Design and Validation of Additively Manufactured Metallic Cellular Scaffold Structures for Bone Tissue Engineering

Bone-related defects that cannot heal without significant surgical intervention represent a significant challenge in the orthopedic field. The use of implants for these critical-sized bone defects is being explored to address the limitations of autograft and allograft options. Three-dimensional cellular structures, or bone scaffolds, provide mechanical support and promote bone tissue formation by acting as a template for bone growth. Stress shielding in bones is the reduction in bone density caused by the difference in stiffness between the scaffold and the surrounding bone tissue. This study aimed to reduce the stress shielding and introduce a cellular metal structure to replace defected bone by designing and producing a numerically optimized bone scaffold with an elastic modulus of 15 GPa, which matches the human’s cortical bone modulus. Cubic cell and diagonal cell designs were explored. Strut and cell dimensions were numerically optimized to achieve the desired structural modulus. The resulting scaffold designs were produced from stainless steel using laser powder bed fusion (LPBF). Finite element analysis (FEA) models were validated through compression testing of the printed scaffold designs. The structural configuration of the scaffolds was characterized with scanning electron microscopy (SEM). Cellular struts were found to have minimal internal porosity and rough surfaces. Strut dimensions of the printed scaffolds were found to have variations with the optimized computer-aided design (CAD) models. The experimental results, as expected, were slightly less than FEA results due to structural relative density variations in the scaffolds. Failure of the structures was stretch-dominated for the cubic scaffold and bending-dominated for the diagonal scaffold. The torsional and bending stiffnesses were numerically evaluated and showed higher bending and torsional moduli for the diagonal scaffold. The study successfully contributed to minimizing stress shielding in bone tissue engineering. The study also produced an innovative metal cellular structure that can replace large bone segments anywhere in the human body.     

Intracerebral injection of low amounts of norharman induces moderate Parkinsonism-like behavioral symptoms in rat

β-Carbolines (BCs) are considered to be endogenous toxins and have been proposed as possible causative candidates inducing Parkinson's disease (PD). However, there is controversy about the effect and also effective dose of these compounds in the etiology of PD. This study was designed to further examine the effect of norharman (NH), a BC which in mammalian brain occurs at high levels in the substantia nigra, on the development of Parkinsonism-like behaviors in rats. A small amount (4μl) of NH solution at 2 or 200ng/ml was unilaterally injected into either striatum or substantia nigra (SN) by stereotaxic surgery. The development of Parkinsonism was assessed by three conventional behavioral tests, compared to the effects of unilateral 6-hydroxydopamine (6-OHDA) - induced lesions in the nigrostriatal pathway. An apomorphine-induced rotational test revealed no Parkinsonism-like behavior in the NH treated groups. However, rats that received the high concentration of NH into their SN showed significant biased swings in the elevated body swing test. In a rotarod test, NH treated groups showed relatively weak motor performance and their learning patterns were close to that of the 6-OHDA treated rats. Considering that the rotational test is only valid in animals with severe Parkinsonism, but time spent on the rotating rod correlates inversely with severity of Parkinsonism, our results indicate that a single exposure to low amounts of NH is effective in producing moderate Parkinsonism-like behavioral symptoms, possibly through a neurotoxic effect of this agent on the SN dopaminergic neurons.     

Destructive Adsorption of Diazinon Pesticide by Activated Carbon Nanofibers Containing Al2O3 and MgO Nanoparticles

We report the destructive adsorption of Diazinon pesticide by porous webs of activated carbon nanofibers containing Al₂O₃ and MgO nanoparticles. The results show that, the presence of Al₂O₃ and MgO nanoparticles in the activated carbon nanofibers increases the amount of destructively adsorbed Diazinon pesticide by activated carbon nanofibers. Moreover, type, amount, and specific surface area of metal oxide nanoparticles affect the adsorption rate as well as the total destructively adsorbed Diazinon. Liquid chromatography proved the degradation of Diazinon by chemical reaction with Al₂O₃ and MgO nanoparticles. Liquid chromatography–mass spectrometry showed that the main product of reaction between Diazinon and the metal oxides is 2-isopropyl-6-methyl-4-pyrimidinol with less toxicity than Diazinon.     

Tissue factor antisense deoxyoligonucleotide prevents monocrotaline/LPS hepatotoxicity in mice

Tissue factor (TF) is a membranous glycoprotein that functions as a receptor for coagulation factor VII/VIIa and activates the coagulation system when blood vessels or tissues are damaged. TF was upregulated in our monocrotaline (MCT)/lipopolysaccharide (LPS) hepatotoxicity model. We tested the hypothesis that TF‐dependent fibrin deposition and lipid peroxidation in the form of oxidized low‐density‐lipoprotein (ox‐LDL) accumulation contribute to liver inflammation induced by MCT/LPS in mice. In the present study, we blocked TF using antisense oligodeoxynucleotides against mouse TF (TF‐ASO). TF‐ASO (5.6 mg kg^?1) was given i.v. to ND4 male mice 30 min after administration of MCT (200 mg kg^?1) p.o. followed after 3.5 h by LPS i.p. (6 mg kg^?1). Blood alanine aminotransferase (ALT), TF, ox‐LDL, platelets, hematocrit and keratinocyte‐derived chemokine (KC) levels were evaluated in different treatment groups. Fibrin deposition and ox‐LDL accumulation were also analyzed in the liver sections using immunofluorescent staining. The results showed that TF‐ASO significantly restored blood ALT, hematocrit and KC levels, distorted after MCT/LPS co‐treatment, as well as preventing the accumulation of ox‐LDL and the deposition of fibrin in the liver tissues, and thereby inhibited liver injury caused by MCT/LPS. In a separate experiment, TF‐ASO administration significantly prolonged animal survival. The current study demonstrates that TF is associated with MCT/LPS‐induced liver injury. Administration of TF‐ASO successfully prevented this type of liver injury. Copyright © 2012 John Wiley & Sons, Ltd.     

