Targeting of aminopeptidase N to bile canaliculi correlates with secretory activities of the developing canalicular domain

We have used human hepatoma cell lines as an in vitro model to study the development of hepatic bile canaliculi (BC). Well-differentiated hepatoma cells cultured for 72 hours could develop characteristic spheroid structures at sites of cell-cell contact that contained tight junctions and various membrane protein markers, resembling BC found in vivo. Intact cytoskeleton was essential for this differentiation process. In the coculture experiments in which cells of different origins were populated together, BC only formed between hepatic cells and preferentially among well-differentiated cells. Poorly differentiated hepatoma cells never formed BC among themselves, but could be induced to undergo canalicular differentiation by interacting with well-differentiated cells. During BC morphogenesis, integral canalicular membrane proteins were gradually delivered and accumulated at the developing BC. Among them, targeting of aminopeptidase N (APN) seemed to correlate with activation of certain secretory functions. Specifically, only APN-positive BC supported excretion of fluorescein diacetate (FDA) and 70-kd dextran, but had no relationship with secretion of horseradish peroxidase (HRP). Targeting of another BC protein, dipeptidyl peptidase IV (DPPIV), on the other hand, bore no association with any secretory activity examined. In addition, inhibition of enzymatic activity of APN could perturb canalicular differentiation without affecting cell proliferation. Our results suggest that targeting of APN proteins may reflect or even play an important role in the development and functional maturation of the canalicular structures.

Structure elucidation of the adducts formed by fjord region Dibenzo[a,l]pyrene-11,12-dihydrodiol 13,14-epoxides with deoxyguanosine

(+/-)-anti-Dibenzo[a,l]pyrene-11,12-dihydrodiol 13,14-epoxide {(+/-)-anti-DB[a,l]PDE} was reacted with deoxyguanosine (dG) in dimethylformamide at 100 degrees C for 30 min, and two sets of adducts were isolated: a mixture of (+/-)-anti-cis- & -trans-N(2)dG (43%) and a mixture of (+/-)-anti-cis- & -trans-N7Gua (45%). Both are mixtures of four stereoisomers that cannot be separated by HPLC. Similarly, (+/-)-syn-DB[a,l]PDE was reacted with dG under the same conditions, and (+/-)-syn-cis- & -trans-N(2)dG (38%) and (+/-)-syn-cis- & -trans-N7Gua (59%) were obtained. The structures of the adducts were determined by a combination of NMR and fast atom bombardment mass spectrometry. By reacting (-)-anti-DB[a,l]PDE or (+)-syn-DB[a,l]PDE with dG under the same conditions, however, optically pure N(2)dG and N7Gua isomers were obtained: (-)-anti-cis-N(2)dG (12%), (-)-anti-trans-N(2)dG (17%), (-)-anti-trans-N7Gua (43%), (+)-syn-cis-N(2)dG (7%), (+)-syn-trans-N(2)dG (3%), (+)-syn-cis-N7Gua (36%), and (+)-syn-trans-N7Gua (22%). The structures of the optically pure adducts were assigned by NMR. syn- and anti-DB[a,l]PDE-N(2)dG adducts can be distinguished by fluorescence line-narrowing spectroscopy (FLNS). Moreover, distinction between cis- and trans-stereochemistry of the adducts is also straightforward by FLNS, because the FLN spectra for the four DB[a,l]PDE-N(2)dG adducts, anti-cis, anti-trans, syn-cis, and syn-trans, are spectroscopically unique.

Therapeutic effects of moxibustion on experimental tumor

This work investigated the therapeutic effects of the improved form of moxibustion (MT) on experimental tumor. Sarcoma 180 cells (1 x 10(7)) were transplanted into the subcutaneous tissue in the breast area of female ICR mice. Mice bearing a tumor were divided into one control and four experimental groups. The experimental groups were treated with MT for 1, 2, 3 and 4 times (abbreviated as MT1, MT2, MT3, MT4, respectively). This study showed that the experimental group treated with MT3 displayed the optimal therapeutic response. The longest mean survival time (87.8 days) within 120 days after treatment of MT3 significantly differed from the control group (60.2 days). In addition, uptake of 86Rb-radioactive tracer significantly decreased in tumors treated with MT3. The improved form of moxibustion used in this study is a reliable model of localized hyperthermia in tumor therapy.

