Fate of premalignant clones during the asymptomatic phase preceding lymphoid malignancy.

Almost all cancers are preceded by a prolonged period of clinical latency during which a combination of cellular events helps move carcinogen-exposed cells towards a malignant phenotype. Hitherto, investigating the fate of premalignant cells in vivo remained strongly hampered by the fact that these cells are usually indistinguishable from their normal counterparts. Here, for the first time, we have designed a strategy able to reconstitute the replicative history of the bona fide premalignant clone in an animal model, the sheep experimentally infected with the lymphotropic bovine leukemia virus.

Age-related changes in ischemic tolerance in male and female mouse hearts.

Aging is associated with reduced tolerance to ischemic insult, and genesis of this intolerant phenotype is poorly understood. We characterized effects of aging and gender on cardiovascular function and cell damage during 20 min ischemia and 60 min reperfusion in isolated hearts from young adult (2-4 months), mature adult (8 months), middle-aged (12 months), aged (18 months), and senescent (24-28 months) C57/Bl6 mice. Aging substantially impaired recovery of ventricular contractility, with this change primarily evident within 12 months of age.

Genetic deletion of the A1 adenosine receptor limits myocardial ischemic tolerance.

Adenosine receptors may be important determinants of intrinsic ischemic tolerance. Genetically modified mice were used to examine effects of global A1 adenosine receptor (A1AR) knockout (KO) on function and ischemic tolerance in perfused mouse hearts. Baseline contractile function and heart rate were unaltered by A1AR KO, which was shown to abolish the negative chronotropic effects of 2-chloroadenosine (A1AR-mediated) without altering A2 adenosine receptor-mediated coronary dilation.

Overlapping CRE and E box motifs in the enhancer sequences of the bovine leukemia virus 5' long terminal repeat are critical for basal and acetylation-dependent transcriptional activity of the viral promoter: implications for viral latency.

Bovine leukemia virus (BLV) infection is characterized by viral latency in a large proportion of cells containing an integrated provirus. In this study, we postulated that mechanisms directing the recruitment of deacetylases to the BLV 5' long terminal repeat (LTR) could explain the transcriptional repression of viral expression in vivo. Accordingly, we showed that BLV promoter activity was induced by several deacetylase inhibitors (such as trichostatin A [TSA]) in the context of episomal LTR constructs and in the context of an integrated BLV provirus.

Reduced proviral loads during primo-infection of sheep by Bovine Leukemia virus attenuated mutants.

Background: The early stages consecutive to infection of sheep (e.g. primo-infection) by Bovine leukemia virus mutants are largely unknown.

Continuous infusion of medications in very low birth weight infants.

Objective: To develop a safe and accurate method for the administration in the neonatal intensive care unit of several potent medications as a continuous infusion without overloading the infant, especially the very low birth weight (VLBW) infant by diluents.

Method: The method designed is based on a weight-adapted solution limiting the diluent administration and allowing for a versatile modulation of dose administration. As this method was initially designed for VLBW infants, the point of departure of this method is a standard maximal fluid load of 0.

Involvement of glutathione as a mechanism of indirect protection against spontaneous ex vivo apoptosis associated with bovine leukemia virus.

Viruses have developed strategies to counteract the apoptotic response of the infected host cells. Modulation of apoptosis is also thought to be a major component of viral persistence and progression to leukemia induced by retroviruses like human T-lymphotropic virus type 1 (HTLV-1) and bovine leukemia virus (BLV). Here, we analyzed the mechanism of ex vivo apoptosis occurring after isolation of peripheral blood mononuclear cells from BLV-infected sheep.

Suppression of tumor growth and cell proliferation by p13II, a mitochondrial protein of human T cell leukemia virus type 1.

Human T cell leukemia virus type 1 encodes an "accessory" protein named p13(II) that is targeted to mitochondria and triggers a rapid flux of K(+) and Ca(2+) across the inner membrane. In this study, we investigated the effects of p13(II) on tumorigenicity in vivo and on cell growth in vitro. Results showed that p13(II) significantly reduced the incidence and growth rate of tumors arising from c-myc and Ha-ras-cotransfected rat embryo fibroblasts.

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.

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.

Interaction of retroviral Tax oncoproteins with tristetraprolin and regulation of tumor necrosis factor-alpha expression.

Background: The Tax oncoproteins are transcriptional regulators of viral expression involved in pathogenesis induced by complex leukemogenic retroviruses (or delta-retroviruses, i.e., primate T-cell leukemia viruses and bovine leukemia virus).

Reduced cell turnover in bovine leukemia virus-infected, persistently lymphocytotic cattle.

Although nucleotide analogs like bromodeoxyuridine have been extensively used to estimate cell proliferation in vivo, precise dynamic parameters are scarce essentially because of the lack of adequate mathematical models. Besides recent developments on T cell dynamics, the turnover rates of B lymphocytes are largely unknown particularly in the context of a virally induced pathological disorder. Here, we aim to resolve this issue by determining the rates of cell proliferation and death during the chronic stage of the bovine leukemia virus (BLV) infection, called bovine persistent lymphocytosis (PL).

Mediastinal restaging: EUS-FNA offers a new perspective.

Study Objective: We hypothesized that transoesophageal endoscopic ultrasound guided fine needle aspiration (EUS-FNA) has the potential to be a valuable and accurate new diagnostic technique for mediastinal restaging in non-small cell lung cancer (NSCLC) after induction chemotherapy. The current restaging modalities either have a low diagnostic accuracy (computed tomography (CT) scan of the thorax) or they are invasive, can be technically difficult and are therefore not commonly performed (remediastinoscopy).

