HSP27 Modulates Neuropathic Pain by Inhibiting P2X3 Degradation

The role of heat shock protein 27 (HSP27), a chaperone, in neuropathic pain after nerve injury has not been systematically surveyed despite its neuroprotective and regeneration-promoting effects. In this study, we found that HSP27 expression in sensory neurons of the dorsal root ganglia (DRG) mediated nerve injury-induced neuropathic pain. Neuropathic pain behaviors were alleviated by silencing HSP27 in the DRG of a rat spinal nerve ligation (SNL) model. Local injection of an HSP27-overexpression construct into the DRG of naïve rats elicited neuropathic pain behaviors. HSP27 interacted with a purinergic receptor, P2X3, and their expression patterns corroborated the induction and reversal of neuropathic pain according to two lines of evidence: colocalization immunohistochemically and immunoprecipitation biochemically. In a cell model cotransfected with HSP27 and P2X3, the degradation rate of P2X3 was reduced in the presence of HSP27. Such an alteration was mediated by reducing P2X3 ubiquitination in SNL rats and was reversed after silencing HSP27 in the DRGs of SNL rats. In summary, the interaction of HSP27 with P2X3 provides a new mechanism of injury-induced neuropathic pain that could serve as an alternative therapeutic target.

Impact of modified teaching strategies used in a gross anatomy course on the academic performance of dental students during the COVID-19 pandemic

INTRODUCTION

Modified teaching strategies (MTS), asynchronous online teaching and smaller dissection groups, were applied to a gross anatomy course for dental students in the National Taiwan University in April 2020 in response to the COVID-19 pandemic. This study aimed to investigate the effects and perceptions of MTS on dental students.

MATERIALS AND METHODS

Scores for anatomy examinations for 2018-2019 (without MTS) and 2019-2020 (with MTS) cohorts were compared to explore the effect on academic performance. Moreover, questionnaire from the 2019-2020 cohort was analysed to determine dental students' perceptions about MTS.

RESULTS

The lecture performance in the final examination of the second semester for the 2019-2020 cohort was significantly higher than that of the first semester (pre-COVID-19) and that for the 2018-2019 cohort. However, the laboratory performance in the midterm examination of the second semester for the 2019-2020 cohort was significantly lower than that for the 2018-2019 cohort and showed no difference in the final examination of the first semester. The questionnaires revealed that the majority of students displayed positive attitudes towards MTS and agreed with the importance of peer discussion during laboratory dissection.

CONCLUSIONS

Asynchronous online learning for anatomy lecture may be beneficial for dental students; however, a smaller dissection group accompanied by reduced peer discussion may temporarily exert negative effects on their laboratory performance at the beginning of the application. Furthermore, more dental students exhibited positive perceptions towards smaller dissection groups. These findings could illuminate the learning condition of dental students in anatomy education.

Benefits of a bilingual web-based anatomy atlas for nursing students in learning anatomy

BACKGROUND

Registered nurses are required for high-quality healthcare. Thus, the anatomy course is essential regarding professional knowledge of the human body during the nursing training process. However, previous studies have indicated that anatomy teaching time and anatomy teachers were reduced and insufficient. Therefore, to improve the learning of practical anatomy in response to these difficulties, a bilingual National Taiwan University web-based anatomy atlas (NTU-WAA) was created as a cross-platform application and its feasibility was evaluated.

METHODS

The comparison of anatomy examination scores between nursing students of two cohorts (66 from the 2018-2019 cohort, whom was without NTU-WAA application; 54 from the 2019-2020 cohort, to whom NTU-WAA was offered) and the evaluation of questionnaires collected from nursing students of the 2019-2020 cohort and 4 anatomy teachers were carried out to define the feasibility of this strategy.

RESULTS

Results obtained by nursing students for the 2019-2020 cohort showed a significant increase in anatomy learning performance compared with that of the 2018-2019 cohort with reference to the laboratory midterm [2018-2019 cohort vs. 2019-2020 cohort, mean (standard deviation, SD): 77.20 (16.14) vs. 81.80 (12.03); p = 0.043], the laboratory final examination [59.68 (15.28) vs. 80.35 (13.74); p < 0.001] and the theory final examination [80.85 (10.10) vs. 84.33 (6.925); p = 0.017]. Moreover, results of the questionnaires indicated that the new bilingual cross-platform atlas was highly accepted by students and teachers.

CONCLUSIONS

The NTU-WAA, a bilingual web-based atlas, was evaluated as a beneficial anatomy-learning tool that may enhance self-study of nursing students with consequent amelioration of their anatomy-related performance in both theoretical and laboratory examinations. This reflection suggests the future implementation of the bilingual web-based atlas on a large scale.

Nonpermissive skin environment impairs nerve regeneration in diabetes via Sec31a

OBJECTIVE

Although the microenvironment for peripheral nerve regeneration is permissive, such a mechanism is defective in diabetes, and the molecular mediators remain elusive. This study aimed to (1) investigate the relationship between skin innervation and collagen pathology in diabetic neuropathy and to (2) clarify the molecular alterations that occur in response to hyperglycemia and their effects on axon regeneration.

METHODS

We addressed this issue using two complementary systems: (1) human skin from patients with diabetic neuropathy and to (2) a coculture model of human dermal fibroblasts (HDFs) with rat dorsal root ganglia neurons in the context of intrinsic neuronal factor and extrinsic microenvironmental collagen and its biosynthetic pathways.

RESULTS

In diabetic neuropathy, the skin innervation of intraepidermal nerve fiber density (IENFd), a measure of sensory nerve degeneration, was reduced with similar expression of a growth associated protein 43, a marker of nerve regeneration. In contrast, the content and packing of collagen in the diabetic skin became more rigid than the control skin. Sec31a, a protein that regulates the collagen biosynthetic pathway, was upregulated and inversely correlated with IENFd. In the cell model, activated HDFs exposed to high-glucose medium enhanced the expression of Sec31a and collagen I through the activation of transforming growth factor β, a profibrotic molecule. Sec31a upregulation impaired neurite outgrowth. This effect was reversed by silencing Sec31a expression and neurite outgrowth was resumed.

INTERPRETATION

The current study provides evidence that Sec31a plays a key role in inhibiting nerve regeneration in diabetic neuropathy. This article is protected by copyright. All rights reserved.

Overall and Cause-Specific Mortality in Patients With Type 1 Diabetes Mellitus: A Population-Based Cohort Study in Taiwan From 1998 Through 2014

Background

To investigate all-cause and cause-specific mortality in Taiwanese patients with type 1 diabetes.

Methods

A cohort of 17,203 patients with type 1 diabetes were identified from Taiwan’s National Health Insurance claims in the period of 1998–2014. Person-years were accumulated for each individual from date of type 1 diabetes registration to date of death or the last day of 2014. Age, sex, and calendar year standardized mortality ratios (SMRs) were calculated with reference to the general population.

Results

In up to 17 years of follow-up, 4,916 patients died from 182,523 person-years. Diabetes (30.15%), cancer (20.48%), circulatory diseases (13.14%), and renal diseases (11.45%) were the leading underlying causes of death. Mortality rate (26.93 per 1,000 person-years) from type 1 diabetes in Taiwan was high, the cause of death with the highest mortality rate was diabetes (8.12 per 1,000 person-years), followed by cancer (5.52 per 1,000 person-years), and circulatory diseases (3.54 per 1,000 person-years). The all-cause SMR was significantly elevated at 4.16 (95% confidence interval, 4.04–4.28), with a greater all-cause SMR noted in females than in males (4.62 vs 3.79). The cause-specific SMR was highly elevated for diabetes (SMR, 16.45), followed by renal disease (SMR, 14.48), chronic hepatitis and liver cirrhosis (SMR, 4.91) and infection (SMR, 4.59). All-cause SMRs were also significantly increased for all ages, with the greatest figure noted for 15–24 years (SMR, 8.46).

