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Biological Interactions (biological + interaction)
Selected AbstractsInteractive effect of retinopathy and macroalbuminuria on all-cause mortality, cardiovascular and renal end points in Chinese patients with Type 2 diabetes mellitusDIABETIC MEDICINE, Issue 7 2007P. C. Y. Tong Abstract Aims To examine the effect of albuminuria and retinopathy on the risk of cardiovascular and renal events, and all-cause mortality in patients with Type 2 diabetes. Methods A post-hoc analysis of 4416 Chinese patients without macrovascular complications at baseline (age 57.6 ± 13.3 years). Glomerular filtration rate (eGFR) was estimated by the abbreviated Modification of Diet in Renal Disease Study Group Formula, further adjusted for Chinese ethnicity. Clinical end points were all-cause mortality, cardiovascular events (heart failure or angina, myocardial infarction, lower limb amputation, re-vascularization procedures and stroke) and renal end points (reduction in eGFR by more than 50% or eGFR < 15 ml/min/1.73 m2 or death as a result of renal causes or need for dialysis). Results Compared with individuals without complications, subjects with retinopathy and macroalbuminuria had higher rates of cardiovascular events (14.1 vs. 2.4%), renal events (40.0 vs. 0.8%) and death (9.3 vs. 1.7%, P < 0.001). For composite event of death, cardiovascular and renal events, the presence of retinopathy, microalbuminuria alone, macroalbuminuria alone, retinopathy with microalbuminuria or retinopathy with macroalbuminuria increased the risk [hazard ratio (95% CI)] by 1.61 (1.05 to 2.47; P = 0.04), 1.93 (1.38 to 2.69; P < 0.001), 4.34 (3.02 to 6.22; P < 0.001), 2.59 [1.76 to 3.81; P < 0.001) and 6.83 (4.89 to 9.55; P < 0.001) fold, respectively. The relative excess risk as a result of interaction between retinopathy and macroalbuminuria was 15.31, implying biological interaction in the development of renal events. Conclusions In Chinese patients with Type 2 diabetes, retinopathy interacts with macroalbuminuria to increase the risk of composite cardio-renal events. [source] The biotin-streptavidin interaction can be reversibly broken using water at elevated temperaturesELECTROPHORESIS, Issue 3 2005Anders Holmberg Abstract The biotin-streptavidin system is the strongest noncovalent biological interaction known, having a dissociation constant, Kd, in the order of 4×10,14 M. The strength and specificity of the interaction has led it to be one of the most widely used affinity pairs in molecular, immunological, and cellular assays. However, it has previously been impossible to re-use any streptavidin solid support, since the conditions needed to break the interaction with biotin has led to the denaturation of the streptavidin. Here, we show that a short incubation in nonionic aqueous solutions at temperatures above 70°C can efficiently break the interaction without denaturing the streptavidin tetramer. Both biotin and the streptavidin remain active after dissociation and both molecules can therefore be re-used. The efficiency of the regeneration allowed solid supports with streptavidin to be used many times, here exemplified with the multiple re-use of streptavidin beads used for sample preparation prior to automated DNA sequencing. The results suggest that streptavidin regeneration can be introduced as an improvement in existing methods and assays based on the streptavidin system as well as emerging solid phase applications in fields, such as microfluidics and nanotechnology. [source] Update on Bioabsorbable Stents: From Bench to ClinicalJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2006F.A.C.C., RON WAKSMAN M.D. Permanent metallic stents are associated with limitations such as continued mechanical stress, transfer to the tissue, and continued biological interaction with the surrounding tissue. They are also associated with late stent thrombosis and artifacts when non-invasive technologies such as MRI and MSCT are used. The potential advantages of bioabsorbable polymeric or metallic stents are to leave no stent behind, they are fully compatible with MRI and MSCT imaging, and are not associated with late stent thrombosis. This review covers the different stent programs as they move from bench to bed and clinical trials. Bioabsorbable stents are considered the next frontier of stenting and we will discuss their potential to fulfill this promise in interventional cardiology. [source] The interpretation, assessment and conservation of ecological communitiesECOLOGICAL MANAGEMENT & RESTORATION, Issue 2009David A. Keith Summary Ecological communities are assemblages of species that occur together in space and time. Their properties include composition, structure, habitat, distribution, biological interactions and ecosystem functions. The community concept has a central role in conservation planning, and is a key approach for biodiversity conservation above the species level. The relatively recent application of risk assessment and regulatory systems to conservation of ecological communities has highlighted a number of challenges related to intrinsic uncertainties in the definition, diagnosis and assessment of ecological communities. In this review, I aim to elucidate some key conceptual issues essential to the interpretation of communities. Effective description, diagnosis and assessment of communities rests on an understanding of community theory in relation to environmental gradients and