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Öğe Cerebral Venous Sinus Thrombosis as a Rare Complication of Systemic Lupus Erythematosus: Subgroup Analysis of the VENOST Study(Elsevier, 2019) Duman, Taşkın; Demirci, Seden; Uludüz, Derya; Kozak, Hasan Hüseyin; Demir, Serkan; Mısırlı, Cemile Handan; Göksan, BakiAim: Systemic lupus erythematosus (SLE) is an unusual risk factor for cerebral venous sinus thrombosis (CVST). As few CVST patients with SLE have been reported, little is known regarding its frequency as an underlying etiology, clinical characteristics, or long-term outcome. We evaluated a large cohort of CVST patients with SLE in a multicenter study of cerebral venous thrombosis, the VENOST study, and their clinical characteristics. Material and Method: Among the 1144 CVST patients in the VENOST cohort, patients diagnosed with SLE were studied. Their demographic and clinical characteristics, etiological risk factors, venous involvement status, and outcomes were recorded. Results: In total, 15 (1.31%) of 1144 CVST patients had SLE. The mean age of these patients was 39.9 +/- 12.1 years and 13 (86.7%) were female. Presenting symptoms included headache (73.3%), visual field defects (40.0%), and altered consciousness (26.7%). The main sinuses involved were the transverse (60.0%), sagittal (40.0%), and sigmoid (20.0%) sinuses. Parenchymal involvement was not seen in 73.3% of the patients. On the modified Rankin scale, 92.9% of the patients scored 0-1 at the 1-month follow-up and 90.9% scored 0-1 at the 1-year follow-up. Conclusions: SLE was found in 1.31% of the CVST patients, most frequently in young women. Headache was the most common symptom and the CVST onset was chronic in the majority of cases. The patient outcomes were favorable. CVST should be suspected in SLE patients, even in those with isolated chronic headache symptoms with or without other neurological findings.Öğe THE EFFECT OF OXALIC ACID PRETREATMENT ON ALKALI PULPING PROCESS(Slovak Forest Products Research Inst, 2016) Üner, Birol; Akgül, Mehmet; Gücüş, Mehmet Onurhan; Demir, SerkanThe objective of this study was to determine prehydrolysis process on kraft and soda pulping process. Optimum cooking conditions were determined by different alkali concentration and cooking period. Oxalicacid was used to hydrolyzechip before cooking. Prehydrolysis proces increased the yield and viscosity of pulp. Incontrast, mechanical properties of paper were not changed significantly. Optical properties were decreased due to lignin content.Öğe Headache as the sole presenting symptom of cerebral venous sinuses thrombosis: Subgroup analysis of data from the VENOST study(2021) Duman, Taşkın; Çınar, Nilgün; Uludüz, Derya; Domaç, Füsun Mayda; Öztürk, Şerefnur; Yayla, Vildan; Demir, SerkanObjectives: Headache is the most common complaint in cerebral venous sinus thrombosis (CVST) and it may sometimes bethe only symptom in these patients. This retrospective and prospective study was an investigation of any differences in termsof clinical risk factors, radiological findings, or prognosis in patients with CVST who presented with isolated headache (IH) andcases with other concomitant findings (non-isolated headache [NIH]).Methods: A total of 1144 patients from a multicenter study of cerebral venous sinus thrombosis (VENOST study) were enrolled inthis research. The demographic, biochemical, clinical, and radiological aspects of 287 IH cases and 857 NIH cases were compared.Results: There were twice as many women as men in the study group. In the IH group, when gender distribution was evaluated byage group, no statistically significant difference was found. The onset of headache was frequently subacute and chronic in the IHgroup, but an acute onset was more common in the NIH group. Other neurological findings were observed in 29% of the IH groupduring follow-up. A previous history of deep, cerebral, or other venous thromboembolism was less common in the IH group thanin the NIH group. Transverse sinus involvement was greater in the IH group, whereas sagittal sinus involvement was greater in theNIH group. The presence of a plasminogen activator inhibitor (PAI) mutation was significantly greater in the IH group.Conclusion: IH and CVST should be kept in mind if a patient has subacute or chronic headache. PAI, which has an importantrole in thrombolytic events, may be a risk factor in CVST. Detailed hematological investigations should be considered. Additional studies are needed.Öğe Melez kavak odunundan (Populus euroamericana) kağıt hamuru üretiminde ön muamele işlemlerinin soda ve modifikasyonları üzerine etkilerinin incelenmesi(Düzce Üniversitesi, 2014) Demir, Serkan; Akgül, MehmetBu çalışmada, Melez kavak (Populus Euramericana) yongalarından soda ve modifiyeleri ile kağıt hamuru üretilmiştir. Modifiye kimyasalları olarak antrakinon (AQ) ve polisülfür (PS) kullanılmıştır. Ön hidroliz yapılacak en uygun pişirmeyi belirlemek amacı ile toplam 6 adet pişirme gerçekleştirilmiştir. Ön hidroliz için, oksalik asit (OA), etil alkol (EA), sodyum borhidrür kimyasalları ile ksilanaz ve lakkaz enzimleri kullanılmıştır. Modifiye, ön hidroliz kimyasalları ve enzimlerin üretilen hamur ve kâğıtların kimyasal, fiziksel ve optik özellikleri üzerine etkisi incelenmiştir. 5/1 sabit çözelti/yonga oranında yapılan kağıt hamuru pişirmeleri, laboratuvar tipi döner kazanda, eşit ortam ve proses suyu sıcaklığı şartlarında gerçekleştirilmiştir. Her pişirmenin hamuru ayrı bir polietilen torbaya konulup hamurun rutubeti TAPPI T 264 om-88 standart yöntemine göre belirlenmiş ve elenmiş hamur verimleri tayin edilmiştir. Ön hidroliz için kullanılacak optimum pişirmeyi belirlemek amacı ile toplam 6 adet pişirme yapılmıştır. Pişirmeler sonucunda elde edilen hamurların elenmiş verim, kappa numarası, viskozite değerleri dikkate alınarak 4 nolu pişirme (%20 NaOH, 170ºC, 120 dak.) kılavuz pişirme olarak seçilmiştir. Bu pişirme koşullarına %0.1 Antrakinon (AQ) %4 Polisülfür (PS) ilave edilmiş ve 2 adet daha pişirme yapılmıştır. Bu şartlarda maksimum hamur verimi elde edilmiştir. Elde edilen hamur verimi KS4 için 48,78, KS7 50,36 ve KS8 50,14'tür. Bu hamurların DP'leri ise sırası ile 1175, 936 ve 957 olarak belirlenmiştir. Soda, soda antrakinon, soda polisulfur hamurlarına ön işlemlerin eklenmesi ile lignin oranının düştüğü ya da aynı kalmasına rağmen DP de artma gözlenmiştir. Uygulanan ön işlemlerin fiziksel ve mekanik özellikleri iyileştirdiği tespit edilmiştir. Oksalik asit ve etanol ile yapılan ön muameleli hamurların toplam veriminde değişiklik olmamasına rağmen, viskoziteleri yükselmiştir. Ksilanaz ve lakkaz enzimiyle yapılan işlemlerde bu durum daha da belirginleşmiştir. Üretilen hamurların özellikleri, geleneksel pişirmelere göre oldukça farklı, daha yüksek verime sahiptir