Histamine, histamine antagonists and regional blood flow

The effects of mepyramine, a selective histamine H1-receptor antagonist, and metiamide, a selective histamine H2-receptor antagonist, have been determined on the cardiovascular response to intravenous infusions of a large dose of histamine, 1 X 10(-7) mol/kg/min. Pretreatment with either mepyramine, 2.5 X 10(-6) mol/kg, or metiamide, 2 X 10(-6) mol/kg/min, had no significant effect on the fall in blood pressure or fall in total peripheral resistance during histamine infusion. Pretreatment with mepyramine, 2.5 X 10(-6) mol/kg, and metiamide, 2 X 10(-6) mol/kg/min, abolished the fall in blood pressure and total peripheral resistance during infusion of histamine. Histamine-induced vasodilatation in the stomach was unaltered by pretreatment with mepyramine but abolished by pretreatment with metiamide. Histamine-induced coronary vasodilation was reduced slightly by pretreatment with mepyramine and substantially by pretreatment with metiamide. Coronary vasodilatation was abolished by treatment with mepyramine and metiamide.     

A refined higher-order C° plate bending element

A general finite element formulation for plate bending problem based on a higher-order displacement model and a three-dimensional state of stress and strain is attempted. The theory incorporates linear and quadratic variations of transverse normal strain and transverse shearing strains and stresses respectively through the thickness of the plate. The 9-noded quadrilateral from the family of two dimensional C° continuous isoparametric elements is then introduced and its performance is evaluated for a wide range of plates under uniformly distributed load and with different support conditions and ranging from very thick to extremely thin situations. The effect of full, reduced and selective integration schemes on the final numerical result is examined. The behaviour of this element with the present formulation is seen to be excellent under all the three integration schemes.     

A simple model for mechanical anisotropy in specially oriented sheets of low-density polyethylene

The anisotropy of the elastic modulus of specially prepared sheets of drawn, rolled and annealed low-density polyethylene has been analysed quantitatively. These materials were regarded as two-phase composites of crystalline and amorphous regions, in which the interlamellar regions of the polymer were assumed to deform under load by both pure shear and simple shear mechanisms. The anisotropy of the a–b and parallel lamellae structures agrees well with the predictions of this simple theory.     

A subject-indexed bibliography of discrete event dynamic systems

A subject-indexed bibliography of discrete event dynamic systems is given. Each subject is briefly described and some characteristic topics and references for each subject are listed. The complete reference list is provided on the ftp-site and instructions how to retrieve related files are given     

An immunohistochemical study of neuronal microtubule-associated proteins in Hirschsprung's disease

Neuronal microtubule-associated proteins (MAPs) are important components of neurons and are believed to regulate neuronal function and development by controlling the assembly of microtubules and the interaction of microtubules with other cytoplasmic organelles. We studied the immunohistochemical localization of MAPs 1, 2, 5, and tau in the intestinal tissues of five patients with Hirschsprung's disease and in five normal controls using monoclonal antibodies. Microtubule-associated proteins 5 and tau proved to be excellent enteric neuronal markers; they were specifically located in the nerve cell bodies and processes of normal intestine as well as in the abnormal hypertrophied nerve fibers of aganglionic colon. Fine fibrillar structures in the neuroplasm were revealed in greater detail than were those obtained from studies with conventional markers, including neuron-specific enolase, S-100 protein, and neurofilament protein. A slight reduction of MAPs 5 and tau immunoreactivity was observed in the aganglionic colon compared with normal colon. Microtubule-associated proteins 1 and 2 were absent from the nerve fibers in both normal and aganglionic colon. This study suggests that immunostaining for MAPs 5 and tau may be superior to other immunohistochemical methods for diagnosing Hirschsprung's disease; however, in view of its limited retrospective nature these findings need to be corroborated by a large prospective evaluation.     

Analysis of the ferroresonant transformer with a rectified outputin the low-line-voltage minimum-line-frequency full-load condition

Most previous analyses of the ferroresonant transformer address the unrectified-output AC-load case, and do not include some or all of the important loss mechanisms. The analysis reported in this paper addresses the rectified-output DC-load case and includes the stray losses. The low-line-voltage minimum-line-frequency full-load condition is the focus of this analysis because it is the worst-case condition for supplying power to the load. Assumptions about the operation of the transformer in this worst-case condition lead to a simplified equivalent circuit. Given equivalent-circuit element values, a special-purpose time-domain computer simulation analyzes transformer performance in the periodic steady-state condition. This analysis technique is used to find equivalent-circuit element values for which the transformer winding currents are a minimum and the input power factor and conversion efficiency are at a maximum