[A cis-regulatory enhancer element of the nodal gene is present in its first intron]

The mouse nodal gene is expressed during early embryogenesis and plays an important role during gastrulation and the determination of the left-right body symmetry/axis formation. The embryonic stem (ES) cell line 413-d 3563 contains a single copy of a retrovirus insertion in the first inton of the nodal gene. Using a quantitative RNase protection assay, the level of the nodal gene expression in this cell line was compared to that of the parental CCE cell line. A 2.3 fold down regulation of the nodal transcript in the 3563 ES cell line suggested that the proviral insertion might decrease the nodal mRNA expression by disrupting the potential cis regulatory elements present at the insertion site in the first intron of the nodal gene. Luciferase reporter constructs containing the entire first intron fragment or part of it were tested by a transient transfection assay for their potential transcriptional regulatory activity. A 2.4 kb DNA fragment from the 5' end of the intron was sufficient to increase the expression level of the reporter gene 8 fold, suggesting that an important cis acting enhancer element for the nodal gene expression is localized within the first intron.

[Delineation of the cis-regulatory sequences of the nodal gene]

In mouse embryo development, nodal is expressed in the node during the gastrulation. It is involved in mesoderm formation and left-right axis determination. The expression of the nodal gene has a restricted spatial and temporal specificity. Studies on the function of the nodal first intron in the gene expression regulation have shown that a 220 bp fragment at the 5' end of the first intron has an enhancer activity. Rather unexpectedly, the transient transfection assays in F9 cells indicate that this fragment also displayed a promoter activity when it is cloned upstream of basic luciferase reporter gene only in sense orientation. We present here the nucleotide sequence of this 220 bp fragment, and discuss its possible role in the nodal gene regulation.

Trace analysis of haloperidol and its chiral metabolite in plasma by capillary electrophoresis

Capillary zone electrophoresis was developed for the simultaneous determination of haloperidol (HP) and its chiral metabolites [(+)- and (-)- reduced haloperidol, (+)- and (-)-RHP] in human plasma. The method involved the presence of an internal standard and liquid-liquid extraction from plasma. After concentration, the residue from the organic extract was dissolved in aqueous acid for capillary electrophoretic analysis. The background electrolyte was Tris-phosphate buffer with dimethyl-beta-cyclodextrin and PEG 6000. In spiked plasma the quantitative ranges were 40-400 nM for HP and 50-500 nM for (+)-RHP or (-)-RHP. The intra-day and inter-day relative standard deviations (n = 3) were all < 20% for each substance. The detection limits were found to be 15 ng/ml for HP and 30 ng/ml for both enantiomers of RHP (S/N = 3, injection 20 s). All recoveries were > 70%. We investigated the in vivo metabolism of HP in Chinese schizophrenia patients. The results show that (-)-RHP seems to be the only chiral metabolite from these two HP-dosed patients.

Berberine-induced apoptosis of human leukemia HL-60 cells is associated with down-regulation of nucleophosmin/B23 and telomerase activity

The steady-state level of nucleophosmin/B23 mRNA decreased during berberine-induced (25 microg/ml, 24 to 96 hr) apoptosis of human leukemia HL-60 cells. A decline in telomerase activity was also observed in HL-60 cells treated with berberine. A stable clone of nucleophosmin/B23 overexpressed in HL-60 cells was selected and found to be less responsive to berberine-induced apoptosis. About 35% to 63% of control vector-transfected cells (pCR3) exhibited morphological characteristics of apoptosis, while about 8% to 45% of nucleophosmin/B23-over-expressed cells (pCR3-B23) became apoptotic after incubation with 15 microg/ml berberine for 48 to 96 hr. DNA extracted from pCR3 cells contained more fragmented DNA than pCR3-B23 cells during treatment with 15 microg/ml berberine for 24 to 48 hr. Our results indicate that berberine-induced apoptosis is associated with down-regulation of nucleophosmin/B23 and telomerase activity. We also suggest that nucleophosmin/B23 may play an important role in the control of the cellular response to apoptosis induction.

