231 research outputs found
Associated risk factors of STIs and multiple sexual relationships among youths in Malawi
Having unprotected sex with multiple sexual partners (MSP) is the greatest risk factor for human immunodeficiency virus (HIV) and other sexually transmitted infections (STIs) among youths. Young people with MSPs are less likely to use a condom and the greater the risk for STIs. This study examines the associated risk factors of STIs and multiple sexual partnerships among youths aged 15–24 years.
The Malawi Demographic Health Survey 2010 data was used. Out of a sample of 2,987 males and 9,559 females aged 15–24 years, 2,026 males and 6,470 females were considered in the study. Chi square test and logistic regression techniques were performed. Analysis was performed using Statistical Package for Social Sciences (SPSS) version 22.Article writing fellowships were received from the Research Development Office, University of the Western Cape, 7535 Bellville, Cape Town, South Africa.Web of Scienc
Translational toxicology in setting occupational exposure limits for dusts and hazard classification – a critical evaluation of a recent approach to translate dust overload findings from rats to humans
Background
We analyze the scientific basis and methodology used by the German MAK Commission in their recommendations for exposure limits and carcinogen classification of “granular biopersistent particles without known specific toxicity” (GBS). These recommendations are under review at the European Union level. We examine the scientific assumptions in an attempt to reproduce the results. MAK’s human equivalent concentrations (HECs) are based on a particle mass and on a volumetric model in which results from rat inhalation studies are translated to derive occupational exposure limits (OELs) and a carcinogen classification.
Methods
We followed the methods as proposed by the MAK Commission and Pauluhn 2011. We also examined key assumptions in the metrics, such as surface area of the human lung, deposition fractions of inhaled dusts, human clearance rates; and risk of lung cancer among workers, presumed to have some potential for lung overload, the physiological condition in rats associated with an increase in lung cancer risk.
Results
The MAK recommendations on exposure limits for GBS have numerous incorrect assumptions that adversely affect the final results. The procedures to derive the respirable occupational exposure limit (OEL) could not be reproduced, a finding raising considerable scientific uncertainty about the reliability of the recommendations. Moreover, the scientific basis of using the rat model is confounded by the fact that rats and humans show different cellular responses to inhaled particles as demonstrated by bronchoalveolar lavage (BAL) studies in both species.
Conclusion
Classifying all GBS as carcinogenic to humans based on rat inhalation studies in which lung overload leads to chronic inflammation and cancer is inappropriate. Studies of workers, who have been exposed to relevant levels of dust, have not indicated an increase in lung cancer risk. Using the methods proposed by the MAK, we were unable to reproduce the OEL for GBS recommended by the Commission, but identified substantial errors in the models. Considerable shortcomings in the use of lung surface area, clearance rates, deposition fractions; as well as using the mass and volumetric metrics as opposed to the particle surface area metric limit the scientific reliability of the proposed GBS OEL and carcinogen classification.International Carbon Black Associatio
Forest biodiversity, ecosystem functioning and the provision of ecosystem services
Forests are critical habitats for biodiversity and they are also essential for the provision of a wide range of ecosystem services that are important to human well-being. There is increasing evidence that biodiversity contributes to forest ecosystem functioning and the provision of ecosystem services. Here we provide a review of forest ecosystem services including biomass production, habitat provisioning services, pollination, seed dispersal, resistance to wind storms, fire regulation and mitigation, pest regulation of native and invading insects, carbon sequestration, and cultural ecosystem services, in relation to forest type, structure and diversity. We also consider relationships between forest biodiversity and multifunctionality, and trade-offs among ecosystem services. We compare the concepts of ecosystem processes, functions and services to clarify their definitions. Our review of published studies indicates a lack of empirical studies that establish quantitative and causal relationships between forest biodiversity and many important ecosystem services. The literature is highly skewed; studies on provisioning of nutrition and energy, and on cultural services, delivered by mixed-species forests are under-represented. Planted forests offer ample opportunity for optimising their composition and diversity because replanting after harvesting is a recurring process. Planting mixed-species forests should be given more consideration as they are likely to provide a wider range of ecosystem services within the forest and for adjacent land uses. This review also serves as the introduction to this special issue of Biodiversity and Conservation on various aspects of forest biodiversity and ecosystem services
How Close Do We Live to Water? A Global Analysis of Population Distance to Freshwater Bodies
Traditionally, people have inhabited places with ready access to fresh water.
