Incorporation of macromolecules in microparticles: preparation and characteristics.

Macromolecules can easily be incorporated in microparticles of polyacrylamide by copolymerization with acrylamide in a water-in-oil emulsion. The microparticles preferably arount 1-3 mum in diameter, will have a macroporous structure formed by the polymeric network. The amount of incorporation of the macromolecules will depend on the structure of the network, which, in turn, will depend on the total amount of monomer (T) and the relative amount of cross-linking agent (C) in the monomeric solution. Two mechanisms are responsible for the incorporation; all macromolecules are, independently of the size, fixed in the threads of polyacrylamide and large ones are entrapped within the network formed by the threads. The amount entrapped will depend on the size of the macromolecule and the mean pore radius of the gel. In microparticles with a total concentration of monomers of 8% and a cross-linking of 25% (T-C=8-25) the biological properties of incorporated macromolecules are retained, due to the macroporous structure, as found in binding studies with albumin. The density of the particles will also depend on C and T and, to some extent, on the protein concentration. Due to the fixation in the polyacrylamide threads, some of the incorporated macromolecules will be exposed on the surface, allowing them to react with, for instance, cells, which cannot penetrate the particles. The optimal conditions for the incorporation of macromolecules in the microparticles are investigated.     

Computational modelling of the natural hip: a review of finite element and multibody simulations

Primary objective: The hip joint suffers from a high prevalence of degenerative conditions. Athough patient's well-being could be improved through early and more effective interventions, without a greater understanding of the mechanics of the hip, these developments cannot be attained. Thus, this review article summarises the current literature on this subject in order to provide a platform for future developments. To illustrate the influence computational simulations have had on the knowledge advancement in hip mechanics, we explored two methodological approaches: finite element (FE) analysis and multibody dynamics (MBD). Main outcomes and results: Notwithstanding the unique capabilities of FE and MBD, the former generally offers the micromechanics of the articulating surfaces whereas the latter the macromechanics of the skeleton, these two methodologies also provide the bulk of the literature regarding computational modelling of the musculoskeletal system. Although FE has provided significant knowledge on contact pressures and the effects of musculoskeletal geometries, in particular cartilage and bone shapes, MBD has afforded a wealth of understanding on the influence of gait patterns and muscle attachment locations on force magnitudes. Conclusions: These two computational techniques have, and will continue to, provide significant contributions towards the development of interventions. It is hoped that this article will help focus ongoing technological developments by highlighting areas of success, but also areas of under development.     

Editorial

Since this is the first issue of Soviet Psychology for which I am officially the editor, a few words concerning my approach to presenting Soviet psychological research to my Englishspeaking colleagues appear timely.

It should be clear to all that a quarterly journal of modest proportions cannot thoroughly cover all developments in a largeand active branch of Soviet science. Great selectivity has been, and will be, exercised.     

Dependence of media cross-sectional area on circumference of aortic rings from normal and hypertensive rats

The purpose of this study is to determine if cross-sectional area and media thickness depend on circumference in excised vessels. Measurements were obtained from rat aortic rings chemically fixed after excision. Rings were fixed without distention or after mounting on circular rods of different diameters. Media cross-sectional area increased with circumference but thickness decreased. Thickness and area were significantly greater in the SHR than the WKY rat at all circumferences. Results of a theoretical analysis predict that cross-sectional area and thickness will depend on circumference in excised rings. Best-fit curves of the experimental data to the theoretical relationships show that neither thickness nor cross-sectional area of the aorta is consistently better correlated with circumference in SHRs and WKY rats. The following conclusions are made: (i) Media cross-sectional area and thickness depend on circumference in excised-aortic rings, and (ii) for a specific method of preparation, thickness and cross-sectional area are equally accurate when comparing aortic rings from normal and hypertensive rats. If an experimental determination of the relationship between circumference and cross-sectional area (or thickness) cannot be done, we suggest that a reasonable alternative is to compare these measurements at the same circumference.     

Globalization's effects on world agricultural trade, 1960�C2050

Recent globalization has been characterized by a decline in the costs of cross-border trade in farm and other products. It has been driven primarily by the information and communication technology revolution and—in the case of farm products—by reductions in governmental distortions to agricultural production, consumption and trade. Both have boosted economic growth and reduced poverty globally, especially in Asia. The first but maybe not the second of these drivers will continue in coming decades. World food prices will depend also on whether (and if so by how much) farm productivity growth continues to outpace demand growth and to what extent diets in emerging economies move towards livestock and horticultural products at the expense of staples. Demand in turn will be driven not only by population and income growth, but also by crude oil prices if they remain at current historically high levels, since that will affect biofuel demand. Climate change mitigation policies and adaptation, water market developments and market access standards particularly for transgenic foods will add to future production, price and trade uncertainties.     