Trace analysis of ethosuximide in human plasma with a chemically removable derivatizing reagent and high-performance liquid chromatography

A simple and sensitive liquid chromatographic method is described for the determination of ethosuximide in human plasma, as a highly sensitive derivative. Ethosuximide spiked in plasma was extracted with toluene and derivatized with a chemically removable derivatizing reagent, 2-(2-naphthoxy)ethyl 2-[1-(4-benzyl)piperazyl]ethanesulfonate, in a homogeneous system, using magnesium oxide as base catalyst. The resulting derivative was separated on a LiChrospher diol column with 1.2% isopropanol in n-hexane as the mobile phase and using coumarin as the internal standard. Several parameters affecting the extraction/derivatization of ethosuximide from spiked plasma were investigated. The linear range for the determination of ethosuximide in spiked plasma was over 30-700 nmol/ml. For ethosuximide in plasma, the detection limit (signal-to-noise ratio=3; sample size, 10 microl) was about 9 pmol; the relative standard deviation was 6.4% for intra-day assay (n=6) and 9.2% for inter-day assay (n=6) and the relative recovery was found greater than 94%.

Suppression of angiogenesis and tumor growth by the inhibitor K1-5 generated by plasmin-mediated proteolysis

Proteolytic enzymes are involved in generation of a number of endogenous angiogenesis inhibitors. Previously, we reported that angiostatin, a potent angiogenesis inhibitor, is a proteolytic fragment containing the first four kringle modules of plasminogen. In this report, we demonstrate that urokinase-activated plasmin can process plasminogen to release an angiogenesis inhibitor, K1-5 (protease-activated kringles 1-5). K1-5 inhibits endothelial-cell proliferation with a half-maximal concentration of approximately 50 pM. This inhibitory effect is endothelial-cell-specific and appears to be at least approximately 50-fold greater than that of angiostatin. A synergistic efficacy of endothelial inhibition was observed when angiostatin and kringle 5 (K5) were coincubated with capillary endothelial cells. The synergistic effect is comparable to that produced by K1-5 alone. Systemic treatment of mice with K1-5 at a low dose significantly blocked the fibroblast growth factor-induced corneal neovascularization, whereas angiostatin had no effect at the same dose. K1-5 also suppressed angiogenesis in chicken embryos. Systemic administration of K1-5 at a low dose at which angiostatin was ineffective significantly suppressed the growth of a murine T241 fibrosarcoma in mice. The antitumor effect correlates with the reduced neovascularization. These findings suggest that the plasmin-mediated proteolysis may be involved in the negative switch of angiogenesis.

Selective inhibition of rat mesangial cell proliferation by a synthetic peptide derived from the sequence of the C2 region of PKCbeta

RACK (receptor for activated C-kinase) is a protein that binds and translocates protein kinase C (PKC) to the appropriate cellular organelles. The binding of RACK has been mapped to C2 region of PKC. A number of peptides from the C2 region of PKCbeta have been shown to inhibit the translocation and activation of PKCbeta. This investigation was undertaken to study the role of PKCbeta in rat mesangial cell proliferation mediated by a number of mitogens. Exposure of rat mesangial cells to thrombin, endothelin, epidermal growth factor, and phorbol 12,13-dibutyrate resulted in increased [3H]thymidine incorporation. Pretreatment of mesangial cells with Ro 32-0432 (selective PKC inhibitor) inhibited the proliferation mediated by all the above mitogens, suggesting that these mitogens mediated proliferation through PKC. Experiments were performed to further evaluate the involvement of PKCbeta in this process by using the peptide derived from the C-2 region of PKCbeta as a tool. The data suggest that although the peptide (P) alone had no effect on basal- or mitogen-mediated proliferation, the peptide in the presence of a carrier peptide (PC) inhibited proliferation mediated by endothelin. In the same experiment, proliferation mediated by epidermal growth factor, thrombin and phorbol dibutyrate was unaffected, suggesting that in rat mesangial cells, endothelin mediated proliferation through the activation of PKCbeta.

The effect of intra-articular irrigation injection therapy on osteoarthrosis of the temporomandibular joint

OBJECTIVE

To investigate the effect of intra-articular irrigation-injection therapy in treating osteoarthrosis of the temporomandibular joint.

MATERIALS AND METHODS

Thirty-seven patients (the test group) received intra-articular irrigation injection; 26 patients (the control group) received intra-articular injection of steroid. The synovial fluid, aspirated from five subjects of the test group before and after the therapy, was assayed to determine the tumor necrosis factor.

