Biomedical subjects

Jing Chen

Publications and source records attributed to Jing Chen.

At least 127 records · Page 7Linked to original sources

PubMed2006

[Studies on HPLC-FPS of the saponins from Semen Ziziphi Spinosae].

OBJECTIVE: To establish a method of HPLC-fingerprint spectrum (HPLC-FPS) for the active part in Semen Ziziphi Spinosae (SZS) in order to control the quality of SZS from different places. METHODS: The gradient elution mode was applied in chromatographic separation, and data were analysed by" Similarity Evaluation software" to compare the HPLC-FPS of SZS from different places. RESULTS: The conditions for HPLC analysis of SZS were established and the FPS of samples from different habitats showed some differences. CONCLUSION: All components in the spectrum were separated well and the HPLC fingerprint method is repeatable. The method can be used in quality assessment of SZS.

Chromatography, High Pressure Liquid↗

PubMed2006

[Apoptosis of psoriatic keratinocytes and the severity of patients' condition].

OBJECTIVE: To investigate the correlation between the apoptosis of psoriatic keratinocytes (KCs) in the psoriatic lesions and patient's condition. METHODS: Thirty patients with psoriasis were included. Activated caspase-3 was examined by colorimetric method in skin biopsy specimens. The apoptotic KCs were detected with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay in skin biopsy specimens. The severities of 26 patients with psoriasis vulgaris (PV) were assessed using the PASI scoring system and the severities of psoriatic lesions. RESULTS: Apoptotic indexes (AI) were higher in the pustular psoriatic lesions than those in the vulgaris psoriatic lesions (P<0.05). In 26 patients with PV, AI and activated caspase-3 in the lesions were significantly higher in the progressive stage than those in the static and the regressive stages (P<0.05). There were no correlations between PASI and AI or the expression of activated caspase-3 in PV lesions (P>0.05). The severities of psoriatic lesions were positively correlated to AI or the expression of activated caspase-3 in PV lesions (P<0.05). CONCLUSION: The amount of apoptotic KCs may be related to varied types, stages of psoriasis, and severities of psoriatic lesions.

Adolescent↗

PubMed2006

[Comprehensive protocol for diagnosis and treatment of childhood neuroblastoma--results of 45 cases].

OBJECTIVE: The aim of the paper was to improve the prognosis of neuroblastoma (NB) stage III and IV in children through the comprehensive therapy including chemotherapy, delayed tumor resection, autologous stem cell transplantation (ASCT) and inducing differentiation and to analyze the factors affecting the prognosis. METHODS: Newly diagnosed neuroblastoma patients seen from Oct.1998 to Dec.2003 were divided into high, medium and low risk groups depending on clinical stage and age. Comprehensive protocol included accurate staging, delayed and/or second tumor resection for stage III and IV patients, chemotherapy of different intensity mainly composed of cell cycle nonspecific drugs and 13-cis-retinoid for inducing cell differentiation. ASCT was given at the end of therapy for high risk group. RESULT: Forty-five patients, 6 months to 11 years of age, 32 males and 13 females, were analyzed. Of them, 15 were found to have the tumor in adrenal gland, 12 had the tumor extended to the retro-peritoneal space, while in 15 cases the tumor was beside the spinal column in chest and in 3 the tumor was located in other places. Nine cases had stage I, 1 case had stage II, 8 cases had III, 26 cases had stage IV and 1 case had stage IVs of the tumor. Depending on the age and stage of the tumor, 26 cases were aligned into high risk protocol, 10 into medium risk and 9 into low risk groups. Thirty nine cases were treated as planned. Eleven of them received ASCT including 2 cases who received second ASCT. Of the thirty-nine patients, 31 achieved complete remission (CR) and 8 partial remission (PR) after surgery and/or chemotherapy. During up to 21 months median following up period (range 14 to 64 months), 24 cases (62%) kept CR (median 22 months) and 4 survived with stable disease. The survival rate (SR) was 72%. Eleven cases died of relapse and disease progression. No death occurred from treatment complication. Statistical analysis showed that the age older than 18 months, and stage III and IV of the tumor were the factors predicting poor prognosis (P = 0.04 and 0.003, respectively). Patients who had the tumor originated from the retroperitoneal space, who had incomplete tumor resection, and those who did not receive ASCT had poorer prognosis, but the differences were not significant (P = 0.092, 0.55 and 0.60, respectively). CONCLUSION: The comprehensive protocol seemed to be reasonable. Age older than 18 months, and stage III and IV were the factors suggesting poor prognosis. The origin of the tumor, completeness of tumor resection, and use of ASCT had no significant impact on the prognosis.

