Fifth-order corrected field descriptions of the Hermite-Gaussian (0,0) and (0,1) mode laser beam

In this paper, we extend the work of Barton and Alexander [J. App. Phys. 66, 2800 (1989)] on the fifth-order corrected field expressions for a Hermite-Gaussian (0,0) mode laser beam to more general cases with adjustable parameters. The parametric dependence of the electron dynamics is investigated by numerical methods. Finally, the fifth-order corrected field equations for the Hermite-Gaussian (0,1) mode are also presented.

Polycystic ovarian syndrome and the risk of spontaneous abortion following assisted reproductive technology treatment

BACKGROUND

A high proportion of infertile patients have polycystic ovarian syndrome (PCOS) with a reportedly greater risk of spontaneous abortion. Because of the close link between PCOS and obesity and the independent association of obesity with poor pregnancy outcomes, it is important to distinguish the possible confounding effect of body mass index (BMI) or other variables from that of PCOS. This study aims to determine the effect of PCOS status on the risk of spontaneous abortion with adjustment for body mass and several other confounding factors in a large cohort of pregnant infertile women.

METHODS

The patients (n = 1018) were treated in a tertiary infertility centre. Their PCOS status was determined by standard criteria and their BMI had been taken less than 1 year before the pregnancy. Patients whose PCOS status or BMI measurements were not assessed were excluded. Student's t-test or chi2 test were used to test the difference between the PCOS and non-PCOS groups while a multivariate logistical regression model was used to assess the effect of PCOS, BMI and other confounding factors.

RESULTS

Overall, the incidence of PCOS was 37% in this cohort. The overall incidence of spontaneous abortion in the study population was 21%. Univariate analysis showed that women with PCOS had a significantly greater risk of spontaneous abortion compared with non-PCOS women (25 versus 18%, P < 0.01). However, using multivariate logistic regression analysis this effect was reduced to a non-significant level [odds ratio (OR) = 1.10, 95% confidence interval (CI) 0.85-1.36] after adjusting for obesity and patients/treatment combination factor, and to nil after adjusting for all confounding factors considered in this study (OR = 0.98, 95% CI 0.75-1.28).

CONCLUSION

The results of this study suggest that the higher risk of spontaneous abortion observed in women with PCOS is likely to be due to their high prevalence of obesity and the type of treatment they receive.

Frozen-thawed embryo transfer: influence of clinical factors on implantation rate and risk of multiple conception

BACKGROUND

Frozen embryo transfer is an important supplementary procedure in the treatment of infertility. While general information concerning the outcome of frozen embryo transfer has been documented, few studies have addressed the potential of embryo implantation in particular clinical situations. Importantly, the risk of multiple conception following frozen embryo transfer has been poorly documented compared with the information available for fresh embryo transfer.

METHODS

This is a retrospective study analysing 3570 frozen embryo transfer cycles (1438 couples) with a view to increasing our understanding of the clinical circumstances that influence the potential for embryo implantation.

RESULTS

The overall implantation rate was 9.1%. The characteristics associated with a more favourable implantation rate were the success of the previous fresh embryo transfer cycle, age < 40 years and non-tubal factor aetiology of infertility. Such women had an increased risk of multiple conception.

CONCLUSION

Female age, the aetiology of infertility and the outcome of fresh embryo transfer are the most important factors influencing the implantation rate following frozen embryo transfer. A prognostic table has been constructed that may assist with the determination of the optimal number of embryos to be replaced in frozen embryo transfer to provide better individualized counselling and to secure an optimal chance of pregnancy while reducing the risk of multiple conception.

[Study on brain targeting 3',5'-dioctanoyl-5-fluoro-2'-deoxyuridine pharmacosomes]

AIM

To investigate the specific brain drug targeting of 5-fluoro-2'-deoxyuridine (FUdR) by synthesis of 3', 5'-dioctanoyl-5-fluoro-2'-deoxyuridine (DO-FUdR) and incorporation into DO-FUdR pharmacosomes (DO-FUdR-PS).

