Persistence of platelet thrombus formation in arterioles of mice lacking both von Willebrand factor and fibrinogen

We used intravital microscopy to observe the formation of platelet plugs in ferric chloride-injured arterioles of live mice. With this model, we evaluated thrombus growth in mice lacking von Willebrand factor (vWF) and fibrinogen (Fg), the two key ligands known to mediate platelet adhesion and aggregation. In vWF(-/-) mice, despite the presence of arterial shear, delayed platelet adhesion occurred and stable thrombi formed. In many mice, a persisting high-shear channel never occluded. Abundant thrombi formed in Fg(-/-) mice, but they detached from the subendothelium, which ultimately caused downstream occlusion in all cases. Surprisingly, mice deficient in both vWF and Fg successfully formed thrombi with properties characteristic of both mutations, leading to vessel occlusion in the majority of vessels. Platelets of these doubly deficient mice specifically accumulated fibronectin in their alpha-granules, suggesting that fibronectin could be the ligand supporting the platelet aggregation.

Evolutionary relationships of endemic/epidemic and sylvatic dengue viruses

Endemic/epidemic dengue viruses (DEN) that are transmitted among humans by the mosquito vectors Aedes aegypti and Aedes albopictus are hypothesized to have evolved from sylvatic DEN strains that are transmitted among nonhuman primates in West Africa and Malaysia by other Aedes mosquitoes. We tested this hypothesis with phylogenetic studies using envelope protein gene sequences of both endemic/epidemic and sylvatic strains. The basal position of sylvatic lineages of DEN-1, -2, and -4 suggested that the endemic/epidemic lineages of these three DEN serotypes evolved independently from sylvatic progenitors. Time estimates for evolution of the endemic/epidemic forms ranged from 100 to 1,500 years ago, and the evolution of endemic/epidemic forms represents relatively recent events in the history of DEN evolution. Analysis of envelope protein amino acid changes predicted to have accompanied endemic/epidemic emergence suggested a role for domain III in adaptation to new mosquito and/or human hosts.

Factors influencing knowledge of and adherence to self-care among patients with heart failure

BACKGROUND

Patient education has been shown to be a key component in comprehensive heart failure management. Few data, however, are available regarding patients' knowledge of and adherence to self-care recommendations for the disease.

OBJECTIVES

To assess the knowledge level of and adherence to self-care among patients with heart failure and to determine associated factors.

METHODS

We conducted a needs-assessment survey among new patients visiting a heart failure clinic from April 1997 through June 1998. Multiple linear regression analysis was used to assess the factors predictive of patients' knowledge level and adherence behaviors.

RESULTS

Of the 113 patients surveyed, 77% were referred by cardiologists and 60% had New York Heart Association class III or IV status. Two thirds of the patients reported receiving information or advice about self-care from health care providers. When asked how much they knew about congestive heart failure, however, 37% said "a little or nothing," 49% said "some," and only 14% said "a lot." Approximately 40% of the patients did not recognize the importance of weighing themselves daily and 27% weighed themselves twice a month or less often. Although 80% of the patients knew they should limit their salt intake, only one third always avoided salty foods. Additionally, 25% of the patients did not appreciate the risk of alcohol use and 36% believed they should drink a lot of fluids. The multiple linear regression analysis indicated that a higher knowledge score was associated with being married, prior hospitalization, and having received both advice and information about self-care from physicians or nurses. A poor adherence behavior score was associated with being unmarried, lower perceived self-efficacy, a lack of knowledge about self-care, and no prior hospitalization.

CONCLUSIONS

We observed a gap between patients receiving and absorbing or retaining information on self-care for congestive heart failure supplied by health care providers. Self-care education needs to be directed to outpatients in addition to inpatients.

