Salicylates inhibit flavivirus replication independently of blocking nuclear factor kappa B activation

Flaviviruses comprise a positive-sense RNA genome that replicates exclusively in the cytoplasm of infected cells. Whether flaviviruses require an activated nuclear factor(s) to complete their life cycle and trigger apoptosis in infected cells remains elusive. Flavivirus infections quickly activate nuclear factor kappa B (NF-kappaB), and salicylates have been shown to inhibit NF-kappaB activation. In this study, we investigated whether salicylates suppress flavivirus replication and virus-induced apoptosis in cultured cells. In a dose-dependent inhibition, we found salicylates within a range of 1 to 5 mM not only restricted flavivirus replication but also abrogated flavivirus-triggered apoptosis. However, flavivirus replication was not affected by a specific NF-kappaB peptide inhibitor, SN50, and a proteosome inhibitor, lactacystin. Flaviviruses also replicated and triggered apoptosis in cells stably expressing IkappaBalpha-DeltaN, a dominant-negative mutant that antagonizes NF-kappaB activation, as readily as in wild-type BHK-21 cells, suggesting that NF-kappaB activation is not essential for either flavivirus replication or flavivirus-induced apoptosis. Salicylates still diminished flavivirus replication and blocked apoptosis in the same IkappaBalpha-DeltaN cells. This inhibition of flaviviruses by salicylates could be partially reversed by a specific p38 mitogen-activated protein (MAP) kinase inhibitor, SB203580. Together, these results show that the mechanism by which salicylates suppress flavivirus infection may involve p38 MAP kinase activity but is independent of blocking the NF-kappaB pathway.

Potential dengue virus-triggered apoptotic pathway in human neuroblastoma cells: arachidonic acid, superoxide anion, and NF-kappaB are sequentially involved

Direct in vivo evidence for the susceptibility of human neuronal cells to dengue virus has not been reported. In this study, we demonstrated that type 2 dengue (DEN-2) virus infection induced extensive apoptosis in the human neuroblastoma cell line SK-N-SH. Phospholipase A(2) (PLA(2)) was activated by DEN-2 infection, which led to the generation of arachidonic acid (AA). Inhibition of PLA(2) activity by the PLA(2) inhibitors, AACOCF(3) and ONO-RS-082, diminished DEN-2 virus-induced apoptosis. In contrast, the cyclooxygenase inhibitors aspirin and indomethacin, thought to increase AA accumulation by blocking AA catabolism, enhanced apoptosis. Exogenous AA induced apoptosis in a dose-dependent manner. Superoxide anion, which is thought to be generated through the AA-activated NADPH oxidase, was increased after infection. Pretreatment with superoxide dismutase (SOD) protected cells against DEN-2 virus-induced apoptosis. Furthermore, generation of superoxide anion was blocked by AACOCF(3). In addition, the transcription factors, NF-kappaB and c-Jun, were found to be activated after DEN-2 virus infection. However, pretreatment of cells with oligodeoxynucleotides containing NF-kappaB, but not c-Jun, binding sites (transcription factor decoy) strongly prevented dengue virus-induced apoptosis. The finding that AACOCF(3) and SOD significantly block activation of NF-kappaB suggests that this activation is derived from the AA-superoxide anion pathway. Our results indicate that DEN-2 virus infection of human neuroblastoma cells triggers an apoptotic pathway through PLA(2) activation to superoxide anion generation and subsequently to NF-kappaB activation. This apoptotic effect can be either directly derived from the action of AA and superoxide anion on mitochondria or indirectly derived from the products of apoptosis-related genes activated by NF-kappaB.

Analysis of prognostic factors in Chinese women with breast cancer in southern Taiwan

BACKGROUND

We conducted a retrospective review of all early-stage breast cancer patients treated at the Veterans General Hospital-Kaohsiung to determine overall and disease-free survival rates, and to evaluate prognostic factors for these outcomes.

METHODS

During the period of October, 1990, to December, 1997, 332 patients with early-stage breast cancer were treated at our institution. Cox's multivariate regression analysis was used to select prognostic factors significant for overall survival and disease-free survival.

RESULTS

The survival rate for breast cancer patients was 88.35% at five years. Prognostic factors predicting breast cancer mortality included poorly differentiated histologic grade, four or more lymph nodes positive for metastasis and negative progesterone-receptor status. For disease recurrence, prognostic factors included positive nodes, aneuploidy and poorly differentiated histologic grading.

CONCLUSIONS

We conclude that a combination of lymph node status, DNA ploidy, histologic grading and progesterone-receptor status help to evaluate the possible outcomes for patients with breast cancer and to plan for optimal therapy.