Outcome comparison in traumatic lower-extremity reconstruction by using various composite vascularized bone transplantation

Lower-extremity injury may present as a composite soft-tissue and bone defect, resulting directly from trauma or subsequent debridements. These composite defects often require vascularized osteocutaneous flaps for an effective, staged reconstruction. Among various donor sites, the vascularized fibular flap is generally considered the best option because of its inherent advantages. However, when the fibular flap is not available, iliac and rib flaps become the alternative choices. The purpose of this retrospective study was to compare the functional results of the alternatively chosen bone flaps (iliac and rib flaps) with those of the fibular flaps.

Spectral and conformational analysis of deoxyadenosine adducts derived from syn- and anti-Dibenzo[a,l]pyrene diol epoxides: fluorescence studies

Low-temperature fluorescence spectra and results of conformational studies with trans-syn-, cis-syn-, trans-anti-, and cis-anti-dibenzo[a,l]pyrene diol epoxide (DB[a,l]PDE)-derived deoxyadenosine (dA) adducts are presented and compared with those previously obtained for the stereoisomeric DB[a,l]P tetrols [Jankowiak, R., et al. (1997) Chem. Res. Toxicol. 10, 677-686]. In contrast to DB[a,l]P tetrols, for which only trans isomers exhibited two conformers, all stereoisomeric dA adducts adopt two different conformations with either half-chair or half-boat structures for the cyclohexenyl ring, and an "open"- or "folded"-type configuration between dA and the DB[a,l]P moiety. The major conformations observed for trans-syn-, cis-syn-, and cis-anti-DB[a,l]PDE-14-N(6)dA could be assigned on the basis of the previous calculations for the DB[a,l]P tetrols. The major conformers of the trans-syn- and cis-syn-DB[a, l]PDE-14-N(6)dA adducts exist in conformations I and II, with their fluorescence origin bands at approximately 382 and approximately 389 nm, respectively. In conformation I, the cyclohexenyl ring adopts a half-boat structure with dA in a pseudoaxial position (an open configuration), whereas the cyclohexenyl ring in conformation II adopts a half-chair structure with dA in pseudoequatorial position (a folded configuration). The major conformation of cis-anti-DB[a, l]PDE-14-N(6)dA, with its origin band at approximately 389 nm, was also assigned as a folded-type configuration with a half-chair structure in the cyclohexenyl ring. Molecular mechanics and dynamical simulations were performed for interpretation of the low-temperature fluorescence spectra and (1)H NMR coupling constants observed for the trans-anti-DB[a,l]PDE-14-N(6)dA adduct. The major conformer of this adduct has a half-chair structure in the cyclohexenyl ring, but a deviation from planarity in the fjord region different from that of conformer II of cis-anti-DB[a, l]PDE-N(6)dA. This new structure is labeled as conformer II'. Its (0, 0) fluorescence band is at 388.1 and 388.3 nm in ethanol and glycerol/water glasses, respectively, consistent with the folded-type configuration revealed by the calculations. The fluorescence line-narrowed spectra reveal that the trans-syn-, cis-syn-, trans-anti-, and cis-anti-DB[a,l]PDE-14-N(6)dA adducts can be distinguished. Thus, their spectra should prove useful for identification of DB[a,l]P-DNA adducts formed at low levels in biological samples.

Donor-site morbidity comparison between endoscopically assisted and traditional harvest of free latissimus dorsi muscle flap

Endoscopically assisted harvest of free latissimus dorsi muscle flaps is being used more frequently in reconstructive microsurgery because it requires a smaller incision and leaves a more acceptable scar in the donor site. Donor-site morbidity was compared between groups of 22 latissimus dorsi muscles harvested using the endoscopically assisted technique and 26 using the traditional technique. The results revealed no statistically significant differences in the amount of intraoperative bleeding, the incidence of postoperative hematoma and seroma, and the incidence of donor-site wound infection as assessed by the surgeon. However, a patient questionnaire revealed that even though it did not reach a statistically significant difference, endoscopically assisted harvest of the latissimus dorsi muscle had less pain and allowed earlier and better movement of the upper extremity of the donor site. The patients' attitudes and feelings about the scar and overall satisfaction were also higher in the endoscopic group, which demonstrated a statistically significant difference.

