Browsing by Author "Spruyt, L. L."

Now showing 1 - 5 of 5
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    Endogenous immunoreactive digitalis-like substance in neonatal serum and placental extracts
    (Health & Medical Publishing Group, 1984) Beyers, A. D.; Spruyt, L. L.; Seifart, H. I.; Kriegler, A.; Parkin, D. P.; Van Jaarsveld, P. P.
    Therapeutic levels of digoxin in the serum of untreated neonates delivered to mothers who had not received the drug prenatally were detected by radio-immunoassay. Digoxin levels in neonates should be interpreted with care because of the unknown contribution by the endogenous digitalis-like substance (DLS) to the level of the drug. Three commercially available radio-immunoassay kits were compared with regard to their sensitivity and reproducibility in detecting the endogenous DLS. The kit from Clinical Assays (Cambridge, Mass., USA) was selected for further investigations. In a series of 35 paired samples of maternal and cord blood the average DLS values in terms of digoxin were 0.52 ± 0.07 and 0.81 ± 0.27 ng/ml respectively. This difference is statistically highly significant. In the case of infants with DLS values of 1-1.5 ng/ml in terms of digoxin, approximately 1 week was required to reach non-therapeutic digoxin levels, i.e. below 0.5 ng/ml. Gel chromatography showed that the DLS in neonatal serum was more closely associated with protein than is authentic digoxin. In placental extracts it followed the elution profile of the protein completely, but it shifted to fractions with a lower molecular weight than haemoglobin after trypsinization. The level of DLS in neonatal serum was also increased by more than half its original value by trypsinization. Proteolysis therefore seems to have a releasing effect on DLS. The molecular size of this substance is probably in the same range as that of polypeptides, since it was not dialysable from trypsinized and untreated samples through a membrane with a 22,000 dalton molecular weight cut-off point.
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    Immunoreactive digitalis-like substance in pre-eclampsia
    (Health & Medical Publishing Group, 1986) Odendaal, H. J.; Beyers, A. D.; Van Heyningen, C. F.; Spruyt, L. L.; Kotze, T. J. van W.; Van Jaarsveld, P. P.
    An endogenous digitalis-like substance (DLS) may be involved in the pathogenesis of essential hypertension and pre-eclampsia. The digoxin levels in maternal and cord blood of 504 randomly selected patients were determined. Since none of the patients received digoxin, these levels indicated a cross-reacting substance (immunoreactive DLS). DLS levels were significantly higher in the cord blood of pre-eclamptic patients than in the cord blood of controls. DLS levels in cord blood increased with the severity of pre-eclampsia, and levels were higher in primigravidas than in multigravidas. The structure and biological activity of DLS must be determined before definite conclusions about its role in the pathogenesis of pre-eclampsia can be made.
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    The possible role of endogenous digitalis-like substance in the causation of pre-eclampsia
    (Health and Medical Publishing Group -- HMPG, 1984-06) Beyers, A. D.; Odendaal, H. J.; Spruyt, L. L.; Parkin, D. P.
    Digoxin levels have been reported in neonatal blood when neither the mother nor the baby had received digoxin. An endogenous digoxin-like substance (DLS) that may be causally related to hypertension has been described. Using a commercially available radio-immunoassay kit, we investigated the presence of an immunoreactive DLS in 21 pre-eclamptic mothers, 36 mothers with normal blood pressure (the control group) and their infants. We found mean DLS levels to be higher in cord blood from infants born to the pre-eclamptic mothers than in cord blood from those born to mothers in the control group. Levels were also higher in cord blood than in maternal blood in both the pre-eclamptic and the control groups. DLS seems to be associated with pre-eclampsia. Although further work is needed for verification, a hypothesis on the possible role of DLS in the causation of pre-eclampsia is presented.
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    A prospective study of long-term use of amikacin in a paediatrics department : indications, administration, side-effects, bacterial isolates and resistance
    (Health & Medical Publishing Group, 1990) Hesseling, P. B.; Mouton, W. L.; Henning, P. A.; Kirsten, G. F.; Spruyt, L. L.; Schraader, E. B.; Wessels, G.; Grassman, R.
    Amikacin (Amikin; B-M) was used as the only aminoglycoside for 18 months in a paediatric department within a general hospital because of high levels of resistance of Klebsiella pneumoniae, Pseudomonas aeruginosa and Enterobacter cloacae isolates to tobramycin, gentamicin and netilmicin. Between 1 February 1987 and 31 July 1988, 816 children were treated with a slow intravenous injection at a standardised dose adjusted for weight and age. Respiratory disease was present in 35,8% of 537 neonates, 56,4% of 190 infants and 70,9% of 89 older children. Escherichia coli (65 isolates), Klebsiella species (59 isolates), Enterobacter species (26 isolates) and P. aeruginosa (22 isolates) constituted the most common Gram-negative pathogens. The positive blood culture yield was 7,8%. Satisfactory median peak and trough serum amikacin levels were achieved. No significant renal side-effects were noted. Severe bilateral hearing loss in 1 low-birthweight infant resulted from inadvertent overdosage. At the end of this 18-month surveillance period 97,7% of E. coli, 98,6% of K. pneumoniae, 96,3% of E. cloacae, and 98,0% of P. aeruginosa isolates remained sensitive to amikacin, while resistance of K. pneumoniae to tobramycin, netilmicin and gentamicin decreased significantly (P < 0,003, P < 0,001 and P < 0,007 respectively; chi-square test).
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    Therapeutic monitoring as an aid in rationalising aminoglycoside dosage techniques in the neonate
    (Health & Medical Publishing Group, 1987) Spruyt, L. L.; Kirsten, G. F.; Parkin, D. P.; Muller, G. J.; Kriegler, A.
    General pharmacokinetic parameters applicable to adults are not suitable in neonatal practice owing to wide interpatient variations in respect of fluid balance, renal clearance and metabolic rates. We attempted to determine whether acceptable blood levels of gentamicin or tobramycin are obtained with dosage regimens and dosage techniques which are generally recommended. Forty neonates receiving aminoglycosides were studied. After administration of the drug as a slow, constant intravenous infusion into the 'Y' connection of the infusion set, peak levels were found to be subtherapeutic. Trough levels were also very low. After administration of the same dose of gentamicin or tobramycin as a bolus into the butterfly connection of the infusion set, however, high therapeutic levels were obtained. We therefore recommend that gentamicin and tobramycin be administered as an intravenous bolus injection and that blood levels be monitored constantly in order to individualise therapy.