CD3+CD4-CD8- alphabeta-TCR+ T cell as immune regulatory cell

Down-regulation of immune responses by regulatory T cells is one of the major mechanisms involved in the induction of tolerance to self- and alloantigens as demonstrated in a number of models of transplantation and autoimmunity. It is clear that regulatory T cells consist of different subsets. Recently a novel subset of antigen-specific alphabeta-TCR+ CD4-CD8- (double negative, DN) regulatory T cells has been found to be able to inhibit the function of the CD8+ T cells carrying the same T cell receptor specificity and prevent the rejection of skin allografts. Identification of the DN regulatory T cells and their novel mechanism of suppression can help us to understand how donor-specific transplantation tolerance can be achieved and to explain how tolerance to self-antigens can be maintained in the periphery.

Construction, safety, and immunogenicity in nonhuman primates of a chimeric yellow fever-dengue virus tetravalent vaccine

We previously reported construction of a chimeric yellow fever-dengue type 2 virus (YF/DEN2) and determined its safety and protective efficacy in rhesus monkeys (F. Guirakhoo et al., J. Virol. 74:5477-5485, 2000). In this paper, we describe construction of three additional YF/DEN chimeras using premembrane (prM) and envelope (E) genes of wild-type (WT) clinical isolates: DEN1 (strain PUO359, isolated in 1980 in Thailand), DEN3 (strain PaH881/88, isolated in 1988 in Thailand), and DEN4 (strain 1228, isolated in 1978 in Indonesia). These chimeric viruses (YF/DEN1, YF/DEN3, and YF/DEN4) replicated to ~7.5 log(10) PFU/ml in Vero cells, were not neurovirulent in 3- to 4-week-old ICR mice inoculated by the intracerebral route, and were immunogenic in monkeys. All rhesus monkeys inoculated subcutaneously with one dose of these chimeric viruses (as monovalent or tetravalent formulation) developed viremia with magnitudes similar to that of the YF 17D vaccine strain (YF-VAX) but significantly lower than those of their parent WT viruses. Eight of nine monkeys inoculated with monovalent YF/DEN1 -3, or -4 vaccine and six of six monkeys inoculated with tetravalent YF/DEN1-4 vaccine seroconverted after a single dose. When monkeys were boosted with a tetravalent YF/DEN1-4 dose 6 months later, four of nine monkeys in the monovalent YF/DEN groups developed low levels of viremia, whereas no viremia was detected in any animals previously inoculated with either YF/DEN1-4 vaccine or WT DEN virus. An anamnestic response was observed in all monkeys after the second dose. No statistically significant difference in levels of neutralizing antibodies was observed between YF virus-immune and nonimmune monkeys which received the tetravalent YF/DEN1-4 vaccine or between tetravalent YF/DEN1-4-immune and nonimmune monkeys which received the YF-VAX. However, preimmune monkeys developed either no detectable viremia or a level of viremia lower than that in nonimmune controls. This is the first recombinant tetravalent dengue vaccine successfully evaluated in nonhuman primates.

Optical rubbery ormosils sensor for the detection of ammonia

Rubbery ormosil films with immobilized aminofluorescein (AF) were investigated to develop an optochemical sensor for the determination of ammonia in water. The gel precursors with tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DiMeDMOS) were deposited on glass supports, and characterized in terms of response to pH, and to dissolved ammonia at constant pH. After preconditioning the sensing film was stable for 6 months. The detection limit for ammonia in water was 0.2 microg mL(-1) (S/N 2), the response being linearly dependent on concentration in the range of 0.5 to 80 microg mL(-1) ammonia. The response time was less than 5 min. The effects of sodium chloride concentration, temperature, and coexisting metal ions and compounds were investigated.

[Study on the phase II metabolites of phenoprolamine hydrochloride in rat bile by LC/DAD/MSD]

AIM

To study the phase II metabolites of phenoprolamine hydrochloride (DDPH) in rat bile.

