Search

During high-salt (HS) diet the kidney increases urinary Na+ and volume excretion to match intake. We recently reported that HS provokes a redistribution of distal convoluted tubule Na+-Cl− cotransporter (NCC) from apical to subapical vesicles and decreases NCC abundance. This study aimed to test the hypothesis that the other renal Na+ transporters' abundance and or subcellular distribution is decreased by HS diet. Six-week-old Sprague-Dawley rats were fed a normal (NS) 0.4% NaCl diet or a HS 4% NaCl diet for 3 wk or overnight. Kidneys excised from anesthetized rats were fractionated on density gradients or analyzed by microscopy; transporters and associated regulators were detected with specific antibodies. Three-week HS doubled Na+/H+ exchanger (NHE)3 phosphorylation at serine 552 and provoked a redistribution of NHE3, dipeptidyl peptidase IV (DPPIV), myosin VI, Na+-Pi cotransporter (NaPi)-2, ANG II type 2 receptor (AT2R), aminopeptidase N (APN), Na+-K+-2Cl− cotransporter (NKCC2), epithelial Na+ channel (ENaC) β-subunit, and Na+-K+-ATPase (NKA) α1- and β1-subunits from low-density plasma membrane-enriched fractions to higher-density intracellular membrane-enriched fractions. NHE3, myosin VI, and AT2R retraction to the base of the microvilli (MV) during HS was evident by confocal microscopy. HS did not change abundance of NHE3, NKCC, or NKA α1- or β1-subunits but increased ENaC-β in high-density intracellular enriched membranes. Responses to HS were fully apparent after just 18 h. We propose that retraction of NHE3 to the base of the MV, driven by myosin VI and NHE3 phosphorylation and accompanied by redistribution of the NHE3 regulator DPPIV, contributes to a decrease in proximal tubule Na+ reabsorption during HS and that redistribution of transporters out of low-density plasma membrane-enriched fractions in the thick ascending limb of the loop of Henle and distal nephron may also contribute to the homeostatic natriuretic response to HS diet.

Udgivelsesdato: 2008-Mar BACKGROUND & AIMS: Previously, we showed high-level, long-term liver replacement after transplantation of unfractionated embryonic day (ED) 14 fetal liver stem/progenitor cells (FLSPC). However, for clinical applications, it will be essential to transplant highly enriched cells, while maintaining high repopulation potential. METHODS: Dlk-1, a member of the delta-like family of cell surface transmembrane proteins, is highly expressed in human and rodent fetal liver. Dlk-1(+) cells, isolated from ED14 fetal liver using immunomagnetic beads, were examined for their hepatic gene expression profile and characteristic properties in vitro and their proliferative and differentiation potential in vivo after transplantation into normal adult rat liver. RESULTS: Rat ED14 FLSPC were purified to 95% homogeneity and exhibited cell culture and gene expression characteristics expected for hepatic stem/progenitor cells. Rat ED14 FLSPC are alpha-fetoprotein(+)/cytokeratin-19(+) or alpha-fetoprotein(+)/cytokeratin-19(-) and contain all of the normal liver repopulation capacity found in fetal liver. Hematopoietic stem cells, a major component in crude fetal liver cell preparations that engraft in other organs, such as bone marrow, spleen, and lung, are totally removed by Dlk-1 selection, and Dlk-1 purified FLSPC repopulate only the liver. CONCLUSIONS: This is the first study reporting purification of hepatic stem/progenitor cells from fetal liver that are fully capable of repopulating the normal adult liver. This represents a major advance toward developing protocols that will be essential for clinical application of liver cell transplantation therapy.

The effect of low-dose methotrexate (MTX) treatment on the CD26 density on circulating monocytes and CD4(+) T lymphocytes or levels of soluble CD26 (sCD26) has not yet been described in rheumatoid arthritis (RA). While CD26 in T lymphocytes is involved in the activation and proliferation of T lymphocytes, little is known of the role of CD26 in monocytes as it has only recently been localized to monocytes. We analysed the CD26 density by flow cytometry and levels of sCD26 in plasma before initiation of MTX treatment and 12 weeks later. This was done on 34 RA patients fulfilling the 1987 American College of Rheumatology (ACR) criteria followed for 16 weeks after starting MTX treatment. CD26 density on monocytes was increased in RA patients compared with healthy controls before MTX treatment (P < 0.01). After 12 weeks of MTX treatment, the CD26 density on monocytes decreased significantly in the ACR-50% group (P = 0.03), but not in the ACR-20% and the non-responder group (P = 0.15 and 0.87). The increased CD26 density on CD4(+) T lymphocytes (P < 0.01) was unaffected by the reduction in disease activity in relation to MTX treatment. The percentage of monocytes and CD4(+) T lymphocytes among peripheral blood circulating mononuclear cells did not change during MTX treatment. No effect of MTX treatment was observed on the plasma levels of sCD26. Active chronic RA is characterized by enhanced CD26 density on circulating monocytes and CD4(+) T lymphocytes. MTX treatment decreased CD26 density on monocytes in the ACR-50% responder group and was associated with decreased disease activity. The enhanced CD26 density on CD4(+) T lymphocytes was uninfluenced by MTX treatment.

Udgivelsesdato: 2009-Jun BI 1356, a xanthine-based DPP-4 inhibitor, has reached Phase III trials. The compound efficiently inhibits dipeptidyl peptidase 4 (DPP-4) in vitro and in vivo. In vivo GLP-1 levels increase to levels at or above the levels of other DPP-4 inhibitors. Preclinical trials suggest a once-daily administration of 5 mg to be efficient, long-lasting and without known side effects.