Characterization of some of the enzymes in ragweed pollen.

Ragweed pollen contains 11 esterase, 5 acid phosphatase, 2 alkaline phosphatose, 2 hexokinase, 2 glucose-6-phosphate dehydrogenase isozymes and one leucine amino peptidase band which can be separated by starch gel electrophoresis. The isozymes were distinguished from one another by their electrophoretic mobility, heat inactivation temperatures and antigenic differences.     

Homozygosity mapping of achromatopsia to chromosome 2 using DNA pooling

Achromatopsia is an autosomal recessive disease of the retina, characterized clinically by an inability to distinguish colors, impaired visual acuity, nystagmus and photophobia. A genome-wide search for linkage was performed using an inbred Jewish kindred from Iran. To facilitate the genome-wide search, we utilized a DNA pooling strategy which takes advantage of the likelihood that the disease in this inbred kindred is inherited by all affected individuals from a common founder. Equal molar amounts of DNA from all affected individuals were pooled and used as the PCR template for short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected members of the kindred was used as a control. A reduction in the number of alleles in the affected versus control pool was observed at several loci. Upon genotyping of individual family members, significant linkage was established between the disease phenotype and markers localized on chromosome 2. The highest LOD score observed was 5.4 (theta = 0). When four additional small unrelated families were genotyped, the combined peak LOD score was 8.2. Analysis of recombinant chromosomes revealed that the disease gene lies within a 30 cM interval which spans the centromere. Additional fine-mapping studies identified a region of homozygosity in all affected individuals, narrowing the region to 14 cM. A candidate gene for achromatopsia was excluded from this disease interval by radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an essential first step in the identification of the disease-causing gene.      

Epithelial hyperplasia in human polycystic kidney diseases. Its role in pathogenesis and risk of neoplasia.

The importance of tubular epithelial hyperplasia in polycystic kidney diseases has become apparent during the last decade. Micropapillary hyperplasia occurs in autosomal dominant polycystic kidney disease, in localized cystic disease, and in acquired cystic disease. Neoplastic or severely dysplastic epithelial hyperplasia occurs in von Hippel-Lindau disease. A histopathologically distinctive epithelial hyperplasia occurs in tuberous sclerosis. In each of these conditions, epithelial hyperplasia may be related to cyst formation and may also impose an increased risk of malignancy--a risk that seems to be highest in patients under treatment with long-term hemodialysis for end-stage kidney disease. Although hyperplasia in some of these diseases may share a common pathway of development, it is more probable that the histopathologic differences reflect different pathogenetic pathways that converge on a common endpoint.     

Evaluation of phagocytic function in Mycobacterium lepraemurium infection

Infection of mice with Mycobacterium lepraemurium caused significant functional alterations of the mononuclear phagocyte system. Accelerated clearance of sheep red blood cells was consistently demonstrated throughout the infection and the infected mice showed progressive anaemia. Infected mice showed an enhanced ability to limit growth of phagocytosed Listeria monocytogenes in spleens during the early stages of infection, whereas moribund leprous mice lost this ability. Autoradiography showed that uninfected Kupffer cells and splenic macrophages of moribund mice could still phagocytose Listeria, suggesting that MLM infection did not affect the capacity of Listeria to localize to macrophages but interfered in some way with subsequent killing of such bacteria. The possible mechanisms underlying these observations are discussed.     

Identification of CD56 and CD57 by flow cytometry in Ewing’s sarcoma or primitive neuroectodermal tumor

 CD56 and CD57 are commonly considered as natural killer and neuroectodermal markers, but their expression has been identified in a wide spectrum of neoplasms including some cases of Ewing’s sarcoma (ES) and primitive neuroectodermal tumor (PNET). We report two cases of small, round blue cell tumor (SRBCT), in which flow cytometry immunophenotyping (FCI) detected strong expression of CD56 and CD57 (one case). Immunohistochemical staining with Leu-19 and Leu-7 confirmed the FI results. Although CD56 and CD57 expression is consistent with ES/PNET, it can be potentially misleading if results of FCI are interpreted in the absence of other findings. These cases suggest the utility of FCI in undifferentiated SRBCT. The literature on CD56 and CD57 expression in ES/PNET is reviewed and discussed. Received: 5 January 1998 / Accepted: 19 February 1998     

Morphogenetic clonal growth of kidney epithelial cell line MDCK

MDCK (Madin-Darby canine kidney) cells were cultured either dispersed within hydrated collagen gel (HCG) or seeded atop a collagen substrate and then immediately overlaid with HCG. Individual cells exhibited clonal growth in three dimensions to form spherical cysts made up of a simple epithelium enclosing a fluid-filled lumen. The cells of MDCK cysts were polarized with the basolateral surface in contact with the collagen gel and the apical surface bordering the lumen. The ultrastructure of MDCK cysts showed similarities to distal nephron. The cells bore apical microvilli and solitary cilia and had occluding junctions and a simple basolateral surface. MDCK cysts increased in size (greater than 800 microns diameter) with continued culture. MDCK cysts grown between layers of HCG were stripped free of the overlying collagen to give direct access to basolateral surface membrane. Unlike monolayer culture, morphogenetic clonal growth of cell line MDCK produces a polarized cell population with a true lumenal and basolateral surface. Collagen-gel-cultured MDCK cysts provide an easily manipulable in vitro cell system that may offer unique advantages for the study of renal cell structure and function.