Oral health status of children in a Paediatric Intensive Care Unit.

OBJECTIVE: The aim of the present study was to examine the dental status of critically ill children in a Paediatric Intensive Care Unit (PICU) and determine the efficacy of the mouth care received. DESIGN: Prospective nonrandomized study. SETTING: The study was carried out in the PICU at Great Ormond Street Hospital for Children. PATIENTS AND PARTICIPANTS: All children admitted to the PICU during the period of the study were eligible for inclusion. A total of 54 children completed the study. MEASUREMENTS AND RESULTS: Children were examined for dental caries, plaque accumulation, gingival inflammation and gingival bleeding on admission to the PICU. The examination was repeated on discharge from the Unit. The levels of dental caries found on examination were compared with results from the most recent national surveys carried out in the United Kingdom, and analysed using the one sample t-test. The levels of plaque accumulation, gingival inflammation and gingival bleeding on admission were compared to those on discharge and analysed using the paired sample t-test. Results revealed a very highly significant increase in plaque accumulation (p = 0.001), and a highly significant increase in gingival inflammation (p = 0.006) between admission to the PICU and discharge. CONCLUSIONS: Results indicate that the present mouth care regimen is not effective in preventing the build up of plaque or maintaining gingival health. These children may therefore be at unnecessary risk from local or systemic spread of oral microorganisms.

MAD analyses of yeast 5-aminolaevulinate dehydratase: their use in structure determination and in defining the metal-binding sites.

MAD experiments attempting to solve the structure of 5--aminolaevulinic acid dehydratase using Zn and Pb edges are described. The data obtained proved insufficient for a complete structure solution but were invaluable in subsequent identification of metal-binding sites using anomalous difference Fourier analyses once the structure of the enzyme had been solved. These sites include the highly inhibitory substitution of an enzymic cofactor Zn(2+) ion by Pb(2+) ions, which represents a major contribution towards understanding the molecular basis of lead poisoning. The MAD data collected at the Pb edge were also used with isomorphous replacement data from the same Pb co-crystal and a Hg co-crystal to provide the first delineation of the enzyme's quaternary structure. In this MADIR analysis, the Hg co-crystal data were treated as native data. Anomalous difference Fouriers were again used, revealing that Hg(2+) had substituted for the same Zn(2+) cofactor ion as had Pb(2+), a finding of fundamental importance for the understanding of mercury poisoning. In addition, Pt(2+) ions were found to bind at the same place in the structure. The refined structures of the Pb- and the Hg-complexed enzymes are presented at 2.5 and 3.0 A resolution, respectively.

X-ray structure of 5-aminolaevulinate dehydratase, a hybrid aldolase.

5-Aminolaevulinate dehydratase (ALAD) is a homo-octameric metallo-enzyme that catalyses the formation of porphobilinogen from 5-aminolaevulinic acid. The structure of the yeast enzyme has been solved to 2.3 A resolution, revealing that each subunit adopts a TIM barrel fold with a 39 residue N-terminal arm. Pairs of monomers wrap their arms around each other to form compact dimers and these associate to form a 422 symmetric octamer. All eight active sites are on the surface of the octamer and possess two lysine residues (210 and 263), one of which, Lys 263, forms a Schiff base link to the substrate. The two lysine side chains are close to two zinc binding sites one of which is formed by three cysteine residues (133, 135 and 143) while the other involves Cys 234 and His 142. ALAD has features at its active site that are common to both metallo- and Schiff base-aldolases and therefore represents an intriguing combination of both classes of enzyme. Lead ions, which inhibit ALAD potently, replace the zinc bound to the enzyme's unique triple-cysteine site.

Crystallization of 5-aminolaevulinic acid dehydratase from Escherichia coli and Saccharomyces cerevisiae and preliminary X-ray characterization of the crystals.

