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Featured researches published by Alev Ozon.


Pediatric Neurosurgery | 2004

Endocrinological Outcome of Different Treatment Options in Children with Craniopharyngioma: A Retrospective Analysis of 66 Cases

E. Nazli Gonc; Nursen Yordam; Alev Ozon; Ayfer Alikasifoglu; Nurgun Kandemir

Craniopharyngioma is one of the leading causes of hypothalamic-pituitary dysfunction in childhood, caused either by the tumor itself or the consequences of treatment. Tumor management in terms of recurrence rate, quality of life and complications is still controversial. Sixty-six patients with craniopharyngioma at pediatric age were reviewed for symptoms, signs, types of treatment, recurrence rates, complications, and endocrinological outcome. The majority of symptoms was related to the neurological system. Complaints only affecting the endocrinological system were seen in 6% of patients. The most frequent complaints were headache and vomiting (74.2%). The main endocrinological complaints were polyuria and polydipsia (15%), and lassitude (10.6%). Although short stature was a symptom in 9.1% of patients, it was a finding in 39.7% of patients. Plain skull X-rays raised the suspicion of intracranial tumor in more than 90% of children with craniopharyngioma. Recurrence rates were independent of the extent of tumor removal (total or subtotal). The frequency of endocrine dysfunction increased significantly after treatment. The most frequent hypothalamic-pituitary dysfunction was growth hormone deficiency (100%) and gonadotropin deficiency (80%). Hypothyroidism was diagnosed in 74% of patients. The frequency of hypothalamic-pituitary dysfunction was not affected by the extent of tumor removal. Radiotherapy did not increase the frequency of endocrine dysfunctions further. In conclusion, growth follow-up in childhood seems to be an important indicator of craniopharyngioma in early diagnosis. Radiotherapy and extent of tumor removal – either total or subtotal – did not influence endocrine outcome.


Journal of Pediatric Endocrinology and Metabolism | 2007

Hashimoto's thyroiditis in children and adolescents: A retrospective study on clinical, epidemiological and laboratory properties of the disease

Huseyin Demirbilek; Nurgun Kandemir; Gonc En; Alev Ozon; Ayfer Alikasifoglu; Nursen Yordam

UNLABELLED Hashimotos thyroiditis (HT) is the most common cause of goiter and acquired hypothyroidism in children and adolescents in iodine replete areas. To find out the clinical, epidemiological and laboratory characteristics of the disease in childhood, we reviewed files of 162 children and adolescents with HT followed in the Department of Pediatric Endocrinology, Hacettepe University Faculty of Medicine. RESULTS Female patients constituted 86.4% (n = 140) of all patients with a female:male ratio of 6.4. Mean age at diagnosis was 11.4 +/- 2.97 years (age range 4.4-16.5 years). At the time of diagnosis 43.2% of the patients (n = 70) were euthyroid, 24.1% (n = 39) had subclinical hypothyroidism, 21% (n = 34) had overt hypothyroidism, and 8.6% (n = 14) had overt and 3.1% (n = 5) subclinical hyperthyroidism. CONCLUSIONS Autoimmune thyroiditis is more frequent in females, and increases in frequency over age during childhood and adolescence. At the time of diagnosis, frequency of overt and subclinical hypothyroidism is similar to that of euthyroid goiter.


Hormone Research in Paediatrics | 2007

Diagnostic Value of Salivary Cortisol in Children with Abnormal Adrenal Cortex Functions