Conclusions

Type 1 diabetes in both genders and all ages was associated with significantly elevated SMRs for all-cause and mostly for diabetes per se and renal disease.

Effect of precursor type on the reduction of concentrated nitrate using zero-valent copper and sodium borohydride

In this study, we demonstrated that the choice of precursor has a strong effect on the reduction of nitrate (NO₃^-) using zero-valent copper (Cu⁰) synthesized by sodium borohydride (NaBH₄). Different precursors: CuSO₄, CuO, Cu₂O, Cu powder, and Cu mesh were used to reduce NO₃^- at 677 mg-N/L under the reducing conditions of NaBH₄. Compared with the prehydrolyzed samples, those prepared without prehydrolysis exhibited lower reduction rates, longer times and higher concentrations of nitrite (NO₂^-) intermediate. It was found that one-time addition of NaBH₄ resulted in higher reduction rate and less NO₂^- intermediate than two-step addition. Results showed that Cu⁰ from CuSO₄ possessed the smallest particle size (890.9 nm), highest surface area (26.0 m²/g), and highest reaction rate (0.166 min^-1). Values of pseudo-first-order constant (k_obs) were in the order: CuSO₄ > CuO > Cu₂O > Cu powder >Cu mesh. However, values of surface area-normalized reaction rate (k_SA) were approximately equal. It was proposed that NO₃^- was reduced to NO₂^- on Cu⁰, and then converted to NH₄⁺ and N₂, respectively; H₂ generated from both NaBH₄ hydration and Cu (II) reduction contributed to NO₃^- reduction as well.

Prevalence of hand syndromes among patients with diabetes mellitus in Taiwan: A population-based study

BACKGROUND

Population-based data for diabetic hand syndrome (DHS) are limited. The aim of the present epidemiological study was to estimate the overall and cause-specific prevalence and rate ratio (RR) of DHS in patients with diabetes.

METHODS

The present study was a cross-sectional study based on a random sample of 57 093 diabetics and matched controls, both identified from Taiwan National Health Insurance claims in 2010. The DHS analyzed in the present study included carpal tunnel syndrome (CTS), stenosing flexor tenosynovitis (SFT), limited joint mobility (LJM), and Dupuytren's disease (DD).

RESULTS

The prevalence of overall DHS was estimated at 2472 per 10⁵ for the diabetics, compared with 1641 per 10⁵ for the controls, representing a prevalence RR of 1.51 (95 % confidence interval [CI] 1.39-1.64). Stratified analyses further revealed that the significantly increased prevalence of overall DHS was more evident in females than males (1.59 vs 1.36) and was only noted in diabetics aged ≥35 years. Cause-specific analysis suggested that patients with diabetes had the highest prevalence of CTS (1244 per 10⁵ ), followed by SFT (1209 per 10⁵ ), LJM (39 per 10⁵ ), and DD (6 per 10⁵ ). In addition, diabetes was only significantly associated with CTS (RR 1.34; 95 % CI 1.20-1.51) and SFT (1.74; 95 % CI 1.54-1.97).

CONCLUSION

The prevalence of overall and certain cause-specific DHS was significantly elevated in patients with diabetes in Taiwan.

Effective gene expression in the rat dorsal root ganglia with a non-viral vector delivered via spinal nerve injection

Delivering gene constructs into the dorsal root ganglia (DRG) is a powerful but challenging therapeutic strategy for sensory disorders affecting the DRG and their peripheral processes. The current delivery methods of direct intra-DRG injection and intrathecal injection have several disadvantages, including potential injury to DRG neurons and low transfection efficiency, respectively. This study aimed to develop a spinal nerve injection strategy to deliver polyethylenimine mixed with plasmid (PEI/DNA polyplexes) containing green fluorescent protein (GFP). Using this spinal nerve injection approach, PEI/DNA polyplexes were delivered to DRG neurons without nerve injury. Within one week of the delivery, GFP expression was detected in 82.8% ± 1.70% of DRG neurons, comparable to the levels obtained by intra-DRG injection (81.3% ± 5.1%, p = 0.82) but much higher than those obtained by intrathecal injection. The degree of GFP expression by neurofilament(+) and peripherin(+) DRG neurons was similar. The safety of this approach was documented by the absence of injury marker expression, including activation transcription factor 3 and ionized calcium binding adaptor molecule 1 for neurons and glia, respectively, as well as the absence of behavioral changes. These results demonstrated the efficacy and safety of delivering PEI/DNA polyplexes to DRG neurons via spinal nerve injection.

Reduction of concentrated nitrate by using in situ synthesized zero-valent copper

Although zero-valent iron represents a promising approach for reduction of nitrate (NO(3)(-)) in water, its application in concentrated nitrate is limited by surface passivation. In this study, an alternative approach using in situ synthesized zero-valent copper (Cu(0)) produced by borohydride (NaBH(4)) was investigated. Complete reduction was observed within 55 min by reacting 677 mg-N/L of NO(3)(-) with CuO (0.312 g/L) and NaBH(4) (4.16 g/L) at 60 °C. The pseudo-first-order rate constant was 0.059 min(-1), and it increased threefold when the CuO dose was increased to 1.24 g/L. Increasing the NaBH(4) dose produced less nitrite (NO(2)(-)) throughout the experiments, indicating that it is the primary agent for reducing NO(2)(-). The initial pH exerted a significant effect on the reaction rate, and NO(3)(-) was rapidly reduced when the initial pH was less than 4. Based on the research findings, possible reaction pathways for NO(3)(-) reduction by Cu(0) are proposed in this work.

Occupational exposure of dentists to extremely-low-frequency magnetic field

OBJECTIVE

To compare occupational exposure to extremely-low-frequency magnetic field (ELF-MF) between dentists practicing in dental clinics and those employed in hospitals.

METHODS

Thirty-two dentists who worked at clinics (n=15) and 33 dentists employed at hospital dental departments (n=7) voluntarily provided their informed consent to participate in this measurement study. The study dentists were requested to wear an ELF-MF dosimeter for some 3 h at work to determine their personal exposure. Spot measurements taken at a number of locations in each dental office were used to indicate the work environment exposure level. Additionally, ELF-MF emitted from common dental equipment was also measured. All measurements were performed with EMDEX Lite meters.

RESULTS

The average environmental exposure to ELF-MF is higher in clinic dental offices than in hospital dental departments (0.55 vs. 0.15 µT, p=0.008). Personal dosimetry showed that on average, clinic dentists spent 35.71 and 19.39% of their time at exposures above 0.3 and 0.4 µT at work, respectively. The corresponding figures for hospital dentists were 19.61 and 13.92%. Additionally, ELF-MF was greater than 0.4 µT at 30 cm from all selected equipment, but the ELF-MF generally diminished as the distance from dental equipment increased. Uultraviolet air sterilization system produced 3 times as much ELF-MF as other dental equipment.

CONCLUSIONS

This study suggests the possibility of over-exposure of dentists to power frequency ELF-MF. Additionally, certain dental equipment may produce ELF-MF levels greater than 0.4 µT in areas where dentists usually work when treating patients.

