Biomedical subjects

Yves Boucher

Publications and source records attributed to Yves Boucher.

21 records · Page 2Linked to original sources

PubMed2003

Lack of quinine-evoked activity in rat trigeminal subnucleus caudalis.

Conflicting reports exist regarding the ability of quinine to activate neurons in the trigeminal system. We used the complementary approaches of single-unit electrophysiology and c-fos immunohistochemistry to investigate whether quinine (100 mM) activates chemonociceptive cells in the brainstem trigeminal subnucleus caudalis (Vc). In electrophysiological experiments, 38 units responded to noxious mechanical, thermal and chemical (200 mM pentanoic acid) stimuli applied to the tongue with an increase in firing rate; none responded to lingual quinine whether the quinine was presented before or after application of pentanoic acid. In the c-fos immunohistochemical experiment, both quinine and water elicited equivalent levels of fos-like immunoreactivity (FLI) in dorsomedial Vc that were significantly lower than the level of FLI evoked by pentanoic acid. These data collectively indicate that quinine does not elicit activity in chemonociceptive Vc neurons.

Animals↗

PubMed2002

Lymphatic metastasis in the absence of functional intratumor lymphatics.

Lymphatic metastasis contributes to mortality from solid tumors. Whether metastasizing cancer cells reach lymph nodes via intratumor lymphatic vessels is unknown. Here, we examine functional lymphatics associated with mouse tumors expressing normal or elevated levels of vascular endothelial growth factor-C (VEGF-C), a molecule that stimulates lymphangiogenesis. Although VEGF-C overexpression increased lymphatic surface area in the tumor margin and lymphatic metastasis, these tumors contained no functional lymphatics, as assessed by four independent functional assays and immunohistochemical staining. These findings suggest that the functional lymphatics in the tumor margin alone are sufficient for lymphatic metastasis and should be targeted therapeutically.

Adenocarcinoma↗

PubMed2002

Diffusion and convection in collagen gels: implications for transport in the tumor interstitium.

Diffusion coefficients of tracer molecules in collagen type I gels prepared from 0-4.5% w/v solutions were measured by fluorescence recovery after photobleaching. When adjusted to account for in vivo tortuosity, diffusion coefficients in gels matched previous measurements in four human tumor xenografts with equivalent collagen concentrations. In contrast, hyaluronan solutions hindered diffusion to a lesser extent when prepared at concentrations equivalent to those reported in these tumors. Collagen permeability, determined from flow through gels under hydrostatic pressure, was compared with predictions obtained from application of the Brinkman effective medium model to diffusion data. Permeability predictions matched experimental results at low concentrations, but underestimated measured values at high concentrations. Permeability measurements in gels did not match previous measurements in tumors. Visualization of gels by transmission electron microscopy and light microscopy revealed networks of long collagen fibers at lower concentrations along with shorter fibers at high concentrations. Negligible assembly was detected in collagen solutions pregelation. However, diffusion was similarly hindered in pre and postgelation samples. Comparison of diffusion and convection data in these gels and tumors suggests that collagen may obstruct diffusion more than convection in tumors. These findings have significant implications for drug delivery in tumors and for tissue engineering applications.

Biological Transport↗