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result(s) for
"Oztas, Onur"
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Genome-wide excision repair in Arabidopsis is coupled to transcription and reflects circadian gene expression patterns
2018
Plants are exposed to numerous DNA-damaging stresses including the exposure to ultraviolet (UV) component of solar radiation. They employ nucleotide excision repair to remove DNA-bulky adducts and to help eliminate UV-induced DNA lesions, so as to maintain their genome integrity and their fitness. Here, we generated genome-wide single-nucleotide resolution excision repair maps of UV-induced DNA damage in
Arabidopsis
at different circadian time points. Our data show that the repair of UV lesions for a large fraction of the genome is controlled by the joint actions of the circadian clock and transcription by RNA polymerase II. Our findings reveal very strong repair preference for the transcribed strands of active genes in
Arabidopsis
, and 10–30% of the transcription-coupled repair is circadian time-dependent. This dynamic range in nucleotide excision repair levels throughout the day enables
Arabidopsis
to cope with the bulky DNA lesion-inducing environmental factors including UV.
Plants use nucleotide excision repair to maintain genome integrity in response to damage caused by stresses such as UV radiation. Here Oztas et al. use genome-wide profiling to show that excision repair in
Arabidopsis
is strongly coupled to transcription and reflects circadian patterns of gene expression.
Journal Article
Global repair is the primary nucleotide excision repair subpathway for the removal of pyrimidine-pyrimidone (6-4) damage from the Arabidopsis genome
2024
Ultraviolet (UV) component of solar radiation impairs genome stability by inducing the formation of pyrimidine-pyrimidone (6-4) photoproducts [(6-4)PPs] in plant genomes. (6-4)PPs disrupt growth and development by interfering with transcription and DNA replication. To resist UV stress, plants employ both photoreactivation and nucleotide excision repair that excises oligonucleotide containing (6-4)PPs through two subpathways: global and transcription-coupled excision repair (TCR). Here, we analyzed the genome-wide excision repair-mediated repair of (6-4)PPs in
Arabidopsis thaliana
and found that (6-4)PPs can be repaired by TCR; however, the main subpathway to remove (6-4)PPs from the genome is global repair. Our analysis showed that open chromatin genome regions are more rapidly repaired than heterochromatin regions, and the repair level peaks at the promoter, transcription start site and transcription end site of genes. Our study revealed that the repair of (6-4)PP in plants showed a distinct genome-wide repair profile compared to the repair of other major UV-induced DNA lesion called cyclobutane pyrimidine dimers (CPDs).
Journal Article
A symbiotic SNARE protein generated by alternative termination of transcription
2016
Many microbes interact with their hosts across a membrane interface, which is often distinct from existing membranes. Understanding how this interface acquires its identity has significant implications. In the symbiosis between legumes and rhizobia, the symbiosome encases the intracellular bacteria and receives host secretory proteins important for bacterial development. We show that the
Medicago truncatula SYNTAXIN 132
(
SYP132
) gene undergoes alternative cleavage and polyadenylation during transcription, giving rise to two target-membrane soluble NSF attachment protein receptor (t-SNARE) isoforms. One of these isoforms, SYP132A, is induced during the symbiosis, is able to localize to the peribacteroid membrane, and is required for the maturation of symbiosomes into functional forms. The second isoform, SYP132C, has important functions unrelated to symbiosis. The SYP132A sequence is broadly found in flowering plants that form arbuscular mycorrhizal symbiosis, an ancestral mutualism between soil fungi and most land plants.
SYP132A
silencing severely inhibited arbuscule colonization, indicating that SYP132A is an ancient factor specifying plant–microbe interfaces.
Specific tissues are developed by legumes during symbiosis to host soil bacteria that will fix nitrogen from air. One single t-SNARE gene in
Medicago
can switch from a housekeeping to a symbiosome-specific function by alternative transcription.
Journal Article
Genome-wide mapping of nucleotide excision repair with XR-seq
2019
Nucleotide excision repair is a conserved pathway to resolve bulky DNA adducts caused by different mutagens. XR-seq generates genome-wide repair maps of DNA damage across a range of organisms.
Journal Article
Evaluation of chronic inflammation in the aetiology of venous insufficiency by investigating cytomegalovirus DNA
by
Ulukan, Mustafa Ozer
,
Beyaz, Metin O.
,
Coskun, Ugur
in
Body mass index
,
chronic inflammation
,
Clinical Research
2022
Lower extremity venous insufficiency is a significant health problem with economic and sociological consequences, lowering the quality of life, and sometimes leading to serious complications. The aim of this study is to evaluate the cytomegalovirus (CMV) effect on chronic inflammation in the aetiology of chronic venous insufficiency.