On-line identification of diastereomeric dibenzo[a,l]pyrene diol epoxide-derived deoxyadenosine adducts by capillary electrophoresis-fluorescence line-narrowing and non-line narrowing spectroscopy

A capillary electrophoretic method for the separation and on-line identification of closely related analytes using low-temperature fluorescence spectroscopy is reported for the eight diastereomeric deoxyadenosine (dA) adducts derived from dibenzo[a,l]pyrene diol epoxide (DB[a,l]PDE). Electrophoretic separation of stereoisomers was accomplished by application of a mixed surfactant buffer [dioctyl sulfosuccinate (DOSS) and Brij-S], which was below the critical micelle concentration (CMC) due to the high concentration (approximately 25%) of organic solvent. Addition of multiple surfactant additives to the separation buffer provided electrophoretic resolution, which was unattainable under single surfactant conditions. It is shown that the CE-separated analyte zones could be identified on-line via low-temperature (4.2 K) fluorescence non-line narrowing and fluorescence line-narrowing (FLN) spectroscopy. In addition, it was determined that in CE buffer trans-syn-,cis-syn- and cis-anti-DB[a,l]PDE-14-N6dA diastereomeric adducts exist mostly with the -dA and DB[a,l]P moiety in an "open"-type conformation while the trans-anti-DB[a,l]PDE-14-N6dA adducts exist in two different conformations whose relative distribution depends on matrix composition. The above conformations have also been revealed by selective laser excitation. Thus, the low-temperature methodology not only provides fingerprint structure via vibrationally resolved 4.2 K fluorescence spectra for adduct identification, but also provides conformational information on the spatial relationship of the carcinogen and dA moiety. These results, taken together with those for DB[a,l]P-DNA adducts formed in standard glasses and mouse epidermis exposed to DB[a,l]P, support our earlier findings that DB[a,l]P-derived adducts exist in different conformations [Jankowiak et al., Chem. Res. Toxicol. 11 (1998) 674]. Therefore, the combination of the separation power of CE and spectral selectivity of low-temperature fluorescence spectroscopy at NLN and FLN conditions provides a powerful methodology which should prove useful for identification of closely related DNA adducts formed at low levels in biological systems.

Hepatitis C virus infection among short-term intravenous drug users in southern Taiwan

The purpose of this study was to determine the correlation between the prevalence of hepatitis C virus (HCV) infection with duration of drug use and other risk factors among drug users. This survey covered 899 male drug users from Kaohsiung Narcotic Abstention Institute and Kaohsiung prison. The prevalence of positive anti-HCV was 67.2% among intravenous drug users (IVDU) and 14.7% among non-intravenous drug users (non-IVDU). Among intravenous (IV) drug users, age and duration of drug use were independently related to HCV seropositivity. Seroprevalence rate for HCV in the IVDU group increased with increasing duration of injection use within the first seven years of drug use. However, the steepest trajectory in seroprevalence of HCV infection occurred within the first four months. Due to the high rate of HCV infection among drug users, investigation of risk behaviors should be routine in such a group. A high frequency of HCV infection was also found among short-term injectors, which indicated that early risk reduction intervention was an important measure in moderating HCV infection.

Increased colonic ornithine decarboxylase activity in inflammatory bowel disease in children

The risk of colorectal carcinoma is increased in pediatric-onset inflammatory bowel disease (IBD). There is little information available regarding the colonic mucosal proliferative state in children with IBD. The aim of this study was to assess colonic ornithine decarboxylase (ODC) activity, a marker of cell proliferation, in pediatric IBD patients. ODC activity was assessed in colonic mucosa from 23 children (7 with ulcerative colitis, 9 with Crohn's disease, and 7 controls) undergoing colonoscopic examination. ODC activities were then compared with degree of inflammation of biopsied samples. ODC activities in patients with and without corticosteroid treatment were also analyzed. The mucosal ODC activities of sigmoid colon and rectum were significantly higher (2.5- to 4-fold) in both ulcerative colitis and Crohn's disease. The higher ODC activity was associated with increased mucosal inflammation. Moreover, treatment with corticosteroids decreased the ODC activity. In conclusion, using ODC activities as a marker of cell proliferation, our results suggest that there is a higher colonic mucosal proliferative state in children with IBD. The increased ODC activities were associated with increased colonic mucosal inflammation. Colonic mucosal ODC activity may provide an additional parameter to access the therapeutic efficacy of corticosteroid treatment in pediatric IBD patients.