METHODS

DDPH was administered by i.p. to bile duct-cannulated rats. Bile samples were collected before drug administration and up to 12 h after drug administration. After being purified and enriched with C-18 SPE columns the rat bile samples were analyzed by LC/DAD/MSD to identify the peaks of phase II metabolites. The fractions of phase II metabolites were prepared by HPLC and treated with beta-glucuronidase, and then were purified and enriched with C-18 SPE columns and analyzed by LC/DAD/MSD. The corresponding reference standards of DDPH phase I metabolites were analyzed by LC/DAD/MSD under identical conditions.

RESULTS

The peaks M7, M8 and M9 in the chromatograms of rat bile samples were the phase II metabolites of DDPH and the enzymatic hydrolysates of M7, M8 and M9 were 1-(2, 6-dimethyl-4-hydroxyphenoxy)-2-(3, 4-methoxyphenylethylamino)-propane (M3), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2-(3, 4-methoxyphenylethylamino)-propane (M2) and 1-(2,6-dimethylphenoxy)-2-(3-methoxy-4-hydroxyphenylethyl-amino)-propane (M1) respectively.

CONCLUSION

beta-1-O-[3,5-dimethyl-4-[-2-methyl-2-(3,4-dimethoxy-phenylethylamino)- ethoxy]-phenyl]-glucuronic acid (M7, glucuronide of M3), beta-1-O-[2, 4-dimethyl-3-[2-methyl-2-(3, 4-dimethoxy-phenylethylamino)-ethoxy]-phenyl]-glucuronic acid (M8, glucuronide of M2) and beta-1-O-[2-methoxy-4-[1-methyl-2-(2, 6-dimethylphenoxy)-ethylamino-ethyl]-phenyl]-glucuronic acid (M9, glucuronide of M1) were the phase II metabolites of DDPH in rat bile.

[Glutamate causes release of nitric oxide from chicken spinal cord in vitro]

Nitric oxide (NO) has been identified to have profound effects on many systems, especially the neural tissues. Many studies suggest that NO mediate the neurotoxicity of glutamate (Glu). In order to determine in vitro whether Glu causes release of NO from chicken spinal cord, different concentrations of Glu (0.1, 0.5, 1.0 mmol.L-1) were added to the primary cultured chicken spinal cord cells, and the quantity of NO- (the metabolism product of NO) in medium was detected. The result shows that Glu can enhance obviously the concentration of NO in primary cell cultures (212% compared with the control). If the spinal cord cells were pretreated with NO synthases (NOS) inhibitor--L-NOARG, the [NO-] was decreased compared with those treated with Glu only, and, on the contrary, the viability of cells was increased. All of the results above indicate that NO may play an important role in the neurotoxicity of Glu on nervous cells. It might be that Glu can instigate the activity of NO synthases, then induce a series of changes within cell and finally lead to the toxic effect on cells.

[Effect of combination of ligustrazine and nitrendipine on hemodynamics in patients with chronic obstructive pulmonary disease]

OBJECTIVE

To find the drugs for lowering the pulmonary vascular resistance in patients of chronic obstructive pulmonary disease (COPD) but would not increase its side-effect.

METHODS

Changes of some hemodynamic parameters in 15 patients of COPD in stable stage treated by nitrendipine and ligustrazine were observed by right heart floating catheterization.

RESULTS

The mean pulmonary arterial pressure reduced by 1.4% immediately after the combined treatment, and reduced by 17.0%, 20.0% and 18.0% in 15 mins, 30 mins and 60 mins after treatment. In the responding time, the pulmonary vascular resistance reduced by 15.2%, 36.2%, 43.0% and 34.6%, the systemic vascular resistance reduced by 7.9%, 19.2%, 17.9% and 20.8%, and the cardiac output increased by 15.8%, 22.6%, 22.2%, and 33.8% respectively. The changes of systemic arterial pressure and heart rate were of no statistical significance.