Autophagy is involved in traumatic brain injury-induced cell death and contributes to functional outcome deficits in mice

Previous data demonstrate that traumatic brain injury (TBI) activates autophagy, and increases microtubule-associated protein 1 light chain 3 (LC3) immunostaining mainly in neurons. However, the role of autophagy in traumatic brain damage remains elusive. The aim of the present study was to investigate the autophagic mechanisms participating in traumatic brain injury. The autophagy inhibitors 3-methyladenine (3-MA) and bafliomycin A1 (BFA) were administered with a single i.c.v. injection before TBI. We first examined the protein levels of Beclin-1 and LC3 II, which have been found to promote autophagy previously. Immunoblotting analysis showed that 3-MA pretreatment reduced post-TBI Beclin-1 and LC3-II levels, and maintained p62/SQSTM1 (p62) levels. In addition, double immunolabeling showed that the increased punctate LC3-II dots colocalizing with Propidium Iodide (PI)-stained nuclei at 24 h after injury, were partially inhibited by 3-MA pretreatment. Furthermore, inhibition of autophagy could reduce TBI-induced cell injury assessed with i.p. injection of PI and lesion volume, and attenuate behavioral outcome evaluated by motor test and Morris water maze. The neuroprotective effects were associated with an inhibition on TBI-induced up-regulation of LC3, Beclin-1, cathepsin B, caspase-3 and the Beclin-1/Bcl-2 ratio. Taken together, these data imply that the autophagy pathway is involved in the pathophysiologic responses after TBI, and inhibition of this pathway may help attenuate traumatic damage and functional outcome deficits.

HIV gag mRNA transfection of dendritic cells (DC) delivers encoded antigen to MHC class I and II molecules, causes DC maturation, and induces a potent human in vitro primary immune response

Dendritic cells (DC) are the major APCs involved in naive T cell activation making them prime targets of vaccine research. We observed that mRNA was efficiently transfected, resulting in superior translation in DC compared with other professional APCs. A single stimulation of T cells by HIV gag-encoded mRNA-transfected DC in vitro resulted in primary CD4(+) and CD8(+) T cell immune responses at frequencies of Ag-specific cells (5-12.5%) similar to primary immune responses observed in vivo in murine models. Additionally, mRNA transfection also delivered a maturation signal to DC. Our results demonstrated that mRNA-mediated delivery of encoded Ag to DC induced potent primary T cell responses in vitro. mRNA transfection of DC, which mediated efficient delivery of antigenic peptides to MHC class I and II molecules, as well as delivering a maturation signal to DC, has the potential to be a potent and effective anti-HIV T cell-activating vaccine.

Analysis of expression of nuclear factor kappa B (NF-kappa B) in multiple myeloma: downregulation of NF-kappa B induces apoptosis

Nuclear factor-kappa B (NF-kappa B) is an important transcription factor that regulates survival in many cells. Activated NF-kappa B has been shown to protect some haematopoietic neoplastic cells from apoptosis. In the present study, we analysed NF-kappa B status in 13 primary samples from patients with multiple myeloma (MM) and in four myeloma cell lines including U266, RPMI 8226, HS-Sultan and K620. Constitutive activation of NF-kappa B was evaluated by either immunohistochemistry or immunofluorescence using a monoclonal mouse anti-human p65 (Rel A) antibody, which recognizes the unbound, active form of p65 (Rel A). Constitutively active NF-kappa B was present in all MM patient samples as well as in all four myeloma cell lines. Inhibition of constitutively active NF-kappa B, by either proteasome inhibitors (MG132, gliotoxin) or inhibitors of I kappa B phosphorylation (Bay117082, and Bay117085), induced apoptosis as demonstrated by both flow cytometric analysis and light microscopic morphological evaluation. This chemically induced apoptosis was associated with decreased DNA binding of nuclear NF-kappa B as determined by the electrophoretic mobility shift assay. In addition, adenovirus vector with dominant negative I kappa B alpha (Ad5I kappa B) was used for inhibition of NF-kappa B in the U266 cell line. Compared with wild-type, super-repressor-treated cells showed an increased level of apoptosis. These results suggest that constitutive expression of NF-kappa B plays an important role in plasma cell survival in MM.

