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An analytical method was developed to simultaneously determine sulfadimethoxine (SDM) and ormetoprim (OMP) in medicated animal feeds. SDM and OMP are extracted from the feed into methylene chloride at pH 10 following the addition of tetrabutylammonium hydroxide to form an ion pair with SDM. After the methylene chloride extract is dried over sodium sulfate, an aliquot is purified by solid-phase extraction using a PrepSep silica extraction column. Both compounds are separated by liquid chromatography on an Ultrasphere ionpair column at 3°0C with UV detection at 275 nm. The average recoveries for OMP and SDM in feeds fortified between 0.01 and 0.5% total combined drug ranged from 96.4 to 101.4%, respectively. Replicate assays of typical feeds yielded coefficients of variation of 1.7-3.1%.

Background: The objectives were to compare actual respiratory syncytial virus (RSV) hospitalization rates and costs in a cohort of Inuit infants to hypothetical palivizumab prophylaxis strategies for infants of all gestational ages in the Eastern Canadian Arctic. Methods: Incidence and costs of RSV hospitalization were collected for infants admitted to the Baffin Regional Hospital in 2002, before the initiation of palivizumab. There was a comparison of the actual costs to the costs associated with 8 palivizumab strategies stratified by age (6 months, 1 year) and location (overall, town Iqaluit, rural communities). It was assumed that each category would receive universal palivizumab prophylaxis resulting in a 78% decrease in RSV admissions. The net costs incurred, number needed to treat (NNT), and incremental costs per hospitalization avoided were calculated for each comparison. Results: There was a great variation in the rates and costs associated with RSV admissions between Iqaluit and the communities. For infants 1 year of age residing in Iqaluit, the mean admission cost was $3915, and palivizumab prophylaxis had an NNT of 20.4 and cost of $162,551 per admission avoided. For rural infants 6 months, the mean cost of admission was $23,030, and palivizumab prophylaxis resulted in an NNT of 3.9 to 2.5 and cost savings of up to $8118 per admission avoided. Conclusions: Due to the high rates and costs associated with RSV admissions, administration of palivizumab in rural communities in the Canadian Arctic to infants less than 6 months of age could result in net cost savings.

In several pathological and experimental conditions, the passive membrane conductance of muscle fibers (G(m)) and their excitability are inversely related. Despite this capacity of G(m) to determine muscle excitability, its regulation in active muscle fibers is largely unexplored. In this issue, our previous study (Pedersen et al. 2009. J. Gen. Physiol. doi:10.1085/jgp.200910291) established a technique with which biphasic regulation of G(m) in action potential (AP)-firing fast-twitch fibers of rat extensor digitorum longus muscles was identified and characterized with temporal resolution of seconds. This showed that AP firing initially reduced G(m) via ClC-1 channel inhibition but after approximately 1,800 APs, G(m) rose substantially, causing AP excitation failure. This late increase of G(m) reflected activation of ClC-1 and K(ATP) channels. The present study has explored regulation of G(m) in AP-firing slow-twitch fibers of soleus muscle and compared it to G(m) dynamics in fast-twitch fibers. It further explored aspects of the cellular signaling that conveyed regulation of G(m) in AP-firing fibers. Thus, in both fiber types, AP firing first triggered protein kinase C (PKC)-dependent ClC-1 channel inhibition that reduced G(m) by approximately 50%. Experiments with dantrolene showed that AP-triggered SR Ca(2+) release activated this PKC-mediated ClC-1 channel inhibition that was associated with reduced rheobase current and improved function of depolarized muscles, indicating that the reduced G(m) enhanced muscle fiber excitability. In fast-twitch fibers, the late rise in G(m) was accelerated by glucose-free conditions, whereas it was postponed when intermittent resting periods were introduced during AP firing. Remarkably, elevation of G(m) was never encountered in AP-firing slow-twitch fibers, even after 15,000 APs. These observations implicate metabolic depression in the elevation of G(m) in AP-firing fast-twitch fibers. It is concluded that regulation of G(m) is a general phenomenon in AP-firing muscle, and that differences in G(m) regulation may contribute to the different phenotypes of fast- and slow-twitch muscle.

(1990). Overview on Bound Residue Issues: Introduction. Drug Metabolism Reviews: Vol. 22, No. 6-8, pp. 589-589.

The gas chromatographic behavior of 16 antihistamines was investigated using packed 0.010-in. diameter capillary and 0.065-in. open tubular columns. All packed columns were 6 ft. long, with a low phase to support ratio and were operated at 175°. The liquid phases used were Carbowax 20M, SE-30, XF-1150, and PDEAS. Of the seven solid supports evaluated for use in low loaded columns, only glass beads, Gas Chrom-P, and Chromosorb W-HMDS proved to be satisfactory. The most successful column for the separation of these antihistamines was a 6-ft.–0.08% PDEAS on 120/170 glass-bead column operated at a temperature of 175°. This column provided good separation and symmetrical peaks. Instrument limitations prevented any valid evaluation of the 0.010-in. capillary column and of the 0.065-in. open tubular column for antihistamine separation.

An apparatus has been designed for the determination of microgram quantities of phosphorus-containing compounds. Both inorganic and organic compounds are reduced to phosphine under a stream of hydrogen in a quartz tube at 900-1000°C. The phosphine is separated from other combustion products on sequential alumina and porous polymer bead columns with final measurement by a thermionic GLC detector. The method routinely requires microgram samples with sensitivity capabilities to the nanogram level. The analysis time per sample is less than 5 min.

A preliminary evaluation is given of the use of potentiostatic pulse polarographic techniques for solid-electrode flow-through electrochemical cells as detectors for use in both automated analysis and liquid chromatography. The following advanatages are noted over previously reported constant-applied-potential techniques: increased sensitivity, minimal effect of flow-rate on current measurement and a vast increase in electrode stability for the short-term sampling period and for extended routing operation.

Methods for the analysis of polyether antibiotics in animal tissues and fluids are described. For monensin and nigericin, only methods based on bioautography are available. For lasalocid, in addition to TLC bioautography for quantitation in chicken skin and fat, LC methods based on fluorescence detection have been developed for quantitation in animal blood, milk, liver, skin, and fat. In addition, a confirmatory method for lasalocid is described; this is based on purification by LC followed by silylation and pyrolysis gas chromatography-positive chemical ionization mass spectrometry.

Chekhov, in the brief 44 years of his life, combined active medical work with the creation of many of the world's literary masterpieces. His extraordinary expedition to the penal island of Sakhalin showed both his humanitarian sensibility and his remarkable foresight as a medical investigator. His sure insight into the selection of appropriate practical measures for dealing with famine and a threatened cholera epidemic further illustrates a unique combination of qualities. But above all, it is his imaginative empathy for all men, in all the vagaries of human experience that makes reading his works so rewarding for those who care for the troubled and for the sick. ( JAMA 229:1203-1204, 1974)

Clinical, dermatoglyphic and cytogenetic features of a child with apparently balanced karyotype carrying a presumptive 2/E translocation are presented. The relevance of the karyotypic anomaly to the clinical findings is briefly discussed.

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