Today, over 50% of the global population lives in urban areas, and water
can be directed via tens of kilometres of pipelines. Still, however, a large
part of the world's population is directly dependent on access to natural
freshwater sources. So how are inhabited places related to the location of
freshwater bodies today? We present a high-resolution global analysis of how
close present-day populations live to surface freshwater. We aim to increase the
understanding of the relationship between inhabited places, distance to surface
freshwater bodies, and climatic characteristics in different climate zones and
administrative regions. Our results show that over 50% of the
world's population lives closer than 3 km to a surface freshwater body, and
only 10% of the population lives further than 10 km away. There are,
however, remarkable differences between administrative regions and climatic
zones. Populations in Australia, Asia, and Europe live closest to water.
Although populations in arid zones live furthest away from freshwater bodies in
absolute terms, relatively speaking they live closest to water considering the
limited number of freshwater bodies in those areas. Population distributions in
arid zones show statistically significant relationships with a combination of
climatic factors and distance to water, whilst in other zones there is no
statistically significant relationship with distance to water. Global studies on
development and climate adaptation can benefit from an improved understanding of
these relationships between human populations and the distance to fresh
water
Palaeoclimatic conditions in the Mediterranean explain genetic diversity of Posidonia oceanica seagrass meadows
Past environmental conditions in the Mediterranean Sea have been proposed as main drivers of the current patterns of distribution of genetic structure of the seagrass Posidonia oceanica, the foundation species of one of the most important ecosystems in the Mediterranean Sea. Yet, the location of cold climate refugia (persistence regions) for this species during the Last Glacial Maximum (LGM) is not clear, precluding the understanding of its biogeographical history. We used Ecological Niche Modelling together with existing phylogeographic data to locate Pleistocene refugia in the Mediterranean Sea and to develop a hypothetical past biogeographical distribution able to explain the genetic diversity presently found in P. oceanica meadows. To do that, we used an ensemble approach of six predictive algorithms and two Ocean General Circulation Models. The minimum SST in winter and the maximum SST in summer allowed us to hindcast the species range during the LGM. We found separate glacial refugia in each Mediterranean basin and in the Central region. Altogether, the results suggest that the Central region of the Mediterranean Sea was the most relevant cold climate refugium, supporting the hypothesis that long-term persistence there allowed the region to develop and retain its presently high proportion of the global genetic diversity of P. oceanica.Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) [SFRH/BPD/85040/2012]; FCT [UID/Multi/04326/2013, FCT-BIODIVERSA/004/2015]; Pew foundation (USA)info:eu-repo/semantics/publishedVersio
213Bi-PAI2 conjugate selectively induces apoptosis in PC3 metastatic prostate cancer cell line and shows anti-cancer activity in a xenograft animal model
A novel α-particle emitting (213Bi) plasminogen activator inhibitor type 2 construct, which targets the membrane-bound urokinase plasminogen activator on prostate cancer cells, was prepared and evaluated in vitro and in a xenograft animal model. The PC3 prostate cancer cell line expresses urokinase plasminogen activator which binds to its receptor on the cell membrane; plasminogen activator inhibitor type 2 is bound to urokinase plasminogen activator/urokinase plasminogen activator receptor to form stable complexes. In vitro, the cytotoxicity of 213Bi-plasminogen activator inhibitor type 2 against prostate cancer cells was tested using the MTS assay and apoptosis was documented using terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end-labelling (TUNEL) assay. In vivo, antiproliferative effects for tumours and prostate cancer lymph node metastasis were carried out in an athymic nude mouse model with a subcutaneous xenograft of PC3 cells. 