bluuebunny/crossref_metadata_2025 huggingface dataset:
Left Ventricular Unloading in a Patient with End‐stage Cardiomyopathy and Medically Unresponsive Pulmonary Hypertension
Authors: Al‐Khaldi Abdulaziz , Ergina Patrick , DeVarennes Benoit , Lachappelle Kevin , Cecere Renzo
Published: February 2004

Abstract:  Severe, medically unresponsive pulmonary hypertension (PHT) is considered to be a contraindication for orthotopic heart transplantation (OHT). Chronic left ventricular (LV) unloading using a left ventricular assist device (LVAD) might result in reversal of the elevated pulmonary vascular resistance (PVR), allowing successful OHT in such patients. In this study, we present a patient with end‐stage ischemic cardiomyopathy and fixed, elevated PVR (7.1 Wood units) who underwent implantation of a Novacor LVAD (Baxter Healthcare Corp., Deerfield, IL, U.S.A.), with a subsequent reduction in PVR to 1.2 Wood units and successful OHT eleven months post‐LVAD implantation. Three years after heart transplant, the patient still leads an active life with no right heart failure. In conclusion, OHT is not contraindicated in patients with end‐stage heart failure and medically unresponsive PHT in the presence of elevated left atrial pressure. Left ventricular unloading should be considered in these patients to allow reversal of the elevated PVR before OHT.
Bone Marrow Cells in the Repair and Modulation of Heart and Blood Vessels: Emerging Opportunities in Native and Engineered Tissue and Biomechanical Materials
Authors: Rezai Nana , Podor Thomas J. , McManus Bruce M.
Published: February 2004

Abstract:  Adult bone marrow‐derived stem/progenitor cells have traditionally been considered to be tissue‐specific cells with limited capacity for differentiation. However, recent discoveries have generated tremendous excitement regarding possible applications of stem cells, particularly bone marrow‐derived stem cells, in the treatment of human diseases. The potential ability to regenerate cells of various different lineages has raised the therapeutic possibility of using these bone marrow‐derived stem cells as a source of cells for tissue repair and regeneration. Tissue engineering is a rapidly expanding interdisciplinary field aimed at restoring function to tissues through the delivery of constructs which become integrated into the patient. The use of bone marrow‐derived stem cells provides a less invasive source for cells applicable to tissue engineering, including cardiovascular tissues such as heart valves, blood vessels, and myocardium. Although these strategies are in the early stages of development, they are conceptually promising and offer important insights into the future treatment of various cardiovascular  ailments.
Improved Early Survival with the Total Artificial Heart
Authors: Haddad Michel , Masters Roy G. , Hendry Paul J. , Mesana Thierry , Haddad Haissam , Davies Ross A. , Mussivand Tofy V. , Struthers Christine , Keon Wilbert J.
Published: February 2004

Abstract:  We report our experience with the total artificial heart (TAH) to determine if outcomes have improved. Thirty‐one patients received the TAH as a bridge to transplant and were divided into the two groups A (eighteen implanted in the first eight years) and B (thirteen implanted in the last eight years). Changes in management included immediate sternal closure, early extubation, delayed transplant listing, early rehabilitation, and measurement of preformed antibodies. The infection rate in B was lower than in A, both during support (31% versus 39%) and following transplant (38% versus 72%), and rejection was lower in B than in A (0% versus 44%). There was no difference in neurological events between groups; however, reopening was more frequent in B (61% versus 28%). Hospital survival increased from 61% in A to 85% in B; however, this was not statistically significant. We hypothesize that this improvement was likely due to changes in patient management.
Therapeutic Left Ventricular Assist Device and Apheresis on Dilated Cardiomyopathy
Authors: Matoba Yoshica , Okubo Hisashi , Nosé Yukihiko
Published: February 2004

Abstract:  Pathogenesis and therapies of dilated cardiomyopathy (DCM) have been discussed for a long time, but both of the ultimate answers are still unknown. In the last decade, the pathogenic role of immunological factors, such as cardiac autoimmune antibodies and cytokines, have been discussed attentively. This has led to one possible new therapy, immunoadsorption, which removes antibodies, and it has made a remarkable effect. However, there are other factors to remove. For the removal of cytokines and neurohormones, the most effective method is hemofiltration (HF). Also, double‐filtration plasmapheresis (DFPP) removes immunoglobulin as well as low‐density lipoprotein (LDL) and coagulation factors that may improve blood circulation, including the coronary arteries. Therefore, to eliminate all deteriorative factors, both apheresis therapies, HF and DFPP, should be performed.

