Molecular definition of a narrow interval at 7q22.1 associated with myelodysplasia

Chromosome 7 translocations, deletions, or monosomy are associated with myelodysplasia (MDS) and acute myeloid leukemia both in children and adults. These chromosomal anomalies represent one of the most common cytogenetic abnormalities associated with these diseases and usually herald a poor prognosis. In this study two cosmid DNA probes that mapped to 7q22.1 and were known to be separated by approximately 500 kb were identified to flank the proximal inversion breakpoint in a patient carrying a constitutional inversion (7q22.1-34) associated with MDS. A yeast artificial chromosome (YAC) clone that encompassed the two cosmids was identified and shown to span the breakpoint. Fluorescence in situ hybridization was then used to analyze six additional patients with myelodysplasia and chromosomal rearrangements of the 7q22 region (three patients had translocations and three carried deletions). The breakpoint in one of the patients was found to be contained within the same YAC clone that spanned the inversion breakpoint. Moreover, this same interval was determined to be absent in all three patients with chromosomal deletions. These results suggest that this segment of DNA on chromosome 7q22.1 may contain specific gene(s) that have a significant role in myeloid malignancies.     

Expression of murine CD38 defines a population of long-term reconstituting hematopoietic stem cells

Using a monoclonal antibody to murine CD38, we showed that a population of adult bone marrow cells that expressed the markers Sca-1 and c-kit but lacked the lineage markers Mac-1, GR-1, B220, IgM, CD3, CD4, CD8 and CD5 could be subdivided by the expression of CD38. We showed that CD38high c-kit+ Sca-1+, linlow/-cells sorted from adult bone marrow cultured with interleukin-3 (IL-3), IL-6, and kit-L produced much larger colonies in liquid culture at a greater frequency than their CD38low/- counterparts. In addition, we found that CD36low/ - cells contained most of the day-12 colony-forming units-spleen (CFU-S) but were not long-term reconstituting cells, whereas the population that expressed higher levels of CD38 contained few, but significant, day-12 CFU-S and virtually all the long-term reconstituting stem cells. Interestingly, the CD38high Sca-1+ c-kit+ linlow/- cells isolated from day-E14.5 fetal liver were also found to be long-term reconstituting stem cells. This is in striking contrast to human hematopoietic progenitors in which the most primitive hematopoietic cells from fetal tissues lack the expression of CD38. Furthermore, because antibodies to CD38 could functionally replace antibodies to Thy-1.1 in a stem cell purification procedure, the use of anti-CD38 may be more generally applicable to the purification of hematopoietic stem cells from mouse strains that do not express the Thy-1.1 allele.     

Report: workshop on mediastinal grey zone lymphoma

Abstract:  There are several indications that classical Hodgkin lymphoma (cHL) and at least a proportion of cases of Primary Mediastinal B cell Lymphoma (PMBL) are derived from B cells at similar stages of differentiation and share common pathogenic mechanisms. The first indication was the existence of mediastinal grey zone lymphomas as identified in the 4th International Symposium on HL, with clinical, histological and immunohistochemical features intermediate between cHL and PMBL. Second, both tumor types resemble a cell that is developmentally situated in-between the germinal center reaction and a plasma cell. Third, cHL and PMBL were found to have similar gene expression profiles, including the lack of immunoglobulin expression and low levels of B cell receptor signalling molecules, and the secretion of molecules like the chemokine TARC and the prominent expression of IL-13 receptors. Fourth, both entities were found to have common genomic aberrancies, notably in 2p15 and 9p24, the sites of the REL oncogene and the tyrosine kinase gene JAK2, respectively. Further comparison of both lymphoma types may provide further insight in the pathogenic mechanisms and allow the design of diagnostic algorithms to sort out the small number of so-called mediastinal grey zone lymphomas, that appear to be intermediate between PMBL and cHL.     

Predictive markers of chronic liver disease in hemophilia

In an attempt to predict progressive liver damage in hemophiliac patients by noninvasive means, we conducted a retrospective analysis of clinical and laboratory data from 44 liver biopsies taken from 35 hemophiliac patients. This showed that serum IgG was normal in patients with chronic persistent hepatitis (CPH) but significantly elevated in those with chronic active hepatitis (CAH) or cirrhosis (CIR) (P less than .001). Relationships were less significant between liver histology and IgM (P less than .01), IgA (P less than .05), and globulin (P less than .05). This was unaffected by human immunodeficiency virus (HIV) antibody status in asymptomatic individuals. Although patients with progressive liver disease were also older than those with CPH (P less than .001), the immunoglobulin abnormalities were independent of this. Neither clinical examination nor liver biochemistry at the time of biopsy were of significant diagnostic value. Our results indicate that in the absence of AIDS an elevated IgG level is a reliable indicator of progressive hemophilic liver disease.     

