The proton RBE and the distal edge effect for acute and late normal tissue damage in vivo.

Background And Purpose: In proton therapy, a relative biological effectiveness (RBE) of 1.1 is used toreach an isoeffective biological response between photon and proton doses. However, the RBE varies with biological endpoints and linear energy transfer (LET), two key parameters in radiotherapy.

An experimental setup for proton irradiation of a murine leg model for radiobiological studies.

Background: The purpose of this study was to introduce an experimental radiobiological setup used for irradiation of a mouse leg target in multiple positions along a proton beam path to investigate normal tissue- and tumor models with varying linear energy transfer (LET). We describe the dosimetric characterizations and an acute- and late-effect assay for normal tissue damage.

Methods: The experimental setup consists of a water phantom that allows the right hind leg of three to five mice to be irradiated at the same time.

Rat mesenteric small artery neurogenic dilatation is predominantly mediated by β -adrenoceptors in vivo.

Key Points: The prevailing dogma about neurogenic regulation of vascular tone consists of major vasodilatation caused by CGRP (and possibly substance P) released from sensory-motor nerves and vasoconstriction caused by noradrenaline, ATP and neuropeptode Y release from sympathetic nerves. Most studies on perivascular nerve-mediated vasodilatation are made in vitro. In the present study, we provide evidence indicating that in vivo electrical perivascular nerve stimulation in rat mesenteric small arteries causes a large β1-adrenoceptor-mediated vasodilatation, which contrasts with a smaller vasodilatation caused by endogenous CGRP that is only visible after inhibition of Y1 NPY receptors.

Allosteric mechanisms underlying the adaptive increase in hemoglobin-oxygen affinity of the bar-headed goose.

The high blood-O affinity of the bar-headed goose () is an integral component of the biochemical and physiological adaptations that allow this hypoxia-tolerant species to undertake migratory flights over the Himalayas. The high blood-O affinity of this species was originally attributed to a single amino acid substitution of the major hemoglobin (Hb) isoform, HbA, which was thought to destabilize the low-affinity T state, thereby shifting the T-R allosteric equilibrium towards the high-affinity R state. Surprisingly, this mechanistic hypothesis has never been addressed using native proteins purified from blood.