Event generator tunes obtained from underlying event and multiparton scattering measurements

New sets of parameters ("tunes") for the underlying-event (UE) modelling of the pythia8, pythia6 and herwig++ Monte Carlo event generators are constructed using different parton distribution functions. Combined fits to CMS UE proton-proton ([Formula: see text]) data at [Formula: see text] and to UE proton-antiproton ([Formula: see text]) data from the CDF experiment at lower [Formula: see text], are used to study the UE models and constrain their parameters, providing thereby improved predictions for proton-proton collisions at 13[Formula: see text]. In addition, it is investigated whether the values of the parameters obtained from fits to UE observables are consistent with the values determined from fitting observables sensitive to double-parton scattering processes. Finally, comparisons are presented of the UE tunes to "minimum bias" (MB) events, multijet, and Drell-Yan ([Formula: see text] lepton-antilepton+jets) observables at 7 and 8[Formula: see text], as well as predictions for MB and UE observables at 13[Formula: see text].

Integrin activation by dithiothreitol or Mn2+ induces a ligand-occupied conformation and exposure of a novel NH2-terminal regulatory site on the beta1 integrin chain

Integrins can be expressed in at least three functional states (i.e. latent, active, and ligand-occupied). However, the molecular bases for the transitions between these states are unknown. In the present study, changes in the accessibility of several beta1 epitopes (e.g. N29, B44, and B3B11) were used to probe activation-related conformational changes. Dithiothreitol or Mn2+ activation of integrin-mediated adhesion in the human B cell line, IM9, resulted in a marked increase in the exposure of the B44 epitope, while N29 expression levels were most sensitive to dithiothreitol treatment. These results contrasted with the epitope expression patterns of spontaneously adherent K562 cells, where N29 was almost fully accessible and B44 was low. Addition of a soluble ligand resulted in a marked increase in B44 levels, suggesting that this antibody detected a ligand-induced binding site. The N29 epitope was mapped to a cysteine-rich region near the NH2 terminus of the integrin chain, thus defining a novel regulatory site. These studies indicate that the activation of integrin function by different stimuli may involve related but nonidentical conformations. Both Mn2+ and dithiothreitol appear to induce localized conformational changes that mimic a ligand-occupied receptor. This differs from the "physiologically" activated integrins on K562 cells that display a marked increase in overall epitope accessibility without exposure of the ligand-induced binding site epitopes. The increased exposure of the N29 site on K562 cells may indicate a role for this region in the regulation of integrin function.

Vitronectin stabilizes thrombi and vessel occlusion but plays a dual role in platelet aggregation

The role of vitronectin (Vn) in thrombosis is currently controversial; both inhibitory and supportive roles have been reported. To monitor directly the function of Vn in thrombotic events at the site of vascular injury, we studied Vn-deficient (Vn-/-) and wild-type (WT) control mice with two real-time intravital microscopy thrombosis models. In the mesenteric arteriole model, vessel injury was induced by ferric chloride. We observed unstable thrombi and a significantly greater number of emboli in Vn-/- mice. Vessel occlusion was also delayed and frequent vessel re-opening occurred. In the cremaster muscle arteriole model, vessel injury was induced by a nitrogen dye laser. We observed significantly fewer platelets, lower fibrin content, and unstable fibrin within the thrombi of Vn-/- mice. To define further the role of Vn in thrombus growth, we studied platelet aggregation in vitro. Consistent with our in vivo data, the second wave of thrombin-induced aggregation of gel-filtered platelets was abolished at a low concentration of thrombin in Vn-/- platelets. Interestingly, adenosine diphosphate (ADP)-induced platelet aggregation was significantly increased in Vn-/- platelet-rich plasma (PRP) and this effect was attenuated by adding purified plasma Vn. We also observed increased platelet aggregation induced by shear stress in Vn-/- whole blood. These data demonstrate that Vn is a thrombus stabilizer. However, in contrast to released platelet granule Vn which enhances platelet aggregation, plasma Vn inhibits platelet aggregation.