CONCLUSION

Combination therapy of nitrendipine and ligustrazine could lower the pulmonary arterial pressure and pulmonary vascular resistance effectively and has a selective effect on pulmonary circulation in patients with COPD.

[Study on the phase I metabolites of phenoprolamine hydrochloride in rat bile by LC/DAD/MSD]

AIM

To study the phase I metabolites of phenoprolamine hydrochloride (DDPH) in rat bile.

METHODS

DDPH was administered i.p. to bile duct-cannulated rats. Bile samples were collected before administration and up to 12 h after administration. After being treated with beta-glucuronidase, the bile samples were purified and enriched with C-18 SPE columns, and then were analyzed by LC/DAD/MSD. The samples containing synthesized reference standards of DDPH metabolite 1-(2, 6-dimethylphenoxy)-2-(3-methoxy-4-hydroxyphenylethylamino)-propane (M1), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2-(3, 4-methoxy-phenylethylamino)-propane (M2), 1-(2,6-dimethyl-4-hydroxyphenoxy)-2-(3,4- methoxyphenylethylamino)-propane (M3), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2-(3-hydroxy-4- methoxyphenylethylamino)-propane (M4), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2- (3-hydroxy-4-methoxyphenylethylamino)-propane (M5) and 1-(2,6-dimethyl-4-hydroxyphenoxy)-2-(3-methoxy-4- hydroxyphenylethylamino)-propane (M6) were analyzed by LC/DAD/MSD under identical conditions.

RESULTS

The retention times, UV spectra, molecular weights and production spectra (obtained by collision-induced dissociation) of the apparent ions of peak A, B, C, D, E and F in the total ion chromatogram of DDPH treated rat bile sample were consistent with those of M1, M2, M3, M5, M4 and M6, respectively.

CONCLUSION

M1, M2, M3, M4, M5 and M6 were identified as the phase I metabolites of DDPH in the rat.

The effects of frequency of social interaction and relationship closeness on reward allocation

In this study of how the frequency of interaction affects decisions on reward allocation, 320 Chinese adults were randomly assigned to 8 conditions and instructed to read a scenario describing 2 co-workers completing a task and obtaining a bonus. The 8 conditions differed in the type of relationships, the frequency of past interaction between co-workers, and the possibility of future interaction. Each participant was instructed to act as the allocator and to hypothetically allocate a monetary reward to the co-worker. The results indicated that both past interaction and future interaction between the co-workers significantly influenced the allocation decision. These results also suggested that the frequency of 2 individuals' past interaction can be predictive of the closeness of their relationship.

[Analysis of the metabolite of 7-(4-chlorbenzyl)-7,8,13,13a-tetrahydroberberine in rabbit]

AIM

To explore the biotransformation of compound 7-(4-chlorbenzyl)-7,8,13, 13a-tetrahydroberberine in the rabbit.

METHODS

Analyze the rabbit bile sample with HPLC, LC/MS and LC/NMR.

RESULTS

A metabolite and unchanged 7-(4-chlorbenzyl)-7,8,13,13a-tetrahydroberberine were found in the rabit bile, the metabolite was characterized and its structure was elucidated.

CONCLUSION

Compound 7-(4-chlorbenzyl)-7,8,13,13a-tetrahydroberberine is metabolized by demethylation at 10-OCH3 position.

[Clinical characteristics of Parkinson's disease in natural population]

OBJECTIVE

To study the Clinical characteristics of Parkinson's disease(PD) in natural population.

METHODS

All the patients diagnosed as Parkinsonism from a prevalence study in Beijing in 1997 were collected for investigation. The spectrum of the clinical features of Parkinsonism and the onset, progression and prognosis of PD were analysed, as well as the impact factors to the prognosis were analysed.

