Biomedical subjects

M Rowe

Publications and source records attributed to M Rowe.

At least 19 recordsLinked to original sources

PubMed2001

Characterization of intercellular adhesion molecule-1 regulation by Epstein-Barr virus-encoded latent membrane protein-1 identifies pathways that cooperate with nuclear factor kappa B to activate transcription.

The latent membrane protein-1 (LMP1) of Epstein-Barr virus induces gene transcription, phenotypic changes, and oncogenic transformation. One cellular gene induced by LMP1 is that for intercellular adhesion molecule-1 (ICAM-1), which participates in a wide range of inflammatory and immune responses. ICAM-1 may enhance the immune recognition of cells transformed by Epstein-Barr virus, and thus combat development of malignancy. Despite growing understanding of the various signaling functions of LMP1, the molecular mechanisms by which LMP1 induces ICAM-1 are not understood. Here, we demonstrate that transcriptional activation by LMP1 is absolutely dependent upon a variant NF-kappaB motif within the tumor necrosis factor alpha (TNFalpha) response element of the ICAM-1 promoter. Although the TNFalpha response element is sufficient for TNFalpha induction of the ICAM-1 promoter, LMP1 also required the cooperation of additional upstream sequences for optimal induction. Inhibitor studies of known LMP1-induced signaling pathways ruled out the involvement of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase, and the Janus-activating tyrosine kinase 3 (JAK3), and confirmed NF-kappaB as a critical factor for induction of ICAM-1. However, although constitutive activation of NF-kappaB efficiently induced promoter activity, it was not sufficient to induce either ICAM-1 mRNA or ICAM-1 protein. Using signaling defective LMP1 mutants and deacetylation inhibitors, we showed that the C-terminal activator region 1 of LMP1 delivers a new cooperating signal to induce ICAM-1 mRNA.

B-Lymphocytes↗

PubMed2001

Mechanism of action of a novel latent membrane protein-1 dominant negative.

Latent membrane protein-1 (LMP1) is a signaling molecule expressed by Epstein-Barr virus during latency. LMP1 is essential for B-cell immortalization by Epstein-Barr virus and transforms rodent fibroblasts. It activates many distinct signaling pathways including the transcription factors NFkappaB and AP1. We have generated a mutant of LMP1 with four point mutations; amino acids 204, 206, and 208 were mutated to alanine, and amino acid 384 was mutated to glycine. This mutant, termed LMP1(AAAG), is not only unable to activate nuclear signaling pathways, but also inhibits signaling from wild type LMP1. We have demonstrated the effectiveness, selectivity, and mechanism of this inhibitory molecule. It inhibits LMP1-stimulated NFkappaB, STAT, and Jun transcriptional activity. It is selective, as it does not inhibit TNF or interleukin-2 signaling. We have demonstrated that it does not sequester the downstream signaling molecule, TRAF2, but instead binds LMP1 and interferes with its ability to bind TRAF2. This demonstrates the importance of the interplay between the signaling domains of LMP1 and the oligomeric structure of LMP1 for effective signaling. It identifies a tool that will be useful to probe LMP1 function in disease.

Alanine↗

PubMed2000

Experimental entanglement of four particles

Quantum mechanics allows for many-particle wavefunctions that cannot be factorized into a product of single-particle wavefunctions, even when the constituent particles are entirely distinct. Such 'entangled' states explicitly demonstrate the non-local character of quantum theory, having potential applications in high-precision spectroscopy, quantum communication, cryptography and computation. In general, the more particles that can be entangled, the more clearly nonclassical effects are exhibited--and the more useful the states are for quantum applications. Here we implement a recently proposed entanglement technique to generate entangled states of two and four trapped ions. Coupling between the ions is provided through their collective motional degrees of freedom, but actual motional excitation is minimized. Entanglement is achieved using a single laser pulse, and the method can in principle be applied to any number of ions.

Journal Article↗

PubMed2000

Viral latent membrane protein 1 (LMP-1)-induced CD99 down-regulation in B cells leads to the generation of cells with Hodgkin's and Reed-Sternberg phenotype.