The future of human cerebral cartography: a novel approach

Cerebral cartography can be understood in a limited, static, neuroanatomical sense. Temporal information from electrical recordings contributes information on regional interactions adding a functional dimension. Selective tagging and imaging of molecules adds biochemical contributions. Cartographic detail can also be correlated with normal or abnormal psychological or behavioural data. Modern cerebral cartography is assimilating all these elements. Cartographers continue to collect ever more precise data in the hope that general principles of organization will emerge. However, even detailed cartographic data cannot generate knowledge without a multi-scale framework making it possible to relate individual observations and discoveries. We propose that, in the next quarter century, advances in cartography will result in progressively more accurate drafts of a data-led, multi-scale model of human brain structure and function. These blueprints will result from analysis of large volumes of neuroscientific and clinical data, by a process of reconstruction, modelling and simulation. This strategy will capitalize on remarkable recent developments in informatics and computer science and on the existence of much existing, addressable data and prior, though fragmented, knowledge. The models will instantiate principles that govern how the brain is organized at different levels and how different spatio-temporal scales relate to each other in an organ-centred context.     

Frequency-dependent selection in bacterial populations

There are many situations in which the direction and intensity of natural selection in bacterial populations will depend on the relative frequencies of genotypes. In some cases, this selection will favour rare genotypes and result in the maintenance of genetic variability; this is termed stabilizing frequency-dependent selection. In other cases, selection will only favour genotypes when they are common. Rare types cannot invade and genetic variability will not be maintained; this is known as disruptive frequency-dependent selection. Phage-mediated selection for bacteria with novel restriction-modification systems is frequency-dependent and stabilizing. In mass culture, selection for the production of toxins and allelopathic agents is likely to be frequency-dependent but disruptive. This also occurs in selection favouring genes and transposable elements that cause mutations. Here I review the results of theoretical and experimental studies of stabilizing and disruptive frequency-dependent selection in bacterial populations, and speculate on the importance of this kind of selection in the adaptation and evolution of these organisms and their accessory elements (plasmid, phage and transposons).     

Reconstructionist molecular biology

In the editorial inaugurating this journal, Levine (1989) pointed to a new reductionism in biology, which--unlike the old reductionism that led to specialization and isolation of areas concerned with different aspects of a complex biological problem--is providing a renewed sense of unity. This development is the result of widespread use of common experimental methodology and the emergence of signal transmission and differential gene expression as themes that are central to many areas of modern biology. I describe here a set of complementary developments in molecular biology that focus attention on the problems of complexity and organization. Simple examples are given that illustrate the difficulty of relating systemic behavior to the properties of the underlying molecular determinants, and the outlines of a general approach to this problem are presented. These developments, together with those highlighted by Levine, are leading us to a new, more integrative intellectual paradigm whose fruits will be the elucidation of fundamental issues concerning network function, design, and evolution that cannot be addressed by the current paradigm.     

Rapid monitoring of recombinant protein products: a comparison of current technologies

Specific measurement of recombinant protein titer in a complex environment during industrial bioprocessing has traditionally relied on labor-intensive and time-consuming immunoassays. In recent years, however, developments in analytical technology have resulted in improved methods for protein product monitoring during bioprocessing. The choice of product-monitoring technology for a particular bioprocess will depend on a variety of assay factors and instrument-specific factors. In this article, we have compiled an overview of the advantages and disadvantages of the most commonly used technologies used: electrochemiluminescence, optical biosensors, rapid chromatography and nephelometry. The advantages of each technology for measuring both small and large recombinant therapeutic proteins are compared with a conventional enzyme-linked immunosorbent assay (ELISA) technique.     

Risky research and bystander consent

There is no quick and easy answer to the question whether research activities that endanger bystanders without their consent ever thereby violate those bystanders’ rights. We cannot dismiss the idea that bystanders possess strong rights against researchers simply on the grounds that they are, after all, merely bystanders. Indeed, it is easy to imagine scenarios in which researchers would be morally required to gain the informed consent of bystanders whom they risk harming. Whether bystander consent is required in any particular real-world case will depend, in part, upon exactly how the research activity endangers them.     