Due to the shortage of donor hearts, left ventricular assist systems (LVAD) have been used as a bridge to transplantation. It has now been reported that the total unloading of the left ventricle does not only maintain, but also recovers, the cardiac function, even from end‐stage heart failure. However, the patients who have obtained a long‐lasting recovery of cardiac function from an LVAD are still in a minority. To make this the majority, therapeutic LVAD should be combined with the apheresis therapies, DFPP and HF. We believe that this concept, a combination of HF and DFPP with therapeutic LVAD, will be the next generation of treatment that has a potential to postpone, or even avoid, heart transplantation.
Cohabiting and Married Couples' Income Organization: Approaches in Sweden and the United States
Authors: Heimdal Kristen R. , Houseknecht Sharon K.
Published: February 2004

Using 1994 International Social Survey Program (ISSP) data, we examine the effect that cohabitation versus marriage has on couples' income organization approaches in Sweden and the United States, two legally and normatively different contexts. Previous research on this topic has focused almost exclusively on married couples, so our inclusion of both married and cohabiting couples helps fill a gap in the literature. The effects of ever having been divorced, socioeconomic homogamy, and traditional gender ideology also are explored. Type of relationship and ever having been divorced are the only variables that predict income organization approach in both countries, suggesting that relationship experiences are more important than socioeconomic or ideological factors.
The Relationship Between Cohabitation and Marital Quality and Stability: Change Across Cohorts?
Authors: Dush Claire M. Kamp , Cohan Catherine L. , Amato Paul R.
Published: February 2004

The relationship between premarital cohabitation and marital dysfunction was examined with a total sample of 1,425 spouses in two U.S. marriage cohorts: those married between 1964 and 1980 (when cohabitation was less common) and those married between 1981 and 1997 (when cohabitation was more common). Spouses in both cohorts who cohabited prior to marriage reported poorer marital quality and greater marital instability. When selection factors for cohabitation and subsequent marital instability were included in the statistical model, cohabitors in both cohorts continued to exhibit poorer marital quality and greater marital instability. These findings lend stronger support to an experience of cohabitation perspective than to a selection perspective as an explanation for why couples who cohabit before marriage tend to have more troubled relationships.
African American and European American Women's Marital Well‐Being
Authors: Goodwin Paula Y.
Published: February 2004

Using a sample of 247 African American and European American women in their 3rd year of marriage, this study compared the predictors of marital well‐being for each group by focusing on the influences of individual, interpersonal, and social and economic resources. Regression analyses revealed that emotional health (individual), trusting one's spouse (interpersonal), and feeling underbenefited in the relationship (interpersonal) were significant predictors of marital well‐being for both groups of women. Physical health (individual) and in‐law relations (social and economic), however, affected the marital well‐being of only African American women. Findings from this study suggest the need to examine marital well‐being within the context of race.
Why Stay Married? Rewards, Barriers, and Marital Stability
Authors: Previti Denise , Amato Paul R.
Published: February 2004

This paper describes people's open‐ended, personal accounts of why they stay married. Most people perceived the cohesiveness of their marriages in terms of rewards and barriers, and few people referred to a lack of good alternatives. People who reported barriers only tended to be relatively unhappy with their marriages and were more likely than other individuals to be thinking about divorce. People who reported barriers only, compared with people who reported rewards only, were more likely to divorce during the next 14 years. This association was significant even after controlling for marital happiness and divorce proneness.
Parenthood and Marital Satisfaction: A Meta‐Analytic Review
Authors: Twenge Jean M. , Campbell W. Keith , Foster Craig A.
Published: February 2004

This meta‐analysis finds that parents report lower marital satisfaction compared with nonparents (d=−.19, r=−.10). There is also a significant negative correlation between marital satisfaction and number of children (d=−.13, r=−.06). The difference in marital satisfaction is most pronounced among mothers of infants (38% of mothers of infants have high marital satisfaction, compared with 62% of childless women). For men, the effect remains similar across ages of children. The effect of parenthood on marital satisfaction is more negative among high socioeconomic groups, younger birth cohorts, and in more recent years. The data suggest that marital satisfaction decreases after the birth of a child due to role conflicts and restriction of freedom.
A Multilevel Analysis of Child Care and Women's Fertility Decisions in Western Germany
Authors: Hank Karsten , Kreyenfeld Michaela
Published: February 2004

The availability of public day care is often assumed to be crucial to the compatibility of childrearing and women's employment. This article takes a multilevel perspective in investigating the role of child care in childbearing decisions in western Germany. Using information on the local supply of public day care and data from the German Socio‐Economic Panel, we estimated first and second birth risks from the 1980s and 1990s. We found that access to informal care arrangements increases the probability of entering parenthood, but we did not find any statistically significant effect of the public day care provision on fertility. This result points to shortcomings in the institutional setup of the German day care (and welfare) regime and to potentially relevant unobserved dimensions of child care.
Has the Price of Motherhood Declined Over Time? A Cross‐Cohort Comparison of the Motherhood Wage Penalty
Authors: Avellar Sarah , Smock Pamela J.
Published: February 2004

Several recent studies have shown a negative association between motherhood and wages. However, an analysis of change over time in the motherhood penalty has not been conducted. Using two cohorts of young women drawn from the 1975–1985 National Longitudinal Survey of Young Women and the 1986–1998 National Longitudinal Survey of Youth, we explicitly test the relationship between motherhood and wages across two cohorts and examine whether that relationship has changed. Even after controlling for unobserved heterogeneity and human capital variables, each additional child is associated with a negative effect on women's wages. Moreover, our findings suggest that the penalty has not diminished over time.
What Parents Learn From Experience: The First Child as a First Draft?
Authors: Whiteman Shawn D. , McHale Susan M. , Crouter Ann C.
Published: February 2004

