Tracking the startle response of guppies Poecilia reticulata in three dimensions

A three-dimensional analysis of startle behaviours of guppies Poecilia reticulata, in dyads or alone, from two populations that show distinct differences in shoaling behaviour was performed. During the first few seconds after a startling stimulus, changes in behaviour, which could be critical if an individual is to survive a predatory attack, and the interactions between pairs of P. reticulata were examined. The enhanced social interactions immediately after the stimulus, as a proxy for shoaling behaviour, and their dissipation were quantified. Social (individuals tested in dyads) v. asocial (tested alone) responses to the startling stimulus were also compared. The three-dimensional reconstruction, from a two-camera, high-frame-rate tracking system allowed for the tracking of the individuals' speed and speed recovery and, for P. reticulata in dyads, interindividual distance and orientation. For the dyads from the high-predation population, the closer the individuals were to each other, the more likely they were to be parallel, but no correlation was found for the low-predation P. reticulata. The startle response of P. reticulata comprised the following sequence: freezing, darting and skittering and recovery to pre-stimulus swimming behaviour. Upon repeated encounters with the stimulus, a reduced shoaling and startle response was observed, although the rate of reduction was faster in P. reticulata from the high-predation population than those from the low-predation population. The results are discussed in light of what is known about the anti-predator behaviour of this species.

Expression of estrogen receptors in gastric cancer and their clinical significance

BACKGROUNDS AND OBJECTIVES

The male predominance of gastric cancer suggests that female sex hormones may have a protective effect against gastric cancer. We evaluated the expression of estrogen receptors in gastric cancer tissue and cells and the clinical significance of ER-β expression in gastric cancer.

METHOD

ER-α, ER-β proteins extracted from normal stomach, gastric cancer tissues, and cultured gastric cancer cells (KATO-III, mkn28, mkn45, and mkn74) were assessed by Western blot analysis. The clinical significance of ER-β was explored using tissue microarray methods and immunohistochemical staining of specimens from 148 gastric cancers.

RESULTS

Both ER-α and β protein expression were noted in normal and gastric cancer tissues. However, in cultured gastric cells, only ER-β was noted in mkn28 and mkn74. Of 148 gastric cancers, 67 (45.3%) were ER-β positive. The ER-β positive group was associated with lower tumor stage, Lauren's intestinal type, negative perineural invasion, and free of recurrence. The ER-β positive group had a better 3-year survival compared with the negative group in survival analysis.

CONCLUSION

Our results suggest that the presence of ER-β in gastric cancer could have a protective effect against invasiveness of gastric cancer. Further studies are needed to clarify the role of ER-β in gastric cancers.

Laparoscopic treatment of a huge cystic lymphangioma: partial aspiration technique with a spinal needle

A cystic lymphangioma is a rare intra-abdominal lesion. Treatment is a complete excision of the cyst because of complications and a rare chance of malignancy. In this paper we report on 2 patients with a huge cystic lymphangioma who were treated by laparoscopic surgery successfully. Each of the cysts were 13 and 11 cm in diameter, were diagnosed by ultrasonography and computed tomography scan. After partial aspiration of the cysts, using a spinal needle, we were prone to grasp the cysts without spillage. Traction and dissection were easy without spillage or injury of the mesenteric vessels. The laparoscopic approach can be successfully and safely performed by an experienced surgeon in keeping with oncologic principles.

Prognostic factors for advanced gastric cancer: stage-stratified analysis of patients who underwent curative resection

PURPOSE

Advanced gastric cancer patients have a poorer prognosis as compared to the patients with early gastric cancer. This study was conducted to define the prognostic factors for advanced gastric cancer.

MATERIALS AND METHODS

606 patients with advanced gastric cancer who underwent curative gastric resection at our hospital were retrospectively examined. The patients were divided into two groups: group 1 was comprised of patients with a survival time <5 years, and group 2 patients had a survival time >or=5 years. We compared clinicopathological characteristics of the two groups by performing univariate and multivariate analysis. We also investigated the prognostic factors according to the stage.

RESULTS

On univariate analysis, 7 factors (age, tumor size, Borrmann type, resection type, distal resection margin, depth of invasion and lymph node status) were found to be different, and multivariate analysis revealed that patient age, depth of invasion and lymph node metastasis were the only significantly differences between the two groups. On the other hand, age and the Borrmann type for stage I b patients, age and the number of retrieved lymph nodes for stage II patients, tumor size for stage III patients, and the type of resection for stage IV patients were found to be the independent prognostic factors.

CONCLUSION

The age of patients had prognostic value in the early stages of advanced gastric cancers such as stage I b or II. The number greater than 20 retrieved lymph nodes affected the survival, particularly for the patients with stage II disease, and the tumor size was a significant prognostic factor for patients with stage III disease. Therefore, physicians are advised to pay special attention to lymph node dissection for those patients with stage II or III disease.