Semra Çetinkaya; Alev Ozon; Nursen Yordam

Aims: It has been shown that the free cortisol level in saliva may reflect plasma free cortisol. The measurement of cortisol in saliva is a simple method, and as such it is important in the pediatric age group. In this research, the diagnostic value of measurement of salivary cortisol (SC) measurement was examined in adrenal insufficiency (AI). Methods: Fifty-one patients, mean age 10.8 ± 4.29, who were investigated for possible AI, were included. Basal cortisol levels were below 18 µg/dl. Adrenal function was determined by low-dose ACTH test. During the test, samples for SC were obtained simultaneously with serum samples (at 0–10–20–30–40 min). Results: Mean basal serum cortisol level was 8.21 ± 4.10 µg/dl (mean ± SD). Basal SC was correlated to basal serum cortisol (r = 0.64, p < 0.001). A cut-off of 0.94 µg/dl for SC differentiated adrenal insufficient subjects from normals with a sensitivity and specificity of 80 and 77%, respectively. A peak SC less than 0.62 µg/dl defined AI with a specificity of 100%; however, sensitivity was 44%. Conclusion: Measurement of SC may be used in the evaluation of AI. It is well-correlated to serum cortisol. Peak SC in low-dose ACTH test can be used to differentiate patients with AI in the initial evaluation of individuals with suspected AI.


Clinical Endocrinology | 2009

Assessment of thyroid function during the long course of Hashimoto's thyroiditis in children and adolescents

Huseyin Demirbilek; Nurgun Kandemir; E. N. Gonc; Alev Ozon; Ayfer Alikasifoglu

Context  The prognosis of Hashimotos thyroiditis (HT) in children and adolescents is not well known and studies reporting long‐term outcome of the disease are scarce.


Proceedings of the National Academy of Sciences of the United States of America | 2017

Clinical, genetic, and structural basis of congenital adrenal hyperplasia due to 11β-hydroxylase deficiency

Ahmed Khattab; Shozeb Haider; Ameet Kumar; Samarth Dhawan; Dauood Alam; Raquel Romero; J. H. Burns; Di Li; Jessica Estatico; Simran Rahi; Saleel Fatima; Ali Alzahrani; Mona Hafez; Noha Musa; Maryam Razzghy Azar; Najoua Khaloul; Moez Gribaa; Ali Saad; Ilhem Ben Charfeddine; Berenice B. Mendonca; Alicia Belgorosky; Katja Dumic; Miroslav Dumić; Javier Aisenberg; Nurgun Kandemir; Ayfer Alikasifoglu; Alev Ozon; Nazli Gonc; Tina Cheng; Ursula Kuhnle-Krahl

Significance Congenital adrenal hyperplasia resulting from mutations in the CYP11B1 gene, which encodes a steroidogenic enzyme 11β-hydroxylase, is a rare inherited disorder associated with hyperandrogenemia, short stature, hypertension, and virilization of female newborns. We present a comprehensive clinical, genetic, and hormonal characterization for 68 of 108 patients with a genotype from an International Consortium on Rare Steroid Disorders. We also use computational modeling to define the effect of each of the missense mutations on the structure of 11β-hydroxylase, information that can be used to predict clinical severity prenatally in high-risk mothers. Congenital adrenal hyperplasia (CAH), resulting from mutations in CYP11B1, a gene encoding 11β-hydroxylase, represents a rare autosomal recessive Mendelian disorder of aberrant sex steroid production. Unlike CAH caused by 21-hydroxylase deficiency, the disease is far more common in the Middle East and North Africa, where consanguinity is common often resulting in identical mutations. Clinically, affected female newborns are profoundly virilized (Prader score of 4/5), and both genders display significantly advanced bone ages and are oftentimes hypertensive. We find that 11-deoxycortisol, not frequently measured, is the most robust biochemical marker for diagnosing 11β-hydroxylase deficiency. Finally, computational modeling of 25 missense mutations of CYP11B1 revealed that specific modifications in the heme-binding (R374W and R448C) or substrate-binding (W116C) site of 11β-hydroxylase, or alterations in its stability (L299P and G267S), may predict severe disease. Thus, we report clinical, genetic, hormonal, and structural effects of CYP11B1 gene mutations in the largest international cohort of 108 patients with steroid 11β-hydroxylase deficiency CAH.


Journal of Pediatric Endocrinology and Metabolism | 2008

Cyclic pamidronate therapy in children with osteogenesis imperfecta: results of treatment and follow-up after discontinuation.

