[Study on interactions between TPO molecules tested with yeast two-hybrid system]

OBJECTIVE

To explore the interactions between TPO molecules and their locations.

METHODS

Full-length TPO, TPO(N) and TPO(C) were inserted respectively into the plasmids of the yeast two-hybrid system. Six different recombinant plasmids were generated. Every 2 recombinant plasmids were transformed into the yeast cell SFY526. The possible interactions between TPOs were then tested by the bioactivity of beta-galactosidase.

RESULTS

There are interactions between full-length TPO themselves TPO(N) themselves and TPO with TPO(N), but not between TPO(C)themselves, TPO with TPO(C) and TPO(N) with TPO(C).

CONCLUSION

Naturally, the molecular interaction domain of TPO may exist in the N terminus but not in the C terminus.

Mössbauer study of atmospheric aerosols of Shanghai

Three iron-containing atmospheric aerosol samples were collected, one at a tunnel, one near a viaduct, and one at a park in Shanghai City. These samples were studied by Mössbauer spectroscopy. The experimental results show that ultrafine particles alpha-Fe2O3 (about 13 nm) are the main component of the iron-containing atmospheric aerosols in the tunnel, and high-spin Fe3+ in sulfate containing a small amount of alpha-FeOOH is the main component of iron-containing particles in the aerosols from the other two places. The concentrations of iron in these locations, compared with those of some foreign cities, are much higher. To explore the chemical compositions of iron compounds in aerosols, SPM (scanning proton microprobe) has also been used. From these results, a possible chemical process by which the iron oxides converted to iron sulfate in air was discussed.

Determination of diphenylamine stabilizer and its nitrated derivatives in smokeless gunpowder using a tandem MS method

A novel method for determination of diphenylamine (DPA) and its nitrated derivatives, which are considered as characteristic components in smokeless powder and gunshot residues, is described. A tandem mass spectrometric method is established and mass spectrometer parameters optimized for each compound to obtain higher sensitivity. Under optimum conditions, quantitative analysis was carried out. The linear ranges are 5.0-200.0, 2.0-200.0 and 5.0-250.0 ng ml-1 and the detection limits are 1.0, 0.5 and 2.5 ng ml-1 for diphenylamine (DPA), N-NO-diphenylamine (N-NO-DPA) and 4-NO2-diphenylamine (4-NO2-DPA), respectively. Intra-assay and inter-assay precision and accuracy of analysis of these three samples were investigated. Based on the regression lines obtained above, smokeless samples were analyzed. It was found that there are 0.952% DPA, 0.384% N-NO-DPA and 0.128% 4-NO2-DPA in smokeless powder. Recovery tests showed that using cotton swabs, 80.3 +/- 4.9% DPA, 79.6 +/- 3.1% N-NO-DPA and 83.1 +/- 5.4% 4-NO2-DPA could be recovered from human hands.

Absence of mutations in the coding regions of follicle-stimulating hormone receptor gene in Singapore Chinese women with premature ovarian failure and polycystic ovary syndrome

Normal gonadal function is critically dependent on the integrity of pituitary-gonadal axis, where follicle-stimulating hormone (FSH) plays a key role. In the female, FSH is required for follicular growth, estrogen production and oocyte maturation. Its function is mediated by its specific receptor (FSHR), and defective FSHR has been shown to affect folliculogenesis and ovarian function. In this study, we screened the entire coding region of FSHR gene for pathogenic mutations in women with premature ovarian failure (POF) (n = 16) and polycystic ovary syndrome (PCOS) (n = 124) and found no mutations in these patients. Two known polymorphisms, Thr307Ala and Ser680Asn showed similar distributions of the allelic variations and protein isoforms in PCOS and normal control subjects (n = 236). It appears from this study that mutations in the coding regions of FSHR gene are not a causative factor of the above clinical manifestations in Chinese Singapore women.

[Expression of human anti-HBsAg-interferon fusion protein in CHO cells]

OBJECTIVE

To study the possibility of expressing human anti-HBsAg-interferon fusion protein in CHO cells as a putative targeting drug for hepatitis B.

