Open and Close-Packed, Shape-Engineered Polygonal Nanoparticle Metamolecules with Tailorable Fano Resonances

A top-down lithographic patterning and deposition process is reported for producing nanoparticles (NPs) with well-defined sizes, shapes, and compositions that are often not accessible by wet-chemical synthetic methods. These NPs are ligated and harvested from the substrate surface to prepare colloidal NP dispersions. Using a template-assisted assembly technique, fabricated NPs are driven by capillary forces to assemble into size- and shape-engineered templates and organize into open or close-packed multi-NP structures or NP metamolecules. The sizes and shapes of the NPs and of the templates control the NP number, coordination, interparticle gap size, disorder, and location of defects such as voids in the NP metamolecules. The plasmonic resonances of polygonal-shaped Au NPs are exploited to correlate the structure and optical properties of assembled NP metamolecules. Comparing open and close-packed architectures highlights that introduction of a center NP to form close-packed assemblies supports collective interactions, altering magnetic optical modes and multipolar interactions in Fano resonances. Decreasing the distance between NPs strengthens the plasmonic coupling, and the structural symmetries of the NP metamolecules determine the orientation-dependent scattering response.

Antibacterial and Cellular Behaviors of Novel Zinc-Doped Hydroxyapatite/Graphene Nanocomposite for Bone Tissue Engineering

Bacteria are one of the significant causes of infection in the body after scaffold implantation. Effective use of nanotechnology to overcome this problem is an exciting and practical solution. Nanoparticles can cause bacterial degradation by the electrostatic interaction with receptors and cell walls. Simultaneously, the incorporation of antibacterial materials such as zinc and graphene in nanoparticles can further enhance bacterial degradation. In the present study, zinc-doped hydroxyapatite/graphene was synthesized and characterized as a nanocomposite material possessing both antibacterial and bioactive properties for bone tissue engineering. After synthesizing the zinc-doped hydroxyapatite nanoparticles using a mechanochemical process, they were composited with reduced graphene oxide. The nanoparticles and nanocomposite samples were extensively investigated by transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. Their antibacterial behaviors against Escherichia coli and Staphylococcus aureus were studied. The antibacterial properties of hydroxyapatite nanoparticles were found to be improved more than 2.7 and 3.4 times after zinc doping and further compositing with graphene, respectively. In vitro cell assessment was investigated by a cell viability test and alkaline phosphatase activity using mesenchymal stem cells, and the results showed that hydroxyapatite nanoparticles in the culture medium, in addition to non-toxicity, led to enhanced proliferation of bone marrow stem cells. Furthermore, zinc doping in combination with graphene significantly increased alkaline phosphatase activity and proliferation of mesenchymal stem cells. The antibacterial activity along with cell biocompatibility/bioactivity of zinc-doped hydroxyapatite/graphene nanocomposite are the highly desirable and suitable biological properties for bone tissue engineering successfully achieved in this work.

Online Estimation of Elbow Joint Angle Using Upper Arm Acceleration: A Movement Partitioning Approach

Estimating the elbow angle using shoulder data is very important and valuable in Functional Electrical Stimulation (FES) systems which can be useful in assisting C5/C6 SCI patients. Much research has been conducted based on the elbow-shoulder synergies. The aim of this study was the online estimation of elbow flexion/extension angle from the upper arm acceleration signals during ADLs. For this, a three-level hierarchical structure was proposed based on a new approach, i.e. 'the movement phases'. These levels include Clustering, Recognition using HMMs and Angle estimation using neural networks. ADLs were partitioned to the movement phases in order to obtain a structured and efficient method. It was an online structure that was very useful in the FES control systems. Different initial locations for the objects were considered in recording the data to increase the richness of the database and to improve the neural networks generalization. The cross correlation coefficient (K) and Normalized Root Mean Squared Error (NRMSE) between the estimated and actual angles, were obtained at 90.25% and 13.64%, respectively. A post-processing method was proposed to modify the discontinuity intervals of the estimated angles. Using the post-processing, K and NRMSE were obtained at 91.19% and 12.83%, respectively.

Stable silencing of IGF1R using Lentiviral-mediated shRNA in HEK293T cells

Insulin-like growth factors are among the peptide mitogens that regulate cell proliferation and differentiation as well as mediator of antiapoptotic signals. The imbalance between the expression and activities of these molecules may lead to malignancy in cells. Evidences have suggested the insulin-like growth factor 1 receptor (IGF-1R) signaling pathway as a therapeutic target in the management and treatment of cancer. In this present study, we have generated silencing stable clones of HEK cells using six different pGIPZ (lentiviral vector) shRNAs targeted to human IGF-1R gene and a pGIPZ non-silencing shRNAmir lentiviral vector (as negative control). The recombinant lentiviral vectors were separately transduced into human embryonic kidney 293 T (HEK293T) cell lines. The knockdown of IGF-1R was confirmed by reverse transcription polymerase chain reaction (RT-PCR) and the relative IGF-1R mRNA levels were expressed as a ratio of IGF-1R to β-actin by REST software. The results showed significant reduction in the expression of IGF-1R mRNAs in cells transduced with all six pGIPZ-IGF-1R recombinant lentivirals compared to non-silencing negative control. No significant difference was observed among the six cassettes. Results indicated that recombinant lentiviral vectors provided an efficient and stable knockdown of IGF-1R providing useful tool for IGF-1R pathway studies.

Removing ECG Artifact from the Surface EMG Signal Using Adaptive Subtraction Technique

BACKGROUND

The electrocardiogram artifact is a major contamination in the electromyogram signals when electromyogram signal is recorded from upper trunk muscles and because of that the contaminated electromyogram is not useful. Objective : Removing electrocardiogram contamination from electromyogram signals.