Polymerase chain reaction for diagnosis of meningococcal meningitis

Meningococcal disease is normally suspected on clinical grounds but confirmed by isolation of Neisseria meningitidis from blood or cerebrospinal fluid (CSF), or by detection of gram-negative diplococci in CSF. After parenteral antibiotics are started the isolation rate of meningococci from blood cultures drops from 50% to less than 5% and the chances of CSF being positive by culture or microscopy are also reduced. We used the polymerase chain reaction (PCR) in a blinded study to detect meningococcal DNA in 54 CSF samples from patients with meningococcal disease or from controls. The PCR primers were specific for the meningococcal insertion sequence IS1106. The sensitivity and specificity of this PCR for diagnosis of meningococcal meningitis were both 91%. Sensitivity was not affected by prior antibiotic treatment. The IS1106 PCR is a rapid and sensitive test for confirmation of the diagnosis of meningococcal meningitis.

Association of autoantibody specificity and response to intravenous immunoglobulin G therapy in immune thrombocytopenia: a multicenter cohort study

BACKGROUND

Immune thrombocytopenia (ITP) is a common autoimmune bleeding disorder, in which platelet glycoprotein (GP)IIb-IIIa and GPIb-IX are the two most frequently targeted autoantigens. Our previous studies in animal models of ITP demonstrated that intravenous immunoglobulin G (IVIG) could protect against anti-GPIIb-IIIa autoantibody-mediated thrombocytopenia but failed to ameliorate ITP induced by most anti-GPIb-IX autoantibodies.

OBJECTIVES

The objective of this human study was to evaluate the association between the specificity of antiplatelet autoantibodies and response to IVIG treatment.

PATIENTS/METHODS

In this retrospective study, a cohort of 156 previously untreated adults with severe ITP who underwent IVIG therapy (0.4 g kg(-1)  day(-1) for 5 days) was analyzed. The primary outcome was response defined as platelet counts of ≥ 30 × 10(9)  L(-1) and a doubling of baseline counts within 7 days of dosing, and an absence of bleeding.

RESULTS AND CONCLUSIONS

Among the 66 patients with anti-GPIb-IX autoantibodies, only 24 (36.4%) achieved a response, as compared with 72 of 90 patients (80.0%) who were negative for anti-GPIb-IX autoantibodies (relative risk 2.2; 95% confidence interval 1.6-3.1). This study found no difference in response between patients with anti-GPIIb-IIIa autoantibodies (61.7%) and those without anti-GPIIb-IIIa autoantibodies (61.3%). Logistic regressions, including main effects and the interaction between these two autoantibodies, showed no influence of anti-GPIIb-IIIa autoantibodies on the effects of anti-GPIb-IX autoantibodies with regard to their association with IVIG response. Thus, in adults with ITP, the presence of anti-GPIb-IX autoantibodies is a predictive factor for poor response to IVIG treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01666795.

MAPKAPK5, a novel mitogen-activated protein kinase (MAPK)-activated protein kinase, is a substrate of the extracellular-regulated kinase (ERK) and p38 kinase

A novel protein kinase that has significant sequence homology to mitogen-activated protein kinase (MAPK)-activated protein kinase (MAPKAPK) was identified. This novel protein kinase has a nucleotide sequence that encodes a protein of 473 amino acids and shares 45%, 46%, and 44% amino acid sequence identities to MAPKAPK2, 3 and 4 respectively. Northern blot analysis revealed that it has a wide tissue distribution. This novel protein kinase designated MAPKAPK5 can be phosphorylated by extracellular-regulated kinase (ERK), and p38 kinase but not by c-jun N-terminal kinase (JNK) in vitro. Recombinant GST-MAPKAPK5 protein can phosphorylate a peptide derived from the regulatory light chain of myosin II. Phosphorylation of MAPKAPK5 by ERK and p38 kinase increased its activity by 9 and 15 fold respectively. Taken together, these data suggest that MAPKAPK5 is a novel in vitro substrate for ERK and p38 kinase.