This study sought evidence for the proposition that experiences with earlier‐born adolescents will improve parents' interactions with and parenting of later‐born adolescents. Participants were mothers, fathers, and both first‐ and second‐born siblings from 392 families participating in a longitudinal study. To collect information on siblings' family experiences, family members were interviewed individually in their homes. During the subsequent 2 to 3 weeks, 7 evening telephone interviews were also conducted, which focused on siblings' daily activities. Findings suggest that when parent‐adolescent relationships were measured at the same age for both siblings, parents experienced less conflict with their second‐born as compared with their firstborn adolescent offspring and exhibited greater knowledge of their second‐born offspring's daily activities as compared with their firstborns' daily experiences. These results are consistent with the notion that parents may learn from their childrearing experiences.
The Infrequency of Family Violence
Authors: Felson Richard B. , Ackerman Jeff , Yeon Seong‐Jin
Published: February 2004

We examined the frequency of domestic violence and verbal altercations relative to the level of domestic conflict using survey data from the United States and Korea. We found evidence that individuals are generally less likely to use violence during an altercation if the antagonist is a family member than if the antagonist is a stranger. People apparently have stronger inhibitions about hitting family members than about hitting strangers, and, as a result, domestic violence is infrequent relative to the level of domestic conflict. In addition, verbal altercations are more likely to occur in conflicts with partners and children than in conflicts involving strangers, suggesting that the relaxation of rules of politeness contributes to the expression of grievances and ultimately the use of violence in these relationships.
A Typology of Maritally Violent Men and Correlates of Violence in a Community Sample
Authors: Delsol Catherine , Margolin Gayla , John Richard S.
Published: February 2004

This study empirically tests A. Holtzworth‐Munroe and G. L. Stuart's (1994) typology of male batterers in a community sample. Latent class analyses based on severity of physical aggression, generality of violence, and psychopathology partially replicated the Holtzworth‐Munroe and Stuart typology by identifying 3 types of violent men: family‐only, medium‐violence, and generally violent/psychologically distressed. Separate groupings of borderline/dysphoric and generally violent/antisocial types were not found. In comparisons of batterer types to each other and to nonviolent men, generally violent/psychologically distressed men differed from other groups on psychological abuse, life stress, marital satisfaction, and attitudes about violence. Types also differed on wives' fearfulness of their husband and injury from marital aggression. Implications of conceptualizing marital violence from a multidimensional typology perspective are discussed.
Establishing Independence in Low‐Income Urban Areas: The Relationship to Adolescent Aggressive Behavior
Authors: Roche Kathleen M. , Ensminger Margaret E. , Chilcoat Howard , Storr Carla
Published: February 2004

Although adolescents in poor urban areas often assume independent, adult‐like roles, relatively little is known about the relationship between these roles and other adolescent behaviors. This research examines the association between independent roles occurring within different contexts (e.g. family, peer, work) and aggressive behavior among 516 low‐income, urban middle school students. Overall, adolescent employment is related to increases in aggressive behavior. However, associations that familial and peer independent roles have with aggression differ by the extent of youth involvement in paid work. Greater engagement in familial independent roles is associated with decreased aggression among employed adolescents, but with increased aggression among unemployed youth. Also, peer independent roles are related to significantly greater increases in aggression among unemployed, compared with employed, adolescents.
Family Policies and Children's School Achievement in Single‐ Versus Two‐Parent Families
Authors: Pong Suet‐ling , Dronkers Jaap , Hampden‐Thompson Gillian
Published: February 2004

We investigate the gap in math and science achievement of third‐ and fourth‐graders who live with a single parent versus those who live with two parents in 11 countries. The United States and New Zealand rank last among the countries we compare in terms of the equality of achievement between children from single‐parent families and those from two‐parent homes. Following a multilevel analysis, we find single parenthood to be less detrimental when family policies equalize resources between single‐ and two‐parent families. In addition, the single‐ and two‐parent achievement gap is greater in countries where single‐parent families are more prevalent. We conclude that national family policies can offset the negative academic outcomes of single parenthood.
Parental Housing Assistance and Parent‐Child Proximity in Italy
Authors: Tomassini Cecilia , Wolf Douglas A. , Rosina Alessandro
Published: February 2004

Many studies of intergenerational exchanges include parent‐child proximity as an exogenous explanatory variable. Proximity may itself be a consequence of intergenerational resource flows, however. We analyze patterns of economic transfers between generations and their relationship to parent‐child proximity in Italy. Parental support for a child's home purchase may influence the child's choice of location, whether to facilitate parent‐child contacts, grandchild care, or parent care. We examine the situation of married couples, focusing on housing help received and the association of that help with proximity to each spouse's parents. Using 1998 survey data and multinomial logistic regression models, we find that past housing assistance has a significant effect on current proximity to each spouse's parents, controlling for parents' survival, family composition, and other factors.
Identifying the Effects of Income on Children's Development Using Experimental Data
Authors: Morris Pamela A. , Gennetian Lisa A.
Published: February 2004

