Researcher:
Taşdemir, Mehmet

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Mehmet

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Taşdemir

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Taşdemir, Mehmet

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2016 - 2019262020 - 202216

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    Improving the urine spot protein/creatinine ratio by the estimated creatinine excretion to predict proteinuria in pediatric kidney transplant recipients
    (Wiley, 2021) Palaoğlu, Kerim Erhan; N/A; İncir, Said; Taşdemir, Mehmet; Koçak, Burak; Yelken, Berna; Arpalı, Emre; Akyollu, Başak; Baygül, Arzu Eden; Bilge, İlmay; Türkmen, Aydın; Doctor; Faculty Member; Faculty Member; Doctor; Doctor; Doctor; Faculty Member; Faculty Member; Doctor; N/A; School of Medicine; School of Medicine; N/A; N/A; N/A; School of Medicine; School of Medicine; N/A; Koç University Hospital; N/A; N/A; Koç University Hospital; Koç University Hospital; Koç University Hospital; N/A; N/A; Koç University Hospital; 175430; 175867; 220671; N/A; N/A; N/A; 272290; 198907; N/A
    Background Since the daily creatinine excretion rate (CER) is directly affected by muscle mass, which varies with age, gender, and body weight, using the spot protein/creatinine ratio (Spot P/Cr) follow-up of proteinuria may not always be accurate. Estimated creatinine excretion rate (eCER) can be calculated from spot urine samples with formulas derived from anthropometric factors. Multiplying Spot P/Cr by eCER gives the estimated protein excretion rate (ePER). We aimed to determine the most applicable equation for predicting daily CER and examine whether ePER values acquired from different equations can anticipate measured 24 h urine protein (m24 h UP) better than Spot P/Cr in pediatric kidney transplant recipients. Methods This study enrolled 23 children with kidney transplantation. To estimate m24 h UP, we calculated eCER and ePER values with three formulas adapted to children (Cockcroft-Gault, Ghazali-Barratt, and Hellerstein). To evaluate the accuracy of the methods, Passing-Bablok and Bland-Altman analysis were used. Results A statistically significant correlation was found between m24 h UP and Spot P/Cr (p < .001, r = 0.850), and the correlation was enhanced by multiplying the Spot P/Cr by the eCER equations. The average bias of the ePER formulas adjusted by the Cockcroft-Gault, Ghazali-Barratt, and Hellerstein equations were -0.067, 0.031, and 0.064 g/day, respectively, whereas the average bias of Spot P/Cr was -0.270 g/day obtained by the Bland-Altman graphics. Conclusion Using equations to estimate eCER may improve the accuracy and reduce the spot urine samples' bias in pediatric kidney transplantation recipients. Further studies in larger populations are needed for ePER reporting to be ready for clinical practice.
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    Progress Study: progression of chronic kidney disease in children and heat shock proteins
    (SPRINGER, 2021) Yürük Yıldırım, Zeynep Nagehan; Usta Akgül, Sebahat; Alpay, Harika; Aksu, Bağdagül; Savran Oğuz, Fatma; Kıyak, Aysel; Akıncı, Nurver; Yavuz, Sevgi; Özçelik, Gül; Gedikbaşı, Asuman; Gökçe, İbrahim; Özkayın, Neşe; Yıldız, Nurdan; Pehlivanoğlu, Cemile; Göknar, Nilüfer; Saygılı, Seha; Tülpar, Sebahat; Küçük, Nuran; Ağbaş, Ayşe; Dirican, Ahmet; Emre, Sevinç; Nayir, Ahmet; Yolmaz, Alev; Bilge, İlmay; Taşdemir, Mehmet; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 198907; 175867
    Various molecular and cellular processes are involved in renal fibrosis, such as oxidative stress, inflammation, endothelial cell injury, and apoptosis. Heat shock proteins (HSPs) are implicated in the progression of chronic kidney disease (CKD). Our aim was to evaluate changes in urine and serum HSP levels over time and their relationships with the clinical parameters of CKD in children. In total, 117 children with CKD and 56 healthy children were examined. The CKD group was followed up prospectively for 24 months. Serum and urine HSP27, HSP40, HSP47, HSP60, HSP70, HSP72, and HSP90 levels and serum anti-HSP60 and anti-HSP70 levels were measured by ELISA at baseline, 12 months, and 24 months. The urine levels of all HSPs and the serum levels of HSP40, HSP47, HSP60, HSP70, anti-HSP60, and anti-HSP70 were higher at baseline in the CKD group than in the control group. Over the months, serum HSP47 and HSP60 levels steadily decreased, whereas HSP90 and anti-HSP60 levels steadily increased. Urine HSP levels were elevated in children with CKD; however, with the exception of HSP90, they decreased over time. In conclusion, our study demonstrates that CKD progression is a complicated process that involves HSPs, but they do not predict CKD progression. The protective role of HSPs against CKD may weaken over time, and HSP90 may have a detrimental effect on the disease course.
