Effect of Environmental Factors on Nuclear Organization and Transformation of Human B Lymphocytes.

Chromosomal translocations have long been known for their association with malignant transformation, particularly in hematopoietic disorders such as B-cell lymphomas. In addition to the physiological process of maturation, which creates double strand breaks in immunoglobulin gene loci, environmental factors including the Epstein-Barr and human immunodeficiency viruses, malaria-causing parasites (Plasmodium falciparum), and plant components (Euphorbia tirucalli latex) can trigger a reorganization of the nuclear architecture and DNA damage that together will facilitate the occurrence of deleterious chromosomal rearrangements.

Changes in pro-inflammatory markers and leucine concentrations in response to Nordic Walking training combined with vitamin D supplementation in elderly women.

Mechanisms underpinning age-related decreases in muscle strength and muscle mass relate to chronic inflammation. Physical activity induces an anti-inflammatory effect, but it is modulated by additional factors. We hypothesized that vitamin D, which has also anti-inflammatory activity will modify adaptation to exercise and reduce inflammation in elderly women. Twenty-seven women aged 67 ± 8 years were included and divided into groups with baseline vitamin D concentration more than 20 ng mL-1 (MVD) and less than 20 ng mL-1 (LVD). Both groups performed 1 h Nordic Walking (NW) training combined with vitamin D supplementation for 12 weeks. Serum concentrations of inflammation markers, branched amino acids, vitamin D, muscle strength and balance were assessed at the baseline and three days after intervention. The training caused the significant decrease in concentration of pro-inflammatory proteins HMGB1 (30 ± 156%; 90% CI) and IL-6 (-10 ± 66%; 90% CI) in MVD group. This effects in group MVD were moderate, indicating vitamin D as one of the modifiers of these exercise-induced changes. Rise of myokine irisin induced by exercise correlated inversely with HMGB1 and the correlation was more pronounced at the baseline as well as after training among MVD participants. Although the intervention caused the leucine level to rise, a comparison of the recorded response between groups and the adjusted effect indicated that the effect was 20% lower in the LVD group. Overall the applied training program was effective in reducing HMGB1 concentration. This drop was accompanied by the rise of myokine irisin and better uptake of leucine among women with higher baseline vitamin D.

Absolute molecular transition frequencies measured by three cavity-enhanced spectroscopy techniques.

Absolute frequencies of unperturbed (12)C(16)O transitions from the near-infrared (3-0) band were measured with uncertainties five-fold lower than previously available data. The frequency axis of spectra was linked to the primary frequency standard. Three different cavity enhanced absorption and dispersion spectroscopic methods and various approaches to data analysis were used to estimate potential systematic instrumental errors. Except for a well established frequency-stabilized cavity ring-down spectroscopy, we applied the cavity mode-width spectroscopy and the one-dimensional cavity mode-dispersion spectroscopy for measurement of absorption and dispersion spectra, respectively. We demonstrated the highest quality of the dispersion line shape measured in optical spectroscopy so far. We obtained line positions of the Doppler-broadened R24 and R28 transitions with relative uncertainties at the level of 10(-10). The pressure shifting coefficients were measured and the influence of the line asymmetry on unperturbed line positions was analyzed. Our dispersion spectra are the first demonstration of molecular spectroscopy with both axes of the spectra directly linked to the primary frequency standard, which is particularly desirable for the future reference-grade measurements of molecular spectra.

Genome- and Cell-Based Strategies in Therapy of Muscular Dystrophies.

Muscular dystrophies are a group of heterogeneous genetic disorders characterized by progressive loss of skeletal muscle mass. Depending on the muscular dystrophy, the muscle weakness varies in degree of severity. The majority of myopathies are due to genetic events leading to a loss of function of key genes involved in muscle function. Although there is until now no curative treatment to stop the progression of most myopathies, a significant number of experimental gene- and cell-based strategies and approaches have been and are being tested in vitro and in animal models, aiming to restore gene function. Genome editing using programmable endonucleases is a powerful tool for modifying target genome sequences and has been extensively used over the last decade to correct in vitro genetic defects of many single-gene diseases. By inducing double-strand breaks (DSBs), the engineered endonucleases specifically target chosen sequences. These DSBs are spontaneously repaired either by homologous recombination in the presence of a sequence template, or by nonhomologous-end joining error prone repair. In this review, we highlight recent developments and challenges for genome-editing based strategies that hold great promise for muscular dystrophies and regenerative medicine.

