INTRA-AORTIC BALLOON RUPTURE CAUSING FEMORAL ENTRAPMENT

Rupture of an intra-aortic balloon counterpulsator (IABCP) demands immediate removal. We report a case of thrombus formation within a Datascope IABCP secondary to IABCP rupture, necessitating surgical exploration for removal. There is a disturbing pattern of balloon ruptures with this type of IABCP.     

PJA-BP expression and TCR delta deletion during human T cell differentiation

Recombination of deltaRec to psiJalpha will delete the TCR delta gene, which is thought to play an important role in the bifurcation of the TCR alphabeta versus TCR gammadelta differentiation lineages. We recently detected a DNA-binding protein in human thymocytes, the so- called PJA-BP, which recognizes the psiJalpha gene segment and might be one of the factors involved in the regulation of preferential deltaRec- psiJalpha rearrangements. We now investigate PJA-BP expression and its correlation with TCR delta gene deletion in thymocytes. Our electrophoretic mobility shift assay experiments showed that the PJA-BP is evolutionary conserved in human, murine and simian thymocytes. Using a large series of human hematopoietic malignancies (n = 30), we conclude that PJA-BP expression is thymocyte specific and seems to be restricted to thymocytes committed to the TCR alphabeta lineage. Analysis of seven well-defined human thymocyte subpopulations showed that preferential deltaRec-psiJalpha rearrangements as well as PJA-BP expression can be detected from the immature CD34-/CD1+/CD3- /CD4+/CD8alpha+beta- thymocyte differentiation stage onwards. These experiments indicate that expression of PJA-BP in human thymocytes starts simultaneously with preferential deltaRec-psiJalpha rearrangements, which supports our hypothesis that PJA-BP is one of the factors involved in the preferential recombination of deltaRec to psiJalpha.      

Effects of mercury on human polymorphonuclear leukocyte function in vitro.

A variety of heavy metals are recognized as environmental pollutants, and although a significant body of literature exists on the acute toxicity of these metals in various tissues, little is known about the effects of metals such as mercury on host defense. Therefore, the effect of mercuric chloride (HgCl2) on human polymorphonuclear leukocytes (PMN) function in vitro was evaluated. The acute toxicity of HgCl2 for human PMN was calculated initially using vital dye exclusion (trypan blue), and lactate dehydrogenase (LDH) release. Concentrations of HgCl2 less than or equal to 10(-6) M did not induce significant LDH release, or uptake of trypan blue. Additionally, HgCl2 at less than or equal to 10(-7) M produced no ultrastructural alterations in the PMN. The effects of HgCl2 on human PMN functions involved in host defense were evaluated next. HgCl2 consistently suppressed human PMN adherence, polarization, chemotaxis, and erythrophagocytosis at concentrations between 10(-6) and 10(-17) M. Because of the established role of oxygen metabolites in host defense, the effects of HgCl2 on human PMN chemiluminescence and H2O2 production were evaluated next. These studies demonstrated that low concentrations of HgCl2 (ie, 10(-9)-10(-15) M) significantly enhanced chemiluminescence, as well as stimulated H2O2 production by the PMN. These studies clearly demonstrate the ability of extremely low levels of HgCl2 not only to suppress various PMN functions involved in host defense, but also to stimulate oxygen metabolism. In vivo, these HgCl2 effects would not only compromise host defense but also promote tissue injury via the local production of oxygen metabolites.     

Missense mutation in a von Willebrand factor type A domain of the alpha 3(VI) collagen gene (COL6A3) in a family with Bethlem myopathy

The Bethlem myopathy is a rare autosomal dominant proximal myopathy characterized by early childhood onset and joint contractures. Evidence for linkage and genetic heterogeneity has been established, with the majority of families linked to 21q22.3 and one large family linked to 2q37, implicating the three type VI collagen subunit genes, COL6A1 (chromosome 21), COL6A2 (chromosome 21) and COL6A3 (chromosome 2) as candidate genes. Mutations of the invariant glycine residues in the triple-helical domain-coding region of COL6A1 and COL6A2 have been reported previously in the chromosome 21-linked families. We report here the identification of a G-->A mutation in the N-terminal globular domain-coding region of COL6A3 in a large American pedigree (19 affected, 12 unaffected), leading to the substitution of glycine by glutamic acid in the N2 motif, which is homologous to the type A domains of the von Willebrand factor. This mutation segregated to all affected family members, to no unaffected family members, and was not identified in 338 unrelated Caucasian control chromosomes. Thus mutations in either the triple-helical domain or the globular domain of type VI collagen appear to cause Bethlem myopathy.