Buckling of nonlocal bars and initial value method in nanotechnology

Bu &ccedil;alışmada, yerel olmayan elastisite &ccedil;er&ccedil;evesinde başlangı&ccedil; değerleri y&ouml;ntemi kullanılarak bir &ccedil;ubuğun burkulması araştırılmıştır. Bilindiği gibi nanoteknoloji, molek&uuml;ler boyutta (1-100 nm) fonksiyonel sistemlerin m&uuml;hendisliğidir. Atom ve molek&uuml;ller &ouml;l&ccedil;eğinde &ouml;zel y&ouml;ntem ve tekniklerle yapıların, materyallerin ve ara&ccedil;ların inş&acirc; edilmesini, bu &ouml;l&ccedil;ekte &ouml;l&ccedil;me, tahmin etme, izleme ve yapım faaliyetlerinde bulunmayı, benzeri g&ouml;r&uuml;lmemiş &ouml;zelliklerde yeni nanoteknolojik aygıtlar &uuml;retmeyi hedefler. Nanoteknolojiyi uygulanabilir kılan şey, atomların yapısı ve aralarındaki olağan&uuml;st&uuml; organizasyon &ouml;zelliği olduğundan atomların yapısı ve davranış bi&ccedil;imlerinin &ccedil;ok iyi bilinmesi gerekir. Nanoteknolojide ilk uygulamalar karbon nanot&uuml;p yapısı kullanılarak ger&ccedil;ekleştirilmiştir. Karbon nanot&uuml;pler hem yapısal, hem de mekanik &ouml;zellikleri bakımından nano &ouml;l&ccedil;ekteki malzemelere en g&uuml;zel &ouml;rneklerden biri olup, sahip oldukları olağan&uuml;st&uuml; &ouml;zelliklerden dolayı bilinen en sert ve en g&uuml;&ccedil;l&uuml; liflerdir. Ayrıca karbon nanot&uuml;pler, molek&uuml;ler boyutta grafit karbonların i&ccedil;i boş silindirik &ccedil;ubukları olarak d&uuml;ş&uuml;n&uuml;l&uuml;r ve geniş &ccedil;apta nanoteknolojik uygulamalarda kullanılırlar. &Ccedil;alışmada başlangı&ccedil; değerleri y&ouml;nteminin uygulanabilirliği i&ccedil;in gerekli olan taşıma matrisi verilmiştir. Bir &ccedil;ubuğa ait taşıma matrisinin bilinmesinin en &ouml;nemli avantajlarından biri, &ccedil;ubukların kuvvetler etkisi altındaki davranışlarını sistematik olarak incelemeyi m&uuml;mk&uuml;n kılmasıdır. Taşıma matrisi elde edildikten sonra &ccedil;eşitli t&uuml;rlerde desteklenmiş &ccedil;ubuklar i&ccedil;in kritik y&uuml;kler hesaplanmıştır. Uygulamalarda elde edilen sonu&ccedil;lar, yerel olmayan etkilerin&nbsp; nanoyapıların mekanik davranışlarını anlamada klasik elastisiteye g&ouml;re &ccedil;ok daha g&uuml;&ccedil;l&uuml; olduğunu ve karbon nanot&uuml;plerin burkulmasında da yerel olmayan etkilerin &ouml;nemli olduğunu g&ouml;stermektedir.&nbsp;Anahtar Kelimeler: Nanoteknoloji, yerel olmayan elastisite, başlangı&ccedil; değer y&ouml;ntemi, nanot&uuml;pler.Nanotechnology is a field of applied science and technology covering a broad range of topics. The main unifying theme is the control of matter on a scale smaller than 1 micrometer, normally between 1-100 nanometers, as well as the fabrication of devices on this same length scale. Nanotechnology cuts across many disciplines, including colloidal science, chemistry, applied physics, materials science, and even mechanical and electrical engineering. Carbon NanoTube (CNT) is a new form of carbon, configurationally equivalent to two dimensional graphene sheet rolled into a tube. It is grown now by several techniques in the laboratory and is just a few nanometers in diameter and several microns long. They are the stiffest and strongest known fibers and have unique electrical properties. An ideal nanotube can be thought of as a hexagonal network of carbon atoms that has been rolled up to make a seamless cylinder. In classical elasticity theory the stress tensor at a given point depends linearly on the strain tensor of the same point. Thus, local elastic theory contains no information