type II DM with vascular disease.

A recombinant antibody-targeted plasminogen activator with high affinity for activated platelets increases thrombolytic potency in vitro and in vivo

To increase thrombolytic specificity of urokinase (uPA), we engineered a recombinant chimeric plasminogen activator SZ51Hu-scuPA, which consists of a humanized monoclonal antibody (SZ-51Hu) specifically against P-selectin on activated human platelet and a single-chain urokinase (scuPA). The cDNA, encoding scuPA amino acids 1-411, was inserted in 5' end to 3' end orientation immediately after the CH3 of SZ-51Hu heavy-chain sequence in the expression vector alphaLys30. The resulting construct alphaLys30-SZ51VH/Hu-scuPA was used to transfect into SP2/0 murine myeloma cell line, which was pretransfected with SZ51Hu light chain. The fusion protein SZ51Hu-scuPA was expressed at 5 mg/L in the supernatant of cell culture. The fusion protein purified by affinity chromatography had a molecular weight of 160 kDa with fibrinolytic activity of 39,000 IU/mg and its affinity to activated human platelet was 67% of the parent murine mAb SZ-51. The thrombolytic property of the fusion protein was first characterized in an in vitro system, which consists of a 125I-fibrin-labeled human plasma clot containing different concentrations of human platelets suspended in citrated human plasma. Fifty percent lysis was reached with SZ51Hu-scuPA in 1 hour at a concentration of 20 IU/mL or in 2 hours at a concentration of 10 IU/ mL, which was much faster than uPA at the same concentration. The maximal lysis of the clots by SZ51Hu-scuPA was 4.1 to 8.4 times more potent than that by uPA. The fusion protein was further characterized in the hamster pulmonary embolism model with clots prepared from fresh platelet-rich human plasma containing 125I-labeled fibrinogen. The thrombolytic activity of SZ51-scuPA was 3.9 times more potent than that of uPA at 2,000 IU/kg in this model. Almost no significant fibrinogen breakdown was observed either in vitro and in vivo.

Hemostasis and thrombosis research in China

PURPOSE

To highlight the development and achievements of hemostasis and thrombosis research in China over the past 50 years.

DATA SOURCES

Both Chinese and English language literature search using MEDLINE (1990-1998), and original articles published in the main Chinese and international journals.

STUDY SELECTION

After reviewing all the main articles on thrombosis and hemostasis, 20 of them were selected that specifically addressed the stated purpose. DATE EXTRATION: The content that could present the progress in hemostasis and thrombosis in China was selected.

RESULTS

Monoclonal antibodies have widely been used in basic research and laboratory diagnosis. Several novel gene mutations of coagulation factors have been identified. Some drugs of traditional Chinese medicine have proved to be efficient in treatment of thrombotic diseases.

CONCLUSIONS

Significant achievements in basic, clinical and pharmacological research in the field of hemostasis and thrombosis have been made in China in the past 50 years. Some new discoveries in platelet membrane glycoproteins and coagulation factors research are believed to be contributions to the international scientific community. However, a specific effort using advanced techniques should be made for future development, especially in molecular biology research.

Sma I, Hha I, Msp I and Rsa I restriction fragment length polymorphisms in the von Willebrand factor gene of Chinese population

OBJECTIVE

To study Sma I, Hha I, Msp I and Rsa I restriction fragment length polymorphisms in vWF gene of Chinese population.

METHODS

The vWF gene from 52 unrelated individuals of Han Nationality, 44 of Yi tribe, 42 of Dai tribe was analyzed by polymerase chain reaction and digestion of the endonucleases of Sma I, Hha I, Msp I and Rsa I.

RESULTS

The allele frequencies were 0.38:0.62 for Sma I+:Sma I- and 0.38:0.62 for Hha I+:Hha I-; 0.20:0.80 for Msp I+:Msp I-; 0.93:0.07 for Rsa I+:Rsa I- in Chinese Han population. The theoretical heterozygous rates were 0.46, 0.46, 0.36 and 0.13 of these polymorphisms, respectively. The allele frequencies were 0.43:0.57 for Sma I+:Sma I- and 0.43:0.57 for Hha I+:Hha I-, 0.26:0.74 for Msp I+:Msp- in Yi tribe and 0.36:0.64 for Sma I+:Sma I- and Hha I+:Hha I-, 0.17:0.83 for Msp I+:Msp I- in Dai tribe. The theoretical rates were 0.49 for Sma I and Hha I and 0.38 for Msp I in Yi tribe; and 0.45 for Sma I and Hha I, 0.28 for Msp I in Dai tribe, respectively.

