Histologic localization of terminal complement complexes in renal diseases. An immunohistochemical study

Histologic localizations of terminal complement complexes (TCCs) were examined and compared with clinical findings in 154 patients with various renal diseases. Immunohistochemical demonstration of TCCs was carried out on ethanol-fixed paraffin-embedded renal biopsy specimens by indirect immunoperoxidase technique. In glomerular diseases that are thought to be immune-complex glomerulonephritis (IC-GN), such as IgA-nephropathy, membranous nephropathy, and systemic lupus erythematosus (SLE), TCCs were demonstrated in a pattern similar to that of immunoglobulins and C3, indicating that TCCs were induced by immune complexes. The intensity of TCC deposition was correlated with the morphologic destruction of glomeruli or serum creatinine levels in IgA-nephropathy, with urine protein in membranous nephropathy, and with serum C4 in SLE. TCC deposits without IC were also observed in tissue damages without disease specificity such as glomerular or vascular sclerosis and tubulointerstitial lesions. These findings suggested the existence of various roles of TCCs in renal injury, according to IC-mediated or non-IC-mediated mechanism acting in individual diseases.     

Antitumor effect of seaweeds. IV. Enhancement of antitumor activity by sulfation of a crude fucoidan fraction from Sargassum kjellmanianum

We have reported an antitumor aqueous extract from a brown marine alga Sargassum kjellmanianum ("Hahakimoku" in Japanese). Although the extract was effective in the in vivo growth inhibition of the implanted Sarcoma-180 cells, it was not effective against L-1210-bearing mice. In the present study, we attempted to obtain a polysaccharide fraction with antitumor activity against L-1210 leukemia from this alga, on the assumption that the main active substance may be sulfated polysaccharide, especially fucoidan which is mainly composed of L-fucose and ester sulfate. Two kinds of polysaccharide fractions (SKCF and SKCF-F), which contained L-fucose and ester sulfate in the amount of 12.6% and 15.4%, 23.5% and 17.2% respectively, were first prepared starting with extraction with cold-hydrochloric acid, and their antitumor activity was examined. It was found however that they are not effective. Sulfation of SKCF was then carried out. The resulting sulfate (Sulfated SKCF) was observed to contain nearly 50% more ester sulfate than in SKCF and to be effective against L-1210 leukemia showing an ILS value of 26%. Mechanisms of antitumor action of this sulfate were also discussed from the viewpoints of negativity of ester sulfate and of activation of host-mediated immune response as known in antitumor polysaccharide preparations from other sources.     

Molecular biology of mammalian glucose transporters

The oxidation of glucose represents a major source of metabolic energy for mammalian cells. However, because the plasma membrane is impermeable to polar molecules such as glucose, the cellular uptake of this important nutrient is accomplished by membrane-associated carrier proteins that bind and transfer it across the lipid bilayer. Two classes of glucose carriers have been described in mammalian cells: the Na(+)-glucose cotransporter and the facilitative glucose transporter. The Na(+)-glucose cotransporter transports glucose against its concentration gradient by coupling its uptake with the uptake of Na+ that is being transported down its concentration gradient. Facilitative glucose carriers accelerate the transport of glucose down its concentration gradient by facilitative diffusion, a form of passive transport. cDNAs have been isolated from human tissues encoding a Na(+)-glucose-cotransporter protein and five functional facilitative glucose-transporter isoforms. The Na(+)-glucose cotransporter is expressed by absorptive epithelial cells of the small intestine and is involved in the dietary uptake of glucose. The same or a related protein may be responsible for the reabsorption of glucose by the kidney. Facilitative glucose carriers are expressed by most if not all cells. The facilitative glucose-transporter isoforms have distinct tissue distributions and biochemical properties and contribute to the precise disposal of glucose under varying physiological conditions. The GLUT1 (erythrocyte) and GLUT3 (brain) facilitative glucose-transporter isoforms may be responsible for basal or constitutive glucose uptake. The GLUT2 (liver) isoform mediates the bidirectional transport of glucose by the hepatocyte and is responsible, at least in part, for the movement of glucose out of absorptive epithelial cells into the circulation in the small intestine and kidney. This isoform may also comprise part of the glucose-sensing mechanism of the insulin-producing beta-cell. The subcellular localization of the GLUT4 (muscle/fat) isoform changes in response to insulin, and this isoform is responsible for most of the insulin-stimulated uptake of glucose that occurs in muscle and adipose tissue. The GLUT5 (small intestine) facilitative glucose-transporter isoform is expressed at highest levels in the small intestine and may be involved in the transcellular transport of glucose by absorptive epithelial cells. The exon-intron organizations of the human GLUT1, GLUT2, and GLUT4 genes have been determined. In addition, the chromosomal locations of the genes encoding the Na(+)-dependent and facilitative glucose carriers have been determined. Restriction-fragment-length polymorphisms have also been identified at several of these loci.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pathogenesis of impaired insulin secretion in NIDDM

The most important role of pancreatic beta-cells is the insulin secretion responding to the plasma glucose level. Molecular biological and electrophysiological approaches have been revealing the molecular mechanism of glucose-stimulated insulin secretion. A lot of key molecules of the systems, including GLUT2, glucokinase, SUR1, Kir6.2 and CD38, have been cloned and characterized whether the mutations in these genes are responsible for the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM). In this paper, we summarized the recent advances concerning pathogenesis of NIDDM in respect of impaired insulin secretion from pancreatic beta-cells.     

Urinary prostaglandin and sodium metabolism in patients with essential hypertension

Urinary prostaglandin E (PGE) excretion as an indicator of renal PGE, urinary aldosterone excretion, plasma renin activity, urinary sodium excretion, and urinary potassium excretion were measured after sodium depletion in 15 patients with essential hypertension to investigate the interaction between renal PGE and sodium metabolism. Following sodium depletion, urinary PGE excretion decreased, whereas urinary aldosterone excretion and plasma renin activity increased. Significant positive correlations were found between urinary PGE excretion and urinary sodium excretion (r=0.41, p less than 0.01) or urinary sodium excretion-urinary potassium excretion ratio (r = 0.43, p less than 0.005). These results support the hypothesis that the renal PGE may play an important role in the regulation of sodium metabolism and this action of PGE is independent of the renin-aldosterone system.     

Functionally distinct NKT cell subsets and subtypes

Natural killer T (NKT) cells are a population of autoreactive cells that mediate both protective and regulatory immune functions. NKT cells comprise several subsets of cells, but it has been unclear whether these different NKT cell subsets possess distinct functions in vivo. New studies now demonstrate that subsets of NKT cells are indeed functionally distinct and that the specific functions of these cells may be dictated in part by organ-specific mechanisms.