MRI as complementary tool added to ultrasound in the diagnosis of fetal renal abnormalities – any added value?

Purpose

To assess the potential role of magnetic resonance imaging (MRI) as a complementary diagnostic tool to ultrasonography (US) in the diagnosis of fetal renal anomalies in pregnant women with oligohydramnios in the absence of amniotic membrane rupture.

Methods

Ninety pregnant women, with oligohydramnios were prospectively evaluated using both US and MRI. Prenatal findings were correlated with the babies’ outcome.

Results

MRI studies of diagnostic quality were obtained in all fetuses. The US and MRI findings were concordant in 79 (87.8%) of the fetuses. MRI modified and changed the diagnosis in 11 fetuses (12.2%), these were five fetuses in which US diagnosis was inconclusive, five cases in which the diagnosis changed from bilateral renal agenesis to unilateral agenesis with the other kidney multicystic dysplastic kidney (MCDK), and in the remaining fetuses the modification was from bilateral renal agenesis to unilateral agenesis with the other kidney structurally normal.Concordant findings for the prenatal US and MRI scans were seen in 100% of the autosomal recessive polycystic kidney disease (APCKD), 96% of MCDK, and 92.9% of bilateral normal kidneys.

Conclusion

MRI is of value in cases of oligohydramnios in limited circumstance when US findings were inconclusive.     

GSTP1, GSTM1, and GSTT1 genetic polymorphisms in patients with cryptogenic liver cirrhosis

We investigated glutathione S-transferase (GST) P1I le (105) Val, T1, and M1 polymorphisms in 45 patients with documented cryptogenic cirrhosis and 56 healthy control subjects. Polymerase chain reaction-based procedures were performed in the studied populations to confirm the genotypes of GSTT1, M1, and P1. Ile/Val and Val/Val GSTP1 genotypes were more frequent in the patients with cirrhosis (n = 39, 87%) than in the control subjects (n = 10; 18%) (odds ratio [OR] 34.04; 95% confidence interval [CI] 10.70 to 108.31, P < 0.001). Among these patients with cirrhosis, 16 were heterozygous and 23 were homozygous, whereas only one person in the control group was homozygous. The GSTM1 null genotype was also more prevalent in cirrhotic patients than in healthy control subjects (OR 6.83, 95% CI 2.53 to 18.42, P < 0.001). The rate of GSTT1 deletion did not show a significant difference between the two groups (OR 2.35, 95% CI 0.76 to 7.28, P = 0.111). To our knowledge, this is the first evidence that GSTP1 and GSTM1 polymorphisms may be related to the development of cirrhosis by unknown mechanisms. The significant association of cryptogenic cirrhosis with Val/Val GSTP1 genotype encoding a low detoxification activity protein implicates this polymorphism as a risk factor for the occurrence of the disease. Presented as an abstract at the Forty-Fourth Annual Meeting of The Society for Surgery of the Alimentary Tract, Orlando, Florida, May 19–22, 2003 (Poster of Distinction).     

A Psychometric Indices of the Farsi Version of the Believability of Anxious Feelings and Thoughts Questionnaire (BAFT)

The following paper aimed to adapt and validate the Farsi version of the Believability of Anxious Feelings and Thoughts Questionnaire (BAFT), which measures cognitive fusion/defusion, one of the six components in Acceptance and Commitment Therapy (ACT). The authors assessed the psychometric properties of the BAFT in a sample of undergraduate students. Exploratory Factor Analysis supported a three-factor structure with 16 items. The results from a Confirmatory Factor Analysis showed the goodness of fit of the model. The test also demonstrated a good level of internal consistency and incremental validity. Overall, the results show that the Farsi version of BAFT is a consistent and valid scale.     

Identification of the phrenic nerve in surgical exploration of the brachial plexus in obstetrical palsy

This report describes a simple technique for identifying the phrenic nerve at the beginning of exploration of the brachial plexus in obstetrical palsy. Both the phrenic and supraclavicular nerves originate from the C4 root; therefore, retrograde dissection of the supraclavicular nerve will end at the C4 root and identify the phrenic nerve. This technique is very useful to less experienced surgeons but may also be helpful when the experienced surgeon encounters excessive scarring of the anterior scalene muscle. Finally, the dissected supraclavicular nerve may be used as a cable graft in brachial plexus reconstruction.