SINGLET OXYGEN RESISTANT 1 links reactive electrophile signaling to singlet oxygen acclimation in Chlamydomonas reinhardtii.

Acclimation of Chlamydomonas reinhardtii cells to low levels of singlet oxygen, produced either by photoreactive chemicals or high light treatment, induces a specific genetic response that strongly increases the tolerance of the algae to subsequent exposure to normally lethal singlet oxygen-producing conditions. The genetic response includes the increased expression of various oxidative stress response and detoxification genes, like the glutathione peroxidase homologous gene GPXH/GPX5 and the σ-class glutathione-S-transferase gene GSTS1. To identify components involved in the signal transduction and activation of the singlet oxygen-mediated response, a mutant selection was performed. This selection led to the isolation of the singlet oxygen resistant 1 (sor1) mutant, which is more tolerant to singlet oxygen-producing chemicals and shows a constitutively higher expression of GPXH and GSTS1. Map-based cloning revealed that the SOR1 gene encodes a basic leucine zipper transcription factor, which controls its own expression and the expression of a large number of oxidative stress response and detoxification genes. In the promoter region of many of these genes, a highly conserved 8-bp palindromic sequence element was found to be enriched. This element was essential for GSTS1 induction by increased levels of lipophilic reactive electrophile species (RES), suggesting that it functions as an electrophile response element (ERE). Furthermore, GSTS1 overexpression in sor1 requires the ERE, although it is unknown whether it occurs through direct binding of SOR1 to the ERE. RES can be formed after singlet oxygen-induced lipid peroxidation, indicating that RES-stimulated and SOR1-mediated responses of detoxification genes are part of the singlet oxygen-induced acclimation process in C. reinhardtii.

Compliance with surgical follow-up does not influence fistula maturation in a county hospital population.

BACKGROUND: The purpose of this study is to examine follow-up rates and maturation rates after dialysis access surgery using a fistula-first approach in a county hospital with an indigent population. METHODS: A prospectively maintained dialysis access database was queried for cases performed between August 1, 2009 and September 30, 2011. The follow-up period ended on December 31, 2011. An attempt was made to contact patients who did not have complete follow-up data recorded to the point of fistula maturation for arteriovenous fistulas (AVF). Patients were contacted directly or through their dialysis center. Maturation was defined by successful use of the AVF for hemodialysis for at least 2 weeks for patients who are dialysis dependent or by the clinical assessment of an attending vascular surgeon for those not on dialysis. RESULTS: Two hundred three dialysis access cases were performed. The mean age was 51.4 years. One hundred twenty-six (62%) were male and 175 (86%) were Hispanic. Of these, 194 (95.6%) were AVF. Three AVF were ligated in the postoperative period for steal. Of the remaining 191 AVF, 94 (49%) patients completed their scheduled follow-up appointments. Sixty-six (35%) patients did not come to clinic but were contacted. Twenty-six (14%) patients were completely lost to follow-up and 5 (2.6%) died. Maturation data was obtained on 160 AVF. Of those, 123 (77%) reached maturation with a mean maturation time of 112 ± 99 days (range, 21-483). Twenty patients who completed follow-up underwent at least 1 additional surgical or endovascular procedure in an attempt to achieve maturation. Seventeen (85%) patients who underwent a secondary procedure went on to achieve maturation. There was no significant difference in maturation between the group that completed follow-up and those who were contacted by phone (69 [73%] vs. 54 [81%], P = not significant). CONCLUSIONS: In this indigent population, follow-up does not influence maturation rates of AVF. Despite poor compliance with follow-up in the setting of a public hospital, the maturation rate of an aggressive fistula-first approach is acceptable.

Stereotactic endovascular aortic navigation with a novel ultrasonic-based three-dimensional localization system.

BACKGROUND: Endovascular aortic procedures have been developed to treat many aortic diseases effectively. However, these procedures are also becoming increasingly complex given the development of branched or fenestrated endografts. Part of the difficulty lies in the limitations of current imaging paradigms. A more intuitive, three-dimensional (3D) mode of intraoperative imaging is desirable to accommodate the future progression of endovascular techniques. This article describes a novel endovascular catheter tracking device that uses ultrasonic signals, not ultrasound imaging. The tracking device displays real-time in vivo location on previously acquired 3D computed tomography (CT) images in an intuitive, endoluminal view. This system was tested in two swine and validated against fluoroscopy and by delivering stent grafts. METHODS: The ultrasonic-based localization system (ULS) provides real-time location information of a modified endovascular catheter and displays this location on preoperative 3D CT images. The 9F endovascular catheter has a small ultrasonic transmitter attached to its tip to signal its location to the ULS. Subsequent endovascular deployment of an aortic stent was carried out using only the ULS to target the stent placement position in the aorta of Yorkshire swine. System accuracy was measured against concurrent angiography as well as to deployed stents in situ. RESULTS: We successfully displayed the endovascular catheter tip location in real time along the registered CT aortic images, providing virtual endoluminal tracking. The relative accuracy of the ULS as compared with angiography for catheter movements in the abdominal aorta was found to have a mean error less than 1 mm. The ULS coordinates tracked within the lumen of the aortic image 98% of the time, as defined by the proportion of points within one radius distance of the aortic image centerline. Finally, three aortic stents were deployed using the ULS virtual image display to locate the target position in the aorta for stent deployment. Errors between target position and actual stent position ranged from -5.0 to +7.9 mm. CONCLUSIONS: This study demonstrates the feasibility of virtual image-guided endovascular aortic navigation using a ULS. This provides a 3D platform for virtual navigation on preoperative CT scan images during endovascular procedures that could assist in stent deployment as well as minimize or eliminate the need for procedural ionizing radiation and iodinated contrast. Future work will focus on miniaturization and refinements in accuracy that will be required to translate this technology into clinical application in endovascular procedures.