The development of collagen hydrogels with tailored properties for improved applications in biomedicine represents an area of opportunity for materials science. The collagen can form ...semi‐interpenetrated networks (semi‐IPN) with various natural and/or synthetic polymers. This work aims the preparation of novel hydrogels generated from a collagen matrix cross‐linked with polyurethane (PU), and the subsequent inclusion of polysaccharide chains to form semi‐IPN systems with improved properties. The choice of polysaccharides for this purpose is related to their ability to modulate the biocompatibility and the antibacterial capacity in various biomedical strategies. The work contemplates to study the effect of the chemical structure of polysaccharide (hydroxyethylcellulose (HEC), hydroxypropylmethylcellulose (HPMC) or starch (Alm)) on the properties of these novel hydrogels. The results indicate that the semi‐IPN hydrogels that include Alm exhibit the formation of stronger intermolecular interactions promoted by hydrogen bonds than HEC and HPMC, significantly improving the mechanical properties and their degradation rate in acidic, alkaline, and proteolytic media; also showing high capacity to inhibit the growth of E. colli. The semi‐IPN hydrogels based on HEC and HPMC exhibit excellent improvement in both thermal and proteolytic degradation, compared with the collagen‐PU matrix. On the other hand, this semi‐IPN system does not present cytotoxic character for monocytes and fibroblasts growing for up to 48 h of culture. Therefore, these innovative 3D matrices will be excellent candidates with potential application in biomedical strategies such as wound healing dressings.
Most people with diabetes suffer some deterioration of the feet. Diabetic foot syndrome causes ulceration in about 15% of cases and such deterioration leads to amputation in about 2.5% of diabetic ...patients, diminishing their quality of life and generating extraordinary costs for patients and public health systems. Currently, there is no objective method for the detection of diabetic foot syndrome in its early stages. We propose terahertz imaging as a method for the evaluation of such deterioration. This screening method could aid the prevention and medical treatment of this condition in the future.
Diabetic retinopathy (DR) is the most common microvascular complication in diabetic patients and one of the main causes of acquired blindness in the world. From the 90s until date, the incidence of ...this complication has increased. Reactive oxygen species (ROS) is a free radical with impaired electron that usually participates in the redox mechanisms of some body molecules such as enzymes, proteins, and so on. In normal biological conditions, ROS is maintained in equilibrium, however its overproduction can lead to biological process called oxidative stress and this is considered the main pathogenesis of DR. The retina is susceptible to ROS because of high-energy demands and exposure to light. When the balance is broken, ROS produces retinal cell injury by interacting with the cellular components. This article describes the possible role of oxidative stress in the development of DR and proposes some treatment options based on its stages. The review of the topic shows that blindness caused by DR can be avoided by early detection and timely treatment.
Pancreatic cancer is the fourth most common cause of cancer-related deaths in the United States, with over 38000 deaths in 2013. The opportunity to detect pancreatic cancer while it is still curable ...is dependent on our ability to identify and screen high-risk populations before their symptoms arise. Risk factors for developing pancreatic cancer include multiple genetic syndromes as well as modifiable risk factors. Genetic conditions include hereditary breast and ovarian cancer syndrome, Lynch Syndrome, familial adenomatous polyposis, Peutz-Jeghers Syndrome, familial atypical multiple mole melanoma syndrome, hereditary pancreatitis, cystic fibrosis, and ataxia-telangiectasia; having a genetic predisposition can raise the risk of developing pancreatic cancer up to 132-fold over the general population. Modifiable risk factors, which include tobacco exposure, alcohol use, chronic pancreatitis, diet, obesity, diabetes mellitus, as well as certain abdominal surgeries and infections, have also been shown to increase the risk of pancreatic cancer development. Several largevolume centers have initiated such screening protocols, and consensus-based guidelines for screening high-riskgroups have recently been published. The focus of this review will be both the genetic and modifiable risk factors implicated in pancreatic cancer, as well as a review of screening strategies and their diagnostic yields.