RESULTS

Clinical evaluations were performed 3 months after the therapy. Thirteen subjects in the test group fell into the "excellent" category, 19 into the "good" category, and five into the "no effect" category; in the control group, eight subjects fell into the "excellent" category; nine into the "good" category, and nine into the "no effect" category. The category difference in total effectiveness between the test group and the control group is statistically significant (X2 = 3.9340 P < 0.05). TNF in synovial fluid also showed statistically significant differences before and after treatment (T = 2.8825, P < 0.05).

CONCLUSIONS

Intra-articular irrigation injection is an effective therapy method for treating osteoarthrosis and is superior to intra-articular injection of steroid.

Hemodynamic effects of 8-day DL-028 and octreotide administration in rats with portal hypertension

BACKGROUND

DL-028 (chemical name: 3-[[4-(2-methoxyphenyl)piperazin-1-yl]methyl]-2,3-dihydroimidaz o[1,2-c]quinazolin-5(6H)-one (27b)) is a synthetic alpha1-adrenoceptor antagonist. The present study was undertaken to investigate the hemodynamic effects of chronic DL-028 administration, alone or in combination with octreotide, in rats with portal hypertension.

METHODS

Portal hypertension was induced by partial portal-vein ligation. Portal-hypertensive rats were allocated to one of the four groups: vehicle group (saline, 0.5 ml/12 h), octreotide group (30 microg/kg/12 h), DL-028 group (0.4 mg/kg/12 h), and octreotide (30 mg/kg/l2 h) plus DL-028 (0.4 mg/kg/12 h) group, with eight rats in each group. DL-028 or saline was administered by gavage and octreotide by subcutaneous injection. Drugs were given immediately after ligation and for 8 consecutive days thereafter. Systemic and splanchnic hemodynamic variables were measured thereafter.

RESULTS

Portal-vein-ligated rats showed a typical hyperdynamic state as compared with sham-operated rats. The portal venous pressure, portal tributary blood flow, and cardiac index were significantly reduced by treatment with octreotide, DL-028, or octreotide plus DL-028 in portal-hypertensive rats. Hyperdynamic variables of systemic, renal, hepatocollateral, and portal territory vascular resistances and renal and hepatic arterial blood flow were ameliorated by treatment with octreotide or octreotide plus DL-028 in portal-hypertensive rats. Octreotide plus DL-028 treatment exerted better hemodynamic effects on the cardiac index but worse effects on systemic and hepatocollateral vascular resistance than octreotide treatment alone.

CONCLUSION

Although either DL-028 or octreotide ameliorated portal hypertension and splanchnic hyperemia in portal-hypertensive rats, octreotide treatment exerted more beneficial hemodynamic effects than DL-028 treatment. The combination of octreotide and DL-028 conferred no better hemodynamic benefits than octreotide alone, except on the cardiac index.

Long-term culture of hepatocytes from human adults

A long-term primary human hepatocyte culture retraining liver-specific functions is important and essential for basic research and for the future development of hepatocyte-based applications. We established a normal hepatocyte culture system from excess normal tissues obtained from adult liver cancer patients who received partial liver resection. Hepatocytes were isolated after perfusion and enzymatic disaggregation, and were first maintained in hormonally defined media on a Matrigel matrix, and then transferred to collagen sandwich gel. The hepatocytes formed clusters on the Matrigel matrix and increased in size and numbers with time of culture and eventually grew into spheroids of variable sizes. After being transferred to collagen gel, the cells migrated outward from spheroids to form a monolayer with cuboidal or polygonal cell shapes with granular cytoplasm and continued to proliferate. Cellular functions specific for hepatocytes were analyzed using immunoblot assay for proteins specifically secreted by the liver cells on different days of culture. The cells secreted albumin, transferrin and alpha-fetoprotein consistently for more than 100 days, to a maximum of 150 days. Thus, we have established a long-term culture of hepatocytes from human adults, which will be useful for basic studies of liver physiology such as metabolism and morphogenesis, as well as for other applications in the study of infectious hepatitis, pharmacology, pharmacokinetics, and toxicology.

Haemodynamic effects of 8-day octreotide and prazosin administration in portal hypertensive rats

BACKGROUND

Octreotide and prazosin are both effective portal hypotensive drugs in the control or prevention of variceal bleeding. The present study was undertaken to investigate the haemodynamic effects of octreotide and prazosin, alone or in combination, in portal hypertensive rats.