Age Factors↗

PubMed2005

Effects of a leukemia-associated gain-of-function mutation of SHP-2 phosphatase on interleukin-3 signaling.

Mutations in SHP-2 phosphatase that cause hyperactivation of its catalytic activity have been identified in human leukemias, particularly juvenile myelomonocytic leukemia, which is characterized by hypersensitivity of myeloid progenitor cells to granulocyte macrophage colony-stimulating factor and interleukin (IL)-3. However, the molecular mechanisms by which gain-of-function (GOF) mutations of SHP-2 induce hematopoietic malignancies are not fully understood. Our previous studies have shown that SHP-2 plays an essential role in IL-3 signal transduction in both catalytic-dependent and -independent manners and that overexpression (5-6-fold) of wild type (WT) SHP-2 attenuates IL-3-mediated hematopoietic cell function through accelerated dephosphorylation of STAT5. These results raised the possibility that SHP-2-associated leukemias are not solely attributed to the increased catalytic activity of GOF mutant SHP-2. GOF mutant SHP-2 must have gained additional capacities. To test this possibility, we investigated effects of a GOF mutation of SHP-2 (SHP-2 E76K) on hematopoietic cell function and IL-3 signal transduction by comparing with those of overexpressed WT SHP-2. Our results showed that SHP-2 E76K mutation caused myeloproliferative disease in mice, while overexpression of WT SHP-2 decreased hematopoietic potential of the transduced cells in recipient animals. The E76K mutation in the N-terminal Src homology 2 domain increased interactions of mutant SHP-2 with Grb2, Gab2, and p85, leading to hyperactivation of IL-3-induced Erk and phosphatidylinositol 3-kinase (PI3K) pathways. In addition, despite the substantial increase in the catalytic activity, dephosphorylation of STAT5 by SHP-2 E76K was dampened. Furthermore, catalytically inactive SHP-2 E76K with an additional C459S mutation retained the capability to increase the interaction with Gab2 and to enhance the activation of the PI3K pathway. Taken together, these studies suggest that in addition to the elevated catalytic activity, fundamental changes in physical and functional interactions between GOF mutant SHP-2 and signaling partners also play an important role in SHP-2-related leukemigenesis.

Adaptor Proteins, Signal Transducing↗

PubMed2005

FGFR3 as a therapeutic target of the small molecule inhibitor PKC412 in hematopoietic malignancies.

Reccurent chromosomal translocation t(4;14) (p16.3;q32.3) occurs in patients with multiple myeloma (MM) and is associated with ectopic overexpression of fibroblast growth factor receptor 3 (FGFR3) that sometimes may contain the activation mutations such as K650E thanatophoric dysplasia type II (TDII). Although there have been significant advances in therapy for MM including the use of proteasome inhibitors, t(4;14) MM has a particularly poor prognosis and most patients still die from complications related to their disease or therapy. One potential therapeutic strategy is to inhibit FGFR3 in those myeloma patients that overexpress the receptor tyrosine kinase due to chromosomal translocation. Here we evaluated PKC412, a small molecule tyrosine kinase inhibitor, for treatment of FGFR3-induced hematopoietic malignancies. PKC412 inhibited kinase activation and proliferation of hematopoietic Ba/F3 cells transformed by FGFR3 TDII or a TEL-FGFR3 fusion. Similar results were obtained in PKC412 inhibition of several different t(4;14)-positive human MM cell lines. Furthermore, treatment with PKC412 resulted in a statistically significant prolongation of survival in murine bone marrow transplant models of FGFR3 TDII-induced pre-B cell lymphoma, or a peripheral T-cell lymphoma associated TEL-FGFR3 fusion-induced myeloproliferative disease. These data indicate that PKC412 may be a useful molecularly targeted therapy for MM associated with overexpression of FGFR3, and perhaps other diseases associated with dysregulation of FGFR3 or related mutants.