Protein profilings in mouse liver regeneration after partial hepatectomy using iTRAQ technology

Liver is unique in its capability to regenerate after an injury. Liver regeneration after a 2/3 partial hepatectomy served as a classical model and is adopted frequently to study the mechanism of liver regeneration. In the present study, semiquantitative analysis of protein expression in mouse liver regeneration following partial hepatectomy was performed using an iTRAQ technique. Proteins from pre-PHx control livers and livers regenerating for 24, 48 and 72 h were extracted and inspected using 4-plex isotope labeling, followed by liquid chromatography fractionation, mass spectrometry and statistical differential analysis. A total of 827 proteins were identified in this study. There were 270 proteins for which quantitative information was available at all the time points in both biologically duplicate experiments. Among the 270 proteins, Car3, Mif, Adh1, Lactb2, Fabp5, Es31, Acaa1b and LOC100044783 were consistently down-regulated, and Mat1a, Dnpep, Pabpc1, Apoa4, Oat, Hpx, Hp and Mt1 were up-regulated by a factor of at least 1.5 from that of the controls at one time point or more. The regulation of each differential protein was also demonstrated by monitoring its time-dependent expression changes during the regenerating process. We believe this is the first report to profile the protein changes in liver regeneration utilizing the iTRAQ proteomic technique.

Signaling pathways of magnolol-induced adrenal steroidogensis

This study focused on identifying the signalling mediating the effect of magnolol on corticosterone production. Magnolol-induced corticosterone production was completely inhibited by mitogen-activated protein kinase kinase (MEK)-inhibitor PD98059, tyrosine kinase (TK)-inhibitor genistein or Janus tyrosine kinase 2 (JAK2)-inhibitor AG490, suggesting that extracellular signal-regulated kinase (ERK) and JAK2 are both involved in this signaling cascade. Further, magnolol induced the transient phosphorylation of MEK, ERK, cAMP response-element binding protein (CREB) and the expression of 32 and 30 kDa steroidogenic acute regulatory protein (StAR) in a time-dependent manner. Inhibition of TK or JAK2 activities blocked magnolol-induced phosphorylation of MEK and ERK, again supporting the upstream role of JAK2. The activation of JAK2 or MEK apparently mediated the magnolol-induced phosphorylation of CREB and the upregulation of StAR. These findings demonstrate a novel pathway for magnolol to induce the expression of StAR, which regulates the rate-limiting step in sterodiogenesis.

Magnolol induces the distributional changes of p160 and adipose differentiation-related protein in adrenal cells

Magnolol stimulates adrenal steroidogenesis and induces the distributional changes of p160 and adipose differentiation-related protein (ADRP) in rat adrenal cells. This study investigated the underlying signaling mechanisms involved in these processes. Magnolol (30 microM) caused a time-dependent increase in the phosphorylation of extracellular signal-related kinase (ERK) in cultured adrenal cells. The following evidence supports a link between ERK activation and p160 translocation. First, the magnolol-induced redistribution of p160 from the lipid droplet surface to the cytosol, resulting in the decrease in the percentages of p160-positive cells, and this decrease in p160-positive cells was completely blocked by pretreatment with either of the MAPK-ERK kinase (MEK) inhibitors PD98059 or U0126. Second, magnolol did not significantly decrease total p160 protein levels but caused an increase in threonine phosphorylation of p160, which reached a maximum after 5 min of magnolol treatment, and this magnolol-induced phosphorylation of p160 was prevented by pretreatment with U0126, suggesting the involvement of ERK. In addition, magnolol decreased both ADRP immunostaining intensity at the lipid droplet surface and the percentage of ADRP-positive cells. This was further confirmed biochemically by the decrease in ADRP levels in total cell homogenates and in lipid droplet fractions. Magnolol-induced decrease in ADRP staining at the lipid droplet surface was not affected by pretreatment with PD98059 or U0126, indicating that ERK signaling was not involved in this event. Furthermore, treatment with 30 microM magnolol for 6 h resulted in about 50% decrease in ADRP protein level. Therefore, decreased protein levels of p160 and ADRP at the lipid droplet surface induced by magnolol were mediated via two different mechanisms: phosphorylation of p160 and downregulation of ADRP expression, respectively.

A novel chromosome region maintenance 1-independent nuclear export signal of the large form of hepatitis delta antigen that is required for the viral assembly

Hepatitis delta virus (HDV) is a satellite virus of hepatitis B virus, as it requires hepatitis B virus for virion production and transmission. We have previously demonstrated that sequences within the C-terminal 19-amino acid domain flanking the isoprenylation motif of the large hepatitis delta antigen (HDAg-L) are important for virion assembly. In this study, site-directed mutagenesis and immunofluorescence staining demonstrated that in the absence of hepatitis B virus surface antigen (HBsAg), the wild-type HDAg-L was localized in the nuclei of transfected COS7 cells. Nevertheless, in the presence of HBsAg, the HDAg-L became both nuclei- and cytoplasm-distributed in about half of the cells. An HDAg-L mutant with a substitution of Pro-205 to alanine could neither form HDV-like particles nor shift the subcellular localization in the presence of HBsAg. In addition, nuclear trafficking of HDAg-L in heterokaryons indicated that HDAg-L is a nucleocytoplasmic shuttling protein. A proline-rich HDAg peptide spanning amino acid residues 198 to 210, designated NES(HDAg-L), can function as a nuclear export signal (NES) in Xenopus oocytes. Pro-205 is critical for the NES function. Furthermore, assembly of HDV is insensitive to leptomycin B, indicating that the NES(HDAg-L) directs nuclear export of HDAg-L to the cytoplasm via a chromosome region maintenance 1-independent pathway.

Roles of the AX(4)GKS and arginine-rich motifs of hepatitis C virus RNA helicase in ATP- and viral RNA-binding activity

The nonstructural protein 3 (NS3) of hepatitis C virus (HCV) possesses protease, nucleoside triphosphatase, and helicase activities. Although the enzymatic activities have been extensively studied, the ATP- and RNA-binding domains of the NS3 helicase are not well-characterized. In this study, NS3 proteins with point mutations in the conserved helicase motifs were expressed in Escherichia coli, purified, and analyzed for their effects on ATP binding, RNA binding, ATP hydrolysis, and RNA unwinding. UV cross-linking experiments indicate that the lysine residue in the AX(4)GKS motif is directly involved in ATP binding, whereas the NS3(GR1490DT) mutant in which the arginine-rich motif (1486-QRRGRTGR-1493) was changed to QRRDTTGR bound ATP as well as the wild type. The binding activity of HCV NS3 helicase to the viral RNA was drastically reduced with the mutation at Arg1488 (R1488A) and was also affected by the K1236E substitution in the AX(4)GKS motif and the R1490A and GR1490DT mutations in the arginine-rich motif. Previously, Arg1490 was suggested, based on the crystal structure of an NS3-deoxyuridine octamer complex, to directly interact with the gamma-phosphate group of ATP. Nevertheless, our functional analysis demonstrated the critical roles of Arg1490 in binding to the viral RNA, ATP hydrolysis, and RNA unwinding, but not in ATP binding.