METHODS

DO-FUdR-PS was prepared by thin-layer ultrasonication technique. In vitro drug release was studied in pH 7.4 phosphate-buffered saline containing 0.3% pancreatic enzyme at 37 degrees C using bulk-equilirium reverse dialysis bag technique. The concentration of FUdR in various organs were determined by reversed phase HPLC after i.v. administration of DO-FUdR-PS and FUdR.

RESULTS

The mean particle size of DO-FUdR-PS was 76 nm with drug loading of 29.02% and entrapment efficiency of 96.62%. The in vitro drug release kinetics could be characterized by bioexponential equation. Compared with FUdR injection, DO-FUdR-PS showed high concentration in tested organs. The brain AUC ratio of DO-FUdR-PS to FUdR was 10.97.

CONCLUSION

DO-FUdR-PS showed a good targeting efficiency in vivo. PS can improve the ability of drug to cross blood-brain barrier and is a promising drug targeting system for the treatment of central nervous system disorders.

Adsorption configuration and local ordering of silicotungstate anions on Ag(100) electrode surfaces

X-ray reflectivity, cyclic voltammetry, and scanning tunneling microscopy (STM) are used to examine the structure of alpha-SiW12O4(4-) or silicotungstic acid (STA) adsorbed on Ag(100) in acid solution. The voltammetry shows that STA passivates the Ag surface relative to electron transfer to a solution redox species. STM images reveal the formation of a series of lattice structures, one of which can be associated with a commensurate ( radical13x radical13)R33.69 degrees structural model. X-ray reflectivity measurements show uniquely that STA orients with its four-fold axis perpendicular to the Ag(100) surface and that the center of the STA molecule is 4.90 A above the top layer of the Ag substrate. Analysis of bond lengths leads to a footprint of STA on Ag(100), in which the four terminal O atoms are located near the hollow sites and have a Ag-O bond length of 2.06 A. This bond length is consistent with a strong covalent interaction between STA and the Ag surface.

Relative risk of conversion from normoglycaemia to impaired glucose tolerance or non-insulin dependent diabetes mellitus in polycystic ovarian syndrome

BACKGROUND

Cross-sectional studies have shown a high frequency of impaired glucose tolerance (IGT) and non-insulin dependent diabetes mellitus (NIDDM) in women with polycystic ovarian syndrome (PCOS). However, little is known about the change in glucose tolerance that occurs over a period of several years in women with PCOS.

METHODS

Sixty-seven women with PCOS received a 75 g glucose tolerance test and measurement of lipids at baseline and at follow-up after an average time of 6.2 years. All women followed prospectively had normal glucose tolerance (n = 54) or IGT (n = 13) at the start of the study.

RESULTS

Change in glycaemic control from baseline was frequent, with 5/54 (9%) of normoglycaemic women at baseline developing IGT and a further 4/54 (8%) moving directly from normoglycaemic to NIDDM. For women with IGT at baseline, 7/13 (54%) had NIDDM at follow-up. Body mass index (BMI) at baseline was an independent significant predictor of adverse change in glycaemic control.

CONCLUSIONS

Women with PCOS, particularly those with a high BMI, should be reviewed regularly with respect to IGT or NIDDM, as the frequency of impaired glycaemic control is high, and that the rate of conversion from normal glucose tolerance to IGT or NIDDM, or from IGT to NIDDM is substantial.

Measurement of the rate of nu(e) + d --> p + p + e(-) interactions produced by (8)B solar neutrinos at the Sudbury Neutrino Observatory

Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.07(stat)(+0.12)(-0.11)(syst) +/- 0.05(theor) x 10(6) cm(-2) s(-1). Comparison of straight phi(CC)(nu(e)) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3 sigma difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- nu(e) component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99 x 10(6) cm(-2) s(-1).