A double-blind, randomised- placebo, controlled, parallel group, multicentre, flexible-dose escalation study to assess the efficacy and safety of sildenafil administered as required to male outpatients with erectile dysfunction in Korea

The efficacy and safety of sildenafil was evaluated in a randomiSed, double-blind, placebo-controlled, flexible-dose study in Korean men aged 28-78 y with erectile dysfunction (ED) of broad-spectrum aetiology and more than 6 months duration. A total of 133 patients were randomised at six centres in Korea to receive either sildenafil (50 mg initially, increased if necessary to l00 mg or decreased to 25 mg depending on efficacy and tolerance) (n=66) or matching placebo (n=67) taken on an 'as needed' basis l h prior to anticipated sexual activity for a period of 8 weeks. At the end of this time, the primary efficacy variables relating to the achievement and maintenance of erections sufficient for sexual intercourse, and the secondary efficacy variables, which included: (1) the five separate domains of sexual functioning of the International Index of Erectile Function (IIEF) scale, (2) the percentage of successful intercourse attempts, and (3) a global assessment of erections, were all statistically significantly improved by sildenafil in comparison with placebo (P&<0.0001). Treatment-related adverse events occurred in 56.1% of patients receiving sildenafil and 20.9% receiving placebo. The most common adverse events with sildenafil were vasodilatation (flushing), headache and abnormalities in colour vision (31.8, 22.7 and 6.1% of patients, respectively), and most were mild in nature. The efficacy and safety of sildenafil in this population of Korean men appears similar to that reported in other studies in western populations.

Emergence of YMDD motif mutant of hepatitis B virus during short-term lamivudine therapy in South Korea

BACKGROUND/AIMS

The emergence of a YMDD mutant resistant to lamivudine therapy has been reported in patients with hepatitis B treated with long-term lamivudine therapy. However, it is not well known whether the YMDD mutant could be detected early in lamivudine therapy in hepatitis B virus (HBV) endemic areas. The aim of this study was to investigate the emergence of the YMDD mutant during short-term lamivudine therapy in South Korea.

METHODS

We prospectively investigated the emergence of the YMDD mutant by the nested PCR assay using restriction fragment length polymorphism in 28 patients with chronic hepatitis B who were treated with 100 mg of lamivudine daily for 12 weeks.

RESULTS

The YMDD mutant was detected in 17 (60.7%) out of 28 patients at week 12, and the only type of mutation found was the YIDD mutation. When we carried out the nested PCR serially in five patients, YIDD mutants were detected as early as 2 weeks by the nested PCR assay. The nested PCR results were in concordance with DNA sequencing in one patient's serial samples.

CONCLUSIONS

YMDD mutants in HBV were detected within a few weeks during lamivudine therapy in South Korea, which suggests that the YMDD mutant may exist even before lamivudine therapy in HBV endemic areas.

Expression of cyclooxygenase-2 (COX-2) in hepatocellular carcinoma and growth inhibition of hepatoma cell lines by a COX-2 inhibitor, NS-398

Cyclooxygenase-2 (COX-2) has been suggested to be associated with carcinogenesis. In hepatocellular carcinoma (HCC), the expression pattern of COX-2 protein has been well correlated with the differentiation grade, suggesting that abnormal COX-2 expression plays an important role in hepatocarcinogenesis. We investigated the expression pattern and clinical significance of COX-2 in HCC tissues. In addition, we evaluated the efficacy of a selective COX-2 inhibitor, NS-398, in three hepatoma cell lines. Thirty-six HCC tissues, 15 hepatoma cell lines, 1 colorectal cell line (HT-29), and 1 fibroblast cell line (SV80) were included in the study. We evaluated serological tests and histological and radiological evaluations of HCC tissues. Immunohistochemical staining for COX-2 was performed on 36 HCC tissues and 17 cancer cell lines. A cell viability assay for growth inhibition of NS-398 in five cell lines was performed. Immunohistochemically, all six well-differentiated HCCs were positive, whereas 83% (10 of 12) of the poorly differentiated HCCs were negative. There was no significant relationship between the intensity of COX-2 expression and the level of alpha-fetoprotein, tumor size, presence of portal vein thrombosis, tumor capsule and metastasis, Tumor-Node-Metastasis staging, and growth types (P > 0.05). According to the cell viability assay, NS-398 suppressed the growth of all cell lines, independent of the degree of COX-2 expression. The inhibitory effect on each cell line was identified in 10 microM NS-398 and was significantly strong in 100 microM NS-398. All cell lines exhibited apoptosis, which was identified by 4'-6-diamidino-2-phenylindole staining. In conclusion, COX-2 may be a determinant of the differentiation grade of HCC, and the inhibition of COX-2 can induce growth suppression of hepatoma cell lines via induction of apoptosis.

