Diversity of Ganglion Cell Responses to Saccade-Like Image Shifts in the Primate Retina.

Saccades are a fundamental part of natural vision. They interrupt fixations of the visual gaze and rapidly shift the image that falls onto the retina. These stimulus dynamics can cause activation or suppression of different retinal ganglion cells, but how they affect the encoding of visual information in different types of ganglion cells is largely unknown. Here, we recorded spiking responses to saccade-like shifts of luminance gratings from ganglion cells in isolated marmoset retinas and investigated how the activity depended on the combination of presaccadic and postsaccadic images. All identified cell types, On and Off parasol and midget cells, as well as a type of Large Off cells, displayed distinct response patterns, including particular sensitivity to either the presaccadic or the postsaccadic image or combinations thereof. In addition, Off parasol and Large Off cells, but not On cells, showed pronounced sensitivity to whether the image changed across the transition. Stimulus sensitivity of On cells could be explained based on their responses to step changes in light intensity, whereas Off cells, in particular, parasol and the Large Off cells, seem to be affected by additional interactions that are not triggered during simple light-intensity flashes. Together, our data show that ganglion cells in the primate retina are sensitive to different combinations of presaccadic and postsaccadic visual stimuli. This contributes to the functional diversity of the output signals of the retina and to asymmetries between On and Off pathways and provides evidence of signal processing beyond what is triggered by isolated steps in light intensity.SIGNIFICANCE STATEMENT Sudden eye movements (saccades) shift our direction of gaze, bringing new images in focus on our retinas. To study how retinal neurons deal with these rapid image transitions, we recorded spiking activity from ganglion cells, the output neurons of the retina, in isolated retinas of marmoset monkeys while shifting a projected image in a saccade-like fashion across the retina. We found that the cells do not just respond to the newly fixated image, but that different types of ganglion cells display different sensitivities to the presaccadic and postsaccadic stimulus patterns. Certain Off cells, for example, are sensitive to changes in the image across transitions, which contributes to differences between On and Off information channels and extends the range of encoded stimulus features.

Investigating the expression level of miR-17-3p, miR-101-3p, miR-335-3p, and miR-296-3p in the peripheral blood of patients with acute myocardial infarction.

The role of inflammation has been proven in acute myocardial infarction (AMI) pathogenesis. Due to the effect of NLRP3 gene expression in the inflammation process of MI, we aimed to explore the expression changes and diagnostic power of four inflammation-related miRNAs including miR-17-3p, miR-101-3p, miR-335-3p, miR-296-3p and their potential target, NLRP3, in ST-segment elevation myocardial infarction (STEMI), and non-STEMI (NSTEMI) patients as two major classes of AMI. The expression level of these genes were evaluated in 300 participants equally divided into three groups of STEMI, NSTEMI, and control using quantitative real-time PCR. The expression level of NLRP3 was upregulated in STEMI and NSTEMI patients compared to control subjects. Besides, the expression levels of miR-17-3p, miR-101-3p, and miR-296-3p were significantly downregulated in STEMI and NSTEMI patients compared to controls. The increased expression of NLRP3 had a very strong inverse correlation with miR-17-3p in patients with STEMI and with miR-101-3p in the STEMI and NSTEMI patients. ROC curve analysis showed that the expression level of miR-17-3p had the highest diagnostic power for discrimination between STEMI patients and controls. Remarkably, the combination of all markers resulted in a higher AUC. In summary, there is a significant association between the expression levels of miR-17-3p, miR-101-3p, miR-335-3p, miR-296-3p, and NLRP3 and the incidence of AMI. Although the miR-17-3p expression level has the highest diagnostic power to distinguish between STEMI patients and control subjects, the combination of these miRNAs and NLRP3 could serve as a novel potential diagnostic biomarker of STEMI.

Prognostic value of circulating macrophage inhibitory cytokine 1-growth differentiation factor 15 (MIC-1/GDF15) in obesity: Relation with vascular endothelial growth factor (VEGF) and markers of oxidative stress.