[Optimization of the preparation of 3',5'-dioctanoyl-5-fluoro-2'-deoxyuridine pharmacosomes using central composite design]

AIM

To optimize the preparation of 3', 5'-dioctanoyl-5-fluoro-2'-deoxyuridine pharmacosomes (DO-FUdR-PS) by using central composite design.

METHODS

DO-FUdR-PS was prepared by a thin-layer ultrasonication technique. The effects of drug phosphatidycholine ratio, pluronic F-68 concentration (%, w/v) and glycerol tristearate (%, w/v) concentration on the mean particle size, entrapment ratio (ER) and drug loading (DL) were investigated. A second-order polynomial equation was fitted to the data and the resulting model was used to predict the response in the optimal region.

RESULTS

All the investigated response variables were found to be highly dependent on the formulation variables. Under the optimized conditions, the mean particle size, ER and DL of DO-FUdR-PS were 76 nm, 97.49% and 31.44%, respectively, which highly agreed with the predicted values.

CONCLUSION

Central composite design was successfully used to optimize the preparation of DO-FUdR-PS.

[Genetic instability in cancer tissues analyzed by RAPD PCR]

In five kinds of tumors, total 128 specimens were analyzed by RAPD (random amplified polymorphic DNA) PCR with nine 10-base arbitrary primers for detecting instabilities of DNA and chromosome and screening new molecular markers coupled to putative or unknown oncogenes and/or tumor suppressor genes. Bands representing instabilities have been recovered and purified from agarose and cloned into pCAPs vector, and further labeled by DIG as probes for analysis of Southern blot, Northern blot and Sequencing. Results revealed that sample 5 and 3 of the gastric cancers showed the highest genomic changes and the average detectability in five sorts of cancers was up to at least 40% (42.2%-49.4%), and that there were significant differences in the ability of each primer to detect genomic instability, which ranged from 27% to 68%. Despite the highest detectability of genetic instability (68%) in tumor tissues, primer 2 could produce stable profiles of DNA bands in normal tissue genome with good reproducibility. On the contrary, primer 8 was of the lowest one (27%). Band B of single copy found to be allelic losses in gastric and colon cancers according to RFLP analysis was of a novel sequence and registered by Gen-Bank (Accession Number AF151005). Therefore the genetic instabilities often concentrated on some special locuses of chromosome e.g. repetitive sequences etc. and coupled to carcinogenesis. It was impossible or difficult to get great achievements for cancer treatments with the procedure of gene therapy only to one oncogene or one tumor suppressor gene because the extensive DNA variations occurred during the progression of tumor. RAPD assay connected with other techniques was a good tool for the detection of genomic instabilities and direct screening of some new molecular markers related to tumor suppressor genes or oncogenes.

[Effect of berberine on intracellular free CA2+ concentration in cultured brain cells]

Intracellular free calcium concentration ([Ca2+]i) was measured with Ca(2+)-sensitive fluorescent indicator, Fura-2/AM, in cultured brain cells using AR-CM-MIC cation measurement system, and the effects of berberine (Ber) on the changes in [Ca2+]i induced by CaCl2, norepinephrine, KCl and H2O2 were studied. The results indicate that the resting [Ca2+]i was 35 +/- 8 nmol.L-1 in Ca(2+)-free Hank's solution. Ber showed no effect on the resting [Ca2+]i when the extracellular Ca2+ were 0.01-10 mmol.L-1. Ber 1-100 mumol.L-1 dose-dependently inhibited norepinephrine and H2O2 induced [Ca2+]i elevation. Ber at high concentration (10-100 mumol.L-1) inhibited K(+)-induced [Ca2+]i elevation. This suggests that the inhibitory effects of Ber on norepinephrine, K(+)-, and H2O2-induced [Ca2+]i elevation may be one of the mechanisms against cerebral ischemia.

Development of PCR-based markers linked to the fertility restorer gene for the polima cytoplasmic male sterility in rapeseed (Brassica napus L.)

