Metabolic acidosis and fatal myocardial failure after propofol infusion in children: five case reports.

OBJECTIVE--To examine the possible contribution of sedation with propofol in the deaths of children who were intubated and required intensive care. DESIGN--Case note review. SETTING--Three intensive care units. SUBJECTS--Five children with upper respiratory tract infections aged between 4 weeks and 6 years. RESULTS--Four patients had laryngotracheo-bronchitis and one had bronchiolitis. All were sedated with propofol. The clinical course in all five cases was remarkably similar: an increasing metabolic acidosis was associated with brady-arrhythmia and progressive myocardial failure, which did not respond to resuscitative measures. All children developed lipaemic serum after starting propofol. These features are not usually associated with respiratory tract infections. No evidence was found of viral myocarditis, which was considered as a possible cause of death. CONCLUSION--Although the exact cause of death in these children could not be defined, propofol may have been a contributing factor.     

Enzymes of urate synthesis and catabolism in the Gecarcinid land crab Gecarcoidea natalis

This study investigated the sites of urate synthesis and catabolism in the gecarcinid land crab Gecarcoidea natalis by assaying spongy connective tissue, midgut gland, muscle and gill for xanthine oxidoreductase, the last enzyme involved in urate synthesis, and uricase and urease, the first and last enzymes involved in urate catabolism. The spongy connective tissue and midgut gland of the G. natalis contained activities of xanthine oxidoreductase and were considered to be sites of urate synthesis. The midgut gland had a high activity of xanthine oxidoreductase [(58.87±4.6 (SE) nmol urate produced g^-1 wet wt. tissue min^-1], 2.7 times the xanthine oxidoreductase activity contained within the spongy connective tissue, and was thought to be the main site of urate synthesis. Xanthine dehydrogenase (EC 1.1.1.204) was the only form of xanthine oxidoreductase detected within the tissues. Its presence means that the cost of synthesising urate de novo is relatively small (between 1 and 3 ATP). Uricase (EC 1.7.3.3) and urease (EC 3.5.1.5) activities were present in the tissues of G. natalis. Spongy connective tissue contained the highest activities of uricase [48.44±4.29 (SE) nmol urate consumed g^-1 wet wt. tissue min^-1] while the highest activities of urease [365.31±37.21 (SE) nmol urate consumed g^-1 wet wt tissue min^-1] were contained within the gills. From this evidence it is clear that G. natalis possesses the uricolytic pathway and hence the ability to catabolise urate, and urate catabolism is begun at the site of urate storage, the spongy connective tissue, and is completed at the gills. As the gills are the site of ammonia excretion in this species the ammonia produced from the catabolism of urate is probably excreted. The urate deposits within the body of G. natalis may be involved in temporary storage of nitrogenous wastes.     

Fluorescence lifetime and polarization anisotropy studies of membrane surfaces with pyridoxal 5'-phosphate

The fluorescence lifetime and depolarization of the pyridoxal 5'-phosphate label demonstrated different environments at the structure-solvent interface for micelles, liposomes, proteins and membranes. A short lifetime and rotational correlation time for the micelles and liposomes proved that the label was strongly associated with the water solvent and rotated freely about the covalent bond. The proteins provided a more buried or hydrophobic site as shown by an increase in the lifetimes. Rotational correlation times of 4-6 ns for sarcolemma and erythrocyte membranes suggested restricted rotation for the pyridoxal 5'-phosphate label. Lower values of the rotational correlation time for rod outer segment and myelin sheath proved that the protein epsilon-amino groups are at the solvent interface which allows for more rotation.     

Growth of Paracoccus denitrificans on [2,3-13C]succinate and [1,4-13C]succinate. II. Isoleucine biosynthesis

Paracoccus denitrificans was grown on either [2,3-13C]succinate or [1,4-13C]succinate, and extracts were analysed by using gas chromatography-mass spectrometry. The distribution of label in isoleucine indicated that the 2-ketobutyrate required for isoleucine biosynthesis was mainly produced from pyruvate by 2-keto-acid chain elongation (i.e. the 'pyruvate elongation pathway'). Approximately 10% of isoleucine was produced by a second pathway involving propionyl CoA. Threonine and glutamate were not utilized by P. denitrificans as a source of 2-ketobutyrate production for isoleucine biosynthesis under the growth conditions used.     

The regulation of haemolymph calcium concentration of the crab Carcinus maenas (L.).

After acclimation, Carcinus can maintain calcium balance in dilute (35-100%) but not in low calcium sea water. 71% of total haemolymph calcium (9-54 +/- 0-42 mM) was in ionic form as compared with 90-9%(9-9mM) in sea water. On acclimation to dilute sea water the calcium activity of the haemolymph was greater than that of the medium, the difference being maintained by active calcium uptake. Carcinus is highly permeable to Ca2+, influx from sea water being 0-513 +/- 0-07 mumoles g-1 h-1 and the time constant for calcium influx 4-3 +/- 0-48 h. Calcium space represented ca. 25% wet body weight independent of body size or salinity of acclimation medium.     

The binding of copper ions to daunomycin and adriamycin

Using visible absorption, CD, ¹H nmr, and epr spectroscopy, the Cu(II) binging properties of daunomycin, adriamycin, and N-trifluoroacetyl daunomycin in water and ethanol have been explored. The drugs form two water soluble complexes having Cu-drug stoichiometries of 1:1 and 1:2, and with apparent pK_as of formation of 5.6 and 6.5, respectively. At pH values above ～8, the drugs form insoluble polymeric complexes with Cu(II). Similar species are also observed in ethanol. The structure of the compounds have been interpreted in terms of binding of the deprotonated hydroxyquinone portion of the drug to the copper ion. No evidence for the binding of the amino group on daunosamine was found.