Recently we reported that the down-regulation of CD99 (Mic2) is a primary requirement for the generation of Hodgkin's and Reed-Sternberg (H-RS) cells seen in Hodgkin's disease. In this study, we provide evidence that the down-regulation of CD99 is induced by high expression of Epstein-Barr virus (EBV) latent membrane protein 1 (LMP-1), which is highly expressed in H-RS cells of EBV-associated Hodgkin's disease. To investigate the effect of LMP-1 on the expression of CD99 in vitro, we established a stable cell line by transfecting an SV40-early promoter driven-LMP-1 expression construct into a neoplastic lymphoblastoid B cell line, IM9, in which the level of endogenous LMP-1 expression is almost negligible. In this cell line, the overexpression of LMP-1 led to the down-regulation of CD99 and the acquisition of morphological and functional characteristics of H-RS cells indistinguishable from those in lymph nodes of Hodgkin's disease patients and in CD99-deficient B cells. In addition, induced LMP-1 expression in an EBV-negative B cell clone, BJAB, directly caused the down-regulation of surface CD99 expression. Northern and Western analysis data, showing that overexpression of LMP-1 negatively influenced the expression of CD99, were supported by experiments in which a CD99 promoter-driven luciferase promoter reporter construct transfected into 293T cells was down-regulated when LMP-1 was coexpressed. Therefore, our data strongly suggest that the EBV LMP-1 protein plays a pivotal role in the down-regulation of CD99 via transcriptional regulation, which leads to the generation of the H-RS cells. (Blood. 2000;95:294-300)

12E7 Antigen↗

PubMed2000

Reply

Explore the source record for details and available documents.

Journal Article↗

PubMed2000

Preceptors' use of reflection to teach in ambulatory settings: An exploratory study.

PURPOSE: Reflection on one's teaching behavior is a means to question teaching events to bring teaching actions to a conscious level, to interpret the consequences of those actions, and to conceptualize alternative teaching actions. Ambulatory teaching settings are variable, unpredictable, and discontinuous, often resulting in less focused teaching. The authors sought to measure the level of reflection on teaching used by preceptors to plan teaching in these settings. METHOD: Three preceptors who had participated in the Case Western Reserve University's peer-coaching program each answered four questions about how they planned to respond to two teaching case studies. The questions were posed by a medical educator who, for three of the four questions, also prompted the preceptors to stimulate their reflection. The audiotaped responses were assessed using Sparks-Langer and Colton's framework for reflective thinking. RESULTS: The levels of reflective thinking increased after prompting, but they did not exceed the rather low technical and practical levels, particularly for the more complex of the two cases. CONCLUSION: This exploratory intervention suggests that faculty rely more on external and non-reflective levels of thought when planning to teach in the ambulatory setting. The authors recommend further research to foster discussions about the cognitive processes involved in planning for teaching in this setting.

Adolescent↗

PubMed2000

The bfl-1 gene is transcriptionally upregulated by the Epstein-Barr virus LMP1, and its expression promotes the survival of a Burkitt's lymphoma cell line.

The recently identified bfl-1 gene (also known as A1 or GRS), a homologue of bcl-2, encodes an antiapoptotic protein that suppresses apoptosis induced by the p53 tumor suppressor protein and exhibits proliferative and potent cooperative transforming activities. We show that elevated levels of bfl-1 mRNA are a feature of Epstein-Barr virus (EBV)-immortalized B-cell lines and Burkitt's lymphoma cell lines expressing the full spectrum of EBV latent proteins. Using an EBV-negative Burkitt's lymphoma cell line in which the expression of EBV latent membrane protein 1 (LMP1) is inducibly regulated by tetracycline, we demonstrate that LMP1 expression coincides with a dramatic increase in the level of bfl-1 mRNA. Also in this system, an increase in the level of Bcl-2 protein was seen to occur earlier than that of bcl-2 mRNA, suggesting that both transcriptional and translational mechanisms are involved in the control of Bcl-2 expression by LMP-1. We show that elevated bfl-1 mRNA stability can contribute to this effect of LMP-1, thus providing evidence of a novel mechanism of gene regulation by this EBV protein. Upregulation of bfl-1 by LMP1 was not observed in the T-cell line Jurkat or the epithelial cell line C33A. Ectopic expression of Bfl-1 in an EBV-positive cell line exhibiting a latency type I infection protects against apoptosis induced by growth factor deprivation, thereby providing a functional role for Bfl-1 in this cellular context and adding Bfl-1 to the list of antiapoptotic proteins whose expression is modulated by EBV. This is the first report of the regulation of bfl-1 expression by a viral protein, and this novel finding may thus represent an important link between the EBV oncoprotein LMP1 and its cellular growth-transforming properties.