Activated ras oncogene collaborates with HBx gene of hepatitis B virus to transform cells by suppressing HBx-mediated apoptosis

The hepatitis B virus HBx protein is a promiscuous transactivator implicated in the development of hepatocellular carcinoma. The ectopic expression of HBx fails to transform both primary and immortalized rodent cells, but rather induces apoptosis. Furthermore, most transgenic mice harboring HBx do not develop liver tumors. Thus, it remains unclear whether and how HBx contributes to oncogenesis. Here, we show that HBx collaborates with activated H-ras to transform immortalized rodent cells. Indeed, REF52 cells transfected by both HBx and activated H-ras were morphologically transformed and were able to grow in soft agar. Remarkably, nude mice injected with REF52 cells transfected by both HBx and activated H-ras developed tumors, whereas the mice injected with REF52 cells transfected by either gene alone did not. Thus, we concluded that HBx could contribute to neoplastic transformation of cells in collaboration with other oncogenes, such as H-ras, that renders cells to overcome the HBx-mediated apoptosis. Further, we found that HBx mediated apoptosis was suppressed by activated H-ras through activation of the phosphatidylinositol-3 kinase and Akt pathway. Data presented here firmly established the oncogenic potential of HBx during multistage carcinogenesis. Oncogene (2001) 20, 16 - 23.

Influence of menopause on high density lipoprotein-cholesterol and lipids

It has been generally accepted that high density lipoprotein cholesterol (HDL-C) level decreases with menopause in women. However, recent reports show different results. There is very little data concerning perimenopausal women. To verify these findings, lipids and lipoprotein(a) [Lp(a)] levels were compared among pre-, peri- and postmenopausal women of similar mean ages. Postmenopausal women had higher HDL-C levels than premenopausal women (p<0.001) and there was no difference between peri- and postmenopausal women. LDL-C level in perimenopausal women was lower than in postmenopausal women (p<0.001) and higher than in premenopausal women with borderline significance (p=.051). Total cholesterol levels showed stepwise elevation from premenopause to postmenopause. Perimenopausal women had lower Lp(a) levels than postmenopausal women (p<0.0005) and similar levels to premenopausal women. Lp(a) levels between 0.1 to 10.0 mg/dL were the most prevalent in pre- and perimenopausal women, and those between 10.1 to 20.0 mg/dL in postmenopausal women. In conclusion, menopause itself is associated with the elevation of HDL-C level, and the postmenopausal increase of coronary artery disease is not related to postmenopausal change of HDL-C level. Perimenopausal status, although transient, may favor Lp(a) and lipid profiles for delaying atherosclerosis.

Evidence that the 5'-end cap structure is essential for encapsidation of hepatitis B virus pregenomic RNA

Hepatitis B virus (HBV) replicates by reverse transcription of an RNA intermediate, the pregenomic RNA. The first step of HBV genome replication is the encapsidation of the pregenomic RNA encoding the encapsidation signal, termed epsilon, into the core particles, which is preceded by recognition and binding of HBV DNA polymerase to epsilon. The pregenomic RNA contains two identical epsilon elements due to its terminal redundancy: one near the 5' end and another near the 3' end. Despite the fact that both epsilon elements have an identical sequence, only the 5' epsilon, but not the 3' epsilon, is functional for encapsidation. To understand the molecular nature of this position effect, we made a series of lacZ RNA expression plasmids which contain the epsilon element at various positions from the 5' end of the transcripts. Following transfection, the lacZ RNAs in cytoplasmic core particles were measured by RNase protection assay for encapsidation. The results indicated that the lacZ RNAs with epsilon positioned up to 65 nucleotides from the 5' end were encapsidated, whereas the lacZ RNAs with epsilon positioned further downstream were not. Interestingly, the cap-free lacZ RNA transcribed by T7 RNA polymerase was not encapsidated, implying that the 5' cap structure is required for encapsidation of the pregenomic RNA. We hypothesized that HBV DNA polymerase must somehow recognize the cap structure and/or its associated factors, as well as the 5' epsilon, for encapsidation to occur.

Real-time imaging of fluorescent flagellar filaments

Bacteria swim by rotating flagellar filaments that are several micrometers long, but only about 20 nm in diameter. The filaments can exist in different polymorphic forms, having distinct values of curvature and twist. Rotation rates are on the order of 100 Hz. In the past, the motion of individual filaments has been visualized by dark-field or differential-interference-contrast microscopy, methods hampered by intense scattering from the cell body or shallow depth of field, respectively. We have found a simple procedure for fluorescently labeling cells and filaments that allows recording their motion in real time with an inexpensive video camera and an ordinary fluorescence microscope with mercury-arc or strobed laser illumination. We report our initial findings with cells of Escherichia coli. Tumbles (events that enable swimming cells to alter course) are remarkably varied. Not every filament on a cell needs to change its direction of rotation: different filaments can change directions at different times, and a tumble can result from the change in direction of only one. Polymorphic transformations tend to occur in the sequence normal, semicoiled, curly 1, with changes in the direction of movement of the cell body correlated with transformations to the semicoiled form.

