Biophysical Research Articles

The Biophysics of RNA

The Biophysics of RNA

The Effect of Beam Energy on the Quality of IMRT Plans for Prostate Conformal Radiotherapy

Three dimensional conformal radiation therapy (3DCRT) for prostate cancer is most commonly delivered with high-energy photons, typically in the range of 10-21 MV. With the advent of Intensity Modulated Radiation Therapy (IMRT), an increase in the number of monitor units (MU) relative to 3DCRT has lead to a concern about secondary malignancies. This risk becomes more relevant at higher photon energies where there is a greater neutron contribution. Subsequently, the majority of IMRT prostate treatments being delivered today are with 6-10 MV photons where neutron production is negligible. However, the absolute risk is small [Hall, E. J. Intensity Modulated Radiation Therapy, Protons, and the Risk of Second Cancers. Int J Radiat Oncol Bio Phys 65, 1-7 (2006); Kry, F. S., Salehpour, M., Followill, D. S., Stovall, M., Kuban, D. A., White, R. A., and Rosen, I. I. The Calculated Risk of Fatal Secondary Malignancies From Intensity Modulated Radiation Therapy. Int J Radiat Oncol Bio Phys 62, 1195-1203 (2005).] and therefore it has been suggested that the use of an 18MV IMRT may achieve better target coverage and normal tissue sparing such that this benefit outweighs the risks. This paper investigates whether 18MV IMRT offer better target coverage and normal tissue sparing. Computed Tomography (CT) image sets of ten prostate cancer patients were acquired and two separate IMRT plans were created for each patient. One plan used 6 MV beams, and the other used 18 MV, both in a coplanar, non-opposed beam geometry. Beam arrangements and optimization constraints were the same for all plans. This work includes a comparison and discussion of the total integral dose, neutron dose conformity index, and total number of MU for plans generated with both energies.

Antennae as Gyroscopes

Antennae as Gyroscopes

Detectors for single-molecule fluorescence imaging and spectroscopy

Single-molecule observation, characterization and manipulation techniques have recently come to the forefront of several research domains spanning chemistry, biology and physics. Due to the exquisite sensitivity, specificity, and unmasking of ensemble averaging, single-molecule fluorescence imaging and spectroscopy have become, in a short period of time, important tools in cell biology, biochemistry and biophysics. These methods led to new ways of thinking about biological processes such as viral infection, receptor diffusion and oligomerization, cellular signaling, protein–protein or protein–nucleic acid interactions, and molecular machines. Such achievements require a combination of several factors to be met, among which detector sensitivity and bandwidth are crucial. Here, the necessary performance of photodetectors used in these types of experiments, the current state of the art for different categories of detectors, and actual and future developments of single-photon counting detectors for single-molecule imaging and spectroscopy, are investigated.

Polyparazitism consequences and complex antiparazitic treatment (Brovitacoccid, Avomec, Tilozin 200) upon the postvaccin immunity in bovine.

The obtained results shows that the polyparasitism (Strongyloides papillosus, Neoascaris vitulorumi, Eimeria bovis, E. smithi, E. zuerni, E. ellipsoidalis) decrease the level of total lymphocytes by 10% (P>0,05), B - 12,6% (P<0,01), T - 18,7% (P<0,01), but increase the quantity of nul lymphocytes by 31,4% (P<0,001) and after all these modifications a lower antibody level is forming 72% (P<0,01) by comparing with the group of uninfected animals and treated with the anticolibacillar vaccine. After the vaccination of the calf treated with Brovitacoccid, Avomec and Tilozin 200 the decreasing of total lymphocyte level was registered 12,5% (P<0,05), B - 16,9% (P<0,001), T - 21,2% (P<0,01), but the quantity of null lymphocytes increased - 21,2% (P<0,01). The impact of this treatment recorded a lower titre of specific anticolibacillar antibodies with 82% (P<0,01) by comparing with the uninfected vaccinated animals. This fact is probably due to the long-term immunotoxic effect of the drug factor, which deeply disturb the biochemical and biophysical processes at the level of immunocompetent cells, including the B lymphocytes that produce the specific antibodies

1P346 燐光の強度相関法による寿命測定と酸素濃度測定(計測,ポスター発表,第45回日本生物物理学会年会)

1P346 燐光の強度相関法による寿命測定と酸素濃度測定(計測,ポスター発表,第45回日本生物物理学会年会)

Dipped in Oil

Dipped in Oil

Housing as a socio-economic determinant of health: findings of a national needs, gaps and opportunities assessment.