Animals↗

PubMed2005

Effect of compressed CO2 on the chloroperoxidase catalyzed halogenation of 1,3-dihydroxybenzene in reverse micelles.

The effect of compressed CO2 on the specific activity of chloroperoxidase (CPO) to catalyze the chlorination of 1,3-dihydroxybenzene in cetyltrimethylammonium chloride (CTAC)/H2O/octane/pentanol reverse micellar solution was studied. The results show that the specific activity of the enzyme can be enhanced significantly by compressed CO2, and the specific activity can be tuned continuously by changing pressure. The mechanism for the specific activity enhancement of the enzyme by CO2 was also studied. We believe that compressed CO2 can be utilized to tune some other enzyme catalytic reactions in different reverse micellar systems with potential advantages.

Journal Article↗

PubMed2005

Discovering novel chemical inhibitors of human cyclophilin A: virtual screening, synthesis, and bioassay.

Cyclophilin A (CypA) is a member of cyclophilins, a family of the highly homologous peptidyl prolyl cis-trans isomerases (PPIases), which can bind to cyclosporin A (CsA). CypA plays critical roles in various biological processes, including protein folding, assembly, transportation, regulation of neuron growth, and HIV replication. The discovery of CypA inhibitor is now of a great special interest in the treatment of immunological disorders. In this study, a series of novel small molecular CypA inhibitors have been discovered by using structure-based virtual screening in conjunction with chemical synthesis and bioassay. The SPECS_1 database containing 85,000 small molecular compounds was searched by virtual screening against the crystal structure of human CypA. After SPR-based binding affinity assay, 15 compounds were found to show binding affinities to CypA at submicro-molar or micro-molar level (compounds 1-15). Seven compounds were selected as the starting point for the further structure modification in considering binding activity, synthesis difficulty, and structure similarity. We thus synthesized 40 new small molecular compounds (1-6, 15, 16a-q, 17a-d, and 18a-l), and four of which (compounds 16b, 16h, 16k, and 18g) showed high CypA PPIase inhibition activities with IC50s of 2.5-6.2 microM. Pharmacological assay indicated that these four compounds demonstrated somewhat inhibition activities against the proliferation of spleen cells.

Animals↗

PubMed2005

Radiation quality of photons in small and large receptors--a microdosimetric analysis.

The quality of different photon radiations in small and large receptors is assessed in terms of microdosimetry. Monte Carlo simulations are performed for the electrons released by photons. To represent the case of a small receptor, only electrons released by the non-degraded incident photons are tracked. For a large receptor, all electrons released in the complete degradation process are followed. Dose averaged values, y(D), of the lineal energy are derived from the simulated tracks for monoenergetic photons from 10 keV to 2 MeV. In microdosimetry, the dose mean lineal energy is the major parameter of radiation quality. The results demonstrate distinct differences in radiation quality between high-energy gamma rays and conventional X rays that are present not just in small cell samples but also in large receptors, such as the human body. The values of y(D) suggest that, for both small and large receptors, conventional X rays should be about twice as effective as gamma rays from 60Co.

Algorithms↗

PubMed2005

"Agouti NOD": identification of a CBA-derived Idd locus on Chromosome 7 and its use for chimera production with NOD embryonic stem cells.