Prior research suggests that poverty can be detrimental to low‐income children's development. Is this relation capturing the effects of poverty or the effects of other characteristics of low‐income families associated with poverty? Can low‐income children benefit from increases in income? In this paper, an instrumental variables estimation strategy is used with data on nearly 900 children from a random assignment evaluation of a pilot welfare reform program in Minnesota in order to answer these questions and to identify the causal effects of income on children's development. There are some suggestions that increased income improves the development of low‐income children, at least with regard to their school engagement and positive social behavior. Results are discussed with regard to their implication for analysis, as well as research and policy.
Neighborhood Structure, Social Organization, and Number of Short‐Term Sexual Partnerships
Authors: Browning Christopher R. , Olinger‐Wilbon Matisa
Published: February 2004

We examine the relationship between neighborhood structural characteristics, social organization, and the sexual partnering practices of adults. Analyses of 1990 census and 1995–1997 survey‐based data on Chicago neighborhoods and adult sexual activity reveal for men a number of neighborhood influences on sexual partnering practices. First, residential stability is negatively associated with having a short‐term sexual partner in the last year. Second, neighborhood social ties are positively associated with short‐term sexual partnering in neighborhoods with low levels of collective efficacy—the combination of cohesion and shared expectations for beneficial action among neighbors—but this effect is substantially reduced as collective efficacy increases. Moreover, neighborhood collective efficacy and social ties mediate the effect of residential stability on sexual partnering practices. Neighborhood characteristics were not associated with short‐term sexual partnering for women.
Explaining the Decline in Women's Household Labor: Individual Change and Cohort Differences
Authors: Artis Julie E. , Pavalko Eliza K.
Published: February 2004

Women's hours of housework have declined, but does this change represent shifts in the behavior of individuals or differences across cohorts? Using data from the National Longitudinal Surveys, individual and cohort change in housework are examined over a 13‐year period. Responsibility for household tasks declined 10% from 1974–75 to 1987–88. For individual women, changes in housework are associated with life course shifts in time availability as well as with changes in gender attitudes and marital status, but are not related to changes in relative earnings. Cohort differences exist in responsibility for housework in the mid‐1970s and they persist over the 13‐year period. Overall, these findings suggest that aggregate changes in women's household labor reflect both individual change and cohort differences.
Underrepresentation of the 3′ Region of the Capsid Pregenomic RNA of Duck Hepatitis B Virus
Authors: Ostrow Kristin M. , Loeb Daniel D.
Published: February 2004

The pregenomic RNA (pgRNA) of hepadnaviruses is packaged into capsids where it is reverse transcribed to yield mature DNA genomes. This report describes differences between the 3′ region and other regions of the pgRNA isolated from capsids. Analysis of capsid pgRNA isolated by using an established method involving micrococcal nuclease treatment demonstrated reduced levels of the 3′ region of the pgRNA compared to the 5′ region. This underrepresentation of the 3′ region was partly a result of microccocal nuclease digestion of the 3′ region because isolation of capsid pgRNA by an alternative method that did not involve nuclease treatment led to a greater, but not complete, recovery of the 3′ region. These results indicate that the 3′ region of the capsid pgRNA is susceptible to micrococcal nuclease digestion during its isolation and that the 3′ region can still be underrepresented when capsid pgRNA is isolated without nuclease digestion. Additional experiments show that the 3′ ends of capsid pgRNA isolated by micrococcal nuclease treatment are heterogeneously dispersed from nucleotide 2577 to the poly(A) tail. These data provide evidence that the 3′ region of the capsid pgRNA has biochemical properties different from those of its 5′ region. Possibly, the 3′ region of the pgRNA is not packaged into the interior of the capsid but rather is associated with a part of the capsid where it is susceptible to microccocal nuclease digestion.
Transforming Growth Factor β Enhances the Glucocorticoid Response of the Mouse Mammary Tumor Virus Promoter through Smad and GA-Binding Proteins
Authors: Aurrekoetxea-Hernández Koldo , Buetti Elena
Published: February 2004

Tissue-specific transcription is advantageously investigated by using viral promoters, which are selected for compact regulatory elements. Mouse mammary tumor virus (MMTV) has adapted to specialized cell types and targets initially B lymphocytes. We previously showed that, in B-cell lines, glucocorticoid-induced MMTV transcription requires an ETS family factor, GA-binding protein (GABP), bound in tandem to the MMTV DNA next to the glucocorticoid receptor (GR). We now report that transforming growth factor β (TGF-β) superinduces this response up to 10-fold through binding of its effectors, Smads, between the GABP-binding motifs. The basal level was unaffected. The TGF-β-glucocorticoid cooperation also depended on GR and GABP binding, was transferable to another promoter, and occurred both with transiently transfected and with integrated templates. Smad3 associated in vitro with GR, with GABPα (via the MH2 domain), and with GABPβ, Smad4 only with GABPα. Interactions of Smad3 with GABP (when coexpressed or endogenous to B cells) were shown by coprecipitation and by mammalian two-hybrid assay. This composite DNA element integrates three signaling pathways deriving from TGF-β, glucocorticoid hormones, and a unique ETS factor, and may allow MMTV to exploit factors from the milk. It may as well indicate novel possibilities for cellular regulatory networks.
Protection against Mucosal Simian Immunodeficiency Virus SIV
mac251
Challenge by Using Replicating Adenovirus-SIV Multigene Vaccine Priming and Subunit Boosting
Authors: Patterson L. Jean , Malkevitch Nina , Venzon David , Pinczewski Joel , Gómez-Román Victor Raúl , Wang Liqun , Kalyanaraman V. S. , Markham Phillip D. , Robey Frank A. , Robert-Guroff Marjorie
Published: February 2004