Genetic variation in the 3' non-coding region of dengue viruses

The 3' non-coding region (3'NCR) of strains of dengue 1 (DEN 1), DEN 2, DEN 3, and DEN 4 viruses, isolated in different geographical regions, was sequenced and compared to published sequences of the four dengue viruses. A total of 50 DEN 2 strains was compared: 7 West African strains, 3 Indonesian mosquito strains, 1 Indonesian macaque isolate, and 39 human isolates from Southeast Asia, the South Pacific, and the Caribbean and Americas. Nucleotide sequence alignment revealed few deletions and no repeat sequences in the 3' NCR of DEN 2 viruses and showed that much of the 3' NCR was well conserved. The strains could be divided into two groups, sylvatic and human/mosquito/macaque, based on nucleotide sequence homology. A hypervariable region was identified immediately following the NS5 stop codon, which involved a 2-10 nucleotide deletion in human, mosquito, and macaque isolates compared with the sylvatic strains. The DEN 2 3'NCR was also compared with 3'NCR sequences from strains of DEN 1, DEN 3, and DEN 4 viruses. DEN 1 was found to have four copies of an eight nucleotide imperfect repeat following the NS5 stop codon, while DEN 4 virus had a deletion of 75 nucleotides in the 3'NCR. We propose that the variation in nucleotide sequence in the 3'NCR may have evolved as a function of DEN virus transmission and replication in different mosquito and non-human primate/human host cycles. The results from this study are consistent with the hypothesis that DEN viruses arose from sylvatic progenitors and evolved into human epidemic strains. However, the data do not support the hypothesis that variation in the 3'NCR correlates with DEN virus pathogenesis.

Molecular basis of attenuation of neurovirulence of wild-type Japanese encephalitis virus strain SA14

To identify the molecular determinants for attenuation of wild-type Japanese encephalitis (JE) virus strain SA14, the RNA genome of wild-type strain SA14 and its attenuated vaccine virus SA14-2-8 were reverse transcribed, amplified by PCR and sequenced. Comparison of the nucleotide sequence of SA14-2-8 vaccine virus with virulent parent SA14 virus and with two other attenuated vaccine viruses derived from SA14 virus (SA14-14-2/PHK and SA14-14-2/PDK) revealed only seven amino acids in the virulent parent SA14 had been substituted in all three attenuated vaccines. Four were in the envelope (E) protein (E-138, E-176, E-315 and E-439), one in non-structural protein 2B (NS2B-63), one in NS3 (NS3-105), and one in NS4B (NS4B-106). The substitutions at E-315 and E-439 arose due to correction of the SA14/CDC sequence published previously by Nitayaphan et al. (Virology 177, 541-552, 1990). The mutations in NS2B and NS3 are in functional domains of the trypsin-like serine protease. Attenuation of SA14 virus may therefore, in part, be due to alterations in viral protease activity, which could affect replication of the virus.

Extraction and validation of a new set of CMS pythia8 tunes from underlying-event measurements

New sets of CMS underlying-event parameters ("tunes") are presented for the pythia8 event generator. These tunes use the NNPDF3.1 parton distribution functions (PDFs) at leading (LO), next-to-leading (NLO), or next-to-next-to-leading (NNLO) orders in perturbative quantum chromodynamics, and the strong coupling evolution at LO or NLO. Measurements of charged-particle multiplicity and transverse momentum densities at various hadron collision energies are fit simultaneously to determine the parameters of the tunes. Comparisons of the predictions of the new tunes are provided for observables sensitive to the event shapes at LEP, global underlying event, soft multiparton interactions, and double-parton scattering contributions. In addition, comparisons are made for observables measured in various specific processes, such as multijet, Drell-Yan, and top quark-antiquark pair production including jet substructure observables. The simulation of the underlying event provided by the new tunes is interfaced to a higher-order matrix-element calculation. For the first time, predictions from pythia8 obtained with tunes based on NLO or NNLO PDFs are shown to reliably describe minimum-bias and underlying-event data with a similar level of agreement to predictions from tunes using LO PDF sets.

