Transport system x c À is a member of plasma membrane heterodimeric amino-acid transporters and consists of two protein components, xCT and 4F2hc. This system mediates cystine entry coupled with the exodus of intracellular glutamate and regulates the intracellular glutathione (GSH) levels in most mammalian cultured cells. We studied the activity of system x c À and GSH content in human ovarian cancer cell line (A2780) and its cisplatin (CDDP)-resistant variant (A2780DDP). The rate of cystine uptake was approximately 4.5-fold higher in A2780DDP cells than in A2780 cells and the cystine uptake in A2780DDP cells was mediated by system x c À . Intracellular GSH content was much higher in A2780DDP cells but it fell drastically in the presence of excess glutamate, which inhibited the cystine uptake competitively. xCT and 4F2hc mRNAs were definitely expressed in A2780DDP cells, but far less in A2780 cells. Expression of system x c À activity by transfection with cDNAs for xCT and 4F2hc made A2780 cells more resistant to CDDP. Similar results on the cystine uptake were obtained in human colonic cancer cell lines. These findings suggest that the system x c À plays an important role in maintaining the higher levels of GSH and consequently in CDDP resistance in cancer cell lines.
We determined the distribution frequency of angiotensin-converting enzyme insertion/deletion (I/D) polymorphism in 111 Japanese patients with non-insulin-dependent diabetes mellitus (NIDDM) of at least 10 years duration (80 patients with diabetic nephropathy and 31 patients without nephropathy) and 76 healthy Japanese controls. Patients with diabetic nephropathy showed an excess of the ID genotype compared with patients without nephropathy (p < 0.02) and less of the II genotype compared with healthy controls (p < 0.01) and patients without nephropathy (p < 0.01). NIDDM patients with the 77 genotype have a decreased risk for the development of diabetic nephropathy.
Lemierre syndrome is characterized by anaerobic bacterial infection in the head and neck, causing thrombophlebitis of the jugular vein and septic metastasis to various distant organs, most often the lungs. Here we describe previously unreported clinical features of cerebral infarctions and brain abscess due to metastatic septic embolism of this uncommon but lethal syndrome, and the successful course of treatment with ampicillin, cefotaxime and metronidazole.
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