METHODS

Both the heavy and light chain genes of human anti-HBsAg antibody derived from a phage display library were fused with alpha-2b interferon (IFN-alpha-2b) gene in vitro by polymerase chain reaction. The IFN alpha-2b gene was placed at the C terminal and a 15 amino acid linker was introduced at the fusion site. The light chain-IFN expression plasmid pLIC was constructed with a mammalian expression vector pcDNA3.1(+) and the heavy chain-IFN expression plasmid pFID was constructed with another mammalian expression vector pCdhfr1. These plasmids and the anti-HBsAg full-length light and heavy chain expression plasmids (pLIC and pHFD, respectively) were transfected into CHO (dhfr-) cells by the following three combinations:I, pLIC + pHFD;II, pLIC + pFID; III, pLFC + pFID. The cultured supernatant of the transfected cells was collected and assayed for IFN activity and HBsAg affinity.

RESULTS

The supernatant of combination I and II displayed IFN activity but only combination I supernatant exhibited HBsAg affinity.

CONCLUSIONS

The successful expression of a fusion protein with both HBsAg affinity and interferon activity may lead to a new way to make a targeting drug for hepatitis B.

Analysis of lipooligosaccharide biosynthesis in the Neisseriaceae

Neisserial lipooligosaccharide (LOS) contains three oligosaccharide chains, termed the alpha, beta, and gamma chains. We used Southern hybridization experiments on DNA isolated from various Neisseria spp. to determine if strains considered to be nonpathogenic possessed DNA sequences homologous with genes involved in the biosynthesis of these oligosaccharide chains. The presence or absence of specific genes was compared to the LOS profiles expressed by each strain, as characterized by their mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel and their reactivities with various LOS-specific monoclonal antibodies. A great deal of heterogeneity was seen with respect to the presence of genes encoding glycosyltransferases in Neisseria. All pathogenic species were found to possess DNA sequences homologous with the lgt gene cluster, a group of genes needed for the synthesis of the alpha chain. Some of these genes were also found to be present in strains considered to be nonpathogenic, such as Neisseria lactamica, N. subflava, and N. sicca. Some nonpathogenic Neisseria spp. were able to express high-molecular-mass LOS structures, even though they lacked the DNA sequences homologous with rfaF, a gene whose product must act before gonococcal and meningococcal LOS can be elongated. Using a PCR amplification strategy, in combination with DNA sequencing, we demonstrated that N. subflava 44 possessed lgtA, lgtB, and lgtE genes. The predicted amino acid sequence encoded by each of these genes suggested that they encoded functional proteins; however, structural analysis of LOS isolated from this strain indicated that the bulk of its LOS was not modified by these gene products. This suggests the existence of an additional regulatory mechanism that is responsible for the limited expression of these genes in this strain.

Structural and immunochemical characterization of the lipooligosaccharides expressed by Neisseria subflava 44

Neisserial lipooligosaccharides (LOSs) are a family of complex cell surface glycolipids. We used mass spectrometry techniques (electrospray ionization, collision-induced dissociation, and multiple step), combined with fluorophore-assisted carbohydrate electrophoresis monosaccharide composition analysis, to determine the structure of the two low-molecular-mass LOS molecules (LOSI and LOSII) expressed by Neisseria subflava 44. We determined that LOSI contains one glucose on both the alpha and beta chains. LOSII is structurally related to LOSI and differs from it by the addition of a hexose (either glucose or galactose) on the alpha chain. LOSI and LOSII were able to bind monoclonal antibody (MAb) 25-1-LC1 when analyzed by Western blotting experiments. We used a set of genetically defined Neisseria gonorrhoeae mutants that expressed single defined LOS epitopes and a group of Neisseria meningitidis strains that expresses chemically defined LOS components to determine the structures recognized by MAb 25-1-LC1. We found that extensions onto the beta-chain glucose of LOSI block the recognition by this MAb, as does further elongation from the LOSII alpha chain. The LOSI structure was determined to be the minimum structure that is recognized by MAb 25-1-LC1.

Association of AccI polymorphism in the follicle-stimulating hormone beta gene with polycystic ovary syndrome

OBJECTIVE

To search for FSH beta-subunit gene mutations in patients with polycystic ovary syndrome (PCOS) and determine the association between the mutations and the syndrome.