Color Doppler vascularity index can predict distant metastasis and survival in colon cancer patients

The purpose of this study was to investigate the clinical usefulness of the color Doppler vascularity index (CDVI) in patients with colon cancer before surgery. Forty-four patients with sonographically visible tumor mass of colon cancer were investigated. The CDVI of each tumor was determined using transabdominal color Doppler ultrasound. The CDVI was defined as the ratio of the number of the colored pixels within a tumor section to the number of total pixels in that specific tumor section and was calculated by using Encomate software (Electronic Business Machine Co. Ltd., Taipei, Taiwan). The correlation between the CDVI and clinicopathological factors, mode of recurrence, and patient survival was studied. For comparison, microvessel density (the mean number of microvessels in three areas of highest vascular density at x200 magnification) of the tumors of these 44 patients was also evaluated by using immunohistochemical staining of surgical specimens with anti-CD34. The microvessel density was not correlated with Dukes' classification, clinicopathological factors, and survival. The CDVI was significantly higher in the patients with lymph node metastases and vascular invasion than in those without such metastases and invasion (P = 0.006 and P = 0.0098, respectively). Moreover, in patients with a high CDVI (> 15%) and positive vascular invasion, survival was significantly poorer than in those with low CDVI (< or = 15%) and negative invasion (P = 0.0037 and 0.0039, respectively). Multivariate analysis indicated that liver metastasis, vascular invasion, and CDVI are independent prognostic factors in the patients with colon cancer. According to the mode of recurrence in 36 patients who underwent curative resection, the frequency of the distant organ recurrence was significantly higher in the high CDVI group (40%) than in the low CDVI group (0%). The CDVI is a good preoperative indicator of recurrence and patient survival in colon cancer. Thus, the CDVI may be helpful in stratifying patients for adjuvant therapy.

Specific interaction between the hepatitis delta virus RNA and glyceraldehyde 3-phosphate dehydrogenase: an enhancement on ribozyme catalysis

Replication of hepatitis delta virus (HDV) RNA occurs in the nuclei of infected cells. The replication is mediated by cellular factors containing an RNA polymerase II-like enzyme activity through a double rolling-circle mechanism and is regulated by delta antigens. In this study, UV cross-linking experiments were carried out to examine interactions between HDV RNA and proteins present in HeLa nuclear extract. Cellular proteins with molecular mass of 23 (p23), 36 (p36), 38 (p38), and 58 (p58) kDa bound to full-length HDV RNA of both genomic and antigenomic strands. Deletion analysis on the antigenomic strand mapped the interacting domain within a 79-nucleotide fragment but not at the ends of the rod-shaped viral RNA structure. The specificity of the RNA-protein interactions was demonstrated by competition experiments and the specific HDV RNA-binding proteins were purified through column chromatography. Electrophoresis mobility shift assay with the purified fractions demonstrated that the interaction between p36 and HDV RNA was relatively stable even in the presence of 0.5 M NaCl. Biochemical analysis including protein microsequencing identified the p36 as glyceraldehyde 3-phosphate dehydrogenase (GAPDH). RNase footprinting indicated that the UC-rich domain between nucleotides 379 and 414 of the HDV antigenomic RNA was involved in the GAPDH binding. Functional studies further demonstrated an enhancing effect of GAPDH on the ribozyme activity of HDV antigenomic RNA. In addition, in the presence of HDV RNA cellular GAPDH relocalized from the cytoplasm to the nucleus where HDV replication occurs. These results suggest that GAPDH is involved in the replication of HDV.

A 12-amino acid stretch in the hypervariable region of the spike protein S1 subunit is critical for cell fusion activity of mouse hepatitis virus

The spike (S) glycoprotein of mouse hepatitis virus (MHV) plays a major role in the viral pathogenesis. It is often processed into the N-terminal S1 and the C-terminal S2 subunits that were evidently important for binding to cell receptor and inducing cell-cell fusion, respectively. As a consequence of cell-cell fusion, most of the naturally occurring infections of MHV are associated with syncytia formation. So far, only MHV-2 was identified to be fusion-negative. In this study, the S gene of MHV-2 was molecularly cloned, and the nucleotide sequence was determined. The MHV-2 S protein lacks a 12-amino acid stretch in the S1 hypervariable region from amino acid residue 446 to 457 when compared with the fusion-positive strain MHV-JHM. In addition, there are three amino acid substitutions in the S2 subunit, Tyr-1144 to Asp, Glu-1165 to Asp, and Arg-1209 to Lys. The cloned MHV-2 S protein exhibited the fusion-negative property in DBT cells as the intrinsic viral protein. Furthermore, similar to the fusion-positive MHV-JHM strain, proteolytic cleavage activity was detected both in DBT cells infected with the fusion-negative MHV-2 and in the transfected cells that expressed the cloned MHV-2 S protein. Domain swapping experiments demonstrated that the 12-amino acid stretch missing in the MHV-2 S1 subunit, but not the proteolytic cleavage site, was critical for the cell-fusion activity of MHV.

Specific interaction between the hepatitis C virus NS5B RNA polymerase and the 3' end of the viral RNA

Hepatitis C virus (HCV) NS5B protein is the viral RNA-dependent RNA polymerase capable of directing RNA synthesis. In this study, an electrophoretic mobility shift assay demonstrated the interaction between a partially purified recombinant NS5B protein and a 3' viral genomic RNA with or without the conserved 98-nucleotide tail. The NS5B-RNA complexes were specifically competed away by the unlabeled homologous RNA but not by the viral 5' noncoding region and very poorly by the 3' conserved 98-nucleotide tail. A 3' coding region with conserved stem-loop structures rather than the 3' noncoding region of the HCV genome is critical for the specific binding of NS5B. Nevertheless, no direct interaction between the 3' coding region and the HCV NS5A protein was detected. Furthermore, two independent RNA-binding domains (RBDs) of NS5B were identified, RBD1, from amino acid residues 83 to 194, and RBD2, from residues 196 to 298. Interestingly, the conserved motifs of RNA-dependent RNA polymerase for putative RNA binding (220-DxxxxD-225) and template/primer position (282-S/TGxxxTxxxNS/T-292) are present in the RBD2. Nevertheless, the RNA-binding activity of RBD2 was abolished when it was linked to the carboxy-terminal half of the NS5B. These results provide some clues to understanding the initiation of HCV replication.

The nucleolin binding activity of hepatitis delta antigen is associated with nucleolus targeting

Hepatitis delta antigens (HDAgs) are important for the replication and assembly of hepatitis delta virus (HDV). To understand the association between HDAgs and cellular proteins and the mechanism of viral multiplication, we have studied the interaction between HDAgs and nucleolin, a major nucleolar phosphoprotein. The interaction between HDAgs and nucleolin was first demonstrated by immunofluorescence staining studies. HDAgs and endogenous nucleolin were colocalized in the nucleoli of cultured cells transfected with plasmids encoding the small and large HDAg. Coimmunoprecipitation results indicated that the NH2-terminal domain of HDAg was essential for its binding to nucleolin. In vitro ligand binding assays revealed two nucleolin binding sites, NBS1 and NBS2. Each spanned amino acid residues 35-50 and 51-65, respectively, with a conserved core sequence K(K/R)XK. HDV replication was modulated by exogenous human nucleolin. In addition, a small HDAg mutant S-d65/75, which possesses both NBS1 and NBS2, was capable of transactivating HDV replication, whereas the small HDAg mutant S-d50/75, which retained NBS1 but not NBS2, was unable to support the replication of HDV. Thus, the nucleolin binding activity of HDAg is critical for its nucleolar targeting and is involved in the modulation of HDV replication.