ecosystem dynamics. Continuum and discrete models can both contribute to interpretation of communities for conservation. Different sources of uncertainty are inherent in the key properties that characterize communities. Although some of these are reducible, remaining uncertainty must be incorporated into assessments and decision-making processes for conservation. Protocols for assessing extinction risks of communities address rates of decline in distribution, size of distribution and rates of decline in ecological functions. Some protocols assess these factors in a manner that may be inconsistent with equivalent methods for assessing species. Communities may be viewed in a framework that distinguishes thematic, spatial and temporal scales. These scales influence the outcomes of risk assessment, the benefits and limitations of maps and how well communities perform their function in conservation planning. When applied effectively, ecological communities can be powerful tools for delivering cost-effective outcomes for land-use planning and biodiversity conservation. [source] Pressure plate studies to determine how moisture affects access of bacterial-feeding nematodes to food in soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2002G.W. Yeates Summary Nematode activity in the soil depends on the presence of free water. We conducted pressure plate experiments to understand better how soil matric potential and structural degradation affect the population growth of three bacterial-feeding nematodes (Cephalobus, Pristionchus, Rhabditis). We took undisturbed cores from six soils (sand, silt loam and silty clay loam with four management regimes), and removed all fauna from them. Ten or 30 nematodes were added, and pressures corresponding to soil matric potentials of ,10, ,33, ,50, ,100 or ,1500 kPa were applied for 35 days. The nematodes were then counted. Significant reproduction of all bacterial-feeding nematodes occurred when the diameters of water-filled pores were approximately 1 ,m. This confirms observations using repacked soils and field manipulations. Only for Pristionchus did declining populations match the reduction in total soil porosity related to intensification of land use on the silty clay loam. We had not expected Cephalobus to have the fastest increase in population of the three nematodes in intact soil cores, and our evidence questions the relative importance given to the three nematode families in soil processes. The differing rates of population increase of the three nematodes in the various soils reflect both habitable pore space and trophic interactions. This suggests that the very diversity of nematode assemblages is crucial in the resilience of biological soil processes. That water-filled pores as small as 1 ,m provide suitable spaces for sizeable populations of bacterial-feeding nematodes accords with the observed migration of infective juveniles of trichostrongylid nematodes and mermithids in water films on herbage. Our results imply that assessment of the role of nematodes in soil processes may be a key to the understanding of biological interactions in water films, and the selection pressures on nematode morphology. [source] Trophic role of Atlantic cod in the ecosystemFISH AND FISHERIES, Issue 1 2009Jason S. Link Abstract As the world's oceans continue to undergo drastic changes, understanding the role of key species therein will become increasingly important. To explore the role of Atlantic cod (Gadus morhua Gadidae) in the ecosystem, we reviewed biological interactions between cod and its prey, predators and competitors within six ecosystems taken from a broad geographic range: three are cod-capelin (Mallotus villosus Osmeridae) systems towards cod's northern Atlantic limit (Barents Sea, Iceland and Newfoundland,Labrador), two are more diverse systems towards the southern end of the range (North Sea and Georges Bank,Gulf of Maine), and one is a species-poor system with an unusual physical and biotic environment (Baltic Sea). We attempt a synthesis of the role of cod in these six ecosystems and speculate on how it might change in response to a variety of influences, particularly climate change, in a fashion that may apply to a wide range of species. We find cod prey, predators and competitors functionally similar in all six ecosystems. Conversely, we estimate different magnitudes for the role of cod in an ecosystem, with consequently different effects on cod, their prey and predator populations. Fishing has generally diminished the ecological role of cod. What remains unclear is how additional climate variability will alter cod stocks, and thus its role in the ecosystem. [source] Approaches to detecting gene × gene interaction in Genetic Analysis Workshop 14 pedigreesGENETIC EPIDEMIOLOGY, Issue S1 2005Brion S. Maher Abstract Whether driven by the general lack of success in finding single-gene contributions to complex disease, by increased knowledge about the potential involvement of specific biological interactions in complex disease, or by recent dramatic increases in computational power, a large number of approaches to detect locus × locus interactions were recently proposed and implemented. The six Genetic Analysis Workshop 14 (GAW14) papers summarized here each applied either existing or refined approaches with the goal of detecting gene × gene, or locus × locus, interactions in the GAW14 data. Five of six papers analyzed the simulated data; the other analyzed the Collaborative Study on the Genetics of Alcoholism data. The analytic strategies implemented for detecting interactions included multifactor dimensionality reduction, conditional linkage analysis, nonparametric linkage correlation, two-locus parametric linkage analysis, and a joint test of linkage and association. Overall, most of the groups found limited success in consistently detecting all of the simulated interactions due, in large part, to the nature of the generating model. Genet. Epidemiol. 