Whereas several recent AIDS vaccine strategies have protected rhesus macaques against a pathogenic simian/human immunodeficiency virus (SHIV)
89.6P
challenge, similar approaches have provided only modest, transient reductions in viral burden after challenge with virulent, pathogenic SIV, which is more representative of HIV infection of people. We show here that priming with replicating adenovirus recombinants encoding SIV
env/rev
,
gag
, and/or
nef
genes, followed by boosting with SIV gp120 or an SIV polypeptide mimicking the CD4 binding region of the envelope, protects rhesus macaques from intrarectal infection with the highly pathogenic SIV
mac251
. Using trend analysis, significant reductions in acute-phase and set point viremia were correlated with anti-gp120 antibody and cellular immune responses, respectively. Within immunization groups exhibiting significant protection, a subset (39%) of macaques have exhibited either no viremia, cleared viremia, or controlled viremia at the threshold of detection, now more than 40 weeks postchallenge. This combination prime-boost strategy, utilizing replication competent adenovirus, is a promising alternative for HIV vaccine development.
Specificity of Interaction of INI1/hSNF5 with Retroviral Integrases and Its Functional Significance
Authors: Yung Eric , Sorin Masha , Wang Emilie-Jeanne , Perumal Seena , Ott David , Kalpana Ganjam V.
Published: February 2004

Integrase interactor 1 (INI1)/hSNF5 is a host factor that directly interacts with human immunodeficiency virus type 1 (HIV-1) integrase and is incorporated into HIV-1 virions. Here, we show that while INI1/hSNF5 is completely absent from purified microvesicular fractions, it is specifically incorporated into HIV-1 virions with an integrase-to-INI1/hSNF5 stoichiometry of approximately 2:1 (molar ratio). In addition, we show that INI1/hSNF5 is not incorporated into related primate lentiviral and murine retroviral particles despite the abundance of the protein in producer cells. We have found that the specificity in incorporation of INI1/hSNF5 into HIV-1 virions is directly correlated with its ability to exclusively interact with HIV-1 integrase but not with other retroviral integrases. This specificity is also reflected in our finding that the transdominant mutant S6, harboring the minimal integrase interaction domain of INI1/hSNF5, blocks HIV-1 particle production but not that of the other retroviruses in 293T cells. Taken together, these results suggest that INI1/hNSF5 is a host factor restricted for HIV-1 and that S6 acts as a highly specific and potent inhibitor of HIV-1 replication.
Genetic Basis of Hypersusceptibility to Protease Inhibitors and Low Replicative Capacity of Human Immunodeficiency Virus Type 1 Strains in Primary Infection
Authors: Leigh Brown Andrew J. , Frost Simon D. W. , Good Benjamin , Daar Eric S. , Simon Viviana , Markowitz Martin , Collier Ann C. , Connick Elizabeth , Conway Brian , Margolick Joseph B. , Routy Jean-Pierre , Corbeil Jacques , Hellmann Nicholas S. , Richman Douglas D. , Little Susan J.
Published: February 2004

The initial virus strains from as many as 12% of individuals with primary human immunodeficiency virus (HIV) infection have a 50% inhibitory concentration ≤0.4-fold that of HIV type 1NL4-3(HIV-1NL4-3) to ritonavir (hypersusceptibility [HS]). There is also substantial variation in replicative capacity (RC) or an in vitro assay of the contributions of protease (PR) and reverse transcriptase to viral fitness. In chronically infected antiretrovirally treated patients, amprenavir HS has been associated with the mutation N88S in PR, but this mutation is not seen in untreated patients. In this study, virus strains from 182 cases of primary HIV infection were analyzed, and a highly significant association between HS and low RC (≤10% that of HIV-1NL4-3) was observed (P< 10−6). Multivariate analysis was used to determine the genotypic basis of ritonavir HS, analyzing all polymorphic amino acid sites and insertions from p7gag through PR. Decision tree models developed on the entire Gag-plus-PR data set and on PR alone gave overall correct classifications of 73 and 72%, respectively, on cross-validation. They were also able to predict low RC, with sensitivities of 69 and 62% and specificities of 84 and 70%, respectively. The analysis shows that ritonavir HS in untreated primary HIV infection is not associated with single mutations but with combinations of amino acids at polymorphic sites and that the same genotypes which confer HS to PR inhibitors confer low RC. This supports the view that variation in PR function is directly responsible for variation in fitness among strains in primary infection.
Underwhelming the Immune Response: Effect of Slow Virus Growth on CD8+-T-Lymphocyte Responses
Authors: Bocharov Gennady , Ludewig Burkhard , Bertoletti Antonio , Klenerman Paul , Junt Tobias , Krebs Philippe , Luzyanina Tatyana , Fraser Cristophe , Anderson Roy M.
Published: February 2004