about the long range forces between atoms i.e., there is no internal length scale. On the other hand, the theory of nonlocal continuum mechanics assumes that the stress state at a given reference point is considered to be function of the strain states of all points in the body. Properties of materials at the nanoscale differ fundamentally from those of their bulk counterparts. Carbon nanotubes are one of the structural elements that are used in nanotechnological applications widely. In this study, they are envisioned as hollow cylindrical bars of graphitic carbon at the nanoscale. For these reasons nonlocal theory is more capable to display the mechanical behaviour of materials at the nanoscale. Carbon nanotubes hold substantial promise for the development of nanotechnology. However, thorough understanding of the mechanical behavior of carbon nanotubes is essential. Currently, theoretical treatment of buckling of carbon nanotubes has relied on the use of classical continuum mechanics models, such as the elastic shell model or the Bernoulli-Euler beam bending model. Although classical continuum models are relevant to some extent, and efficient in computation for models at large length scales, the applicability of these classical continuum models at small length scales is questionable. Multiple recent experimental results have shown a significant size-effect in mechanical properties when the dimensions of the specimen or the probed material volume become small. The classical continuum theories lack the capability of representing such effects since they do not include any internal length scale. Consequently, these theories are expected to fail when the specimen size become comparable with the internal length scale(s) of the material. Several modifications of the classical elasticity formulation have been proposed to address this deficiency. They are of nonlocal or gradient type and, as a common feature, include one or several intrinsic length scales. Nonlocal elasticity theory was proposed to account for the scale effect in elasticity by assuming the stress at a reference point to be a function of strain field at every point in the body. When the structure considered falls into the nanometer range, nonlacality parameter has a significant influence on the outcomes of this study. In some cases, the ratio of local and nonlocal buckling loads can be 1.4. The buckling of carbon nanotubes has been studied by molecular mechanics in literature. In this paper the method of initial values is used in the frame of nonlocal elasticity.  This method gives the values of the displacements and stress resultants throughout the rod once the initial displacements and initial stress resultants are known. A priority of this method is that the high degree of statical indeterminancy adds no extra hardship to the solution of the problem. It is interesting to note that the size of the matrix (2x2) from which the buckling determinant obtained in the presented method is the half of its classical counterpart. Local modeling of nanomaterials can be inaccurate, inadequate and misleading. Proposed nanotechnology devices are envisioned to have lengths on the order of nanometers(10-7 cm < L < 10-6 cm). It is clear that for the devices of this size nonlocal effects could be significant. The results are used to display that nonlocal effects could be significant in buckling of carbon nanotubes. Keywords: Nanotechnology, nanobar, carbon nanotubes, nonlocal elasticity, initial value problems