29(Suppl. 1):S116,S119, 2005. © 2005 Wiley-Liss, Inc. [source] Climate control on the long-term anomalous changes of zooplankton communities in the Northwestern MediterraneanGLOBAL CHANGE BIOLOGY, Issue 1 2008JUAN CARLOS MOLINERO Abstract In marine ecosystems, pelagic copepods, chaetognaths and jellyfish play a key role in matter and energy flow. While copepods support most food webs and the biological pump of carbon into the deep ocean, chaetognaths and jellyfish may affect the strength of the top-down control upon plankton communities. In this study, we show that the main events in the long-term variability of these functional groups in the Northwestern Mediterranean were tightly linked to changes of climate forcing of the North Atlantic sector. Large-scale climate forcing has altered the pelagic food-web dynamics through changes in biological interactions, competition and predation, leading to substantial changes manifested as bursts or collapses in zooplankton populations, and consequently to a major change ca. 1987. These events become more frequent in the 1980s and the early 1990s in the studied zooplankton functional groups suggesting a shift in the functioning of the pelagic ecosystem. The environmental modifications and the results reported here are therefore, indicators of a regime change pointing to a more regeneration-dominated system in the study area. We suggest a chain of mechanisms, whereby climate variation has modified the long-term dynamics of pelagic copepods, chaetognaths and jellyfish in the Ligurian Sea. [source] From agriculture based on fossil fuel resources to agriculture based on biological interactions and matter cycling in agroecosystemsGRASSLAND SCIENCE, Issue 1 2005Masae Shiyomi Abstract The modern system of agriculture, which depends on the consumption of large quantities of fossil fuel, will be forced to change to a system in which matter cycling and the various interactions operating among organisms and between organisms and their environment are effectively used. Three key factors will necessitate this change: the depletion of readily available fossil fuel resources; the leveling-off of the growth and yield response of crops in response to the increase in the use of fertilizers, agrochemicals and big machinery; and the degradation of the environment associated with the consumption of fossil fuels and derived agrochemicals. Therefore, it is essential to further promote the following two types of study: (i) the elucidation of the structure and use of complex biological interactions, and the cause-and-effect relationships among and between organisms in relation to their environment; and (ii) the effective use of matter cycling in agricultural ecosystems. Efficient use of biological interactions and matter cycling will reduce the dependence of agriculture on fossil fuel. [source] Spatial Distribution and Coexistence Patterns of Caddisfly Larvae (Trichoptera) in a Hungarian StreamINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2004Dénes Schmera Abstract It is well known that stream macroinvertebrates usually show aggregated spatial distributions caused by extrinsic factors and interactions among species and individuals. In the present study, the spatial distribution of caddisfly assemblages and coexistence patterns of larval caddisfly species (Insecta: Trichoptera) were measured in a Hungarian stream reach at three different spatial scales. Caddisfly assemblages showed aggregated, random and regular distributions as measured by the variance-mean relationship of species richness as sampling area increased from 0.0225 m2 to 0.2025 m2. The observed coexistence patterns indicated interactions (lower diversity of unique species combinations than expected by chance) among species for aggregated distributions. These interactions among species proved to be positive associations particularly among species belonging to the same functional feeding group. The positive associations and the aggregated distribution of caddisflies supported the hypothesis that microhabitat patches (patchy microhabitat-macroinvertebrate model) and/or positive biological interactions among species using the same resource (hypothesis of facilitation) have a deterministic effect on the spatial distribution of caddisfly assemblages. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Teretrius nigrescens against larger grain borer Prostephanus truncatus in African maize stores: biological control at work?JOURNAL OF APPLIED ECOLOGY, Issue 2 2003Niels Holst Summary 1Following the accidental introduction of the bostrichid beetle Prostephanus truncatus into East and West Africa around 1980, a classical biological control campaign was launched in 1991; the histerid beetle Teretrius nigrescens was released as a biocontrol agent to prevent the destructive outbreak of the pest in small-farm maize stores. However, while the campaign has been ongoing, so has discussion in the scientific community about the merits of this campaign and its chances of success. 