Effect of conductivity interfaces in electrocardiography

This paper develops numerical techniques for two problems of interest in electrocardiography: (1) the determination of infinite-media surface potential gradients from boundedmedia torso potentials, and (2) the effects of lung-torso, blood mass-torso, and torso-air conductivity interfaces on torso surface potentials. This paper is an extension of a previous paper on the effects of conductivity interfaces which also utilized an integral equation formulation of Laplace's equation. Supported in part by USPHS Grants HE 05716 and HE 11307 and American Heart Grant 67-850.     

On the origins of esterases

Comparisons among the primary sequences of five cloned eukaryotic esterases reveal two distinct lineages, neither bearing any significant overall sequence similarity to the functionally related serine protease multigene family. We have not eliminated the possibility that the esterases may have residual conformational similarities to the serine proteases. However, our profile analysis and analyses of the predicted conformations of the esterases reveal little similarity to the serine proteases. Four of the esterase proteins share 27%-53% overall sequence similarity and evidence of a catalytic mechanism involving the same Arg- Asp-Ser or His-Asp-Ser charge relay. We propose that these four esterases, three of them cholinesterases, form part of a multigene family essentially separate from the serine proteases.      

Effect of conductivity interfaces

By utilizing an integral equation formulation of Laplace’s equation it is shown that knowledge of the geometry of the conductivity interface, the values of conductivity, and the potentials and gradients on the conductivity interface are sufficient information to determine the infinite media potentials and infinite media potential gradients. The integral equations may be approximated by finite sums and the results can be implemented practically by using a medium size digital computer.     

Towards a unified mechanism of biological methane oxidation

Abstract The biological oxidation of methane to methanol is catalysed by soluble and particulate forms of the enzyme methane monooxygenase. Little information is available regarding the structure and mechanism of the particulate enzyme whereas much is known about the soluble form of the enzyme. This review concentrates on current knowledge of the structure of the components of the soluble methane monooxygenase and draws together these results with those on the kinetics and substrate specificity of the enzyme in a possible chemical mechanism for enzymatic methane oxidation.