Bulked segregant analysis was used to identify RAPD markers linked to the Rfp of pol cms in rapeseed (Brassica napus L.) from the fertile and sterile DNA bulks. DNA bands amplified from 1040 random 10-mer primers were screened. Two polymorphic bands S1019(720) and S1036(810) were found linked to the Rfp locus at the same side with a map distance of 5.8 cM and 12.3 cM respectively. These polymorphic fragments were cloned and sequenced. Nucleotide sequence information was used to design 20-24-mer oligo nucleotide primers for PCR amplification. The SCAR markers that generated from the long primers showed the same pattern of segregation as the original RAPD markers in the backcross population. The SCAR markers would facilitate selection on the Pol CMS restorer lines in rapeseed.

[Cancer risk assessment among medical X-ray workers in China]

Cancer incidence(1950-1995) among 27,011 medical X-ray workers in comparison with 25,782 non X-ray medical specialists between 1950 and 1980 in China was investigated. The average cumulative dose received by the X-ray workers also reconstructed by retrospective dosimetry methods. Significant cancer risk was seen among medical X-ray workers(RR = 1.2). Significantly elevated risks were found in leukemia, cancer of skin, female breast, lung, liver, bladder and esophagus, the RRs were 2.2, 4.1, 1.3, 1.2, 1.2, 1.8 and 2.7 respectively. The patterns of cancer risk were associated with years since beginning of X-ray work, age and calendar year of initial employment and cumulative dose suggest that the risks of leukemia, skin cancer and female breast cancer, possibly thyroid cancer were related to occupational exposure to X-rays. A significant cancer risk could be induced by prolonged exposure to low dose ionizing radiation when the cumulative dose reached a certain level.

Reproductive hormones and blood pressure during pregnancy

The mechanisms involved in cardiovasular changes during human pregnancy and the complicated aetiology of gestational hypertension are unclear. Reproductive hormones have known effects on the cardiovascular system in the non-pregnant state and in animal systems, but their effects in human pregnancy are uncertain. In this study of pregnant women, the effects of serum concentrations of relaxin, progesterone and oestradiol on arterial blood pressure were studied. Higher serum concentrations of progesterone and relaxin, but not oestradiol, in early pregnancy were related to lower mean systolic blood pressures in the second and third trimesters. No relationship was found between hormonal concentrations and diastolic blood pressures. However, women with a diastolic blood pressure of >90 mmHg in late pregnancy showed statistically significant lower relaxin concentrations in early pregnancy in comparison with women whose diastolic blood pressure was </=90 mmHg. In a multivariate analysis, the mean systolic blood pressure (P: < 0.0001) and serum relaxin (P: < 0.01) in early pregnancy, but not progesterone, were independently related to systolic blood pressure in late pregnancy. The results support previous experimental and clinical studies. The effect of relaxin may be explained by a possible vasodilatatory action seen in animal studies and appears to be moderate.

[Clinical application of 3D reconstruction in maxillofacial fractures]

OBJECTIVE

To study the value of 3D reconstructive technique in midfacial fractures,especially its significance in preoperative diagnosis and operation planning of complicated,multiple fractures in midface.

METHODS

To preoperatively scan and reconstruct 47 fracture patients with spiral CT.

RESULTS

38 cases received operation which confirmed the preoperative diagnosis of 3D CT. The conservationed treatment was applied to other 9 patients.

CONCLUSION

The 3D reconstruction can reveal the complicated fractures in midface as approximate model, and benefit the selection of the most suitable plan before operation.