The speed of virus replication has typically been seen as an advantage for a virus in overcoming the ability of the immune system to control its population growth. Under some circumstances, the converse may also be true: more slowly replicating viruses may evoke weaker cellular immune responses and therefore enhance their likelihood of persistence. Using the model of lymphocytic choriomeningitis virus (LCMV) infection in mice, we provide evidence that slowly replicating strains induce weaker cytotoxic-T-lymphocyte (CTL) responses than a more rapidly replicating strain. Conceptually, we show a “bell-shaped” relationship between the LCMV growth rate and the peak CTL response. Quantitative analysis of human hepatitis C virus infections suggests that a reduction in virus growth rate between patients during the incubation period is associated with a spectrum of disease outcomes, from fulminant hepatitis at the highest rate of viral replication through acute resolving to chronic persistence at the lowest rate. A mathematical model for virus-CTL population dynamics (analogous to predator [CTL]-prey [virus] interactions) is applied in the clinical data-driven analysis of acute hepatitis B virus infection. The speed of viral replication, through its stimulus of host CTL responses, represents an important factor influencing the pathogenesis and duration of virus persistence within the human host. Viruses with lower growth rates may persist in the host because they “sneak through” immune surveillance.
Expansion of Protective CD8+T-Cell Responses Driven by Recombinant Cytomegaloviruses
Authors: Karrer Urs , Wagner Markus , Sierro Sophie , Oxenius Annette , Hengel Hartmut , Dumrese Tilman , Freigang Stefan , Koszinowski Ulrich H. , Phillips Rodney E. , Klenerman Paul
Published: February 2004

CD8+T cells are critical for the control of many persistent viral infections, such as human immunodeficiency virus, hepatitis C virus, Epstein-Barr virus, and cytomegalovirus (CMV). In most infections, large CD8+-T-cell populations are induced early but then contract and are maintained thereafter at lower levels. In contrast, CD8+T cells specific for murine CMV (MCMV) have been shown to gradually accumulate after resolution of primary infection. This unique behavior is restricted to certain epitopes, including an immunodominant epitope derived from the immediate-early 1 (IE1) gene product. To explore the mechanism behind this further, we measured CD8+-T-cell-mediated immunity induced by recombinant MCMV-expressing epitopes derived from influenza A virus or lymphocytic choriomeningitis virus placed under the control of an IE promoter. We observed that virus-specific CD8+-T-cell populations were induced and that these expanded gradually over time. Importantly, these CD8+T cells provided long-term protection against challenge without boosting. These results demonstrate a unique pattern of accumulating T cells, which provide long-lasting immune protection, that is independent of the initial immunodominance of the epitope and indicates the potential of T-cell-inducing vaccines based on persistent vectors.
Promoting Trimerization of Soluble Human Immunodeficiency Virus Type 1 (HIV-1) Env through the Use of HIV-1/Simian Immunodeficiency Virus Chimeras
Authors: Center Rob J. , Lebowitz Jacob , Leapman Richard D. , Moss Bernard
Published: February 2004

The envelope proteins (Env) of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) form homo-oligomers in the endoplasmic reticulum. The oligomeric structure of Env is maintained, but is less stable, after cleavage in a Golgi compartment and transport to the surface of infected cells. Functional, virion-associated HIV-1 and SIV Env have an almost exclusively trimeric structure. In addition, a soluble form of SIV Env (gp140) forms a nearly homogeneous population of trimers. Here, we describe the oligomeric structure of soluble, uncleaved HIV-1 gp140 and modifications that promote a stable trimeric structure. Biochemical and biophysical analyses, including sedimentation equilibrium and scanning transmission electron microscopy, revealed that unmodified HIV-1 gp140 purified as a heterogeneous range of oligomeric species, including dimers and aggregates. Deletion of the V2 domain alone or, especially, both the V1 and V2 domains reduced dimer formation but promoted aggregation rather than trimerization. Expressing gp140 with mannose-only oligosaccharides did not eliminate heterogeneity. Replacement of the entire gp41 segment of HIV-1 gp140 or just the N-terminal half (85 amino acids) of this segment with the corresponding region of SIV was sufficient to confer efficient trimerization for gp140 derived from clade B and C isolates. Importantly, the relatively small segment of the HIV Env replaced by SIV sequences contains no known targets of neutralizing antibody. The soluble trimeric form of HIV-1 Env should prove useful for assessment of antigenic structure and immunogenicity.
Role for CCR5Δ32 Protein in Resistance to R5, R5X4, and X4 Human Immunodeficiency Virus Type 1 in Primary CD4+Cells
Authors: Agrawal Lokesh , Lu Xihua , Qingwen Jin , VanHorn-Ali Zainab , Nicolescu Ioan Vlad , McDermott David H. , Murphy Philip M. , Alkhatib Ghalib
Published: February 2004