Torque-generating units of the flagellar motor of Escherichia coli have a high duty ratio

Rotation of the bacterial flagellar motor is driven by an ensemble of torque-generating units containing the proteins MotA and MotB. Here, by inducing expression of MotA in motA- cells under conditions of low viscous load, we show that the limiting speed of the motor is independent of the number of units: at vanishing load, one unit turns the motor as rapidly as many. This result indicates that each unit may remain attached to the rotor for most of its mechanochemical cycle, that is, that it has a high duty ratio. Thus, torque generators behave more like kinesin, the protein that moves vesicles along microtubules, than myosin, the protein that powers muscle. However, their translation rates, stepping frequencies and power outputs are much higher, being greater than 30 microm s(-1), 12 kHz and 1.5 x 10(5) pN nm s(-1), respectively.

Flagellar determinants of bacterial sensitivity to chi-phage

Bacteriophage chi is known to infect motile strains of enteric bacteria by adsorbing randomly along the length of a flagellar filament and then injecting its DNA into the bacterial cell at the filament base. Here, we provide evidence for a "nut and bolt" model for translocation of phage along the filament: the tail fiber of chi fits the grooves formed by helical rows of flagellin monomers, and active flagellar rotation forces the phage to follow the grooves as a nut follows the threads of a bolt.

Monitoring antibody titers to recombinant Core-NS3 fusion polypeptide is useful for evaluating hepatitis C virus infection and responses to interferon-alpha therapy

To evaluate the clinical feasibility of the antibody titer against a chimeric polypeptide (named Core 518), in which a domain of Core and NS3 of hepatitis C virus (HCV) was fused, ELISA was performed in a total of 76 serum samples. Each serum was serially diluted using two-fold dilution method with distilled water into 10 concentrations. They were all positive for second generation anti-HCV assay (HCV EIA II; Abbott Laboratories). Genotyping RT-PCR, quantitative competitive RT-PCR, and RIBA (Lucky Confirm; LG Biotech) were also assayed. Anti-Core 518 antibody was detected in x 12800 or higher dilutions of sera from 35 of 43 chronic hepatitis C (81.4%) and nine of 16 hepatocellular carcinoma sera (56.3%), one of four cirrhosis (25%), 0 of four acute hepatitis C, and one of nine healthy isolated anti-HCV-positive subjects (p=0.0000). The anti-Core 518 antibody titers were well correlated with the presence of HCV RNA in serum (p=0.002). The anti-Core 518 antibody titers decreased significantly in nine of ten responders to IFN-alpha treatment. Monitoring anti-Core 518 titers may be helpful not only for differentiating the status of HCV infection among patients with various type C viral liver diseases, but also for predicting responses to IFN-alpha treatment.

A novel parvovirus isolated from Manchurian chipmunks

A novel parvovirus was identified in Manchurian chipmunks inhabiting Korea. Hepatitis B surface antigen (HBsAg) was detected in sera from 4 animals among 62 apparently healthy chipmunks. Electron microscopic examination of the HBsAg-positive sera revealed virus-like spherical particles 20-22 nm in diameter. Extraction of nucleic acid under annealing conditions from the serum samples containing virus-like particles yielded a single species of DNA molecule with the electrophoretic mobility of 5.6-kb double-stranded DNA. Four overlapping clones that encompassed almost the full-length viral genome, except both ends, were obtained. By sequencing these clones, we determined the sequence of 5097 nucleotides of the viral DNA. Two open reading frames were identified, with the left side open reading frame encoding a putative nonstructural protein and the right side open reading frame encoding a putative capsid protein. The nucleotide and amino acid sequences showed significant homology to parvovirus B19 and simian parvovirus, but showed little homology to other mammalian autonomous parvoviruses or adeno-associated viruses. These observations indicate that the virus isolated from Manchurian chipmunks is a novel parvovirus and may be a potentially useful animal model of human B19 infection as a new member of the Erythrovirus genus of the Parvoviridae.

Increased expression of membrane-type matrix metalloproteinase and preferential localization of matrix metalloproteinase-2 to the neointima of balloon-injured rat carotid arteries

BACKGROUND

Remodeling of the injured vascular wall is dependent on the action of several extracellular proteases. Previous studies have shown that expression of matrix metalloproteinases (MMP-2 and MMP-9) is upregulated after vascular injury and that MMP-2 is required for the migration of cultured vascular smooth muscle cells across complex extracellular matrix barriers. The present study examined changes in the expression of membrane-type metalloproteinase (MT-MMP-1), a putative regulator of MMP-2, in the tissue localization of MMP-2, and in the expression of activated and latent forms of MMP-2 and the tissue inhibitor of metalloproteinases, TIMP-2, in rat carotid arteries subjected to balloon catheter injury.