Recombinant rhodostomin substrates induce transformation and active calcium oscillation in human platelets

Platelet activation has been a focus of numerous studies in normal and abnormal states. Morphological changes and calcium signals found with activated platelets in vitro have been well characterized. However, the rate of cell spreading on substrates and the frequency of calcium oscillation within individual platelets upon activation have not yet been reported. In this study, we first examined the ability of a recombinant fusion protein of rhodostomin (GST-rhodostomin), a snake disintegrin containing an Arg-Gly-Asp (RGD) motif, to activate platelets when GST-rhodostomin served as a substrate. Four aspects of platelet activities induced by immobilized GST-rhodostomin and fibrinogen were analyzed in parallel. Examinations of (1) translocation of P-selectin from intracellular compartments to the plasma membrane, (2) platelet adhesion to and spreading on substrates, (3) platelet contact pattern on substrates, and (4) the degree of phosphorylation of focal adhesion kinase in platelets indicated that GST-rhodostomin was a better substrate for platelet activation than fibrinogen. Analysis of the rate of platelet spreading on GST-rhodostomin was examined by time-lapsed video microscopy. The spreading rate averaged 0.43 micrometer/minute, while cell spreading averaged 0.22 micrometer/minute when platelets were plated on fibrinogen and treated with thrombin. A newly developed method, using time-lapsed microscopy and the Metamorph program, was used to analyze calcium signals within platelets. We found that platelets on GST-rhodostomin evoked calcium oscillation at a frequency of 4.77 spike/cell/minute vs 2.76 spike/cell/minute on fibrinogen. The results of cell spreading and calcium oscillation were consistent with the results of microscopic and biochemical assays. We therefore conclude that the determination of the rate of platelet spreading and the frequency of calcium oscillation within platelets performed in this study provides more quantitative parameters for measuring platelet activities. Our results also suggest that GST-rhodostomin might potentially be used as a probe to dissect the molecular mechanisms underlying the kinetic processes of platelet activation.

Suppression of tumorigenicity in cervical carcinoma HeLa cells by an episomal form of adeno-associated virus

To compare the oncosuppressive activity of integrated and episomal adeno-associated virus (AAV), two Epstein-Barr virus (EBV) derived episomal form vectors, p205 and p220, were used to generate plasmids containing episomal AAV. HeLa cells transfected with p205, p220, and the plasmids with forward (pA205-1, pA220-1) and reverse (pA205-1, pA220-2) orientation of inserted AAV DNA were designated H205, H220, HA205-1, HA220-1, HA205-1, and Ha220-2, respectively. The respective average copy numbers of pA205 and pA220 per cell are 4.9-6.9 and 4.3. The AAV-transfected HeLa cells displayed growth inhibition when compared to parental and the vector-transfected HeLa cells. Nude mice assay showed that the tumor size from HA205-1 and HA205-2 cells were 11.3 and 22.6%, and those from HA220-1 and HA220-2 cells were 54.8 and 57.3%, respectively, when compared to parental HeLa cells. HA205-1 cells containing forward AAV insert exerted more oncosuppressive effect than HA205-2 cells containing reverse AAV insert. Our data indicate that the episomal AAV can exert oncosuppressive activity as compared to the integrated AAV in HeLa cells.