Background: Macrophage inhibitory cytokine 1-Growth differentiation Factor 15 (MIC-1/GDF15) and vascular endothelial growth factor (VEGF) are novel regulators of obesity and energy homeostasis and food intake. Aims: In the current cross-sectional study, we aimed to evaluate MIC-1 and VEGF concentrations and their association with serum lipids and biomarkers of oxidative stress in obese individuals. Methods: Fifty six obese subjects, aged between 20-50 years old, participated in the current study. Anthropometric and nutritional parameters were assessed and serum and blood concentrations of MIC-1/GDF15, VEGF, markers of oxidative stress and serum lipids were evaluated. Results: Serum VEGF was strongly associated with serum lipids and MIC-1/GDF15 concentrations while serum MIC-1/GDF15 was associated with total cholesterol (TC) and VEGF levels. In multivariate regression analysis, serum VEGF, appetite and GPX were potent determinants of MIC-1/GDF15 concentrations while VEGF was only associated with serum MIC-1/GDF15. Conclusion: The findings of the current study demonstrated the association between MIC-1/GDF15 and VEGF. Moreover, a positive association between these cytokines and serum lipids, was also observed. The results suggest that MIC-1/GDF15 and VEGF might be considered as prognostic markers in obesity-related metabolic disorders. Although further mechanistic studies are needed to better clarify the underlying mechanism.

The evaluation of efficacy of atmospheric pressure plasma in diabetic ulcers healing: A randomized clinical trial.

The aim of this study is to evaluate the efficacy and safety of cold atmospheric plasma (CAP) as a novel therapy for diabetic foot ulcers. This was an investigator-blinded, randomized controlled trial of 14 weeks (6 weeks of treatment and 8 weeks of follow-up). Twenty patients with diabetic foot ulcers were divided into two groups: the control group receiving standard wound care and the plasma group, which received CAP twice a week for six consecutive weeks in addition to standard wound care. The ulcer size, amount of exudate, and wound grading were determined weekly. Cold plasma was produced by applying a high voltage (4.5 kV) and a high frequency (22 kHz) to helium gas. Exudate from wounds treated with CAP showed a significant reduction in the third week after complete treatment (p = 0.039). The wound grading of the ulcers improved by the sixth week (p = 0.019), and the sizes of ulcers significantly decreased in the plasma group at the end of the treatment period (p = 0.007). In this randomized clinical trial, CAP was an effective treatment option for diabetic foot ulcers in terms of wound surface reduction and antibacterial effects.

The cooperative effects of micro-grooved topography and TGF-ß1 on the vascular smooth muscle cell contractile protein expression of the mesenchymal stem cells.

Cell morphological changes induced by micro-grooved topography have been shown to be an important regulator of smooth muscle (SM) differentiation of mesenchymal stem cells (MSCs). In addition to the micro-grooved topography, transforming growth factor-ß1 (TGF-ß1) can also modulate MSCs differentiation towards smooth muscle cells (SMCs) through alterations in cell morphological characteristics. Thus, it can be hypothesized that substrate topography and TGF-ß1 may interact to facilitate differentiation of MSCs into SMCs. In this study, we investigated the time-course cooperative effects of substrate topography and TGF-ß1 in the regulation of SM differentiation of human MSCs. Western blotting, followed by image analysis, was performed to assess the protein expression of α-actin, h1-calponin and gelsolin. Three-way analysis of variance was employed to investigate the main effect of each independent variable, i.e. TGF-ß1 conditioning, substrate topography and culture time, along with the interactions of these variables. Each of TGF-ß1, substrate topography and culture time significantly affected the protein expression of α-actin, h1-calponin and gelsolin. Overall, TGF-ß1 conditioning of the cells and culturing the cells on the micro-grooved substrate resulted in greater protein expression of α-actin and h1-calponin, and lesser protein expression of gelsolin. In addition to the isolated effects of the variables, treatment type interacted with substrate topography and culture time to regulate the expression of the above-mentioned proteins. This study indicated the feasibility of promoting SM differentiation of human MSCs by simultaneous recruitment of micro-grooved topography and TGF-ß1. The findings could be of assistance when effective utilization of chemo-physical cues is needed to achieve functional SMC-like MSCs in vitro.

Improved osteogenic differentiation of human induced pluripotent stem cells cultured on polyvinylidene fluoride/collagen/platelet-rich plasma composite nanofibers.