Prognostic factors in patients with bulky stage IB or IIA cervical carcinoma undergoing neoadjuvant chemotherapy and radical hysterectomy

All patients with bulky (> or =4 cm) Stage Ib or IIa cervical carcinoma treated at Chang Gung Memorial Hospital between August 1988 and December 1991 using a strategy of neoadjuvant chemotherapy with cisplatin, vincristine, and bleomycin and radical hysterectomy were reviewed. Fifty-nine evaluable patients received 1 to 3 courses of chemotherapy, and 51 underwent subsequent hysterectomy. The remaining 8 patients, not completing planned surgery, were treated with definitive radiotherapy. The overall clinical response rate was 81.4% (48/59) with 18.6% complete response. Clinical response to chemotherapy was not different by stage, histologic type, tumor size, level of squamous cell carcinoma antigen, or DNA ploidy. However, tumors with DNA indices (DI) greater than 1.3 were associated with higher clinical response rates than tumors with DI < or = 1.3 (P = 0.043). Histologically proven pelvic node metastases was noted in 18.5% (10/54) who had laparotomy. Concomitant pregnancy and more than one node metastases had significant adverse influence on recurrence and death. The 5-year survival rate of those patients who received hysterectomy was 80.3%, while only 1 of the 8 patients without hysterectomy survived. Of the 7 patients received hysterectomy despite clinical poor response, only 2 had node metastases and 3 died, whereas all the 4 patients deterred hysterectomy for poor response died. This study demonstrates the value of DNA flow cytometry in predicting chemosensitivity. However, with a DI cutoff at 1.3, only 29.2% patients could be selected. Further studies are necessary to find additional indicators that predict histological response to select better candidates for this approach and to determine optimal adjunctive treatment in case that poor prognostic features are found.

Role of the electrostatic attractive force in the adsorption of proteins by aluminum hydroxide adjuvant

The fact that both aluminum hydroxide adjuvant and proteins have a pH dependent surface charge means that electrostatic forces play a role in the adsorption of proteins by aluminum hydroxide adjuvant during the preparation of vaccines. The objective of this study was to examine the contribution of the electrostatic attractive force in the adsorption of proteins by aluminum hydroxide adjuvant. Since the surface charge characteristics of aluminum hydroxide adjuvant can be modified by the adsorption of phosphate anion, a series of aluminum hydroxide adjuvants were prepared by treatment with various concentrations of phosphate anion. The isoelectric points (iep) of these adjuvants ranged from 11.0 to 4.6 and the electrophoretic mobilities at pH 7.4 ranged from 2.0 to -3.3 microns cm/V s. The line broadening of the (020) band of the X-ray diffraction pattern indicated that treatment with phosphate anion did not change the primary crystallite dimension. Adsorption at pH 7.4 of positively charged lysozyme (iep = 11.1) was directly related to the negative surface charge of the adjuvant. No adsorption occurred when the surface charge was positive. In contrast, negatively charged ovalbumin (iep = 4.6) was adsorbed by all of the adjuvants at pH 7.4, although the adsorptive capacity was the greatest when the surface charge was positive. The results indicate that adsorptive forces in addition to the electrostatic attractive force play an important role in the adsorption of some proteins by aluminum hydroxide adjuvant. It is believed the structurally flexible proteins, like ovalbumin, exhibit more complex adsorption behavior than structurally rigid proteins, like lysozyme, for which adsorptive behavior can be explained by electrostatic forces.

Breast cancer vascularity: color Doppler sonography and histopathology study

In this prospective study, the authors examined 50 patients with breast tumors (malignant, n = 32; benign, n = 18) to investigate the correlation between color Doppler flow mapping and histopathological findings and to evaluate the clinical significance of color Doppler mapping. Among the 32 patients with breast cancer, color Doppler signals were detected in 24 patients (75%). The maximum flow velocities varied from 5 to 34 cm/sec, with 16 (67%) of them above 15 cm/sec. Among the 18 patients with benign tumors, color Doppler signals could be detected in 7 (39%). The maximum flow velocity varied from 3 to 30 cm/sec but was over 15 cm/sec in only two patients (28%). Histological studies revealed that color Doppler signals detected by Doppler sonography correlated with disordered neovascularization penetrating the lesion from its periphery, consisting of thin-walled blood vessels and large arteriovenous shunts. Although large tumors tend to have high Doppler flow, there is no significant correlation between the maximum flow velocity and tumor size. There is also no significant correlation between the detection of high flow color Doppler signals and the age, receptor status, tumor size, lymph node metastases, or clinical stage of patients with breast cancer. However, there is a positive association (p < 0.05) between nodal metastases and higher tumor flow velocity in T1 (< or = 2 cm) breast tumors, but not in larger tumors. It is concluded that color Doppler is useful in the assessment of tumor vascularity but is of limited value in the differentiation of benign from malignant lesions. However, the presence of color Doppler signals in T1 breast cancer suggesting early dissemination of the cancer might be of important clinical significance in detecting those small, apparently early, but aggressive tumors with poor prognosis.

Rifabutin as salvage therapy for cases of chronic multidrug-resistant pulmonary tuberculosis in Taiwan

This study was aimed at assessing the efficacy and tolerability of rifabutin for the re-treatment of cases of chronic, multidrug-resistant pulmonary tuberculosis. The study design was self-controlled, single center. Rifabutin was administered as part of an individual-tailored multidrug regimen. In-patients suffering from pulmonary tuberculosis, infected with Mycobacterium tuberculosis bacilli resistant to isoniazid, rifampicin and other drugs with progressive disease unresponsive to prior courses with standard anti-tuberculosis medications were treated. Overall, 43 patients were enrolled and treated with rifabutin at 300 or 450mg/day according to body weight in conjunction with available anti-tuberculous drugs for a mean time of 353 days (range 42-678). Of these, 36 met all eligibility criteria (i.e. positive baseline culture of sputum with bacilli resistant to rifampicin at least) and were retained for the analysis of efficacy. Seventeen patients (47%) achieved a sustained conversion to a negative culture of sputum in a mean time of 47.7 days with a range of 14-120 days. Treatment prevented deterioration in most patients and resulted in clinical and radiological cure or marked improvement in more than half of cases. No correlation was found between treatment outcome and use of medication concomitant to rifabutin or susceptibility of bacilli to the drugs used. Four deaths occurred due to disease progression, in no case being related to study drugs. Ten patients reported a total of 18 adverse events that led to treatment discontinuation in 5 cases. Rifabutin should be considered for inclusion in regimens for cases of pulmonary multidrug-resistant tuberculosis which fail to respond to previous therapy.

Automated analytical systems for drug development studies. Part IV. A microdialysis system to study the partitioning of lomefloxacin across an erythrocyte membrane in vitro

An automated system utilizing microdialysis sampling, intermittent dosing, and liquid chromatographic analysis was assembled in order to study the partitioning of lomefloxacin, a fluoroquinolone antimicrobial, into human erythrocytes in vitro. The apparent erythrocyte:buffer partition coefficient was found to be approximately 2.0 with this system and by a manual method. The value was concentration-dependent; lower partition coefficients were observed at lomefloxacin concentrations less than 1 microgram ml-1. At all concentrations, values obtained by microdialysis were statistically indistinguishable from those obtained by a conventional manual method. The results indicate that erythrocyte partition coefficients can be measured successfully with the microdialysis system. Furthermore, microdialysis sampling eliminates the tedious methodology associated with traditional erythrocyte partitioning studies, including sample clean-up. Due to automated intermittent dosing and on-line LC analysis, the system operates unattended.