RESULTS

109 cases were ascertained as PD from the sample population, in which 64(58.7%) were PD, 11 (10.1%) were Parkinson plus syndrome and 34(31.2%) were symptom Parkinsonism. 30 of the 64 PD cases were male. The median age of PD was 74.5 years. The median age at onset was 68 years old. The median duration was 5 years. The average Hoehn-Yahr staging score was 2.81. The clinical characteristics of PD and other Parkinsonism were compared, as asymmetry of symptoms and signs was an important feature to differentiate PD from other Parkinsonism. 20.3 percent of PD cases were associated with dementia. 16(25%) of the 64 PD cases initiated with essential tremor and developed to PD during 6-49 years after the onset of tremor. Tremor was the dominant initial symptoms of PD(60.9%). Type of initial symptoms was a relatively definite impact factor to the prognosis of PD. Levodopa treatment was likely to delay the duration of PD.

CONCLUSIONS

The clinical features of Parkinsonism in natural population were different as compared with previous studies. A further study on the natural history of PD thoroughly is needed.

Molecular basis for attenuation of neurovirulence of a yellow fever Virus/Japanese encephalitis virus chimera vaccine (ChimeriVax-JE)

A yellow fever virus (YFV)/Japanese encephalitis virus (JEV) chimera in which the structural proteins prM and E of YFV 17D are replaced with those of the JEV SA14-14-2 vaccine strain is under evaluation as a candidate vaccine against Japanese encephalitis. The chimera (YFV/JEV SA14-14-2, or ChimeriVax-JE) is less neurovirulent than is YFV 17D vaccine in mouse and nonhuman primate models (F. Guirakhoo et al., Virology 257:363-372, 1999; T. P. Monath et al., Vaccine 17:1869-1882, 1999). Attenuation depends on the presence of the JEV SA14-14-2 E protein, as shown by the high neurovirulence of an analogous YFV/JEV Nakayama chimera derived from the wild JEV Nakayama strain (T. J. Chambers, A. Nestorowicz, P. W. Mason, and C. M. Rice, J. Virol. 73:3095-3101, 1999). Ten amino acid differences exist between the E proteins of ChimeriVax-JE and the YFV/JEV Nakayama virus, four of which are predicted to be neurovirulence determinants based on various sequence comparisons. To identify residues that are involved in attenuation, a series of intratypic YFV/JEV chimeras containing either single or multiple amino acid substitutions were engineered and tested for mouse neurovirulence. Reversions in at least three distinct clusters were required to restore the neurovirulence typical of the YFV/JEV Nakayama virus. Different combinations of cluster-specific reversions could confer neurovirulence; however, residue 138 of the E protein (E(138)) exhibited a dominant effect. No single amino acid reversion produced a phenotype significantly different from that of the ChimeriVax-JE parent. Together with the known genetic stability of the virus during prolonged cell culture and mouse brain passage, these findings support the candidacy of this experimental vaccine as a novel live-attenuated viral vaccine against Japanese encephalitis.

[Therapeutic mechanism of combination therapy of ligustrazine and nitrendipine in treating patients with chronic obstructive pulmonary disease]

OBJECTIVE

To study the therapeutic mechanism of combination therapy of ligustrazine and nitrendipine in treating patients with chronic obstructive pulmonary disease (COPD).

METHODS

Thirty COPD patients divided in to 3 groups (10 in each) were treated with ligustrazine, nitrendipine and ligustrazine plus nitrendipine respectively, and the changes of hemorrheologic parameters, plasma endothelin (ET-1), thromboxane A2(TXA2) and platelet-P-selectin (CD62P) before and after treatment were observed.

RESULTS

The combination therapy of ligustrazine and nitrendipine could lower the levels of plasma ET-1, TXA2, CD62P and the hemorrheologic parameters.

CONCLUSION

Combination of ligustrazine and nitrendipine showed a therapeutic effect better than that of the two drugs used separately. Its effect in lowering pulmonary circulation resistance is related with the lowering of plasma vaso-contrictive factor and the changing of hemorrheologic properties. The integrated traditional Chinese and western medical therapy is valuable in treating COPD.