DESIGN

Clinical and molecular studies.

SETTING

Clinics and laboratories of the National University Hospital Obstetrics and Gynecology Department in Singapore.

PATIENT(S)

One hundred thirty-five patients with PCOS and 105 normal control subjects.

INTERVENTION(S)

Exons two and three were screened for mutations by single-stranded conformational polymorphism and DNA sequencing.

MAIN OUTCOME MEASURE(S)

Polymerase chain reaction followed by restriction enzyme analysis.

RESULT(S)

No missense mutation was found in the functional units of the FSHbeta gene in patients with PCOS, but a thymine-cytosine substitution in exon 3 (codon 76, TAT to TAC) was identified. The nucleotide change led to creation of an AccI digestion site. The distribution pattern of AccI polymorphism in the patients was significantly different from that in the control group, and the occurrence of homozygous carriers was significantly higher in patients (12.6%) than in the control group (3.8%). The frequency of polymorphism and prevalence of homozygosity were significantly higher in patients with PCOS with obesity (0.50% and 31.0%, respectively) than in those with menstrual disorders only (0.366% and 8.5%, respectively), which correlated with significantly higher androgen levels in the obese patients.

CONCLUSION(S)

The AccI polymorphism in FSHbeta gene may be associated with PCOS in some women, especially those with obesity.

Persistent, antigen-specific, therapeutic antitumor immunity by dendritic cells genetically modified with an adenoviral vector to express a model tumor antigen

Dendritic cells (DC) are potent antigen-presenting cells that play a critical role in the initiation of cellular immune responses. Using a BALB/c syngeneic colon carcinoma cell line expressing a model tumor antigen beta-galactosidase (betagal), we previously reported (Song et al, J Exp Med 1997; 186: 1247-1256) that immunization of mice with a single injection of DCs genetically modified with an adenovirus vector expressing betagal confers potent protection against a lethal intravenous tumor challenge, as well as suppression of pre-established lung tumors, resulting in a significant survival advantage. In the present study, we have addressed the question: how long does the memory of tumor antigen- specific immunity persists after DC priming in vivo using this genetically modified DC-based cancer vaccination strategy? To accomplish this, two groups of mice were evaluated: (1) mice surviving >400 days following protection from an initial intravenous tumor challenge after immunization with DC genetically modified to express betagal; and (2) mice surviving >300 days that had previously demonstrated regression of pre-established lung tumors after treatment with DC immunization. By analyzing the antigen-specific cytotoxic T lymphocyte response and challenging these long-term survival mice with a second subcutaneous tumor administration, the data demonstrate that a single administration of DC genetically modified to express a model antigen induces long-lasting, antigen-specific antitumor immunity in both naive and tumor-bearing hosts, observations that have important implications in the development of genetically modified DC-based antitumor vaccination strategies. Gene Therapy (2000) 7, 2080-2086.

[Study of mdr1 antisense oligodeoxynucleotides on reversal of multidrug resistance in ovarian carcinoma cell line SKOV3]

OBJECTIVE

To investigate the effect of mdr1 antisense oligodeoxynucleotides (ASON) on reversal of multidrug resistance in ovarian carcinoma cells.

METHODS

Drug resistance ovarian carcinoma cells SKOV3/mdr1 transducted with human multidrug resistance gene (mdr1) were served as models. The positive rate and function of the mdr1 gene product P-glycoprotein (P-gp) in SKOV3/mdr1 cells after mdr1-ASON (250 micrograms/ml) treatment were determined by flow cytometry and rhodamine 123 efflux trial. Drug resistance of SKOV3/mdr1 cells was also observed by cell colony culture.

RESULTS

P-gp positive rate of SKOV3/mdr1 cells after mdr1-ASON treatment was decreased from 38.9% to 21.3% (P < 0.01). Intracellular rhodamine retension in SKOV3/mdr1 cells after mdr1-ASON treatment was increased from 32.1% to 50.7% (P < 0.01). Under effect of Taxol 5 ng/ml, the relative percents of drug-resistant colony in mdr1-ASON treated SKOV3/mdr1 cells and in SKOV3/mdr1 cells was 8% and 63%, respectively, (P < 0.01). Under effect of Doxorubicin 100 ng/ml, the relative percents of drug-resistant colony in mdr1-ASON treated SKOV3/mdr1 cells and in SKOV3/mdr1 cells was 34% and 79%, respectively, (P < 0.01).