Membrane permeabilization by small hydrophobic nonstructural proteins of Japanese encephalitis virus

Infection with Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, may cause acute encephalitis in humans and induce severe cytopathic effects in various types of cultured cells. We observed that JEV replication rendered infected baby hamster kidney (BHK-21) cells sensitive to the translational inhibitor hygromycin B or alpha-sarcine, to which mock-infected cells were insensitive. However, little is known about whether any JEV nonstructural (NS) proteins contribute to virus-induced changes in membrane permeability. Using an inducible Escherichia coli system, we investigated which parts of JEV NS1 to NS4 are capable of modifying membrane penetrability. We found that overexpression of NS2B-NS3, the JEV protease, permeabilized bacterial cells to hygromycin B whereas NS1 expression failed to do so. When expressed separately, NS2B alone, but not NS3, was sufficient to alter bacterial membrane permeability. Similarly, expression of NS4A or NS4B also rendered bacteria susceptible to hygromycin B inhibition. Examination of the effect of NS1 to NS4 expression on bacterial growth rate showed that NS2B exhibited the greatest inhibitory capability, followed by a modest repression from NS2A and NS4A, whereas NS1, NS3, and NS4B had only trivial influence with respect to the vector control. Furthermore, when cotransfected with a reporter gene luciferase or beta-galactosidase, transient expression of NS2A, NS2B, and NS4B markedly reduced the reporter activity in BHK-21 cells. Together, our results suggest that upon JEV infection, these four small hydrophobic NS proteins have various modification effects on host cell membrane permeability, thereby contributing in part to virus-induced cytopathic effects in infected cells.

Study of Dengue virus infection in SCID mice engrafted with human K562 cells

Here we report that severe combined immunodeficient (SCID) mice engrafted with human K562 cells (K562-SCID mice) can be used as an animal model to study dengue virus (DEN) infection. After intratumor injection into K562 cell masses of PL046, a Taiwanese DEN-2 human isolate, the K562-SCID mice showed neurological signs of paralysis and died at approximately 2 weeks postinfection. In addition to being detected in the tumor masses, high virus titers were detected in the peripheral blood and the brain tissues, indicating that DEN had replicated in the infected K562-SCID mice. In contrast, the SCID mice were resistant to DEN infection and the mock-infected K562-SCID mice survived for over 3 months. These data illustrate that DEN infection contributed directly to the deaths of the infected K562-SCID mice. Other serotypes of DEN were also used to infect the K562-SCID mice, and the mortality rates of the infected mice varied with different challenge strains, suggesting the existence of diverse degrees of virulence among DENs. To determine whether a neutralizing antibody against DEN in vitro was also protective in vivo, the K562-SCID mice were challenged with DEN-2 and received antibody administration at the same time or 1 day earlier. Our results revealed that the antibody-treated mice exhibited a reduction in mortality and a delay of paralysis onset after DEN infection. In contrast to K562-SCID, the persistently DEN-infected K562 cells generated in vitro invariably failed to be implanted in the mice. It seems that in the early stage of implantation, a gamma interferon activated, nitric oxide-mediated anti-DEN effect might play a role in the innate immunity against DEN-infected cells. The system described herein offers an opportunity to explore DEN replication in vivo and to test various antiviral protocols in infected hosts.

A study of the oligomeric state of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-preferring glutamate receptors in the synaptic junctions of porcine brain

The number of the subunits in an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-preferring L-glutamate receptor in the synaptic junctions of porcine brain was investigated in this study. Upon incubation of the synaptic junctions with three cross-linking regents, dimethyl adipimidate (DMA), dimethyl suberimidate (DMS) and N-succinimidyl-(4-azidophenyl)-1,3'-dithiopropionate (SADP), AMPA receptor subunits in higher-molecular-mass aggregates were detected by immunoblotting. These aggregates migrated as proteins of approx. 200, 300 and 400 kDa. The number and identity of the subunits in a solubilized AMPA receptor were also investigated here. Two samples, W1 and W2, enriched in AMPA receptors were prepared from synaptic junctions by a combination of detergent-solubilization, anion-exchange chromatography and wheatgerm agglutinin affinity chromatography. Hydrodynamic behaviour analyses revealed that the majority of the AMPA receptors in either one of these samples were asymmetrical detergent-surrounded particles with a protein mass around 350 kDa. SDS/PAGE analysis revealed that the majority of AMPA receptors in the W1 sample were comprised of dimers of 106 kDa subunits which were covalently linked by disulphide bonds. Cross-linking these receptors with SADP yielded a new band of approx. 400 kDa. The results obtained here, either from the studies of AMPA receptors embedding in synaptic junctions or from those of detergent-solubilized and partially purified receptors, suggest that AMPA receptors contain a basic core structure comprising of four 106 kDa subunits.