Calcium binding mode of gamma-carboxyglutamic acids in conantokins

Conantokin-T (con-T) and conantokin-G (con-G) are two highly homologous peptide toxins found in Conus venom. The former is a 21-residue peptide with four gamma-carboxyglutamic acid (Gla) residues (at positions 3, 4, 10 and 14), while the latter is a 17-residue peptide with five gamma-carboxyglutamic acid residues (at positions 3, 4, 7, 10 and 14). Despite the apparent similarity in number and relative positions of the gamma-carboxyglutamic acid residues, (113)Cd-NMR studies indicated a distinct metal binding behavior for con-G and con-T. There appears to be four binding sites in con-G in contrast to one metal binding site in con-T. To elucidate the mode of calcium binding by the gamma-carboxyglutamic acid residues in these conantokins, we designed various analogous peptides with their gamma-carboxyglutamic acid replaced by other amino acid residues. (113)Cd-NMR experiments on conantokin analogues reveal that the major difference in the number of metal binding sites between con-G and con-T is due to the residue at position 7. We also performed molecular simulations to calculate the relative binding free energies of several potential binding sites. Based on our theoretical and experimental results, we propose a 'four-site' binding model for conantokin-G and a 'single-site' binding model for conantokin-T.

Interactive voxel surface rendering in medical applications

Semi-boundary (SB) data structure is a compact voxel surface representation of the structure from the medical images. It represents only the boundary of the extracted structure and only an opaque object boundary involved in a 3D dataset can be visualized. Its computational complexity is in proportion to the number of SB voxels. In this paper, we propose schemes to reduce the number of projections in two ways. First, in conjunction with neighboring code, we exploit a set of visibility tables to cull some of the invisible SB voxels. Second, we exploit three pass rotations and an incremental approach to quickly determine the projection position for each SB voxel during rendering. With these two combinations, we significantly improve SB rendering performance. As a result, we can achieve an interactive rendering speed on general purpose workstations for our medical applications.

Hydrops fetalis with complete heart block secondary to congenital lupus: report of one case

Neonatal lupus erythematosus is an uncommon syndrome characterized by a congenital heart block and/or cutaneous lesion. We report a male newborn with neonatal lupus erythematosus presenting with complete heart block, cutaneous lesions, and hydrops. Transplacental passage of anti-SSA/Ro and anti-SSB/La antibodies were positive. Under the regimens of steroid for maternal systemic lupus erythematosus, perinatal anticongestive agents, and postnatal ventricular pacing with inotropic therapy, the infant died at the age of two days. The prognosis of hydrops fetalis secondary to neonatal lupus with complete heart block is usually fatal.

Reduction in lipopolysaccharide-induced thrombocytopenia by triflavin in a rat model of septicemia

BACKGROUND

Thrombocytopenia frequently occurs early in the course of Gram-negative bacterial infections. Triflavin, an Arg-Gly-Asp-containing disintegrin, has been suggested to interfere with the interaction of fibrinogen with the glycoprotein IIb/IIIa complex. The present study was undertaken to determine whether triflavin could prevent thrombocytopenia in lipopolysaccharide (LPS)-treated rats.

METHODS AND RESULTS

In this study, 51Cr-labeled platelets were used to assess blood and tissue platelet accumulation after LPS challenge. The administration of LPS (4 mg/kg IV bolus) for 4 hours induced a reduction in radiolabeled platelets in blood and an obvious accumulation of platelets in liver. Triflavin (500 microg/kg) but not GRGDS (20 mg/kg) significantly prevented the alteration of radiolabeled platelet distribution in blood and liver when induced by LPS. Furthermore, triflavin but not GRGDS markedly suppressed the elevation in plasma thromboxane B2 concentration within the 4-hour period of LPS administration. In LPS-treated rats, the 5-hydroxytryptamine level was lower in the blood and higher in the liver compared with levels in normal saline-treated rats. Pretreatment with triflavin (500 microg/kg) significantly reversed the 5-hydroxytryptamine concentration in blood and liver of LPS-treated rats. In histological examinations and platelet adhesion assay, triflavin markedly inhibited the adhesion of platelets to subendothelial matrixes in vivo and in vitro.

CONCLUSIONS

The results indicate that triflavin effectively prevents thrombocytopenia, possibly through the following 2 mechanisms: (1) Triflavin markedly inhibits platelet aggregation, resulting in decreased thromboxane A2 formation. (2) It inhibits the adhesion of platelets to subendothelial matrixes, thereby leading to a reversal in the distribution of platelets in blood and liver in LPS-treated rats.

