Homojen Olmayan Elastik Konik Bir Kabuğun Üniform Olmayan Yanal Dış Basınç Yükü Etkisi Altında Stabilitesi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2008Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2008Bu çalışmada homojen olmayan elastik kesik konik bir kabuğun uniform olmayan yanal basınç yükü etkisi altında stabilitesi incelenmiştir. Çalışmada, basit mesnetli homojen olmayan elastik malzemelerden oluşan konik kabukların temel bağıntıları çıkarılmış, değiştirilmiş Donnell tipi stabilite ve deformasyon uygunluk denklemleri elde edilmiş ve bu denklemlere Galerkin yöntemi uygulanarak uniform olmayan yanal basınç yükü için analitik ifade elde edilmiştir. Elde edilen ifade çevresel dalga sayısına göre minimize edilerek uniform olmayan kritik yanal basınç yükünün minimum değeri bulunmuştur. Son olarak da hesaplar yapılarak, koni parametrelerinin ve homojen olmamanın kuvvet fonksiyonu şeklinde değişiminin kritik yanal basınç yükü değerine etkileri incelenmiştir. Elde edilen ifadeler üzerine yapılan sayısal sonuçlar kaynaklardaki sonuçlarla karşılaştırılarak doğruluğu saptanmıştır.In this study, stability of a non-homogeneous elastic truncated conical shell under non-uniform lateral pressure is studied. Firstly, fundamental relations of conical shells made of nonhomogeneous elastic materials are expressed and modified Donnell type stability and compatibility equations are obtained. Then, applying Galerkin method to these equations, an analytical expression for non-uniform lateral pressure is get. Minimizing the obtained expression according to the circumferential wave number, minimum value of the non-uniform critical lateral pressure is found. Finally, making computations, the effects of the variations of conical shell parameters and non-homogeneity as power functions to the critical lateral pressure values are examined. Obtained results are compared with those in the literature and the validity of the study is established

Sonography of the bladder after ureteral reimplantation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135188/1/jum199211287.pd

Malrotation in patients with duodenal atresia: A true association or an expected finding on postoperative upper gastrointestinal barium study?

We retrospectively reviewed the imaging and surgical findings in 17 patients with duodenal atresia to determine (a) the frequency of coexistent malrotation in patients with duodenal atresia and (b) the reliability of the upper gastrointestinal barium study (UGI) in differentiating malrotation from postoperative deformity of the duodenal sweep after repair of duodenal atresia. Postoperatively, 9 (53%) of the 17 patients had UGI findings consistent with malrotation. Of these nine, only two had malrotation coexistent with duodenal atresia, while the other seven had normal midgut rotation demonstrated intraoperatively. The radiographic appearance of malrotation was simulated in two patients in whom the ligament of Treitz had been surgically divided, in three in whom the ligament had not been taken down, and in two in whom the status of the ligament was not specified in the surgical report. Although there is an association between duodenal atresia and malrotation, this cannot be accurately documented on postoperative UGI examination. Malrotation cannot be detected preoperatively because contrast material cannot pass beyond the level of the atresia. Postoperatively, surgical deformity of the duodenal sweep cannot be reliably distinguished from malrotation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46705/1/247_2005_Article_BF02012180.pd

Mini craniotomy for chronic subdural haematoma: surgical outcome from a single institution experience and predictors of success

Background: Chronic subdural hematoma (CSDH) is an increasingly common neurological disease in daily neurosurgical practice. Despite the wide prevalence of CSDH, there remains a lack of consensus regarding numerous aspects of its surgical management. The diagnosis and treatment are well established but there are different surgical procedures and outcome related to these procedures are not completely understood.Methods: The study conducted was conducted in department of neurosurgery at Ibrahim cardiac hospital and research institute, Dhaka, Bangladesh between January 2019 to July 2020, 105 patients were treated for chronic subdural haematoma This study evaluated the clinical features, radiological findings and surgical outcome by mini craniotomy assessed by modified Rankin scale (mRS) score and Glasgow outcome scale (GOS) score in a large series of patients treated at single institution.Results: At 6 months follow up, only one patient died (0.95%) because of co-morbidities and not directly related to the chronic subdural haematoma, 15 patients (14.3%) improved to mRS 0, 33.33% showed only mild symptoms without any significant disability-mRS 1, slight disability was observed in 28.5% patients, moderate disability was observed in 17.14% patients-mRS 3, moderately severe disability was observed in 5.7%-mRS 4.Conclusions: GOS score at 6 months follow up which shows majority of the patient improved to GOS score 4 (45.71%) and 5 (38.09%). Based on these results, among various method of surgical management, mini craniotomy provides better outcome