Nesibe Andiran; Ayfer Alikasifoglu; Nazli Gonc; Alev Ozon; Nurgun Kandemir; Nursen Yordam

BACKGROUND Cyclic intravenous pamidronate treatment is widely used for symptomatic therapy of osteogenesis imperfecta (OI). However, data after discontinuation are very limited. AIM The results of cyclical pamidronate treatment in 14 patients with moderate/severe OI and follow up of six of them after discontinuation are presented to assess the effects of pamidronate and its discontinuation. PATIENTS AND METHODS Pamidronate was administered at a dosage of 0.5 mg/kg for 3 successive days every 2 months in 14 patients with OI aged 5.10 +/- 3.68 years. Treatment was stopped in six patients after a duration of 16.33 +/- 4.63 months, due to stable bone mineral density (BMD) values and/or no fracture in the last 6 months, or due to family demand. The main outcome measures were areal BMD (aBMD) of the lumbar spine, biochemical markers of bone metabolism, fracture rate, and clinical evaluation. RESULTS Areal BMD and aBMD z-scores showed significant improvement during the treatment period. Both serum and bone-specific alkaline phosphatase values were significantly decreased. Fracture rate reduced significantly from 3.5 +/- 1.01 to 0.83 +/- 0.77 fractures/year. Bone pain, which was severe in five patients, disappeared just after the first cycle, and the activity and mobility of patients increased. aBMD and aBMD z-scores were decreased 1.5 years after discontinuation, although not statistically significant. Annual fracture rate increased significantly. Bone pain recurred in four patients. Pamidronate treatment was reinstituted in five of these patients at the end of 1.5 years. CONCLUSION Cyclical pamidronate treatment is very effective in children with moderate/severe OI. This treatment should be started early enough before the occurrence of irreversible deformities and must be given for a longer time during the growth period.


Journal of Pediatric Endocrinology and Metabolism | 2007

Inappropriate use of potent topical glucocorticoids in infants.

Alev Ozon; Cetinkaya S; Ayfer Alikasifoglu; Gonc En; Sen Y; Nurgun Kandemir

Topical therapy with glucocorticoids (GCs) is used commonly in chronic dermatoses. Side effects are less common compared to systemic use; however, newer potent preparations may have serious side effects. A potential danger is their inappropriate use. Three infants who developed iatrogenic Cushings syndrome and prolonged adrenal suppression in the course of GC therapy for simple diaper dermatitis are described. One patient also developed steatohepatitis which is uncommon with local GCs.


Journal of Asthma | 2002

Increased Interleukin-4 and Decreased Interferon Gamma Production in Children with Asthma: Function of Atopy or Asthma?

Akgul Akpinarli; Dicle Guc; Omer Kalayci; Emre Yigitbas; Alev Ozon

Both atopy and asthma are claimed to be associated with a Th-2 cytokine pattern. We sought to determine the contribution of atopy and asthma to the observed Th-2/Th-1 imbalance in these conditions. Of 60 children aged 6–16 years that were included in the study, 13 were nonatopic nonasthmatic, 15 atopic nonasthmatic, 14 nonatopic asthmatic, and 18 atopic asthmatic. Atopic children had positive skin prick tests to grass pollens only. All children were studied after an asymptomatic and drug-free period of at least three months. Total IgE was measured in serum. Peripheral blood mononuclear cells were cultured and stimulated in vitro with phytohemagglutinin and interferongamma (IFN-γ) and interleukin-4 (IL-4) measured in the supernatants. Total IgE was significantly higher in atopic asthmatics compared to nonatopic asthmatics (p = 0.004), and nonatopic nonasthmatics (p = 0.001), but was not different from atopic nonasthmatics (p > 0.05). On the other hand, IL-4 was significantly elevated in atopic asthmatics and in nonatopic asthmatics compared to nonatopic nonasthmatics (p = 0.037 and p = 0.009, respectively). Although atopic asthmatics had lower IFN-γ values than nonatopic asthmatics, the difference did not reach statistical significance. No correlation was detected between any two parameters. Our results suggest that both atopy and asthma contribute to the increased levels of IL-4 and that, whereas nonatopic asthma is associated with increases in both IL-4 and IFN-γ release by mononuclear cells, only atopic asthma is characterized by a Th-2 type cytokine dominance.


