Gene amplifications and extrachromosomal circular DNAs: function and biogenesis.

Gene amplification is an increase in the copy number of restricted chromosomal segments that contain gene(s) and frequently results in the over-expression of the corresponding gene(s). Amplification may be found in the form of extrachromosomal circular DNAs (eccDNAs) or as linear repetitive amplicon regions that are integrated into chromosomes, which may form cytogenetically observable homogeneously staining regions or may be scattered throughout the genome. eccDNAs are structurally circular and in terms of their function and content, they can be classified into various subtypes. They play pivotal roles in many physiological and pathological phenomena such as tumor pathogenesis, aging, maintenance of telomere length and ribosomal DNAs (rDNAs), and gain of resistance against chemotherapeutic agents. Amplification of oncogenes is consistently seen in various types of cancers and can be associated with prognostic factors. eccDNAs are known to be originated from chromosomes as a consequence of various cellular events such as repair processes of damaged DNA or DNA replication errors. In this review, we highlighted the role of gene amplification in cancer, the functional aspects of eccDNAs subtypes, the proposed biogenesis mechanisms, and their role in gene or segmental-DNA amplification.

Optimization of Micro-Drilling of Laminated Aluminum Composite Panel (Al-PE) Using Taguchi Orthogonal Array Design.

Aluminum Matrix Composite (AMC) represents an innovative class of materials that is extensively utilized in industries such as automotive, defense, aerospace, structural engineering, sports, and electronics. This study investigates the thrust force, exit burr formation, changes in the micro-tool, and drilled hole diameters during the micro-drilling of an aluminum-polyethylene composite panel (Al-PE). The panel consists of 3501 series aluminum skin materials bonded to a polyethylene (PE) core. Micro-drilling test parameters were designed using Taguchi's L16 (42 23) orthogonal array. Tests were conducted with five control parameters: cutting speed with four levels (10 m/min, 20 m/min, 30 m/min, 40 m/min), feed rate with four levels (0.5 µm/rev, 1 µm/rev, 2 µm/rev, 4 µm/rev), the tool diameter with two levels (0.7 mm, 1 mm), and tool point angle with two levels (100°, 140°) using both AlTiN-coated and uncoated drills. The maximum thrust force (Fz), maximum burr height, and changes in both the drill tool and hole diameters were measured for analysis of variance (ANOVA). The results showed that, in terms of impact on Fz, tool point angle had the highest positive influence (64.54%) on the micro-drill at the entrance of composite (upper aluminum plate). The cutting speed had the highest positive influence (45.32%) on the tool in the core layer (PE core layer). The tool point angle also had the highest positive influence (68.95%) on the micro-drill at the lower layer of the composite (the lower aluminum plate). There was noticeable chip adhesion on the major cutting edge and nose area under micro-drilling conditions with higher thrust forces and burr height. The AlTiN coating had a positive effect on tool wear and hole diameter deviations, but it adversely affected the burr height.

The Reality of Hypoparathyroidism After Thyroidectomy: Which Risk Factors are Effective? Single-Center Study.