Blood transfusion or blood products, such as plasma, have a long history in improving health, but today, platelet-rich plasma (PRP) is used in various medical areas such as surgery, orthopedics, and rheumatology in many ways. Considering the high efficiency of tissue engineering in repairing bone defects, in this study, we investigated the combined effect of nanofibrous scaffolds in combination with PRP on the osteogenic differentiation potential of human induced pluripotent stem cells (iPSCs). Electrospinning was used for fabricating nanofibrous scaffolds by polyvinylidene fluoride/collagen (PVDF/col) with and without PRP. After scaffold characterization, the osteoinductivity of the fabricated scaffolds was studied by culturing human iPSCs under osteogenic medium. The results showed that PRP has a considerable positive effect on the biocompatibility of the PVDF/col nanofibrous scaffold when examined by protein adsorption, cell attachment, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. In addition, the results obtained from alkaline phosphatase activity and calcium content assays demonstrated that nanofibers have higher osteoinductivity while grown on PRP-incorporated PVDF/col nanofibers. These results were also confirmed while the osteogenic differentiation of the iPSCs was more investigated by evaluating the most important bone-related genes expression level. According to the results, it can be concluded that PVDF/col/PRP has much more osteoinductivity while compared with the PVDF/col, and it can be introduced as a promising bone bio-implant for use in bone tissue engineering applications.

Effect of flagellin on inhibition of infectious mechanisms by activating opsonization and salmonella flagellum disruption.

Some serovars of salmonella cause huge global diseases such as enteric fever and invasive non typhoidal Salmonella disease. Flagellin as a key antigenic component of salmonella, can induce humoral and cellular immunity responses. In this research, we performed an opsonophagocytic killing assay (OPKA) as an important mechanism of the host-defense system, for salmonella to study the activity of anti-sera of native FliC, truncated modified recombinant FliC (tmFliC) and full length recombinant FliC proteins (flFliC). Also, the potency of antibodies for inhibiting bacterial movement was evaluated by traditional and newly-designed motility inhibition assay methods. Results showed both recombinant FliC anti-sera and native FliC (nFliC) anti-serum had the ability to opsonize Salmonella typhimurim, which led to bacterial clearance by mice macrophages. Also, inhibition of bacterial motility was observed for all anti-sera. Anti-nFliC and anti-flFliC sera showed higher effects on Salmonella typhimurim motility than that of tmFliC. In traditional method, about 88%, 86% and 80% inhibition were observed by using 5% nFliC, anti-flFliC and anti-tmFliC sera, respectively. In the newly-designed method using SIM (Sulfide indole motility) medium, results confirmed the traditional method for motility inhibition. Our findings suggest that salmonella fliC as a protective antigen may disrupt the flagellum apparatus activity.

Skimmed milk as an alternative for IPTG in induction of recombinant protein expression.

Cost-effectiveness is an important issue in biotechnological manufacturing industry and using alternative cheap materials with the same benefits has been noticed in most literatures. Isopropyl ß-d-1-thiogalactopyranoside (IPTG), a well-known chemical element for induction of protein expression, has several disadvantages such as high expense and toxicity. In this study, we aimed to introduce skimmed milk as an alternative material for protein expression by induction of lac operon. In this way, Escherichia coli BL21 (DE3) bacteria were induced using 1 mM IPTG or 1.0% (w/v) skimmed milk. Protein purification was performed using Ni-NTA (nickel-nitrilotriacetic acid) for His-tagged recombinant proteins and protein purity was evaluated by SDS-PAGE. Results showed high level of recombinant protein expression using skimmed milk, and interestingly, the growth rate of bacteria improved. Our findings suggested that skimmed milk can be a suitable alternative for induction of recombinant protein expression, which has advantages such as more availability and affordability, in comparison to IPTG supplementation.

Effect of kidney transplantation on right ventricular function, assessment by 2- dimensional speckle tracking echocardiography.

