Identification of the human sphingolipid C4-hydroxylase, hDES2, and its up-regulation during keratinocyte differentiation

AbstractThe C4-hydroxylation of dihydrosphingosine or dihydroceramide is a key reaction in the biosynthesis of phytosphingolipids, both in yeasts and in mammalian cells. Mouse DES2 (mDES2) was recently cloned and shown to work as a Δ4-desaturase/C4-hydroxylase, when expressed in yeast cells. Here, we cloned a human homologue of mDES2, hDES2, by homology search utilizing a BLAST program. When expressed in HEK 293 cells, hDES2 exhibited hydroxylase activity for dihydroceramide. Northern blot analyses of hDES2 revealed high expression in skin, intestines, and kidney, sites reportedly possessing high levels of phytosphingolipids. Furthermore, up-regulation of hDES2 mRNA expression and subsequent phytoceramide production were observed during vitamin C/serum-induced differentiation of human keratinocytes. These results suggest that the newly cloned hDES2 plays an essential role in phytosphingolipid synthesis in human skin and other phytosphingolipid-containing tissues

A glomerular permeability factor produced by human T cell hybridomas

A glomerular permeability factor produced by human T cell hybridomas. T cell hybridomas derived from the T cells of a patient with minimal change nephrotic syndrome (MCNS) made a glomerular permeability factor (GPF). Sufficient quantities of GPF were available for further analysis and characterization. We obtained four stable clones of human T cell hybridomas which produced a glomerular permeability factor. When this factor was injected intravenously into rats, significant proteinurias were induced, and in normal human lymphocyte culture, GPF enhanced Concanavalin-A (Con-A) induced lymphocyte histogenesis by greater than ten fold. GPF was cytotoxic to tumor cell lines of epithelial origin, but only cytostatic to tumor cells of hematopoietic origin. Electron microscopy studies, with polyethyleneimine (PEI) staining, indicated that GPF induced the changes in the arrangement of PEI particles and partial fusion of glomerular epithelial cells in the rats given this factor intravenously. The molecular weight of GPF were estimated to be between 60,000 and 160,000 daltons. The molecular weight of the factor and its TNF like activity, we speculated that the factor was a lymphokine, like lymphotoxins

Evaluation of capillary pore size characteristics in high-strength concrete at early ages

金沢大学工学部The quantitative scanning electron microscope-backscattered electron (SEM-BSE) image analysis was used to evaluate capillary porosity and pore size distributions in high-strength concretes at early ages. The Powers model for the hydration of cement was applied to the interpretation of the results of image analysis. The image analysis revealed that pore size distributions in concretes with an extremely low water/binder ratio of 0.25 at early ages were discontinuous in the range of finer capillary pores. However, silica-fume-containing concretes with a water/binder ratio of 0.25 had larger amounts of fine pores than did concretes without silica fume. The presence of larger amounts of fine capillary pores in the concretes with silica fume may be responsible for greater autogenous shrinkage in the silica-fume-containing concretes at early ages