Apoptosis↗

PubMed1999

Comparison of immunogenicity of two hepatitis A vaccines--VAQTA and HAVRIX--in young adults.

Two new hepatitis A vaccines have been developed, and their immunogenicity tested using different immunoassays. The present study was designed to compare the immunogenicity of these two hepatitis A virus (HAV) vaccines--VAQTA and HAVRIX--as determined by seroconversion rates and anti-HAV titers, and using the same immunoassay. Healthy volunteers (15-30 y), seronegative for anti-HAV, were randomized in an open single center study to four groups of 20-21 vaccinees each, to receive either a 25 U or a 50 U dose of VAQTA, or HAVRIX at 720 EU or 1440 EU/dose, administered at 0, 1 and 6 m or at 0 and 6 m, respectively. Four weeks after primary immunization, seroconversion rates were 100% for VAQTA and 95% for HAVRIX, following injection of 50 U or 1440 EU, respectively (p = NS) and anti-HAV GMTs were 40 and 37 mIU/ml for VAQTA and HAVRIX, respectively. At 6 months, prior to the booster dose, seroconversion rates were 100% for both vaccines, with anti-HAV GMTs of 111 and 70 mIU/ml for VAQTA and HAVRIX, respectively (P < 0.05). At month 7, four weeks after the only booster injection, using the two dose regimen, anti-HAV titers were 2212 and 1511 mIU/ml for VAQTA and HAVRIX, respectively (P < NS). Using three doses of 25 U/dose of VAQTA or 720 EU/dose of HAVRIX at 0, 1 and 6 m did not produce any clinically evaluable advantage over the two dose regimen for either vaccine. No significant adverse events were observed using either vaccine. In summary, both vaccines have similar immunogenicity demonstrated using identical immunoassays for evaluation. These results also confirm the outstanding immunogenicity of a single dose of either of the HAV vaccines and support their use in pre- and possibly postexposure prophylaxis against hepatitis A virus infection.

Adolescent↗

PubMed1999

Differential responses to CD40 ligation among Burkitt lymphoma lines that are uniformly responsive to Epstein-Barr virus latent membrane protein 1.

Ligation of CD40 on the surface of B cells induces multiple phenotypic effects, many of which are mimicked by the EBV latent membrane protein 1 (LMP1) through its interaction with downstream components of the CD40 signaling pathway. Because the effects of LMP1 have been most closely studied in human Burkitt Lymphoma (BL) cell lines retaining a tumor biopsy-like phenotype in vitro, we have examined the response of a panel of such lines to CD40 ligation. Two distinct patterns of response were observed that were unrelated to the surface level of CD40 or to the EBV genome status of the lines. Following exposure to either CD40-specific mAbs or the soluble trimeric ligand (sCD40L), high responder (HR) lines showed rapid aggregation, activation of NF-kappa B, up-regulation of cell surface markers ICAM-1/CD54 and Fas/CD95, and growth inhibition. Aggregation was seen at lower doses than those required to elicit the other effects. By contrast, low responder (LR) lines showed no detectable response to CD40 mAbs, while their responses to sCD40L were limited to activation of NF-kappa B and up-regulation of CD95 only. However, in transfection experiments, LMP1 uniformly induced the full spectrum of phenotypic effects in both HR and LR lines. We conclude that some BL cell lines show a highly restricted response to CD40 ligation but remain fully susceptible to LMP1.

Burkitt Lymphoma↗

PubMed1999

Comparison of immune reactivity and pharmacokinetics of two hepatitis B immune globulins in patients after liver transplantation.