A study on the electrophysiological heterogeneity of rabbit ventricular myocytes the effect of ischemia on action potentials and potassium currents

With the whole-cell variant patch-clamp technique, action potentials (AP) and outward potassium currents of rabbit ventricular myocytes isolated from subendocardium and subepicardium were recorded and their changes were observed under normal and ischemia conditions. The results showed that (1) under normal condition, there were differences in the AP figures between ventricular subendocardial and subepicardial myocytes. Action potentials recorded from subepicardial myocytes had shorter action potential duration (APD) and a notch between phases 1 and 2, compared with those of subendocardial myocytes. The resting potential had no significant difference between these two populations of the action myocytes; (2) under ischemia condition, the notch of action potentials of subepicardial myocytes disappeared and the APD was shortened even more, compared with that of subendocardial myocytes; (3) under normal condition, the density of steady-state outward potassium currents of subepicardial myocytes was significantly greater than that of subendocardial myocytes; (4) under ischemia condition, the increase of steady-state outward potassium currents of subepicardial myocytes was greater than that of subendocardial myocytes. Glybenclamide could partly reverse the above changes. It is suggested that the increase of steady-state outward potassium currents during ischemia is mainly due to the opening of I(K-ATP) channels as a result of the deficiency of intracellular ATP caused by ischemia.

[Separation and determination of effective components in silymarin and preparations of silymarin by MECC]

AIM

To develop a micellar electrokinetic capillary chromatographic (MECC) method for the separation and determination of silybin, isosilybin, silydianin and silycristin in Legalon capsules, Yiganling tablets and silymarin.

METHODS

A buffer solution containing 30 mmol.L-1 disodium tetraborate, 50 mmol.L-1 taurodeoxycholic acid sodium salt and 20 mmol.L-1 beta-cyclodextrin (pH 9.2) was found to be the most suitable electrolyte for this separation. The applied voltage was 20 kV and UV detection wavelength was 288 nm. Rutin was used as internal standard.

RESULTS

The average recoveries of 99.9% for silycristin, 98.3% for silydianin, 99.0% for silybin and 98.2% for isosilybin were obtained.

CONCLUSION

The method is sensitive and accurate for the analysis of diasteroisomers of silybin and isosilybin.

[Determination of fatty acids in shark cartilage by GC-MS using microwave-assisted digestion and derivatization]

A rapid microwave-assisted digestion and derivatization method for the determination of fatty acids in shark cartilage by GC-MS was developed. The optimum conditions for digestion and derivatization were studied in detail using orthogonal design. The digestion and derivatization were accomplished in 4 minutes at 600 W microwave power using HCl-methanol (1:4, V/V) as digestion and derivatization solvent, and the extraction of the target analytes could be carried out simultaneously. This method is rapid, solvent-saving, and particularly suitable for the rapid determination of fatty acids in solid samples.

Identification of a previously unknown antigen-specific regulatory T cell and its mechanism of suppression

Despite increasing evidence for the existence of antigen-specific regulatory T cells, the mechanisms underlying suppression remain unclear. In this study we have identified and cloned a novel subset of antigen-specific regulatory T cells and demonstrated that these T cells possess a unique combination of cell surface markers and array of cytokines. The regulatory T cells are able to inhibit the function of T cells carrying the same T-cell receptor specificity and prevent skin allograft rejection in an antigen-specific, dose-dependent manner. The regulatory T cells are able to acquire alloantigen from antigen-presenting cells, present the alloantigen to activated syngeneic CD8+ T cells and then send death signals to CD8+ T cells. These findings provide a novel mechanism of regulatory T-cell-mediated, antigen-specific suppression.