METHODS

Portal hypertension was induced by partial portal vein ligation. Portal hypertensive rats were allocated into one of the four groups-vehicle group (saline, 0.5 mL 12 h-1), octreotide group (30 micrograms kg-1 12 h-1), prazosin group (0.4 mg kg-1 12 h-1), and octreotide (30 micrograms kg-1 12 h-1) plus prazosin (0.4 mg kg-1 12 h-1) group-with eight rats in each group. Prazosin or saline was administered by gavage, whereas octreotide was administered by subcutaneous injection. The drug was given on the day of ligation and continued for 8 consecutive days. Systemic as well as splanchnic haemodynamic parameters were measured thereafter.

RESULTS

Portal vein-ligated rats exhibited typical hyperdynamic state compared with sham-operated rats. The portal venous pressure, portal tributary blood flow and cardiac index were significantly reduced by treatment of octreotide, prazosin or octreotide plus prazosin in portal hypertensive rats. Hyperdynamic parameters of systemic, renal and portal territory vascular resistances, and renal as well as hepatic arterial blood flow were ameliorated by treatment of octreotide or octreotide plus prazosin in portal hypertensive rats. Overall, octreotide treatment exerted more beneficial haemodynamic effects than prazosin treatment. The combination of octreotide and prazosin exerted better haemodynamic effects in cardiac index but worse effects in systemic as well as portal territory vascular resistance than octreotide treatment alone.

Transforming growth factor-beta-mediated proliferation of renal tubular epithelial cells involves pertussis toxin-sensitive G protein-and protein kinase C-dependent pathways

Exposure of LLCPK-1 cells to transforming growth factor (TGF)-beta(1) resulted in an increase in [3H]thymidine incorporation. This increase depended on the concentration of TGF-beta(1) used with an EC50 value of 0.3-1 pmol/l. Concentrations > 10 pmol/l were inhibitory. Similar effects occurred with TGF-beta(3). Addition of both TGF-beta(1) and TGF-beta(3) together had no additive effect. Pretreatment of cells with 10 mumol/1 genestein exerted no effect on TGF-beta-mediated response, whereas pretreatment with 10 mumol/1 Ro-32-0432 inhibited TGF-beta-mediated [3H]thymidine incorporation. In addition, pretreatment of cells with pertussis toxin attenuated TGF-beta-mediated proliferation of LLCPK-1 cells. These data indicate that in LLCPK-1 cells, TGF-beta(1) and TGF-beta(3) mediate their responses through the same receptor. This pathway involves protein kinase C and pertussis toxin-sensitive G protein.

Preparation of a novel streptokinase mutant with improved stability

The novel mutant streptokinase, SK-K59E, can activate human plasminogen as efficiently as the purified commercially available streptokinase. Several peptide bonds including Lys59-Ser60 in native streptokinase were hydrolyzed in reaction with plasmin and peptides of small molecular masses were generated. The plasminogen activator activity of native streptokinase in reaction with human plasmin declined to 25% of the original activity in a 120-min incubation. On the other hand, the NH2-terminal peptide of SK-K59E remained intact in reaction with plasmin and the activator activity of streptokinase decreased to 75% of the original activity in 120 min. The major degraded peptide fragments of native streptokinase in reaction with plasmin had molecular masses of 36 and 30 kDa. However, two major peptide fragments of 42 and 34 kDa were observed in the reaction of SK-K59E with human plasmin. The 42 kDa peptide fragment, which contained NH2-terminal of streptokinase, could activate human plasminogen as efficiently as the native streptokinase. SK-K59E can induce greater degree of caseinolysis and fibrinolysis than the native streptokinase. In conclusion, the results demonstrate that the prevention of cleavage at Lys59 of streptokinase prolongs the half-life of streptokinase in complex with plasmin and that the NH2-terminal of streptokinase (Ile1-Lys59) plays an important role in maintaining its stability.

