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Dive into the research topics where Çağdaş Kalkan is active.

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Featured researches published by Çağdaş Kalkan.


Platelets | 2014

The predictive value of mean platelet volume, plateletcrit and red cell distribution width in the differentiation of autoimmune gastritis patients with and without type I gastric carcinoid tumors

Ali Tüzün; Onur Keskin; Mustafa Yakut; Çağdaş Kalkan; Irfan Soykan

Abstract Autoimmune gastritis is an autoimmune and inflammatory condition that may predispose to gastric carcinoid tumors or adenocarcinomas. The early diagnosis of these tumors is important in order to decrease morbidity and mortality. Platelet indices such as mean platelet volume and plateletcrit levels increase in inflammatory, infectious and malign conditions. The primary aim of this study was to explore wheter platelet indices and red cell distribution width have any predictive role in the discrimination of autoimmune gastritis patients with and without gastric carcinoid tumors. Also secondary aim of this study was to investigate whether any changes exist betwenn autoimmune gastritis and functional dyspepsia patients by means of platelet indices. Plateletcrit (0.22 ± 0.06 vs. 0.20 ± 0.03%, p < 0.001) and red cell distribution width (16.11 ± 3.04 vs. 13.41 ± 0.95%, p < 0.001) were significantly higher in autoimmune gastritis patients compared to control group. Receiver operating curve analysis suggested that optimum plateletcrit cut-off point was 0.20% (AUC: 0.646), and 13.95% as the cut off value for red cell distribution width (AUC: 0.860). Although plateletcrit (0.22 ± 0.06 vs. 0.21 ± 0.04%, p = 0.220) and mean platelet volume (8.94 ± 1.44 vs. 8.68 ± 0.89 fl, p = 0.265) were higher in autoimmune gastritis patients without carcinoid tumor compared to patients with carcinoid tumors, these parameters were not statistically significant. Changes in plateletcrit and red cell distribution width values may be used as a marker in the discrimination of autoimmune gastritis and fucntional dyspepsia patients but not useful in patients with gastric carcinoid tumor type I.


Hepatology | 2018

Optimizing lonafarnib treatment for the management of chronic delta hepatitis: The LOWR HDV‐1 study

Cihan Yurdaydin; Onur Keskin; Çağdaş Kalkan; Fatih Karakaya; Aysun Çalişkan; Ersin Karatayli; Senem Karatayli; A. Mithat Bozdayi; Christopher Koh; Theo Heller; Ramazan Idilman; Jeffrey S. Glenn

In a proof‐of‐concept (POC) study, the oral prenylation inhibitor, lonafarnib (LNF), decreased hepatitis D virus (HDV) RNA during 4 weeks of treatment. Here, we explored optimal LNF regimens. Fifteen patients (five groups; 3 per group) completed dosing as follows: (1) LNF 200 mg twice‐daily (BID; 12 weeks); (2) LNF 300 mg BID (12 weeks); (3) LNF 100 mg thrice‐daily (5 weeks); (4) LNF 100 mg BID + pegylated interferon alfa (PEG‐IFNα) 180 μg once‐weekly (QW; 8 weeks); and (5) LNF 100 mg BID + ritonavir (RTV) 100 mg once‐daily (QD; 8 weeks). Tolerability and efficacy were assessed. Higher LNF monotherapy doses had greater decreases in HDV viral load than achieved in the original POC study. However, this was associated with increased gastrointestinal adverse events. Addition of RTV 100 mg QD to a LNF 100 mg BID regimen yielded better antiviral responses than LNF 300 mg BID monotherapy and with less side effects. A similar improvement was observed with LNF 100 mg BID + PEG‐IFNα 180 μg QW. Two of 6 patients who received 12 weeks of LNF experienced transient posttreatment alanine aminotransferase (ALT) increases resulting in HDV‐RNA negativity and ALT normalization. Conclusion: The cytochrome P450 3A4 inhibitor, RTV, allows a lower LNF dose to be used while achieving higher levels of postabsorption LNF, yielding better antiviral responses and tolerability. In addition, combining LNF with PEG‐IFNα achieved more substantial and rapid HDV‐RNA reduction, compared to historical responses with PEG‐IFNα alone. Twelve weeks of LNF can result in posttreatment HDV‐RNA negativity in some patients, which we speculate results from restoring favorable immune responses. These results support further development of LNF with RTV boosting and exploration of the combination of LNF with PEG‐IFN. (Hepatology 2018;67:1224‐1236)


