The wearing of complete dentures: guidance to patients

The effect of continuous wear of complete dentures in relation to the health of the oral mucosa is discussed. The results of a questionnaire on denture wearing advice among 120 dental schools, revealed divergence of opinions on the subject.     

Control of iron absorption

Intestinal iron absorption plays an essential role in body iron homeostasis, although the mechansim by which iron moves across the cells of the intestinal epithelium and the way in which this process is regulated are poorly understood. Signals to alter iron absorption are received from the body by cells of the intestinal crypt and these signals are translated into an absortion response after the cells have migrated up the villus and differentiated into mature absorptive enterocytes. The intracellular iron concentration of the crypt cell may play an important role in the regulation of this process. Biochemical investigations on the mechanism of iron absorption have met with only limited success and a molecular understanding of this mechanism appears most likely to come from the identification of the genes affected in various inherited disturbances of iron absorption in several mammalian species.     

Gentamicin dosing in neonates: evaluation of a dosing protocol

A study was carried out to examine the dosing of gentamicin and to investigate some of the determinants of serum gentamicin concentrations in neonates at the Royal Hobart hospital, Tasmania, Australia, and to examine the appropriateness of the current dosing protocol (that of the Royal Children's hospital, Melbourne). Clinical and demographic data were retrospectively collected from the records of 39 neonates who had received therapy with gentamicin for suspected or proven septicaemia during the period May to September, 1993. Peak and trough serum concentrations of gentamicin were measured, at least 36 hours after starting therapy. The mean gestational age (± SD) of the sample was 32.3 ± 4.9 weeks, and 30 patients were male. The mean dosage of gentamicin was 4.0 ± 1.3mg/kg/day and the median duration of therapy was 4 days (range 2 to 22 days). Trough serum concentrations of gentamicin ranged from 0.6 to 6.0mg/L (mean 1.9 ± 1.0mg/L), with 35.9 per cent being 2.0mg/L or higher. Peak serum concentrations ranged from 4.3 to 12.9 mg/L (mean 6.1 ± 1.5 mg/L), with 89.7 per cent being between 5.0 and 8.0mg/L. The peak and trough serum concentrations were significantly related, while the total daily dosage of gentamicin and the resulting peak and trough serum concentrations were not significantly related. The trough serum concentration of gentamicin was significantly related to the serum creatinine concentration. Patients who had been dosed correctly according to the protocol were less likely to have a potentially toxic trough serum concentration of gentamicin. Those administered gentamicin every 12 hours tended to have higher serum trough concentrations of the drug than those who received it either 18- or 24-hourly. This study has confirmed that excessive serum concentrations of gentamicin occur frequently in neonates, a situation which may be improved by greater usage of an 18-hourly dosing regimen and prompt adjustment of dosage according to renal function.     

Rapid purification of radioiodinated peptides with Sep-Pak® reversed phase cartridges and HPLC

A simple, rapid method is described for the purification of radioiodinated peptides for use in radioimmuno- and in radioreceptor assays. Iodinated reaction mixtures are applied directly onto Sep-Pak® disposable, reversed phase cartridges equilibrated with phosphate buffer. Unreacted 125-iodide and other non-peptide reaction components are eluted with buffer. The peptide fraction is then eluted with 70% buffer:30% acetonitrile. The peptide fraction is further purified by reversed phase high pressure liquid chromatography to separate the native peptide and the mono- and diiodo-derivatives. In this study the method is used to prepare 125-iodide-labeled monoiodo-leucine enkephalin and monoiodo-angiotensin II, which are free of the parent peptides and diiodo-derivatives and are of maximum obtainable specific radioactivity. The usefulness of these labeled peptides in radioimmuno- and radioreceptor assays is demonstrated by their binding to specific antibodies and receptors, respectively.