BACKGROUND: Advanced chronic kidney disease often results in adverse cardiovascular outcomes and is the leading cause of mortality in patients with end stage renal diseases (ESRD). There is much information about the effect of chronic kidney diseases (CKD) on the left ventricle (LV) chamber, but the right ventricle (RV) as a neglected chamber had not been evaluated precisely, in spite of its importance. OBJECTIVES: The aim of this study was to evaluate the impact of successful kidney transplants on the RV systolic and diastolic function using the advanced method of 2D speckle tracking echocardiography and comparison with the conventional methods. METHOD: The study included 48 patients with CKD who were eligible for kidney transplantation and underwent successful kidney transplantations. Right ventricular indices were evaluated, while RV function was focused by conventional methods and 2D speckle tracking echocardiography before the successful kidney transplant and 1 week, 1 month, and 3 months after the successful kidney transplant. RESULTS: The results of the study showed that RV global longitudinal strain and RV free wall longitudinal strain improved over the time (P = 0.024, P < 0.001 respectively). It also represented that kidney transplantation did not have significant effect on the RV mid cavity diameter, tissue velocity, Myocardial performance index, RV longitudinal diameter, and Tricuspid annular plane systolic excursion indices, but for other indices this effect was significant. On the differences between the mean slope of regression line of the GLS variable in hypertensive subjects (1.0 ± 0.2) and non-hypertensive subjects (0.36 ± 0.32), an independent t-test showed that between the two groups in terms of the improvement of RVGLS, there was a significant statistical difference (P = 0.0067). CONCLUSION: Most of the ESRD patients had subtle RV dysfunction which could be better detected by recent echocardiography methods than conventional methods. Moreover, kidney transplantation led to considerable improvements in RV function in this population.

Adipose-derived stem cells-conditioned medium improved osteogenic differentiation of induced pluripotent stem cells when grown on polycaprolactone nanofibers.

Considering that the common osteogenic growth factors cannot be transplanted with stem cells to the patients, many studies are underway to find a replacement for these factors. Recently, it has been determined that mesenchymal stem cell (MSC)-derived conditioned medium (CM) contains effective factors in the bone formation process. In the current study, the synergistic effect of adipose-derived MSC's CM, and polycaprolactone (PCL) scaffold was investigated on the osteogenic differentiation potential of human induced pluripotent stem cells (iPSCs). After scaffold fabrication by electrospinning and characterization by scanning electron microscopy, iPSCs proliferation in the presence of CM, PCL, and both was evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide. Then, iPSCs osteogenic differentiation was investigated while cultured on tissue culture plate and PCL under CM compared with the osteogenic medium using alizarin red staining, calcium content, alkaline phosphatase activity and gene and protein expression analysis. Proliferation rate of the iPSCs was increased while cultured under CM and its effect was synergistically enhanced by culture on PCL. Evaluation of the osteogenic markers was showed CM alone could induce osteogenic differentiation into the iPSCs and this potential was significantly increased while combined with PCL nanofibrous scaffold. According to the results, it was demonstrated that CM has an osteogenic induction property almost the same of the common osteogenic medium and it can also be used potentially with stem cells when transplant to the patients. CM can also help by prolonging cell survival at the site of the defect as well as accelerating healing process.

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) improved osteogenic differentiation of the human induced pluripotent stem cells while considered as an artificial extracellular matrix.

Cocell polymers can be the best implants for replacing bone defects in patients. The pluripotent stem cells produced from the patient and the nanofibrous polymeric scaffold that can be completely degraded in the body and its produced monomers could be also usable are the best options for this implant. In this study, electrospun poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers were fabricated and characterized and then osteogenic differentiation of the human-induced pluripotent stem cells (iPSCs) was investigated while cultured on PHBV scaffold. MTT results showed that cultured iPSCs on PHBV proliferation were increased compared to those cultured on tissue culture polystyrene (TCPS) as the control. Alkaline phosphatase (ALP) activity and calcium content were also significantly increased in iPSCs cultured on PHBV compared to the cultured on TCPS under osteogenic medium. Gene expression evaluation demonstrated that Runx2, collagen type I, ALP, osteonectin, and osteocalcin were upregulated in iPSCs cultured on PHBV scaffold in comparison with those cultured on TCPS for 2 weeks. Western blot analysis have shown that osteocalcin and osteopontin expression as two major osteogenic markers were increased in iPSCs cultured on PHBV scaffold. According to the results, nanofiber-based PHBV has a promising potential to increase osteogenic differentiation of the stem cells and iPSCs-PHBV as a cell-co-polymer construct demonstrated that has a great efficiency for use as a bone tissue engineered bioimplant.

