Cell cycle-dependent regulation of the bi-directional overlapping promoter of human BRCA2/ZAR2 genes in breast cancer cells

<p>Abstract</p> <p>Background</p> <p>BRCA2 gene expression is tightly regulated during the cell cycle in human breast cells. The expression of BRCA2 gene is silenced at the G0/G1 phase of cell growth and is de-silenced at the S/G2 phase. While studying the activity of BRCA2 gene promoter in breast cancer cells, we discovered that this promoter has bi-directional activity and the product of the reverse activity (a ZAR1-like protein, we named ZAR2) silences the forward promoter at the G0/G1 phase of the cell. Standard techniques like cell synchronization by serum starvation, flow cytometry, N-terminal or C-terminal FLAG epitope-tagged protein expression, immunofluorescence confocal microscopy, dual luciferase assay for promoter evaluation, and chromatin immunoprecipitation assay were employed during this study.</p> <p>Results</p> <p>Human <it>BRCA2 </it>gene promoter is active in both the forward and the reverse orientations. This promoter is 8-20 fold more active in the reverse orientation than in the forward orientation when the cells are in the non-dividing stage (G0/G1). When the cells are in the dividing state (S/G₂), the forward activity of the promoter is 5-8 folds higher than the reverse activity. The reverse activity transcribes the ZAR2 mRNA with 966 nt coding sequence which codes for a 321 amino acid protein. ZAR2 has two C4 type zinc fingers at the carboxyl terminus. In the G0/G1 growth phase ZAR2 is predominantly located inside the nucleus of the breast cells, binds to the BRCA2 promoter and inhibits the expression of BRCA2. In the dividing cells, ZAR2 is trapped in the cytoplasm.</p> <p>Conclusions</p> <p><it>BRCA2 </it>gene promoter has bi-directional activity, expressing BRCA2 and a novel C4-type zinc finger containing transcription factor ZAR2. Subcellular location of ZAR2 and its expression from the reverse promoter of the BRCA2 gene are stringently regulated in a cell cycle dependent manner. ZAR2 binds to BRCA2/ZAR2 bi-directional promoter <it>in vivo </it>and is responsible, at least in part, for the silencing of BRCA2 gene expression in the G0/G1 phase in human breast cells.</p

Management of cardiac tamponade during catheter-directed thrombolysis of saddle pulmonary embolism: A clinical dilemma

Catheter-directed thrombolysis (CDT) for the treatment of acute pulmonary embolism (PE) has gained popularity in recent years, but potential complications during the procedure and their management are not frequently discussed in the literature. In this case report, we describe the clinical dilemma regarding the postoperative anticoagulation management of a 60-year-old male who developed cardiac perforation during a CDT of an acute saddle PE. Early resumption of systemic heparin in such cases may help in clot resolution; however, it can worsen the hemopericardium. On the other hand, delaying restarting heparin may help in healing of the cardiac perforation but can lead to clot propagation. As the chest tube output was minimal initially, anticoagulation was started, which, however, led to disastrous outcome. With limited published medical literature to help guide such a complex situation, it may be prudent to carefully weigh the risks and benefits of resuming systemic heparin versus delaying it for 1–2 days to allow for definitive resolution of the cardiac perforation

Safety and efficacy of a modified HeRO dialysis device in achieving early graft cannulation: A single-institution experience

Hemodialysis Reliable Outflow (HeRO) grafts (Merit Medical Systems, Inc, South Jordan, Utah) provide a means for access in catheter-dependent hemodialysis patients but typically require several weeks for tissue incorporation. Modifying the HeRO graft with an ACUSEAL graft (W. L. Gore & Associates, Newark, Del) can allow immediate cannulation, thus reducing catheter dependence time and its associated complications. A retrospective review of patients at our institution from 2013 to 2016 who underwent placement of a modified HeRO dialysis system with ACUSEAL graft was performed. Complications and outcomes were analyzed, with patency rates and hours to successful cannulation being major end points. Modified HeRO grafts were successfully placed in 10 catheter-dependent patients. Postoperative complications included two thromboses and one hematoma. At 6 months of follow-up, mean time to graft cannulation was 33.7 hours, with 100% success; the primary and secondary patency rates were 70% and 90%, respectively. Our modification allows an accelerated use of the HeRO system, reducing catheter dependence time with acceptable postoperative complications and patency rates

Incidental finding of tracheal bronchus complicating the anesthetic management of a left video-assisted thoracoscopic procedure

Congenital abnormalities of the large airways are uncommon, but may occasionally pose significant difficulties for anesthesiologists. The tracheal bronchus is an anatomical variant in which an accessory bronchus originates directly from the trachea rather than distal to the carina, as a takeoff from the right mainstem bronchus. Anesthesiologists should be aware of this uncommon anomaly, its different variants, and its management in order to successfully establish one lung ventilation (OLV) for surgical isolation. In this article, we report the challenges encountered in establishing OLV in a patient with a previously undiagnosed aberrant right upper lobe bronchus arising directly from the trachea

Inhaled Carbon Monoxide Attenuates Myocardial Inflammatory Cytokine Expression in a Rat Model of Cardiopulmonary Bypass

Carbon monoxide (CO), a by-product of Heme metabolism, is a potent modulator of inflammation. Low dose inhaled CO has demonstrated reduced lung and kidney injury in animal models of cardiopulmonary bypass (CPB). We evaluated the impact of low dose inhaled CO on systemic, pulmonary, and myocardial inflammatory response to CPB in rats. Sixteen male Sprague-Dawley rats underwent CPB for 1 hour. The CO (n = 8) group received inhaled CO at 250 ppm for 3 hours before CPB. The Air (n = 8) group served as the control. Pulmonary mechanics were assessed pre and post CPB. The animals were recovered for 30 minutes post CPB and subsequently sacrificed. Pre CPB and post CPB serum Tumor Necrosis Factor-alpha (TNF-α) and Interleukin-10 (IL-10) were analyzed by enzyme-linked immunosorbent assay. Gene expression array and real time quantitative polymerase chain reaction (PCR) analysis was performed on the extracted heart tissue. Baseline characteristics were similar between the groups with the expected exception of carboxyhemoglobin levels (p ≤.001) and oxyhemoglobin saturation (p ≤.01) in Air versus CO treated groups, respectively. Serum TNF-α (363 ± 278 vs. 287 ± 195; p = .13) and IL-10 (237 ± 26 vs. 302 ± 137; p = Not Significant) in Air versus CO groups respectively were not statistically different after CPB, despite showing a trend of inflammatory attenuation. Gene expression array of the myocardial tissue suggested a pattern of inflammatory modulation, which was confirmed by real time quantitative PCR demonstrating IL-10 expression 3.13 times higher (p = .02) in the CO treated group com pared to the Air group. These data demonstrate that pretreatment with CO at 250 ppm may have a modulatory effect on the inflammatory response to CPB without compromising hemodynamics or oxygen delivery. Further investigation in a survival model of CPB is warranted