Penetrance of the complex of genes predisposing the nonobese diabetic (NOD) mouse to autoimmune diabetes is affected by the maternal environment. NOD.CBALs-Tyr(+)/Lt is an agouti-pigmented Chromosome 7 congenic stock of NOD/Lt mice produced as a resource for embryo transfer experiments to provide the necessary maternal factors and allow the easy identification of NOD (albino) embryo donor phenotype. CBcNO6/Lt, a recombinant congenic agouti stock already containing approximately 50% NOD genome, was used as the donor source of a wild-type CBA tyrosinase allele. When the incidence of diabetes was assessed after nine generations of backcrossing and one generation of sib-sib mating, significant reduction in diabetes development was observed. No difference in diabetes development was observed in Tyr/Tyr(c) heterozygotes, showing that protection was recessive. Analysis of diabetes progression in another NOD stock congenic for C57BL/6 alleles on Chromosome 7 linked to the glucose phosphate isomerase (Gpi1(b)) locus provided no protection, indicating that the diabetes resistance (Idd) gene was distal to 34 cM (D7Mit346). Approximately 5 cM of the distal congenic region overlaps a region from C57L previously associated with protection when homozygous. The delayed onset and reduced frequency of diabetes in the NOD.CBALs-Tyr(+)/Lt stock is an advantage when females of this stock are used as surrogate mothers in studies involving hysterectomy or embryo transfers. Indeed, a newly developed NOD embryonic stem (ES) cell line injected into NOD.CBALs- Tyr(+)/Lt blastocysts produced approximately 50% live-born mice, of which approximately 11% were chimeric. Presumably because of high genomic instability, no germline transmission was observed.

Animals↗

PubMed2005

Investigation of non-typeable Haemophilus influenzae outer membrane protein P6 as a new carrier for lipooligosaccharide conjugate vaccines.

Non-typeable Haemophilus influenzae (NTHi) outer membrane protein P6 was used as a new protein carrier for NTHi detoxified lipooligosaccharide (dLOS) conjugates due to its conservation and potential to elicit bactericidal antibodies. P6 was covalently conjugated to dLOS of strain 9274 through adipic acid dihydrazide with different ratios of dLOS to P6, which resulted in two conjugate formulations with weight ratios of dLOS to P6 of 3.7 for dLOS-P6 (I) and 1.6 for dLOS-P6 (II). Binding activity of the conjugates was examined by an enzyme-linked immunosorbent assay with mouse monoclonal antibodies specific to LOS and P6 and a rabbit anti-P6 serum. The results showed that the conjugates bound not only to the LOS antibody but also to both P6 antibodies, suggesting that the conjugates retained epitopes of both LOS and P6 antigens. Animal studies revealed that dLOS-P6 (II) induced high levels of anti-LOS and anti-P6 IgGs in mice and rabbits. However, dLOS-P6 (I) induced lower levels of anti-LOS IgGs in mice and rabbits and anti-P6 IgGs in rabbits with no anti-P6 IgGs in mice. In addition, all rabbit, but not mouse, antisera elicited by the conjugates showed bactericidal activity against the homologous strain, and two of them elicited by each conjugate plus Ribi adjuvant showed cross-bactericidal activity against three of five major serotype stains. These data indicate that P6 could serve as an effective carrier for dLOS or other carbohydrate conjugates and that the ratio of carbohydrate to P6 might contribute to immune responses in vivo.

Animals↗

PubMed2005

Receptor-binding domain of SARS-Cov spike protein: soluble expression in E. coli, purification and functional characterization.