2From published and unpublished data from experimental maize stores in Benin, West Africa, we derived statistical models describing the in-store insect population dynamics, and were thus able to point out significant biological interactions and to explain the observed lack of biological control. 3We found that (i) T. nigrescens reduced significantly the population growth rate of both P. truncatus and the non-target pest, the weevil Sitophilus zeamais; (ii) T. nigrescens displayed a positive numerical response to both prey species, P. truncatus and S. zeamais; (iii) asymmetric competition existed between the two prey species, S. zeamais was negatively affected by P. truncatus but not vice versa; (iv) T. nigrescens and S. zeamais displayed negative intraspecific density-dependence whereas P. truncatus was resource-limited. 4We conclude that classical biological control with T. nigrescens is not likely to become successful, mainly due to the predator's intraspecific density-dependence and its low population growth rate compared with its prey. We recommend that further research on P. truncatus integrated pest management takes into account the farmer as an active agent managing the store. 5Synthesis and applications. When biocontrol does not result in satisfactory pest control, as in the case of P. truncatus, farmers should learn how to scout for the pest and take action when a need is detected. In areas where the pest is usually only a minor problem, the agricultural extension service should consider setting up a simple early warning system for their region. When attempts at classical biological control remain unsuccessful, as in the case of P. truncatus now for 10 years, policy-makers should prioritize training of extension service and farmers in integrated pest management techniques (e.g. need-based use of insecticides) as a necessary supplement to biocontrol. [source] Establishing a perimeter position: speciation around the Indian Ocean BasinJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2008G. VOELKER Abstract Historical biological interactions among peripheral landmasses on the periphery of the Indian Ocean Basin (IOB) are generally poorly understood. While interactions based on early Gondwanan vicariance have been used to explain present day lineage distributions, several recent studies have instead inferred dispersal across the IOB. This inference is often advanced because lineages under study have species inhabiting IOB islands. Here we examine the roles of continental vicariance vs. trans-IOB dispersal in the distribution of an avian genus found around the perimeter of the IOB. A molecular phylogeny does reveal evidence of a relationship that would require the inference of trans-IOB dispersal between eastern Africa and Sri Lanka. However, molecular clock data, ancestral area analyses and paleoclimatic reconstructions suggest that vicariance related to tropical forest expansion and retraction is more likely to have facilitated African,Asian interchange, with an initial colonization of Africa from Asia quickly followed by a recolonization of Asia. Subsequent dispersal from Asia to Sri Lanka and islands east of the Sunda Shelf are inferred; these latter islands were colonized in a stepping-stone fashion that culminated in colonization of the Sunda Shelf, and a recolonization of mainland Asia. We propose that circum-IOB distributions, which post-date early Gondwanan breakup, are most likely the result of continent-based vicariant events, particularly those events related to large-scale habitat alterations, and not trans-IOB dispersals. [source] Combinational polymorphisms of four DNA repair genes XRCC1, XRCC2, XRCC3, and XRCC4 and their association with oral cancer in TaiwanJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 5 2008Ching-Yu Yen Background:, Many single nucleotide polymorphisms (SNPs) have been found to be associated with oral cancer but the biological interactions through SNPs are seldom addressed. In this study, we focused on the joint effect for SNP combinations of four DNA repair genes, X-ray repair cross-complementing groups (XRCCs) 1,4, involved in major cancer-related pathways. Methods:, Single nucleotide polymorphism genotyping was determined using by polymerase chain reaction-restriction fragment length polymorphism in this study (case = 103, control = 98). Different numbers of combinational SNPs with genotypes called the pseudo-haplotypes from these chromosome-wide genes were used to evaluate their joint effect on oral cancer risk. Results:, Except for XRCC2 rs2040639-AG, none of these SNPs was found to individually contribute to oral cancer risk. However, for two combined SNPs, the proportion of subjects with oral cancer was significantly higher in the pseudo-haplotype with AG-CC genotypes in rs2040639-rs861539 (XRCC2,XRCC3) compared with those with non-AG-CC genotypes. Similarly, the pseudo-haplotype of rs2040639,rs861539,rs2075685 (XRCC2,XRCC3,XRCC4) and rs2040639,rs861539,rs2075685,rs1799782 (XRCCs 1,4) with specific genotype pattern (AG-CC-TG and CT-AG-CC-TG) among three and four combinational SNPs were significantly associated with oral cancer. After controlling for age, gender, smoking, drinking, and betel nut chewing, the estimated odds ratio of oral cancer were 2.45, 5.03, and 10.10 for two, three and four specific SNP combinations, respectively, comparing these specific pseudo-haplotypes to their corresponding