Incorporated-bFGF polycaprolactone/polyvinylidene fluoride nanocomposite scaffold promotes human induced pluripotent stem cells osteogenic differentiation.

Bioactive scaffolds that can increase transplanted cell survival time at the defect site have a great promising potential to use clinically since tissue regeneration or secretions crucially depend on the transplanted cell survival. In this study embedded basic fibroblast growth factor (bFGF)-polycaprolactone-polyvinylidene fluoride (PCL-PVDF) hybrid was designed and fabricated by electrospinning as a bio-functional nanofibrous scaffold for bone tissue engineering. After morphological characterization of the PCL-PVDF (bFGF) scaffold, nanofibers biocompatibility was investigated by culturing of the human induced pluripotent stem cells (iPSCs). Then, the bone differentiation capacity of the iPSCs was evaluated when grown on the PCL-PVDF and PCL-PVDF (bFGF) scaffolds in comparison with culture plate as a control using evaluating of the common osteogenic markers. The viability assay displayed a significant increase in iPSCs survival rate when grown on the bFGF content scaffold. The highest alkaline phosphatase activity and mineralization were detected in the iPSCs while grown on the PCL-PVDF (bFGF) scaffolds. Obtained results from gene and protein expression were also demonstrated the higher osteoinductive property of the bFGF content scaffold compared with the scaffold without it. According to the results, the release of bFGF from PCL-PVDF nanofibers increased survival and proliferation rate of the iPSCs, which followed by an increase in its osteogenic differentiation potential. Taking together, PCL-PVDF (bFGF) nanofibrous scaffold demonstrated that can be noted as a promising candidate for treating the bone lesions by tissue engineering products.

Immunostimulatory effects of truncated and full-length flagellin recombinant proteins.

Problems regarding purification efficacy in recombinant technologies is due to the protein structure. Experimental manipulation of genes and the subsequent proteins may overcome this issue. In order to improve production efficacy and maintain immunestimulatory effect of flagellin, the Toll-like Receptor 5 (TLR5) ligand and a potent adjuvant, we performed a bioinformatic study to find the best model for FliC manipulation. Truncated modified FliC (tmFliC) and full length FliC (flFliC) genes were cloned and expressed in pET-21a vector and protein purification was carried out using an improved His-Tag method. Polyclonal antibodies were generated against flFliC and tmFliC in New Zealand white rabbits. IgG response to the recombinant proteins was determined by ELISA. Cross-reactivity assay was performed by ELISA for all proteins and bacteria. Immunogenicity of tmFliC and flFliC was evaluated in chicken cells, and expression level of tumor necrotic factor-α (TNF-α) and interleukin-6 (IL-6) were relatively analyzed by Real-Time-PCR. Results showed high purification efficacy for tmFliC. Antibody titer of tmFliC was significantly higher than that of flFliC. In addition, the cross-reactivity assay for both proteins and Salmonella was positive which indicates similar epitopic regions. Stimulation of both FliCs significantly increased TNF-α and IL-6 expression in peripheral blood mononuclear cells (PBMCs) and splenocytes, with higher effect observed with flFliC. IL-8 protein level increased after 6 and 24 h stimulation with different concentrations of tmFliC and flFliC. These results suggest that the aimed gene modification in fliC gene produces a bioactive immunostimulant type of flagellin which upregulates TLR5 downstream genes as well as in flFliC.

Introducing a cost-effective method for purification of bioactive flagellin from several flagellated gram-negative bacteria.