Variation of cats under domestication: genetic assignment of domestic cats to breeds and worldwide random-bred populations.

Both cat breeders and the lay public have interests in the origins of their pets, not only in the genetic identity of the purebred individuals, but also in the historical origins of common household cats. The cat fancy is a relatively new institution with over 85% of its 40-50 breeds arising only in the past 75 years, primarily through selection on single-gene aesthetic traits. The short, yet intense cat breed history poses a significant challenge to the development of a genetic marker-based breed identification strategy. Using different breed assignment strategies and methods, 477 cats representing 29 fancy breeds were analysed with 38 short tandem repeats, 148 intergenic and five phenotypic single nucleotide polymorphisms. Results suggest the frequentist method of Paetkau (single nucleotide polymorphisms = 0.78, short tandem repeats = 0.88) surpasses the Bayesian method of Rannala and Mountain (single nucleotide polymorphisms = 0.56, short tandem repeats = 0.83) for accurate assignment of individuals to the correct breed. Additionally, a post-assignment verification step with the five phenotypic single nucleotide polymorphisms accurately identified between 0.31 and 0.58 of the misassigned individuals raising the sensitivity of assignment with the frequentist method to 0.89 and 0.92 for single nucleotide polymorphisms and short tandem repeats respectively. This study provides a novel multistep assignment strategy and suggests that, despite their short breed history and breed family groupings, a majority of cats can be assigned to their proper breed or population of origin, that is, race.

Transcription factories in the context of the nuclear and genome organization.

In the eukaryotic nucleus, genes are transcribed in transcription factories. In the present review, we re-evaluate the models of transcription factories in the light of recent and older data. Based on this analysis, we propose that transcription factories result from the aggregation of RNA polymerase II-containing pre-initiation complexes assembled next to each other in the nuclear space. Such an aggregation can be triggered by the phosphorylation of the C-terminal domain of RNA polymerase II molecules and their interaction with various transcription factors. Individual transcription factories would thus incorporate tissue-specific, co-regulated as well as housekeeping genes based only on their initial proximity to each other in the nuclear space. Targeting genes to be transcribed to protein-dense factories that contain all factors necessary for transcription initiation and elongation through chromatin templates clearly favors a more economical utilization and better recycling of the transcription machinery.

HIRA, a mammalian homologue of Saccharomyces cerevisiae transcriptional co-repressors, interacts with Pax3.

HIRA maps to the DiGeorge/velocardiofacial syndrome critical region (DGCR) at 22q11 (refs 1,2) and encodes a WD40 repeat protein similar to yeast Hir1p and Hir2p. These transcriptional co-repressors regulate cell cycle-dependent histone gene transcription, possibly by remodelling local chromatin structure. We report an interaction between HIRA and the transcription factor Pax3. Pax3 haploinsufficiency results in the mouse splotch and human Waardenburg syndrome (WSI and WSIII) phenotypes. Mice homozygous for Pax3 mutations die in utero with a phenocopy of DGS, or neonatally with neural tube defects. HIRA was also found to interact with core histones. Thus, altered stoichiometry of complexes containing HIRA may be important for the development of structures affected in WS and DGS.

Metabolism of 4-pyridone-3-carboxamide-1-ß-D-ribonucleoside (4PYR) in rodent tissues and in vivo.

Our previous studies identified 4-pyridone-3-carboxamide-1-ß-D-ribonucleoside (4PYR) phosphates in human erythrocytes. We demonstrated formation of these nucleotides by phosphorylation of 4PYR and potential toxicity due to disruption of erythrocyte energy balance. This study aimed to evaluate the ability of the other cell types to phosphorylate 4PYR to characterize function and toxicity of these compounds. Homogenates of rat heart, kidneys, and liver were used to study the rate of 4PYR phosphorylation in the presence of ATP. In another experiment, 4PYR was administered into mouse as repeated subcutaneous injections and into rats as intraperitoneal infusion. After 7 days, heart, liver, kidney, lungs, and skeletal muscle were collected, and the concentration of 4PYR nucleotides was evaluated. HPLC was used to measure 4PYR and 4PYR nucleotides in homogenate and specimens from in vivo experiments. 4PYR was rapidly phosphorylated by the liver homogenate (390 ± 27 nmol/min/g wet wt). Significant rates were reported in the heart and kidneys' homogenates: 34.3 ± 4.3 nmol/min/g and 33.2 ± 9.2 nmol/min/g, respectively. Phosphorylation of 4PYR was almost completely inhibited by adenosine kinase inhibitor 5'-iodotubercidin. Administration of 4PYR in vivo resulted in accumulation of 4PYR monophosphate in the liver, heart, skeletal muscle, and lung (20-220 nmol/g dry wt) except kidney (<1 nmol/g). In contrast to erythrocytes, no 4PYR triphosphate formation (<1 nmol/g) was observed in any of the organs studied. We conclude that not only the erythrocytes but also other cell types are capable of phosphorylating 4PYR to form 4PYR monophosphate. Potential toxicity or physiological role of 4PYR in peripheral organs could be considered, but mechanisms will be different from that in erythrocytes.