METHODS AND RESULTS

MT-MMP-1 mRNA levels increased sixfold after 3 days of injury, coinciding with an increase in MMP-2 activation assessed by gelatin zymography. Western blotting and gelatin zymography showed an increase in MMP-2 protein levels beginning 5 to 7 days after injury; immunocytochemistry and Western blotting showed that the increase occurred preferentially in the developing neointima.

CONCLUSIONS

These results show that increased expression of MT-MMP-1 and activation of MMP-2 occurs early after injury to the rat carotid artery and that at later times MMP-2 is preferentially localized to the developing neointima.

Effect of a novel saponin adjuvant derived from Quillaja saponaria on the immune response to recombinant hepatitis B surface antigen

Adjuvant activity of saponins extracted from the South American tree Quillaja saponaria has been demonstrated with many antigens. Recently, four saponin fractions (designated as QS-7, QS-17, QS-18, and QS-21) with adjuvant activity were purified by reverse phase chromatography. In particular, efficacy of the less toxic QS-21 fraction has been demonstrated with several recombinant viral antigens including HIV gp120. Here, we report a novel saponin fraction (designated as QS-L1) derived from Quillaja saponaria. Unlike previously identified saponins, QS-L1 had a different chemical structure and showed adjuvant activity only when administered in the presence of alum-precipitated antigen. Interestingly, the QS-L1 greatly increased not only a humoral immune response but also cellular immune response to recombinant hepatitis B virus surface antigen (HBsAg). Furthermore, QS-L1 showed lower toxicity in vivo and in vitro than the previously identified saponin fraction, QS-21. Finally, we examined the chemical structure of the QS-L1 using mass spectroscopic analysis, carbohydrate composition analysis and NMR spectroscopic analysis. Thus, our results indicated that this novel QS-L1 saponin fraction had several desirable properties required for an effective adjuvant.

Presentation of the hydrophilic domains of hepatitis C viral E2 envelope glycoprotein on hepatitis B surface antigen particles

Subviral particles of hepatitis B virus have been used to present foreign epitopes. We attempted to present the hydrophilic domains of E2 envelope protein of hepatitis C virus (HCV) as a fusion protein with hepatitis B virus surface antigen (HBsAg). The five hydrophilic domains of HCV E2 antigen were inserted into HBsAg such that the inserted hydrophilic domains were presented on the outer surface of HBV subviral particles. In addition, a fusion encoding the hypervariable region (HVR) of E2 antigen was also made. Cell lysate and culture medium were analyzed for the synthesis and secretion of the fusion proteins by immunoprecipitation with polyclonal anti-HBsAg antibody using recombinant vaccinia virus system. The results showed that the fusion proteins containing these six E2 domains were made in the cell, but only two out of six fusion proteins were secreted into culture medium. Further, cesium chloride density gradient analysis and electron microscopy revealed that these fusions were secreted into culture media as particles. It will be of interest to test immunogenicity of the HBsAg fusion particles containing the HCV E2 domains in animal model.

Effect of hormone replacement therapy on lipoprotein(a) and lipid levels in postmenopausal women. Influence of various progestogens and duration of therapy

BACKGROUND

Estrogen replacement therapy in postmenopausal women reduces the risk of coronary artery disease. One of the possible mechanisms of this effect is the modification of lipid profiles. However, there is controversy concerning the effects on lipoprotein(a) [Lp (a)] and lipid levels of progestogens administered with estrogen.

METHODS

Five hundred fifty-one postmenopausal women were divided into 5 groups: group 1, 0.625 mg of conjugated equine estrogen (CEE) (n = 140); group 2, 0.625 mg of CEE plus 5 mg of medroxyprogesterone acetate (MPA) (n = 97); group 3, 0.625 mg of CEE plus 10 mg of MPA (n = 109); group 4, 2 mg of estradiol valerate plus 0.5 mg of norgestrel (n = 134); and group 5, control (n = 71). The Lp(a) and lipid levels were measured before and 2, 6, and 12 months after hormone replacement therapy.

RESULTS

Estrogen replacement therapy for 12 months lowered the Lp(a) level by 37.1%. The addition of progestogen attenuated the Lp(a)-lowering effect of estrogen. The high-density lipoprotein cholesterol (HDL-C) level was markedly increased in group 1 (16.5%), was moderately increased in groups 2 (10.8%) and 3 (11.3%), and was not changed in group 4. The low-density lipoprotein cholesterol level was decreased by 10.9% to 17.6% in all the treatment groups. Estrogen replacement therapy for 2, 6, and 12 months raised the HDL-C level by 7.2%, 17.4%, and 17.8%, respectively. In the group with combined estradiol plus norgestrel therapy, the HDL-C level was decreased after 2 months and was not changed after 6 and 12 months. The groups that received CEE plus MPA showed intermediate effects between the group that received CEE only and the group that received estradiol plus norgestrel.