Micellar electrokinetic chromatography of scopolamine-related anticholinergics

A simple micellar electrokinetic chromatography (MEKC) method is described for the separation of scopolamine N-oxide hydrobromide (SO), scopolamine hydrobromide (SH), scopolamine N-methylbromide (SM) and scopolamine N-butylbromide (SB), and for the quantitation of SH, SM and SB (using SO as an internal standard). The analysis of these drugs was performed in a phosphate buffer (30 mM; pH 7.00) with sodium dodecyl sulfate (SDS) (30 mM) as an anionic surfactant. Several parameters affecting the separation of the drugs were studied, including the concentrations of the buffer and SDS. The stability of the drugs in the phosphate buffer (pH 7.00) was also examined. Partial application of the method to the determination of scopolamine N-butylbromide in tablets proved to be feasible.

Trace determination of methanol in water-ethanol solution by derivatization and high-performance liquid chromatography

A simple and sensitive high-performance liquid chromatographic method has been established for the determination of methanol in water-ethanol solution. The method is based on the transfer of the methoxide anion, which is formed from methanol under strong alkaline treatment in aqueous solution, by benzalkonium chloride into the dichloromethane organic phase for derivatization with 3-bromomethyl-7-methoxy-1,4-benzoxazin-2-one. The derivative obtained was separated on a LiChrospher diol column with n-hexane-dichloromethane (9:1, v/v) as the mobile phase. Several parameters affecting the partition/derivatization of methanol were investigated. The linear range for the determination of methanol was 2-20 mumol/ml; the detection limit (signal-to-noise ratio = 5; sample size, 10 microliters) of methanol was about 0.10 mumol/ml (R.S.D. = 16%, n = 3). The method has been satisfactorily applied to the assay of methanol in spiked commercial liquors.

Dissolution difference between acidic and neutral media of acetaminophen tablets containing a super disintegrant and a soluble excipient. II

The disintegration and dissolution of acetaminophen tablets containing sucrose and Ac-Di-Sol/Primojel was significantly different between acidic and neutral media. The purpose of this study was to investigate the mechanism of this phenomenon and to propose a way of reducing the dissolution difference between the two media. Tablets of different combinations of active ingredient, sucrose, and Ac-Di-Sol/Primojel were prepared and their dissolution in various media was evaluated. The dissolution differences were found to be largely related to the hydrophobicity of the active ingredient and pH difference of the two media. This difference was even more evident under the condition where acetaminophen, sucrose, and Primojel were combined. The dissolution difference was therefore attributed to the depressed function of Primojel in the acidic medium, the stronger binding of sucrose, the hydrophobicity of the active ingredient and pH difference of the two media. Increasing the concentration of Primojel or incorporating the surfactant in the tablet can thus greatly decrease the dissolution difference between acidic and neutral media.

Plasminogen activation by streptokinase via a unique mechanism

The mechanism of human plasminogen (HPlg) activation by streptokinase (SK)-type activator was investigated with recombinant truncated SK peptides. An enzyme-substrate intermediate of HPlg.SK. HPlg ternary complex was demonstrated by a sandwich-binding experiment. Formation of the ternary complex was saturable, HPlg-specific, and inhibited by 6-aminocaproic acid. Three interaction sites between SK and HPlg were demonstrated. SK-(220-414) bound to HPlg with two binding sites: one to the micro-HPlg region, the catalytic domain of HPlg, and one to the kringle 1-5 region, with Kd values of 1.50 x 10(-7) and 2.44 x 10(-6) M, respectively. SK-(16-251) bound to a single site on the kringle 1-5 region of HPlg with a Kd of 4.09 x 10(-7) M. SK-(220-414) and SK-(16-251) competed for binding on the same or nearby location on the human kringle 1-5 domain. Combination of SK-(220-414) and SK-(16-251), but not either peptide alone, could effectively activate HPlg. In addition, SK-(16-251) dose-dependently enhanced the activation of HPlg by SK-(16-414), while the HPlg activation by SK-(16-414) was inhibited by SK-(220-414). We conclude that the HPlg that binds to the COOH-terminal domains of SK functions as an enzyme to catalyze the conversion of substrate HPlg that binds to the NH2-terminal domain of SK to human plasmin.