The objective of this study was to introduce a simple and cheap method for purification of flagellin. So, flagellin proteins of Salmonella typhimurium (S. typhimurium), Escherichia coli (E. coli), Citrobacter freundii (C. freundii) and Salmonella typhi (S. typhi) were purified by a modified simple method. Bacterial cultures were precipitated by centrifugation. Precipitates were washed twice and flagellin proteins were detached by shaking vigorously (in PBS pH = 2), and then flagellin proteins were precipitated by ammonium sulfate saturation. Evaluation of purification efficiency and concentration were examined by SDS-PAGE and Bradford assay. Polyclonal antibodies were produced against S. typhimurium FliC and cross-reactivity of anti-S. typhimurium was assessed against other flagellins. Bioactivity of flagellins was evaluated by cell proliferation and IL-8 protein expression assay in HEK293 cells, and also, IL-6 and TNF-α genes expression in chicken cells. Results showed a single band for flagellin proteins of all bacteria on %10 SDS-PAGE, which concentration ranged from 150 to 400 µg/mL. All flagellin proteins increased cell proliferation, and IL-8 levels were increased after treatment by flagellins and levels of IL-6 and TNF-α were increased after treatment with S. typhimurium FliC. All flagellin proteins showed cross-reactivity with antibodies. Findings showed that application of our method, not only reduced time and cost, but also, the purified flagellin proteins had acceptable bioactivity.

Bone tissue engineering: Adult stem cells in combination with electrospun nanofibrous scaffolds.

Since bone tissue lesions caused by several reasons and has global outbreak without any attentions to the modernity level of the countries. In the other hands treatment of patients with this problem faced to the several limitations, in this because the future of the bone lesions treatments is related to the future of the bone tissue engineering. This review tries to cover the most suitable stem cells and materials from either natural or synthetic sources for bone tissue engineering. These understanding points would help researchers to further uncover the application of different adult stem cell sources in electrospinning scaffolds, promotion of nanofibrous composite construct design and adult stem cell type selection to enhance cell function and bone tissue engineering, and link laboratory investigations to clinical applications.

Diversity in spatial scope of contrast adaptation among mouse retinal ganglion cells.

Retinal ganglion cells adapt to changes in visual contrast by adjusting their response kinetics and sensitivity. While much work has focused on the time scales of these adaptation processes, less is known about the spatial scale of contrast adaptation. For example, do small, localized contrast changes affect a cell's signal processing across its entire receptive field? Previous investigations have provided conflicting evidence, suggesting that contrast adaptation occurs either locally within subregions of a ganglion cell's receptive field or globally over the receptive field in its entirety. Here, we investigated the spatial extent of contrast adaptation in ganglion cells of the isolated mouse retina through multielectrode-array recordings. We applied visual stimuli so that ganglion cell receptive fields contained regions where the average contrast level changed periodically as well as regions with constant average contrast level. This allowed us to analyze temporal stimulus integration and sensitivity separately for stimulus regions with and without contrast changes. We found that the spatial scope of contrast adaptation depends strongly on cell identity, with some ganglion cells displaying clear local adaptation, whereas others, in particular large transient ganglion cells, adapted globally to contrast changes. Thus, the spatial scope of contrast adaptation in mouse retinal ganglion cells appears to be cell-type specific. This could reflect differences in mechanisms of contrast adaptation and may contribute to the functional diversity of different ganglion cell types.NEW & NOTEWORTHY Understanding whether adaptation of a neuron in a sensory system can occur locally inside the receptive field or whether it always globally affects the entire receptive field is important for understanding how the neuron processes complex sensory stimuli. For mouse retinal ganglion cells, we here show that both local and global contrast adaptation exist and that this diversity in spatial scope can contribute to the functional diversity of retinal ganglion cell types.

Enhanced Skin Regeneration by Herbal Extract-Coated Poly-L-Lactic Acid Nanofibrous Scaffold.

The wound healing process is directly related to the type of treatment. Existing methods of treatment are not responsive enough for severe wounds. The aim of this study was the potential capacity investigation of poly-L-lactic acid (PLLA) nanofibrous scaffolds coated by aloe vera gel for wound dressing applications. In this study, electrospinning method was used for preparing PLLA nanofibers, and after characterization by SEM and MTT, its influence on the wound healing process was investigated with and without aloe vera gel as a wound dressing in full-thickness skin defect in mice. Band-Aids were used as a positive control and vaseline gauze as a negative control. SEM and MTT assays confirmed the nanometer size and biocompatibility of fabricated nanofibers. Macroscopic and histopathological characteristics were evaluated at the end of days 7, 12, and 17 and their results showed that the gel-coated scaffold accelerated the wound-healing process compared with other groups. At the end of the experiment, it was shown that during the whole time of study, gel-coated scaffold had the highest overall repair score. Therefore, gel-coated PLLA scaffold would be an ideal construct for wound healing and skin regenerative medicine application.