Interactive 3-D virtual colonoscopy system

We describe a low-cost three-dimensional (3-D) virtual colonoscopy system that is a noninvasive technique for examining the entire colon and can assist physicians in detecting polyps inside the colon. Using the helical CT data and proposed techniques, we can three-dimensionally reconstruct and visualize the inner surface of the colon. We generate high resolution of video views of the colon interior structures as if the viewer's eyes were inside the colon. The physicians can virtually navigate inside the colon in two different modes: interactive and automatic navigation, respectively. For automatic navigation, the flythrough path is determined a priori using the 3-D thinning and two-pass tracking schemes. The whole colon is spatially subdivided into several cells, and only potentially visible cells are taken into account during rendering. To further improve rendering efficiency, potentially visible cells are rendered at different levels of detail. Additionally, a chain of bounding volume in each cell is used to avoid penetrating through the colon during navigation. In comparison with previous work, the proposed system can efficiently accomplish required preprocessing tasks and afford adequate rendering speeds on a low-cost PC system.

Chromosomal aberrations in nasopharyngeal carcinoma analyzed by comparative genomic hybridization

To investigate the genomic imbalances associated with nasopharyngeal carcinoma (NPC), we have performed chromosome analysis by comparative genomic hybridization (CGH) on 51 tumors, including 25 primary and 26 recurrent tumors. The most common copy number increases occurred on chromosome arms 12p (59%), 1q (47%), 17q (47%), 11q (41%), and 12q (35%). The minimal overlapping regions were at 12p12-13, 1q21-22, 17q21, 17q25, 11q13, and 12q13. The most frequent losses were from chromosome arms 3p (53%), 9p (41%), 13q (41%), 14q (35%), and 11q (29%). The minimal overlapping regions were at 3p12-14, 3p25-26, 9p21-23, 13q21-32, 14q12-21, and 11q14-23. Compared with the primary cancers, no additional chromosomal change was found in the recurrent tumors; however, the most frequent gain in the recurrent NPCs was at 11q13 (53%) instead of 12p in the primary tumors. An increase of gene alterations correlated with clinical stage. Our results provide a first comprehensive view of the genomic changes associated with NPC and reveal several new sites of genomic imbalance, indicating the possible involvement of novel oncogenes/tumor suppressor genes in the carcinogenesis of NPC.

HLA-DMA and HLA-DMB genotyping in patients with rheumatic diseases

To investigate the correlation of HLA-DMA and DMB alleles to some rheumatic diseases, HLA-DMA and DMB genes were detected in 11 patients with juvenile rheumatoid arthritis (JRA), 22 patients with psoriatic arthritis, 26 patients with Behcet's disease, 62 patients with ankylosing spondylitis (AS), and 138 unrelated healthy controls. There was no significant difference in phenotypic frequencies of HLA-DMA and DMB alleles between controls and patients with these rheumatic diseases. HLA-DMA and DMB genes are not related to the susceptibility of JRA, psoriatic arthritis, Behcet's disease, and AS.

The antiplatelet activity of Escherichia coli lipopolysaccharide is mediated through a nitric oxide/cyclic GMP pathway

In this study, Escherichia coli LPS dose-dependently (100-500 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human and rabbit platelets stimulated by agonists. LPS also dose-dependently inhibited the intracellular Ca2+ mobilization in human platelets stimulated by collagen. In addition, LPS (200 and 500 microg/ml) significantly increased the formation of cyclic GMP but not cyclic AMP in platelets. LPS (200 microg/ml) significantly increased the production of nitrate within a 10-min incubation period. Furthermore, LPS also dose-dependently inhibited platelet aggregation induced by PDBu (30 nmol/l), a protein kinase C activator. These results indicate that the antiplatelet activity of E. coli LPS may be involved in the activation of a nitric oxide/cyclic GMP pathway in platelets, resulting in inhibition of platelet aggregation. Therefore, LPS-mediated alteration of platelet function may contribute to bleeding diathesis in septicemic and endotoxemic patients.

