Stability of multiple antigen receptor gene rearrangements and immunophenotype in Hodgkin's disease-derived cell line L428 and variant subline L428KSA.

The Hodgkin's disease (HD) derived cell line L428 and a phorbol ester-selected subline L428KSA, which have been independently passaged in tissue culture for several years, were studied for possible antigen receptor gene and immunophenotypic differences. Multiple but identical alterations of these genes were found, including: the deletion of one and rearrangement of the other immunoglobulin (Ig) heavy chain allele; the rearrangement of one kappa and one lambda light chain allele; and the rearrangement of one T cell receptor (TCR) beta allele. Restriction mapping of the Ig heavy chain locus indicated that rearrangement of the retained allele produced a JH-C gamma 4 fusion product by an isotype switch mechanism. The 14q+ chromosome [t(14q32;?)] present in both cell cultures derived either from translocation 5' (telomeric) to the rearranged JH allele or 3' (centromeric) to the deleted Ig heavy chain allele and did not involve detectable rearrangement of the c-myc, bcl 1, or bcl 2 oncogenes. No differences in the immunophenotype were found between the L428 and L428KSA cells: both expressed leukocyte activation antigens and some determinants associated with myelomonocytic cells but no lymphoid markers. It is postulated that these phenotypic characteristics derived from secondary genetic events/differentiative reprogramming which produced extinction of primary lymphoid characters, including terminal deoxynucleotidyl transferase (TdT) essential to generation of the Ig and TCR gene rearrangements, and expression of an incomplete set of myelomonocytic markers.

Nitric oxide triggers programmed cell death (apoptosis) of adult rat ventricular myocytes in culture.

Excessive nitric oxide (NO) production within the heart is implicated in the pathogenesis of myocyte death, but the mechanism whereby NO kills cardiac myocytes is not known. To determine whether NO may trigger programmed cell death (apoptosis) of adult rat ventricular myocytes in culture, the NO donor S-nitroso-N-acetylpenicillamine (SNAP) was shown to kill purified cardiac myocytes in a dose-dependent fashion. In situ analysis of ventricular myocytes plated on chamber slides using nick-end labeling of DNA demonstrated that SNAP induces cardiac myocyte apoptosis, which was confirmed by the identification of oligonucleosomal DNA fragmentation on agarose gel electrophoresis. Similarly, treatment of cardiac myocytes with cytokines that induce inducible NO synthase was shown to cause an NO-dependent induction of apoptosis. Addition of reduced hemoglobin to scavenge NO liberated by SNAP extinguished both the increase in percentage of apoptotic cells and the appearance of DNA ladders. Treatment with SNAP (but not with N-acetylpenicillamine or SNAP + hemoglobin) not only induced apoptosis but resulted in a marked increase in p53 expression in cardiac myocytes detected by Western blotting and immunohistochemistry. These data indicate that NO has the capacity to kill cardiac myocytes by triggering apoptosis and suggest the involvement of p53 in this process.

A founder mutation in presenilin 1 causing early-onset Alzheimer disease in unrelated Caribbean Hispanic families.

CONTEXT: Genetic determinants of Alzheimer disease (AD) have not been comprehensively examined in Caribbean Hispanics, a population in the United States in whom the frequency of AD is higher compared with non-Hispanic whites. OBJECTIVE: To identify variant alleles in genes related to familial early-onset AD among Caribbean Hispanics. DESIGN AND SETTING: Family-based case series conducted in 1998-2001 at an AD research center in New York, NY, and clinics in the Dominican Republic. PATIENTS: Among 206 Caribbean Hispanic families with 2 or more living members with AD who were identified, 19 (9.2%) had at least 1 individual with onset of AD before the age of 55 years. MAIN OUTCOME MEASURE: The entire coding region of the presenilin 1 gene and exons 16 and 17 of the amyloid precursor protein gene were sequenced in probands from the 19 families and their living relatives. RESULTS: A G-to-C nucleotide change resulting in a glycine-alanine amino acid substitution at codon 206 (Gly206Ala) in exon 7 of presenilin 1 was observed in 23 individuals from 8 (42%) of the 19 families. A Caribbean Hispanic individual with the Gly206Ala mutation and early-onset familial disease was also found by sequencing the corresponding genes of 319 unrelated individuals in New York City. The Gly206Ala mutation was not found in public genetic databases but was reported in 5 individuals from 4 Hispanic families with AD referred for genetic testing. None of the members of these families were related to one another, yet all carriers of the Gly206Ala mutation tested shared a variant allele at 2 nearby microsatellite polymorphisms, indicating a common ancestor. No mutations were found in the amyloid precursor protein gene. CONCLUSIONS: The Gly206Ala mutation was found in 8 of 19 unrelated Caribbean Hispanic families with early-onset familial AD. This genetic change may be a prevalent cause of early-onset familial AD in the Caribbean Hispanic population.