5-Aminolaevulinic acid dehydratase (ALAD) catalyzes the formation of porphobilinogen from two molecules of 5-aminolaevulinic acid. Both Escherichia coli and Saccharomyces cerevisiae ALADs are homo-octameric enzymes which depend on Zn2+ for catalytic activity and are potently inhibited by lead ions. The E. coli enzyme crystallized in space group I422 (unit cell dimensions a = b = 130.7 A, c = 142.4 A). The best crystals were obtained in the presence of the covalently bound inhibitor laevulinic acid. The yeast enzyme (expressed in E. coli) crystallized in the same space group (I422) but with a smaller unit cell volume (a = b = 103.7 A, c = 167.7 A). High resolution synchrotron data sets were obtained from both E. coli and yeast ALAD crystals by cryocooling to 100 K.

Comparative studies on the 5-aminolaevulinic acid dehydratases from Pisum sativum, Escherichia coli and Saccharomyces cerevisiae.

5-Aminolaevulinic acid dehydratase (ALAD) is an essential enzyme in most organisms, catalysing an inaugural step in the tetrapyrrole biosynthetic pathway, the Knorr-type condensation reaction of two molecules of 5-aminolaevulinic acid (ALA) to form the monopyrrole porphobilinogen. ALADs can be conveniently separated into two main groups: those requiring Zn2+ for activity (typified here by the enzymes from Escherichia coli and Saccharomyces cerevisiae, yeast) and those requiring Mg2+ (represented here by the enzyme from Pisum sativum, pea). Here we describe a detailed comparison of these two metal-dependent systems. Kinetically influential ionizations were identified by using pH-dependent kinetics. Groups with pKa values of approx. 7 and 10 (assigned to cysteine and lysine residues) were detected in the free enzyme and enzyme-substrate states of all three enzymes, and a further ionizable group with a pKa of approx. 8.5 (assigned to histidine) was found to be additionally important to the yeast enzyme. The importance of these residues was confirmed by using protein modifying reagents. Shifts in the pKa values of the pea and E. coli enzymes consequent on E-S complex formation suggest a change to a less hydrophobic micro-environment when substrate binds. Studies with inhibitors revealed that the three enzymes exhibit differential susceptibilities and, in the case of succinylacetone, this is reflected in Ki values that vary by three orders of magnitude. In addition, the crystallization of the yeast ALAD is described, raising the possibility of an X-ray-derived three-dimensional structure of this enzyme.

Can we predict the patient who leaves against medical advice: the search for a method.

Previous attempts to determine a profile of the typical patient who leaves against medical advice (AMA) have been largely unsuccessful. The premature separation from the hospital arouses unresolved feelings in everyone involved, including the patient, and is expensive as well. The theory that a patient left AMA as a result of a malfunction in the contracting process on admission was not replicable in our institution. We found that the largest group of patients leaving AMA was the young male substance abuser, who is usually the most unpopular type of patient. We believe that staff, actively or passively, encourage patients that they do not like to leave AMA. This interpersonal process may be the one which most needs addressing.

Size at birth of Asian and white Caucasian babies born in Leicester: implications for obstetric and paediatric practices.

This investigation extends our knowledge of the size of British born Asian babies compared with those of white Caucasian origin. Seventy Leicester born term Asian babies at birth were lighter, shorter, leaner and had smaller heads than their white Caucasian counterparts. The Asian mothers were shorter and lighter at the start of pregnancy but their weight/height2 index was the same. With the appreciation that the Asian population in Britain is far from homogenous in regard to religion, diet and country of origin, it is concluded that the smaller size at birth of Asian babies is unlikely to be due to undernutrition of their mothers in pregnancy. Genetic factors, as indicated by the shorter stature of the mothers are more likely to be responsible. These findings have implications for obstetric and paediatric practices.

Time estimation and hyperactivity, replication.

Three groups of boys included 135 of normal IQ, showing normal activity; 6 were hyperactive and of normal IQ, and 6 showed normal activity but low IQ. Their ability to estimate a 30-sec. interval showed only the 6 normally active boys of low IQ had significantly different elapsed and estimated times. Time estimation is not clinically useful for identifying hyperactive boys.