Mechanical Properties of Natural Chitosan/Hydroxyapatite/Magnetite Nanocomposites for Tissue Engineering Applications

Chitosan (CS), hydroxyapatite (HA), and magnetite (Fe3O4) have been broadly employed for bone treatment applications. Having a hybrid biomaterial composed of the aforementioned constituents not only accumulates the useful characteristics of each component, but also provides outstanding composite properties. In the present research, mechanical properties of pure CS, CS/HA, CS/HA/magnetite, and CS/magnetite were evaluated by the measurements of bending strength, elastic modulus, compressive strength and hardness values. Moreover, the morphology of the bending fracture surfaces were characterized using a scanning electron microscope (SEM) and an image analyzer. Studies were also conducted to examine the biological response of the human Mesenchymal Stem Cells (hMSCs) on different composites. We conclude that, although all of these composites possess in-vitro biocompatibility, adding hydroxyapatite and magnetite to the chitosan matrix can noticeably enhance the mechanical properties of the pure chitosan

Relation between chronic urticaria and thyroid autoimmunity

AbstractBackground and Purpose: chronic urticaria is a tormenter and does not have a known etiology. Association between chronic urticaria and thyroid auto-immunity has shown different results. The aim of this study is to evaluate the effect of Levo-thyroxine on the chronic urticaria and association between chronic urticaria with thyroid auto-immunity.Materials and Methods: In a prospective case-control study, we compared the frequency of thyroid auto antibodies in 60 patients (all females, with exception of six males, ages 15 to 60 years) with chronic urticaria and compared with 60 mached age healthy volunteers. All cases with chronic urticaria and control group were normal CBC, antinuclear antibodies, rheumatoid factors, complement, stool exam, liver function test (LFT), kidney function and skin prick test, prior to being referred to us. We performed thyroid auto antibodies, thyroid hormones and IgE antibodies before treating all subjects. Half of them with positive anti-thyroid antibody (n=11), received Levo-thyroxine (100 μg) daily for 1 month and the remaining half (n=11) were control group.Results: The frequency of thyroid auto antibodies was significantly higher in patients with chronic urticaria than in healthy control (36.6% vs. 9%; p<0.01).() All patients were euthyroid, however, one was found to have increased anti-thyroid antibody levels with sub clinical hypothyroidism (TSH increased, low T4). Total serum IgE increased in ten cases of patients group (16.6%) compared with six control groups (10%). Nine patients (40%) had complete response, five patients (30%) had partial response and five patients (30%) did not show any response to treatment compared with control group, in which complete and partial resolution was 30% and others with no resolution.Conclusion: chronic urticaria may be associated with thyroid disorders (positive anti- thyroid antibodies) despite normal thyroid function test. For chronic urticaria despite increase serum IgE level with unknown origin, must be evaluated by a thyroid function test, along with anti -thyroid antibodies and treatment if necessary.Key words: Anti-thymoglobulin; Antiperoxidase; Chronic urticaria, Levo-thyroxineJ Mazand Univ Med Sci 2008; 18(63): 66-72 (Persian

The effects of acupressure on pain severity in female nurses with chronic low back pain

Background: Low back pain causes physical and psychological impacts among nurses. This study aimed to investigate the effects of acupressure on the severity of pain in chronic low back pain in female nurses. Materials and Methods: This study is a single-blinded randomized clinical trial conducted among 50 nurses suffering from chronic low back pain. After simple sampling, participants were randomly assigned into acupressure and sham groups using lottery method (25 patients in each group). In the experimental group, the intervention was performed by the researcher three times a week throughout a 3-week period. The sham group received placebo interventions. Data was collected through VAS questionnaire before, immediately after, 2 weeks, and 4 weeks after performing intervention. Data analysis was conducted using SPSS version 18 using descriptive and inferential statistical methods. Results: There was no significant difference in the mean pain severity scores in the pre-interventions phase between the groups (P = 0.63), however, a significant difference was observed Immediately, 2 weeks, and 4 weeks after performing intervention. Further, the mean pain severity scores in intervention group significantly decreased compared to the sham group (P = 0.000). Conclusions: Acupressure on specific points was proved to reduce pain. Thus, acupressure can be used as nonmedicament, inexpensive, and without side effects treatment in reducing pain

A new approach for optimizing automotive crashworthiness: concurrent usage of ANFIS and Taguchi method

Design optimization is presented for the crashworthiness improvement of an automotive body structure. The optimization objective was to improve automotive crashworthiness conditions according to the defined criterion (occupant chest deceleration) during a full frontal impact. The controllable factors used in this study consisted of six internal parts of the vehicle&#039;s frontal structure in a condition that their thickness was the &quot;design parameter&quot;. First using the Taguchi method, this study analyzed the optimum conditions in discontinuous design area and impact factors and their optimal levels of design objectives were obtained by analyzing the experimental results. Next to model a precise understanding of the explicit mathematical input-output relationship, fuzzy logic is utilized which make use of full factorial design set of experimental test cases resulted from Taguchi predicting formulations. Interestingly, the optimum conditions for automotive crashworthiness occurred with 2.72 % improvement in the defined crashworthiness criterion in comparison with the baseline design while selected structural parts experienced mass reduction by 8.23 %