Menopause accelerates biological aging Levine, Morgan E.; Lu, Ake T.; Chen, Brian H. ...
Proceedings of the National Academy of Sciences - PNAS,
08/2016, Letnik:
113, Številka:
33
Journal Article
Recenzirano
Odprti dostop
Although epigenetic processes have been linked to aging and disease in other systems, it is not yet known whether they relate to reproductive aging. Recently, we developed a highly accurate ...epigenetic biomarker of age (known as the “epigenetic clock”), which is based on DNA methylation levels. Here we carry out an epigenetic clock analysis of blood, saliva, and buccal epithelium using data from four large studies: the Women’s Health Initiative (n = 1,864); Invecchiare nel Chianti (n = 200); Parkinson’s disease, Environment, and Genes (n = 256); and the United Kingdom Medical Research Council National Survey of Health and Development (n = 790). We find that increased epigenetic age acceleration in blood is significantly associated with earlier menopause (P = 0.00091), bilateral oophorectomy (P = 0.0018), and a longer time since menopause (P = 0.017). Conversely, epigenetic age acceleration in buccal epithelium and saliva do not relate to age at menopause; however, a higher epigenetic age in saliva is exhibited in women who undergo bilateral oophorectomy (P = 0.0079), while a lower epigenetic age in buccal epithelium was found for women who underwent menopausal hormone therapy (P = 0.00078). Using genetic data, we find evidence of coheritability between age at menopause and epigenetic age acceleration in blood. Using Mendelian randomization analysis, we find that two SNPs that are highly associated with age at menopause exhibit a significant association with epigenetic age acceleration. Overall, our Mendelian randomization approach and other lines of evidence suggest that menopause accelerates epigenetic aging of blood, but mechanistic studies will be needed to dissect cause-and-effect relationships further.
Quantum wells formed by layers of HgTe between HgFormula: see textCdFormula: see textTe barriers lead to two-dimensional (2D) topological insulators, as predicted by the BHZ model. Here, we ...theoretically and experimentally investigate the characteristics of triple HgTe quantum wells. We describe such heterostructure with a three dimensional Formula: see text Kane model, and use its eigenstates to derive an effective 2D Hamiltonian for the system. From these we obtain a phase diagram as a function of the well and barrier widths and we identify the different topological phases composed by zero, one, two, and three sets of edge states hybridized along the quantum wells. The phase transitions are characterized by a change of the spin Chern numbers and their corresponding band inversions. Complementary, transport measurements are experimentally investigated on a sample close to the transition line between the phases with one and two sets of edges states. Accordingly, for this sample we predict a gapless spectrum with low energy bulk conduction subbands given by one parabolic and one Dirac subband, and with edge states immersed in the bulk valence subbands. Consequently, we show that under these conditions, local and non-local transport measurements are inconclusive to characterize a sole edge state conductivity due to bulk conductivity. On the other hand, Shubnikov-de Haas (SdH) oscillations show an excellent agreement with our theory. Particularly, we show that the measured SdH oscillation frequencies agrees with our model and show clear signatures of the coexistence of a parabolic and Dirac subbands.
Objective
To evaluate the reasons for COVID‐19 vaccine hesitancy during pregnancy.
Design
We used regular expressions to identify publicly available social media posts from pregnant people expressing ...at least one reason for their decision not to accept COVID‐19 vaccine.
Setting
Two social media platforms – WhatToExpect and Twitter.
Sample
A total of 945 pregnant people in WhatToExpect (1017 posts) and 345 pregnant people in Twitter (435 tweets).
Methods
Two annotators manually coded posts according to the Scientific Advisory Group for Emergencies (SAGE) working group's 3Cs vaccine hesitancy model (confidence, complacency and convenience barriers). Within each 3Cs we created subthemes that emerged from the data.
Main Outcome Measures
Subthemes were derived according to the people's posting own words.