Geriatrics & Gerontology International | 2016

Factors related to low serum vitamin B12 levels in elderly patients with non‐atrophic gastritis in contrast to patients with normal vitamin B12 levels

Çağdaş Kalkan; Fatih Karakaya; Ali Tüzün; Zeynep Bıyıklı Gençtürk; Irfan Soykan

Vitamin B12 deficiency is frequent in older patients, and the main reason is pernicious anemia. However, vitamin B12 deficiency can occur in patients who do not have atrophic gastritis. The aim of the present study was to investigate factors affecting serum vitamin B12 levels in older patients with non‐atrophic gastritis.


Clinical Transplantation | 2016

The long-term efficacy of combining nucleos(t)ide analog and low-dose hepatitis B immunoglobulin on post-transplant hepatitis B virus recurrence

Ramazan Idilman; Murat Akyildiz; Onur Keskin; Gökhan Güngör; Tonguc U. Yilmaz; Çağdaş Kalkan; Murat Dayangac; Kubilay Çinar; Deniz Balci; Selcuk Hazinedaroglu; Yaman Tokat

The aim of this study was to determine the long‐term efficacy of nucleos(t)ide analog (NA) and low‐dose hepatitis B immunoglobulin (HBIG) combination treatment for preventing post‐transplant hepatitis B virus (HBV) recurrence.


European Journal of Internal Medicine | 2014

Manometric assessment of esophageal motor function in patients with primary biliary cirrhosis

Mehmet Bektas; Gülseren Seven; Ramazan Idilman; Mustafa Yakut; Beyza Doganay; Gökhan Kabaçam; Yusuf Üstün; Esin Korkut; Çağdaş Kalkan; Günay Sahin; Hülya Çetinkaya; Hakan Bozkaya; Cihan Yurdaydin; Kadir Bahar; Kubilay Çinar; Irfan Soykan

INTRODUCTION/AIM Primary biliary cirrhosis is associated with other autoimmune diseases including Sjögrens syndrome, and scleroderma. Esophageal dysmotility is well known in scleroderma, and Sjögrens syndrome. The aim of this study is to investigate whether any esophageal motor dysfunction exists in patients with primary biliary cirrhosis. METHOD The study was performed in 37 patients (36 women, mean age: 56.29 ± 10.01 years) who met diagnostic criteria for primary biliary cirrhosis. Thirty-seven functional dyspepsia patients, were also included as a control group. Patients entering the study were asked to complete a symptom questionnaire. Distal esophageal contraction amplitude, and lower esophageal sphincter resting pressure were assessed. RESULTS Manometric findings in primary biliary cirrhosis patients vs. controls were as follows: Median lower esophageal sphincter resting pressure (mmHg): (24 vs 20, p=0.033); median esophageal contraction amplitude (mmHg): (71 vs 56, p=0.050); mean lower esophageal sphincter relaxation duration (sc, x ± SD): (6.10 ± 1.18 vs 8.29 ± 1.92, p<0.001); and median lower esophageal sphincter relaxation (%) (96 vs 98, p=0.019); respectively. No significant differences were evident in median peak velocity (sc) (3.20 vs 3.02, p=0.778) between patients with primary biliary cirrhosis and the functional dyspepsia patients. Esophageal dysmotility was found in 17 (45.9%) primary biliary cirrhosis patients (non-specific esophageal motor disorder in ten patients, hypomotility of esophagus in five patients, nutcracker esophagus in one patient and hypertensive lower esophageal sphincter in one patient). CONCLUSION Esophageal dysmotility was detected in 45.9% of patients. The study suggests that subclinic esophageal dysmotility is frequent in patients with primary biliary cirrhosis.