CONCLUSION

mdr1-ASON can reverse multidrug resistance of ovarian carcinoma cell in a certain extent so as to increase chemotherapeutic sensitivity of ovarian carcinoma cells.

[Study on clinical and molecular biological characteristics of infant acute leukemia]

OBJECTIVE

To study the clinical and molecular biological characteristics of infant acute leukemia (IAL).

METHODS

R and/or G banding technique was used for analysis of karyotype. DNA blotting for HRX gene rearrangement, and polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) for fusion gene detection.

RESULTS

Twenty cases of IAL were detected. HRX gene rearrangement was found in 10 cases, including HRX/AF-4 fusion gene in 5, HRX/AF-9 fusion in 2, and HRX/ENL fusion in 1, HRX self-fusion mediated by alu-repeat homologous recombination and HRX/EEN fusion each in one (HRX/EEN is a novel fusion gene reported for the first time).

CONCLUSION

High frequency of HRX gene rearrangement occurred in IAL, which is characterised by a massive leukemia cell burden and 11q23 translocation, forming fusion genes, especially HRX/AF-4 (about 50%). The results are of important significance in guiding clinical treatment and approaching the etiology of IAL.

[Chemoprotection of transfer of multidrug resistance gene into human hematopoietic progenitor cell]

OBJECTIVE

To observe the effect of the transfer of multidrug resistance gene (mdr1) into human hematopoietic progenitor cells (HPC) on the chemoprotection.

METHODS

Human CD34+ cells served as a target of mdr1 gene transfer. Retroviral vector SF-mdr containing human total length mdr1cDNA was introduced into packing cells GP-envAM12 by liposome-mediated transfection. The mdr1 gene was transduced into human CD34+ cells by retroviral supernatants of packing cells. The integration and expression of the mdr1 gene and its protein (P170) in transduced cells were determined by PCR, RT-PCR, and flow cytometry. The drug resistance of chemotherapy in transduced HPC was determined by culturing colonies.

RESULTS

The mdr1 gene was integrated and expressed in transduced CD34+ cells. The efficiency of mdr1 gene transfer was 10%-14%. Compared with untransduced controls, within a certain range of drug concentration, the number of drug-resistant colony in transduced HPC for taxol, doxorubicin, VCR and VP16 were increased by 3.6 +/- 2.1 fold, 2.9 +/- 0.3 fold, 1.9 +/- 0.4 fold, and 3.5 +/- 0.5 fold, respectively.

CONCLUSION

The transfer of the mdr1 gene into human HPC can increase the drug resistance of the transduced cells to corresponding chemotherapeutic drugs that may provide some degree of chemoprotection for HPC.

[Exploration of factors increasing transfer efficiency of retroviral mediated multidrug resistance gene (mdr1) into human CD(34)(+) cells]

OBJECTIVE

To explore factors influencing transfer of retroviral mediated multidrug resistance gene (mdr1) into human CD(34)(+) cells.

METHODS

Transduction efficiency in the presence of different combinations of cytokines and human bone marrow stromal cells plus cytokines were determined by flow cytometry (FCM). Drug resistance was evaluated by plating yields of cultured hematopoietic progenitor cells. The effect of Taxol at different concentrations on mdr1 gene transfer cells was determined by FCM.

RESULT

Transduction efficiency in the presence of SCF + FL + IL-3 was higher than that in other combinations of cytokines (SCF + IL-6 + IL-3, SCF + IL-6 + IL-3 + Tpo, SCF + IL-3). Transduction efficiency (20.5%) in the presence of bone marrow stromal cells plus cytokines (SCF + FL + IL-3) was higher than that (15.2%) without stromal cells, and the number of drug-resistant colony-forming cells was more in the former than in the latter. The percentage of CD(34)(+) cell with the gene transduction at 10 ng/ml Taxol reached 38.5%.

