Calcium phosphate (CaP) has traditionally been used for the repair of bone defects because of its strong resemblance to the inorganic phase of bone matrix. Nowadays, a variety of natural or synthetic ...CaP-based biomaterials are produced and have been extensively used for dental and orthopaedic applications. This is justified by their biocompatibility, osteoconductivity and osteoinductivity (i.e. the intrinsic material property that initiates de novo bone formation), which are attributed to the chemical composition, surface topography, macro/microporosity and the dissolution kinetics. However, the exact molecular mechanism of action is unknown. This review paper first summarizes the most important aspects of bone biology in relation to CaP and the mechanisms of bone matrix mineralization. This is followed by the research findings on the effects of calcium (Ca2+) and phosphate (PO43-) ions on the migration, proliferation and differentiation of osteoblasts during in vivo bone formation and in vitro culture conditions. Further, the rationale of using CaP for bone regeneration is explained, focusing thereby specifically on the material’s osteoinductive properties. Examples of different material forms and production techniques are given, with the emphasis on the state-of-the art in fine-tuning the physicochemical properties of CaP-based biomaterials for improved bone induction and the use of CaP as a delivery system for bone morphogenetic proteins. The use of computational models to simulate the CaP-driven osteogenesis is introduced as part of a bone tissue engineering strategy in order to facilitate the understanding of cell–material interactions and to gain further insight into the design and optimization of CaP-based bone reparative units. Finally, limitations and possible solutions related to current experimental and computational techniques are discussed.
SALL4,
which is expressed in fetal but not adult liver, is reexpressed in a subgroup of hepatocellular cancers associated with a poor prognosis. In mice, treatment aimed at inhibiting
SALL4
has ...antitumor effects.
Hepatocellular carcinoma is the third leading cause of cancer-related deaths globally. Although the epidemiologic risk factors for hepatocellular carcinoma are well known,
1
the molecular mechanisms underlying hepatocarcinogenesis are not well characterized. Elucidation of these mechanisms may allow identification of new candidates for therapeutic targeting. Although surgery, liver transplantation, and radiologic intervention may be viable options for patients with early-stage disease, the prognosis associated with advanced-stage hepatocellular carcinoma remains bleak.
2
Combination chemotherapy has not improved overall survival but has nonetheless been in wide use for many years because of its possible role in palliation. The need to understand the molecular pathogenesis . . .
Poultry CHAI, S. J.; COLE, D.; NISLER, A. ...
Epidemiology and infection,
01/2017, Letnik:
145, Številka:
2
Journal Article
Recenzirano
Odprti dostop
As poultry consumption continues to increase worldwide, and as the United States accounts for about one-third of all poultry exports globally, understanding factors leading to poultry-associated ...foodborne outbreaks in the United States has important implications for food safety. We analysed outbreaks reported to the United States' Foodborne Disease Outbreak Surveillance System from 1998 to 2012 in which the implicated food or ingredient could be assigned to one food category. Of 1114 outbreaks, poultry was associated with 279 (25%), accounting for the highest number of outbreaks, illnesses, and hospitalizations, and the second highest number of deaths. Of the 149 poultry-associated outbreaks caused by a confirmed pathogen, Salmonella enterica (43%) and Clostridium perfringens (26%) were the most common pathogens. Restaurants were the most commonly reported location of food preparation (37% of poultry-associated outbreaks), followed by private homes (25%), and catering facilities (13%). The most commonly reported factors contributing to poultry-associated outbreaks were food-handling errors (64%) and inadequate cooking (53%). Effective measures to reduce poultry contamination, promote safe food-handling practices, and ensure food handlers do not work while ill could reduce poultry-associated outbreaks and illnesses.
Chondrogenic mesenchymal stem cells (MSCs) have not yet been used to address the clinical demands of large osteochondral joint surface defects. In this study, self-assembling tissue intermediates ...(TIs) derived from human periosteum-derived stem/progenitor cells (hPDCs) were generated and validated for stable cartilage formation in vivo using two different animal models.
hPDCs were aggregated and cultured in the presence of a novel growth factor (GF) cocktail comprising of transforming growth factor (TGF)-β1, bone morphogenetic protein (BMP)2, growth differentiation factor (GDF)5, BMP6, and fibroblast growth factor (FGF)2. Quantitative polymerase chain reaction (PCR) and immunohistochemistry were used to study in vitro differentiation. Aggregates were then implanted ectopically in nude mice and orthotopically in critical-size osteochondral defects in nude rats and evaluated by microcomputed tomography (µCT) and immunohistochemistry.