Recombinant chimeric yellow fever-dengue type 2 virus is immunogenic and protective in nonhuman primates

A chimeric yellow fever (YF)-dengue type 2 (dengue-2) virus (ChimeriVax-D2) was constructed using a recombinant cDNA infectious clone of a YF vaccine strain (YF 17D) as a backbone into which we inserted the premembrane (prM) and envelope (E) genes of dengue-2 virus (strain PUO-218 from a case of dengue fever in Bangkok, Thailand). The chimeric virus was recovered from the supernatant of Vero cells transfected with RNA transcripts and amplified once in these cells to yield a titer of 6.3 log(10) PFU/ml. The ChimeriVax-D2 was not neurovirulent for 4-week-old outbred mice inoculated intracerebrally. This virus was evaluated in rhesus monkeys for its safety (induction of viremia) and protective efficacy (induction of anti-dengue-2 neutralizing antibodies and protection against challenge). In one experiment, groups of non-YF-immune monkeys received graded doses of ChimeriVax-D2; a control group received only the vaccine diluents. All monkeys (except the control group) developed a brief viremia and showed no signs of illness. Sixty-two days postimmunization, animals were challenged with 5.0 log(10) focus forming units (FFU) of a wild-type dengue-2 virus. No viremia (<1.7 log(10) FFU/ml) was detected in any vaccinated group, whereas all animals in the placebo control group developed viremia. All vaccinated monkeys developed neutralizing antibodies in a dose-dependent response. In another experiment, viremia and production of neutralizing antibodies were determined in YF-immune monkeys that received either ChimeriVax-D2 or a wild-type dengue-2 virus. Low viremia was detected in ChimeriVax-D2-inoculated monkeys, whereas all dengue-2-immunized animals became viremic. All of these animals were protected against challenge with a wild-type dengue-2 virus, whereas all YF-immune monkeys and nonimmune controls became viremic upon challenge. Genetic stability of ChimeriVax-D2 was assessed by continuous in vitro passage in VeroPM cells. The titer of ChimeriVax-D2, the attenuated phenotype for 4-week-old mice, and the sequence of the inserted prME genes were unchanged after 18 passages in Vero cells. The high replication efficiency, attenuation phenotype in mice and monkeys, immunogenicity and protective efficacy, and genomic stability of ChimeriVax-D2 justify it as a novel vaccine candidate to be evaluated in humans.

Chimeric yellow fever virus 17D-Japanese encephalitis virus vaccine: dose-response effectiveness and extended safety testing in rhesus monkeys

ChimeriVax-JE is a live, attenuated recombinant virus prepared by replacing the genes encoding two structural proteins (prM and E) of yellow fever 17D virus with the corresponding genes of an attenuated strain of Japanese encephalitis virus (JE), SA14-14-2 (T. J. Chambers et al., J. Virol. 73:3095-3101, 1999). Since the prM and E proteins contain antigens conferring protective humoral and cellular immunity, the immune response to vaccination is directed principally at JE. The prM-E genome sequence of the ChimeriVax-JE in diploid fetal rhesus lung cells (FRhL, a substrate acceptable for human vaccines) was identical to that of JE SA14-14-2 vaccine and differed from sequences of virulent wild-type strains (SA14 and Nakayama) at six amino acid residues in the envelope gene (E107, E138, E176, E279, E315, and E439). ChimeriVax-JE was fully attenuated for weaned mice inoculated by the intracerebral (i.c.) route, whereas commercial yellow fever 17D vaccine (YF-Vax) caused lethal encephalitis with a 50% lethal dose of 1.67 log(10) PFU. Groups of four rhesus monkeys were inoculated by the subcutaneous route with 2.0, 3.0, 4.0, and 5. 0 log(10) PFU of ChimeriVax-JE. All 16 monkeys developed low viremias (mean peak viremia, 1.7 to 2.1 log(10) PFU/ml; mean duration, 1.8 to 2.3 days). Neutralizing antibodies appeared between days 6 and 10; by day 30, neutralizing antibody responses were similar across dose groups. Neutralizing antibody titers to the homologous (vaccine) strain were higher than to the heterologous wild-type JE strains. All immunized monkeys and sham-immunized controls were challenged i.c. on day 54 with 5.2 log(10) PFU of wild-type JE. None of the immunized monkeys developed viremia or illness and had mild residual brain lesions, whereas controls developed viremia, clinical encephalitis, and severe histopathologic lesions. Immunized monkeys developed significant (>/=4-fold) increases in serum and cerebrospinal fluid neutralizing antibodies after i.c. challenge. In a standardized test for neurovirulence, ChimeriVax-JE and YF-Vax were compared in groups of 10 monkeys inoculated i.c. and analyzed histopathologically on day 30. Lesion scores in brains and spinal cord were significantly higher for monkeys inoculated with YF-Vax. ChimeriVax-JE meets preclinical safety and efficacy requirements for a human vaccine; it appears safer than yellow fever 17D vaccine but has a similar profile of immunogenicity and protective efficacy.