CONCLUSION

Human bone marrow stromal cells plus cytokines (SCF + FL + IL-3) is more effective in enhancing mdr1 gene transduction. Taxol at a certain concentration can enrich mdr1 gene transferred cells.

Conformationally constrained substance P analogues: the total synthesis of a constrained peptidomimetic for the Phe7-Phe8 region

A lactam-based peptidomimetic for the Phe7-Phe8 region of substance P has been synthesized. The synthesis used an anodic amide oxidation to selectively functionalize the C5-position of a 3-phenylproline derivative. The resulting proline derivative was coupled to a Cbz-protected phenylalanine, and an intramolecular reductive amination strategy used to convert the coupled material into a bicyclic piperazinone ring skeleton. The net result was a dipeptide building block that imbedded one of two proposed receptor bound conformations for the Phe7-Phe8 region of substance P into a bicyclic ring skeleton. The building block was then converted into a constrained substance P analogue with the use of solid-phase peptide synthesis. A similar intramolecular reductive amination strategy was used to synthesize a substance P analogue having only Phe7 constrained, and the original 3-phenylproline was converted into a substance P analogue having only Phe8 constrained. All of the analogues were examined for their ability to displace substance P from its NK-1 receptor.

Ontogenic profile of the expression of the mu opioid receptor gene in the rat telencephalon and diencephalon: an in situ hybridization study

The developmental profile of mu (mu) opioid receptor gene expression has been characterized in the embryonic, postnatal and adult rat brain by in situ hybridization histochemistry. By ED12, mu opioid receptor mRNA was detectable in the deep neuroepithelium of the cortical plate. In the developing rat central nervous system (ED13-PD40), transcripts were seen over numerous telencephalic and diencephalic structures, such as the olfactory bulb, caudate-putamen, nucleus accumbens, amygdaloid complex, hippocampal formation, hypothalamus and thalamus. In the vast majority of brain regions examined, the developmental profile of the mu opioid receptor gene expression is similar to that of its translated protein as established using receptor autoradiography. Once a hybridization signal is detected in the prenatal period, it gradually increased to reach maximal levels during the second and third postnatal weeks. By the end of the third postnatal week, mu opioid receptor mRNA levels decreased to reach amounts seen in adulthood. Our study demonstrates that mu opioid receptor gene expression is seen very early on in the embryonic rat brain with transient increases observed during the critical period of neurogenesis, neuronal migration and synaptogenesis, suggesting a role of this opioid receptor subtype in brain developmental processes.

[Establishment of a high germline competent C57BL/6J ES cell line]

Eleven ES cell lines from C57BL/6J mice were established, with the primary culture of mice embryos as feeder cells and 1 x 10(3) units Leukemia Inhibitory Factor (LIF) in the DMEM (high glucose) medium. The frequency of establishment was 9.6%. Five of these ES cell lines were demonstrated karyotypically normal with diploid composition of over 70%. They shared the characteristics of early embryonic cells: positive for alkaline phosphatase activity and oct4 gene expression. They also showed high potency to differentiate into wide types of cells in vivo. Following injection of the blastocysts, three of them showed abilities to give rise to chimeras and MESPU35 cell line was identified to have high efficiency of colonization into the germline. The clones of MESPU35 cells maintained the germline competence and the mutant clone also retained the high potency to participate into the development of embryos. MESPU35 cells can serve as a valuable vehicle for the production of mutant mice.

Expression of GIRK (Kir3.1/Kir3.4) channels in mouse fibroblast cells with and without beta1 integrins

G protein-activated K+ channel (GIRK) subunits possess a conserved extracellular integrin-binding motif (RGD) and bind directly to beta1 integrins. We expressed GIRK1/GIRK4 channels labeled with green fluorescent protein in fibroblast cell lines expressing or lacking beta1 integrins. Neither plasma membrane localization nor agonist-evoked GIRK currents were affected by the absence of beta1 integrins or by incubation with externally applied RGD-containing peptide. Mutation of the aspartate (D) of RGD impaired currents, GIRK glycosylation, and membrane localization, but the interaction with beta1 integrins remained intact. Thus, beta1 integrins are not essential for functional GIRK expression; and the GIRK-integrin interactions involve structural elements other than the RGD motif.