Purification and biochemical characterization of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate-sensitive L-glutamate receptors of pig brain

Two preparations of glutamate receptors were purified from the synaptic junctions of pig brain by a combination of detergent solubilization, anion-exchange chromatography, wheat-germ agglutinin affinity chromatography and sedimentation through sucrose gradients. These preparations were enriched in specific L-[3H]glutamate binding activity (> 5000 pmol of glutamate binding sites/mg of protein), and the rank order of ligand affinity for binding to these preparations was: quisqualate > 6-cyano-7- nitroquinoxaline-2,3-dione > alpha-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA) > L-glutamate > kainate > > N-methyl-D-aspartate approximately L-2-amino-4-phosphonobutyrate. SDS/PAGE analysis revealed that more than 80% of the protein in either of these preparations appeared as a single protein band of 106 kDa. Two-dimensional gel electrophoresis further revealed that these 106 kDa proteins consisted of a series of acidic proteins which were recognized by antibodies against rat AMPA receptor subunits. These 106 kDa proteins were also recognized by wheatgerm agglutinin and concanavalin A; in addition, peptide N-glycosidase F treatment of these preparations decreased their size to 99 kDa. Our results suggest that the putative glutamate receptors isolated here are likely to belong to the AMPA subtype of glutamate receptors in pig brain. Using the purification procedure reported here, 5 micrograms of AMPA receptor proteins can be isolated from 250 g of pig brain tissue.

Persistence of Japanese encephalitis virus is associated with abnormal expression of the nonstructural protein NS1 in host cells

Persistent infection with Japanese encephalitis virus (JEV) was established in murine neuroblastoma N18 cells, and the persistency has been maintained in cell culture for over 6 months. From the persistently infected cells, a clone named C2-2 was selected and expanded to form a stable cell line. The vast majority of C2-2 cells showed viral protein staining by immunofluorescence and continuously produced low levels of virus (10(3) to 10(4) PFU/ml) without marked cytopathic effects or cyclic variations. In addition to the wild-type viral proteins, truncated forms of the viral nonstructural protein 1 (NS1) as well as its derivative NS1' were produced in C2-2 cells. Both truncated NS1 and NS1' contain deletions at their N-termini; however, the analyses by RT-PCR and direct sequencing of the viral RNA failed to detect any truncations or mutations within the NS1 region, suggesting that NS1 truncation was a result of a unique posttranslational proteolytic cleavage of NS1 in the persistently infected cells. Similar but not identical truncation of NS1 was also observed in two other persistently infected cell lines established in Vero and DBT (murine astrocytoma) cells. However, viruses released from C2-2 cells did not produce truncated NS1 upon infection of N18 cells, suggesting that NS1 truncations were the result of virus-cell interaction in persistently infected cells. These data indicate a strong association between abnormal NS1 expression and JEV persistency. A probable involvement of dysfunctional NS1 in the establishment and/or maintenance of JEV persistency in tissue culture is discussed.

Generation and characterization of Japanese encephalitis virus specific monoclonal antibodies

Monoclonal antibodies (MoAbs) specifically against Japanese encephalitis virus (JEV) were generated by fusion of immunized mouse spleen cells with NS-1 myeloma cells. Nakayama-NIH (Na) and three Taiwan local strains of JEV, i.e., TL isolated from a patient's brain in 1965, NT109 (JE7) isolated from Cx. tritaeniorhynchus in 1985, and RP9, a plaque purified clone of NT109, were used in the immunization. The specificities of moAbs were determined by immunoprecipitation and western blotting, using JEV-infected cell lysates. They were confirmed by the same methods using recombinant JEV proteins as antigens. From Na immunization, 4 anti-E, 3 anti-NS1 and 3 anti-NS3 moAbs were generated. Seventeen anti-E, three anti-NS1 and three anti-NS3 specific moAbs were generated from mice immunized with Taiwan local JEV strains. Overall 21 anti-E, 6 anti-NS1, and 6 anti-NS3 moAbs were produced and characterized. The isotypes of these moAbs were also determined and described. Interestingly, a majority of the moAbs generated for RP9 were IgG1 isotype. In conclusion, 33 moAbs specific to JEV were generated and characterized, and some of these anti-JEV moAbs were made against Taiwan local isolates. These moAbs provide a powerful tool to study JEV, especially the antigenic properties of Taiwan's local strains.

Detection of point mutations in the chloroplast genome by single-stranded conformation polymorphism analysis

Single-stranded conformation polymorphism (SSCP) analysis was used to examine the mutations of the chloroplast 16S rRNA locus of streptomycin-resistant mutants in Nicotiana plumbaginifolia. DNA fragments of 121, 517, 968 and 1578 bp, each possessing a known point mutation, were generated by polymerase chain reaction (PCR). The resulting fragments were denatured and separated by nondenaturing polyacrylamide gel electrophoresis. Compared to the patterns of the wild-type DNA fragments, the bands of the single-stranded DNA fragments of 121 and 517 bp with base changes were shifted. However, no pattern variations were detected from the DNA fragments of 968 and 1578 bp generated from both wild-type and mutants.