A frequent TG deletion near the polyadenylation signal of the human HEXB gene: Occurrence of an irregular DNA structure and conserved nucleotide sequence motif in the 3′ untranslated region

While screening for new mutations in the HEXB gene, which encodes the β-subunit of β-hexosaminidase, a TG deletion (ΔTG) was found in the 3′ untranslated region (3′UTR) of the gene, 7 bp upstream from the polyadenylation signal. Examination of DNA samples of 145 unrelated Argentinean individuals from different racial backgrounds showed that the ΔTG allele was present with a frequency of approximately 0.1, compared with the wild-type (WT) allele. The deletion was not associated with infantile or variant forms of Sandhoff disease when present in combination with a deleterious allele. Total Hex and Hex B enzymatic activities measured in individuals heterozygous for ΔTG and a null allele, IVS-2+1G→A (G→A), were approximately 30% lower than the activities of G→A/WT individuals. Analysis of the HEXB mRNA from leukocytes of ΔTG/WT individuals by RT-PCR of the 3′UTR showed that the ΔTG allele is present at lower level than the WT allele. By polyacrylamide gel electrophoresis, it was determined that a PCR fragment containing the +TG version of the 3′UTR of the HEXB gene had an irregular structure. On inspection of genes containing a TG dinucleotide upstream from the polyadenylation signal we found that this dinucleotide was part of a conserved sequence (TGTTTT) immersed in a A/T-rich region. This sequence arrangement was present in more than 40% analyzed eukaryotic mRNAs, including in the human, mouse and cat HEXB genes. The significance of the TG deletion in reference to Sandhoff disease as well as the possible functional role of the consensus sequence and the DNA structure of the 3′UTR are considered. Hum Mutat 12:320–329, 1998.© 1998 Wiley-Liss, Inc.     

Using a phenomenological research technique to examine student nurses' understandings of experiential teaching and learning: a critical review of methodological issues

This paper provides a report of the usage of a phenomenological research methodology to investigate the influence on clinical practice of pre- and post-registration nurse education which makes explicit use of experiential teaching and learning approaches. The primary aim of the research was to explore the use of a phenomenological research methodology to examine the students'understanding of experiential teaching and learning. The claims made for the use of experiential teaching and learning approaches in both pre- and post-registration nurse courses and how clinical practice is influenced by the experiential learning elements of pre- and post-registration nurse education were also examined. The first stage of the enquiry involved focused non-directive interviews with members of BSc Nursing Studies and MSc Mental Health Branch programmes. Both programmes claim to make use of experiential teaching and learning. The data were analysed using a technique developed by Giorgi. Previous experiences of experiential teaching and learning were probed, student interpretations differentiated, and the relationship between course-based learning using experiential approaches and the implications for it's influence on practice were examined. The second stage of the enquiry has followed up the initial findings, exploring the students'experience of experiential approaches on their courses both in the classroom and in work-based learning situations. The findings are presented and discussed in the context of other studies from both nurse and higher education. Throughout the paper methodological concerns arising are discussed. The paper concludes with the identification of methodological problems arising from the research strategy: the implications of the power nexus created when teachers research students, and issues relating to the use of a phenomenological methodology in a longitudinal study.     

Production of the proto-oncogene BAX does not vary with changing in luteal function in women

The mechanisms of luteal maintenance and regression in women are uncertain, but morphological and oligonucleosome studies raise the possibility that apoptosis may be involved. BAX is a proto-oncogene of the BCL-2 family which can induce apoptosis. The aim of this study was to determine whether BAX is expressed in the human corpus luteum and whether the level of expression changes relative to the stage of the luteal phase or in simulated early pregnancy. Carefully timed samples of corpus luteum were studied by immunostaining, sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblotting. BAX protein was immunolocalized in luteal sections from all stages including luteal rescue but BAX production did not change during luteal maintenance or regression. Localization of BAX to the steroid-secreting cells of the corpus luteum implies a functional role and BAX may interact with other members of the BCL-2 family to affect luteal function.      

Impassable urethral strictures: percutaneous transvesical catheterization and balloon dilatation

Urethral strictures that are impassable in retrograde fashion present a special problem to the urologist because they cannot be managed by standard dilatation techniques or direct-vision internal urethrotomy. Open urethroplasty is usually required. We describe a technique to catheterize the urethra in an antegrade fashion and dilate the strictures. Our study involved six patients with impassable urethral strictures that were successfully traversed and dilated. Percutaneous transvesical antegrade catheterization and balloon dilatation are beneficial for patients with bladder outlet obstruction.