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    Approaches of pediatric nephrologists to hypertensive patients in Turkey (Turkish pediatric hypertension working group study)
    (Springer, 2018) Demir, Belde Kasap; Hacıhamdioğlu, Duygu Övüç; Girişgen, İlknur; Dursun, Hasan; Çivilibal, Mahmut; Benzer, Meryem; Bıyıklı, Neşe Karaaslan; Özkayın, Neşe; Sönmez, Ferah; Taşdemir, Mehmet; Faculty Member; School of Medicine; 175867
    Objective: We aimed to evaluate the approaches of pediatric nephrologists in our country to the management of childhood hypertension. Methods: The pediatric nephrologists in our country were invited to fill out an online questionnaire including 24 questions. The answers were compared between those working in the field for <= 10 years (Group 1, n =74) and >10 years (Group 2, n = 62). Results: of 136 participants (M/F = 101/35), 52% were following a single guideline [31% Fourth Report of 2004, 17% European Society of Hypertension in 2016, and 52% American Academy of Pediatrics in 2017], which is more common in Group 1 (P =.035). The most commonly used guideline was American Academy of Pediatrics of 2017 and Group 2 used Fourth Report of 2004 more commonly (P =.042). The most common choice to diagnose hypertension was office + home + ambulatory blood pressure monitoring (59%). The frequency of screening for end-organ damage at first evaluation was 96%. The time to wait for the effect of lifestyle modifications was 3 months in 52%. The first choice medication was angiotensin-converting enzyme inhibitors (49%) or calcium-channel blockers (48%) in non-obese and angiotensin-converting enzyme inhibitors (74%) in obese children. Calcium-channel blockers were more commonly prescribed as the first choice in non-obese children in Group 1 (P =.035). The most accessible emergency drug was esmolol. Conclusion: Despite following recent guidelines, the time spent in the proficiency would change the practices.
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    Hemolytic uremic syndrome outbreak in Istanbul-Turkey in 2015; outcome and eculizumab experience
    (Springer, 2017) Ağbaş, Ayşe; Göknar, Nilufer; Akıncı, Nurver; Yıldırım, Zeynep Yürük; Benzer, Meryem; Gökçe, İbrahim; Küçük, Nuran; Çalışkan, Salim; Taşdemir, Mehmet; Demirkol, Demet; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 175867; 108964
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    A rare cause of chronic hyponatremia in an infant: aldosterone synthase type-2 deficiency
    (Springer, 2018) Güran, Tülay; Yeşiltepe Mutlu, Rahime Gül; Taşdemir, Mehmet; Kızılkan, Nuray Uslu; Börklü Yücel, Esra; Hatun, Şükrü; Kayserili, Hülya; Bilge, İlmay; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Faculty Member; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; 153511; N/A; 221274; N/A; 153504; 7945; 198907
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    COVID-19 in children with chronic dialysis and kidney transplantation: a multicenter study from Istanbul
    (SPRINGER, 2021) Canpolat, Nur; Yıldırım, Zeynep Yürük; Yıldız, Nurdan; Göknar, Nilüfer; Evrengül, Havva; Gülmez, Rüveyda; Aksu, Bağdagül; Dursun, Hasan; Özçelik, Gül; Yavaşcan, Önder; Çiçek, Rümeysa Yasemin; Tülpar, Sebahat; Hacıhamdioğlu, Duygu Övünç; Nayir, Ahmet; Alpay, Harika; Taşdemir, Mehmet; Faculty Member; School of Medicine; Koç University Hospital; 175867
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    Is there a unique symptom in lower urinary tract dysfunction in children?