AIM: Spike protein of coronavirus is responsible for virus binding, fusion and entry, and is a major inducer of neutralizing antibodies. This paper was to find a soluble and functional recombinant receptor-binding domain of severe acute respiratory syndrome-associated coronavirus (SARS-Cov), and to analyze its receptor binding ability. METHODS: Three fusion tags (glutathione S-transferase, GST; thioredoxin, Trx; maltose-binding protein, MBP), which preferably contributes to increasing solubility and to facilitating the proper folding of heteroprotein, were used to acquire the soluble and functional expression of RBD protein in Escherichia coli (BL21(DE3) and Rosetta-gamiB(DE3) strains). The receptor binding ability of the purified soluble RBD protein was then detected by ELISA and flow cytometry assay. RESULTS: RBD of SARS-Cov spike protein was expressed as inclusion body when fused as TrxA tag form in both BL21 (DE3) and Rosetta-gamiB (DE3) under many different cultures and induction conditions. And there was no visible expression band on SDS-PAGE when RBD was expressed as MBP tagged form. Only GST tagged RBD was soluble expressed in BL21(DE3), and the protein was purified by AKTA Prime Chromatography system. The ELISA data showed that GST/RBD antigen had positive reaction with anti-RBD mouse monoclonal antibody 1A5. Further flow cytometry assay demonstrated the high efficiency of RBD's binding ability to ACE2 (angiotensin-converting enzyme 2) positive Vero E6 cell. And ACE2 was proved as a cellular receptor that meditated an initial-affinity interaction with SARS-Cov spike protein. The geometrical mean of GST and GST/RBD binding to Vero E6 cells were 77.08 and 352.73 respectively. CONCLUSION: In this paper, we get sufficient soluble N terminal GST tagged RBD protein expressed in E.coli BL21(DE3); data from ELISA and flow cytometry assay demonstrate that the recombinant protein is functional and binding to ACE2 positive Vero E6 cell efficiently. And the recombinant RBD derived from E.coli can be used to developing subunit vaccine to block S protein binding with receptor and to neutralizing SARS-Cov infection.

Animals↗

PubMed2005

Identification of a ferrireductase required for efficient transferrin-dependent iron uptake in erythroid cells.

The reduction of iron is an essential step in the transferrin (Tf) cycle, which is the dominant pathway for iron uptake by red blood cell precursors. A deficiency in iron acquisition by red blood cells leads to hypochromic, microcytic anemia. Using a positional cloning strategy, we identified a gene, six-transmembrane epithelial antigen of the prostate 3 (Steap3), responsible for the iron deficiency anemia in the mouse mutant nm1054. Steap3 is expressed highly in hematopoietic tissues, colocalizes with the Tf cycle endosome and facilitates Tf-bound iron uptake. Steap3 shares homology with F(420)H(2):NADP(+) oxidoreductases found in archaea and bacteria, as well as with the yeast FRE family of metalloreductases. Overexpression of Steap3 stimulates the reduction of iron, and mice lacking Steap3 are deficient in erythroid ferrireductase activity. Taken together, these findings indicate that Steap3 is an endosomal ferrireductase required for efficient Tf-dependent iron uptake in erythroid cells.

Amino Acid Sequence↗

PubMed2005

Relation of inflammation to peripheral arterial disease in the national health and nutrition examination survey, 1999-2002.

The relation between inflammation and peripheral arterial disease (PAD) is not well characterized. This study examined this relation and its consistency across important subgroups in a cross-sectional, nationally representative sample of the adult United States population. C-reactive protein (CRP), fibrinogen, leukocyte count, and PAD were assessed in a sample of 4,787 participants aged>or=40 years in the National Health and Nutrition Examination Survey 1999-2002. PAD was defined as an ankle-brachial blood pressure index <0.9. Graded relations were present between inflammatory markers and PAD. The multivariate adjusted odds ratios of PAD associated with the highest versus the lowest quartile of CRP, fibrinogen, and leukocyte count were 2.14 (95% confidence interval [CI] 1.41 to 3.25), 2.49 (95% CI 1.27 to 4.85), and 1.67 (95% CI 0.84 to 3.31), respectively (each p trend<0.05 across quartiles). Associations between inflammation and PAD were similar across gender, obesity, and diabetic subgroups. However, the odds ratios of PAD for the highest CRP quartile versus the 3 lowest quartiles were 3.10 (95% CI 1.76 to 5.45) for non-Hispanic blacks versus 1.50 (95% CI 0.98 to 2.28) for non-Hispanic whites and 1.11 (95% CI 0.57 to 2.17) for Mexican Americans (p interaction=0.049) and 5.59 (95% CI 1.82 to 17.17) for patients aged 40 to 54 years versus 2.01 (95% CI 1.13 to 3.58) for patients aged 55 to 69 years and 0.98 (95% CI 0.65 to 1.48) for patients aged>or=70 years (p interaction=0.018). Odds ratios of PAD for the highest fibrinogen quartile versus the lowest 3 quartiles were 3.26 (95% CI 1.69 to 6.28) for current smokers versus 0.83 (95% CI 0.51 to 1.35) for never smokers (p interaction=0.006). In conclusion, in the general United States adult population, inflammation is independently associated with PAD.

