A genetic and genomic analysis identifies a cluster of genes associated with hematopoietic cell turnover.

Hematopoietic stem cells from different strains of mice vary widely with respect to their cell cycle activity. In the present study we used complementary genetic and genomic approaches to identify molecular pathways affecting this complex trait. We identified a major quantitative trait locus (QTL) associated with variation in cell proliferation in C57BL/6 and DBA/2 mice to a 10 centimorgan (cM) region on chromosome 11.

Growth factor treatment prior to low-dose total body irradiation increases donor cell engraftment after bone marrow transplantation in mice.

Low-toxicity conditioning regimens prior to bone marrow transplantation (BMT) are widely explored. We developed a new protocol using hematopoietic growth factors prior to low-dose total body irradiation (TBI) in recipients of autologous transplants to establish high levels of long-term donor cell engraftment. We hypothesized that treatment of recipient mice with growth factors would selectively deplete stem cells, resulting in successful long-term donor cell engraftment after transplantation.

[From gene to disease; progressive myoclonus epilepsy of Unverricht-Lundborg and mutations in the cystatin B gene].

Progressive myoclonus epilepsy type 1 of Unverricht-Lundborg (EPM1) is a rare disorder, associated with mutations in the cystatin B (CSTB) gene. The most prevalent molecular abnormality is an expansion of a dodecamer repeat in the promoter region of the CSTB gene, but point mutations in the CSTB gene have also been found. DNA examination may be useful in discriminating EPM1 from juvenile myoclonic epilepsy, and from other types of progressive myoclonus epilepsy.

Hematopoietic stem cells: self-renewing or aging?

Stem cells are defined by their extensive self-renewal properties, and yet there is abundant evidence of erosion of stem cell functioning during aging. Whereas intracellular repair and protection mechanisms determine the lifespan of an individual cell, here an argument is made that somatic stem cells determine the lifespan of an entire tissue, and thus play a key role in the organismal aging process. Recently it has been shown that the developmental potential of somatic stem cells may be far greater than previously anticipated.

Hansenula polymorpha Pex3p is a peripheral component of the peroxisomal membrane.

Hansenula polymorpha Pex3p plays an essential role in the biogenesis and maintenance of the peroxisomal membrane. In the initial report, bakers' yeast Pex3p was suggested to represent an integral component of the peroxisomal membrane, containing one membrane-spanning region that exposes the N terminus of the protein into the organellar matrix. Biochemically, HpPex3p behaved like an integral membrane protein as it was resistant toward high salt and carbonate treatment.

Pharmacokinetics and pharmacodynamics of midazolam administered as a concentrated intranasal spray. A study in healthy volunteers.

Aims: To investigate the pharmacokinetic and pharmacodynamic profile of midazolam administered as a concentrated intranasal spray, compared with intravenous midazolam, in healthy adult subjects.

Methods: Subjects were administered single doses of 5 mg midazolam intranasally and intravenously in a cross-over design with washout period of 1 week. The total plasma concentrations of midazolam and the metabolite 1-hydroxymidazolam after both intranasal and intravenous administration were described with a single pharmacokinetic model.

Stem cells from birth to death: The history and the future.

The concept that adult stem cells, despite their impressive proliferative potential, are immortal has been challenged by experimental studies of hematopoietic stem cells. In this review, we discuss the properties that characterize a stem cell, the growing list of tissues in which stem cells are found, how they can be identified and isolated, how stem cells may transdifferentiate, and the findings that illustrate how age affects the hematopoietic stem cell population. We propose that an aging stem cell population affects tissue and organ homeostasis, particularly in response to environmental stresses, and we hypothesize that through this mechanism the functional status of stem cells affects the longevity of the organism.

Normal peroxisome development from vesicles induced by truncated Hansenula polymorpha Pex3p.

We show that the synthesis of the N-terminal 50 amino acids of Pex3p (Pex3p(1-50)) in Hansenula polymorpha pex3 cells is associated with the formation of vesicular membrane structures. Biochemical and ultrastructural findings suggest that the nuclear membrane is the donor membrane compartment of these vesicles. These structures also contain Pex14p and can develop into functional peroxisomes after subsequent reintroduction of the full-length Pex3p protein.

The cobblestone-area-forming cell assay.

Hematopoietic stem cell (HSC) subsets are defined by the capacity to which their offspring can contribute to the various mature blood-cell lineages. However, the proliferative potential of stem cells is highly dependent on the environment in which they reside, and it is only in retrospect that the characteristics of a stem cell can be identified. Partly because of these elusive properties of stem cells, various functional assays to measure their frequency have been developed, both in vivo and in vitro.

Age- and stage-specific regulation patterns in the hematopoietic stem cell hierarchy.

The molecular mechanisms that regulate self-renewal and differentiation of very primitive hematopoietic stem and progenitor cells in vivo are still poorly understood. Despite the clinical relevance, even less is known about the mechanisms that regulate these cells in old animals. In a forward genetic approach, using quantitative trait linkage analysis in the mouse BXD recombinant inbred set, this study identified loci that regulate the genetic variation in the size of primitive hematopoietic cell compartments of young and old C57BL6 and DBA/2 animals.

SPTLC1 is mutated in hereditary sensory neuropathy, type 1.

Hereditary sensory neuropathy type 1 (HSN1, MIM 162400; ref. 1) genetically maps to human chromosome 9q22 (refs. 2-4).

Autonomous behavior of hematopoietic stem cells.

Mechanisms that affect the function of primitive hematopoietic stem cells with long-term proliferative potential remain largely unknown. Here we assessed whether properties of stem cells are cell-extrinsically or cell-autonomously regulated. We developed a model in which two genetically and phenotypically distinct stem cell populations coexist in a single animal.