CONCLUSIONS

Combined estrogen and progestogen therapy may have effects on the heart different from those of estrogen therapy alone because of adverse impact of progestogens on Lp(a) and HDL-C levels. The effects of progesterones were dependent on the androgenic potency of progestogen and the duration of therapy.

Changes in Lp(a) lipoprotein and lipid levels after cessation of female sex hormone production and estrogen replacement therapy

OBJECTIVE

To investigate the serial changes in Lp(a) lipoprotein levels with the loss of female sex hormones by surgical menopause and with estrogen replacement therapy in the same woman.

PATIENTS AND METHODS

Forty-four premenopausal women who underwent a transabdominal hysterectomy (TAH) because of benign gynecological disorders were divided into two groups: women who underwent a TAH and unilateral salpingo-oophorectomy (n=31) and women who underwent a TAH and bilateral salpingo-oophorectomy (n=13). In the group of women who underwent a TAH and bilateral salpingo-oophorectomy, 0.625 mg of conjugated equine estrogen was given daily 2 months after the operation. The levels of Lp(a) lipoprotein and lipids were measured before and at 2 and 4 months after the operation.

RESULTS

In the group of women who underwent a TAH and bilateral salpingo-oophorectomy, the mean (+/-SD) concentration of Lp(a) lipoprotein was increased by 24.5% from 0.48+/-0.47 mmol/L (18.4+/-18.3 mg/dL) to 0.59+/-0.54 mmol/L (22.9+/-21.0 mg/dL) after 2 months (P<.05), and it was reduced by 30.6% to 0.41+/-0.51 mmol/L (15.9+/-20.1 mg/dL)(P<.005) with therapy with conjugated equine estrogen (Premarin). The Lp(a) lipoprotein levels were not changed in the group of women who underwent a TAH and unilateral salpingo-oophorectomy. In the group of women who underwent a TAH and bilateral salpingo-oophorectomy, the high density lipoprotein cholesterol level showed a trend of increase after 2 months from 1.45+/-0.48 mmol/L (56.1+/-18.5 mg/dL) to 1.58+/-0.309 mmol/L (61.2+/-15.1 mg/dL) without statistical significance, and it revealed a significant elevation to 1.76+/-0.43 mmol/L (68.2+/-16.8 mg/dL) with therapy with conjugated equine estrogen (Premarin) compared with that of the basal level (P<.05).

CONCLUSIONS

tHE Lp(a) lipoprotein levels appear to be closely associated with female sex hormones. This association might play a pivotal role in postmenopausal increases of atherosclerotic diseases and cardioprotective effect of estrogen in postmenopausal women.

Hepatitis delta virus mutant: effect on RNA editing

During the replication cycle of hepatitis delta virus (HDV), RNA editing occurs at position 1012 on the 1679-nucleotide RNA genome. This changes an A to G in the amber termination codon, UAG, of the small form of the delta antigen (delta Ag). The resultant UGG codon, tryptophan, allows the translation of a larger form of the delta Ag with a 19-amino-acid C-terminal extension. Using HDV cDNA-transfected cells, we examined the editing potential of HDV RNA mutated from G to A at 1011 on the antigenome, adjacent to normal editing site at 1012. Four procedures were used to study not only the editing of the A at 1012, but also that of the new A at 1011: (i) nucleotide sequencing, (ii) a PCR-based RNA-editing assay, (iii) immunoblot assays, and (iv) immunofluorescence. Five findings are reported. (i) Even after the mutation at 1011, editing still occurred at 1012. (ii) Site 1011 itself now acted as a novel RNA-editing site. (iii) Sites 1011 and 1012 were edited independently. (iv) At later times, both sites became edited, thereby allowing the synthesis of the large form of the delta Ag (delta Ag-L). (v) Via immunofluorescence, such double editing became apparent as a stochastic event, in that groups of cells arose in which the changes had taken place. Evaluation of these findings and of those from previous studies of the stability of the HDV genomic sequence (H.J. Netter et al., J. Virol. 69:1687-1692, 1995) supports both the recent reevaluation of HDV RNA editing as occurring on antigenomic RNA (Casey and Gerin, personal communication) and the interpretation that editing occurs via the RNA-modifying enzyme known as DRADA.

Association of hepatitis C virus particles with immunoglobulin: a mechanism for persistent infection

The physical properties of hepatitis C virus (HCV) particles were determined by ultracentrifugation on 20-60% isopycnic sucrose density gradients. We report that (i) two populations of HCV particles were found in the sera of patients with chronic HCV infection [at high density (1.186-1.213 g/ml) and at low density (1.099-1.127 g/ml)], (ii) virus particles with high density values were associated with immunoglobulin, and (iii) virus particles with low density values accumulated base changes within a hypervariable region (HVR) of the E2 envelope domain of the RNA genome. The results indicate that base changes within the HVR of E2 lead to the accumulation of immunoglobulin-free virus particles. Therefore, these findings imply that persistent HCV infection is established as a consequence of sequence variation in the E2 envelope domain.