Between November 2017 and August 2018, 468 patients who underwent radio-frequency ablation therapy and phlebectomy were included in the study. PCR analyses for CMV DNA were performed on the venous tissue samples. Patients with post-thrombotic syndrome were excluded from the study. After ethical approval, the relationship between the presence of CMV DNA, gender, body mass index, and bilaterality of chronic venous insufficiency were investigated.
When the relationship between CMV DNA and gender or body mass index was examined, a significant relationship was not detected. But when the patients with bilateral chronic venous insufficiency and patients with unilateral chronic venous insufficiency were compared regarding CMV DNA positivity, the patients with bilateral chronic venous insufficiency had significantly higher CMV DNA positivity (
= 0.002). Also, the incidence of venous ulcers in the CMV DNA exposed group was significantly higher.
In the literature there are many studies showing that CMV triggers atherosclerosis, but there is no study in which CMV directly produces chronic venous insufficiency. The high rates of positivity suggest that CMV, which is the basis of chronic inflammation, may be a significant factor in the aetiology of chronic venous insufficiency.
Journal Article
The geometrical modeling of aortic root complex
by
Oztas, Didem
,
Bozbuga, Nilgun
,
Sahinoglu, Kayihan
in
Aortic root
,
cardiac anatomy
,
Coronary vessels
2019
Background: This study was designed to investigate the anatomical relationship of the different levels of aortic root.
Materials and Methods: The morphological features of the aortic root were examined using of 12 adult hearts from fixed male cadavers who had expired due to noncardiac causes by magnetic resonance imaging and applied mathematical analyses to the results. The measurements of the aortic root were done at four levels: at the ventriculoarterial junction (annulus), at the largest level of the Valsalva sinuses (sinus), at the level of commissures (sinotubular junction [STJ]), and at 1 cm above the STJ (aorta ascendens). We derived an equation that allows calculation of the appropriate diameter of the aortic root from four levels. Statistical analysis among the variation of the diameters at the four levels of aortic root was achieved using test one-way analysis of variance.
Results: The data showed a geometric pattern of the aortic root. The comparison of the values from four levels showed that the narrowest at the sinotubular junctional level and the widest at the sinus level.
Conclusion: The analysis of our data shows that the aortic root has a consistent shape with varying size and that is a definable mathematical relationship between root diameter.
Journal Article
Follow-up Results of Endovascular Aneurysm Repair Following Abdominal Visceral Debranching
2022
The aim of this study is to present a series of six cases with thoracoabdominal aneurysm treated with hybrid technique in our center.
Between May 2015 and December 2018, the data of six patients with thoracoabdominal aneurysms and various comorbidities who underwent visceral debranching followed by endovascular aortic aneurysm repair were reviewed retrospectively.
Patients' mean age was 65.3±19.6 years. All of them were male. Comorbidities were old age, congestive heart failure, coronary artery disease, chronic obstructive pulmonary disease, previous surgical interventions, and/or esophageal hemangioma. Except for one patient who underwent coronary artery bypass grafting (inflow was taken from ascending aorta), debranching was performed from the right iliac artery. Debranching of four visceral arteries (superior mesenteric artery, celiac trunk, and bilateral renal right arteries) was performed in three patients, of three visceral arteries (superior mesenteric artery, celiac trunk, right renal artery) was performed in one, and of two visceral arteries (superior mesenteric artery, celiac trunk) was performed in two patients. Great saphenous vein and 6-mm polytetrafluoroethylene grafts were used in one and five patients, respectively, for debranching. Endovascular aneurysm repair was performed following debranching procedures as soon as the patients were stabilized. In total, three patients died at the early, mid, and long-term follow-up due to multiorgan failure, pneumonia, and unknown reasons.
Hybrid repair of thoracoabdominal aneurysms may be an alternative to fenestrated or branched endovascular stent grafts in patients with increased risk factors for open surgical thoracoabdominal aneurysm repair; however, the procedure requires experience and care.
Journal Article
Preoperative Arterial and Venous Cannulation in Redo Cardiac Surgery: From the Safety and Cost-effectiveness Points of View
by
Ulukan, Mustafa Ozer
,
Erkanli, Korhan
,
Unal, Orcun
in
Adult
,
Blood products
,
CARDIAC & CARDIOVASCULAR SYSTEMS
2020
To investigate the safety and cost-effectiveness of preoperative cannulation and conventional approach techniques.
Sixty-one patients who underwent redo open cardiac procedures between September 2015 and November 2018 were divided into two groups - Group A (n: 30), patients who underwent conventional cannulation after sternotomy, and Group B (n: 31), those who underwent cannulation before sternotomy. Patients were evaluated retrospectively for general complication rates and total hospital costs.
