Estimation of serum gentamicin by quenching fluoroimmunoassay

A new type of non-isotopic immunoassay, applied to the determination of serum gentamicin, is reported. The method is based on partial quenching of fluorescence observed when fluorescein-labelled gentamicin is bound by anti-gentamicin serum. The fluorescence intensity of the labelled gentamicin in an unseparated immunoassay incubation mixture therefore serves to indicate the extent of binding, which is related to the amount of competing unlabelled gentamicin present. Precision and accuracy are shown to be similar to those of the best existing methods for gentamicin, while the new assay is more rapid and technically simpler, and avoids the use of expensive radio-chemicals with their attendant health hazard. Assays of patient samples correlate with established bioassay and polarisation fluoroimmunoassay methods.     

The surgical management of catheter injuries of the brachial artery

In 84 patients the wrist pulses were lost after diagnostic left heart catheterization via the brachial artery. Sixty-six of these patients underwent surgical exploration of the brachial artery for restoration of pulsatile arterial flow to the hand. This aim was achieved in 64 instances. In all cases, the artery was found to be occluded by fresh thrombus. In 36 patients, balloon thrombectomy and accurate arterial closure were successful. In the remainder, in addition to thrombectomy, indentification of an area of damage to the arterial wall required additional surgical measures, usually in the form of resection and anastomosis. The surgical approach to this problem and the importance of the recognition and treatment of arterial wall damage by the catheter are stressed in this paper.     

Analysis of theoretical behavior of a proposed zero-order drug delivery system

An analysis of the theoretical behavior of a proposed zero-order drug delivery system is presented. Equations describing drug release with time are developed using a physically realistic model. The theory agrees well with experimental data and indicates that drug release from the device is nearly, although not rigorously, zero order.     

Studies on the neurophysiology of the vas deferens

In order to investigate the mechanism of sperm transport along the genital ducts, intraluminal pressure of isolated segments of the vas deferens was recorded in vivo. Responses to filling and mechanical as well as pharmacologic and electric stimulation of the autonomic nervous system were monitored. Contraction waves were initated in response to the stretch of filling and from mechanical stimulation. Pharmacologic response was variable. Low doses of alpha-adrenergic stimulant produced an increase in frequency of the contraction wave. Large doses of the same drug induced stroking contraction of the entire vas. alpha-Blocking drugs did not alter the rhythmic activity of the vas. beta-Adrenergic stimulation blocked peristaltic activity while administration of parasympathomimetic drugs increased the force of contraction. Electric stimulation of the hypogastric nerve produced strong sustained contractions. These data suggest that, whenever stretched, the vas deferens responds by regular peristaltic waves of low amplitude. These peristaltic waves can be enhanced by sympathomimetics or electric stimulation of the sympathetic system. The contents of the vas are propulsed into the urethra through strong rhythmic contractions of the entire vas.     

The effect of coolant loss on current leads for superconducting magnets

In this paper, we have examined the recovery of current leads for superconducting magnets after loss of coolant. It is found that if a lead is without cooling for longer than a time τ_max, thermal runaway can be prevented by an increase in cooling or a decrease in current through the lead. It is evident that designing a lead away from its optimal values can make the lead significantly less susceptible to problems of thermal runaway.