CCR5Δ32is a loss-of-function mutation that abolishes cell surface expression of the human immunodeficiency virus (HIV) coreceptor CCR5 and provides genetic resistance to HIV infection and disease progression. Since CXCR4 and other HIV coreceptors also exist, we hypothesized thatCCR5Δ32-mediated resistance may be due not only to the loss of CCR5 function but also to a gain-of-function mechanism, specifically the active inhibition of alternative coreceptors by the mutant CCR5Δ32 protein. Here we demonstrate that efficient expression of the CCR5Δ32 protein in primary CD4+cells by use of a recombinant adenovirus (Ad5/Δ32) was able to down-regulate surface expression of both wild-type CCR5 and CXCR4 and to confer broad resistance to R5, R5X4, and X4 HIV type 1 (HIV-1). This may be important clinically, since we found that CD4+cells purified from peripheral blood mononuclear cells of individuals who were homozygous forCCR5Δ32, which expressed the mutant protein endogenously, consistently expressed lower levels of CXCR4 and showed less susceptibility to X4 HIV-1 isolates than cells from individuals lacking the mutation. Moreover, CD4+cells from individuals who were homozygous forCCR5Δ32expressed the mutant protein in five of five HIV-exposed, uninfected donors tested but not in either of two HIV-infected donors tested. The mechanism of inhibition may involve direct scavenging, since we were able to observe a direct interaction of CCR5 and CXCR4 with CCR5Δ32, both by genetic criteria using the yeast two-hybrid system and by biochemical criteria using the coimmunoprecipitation of heterodimers. Thus, these results suggest that at least two distinct mechanisms may account for genetic resistance to HIV conferred byCCR5Δ32: the loss of wild-type CCR5 surface expression and the generation of CCR5Δ32 protein, which functions as a scavenger of both CCR5 and CXCR4.
A Cysteine-Rich Plant Protein Potentiates
Potyvirus
Movement through an Interaction with the Virus Genome-Linked Protein VPg
Authors: Dunoyer P. , Thomas C. , Harrison S. , Revers F. , Maule A.
Published: February 2004

We have identified a cellular factor that interacts with the virus genome-linked proteins (VPgs) of a diverse range of potyviruses. The factor, called
Potyvirus
VPg-interacting protein (PVIP), is a plant-specific protein with homologues in all the species examined, i.e., pea,
Arabidopsis thaliana
, and
Nicotiana benthamiana
. The sequence of PVIP does not identify a specific function, although the existence of a “PHD finger” domain may implicate the protein in transcriptional control through chromatin remodeling. Deletion analysis using the yeast two-hybrid system showed that the determinants of the interaction lay close to the N terminus of VPg; indeed, the N-terminal 16 amino acids were shown to be both necessary and sufficient for the interaction with at least one PVIP protein. From a sequence comparison of different potyvirus VPg proteins, a specific amino acid at position 12 was directly implicated in the interaction. This part of VPg is distinct from regions associated with other functional roles of VPg. Through mutation of
Turnip mosaic virus
(TuMV) at VPg position 12, we showed that the interaction with PVIP affected systemic symptoms in infected plants. This resulted from reduced cell-to-cell and systemic movement more than reduced virus replication, as visualized by comparing green fluorescent protein-tagged wild-type and mutant viruses. Furthermore, by using RNA interference of PVIP in
Arabidopsis
, we showed that reduced expression of
PVIP
genes reduced susceptibility to TuMV infection. We conclude that PVIP functions as an ancillary factor to support potyvirus movement in plants.
Characterization of Rotavirus Cell Entry
Authors: Sánchez-San Martín Claudia , López Tomás , Arias Carlos F. , López Susana
Published: February 2004

While recently we have learned much about the viral and cellular proteins involved in the initial attachment of rotaviruses to MA104 cells, the mechanism by which these viruses reach the interior of the cell is poorly understood. For this study, we observed the effects of drugs and of dominant-negative mutants, known to impair clathrin-mediated endocytosis and endocytosis mediated by caveolae, on rotavirus cell infection. Rotaviruses were able to enter cells in the presence of compounds that inhibit clathrin-mediated endocytosis as well as cells overexpressing a dominant-negative form of Eps15, a protein crucial for the assembly of clathrin coats. We also found that rotaviruses infected cells in which caveolar uptake was blocked; treatment with the cholesterol binding agents nystatin and filipin, as well as transfection of cells with dominant-negative caveolin-1 and caveolin-3 mutants, had no effect on rotavirus infection. Interestingly, cells treated with methyl-β-cyclodextrin, a drug that sequesters cholesterol from membranes, and cells expressing a dominant-negative mutant of the large GTPase dynamin, which is known to function in several membrane scission events, were not infected by rotaviruses, indicating that cholesterol and dynamin play a role in the entry of rotaviruses.
Role of Human Immunodeficiency Virus Type 1 Matrix Phosphorylation in an Early Postentry Step of Virus Replication
Authors: Kaushik Rajnish , Ratner Lee
Published: February 2004

The matrix domain (MA) is important for targeting of human immunodeficiency virus type 1 Gag assembly to the plasma membrane, envelope incorporation into virions, preintegration complex import into the nucleus, and nuclear export of viral RNA. Myristylation and phosphorylation are key regulatory events for MA function. Previous studies have indicated that MA phosphorylation at serine (Ser) residues is important for viral replication. This study defines the molecular mechanisms of virus particle assembly and infectivity through a detailed study of the role of MA serine phosphorylation. We show that the combined mutation of Ser residues at positions 9, 67, 72, and 77 impairs viral infectivity in dividing and nondividing cells, although the assembly of these Ser mutant viruses is comparable to that of wild-type virus. This defect can be rescued by pseudotyping these mutant viruses with vesicular stomatitis virus G protein, suggesting that these serine residues are critical in an early postentry step of viral infection. The phosphorylation level of MA in defective mutant viruses was severely reduced compared to that of the wild type, suggesting that phosphorylation of Ser-9, -67, -72, and -77 is important for an early postentry step during virus infection.
Cell Cycle Requirements for Transduction by Foamy Virus Vectors Compared to Those of Oncovirus and Lentivirus Vectors
Authors: Trobridge Grant , Russell David W.
Published: February 2004

