Strengthening biomedicine's roots

Synthesis and Properties of New "Stimuli" Responsive Nanocomposite Hydrogels Containing Silver Nanoparticles

Hydrogel nanocomposites containing silver nanoparticles of size 15⁻21 nm were prepared by diffusion and in-situ chemical reduction in chemically crosslinked polymers based on N-acryloyl-N'-ethyl piperazine (AcrNEP) and N-isopropylacrylamide (NIPAM). The polymer chains of the hydrogel network offered control and stabilization of silver nanoparticles without the need for additional stabilizers. The presence of silver nanoparticles and their size was quantified by UV-Vis absorption spectroscopy and scanning electron microscopy. The nanocomposite hydrogels were responsive to pH and temperature changes of the external environment. The equilibrium weight swelling ratio of the hydrogel nanocomposite was lower in comparison with the precursor hydrogel. Silver nanoparticles present in the nanocomposite offered additional physical crosslinking which influenced media diffusion and penetration velocity. The release of silver nanoparticles from the hydrogel matrix in response to external pH changes was studied. The rate of release of silver nanoparticles was higher in a solution of pH 2.5 due to maximum swelling caused by ionization of the gel network. No significant release of nanoparticles was observed in a solution of pH 7.

Managing the future: the Special Virus Leukemia Program and the acceleration of biomedical research

After the end of the Second World War, cancer virus research experienced a remarkable revival, culminating in the creation in 1964 of the United States National Cancer Institute's Special Virus Leukemia Program (SVLP), an ambitious program of directed biomedical research to accelerate the development of a leukemia vaccine. Studies of cancer viruses soon became the second most highly funded area of research at the Institute, and by far the most generously funded area of biological research. Remarkably, this vast infrastructure for cancer vaccine production came into being before a human leukemia virus was shown to exist. The origins of the SVLP were rooted in as much as shifts in American society as laboratory science. The revival of cancer virus studies was a function of the success advocates and administrators achieved in associating cancer viruses with campaigns against childhood diseases such as polio and leukemia. To address the urgency borne of this new association, the SVLP's architects sought to lessen the power of peer review in favor of centralized Cold War management methods, fashioning viruses as "administrative objects" in order to accelerate the tempo of biomedical research and discovery.

Mapping the emergence and development of translational cancer research

Cancer research is one of the principal targets of translational research, yet the nature of the relationships between different forms of cancer research remains controversial. The paper examines publications in the cancer field during the 1980-2000 period. A network analysis software program was used to map evolving patterns of inter-citations between cancer publications, their different research levels and the transformation of their relational content. Both inter-citation and content maps provide striking evidence of the consolidation in the 1990s of a translational interface that was practically non existent a few decades before. In 1980, research was polarized according to the allegiance to either a clinical or a laboratory style. This same duality obtains in the year 2000, albeit with the additional presence of a third, biomedical player whose activities are similarly structured by a common orientation, rather than by an exclusive commitment to a specific sub-domain.

[What is biomedicine? A socio-historical outline]

The article examines the debates surrounding the emergence of the term biomedicine, with a particular focus on the relation between the pathological and the normal. The authors reject simplistic definitions of biomedicine as a one-way street leading to the application of medical knowledge to medicine, or even as a two-way street characterized by iterative exchanges between the clinic and the laboratory. Rather, the authors introduce the notion of a biomedical platform as the site where the clinic and the laboratory intermingle and are realigned in connection with the ongoing process of medical innovation and the increasing automation of molecular procedures. The examples used in the article are drawn mainly from the field of onco-hematology.

Nonmonotonic variation with salt concentration of the second virial coefficient in protein solutions

The osmotic virial coefficient B2 of globular protein solutions is calculated as a function of added salt concentration at fixed pH by computer simulations of the "primitive model." The salt and counterions as well as a discrete charge pattern on the protein surface are explicitly incorporated. For parameters roughly corresponding to lysozyme, we find that B2 first decreases with added salt concentration up to a threshold concentration, then increases to a maximum, and then decreases again upon further raising the ionic strength. Our studies demonstrate that the existence of a discrete charge pattern on the protein surface profoundly influences the effective interactions and that linear and nonlinear Poisson Boltzmann theories fail for large ionic strength. The observed nonmonotonicity of B2 is compared with experiments. Implications for protein crystallization are discussed.

Effects of material hydrophobicity on physical properties of polymeric microspheres formed by double emulsion process

Human serum albumin (HSA) was encapsulated as a model protein in microspheres of biodegradable and biocompatible polymers by the water-in-oil-in-water (w/o/w) emulsion solvent extraction/evaporation (double emulsion) technique for purpose of controlled release. To improve the properties and control the rate of drug release of the delivery vehicle, materials with different hydrophobicity from that of their conventional counterparts, such as poly(lactide-co-ethylene glycol) (PELA) in place of poly(lactide-co-glycolide) (PLGA) as the polymer matrix, ethyl acetate/acetone in place of dichloride methane (DCM) as the (co)solvent and d-alpha tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) as the additive, were used to prepare the microspheres. It has been found that PELA microspheres, compared with PLGA ones, were slightly smaller in size if prepared at identical emulsification strength. They had more porous surface and internal structure, higher encapsulation efficiency (EE) and more rapid in vitro release rate. Furthermore, the physical properties of the microspheres were also affected by the presence of solvents and additives and their properties. Our results suggest that these materials could have interesting potential applications in preparation of polymeric microspheres for controlled protein release.

Complex disease and the new clinical sciences

Medical research today is dominated by a genocentric point of view. At the same time, clinical discovery and patient-oriented research have become less common. Here, I suggest that these developments are interdependent, each representing the flip side of an inaccurate view of how clinical advance occurs.

Breaking down the walls: thoughts on the scholarship of integration

The scholarship of integration is concerned with making connections across scientific disciplines, placing the work of individual investigators and their specialty fields into a larger context, and educating nonspecialists. The authors focus their comments on the biomedical sciences, but observe that closer integration of the biomedical and behavioral sciences will be particularly crucial to advance understanding of the human brain. They observe that as biomedical sciences become more technologically sophisticated, progress is increasingly dependent on sciences such as physics, chemistry, engineering, and related fields. However, the scholarship of integration has been slower than other forms of scholarship to gain acceptance as an integral activity of the professoriate. The isolation of disciplines from one another, particularly at large universities, and the perception of interdisciplinary work as risky and professionally unrewarding are among the forces that may discourage integrative scholarship. In addition, a troubling disconnect exists between the scientific community and the larger public in the understanding of science. Leaders in academic medicine and science must develop strategies to move interdisciplinary work from the margins into the mainstream of academia. Solutions that have been proposed include creating new research entities and funding mechanisms dedicated to interdisciplinary work; reinvigorating the integrative role of the physician-scientist; and training specialists in translational research. The scientific community must also work to develop more effective means of communicating the importance of its work to the public.

Solution structure and dynamics of biomolecules from Raman optical activity

Raman optical activity (ROA) measures vibrational optical activity by means of a small difference in the intensity of Raman scattering from chiral molecules in right and left circularly polarized incident laser light. The ROA spectra of a wide range of biomolecules in aqueous solution can now be measured routinely. Because of its sensitivity to the chiral elements of biomolecular structure, ROA provides new information about solution structure and dynamics complementary to that supplied by conventional spectroscopic techniques. This article provides a brief introduction to the theory and practice of ROA spectroscopy followed by a review of recent ROA results on polypeptides, proteins, carbohydrates, nucleic acids and viruses which illustrate how new insight into current problems of structure, folding and function may be obtained from ROA studies.