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Biomedical subjects

J E Willett

Publications and source records attributed to J E Willett.

7 recordsLinked to original sources

Alloimmune neonatal neutropenia linked to anti-HNA-4a.

This is a novel case report of alloimmune neonatal neutropenia (ANN) linked to the neutrophil antibody anti-HNA-4a (MART). Since its discovery, the HNA-4a antigen has never been associated with any clinical neutropenia. A first-born neonate with respiratory distress was found to be severely neutropenic, because of ANN. The broad reactivity of the antibody together with its capture by CD11b and CD18 in monoclonal antibody immobilization of granulocyte antigen test suggested HNA-4a specificity. DNA sequencing confirmed that the father is HNA-4a-positive and that the mother is HNA-4a-negative, supporting the diagnosis of ANN linked to MART.

Antigen-Antibody Reactions↗

Atrial arrhythmia suppression by atrial overdrive pacing: pacemaker Holter assessment.

The purpose of this study was to assess the efficacy of overdrive, single-site right atrial appendage pacing to reduce the burden of atrial fibrillation (AF) when compared with a standard lower rate limit of 60 bpm. This was verified by using the pacemaker's Holter. Eighteen subjects with a pre-implant history of paroxysmal AF and implanted DDDR mode-switching pacemakers were recruited. The pacemaker lower rate limit was programmed in random order to 60, 75 or 90 bpm for three 2-month periods and the amount of AF quantified. In addition, the exercise tolerance (ET), general well being (GWB), functional capacity (FC) and specific symptom prevalence (SSP) were assessed. The main finding of the study was that when ranked according to the amount of AF, there was no significant difference in the amount of AF according to the pacing rate. Six patients failed to tolerate pacing at 90 bpm. There were no differences in the ET, GWB, FC and SSP scores. It is concluded that those clinicians that manage patients with paroxysmal

Adult↗

Equilibrium orbit analysis in a free-electron laser with a coaxial wiggler.

An analysis of single-electron orbits in combined coaxial wiggler and axial guide magnetic fields is presented. Solutions of the equations of motion are developed in a form convenient for computing orbital velocity components and trajectories in the radially dependent wiggler. Simple analytical solutions are obtained in the radially-uniform-wiggler approximation and a formula for the derivative of the axial velocity with respect to the Lorentz factor gamma is derived. Results of numerical computations are presented and the characteristics of the equilibrium orbits are discussed. The third spatial harmonic of the coaxial wiggler field gives rise to group III orbits which are characterized by a strong negative mass regime.

Journal Article↗

Wiggler-field effects on the space-charge waves of a Raman free-electron laser.

An analysis of the propagation of a space-charge wave through the wiggler and axial magnetic fields of a free-electron laser is presented. The relativistic electron beam is contained within and only partially fills a cylindrical metallic waveguide. A theory is developed using lab-frame Maxwell and fluid equations in a form which is equivalent to the electrostatic approximation in the beam frame. The computational method of determining the dispersion relation is described and some numerical results are presented which illustrate effects arising from the wiggler and the partially filled waveguide.

Journal Article↗

Androgen-responsive functions of male rat liver. Effect of chronic alcohol ingestion.

Many liver processes are sexually dimorphic, and in rats, testosterone is the major steroid hormone determinant of the differing patterns of hepatic function. The microsomal content of specific enzymes and the syntheses of specific proteins are dependent on serum testosterone to maintain this dimorphism. Because the liver of male rats is strikingly androgen responsive, and because chronic alcohol ingestion decreases serum testosterone, we sought to determine whether chronic alcohol feeding would alter the masculine pattern of hepatic liver function in male rats. We quantitated both the cytosolic and nuclear forms of the hepatic androgen receptor. Alcohol feeding of male rats results in a significant loss of both types of androgen receptor sites; the specific binding capacity of both cytosolic and nuclear receptor in alcohol-fed rats is reduced to about 30% of that in either isocalorically fed rats or rats fed ad libitum. This reduction in hepatic androgen receptor activity is concomitant with a 50% reduction in serum testosterone content in the alcohol-fed animals. In addition, the activities of two hepatic androgen-responsive proteins, namely a cytosolic estrogen binder and a microsomal enzyme, estrogen 2-hydroxylase, demonstrate a decrease in activity that parallels the decreases in both forms of the androgen receptor. Administration of testosterone to the alcohol-fed animals normalized both the hepatic androgen receptor and the androgen-responsive protein activities. From these results, we conclude that chronic alcohol feeding results in a decreased androgen responsiveness of the liver, a condition that most likely results from the decreased serum testosterone levels in the alcohol-fed animals.

Androgens↗