CONCLUSIONS

The allele frequencies and theoretical rates of these polymorphisms in vWF gene are different between Chinese populations and Caucasians. They should be useful for the carrier detection and prenatal diagnosis in vWD families of Chinese.

[Preparation and characterization of monoclonal antibodies against Clonorchis sinensis]

AIM

To develop and identify monoclonal antibody (McAb) against adult Clonorchis sinensis.

METHODS

BALB/c mice were immunized with soluble antigen of adult Clonorchis sinensis, the spleen cells of immunized mice were fused with myeloma cell line SP2/0. Then the hybridoma cell lines secreting high titer of McAbs were screened. The Ig subtypes and titer of the McAbs were assayed with ELISA. The antigens recognized by the McAbs were examined with IFAT and identified by immunoblot analysis. The cross reactions between the McAbs and antigens of Schistosoma japonicum, Paragonimus westermani and Cysticercus cellulosae were detected.

RESULTS

5 hybridoma cell lines secreting high titer of McAbs against adult Clonorchis sinensis were established. All five clones of McAbs belonged to IgM subtype. The antigens recognized by the McAbs were located at the intestinal tract wall of adult Clonorchis sinensis. The McAbs had no cross reactions with antigens of Schistosoma japonicum, Paragonimus and Cysticercus cellulosae.

CONCLUSION

5 hybridoma cell lines against adult Clonorchis sinensis secreting high titer of McAbs with high specificity were established.

Clinical and biological relevance of flow cytometric determination of P-glycoprotein expression in acute non-lymphocytic leukemia

OBJECTIVE

To evaluate the characteristics of P-glycoprotein (P-gp) expression of acute non-lymphocytic leukemia (ANLL) at different status and the prognostic and biological features in ANLL at diagnosis.

METHODS

Monoclonal antibody UIC2 and indirect immunofluorescence assay by flow cytometry were used to determine P-gp expression of 169 patients with ANLL, including 152 previously untreated, 7 refractory and 10 at remission.

RESULTS

P-gp was expressed in 28.9% of the previously untreated ANLL cases and P-gp was lower than that in 71.4% of the refractory cases (P < 0.05). No P-gp expression was found in the patients at remission. For previously untreated AN-LL, P-gp was highly expressed in hybrid acute leukemia (66.7%) and acute monoblastic leukemia (47.4%). P-gp expression was highly associated with surface markers [cluster of differentiation (CD) 34, CD7, CD14, CD42b and CD61] and unfavorable cytogenetic abnormalities. About 23% of P-gp-ANLL obtained complete remission, which was significantly lower than that (76%) in P-gp-cases.

CONCLUSIONS

P-gp expression is higher in refractory ANLL cases than that in cases at diagnosis or at remission. P-gp is an index of poor prognosis in adults with ANLL. P-gp+ ANLL cases have unique clinical and biological characteristics.

[Immunophenotypic and clinical features of Philadelphia chromosome positive adult lymphocytic leukemia]

OBJECTIVE

To sutdy the immunophenotypic and clinical features of Philadelphia chromosome positive adult acute lymphocytic leukemia (Ph+ ALL).

METHODS

Fifty-one previously untreated Ph+ ALL were included. Morphologic/cytochemistric, cytogenetic and immunophenotypic examinations were performed. Patients received daunorubicin-vincristine-prednisone (DOP) or DOP-asparaginas (DOLP) induction protocols. Two patients received autologous bone marrow transplantation (ABMT) as postremission therapy.

RESULTS

The 51 patients were among 158 patients with ALL (32.3%). Patients with Ph+ ALL were older and had a significantly higher incidence of peripheral leukocytosis and blasts, FAB L2 subtype, B lineage antigens expression and CD34 positivity. 42.1% of Ph+ ALL achieved complete remission (CR). Their remission duration was 4.5 months, the median time to CR was 54 days. Two patients receiving ABMT survived in remission 22 and 33 months, respectively.

CONCLUSION

Patients with Ph+ ALL are usually older, have FAB L2 morphology, and are B lineage antigens, CD34 positive. These patients had lower CR rate, shorter remission duration, and needed longer time to achieve CR.