Objectives: One of the most common complications of thyroidectomy is hypoparathyroidism and that complication has a multifactorial etiology. The etiology of post-operative hypoparathyroidism is multifactorial, some factors affecting hypoparathyroidism have been revealed in the literature, and there are some conflicting results about this complication. In the present study, we aimed to evaluate pre-operative and intraoperative factors affecting development of hypoparathyroidism. Methods: Data of 542 patients underwent thyroidectomy±central dissection (±lateral dissection) and whose post-operative parathormone values could be obtained, between 2012 and 2020 were collected prospectively and evaluated retrospectively. A parathyroid hormone (PTH) value of <15 pg/mL at the post-operative 4th h was defined as hypoparathyroidism, and a calcium (Ca) value of <8 mg/dl on the 1st post-operative day was defined as biochemical hypocalcemia. Patients were divided into two groups as post-operative hypoparathyroidism (Group 1) and non-hypoparathyroidism (Group 2). In addition, PTH value below the reference value at the post-operative 6th month and/or still needing calcium treatment was defined as permanent hypoparathyroidism. Demographic data of the patients, pre-operative biochemical values, surgical indications, intraoperative findings, post-operative 4th h PTH values, post-operative 1st day calcium values, and pathological examination of the specimen whether there was an unintenionally resected parathyroid gland or not were evaluated as risk factors for hypoparathyroidism. A logistic regression model was used to determine independent risk factors for the development of hypoparathyroidism. Results: Hypoparathyroidism was determined in 124 (22.9%) and hypocalcemia was determined in 120 (22.1%) patients. According to 6-month follow-up period; 110 (20.3%) patients were transient, 7 (1.3%) patients were permanent, and 7 (1.3%) patients data could not be obtained. The hypocalcemia rate was higher in Group 1 (39.3% vs. 14.3%, p<0.0001), also the post-operative 1st day calcium values were lower (8.2+0.7 mg/dl vs. 8.5+0.6 mg/dl; p=0.000). The rate of parathyroid autotransplantation, the rate of parathyroid gland in pathological specimen, and the rate of central dissection were significantly higher in Group 1 compared to group 2 (15.8% vs. 8%; p=0.006; 20% vs. 10.6%; p=0.003; 16.4% vs. 5.3%, p<0.0001, respectively). The difference between the two groups was significant in terms of the number of remaining parathyroids, and the rate of the number of patients with four remaining parathyroids in place was higher in Group 2 than in Group 1 (84.1% vs. 67.9; p=0.000). In the logistic regression analysis, only central dissection is an independent risk factor affecting the development of hypoparathyroidism, and central dissection increases the risk of hypoparathyroidism approximately 2.3 times (p=0.014; OR: 2.336). The other factors were not determined as independent risk factor. Conclusion: Performing central neck dissection with total thyroidectomy may increase the risk of hypoparathyroidism development. The risk of hypoparathyroidism should be considered when evaluating the indications and dissection extent in the central dissection. Maximum effort should be made to preserve the parathyroid glands and their vascularization during central dissection, and if there is a removed parathyroid gland, it should be autotransplanted.

[Comparison of rhinomanometry results with polysomnography and physical examination findings in patients with obstructive sleep apnea syndrome]. / Obstrüktif uyku apnesi sendromlu hastalarda rinomanometri sonuçlarinin polisomnografi ve fizik muayene bulgulari ile karsilastirilmasi

OBJECTIVES: This study aims to investigate the effects of anterior rhinomanometry-induced nasal resistance on obstructive sleep apnea syndrome (OSAS) patients. PATIENTS AND METHODS: Between May 2011 and September 2011, 100 volunteer patients (76 males, 24 females; mean age 47.6±11.6 years; range 20 to 71 years) who were admitted with complaints of snore, breathing pauses told by their partners, oversleep mood in a daytime and fatigue and diagnosed with OSAS by polysomnography with simple snore were included. Anterior rhinomanometry was applied for all patients and nasal resistance was estimated. Mallampati index and body mass index (BMI) of patients was calculated. The mean apnea-hypopnea index (AHI) and minimum oxygen saturation values were measured. RESULTS: There was no significant relationship between nasal resistance and AHI. However, a significant relationship between AHI and Mallampati and BMI values was observed. The AHI values increased, as the Mallampati and BMI values increased. CONCLUSION: Our study results show that nasal resistance has no significant effect on AHI and minimum oxygen saturation in OSAS patients.

Idiopathic true brachial artery aneurysm in a nine-month infant.

Upper extremity peripheral artery aneurysms are a rarely encountered arterial disorder. Brachial artery aneurysms seen in the pediatric age group are generally trauma resultant. A nine-month-old male infant patient presented with complaints of an asymptomatic mass in the arm. Following Doppler ultrasonography and magnetic resonance imaging (MRI) examinations, saccular aneurysm, originating from the left brachial artery was diagnosed in the patient without history of trauma. The aneurysm was resected by surgical intervention, and primary repair of the brachial artery was performed by end-to-end anastomosis. No complication was observed during the follow-up. Surgical intervention for upper extremity aneurysms should be initiated without delay in order to prevent extremity ischemia and amputation.