Fibrinogen and von Willebrand factor-independent platelet aggregation in vitro and in vivo

BACKGROUND

Fibrinogen (Fg) has been considered essential for platelet aggregation. However, we recently demonstrated formation of occlusive thrombi in Fg-deficient mice and in mice doubly deficient for Fg and von Willebrand factor (Fg/VWF(-/-)).

METHODS AND RESULTS

Here we studied Fg/VWF-independent platelet aggregation in vitro and found no aggregation in citrated platelet-rich plasma of Fg/VWF(-/-) mice. Surprisingly, in Fg/VWF(-/-) plasma without anticoagulant, adenosine diphosphate induced robust aggregation of Fg/VWF(-/-) platelets but not of beta(3)-integrin-deficient (beta(3) (-/-)) platelets. In addition, beta(3) (-/-) platelets did not significantly incorporate into thrombi in Fg/VWF(-/-) mice. This Fg/VWF-independent aggregation was blocked by thrombin inhibitors (heparin, hirudin, PPACK), and thrombin or thrombin receptor activation peptide (AYPGKF-NH(2)) induced aggregation of gel-filtered Fg/VWF(-/-) platelets in 1 mm Ca(2+) PIPES buffer. Notably, aggregation in PIPES buffer was only 50-60% of that observed in Fg/VWF(-/-) plasma. Consistent with the requirement for thrombin in vitro, hirudin completely inhibited thrombus formation in Fg/VWF(-/-) mice. These data define a novel pathway of platelet aggregation independent of both Fg and VWF. Although this pathway was not detected in the presence of anticoagulants, it was observed under physiological conditions in vivo and in the presence of Ca(2+)in vitro.

CONCLUSIONS

beta(3) integrin, thrombin, and Ca(2+) play critical roles in this Fg/VWF-independent aggregation, and both plasma and platelet granule proteins contribute to this process.

Active site binding modes of HIV-1 integrase inhibitors

Using the crystal structure of the first complex of the HIV-1 integrase catalytic core domain with an inhibitor bound to the active site, structural models for the interaction of various inhibitors with integrase were generated by computational docking. For the compound of the crystallographic study, binding modes unaffected by crystal packing have recently been proposed. Although a large search region was used for the docking simulations, the ligands investigated here are found to bind preferably in similar ways close to the active site. The binding site is formed by residues 64-67, 116, 148, 151-152, 155-156, and 159, as well as by residue 92 in case of the largest ligand of the series. The coherent picture of possible interactions of small-molecule inhibitors at the active site provides an improved basis for structure-based ligand design. The recurring motif of tight interaction with the two lysine residues 156 and 159 is suggested to be of prime importance.

Responses of plasma adrenocortical steroids to low dose ACTH in normal subjects

OBJECTIVE

The standard ACTH test in clinical use employs a pharmacological dose of ACTH which assesses the maximum secretory capacity of the adrenal cortex. We have investigated the responses of plasma adrenocortical steroids including cortisol, aldosterone and dehydroepiandrosterone (DHEA) to physiological doses of ACTH (ACTH 1-24, tetracosactide, Cortrosyn) and determined the minimal dose which induces a response equivalent to that induced by a pharmacological dose of ACTH.

DESIGN

Rapid ACTH tests at various physiological (0-1, 0.5, 1 and 5 micrograms) and standard pharmacological (250 micrograms) intravenous doses.