Inflammatory aneurysm of the abdominal aorta: diagnosis by computerized tomography and ultrasonography

We correctly diagnosed seven cases of inflammatory aneurysm of the abdominal aorta preoperatively by computerized tomography (CT) and ultrasonography (US). Excessive thickening of the aneurysmal wall and conspicuous enhancement on CT are the characteristic features that led to the correct diagnosis. Ultrasonographic findings are nonspecific, but US is the screening method of choice. If US shows a sonolucent zone anterior or anterolateral to an atherosclerotic aneurysm, CT should be used to delineate the perivascular abnormalities.

Diagnostic imaging in mediastinal thyroid tumor

Various diagnostic imagings in nine patients with mediastinal goiters were presented. The clinical manifestations of these patients were various, from totally asymptomatic to severe dyspnea. Six of the nine patients underwent surgical intervention, three were follicular adenomas and three were nodular goiters. A chest radiograph (positive in seven out of nine patients) provided the most valuable initial localization of a goiter mass to the anterior, middle, or posterior compartment. Esophagograms (performed in four patients) showed compression of esophagus by the mediastinal mass. I-131 scintigraphy (performed in seven patients) was capable of detection of functional (in three patients) vs nonfunctional status of thyroid status (in four patients). Angiography (performed in five patients), characterized by anatomic continuity with cervical thyroid gland, calcifications, well-defined border of masses and/or contrast enhancement, offered important roles to direct a diagnosis of intrathoracic goiter. The computed tomography becomes increasingly important because all mediastinal goiters are not radioiodine avid.

Intramural gastric diverticula: a report of three cases

Intramural gastric diverticula are true diverticula, entirely contained within the wall of the stomach without deformity of the serosa. All of the 13 known reported cases are at the greater curvature of the distal antrum. This is true of our three cases as well. The unique location and characteristic change in shape with peristalsis distinguish them from pathological entities.

Carcinoma of the esophagus: assessment of submucosal extent

Submucosal extension of carcinoma of the esophagus is common, often presenting as a varicoid pattern on the esophagogram. Forty-two per cent of our 153 patients with carcinoma of the esophagus showed area(s) of a varicoid pattern in association with the other usual pattern(s) (fungating, ulcerating or infiltrating). A few of the patients have findings similar to those associated with esophageal varices on the esophagogram. Such patients are identical to those with "varicoid carcinoma" reported in the literature. The differentiation between varicoid carcinoma dn esophageal varices may be made on fluoroscopy, where the former is characterized by rigidity and the latter by flexibility.

Isolation of Candida albicans and their sensitivity to antifungal agents

During 1978 and 1979 outbreaks of candidiasis were encountered in about 500,000 broiler chickens on 30 farms, 30,000 guinea fowl on 4 farms, 500 geese on 1 farm, and 10 penguins in a zoo. This represents the first report of avian candidiasis in Taiwan. Diagnoses were based on typical gross and microscopic pathology consistent isolation of Candida albicans from crop and esophageal lesions, virulence of isolates in rabbits, identification of the isolates as C. albicans serotype A by chlamydospore and germ tube formation, fermentation tests, and agglutination by specific antisera, and the lack of any sign of fowl pox or trichomoniasis. The upsurge of candidiasis is attributed to the modernization stressors which interact deleteriously with opportunistic pathogens. In vitro sensitivity testing recorded the following order of effectiveness against 20 isolates: nystatin greater than gentian violet greater than copper sulfate = propionic acid = p-hydroxy benzoic acid greater than calcium propionate = propylene glycol.

Esophageal intramural pseudodiverticulosis

Esophageal intramural pseudodiverticulosis (EIP) is a rare condition of unknown etiology. It is characterized by multiple, small, flaskshaped outpouchings in the esophageal wall. Involvement may be segmental or diffuse. Since this entity was first reported in 1960, there have been 43 cases described in the English literature. These cases are reviewed and six additional cases are reported with emphasis on clinical and radiographic parameters of this entity.

Tuberculous mediastinal lymphadenopathy in adults

Three cases of paratracheal and hilar lymph node enlargement without parenchymal lung lesion simulating sarcoidosis, lymphoma, and metastasis were finally proved to be tuberculous lymphadenitis. Although it is not a common manifestation of tuberculous infection in the adult, this possibility should be considered in the differential diagnosis of mediastinal lymphadenopathy, especially in non-whites.