A multicenter, randomized clinical study to evaluate the effect on cognitive function of topiramate compared with valproate as add-on therapy to carbamazepine in patients with partial-onset seizures.

Purpose: This study compares the cognitive effects of topiramate (TPM) with those of valproate (VPA) using efficacious doses of each drug when used as adjunctive therapy to carbamazepine (CBZ). A key question of the study is to what extent a more gradual introduction of TPM improves tolerability and prevents cognitive impairment.

Methods: The study is a multicenter, randomized, observer-blinded, parallel-group clinical trial with VPA or TPM given as first-line add-on therapy to steady-state treatment with CBZ.

Efficient mobilization of haematopoietic progenitors after a single injection of pegylated recombinant human granulocyte colony-stimulating factor in mouse strains with distinct marrow-cell pool sizes.

We have compared the efficacy of a single injection of SD/01, a newly engineered, pegylated form of recombinant human granulocyte colony stimulating factor (rhG-CSF), with a single injection of glycosylated rhG-CSF (Filgrastim). SD/01 was administered to regular and recombinant inbred strains of mice (AKR, C57L/J, DBA/2, C57BL/6, AKXL) known to have widely distinct marrow-cell pool sizes and proliferation kinetics. A single injection of G-CSF was unable to mobilize granulocyte-macrophage colony-forming units (CFU-GM).

Distinct functional properties of highly purified hematopoietic stem cells from mouse strains differing in stem cell numbers.

We have previously demonstrated that young adult DBA/2 (DBA) mice have more stem cells than C57BL/6 (B6) mice, as measured in a cobblestone area-forming cell (CAFC) assay using unfractionated marrow. To study the nature of this difference, we have now compared the proliferative fate of single, highly enriched Sca-1(+)c-kit(+)Lin(-) stem cells from these strains. Although equal in frequency, functional comparison revealed that Sca-1(+)c-kit(+)Lin(-) cells from DBA mice contained twice as many cells with CAFC activity.

Genome search for susceptibility loci of common idiopathic generalised epilepsies.

Genetic factors play a major role in the aetiology of idiopathic generalised epilepsies (IGEs). The present genome scan was designed to identify susceptibility loci that predispose to a spectrum of common IGE syndromes. Our collaborative study included 130 IGE-multiplex families ascertained through a proband with either an idiopathic absence epilepsy or juvenile myoclonic epilepsy, and one or more siblings affected by an IGE trait.

Estrogen receptor-KRAB chimeras are potent ligand-dependent repressors of estrogen-regulated gene expression.

As an approach to targeted repression of genes of interest, we describe the development of human estrogen receptor (ER) alpha-KRAB repressor domain chimeras that are potent ligand-dependent repressors of the transcription of estrogen response element (ERE)-containing promoters and analyze their mechanisms of action. Repression by the KRAB domain was dominant over transactivation mediated by ER AF1 and AF2. An ERE and an ER ligand (estrogen or antiestrogen) were required for repression.

Dynamic changes in mouse hematopoietic stem cell numbers during aging.

To address the fundamental question of whether or not stem cell populations age, we performed quantitative measurements of the cycling status and frequency of hematopoietic stem cells in long-lived C57BL/6 (B6) and short-lived DBA/2 (DBA) mice at different developmental and aging stages. The frequency of cobblestone area-forming cells (CAFC) day-35 in DBA fetal liver was twofold to threefold higher than in B6 mice, and by late gestation, the total stem cell number was nearly as large as that of young DBA adults. Following a further approximately 50% increase in stem cells between 6 weeks and 1 year of age, numbers in old DBA mice dropped precipitously between 12 and 20 months of age.

Genetic analysis of hemopoietic cell cycling in mice suggests its involvement in organismal life span.

Normal somatic cells undergo replicative senescence in vitro but the significance of this process in organismic aging remains controversial. We have shown previously that hemopoietic stem cells of common inbred strains of mice vary widely in cycling activity and that this parameter is inversely correlated with strain-dependent mean life span. To assess whether cell cycling and life span are causally related, we searched for quantitative trait loci (QTLs) that contributed to variation of these traits in BXH and BXD recombinant inbred mice.

Influence of an evacuation in February 1995 in The Netherlands on the seizure frequency in patients with epilepsy: a controlled study.

Purpose: Stress is often noted by patients to be a precipitating factor in causing seizures. No precise data are, however, available. In 1995 for 250,000 inhabitants in The Netherlands, a serious life event occurred within a period of seven days.

Sequence specificity of illegitimate plasmid recombination in Bacillus subtilis: possible recognition sites for DNA topoisomerase I.

Previous work in our group indicated that structural plasmid instability in Bacillus subtilis is often caused by illegitimate recombination between non-repeated sequences, characterized by a relatively high AT content. Recently we developed a positive selection vector for analysis of plasmid recombination events in B. subtilis which enables measurement of recombination frequencies without interference of selective growth differences of cells carrying wild-type or deleted plasmids.

Interactions of erythropoietin, granulocyte colony-stimulating factor, stem cell factor, and interleukin-11 on murine hematopoiesis during simultaneous administration.

We investigated how in vivo effects of single hematopoietic cytokines change if given in combination for a prolonged time. Mice were treated with every combination of recombinant human (rh) erythropoietin (EPO), rh granulocyte colony-stimulating factor (G-CSF), recombinant rat (rr) stem cell factor (SCF), and rh interleukin (IL)-11 by continuous infusion over 7 days (full factorial design with three dose levels for each cytokine). Burst-forming unit-erythroid (BFU-E), colony-forming unit-erythroid (CFU-E), and colony-forming unit-granulocyte-macrophage (CFU-GM) were determined in bone marrow and spleen, reticulocytes, hematocrit, granulocytes, and thrombocytes in the peripheral blood.