Is decreased tissue elasticity more important than histopathological changes in ruptures of ascending aortic aneurysms?

Background: In this study, we aimed to investigate the natural properties of ascending aortic aneurysms and to compare dilated aortic tissues of patients with ascending aortic aneurysms and the non-pathological aortic tissues of cadavers. Methods: Between January 2017 and January 2020, a total of 14 patients (12 males, 2 females; mean age: 66.6±8.4 years; range, 54 to 77 years) who underwent elective ascending aortic surgery without genetic disease or family history in the etiology were included in the study. Aortic tissues taken from the patients with ascending aortic aneurysms and cadavers without any aortic pathology were compared histopathologically and biomechanically. An experienced pathologist performed a histological evaluation with appropriate staining and scoring. In the biomechanical examination, stress-strain curves were created with the uniaxial tensile test. The instantaneous elastic modulus was calculated based on the first regions of the curves (Ei) and the slopes of the linear region close to rupturing (Es). Results: In the pathological examination, there was no statistically significant difference in the parameters of both the patient and control groups (p>0.05). In the biomechanical examination, Ei values were significantly higher in the patients with ascending aortic aneurysms, while Es values were comparable between the groups (p=0.028 and p=0.609, respectively). Conclusion: Our study results showed that the tissues of the ascending aortic aneurysm were much more rigid, although no significant histopathological changes were detected. These findings are meaningful in understanding the structure of normal and pathological aortic tissue.

Modification of Surface and Subsurface Properties of AA1050 Alloy by Shot Peening.

AA1050 Al alloy samples were shot-peened using stainless-steel shots at shot peening (SP) pressures of 0.1 and 0.5 MPa and surface cover rates of 100% and 1000% using a custom-designed SP system. The hardness of shot-peened samples was around twice that of unpeened samples. Hardness increased with peening pressure, whereas the higher cover rate did not lead to hardness improvement. Micro-crack formation and embedment of shots occurred by SP, while average surface roughness increased up to 9 µm at the higher peening pressure and cover rate, indicating surface deterioration. The areal coverage of the embedded shots ranged from 1% to 5% depending on the peening parameters, and the number and the mean size of the embedded shots increased at the higher SP pressure and cover rate. As evidenced and discussed through the surface and cross-sectional SEM images, the main deformation mechanisms during SP were schematically described as crater formation, folding, micro-crack formation, and material removal. Overall, shot-peened samples demonstrated improved mechanical properties, whereas sample surface integrity only deteriorated notably during SP at the higher pressure, suggesting that selecting optimal peening parameters is key to the safe use of SP. The implemented methodology can be used to modify similar soft alloys within confined compromises in surface features.

Effects of different cadaver preservation methods on muscles and tendons: a morphometric, biomechanical and histological study.

No prior publication studying the biomechanical and histological properties of cadavers fixed with Logan or modified Logan solution (MLS) was found in the literature. It was aimed in this study to compare MLS fixation and other cadaver preservation procedures regarding the use in basic histological studies, anatomy education and surgical trainings. This study was placed on 35 male 17-week-old Wistar Albino rats. MLS fixated tissues were systematically compared with 10% formalin (F10), saturated salt solution (SSS), Thiel and frozen/thawed (FT) tissues. Organoleptic (color, appearance, flexibility, odor, etc.), morphometric (e.g. length, width and cross-sectional area), biomechanical (Young's modulus, stiffness, maximum load, etc.) and histological (tendon and muscle fiber integrity, nuclear prominence, blur in microscopy, etc.) analyses were conducted. Organoleptic properties of Thiel and SSS fixated muscles and tendons were better preserved than F10 and MLS. No significant difference was observed in gross morphometric properties (e.g. length, width and cross sectional area) following any of the cadaver and tissue preservation techniques. MLS and F10 was observed to increase the stiffness, Young's modulus and maximum load parameters of the tendons. Thiel and SSS fixated tendons had similar mechanical properties to fresh and FT tendons. No effect of fixation solutions on tendons is observed in the histological analysis regarding fiber integrity, nuclear prominence, blur in microscopy, shrinkage of tissues. Thiel solution was observed to distort fiber integrity, nuclear prominence and blur the microscopy of muscle tissue. Thiel and SSS fixated muscles and tendons were observed to absorb more stain with Masson's trichrome staining and appear as darker red. No muscle and tendon shrinkage due to fixative solutions was observed with our fixation method. Pondering the organoleptic (color, appearance, consistency, odor, etc.) and biomechanical analyses (stiffness, Young's modulus, etc.), Thiel and SSS fixed cadavers are more suitable for purposes as surgical trainings and development of new surgical procedures. However, the change in the micro-anatomical structure of the muscles, especially with the Masson's trichrome staining, caused by these two solutions should not be overlooked.

Effectiveness of Intraductal Meibomian Gland Probing for Obstructive Meibomian Gland Dysfunction.

PURPOSE: To evaluate the short-term effectiveness of intraductal meibomian gland probing using modified Maskin cannulas in patients with obstructive meibomian gland dysfunction. METHODS: The study prospectively included 58 eyes of 30 patients with a diagnosis of meibomian gland dysfunction who were refractory to medical treatment for at least 6 months. The patients were divided into 4 groups according to the number of probing procedures applied. During probing, sterile modified Maskin probes 2, 2.5, 4, and 6 mm in length were used. A tarsal massage was recommended after medical treatment. Preoperatively, then postoperatively at 1 week, 1 month, and 3 months, the Schirmer 1 test was performed, tear break-up time was measured, and images of the anterior segment were recorded. In addition, the Ocular Surface Disease Index questionnaire was completed at baseline and at 3 months. RESULTS: In all groups, there were no statistically significant differences between Schirmer 1 test results at preoperative and postoperative 3 months, but tear break-up time values measured at baseline and at 3 months differed significantly (5 seconds, 13 seconds, P < 0.001). In the analyses of anterior segment photographs of all patients, statistically significant postprocedural decreases in conjunctival hyperemia (P < 0.0001) and eyelid margin vascularization (P = 0.004) were detected, and the later Ocular Surface Disease Index scores showed a significant improvement between preop and 3 months. CONCLUSIONS: A procedure using modified Maskin probes was effective and reliable in the short term for patients with meibomian gland dysfunction.