SUBJECTS

Seven healthy normal volunteers.

MEASUREMENTS

Plasma cortisol, aldosterone and DHEA were measured. Peak value and the increment from basal value were used as indices of responses.

RESULTS

Each steroid responded to physiological doses of ACTH in a dose dependent manner. The minimum dose inducing an equivalent response to 250 micrograms ACTH was 0.5 micrograms for peak and incremental values in cortisol and DHEA, while that for aldosterone was 0.1 microgram. The time to peak for each steroid was delayed as the dose increased. Plasma aldosterone and DHEA peaked significantly earlier than plasma cortisol in 1-5 micrograms and 0.5-5-micrograms ACTH tests, respectively.

CONCLUSIONS

These results suggest that the sensitivity of secretion to physiological doses of ACTH in descending order is aldosterone > DHEA = cortisol. When peak and incremental values are used, sufficient doses of ACTH are 0.1 microgram for plasma aldosterone and 0.5 microgram for plasma cortisol and DHEA in the rapid ACTH test.

Valproic acid adjunctive therapy for HIV-associated cognitive impairment: a first report

In vitro and animal model data demonstrate that valproic acid (VPA) can ameliorate HIV-associated neurotoxicity. The authors conducted a pilot 10-week placebo-controlled study of VPA 250 mg twice daily in 22 HIV-infected individuals with (n = 16) and without (n = 6) cognitive impairment. VPA was safe and well tolerated, with trends toward improved neuropsychological performance and brain metabolism in the impaired subjects.

Characterization of NF-kappaB expression in Hodgkin's disease: inhibition of constitutively expressed NF-kappaB results in spontaneous caspase-independent apoptosis in Hodgkin and Reed-Sternberg cells

Although the neoplastic cells of classical Hodgkin's disease (CHD) demonstrate high levels of constitutively active nuclear NF-kappaB, the precise physiologic and clinical significance of NF-kappaB expression is currently undefined. Expression of active NF-kappaB p65(Rel A) was evaluated in patient samples of CHD and nodular lymphocyte predominance Hodgkin's disease. The action of the chemical NF-kappaB inhibitors gliotoxin and MG132 and the effect of NF-kappaB inhibition utilizing an adenovirus vector carrying a dominant-negative IkappaBalpha mutant (Ad5IkappaB) were then demonstrated in CHD cell lines (L428, KMH2, and HS445). Hodgkin and Reed-Sternberg (HRS) cells from all patient and cell line specimens showed strong immunopositivity for active p65(Rel A). Expression was also seen in lymphocytic/histiocytic cells from all cases of nodular lymphocyte predominance Hodgkin's disease. After chemical NF-kappaB inhibition, p65(Rel A) was significantly reduced in nuclear extracts from cultured HRS cells as revealed by electrophoretic mobility shift assays. Furthermore, chemical NF-kappaB inhibition resulted in time- and concentration-dependent apoptosis in HRS cells. With the exception of MG132-induced apoptosis in HS445, apoptosis by chemical NF-kappaB inhibition was not significantly altered by preincubation with various caspase inhibitors (z-DQMD-FMK, z-DEVD-FMK, z-VAD-FMK, z-VEID-FMK, and z-IETD-FMK). Regardless of the chemical inhibitor used, no significant change in caspase-3 functional activity was found in CHD cell lines. HRS cells infected with Ad5IkappaB also showed a marked increase in spontaneous apoptosis compared with wild type adenovirus-infected and control cells. Overall, the inhibition of active NF-kappaB in HRS cells resulting in spontaneous caspase-independent apoptosis demonstrates a critical role for NF-kappaB in HRS cell survival and resistance to apoptosis.