Gene expression analysis after 28 days of in vitro culture revealed the expression of early and late chondrogenic markers and a significant upregulation of NOGGIN as compared to human articular chondrocytes (hACs). Histological examination revealed a bilayered structure comprising of chondrocytes at different stages of maturity. Ectopically, TIs generated both bone and mineralized cartilage at 8 weeks after implantation. Osteochondral defects treated with TIs displayed glycosaminoglycan (GAG) production, type-II collagen, and lubricin expression. Immunostaining for human nuclei protein suggested that hPDCs contributed to both subchondral bone and articular cartilage repair.
Our data indicate that in vitro derived osteochondral-like tissues can be generated from hPDCs, which are capable of producing bone and cartilage ectopically and behave orthotopically as osteochondral units.
In the urban area of Guangzhou, observations on aerosol light extinction effect were conducted at a monitoring site of the South China Institute of Environmental Sciences (SCIES) during April 2009, ...July 2009, October 2009 and January 2010. The main goal of these observations is to recognise the impact of relative humidity (RH) and particles number distribution on aerosol light extinction. PM sub(2.5) was sampled by Model PQ200 air sampler; ions and OC/EC in PM sub(2.5) were identified by the Dionex ion chromatography and the DRI model 2001 carbon analyser, respectively; particles number size distribution was measured by TSI 3321 APS, while total light scattering coefficient was measured by TSI 3563 Nephelometer. Chemical composition of PM sub(2.5) was reconstructed by the model ISORROPIA II. As a result, possible major components in PM sub(2.5) were (NH sub(4)) sub(2)SO sub(4), Na sub(2)SO sub(4), K sub(2)SO sub(4), NH sub(4)NO sub(3), HNO sub(3), water, POM and EC. Regarding ambient RH, mass concentration of PM sub(2.5) ranged from 26.1 to 279.1 mu g m super(-3) and had an average of 94.8, 44.6, 95.4 and 130.8 mu g m super(-3) in April, July, October and January, respectively. With regard to the total mass of PM sub(2.5), inorganic species, water, POM, EC and the Residual accounted for 34-47%, 19-31%, 14-20%, 6-8% and 8-17%, respectively. Under the assumption of "internal mixture", optical properties of PM sub(0.5-20) were estimated following the Mie Model. Optical refractive index, hygroscopic growth factor and the dry aerosol density required by the Mie Model were determined with an understanding of chemical composition of PM sub(2.5). With these three parameters and the validated particles number size distribution of PM sub(0.5-20), the temporal variation trend of optical property of PM sub(0.5-20) was estimated with good accuracy. The highest average of b sub(ep,pm0.5-20) was 300 Mm super(-1) in April while the lowest one was 78.6 Mm super(-1) in July. Regarding size distribution of b sub(ep,pm0.5-20), peak value was almost located in the diameter range between 0.5 and 1.0 mu m. Furthermore, hygroscopic growth of optical properties of PM sub(0.5-20) largely depended on RH. As RH increased, b sub(ep,pm0.5-20) grew and favoured a more rapid growth when aerosol had a high content of inorganic water-soluble salts. Averagely, f sub(bep,pm0.5-20) enlarged 1.76 times when RH increased from 20% to 90%. With regard to the temporal variation of ambient RH, f sub(bep,pm0.5-20) was 1.29, 1.23, 1.14 and 1.26 on average in April, July, October and January, respectively.
Owing to its high stability in aqueous solution and high quantum efficiency, tantalum based oxyntride (TaON) has attracted increasing attentions for application as visible light photocatalyst. ...However, despite the recent progress in photocatalytic studies, its bulk charge transport mechanisms are yet to be discovered because of the lack of single crystal sample. In this paper, high quality single crystalline TaON(100) thin film was prepared on cubic YSZ(100) surface by reactive RF magnetron sputtering to avail the understandings of charge transport mechanism so as to improve the device efficiency. The stoichiometry, crystal phase and structure were examined in situ by x-ray photoelectron spectroscopy (XPS) and ex situ by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The TaON film crystallizes in monoclinic β-phase with its 010/001 directions aligned to those of the substrate. The small band gap of 2.5eV as well as the high structure perfection suggests better performance for visible light water splitting. The method can be used to prepare other surface orientations to elucidate fundamental surface structure dependent photoactivities.