HNK-1 antibody detects an antigen expressed on neuroectodermal cells.

The HNK-1 antibody known to define a subpopulation of human lymphocytes with natural killer and killer cell activities was shown to detect a common neuroectodermal antigen. Most tumor lines and paraffin-embedded tumors and normal tissues of neuroectodermal origin were specifically stained by HNK-1. Lines and tissues of other derivations were negative except a trophoblastic tumor line and a percentage of Ewing's sarcomas, whose histogenesis is poorly understood. These data indicate that HNK-1 antibody could be of interest in clinical histopathology but cannot be considered as specific for a lymphocyte subset.

A novel subset of human lymphocytes with a T cell receptor-gamma complex.

We have previously characterized a CD3+ T cell receptor (TCR) alpha/beta- human fetal cloned cell line, termed F6C7, which surface-expresses a CD3-associated gamma chain identified by anti-NKFi, an mAb with a restricted clonotypic reactivity. Here, we have produced an additional antibody, anti-Ti-gamma A, which recognizes a public epitope of the gamma molecule defined by anti-NKFi. Ti-gamma A is present on approximately 3% of circulating lymphocytes with a wide range (1-15%) among 30 healthy individuals tested. Two-color immunofluorescence experiments performed with anti-Ti-gamma A and BMA 031 mAb (a reagent specific for the TCR-alpha/beta receptor) showed that surface expression of Ti-alpha/beta and Ti-gamma A is mutually exclusive. Moreover, it was found that most Ti-gamma A+ cells are CD2+, CD3+, CD4-, CD5+, NKH1-, HLA class II-negative. In contrast, the expression of the CD8 molecule on these T lymphocytes appears to be variable from one individual to another. Finally, we found that Ti-gamma A+ cells represent a majority of peripheral lymphocytes that express CD3 proteins but not the TCR-alpha/beta heterodimer. The delineation of this unique lymphocyte subset should help further studies on the biology of cells with a CD3-associated gamma complex.

Absence of allogeneic restriction in human T-cell-mediated cytotoxicity to Epstein-Barr virus-infected target cells. Demonstration of an HLA-linked control at the effector level.

Peripheral T lymphocytes from patients with infectious mononucleosis (IM) are sensitized in vivo against the Epstein-Barr virus (EBV). The expression of HLA-A, B, or C molecules at the target cell surface is necessary for the cytotoxic reaction because (a) EBV-positive Daudi cells lacking HLA-A, B, and C determinants are resistant to anti-EBV T-cell lysis, (b) cytolysis of EBV-positive target cells can be consistently inhibited by anti-HLA-A, B, and C and anti-beta 2 microglobulin antibodies. However, no evidence for allogeneic restriction in this system was apparent as (a) cytotoxic T lymphocytes (CTL) from one given individual could exert a cytotoxicity of a similar magnitude on different EBV-positive target cells, regardless of the number of HLA-A or B specificities shared by the effectors and targets; (b) CTL from IM patients were able to kill target cells without any HLA-A or B antigen in common; and (c) T5-1 variants lacking one or two HLA antigens at the A, B, or D locus are killed to the same extent as the parental cells. 7 of the 9 IM patients with detectable circulating anti-EBV CTL carried the HLA-A1 antigen, whereas none of the 16 IM patients lacking detectable peripheral CTL were HLA-A1 positive (mean specific lysis of T5-1 target cells by T cells from HLA-A1 positive patients: 29.3 vs. 0.6% in HLA-A1-negative patients) (P less than 10(-9)). These data suggest an HLA-A1-linked gene control of the magnitude of the anti-EBV CTL response. Thus, the HLA region appears to act at two different level sin the T-cell-mediated lysis of EBV-infected cells by controlling first, the development of anti-EBV and second, the expression of HLA-A, B, and C molecules involved as recognition structures at the target cell surface.