[Simultaneous determination of magnolol and honokiol in serum and urine by high performance liquid chromatography]

A reversed-phase high performance liquid chromatographic method for simultaneous determination of magnolol and honokiol in serum and urine of rat has been established. Two drugs were determined within 15 minutes by the method on the column with spherisorb C18, by using a mobile phase consisted of methanol-water-glacial acetic acid (70:30:1, V/V) at 1 mL/min, monitored at 294 nm and with a sensitivity of 0.005 AUFS. After 0.25, 1 and 8 hour of administration of the drugs, protein in serum and urine of Wistar rat was precipitated by methanol and magnolol and honokiol in acidified body fluid were determined after being extracted by a mixture of ethyl acetate and ether. Good linear relationship between concentration in serum and urine and peak area in the ranges of 0.05-2 mg/L for magnolol and 0.025-1 mg/L for honokiol was obtained. Good precision and reproducibility were found too. The average recoveries of the two drugs were 95.6% (RSD = 3.85%), 93.8% (RSD = 3.95%) in serum and 96.0% (RSD = 3.83%), 94.9% (RSD = 3.54%) for urine respectively. The lower limit of the method was 0.02 mg/L of magnolol and 0.04 mg/L of honokiol respectively. The results showed that this method is suitable for the determination of magnolol and honokiol in body fluids.

Conditions for electron capture by an ultraintense stationary laser beam

We present in this paper a quantitative study of an effect, in which a low-energy free electron is captured and violently accelerated to GeV final kinetic energy by a stationary extra-high-intensity laser beam (Q0 identical witheE/m(e)omegac greater, similar100). The conditions under which this phenomenon can occur, such as the momentum range, incident angle of the incoming electron, the waist width of the laser beam, etc., have been investigated in detail.

High-intensity laser-induced electron acceleration in vacuum

In this paper, an approximate pulsed-laser-beam solution of Maxwell's equation in vacuum is derived. Then with the numerical simulation method, electron acceleration induced by high-intensity [Q(0)=eE(0)/(m(e)omega c)=3] lasers is discussed in connection with the recent experiment of Malka et al. It is found that the maximum energy gain and the relationship between the final energy and the scattering angle can be well reproduced, but the polarization effect of electron-laser interactions is not very prominent. These results show that the ponderomotive potential model is still applicable, which means that the stimulated Compton scattering is the main fundamental mechanism responsible for the electron acceleration at this laser intensity.

Semirational design of a potent, artificial agonist of fibroblast growth factor receptors

Fibroblast growth factors (FGFs) are being investigated in human clinical trials as treatments for angina, claudication, and stroke. We designed a molecule structurally unrelated to all FGFs, which potently mimicked basic FGF activity, by combining domains that (1) bind FGF receptors (2) bind heparin, and (3) mediate dimerization. A 26-residue peptide identified by phage display specifically bound FGF receptor (FGFR) 1c extracellular domain but had no homology with FGFs. When fused with the c-jun leucine zipper domain, which binds heparin and forms homodimers, the polypeptide specifically reproduced the mitogenic and morphogenic activities of basic FGF with similar potency (EC50 = 240 pM). The polypeptide required interaction with heparin for activity, demonstrating the importance of heparin for FGFR activation even with designed ligands structurally unrelated to FGF. Our results demonstrate the feasibility of engineering potent artificial agonists for the receptor tyrosine kinases, and have important implications for the design of nonpeptidic ligands for FGF receptors. Furthermore, artificial FGFR agonists may be useful alternatives to FGF in the treatment of ischemic vascular disease.

Gene therapy for human hepatocellular carcinoma with cytosine deaminase gene and prodrug flucytosine

AIM

To investigate the antitumor effects of cytosine deaminase (CD) gene in combination with prodrug flucytosine (Flu, 5-fluorocytosine) on human hepatocellular carcinoma.

METHODS

CD gene was transduced into human hepatocellular carcinoma cell line SMMC7721 with retroviral method and the cytotoxicity of Flu on the tumor cells was assayed in vitro with clonogenic techniques. The xenograft tumor model in nude mice was used to study in vivo therapeutic effects of CD gene/Flu system against human hepatocellular carcinoma.