Cellular proteins specifically bind to the 5'-noncoding region of hepatitis C virus RNA

Hepatitis C virus (HCV) RNA contains a highly conserved 5'-noncoding region (5'NCR) which may be important in viral multiplication. To study the possible mechanisms of the cellular proteins involved in HCV replication and pathogenesis, a gel mobility shift assay and competition analysis were performed with the HCV 5'NCR. Two specific complexes were formed between the 341-nucleotide RNA of the HCV 5'NCR and proteins of mammalian cells. The specific RNA-protein complexes were maintained in the region of the 5'NCR from nucleotides 131 to 253. Nevertheless, the slower migrating RNA-protein complex failed to form when a polypyrimidine tract sequence (191-UCCUUUCUU-199) in the stem-loop III structure of HCV 5'NCR was changed to 191-UCCUUUggU-199. A uv cross-linking assay further identified two cellular proteins, p87 and p120, that specifically bound to the stem-loop III structure. Mutations at the polypyrimidine tract sequence inhibited the binding of p87, but maintained the ability of the mutant HCV RNA to interact with p120. Translation competition assay demonstrated that the 5'NCR from nt 131 to 253 within the stem-loop III structure is important for the translation of HCV core protein. In addition, p120 and unidentified cellular proteins are likely to be involved in the translation of HCV polyprotein, whereas p87 may play important roles in HCV multiplication other than translation.

Functional domains of delta antigens and viral RNA required for RNA packaging of hepatitis delta virus

The functions of delta antigens (HDAgs) in the morphogenesis of hepatitis delta virus (HDV) have been studied previously. The C terminus of large HDAg has been shown to complex with the small surface antigen (HBsAg) of helper hepatitis B virus, whereas the assembly of small HDAg requires interaction with the N terminus of large HDAg (M.-F. Chang, C.-J. Chen, and S. C. Chang, J. Virol. 68:646-653, 1994). To further examine the molecular mechanisms by which HDAgs are involved in the assembly of HDV RNA, we have cotransfected Huh-7 cells with plasmids representing a longer than unit-length HDV and the small HBsAg cDNAs. We found that HDAg mRNA could be generated from an endogenous promoter within the HDV cDNA that was translated into large HDAg. Large HDAg is capable of complexing with monomeric HDV genomic RNA to form ribonucleoprotein particles (RNPs) and is capable of forming enveloped HDV-like particles in the presence of small HBsAg without undergoing HDV replication. In addition, the middle region from amino acid residues 89 to 145 of large HDAg is required for assembly of the RNPs but is dispensable for assembly of the enveloped particles. RNA assembly is also demonstrated with small HDAg when it is cotransfected with a packaging-defective large HDAg mutant and small HBsAg. Leu-115 within the putative helix-loop-helix structure of the small HDAg is important for the replication of HDV but is not essential for RNA assembly, suggesting that conformational requirements of small HDAg for replication and assembly of viral RNA may be different. Further studies indicate that a 312-nucleotide linear HDV RNA from one end of the HDV and structure is sufficient to form RNP complexes competent for assembly of virus-like particles with large HDAg and small HBsAg.

Nuclear localization signals in the core protein of hepatitis C virus

The core protein of the hepatitis C virus is derived from the N-terminal 191 amino acids of the viral polyprotein by proteolytic cleavage. In the current study, subcellular localizations of the HCV core and its beta-galactosidase fusion proteins in transfected cells were examined by indirect immunofluorescence and cytochemical staining. The core protein was located predominantly in the cytoplasm 6 days after a plasmid encoding the full-length core protein had been introduced into mammalian cells. A hydrophobic domain in the C-terminal region of the core protein may block the efficiency of nuclear transport, since a beta-galactosidase fusion protein that contains HCV core protein lacking the C-terminal 66-amino-acid was located within the nuclei of mammalian cells 24 hours posttransfection. Three independent nuclear localization signals were further identified in the N-terminal region of the HCV core protein.

Mutational analysis of delta antigen: effect on assembly and replication of hepatitis delta virus

Hepatitis delta virus requires a helper function from hepatitis B virus for packaging, release, and infection of hepatocytes. The assembly of large delta antigen (HDAg) is mediated by copackaging with the small surface antigen of hepatitis B virus (HBsAg), and the assembly of small HDAg requires interactions with large HDAg. To examine the molecular mechanisms by which small HBsAg, large HDAg, and small HDAg interact, we have established a virion assembly system in COS7 cells by cotransfecting plasmids encoding the small HBsAg, the small HDAg, and large HDAg mutants. Results indicate that sequences within the C-terminal 19-amino-acid domain flanking the Cxxx isoprenylation motif are important for the assembly of large HDAg. In addition, a large HDAg mutant bearing extra sequences separating the C-terminal 19-amino-acid domain from the common regions of the small and large HDAgs is capable, like the wild-type large HDAg, of copackaging with small HBsAg. The ability of assembly is also demonstrated for a large HDAg mutant from which nuclear localization signals have been removed. Furthermore, a cryptic signal within the N-terminal 50 amino acid residues other than the putative N-terminal coiled-coil structure and a subdomain between amino acid residues 50 and 65 of the large HDAg are important for the assembly of small HDAg as well as the trans-dominant negative regulation of large HDAg in hepatitis delta virus replication.

The uses and limitations of DNA flow cytometry in stage IB or II cervical carcinoma

BACKGROUND

The role of flow cytometry in predicting prognosis for cervical carcinoma remains unclear.

METHODS

Flow cytometric analysis was performed on tissues, fixed in formaldehyde solution and embedded in paraffin, from 411 patients with Stage IB or II cervical carcinoma who had been treated with radical abdominal hysterectomy and bilateral pelvic lymphadenectomy.

RESULTS

DNA aneuploid-multiploid tumors were found in 37.5%, tetraploid in 4.6%, and diploid-peridiploid in 57.9%. Five-year recurrence-free survival rates of the three groups were 74.3%, 77.8%, and 76.4%, respectively (P > 0.05). DNA aneuploidy and DNA index (DI) of greater than 1.3 were highly correlated to parametria extension. In univariate analysis, pelvic lymph node metastases, stage, parametrial extension, depth of cervical stromal invasion, tumor size, and DI (1.3, 1.4, 1.5 as breakpoint) were significant prognostic factors. DNA ploidy, S-phase fraction, and S-G2M fraction were not significant. In multivariate analysis, DI of greater than 1.3, pelvic node metastases, clinical Stage II, and depth of stromal invasion greater than two-thirds of full cervical thickness were independent and significant variables. The prognostic index (PI), defined by the model, was able to categorize the patients into three distinct risk groups. The 5-year recurrence free survival rates of the low-, intermediate-, and high-risk groups were 89.5%, 73.0%, and 58.9%, respectively (P < 0.0001).

CONCLUSIONS

The prognostic value of the DI as a single variable is promising and warrants additional investigation to establish its appropriate use.

Functional motifs of delta antigen essential for RNA binding and replication of hepatitis delta virus

The functions of delta antigens (HDAgs) in the replication of hepatitis delta virus (HDV) have been identified previously. The small HDAg acts as a transactivator, whereas the large HDAg has a negative effect on replication. To understand the molecular mechanisms involved in the control of HDV replication, we have established a replication system in Huh-7 cells by cotransfecting a monomeric cDNA genome of HDV and a plasmid encoding the small HDAg. We demonstrate that a leucine repeat in the middle domain of the small HDAg is involved in binding to the HDV genome and transactivation of HDV replication. When the leucine repeat was disrupted by a substitution of valine for leucine at position 115, both RNA-binding and transactivation activity of the small HDAg were abolished. In contrast, the binding and transactivation activities were not affected when Leu-37 and Leu-44 of the small HDAg were replaced by valines. In addition, small and large HDAgs can interact with each other to form protein complexes in vitro. The complex formation that may lead to the trans-dominant negative regulation of large HDAg in HDV replication is mediated by a cryptic signal located between amino acid residues 35 and 65 other than the putative N-terminal leucine zipper motif. Furthermore, an extra 21-amino-acid extension near the N terminus converts the small HDAg into a pseudo-large HDAg with negative regulation activity of HDV replication even though the extreme C-terminal residue is unchanged.

