Electron‐deficient p‐benzoyl‐l‐phenylalanine derivatives increase covalent chemical capture yields for protein–protein interactions

The photoactivatable amino acid p‐benzoyl‐l ‐phenylalanine (pBpa) has been used for the covalent capture of protein–protein interactions (PPIs) in vitro and in living cells. However, this technique often suffers from poor photocrosslinking yields due to the low reactivity of the active species. Here we demonstrate that the incorporation of halogenated pBpa analogs into proteins leads to increased crosslinking yields for protein–protein interactions. The analogs can be incorporated into live yeast and upon irradiation capture endogenous PPIs. Halogenated pBpas will extend the scope of PPIs that can be captured and expand the toolbox for mapping PPIs in their native environment.     

Nicotine-induced respiratory effects of cigarette smoke in dogs

We report that nicotine is responsible for both a blood-borne stimulation of the respiratory center and a direct effect on intrathoracic airway tone in dogs. We introduced cigarette smoke into the lungs of donor dogs and injected arterial blood obtained from them into the circulation of recipient dogs to show that a blood-borne material increased breathing and airway smooth muscle tone. Smoke from cigarettes containing 2.64 mg of nicotine was effective; that from cigarettes containing 0.42 mg of nicotine was not. Nicotine, in doses comparable to the amounts absorbed from smoke, also increased breathing and tracheal smooth muscle tension when injected into the vertebral circulation of recipient dogs. Finally, blockade of nicotine receptors in the central nervous system and in the airway parasympathetic ganglia inhibited the effects of inhaled cigarette smoke and intravenous nicotine on the respiratory center and on bronchomotor tone. We conclude that nicotine absorbed from cigarette smoke is the main cause of cigarette smoke-induced bronchoconstriction. It caused central respiratory stimulation, resulting in increased breathing and airway smooth muscle tension, and had a direct effect on airway parasympathetic ganglia as well.     

Innervation and neurokinin receptors during angiogenesis in the rat sponge granuloma

Summary Angiogenesis is an essential component of wound healing and inflammation. In the rat subcutaneous sponge implantation model, angiogenesis can be enhanced by administration of the sensory neuropeptide, substance P. We have used quantitativein vitro receptor autoradiography and immunohistochemistry to investigate the development of endogenous neurovascular regulatory systems in the newly-formed granulation tissue of this model. The fraction of endothelial cells immunoreactive for proliferating cell nuclear antigen, endothelial fractional area, and¹³³Xe clearance were used as measures of endothelial proliferation, neovascularization, and blood flow, respectively. Endothelial proliferation occurred predominantly in tissues surrounding the sponge, and peaked before neovascularization of sponge stroma and the establishment of sponge blood flow. Substance P-containing sensory nerves and specific, high affinity substance P binding sites with characteristics of neurokinin receptors of the NK₁ subclass, were localized to microvessels surrounding the sponge at all time points. Lower density substance P binding sites were localized to newly formed microvessels within the sponge stroma, progressively increasing in density from day 4 to day 14. Nerve fibres were observed in the stroma of only 2 of 6 sponges at day 14, and none at earlier time points. These data support the hypothesis that substance P-enhanced angiogenesis in this model results from a direct action on microvascular NK₁ receptors. Neovascularization is a sequential process, with early endothelial proliferation followed by new vessel formation and increased blood flow, with maturation of endogenous neurovascular regulatory systems occurring late in this process in inflamed tissues.