Predictive factors for beneficial response to interferon-alfa therapy in chronic hepatitis C

OBJECTIVES

Interferon is the only established treatment for chronic hepatitis C but the host-dependent or virus-related factors affecting the response rate to interferon therapy are not yet clear. The purpose of this study was to investigate the factors predictive of response to interferon-alfa therapy in chronic hepatitis C.

METHODS

Twenty-five consecutive patients with chronic hepatitis C were randomized to three regimens of interferon-alfa: group A (n = 7, 3 MU every day for 3 months), group B (n = 8, 3 MU every other day for 3 months) and group C (n = 10, 3 MU every other day for 6 months). We quantified serum HC RNA levels by competitive reverse transcription-polymerase chain reaction (RT-PCR) and performed HCV genotyping using type-specific primers deduced form the NS5 region of the HCV genome. We also attempted to identify which demographic, biochemical and histologic factors in addition to virus-related factors would significantly predict beneficial response to interferon by multivariate analysis.

RESULTS

Sustained responders were 8 (36.4%), nonsustained responders were 2 (9.1%) and nonresponders were 12 (54.5%) of 22 patients who had received complete therapy. The initial HCV RNA level (logarithmic transformed copy numbers per ml of serum) in sustained responders (5.75 +/- 0.39) was significantly lower than that of nonsustained responders (6.80 +/- 0.71) and nonresponders (6.70 +/- 0.52) (p < 0.05). In multivariate multiple logistic regression analysis, the serum HCV RNA level before therapy was only the independent predictor of a sustained response to interferon-alfa therapy (p = 0.001).

CONCLUSIONS

Serum HCV RNA level before therapy was the most useful predictor of a sustained response to interferon-alfa therapy for chronic hepatitis C.

Nucleotide sequence stability of the genome of hepatitis delta virus

Cultured cells were cotransfected with a fully sequenced 1,679-base cDNA clone of human hepatitis delta virus (HDV) RNA genome and a cDNA for the genome of woodchuck hepatitis virus (WHV). The HDV particles released were able to infect a woodchuck that was chronically infected with WHV. The HDV so produced was passaged a total of six times in woodchucks in order to determine the stability of the HDV nucleotide sequence. During a final chronic infection with such virus, liver RNA was extracted, and the HDV nucleotide sequence for the 352-base region, positions 905 to 1256, was obtained. By means of PCR, we obtained double-stranded cDNA both for direct sequencing and also for molecular cloning followed by sequencing. By direct sequencing, we found that a consensus sequence existed and was identical to the original sequence. From the sequences of 31 clones, we found 32% (10 of 31) to be identical to the original single nucleotide sequence. For the remainder, there were neither insertions nor deletions but there was a small number of single-nucleotide changes. These changes were predominantly transitions rather than transversions. Furthermore, the transitions were largely of just two types, uridine to cytidine and adenosine to guanosine. Of the 40 changes detected on HDV, 35% (14 of 40) occurred within an eight-nucleotide region that included position 1012, previously shown to be a site of RNA editing. These findings may have significant implications regarding both the stability of the HDV RNA genome and the mechanism of RNA editing.

Ribonucleoprotein complexes of hepatitis delta virus

Human hepatitis delta virus (HDV) is a subviral satellite agent of hepatitis B virus (HBV). The envelope proteins of HDV are provided by the helper virus, HBV, but very little is known about the internal structure of HDV. The particles contain multiple copies of the delta antigen and an unusual RNA genome that is small, about 1,700 nucleotides in length, single stranded, and circular. By using UV cross-linking, equilibrium density centrifugation, and immunoprecipitation, we obtained evidence consistent with the interpretation that delta antigen and genomic RNA form a stable ribonucleoprotein (RNP) complex within the virion. Furthermore, electron-microscopic examination of the purified viral RNP revealed a roughly spherical core-like structure with a diameter of 18.7 +/- 2.5 nm. We also isolated HDV-specific RNP structures from the nuclei of cells undergoing HDV genome replication; both the genome and antigenome (a complement of the genome) of HDV were found to be in such complexes. From the equilibrium density analyses of the viral and nuclear RNPs, we were able to deduce the number of molecules of delta antigen per molecule of HDV RNA. For virions, this number was predominantly ca. 70, which was larger than for the nuclear RNPs, which were more heterogeneous, with an average value of ca. 30.