Testicular infarction in the newborn: Ultrasound findings

Three patients with neonatal testicular torsion and infarction (two bilateral, one unilateral) are presented with a distinctive sonographic appearance. All five testes appeared inhomogeneously hypoechoic and each was surrounded by a brightly echogenic rim. Whereas surgical exploration was required in the past to establish the diagnosis of testicular infarction in the neonate, sonographic demonstration of the abnormality in the appearance of the testicular parenchyma permits nonoperative diagnosis. Because surgical salvage of the testis in the setting of neonatal extravaginal torsion is thought to be quite rare, the necessity of removing the testis is less clear when the diagnosis is established preoperatively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46692/1/247_2005_Article_BF02013166.pd

Bilateral branch pulmonary artery valve implantation in repaired tetralogy of fallot

BackgroundTranscatheter, bilateral branch pulmonary artery (PA) valve implantation is a novel treatment for patients with severe pulmonary insufficiency and oversized right ventricle (RV) outflow tract. There is scarce data on efficacy and safety of this approach.MethodsThis was a retrospective study of 8 patients with repaired tetralogy of fallot (TOF) who underwent bilateral branch PA valve implantation. Demographics, echocardiography, cardiac catheterization, and axial imaging data were reviewed. Variables were compared by a paired sample t‐test.ResultsAll patients were adult sized (weight 43–99 kg) with oversized RV outflow tract not suitable for conventional transcatheter pulmonary valve implantation. Staged bare metal PA stenting followed by valve implantation (interval 3–5 months) was technically successful in 7 patients with one stent embolization. In another patient, proximal stent migration prevented placement of bilateral pulmonary valve stents. There were a total of 14 valved branch PA stents placed (Melody valve n = 9, Sapien XT n = 2, Sapien 3 n = 3). In the 7 patients undergoing successful branch pulmonary valve placement, at median follow up of 10 months (range 3 months to 6 years), 13 (93%) valves had none/trivial insufficiency on echocardiography. Prevalve and postvalve implantation cardiac magnetic resonance imaging in five patients showed significant reduction of indexed RV end‐diastolic volume (152 ± 27 to 105 ± 15 mL/m2, P < .001).ConclusionsTranscatheter, bilateral branch PA valve implantation was technically feasible with satisfactory efficacy and safety in patients with repaired TOF, severe pulmonary insufficiency, and oversized RV outflow tracts. Elimination of pulmonary insufficiency with this method resulted in reduced RV end‐diastolic volume. This approach can be offered as an alternative to surgery, particularly in patients considered high risk for standard surgical placement and who are not candidates for the newer self‐expanding valve prosthesis for placement in RV outflow tracts larger than 30 mm diameter.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143803/1/ccd27489.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143803/2/ccd27489_am.pd

“Dilatation” of the left renal vein on computed tomography in children: A normal variant

Compression of the left renal vein (LRV) between the superior mesenteric artery and the aorta is thought to be a cause of hematuria, periureteral and gonadal varices, and varicocele (“Nutcracker phenomenon”). Previous investigators have suggested that this diagnosis can be made on computed tomography when the LRV ratio ≥1.5 (the diameter of the LRV proximal to the aorto-mesenteric angle divided by the diameter of the LRV distal to the aorto-mesenteric angle). This study was designed to establish the normal range for the LRV ratio on CT in children. The LRV ratio was measured in thirty-nine consecutive children undergoing intravenously enhanced CT of the abdomen. None of the children had hematuria on urinalysis immediately before or after the CT. Children with any known abnormality involving the kidneys, adrenal glands, IVC, or renal or gonadal veins were excluded. The patients ranged in age from 3.4 to 18.5 years (mean=10.6 years). LRV ratio ranged from 0.78 to 2.00 (mean=1.46; S.D.=0.312). Twenty of the 39 children (51.3%) had a LRV ratio ≥1.50. The conclusion is that the normal range for the LRV ration is too wide for it to be useful in diagnosing LRV entrapment and that a LRV ratio ≥1.5 on CT is normal in children.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46695/1/247_2005_Article_BF02018620.pd

Determining the role of novel metabolic pathways in driving intracranial pressure reduction after weight loss

