Biomedical subjects
R H Jackson
Publications and source records attributed to R H Jackson.
Paediatric continuous ambulatory peritoneal dialysis.
Ten children in end-stage renal failure were treated by continuous ambulatory peritoneal dialysis (CAPD). This represents a total of 3.4 patient years. Biochemical control was good, and parent and patient acceptability high. Peritonitis was the chief complication, but after the institution of a specific CAPD education and training programme the incidence declined 10-fold. We regard CAPD as an effective short- and medium-term treatment for children with end-stage renal failure as part of an integrated dialysis and transplant programme, but it requires a devoted and enthusiastic trained staff to ensure success.
Relationship of the oxidation state of the iron-sulfur cluster of aconitase to activity and substrate binding.
It is known that aconitase from mammalian mitochondria is only partially active as isolated but may be activated by incubation with iron, ascorbate, and a thiol, or with dithionite. It has been suggested that the added Fe in the activation mixture is essential for activation and that it is incorporated in the enzyme [Villafranca, J. J., & Mildvan, A. S. (1971) J. Biol. Chem. 246, 772-779; Gawron, O., Waheed, A., Glaid, A. J., & Jaklitsch, A. (1974) Biochem. J. 139, 709-714]. However, it is shown in this paper that, when the enzyme has a full complement of 3Fe and 3S, full activation is reached coulometrically, without iron or other chemical reducing agents. It is clear, therefore, that the role of activators is to reduce the iron--sulfur cluster of the enzyme. The appearance of catalytic activity on reduction of the cluster shows a pronounced lag, as does the decay of activity after reoxidizing the cluster. This suggests that catalytic activity requires a conformational change in the protein which is initiated by reduction of the cluster and that, following reoxidation, activity disappears only after the inactive conformation is assumed. Citrate and the competitive inhibitor trans-aconitate are bound to a comparable extent to the active and inactive forms, but only the active form can bind 1-hydroxy-2-nitro-1,3-propanedicarboxylic acid, a transition-state analogue. This is interpreted to show that in the inactive state aconitase cannot enter the conformation it assumes in the transition state during catalysis.
Lacerations from glass in childhood.
A study of 62 glass injuries to children serious enough to warrant admission to hospital showed that 30 were due to architectural glass in doors or windows and 26 of these occurred in houses. Glass bottles caused 12 injuries. Architectural glass produced more serious injuries affecting major arteries, nerves and tendons, and internal viscera. In view of the frequency and severity of architectural glass injuries in houses, safety glass in recommended for all glass doors, French windows, patio doors, and the lower parts of windows.
The steady-state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K 12. Nitrite and hydroxylamine reduction.
The reduction of both NO2- and hydroxylamine by the NADH-dependent nitrite reductase of Escherichia coli K 12 (EC 1.6.6.4) appears to follow Michaelis-Menten kinetics over a wide range of NADH concentrations. Substrate inhibition can, however, be detected at low concentrations of the product NAD+. In addition, NAD+ displays mixed product inhibition with respect to NADH and mixed or uncompetitive inhibition with respect to hydroxylamine. These inhibition characteristics are consistent with a mechanism in which hydroxylamine binds during catalysis to a different enzyme form from that generated when NAD+ is released. The apparent maximum velocity with NADH as varied substrate increases as the NAD+ concentration increases from 0.05 to 0.7 mM with 1 mM-NO2- or 100 mM-hydroxylamine as oxidized substrate. This increase is more marked for hydroxylamine reduction than for NO2- reduction. Models incorporating only one binding site for NAD can account for the variation in the Michaelis-Menten parameters for both NADH and hydroxylamine with [NAD+] for hydroxylamine reduction. According to these models, activation of the reaction occurs by reversal of an over-reduction of the enzyme by NADH. If the observed activation of the enzyme by NAD+ derives both from activation of the generation of the enzyme-hydroxylamine complex from the enzyme-NO2- complex during NO2- reduction and from activation of the reduction of the enzyme-hydroxylamine complex to form NH4+, then the variation of Vapp. for NO2- or hydroxylamine with [NAD+] is consistent with the occurrence of the same enzyme-hydroxylamine complex as an intermediate in both reactions.
Prosthetic groups of the NADH-dependent nitrite reductase from Escherichia coli K12.
A substantially improved purification of Escherichia coli NADH-dependent nitrite reductase was obtained by purifying it in presence of 1 mM-NO2- and 10 microM-FAD. The enzyme was obtained in 20% yield with a maximum specific activity of 1.04 kat . kg-1: more than 95% of this sample subjected to sodium dodecyl sulphate/polyacrylamide-gel electrophoresis migrated as a single band of protein. This highly active enzyme contained one non-covalently bound FAD molecule, and, probably, 5 Fe atoms and 4 acid-labile S atoms per subunit. No FMN, covalently bound flavin or Mo was detected. The spectrum of the enzyme shows absorption maxima at 386, 455, 530 and about 575 nm with a shoulder at 480--490 nm. The Soret-band/alpha-band absorbance ratio is about 4:1. These spectral features are characteristic of sirohaem, apart from the maximum at 455nm, which is attributed to flavin. The enzyme also catalyses the NADH-dependent reduction of horse heart cytochrome c, 2,6-dichlorophenol-indophenol and K3Fe(CN)6. The presence of sirohaem in E. coli nitrite reductase explains the apparent identity of the cysG and nirB gene of E. coli and inability of hemA mutants to reduce nitrite.
The last Jesuit censuses of the Pimeria Alta Missions, 1761 and 1766.
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Case report. Clindamycin associated pseudomembranous colitis.
Pseudomembranous colitis is rare in children. We describe a case associated with clindamycin in which Clostridium difficile and its enterotoxin were isolated from the stool. Treatment with oral vancomycin brought about a prompt and complete recovery.
Epidemic disease and population decline in the Baja California Missions, 1697-1834.
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Avascular necrosis of bone in children receiving high-dose steroid treatment.
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Child-resistant containers.
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[The role of the paediatrician in childhood accident prevention (author's transl)].
The importance of accidents as a cause of death and morbidity in childhood is realized in the countries of the so-called "western" world and in developing countries. The increasing recognition of accidents as a problem has led to paediatricians playing a greater part in accident management and prevention.
Child-resistant containers really are effective.
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Injuries to boys who scramble.
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Accidents in childhood.
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Fracture and complete dislocation of the thoracic or lumbosacral spine: report of three cases.
Severe fracture/dislocation of the thoracic (T) or lumbar (L) spine is usually associated with complete neurological dysfunction below the level of injury. Three cases of severe spinal fracture/dislocation are presented in this report. Two of these patients suffered only partial neurological deficit, which improved after open reduction, internal fixation, and bone fusion. Severe fracture/dislocation of the T or L spine may be quite obvious on lateral roentgenograms. Occasionally, however, the fracture site may be obscured by the overlying shoulders, hips, or soft tissues. If no lateral displacement is evident on anteroposterior (AP) films, a false impression of normal alignment may be given, as was the case in two of our patients. A careful interpretation of the AP view will provide the diagnosis in such cases. The subtle AP radiographic changes suggesting fracture/dislocation of the T or L spine are detailed. The mode of injury, physical findings, prognosis, and surgical treatment of such severe injuries are also briefly reviewed.
Bicycle saddles and torsion of the testis.
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