Mechanical analysis of a rodent segmental bone defect model: The effects of internal fixation and implant stiffness on load transfer

Segmental bone defect animal models are often used for evaluating the bone regeneration performance of bone substituting biomaterials. Since bone regeneration is dependent on mechanical loading, it is important to determine mechanical load transfer after stabilization of the defect and to study the effects of biomaterial stiffness on the transmitted load. In this study, we assess the mechanical load transmitted over a 6 mm femur defect that is stabilized with an internal PEEK fixation plate. Subsequently, three types of selective laser melted porous titanium implants with different stiffness values were used to graft the defect (five specimens per group). In one additional group, the defect was left empty. Micro strain gauges were used to measure strain values at four different locations of the fixation plate during external loading on the femoral head. The load sharing between the fixation plate and titanium implant was highly variable with standard deviations of measured strain values between 31 and 93% of the mean values. As a consequence, no significant differences were measured between the forces transmitted through the titanium implants with different elastic moduli. Only some non-significant trends were observed in the mean strain values that, consistent with the results of a previous finite element study, implied the force transmitted through the implant increases with the implant stiffness. The applied internal fixation method does not standardize mechanical loading over the defect to enable detecting small differences in bone regeneration performances of bone substituting biomaterials. In conclusion, the fixation method requires further optimization to reduce the effects of the operative procedure and make the mechanical loading more consistent and improve the overall sensitivity of this rat femur defect model.     

Distribution and genotype frequency of adiponectin (+45 T/G) and adiponectin receptor2 (+795 G/A) single nucleotide polymorphisms in Iranian population

The Adiponectin (ADIPOQ) gene encodes adipose tissue-secreted hormone, Adiponectin, which is secreted to the bloodstream by adipocytes. Adiponectin is a hormone with anti-inflammatory and anti-atherogenic properties and plays a significant role in insulin sensitivity and obesity. The genetic variations in ADIPOQ gene change the circulating adiponectin level and may cause insulin resistance. The aim of the present study is to evaluate the frequency of a common single nucleotide polymorphism (SNP) of ADIPOQ gene (+45T/G) and adiponectin receptor-2 (ADIPOR2) gene (+795G/A) in Iranian population and to correlate these data with other populations. A hundred healthy volunteers were enrolled to identify the genotype of ADIPOQ gene (+45T/G) and ADIPOR2 gene (+795G/A). This was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Genotype frequencies for ADIPOQ (+45T/G) were 0.789 for TT, 0.164 for TG, and 0.0468 for GG. Allelic frequencies were 0.87 and 0.13 for T and G, respectively. Genotype frequencies for ADIPOR2 (+795G/A) were 0.09 for AA, 0.3 for AG, and 0.61 for GG; allelic frequencies were 0.24 for A and 0.76 for G. Comparisons between ADIPOQ and ADIPOR2 polymorphisms in Iranian population with those in other populations showed significant differences.     

Frequency of HLA-G exon 8 polymorphisms and kidney allograft outcome in Iranian population

The 14-bp polymorphism in exon 8 of the HLA-G gene is associated with HLA-G mRNA stability and the patterns of alternative isoform splicing and may influence the functionality of the HLA-G molecule. HLA-G expression was related to allograft acceptance and fewer episodes of acute rejection during heart, kidney and liver–kidney transplantation. In order to determine a possible correlation between the 14-bp insertion/deletion polymorphism and kidney allograft outcome in our population, genomic DNA was isolated from 144 patients who had received isolated kidney allografts. The recipients was divided into two groups, grafts presenting features of rejection group and a non-rejection group, and compared them with a control group of 100 healthy subjects. There was no significant difference in allelic frequencies of 14-bp insertion/deletion polymorphism between normal controls and kidney transplant patients. No significant difference was found between the RG and the NRG regarding the 14-bp genotypes and alleles. Therefore, additional studies with more sample size from other populations with analysis of other HLA-G polymorphisms are necessary to define this polymorphism as a valuable clinical marker.     