Antiviral Therapy | 2017

Discontinuation of lamivudine treatment in HBeAg-negative chronic hepatitis B: a pilot study with long-term follow-up

Fatih Karakaya; Sevil Özer; Çağdaş Kalkan; E Ali Tüzün; Aysun Çalişkan; Onur Keskin; Gökhan Kabaçam; Senem Karatayli; Ersin Karatayli; A. Mithat Bozdayi; Ramazan Idilman; Cihan Yurdaydin

BACKGROUND Finite treatment of hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) with nucleoside/nucleotide analogues (NAs) is important in resource-limited countries. Outcome of treatment discontinuation in patients on long-term lamivudine (LVD) was assessed in a single centre observational pilot study in the current study. METHODS Non-cirrhotic patients on LVD for at least 5 years with undetectable HBV DNA on at least two consecutive assessments were offered to stop treatment. Biochemical, serological and virological measures were determined at 3-6 month intervals after treatment discontinuation. Serum quantitative hepatitis B surface antigen (HBsAg) was determined at treatment discontinuation and 5-6 years thereafter. NA treatment was re-instituted in patients with confirmed viral rebound defined as HBV DNA >20,000 IU/ml. Relapser patients were no longer followed but were re-assessed 6 years after treatment cessation. RESULTS LVD was discontinued in 23 patients. 8 patients relapsed within 1 year and NA treatment was restarted; 15 patients (65%) were non-relapsers. Thirteen of them were followed for at least 5 years. Two patients had undetectable HBV DNA throughout the follow-up period. In the rest, HBV DNA fluctuated at low levels. Two patients cleared HBsAg 24 and 36 months after stopping treatment. Quantitative HBsAg levels 5-7 years after treatment discontinuation were lower in non-relapser compared to relapser patients (1.21 IU/ml ±0.98 versus 2.71 ±0.76; P=0.002). Of 8 relapser patients 1 patient had HBsAg levels less than 100 IU/ml compared to 11 out of 13 non-relapser patients (P=0.0022). CONCLUSIONS These data suggest that cessation of NA treatment is a viable option after a reasonable treatment duration in patients with HBeAg-negative CHB and that HBsAg clearance may become an achievable target in these patients.


European Journal of Internal Medicine | 2016

Polyautoimmunity in autoimmune gastritis

Çağdaş Kalkan; Irfan Soykan

OBJECTIVES Autoimmune gastritis may be associated with other organ-specific autoimmune disorders, but the prevalence of this association is not entirely quantified. The aims of this study were to investigate the prevalence of autoimmune disorders and evaluate the factors that might affect this association in patients with autoimmune gastritis. METHODS A total of 320 patients with autoimmune gastritis were retrospectively studied and data on concomitant autoimmune diseases, serum gastrin and chromogranin A levels, anti-Hp IgG, antiparietal cell antibodies, presence of enterochromaffin-like cell hyperplasia and gastric atrophy were gathered for each patient and associations between autoimmune gastritis and studied parameters were explored through descriptive statistics and logistic regression analysis. RESULTS Of the 320 atrophic body autoimmune gastritis patients, 171 (53.4%) had an associated autoimmune disorder. Autoimmune thyroiditis was the most common concurrent disease, diagnosed in 116 patients (36.2%). Multivariate analysis showed that, presence of enterochromaffin cell hyperplasia (odds ratio [OR] 9.445, 95% confidence [CI]: 4.42-20.22), serum gastrin (OR 3.1, 95% CI: 1.46-6.60) and serum chromogranin A (OR 4.14, 95% CI: 2.01-8.52) levels remained significantly associated with the coexistence of an autoimmune disease. CONCLUSIONS Concurrent autoimmune diseases are common in patients with autoimmune gastritis. Autoimmune thyroiditis is the most encountered disease. These data suggest that patients with autoimmune gastritis should be investigated for the presence of an autoimmune disease, in particular patients with enterochromaffin cell hyperplasia and those with serum gastrin and chromogranin A levels above cut-off values.


