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Follicular lymphoma (FL) is the most common subtype of indolent non-Hodgkin lymphoma. Patients with stage I disease are usually treated with radiotherapy (RT). In previous studies, mostly from the pre positron emission tomography-computed tomography (PET-CT) era, the 5 year progression-free survival (PFS) and overall survival (OS) rates of stage I disease were 60-80% and 80-93%, respectively. This study retrospectively evaluated the outcome of stage I FL which was treated with involved field RT in the PET-CT era between 2002 and 2015. Ninety-one patients were enrolled. Five year PFS and OS rates were 73% and 97%, respectively. Relapse occurred in 19 (21%) patients, 74% occurring outside the radiation field. In conclusion, PET-CT staging of clinical stage I FL may contribute to the improved prognosis in patients treated with RT compared to historical cohorts, possibly due to better identification of “genuine” stage I disease. [ABSTRACT FROM AUTHOR]

Dimethyl sulfoxide (DMSO) is a solvent that is commonly used in medicine. Conflicting data exist as to its effects on endothelial function. Endothelial cell dysfunction (ECD) is characterized by decreased endothelial nitric oxide synthase (eNOS) activity. Cationic amino acid transporter-1 (CAT-1), the specific arginine transporter for eNOS, has been shown to modulate eNOS activity. We hypothesize that DMSO inhibits eNOS activity through modulation of its selective arginine supplier CAT-1. We studied the effect of DMSO on arginine transport, NO 2 /NO 3 generation as an index of NO production, as well as CAT-1 and Protein Kinase C alpha (PKC-α) (CAT-1 inhibitor) protein expression in human umbilical vein endothelial cell cultures (HUVECs). DMSO 2.5% and 3.5% (v/v) significantly attenuated arginine transport, a phenomenon which was prevented by co-incubation with l -arginine (1 mM). The aforementioned findings were accompanied by a decrease in NO 2 /NO 3 generation. DMSO significantly increased the abundance of phosphorylated CAT-1 (the inactive form) and phosphorylated PKC-α protein, an effect that was attenuated by l -arginine. GO 6976 (PKC-α antagonist) prevented the decrease in arginine transport caused by DMSO. DMSO also induced profound transient morphological changes in HUVECs' structure but these were not related to its effect on arginine transport. In conclusion, DMSO inhibits NO generation by endothelial cells through modulation of CAT-1 activity. [ABSTRACT FROM AUTHOR]

Decreased generation of nitric oxide (NO) by endothelial NO synthase (eNOS) characterizes endothelial dysfunction (ECD). Delivery of arginine to eNOS by cationic amino acid transporter-1 (CAT-1) was shown to modulate eNOS activity. We found in female rats, but not in males, that CAT-1 activity is preserved with age and in chronic renal failure, two experimental models of ECD. In contrast, during pregnancy CAT-1 is inhibited. We hypothesize that female sex hormones regulate arginine transport. Arginine uptake in human umbilical vein endothelial cells (HUVEC) was determined following incubation with either 17β- estradiol (E2) or progesterone. Exposure to E2) (50 and 100 nM) for 30 min resulted in a significant increase in arginine transport and reduction in phosphorylated CAT-1 (the inactive form) protein content. This was coupled with a decrease in phosphorylated MAPK/extracellular signal-regulated kinase (ERK) 1/2. Progesterone (1 and 100 pM for 30 min) attenuated arginine uptake and increased phosphorylated CAT-1, phosphorylated protein kinase Cα (PKCα), and phosphorylated ERK1/2 protein content. GO-6976 (PKCα inhibitor) prevented the progesterone-induced decrease in arginine transport. Coincubation with both progesterone and estrogen for 30 min resulted in attenuated arginine transport. While estradiol increases arginine transport and CAT-1 activity through modulation of constitutive signaling transduction pathways involving ERK, progesterone inhibits arginine transport and CAT-1 via both PKCα and ERK1/2 phosphorylation, an effect that predominates over estradiol. [ABSTRACT FROM AUTHOR]