The role of NO and B-50 in neurotoxicity of excitatory amino acids

To investigate the direct evidence for the role which nitric oxide (NO) plays in the neurotoxicity of excitatory amino acids, we evaluated NO level by Greiss testing solution when glutamate (Glu) and kainate (KA) induced neuronal degeneration in primary cortical cultures. Glutamate-induced neurotoxicity was accompanied by a rise in NO. 5 mM hemoglobin (Hb) led to a decrease of NO content and prevented excitotoxicity induced by 1 mM glutamate. 1 mM L-arginine (L-Arg) reversed the effect of hemoglobin by raising the NO level. No change in NO content was found in KA-induced neurotoxicity, which was not affected by L-Arg, Hb or L-Arg + Hb. It is suggested that NO plays an important role in glutamate-, but not KA-induced neurotoxicity in primary cortical cultures. We also investigated the effects of glutamate on a growth-associated protein, B-50. The B-50 level declined significantly 24 h after exposure to 100 microM glutamate for 30 min and then recovered 2 days later. The effect of glutamate on B-50 was concentration-dependent. This indicates that B-50 might be involved in both glutamate neurotoxicity and the following neuronal repair process.

Characterization of a monoclonal antibody and its single-chain antibody fragment recognizing the nucleoside Triphosphatase/Helicase domain of the hepatitis C virus nonstructural 3 protein

We have produced a murine monoclonal antibody (MAb), ZX10, recognizing the NTPase/helicase domain of the hepatitis C virus (HCV) nonstructural 3 protein (NS3), from which we designed a single-chain variable fragment (ScFv). The ZX10 MAb recognized a discontinuous epitope of the NTPase/helicase domain, of which the linear sequence GEIPFYGKAIPL at residues 1371 to 1382 constitutes one part. cDNAs from variable regions coding for the heavy and light chains were cloned, sequenced, and assembled into the NS3-ScFv, which was inserted into procaryotic and eucaryotic expression vectors. Escherichia coli-expressed NS3-ScFv inhibited the binding of the ZX10 MAb to NS3, confirming a retained specificity. However, the ability to bind the peptide 1371-1382 had been lost. In vitro-translated NS3-ScFv and HCV NS3/NS4A were coprecipitated by antibodies to HCV NS4A, confirming the in vitro activity of the NS3 ScFv. Thus, we have designed a functional NS3 NTPase/helicase domain-specific ScFv which should be evaluated further with respect to disturbing enzymatic functions of the NS3 protein.