Journal of Gastrointestinal and Digestive System | 2014

The Risk of Ileocolonic Perforation in Patients with Behet's Disease: Report ofThree Cases and Review of the Literature

Mehmet Bektas; Çağdaş Kalkan; Irfan Soykan; Ayşe Boyvat; Berna Savas; Ethem Gecim; Onur Keskin; Ekin Kırcali; Ali Tüzün; Necati Örmeci

Introduction/Purpose: Intestinal Behcet’s disease may cause serious complications. Massive hemorrhage, fistulisation and intestinal perforation are encountered complications in approximately 50% of patients suffering from intestinal Behcet’s disease. Currently, there is not enough data inquiring iatrogenic ileocolonic perforation during colonoscopy in patients with intestinal Behcet’s disease; therefore we aimed to study intestinal Behcet’s disease patients who suffered perforation during or after colonoscopy. Methods: A total of 2615 colonoscopic examinations were performed between May 2002 and December 2007. Of these 2615 patients, main indication for colonoscopy was intestinal Behcet’s disease in 135 patients. Results: In total 135 patients with Behcet’s patients were assessed with colonoscopy due to presumed ileocolonic involvement. 8 out of 135 (5.9%) patients had ileal and colonic ulcers. 3 patients (2.22%) had iatrogenic perforation, 2 of whom had profound ulcers in proximal colon and ileum. The third case had ulcers in sigmoid colon, descending and transverse colon segments. All these 3 patients had undergone surgical intervention including ileal resection and right hemicolectomy. Discussion: Colonoscopic examination is commonly used in Behcet’s disease not only for diagnostic purposes but also for surveillance of intestinal involvement in Behcet’s disease. Volcano-shaped ulcers are specially inclined to perforate. Both clinicians and endoscopists should be alert against barotrauma applied during colonoscopy may cause perforation. Also patients should be followed-up necessarily and in case of abdominal pain after colonoscopic examination, colonic perforation should always be kept in mind.f


The Journal of Infectious Diseases | 2018

Interferon Treatment Duration in Patients With Chronic Delta Hepatitis and its Effect on the Natural Course of the Disease

Cihan Yurdaydin; Onur Keskin; Çağdaş Kalkan; Fatih Karakaya; Aysun Çalişkan; Gökhan Kabaçam; F. Oğuz Önder; Senem Karatayli; Ersin Karatayli; Xheni Deda; Hakan Bozkaya; A. Mithat Bozdayi; Ramazan Idilman

Background Interferon is the only treatment option in chronic delta hepatitis (CDH). A CDH database (333 patients, 161 with interferon treatment history) was analyzed for effects of treatment duration on virologic response and clinical outcomes. Methods Ninety-nine CDH patients who received at least 6 months of interferon were selected. Maintained virologic response (MVR) was defined as hepatitis D virus RNA negative for 2 years after treatment discontinuation. Cumulative median interferon treatment duration was 24 months (range 6-126 months), with a median of 2 courses (range 1-8). Post-treatment median follow-up was 55 months (24-225 months). Results Thirty-five patients achieved MVR. Cumulative probability of MVR increased with treatment duration and reached 50% at 5 years. Patients with MVR were less likely to die from liver disease or develop complications compared to patients without MVR (P = .032, P = .006, respectively). Cirrhosis at baseline and no response to therapy (odds ratio 16.1 and 5.23, respectively) predicted an adverse endpoint. Hepatitis B surface antigen clearance occurred in 37% of patients with MVR. Conclusion Viral response to interferon increases with treatment duration and favorably affects the natural course of disease. Interferon treatment duration has to be individualized with careful post-treatment assessment.


Geriatrics & Gerontology International | 2017

Differences between older and young patients with autoimmune gastritis

Çağdaş Kalkan; Irfan Soykan

Elderly patients with autoimmune gastritis might have different symptoms than those of young patients. The aim of the present study was to compare presented symptoms and laboratory parameters associated with autoimmune gastritis in both old and young age groups.

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