Riluzole- and Resveratrol-Induced Delay of Retinal Ganglion Cell Death in an Experimental Model of Glaucoma.

PURPOSE: To evaluate the effects of the neuroprotective agents riluzole and resveratrol on the survival of retinal ganglion cells (RGCs) when administered alone or in combination. MATERIALS AND METHODS: Experimental glaucoma was induced by injecting hyaluronic acid into the anterior chamber of Wistar albino rats weekly for a six-week period. Intraocular pressure was measured before and immediately after glaucoma induction. The neuroprotective effects of daily intraperitoneal injections of riluzole (8 mg/kg) and resveratrol (10 mg/kg) were evaluated and compared. After the six-week period, dextran tetramethylrhodamine was applied into the optic nerve and the density of surviving RGCs was evaluated by counting the labeled RGCs in whole mount retinas for retrograde labeling of RGCs. RESULTS: The mean numbers of RGCs were significantly preserved in all treatment groups compared to the vehicle-treated glaucoma group (G). The mean number of RGCs in mm(2) were 1207 ± 56 in the control group (C), 404 ± 65 in G group, 965 ± 56 in riluzole-treated group in the early phase of glaucoma (E-Ri), 714 ± 25 in riluzole-treated group in the late phase of glaucoma (L-Ri), 735 ± 29 in resveratrol-treated group in the early phase of glaucoma (E-Re), 667 ± 20 in resveratrol-treated group in the late phase of glaucoma (L-Re), and 1071 ± 49 in riluzole and resveratrol combined-treated group in the early phase of glaucoma (E-RiRe group). CONCLUSIONS: When used either alone or in combination, both riluzole and resveratrol, two agents with different mechanisms of action in glaucoma, significantly delayed RGC loss in this study's experimental glaucoma model.

Effects of botulinum toxin A on fracture healing in rats: an experimental study.

INTRODUCTION: Fracture healing is a complex process influenced by intrinsic and extrinsic factors. The aim of the present study was to evaluate the effects of botulinum toxin (BTX) A on fracture healing. MATERIALS AND METHODS: Following the induction of bilateral standard closed femoral fractures and relative fixation in 18 Wistar albino rats, 8 IU of BTX A were injected into the right femoral region. After 28 days, all of the rats were sacrificed, the diameter of the callus was measured, and fracture healing was assessed by biomechanical and histopathologic evaluation. RESULTS: While an increase in biomechanical and histopathologic healing was noted on the side injected with BTX A, a decrease in callus diameter was observed. CONCLUSION: Botulinum toxin A administration increases the healing power in a relatively fixated fracture and decreases the callus diameter, just as if rigid fixation had been performed. The beneficial effect of BTX A on fracture healing might be associated with increased fixation rigidity.

Comparison of tumor marker CA 242 with CA 19-9 and carcinoembryonic antigen (CEA) in pancreatic cancer.

BACKGROUND/AIMS: Although there are a variety of tumor markers used for diagnosis of pancreatic carcinoma, the sensitivity and specificity of those markers have not yet reached an ideal level. The aim of this study was to compare the diagnostic value of CA 242 with CA 19-9 and CEA in the patients with pancreatic cancer. METHODOLOGY: Serum CA 242, CA 19-9 and CEA levels were determined in 135 subjects in the following groups: Pancreatic cancer (n = 40), cholangiocellular carcinoma (n = 15), hepatocellular carcinoma (n = 10), cirrhosis (n = 7), chronic active hepatitis (n = 7), choledochal stone (n = 12), chronic pancreatitis (n = 9), acute pancreatitis (n = 6), and healthy controls (n = 29). RESULTS: An elevated serum CA 242 concentration (> 20 U/mL) was found in 30 out of 40 (70%) (mean; 2163 +/- 838 U/mL) patients with pancreas cancer, in 11 out of 15 patients with cholangiocellular carcinoma (93.3%) (mean 916 +/- 529 U/mL), in none of patients with hepatocellular carcinoma and healthy controls. Slightly elevated CA 242 concentration was found in 6 out of 41 patients with benign hepatobiliary and pancreatic disease (range 0.4-97.8 U/mL) (1 acute pancreatitis, 2 chronic pancreatitis, 1 cirrhosis, 2 choledochal stone). Mean serum CA 242, CA 19-9 and CEA levels of the pancreas cancer group were significantly higher than those of the other groups except the cholangiocellular carcinoma group. There was no significant difference between the stage of pancreas cancer regarding mean serum CA 242, CA 19-9 and CEA level. There was positive correlation between serum CA 242 and CA 19-9 level. In the pancreas cancer, the sensitivity of CA 242, CA 19-9 and CEA was 75%, 80%, 40%, respectively and the specificity of those markers was 85.5%, 67.5% and 73%, respectively. CONCLUSIONS: In conclusion, the advantage of CA 242 compared to CA 19-9 is that its specificity is higher than that of CA 19-9 in the diagnosis of pancreas cancer.