[Construction and expression of a functional chimeric murine-human antibody directing against human cross-linked fibrin]

OBJECTIVE

In order to reduce the immunogenicity of the murine antifibrin monoclonal antibody (MAb) SZ-63 to human beings.

METHODS

First of all, the cDNA sequences encoding the constant regions of the murine kappa light chain and gamma 1 heavy chain in the SZ-63 MAb were substituted with the corresponding human genomic sequences. Then the constructed MAb was cloned separately into two selectable expression vectors, and the latter were transfected into mouse myeloma cells (SP2/0) one by one.

RESULTS

ELISA, Western blot and competition experiment results showed that there was 0.8 approximately 1.0 mg/L of chimeric 63 IgG in the conditioned medium of selected cell lines, and the expressed IgG had higher antifibrin D-Dimer capability than that of the original MAb.

CONCLUSION

The expressed chimeric antibody can be used as a targeting agent for thrombus imaging and treatment.

A patient with type 2N von Willebrand disease is heterozygous for a new mutation: Gly22Glu. Demonstration of a defective expression of the second allele by the use of monoclonal antibodies

We report the case of a Chinese patient who has subnormal von Willebrand factor (vWF) level and normal vWF multimeric pattern, but a lack of vWF capacity to bind factor VIII (FVIII). Exons 18 to 20 of the patient's vWF gene were analyzed by DGGE and a G2354 --> A substitution which changes the encoded amino acid sequence from Gly22 to Glu was identified. The patient is heterozygous for this substitution, creating a unique Sac I restriction site. Recombinant vWF (rvWF) containing the candidate mutation was transiently expressed in COS-7 cells. It was processed and secreted normally but failed to bind FVIII. FVIII binding ability of hybrid rvWF, obtained by cotransfection of normal and mutated expression vectors and corresponding to a heterozygous genotype, was moderately decreased. To explain this functional discrepancy between patient's plasma vWF and hybrid rvWF, we used anti-vWF monoclonal antibodies (MoAbs) as capture in an enzyme-linked immunosorbent assay test. MoAb 32B12 recognized both wild-type and mutated rvWFs whereas MoAb 418 did not recognize mutated rvWF. Because MoAb 418 also failed to capture the plasma vWF from propositus, it means that his second nonmutated allele is not expressed or expressed at a very low level.

Thermo Sequenase DNA polymerase and T. acidophilum pyrophosphatase: new thermostable enzymes for DNA sequencing

A combination of thermostable enzymes has been developed that produces higher quality cycle sequences. Thermo Sequenase DNA polymerase is a thermostable enzyme engineered to catalyze the incorporation of ddNTPs with an efficiency several thousandfold better than other thermostable DNA polymerases. Since the enzyme also catalyzes pyrophosphorolysis at dideoxy termini, a thermostable inorganic pyrophosphatase is needed to remove the pyrophosphate produced during sequencing reactions. Thermoplasma acidophilum inorganic pyrophosphatase (TAP) is thermostable and effective for converting pyrophosphate to orthophosphate. The use of the combination of Thermo Sequenase polymerase and TAP for cycle sequencing yields sequence data with uniform band intensities, allowing the determination of longer, more accurate sequence reads. Uniform band intensities also facilitate interpretation of sequence anomalies and the presence of mixed templates. Sequencing PCR products of DNA amplified from heterozygous diploid individuals results in signals of equal intensity from each allele.

Construction and expression of mouse-human chimeric antibody SZ-51 specific for activated platelet P-selectin

A murine monoclonal (mAb) SZ-51 specific for human P-selectin may be used for in vivo thrombus imaging and for the targeting of fibrinolytic agents to thrombi. In order to reduce the immunogenicity of the murine mAb SZ-51 in humans, we cloned and sequenced the cDNAs encoding the variable region of mAb SZ-51 in order to develop mouse/human chimeric reagents. The E. coli expression vector pHEN1-SZ51Fab/Hu was constructed by fusing the variable regions of mAb SZ-51 with human IgG gamma 1CH1 and C kappa genes. The constructs were introduced into E. coli HB2151 for expression of soluble chimeric Fab fragment. We also constructed two fusion products by joining the variable regions of mouse antibody to the appropriate constant regions of human Ig gamma 1 and kappa. These chimeras were cloned into two eukaryotic selectable expression vectors separately, which were then contransfected into a non-Ig secreting murine myeloma line SP2/0 with lipofectin reagent. Six cell lines remained positive for Ig secretion. The highest producing cell line, which showed stable integration and expression at 5 mg/l of culture, was selected for the large scale production of chimeric antibody. Immunoblotting analysis demonstrated that both of the chimeric antibodies (SZ51Fab/Hu, SZ51/Hu) in the culture supernatants, like the native mAb SZ-51, bind P-selectin. In addition, the whole chimeric antibody can compete for binding to activated platelets with murine SZ-51. Therefore, the SZ-51 chimeric antibody may be a potential agent for diagnosis and treatment of thrombotic diseases in the future.