non-pseudo-haplotypes. Conclusion:, We have identified the potential combined XRCCs 1,4 SNPs with genotypes that were associated with oral cancer risk and may have an impact on identification of a high-risk population. [source] Biological foundation for periodontitis as a potential risk factor for atherosclerosisJOURNAL OF PERIODONTAL RESEARCH, Issue 1 2005Yong-Hee P. Chun Objectives:, Links between periodontal diseases and systemic diseases have been well documented by epidemiological studies. Recently, research has shifted to elucidating the biologic mechanism for a causal relationship. One focus of interest is atherosclerosis, the underlying event of cardiovascular diseases due to its serious health impact. However, it is still not clear whether periodontopathic pathogens are truly etiologic agents or ubiquitous bystanders. This article reviews the current understanding about the molecular biological interactions between periodontal disease and atherosclerosis and the biological plausibility of periodontitis as a potential risk factor for cardiovascular disease. Materials and methods:, The current literature regarding periodontal diseases and atherosclerosis and coronary vascular disease was searched using the Medline and PubMed databases. Results:,In vitro experiments and animal models are appropriate tools to investigate the biological interactions between periodontal disease and atherosclerosis at the cell molecular level. The concepts linking both pathologies refer to inflammatory response, immune responses, and hemostasis. In particular, Porphyromonas gingivalis appears to have unique, versatile pathogenic properties. Whether or not these findings from isolated cells or animal models are applicable in humans with genetic and environmental variations is yet to be determined. Likewise, the benefit from periodontal therapy on the development of atherosclerosis is unclear. Approaches targeting inflammatory and immune responses of periodontitis and atherosclerosis simultaneously are very intriguing. Conclusion:, An emerging concept suggests that a pathogenic burden from different sources might overcome an individual threshold culminating in clinical sequela. P. gingivalis contributes directly and indirectly to atherosclerosis. [source] Particulate delivery systems for vaccines: what can we expect?JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2006Vincent W. Bramwell In our attempts to thwart the unwanted attentions of microbes by prophylactic and therapeutic vaccination, the knowledge of interactions at the molecular level may prove to be an invaluable asset. This article examines how particulate delivery systems such as liposomes and polymer micro-spheres can be applied in the light of recent advances in immunological understanding. Some of the biological interactions of these delivery systems are discussed with relevance for antigen trafficking and molecular pathways of immunogenicity and emphasis on the possible interaction of liposomal components. In particular, traditional concepts such as antigen protection, delivery to antigen presenting cells and depot formation remain important aspects, whilst the inclusion of selected co-adjuvants and enhanced delivery of these moieties in conjunction with antigen now has a firm rationale. [source] Kinetic studies of biological interactions by affinity chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2009John E. Schiel Abstract The rates at which biological interactions occur can provide important information on the mechanism and behavior of such processes in living systems. This paper will discuss how affinity chromatography can be used as a tool to examine the kinetics of biological interactions. This approach, referred to here as biointeraction chromatography, uses a column with an immobilized binding agent to examine the association or dissociation of this agent with other compounds. The use of HPLC-based affinity columns in kinetic studies has received particular attention in recent years. Advantages of using HPLC with affinity chromatography for this purpose include the ability to reuse the same ligand within a column for a large number of experiments, and the good precision and accuracy of this approach. A number of techniques are available for kinetic studies through the use of affinity columns and biointeraction chromatography. These approaches include plate height measurements, peak profiling, peak fitting, split-peak measurements, and peak decay analysis. The general principles for each of these methods are discussed in this paper and some recent applications of these techniques are presented. The advantages and potential limitations of each approach are also considered. [source] Gold Nanoparticle-Hybridized "Nano-Sponge" Polymer Coatings to Enhance the Reliability and Sensitivity of BiosensorsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2009Hyung-Jun Jeong Abstract We have created a new functional biosensor coating composed of polyelectrolyte multilayers containing gold nanoparticles. This gold-hybridized polyelectrolyte multilayer film possesses a stable nanoporous structure under physiological conditions. Antibody molecules were successfully conjugated onto the gold nanoparticles within the film. This functional coating successfully extinguished false signals from non-specific binding of proteins and cells and also provided highly enhanced detection sensitivity. Furthermore, the drastic differences in protein and cellular adhesion