Rectal methohexital sedation for computed tomography imaging of stable pediatric emergency department patients.

OBJECTIVE: Rapid onset of sleep, brief duration of action, and ease of administration are properties that make rectal methohexital (MXT) an attractive choice for sedating stable pediatric emergency department (ED) patients for computed tomography (CT) imaging. METHODOLOGY: One hundred stable patients between 3 and 60 months of age who presented to any of 3 participating EDs and required sedation to undergo CT scanning were given 25 mg/kg of rectal MXT approximately 15 minutes before their imaging. Vital signs and oxygen saturation were recorded at regular intervals. Data collected included indication for CT imaging, time to achieve sleep, time to reach discharge criteria, adequacy of sedation, adverse effects, and parental satisfaction. RESULTS: Ninety-five percent of the patients were adequately sedated with rectal MXT. It took an average of 8 minutes to achieve full sedation and the duration of action averaged 79.3 minutes. Ten percent had transient side effects, but all recovered completely. None required intubation. Parental satisfaction was 90%. CONCLUSION: Rectal MXT compares favorably to other methods of nonintravenous sedation for CT scanning of stable pediatric ED patients in terms of rapidity of onset and reliability but does cause a significant amount of transient respiratory depression. Its use requires careful monitoring of oxygen saturation and should be used only in a setting where physicians skilled in airway management are present. If these requirements are met, it may be a good choice for the relatively noninvasive sedation of pediatric ED patients undergoing painless but anxiety-provoking procedures.methohexital, pediatric procedure sedation, rectal administration, computerized tomography imaging.

Parallel synthesis of 1,2,4-oxadiazoles using CDI activation.

1,2,4-Oxadiazoles have been prepared in parallel using 1,1'-carbonyldiimidazole (CDI) as a reagent for both formation and cyclodehydration of O-acyl benzamidoximes. The use of CDI facilitates parallel purification of the oxadiazole products by simple liquid-liquid extraction and filtration.

Automated chemical synthesis: from resins to instruments.

Solid-phase organic synthesis is now a prevalent activity in drug discovery. In keeping with this keen interest is the need to develop reliable automated synthesis instrumentation as well as polymeric supports and linkers suitable for the full range of organic synthesis applications. In this paper, we review our activities in the development of new and enabling tools for automated chemical synthesis, including the following: (i) new solid supports such as ArgoGel (PS-PEG-based) and Argo-X203 (PS-based); and (ii) the Nautilus 2400 system, a fully closed and inert automated chemistry development workstation. Selected chemistry optimization and synthesis examples performed on the Nautilus and new solid supports will be described.

Interference by pro-apolipoprotein A-I in apolipoprotein E phenotyping using chemical precipitation procedures.

Lipoproteins of density, d less than 1.063, isolated by polyanion-cation precipitation methods, gave isoelectric focussing patterns of apolipoprotein E isoforms by rod-gel electrophoresis which differed from the corresponding patterns obtained from ultracentrifugally-derived very low density lipoproteins. The differences were sporadic and variable but the most common effect was an increased frequency of the E3 isoform. Two-dimensional analyses involving sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoelectrophoresis against anti-apolipoprotein A-I indicated that contamination of precipitated lipoproteins with pro-apolipoprotein A-I was responsible for this phenomenon. It is suggested that two-dimensional techniques should be applied for definitive phenotyping if precipitated lipoproteins are used as source material.

Loss of A-apoprotein immunoreactivity during high-density lipoprotein separation.

By use of an electroimmunoassay, concentrations of A-apoproteins were estimated in serum and in corresponding apoprotein fractions isolated by ultracentrifugation. These values were compared with high-density lipoprotein concentrations determined by analytical ultracentrifugation. Concentrations of A-apoproteins estimated in serum were considerably higher than in isolated high-density lipoprotein fractions. These discrepancies could not be accounted for entirely by material losses into other fractions during ultracentrifugal fractionation. No comparable differences in apoprotein-B concentrations were observed during the ultracentrifugal separation of low-density lipoprotein. Concentrations of A-apoproteins estimated in the residual serum after precipitation of low-density lipoproteins by heparin and manganous ions were also lower than in the corresponding whole sera. The discrepancies persisted after treatment of serum and isolated fractions with tetramethylurea, urea (9 mol/l), and by heating at 52 degrees C for 3 hours. It is considered that separation by ultracentrifugation induces subtle alterations in the surface structure of the lipoprotein species which give rise to changes in immunoreactivity.