Lipocortin 1 co-associates with cytokeratins 8 and 18 in A549 cells via the N-terminal domain

An affinity chromatography strategy was used to search for proteins in A549 cells which interact with the N-terminus of lipocortin 1 (annexin 1). Using the biologically active fragment Lc13-25 as the affinity ligand, two proteins of molecular weight (m.w.) 52 and 48kDa were extracted. Affinity blots of these proteins bound iodinated Lc13-25. Partial tryptic digests of these proteins were analysed by matrix assisted laser desorption mass spectrometry and found to display fragmentation patterns with a strong similarity to those of cytokeratin 8 and 18 respectively. Subsequent blotting with a panel of specific cytokeratin antibodies strongly supported the idea that the two proteins were cytokeratin 8 and cytokeratin 18. Cytokeratin 8 was isolated from A549 cells in intermediate filament (IF) preparations which were also found to contain lipocortin 1 as a potential intermediate filament associated protein (IFAP). This association persisted throughout cycles of IF assembly and disassembly. Dual-labelling immuno-histochemistry in A549 cells showed strong co-localization of lipocortin 1 and cytokeratin 8. The implications of this finding are discussed in the light of the biological activity and possible function of lipocortin 1.

Rejoining and misrejoining of radiation-induced chromatin breaks. III. Hypertonic treatment

It has been shown that treatment in anisotonic medium modifies rejoining of radiation-induced breaks in interphase chromosomes. In previous work, we have demonstrated that formation of exchanges in human lymphocytes has a slow component (half-time of 1-2 h), but a fraction of exchanges are also observed in samples assayed soon after exposure. In this paper we studied the effect of hypertonic treatment on rejoining and misrejoining of radiation-induced breaks using fluorescence in situ hybridization of prematurely condensed chromosomes in human lymphocytes. Isolated lymphocytes were irradiated with 7 Gy gamma rays, fused to mitotic hamster cells and incubated in hypertonic solution (0.5 M NaCl) for the period normally allowed for interphase chromosome condensation to occur. The data from hypertonic treatment experiments indicate the presence of a class of interphase chromosome breaks that rejoin and misrejoin very quickly (half-time of 5-6 min). The fast misrejoining of these lesions is considered to be responsible for the initial level of exchanges which we reported previously. No significant effect of hypertonic treatment on the yield of chromosome aberrations scored at the first postirradiation mitosis was detected.

Upregulation of osteopontin in ischemia-induced renal failure in rats: a role for ET-1?

In this study, the involvement of osteopontin in a rat model of ischemia-induced acute renal failure (ARF) was evaluated. In unilaterally nephrectomized Sprague Dawley rats where the left artery was occluded for 30 min., plasma creatinine levels increased significantly within two hours following reperfusion indicating the onset of renal failure. Northern analysis of kidney cortical RNA from these rats showed a time-dependent increase in osteopontin mRNA expression that was significantly higher than sham-operated rats. Since endothelin-1 (ET-1) is implicated as a mediator of acute renal failure, we evaluated its effects on osteopontin expression in a rat mesangial cell-line. Data from in vitro studies indicated that endothelin-1 (ET-1) caused a modest but reproducible increase in osteopontin mRNA in these cells. While the signal for osteopontin upregulation in the rat model is not known, ET-1, which is known to be increased during ischemia, may contribute at least in part to this process.

Identification of the functional regions required for hepatitis D virus replication and transcription by linker-scanning mutagenesis of viral genome

To define the important cis-elements in hepatitis delta virus (HDV) RNA, the viral genome was mutated by a linker-scanning mutagenesis strategy that maintained the native rod-like structure of HDV RNA. Mutant HDV cDNAs or their corresponding RNA transcripts were transfected into a Huh-7-derived cell line which continuously expressed small hepatitis delta antigen to study the viral replication and transcription. Here we report the following findings. (i) Although most of the mutant RNAs could self-process to generate the 1.7-kb genomic RNA and all their stabilities were similar, positions which surround the genomic ribozyme domain were found to be important for the self-processing of the dimeric RNA. (ii) The replication of viral RNA was greatly diminished in many mutants, suggesting that multiple regions in HDV RNA were required for replication. (iii) In certain mutants, replication of the HDV antigenomic RNA was selectively abolished but that of the genomic RNA was not. Therefore, this was the first report to show that the cis-elements needed for the replication of genomic or antigenomic HDV RNA could be different. (iv) A continuous region (nt 1625 to nt 431), spanning the HDAg mRNA initiation site and containing the in vitro identified RNA promoter, was found to be important for mRNA production in vivo. (v) The HDV RNA replication and transcription was previously proposed to be governed by a single "double-acting promoter." However, two mutants which were deficient in mRNA synthesis still retained active viral RNA replication. It suggested that the HDV replication could initiate from sites other than this single promoter. This study therefore provided an insight into the cis-elements required for HDV RNA replication and transcription and further contributed to our understanding of HDV life cycle.