Methods And Patients: Nineteen consecutive patients with NSCLC and proven ipsilateral or subcarinal lymph node metastases (N2 disease) who had been treated with induction chemotherapy underwent mediastinal restaging by EUS-FNA.

Effects of aging and ischemia on adenosine receptor transcription in mouse myocardium.

The well-documented age-related change in ischemic tolerance may result from impaired adenosine-mediated cardioprotection. Additionally, ischemia itself may potentially modify adenosine signalling, contributing to the post-ischemic phenotype. This study investigates age- and ischemia-dependent changes in adenosine receptor transcript levels (Adora) for the A(1), A(2A), A(2B), and A(3) receptor subtypes in mouse myocardium.

Aging-related changes in myocardial purine metabolism and ischemic tolerance.

Impaired tolerance to ischemia-reperfusion in older hearts may stem in part from alterations in purine catabolism, impacting on maintenance of energy state and protective signaling via extracellular adenosine. We characterized effects of aging on normoxic and post-ischemic purine metabolism in hearts from young (2-4 month), middle-aged (12 month), old (18 month), and senescent (24-28 month) C57/Bl6 mice. Normoxic function was similar in all age groups while normoxic purine efflux increased gradually with age.

Shortage of donation despite an adequate number of donors: a professional attitude?

Background: A major problem in the field of transplantation is the persistent shortage of donor organs and tissues for transplantation. This study was initiated to (1) chart the donor potential for organs and tissue in The Netherlands and (2) to identify factors influencing whether donation is discussed with next of kin.

Methods: A registration form was constructed to obtain information at time of death of patients about the demographic characteristics, diagnosis, and medical suitability for donation.

The epidemiology of myasthenia gravis, Lambert-Eaton myasthenic syndrome and their associated tumours in the northern part of the province of South Holland.

We studied the epidemiology of myasthenia gravis (MG) and the Lambert-Eaton myasthenic syndrome (LEMS), and their association with small cell lung carcinoma (SCLC) and thymoma, in a well defined region of the Netherlands. Available data on all the patients with MG, LEMS, thymoma or SCLC living between 1 January 1990 and 31 December 1999 in the northern region of South Holland, with a population of 1.7 million inhabitants, were evaluated.

Ischaemic tolerance in aged mouse myocardium: the role of adenosine and effects of A1 adenosine receptor overexpression.

The genesis of the ischaemia intolerant phenotype in aged myocardium is poorly understood. We tested the hypothesis that impaired adenosine-mediated protection contributes to ischaemic intolerance, and examined whether this is countered by A1 adenosine receptor (A1AR) overexpression. Responses to 20 min ischaemia and 45 min reperfusion were assessed in perfused hearts from young (2-4 months) and moderately aged (16-18 months) mice.

Morphological quantification of emphysema in small human lung specimens: comparison of methods and relation with clinical data.

Small human lung specimens are frequently used for cell biological studies of the pathogenesis of emphysema. In general, lung function and other clinical parameters are used to establish the presence and severity of emphysema/chronic obstructive pulmonary disease without morphological analysis of the specimens under investigation. In this study we compared three morphological methods to analyze emphysema, and evaluated whether clinical data correlate with the morphological data of individual lung samples.

Lymphocyte kinetics: the interpretation of labelling data.

DNA labelling provides an exciting tool for elucidating the in vivo dynamics of lymphocytes. However, the kinetics of label incorporation and loss are complex and results can depend on the method of interpretation. Here we describe two approaches to interpreting labelling data.

Receptor and non-receptor-dependent mechanisms of cardioprotection with adenosine.

The relative roles of mitochondrial (mito) ATP-sensitive K(+) (mitoK(ATP)) channels, protein kinase C (PKC), and adenosine kinase (AK) in adenosine-mediated protection were assessed in Langendorff-perfused mouse hearts subjected to 20-min ischemia and 45-min reperfusion. Control hearts recovered 72 +/- 3 mmHg of ventricular pressure (50% preischemia) and released 23 +/- 2 IU/g lactate dehydrogenase (LDH). Adenosine (50 microM) during ischemia-reperfusion improved recovery (149 +/- 8 mmHg) and reduced LDH efflux (5 +/- 1 IU/g).

Bovine leukemia virus SU protein interacts with zinc, and mutations within two interacting regions differently affect viral fusion and infectivity in vivo.

Bovine leukemia virus (BLV) and human T-cell lymphotropic virus type 1 (HTLV-1) belong to the genus of deltaretroviruses. Their entry into the host cell is supposed to be mediated by interactions of the extracellular (SU) envelope glycoproteins with cellular receptors. To gain insight into the mechanisms governing this process, we investigated the ability of SU proteins to interact with specific ligands.

Increased cell proliferation, but not reduced cell death, induces lymphocytosis in bovine leukemia virus-infected sheep.

Lymphocyte homeostasis is the result of a critical balance between cell proliferation and death. Disruption of this subtle equilibrium can lead to the onset of leukemia, an increase in the number of lymphocytes being potentially due to both of these parameters. The relative importance of cell proliferation vs.

Subcellular localization of the bovine leukemia virus R3 and G4 accessory proteins.

Bovine leukemia virus (BLV) is a complex retrovirus that belongs to the Deltaretrovirus genus, which also includes Human T-cell leukemia virus type 1 (HTLV-1). Both viruses contain an X region coding for at least four proteins: Tax and Rex, which are involved in transcriptional and posttranscriptional regulation, respectively, and the accessory proteins R3 and G4 (for BLV) and p12(I), p13(II), and p30(II) (for HTLV-1). The present study was aimed at characterizing the subcellular localization of BLV R3 and G4.