The maintenance effect of β-amyloid injection in the CA1 region of hippocampus on learning and spatial memory in adult male rats

Background: Alzheimer’s disease is one of the most common neurodegenerative diseases that lead to the progressive loss of mental, behavioral and learning abilities. The aim of this study was to investigate the maintenance effect of β-amyloid1-42 (Aβ) injection in the CA1 region of hippocampus on learning and spatial memory of adult male rats using the Morris water maze test. Materials and Methods: In this study, 42 adult male Wistar rats were randomly divided into control (intact), sham (Aβ solvent) and Aβ-injected groups (5 μg/μl). The β-amyloid and its solvent were bilaterally injected into the CA1 region of rats' hippocampus. The first recipient group of Aβ and its solvent after 6, the second group after 11 and the third groups after 31 days were trained by the Morris water maze test. Results: During 4 training days and also in probe and visible tests, there was no significant difference between control and sham groups. The results of the learning steps in Aβ groups showed that traveled distance and escape latency to find the hidden platform was significantly increased compared with the sham groups, but there was no significant difference in the probe and visible tests between these groups. Conclusion: It seems that long exposure to Aβ can lead to more memory and learning loss in animals with Alzheimer

Evaluation of the Suitability of Kinetic Chromogenic LAL Assay for Determination of Endotoxin Levels in Heparin Sodium Injection

 Determination of the levels of endotoxins in injectable products has always been one of the concerns of regulatory authorities and manufacturers. Since a number of pharmaceuticals interfere with the LAL test to some degree, overcoming the inhibition or enhancement properties of a product is required as part of the validation of the LAL test for use in the final release testing of parenteral products. In this study, interference profile of Heparin injection in quantitative chromogenic LAL test was evaluated and the method of overcoming was investigated and validated. The results indicate that dilution as the most widely used technique for overcoming interference could not eliminate LAL interference in the aforementioned medicinal product. The inhibitory nature of heparin occurs due to its anticoagulant properties and can be overcome by using divalent cations such as magnesium. Three concentrations of magnesium chloride were evaluated for elimination of heparin’s inhibitory effect. All three concentrations studied (5, 10 and 25 mM) could effectively eliminate the inhibitory effects of heparin. Hence, one-way analysis of variance was used to determine statistically significant differences between these three concentrations. The results of ANOVA statistical method showed the optimal recovery of spiked endotoxin was at a concentration of 10 mM of magnesium chloride. In consequence, chromogenic LAL test using 10 mM of magnesium chloride as diluent could be a validated method of choice for heparin LAL assay.Highlights Bacterial endotoxins are important contaminants associated with injectable pharmaceuticals.Kinetic chromogenic LAL assay was used as the method to determine endotoxin levels in heparin injections.Selectivity, linearity and repeatability of the endotoxin chromogenic method was validated

An Approach to Elastoplasticity at Large Deformations

Finite plasticity theories are still a subject of controversy and lively discussions. Among the approaches to finite elastoplasticity two became especially popular. The first, implemented in the commercial finite element codes, is based on the introduction of a hypoelastic constitutive law and the additive elastic-plastic decomposition of the deformation rate tensor. Unfortunately, the use of hypoelasticity may lead to a nonphysical creation or dissipation of energy in a closed deformation cycle. In order to replace hypoelasticity with hyperelasticity the second popular approach based on the multiplicative elastic-plastic decomposition of the deformation gradient tensor was developed. Unluckily, the latter theory is not perfect as well because it introduces intermediate plastic configurations, which are geometrically incompatible, non-unique, and, consequently, fictitious physically. In the present work, an attempt is made to combine strengths of the described approaches avoiding their drawbacks. Particularly, a tensor of the plastic deformation rate is introduced in the additive elastic-plastic decomposition of the velocity gradient. This tensor is used in the flow rule defined by the generalized isotropic Reiner-Rivlin fluid. The tensor of the plastic deformation rate is also used in an evolution equation that allows calculating an elastic strain tensor which, in its turn, is used in the hyperelastic constitutive law. Thus, the present approach employs hyperelasticity and the additive decomposition of the velocity gradient avoiding nonphysical hypoelasticity and the multiplicative decomposition of the deformation gradient associated with incompatible plastic configurations. The developed finite elastoplasticity framework for isotropic materials is specified to extend the classical -theory of metal plasticity to large deformations and the simple shear deformation is analyzed

The maintenance effect of β-amyloid injection in the CA1 region of hippocampus on learning and spatial memory in adult male rats

Background: Alzheimer’s disease is one of the most common neurodegenerative diseases that lead to the progressive loss of mental, behavioral and learning abilities. The aim of this study was to investigate the maintenance effect of β-amyloid1-42 (Aβ) injection in the CA1 region of hippocampus on learning and spatial memory of adult male rats using the Morris water maze test. Materials and Methods: In this study, 42 adult male Wistar rats were randomly divided into control (intact), sham (Aβ solvent) and Aβ-injected groups (5 μg/μl). The β-amyloid and its solvent were bilaterally injected into the CA1 region of rats' hippocampus. The first recipient group of Aβ and its solvent after 6, the second group after 11 and the third groups after 31 days were trained by the Morris water maze test. Results: During 4 training days and also in probe and visible tests, there was no significant difference between control and sham groups. The results of the learning steps in Aβ groups showed that traveled distance and escape latency to find the hidden platform was significantly increased compared with the sham groups, but there was no significant difference in the probe and visible tests between these groups. Conclusion: It seems that long exposure to Aβ can lead to more memory and learning loss in animals with Alzheimer