Nuclear localization signals, but not putative leucine zipper motifs, are essential for nuclear transport of hepatitis delta antigen

Hepatitis delta antigen (HDAg) is the only known protein of hepatitis delta virus and was previously shown to localize in the nucleoplasm of infected liver cells. In this study, nuclear localization signals of HDAg were defined by expressing various domains of the antigen in both hepatic and nonhepatic cells as beta-galactosidase fusion proteins. A cytochemical staining assay demonstrated that a domain from amino acid residues 35 to 88 of HDAg was able to facilitate transport to the nucleus of the originally cytoplasm-localized protein beta-galactosidase. Two nuclear localization signals, NLS1 and NLS2, which are similar to those of simian virus 40 T antigen and polyomavirus T antigen, respectively, were identified. Either NLS1 or NLS2 alone was sufficient for the nuclear transport of HDAg. However, a fusion protein (N65Z) containing beta-galactosidase and the N-terminal 65 amino acids of HDAg, containing NLS1, was localized exclusively in the cytoplasm and perinuclear region. A possible hydrophobic subdomain between amino acid residues 50 and 65 may block the function of NLS1. Nevertheless, N65Z could enter the nuclei of transfected cells when it was coexpressed with full-length HDAg. Entry into the nucleus may be mediated by the coiled-coil structure rather than the putative leucine zipper motif located between amino acid residues 35 and 65. The existence of two independent nuclear localization signals may ensure the proper functioning of HDAg in the multiplication of delta virus in the nucleus. In addition, two putative casein kinase II sites (SRSE-5 and SREE-126) that may be important in controlling the rate of nuclear transport were found in HDAg.

Sequence conservation and divergence of hepatitis delta virus RNA

The complete RNA sequence of the hepatitis delta virus (HDV) obtained from the Nauru Island in the Pacific was determined by cDNA cloning and amplification by polymerase chain reaction (PCR). The sequence showed 14-17% divergence from the two known HDV RNA sequences. There are three highly conserved domains: the region around the autocatalytic cleavage site of the genomic RNA (nucleotides 659 to 772), the region around the autocatalytic cleavage site of the antigenomic-sense RNA (nucleotides 847 to 966), and the region around the middle one-third domain of the open reading frame (ORF) encoding the hepatitis delta antigen on the antigenomic RNA (nucleotides 1267 to 1347). The two autocatalytic activities are required for the cleavage and ligation of HDV RNA during RNA replication. The third conserved domain codes for the RNA-binding domain of HDAg, which specifically interacts with HDV RNA. Three nucleotide changes within the genomic catalytic sequence are present but did not alter the catalytic cleavage activity of the HDV RNA. Microheterogeneity of the RNA sequences was also detected. One of these occurred within the coding region of the delta antigen, creating an amber termination codon in some of the RNA species. Thus, this HDV strain contains two different RNA species, one of which encodes a delta antigen of 214 amino acids and the other 195 amino acids. These two protein species were detected by immunoblotting of the patient's plasma. In contrast to other HDV strains, only three ORFs capable of encoding more than 100 amino acids each are present in this HDV RNA. We recommend that oligonucleotides complementary to the highly conserved sequences should be used as primers for PCR in clinical detection assays of hepatitis delta virus infection.

Heterogeneity of hepatitis delta antigen

Hepatitis delta antigen (HDAg) is the only known protein encoded by the hepatitis delta virus (HDV). Two HDAg species of different sizes have been detected in the sera and livers of the infected humans, chimpanzees, and woodchucks, even though only one RNA species was previously identified in most of the HDV strains. To study HDAg heterogeneity, we took advantage of the fact that a single base mutation at nucleotide 1015 (C to U), which results in an amber termination codon in the HDAg open reading frame (ORF), eliminates a unique Ncol restriction enzyme site. We screened various HDV cDNA clones and detected sequence heterogeneity of the HDAg-coding region on the basis of the presence or absence of the Ncol site. Five delta hepatitis patients were examined. In every patient, two types of HDAg-coding sequence were detected at nucleotide 1015: one which contains a C and results in an ORF encoding a delta antigen of 214 amino acids, and the other which possesses a U and results in an amber termination codon and a truncated HDAg species of 195 amino acids. The in vitro translation products of these two ORFs comigrated with the two HDAg species from the patient's plasma on SDS polyacrylamide gels. Polymerase chain reaction (PCR) amplification of the HDV RNA from some patients' sera and subsequent sequencing showed several additional mutations in the HDAg-coding region. These mutations are independent of the C or U nucleotide change at the site of the amber termination codon.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of hepatitis delta antigen: specific binding to hepatitis delta virus RNA

It has previously been shown that human hepatitis virus delta antigen has an RNA-binding activity (Chang et al., J. Virol. 62:2403-2410, 1988). In the present study, the specificity of such an RNA-protein interaction was demonstrated by expressing various domains of the delta antigen in Escherichia coli as TrpE fusion proteins and testing their RNA-binding activities in a Northwestern protein-RNA immunoblot assay and RNA gel mobility shift assay. Hepatitis delta virus (HDV) RNA bound specifically to the delta antigen in the presence of an excess amount of unrelated RNAs and a relatively high salt concentration. Both genome- and antigenome-sense HDV RNAs and at least two different regions of HDV genomic RNA bound to the delta antigen. Surprisingly, these two different regions of HDV genomic RNA could compete with each other for delta antigen binding, although they do not have common nucleotide sequences. In contrast, this binding could not be competed with by other viral or cellular RNA. Since both the genomic and antigenomic HDV RNAs had strong intramolecular complementary sequences, these results suggest that the binding of delta antigen is probably specific for a secondary structure unique to the HDV RNA. By expressing different subdomains of the delta antigen, we found that the middle one-third of delta antigen was responsible for binding HDV RNA. Neither the N-terminal nor the C-terminal domain bound HDV RNA. Binding between the delta antigen and HDV RNA was also demonstrated within the HDV particles isolated from the plasma of a human delta hepatitis patient. This in vivo binding resisted treatment with 0.1% sodium dodecyl sulfate and 0.5% Nonidet P-40. In addition, we showed that the antiserum from a human patient with delta hepatitis reacted with all three subdomains of the delta antigen, indicating that all of the domains are immunogenic in vivo. These studies demonstrated the specific interaction between delta antigen and HDV RNA.

Identification of a domain required for autoproteolytic cleavage of murine coronavirus gene A polyprotein

The 5'-most gene of the murine coronavirus genome, gene A, is presumed to encode viral RNA-dependent RNA polymerase. It has previously been shown that the N-terminal portion of this gene product is cleaved into a protein of 28 kilodaltons (p28). To further understand the mechanism of synthesis of the p28 protein, cDNA clones representing the 5'-most 5.3 kilobases of murine coronavirus mouse hepatitis virus strain JHM were sequenced and subcloned into pT7 vectors from which RNAs were transcribed and translated in vitro. The sequence was found to encode a single long open reading frame continuing from near the 5' terminus of the genome. Although p28 is encoded from the first 1 kilobase at the 5' end of the genome, translation of in vitro-transcribed RNAs indicated that this protein was not detected unless the product of the entire 5.3-kilobase region was synthesized. Translation of RNAs of 3.9 kilobases or smaller yielded proteins which contained the p28 sequence, but p28 was not cleaved. This suggests that the sequence in the region between 3.9 and 5.3 kilobases from the 5' end of the genomic RNA is essential for proteolytic cleavage and contains autoproteolytic activity. The p28 protein could not be cleaved from the smaller primary translation products of gene A, even in the presence of the larger autocleaving protein. Cleavage of the p28 protein was inhibited by addition of the protease inhibitor ZnCl2. This study thus identified a protein domain essential for autoproteolytic cleavage of the gene A polyprotein.