Multiobjective crashworthiness optimization of multi-cornered thin-walled sheet metal members

Plastic deformation of structures absorbs substantial kinetic energy when impact occurs. Therefore, energy-absorbing components have been extensively used in structural designs to intentionally absorb a large portion of crash energy. On the other hand, high peak crushing force, especially with regard to mean crushing force, may lead to a certain extent and indicate the risk of structural integrity. Thus, maximizing energy absorption and minimizing peak to mean force ratio by seeking for the optimal design of these components are of great significance. Along with this analysis, the collapse behavior of square, hexagonal, and octagonal cross-sections as the baseline for designing a newly introduced 12- edge section for stable collapse with high energy absorption capacity was characterized. Inherent dissipation of the energy from severe deformations at the corners of a section under axial collapse formed the basis of this study, in which multi-cornered thin-walled sections was focused on. Sampling designs of the sections using design of experiments (DOE) based on Taguchi method along with CAE simulations was performed to evaluate the responses over a range of steels grades starting from low end mild steels to high end strength. The optimization process with the target of maximizing both specific energy absorption (SEA) and crush force efficiency (CFE), as the ratio of mean crushing load to peak load, was carried out by nonlinear infinite element analysis through LS-DYNA. Based on single-objective and multi-objective optimizations, it was found that octagonal and 12-edge sections had the best crashworthiness performance in terms of maximum SEA and CFE

The effect of gestational diabetes mellitus on sciatic nerve in adult offspring rats Efecto de la Diabetes Mellitus Gestacional Sobre el Nervio Ciático en Ratas Adultas

Gestational diabetes mellitus (GDM) is one form of diabetes affect approximately 7 of pregnancies. Diabetic peripheral neuropathy (DPN) is a common complication of diabetes that is associated with loss of nerve fibers, myelin abnormalities and significant decrease in the expression of myelin basic protein (MBP) in peripheral nerves. This study was done to determine the effect of induced diabetes during pregnancy on sciatic nerve in adult rat offspring. In this study, wistar rats' dams were allocated to control and diabetic groups. Diabetic rats were received 40 mg/kg/body weight of streptozotocin (STZ) on the first day of gestation. Six offspring of each group were randomly selected on 12 weeks postnatal and histopathological changes in their nerve tissue were examined through H&E staining and transmission electron microscopy. Furthermore, the expression of MBP in sciatic nerve was examined by immunohistochemistry. We found that the myelinated fiber number of sciatic nerve in offspring of diabetic rats was reduced compared to the controls, but this difference was not significant. The average thickness of the myelin sheath of sciatic nerve fibers in the control and GDM was 97.1±0.1 and 94.1±0.2 mm, respectively that the difference was not statistically significant. The expression of MBP protein in the myelin sheath of both groups was similar. TEM results showed that myelin sheath of diabetic offspring had not any changes compared to control. Atrophy of axons and schwannocytus (Schwann cells) alterations were not observed in diabetic offspring. Induction of diabetes during pregnancy reduced the number of nerve fibers and thickness of the myelin sheath. But it has no effect on MBP expression and schwannocytus morphology. © 2017, Universidad de la Frontera. All rights reserved

Classification of Asthma Based on Nonlinear Analysis of Breathing Pattern.

Normal human breathing exhibits complex variability in both respiratory rhythm and volume. Analyzing such nonlinear fluctuations may provide clinically relevant information in patients with complex illnesses such as asthma. We compared the cycle-by-cycle fluctuations of inter-breath interval (IBI) and lung volume (LV) among healthy volunteers and patients with various types of asthma. Continuous respiratory datasets were collected from forty age-matched men including 10 healthy volunteers, 10 patients with controlled atopic asthma, 10 patients with uncontrolled atopic asthma, and 10 patients with uncontrolled non-atopic asthma during 60 min spontaneous breathing. Complexity of breathing pattern was quantified by calculating detrended fluctuation analysis, largest Lyapunov exponents, sample entropy, and cross-sample entropy. The IBI as well as LV fluctuations showed decreased long-range correlation, increased regularity and reduced sensitivity to initial conditions in patients with asthma, particularly in uncontrolled state. Our results also showed a strong synchronization between the IBI and LV in patients with uncontrolled asthma. Receiver operating characteristic (ROC) curve analysis showed that nonlinear analysis of breathing pattern has a diagnostic value in asthma and can be used in differentiating uncontrolled from controlled and non-atopic from atopic asthma. We suggest that complexity analysis of breathing dynamics may represent a novel physiologic marker to facilitate diagnosis and management of patients with asthma. However, future studies are needed to increase the validity of the study and to improve these novel methods for better patient management