Structure of single crystalline β-TaON and its diffraction pole figure. Display omitted
•High quality single crystal TaON(100) thin film were grown on YSZ(100) surface.•β-phase monoclinic TaON film is formed.•Its 010/001 directions are aligned to those of the substrate.•The small band gap and structure perfection suggest visible light photo-activity.
California has a large population of people experiencing homelessness (PEH) that is characterised by a high proportion of people who are unsheltered and chronically homeless. PEH are at increased ...risk of communicable diseases due to multiple, intersecting factors, including increased exposures, comorbid conditions including substance use disorder and mental illness and lack of access to hygiene and healthcare facilities. Data available for several communicable diseases show that PEH in California experiences an increased burden of communicable diseases compared to people not experiencing homelessness. Public health agencies face unique challenges in serving this population. Efforts to reduce homelessness, increase access to health care for PEH, enhance data availability and strengthen partnerships among agencies serving PEH can help reduce the disparity in communicable disease burden faced by PEH.
Early in a foodborne disease outbreak investigation, illness incubation periods can help focus case interviews, case definitions, clinical and environmental evaluations and predict an aetiology. Data ...describing incubation periods are limited. We examined foodborne disease outbreaks from laboratory-confirmed, single aetiology, enteric bacterial and viral pathogens reported to United States foodborne disease outbreak surveillance from 1998-2013. We grouped pathogens by clinical presentation and analysed the reported median incubation period among all illnesses from the implicated pathogen for each outbreak as the outbreak incubation period. Outbreaks from preformed bacterial toxins (Staphylococcus aureus, Bacillus cereus and Clostridium perfringens) had the shortest outbreak incubation periods (4-10 h medians), distinct from that of Vibrio parahaemolyticus (17 h median). Norovirus, salmonella and shigella had longer but similar outbreak incubation periods (32-45 h medians); campylobacter and Shiga toxin-producing Escherichia coli had the longest among bacteria (62-87 h medians); hepatitis A had the longest overall (672 h median). Our results can help guide diagnostic and investigative strategies early in an outbreak investigation to suggest or rule out specific etiologies or, when the pathogen is known, the likely timeframe for exposure. They also point to possible differences in pathogenesis among pathogens causing broadly similar syndromes.
We report on the demonstration of photodetectors based on large scale two-dimensional molybdenum disulfide (MoS2) transition metal dichalcogenides. Excellent film uniformity and precise control of ...the MoS2 thickness down to a monolayer (~0.75nm) were achieved by magnetron sputtering synthesis approach. In particular, the photodetectors integrated with five MoS2 monolayers exhibit a high photoresponsivity of 1.8 A/W, an external quantum efficiency exceeding 260%, and a photodetectivity of ~5 x 10(8) Jones for a wavelength of 850 nm, surpassing the performance of mechanically exfoliated based photodetectors.
In underground tunnels, caverns or pillar goaf, the time-dependent deformation or failure of the rock or coal mass is a major safety concern, which affects the mechanical properties and stability of ...the coal and rock in the underground excavations. However, the damage surrounding rock or coal usually occurs from the time mining starts. This initial damage is rarely considered during the current creep tests used for coal. In the present study, an experimental specimen processing method to identify the initial damage to a coal deposit is suggested. The effect of the strain history on the deformation of coal samples with initial damage during multi-level loading triaxial compression creep tests was studied. The laboratory tests showed that the strain versus creep curve of the coal samples experiences three typical creep stages of deceleration creep in the early stage, constant velocity creep in the medium term and catastrophic accelerated creep in the later stage. With the increase in initial damage, it was observed the gradual decrease in total creep time, deviating stress of creep failure, stress threshold of accelerated creep and starting time of the volume expansion. When the initial damage value increased from 0.0 to 0.50, the deviating stress of creep failure, stress threshold of accelerated creep and starting time of the volume expansion of the coal decreased by 42.3%, 48.5% and 51.4%, respectively. The study is of great significance to conduct researches on the deformation, mechanical characteristics and long-term strength of coal pillar with initial damages under long-term pressure, and also provides insight into the underground excavations and the design of supports to the opneings under such disturbance.
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