    (Wiley, 2021) N/A; N/A; Özen, Mehmet Ali; Taşdemir, Mehmet; Aygün, Murat Serhat; Necef, Işıl; Aydın, Emrah; Bilge, İlmay; Eroğlu, Egemen; Faculty Member; Faculty Member; Teaching Faculty; Faculty Member; Faculty Member; Faculty Member; Faculty Member; School of Medicine; School of Medicine School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; 293404; 175867; 291692; N/A; 32059; 198907; 214688
    Objectives Lower urinary tract symptoms (LUTS), particularly urgency, incontinence and intermittency are common in children and it is suggested that the specific symptoms may be used for definite diagnosis for LUT dysfunction (LUTD). This study was performed to investigate the relationship between each LUTD and its associated symptoms, using uroflowmetry/electromyography (UF/EMG) as a diagnostic tool. Methods Each patient was categorized into one of four LUT conditions which were overactive bladder (OAB), dysfunctional voiding (DV), underactive bladder and primary bladder neck dysfunction (PBND), according to UF/EMG results. Patients' complaints and findings were documented by using voiding dysfunction symptom score, bladder diary, urine analysis and ultrasonography. In addition, a detailed history of bowel habits (including use of Rome III criteria) was obtained. Results There were 189 children of which 106 were female. The OAB was the largest group including 91 patients, followed by the DV group which had 61 patients. The symptoms specific to any LUTD group were constipation and hesitancy (P < .05). Hesitancy was present in 89.4% with PBND and constipation was present in 78.6% of patients with DV. None of other symptoms were able to differentiate any LUTD group from the other. Conclusions While certain symptoms are often presumed by clinicians to imply specific diagnoses, the main outcome of this study is that there is a generally weak correlation between the specificity of symptoms and LUTD. Symptoms-based approach may lead to misdiagnosis in LUTD. Thus, it may be essential to focus on the underlying pathologies and UF/EMG test may help this.
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    Outbreak of Shiga toxin-producing Escherichia-coli-associated hemolytic uremic syndrome in Istanbul in 2015: outcome and experience with eculizumab
    (Springer, 2018) Ağbas, Ayşe; Göknar, Nilüfer; Akıncı, Nurver; Yıldırım, Zeynep Yürük; Benzer, Meryem; Gökçe, İbrahim; Candan, Cengiz; Küçük, Nuran; Uzuner, Selçuk; Özçelik, Gül; Sever, Lale; Çalışkan, Salim; Taşdemir, Mehmet; Demirkol, Demet; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 175867; 108964
    Background: This study aims to identify epidemiological and clinical characteristics of patients and report our experience with eculizumab treatment during an outbreak of hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) in Istanbul in 2015. Methods: Thirty-two children (21 females, median age 3.25 years) were included in this study. Demographic, clinical and laboratory data, and treatment details were retrospectively collected. Renal outcomes were assessed at last follow-up visit. To assess the effect of eculizumab on prognosis of STEC-HUS, subgroup analysis was performed on patients who required dialysis. Results: A high number of cases occurred within a certain region of Istanbul. Stool samples were cultured from 21 patients (65%), and enteroaggregative E. coli (EAEC; n = 7) and enterohemorrhagic E. coli (EHEC; n = 3) strains were detected. Rates of dialysis treatment, neurological manifestations, and death were 59%, 25%, and 3%, respectively. Mean follow-up duration was 8.6 ± 2.6 months (range 3–12 months). None of the patients (n = 25) was on dialysis at the final visit. The complete renal recovery rate was 54%. Nine patients were treated with eculizumab. At final follow-up visit, no differences in estimated glomerular filtration rate, proteinuria level, or hypertension incidence were observed between patients treated with eculizumab and those not treated with eculizumab. Conclusions: An outbreak of EAEC occurred in a specific region of Istanbul. Livestock markets were suspected as the source. Evidence for beneficial effects of eculizumab on renal outcome was not clear in this cohort.
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    Are there any new reliable markers to detect renal injury in obese children?
