Na(+)-coupled transport of L-carnitine via high-affinity carnitine transporter OCTN2 and its subcellular localization in kidney

The mechanism of Na(+)-dependent transport of L-carnitine via the carnitine/organic cation transporter OCTN2 and the subcellular localization of OCTN2 in kidney were studied. Using plasma membrane vesicles prepared from HEK293 cells that were stably transfected with human OCTN2, transport of L-carnitine via human OCTN2 was characterized. Uptake of L-[(3)H]carnitine by the OCTN2-expressing membrane vesicles was significantly increased in the presence of an inwardly directed Na(+) gradient, with an overshoot, while such transient uphill transport was not observed in membrane vesicles from cells that were mock transfected with expression vector pcDNA3 alone. The uptake of L-[(3)H]carnitine was specifically dependent on Na(+) and the osmolarity effect showed that Na(+) significantly influenced the transport rather than the binding. Changes of inorganic anions in the extravesicular medium and of membrane potential by valinomycin altered the initial uptake activity of L-carnitine by OCTN2. In addition, the fluxes of L-carnitine and Na(+) were coupled with 1:1 stoichiometry. Accordingly, it was clarified that Na(+) is coupled with flux of L-carnitine and the flux is an electrogenic process. Furthermore, OCTN2 was localized on the apical membrane of renal tubular epithelial cells. These results clarified that OCTN2 is important for the concentrative reabsorption of L-carnitine after glomerular filtration in the kidney.     

Identification of putative metabolites of docosahexaenoic acid as potent PPARgamma agonists and antidiabetic agents

We found that putative metabolites of docosahexaenoic acid (DHA) are strong PPARgamma activators and potential antidiabetic agents. We designed DHA derivatives based on the crystal structure of PPARgamma, synthesized them and evaluated their activities in vitro and in vivo. The efficacy of 5E-4-hydroxy-DHA 2a as a PPARgamma activator was about fourfold stronger than that of pioglitazone. Furthermore, the 4-keto derivative (10b) showed antidiabetic activity in animal models without producing undesirable effects such as obesity and hepatotoxicity.     

Free dorsoulnar perforator flap transfers for the reconstruction of severely injured digits

The aim of this study was to investigate the feasibility of transferring the free dorsoulnar perforator flap nourished by the cutaneous perforator branched dorsoulnar artery to reconstruct severely injured fingers under upper arm anesthesia. Between April of 2001 and April of 2002, 13 free dorsoulnar perforator flaps were used in 13 patients. There were 11 men and two women ranging in age from 18 to 64 years, with an average age of 38 years. The affected fingers were one thumb, four index fingers, five middle fingers, two ring fingers, and one little finger. All cases were performed under upper arm anesthesia combined with intravenous local anesthesia. The operative time ranged from 103 to 140 minutes, with an average time of 120 minutes. The flap size ranged from 1 x 3 to 3 x 4 cm, and was transferred from the same forearm of the injured finger. All donor sites were closed primarily without a skin graft. The aim of reconstruction for fingers was to repair a traumatic defect (five cases), partial necrosis following replantation (two cases), and soft-tissue defects resulting from resection of a scar (three cases) and to revascularize ischemic fingers (three cases). All flaps survived completely. After repair of the flow-through circulation of the common digital artery and ischemic finger, a postoperative angiogram showed the vascular patency and hypervascularity of the reconstructed fingers, and the patients' complaints were reduced. The free dorsoulnar perforator flap under regional anesthesia is first reported; it may become one valuable option as a very small flap for the treatment of repairing intercalated or segmental defects as a flow-through flap for soft-tissue defects and ischemic fingers.     

Extramedullary plasmacytoma of the thyroid gland producing gamma heavy chain

We encountered a 65-year-old man with gamma heavy chain disease associated with extramedullary plasmacytoma of the thyroid gland. Serum electrophoresis revealed an abnormal fast gamma band that cross-reacted with anti-IgG (Fc gamma) sera immunoelectrophoretically. Intracytoplasmic monoclonal immunoglobulin, IgG (Fc gamma), was demonstrated in thyroid tissue sections using an indirect immunofluorescence method. After surgery, the serum abnormal fast gamma band disappeared. At the time of writing, the patient has survived 18 months post-surgery.     

