Transfected leukocyte integrin CD11b/CD18 (Mac-1) mediates phorbol ester-activated, homotypic cell:cell adherence in the K562 cell line

The CD11b/CD18 leukocyte integrin molecule mediates diverse neutrophil adherence-related functions, including cell:cell and cell:extracellular matrix attachments. To study the individual role of this leukocyte integrin in cell adherence in hematopoietic cells, we expressed the CD11b/CD18 complex on the surface of K562 cells, a cell line derived from an individual with chronic myelogenous leukemia in blast crisis. We used an amphotrophic retroviral vector designated LCD18SN, harboring the complete coding sequence for the CD18 subunit, to transfer the CD18 cDNA into K562 cells and select stable cell lines. The CD11b subunit in the expression plasmid pREP4 was transfected into these K562/CD18 cells by electroporation and stable cell clones were selected. These K562 cells possessed RNA and intracellular protein for each subunit, and they expressed the CD11b/CD18 heterodimer on the cell surface. When CD11b/CD18 expressing K562 cells were stimulated with phorbol myristate acetate (50 ng/mL) for 24 to 48 hours, these K562 cells formed dense cell:cell aggregates. This homotypic aggregation required both activation of the CD11b/CD18 complex and the induction of the counter- receptor for CD11b/CD18 on the conjugate cell. This cell line will (1) enable the structure-function relationships between cell activation and homotypic adherence to be assessed, (2) provide the opportunity to identify accessory molecules required for activation of the CD11b/CD18 complex, and (3) facilitate the identification of novel ligands for the CD11b/CD18 complex.     

Gerota versus Zuckerkandl: the renal fascia revisited

In the medical literature, Gerota fascia is frequently used as a general term to describe both the anterior and posterior pararenal fascia. However, Zuckerkandl's name is also often used to describe either the anterior or posterior fascia. To resolve this confusion, the authors reviewed the original works by Gerota and Zuckerkandl. In 1883, Zuckerkandl described the posterior renal fascia but did not recognize the presence of the anterior renal fascia. In 1895, Gerota documented the presence of the anterior renal fascia and clearly assigned Zuckerkandl's name to the posterior renal fascia. Thus, the terms Zuckerkandl fascia and posterior renal fascia are synonymous, as are Gerota fascia and anterior renal fascia.     

Arsenic intoxication as a cause of megaloblastic anemia

We have described a case of chronic arsenic intoxication associated with pancytopenia and megaloblastic erythropoiesis. The patient had the typical laboratory manifestations of effective erythorpoiesis due to a megaloblastic process, including macroovalocytes, mild pancytopenia, low reticulocyte index, increased marrow cellularity with erythroid hyperplasia, and morphologic evidence of megaloblastic maturation in the marrow. The patient's serum folate and vitamin B12 were normal, and the anemia regressed without therapy. Our case suggests that the combination of megaloblastosis with normoblastic or megaloblastic karyorrhexis,should raise the suspicion of arsenic intoxication in the mind of the observer. In addition, arsenic should be added to the list of agents causing a reversible megaloblastic anemia.     

Intrauterine growth retardation: evaluation by magnetic resonance. Work in progress

Eleven high risk fetuses between 32 and 37 menstrual weeks gestational age were examined by magnetic resonance (MR) imaging. Serial obstetrical sonograms, birth weights, and serial postnatal examinations were obtained in all subjects. Sagittal MR spin echo images obtained using TR = 0.5 sec and TE = 28 msec were useful for assessing subcutaneous fat. Prospective estimates of fetal fat stores correlated with neonatal outcome better than sonographic measurements of fetal growth parameters or actual birth weight. MR appears to be a safe and useful technique that offers information complementary to obstetrical sonography when IUGR is suspected.