Pre-Loaded high strength bolted connections of aluminium members with steel members

Bu araştırmada al&uuml;minyum ve &ccedil;elik iki farklı malzemenin &ouml;ngerilmeli y&uuml;ksek mukavemetli bulonla s&uuml;rt&uuml;nme ile y&uuml;k aktaran birleşimi incelenmiştir. S&uuml;rt&uuml;nme ile y&uuml;k aktaran birleşimlerin davranışını belirlemek amacı ile, iki farklı grup deney ger&ccedil;ekleştirilmiştir. Bunlar, kısa s&uuml;reli ve uzun s&uuml;reli kayma deneyleridir. Kısa s&uuml;reli kayma deneyleri ile &ouml;ngerilmeli y&uuml;ksek mukavemetli bulonlu birleşimlerde, hem al&uuml;minyum ve hem de galvanizli &ccedil;elik temas y&uuml;zeylerine herhangi bir işlem yapılmadan sadece y&uuml;zeyler yağdan arındırılmış durum i&ccedil;in ve alkali silikat &ccedil;inko boya ile boyanmış durum i&ccedil;in, s&uuml;rt&uuml;nme katsayısı belirlenmiştir. Yukarıda belirtilen iki farklı temas y&uuml;zeyi haline ait y&uuml;k-yer değiştirme diyagramları, kayma y&uuml;k&uuml; ve sonrasında kopma haline kadar incelenmiştir. Deney sırasında y&uuml;k altında bulonlardaki &ouml;ngerilme kuvvetindeki değişim araştırılmıştır. Kısa s&uuml;reli deneylerde s&uuml;rt&uuml;nme y&uuml;zeylerine boya kullanılmaması durumunda birleşimler ekonomik olmaktan uzaktır. S&uuml;rt&uuml;nme arttırıcı alkali silikat &ccedil;inko boya kullanılması durumunda bir bulonun s&uuml;rt&uuml;nme ile taşıyabileceği kuvvet yaklaşık olarak 3.5 kat daha fazladır. Yapılan ond&ouml;rt adet kısa s&uuml;reli deneyden elde edilen verilerden yararlanılarak uzun s&uuml;reli deney sistemi hazırlanmış ve toplam onbeş adet uzun s&uuml;reli birleşim numunesi bir yıl boyunca &uuml;&ccedil; farklı &ccedil;er&ccedil;evede 90 kN, 78 kN ve 60 kN&rsquo;luk s&uuml;rekli y&uuml;k altında g&ouml;zlenmiştir. Bu deney sonu&ccedil;larının irdelenmesinde daha &ouml;nce literat&uuml;rde rastlanmayan sabit aralıklı ayrıklaştırma uygulanmak suretiyle elli yılsonundaki davranış tahmin edilmeye &ccedil;alışılmıştır. Bu araştırma ile al&uuml;minyum ve &ccedil;elikten oluşan farklı iki malzemenin birleşimi i&ccedil;in alkali silikat &ccedil;inko boyanın kullanılabileceği ve s&uuml;rt&uuml;nme katsayısını arttırdığı g&ouml;sterilmiştir. &nbsp;Anahtar Kelimeler: Birleşim, &ouml;ngerilmeli y&uuml;ksek mukavemetli bulon, al&uuml;minyum elemanlar.A certain amount of research and studies has been done on the connections of the same kind of material such as aluminum to aluminum or steel to steel connections. However, as far as the connections of two different materials are concerned, there are no systematic works on the subject. In order to connect hot dip galvanized steel material with aluminum material, it is necessary to use high strength pre-loaded bolts. The use of weld is not possible because of the different properties of materials. The presented work is the result of the studies conducted on two different materials- aluminium and steel and their friction grip pre-loaded high strength bolted connections. For this reason, two different types of experiments have been done. These tests are the short-term and the long-term tests, performed on four different dimensions of thickness: 10.0 mm, 9.7 mm, 8.0 mm and 5.0 mm, and on three different aluminum alloys: AlMgSi1 (6082), AlMgSi0.5 (6063) and AlZn4.5Mg1 (7020). In each specimen two 10.9 M16 bolts have been used. In the first five tests of the short-term tests, friction surfaces are only treated oil-free and in the latter 9 test specimens are painted with alkali silicate zinc. In pre-loaded high strength bolted connections, the friction coefficient had been determined for the aluminum and steel specimens with oil-free contact surfaces and also for the alkali silicate zinc painted contact surfaces. For the above mentioned two different cases of treatment of the contact surface, loading-displacement diagrams are studied for shear loads and after it then, up to the occurrence of the rupture. After having subjected the bolts to pre-loading, the loss of pre-load had been studied for 30 min. prior to the beginning of the test. During the test under load, the specimen was monitored to determine whether a sudden loss in pre-load occurred. In the short-term tests after applying the pre-loading to the bolts, no big loss on the pre-load was noticed, because of the creep behavior of aluminum in time. In the short-term tests, when no paint on the friction surfaces was used, the number of the bolts necessary for the proper connections would be too high to be considered economical. In case of using the friction-increasing alkali silicate zinc paint, the limit friction force of one bolt increases 3.5 times. A change of the thickness has no effect on the friction coefficient in short-term tests. When the aluminum alloy has lower yield stress than the steel, an indent under the washer will be observed. This observation is valid only for the AlMgSi0.5 (6063) alloy. That's why it is necessary to transfer the pre-load to a greater surface. To prevent the indent from happening, a thicker and wider washer could be used. After evaluating the short-term test results statistically, it has been noticed that the standard deviation of the distribution of friction coefficient does not exceed 10% limit. With the help of the results of fourteen short-term tests that were conducted, a long-term testing system was prepared and a total of fifteen long-term connection specimens in three different frames with 90 kN, 78 kN and 60 kN of continuous loading was monitored. The loading on each frame was determined so that the friction surface of each specimen was loaded with 75%, 65% and 50% ratios. To prepare the friction surfaces of long-term test specimens, all surfaces were treated with alkali silicate zinc paint. The long-term test had been carried out within one - year time span, during which the loading of each frame, the pre-loading on bolts and the slip between aluminum and steel plates were observed. The effect of small thickness on friction in the long-term tests causes the slip of contact surfaces in time. By using thinner aluminum plates, contact pressure was distributed on a smaller area of contact surface. This explains the earlier shear observed in the long-term tests under constant tension force. The thinner the specimen, the earlier the slip occurs. For the study of the long-term test results using constant distance separation - a method not found in the literature, an attempt has been made to predict the behavior of specimens within 50 years onwards. Inspecting of the 10 mm thick aluminum plate specimens after the period of one year shows that the predicted displacement in 50 years' time will be within the 0.30 mm slip limit range. The conclusion can be drawn that the alkali silicate zinc paint increases the friction coefficient of connections made of two different materials- aluminum and steel. Keywords: Connections, high strength bolts, aluminum members