properties between a chip coated with the nanoporous PEM film and a bare chip demonstrate that morphological control of biological interactions on chip surfaces is possible. [source] Experimental evidence of habitat provision by aggregations of Riftia pachyptila at hydrothermal vents on the East Pacific RiseMARINE ECOLOGY, Issue 1 2007Breea Govenar Abstract Habitat created or modified by the physical architecture of large or spatially dominant species plays an important role in structuring communities in a variety of terrestrial, aquatic, and marine habitats. At hydrothermal vents, the giant tubeworm Riftia pachyptila forms large and dense aggregations in a spatially and temporally variable environment. The density and diversity of smaller invertebrates is higher in association with aggregations of R. pachyptila than on the surrounding basalt rock seafloor. Artificial substrata designed to mimic R. pachyptila aggregations were deployed along a gradient of productivity to test the hypothesis that high local species diversity is maintained by the provision of complex physical structure in areas of diffuse hydrothermal flow. After 1 year, species assemblages were compared among artificial aggregations in low-, intermediate-, and high-productivity zones and compared to natural aggregations of R. pachyptila from the same site. Hydrothermal vent fauna colonized every artificial aggregation, and both epifaunal density and species richness were highest in areas of high chemosynthetic primary production. The species richness was also similar between natural aggregations of R. pachyptila and artificial aggregations in intermediate- and high-productivity zones, suggesting that complex physical structure alone can support local species diversity in areas of chemosynthetic primary production. Differences in the community composition between natural and artificial aggregations reflect the variability in microhabitat conditions and biological interactions associated with hydrothermal fluid flux at low-temperature hydrothermal vents. Moreover, these local ecological factors may further contribute to the maintenance of regional species diversity in hydrothermal vent communities on the East Pacific Rise. [source] Multiscale observation of biological interactions of nanocarriers: From nano to macroMICROSCOPY RESEARCH AND TECHNIQUE, Issue 9 2010Su-Eon Jin Abstract Microscopic observations have played a key role in recent advancements in nanotechnology-based biomedical sciences. In particular, multiscale observation is necessary to fully understand the nano-bio interfaces where a large amount of unprecedented phenomena have been reported. This review describes how to address the physicochemical and biological interactions of nanocarriers within the biological environments using microscopic tools. The imaging techniques are categorized based on the size scale of detection. For observation of the nanoscale biological interactions of nanocarriers, we discuss atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). For the micro to macro-scale (in vitro and in vivo) observation, we focus on confocal laser scanning microscopy (CLSM) as well as in vivo imaging systems such as magnetic resonance imaging (MRI), superconducting quantum interference devices, and IVIS®. Additionally, recently developed combined techniques such as AFM-CLSM, correlative light and electron microscopy (CLEM), and SEM spectroscopy are also discussed. In this review, we describe how each technique helps elucidate certain physicochemical and biological activities of nanocarriers such as dendrimers, polymers, liposomes, and polymeric/inorganic nanoparticles, thus providing a toolbox for bioengineers, pharmaceutical scientists, biologists, and research clinicians. Microsc. Res. Tech. 73:813,823, 2010. © 2010 Wiley-Liss, Inc. [source] Genetic estimates of contemporary effective population size: what can they tell us about the importance of genetic stochasticity for wild population persistence?MOLECULAR ECOLOGY, Issue 15 2008FRISO P. PALSTRA Abstract Genetic stochasticity due to small population size contributes to population extinction, especially when population fragmentation disrupts gene flow. Estimates of effective population size (Ne) can therefore be informative about population persistence, but there is a need for an assessment of their consistency and informative relevance. Here we review the body of empirical estimates of Ne for wild populations obtained with the temporal genetic method and published since Frankham's (1995) review. Theoretical considerations have identified important sources of bias for this analytical approach, and we use empirical data to investigate the extent of these biases. We find that particularly model selection and sampling require more attention in future studies. We report a median unbiased Ne estimate of 260 (among 83 studies) and find that this median estimate tends to be smaller for populations of conservation concern, which may therefore be more sensitive to genetic stochasticity. Furthermore, we report a median Ne/N ratio of 0.14, and find that this ratio may actually be higher for small populations, suggesting changes in biological interactions at low population abundances. We confirm the role of gene flow in countering genetic stochasticity by finding that Ne correlates strongest with neutral genetic metrics when populations can be considered isolated. This underlines the importance of gene flow for the estimation