Assembly of hepatitis delta virus particles

Hepatitis delta virus (HDV) is a subviral satellite of hepatitis B virus (HBV). Since the RNA genome of HDV can replicate in cultured cells in the absence of HBV, it has been suggested that the only helper function of HBV is to supply HBV coat proteins in the assembly process of HDV particles. To examine the factors involved in such virion assembly, we transiently cotransfected cells with various hepadnavirus constructs and cDNAs of HDV and analyzed the particles released into the medium. We report that the HDV genomic RNA and the delta antigen can be packaged by coat proteins of either HBV or the related hepadnavirus woodchuck hepatitis virus (WHV). Among the three co-carboxy-terminal coat proteins of WHV, the smallest form was sufficient to package the HDV genome; even in the absence of HDV RNA, the delta antigen could be packaged by this WHV coat protein. Also, of the two co-amino-terminal forms of the delta antigen, only the larger form was essential for packaging.

Expression from herpesvirus promoters does not relieve the intron requirement for cytoplasmic accumulation of human beta-globin mRNA

Expression plasmids were constructed in which the human beta-globin gene or a variant of it precisely lacking its two introns was transcribed from its own promoter, the herpes simplex virus type 1 thymidine kinase (HSV-tk) promoter, or the immediate early promoter of human cytomegalovirus (CMV-IE). Forty two hours after transfection of these plasmids into monkey kidney cells, nuclear and cytoplasmic RNA were isolated. Quantitative S1 nuclease mapping and primer extension analysis were used to determine the relative abundances, cellular locations, and leader sizes of the accumulated beta-globin RNAs. Whereas transcripts of all of the intron-containing genes accumulated in the cytoplasm to high levels, transcripts of their cDNA variants were neither stably maintained in the nucleus nor accumulated in the cytoplasm, irrespective of the promoter from which transcription was driven. We conclude that the intron requirement for cytoplasmic accumulation of beta-globin RNA can not be circumvented by synthesis from either the promoter of the intronless HSV-tk gene or the CMV-IE promoter.

The roles of the delta antigen in the structure and replication of hepatitis delta virus

The delta antigen is the only known protein encoded by hepatitis delta virus (HDV). The predicted protein is 195 amino acids in length, but for reasons that are not yet clear, there occurs during the replication of the HDV genome, a specific base change in the termination codon of this open reading frame. This leads to the synthesis of a form of the delta antigen that is 19 amino acids longer, with a total length of 214 amino acids. Studies are described which relate to the roles of these two forms of the delta antigen in genome replication and subsequent particle assembly.

Simian virus 40 late transcripts lacking excisable intervening sequences are defective in both stability in the nucleus and transport to the cytoplasm

Little or no simian virus 40 (SV40) late mRNA accumulates in the cytoplasm when the primary transcript lacks an excisable intervening sequence. To begin to understand why, we analyzed the synthesis, processing, transport, and stability of SV40 late transcripts accumulated in the nucleus and cytoplasm of monkey cells cotransfected with the DNAs of wild-type and mutants of SV40 lacking precisely various introns. The data from these experiments indicated that (i) the presence of excisable intervening sequences in SV40 late transcripts is necessary for efficient accumulation in the cytoplasm of any of the SV40 late RNA species and (ii) SV40 late transcripts lacking excisable intervening sequences are defective in both stability in the nucleus and transport to the cytoplasm but not in stability in the cytoplasm. We hypothesize that SV40 late transcripts need to be processed via a pathway that couples stabilization of the primary transcript within the nucleus, excision of intervening sequences, proper 5'- and 3'-end formation, and transport to the cytoplasm.

The late spliced 19S and 16S RNAs of simian virus 40 can be synthesized from a common pool of transcripts

The late transcripts from the simian virus 40 (SV40) are alternatively spliced into two classes of spliced RNAs, 19S and 16S in size. We are interested in understanding the precursor-product relationships that result in the excision of different intervening sequences (introns) from the late transcripts. SV40 mutants containing precise deletions of the introns for each of the spliced 19S and 16S RNA species, including a previously undetected doubly spliced 19S RNA species, were isolated. Analysis by S1 mapping and a modified primer extension technique of the viral RNAs made in monkey cells transfected with each of these mutants led to the following conclusions. (i) Spliced late 19S RNA is not an intermediate in the synthesis of the late 16S RNAs. (ii) The 3' splice site used in the synthesis of the late 16S RNAs can join, albeit inefficiently, with alternative 5' splice sites in the absence of the 5' splice site normally used to synthesize 16S RNA. (iii) There is no obligatory order of excision of introns in the formation of the doubly spliced SV40 late 19S and 16S RNA species. A mutant was constructed by site-directed mutagenesis in which the 5'-proximal 3' splice site used in the synthesis of the doubly spliced RNAs is inactive. Cells transfected with this mutant processed transcripts into 19S RNA which, in wild-type-transfected cells, would have become doubly spliced 16S RNA. Therefore, we conclude that some of the spliced late 19S and 16S RNA can be synthesized from a common pool of transcripts.