Interim results from an ongoing, open-label, single-arm trial of odevixibat in progressive familial intrahepatic cholestasis

Background & Aims: PEDFIC 2, an ongoing, open-label, 72-week study, evaluates odevixibat, an ileal bile acid transporter inhibitor, in patients with progressive familial intrahepatic cholestasis. Methods: PEDFIC 2 enrolled and dosed 69 patients across two cohorts; all received odevixibat 120 μg/kg per day. Cohort 1 comprised children from PEDFIC 1, and cohort 2 comprised new patients (any age). We report data through 15 July 2020, with Week 24 of PEDFIC 2 the main time point analysed. This represents up to 48 weeks of cumulative exposure for patients treated with odevixibat from the 24-week PEDFIC 1 study (cohort 1A) and up to 24 weeks of treatment for those who initiated odevixibat in PEDFIC 2 (patients who received placebo in PEDFIC 1 [cohort 1B] or cohort 2 patients). Primary endpoints for this prespecified interim analysis were change from baseline to Weeks 22–24 in serum bile acids (sBAs) and proportion of positive pruritus assessments (≥1-point drop from PEDFIC 2 baseline in pruritus on a 0–4 scale or score ≤1) over the 24-week period. Safety monitoring included evaluating treatment-emergent adverse events (TEAEs). Results: In cohort 1A, mean change from PEDFIC 1 baseline to Weeks 22–24 of PEDFIC 2 in sBAs was -201 μmol/L (p <0.0001). For cohort 1B and cohort 2, mean changes from odevixibat initiation to weeks 22–24 in sBAs were -144 and -104 μmol/L, respectively. The proportion of positive pruritus assessments in the first 24-week period of PEDFIC 2 was 33%, 56%, and 62% in cohorts 1A, 1B, and 2, respectively. Most TEAEs were mild or moderate. No drug-related serious TEAEs occurred. Conclusions: Odevixibat in patients with progressive familial intrahepatic cholestasis was generally well tolerated and associated with sustained reductions in sBAs and pruritus. Clinical Trials Registration: This study is registered at ClinicalTrials.gov (NCT03659916). Impact and Implications: Disrupted bile flow is a hallmark feature of patients with progressive familial intrahepatic cholestasis and can result in build-up of bile constituents in the liver with spill over into the bloodstream; other effects that patients can experience include extremely itchy skin, and because not enough bile reaches the gut, patients can have problems digesting food, which may lead to poor growth. Odevixibat is an orally administered medication that shunts bile acids away from the liver. The current study, called PEDFIC 2, suggested that odevixibat can improve the problematic signs and symptoms of progressive familial intrahepatic cholestasis and was generally safe for patients