213Bi-plasminogen activator inhibitor type 2 was specifically cytotoxic to PC3 cells in a concentration-dependent fashion, causing the cells to undergo apoptosis. A single local or i.p. injection of 213Bi-plasminogen activator inhibitor type 2 was able to completely regress the growth of tumours and lymph node metastases 2 days post subcutaneous inoculation, and obvious tumour regression was achieved in the therapy groups compared with control groups with 213Bi-plasminogen activator inhibitor type 2 when the tumours measured 30–40 mm3 and 85–100 mm3. All control animals and one of five (20%) mice treated with 3 mCi kg−1 213Bi-plasminogen activator inhibitor type 2 developed metastases in the lymph nodes while no lymphatic spread of cancer was found in the 6 mCi kg−1 treated groups at 2 days and 2 weeks post-cell inoculation. These results demonstrate that this novel 213Bi-plasminogen activator inhibitor type 2 conjugate selectively targets prostate cancer in vitro and in vivo, and could be considered for further development for the therapy of prostate cancer, especially for the control of micro-metastases or in minimal residual disease
Contrasting signals from multiple markers illuminate population connectivity in a marine fish
Recent advances in molecular biology and bioinformatics have helped to unveil striking and previously unrecognized patterns of geographic genetic structure in marine populations. Largely driven by the pressing needs of fisheries management and conservation, studies on marine fish populations have played a pivotal role in testing the efficiency of a range of approaches to explore connectivity and dispersal at sea. Here, we employed nuclear and mitochondrial DNA markers and parasitic infestations to examine the nature and patterns of population structure in a warm-temperate coastal marine teleost across major putative biogeographic barriers in the Mediterranean Sea and Eastern Atlantic Ocean. We detected deep genetic divergence between mitochondrial lineages, likely caused by dramatic climatic and geological transformations before and during the Pleistocene. Such long-diverged lineages later came into secondary contact and can now be found in sympatry. More importantly, microsatellite data revealed that these lineages, after millions of years of independent evolution, now interbreed extensively. By combining genetic and parasite data, we were able to identify at least five independent demographic units. While the different genetic and parasite-based methods produce notably contrasting signals and may complicate the reconstruction of connectivity dynamics, we show that by tailoring the correct interpretation to each of the descriptors used, it is possible to achieve a deeper understanding of the micro-evolutionary process and, consequently, resolve population structure
124I-L19-SIP for immuno-PET imaging of tumour vasculature and guidance of 131I-L19-SIP radioimmunotherapy
Purpose: The human monoclonal antibody (MAb) fragment L19-SIP is directed against extra domain B (ED-B) of fibronectin, a marker of tumour angiogenesis. A clinical radioimmunotherapy (RIT) trial with 131 I-L19-SIP was recently started. In the present study, after GMP production of 124 I and efficient production of 124 I-L19-SIP, we aimed to demonstrate the suitability of 124 I-L19-SIP immuno-PET for imaging of angiogenesis at early-stage tumour development and as a scouting procedure prior to clinical 131 I-L19-SIP RIT. Methods: 124 I was produced in a GMP compliant way via 124 Te(p,n) 124 I reaction and using a TERIMO™ module for radioiodine separation. L19-SIP was radioiodinated by using a modified version of the IODO-GEN method. The biodistribution of coinjected 124 I- and 131 I-L19-SIP was compared in FaDu xenograft-bearing nude mice, while 124 I PET images were obtained from mice with tumours of 90%, respectively. Tumour uptake was 7.3±2.1, 10.8±1.5, 7.8±1.4, 5.3±0.6 and 3.1±0.4%ID/g at 3, 6, 24, 48 and 72 h p.i., resulting in increased tumour to blood ratios ranging from 6.0 at 24 h to 45.9 at 72 h p.i.. Fully concordant labelling and biodistribu- tion results were obtained with 124 I- and 131 I-L19-SIP. Immuno-PET with 124 I-L19-SIP using a high-resolution research tomograph PET scanner revealed clear delineation of the tumours as small as 50 mm3 and no adverse uptake in other organs. Conclusions: 124 I-MAb conjugates for clinical immuno-PET can be efficiently produced. Immuno-PET with 124 I-L19-SIP appeared qualified for sensitive imaging of tumour neo- vasculature and for predicting 131 I-L19-SIP biodistribution.ISSN:1619-7070ISSN:1619-708
Preclinical studies of targeted α therapy for breast cancer using 213Bi-labelled-plasminogen activator inhibitor type 2
Cell Death or Survival Promoted by Alternative Isoforms of ErbB4
The report demonstrates that two distinct isoforms of the ErbB4 receptor tyrosine kinase stimulate either proliferation or apoptosis by mechanisms involving differential transcriptional regulation of the PDGFRA gene. These data have implications for developing approaches to target ErbB4 signaling in cancer
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