of Ne, and of population connectivity for conservation in general. Reductions in contemporary gene flow due to ongoing habitat fragmentation will likely increase the prevalence of genetic stochasticity, which should therefore remain a focal point in the conservation of biodiversity. [source] Interactions between fetal HLA-DQ alleles and maternal smoking influence birthweightPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 5 2006G. Malcolm Taylor Summary Maternal smoking during pregnancy inhibits fetal growth, and is a major cause of childhood and adult morbidity, including increased risks of cardiovascular disease and diabetes. However, the use of birthweight as a proxy for future smoking-related morbidity is hindered by its wide variability, suggesting a role for other birthweight-modifying factors. We report here, for the first time, that interactions between specific fetal HLA-DQA1 and DQB1 alleles and maternal smoking can influence birthweight. We compared mean birthweights of a series of term, HLA-DQ typed white UK newborns (n = 552) whose mothers had either smoked (n = 211) or not smoked (n = 341) during pregnancy. Maternal smoking during pregnancy resulted in an average birthweight reduction of 244 g, but the combined effects of maternal smoking and fetal DQA1*0101 or DQB1*0501 alleles resulted in a 230 and 240 g further reduction in mean birthweight, respectively, resulting from interactions between smoking and these DQ types. Other fetal DQ allele-specific interactions with maternal smoking are suggested by a ,protective' effect on smoking-associated birthweight reduction in newborns typing for DQA1*0201 and DQB1*0201. Our results suggest biological interactions between maternal cigarette smoking during pregnancy and specific fetal DQ alleles that affect fetal growth. The precise nature of these interactions merits further investigation, as knowledge of fetal HLA-DQ type may be useful in refining risk estimates of severe fetal growth restriction because of maternal smoking during pregnancy. [source] Conservation ecology of Primula sieboldii: Synthesis of information toward the prediction of the genetic/demographic fate of a populationPLANT SPECIES BIOLOGY, Issue 1 2005IZUMI WASHITANI Abstract In an age of deepening biodiversity crisis, plant species biological studies integrating ecological and genetic approaches, especially exhaustive studies with a model plant species, are urgently needed for both assessing the present status and implementing effective conservation measures, as a comprehensive understanding of demographic/genetic interactions involved in the vicious cycle of plant population extinction is a prerequisite for any precise prediction regarding plant conservation. In this article, we summarize the major contributions to conservation ecological studies on a heterostylous clonal herb Primula sieboldii, focusing on gene flow and reproductive success, which are dependent on the life-history traits of the species and biological interactions with its effective pollinators, long-tongued bumblebees. [source] Dendrimer-grafted cell adhesion peptide,modified PDMSBIOTECHNOLOGY PROGRESS, Issue 4 2008A. S. Mikhail Abstract Surface concentration of cell adhesion peptides is thought to play a role in the interactions between biomaterials and cells. The high density of functional groups at the periphery of dendrimers has been exploited in various applications, but their full potential for generating surfaces with high functional group concentrations has not yet been realized. Poly(dimethylsiloxane) elastomers were surface modified with both polyethylene oxide (PEO) and generation 3 diaminobutane dendrimers. PEO and the dendrimers were subsequently used as linker molecules for surface grafting of cell adhesion peptides. ATR-FTIR, X-ray photoelectron spectroscopy, and water contact angle results confirmed the successful attachment of the polymer linkers and peptides. Peptide grafting density was quantified by means of 125I radiolabeling. Maximum surface peptide grafting density on dendrimer-modified surfaces was twofold greater than the maximum peptide grafting density achieved via the PEO linker. However, vascular endothelial cell adhesion was significantly greater on surfaces modified with the PEO linker, presumably due to the highly flexible PEO spacer making the peptide more accessible for binding with the cell surface receptors. These results suggest that, although peptide surface density may be important, optimizing surface density may not be sufficient for improving biological interactions. [source] An Approach towards the Quantitative Structure,Activity Relationships of Caffeic Acid and its DerivativesCHEMBIOCHEM, Issue 9 2004Rajeshwar P. Verma Dr. Abstract Caffeic acid and its derivatives are already known to possess a wide range of biological activities. We have developed quantitative structure,activity relationships (QSARs) for different series of caffeic acid derivatives (including caffeic acid) in order to understand the chemical,biological interactions governing antitumor activity against six different tumor cell lines, nitric oxide production, anti-HIV and enzymatic activities, and binding affinity to the lck domain. QSAR results have shown that the different activities of caffeic acid and its derivatives are largely dependent on their hydrophobicity or molar refractivity, with a bilinear correlation being the most important. [source] 4237: New biomaterials for