Plant Derived Antimalarial Agents: New Leads and Challenges

New treatments for malaria are urgently needed due to the increasing problem of drug-resistance in malaria parasites. The long-established use of quinine and the more recent introduction of artemisinin and its derivatives as highly effective antimalarials demonstrates that plant species are an important resource for the discovery of new antimalarial agents. Furthermore, many plant species continue to be used in traditional medicines for the treatment of malaria and many people depend on such remedies as they cannot afford and/or do not have access to effective antimalarial drugs. In this paper the potential of plant species to yield new leads to antimalarial drugs will be illustrated with reference to cryptolepine, the main alkaloid present in the species, Cryptolepis sanguinolenta. In addition to this approach, there is currently increasing interest in the use and development of traditional herbal remedies for the treatment of malaria as these may have the potential to provide affordable antimalarial treatment for many who cannot afford the drugs needed to treat chloroquine-resistant Plasmodium falciparum infections. However, little is known with respect to the efficacy and safety of traditional antimalarials and clinical studies are urgently needed to establish their value. Some of the issues pertinent to this area will be briefly reviewed and it is hoped that this will stimulate further discussion and research on this important topic.     

Fixatives and fixation: a review

Conclusions During the period under review, various new fixatives have been introduced. The most important of these is glutaraldehyde which has become very widely used. The processes involved in fixation are becoming better understood in chemical and physical terms, largely due to developments in biochemistry and tanning. This understanding will become increasingly important as the resolution of macromolecules by the electron microscope increases. The images seen will then be able to be interpreted in the light of biochemical knowledge of the macromolecules and thus the gap between morphology and biochemistry will be bridged.Some of the fixatives have secondary uses in that they may demonstrate chemical substances. Others apparently destroy certain biological activities selectively.Increasing attention is being paid to the loss of substances from biological material during preparation. The importance of such studies cannot be overemphasized.No one fixative is ideal for all situations. By comparing the results obtained by a number of fixatives, and assessing the loss of substances during processing, it is far less likely that artefacts will be described as constant features.     

The mosquito genome: organization, evolution and manipulation

Apart from the genetic flexibility of the vectors, impediments to the control of vector-borne diseases include the rapid spread of drug resistance throughout parasite populations, the increasing movement of people to and from disease-endemic regions and the limited funds and public health infrastructures of most developing countries. The widely used residual insecticides and antiparasitic drugs have been inadequate solutions to the problem of vector-borne disease control. New approaches are needed. The enormous impact of recent developments in molecular genetics on the understanding of basic biology and human disease has stimulated a re-examination of the prospects for genetic manipulation of vector populations as a means for reducing or eliminating vector-borne diseases, especially malarial. Although control scenarios that exploit this technology may never be realized, Nora Besansky and Frank Collins emphasize that the increase in knowledge of basic mosquito biology on which these ideas depend will inevitably stimulate novel approaches to the control of mosquito-borne diseases.     

Current Status of Genetics and Genomics of Reared Penaeid Shrimp: Information Relevant to Access and Benefit Sharing

At present, research and progress in shrimp genomics and genetics show significant developments. Shrimp genetics and genomics also show immense potential for an increased production in a way that meets shrimp culture progress goals for the third millennium. This review article aims to provide an overview of its current status and future direction, discusses questions that need focused research to address them, and summarizes areas where genetics and genomics knowledge can make a positive difference to shrimp culture sustainability. Sustainable progress of penaeid shrimps will depend upon feasible solutions for environmental, research, economic, consumer problems, proper development, and planning policy enforcement. It is recommended that increased funding for biotechnology research and progress be directed to expand worldwide commercial shrimp culture and address environmental and public health issues. For any researcher or shrimp company member who has attempted to or whom would like to thoroughly search the literature to gain a complete understanding of the current state of shrimp genetics and genomics, this publication will be an invaluable source of reference materials, some of which is reported here for the first time.     

Cryoconservation du tissue testiculaire chez l’enfant: comment préserver la fertilité chez le jeune garçon?