Role of block copolymer adsorption versus bimodal grafting on nanoparticle self-assembly in polymer nanocomposites.

We compare the self-assembly of silica nanoparticles (NPs) with physically adsorbed polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymers (BCP) against NPs with grafted bimodal (BM) brushes comprised of long, sparsely grafted PS chains and a short dense carpet of P2VP chains. As with grafted NPs, the dispersion state of the BCP NPs can be facilely tuned in PS matrices by varying the PS coverage on the NP surface or by changes in the ratio of the PS graft to matrix chain lengths. Surprisingly, the BCP NPs are remarkably better dispersed than the NPs tethered with bimodal brushes at comparable PS grafting densities. We postulate that this difference arises because of two factors inherent in the synthesis of the NPs: In the case of the BCP NPs the adsorption process is analogous to the chains being "grafted to" the NP surface, while the BM case corresponds to "grafting from" the surface. We have shown that the "grafted from" protocol yields patchy NPs even if the graft points are uniformly placed on each particle. This phenomenon, which is caused by chain conformation fluctuations, is exacerbated by the distribution function associated with the (small) number of grafts per particle. In contrast, in the case of BCP adsorption, each NP is more uniformly coated by a P2VP monolayer driven by the strongly favorable P2VP-silica interactions. Since each P2VP block is connected to a PS chain we conjecture that these adsorbed systems are closer to the limit of spatially uniform sparse brush coverage than the chemically grafted case. We finally show that the better NP dispersion resulting from BCP adsorption leads to larger mechanical reinforcement than those achieved with BM particles. These results emphasize that physical adsorption of BCPs is a simple, effective and practically promising strategy to direct NP dispersion in a chemically unfavorable polymer matrix.

Extra-axial medulloblastoma in cerebello-pontine angle: A report of a rare case with literature review.

Medulloblastoma is quite uncommon in the adult population and even rarer in extra-axial site in cerebello-pontine (CP) angle. In this report, a 23-year-old male patient with a two month history of deafness, nausea, vomiting and ataxia is presented. Clinical and radiological findings demonstrated a heterogeneously enhanced extra-axial lesion in the right CP angle. Total excision was performed and the histopathological features of medulloblastoma were confirmed. After surgery, the patient had no neurological deficit and the audiometric findings were improved. In addition, he underwent adjuant radiotherapy and no sign of metastatic mass was observed in follow-up spinal cord MRI. Although extremely rare, medulloblastoma must be considered in the differential diagnosis of extra-axial CP angle lesions.

Comparison of aloe vera gel dressing with conventional dressing on pressure ulcer pain reduction: a clinical trial.

BACKGROUND: Aloe Vera has a strong analgesic and anti-inflammatory effect, and its use effectively controls pain. This study aimed to determine the effect of Aloe Vera gel versus saline on pain relief of pressure ulcers. METHODS: This study is a double-blind, randomized clinical trial conducted in Valiasr Hospital in Arak, Markazi Province, in the center of Iran from May 2020 to April 2022. Using the available sampling method, 95 patients with pressure ulcers were assessed for eligibility, 64 patients were selected, 33 patients were placed in the experimental and 34 patients in control. For the experimental group, the ulcers were first cleaned with normal saline to remove the slough and then the already prepared Aloe Vera gel was evenly applied. For control groups, the ulcers were first washed with normal saline to remove off the slough and then covered with a sterile cotton gage, and the wound was tightly bandaged with a cotton roll to keep the "daily dressing" in place. A visual pain scale was used to assess the patient's pain level. Data analysis was done using SPSS 17. Descriptive statistics, ANOVA, and greenhouse tests were used. The significance level was 0.05. RESULTS: The results showed that the average pain score in both groups had a downward trend; that is, both dressings effectively reduced pressure ulcer pain (P < 0.001). The greenhouse test results showed that the difference between the two groups was significant (P < 0.001). CONCLUSION: The results showed the effect of Aloe Vera gel in reducing pressure ulcer pain. Dressing with Aloe Vera gel is preferable to reducing pain during dressing changes in patients with pressure ulcers. TRIAL REGISTRATION: Iranian Registry of Clinical Trials IRCT20180715040478N2, 2021-08-17.