Adult↗

PubMed2005

The MLL fusion gene, MLL-AF4, regulates cyclin-dependent kinase inhibitor CDKN1B (p27kip1) expression.

MLL, involved in many chromosomal translocations associated with acute myeloid and lymphoid leukemia, has >50 known partner genes with which it is able to form in-frame fusions. Characterizing important downstream target genes of MLL and of MLL fusion proteins may provide rational therapeutic strategies for the treatment of MLL-associated leukemia. We explored downstream target genes of the most prevalent MLL fusion protein, MLL-AF4. To this end, we developed inducible MLL-AF4 fusion cell lines in different backgrounds. Overexpression of MLL-AF4 does not lead to increased proliferation in either cell line, but rather, cell growth was slowed compared with similar cell lines inducibly expressing truncated MLL. We found that in the MLL-AF4-induced cell lines, the expression of the cyclin-dependent kinase inhibitor gene CDKN1B was dramatically changed at both the RNA and protein (p27kip1) levels. In contrast, the expression levels of CDKN1A (p21) and CDKN2A (p16) were unchanged. To explore whether CDKN1B might be a direct target of MLL and of MLL-AF4, we used chromatin immunoprecipitation (ChIP) assays and luciferase reporter gene assays. MLL-AF4 binds to the CDKN1B promoter in vivo and regulates CDKN1B promoter activity. Further, we confirmed CDKN1B promoter binding by ChIP in MLL-AF4 as well as in MLL-AF9 leukemia cell lines. Our results suggest that CDKN1B is a downstream target of MLL and of MLL-AF4, and that, depending on the background cell type, MLL-AF4 inhibits or activates CDKN1B expression. This finding may have implications in terms of leukemia stem cell resistance to chemotherapy in MLL-AF4 leukemias.

Cell Line↗

PubMed2005

Major causes of death among men and women in China.

BACKGROUND: With China's rapid economic development, the disease burden may have changed in the country. We studied the major causes of death and modifiable risk factors in a nationally representative cohort of 169,871 men and women 40 years of age and older in China. METHODS: Baseline data on the participants' demographic characteristics, medical history, lifestyle-related risk factors, blood pressure, and body weight were obtained in 1991 with the use of a standard protocol. The follow-up evaluation was conducted in 1999 and 2000, with a follow-up rate of 93.4 percent. RESULTS: We documented 20,033 deaths in 1,239,191 person-years of follow-up. The mortality from all causes was 1480.1 per 100,000 person-years among men and 1190.2 per 100,000 person-years among women. The five leading causes of death were malignant neoplasms (mortality, 374.1 per 100,000 person-years), diseases of the heart (319.1), cerebrovascular disease (310.5), accidents (54.0), and infectious diseases (50.5) among men and diseases of the heart (268.5), cerebrovascular disease (242.3), malignant neoplasms (214.1), pneumonia and influenza (45.9), and infectious diseases (35.3) among women. The multivariate-adjusted relative risk of death and the population attributable risk for preventable risk factors were as follows: hypertension, 1.48 (95 percent confidence interval, 1.44 to 1.53) and 11.7 percent, respectively; cigarette smoking, 1.23 (95 percent confidence interval, 1.18 to 1.27) and 7.9 percent; physical inactivity, 1.20 (95 percent confidence interval, 1.16 to 1.24) and 6.8 percent; and underweight (body-mass index [the weight in kilograms divided by the square of the height in meters] below 18.5), 1.47 (95 percent confidence interval, 1.42 to 1.53) and 5.2 percent. CONCLUSIONS: Vascular disease and cancer have become the leading causes of death among Chinese adults. Our findings suggest that control of hypertension, smoking cessation, increased physical activity, and improved nutrition should be important strategies for reducing the burden of premature death among adults in China.

Adult↗

PubMed2005

Electrochemical immunoassay of membrane P-glycoprotein by immobilization of cells on gold nanoparticles modified on a methoxysilyl-terminated butyrylchitosan matrix.