Serotonin-6 receptor variant (C267T) and clinical response to clozapine

Clozapine is an effective atypical antipsychotic that has high affinity for serotonin type 6 receptors (5HT6). We tested the hypothesis that clinical response to clozapine in patients refractory to typical antipsychotic treatment is related to the genetic variant (C267T) of the 5HT6 receptors. Ninety-nine schizophrenic patients with a history of non-response to typical antipsychotics were included in the study. The results demonstrated a modest but significant relationship between presence of the variant of the 5HT6 receptors and the response to clozapine in these patients. Patients with homogenous 267T/T genotype had a better response than other patients. Although replication is required, these results suggest that the 5HT6 receptor C267T polymorphism may be involved in clozapine response, especially in patients with anxious or depressed symptoms.

Hepatitis C virus core protein interacts with cellular putative RNA helicase

The nucleocapsid core protein of hepatitis C virus (HCV) has been shown to trans-act on several viral or cellular promoters. To get insight into the trans-action mechanism of HCV core protein, a yeast two-hybrid cloning system was used for identification of core protein-interacting cellular protein. One such cDNA clone encoding the DEAD box family of putative RNA helicase was obtained. This cellular putative RNA helicase, designated CAP-Rf, exhibits more than 95% amino acid sequence identity to other known RNA helicases including human DBX and DBY, mouse mDEAD3, and PL10, a family of proteins generally involved in translation, splicing, development, or cell growth. In vitro binding or in vivo coimmunoprecipitation studies demonstrated the direct interaction of the full-length/matured form and C-terminally truncated variants of HCV core protein with this targeted protein. Additionally, the protein's interaction domains were delineated at the N-terminal 40-amino-acid segment of the HCV core protein and the C-terminal tail of CAP-Rf, which encompassed its RNA-binding and ATP hydrolysis domains. Immunoblotting or indirect immunofluorescence analysis revealed that the endogenous CAP-Rf was mainly localized in the nucleus and to a lesser extent in the cytoplasm, and when fused with FLAG tag, it colocalized with the HCV core protein either in the cytoplasm or in the nucleus. Similar to other RNA helicases, this cellular RNA helicase has nucleoside triphosphatase-deoxynucleoside triphosphatase activity, but this activity is inhibited by various forms of homopolynucleotides and enhanced by the HCV core protein. Moreover, transient expression of HCV core protein in human hepatoma HuH-7 cells significantly potentiated the trans-activation effect of FLAG-tagged CAP-Rf or untagged CAP-Rf on the luciferase reporter plasmid activity. All together, our results indicate that CAP-Rf is involved in regulation of gene expression and that HCV core protein promotes the trans-activation ability of CAP-Rf, likely via the complex formation and the modulation of the ATPase-dATPase activity of CAP-Rf. These findings provide evidence that HCV may have evolved a distinct mechanism in alteration of host cellular gene expression regulation via the interaction of its nucleocapsid core protein and cellular putative RNA helicase known to participate in all aspects of cellular processes involving RNA metabolism. This feature of core protein may impart pleiotropic effects on host cells, which may partially account for its role in HCV pathogenesis.

Lack of significant proximal esophageal acid reflux in infants presenting with respiratory symptoms

The effects of proximal esophageal acid reflux on upper and lower respiratory tract symptoms in infants with gastroesophageal reflux (GER) remain controversial. We studied 116 infants with either respiratory or gastrointestinal symptoms to determine whether acid reflux in the proximal esophagus plays an etiologic role in the elicitation of respiratory symptoms in comparison to causing gastrointestinal (GI) symptoms only. Sixty-two infants (age range, 1-12 months) with respiratory symptoms suggestive of GER and 54 infants with gastrointestinal symptoms only (age range, 1-10 months) were evaluated with dual level esophageal pH monitoring. Mean duration of dual-level pH monitoring in infants with respiratory symptoms was 20.4 h, and in those with GI symptoms was 20.7 h. Seventeen of 54 infants with GI symptoms only and 16 of 63 infants with respiratory symptoms had abnormal distal esophageal acid reflux indices (i.e., pH <4.0 for >5% of the duration of study). In infants with abnormal distal pH monitoring, the median proximal acid reflux index in the GI group was 4.0% in comparison to 0.95% in the respiratory group (P < 0.01 by Wilcoxon rank sum W test). Values for other reflux parameters were also higher in the GI than in the respiratory group. We conclude that reflux-associated respiratory symptoms are more likely due to mechanisms other than the mere presence of refluxed acid in the proximal esophagus.