Evolutionary conservation of surface molecules that distinguish T lymphocyte helper/inducer and cytotoxic/suppressor subpopulations in mouse and man.

We describe the biochemical properties and cell surface distributions of three human T cell antigens (Leu-1, Leu-2a, and Leu-2b) which we postulate to be the homologues of the Lyt-1, Lyt-2, and Lyt-3 antigens that distinguish functional T cell subsets in the mouse. Leu-l, like Lyt-1, is on all thymocytes and peripheral T cells and is present in greater amounts on the helper/inducer subset than on the cytotoxic/suppressor subset. Both antigens increase in parallel fashion during T cell maturation in the thymus and each antigen is carried on a single 67,000-molecular weight (relative) (M(r)) polypeptide chain. Surprisingly, Leu-1 and Lyt-1 each are also expressed in readily detectable amounts on some B celI Ieukemias but not detectably so on normal B cells. Leu-2a and Leu-2b are antigens found only on suppressor/cytotoxic cells in the human and are very similar to the murine Lyt-2 and Lyt-3 antigens. In both species, the two antigens are on the same disulfide- linked multimeric molecules. Disulfide-bond reduction in both species yields subunits of similar size and charge. Lyt-3 and Leu-2b are extremely sensitive to trypsin digestion on viable cells whereas Lyt-2 and Leu-2a are much less so. A different membrane antigen, Leu-3, is an exclusive marker of the helper/inducer subset in man. No mouse homologue for this 55,000-M(r) protein is known. The maintenance of the homologous molecules on functionally distinct T cell subpopulations in two evolutionarily distant species suggests that the Lyt and Leu antigens perform essential functions for the cells on which they are found.

Iron deficiency anemia and cardiac mortality in patients with left ventricular systolic dysfunction undergoing coronary stenting.

AIM: The aim of this study was to assess cardiac mortality in patients with reduced ejection fraction (EF< or =45%) and anemia (Hb< or =12 g/dL) undergoing coronary stenting and to investigate whether iron-deficiency anemia influenced outcome when compared to non-anemic patients or patients with other types of anemia. METHODS: One hundred twenty consecutive patients undergoing percutaneous coronary intervention (PCI) between April 2003 and December 2005 were identified and followed for a median of 30 months. Patients were divided into 2 groups, anemic (Hb< or =12 g/dL) and non-anemic. Anemic patients were then divided into 3 sub-groups based on laboratory analysis and anemia work-up: iron-deficiency, malignancy-associated, and anemia of chronic disease (including chronic kidney disease). Mortality rates and cause of death were retrieved using both the Social Security database and the hospital records. RESULTS: Thirty-one percent of patients had iron deficiency, 24% had a malignancy-associated anemia and 45% had anemia of chronic disease. Overall mortality was 12% of which 29% was cardiac death. All-cause and cardiac mortality were significantly higher in anemic vs. non-anemic patients, (31% vs. 6%, P<0.001, and 10% vs. 1%, P=0.016, respectively). Iron-deficiency anemia strongly predicted cardiac mortality (33% vs. 1% in non-anemic patients, P<0.001), while malignancy-associated anemia was the strongest predictor of non-cardiac death (57% vs. 4% in non-anemic patients, P<0.001). Anemia of chronic disease neither predicted cardiac nor non-cardiac death. CONCLUSIONS: To the authors' knowledge, this is the first study to show that iron-deficiency anemia is a strong predictor of cardiac death when compared to patients with other types of anemia or to non-anemic patients.

A Survey of Nephrologists Regarding Their Communication with Transplant Centers.