Study of the association between glutathione S-transferase (GSTM1, GSTT1, GSTP1) polymorphisms with type II diabetes mellitus in southern of Iran

Diabetes Mellitus is characterized by chronic hyperglycemia and associated with an increased production of reactive oxygen species (ROS). Oxidative stress is the result of accumulation of free radicals in tissues which specially affects beta cells in pancreas. Glutathione S-transferases (GSTs) are a family of antioxidant enzymes that include several classes of GSTs. These enzymes have important roles in decreasing of ROS species and act as a kind of antioxidant defense. To investigate the association between GSTs polymorphism with type 2 diabetes mellitus (T2DM), we investigated the frequency of GSTM1, T1 and P1 genotypes in patients with T2DM and controls. The genotypes of GSTT1, M1 and P1 were determined in 171 clinically documented T2DM patients and 169 normal cases (as controls) by multiplex polymerase chain reaction and PCR–RFLP. In diabetic patients, the frequency of GSTM1-null genotype was significantly (OR?=?1.74; 95?% CI?=?1.13–2.69, P?=?0.016) higher than that in control. However, the frequency of GSTT1 (OR?=?1.29; 95?% CI?=?0.07–2.14, P?=?0.367) and GSTP1 (OR?=?0.83; 95?% CI?=?0.53–1.30, P?=?0.389) genotypes were not significantly different comparing both groups. Also, the frequency of both GSTT1-null and GSTM1-null genotypes in patients (19.88?%) was significantly higher compared to controls with the same genotypes (11.83?%, P?=?0.022). Our results indicated that GSTM1 and GSTT1 genotypes might be involved in the pathogenesis of T2DM in south Iranian population.     

Mechanism of Clostridium perfringens enterotoxin interaction with claudin-3/-4 protein suggests structural modifications of the toxin to target specific claudins

Claudins (Cld) are essential constituents of tight junctions. Domain I of Clostridium perfringens enterotoxin (cCPE) binds to the second extracellular loop (ECL2) of a subset of claudins, e.g. Cld3/4 and influences tight junction formation. We aimed to identify interacting interfaces and to alter claudin specificity of cCPE. Mutagenesis, binding assays, and molecular modeling were performed. Mutation-guided ECL2 docking of Cld3/4 onto the crystal structure of cCPE revealed a common orientation of the proposed ECL2 helix-turn-helix motif in the binding cavity of cCPE: residues Leu(150)/Leu(151) of Cld3/4 bind similarly to a hydrophobic pit formed by Tyr(306), Tyr(310), and Tyr(312) of cCPE, and Pro(152)/Ala(153) of Cld3/4 is proposed to bind to a second pit close to Leu(223), Leu(254), and Leu(315). However, sequence variation in ECL2 of these claudins is likely responsible for slightly different conformation in the turn region, which is in line with different cCPE interaction modes of Cld3 and Cld4. Substitutions of other so far not characterized cCPE residues lining the pocket revealed two spatially separated groups of residues (Leu(223), Asp(225), and Arg(227) and Leu(254), lle(258), and Asp(284)), which are involved in binding to Cld3 and Cld4, albeit differently. Involvement of Asn(148) of Cld3 in cCPE binding was confirmed, whereas no evidence for involvement of Lys(156) or Arg(157) was found. We show structure-based alteration of cCPE generating claudin binders, which interact subtype-specific preferentially either with Cld3 or with Cld4. The obtained mutants and mechanistic insights will advance the design of cCPE-based modulators to target specific claudin subtypes related either to paracellular barriers that impede drug delivery or to tumors.     

Interaction Between Central Opioidergic and Glutamatergic Systems on Food Intake in Neonatal Chicks: Role of NMDA,AMPA and mGLU1 Receptors

The present study was designed to examine the role of opioidergic and glutamatergic systems on feeding behavior in neonatal meat-type chicken. In experiment 1, FD₃ neonatal broilers ICV injected with (A) saline, (B) DAMGO (µ-opioid receptor agonist, 125 pmol), (C) MK-801 (NMDA glutamate receptors antagonist, 15 nmol) and (D) combination of DAMGO plus MK-801. Experiments 2–5 were similar to experiment 1, except FD₃ chicks ICV injected with CNQX (AMPA glutamate receptors antagonist, 390 nmol), AIDA (mGLU₁ receptors antagonist, 2 nmol), LY341495 (mGLU₂ receptors antagonist, 150 nmol) and UBP1112 (mGLU₃ receptors antagonist, 2 nmol) instead of MK-801, respectively. In experiments 6–10, FD₃ chicks ICV injected as the same as procedure to the experiments 1–5, except to inject with DPDPE (δ-opioid receptor agonist, 40 nmol) instead of the DAMGO. The experiments 11–15 were similar to the experiments 1–5, except neonatal broilers ICV injected with U-50488H (κ-opioid receptor agonist, 30 nmol) instead of DAMGO. Then the cumulative food intake measured until 120 min post injection. According to the results, ICV injection of DAMGO, significantly decreased food intake (P?<?0.05) while DPDPE and U-50488H increased feeding behavior compared to the control group (P?<?0.05). Co-injection of the DAMGO?+?MK-801 and DAMGO?+?AIDA, significantly decreased DAMGO-induced hypophagia in neonatal chicks (P?<?0.05). Also, co-injection of the DPDPE?+?CNQX significantly amplified DPDPE induced feeding behavior (P?<?0.05). These results suggested interconnection between central opioidergic and glutamatergic systems on feeding behavior mediates via µ- and δ-opioid receptor with NMDA, AMPA and mGLU₁ receptors in FD₃ neonatal broilers. These findings may shed light on the circuitry underlying interconnection between central opioidergic and glutamatergic systems on feeding behavior.     