Existence and uniqueness theorems in nonlocal plasticity

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1992Thesis (Ph.D.) -- İstanbul Technical University, Institute of Science and Technology, 1992Bu çalışma 5 bölümden oluşmaktadır. Birinci bölümde önce yerel teori ve yerel olmayan teori kısaca tanıtılmış, daha sonra "Yerel olmayan plastisite" ve "Yarım düzlemde hareketli zımba" konusunda literatürde yapılan çalışmalar dan bahsedilmiştir. "Yerel olmayan plastisite teorisinde pekleşmeyen mal zeme için varlık ve teklik teoremleri" adlı ikinci bölüm de, önce plastisite teorisinin temel denklemleri verilmiş, daha sonra teoremlerin ispatı yapılırken kullanılacak olan matematik kavramlar kısaca açıklandıktan sonra yerel olma yan halde pekleşmeyen malzeme için plastisite problemi ta nımlanmıştır. Bundan sonra, önce problemin çözümünün tek olduğu, daha sonra ise çözümün mevcut olduğu gösterilmiş tir. Çalışmanın "îzotropik ve kinematik pekleşme olması durumunda yerel olmayan halde plastisite probleminin zayıf çözümünün varlığı ve tekliği" adlı üçüncü bölümünde, önce kinematik pekleşme ve izotropik pekleşme ayrı ayrı tanım lanmış ve bu halleri ifade eden bünye denklemleri veril miştir. Hem izotropik hem de kinematik pekleşmeyi birara- da ifade eden genel bir bünye denklemi elde edildikten sonra, yerel olmayan halde pekleşen malzeme için plastisi te probleminin tanımı verilmiş ve önce problemin çözümü nün tek olduğu, daha sonra ise problemin çözümünün mevcut olduğu gösterilmiştir. "Yarım düzlemde hareketli sürtünmeli zımba problemi nin yerel olmayan halde çözümü ve çözümün yerel haldeki sonuçlarla karşılaştırılması" adlı dördüncü bölümde, zımba problemi yerel olmayan elastisitede çözülerek sonuçlar yerel problemin sonuçları ile karşılaştırılmıştı r. Çalışmanın "EkA" bölümünde yerel halde yarım düzlemde hareketli zımba probleminin çözümü ayrıntılı şekilde ve rilmiştir. "EkB" adlı bölümde yerel olmayan halde hareketli zım ba probleminin çözümüyle ilgili bilgisayar çıkışları ve rilmiştir.As the first subject of this work, "Existence and uniqueness theorems in the nonlocal theory of perfect elastoplastici ty " has been handled. The stress boundary value problem can be weakly formulated as follows. A state of stress o..CO is looked for such v J that the following conditions are satisfied : ID In a bounded volume O, for every continuously dif ferentiable vector-valued function v CxD, i = 1,2,3 the following equality should be satisfied : f a £.. > 0 C4) VI where T..Cx.tD is a symmetric smooth tensor field «? J satisfying the first two conditions CI 5, C 33. We assume that there exists a c > O such that (T a ^ ' ' i jkl v j kl c fr. t. dx ; c>0 C53 for all t... 0, then X > O otherwise X = 0. The uniqueness of the solution can be shown by using the inequality C40 given in the third condition of the stress boundary value problem. We first assume that a = o, t = a where a and a are presumed to be both solutions: VÜ ...»..... r..Z... t) _ f dt f f   > O O such that f(c° where vxii C fCoO - a ] = o r fCoO-cx if fCe>0>a o o O otherwise This functional is convex. As a result its Gateaux differential satisfies the monotonocity condition: DgC a, cr-iO - DgCT,cr- iO > O The Gateaux differential of gCoO is CI 23 tf c C t,t D2, t e S o Then if Be = a we have a = -B& -P C X C22D *» 2 J O O O 4y o can be easily demonstrated to be valid where the inner product t, ] is defined by [ff,T] = f | 0 Ca6D o where c is statically admissible and Fl&, y,cb ,y,a;-T,y-6,oı-f& > O C313 where the triple r,6,ft is staticaly admissible. Using xii o £ any statical y admissible a, cr can be decomposed as £ O ~£ a = a + a where a belongs to S. Let us find the nonlocal elastic strain on S ; a = PRer. a can be obtained from a boundary value problem of a system of first -order ordinary differential equations: hf = -PRc^CtD - P - D gCo-°+ CPR5 ^af,y, oû ; a^CCO =0 S ' ?& £ From a, we obtain a and consequently a and we show that for £+0 we find the solution of the problem. In the thesis, it is also given an example for nonlocal elastodynamic boundary value problems. It is the problem of a moving rijid punch on a nonlocal elastic half plane. The kernel of the constitutive equation has been chosen in the form Jx'-x |a where a is the atomic distance. The speed of the punch is constant. The results have been obtained for three cases. In the first case both ends of the punch do not touch the plane, in the second case only one end indents the plane, in the third case both ends of the punch are immersed. There nowhere exists an infinite stress. DoktoraPh.D