Hepatitis B virus (HBV) immune globulin (HBIg) administration will prevent HBV graft reinfection in HBV patients after orthotopic liver transplantation (OLT). However, the expenditure for such prophylaxis is extremely high ranging between $2,000 to $10,000 per month in various countries for an undefined period and presumably for life. As a consequence, there is a need for introduction of additional and less expensive modes of treatment. In a preliminary clinical trial a new HBIg preparation has been shown to induce longer lasting levels of circulating antibodies to hepatitis B surface antigen (anti-HBs) in patients after OLT compared with previous experience with conventional HBIg preparations. In the present study the pharmacokinetics of this new HBIg, OMRI-Hep-B, were studied and compared with a conventional, licensed preparation, Hepatect. Fifteen post-OLT patients (2-8 years post-OLT, 18-62 years of age, 6 men, 9 women) were treated intravenously with 49 doses of OMRI-Hep-B or Hepatect given at least once, alternately, at 10,000 to 14,000 units per injection ( approximately 130 IU/kg body weight). The new HBIg was well tolerated and no adverse effects were observed. Administration of OMRI-Hep-B was shown to induce high and long-lasting levels of circulating anti-HBs antibodies and greater areas under the curve (AUC) compared with the conventional preparation. Thus, anti-HBs half-life was 22 +/- 1.3 days for OMRI-Hep-B recipients and 13 +/- 1.3 days for Hepatect recipients (P <.001). Time to reach trough anti-HBs levels of 150 mIU/mL was significantly longer after administration of OMRI-Hep-B than after Hepatect (79 +/- 4.5 and 52 +/- 3.8 days, respectively; P <.001). In summary, the pharmacokinetic profile of the new HBIg, and in particular its prolonged elimination half-life, may reduce the cost of administration by approximately 30% and improve the quality of life of patients by extending the interval between repeated immune globulin injections.

Adolescent↗

PubMed1999

Outreach workers' experiences in a homeless outreach project: issues of boundaries, ethics and staff safety.

Mental health professionals and researchers have emphasized the importance of conducting outreach to locate homeless persons with mental illness, and of creatively engaging these persons into a therapeutic relationship. These outreach and engagement activities raise challenging issues in the areas of client-staff boundaries, professional ethics, and staff safety. While several issues in each of these three key areas have received attention in the growing literature on homelessness, certain issues within each area remain unexplored. The authors draw from the street experiences of outreach staff in a federally funded homeless outreach project to further explore each of these areas, and suggest that experiences of outreach workers are essential in shaping and redefining work activities in these, and other important areas.

Adult↗

PubMed1999

Interference of antibody production to hepatitis B surface antigen in a combination hepatitis A/hepatitis B vaccine.

A randomized trial comparing 3 manufacturing consistency lots of a combination hepatitis A/hepatitis B vaccine to each other and to hepatitis A vaccine and hepatitis B vaccine given separately and concurrently was done to evaluate safety, tolerability, and immunogenicity. Healthy volunteers >/=11 years of age were divided into 4 groups. Each of 3 groups received a separate consistency lot of the combination vaccine, and 1 group received separate but concurrent injections of hepatitis A and hepatitis B vaccines. Injections were given at weeks 0 and 24. The combination vaccine was generally well tolerated. The hepatitis A portion of the combination vaccine produced clinically acceptable high seropositivity rates 4 and 52 weeks after the first injection. The hepatitis B portion of the vaccine did not produce clinically acceptable seropositivity rates 4 weeks after the second injection. Lack of antibody production may be attributed, at least in part, to immunologic interference.

Adolescent↗

PubMed1999

Epstein-Barr virus-encoded latent membrane protein 1 activates the JNK pathway through its extreme C terminus via a mechanism involving TRADD and TRAF2.