In 2002-2003, a Needs, Gaps and Opportunities Assessment (NGOA) was conducted to investigate relationships between socio-economic dimensions of housing and health. Recent reviews of the literature point to a dearth of research on the socio-economic dimensions of housing and health, despite its potential for promoting health. The NGOA sought to identify research needs and gaps, and future opportunities for research in housing, socio-economic status and health. The methods used included a literature scan, a scan of research capacity, eight regional stakeholder workshops across Canada, and an open-ended e-mail survey of stakeholders. In this paper, we report the findings of the stakeholder consultations. The main finding of the NGOA was that there is a significant dearth of research on housing as a socio-economic determinant of health but enormous potential for conducting high-impact, longitudinal and quasi-experimental research in the area. Of particular interest to stakeholder participants in the NGOA were the economic aspects of housing and health; the impact of housing on health for vulnerable subgroups (e.g., Aboriginal peoples, immigrants, children, seniors); the role of socio-economically and ethnically mixed communities; and the interaction between socio-economic aspects of housing and biophysical hazards in the home. The NGOA demonstrated that there is a substantial audience eager for knowledge on housing as a socio-economic determinant of health and that such knowledge could make an immediate impact on policy decision-making and program operation. Although knowledge gaps are substantial, the NGOA clearly identifies opportunities for high-impact, longitudinal and quasi-experimental research. Recently signed federal-provincial funding agreements for housing make the findings of the NGOA timely. Moreover, the NGOA results demonstrate how research on housing as a socio-economic determinant of health could be a strategy for improving our understanding of the effects of social environments on health and for reducing health disparities.

Cryopreservation and "Intractable Laws of Biophysics"

Cell Preservation TechnologyVol. 4, No. 2 From the Editor's DeskCryopreservation and "Intractable Laws of Biophysics"J.G. BaustJ.G. BaustSearch for more papers by this authorPublished Online:25 Jul 2006https://doi.org/10.1089/cpt.2006.4.81AboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail "Cryopreservation and "Intractable Laws of Biophysics"." , 4(2), p. 81FiguresReferencesRelatedDetails Volume 4Issue 2Jun 2006 InformationCopyright 2006, Mary Ann Liebert, Inc.To cite this article:J.G. Baust.Cryopreservation and "Intractable Laws of Biophysics".Cell Preservation Technology.Jun 2006.81-81.http://doi.org/10.1089/cpt.2006.4.81Published in Volume: 4 Issue 2: July 25, 2006PDF download

Radiobiophysical Aspects of Stereotaxic Radiation Treatment of Central Nervous System Diseases.

The biophysical aspects of stereotaxic treatment are summarized, emphasizing the complex interplay between time-dose-fractionation, partial volume effect, physical dose distribution, and set-up uncertainties in influencing treatment outcome. The radiobiological advantage of dose-fractionation for normal tissue sparing is estimated using the linear-quadratic model and viewed in the context of clinical situations and results. Counterbalancing this benefit is the larger geometrical uncertainty associated with multiple fraction treatment, which would require increased treatment volume and an associated decrease in treatment dose. This last consideration requires knowledge of volume-dose relation of radiation-induced normal brain toxicity, the current status of which is also outlined.

Why Food Biophysics?

Why Food Biophysics?

Biophysical sensor

Biophysical sensor

The Regional Biophysics Meeting March 16−20, 2005, Zreče, Slovenia

The Regional Biophysics Meeting March 16−20, 2005, Zreče, Slovenia

Statistical-Mechanical Viewpoint Needed in Teaching Biophysics

Statistical-Mechanical Viewpoint Needed in Teaching Biophysics

Statistical-Mechanical Viewpoint Needed in Teaching Biophysics

Statistical-Mechanical Viewpoint Needed in Teaching Biophysics

Biophysical approaches for studying the integrity and function of tight junctions.