Retroviral vectors based on foamy viruses (FV) are efficient gene delivery vehicles for therapeutic and research applications. While previous studies have shown that FV vectors transduce quiescent cell cultures more efficiently than oncoviral vectors, their specific cell cycle requirements have not been determined. Here we compare the transduction frequencies of FV vectors with those of onco- and lentiviral vectors in nondividing and dividing normal human fibroblasts by several methods. FV vectors transduced serum-deprived fibroblast cultures more efficiently than oncoretroviral vectors and at rates comparable to those of lentiviral vectors. However, in these cultures FV vectors only transduced a subpopulation of proliferating cells, as determined by bromodeoxyuridine staining for DNA synthesis. In contrast to lentiviral vectors, FV vectors were unable to transduce human fibroblasts arrested by aphidicolin (G
1
/S phase) or γ-irradiation (G
2
phase), and a partial cell cycle that included mitosis but not DNA synthesis was required. We could not determine if mitosis facilitated nuclear entry of FV vectors, since cell-free vector preparations contained long terminal repeat circles, precluding their use as nuclear markers. In contrast to oncoviral vectors, both FV and lentiviral vectors efficiently transduced G
0
fibroblasts that were later stimulated to divide. In the case of FV vectors, this was due to the persistence of a stable transduction intermediate in quiescent cells. Our findings support the use of FV vectors as a safe and effective alternative to lentiviral vectors for ex vivo transduction of stem cells that are quiescent during culture but divide following transplantation.
Investigation of the Susceptibility of Human Cell Lines to Bovine Herpesvirus 4 Infection: Demonstration that Human Cells Can Support a Nonpermissive Persistent Infection Which Protects Them against Tumor Necrosis Factor Alpha-Induced Apoptosis
Authors: Gillet L. , Minner F. , Detry B. , Farnir F. , Willems L. , Lambot M. , Thiry E. , Pastoret P.-P. , Schynts F. , Vanderplasschen A.
Published: February 2004

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus that has a worldwide distribution in the population of cattle. Many factors make human contamination by BoHV-4 likely to occur. In this study, we performed in vitro experiments to assess the risk and the consequences of human infection by BoHV-4. First, by using a recombinant BoHV-4 strain expressing enhanced green fluorescent protein under the control of the human cytomegalovirus immediate-early gene promoter, we tested 21 human cell lines for their sensitivity and their permissiveness to BoHV-4 infection. These experiments revealed that human cell lines from lymphoid and myeloid origins were resistant to infection, whereas epithelial cells, carcinoma cells, or adenocarcinoma cells isolated from various organs were sensitive but poorly permissive to BoHV-4 infection. Second, by using the HeLa cell line as a model of human cells sensitive but not permissive to BoHV-4 infection, we investigated the resistance of infected cells to apoptosis and the persistence of the infection through cellular divisions. The results obtained can be summarized as follows. (i) BoHV-4 nonpermissive infection of HeLa cells protects them against tumor necrosis factor alpha-induced apoptosis. (ii) BoHV-4 infection of HeLa cells persists in cell culture; however, the percentage of infected cells decreases with time due to erratic transmission of the viral genome through cell division. (iii) BoHV-4 infection has no effect on the rate of HeLa cell division. Altogether, these data suggest that BoHV-4 could infect humans. This study also stresses the importance of considering the insidious effects of nonpermissive infection when the biosafety of animal gammaherpesviruses for humans is being considered.
Vaccinia Virus A28L Gene Encodes an Essential Protein Component of the Virion Membrane with Intramolecular Disulfide Bonds Formed by the Viral Cytoplasmic Redox Pathway
Authors: Senkevich Tatiana G. , Ward Brian M. , Moss Bernard
Published: February 2004

We report the initial characterization of the product of the vaccinia virus A28L gene, which is highly conserved in all sequenced poxviruses. Our studies showed that the A28 protein is expressed at late times during the virus replication cycle and is a membrane component of the intracellular mature virion. An N-terminal hydrophobic sequence, present in all poxvirus A28 orthologs, anchors the protein in the virion surface membrane so that most of it is exposed to the cytoplasm. The cytoplasmic domain contains four conserved cysteines, which form two intramolecular disulfide bonds. Disulfide bond formation depended on the expression of three viral proteins, E10, A2.5, and G4, which together comprise a conserved cytoplasmic redox pathway. A28 is the third identified substrate of this pathway; the others are the L1 and F9 proteins. We constructed a conditional-lethal recombinant vaccinia virus with an inducible A28L gene. The recombinant virus was propagated in the presence of inducer but was unable to replicate and spread in its absence. During a single round of an abortive infection in the absence of inducer, the synthesis and processing of viral proteins, assembly of intra- and extracellular virions, and formation of actin tails occurred normally. In another paper (T. Senkevich, B. M. Ward, and B. Moss, J. Virol. 78:2357-2366, 2004), we have demonstrated that virions assembled without A28 cannot carry out a second round of infection because they are defective in cell penetration.