METHODS

In this paper, the clean electromyogram signal, electrocardiogram artifact and electrocardiogram signal were recorded from leg muscles, the pectoralis major muscle of the left side and V4, respectively. After the pre-processing, contaminated electromyogram signal is simulated with a combination of clean electromyogram and electrocardiogram artifact. Then, contaminated electromyogram is cleaned using adaptive subtraction method. This method contains some steps; (1) QRS detection, (2) formation of electrocardiogram template by averaging the electrocardiogram complexes, (3) using low pass filter to remove undesirable artifacts, (4) subtraction.

RESULTS

Performance of our method is evaluated using qualitative criteria, power spectrum density and coherence and quantitative criteria signal to noise ratio, relative error and cross correlation. The result of signal to noise ratio, relative error and cross correlation is equal to 10.493, 0.04 and %97 respectively. Finally, there is a comparison between proposed method and some existing methods.

CONCLUSION

The result indicates that adaptive subtraction method is somewhat effective to remove electrocardiogram artifact from contaminated electromyogram signal and has an acceptable result.

Effect of early interferon beta-1a therapy on conversion to multiple sclerosis in Iranian patients with a first demyelinating event

BACKGROUND

A new treatment approach to multiple sclerosis (MS) is the initiation of interferon therapy in the early phase of the disease when a patient presents with clinically isolated syndrome.

AIMS OF THE STUDY

The goal of this study was to assess the effect of early treatment on the risk of conversion to clinically definite MS in Iranian patients.

METHODS

Eligible patients had presented with a first episode of neurological dysfunction suggesting MS within the previous 3 months and had abnormal brain magnetic resonance imaging (MRI). Patients were randomly assigned to receive intramuscular interferon beta 1a 30 mug or placebo once a week for 3 years.

RESULTS

Of the 217 patients randomized, 202 patients completed the study; 104 received Avonex and 98 received placebo. Fewer patients converted to clinically definite multiple sclerosis in the treated group than in the placebo group during the study (36.6% vs 58.2%, P < 0.003). The number of active T2-weighted MRI lesions was significantly lower in the treated group.

CONCLUSIONS

The results of our study, which are consistent with those from western studies, show that treatment at an early stage of MS delays conversion to definite MS and has positive effects on MRI outcomes.

Treatment of early onset multiple sclerosis with suboptimal dose of interferon beta-1a

BACKGROUND

Patients with early onset multiple sclerosis may develop disability at a younger age than adults. There are several reports about safety of beta interferons in childhood and juvenile MS with different doses.

OBJECTIVES

To determine safety and efficacy of substandard dose of intramuscular interferon beta-1a in a prospective randomized trial in patients with multiple sclerosis under the age of 16.

METHODS

Sixteen patients were divided into two groups randomly. The first group was treated with intramuscular interferon beta-1a 15 micrograms once a week and the second group received no disease-modifying therapy.

RESULTS

The patients were followed for four years. There was no significant side effect and none of the treated patients discontinued the drug. There were significant differences between two groups regarding relapse rates (p = 0.04), disability progression (p = 0.01), and new T2 lesions (p = 0.006).

CONCLUSION

Treatment with interferon beta-1a is well tolerated for a long period of time and may be effective in substandard doses in early onset multiple sclerosis.

[Acute encephalopathy and recurrent hepatic steatosis with normal long and medium chain fatty acyl-CoA-dehydrogenase activity]

A boy suffering from recurrent episodes of acute encephalopathy and hepatic steatosis died at 40 months of age. The symptoms started when he was 13 months old and he appeared completely normal in the intervals. Pertinent biologic findings were as follows: slight labile hypoglycemia and hyperammonemia having no direct correlation with neurologic derangement, no elevation of ammonia levels in loading tests, complete failure to generate ketones and the absence of organic aciduria during a fast, normal plasma carnitine levels and normal activity of long and medium chain acyl-CoA-dehydrogenase in skin fibroblasts. Pertinent autopsy findings were marked steatosis of liver and renal tubular cells with many foamy histiocytes in bone marrow. An error in metabolic pathways, particularly a derangement in lipid metabolism, was considered.

[Diffuse cutaneous vasculitis disclosing acute lymphoblastic leukemia]

Biopsy of skin for etiologic evaluation of generalized erythematous eruptions in a 4 1/2 years old child, starting four months ago, led to diagnosis of acute lymphoblastic leukemia. Leukocyte counts five and eight weeks and four months after appearance of eruptions were normal and no blasts were found. A leukocyte count performed simultaneously with biopsy of skin also showed few (less than 10%) blasts. Histologic examination of skin revealed two types of pathologic lesions: a perivascular cuffing of lymphoblasts and a leukocytoclastic type of small vessel vasculitis in other parts. This type of vasculitis which have been reported in association with chronic lymphocytic and hairy cell leukemias, is uncommon in acute lymphoblastic leukemia.

[Coexistence of late spondyloepiphyseal dysplasia and congenital megaloblastic anemia with proteinuria in the same family]

A case of spondyloepiphyseal dysplasia tarda was noted in a dwarf (130 cm tall) 18 years old boy associated with congenital megaloblastic anemia and proteinuria. His two sisters and a cousin are also suffering from similar hematologic disorder. One of his brothers, 145 cm tall, is also involved by spondyloepiphyseal dysplasia, but there is no known hematologic abnormalities. Review of family history revealed that two aunts from mother's side were deceased in adulthood following a chronic anemic disease. The findings in this anemia are compatible with Imerslund-Grâsbech syndrome and coexistence of these two rare genetic disorders in a single family has not been reported previously.