    (2018) Gayret, Özlem Bostan; Erol, Meltem; Nacaroğlu, Hikmet Tekin; Zengi, Oğuzhan; Yiğit, Özgül; Taşdemir, Mehmet; Faculty Member; School of Medicine; Koç University Hospital; 175867
    Aim: The aim of this study was to examine the serum and urine levels of kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), osteopontin (OPN), matrix metalloproteinase-9 (MMP-9), and serum Cystatin-C to determine the renal effect of obesity in obese children. Methods: Seventy-two obese and 35 non-obese healthy children were included in this study. Blood pressure (BP) was evaluated with office measurement. Creatinine, cystatin C, lipids, fasting glucose, and insulin levels were measured, and homeostasis model assessment -insulin resistance (HOMA-IR) was calculated. The urine albumin/creatinine ratio was calculated. The serum and urine KIM-1, NGAL, OPN, and MMP-9 levels were measured. Results: Serum cystatin-C, triglyceride, and homeostasis model assessment-insulin resistance (HOMA-IR) index were found to be significantly higher in the obese group (p = .0001), and high-density lipoprotein (HDL) cholesterol was found to be significantly lower (p = .019) in the obese group. No significant differences were found in serum KIM-1, NGAL, OPN or MMP-9 levels between groups (p > .05). No significant differences were found in urine KIM-1 and MMP-9 levels (p > .05), Urine NGAL, and OPN levels were found significantly higher in obese groups (p < .05). Conclusions: According to our results, although serum KIM-1, NGAL, OPN, MMP-9, and urine MMP-9, urine KIM-1 do not appear to be ideal markers to evaluate renal injury in the early period of obesity, the serum levels of cystatin C and urine NGAL, urine OPN can be used as a good marker for assessing the renal effect of obesity which can lead end stage renal disease in pediatric population.
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    Association of osteoprotegerin with obesity, ınsulin resistance and non-alcoholic fatty liver disease in children
    (Kowsar Publ, 2016) Erol, Meltem; Gayret, Özlem Bostan; Nacaroğlu, Hikmet Tekin; Yiğit, Özgül; Zengi, Oğuzhan; Akkurt, Mehmet Salih; Taşdemir, Mehmet; Faculty Member; School of Medicine; Koç University Hospital; 175867
    Background: Osteoprotegerin (OPG) is a member of the tumor necrosis factor superfamily. Reduced OPG levels are related to obesity, insulin resistance, and non-alcoholic fatty liver disease (NAFLD). Objectives: The aim of this study was to evaluate the relationship between OPG levels, obesity, insulin resistance, and NAFLD in pediatric patients. Methods: This was a prospective, cross-sectional, controlled study that was conducted in the department of pediatrics at Bagcilar training and research hospital in Istanbul, Turkey, between April and August 2015. The study was performed on 107 children with obesity and 37 controls aged 5-17 years. In the obese subset, 62 patients had NAFLD. Homeostatic model assessment-insulin resistance (HOMA-IR) was used to calculate insulin resistance. Insulin resistance was defined as a HOMA-IR value greater than 2.5. Plasma OPG levels were measured using enzyme-linked immunosorbent assays. NAFLD was diagnosed by hepatic ultrasound. Results: The mean age was 11.25 +/- 3.38 years in the patient group and 10.41 +/- 3.15 years in the control group. The OPG level in the obese group with the mean of 55.20 +/- 24.55 pg/mL (median = 48.81 pg/mL) was significantly lower than that in the control group with the mean of 70.78 +/- 33.41 pg/mL (median = 64.57 pg/mL) (P = 0.0001). The optimal cut-off point (sensitivity, specificity) of the OPG level for the diagnosis of obesity was +/- 46, 19 pg/mL. According to logistic regression analysis, fasting insulin (P = 0.036) and OPG (P = 0.01) levels were most affected by obesity. In the obese patients, who had HOMA-IR < 2.5, the mean level of OPG was 58.91 +/- 6.88729 pg/mL (median = 49.55). In the obese patients, who had HOMA-IR <= 2.5, the mean level of OPG was 54.19 +/- 22.21 pg/mL (median = 48.47). No significant correlations were found between OPG and HOMA-IR (P = 0.791). No statistically significant difference was observed in the mean OPG between patients with hepatosteatosis (mean = 54.55 +/- 25.01 pg/mL) (median = 49.46) and those without the disease (56.30 +/- 24.02 pg/mL) (mean = 48.34) (P = 0.089). Conclusions: We confirmed that serum OPG concentrations reduce in obese children. However, no correlation was identified between OPG and insulin resistance. OPG levels are not meaningful in the diagnosis of NAFLD in children with obesity.