RESULTS

CD gene/Flu system had significant antitumor activities on human hepatocellular carcinoma cells in vitro and in nude mice. The antitumor activities of Flu 500 mg.kg-1 on hepatocellular carcinoma xenografts in nude mice were more potent than those of 5-fluouracil 10 mg.kg-1. CD gene/Flu system possessed bystander killing effects on hepatocellular carcinoma xenografts in nude mice.

CONCLUSION

The experiment demonstrates the potential value of the CD gene/Flu system in the treatment of human hepatocellular carcinoma.

Quercetin decreased heart rate and cardiomyocyte Ca2+ oscillation frequency in rats and prevented cardiac hypertrophy in mice

AIM

To study the effects of quercetin (Que) on myocardial excitation-contraction coupling and cardiac remodeling.

METHODS

Left ventricles and femoral arteries of rats were cannulated for hemodynamic recording. Mouse cardiac hypertrophy was induced by abdominal aortic coarctation (AAC). Cultured myocardial cells in neonatal rats were loaded with Fura 2-AM. The intracellular calcium ([Ca2+]i) and spontaneous [Ca2+]i oscillations ([Ca2+]i-SO) were tested by AR-CM-MIC cation measurement system.

RESULTS

Que 3 or 25 mg.kg-1 i.v. in rats decreased heart rate from (420 +/- 19) to (390 +/- 15) and (314 +/- 18) beat.min-1, respectively, companied with very modest changes in both left ventricular pressures (LVP) and its differential dpLV/dtmax. Que 10, 50, 250 mumol.L-1 concentration-dependently slowed the frequency of [Ca2+]i-SO in cultured myocardial cells from (26 +/- 4) to (25 +/- 3), (18 +/- 4), and (12 +/- 3) time.min-1, respectively, but did not change their resting [Ca2+]i or amplitudes of [Ca2+]i-SO. Similarly, the increases in frequency of [Ca2+]i-SO caused by either isoproterenol (Iso) or ouabain (Oua) were prevented by Que 100 mumol.L-1, while the simultaneous increases in amplitude of [Ca2+]i-SO remained. Besides, [Ca2+]i rises excited by angiotensin II (Ang II) but not high [K+]o were prevented by Que 100 mumol.L-1. Daily administration of Que 120 mg.kg-1 i.g. for 5 d markedly prevented the cardiac hypertrophy in AAC mice, without effects on the ventricular mass to body weight ratio (VM/BW) in sham-operated mice.

CONCLUSION

Que decreased myocardial [Ca2+]i-oscillation frequency and prevented cardiac remodeling, but had no direct effect on cardiac excitation-contraction coupling.

Antianginal effects of ranolazine in various experimental models of angina

The effects of ranolazine (CAS 95635-55-5, KEG-1295), a novel antianginal drug, on the ST-segment changes induced by coronary ligation, epinephrine, and vasopressin were examined following oral or intraduodenal administration. In anesthetized dogs, intraduodenal administration of KEG-1295 (10, 30, or 50 mg/kg) or atenolol (10 mg/kg) significantly attenuated the ST-T wave elevation induced by 2-min coronary ligation imposed during electrical heart pacing (200 beats/min). This antianginal effect of KEG-1295 persisted for 3 h without any changes in hemodynamic parameters, while that of atenolol was accompanied by more or less maintained decreases in diastolic blood pressure, heart rate, and the maximum first derivative of left ventricular pressure. In anesthetized rats, oral administration of KEG-1295 (10, 30, or 50 mg/kg) attenuated the ST-T wave elevation induced by epinephrine (0.3 microgram/kg i.v.) in a dose-dependent manner, although KEG-1295 (10 or 30 mg/kg p.o.) failed to attenuate the ST-segment depression induced by vasopressin (0.2 IU/kg i.v.). These findings suggest that, taken orally, KEG-1295 may exert potent protective effects against angina pectoris, except that caused by vasospasm. Further, KEG-1295 may be categorized as a new type of antianginal agent, without any primary hemodynamic effects.