The transforming Epstein-Barr virus-encoded latent membrane protein 1 (LMP1) activates signalling on the NF-kappaB axis through two distinct domains in its cytoplasmic C terminus, namely, CTAR1 (amino acids [aa] 187 to 231) and CTAR2 (aa 351 to 386). The ability of CTAR1 to activate NF-kappaB appears to be attributable to the direct interaction of tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2), while recent work indicates that CTAR2-induced NF-kappaB is mediated through its association with TNF receptor-associated death domain (TRADD). LMP1 expression also results in activation of the c-Jun N-terminal kinase (JNK) (also known as stress-activated protein kinase) cascade, an effect which is mediated exclusively through CTAR2 and can be dissociated from NF-kappaB induction. The organization and signalling components involved in LMP1-induced JNK activation are not known. In this study we have dissected the extreme C terminus of LMP1 and have identified the last 8 aa of the protein (aa 378 to 386) as being important for JNK signalling. Using a series of fine mutants in which single amino acids between codons 379 and 386 were changed to glycine, we have found that mutations of Pro379, Glu381, Ser383, or Tyr384 diminish the ability of LMP1 CTAR2 to engage JNK signalling. Interestingly, this region was also found to be essential for CTAR2-mediated NF-kappaB induction and coincides with the LMP1 amino acid sequences shown to bind TRADD. Furthermore, we have found that LMP1-mediated JNK activation is synergistically augmented by low levels of TRADD expression, suggesting that this adapter protein is critical for LMP1 signalling. TRAF2 is known to associate with TRADD, and expression of a dominant-negative N-terminal deletion TRAF2 mutant was found to partially inhibit LMP1-induced JNK activation in 293 cells. In addition, the TRAF2-interacting protein A20 blocked both LMP1-induced JNK and NF-kappaB activation, further implicating TRAF2 in these phenomena. While expression of a kinase-inactive mutated NF-kappaB-inducing kinase (NIK), a mitogen-activated protein kinase kinase kinase which also associates with TRAF2, impaired LMP1 signalling on the NF-kappaB axis, it did not inhibit LMP1-induced JNK activation, suggesting that these two pathways may bifurcate at the level of TRAF2. These data further define a role for TRADD and TRAF2 in JNK activation and confirm that LMP1 utilizes signalling mechanisms used by the TNF receptor/CD40 family to elicit its pleiotropic activities.

Amino Acids↗

PubMed1999

Epstein-Barr virus nuclear antigen 3C interacts with histone deacetylase to repress transcription.

EBNA3C can specifically repress the expression of reporter plasmids containing EBV Cp latency-associated promoter elements. Cp is normally the main promoter for EBNA mRNA initiation, so it appears that EBNA3C contributes to a negative autoregulatory control loop. By mutational analysis it was previously established that this repression is consistent with EBNA3C being targeted to Cp by binding the cellular sequence-specific DNA-binding protein CBF1 (also known as recombination signal-binding protein [RBP]-Jkappa. Further analysis suggested that in vivo a corepressor interacts with EBNA3C in this DNA binding complex. Results presented here are all consistent with a component of such a corepressor exhibiting histone deacetylase activity. The drug trichostatin A, which specifically inhibits histone deacetylases, relieved two- to threefold the repression of Cp induced by EBNA3C in two different cell types. Moreover, repression of pTK-CAT-Cp4x by EBNA3C was specifically enhanced by cotransfection of an expression plasmid for human histone deacetylase-1 (HDAC1). Consistent with these functional assays, in vitro-translated HDAC1 bound to a glutathione S-transferase (GST) fusion protein including full-length EBNA3C, and in the reciprocal experiment EBNA3C bound to a GST fusion with the N terminus of HDAC1. Coimmunoprecipitations also revealed an EBNA3C-HDAC1 interaction in vivo, and GST-EBNA3C bound functional histone deacetylase enzyme activity from HeLa cell nuclear extracts. The region of EBNA3C involved in the interaction with HDAC1 appears to correspond to the region which is necessary for binding to CBF1/RBP-Jkappa. A direct physical interaction between EBNA3C and HDAC1 was demonstrated with recombinant proteins purified from bacterial cells, and we therefore conclude that HDAC1 and CBF1/RBP-Jkappa bind to the same or adjacent regions of EBNA3C. These data suggest that recruitment of histone deacetylase activity makes a significant contribution to the repression of transcription from Cp because EBNA3C bridges an interaction between CBF1/RBP-Jkappa and HDAC1.

Animals↗

PubMed1999

Handsearching the Journal of the Royal Army Medical Corps for trials.