Galactosemia: a case referring with ascites and liver failure

50. Türk Pediatri Kongresi’nde (Antalya, 26-30 Mayıs 2014) poster bildiri olarak sunulmuştuKlasik galaktozemi galaktoz-1-fosfat üridil transferaz (GALT) eksikliğine bağlı oluşur. Erken dönemde tedavi edilmeyen hastalar yenidoğan döneminden itibaren büyüme geriliği, sarılık, kanama bozuklukları, koagülopati, karaciğer fonksiyon bozuklukları ve/veya hepatomegali, katarakt, letarji, hipotoni, sepsisle başvururlar. Erken dönemde asit ile başvuran hastalar da olabilmektedir. Otuz beş günlük erkek hasta karın şişliği, tartı alamama, sarılık şikayeti ile tarafımıza başvurdu. Asiti olan ve karaciğer yetmezliği etyolojisi araştırılan hastanın yapılan tetkiklerinde idrarda redüktan madde pozitifliği, göz muayenesinde bilateral katarakt ve galaktoz-1-fosfat üridil transferaz düzeyi çok düşük saptandı. Hastaya galaktozemi tanısı kondu ve laktoz içermeyen mama sonrası tüm bulguları geriledi. Erken süt çocukluğu döneminde karaciğer yetmezliği ve asit ile başvuran hastalarda ayırıcı tanıda galaktozemi düşünülmesinin gerektiği amacıyla bu olgu sunumu yapıldı.Classic galactosemia appears due to deficiency of galactose-1-transferase (GALT). Patients who were not treated during the early phase refer by growth retardation, jaundice, hemorrhagic disorders, coagulopathy, hepatic function disorders and/or hepatomegalia, cataract, lethargy, hypotony and sepsis since newborn period. There may be patients who refer with ascites. A thirty-five day old male patient referred us because of abdominal distention, inability to gain weight. The infant had ascites and liver failure etiology was investigated; substance from reduced positivity in the urine, bilateral cataract in the eye examination and low galactose-1-phosphare uridyl transferase level were detected. The patient was diagnosed with galactosemia and all findings regressed after lactose free formula. This case report was presented to remind the necessity of consideration of galactosemia in differential diagnosis for the patients who refer by liver failure during early infancy period

Retrospective evaluation of our pediatric patients with coeliac disease

Çalışmamızın amacı Çölyak hastalığı (ÇH) tanılı hastalarımızın klinik, laboratuvar ve uzun süreli izlem bulgularını araştırmaktır. ÇH tanısı ile izlenen 2-18 yaş arasındaki çocuk hastalarımızın dosyaları retrospektif olarak incelendi. Çalışmamız süresince çölyak tanılı 159 hasta çalışmaya alındı. Çalışmamızda olgularımızın en sık başvuru yakınmalarını ishal (% 78) ve karın ağrısı (% 36) oluşturuyordu. Çölyak tanılı olgularımızın 102’sinin doku grupları çalıştırılmış olup doku gruplarına göre dağılımı incelendiğinde, % 76’sında HLA-DQ2 ve HLADQ8, % 67’sinde HLA-DQ2 ve % 25’inde de HLA-DQ8 pozitifliği gözlendi. Ancak hastalarımızın % 24’ünde ne HLA-DQ2 ne de HLADQ8 doku grupları gözlendi. Anti-dTG IgA % 78 oranında, anti-dTG IgG pozitifliği % 22 oranında gözlenmiştir. Olgularımızın izleminde klinik düzelme % 93 oranında gözlenmiş olup bunun % 95’i diyete tam olarak uyanlar idi. Çalışmamızın sonuçları, çocuklarda ÇH’nin başvuru semptomlarının en sık gastrointestinal semptomlar ve büyüme geriliği olduğunu göstermiştir. Aynı zamanda tedavide en önemli basamağın diyete uyum olduğunu göstermiştir.The aim of our study was to investigate the clinical, laboratory and long-term follow-up findings in our patients with the diagnosis of CD. The files of our pediatric patients between the ages of 2-18 years, who were followed up with CD diagnosis were retrospectively investigated. 159 patients with the diagnosis of CD were included in the study. The most common complaints at the admission were diarrhea (78%) and abdominal pain (36%). The distribution of 102 patients with the diagnosis of CD according to the tissue groups was as follows: 76% of the patients were HLA-DQ2 and HLA-DQ8 positive; 67% HLA-DQ2 and 25% HLA-DQ8 positive. However, in 24% of the patients, we observed neither HLA-DQ2 nor HLA-DQ8 tissue groups. The rate of anti-dTG IgA was 78% and the rate of positive anti-dTG IgG was 22%. During the follow-up period, in 79% of the patients, anti-dTG antibodies became negative. In 95% of these patients complied fully with the dietary recommendations. The results of our study showed that the most common symptoms at admission were gastrointestinal symptoms and growth retardation. In addition, the results also indicated that the compliance with the dietary recommendations was the most important step in the treatment