Expression of plasma membrane proton-ATPase gene in salt-tolerant yeast Zygosaccharomyces rouxii is induced by sodium chloride

Abstract The amounts of mRNA and protein of plasma membrane proton-ATPase were measured in the salt-tolerant yeast Zygosaccharomyces rouxii by Northern and Western blot analyses. Although their amounts were independent of growth phase, their synthesis were induced when yeast cells were grown in the presence of NaCl or were subjected to NaCl shock. This finding was consistent with our previous result that plasma membrane proton-ATPase activity was elevated in Z. rouxii cells grown in medium containing high concentrations of NaCl.     

Effect of immunoglobulin G on membrane-bound enzyme activity of sarcoma 180 cells

Changes in the activity of membrane bound ATPase of Sarcoma 180 cells caused by immunoglobulin G (IgG) of anti-Sarcoma 180 was investigated in relation to the incorporation of amino acid by the cells. Enzymatic activity of ATPase was increased up to 160% of the original activity upon incubation of the cell Igg. Kinetic studies showed that IgG did not change the affinity of this enzyme for the substrate but exerted influence upon catalytic efficiency of the enzyme. The rate of incorporation of leucine into Sarcoma 180 cells was also affected by IgG, as observed in the effect of IgG on the enzymatic reaction of the cells.     

A follow-up study of 85 patients with Graves' disease in remission who developed undetectable serum thyroid-stimulating hormone concentrations using sensitive TSH assays.

Eighty-five patients with Graves' disease in clinical remission after treatment for over 1 year by methimazole therapy (36 patients, group A) or subtotal thyroidectomy (49 patients, group B) who became undetectable for serum thyrotropin levels (TSH less than 0.05 mU/l), were further followed for 1 year or more. Eight patients in group A (22%) and 7 patients in group B (14%) relapsed. Eleven patients in group A (30%) and 5 patients in group B (10%) had fluctuating patterns of free T4 in the upper normal to slightly supranormal range indicative of subclinical hyperthyroidism. The remaining patients continued to have undetectable TSH levels or restored normal TSH levels and normal thyroid hormone concentrations in sera. The results of the present study indicate that the occurrence of undetectable serum TSH concentrations in Graves' disease patients previously treated with methimazole or surgery are not necessarily predictive of clinical relapse because the eventual outcome is variable.     

Plasma L-cystine/L-glutamate imbalance increases tumor necrosis factor-alpha from CD14+ circulating monocytes in patients with advanced cirrhosis

Background and Aims

The innate immune cells can not normally respond to the pathogen in patients with decompensated cirrhosis. Previous studies reported that antigen-presenting cells take up L-Cystine (L-Cys) and secrete substantial amounts of L-Glutamate (L-Glu) via the transport system Xc- (4F2hc+xCT), and that this exchange influences the immune responses. The aim of this study is to investigate the influence of the plasma L-Cys/L-Glu imbalance observed in patients with advanced cirrhosis on the function of circulating monocytes.

Methods

We used a serum-free culture medium consistent with the average concentrations of plasma amino acids from patients with advanced cirrhosis (ACM), and examined the function of CD14+ monocytes or THP-1 under ACM that contained 0–300 nmol/mL L-Cys with LPS. In patients with advanced cirrhosis, we actually determined the TNF-alpha and xCT mRNA of monocytes, and evaluated the correlation between the plasma L-Cys/L-Glu ratio and TNF-alpha.

Results

The addition of L-Cys significantly increased the production of TNF alpha from monocytes under ACM. Monocytes with LPS and THP-1 expressed xCT and a high level of extracellular L-Cys enhanced L-Cys/L-Glu antiport, and the intracellular GSH/GSSG ratio was decreased. The L-Cys transport was inhibited by excess L-Glu. In patients with advanced cirrhosis (n = 19), the TNF-alpha and xCT mRNA of monocytes were increased according to the Child-Pugh grade. The TNF-alpha mRNA of monocytes was significantly higher in the high L-Cys/L-Glu ratio group than in the low ratio group, and the plasma TNF-alpha was significantly correlated with the L-Cys/L-Glu ratio.

Conclusions

A plasma L-Cys/L-Glu imbalance, which appears in patients with advanced cirrhosis, increased the TNF-alpha from circulating monocytes via increasing the intracellular oxidative stress. These results may reflect the immune abnormality that appears in patients with decompensated cirrhosis.