Biomedical subjects

V Barron

Publications and source records attributed to V Barron.

7 recordsLinked to original sources

PubMed2006

Characterisation of a collagen membrane for its potential use in cardiovascular tissue engineering applications.

In this study, Biomend, a collagen membrane conventionally used in the regeneration of periodontal tissue, is investigated for its possible use in the field of cardiovascular tissue engineering. A key requirement of most potential tissue engineering scaffolds is that degradation occurs in tandem with tissue regeneration and extra cellular matrix remodelling. To this end, it is crucial to understand the degradation mechanics and mechanisms of the material and to investigate the practicability of using Biomend as a possible scaffold material. With this in mind, methodologies for the initial characterisation of the scaffold material were determined. The mechanical properties of Biomend samples, subjected to various degrees of hydration and enzymatic degradation, were examined primarily through tensile testing experiments. The effects of enzymatic degradation were monitored quantitatively, by observing weight loss, and visually, by studying micrographs. Cell adhesion and viability were of primary concern. Confocal laser scanning microscopy was employed to illustrate endothelialisation on the surface of this collagen membrane. Fluorescence microscopy was used to visualise cell viability on the membrane surface. These images, coupled with assays to measure cell activity, suggest that Biomend is not a suitable substrate to allow endothelialisation. In summary, this collagen membrane has suitable mechanical properties with the potential to control its degradation rate. However, since poor endothelial cell viability was observed on the membrane, it may not be suitable for use in cardiovascular tissue engineering applications.

Biocompatible Materials↗

PubMed2005

Biomodels of bone: a review.

In this paper, a definition of a biomodel is presented, based on which different specific types of biomodels are identified, viz., virtual biomodels, computational biomodels, and physical biomodels. The paper then focuses on both physical and virtual biomodels of bone, and presents a review of model generation methodologies, giving examples of typical biomodel applications. The use of macroscale biomodels for such issues as the design and preclinical testing of surgical implants and preoperative planning is discussed. At the microscale, biomodels of trabecular bone are examined and the link with scaffolds for tissue engineering is established. Conclusions are drawn on the state of the art, and the major developments necessary for the continued expansion of the field are identified. Finally, arguments are given on the benefits of integrating the use of the different types of biomodels reviewed in this paper, for the benefit of future research in biomechanics and biomaterials.

Animals↗

PubMed2004

Endothelial cell alignment on cyclically-stretched silicone surfaces.

Endothelial cells at the interface between the bloodstream and the vessel wall are continuously subjected to mechanical stimulation in vivo, and it widely recognised that such stimulation plays an important role in cardiovascular physiology. Cell deformation is induced by mechanical forces such as cyclic stretch, fluid shear stress, and transmural pressure. Although much of the work in this field has dealt with the effect of fluid shear stress, very little is known about how cyclic forces modulate and alter the morphology of single endothelial cells, and thereafter, how they effect the confluent layer of endothelial cells lining the vessel wall. The aim of this study is to investigate the response of endothelial cells when subjected to substrate deformation of similar magnitude to those experienced in vivo. Human umbilical vein endothelial cells (HUVEC) were cultured on plasma-treated silicone strips and uni-axially cyclically stretched using a custom made mechanical device. Results showed that endothelial cells subject to 10% deformation for as little as 4 h reoriented perpendicular to the stretch direction. In addition, although no integrin coating was applied to the substrate, it was found that plasma-treated silicone provided a cell adhesion substrate comparable to the commonly used collagen type I. Thus the results show that the stretch stimulus alone affects the morphology of endothelial cells. Further studies are required to establish the relative importance of substrate strain vs. fluid flow stimuli.

Biocompatible Materials↗

PubMed2003

Bioreactors for cardiovascular cell and tissue growth: a review.

Heart disease is a major cause of death in the Western world. In the past three decades there has been a number of improvements in artificial devices and surgical techniques for cardiovascular disease; however, there is still a need for novel devices, especially for those individuals who cannot receive conventional therapy. The major disadvantage of current artificial devices lies in the fact that they cannot grow, remodel, or repair in vivo. Tissue engineering offers the possibility of developing a biological substitute material in vitro with the inherent mechanical, chemical, biological, and morphological properties required in vivo, on an individual patient basis. In order to develop a true biological cardiovascular device a dynamic physiological environment needs to be created. One approach that employs the use of a simulated biological environment is a bioreactor in which the in vivo biomechanical and biochemical conditions are created in vitro for functional tissue development. A review of the current state of the art bioreactors for the generation of tissue engineered cardiovascular devices is presented in this study. The effect of the simulated physiological environment of the bioreactor on tissue development is examined with respect to the materials properties of vascular grafts, heart valves, and cardiac muscles developed in these bioreactors.

Animals↗

PubMed1987

Texaco mortality study: III. A cohort study of producing and pipeline workers.

While there have been numerous epidemiology studies of refinery workers, no studies have been done on producing and pipeline workers. This is a retrospective follow-up study of all persons who were employed for at least 6 months at a Texaco producing or pipeline location and who worked at some time during the period 1946-1980. Of the 11,098 white men in the cohort, 8,964 were alive, 1,886 were known to be dead, and the vital status of the remaining 248 as of December 31, 1980 was unknown. The standardized mortality ratio (SMR) of 63 for all causes was significantly low, on the basis of 2,976 expected deaths. Statistically significant deficits also were seen for all major causes of death. Mortality patterns were also examined for the major job categories in these departments. Similar patterns of mortality were seen, although there was a significant excess of thyroid cancer in those employed as pumper-gaugers. However, it was based on only four cases.

Chemical Industry↗

PubMed1986

Texaco Mortality Study: II. Patterns of mortality among white males by specific job groups.

While an earlier report on the Texaco Mortality Study cohort showed no statistically significant elevations for any cause of death for the white males, it did not preclude any excess risk of mortality within subgroups of workers. In this study, an employee's complete job history was used to determine his work categories, and patterns of mortality were examined for the more common job categories. All of the job categories examined showed deficits for mortality overall, and the patterns seen were similar to those for the entire cohort. Significant elevations were seen in pancreas cancer mortality for office and managerial people and in leukemia mortality for pipefitters and boilermakers. Other elevations of particular interest based on five or more deaths were brain cancer for laboratory workers and benign neoplasms in pipefitters and boilermakers. These associations were examined by latency and years worked, and no consistently positive associations were seen. It was not possible to take into account calendar time of exposure in this type of analysis, nor could any specific chemicals or levels of exposure be associated with the job categories where the standardized mortality ratios were elevated.

Adult↗

PubMed1985

Texaco mortality study. I. Mortality among refinery, petrochemical, and research workers.

The Texaco mortality study is a retrospective follow-up study of all persons who were employed for at least five years in a refining, petrochemical, or research facility and who worked at some time during the period 1947 through 1977. Of the 19,077 white men in the cohort, 14,609 were alive, 4,024 were known to be dead, and the vital status of the remaining 444 was unknown as of Dec. 31, 1977. The standardized mortality ratio (SMR) of 75 for all causes was significantly low, on the basis of 5,332 expected deaths. Statistically significant deficits also were seen for all major causes of death and for cancer of many sites, including lung, stomach, bladder, and colon. The SMR was greater than 100 for six causes of death: pancreas cancer, brain cancer, leukemia, Hodgkin's disease, other lymphatic cancer, and benign neoplasms. However, none of these increases was statistically significant, and all SMRs except that for benign neoplasms (SMR = 148) were under 119.

Adult↗