BACKGROUND: Patients with end-stage renal disease (ESRD) undergo a transition of care between their primary nephrologist and the transplant center during evaluation for kidney transplantation. Due to medical complexity, high hospitalization rate, and involvement of multiple medical stakeholders, transitions of medical care among patients with ESRD are likely to be associated with suboptimal care and medical errors. Provider-to-provider communication improves outcomes among ESRD patients transitioning between dialysis and transplant. There is little data analyzing proper transition of care between the nephrologist and the transplant center (TC). OBJECTIVE: Using survey methodology, we examined nephrologists' current practice and experience regarding patient-related communication with the TC. METHODS: From among 822 nephrologists who were following at least 20 ESRD patients, we randomly selected 252 nephrologists to participate in the study. The survey consisted of 102 multiple choice and Likert-style items probing perceptions about various aspects of transplant, including communication between TC and nephrologist. Responses from 216 participants who submitted complete responses were included in the final analysis. RESULTS: Depending on the phase of transplant, nephrologist-TC communication varied between 50%-81% of nephrologists. Factors associated with higher likelihood of nephrologist-TC communication included attending transplant-related educational activity, practicing in a group with more than 5 nephrologists, and having more than 50 patients on dialysis. The majority of nephrologists indicated satisfaction with access to an attending physician in the TC, receiving timely and adequate information from the TC about their patients. Factors associated with higher likelihood of nephrologist satisfaction regarding communication with the TC included attending national nephrology meetings, medical directorship of a dialysis unit, fellowship training at an institution with an on-site transplant program, and availability of more than 2 transplant centers within 50 miles. CONCLUSION: There is a lack of evidence-based guidelines for patient transfer of care between nephrologists and transplant centers during various phases of transplant referral, evaluation and post-transplant care. We found that the likelihood of the nephrologists' communication with the transplant center and their satisfaction with the communication are related to their training, participation in continuing educational meetings, their practice location and size, and the overall composition of their patient population.

A glycolipid antigen associated with Burkitt lymphoma defined by a monoclonal antibody.

The antigen defined by a rat monoclonal antibody directed to a Burkitt lymphoma cell line was identified as globotriaosylceramide [Gal alpha (1 leads to 4)-Gal beta (1 leads to 4)-Glc beta (1 leads to 1)-ceramide]. The antibody demonstrated a strict steric specificity since it did not react with globoisotriaosylceramide [Gal alpha (1 leads to 3)-Gal beta (1 leads to 4)-Glc beta (1 leads to 1)-ceramide], the positional isomer of the antigen associated with the Burkitt lymphoma. Chemical analysis of various Burkitt lymphoma cell lines revealed that the Burkitt lymphoma cells contained more than 100 times as much of the glycolipid antigen as was found in other human lymphoma and leukemia cell lines.

Factors Considered by Nephrologists in Excluding Patients from Kidney Transplant Referral.

BACKGROUND: Provider perceptions about patient candidacy for kidney transplant (KT) are potentially significant contributors to disparities in KT. OBJECTIVE: To examine nephrologists' perceptions about factors that are important in excluding patients from KT referral, and to analyze the association between these perceptions and nephrologists' demographic and practice characteristics.Methods: Invitations were sent to 3180 nephrologists. Among those who consented, 822 fulfilled the inclusion criteria, and 250 were randomly invited to complete a questionnaire about perceptions of factors essential in deciding not to refer patients for KT. RESULTS: Responses from 216 participants with complete responses were analyzed. The 3 most common reasons for excluding patients were "patient's inadequate social support" (44%), "limited understanding of the process due to patient's inadequate education" (32%), and "patient's age above 65" (26%). Nephrologists practicing in rural settings were more likely to consider inadequate support and limited education of patients as reasons not to refer for KT. In multivariate analysis, physicians with 2 or fewer transplant centers within 50 miles were more likely to report inadequate social support (OR: 3.15, 95% CI: 1.59-6.24) and age greater than 65 years (OR: 1.88, 95% CI: 1.01-3.49) as reasons to exclude patients from KT referral. Nephrologists whose practice included patients majority of whom had not completed high school were more likely to consider limited understanding due to inadequate education as an important reason to exclude patients from KT (OR: 3.31, 95% CI: 1.60-6.86). CONCLUSION: Patient's social support, understanding, and age were the most common factors regarded by nephrologists as important in not referring patients for KT evaluation. Practice location, particularly rural setting, proximity to a transplant center, and the education level of a nephrologist's patient population were important determinants of referral for KT.

Core histones and HIRIP3, a novel histone-binding protein, directly interact with WD repeat protein HIRA.