keratoprosthesesACTA OPHTHALMOLOGICA, Issue 2010AW LLOYD Purpose Although a wide range of keratoprostheses have been developed from various materials over the last 30 years there has been limited optimisation of material properties to enhance clinical performance and minimise tissue incompatibility within the ocular environment. The development of our understanding of the biological interactions between materials and corneal tissues, the failure of existing keratoprostheses, the advances in the design and synthesis of materials of controlled molecular architectures and the advancements in composite biomaterials in recent years provides an opportunity to design enhanced biomaterials for the fabrication of the next generation of keratoprosthetic with improved clinical performance. Methods This paper will review studies undertaken by our group which have enhanced our understanding of the biological interactions of existing keratoprosthetic materials in the ocular environment and the development of novel approaches to new materials for the fabrication of keratoprosthetic based on the utilisation of biomimetic and composite systems and recent advances in the polymeric biomaterials. Results The paper will review data relating to the biological degradation of biomimetic materials and approaches to optimising these processes to provide materials with enhanced tissue integration and reduced inflammatory response. The in vitro biological evaluation of some of these materials indicates that material engineering may improve the clinical performance of biomaterials in the corneal environment. Conclusion The development of novel materials for the fabrication of keratoprostheses relies on improving our understanding of the mechanisms of failure of existing devices and how biomaterials can be engineered to overcome these challenges [source] Differential expression of p53, p63 and p73 proteins in human buccal squamous-cell carcinomasCLINICAL OTOLARYNGOLOGY, Issue 5 2003Y.K. Chen Abnormalities in the p53 gene are regarded as the most consistent of the genetic abnormalities in oral squamous-cell carcinoma. Two new members of the p53 gene family, p73 and p63, have recently been identified, with the three sharing considerable sequence homology at the acidic N-terminal transactivation, central DNA-binding and C-terminal oligomerization domains, indicating possible functional and biological interactions. The differential expression of p73, p63 and p53 genes in human oral squamous-cell carcinoma does not yet appear to be completely understood, however. In this study, therefore, immunohistochemical analysis of protein expression was performed for 40 samples of well-differentiated human buccal squamous-cell carcinomas, with 10 specimens of normal buccal mucosa employed as controls. Differential expressions of p63, p73 and p53 proteins in the carcinoma samples were: p63+/p73+/p53 + (n = 28; 70%); p63+/p73+/p53, (n = 4; 10%); p63+/p73,/p53, (n = 8; 20%), respectively; and p63+/p73+/p53, for normal mucosa (n = 10; 100%). A significant correlation between p53, p63 and p73 immunoexpression was demonstrated for the buccal squamous-cell carcinoma samples (P < 0.0001; Fisher's exact test). Significance was not achieved for the correlation between p73 and p53 immunoexpression and clinicopathological parameters for buccal carcinomas (P > 0.05; Fisher's exact test). Our results indicate that both p73 and p63 may be involved in the development of human buccal squamous-cell carcinoma, perhaps in concert with p53. [source] Quantitative Chemical Mapping of Relevant Trace Elements at Biomaterials/Biological Media Interfaces by Ion Beam MethodsADVANCED ENGINEERING MATERIALS, Issue 7 2010Edouard Jallot The definition of biomaterial as proposed by the European Society for Biomaterials in 1986 puts forward the overall importance of the notion of contact between the biomaterial and biological medium (cell, tissue, fluid,,). The underlying concept of biocompatibility makes the interface between biomaterial and biological medium a privileged zone of interest. In this paper, we would like to give an exhaustive view of how ion beams techniques can contribute to a better understanding of such interface taking several examples dealing with bone tissue substitution. After a short presentation of ion beams techniques the paper will focus on PIXE/RBS spectroscopies and will give the basics of these coupled technique. Three examples will then be presented to illustrate the interest of these techniques to study biomaterials/biological interactions. The first example deals with metallic alloys based joint prostheses. The ionic release from the prosthesis and the wear behavior of total knee prostheses will be presented. In the last two examples, bioactive materials will be studied. The common characteristic of bioactive ceramics is the kinetic modification of their surface upon interaction which is ideally monitored by PIXE chemical mapping. The second example will review the benefit of using PIXE/RBS technique to study the effect of doping of bioactive glasses on the very first steps involved in the bioactivity mechanisms like dissolution, ionic release, and biomineralization onto the surface of the glasses. Finally, protein delivery systems based upon mesoporous hydroxyapatites will be studied. Chemical mapping allowing the quantitative determination of protein distribution inside the HAp grains will be presented for the first time. [source] | ||||||||||||||||||||||