Idiopathic intracranial hypertension, a disease classically occurring in women with obesity, is characterised by raised intracranial pressure. Weight loss leads to reduction in intracranial pressure. Additionally, pharmacological glucagon-like peptide-1 agonism reduces cerebrospinal fluid secretion and intracranial pressure. The potential mechanisms by which weight loss reduces intracranial pressure are unknown and was the focus for this study.Meal stimulation tests (fasted plasma sample, then samples at 15, 30, 60, 90 and 120 minutes following a standardised meal) were conducted pre- and post-bariatric surgery (early (2 weeks) and late (12 months)) in patients with active idiopathic intracranial hypertension. Dynamic changes in gut neuropeptides (glucagon-like peptide-1, gastric inhibitory polypeptide, and ghrelin) and metabolites (untargeted ultra-high performance liquid chromatography-mass spectrometry) were evaluated. We determined the relationship between gut neuropeptides, metabolites, and intracranial pressure.18 idiopathic intracranial hypertension patients were included (Roux-En-Y gastric bypass n=7, gastric banding n=6, or sleeve gastrectomy n=5). At 2 weeks post-bariatric surgery, despite similar weight loss, Roux-En-Y gastric bypass had a two-fold (50%) greater reduction in intracranial pressure compared to sleeve. Increased meal stimulated glucagon-like peptide-1 secretion was observed after Roux-En-Y gastric bypass (+600 %) compared to sleeve (+319 %). There was no change in gastric inhibitory polypeptide and ghrelin. Dynamic changes in meal stimulated metabolites after bariatric surgery consistently identified changes in lipid metabolites, predominantly ceramides, glycerophospholipids and lysoglycerophospholipids, which correlated with intracranial pressure. A greater number of differential lipid metabolites were observed in the Roux-En-Y gastric bypass cohort at 2 weeks, and these also correlated with intracranial pressure.In idiopathic intracranial hypertension, we identified novel changes in lipid metabolites and meal stimulated glucagon-like peptide-1 levels following bariatric surgery which were associated with changes in intracranial pressure. Roux-En-Y gastric bypass was most effective at reducing intracranial pressure despite analogous weight loss to gastric sleeve at 2 weeks post-surgery and was associated with more pronounced changes in these metabolite pathways. We suggest that these novel perturbations in lipid metabolism and glucagon-like peptide-1 secretion are mechanistically important in driving reduction in intracranial pressure following weight loss in patients with idiopathic intracranial hypertension. Therapeutic targeting of these pathways, for example with glucagon-like peptide-1 agonist infusion, could represent a therapeutic strategy

Biallelic TMEM260 variants cause truncus arteriosus, with or without renal defects

Only two families have been reported with biallelic TMEM260 variants segregating with structural heart defects and renal anomalies syndrome (SHDRA). With a combination of genome, exome sequencing and RNA studies, we identified eight individuals from five families with biallelic TMEM260 variants. Variants included one multi-exon deletion, four nonsense/frameshifts, two splicing changes and one missense change. Together with the published cases, analysis of clinical data revealed ventricular septal defects (12/12), mostly secondary to truncus arteriosus (10/12), elevated creatinine levels (6/12), horse-shoe kidneys (1/12) and renal cysts (1/12) in patients. Three pregnancies were terminated on detection of severe congenital anomalies. Six patients died between the ages of 6 weeks and 5 years. Using a range of stringencies, carrier frequency for SHDRA was estimated at 0.0007–0.007 across ancestries. In conclusion, this study confirms the genetic basis of SHDRA, expands its known mutational spectrum and clarifies its clinical features. We demonstrate that SHDRA is a severe condition associated with substantial mortality in early childhood and characterised by congenital cardiac malformations with a variable renal phenotype

Intravesical oxybutinin chloride in children with intermittent catheterization: Sonographic findings

The sonographic findings in the bladder are presented in four children with myelomeningocele and neurogenic dysfunction of the bladder, who were treated with intermittent self-catheterization and intravesical oxybutinin chloride. All were referred for routine sonography of the urinary tract. Each had infused a crushed tablet of oxybutinin chloride intravesically 30–120 min before the examination. In two children, brightly echogenic, non-shadowing particles were suspended in the bladder urine. In one of these, the particles swirled giving the impression of a “snowstorm”; in the other, most of the particles gradually settled forming an irregular clump on the bladder base. In the remaining two children, the urine appeared diffusely hazy with innumerable tiny particles giving the impression of a fine mist filling the bladder. The sonographic appearance of the urine in the bladder after intravesical instillation of crushed tablets can be dramatic and can simulate pus, blood, fungus, or other debris in the bladder lumen. In the absence of clinical symptoms or hematuria, a history of recent infusion of medication into the bladder should be sought.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46706/1/247_2005_Article_BF02012126.pd