The human HIRA gene has been named after Hir1p and Hir2p, two corepressors which together appear to act on chromatin structure to control gene transcription in Saccharomyces cerevisiae. HIRA homologs are expressed in a regulated fashion during mouse and chicken embryogenesis, and the human gene is a major candidate for the DiGeorge syndrome and related developmental disorders caused by a reduction to single dose of a fragment of chromosome 22q. Western blot analysis and double-immunofluorescence experiments using a specific antiserum revealed a primary nuclear localization of HIRA. Similar to Hir1p, HIRA contains seven amino-terminal WD repeats and probably functions as part of a multiprotein complex. HIRA and core histone H2B were found to physically interact in a yeast double-hybrid protein interaction trap, in GST pull-down assays, and in coimmunoprecipitation experiments performed from cellular extracts. In vitro, HIRA also interacted with core histone H4. H2B- and H4-binding domains were overlapping but distinguishable in the carboxy-terminal region of HIRA, and the region for HIRA interaction was mapped to the amino-terminal tail of H2B and the second alpha helix of H4. HIRIP3 (HIRA-interacting protein 3) is a novel gene product that was identified from its HIRA-binding properties in the yeast protein interaction trap. In vitro, HIRIP3 directly interacted with HIRA but also with core histones H2B and H3, suggesting that a HIRA-HIRIP3-containing complex could function in some aspects of chromatin and histone metabolism. Insufficient production of HIRA, which we report elsewhere interacts with homeodomain-containing DNA-binding factors during mammalian embryogenesis, could perturb the stoichiometric assembly of multimolecular complexes required for normal embryonic development.

HIRA, the human homologue of yeast Hir1p and Hir2p, is a novel cyclin-cdk2 substrate whose expression blocks S-phase progression.

Substrates of cyclin-cdk2 kinases contain two distinct primary sequence motifs: a cyclin-binding RXL motif and one or more phosphoacceptor sites (consensus S/TPXK/R or S/TP). To identify novel cyclin-cdk2 substrates, we searched the database for proteins containing both of these motifs. One such protein is human HIRA, the homologue of two cell cycle-regulated repressors of histone gene expression in Saccharomyces cerevisiae, Hir1p and Hir2p. Here we demonstrate that human HIRA is an in vivo substrate of a cyclin-cdk2 kinase. First, HIRA bound to and was phosphorylated by cyclin A- and E-cdk2 in vitro in an RXL-dependent manner. Second, HIRA was phosphorylated in vivo on two consensus cyclin-cdk2 phosphoacceptor sites and at least one of these, threonine 555, was phosphorylated by cyclin A-cdk2 in vitro. Third, phosphorylation of HIRA in vivo was blocked by cyclin-cdk2 inhibitor p21(cip1). Fourth, HIRA became phosphorylated on threonine 555 in S phase when cyclin-cdk2 kinases are active. Fifth, HIRA was localized preferentially to the nucleus, where active cyclin A- and E-cdk2 are located. Finally, ectopic expression of HIRA in cells caused arrest in S phase and this is consistent with the notion that it is a cyclin-cdk2 substrate that has a role in control of the cell cycle.

HIV Tat induces a prolonged MYC relocalization next to IGH in circulating B-cells.

With combined antiretroviral therapy (cART), the risk for HIV-infected individuals to develop a non-Hodgkin lymphoma is diminished. However, the incidence of Burkitt lymphoma (BL) remains strikingly elevated. Most BL present a t(8;14) chromosomal translocation which must take place at a time of spatial proximity between the translocation partners. The two partner genes, MYC and IGH, were found colocalized only very rarely in the nuclei of normal peripheral blood B-cells examined using 3D-FISH while circulating B-cells from HIV-infected individuals whose exhibited consistently elevated levels of MYC-IGH colocalization. In vitro, incubating normal B-cells from healthy donors with a transcriptionally active form of the HIV-encoded Tat protein rapidly activated transcription of the nuclease-encoding RAG1 gene. This created DNA damage, including in the MYC gene locus which then moved towards the center of the nucleus where it sustainably colocalized with IGH up to 10-fold more frequently than in controls. In vivo, this could be sufficient to account for the elevated risk of BL-specific chromosomal translocations which would occur following DNA double strand breaks triggered by AID in secondary lymph nodes at the final stage of immunoglobulin gene maturation. New therapeutic attitudes can be envisioned to prevent BL in this high risk group.

Liquid chromatographic/mass spectrometric procedure for measurement of NAD catabolites in human and rat plasma and urine.

Monitoring level of the metabolites of the coenzyme NAD such as nicotinamide and its oxidized and methylated derivatives is important due to therapeutic applications of these compounds and monitoring of oxidative stress. We evaluated feasibility of using HPLC with electrospray ion-trap mass detection for single run separation and quantitation of all the NAD metabolites. We achieved good separation and retention of all the metabolites of interest using reversed-phase with ion-pairing. Single ion monitoring or tandem MS were used for detection and quantitation of the specific compounds with good linearity. The method was able to detect all the physiological metabolites in plasma samples of rats and humans or in urine. However, full validation is necessary before this method could be routinely applied.