A strategy to detect P-glycoprotein (P-gp) on cell membrane and quantify the cell number using electrochemical immunoassay was developed by effective surface immunoreactions and immobilization of cells on a highly hydrophilic interface, which was constructed by adsorption of colloidal gold nanoparticles on a methoxysilyl-terminated (Mos) butyrylchitosan modified glassy carbon electrode (Au-CS/GCE). Atomic force microscopy studies proved that the nanoparticles adsorbed on Mos-butyrylchitosan were efficient in preventing the cell leakage and retaining the activity of immobilized living K562/ADM leukemic cells. The incubation with P-gp monoclonal antibody and then the secondary alkaline phosphatase (AP) conjugated antibody introduced AP onto the K562/ADM cell immobilized on Au-CS/GCE. The bound AP led to an amperometric response of 1-naphthyl phosphate. Under optimal conditions the response was proportional to the logarithm of cell concentration in the range from 5.0 x 10(4) to 1.0 x 10(7) cells mL(-)(1) with a detection limit of 1.0 x 10(4) cells mL(-)(1). The results were comparable to flow cytometric analysis of P-gp expression. This proposed method was practical, convenient, and significant in the clinic and cytobiology.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

Construction of a biomimetic zwitterionic interface for monitoring cell proliferation and apoptosis.

A new zwitterionic monolayer film of sulfobetaine was constructed by grafting novelly designed N,N-dimethyl (beta-hydroxyethyloxyethyl) ammonium propanesulfonate (DHAPS) to hydroxyl groups of glass in the presence of hexamethylene diisocyanate (HDI) as a coupling agent and dibutyltin dilaurate (DBTDL) as a catalyst. Experiments of blood adhesion proved that the zwitterionic film possessed excellent hydrophilicity and very good biocompatibility and provided an appropriate biomimetic interface for adhesion and proliferation of cells. Thus, the monitoring of the cell proliferation and apoptotic processes on the zwitterionic surface during an incubation process was achieved, using different techniques, such as electrochemical impedance spectroscopy, scanning electron microscopy, flow cytometric assay, and Trypan blue staining. K562 leukemia cells, as a model, cultured in vitro on the zwitterionic surface kept their viability for 5 days and remained healthy and undifferentiated, indicating that the zwitterionic surface did not have a deleterious effect on cell growth in normal conditions. Thus, this man-made interface would be applicable to the growth of cells and the study of biomaterial-cell interaction and has potential applications in medicine and cytobiology.

Alkanesulfonic Acids↗

PubMed2005

The combination of the farnesyl transferase inhibitor lonafarnib and the proteasome inhibitor bortezomib induces synergistic apoptosis in human myeloma cells that is associated with down-regulation of p-AKT.

The identification of signaling pathways critical to myeloma growth and progression has yielded an array of novel agents with clinical activity. Multiple myeloma (MM) growth is IL-6 dependent, and IL-6 is secreted in an autocrine/paracrine fashion with signaling via the Ras/Raf/mitogen-activated protein kinase (MAPK) pathway. We hypothesized that combining a Ras pathway inhibitor (lonafarnib, SCH66336) with a proteasome inhibitor (bortezomib, Velcade, PS-341) would enhance myeloma-cell killing. MM cell lines and primary human cells were used to test either single agent bortezomib, lonafarnib, or the combination on MM signaling and apoptosis. Combination therapy induced synergistic tumor-cell death in MM cell lines and primary MM plasma cells. Cell death was rapid and associated with increased caspase 3, 8, and 9 cleavage and concomitant down-regulation of p-AKT. Down-regulation of p-AKT was seen only in combination therapy and not seen with either single agent. Cells transfected with constitutively active p-AKT, wild-type AKT, or Bcl-2 continued to demonstrate synergistic cell death in response to the combination. The order of addition was critically important, supporting bortezomib followed by lonafarnib as the optimal schedule. The combination of a proteasome inhibitor and farnesyl transferase inhibitor demonstrates synergistic myeloma-cell death and warrants further preclinical and clinical studies.

Apoptosis↗