Survival rates for almost all types of childhood cancer have improved over the last 30 years. Estimates suggest that, in 2010, 1 out of 715 adolescents and young adults will be a long-term survivor of childhood cancer. With current therapy, 70% of children are cured. The increased number of survivors has focused attention on the many long-term or late sequelae of treatment. Most of the effects cannot be detected at the end of therapy, but only become apparent with puberty, growth and the normal aging process. Among the various sequelae, gonadal dysfunction is observed and the degree of gonadal damage depends on the type and total doses of chemotherapy and/or radiotherapy. The male gonald is also more sensitive to cancer therapy than the female gonad. Cryopreservation of ejaculated spermatozoa should be proposed for sexually mature boys. However, when ejaculated semen samples cannot be collected, or in the case of prepubertal boys who are not yet able to produce spermatozoa, another strategy must be used: testicular biopsy associated with cryopreservation of (i) testicular tissue, or (ii) isolated testicular spermatozoa or (iii) immature germ cells. The future use of immature testicular tissue will depend on the development of novel technologies in humans such as germ cellin vitro maturation, or autologous or xenogeneic germ cell transplantation.     

Heritability of dispersal in banner-tailed kangaroo rats, Dipodomys spectabilis

In a wild population of banner-tailed kangaroo rats, heritability of dispersal was estimated using two measures of dispersal tendency: distance moved from the natal site and likelihood of leaving the natal home range. Neither of the heritability measures was significantly different from 0. The results indicate that the main causes of variation in dispersal behaviour in this species are environmental, and suggest that there is no class of ‘innate’ dispersers. The possibility cannot be excluded that this population retains modest additive genetic variance for dispersal tendency. The survival consequences of dispersal in kangaroo rats are known to depend on population density and to change significantly between years, so that selection should maintain genetic variation in dispersal tendencies. Modest genetic variation for dispersal tendencies, especially if dispersal is a conditional trait, will be extremely difficult to detect in field studies.     

Relative effectiveness of different particles and energies in disrupting behavioral performance

On exploratory class missions to other planets, astronauts will be exposed to varieties and doses of heavy particles, which are not experienced in low earth orbit. These particles can affect neurobehavioral function and potentially interfere with the ability of astronauts to successfully meet mission requirements. While a significant amount of research has been performed on the relative biological effectiveness (RBE) of different types of heavy particles on cytogenetic function, little research has been done on the effectiveness of different particles on central nervous system function and on cognitive/behavioral performance. The present paper reviews some recent research on the effects of exposure to different types and energies of heavy particles on the performance of two behavioral tasks which depend upon the integrity of the central dopaminergic system. This review indicates that the RBE of different particles for neurobehavioral dysfunction cannot be predicted only on the basis of the linear energy transfer of the specific particle.     

Twenty years of phylogeography: the state of the field and the challenges for the Southern Hemisphere

Phylogeography is a young, vigorous and integrative field of study that uses genetic data to understand the history of populations. This field has recently expanded into many areas of biology and also into several historical disciplines of Earth sciences. In this review, I present a numerical synthesis of the phylogeography literature based on an examination of over 3000 articles published during the first 20 years of the field (i.e. from 1987 to 2006). Information from several topics needed to evaluate the progress, tendencies and deficiencies of the field is summarized for 10 major groups of organisms and at a global scale. The topics include the geography of phylogeographic surveys, comparative nature of studies, temporal scales and major environments investigated, and genetic markers used. I also identify disparities in research productivity between the developing and the developed world, and propose ways to reduce some of the challenges faced by phylogeographers from less affluent countries. Phylogeography has experienced explosive growth in recent years fuelled by developments in DNA technology, theory and statistical analysis. I argue that the intellectual maturation of the field will eventually depend not only on these recent developments, but also on syntheses of comparative information across different regions of the globe. For this to become a reality, many empirical phylogeographic surveys in regions of the Southern Hemisphere (and in developing countries of the Northern Hemisphere) are needed. I expect the information and views presented here will assist in promoting international collaborative work in phylogeography and in guiding research efforts at both regional and global levels.     

Adhesions that mediate invasion

Infiltration of new tissue areas requires that a mammalian cell overcomes the physical and biochemical barrier of the surrounding extracellular matrix. Cell migration during embryonic development, and growth, invasion and dispersal of metastatic tumor cells depend to a large extent on the controlled degradation of extracellular matrix components. Localized degradation of the surrounding matrix is seen at defined adhesive (podosomes) and/or protrusive (invadopodia) locations in a variety of normal cells and aggressive carcinoma cells, suggesting that these membrane-associated cellular devices have a central role in mediating polarized migration in cells that cross-tissue boundaries. Here, we will discuss the recent advances and developments in this field, and provide our provisional outlook into the future understanding of the principles of focal extracellular matrix degradation by podosomes and invadopodia.