Detection by denaturing gradient gel electrophoresis of an Arg1689Cys mutation in a Chinese patient with mild hemophilia A

OBJECTIVE

To detect gene defects of factor VIII (F VIII) in Chinese hemophilia A patients.

METHODS

3' end of exon 14 of F VIII gene from a mild hemophilia A patient of Chinese origin was amplified by polymerase chain reaction (PCR) and identified mutations by denaturing gradient gel electrophoresis (DGGE) combining with direct sequencing.

RESULTS

An upward shift band was detected by DGGE in W381. Direct sequencing demonstrated a C to T transition resulting in substitution of Arg1689Cys within a thrombin activation site of mature F VIII protein, which created a unique a thrombin activation site of mature F VIII protein, which created a unique PstI site in amplified fragment of F VIII.

CONCLUSIONS

The association of PCR and DGGE can detect a single base substitution; the Arg1689Cys mutation that inhibited activation of F VIII by thrombin is a molecular defect associated with hemophilia A in W381.

Radioimmunoimaging of arterial and venous thrombi in canine model using 99mTc labeled monoclonal antifibrin antibody

OBJECTIVE

To evaluate the usefulness of 99mTc labelled monoclonal antifibrin antibody SZ-63 for the detection of vascular thrombi, and to investigate the feasibility of thrombus imaging 99mTc-SZ-63.

METHODS

The monoclonal antibody SZ-63 (Mab SZ-63), which reacts with D-dimer, XLFN and fibrin monomer was produced and labelled with 99mTc using pretinning procedure. After that, the femoral arterial or venous thrombus model was prepared in dogs and injected with 99mTc-SZ-63 intravenously. Both arterial and venous thrombus models were imaged.

RESULTS

Both the arterial and venous thrombi were clearly visible within 2.5 hours after injection of 99mTc-SZ-63. Quantitative imaging analysis showed that the ratios between the thrombus and the opposite vessel increased with time extension. The ratios of thrombus to blood or surrounding muscle were 2. 56 +/- 0.83 and 13.40 +/- 5.10 for arterial thrombi and 3.34 +/- 1.06 and 22.40 +/- 6.40 for venous thrombi after the canines were killed.

CONCLUSION

99mTc-SZ-63 is a useful imaging agent for thrombus detection in vivo.

DNA sequencing with [alpha-33P]-labeled ddNTP terminators: a new approach to DNA sequencing with Thermo Sequenase DNA polymerase

A new approach to DNA sequencing is described. The method is based on the use of [alpha-33P]-labeled dideoxyribonucleoside triphosphate terminators and Thermo Sequenase DNA polymerase in cycle sequencing. Thermo Sequenase DNA polymerase incorporates ddNTPs as efficiently as dNTPs, allowing the use of low concentrations of these nucleotides in DNA sequencing. Because only the properly terminated chains are labeled and visualized on autoradiography of the sequencing gels, the sequence results are free of background. The intensity of DNA bands generated are remarkably uniform, which makes reading of DNA sequences easy. By staggered loading of the sequencing gel (at 2-3 hour intervals), it is possible to sequence DNA at least 450 to 500 nucleotides. Exposure time for autoradiography with [alpha-33P] labels is much shorter than with [35S] and does not substantially compromise autoradiographic resolution. Data can be obtained after only 12 hours of exposure of an X-ray film. Moreover, cycle sequencing requires very small amounts of single- or double-stranded template. Consequently, it is even possible to generate sequence data from a single bacterial colony. The details of the protocol are presented in a stepwise manner, and some important parameters to be considered for sequencing with this method are discussed.