Greener,Nonhalogenated Solvent Systems for Highly Efficient Perovskite Solar Cells

All current highest efficiency perovskite solar cells (PSCs) use highly toxic, halogenated solvents, such as chlorobenzene (CB) or toluene (TLN), in an antisolvent step or as solvent for the hole transporter material (HTM). A more environmentally friendly antisolvent is highly desirable for decreasing chronic health risk. Here, the efficacy of anisole (ANS), as a greener antisolvent for highest efficiency PSCs, is investigated. The fabrication inside and outside of the glovebox showing high power conversion efficiencies of 19.9% and 15.5%, respectively. Importantly, a fully nonhalogenated solvent system is demonstrated where ANS is used as both the antisolvent and the solvent for the HTM. With this, state‐of‐the‐art efficiencies close to 20.5%, the highest to date without using toxic CB or TLN, are reached. Through scanning electron microscopy, UV–vis, photoluminescence, and X‐ray diffraction, it is shown that ANS results in similar mixed‐ion perovskite films under glovebox atmosphere as CB and TLN. This underlines that ANS is indeed a viable green solvent system for PSCs and should urgently be adopted by labs and companies to avoid systematic health risks for researchers and employees.     

Temporal proteomic profiling of Chlamydia trachomatis–infected HeLa‐229 human cervical epithelial cells

Chlamydia trachomatis is the leading causative agent of bacterial sexually transmitted infections worldwide which can lead to female pelvic inflammatory disease and infertility. A greater understanding of host response during chlamydial infection is essential to design intervention technique to reduce the increasing incidence rate of genital chlamydial infection. In this study, we investigated proteome changes in epithelial cells during C. trachomatis infection by using an isobaric tags for relative and absolute quantitation (iTRAQ) labeling technique coupled with a liquid chromatography‐tandem mass spectrometry (LC‐MS³) analysis. C. trachomatis (serovar D, MOI 1)–infected HeLa‐229 human cervical carcinoma epithelial cells (at 2, 4 and 8 h) showed profound modifications of proteome profile which involved 606 host proteins. MGST1, SUGP2 and ATXN10 were among the top in the list of the differentially upregulated protein. Through pathway analysis, we suggested the involvement of eukaryotic initiation factor 2 (eIF2) and mammalian target of rapamycin (mTOR) in host cells upon C. trachomatis infection. Network analysis underscored the participation of DNA repair mechanism during C. trachomatis infection. In summary, intense modifications of proteome profile in C. trachomatis–infected HeLa‐229 cells indicate complex host‐pathogen interactions at early phase of chlamydial infection.     

Genetic Variants of Angiotensin-Converting Enzyme Are Linked to Autism: A Case-Control Study

BackgroundAutism is a disease of complex nature with a significant genetic component. The importance of renin-angiotensin system (RAS) elements in cognition and behavior besides the interaction of angiotensin II (Ang II), the main product of angiotensin-converting enzyme (ACE), with neurotransmitters in CNS, especially dopamine, proposes the involvement of RAS in autism. Since the genetic architecture of autism has remained elusive, here we postulated that genetic variations in RAS are associated with autism.MethodsConsidering the relation between the three polymorphisms of ACE (I/D, rs4343 and rs4291) with the level of ACE activity, we have investigated this association with autism, in a case-control study. Genotype and allele frequencies of polymorphisms were determined in DNAs extracted from venous blood of 120 autistic patients and their age and sex-matched healthy controls, using polymerase chain reaction (PCR) and PCR–restriction fragment length polymorphism (PCR–RFLP) methods.ResultsThere were strong associations between both DD genotype of ACE I/D and the D allele, with autism (P = 0.006, OR = 2.9, 95% CI = 1.64–5.13 and P = 0.006, OR = 2.18, 95% CI = 1.37–3.48 respectively). Furthermore, a significant association between the G allele of rs4343 and autism was observed (P = 0.006, OR = 1.84, 95%CI = 1.26–2.67). Moreover, haplotype analysis revealed an association between DTG haplotype and autism (P = 0.008).ConclusionOur data suggests the involvement of RAS genetic diversity in increasing the risk of autism.