Cell-cell adhesion is an extremely important phenomenon as it influences several biologically important processes such as inflammation, cell migration, proliferation, differentiation and even cancer metastasis. Furthermore, proteins involved in cell-cell adhesion are also important from the perspective of facilitating better drug delivery across epithelia. The adhesion forces imparted by proteins involved in cell-cell adhesion have been the focus of research for sometime. However, with the advent of nanotechnological techniques such as the atomic force microscopy (AFM), we can now quantitatively probe these adhesion forces not only at the cellular but also molecular level. Here, we review the structure and function of tight junction proteins, highlighting some mechanistic studies performed to quantify the adhesion occurring between these proteins and where possible their association with human diseases. In particular, we will highlight two important experimental techniques, namely the micropipette step pressure technique and the AFM that allow us to quantify these adhesion forces at both the cellular and molecular levels, respectively.

Biophysics: The end of simplicity?

Biophysics: The end of simplicity?

The Comparison of Treatment Plans.

Abstract The comparison of plans, once done by looking from one isodose plot to another, has become in hyper-dimensional planning a sophisticated matter. I have described here a number of tools that support plan evaluation and comparison, namely: 1.1. Side-by-side display of dose distributions: using color-wash to represent dose; displays on any section, transverse, sagittal, coronal, oblique; ostensive (mouse-driven cursor) interrogation of dose at a point; pan and zoom to highlight a specified volume of interest. 2.2. Dose-volume histograms: cumulative and (optionally) differential; with superposed constraint points. 3.3. Dose statistics: minimum, mean, maximum dose to a volume of interest; minimum dose received by a specified proportion of a VOI; proportion of a VOI which receives at least a specified dose; numerical score based on deviation from specified dose or dose-volume constraint. 4.4. Biophysical models: tumor control probability; normal tissue control probability. The greater complexity that this tool kit implies has, of course, its downside: although the clinician has much more useful information at his or her fingertips, it can take longer to use it. For this reason I have emphasized here the importance of speed and inter-activity in the programs and of tools to help users in the evaluation process. These are becoming increasingly available in the new generation of treatment-planning programs; pressure from the consumer is needed to keep researchers on their toes and manufacturers responsive!

Structural and functional alterations in major peanut allergens caused by thermal processing.

The majority of foods that we eat are subjected to some type of processing either at home or by the manufacturer. The biochemical reactions that occur in foods as a result of thermal processing can be both beneficial and harmful. Here, we briefly review the effects of thermal processing and some of the effects of the Maillard reaction on the allergenicity of food proteins. Specifically, we focus on the known effects of roasting on the allergenic properties of peanut proteins and the contribution of Maillard reaction products or advanced glycation end products to these observed effects. The most thorough understanding of the effects of thermal processing on allergenicity involves the peanut proteins. Thermal processing alters specific biophysical and immunological properties of peanut proteins, such as structure, function, solubility, digestibility, immunoglobulin E (IgE) binding, and T-cell responses. A better understanding of the effects of thermal processing-induced biochemical and immunological alterations is of utmost importance for proper risk assessment of existing and newly introduced proteins in the food source, as well as development of effective diagnostic tools and therapeutic treatments for food allergy.

5 Structural Studies of Prion Proteins

Although many aspects of prion disease biology are unorthodox, perhaps the most fundamental paradox is posed by the coexistence of inherited, sporadic, and infectious forms of these diseases. Sensible molecular mechanisms for prion propagation must explain all three forms of prion diseases in a manner that is compatible with the formidable and ever-increasing array of experimental data derived from histopathologic, biochemical, biophysical, human genetic, and transgenetic studies. In this chapter, we explore the phenomenologic constraints on models of prion replication with a specific emphasis on biophysical studies of prion protein structures. We examine how an inherited disease can also present as a sporadic or infectious illness in the context of the structural data on PrPs that are currently available. Since the first version of this chapter was written, much more has been learned about prion biology. Many ideas have been reinforced and structural models have been revised. Exciting new advances toward the treatment of prion disease have resulted. THEORY OF PRION DISEASES The inherited prion diseases include Gerstmann-Straussler-Scheinker disease (GSS), familial Creutzfeldt-Jakob disease (fCJD), and fatal familial insomnia (FFI). These patients present with characteristic clinical and neuropathologic findings as early as their third or fourth decade of life, and their family histories are compatible with an autosomal dominant pattern of inheritance (Chapter 14). Molecular genetic studies argue that these diseases are caused by mutations in the prion protein (PrP) gene based on high LOD scores for 5 of the 30 known mutations (Hsiao et al. 1989; Dlouhy et al. 1992;...