Comparison of Implicit Motor Sequence Learning in Children with and without Developmental Coordination Disorder

Introduction: This study was performed to compare the implicit motor sequence learning in children with and without developmental coordination disorder. Materials and Methods: To compare the implicit motor learning, serial reaction time task (SRT) was designed and used in C++ programming environment. In this study, 24 participated children were divided into two equal groups of with and without developmental coordination disorder; they practiced 10 blocks of SRT task during the two days with an interval of 24 hours. At the beginning of the test, no explanation was given to learners about the appearance of stimuli and motor learning took place implicitly. Data were analyzed using independent-t and ANOVA tests. Results: There was no significant difference between the two groups of children with and without developmental coordination disorder in speed (P = 0.235) and precision (P = 0.072) components. However, comparing the between subjects effects during blocks of motor sequence acquisition phase (indicating) significant differences between children with and without developmental disorder in both speed and accuracy variable (P > 0.001). Conclusion: Although children with developmental coordination disorder have difficulties in acquisition and learning of everyday motor skills, their implicit motor sequence is intact. Therefore, in the process of teaching and rehabilitation of children with developmental coordination disorder, we can take advantage from implicit learning

Block of 5-HT 2 Receptors Enhances Hippocampal Long-Term Potentiation

ABSTRACT The effect of endogenous serotonin on long-term potentiating (LTP) in region CA 1 was studied by blocking 5-HT 2 receptors with ketanserin in rat hippocampal slices. Such a block significantly enhanced long-term potentiation of the CA 1 population spike induced by high frequency stimulation of the schaffer collateral/ commissural pathway. This implies that serotonin acts on 5-HT 2 receptors in CA 1 to repress long-term potentiation

Protein Kinase C Involvement in Neuroprotective Effects of Thymol and Carvacrol Against Toxicity Induced by Amyloid-β in Rat Hippocampal Neurons

Introduction: We have reported that thymol and carvacrol can improve cognitive abilities in Alzheimer Disease (AD) rat models. However, the mechanism of their action is not yet fully understood. Recently, our in vitro results suggested that PC12 cell death induced by Aβ25-35 can be protected by thymol and carvacrol via Protein Kinase C (PKC) and Reactive Oxygen Species (ROS) pathways. So, we hypothesize that the mechanisms of thymol and carvacrol in improving the learning impairment in the AD rat model may be related to their effects on PKC. So, the activity of PKC and protein expression levels of PKCα were examined in the hippocampal cells of the AD rat model. Methods: To examine the thymol and carvacrol effects, we performed a behavioral test in AD rat models induced by Aβ25–35 neurotoxicity. To access the underlying mechanism of the protective effects, western blotting was performed with antibodies against PKCα. We also measured the PKC activity assay by Elisa. Histopathological studies were carried out in the hippocampus with Hematoxylin and Eosin (H&E) staining.  Results: The escape latency increased in Aβ-received rats compared to the control group, and thymol and carvacrol reversed this deficit. Furthermore, these compounds could enhance the PKC activity and increase the PKCα expression ratio. Moreover, H&E staining showed that Aβ caused shrinkage of the CA1 pyramidal neurons. However, thymol and carvacrol treatments could prevent this effect of Aβ peptides. Conclusion: This study suggests that Amyloid-Beta (Aβ) results in memory decline and histochemical disturbances in the hippocampus. Moreover, these results revealed that thymol and carvacrol could have protective effects on cognition in AD-like models via PKC activation

Knee injury and osteoarthritis outcome score in patients with isolated meniscus injury; Validity and reliability

Background: The aim of this study is evaluation of the validity and reliability of the Persian version of Knee Injury and Osteoarthritis Outcome Score (KOOS) in patients with isolated meniscus injury. Materials and Methods: One hundred people with isolated meniscal injury (29 females and 71 males with a mean age ± standard deviation [SD] = 32.37 ± 9.97 years) and fifty normal people with no knee problems (34 females and 16 males with a mean age ± SD = 28.42 ± 8.84 years) participated in this study. In patients, the duration of meniscus injury ranged from 1 month to 4 years. For evaluation of discriminate validity, we compared scores of KOOS questionnaire between patients and healthy people, and for concurrent validity, in addition to filling KOOS questionnaire, patients completed Short Form (SF-36) questionnaire, test–retest reliability with intraclass correlation coefficient) ICC), and internal consistency with Cronbach's alpha was calculated. Results: Mean scores of patients (49.51 ± 17.13) and healthy people (86.01 ± 13.44) were different significantly (P < 0.001). The correlation between total score of SF-36 and KOOS was significant (r = 0.77, P< 0.001). ICC was 0.80 (ranged from 0.64–0.75) and Cronbach's alpha was 0.96 (ranged from 0.72 to 0.94). Conclusion: The Iranian version of KOOS is a reliable and valid tool for patients with isolated meniscus injury, so the clinicians and investigators may use this questionnaire in clinical settings and their researches