As part of the Cochrane Collaboration's international research endeavour, the authors carried out a handsearch of the RAMC Journal from 1948 to 1998, searching for randomised controlled trials (RCTs) and controlled clinical trials (CCTs). Ten trials were identified, of which 6 were RCTs and 4 were CCTs. The first trial was published in 1967. Four of the 10 identified trials were in the field of respiratory medicine, and 2 were in obstetrics and gynaecology. Of the 10 trials, only 3 had been found through a rigorous interrogation of Medline. The 7 newly identified trials were reported to the UK Cochrane Centre, and summary details of these trials were entered into Medline for use by clinicians and investigators in the future.

Adult↗

PubMed1999

The effectiveness of slow-stroke massage in diffusing agitated behaviors in individuals with Alzheimer's disease.

Agitated behaviors of individuals with Alzheimer's disease (AD), often endured or unsuccessfully treated with chemical or physical restraints, markedly increase the stress levels of family caregivers. The Theoretical Model for Aggression in the Cognitively Impaired guided the examination of caregiver-provided slow-stroke massage on the diffusion of actual and potential agitation for community-dwelling individuals with AD. Characteristics and frequency of agitation were quantified by two highly correlated instruments, the Agitated Behavior Rating Scale Scoring Guide and the Brief Behavior Symptom Rating Scale. Expressions of agitation of patients with AD increased in a linear pattern from dawn to dusk. Verbal displays of agitation, the most frequently cited form of agitation in community-dwelling individuals with AD, were not diffused by slow-stroke massage. However, the more physical expressions of agitation such as pacing, wandering, and resisting were decreased when slow-stroke massage was applied. This study contributes to building a body of knowledge regarding the phenomenon of agitated behaviors in cognitively impaired elderly individuals--its nature, frequency of occurrence, measurement, associated factors, and management.

Aged↗

PubMed1999

Handsearching the Journal of the Royal Naval Medical Service for Trials.

As part of the Cochrane Collaboration's international research endeavour, the authors carried out a handsearch of the Journal of the Royal Naval Medical Service from 1948 to 1998, searching for randomised controlled trials (RCTs) and controlled clinical trials (CCTs). Five trials were identified, of which three were RCTs and two were CCTs. The first trial was published in 1960. The identified trials were in the fields of dentistry (two trials), gastroenterology, occupational medicine and orthopaedic surgery. Of the five trials, only two had been located previously through a rigorous interrogation of Medline. The three newly identified trials were reported to the UK Cochrane Centre, and details of these three trials were entered into Medline for use by clinicians and investigators in the future.

Controlled Clinical Trials as Topic↗

PubMed1998

Epstein-Barr virus latent membrane protein-1 (LMP1) signalling is distinct from CD40 and involves physical cooperation of its two C-terminus functional regions.

The Epstein-Barr virus (EBV) encoded Latent Membrane Protein-1 (LMP1) mimics a constitutively active receptor molecule, and has been shown to activate NF-kappaB and the MAPK and JNK pathways. Two regions within the cytosolic domain of LMP1 have been found to effect cell signalling. One of these, the carboxy-terminal activation region-1 (CTAR1), binds members of the TRAF family of proteins, and the other (CTAR2) binds TRADD, suggesting that LMP1 transduces signals similarly to the Tumour Necrosis Factor Receptor family of receptors. The ability to bind TRAFs, to activate NF-kappaB and the JNK pathway, to upregulate cellular genes such as CD54 (ICAM-1 adhesion molecule), and to affect cell growth and apoptosis has led to the suggestion that LMP1 signalling is similar to, or even identical to CD40. However, we now show that while ligand-induced CD40 signalling is impaired in the Jurkat T cell line, LMP1 was fully functional; therefore demonstrating that LMP1 and CD40 signalling differ. Mutated LMP1 genes, in which one or other of the CTAR1 and CTAR2 domains was non-functional, behaved more like CD40 in being unable to upregulate the CD54 cell surface marker in Jurkat cells. However, the CTAR1 domain of LMP1, which shared a TRAF-binding sequence motif with CD40, differed from CD40 in being unable to activate NF-kappaB in Jurkat. Cotransfection experiments with LMP1 mutants demonstrated that CTAR1 can cooperative with CTAR2 on separate LMP1 molecules, provided that they exist within the same oligomeric complex.

CD40 Antigens↗