Mortality occurred in four patients from Group A and in one patient from Group B. Four patients required extracorporeal membrane oxygenation (ECMO) in Group A, whereas two required ECMO in Group B. Duration of total operation, cardiopulmonary bypass, and cross-clamp times were longer in the conventional surgery group than in the pre-sternotomy cannulation group (420.29±188.84 vs. 314.77±187.38, P=0.036; 171.87±85.59 vs. 141.7±82.47, P=0.089; and 102.94±70.67 vs. 60.97±52.81, P=0.009; respectively). Total blood and blood product usage were higher in Group A than in Group B. Postoperative intensive care unit stay was 62.77±145.3 hours vs. 25.13±73.11 hours, ventilation time was 5.16±5.09 hours vs. 3.03±2.78 hours, duration of ward stay was 5.23±2.52 days vs. 5.57±2.16 days, and duration of hospital stay was 9.58±5.85 days vs. 9.8±5.31 days in conventional sternotomy and pre-sternotomy cannulation groups, respectively. Total hospital costs were calculated 35863.52±20803.99 Turkish Liras (TL) in Group A and 25744.74±16472.03 TL in Group B (P=0,042).
Venous and arterial cannulations before sternotomy decreased myocardial injury and complication rates, blood and blood product usage, hospital stay, and, consequently, hospital costs in our modest cohort.
Journal Article
Congenital cardiac interventions during the peak phase of COVID-19 pandemics in the country in a pandemics hospital in Istanbul
by
Akdeniz, Celal
,
Turkoglu, Halil
,
Karakaya, Atalay
in
Adolescent
,
Algorithms
,
Cardiovascular Surgical Procedures - adverse effects
2020
In this report, we aim to present our algorithm and results of patients with congenital cardiac disorders who underwent surgical or interventional procedures during the peak phase of the pandemics in our country.
The first COVID-19 case was diagnosed in Turkey on 11 March, 2020, and the peak phase seemed to end by the end of April. All the patients whom were referred, treated, or previously operated but still at the hospital during the peak phase of COVID-19 pandemics in the country were included into this retrospective study. Patient's diagnosis, interventions, adverse events, and early post-procedural courses were studied.
Thirty-one patients with various diagnoses of congenital cardiovascular disorders were retrospectively reviewed. Ages of the patients ranged between 2 days and 16 years. Seventeen cases were males and 14 cases were females. Elective cases were postponed. Priority was given to interventional procedures, and five cases were treated percutaneously. Palliative procedures were preferred in patients whom presumably would require long hospital stay. Corrective procedures were not hesitated in prioritised stable patients. Mortality occurred in one patient. Eight patients out of 151 ICU admissions were diagnosed with COVID-19, and they were transferred to COVID-19 ICU immediately. Three nurses whom also took care of the paediatric cases became infected with SARS-CoV-2; however, the children did not catch the disease.
Mandatory and emergent congenital cardiac percutaneous and surgical procedures may be performed with similar postoperative risks as there are no pandemics with meticulous care and preventive measures.
Journal Article
Comparison of the Apoptotic Effects of Topically Applied Papaverine, Diltiazem, and Nitroprusside to Internal Thoracic Artery
by
Bakuy, Vedat
,
Aral, Erinc
,
Ulukan, Mustafa Ozer
in
Apoptosis
,
Biotin
,
CARDIAC & CARDIOVASCULAR SYSTEMS
2020
To detect and to compare the apoptotic effects of intraoperatively topically applied diltiazem, papaverine, and nitroprusside.
Internal thoracic artery segments of ten patients were obtained during coronary bypass grafting surgery. Each internal thoracic artery segment was divided into four pieces and immersed into four different solutions containing separately saline (Group S), diltiazem (Group D), papaverine (Group P), and nitroprusside (Group N). Each segment was examined with both hematoxylin-eosin and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method in order to determine and quantify apoptosis.
Apoptotic cells were counted in 50 microscopic areas of each segment. No significant difference was observed among the four groups according to hematoxylin-eosin staining. However, the TUNEL method revealed a significant increase in mean apoptotic cells in the diltiazem group when compared with the other three groups (Group S=4.25±1.4; Group D=13.31±2.8; Group N=9.48±2.09; Group P=10.75±2.37). The differences between groups were significant (P=0.0001). No difference was observed between the samples of the diabetic and non-diabetic patients in any of the study groups.
The benefit of topically applied vasodilator drugs must outweigh the potential adverse effects. In terms of apoptosis, diltiazem was found to have the most deleterious effects on internal thoracic artery graft segments. Of the analyzed medical agents, nitroprusside was found to have the least apoptotic activity, followed by papaverine. Diabetes did not have significant effect on the occurrence of apoptosis in left internal thoracic artery grafts.
Journal Article