Journal of Clinical Research in Pediatric Endocrinology | 2012

Hypophosphatasia Presenting with Pyridoxine-Responsive Seizures, Hypercalcemia, and Pseudotumor Cerebri: Case Report

Huseyin Demirbilek; Yasemin Alanay; Ayfer Alikasifoglu; Meral Topçu; Etienne Mornet; Nazli Gonc; Alev Ozon; Nurgun Kandemir

Hypophosphatasia (HPP) is an inborn error of metabolism characterized by defective bone mineralization caused by a deficiency in alkaline phosphatase (ALP) activity due to mutations in the tissue-nonspecific ALP (TNALP) gene. The clinical expression of the disease is variable. Six forms of HPP are identified according to age at presentation and clinical features. Patients with the infantile form are normal at birth. First symptoms appear within the first 6 months of life. Along with skeletal findings, HPP patients may present with hypercalcemia, seizures, pseudotumor cerebri, and pulmonary insufficiency. Seizures in HPP are refractory to conventional antiepileptic drugs, but are responsive to pyridoxine. Herein, we report a case of HPP who presented with pyridoxine-responsive seizures in the early neonatal period and was found to have hypercalcemia, skeletal demineralization and increased intracranial pressure. Key words: Hypophosphatasia, pyridoxine-responsive seizures, bisphosphonates, alkaline phosphatase, bone resorption, hypercalcemia Conflict of interest:None declared.


Journal of Pediatric Endocrinology and Metabolism | 2008

Final Heights of Boys with Normal Growth Hormone Responses to Provocative Tests Following Priming

Gonc En; Nurgun Kandemir; Alev Ozon; Ayfer Alikasifoglu

Priming with sex steroids prior to growth hormone (GH) stimulation tests for the diagnosis of GH deficiency is still debatable. We analyzed the auxological data of boys with growth retardation who had normal GH responses to stimulation tests only after priming to establish the validity of priming in the diagnosis of GH deficiency. We also analyzed the effect of different protocols for priming and their efficiency in the diagnosis of GH deficiency. Fifty boys with growth retardation who failed to respond to unprimed GH stimulation tests but responded normally to primed tests were included in the study. Thirty-one of 50 boys responded to GH stimulation tests after single low dose testosterone, 11/50 boys after single conventional dose, and 8/50 boys with multiple-dose testosterone. The study group was followed till final height; height velocity, final height and height SDS were compared to parental and mid-parental heights to determine whether or not the children achieved their height potential. Mean final height SDS of the study group (-1.27 +/- 0.72 SDS) was similar to mid-parental (-1.38 +/- 0.72 SDS) (p = 0.249) and maternal height SDS (-1.26 +/- 1.05 SDS) (p = 0.941), whereas it was greater than the paternal height SDS (-1.7 +/- 0.86) (p = 0.001). The final height SDS of the study group was correlated to maternal, paternal and mid-parental height SDS. Height velocity after the test was greater than the previous height velocity. Final height SDS of the boys who responded to the GH stimulation tests with different priming protocols were compared and found to be similar. Normal responders in primed GH tests grow normally to their target height, suggesting that priming might be a valuable method in the assessment of GH status. Use of priming in the GH stimulation tests of peripubertal boys with decreased growth rate may help avoid unnecessary GH therapy. Multiple-dose testing might exclude GHD in a patient population who failed to respond to a single dose of testosterone. This finding suggests that multiple-dose testosterone might be a more valuable method for priming in the differentiation of normal from abnormal GH secretion.

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Nurgun Kandemir

Boston Children's Hospital

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Nurgun Kandemir

Boston Children's Hospital

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