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P McGill

Publications and source records attributed to P McGill.

13 recordsLinked to original sources
PubMed1995

Orientation independence of single-vacancy and single-ion permeability ratios.

Single-vacancy models have been proposed as open channel permeation mechanisms for K+ channels. Single-ion models have been used to describe permeation through Na+ channels. This paper demonstrates that these models have a distinctive symmetry property. Their permeability ratios, measured under biionic conditions, are independent of channel orientation when the reversal potential is zero. This symmetry is a property of general m-site single-vacancy channels, m-site shaking-stack channels, as well as m-site single-ion channels. An experimental finding that the permeability ratios of a channel did not have this symmetry would provide evidence that a single-vacancy or single-ion model is an incorrect or incomplete description of permeation.

Animals↗
PubMed1994

A simple model for surface charge on ion channel proteins.

We present a simple two-parameter model for surface charge directly associated with ion channels. A spherically symmetric "charged shell" models a distribution of surface charge arrayed about the channel entrance, with a corresponding set of image charges behind the plane of the membrane. The transition between a regime of buffered conductance and a regime of rapidly falling conductance at very low ionic strength is found to depend on the magnitude of the surface charge as well as the separation between the charge and the channel entrance. This resolves an apparent discrepancy between the experimental findings of Naranjo and Latorre (1993. Biophys. J. 64:1038-1050) and previous theoretical computations. The charged-shell model is used in a comparative study of the toad skeletal muscle conductance data of Naranjo and Latorre, the rat skeletal muscle conductances of Ravindran et al. (1992. Biophys. J. 61:494-508), and a second set of rat muscle conductances presented in this paper.

Animals↗
PubMed1993

Cytokine and prostaglandin production by monocytes of volunteers and rheumatoid arthritis patients treated with dietary supplements of blackcurrant seed oil.

In this study, dietary supplements of blackcurrant seed oil (BCO) rich in the n-6 polyunsaturated fatty acid (PUFA) gamma-linolenic acid were fed to both RA patients and healthy volunteers with sunflower seed oil being fed to control subjects. A significant improvement in morning stiffness was noted in the RA patients receiving BCO. Monocytes were isolated from all subjects and cultured in the presence of lipopolysaccharide. It was observed that the production from the cultured monocytes of the cytokines IL-1 beta, TNF alpha and IL-6 as well as the prostaglandin PGE2 was markedly altered in those subjects given BCO. The results suggest that the numerous beneficial effects of PUFAs in inflammatory diseases such as RA may be due to a reduction in the secretion of the inflammatory cytokines IL-1 beta and TNF-alpha via redirection of eicosanoid metabolism although the possibility cannot be excluded that the PUFAs may be altering cytokine release directly through an effect on monocyte membranes.

Adult↗
PubMed1985

Adoptive transfer of autoimmune diabetes mellitus in biobreeding/Worcester (BB/W) inbred and hybrid rats.

Adoptive transfer of diabetes was accomplished by the injection of Con A-activated acutely diabetic BB/W rat spleen cells into immunosuppressed diabetes-resistant BB/W control rats and F1 hybrid offspring produced by BB/W X Lewis, BN, Yashida, and NEDH matings. Immune suppression methods that facilitated adoptive transfer of diabetes included neonatal thymectomy, cyclophosphamide, and splenectomy plus rabbit anti-rat lymphocyte serum injections. The successful transfer of BB/W diabetes to otherwise normal (BB/W X inbred)F1 rats and to diabetes-resistant BB/W animals suggests that antigenically normal pancreatic beta cells were destroyed by the injected effector cells. Diabetes-resistant BB/W control rats also evidenced diabetes after the injection of cyclophosphamide alone. The requirement for immunosuppression suggests that an intact immune system protects against adoptive transfer and diabetes in diabetes-resistant BB/W rats.

Animals↗
PubMed1974

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PubMed1974

Disposables.

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