The incidence of HLA-DQ2/DQ8 in Turkish children with celiac disease and a comparison of the geographical distribution of HLA-DQ

Introduction : Celiac disease (CD) is an auto-immune enteropathy that occurs in genetically pre-disposed people as a result of the consumption of gluten-containing foods. Aim : To identify the incidence of HLA-DQ2 and HLA-DQ8 observed in children with CD. Material and methods : In this study, we focused on children ranging in age from 2 to 18 years and diagnosed with celiac disease. In our patients diagnosed with CD, in addition to tissue transglutaminase antibodies (anti-tTG), we also evaluated HLA-DQ2 B1 and HLA-DQ8 B1 alleles using the method of polymerase chain reaction (PCR)/sequence-specific oligonucleotide probes (Luminex®). The detection of 0201/0202 for HLA-DQ2 allele and 0302 for HLA-DQ8 allele was accepted as a positive result. Results : The mean age of our patients with celiac disease was 7.42 ±3.18 years, and the female/male ratio was 1.5/1. Seventy-six percent of our patients were HLA-DQ2 and/or HLA-DQ8 positive, 67% were HLA-DQ2 positive, and 25% were HLA-DQ8 positive. Nevertheless, 24% of them were HLA-DQ2 and HLA-DQ8 negative. The incidence of HLA-DQ2 in the control group was 18.8% with a significant difference compared to the HLA-DQ2 incidence in the patient group (67%) (p < 0.05). Similarly the HLA-DQ8 incidence in the control group (5.7%) was significantly lower than the incidence in the patient group (25%) (p < 0.05). Conclusions : The incidence of the patients diagnosed with CD, who are HLA-DQ2 and HLA-DQ8 negative, varies among different populations

Crohn's disease in a child with colonic stricture: A case report

Crohn Hastalığı (CH) tüm gastrointestinal sistemi transmural ve segmental olarak tutabilen multisistemik bir hastalık olup tutulum yerine göre çok çeşitli semptomlar ile hastalar başvurabilmektedir. On beş yaşında şiddetli karın ağrısı ile başvuran hastada yapılan incelemelerde sağ kolonda darlık gözlenmiş olup CH ile uyumlu saptandı. İzleminde cilde fistülize olan, karın içinde abse gelişen hastanın tedavisinde kortikosteroid, azathiopurin, mesalazin, metotreksat, infliksimab ve antibiyotik tedavisi ile düzelme sağlandı. İzlemde şikayetleri gerileyen hastanın kontrollerinde karın içi abseleri ve kolon darlığı geriledi. Crohn Hastalığında, daha çok erişkin dönemde geç dönem komplikasyonu olarak karşılaştığımız bağırsak striktürü ile prezente olan CH saptadığımız çocuk hastayı sunmak istedik.Crohn’s Disease (CD) is a multisystemic disease which may affect gastrointestinal system transmural and segmental and patients may present with any kind of symptoms. An investigation on 15-year-old patient who presented with severe abdominal pain revealed narrowing in right colon and found consistent with CD. The patient who devepoled an abcess fistulized to the skin during the follow-up showed improvement after treatment with corticosteroid, azathioprine, mesalazine, methotrexate, infliximab, and antibiotics. During follow-up, intra-abdominal abcesses and narrowing of the colon regressed along with patient’s symptoms. We wanted to present this case where our patient was diagnosed with CD after presenting with colon stricture which is more commonly seen as late stage complication in adult CD