[Establishment of two ES cell lines with good germline contribution]

Nine embryonic stem cell lines have been established from mouse strain 129/ter. Three of the nine ES cell lines were karyotypically normal. The nine cell lines showed some difference in the growth rate and the differential competence. Chimeras were made by injecting the ES cells into C57BL/6J blastocysts, and the germline compositions of the chimeras were detected by mating them with albino ICR mice. The results indicated that ES cell line MESPU21 and MESPU22 were both highly germline-competent. Comparing with other ones, these two cell lines both were karyotypically normal and propagated fast. The tissue composition of the teratocarcinomas derived from these cell lines appeared paralle to the results of chimera production. Careful manipulation during the process of ES cell establishment was helpful to obtain good cell lines.

[Regulation of gene co-expression after bicistronic retrovirus-mediated gene transfer into human cord blood CD34+ cells]

OBJECTIVE

To compare internal SV40 early promoter with IRES of the in regulatory effect on gene co-expression after retrovirus-mediated gene transfer into human cord blood CD34+ cells.

METHODS

Based on pLXSN, vectors pLESN and pLEIN carrying EGFP and neo gene, distinguished by the in sequences between two, genes, were constructed. After liposome-mediated gene transfer into packaging cells, high-titre virus supernatant was obtained. After supernatant infection in vitro, transduced cells were cultured in CFC assay.

RESULTS

FACS analysis demonstrated that 10% of human cord blood CD34+ cell were infected in vitro. All of G418 resistant colonies demonstrated green fluorescence in LEIN group, while only 41.1% in LESN group.

CONCLUSION

IRES is superior to SV40 promoter for the guarantee of co-expression in bicistronic retrovirus-mediated gene therapy in human cord blood CD34+ cells.

[Study of conformation of serum albumin by FTIR]

This paper used the FTIR method to study the spectra of bovine serum albumin (BSA) and its solution. The secondary structure and conformation was assigned by FTIR-deconvolution analysis. The result indicated that BSA secondary structure in solid is different from in aqueous solution. As the decrease of BSA concentration from 3.241 x 10(-1) to 4.032 X 10(-2) g X mL(-1), the amide I band components at 1 609.84, 1 633.85,1 653.69, 1 681.16 and 1 694.88 cm(-1) shifted to 1 608. 24, 1 638.36, 1 656.10, 1 674.87 and 1 690.78 cm(-1), respectively, the component at 1 621.50 cm(-1) unchanged.

[Acute toxicity of Stephania cepharantha]

The acute toxicity of Stephania cepharantha was studied, LD50 of aqueous extract of its wet and dry root tuber oral were 41.4 g/kg and 22.9 g/kg respectively.

[Synergistic interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines in vitro]

OBJECTIVE

To study in vitro the anticancer interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines.

METHOD

Using human breast cancer cell MCF-7 and its adriamycin-resistant cell line MCF-7/Adr, and human nasopharyngeal cancer cell KB and its vincristine-resistant cell line KBv200 in an in vitro system, anticancer interaction between Ys-96 and adriamycin or vincristine was evaluated with a method reported by Berenbaum.

RESULT

The SFIC values (sum of fractional inhibitory concentration) of the combinations with 3 different ratios between Ys-96 and adriamycin or vincristine were markedly less than 1.0, and the shapes of all the isobologram curves were concave.

CONCLUSION

The synergistic interaction between Ys-96 and adriamycin or vincristine against the above human cancer cell lines was positively observed in vitro.

Ab initio studies of some amino acid residue complexes with 4-mercaptopyridine as a model for thymitaq (AG337), an inhibitor of thymidylate synthase

The complex formed by isopentane, as a model for the isoleucine residue present in the wild-type thymidylate synthase, with 4-mercaptopyridine as a fragment of the thymidylate synthase inhibitor Thymitaq (AG337) is investigated with ab initio quantum chemical calculations at Hartree-Fock and MP2 levels, using the 3-21G* basis set. The binding energy is compared with the binding energies of 4-mercaptopyridine with amino acid residues found in mutant thymidylate synthase enzymes. As compared with isoleucine, alanine and glycine do not show binding, in agreement with enzyme-inhibition results.