[Comparative study on the chimeric ability of embryonic stem cell lines HDC and MESPU-13]

While producing transgenic mice by ES cell route, it is important to know whether ES cells used have a strong ability to produce chimeras or not. In this report, two methods were used for studying the chimeric ability of two ES cell lines (HDC and MESPU-13). One method was the blastocyst microinjection, that is, chimeras were produced by injecting 15 ES cells into the cavity of C57BL/6J blastocysts. Another was GPI electrophoresis for examinizing the chimerism of ES cells in internal tisssues and organs of chimeras. The results showed that the ability of producing chimeras of MESPU-13 cells was stronger than that of HDC cells. The reason was discussed in detail.

Susceptibility of three laboratory strains of Aedes albopictus (Diptera: Culicidae) to Japanese encephalitis virus from Taiwan

The susceptibility of 3 laboratory strains of Aedes albopictus (Skuse) (Sanhsia [SH], Yungho [YH], Liyang [LY], and 1 strain of Culex tritaeniorhynchus Giles from northern and central Taiwan were compared for susceptibility to the MQ1-2 strain of Japanese encephalitis (JE) virus. The median infective dose (MID50) by intrathoracic inoculation was 0.23, 0.76, 1.60, and -0.03 log10 WMICLD50 (50% weanling mice intracranial lethal dose) with Ae. albopictus SH, YH, LY, and Cx. tritaeniorhynchus, respectively. After feeding on a sweetened blood-virus mixture, the oral MID50 was 2.03, 4.32, and 4.98 log10 WMICLD50 for SH, YH, and LY, respectively, and 1.02 log10 WMICLD50 for Cx. tritaeniorhynchus. The SH Ae. albopictus strain transmitted virus to normal mice after 14 d. with an average transmission rate of 45%. Based on these results, the SH strain was the most susceptible and important potential vector among 3 Ae. albopictus strains for the sympatric MQ1-2 strain of JE.

Molecular biology of hepatitis D virus: research and potential for application

Superinfection by hepatitis D virus (HDV) leads to acute hepatitis and causes progression to liver cirrhosis in a significant proportion of hepatitis B surface antigen (HBsAg) carriers. Current regimens (interferon) to treat hepatitis D patients has only transient but no lasting effects. New approaches are, therefore, warranted. Recently, several laboratory studies have discovered interesting properties of HDV that may become targets for antiviral chemicals. Viral replication requires the small hepatitis delta antigen (s-HDAg). The s-HDAg is a nuclear phosphoprotein. There is evidence indicating that phosphorylation is important for HDV replication. A second step of replication requires HDV-RNA self-cleavage and self-ligation. Interestingly, one group of antibiotics, the aminoglycosides, exerts strong suppression effects on HDV ribozyme activities. In the following stage of viral assembly, two post-translational modifications, namely isoprenylation of large HDAg and glycosylation of HBsAg are involved. Agents capable of blocking the two modifications should reduce viral production. These four possible targets are reviewed. For prevention, effective vaccines are not yet available. Two novel approaches are discussed. The first demonstrates the immunogenicity of a nucleic acid vaccine in mice. The second approach assembled an empty HDV particle in yeast. Advances on such laboratory investigations may provide new methods for the control of hepatitis D in the future.

Antibodies against dengue virus E protein peptide bind to human plasminogen and inhibit plasmin activity

Both mice and rabbits immunized with dengue virus E protein peptide spanning amino acids 100-119 (D4E) produced antibodies that reacted not only with the D4E peptide itself but also with human plasminogen, as shown by ELISA and Western blot. Sera from dengue virus-hyperimmunized mice and dengue patients also contained antibodies against D4E and plasminogen. Furthermore, such sera all contained plasmin inhibitory activity. Using affinity-purified anti-D4E antibodies and free D4E peptide for competitive inhibition, we demonstrated that the inhibition of plasmin activity was due to anti-D4E antibodies rather than other substances in the sera. Taken together, these results suggest dengue virus E protein amino acids 100-119 are a cross-reactive immunogenic region, and antibodies against this region may interfere with human fibrinolysis.