Molecular differences between wild-type Japanese encephalitis virus strains of high and low mouse neuroinvasiveness

Japanese encephalitis (JE) virus strain P3 was highly neurovirulent and neuroinvasive in weanling mice whereas two other JE virus strains, SA14/USA and S892, were only neurovirulent. Infectivity titrations of brains and sera showed that P3 virus multiplied faster and reached a higher infectivity titre than S892 virus following inoculation of viruses by the intraperitoneal (i.p.) route. The p.f.u./LD50 was 10(1.7) and 10(6.2) for P3 and S892 viruses respectively, following i.p. inoculation, while JE virus strain SA14/USA did not kill mice when inoculated by this route (i.e. > or = 10(6.3) p.f.u./LD50). Nevertheless, the genomic similarity between P3 virus and strains SA 14/USA and S892 was more than 97.8 percent at the nucleotide level and 99 percent at the amino acid level. Compared with S892 and SA14/USA viruses, P3 virus had 33 and 21 amino acid differences, respectively. The structural protein genes of P3 virus were more divergent than non-structural protein genes. Nine unique amino acids were found in the envelope protein gene. None of these amino acid differences were shared with other wild-type JE virus strains. Although we cannot identify the precise molecular determinants of virulence of JE virus, there were no unique amino acids in M, NS1, NS2A, NS3, NS4A and NS4B proteins of P3 virus compared with other wild-type viruses. Therefore, it appears that these proteins make no significant contribution to the high neuroinvasiveness of P3 virus. The structural proteins, and non-structural proteins NS2B and NS5 may be involved in increasing neurovirulence and neuroinvasiveness of P3 virus. P3 virus differed by several nucleotides in the 3' non-coding region while no nucleotide difference was found in the 5' non-coding region.

Comparison of nucleotide and deduced amino acid sequence of the 5' non-coding region and structural protein genes of the wild-type Japanese encephalitis virus strain SA14 and its attenuated vaccine derivatives

Nucleotide sequences of the 5' non-coding region and the structural protein genes of the live, attenuated Japanese encephalitis vaccine virus strains SA14-2-8 and SA14-5-3 and the wild-type parental strain SA14/USA were determined. SA14-2-8 differed from SA14/USA by 13 nucleotides and eight amino acids whereas SA14-5-3 differed from SA14/USA by 15 nucleotides and eight amino acids. A comparison of the 5' non-coding region and amino acid sequences of the structural proteins of these two attenuated vaccine strains and of vaccine strains SA14-14-2/PHK and SA14-14-2/PDK with three sequences of their wild-type parent SA14 virus was performed. This revealed only two common amino acid substitutions at positions 138 and 176 in the envelope (E) protein. The substitution at E138 was predicted to cause a change in the secondary structure of the E protein. These two amino acid substitutions in the E protein may contribute to attenuation of the Japanese encephalitis vaccine viruses.

Attenuation of Japanese encephalitis virus by selection of its mouse brain membrane receptor preparation escape variants

Six variants of Japanese encephalitis (JE) virus strain P3 were selected for resistance to binding to mouse brain membrane receptor preparations (MRP). All but one of these MRP escape (MRPR) variants were significantly attenuated in mice for both neuroinvasiveness (>200-fold) and neurovirulence (>500-fold) compared to their parent virus. Attenuated mouse brain MRPR variants could be detected in the sera of mice following either intracerebral (i.c.) or intraperitoneal inoculation, whereas virus was detected only in brains of mice following ic inoculation. Immunization of mice with MRPRs induced neutralizing antibodies and protected mice against challenge with wild-type JE virus. A common amino acid mutation was found in the envelope (E) protein gene of all attenuated mouse brain MRPR variants at residue E-306 compared to P3 virus grown in mosquito C6-36 cells or plaque purified and amplified in monkey kidney Vero cells. This amino acid is putatively responsible for attenuation due to alteration in binding of JE virus to its cell receptor in mouse brain. The methodology developed in this study has general applicability to the attenuation of virulence of viruses and to the identification of agents that will block amino acids in a viral attachment protein(s) that interacts with cell receptors.