Results
Safety concerns were most common and largely linked to the perceived speed at which the vaccine was created and the lack of data about its safety in pregnancy. This led to a preference to wait until after the baby was born or to take other precautions instead. Complacency surrounded a belief that they are young and healthy or already had COVID‐19. Misinformation led to false safety and efficacy allegations, or even conspiracy theories, and fed into creating confidence and complacency barriers. Convenience barriers (such as availability) were uncommon.
Conclusion
The information in this study can be used to highlight the questions, fears and hesitations pregnant people have about the COVID‐19 vaccine. Highlighting these hesitations can help public health campaigns and improve communication between healthcare professionals and patients.
This article includes Author Insights, a video available at: https://players.brightcove.net/3806881048001/default_default/index.html?videoId=6322479081112.
The deep-seated infections caused by the
genus are associated with a high mortality rate, and
is the most frequent species associated with these diseases. The fungal wall is composed of ...macromolecules not synthesized by the host, and therefore is a source of ligands recognized by innate immune cells.
We performed a comparative study analyzing the cell wall composition and organization of
,
, and
, along with their ability to stimulate cytokine production and phagocytosis by human innate immune cells.
We found that the wall of these species had the basic components already described in
, with most of the chitin and b1,3-glucan located underneath the mannan layer. However, the walls of
and
were rich in chitin and the former had a lower content of mannans.
contained changes in the mannan and the b1,3-glucan levels. These species were differentially phagocytosed by human macrophages and stimulated cytokine production in a dectin-1-dependent pathway.
showed the most significant changes in the tested parameters, whereas
behaved like
.
Our results suggest that the cell wall and innate immune recognition of
,
,
, and
is different from that reported for
.
Carbonaceous chondrites record processes of aqueous alteration in the presence of hydrated and hydroxylated minerals, which could have provided a source of water in the inner solar system (Alexander ...et al., 2012, 2013). In this study, thermogravimetric analysis (TGA) was performed on 26 CM chondrites, which cover a range of degree of aqueous alteration from 2.0, such as Meteorite Hills (MET) 01070, to 2.6, such as Queen Alexandra Range (QUE) 97990, in order to quantify their water content. In addition, by measuring the release of volatile elements as a function of temperature, we obtained information on the mineralogy of water-bearing phases and provide indicators of aqueous alteration based on water released by phyllosilicates. These analyses are combined with infrared spectroscopy (IR) made on meteorite pellets heated up to 300°C. The infrared features (–OH band at 3-μm and SiO4 around 10-μm) revealed a correlation with TGA. The two techniques are in agreement with the scheme of aqueous alteration proposed by Rubin et al. (2007) and Alexander et al. (2013) based on phyllosilicate abundance.
The low temperature (200–400°C) mass loss observed in TGA is attributed to Fe-oxy-hydroxydes (ferrihydrite, goethite). However, the proportion of these minerals formed by terrestrial alteration remains unknown. TGA also revealed two anomalous CM chondrites, Pecora Escarpment (PCA) 02012 and PCA 02010. Their TGA curves are significantly different from those of “regular” CMs with little mass loss, which can be related to the dehydration history of these meteorites in response to a heating event (Raman measurements also point toward a thermal event, Quirico et al., 2013). In the case of more mildly heated chondrites, such as with Wisconsin Range (WIS) 91600, the TGA curve presents similar mass loss to the other CMs.
Seven bulk measurements of CR chondrites and 3 measurements of matrix-enriched parts of CR meteorites were also studied by TGA, and confirm the low hydration level of chondrules and a significant alteration of the matrix. The water content of the matrix of the CM 2.6 QUE 97990 was estimated and compared to TGA of the matrix enriched portion of the CR2 EET 92159 and that of Orgueil.
Results suggest a similar aqueous alteration degree between Orgueil and the matrix of CMs (around 25wt.%) and a lower alteration of the CR2 matrix (11wt.% of H2O).
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