[Effect of chronic hypoxia on the calcium and potassium current of myocytes of the right ventricle in guinea pig]

To explore the effect of chronic hypoxia on calcium and potassium currents of the right ventricle myocytes in the guinea pig, the cell membrane capacities, calcium and delayed rectifier potassium current were recorded using the whole-cell patch clamp technique from single right ventricle myocytes in guinea pigs under chronic hypoxia. The result demonstrated that the cell membrane capacities of the hypoxic group were larger than those of the control; between test potential of -20 mV to +20 mV, the calcium current density of the myocytes of the chronic hypoxic group was less than that of the control; the amplitude of IK of the myocytes of the chronic hypoxia group were less than that of the control group between test potential of +20 mV to +60 mV, and the IK density of the hypoxic group was also less than that of the control group between -20 mV to +60 mV. Consequently, it is suggested that chronic hypoxia may cause an increase of the membrane capacity, a decrease of the calcium current density of ventricle myocytes and a delay of the rectifier potassium current amplitude and density. All these observations provide information for the ionic basis of the attenuated contraction of cardiac muscles and prolonged action potential duration of hypoxic guinea pigs.

R-dl-verapamil downmodulates multidrug resistance of KBv200 cells to vincristine and doxorubicin

AIM

To study the attenuation of multidrug resistance (MDR) by R-dl-verapamil (R-Ver) and the acute animal toxicity of R-Ver, and to compare these results of R-Ver with the results of dl-verapamil (Ver).

METHODS

Cytotoxicity was determined by tetrazolium (MTT) assay. Cellular accumulation of doxorubicin (Dox) was measured by fluorescence spectrophotometry. Acute animal toxicity was tested by i.p. drug administration in BALB/c mice.

RESULTS

R-Ver attenuated MDR of KBv200 cells to vincristine (VCR) and Dox. This attenuation ability was dose-related, and was also dependent on drug exposure time. R-Ver 1.25 mumol.L-1 increased the sensitivity of KBv200 cells to VCR (P < 0.01) with a 24-h period of drug exposure. R-Ver downmodulated MDR and increased cellular Dox accumulation of KBv200 cells as effectively as Ver, but possessed lower acute toxicity in BALB/c mice. While LD50 of Ver was 60 (49-73) mg.kg-1, LD50 of R-Ver was 166 (137-202) mg.kg-1.

CONCLUSION

R-Ver downmodulated the MDR to VCR and Dox at 1.25 mumol.L-1, and this effect on VCR can be realized with drug exposure duration of 24 h.

New pregnane glycosides from Sinomarsdenia incisa

Five new pregnane glycosides, sinomarinosides A (1), B (2), C (3), D (4), and E (5), have been isolated from Sinomarsdenia incisa (Asclepiadaceae). The structures of these compounds were elucidated by NMR and mass spectroscopic methods and chemical evidence.

Immunogenicity, genetic stability, and protective efficacy of a recombinant, chimeric yellow fever-Japanese encephalitis virus (ChimeriVax-JE) as a live, attenuated vaccine candidate against Japanese encephalitis

Yellow fever (YF) 17D vaccine virus, having a 60-year history of safe and effective use, is an ideal vector to deliver heterologous genes from other medically important flaviviruses. A chimeric YF/Japanese encephalitis (JE) virus (ChimeriVax-JE virus) was constructed by insertion of the premembrane and envelope (prME) genes of an attenuated human vaccine strain (SA14-14-2) of Japanese encephalitis (JE) virus between core and nonstructural (NS) genes of a YF 17D infectious clone. The virus grew to high titers in cell cultures and was not neurovirulent for 3- to 4-week-old mice at doses </=6 log10 plaque forming units (pfu) inoculated by the intracerebral (IC) route. In contrast, commercial YF 17D vaccine was highly neurovirulent for weanling mice by the same route. Mice inoculated subcutaneously with one dose of >/=10(3) pfu of ChimeriVax-JE virus were solidly protected against intraperitoneal challenge with a virulent JE virus. Genetic stability of the chimera was assessed by sequential passages in cell cultures or in mouse brain. All attenuating residues and the avirulent phenotype were preserved after 18 passages in cell cultures or 6 passages in mouse brains.

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.