Effects of dexamethasone on intracellular Ca2+ in its sensitive cells from neonatal mouse hippocampus and cultured cortical neurogliocytes

AIM

To investigate the effects of dexamethasone (Dex) on intracellular free calcium ([Ca2+]i) in the single neuron or neurogliocyte.

METHODS

Neonatal mouse hippocampal cells (NMHC) and cultured cortical neurogliocytes (CCN) were loaded with Fura 2-AM. The [Ca2+]i was measured with AR-CM-MIC-cation measurement system.

RESULTS

Most of freshly isolated NMHC exhibited a rapid and concentration-dependent [Ca2+]i increase after administration of Dex 40-200 mumol.L-1. Only 10% of NMHC showed their [Ca2+]i decreases in total 96 tested cells. Dex-triggered [Ca2+]i rise was prevented by incubating the cells with Mg(2+)-free solution and reduced by adding LaCl3. Suspended NMHC in Ca(2+)-free solution or pretreated cells with mifepristone or tetrodotoxin prevented the initial [Ca2+]i increases caused by Dex 40-90 mumol.L-1, but only diminished the later [Ca2+]i rises by Dex 200 mumol.L-1. About 50% of tested single CCN showed a rapid and concentration-related [Ca2+]i increase due to Dex 90-270 mumol.L-1 exposure. This effect was partially inhibited under extracellular Ca(2+)- or Mg(2+)-free and mifepristone pretreatment conditions.

CONCLUSION

Dex produces the rapid [Ca2+]i changes in both neurons and glia cells. Reactions among most cells include a Mg(2+)-dependent and glucocorticoid receptor-related extracellular Ca2+ influx and a high concentration of Dex-mediated intracellular Ca2+ release.

High-throughput screening for ligand-induced c-fos mRNA expression by branched DNA assay in Chinese hamster ovary cells

We have developed a generally useful screening assay for receptor agonists and antagonists in Chinese Hamster Ovary (CHO) cells. Three key features of the assay make it applicable to a broad range of receptors: (1) the use of CHO cells as host cells to overexpress receptors, (2) measurement of endogenous c-fos mRNA, which responds to a wide spectrum of stimuli, and (3) the use of branched chain DNA assay which is highly sensitive, quantifiable, amenable to high-throughput analysis, and easy to execute. The combination of these features provides a powerful means to screen rapidly for peptide and small molecule ligands for a variety of receptors. CHO cells overexpressing insulin receptor were used as a test system to compare conventional signaling assays with the high-throughput c-fos branched DNA assay.

Thioredoxin fusion/HIV-1 protease coexpression system for production of soluble human IL6 in E. coli cytoplasm

In this paper, thioredoxin (TRX) fusion expression system has been modified to produce soluble human IL6 (hIL6) without TRX moiety in E. coli cytoplasm. A novel TRX gene fusion vector was developed that contained at the 3'-end of TRX gene a short DNA sequences encoding a linker peptide '-GSGSGVSQNYPIVQHHHHHH-', serving not only as a specific HIV-1 protease site but also providing six contiguous histidine (His) residues to foreign proteins. The cDNA for hIL6 was cloned into this vector resulting in plasmid pTRX@HISIL6. The cDNA for the HIV-1 protease has been cloned into another compatible plasmid pHMM2, resulting in plasmid pHMM2-PR. Both plasmids were transformed into E. coli strain GI724, and when induced for expression of both proteins, the correct processing of TRX@HISIL6 was obtained, producing hIL6 with His6-tag at the N terminus named HISIL6. A fraction of HISIL6 was found in soluble form and could be purified to homogeneity by Ni-NTA Superflow and ion-exchange chromatography. The biological activity of purified HISIL6 was measured by MTT method in an IL-6-dependent cell line 7TD1 to be 2.1 x 10(8) unit/mg.