Evaluation of the polyethylene glycol precipitation method for the estimation of high-density lipoprotein cholesterol.

Treatment of fresh sera with polyethylene glycol 6000 at a final concentration of 100 g/l produced selective precipitation of low-density lipoproteins with only traces of contamination with high-density lipoproteins, as determined by electroimmunoassay using antisera to human alpha1-lipoprotein and human beta-lipoprotein. Supernatants collected for high-density lipoprotein-cholesterol estimation were free from low-density lipoproteins. Precipitates sedimented readily from specimens with high triglyceride contents, and secondary precipitation during enzymatic cholesterol determinations was absent. Values obtained by this method correlated well with those obtained by precipitation of low-density lipoproteins with heparin and manganous ions at concentrations optimal for discrete of lipoprotein classes (r = 0.975; p less than 0.001).

Changes in serum creatine kinase isoenzyme activities after surgical procedures and cardioversion.

Serum activities of creatine kinase (CK) and its isoenzymes were monitored before and 16 to 20 hours after a variety of surgical procedures and cardioversion. Changes in total CK and CK MM activities in the surgical patients were consistent with the extent of trauma; changes in these activities in the cardioversion patients were more variable, ranging from -2 to 1829 U/l, and were unrelated to the applied electrical force. CK MB activity was unchanged after cystoscopy but rose moderately in 60% of patients after cholecystectomy, in 43% of patients requiring only implantation of a new pacemaker box, and in 87% of patients after implantation of an entire pacemaker system. No increase exceeded 6U/l. Fifty per cent of patients requiring cardioversion showed rises; the maximum value was 40.9 U/l.

Selective precipitation of very low density lipoproteins from fasting sera by heparin and manganese ions.

Complete and discrete precipitation of very low density lipoproteins (VLDL) from fasting sera required heating at 40 degrees C for 60 min in the presence of 0.05 M manganous ions and heparin in a concentration dependent upon the VLDL content. The minimum polyanion concentration, employed with VLDL contents less than 1.0 g/l, was 85 mg/l; an increment of 5 mg/l was required for each 1.0 g/l increase in VLDL content. The products isolated by this procedure had electrophoretic, immunochemical and ultracentrifugal characteristics skin to those of native VLDL and were slightly contaminated with albumin. The reaction conditions did not affect adversely the subsequent precipitation of low density lipoproteins.

Plasma catecholamine levels and cardiac rhythm before and after cardiac catheterisation.

Plasma catecholamine concentrations were estimated in a group of 17 fasting patients immediately before and 3 days after cardiac catheterisation. At both times electrocardiograms were recorded and blood pressures, heart rates, and respiration rates measured. Control catecholamine values were established in a group of 10 male and 10 female volunteers, bled at the same time of day under the same conditions of nutrition and posture. Levels of adrenaline and noradrenaline were increased substantially before catheterisation; 3 days later, the values were comparable to those of the control group, though still marginally higher. The increments in catecholamine levels were independent of sex and of the presence or otherwise of persistent supraventricular arrhythmias. In spite of the considerably raised catecholamine levels, electrocardiographic patterns remained unchanged, as did the other physiological values. The absence of any relation between enhanced catecholamine secretion and physiological effects is considered to be the result either of enhanced parasympathetic activity or of adaptation to a prolonged period of stress.

Changes in glomerular filtration rate following myocardial infarction.

Cr EDTA clearance was measured in 10 patients immediately after uncomplicated myocardial infarction and 3 weeks later. The initial values (120 +/- 36 ml/min) were significantly higher than the later values (79 +/- 23 ml/min). Possible reasons for this are reviewed.