Selection of an HEL-derived cell line expressing high levels of platelet factor 4

A platelet factor 4 (PF4)-expressing cell line, HELNeo, was derived from the human erythroleukemia cell line, HEL. This was achieved by stable transfection of HEL cells with a construct containing the rat PF4 promoter driving the gene coding for resistance to neomycin, followed by selection of neomycin-resistant clones. HELNeo cells were all nonadhering and about 5% of the cells had polyploid nuclei (> or = 8N), as compared with 1% in HEL cells. Immunohistochemistry showed that about 90% of the HELNeo cells contained PF4, whereas only approximately 5% of the HEL cells contained PF4. No significant parallel enrichment was observed for other megakaryocytic markers, such as the glycoprotein complex IIb/IIIa, von Willebrand factor, and platelet activation- dependent granule to external membrane glycoprotein (PADGEM), which were present to a similar extent in both HEL and HELNeo lines. The increased expression of PF4 in HELNeo cells was confirmed by transient expression assays and was associated with a fivefold increase in trans- acting factors binding to the PF4 promoter. These cells should be a rich source for purifying trans-acting factors binding to the PF4 gene. Moreover, our study shows how a lineage-specific promoter may be used to generate lineage-specific cell lines from a multilineage hematopoietic cell line.     

Cytogenetic studies in patients with secondary leukemia/dysmyelopoietic syndrome after different treatment modalities

Cytogenetic studies of 68 patients who developed secondary leukemia (SL)/dysmyelopoietic syndrome (DMS) after extensive chemotherapy and/or radiation therapy as well as patients who developed SL/DMS without such treatment showed that those patients who received radiation alone or with chemotherapy had more extensive numerical and structural abnormalities than those who received only chemotherapy. In terms of the specific chromosomal abnormalities, there are no differences between the various treatment groups. Hypodiploidy is the most common form of aneuploidy in these patients, with the most common numerical abnormality being the loss of chromosome 7. The most common structural abnormalities involved chromosomes 3 and 5. When compared with patients with de novo leukemia and DMS, the chromosomal abnormalities in these patients are more complex and extensive. Serial studies revealed that cytogenetic abnormalities do not precede the development of hematologic changes by significant time periods.     

Human platelet fibrinogen: purification and hemostatic properties

Conditions were developed in which 80% to 90% of platelet fibrinogen could be routinely purified in nondegraded form from the fluid phase of platelet suspensions stimulated with the calcium ionophore, A23187, in the presence of calcium, leupeptin, and prostaglandin E1. Fibrinogen was separated from other released proteins by chromatography on diethylaminoethanol (DEAE)-cellulose using a continuous pH and ionic strength gradient. Purified platelet fibrinogen, greater than 98% homogeneous by immunoelectrophoresis and sodium-dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE), consisted of intact A alpha, B beta and gamma A chains, but not gamma' chains, and was 95% to 96% clottable. Platelet fibrinogen was shown to compete for the binding of radiolabeled plasma fibrinogen to ADP-activated platelets in a manner identical to that of unlabeled plasma fibrinogen itself. Also, at equivalent protein concentrations, platelet and plasma fibrinogens supported platelet aggregation to an equivalent extent. Based upon these results, we conclude that there is no significant difference between platelet and plasma fibrinogen with respect to their size, their clottability, their affinity for the activated platelet fibrinogen receptor, or their capacity to support subsequent platelet aggregation.     

Ulnar nerve injuries of the hand producing intrinsic muscle denervation on magnetic resonance imaging

Muscle and nerve injuries in the hand may be difficult to detect and diagnose clinically. Two cases are reported in which magnetic resonance imaging showed ulnar nerve injury and intrinsic hand muscle denervation. The clinical, anatomical and radiological features of injury to the deep motor branch of the ulnar nerve and associated muscle denervation are discussed and illustrated.     

Selective delivery of chemotherapeutic agents with a new catheter system

A new catheter system was used in ten patients (16 infusions) for infusion of chemotherapeutic agents to the sites of malignant gliomas. Thirteen infusions to the supraophthalmic region were successful, as were three infusions to the posterior cerebral region. There were no complications after the infusions. A neurologic complication occurred in one patient in whom two successful supraophthalmic infusions were previously carried out. In this patient the guide wire separated during catheter placement into the posterior cerebral artery.     

Altered functional responsiveness of thymocyte subsets from CD3delta- deficient mice to TCR-CD3 engagement

CD3delta-deficient (delta degrees) mice are defective in alphabeta T cell development. Here we explore the capacity of TCR-CD3 signaling complexes expressed on delta degrees thymocytes to mediate the following functional outcomes in response to antibody cross-linking: (i) the transition from the CD4-CD8- to CD4+CD8+ stage, (ii) the transition from the CD4+CD8+ to CD4+CD8- or CD4-CD8+ stages and (iii) the induction of apoptosis. We provide evidence that CD3deltaepsilon complexes are dispensable for mediating the anti-CD3-mediated CD4-CD8- to CD4+CD8+ transition. On the other hand, CD3delta is critical at the CD4+CD8+ stage. We demonstrate that CD4+CD8+ thymocytes from delta degrees mice, unlike delta degrees CD4-CD8- thymocytes and wild-type CD4+CD8+ thymocytes, require prolonged or consecutive stimuli to elicit functional responses. Depending on the nature of the secondary stimulus, delta degrees thymocytes can be induced to undergo apoptosis or preferential maturation to the CD4-CD8+ stage. Taken together these results indicate that the signaling capacity of the TCR-CD3 complex is noticeably altered in the absence of CD3delta. The essential role of CD3delta at the CD4+CD8+ stage of development correlates with the onset of TCRalpha rearrangement, consistent with a critical structural and/or functional relationship between CD3delta and TCRalpha.