Human hepatitis delta virus RNA subfragments contain an autocleavage activity

Hepatitis delta virus (HDV) contains a single-stranded circular RNA genome of 1.7 kilobases. In this report we demonstrate that subfragments of HDV RNA can undergo autocatalytic cleavage. This cleavage requires at least 500 microM of Mg2+ or Ca2+, is not affected by varying the pH from 5.0 to 9.1, and occurs with RNA fragments as small as 133 nucleotides. The larger RNA fragments containing additional HDV sequences have a lower efficiency of cleavage. Deletion analysis at both ends of RNA subfragments suggested that the catalytic ability of HDV RNA resides in a stretch of no more than 117 nucleotides around the cleavage site. The cleavage occurs at the phosphodiester bond between nucleotides 688 and 689 on the HDV genomic map, generating a 5' fragment with a terminal uridyl 2',3'-cyclic monophosphate residue and a 3' fragment with a guanosyl residue with a 5'-hydroxyl group. The smallest autocleaving RNA does not contain the "hammerhead" sequence required for the autocleavage of other known self-cleaving RNA. The cleavage of HDV RNA occurs at a much faster rate, even at a very low Mg2+ concentration, than that of other "ribozymes." Thus, HDV RNA represents a distinct class of ribozyme.

Human hepatitis delta antigen is a nuclear phosphoprotein with RNA-binding activity

The genetic origin, structure, and biochemical properties of the delta antigen (HDAg) of a human hepatitis delta virus (HDV) were investigated. A cDNA fragment containing the open reading frame encoding the HDAg was transcribed into RNA and used for in vitro translation in rabbit reticulocyte lysates. The HDAg open reading frame was also inserted into an expression vector containing a simian virus 40 T-antigen promoter and expressed into COS 7 cells. In both systems, a protein species of 26 kilodaltons was synthesized from this open reading frame and could be specifically immunoprecipitated with antisera obtained from patients with delta hepatitis. A similar protein was also synthesized from antigenomic-sense monomeric HDV RNA in both systems, although the efficiency of translation was lower than that of the isolated open reading frame. This protein was found to be phosphorylated at the serine residues. Immunoperoxidase studies with anti-HDV sera demonstrated that the HDAg was expressed mainly in the nuclei of the transfected COS 7 cells. Moreover, the HDAg was shown to bind the genomic RNA of HDV. These studies indicate that HDAg is encoded by the antigenomic-sense RNA of HDV and is a nuclear phosphoprotein associated with an RNA-binding activity.

Transcripts of the Drosophila blastoderm-specific locus, terminus, are concentrated posteriorly and encode a potential DNA-binding finger

The commitment of cells to specific fates, as well as the transitions in the cell cycle and transcription that occur at the cellular blastoderm stage of Drosophila embryogenesis, suggest that there are genes with unique functions expressed specifically at this stage. In an attempt to identify such genes, we used molecular screening to isolate several loci which encode blastoderm-specific transcripts (Roark et al., (1985). Dev. Biol. 109, 476-488). We report here the complete nucleotide sequence of one of these genes, terminus (ter), which maps to 75C1,2. The predicted ter protein possesses a transcription factor IIIA (TFIIIA)-like putative Zn-binding, DNA-binding finger. The ter RNA, detected by in situ hybridization, is distributed uniformly in the embryo during the syncytial blastoderm stage, and then becomes more concentrated in the posterior during the late cellular blastoderm stage. During gastrulation, the RNA is most concentrated in the amnioproctodeal invagination; it is also found at a lower concentration in the ventral furrow and in the anterodorsal neurogenic region. By the end of germ band extension, ter RNA is no longer detected.

Sequence and translation of the murine coronavirus 5'-end genomic RNA reveals the N-terminal structure of the putative RNA polymerase

A 28-kilodalton protein has been suggested to be the amino-terminal protein cleavage product of the putative coronavirus RNA polymerase (gene A) (M.R. Denison and S. Perlman, Virology 157:565-568, 1987). To elucidate the structure and mechanism of synthesis of this protein, the nucleotide sequence of the 5' 2.0 kilobases of the coronavirus mouse hepatitis virus strain JHM genome was determined. This sequence contains a single, long open reading frame and predicts a highly basic amino-terminal region. Cell-free translation of RNAs transcribed in vitro from DNAs containing gene A sequences in pT7 vectors yielded proteins initiated from the 5'-most optimal initiation codon at position 215 from the 5' end of the genome. The sequence preceding this initiation codon predicts the presence of a stable hairpin loop structure. The presence of an RNA secondary structure at the 5' end of the RNA genome is supported by the observation that gene A sequences were more efficiently translated in vitro when upstream noncoding sequences were removed. By comparing the translation products of virion genomic RNA and in vitro transcribed RNAs, we established that our clones encompassing the 5'-end mouse hepatitis virus genomic RNA encode the 28-kilodalton N-terminal cleavage product of the gene A protein. Possible cleavage sites for this protein are proposed.

Molecular cloning and sequencing of a human hepatitis delta (delta) virus RNA

Human hepatitis delta (delta) virus (HDV) is a form of defective virus, which infects humans only in the presence of a co-infecting hepatitis B virus (HBV). HDV superinfection in a chronic HBV carrier often results in severe chronic hepatitis and cirrhosis, whereas acute HDV and HBV co-infection is frequently associated with fulminant hepatitis. HDV consists of a 36-nm particle, which contains an envelope with HBV surface antigen, and a nucleocapsid containing the hepatitis delta-antigen (HDAg) and an RNA genome of 1.75 kilobases (kb). Recently, the genomic RNA from an HDV serially passaged in chimpanzees has been cloned and sequenced in a study which showed that the HDV RNA is a single-stranded circular molecule with properties similar to those of viroid or virusoid. However, it is not known whether serial passages in chimpanzees had altered the properties of human HDV. Here we report the cloning and sequencing of an HDV RNA isolated directly from a patient with acute delta-hepatitis. The sequence showed considerable divergence (11%) from that of the chimpanzee-adapted HDV. Five open reading frames (ORFs) of more than 100 amino acids in both genomic and anti-genomic sense were found. The largest ORF in antigenomic sense, which can code for 214 amino acids, may correspond to the HDAg.

The 5'-end sequence of the murine coronavirus genome: implications for multiple fusion sites in leader-primed transcription

The coronavirus leader-primed transcription model proposes that free leader RNA species derived from the 5'-end of the genomic RNA are utilized as a primer for the transcription of subgenomic mRNAs. To elucidate the precise mechanism of leader-priming, we cloned and sequenced the 5'-end of the mouse hepatitis virus genomic RNA. The 5'-terminal sequences are identical to the leader sequences present at the 5'-end of the subgenomic mRNAs. Two possible hairpin loop structures and an AU-rich region around the 3'-end of the leader sequence may provide the termination site for leader RNA synthesis. The comparison of 5'-end genomic sequences and the intergenic start sites for mRNA transcription revealed that there are homologous regions of 7-18 nucleotides at the putative leader/body junction sites. Some intergenic regions contain a mismatching nucleotide within this homologous region. We propose that free leader RNA binds to the intergenic region due to this homology and is cleaved at the mismatching nucleotide before serving as a primer. Thus, the free leader RNA species may be longer than the leader sequences in the subgenomic mRNAs and different mRNAs may have different leader/body junction sites.