The reaction of yeast alcohol dehydrogenase with iodoacetamide as determined with a silver-silver iodide electrode.
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Alcohol Oxidoreductases↗
Biomedical subjects
D C Watts
Publications and source records attributed to D C Watts.
The number of catalytic sites in creatine phosphokinase as determined by a study of its reactive sulphydryl groups.
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Journal Article↗
False elevation of amniotic fluid enzymes of relevance for prenatal diagnosis: creatine kinase measurement in relation to Duchenne muscular dystrophy.
The creatine kinase activity of amniotic fluid was measured in samples collected at fetoscopy. In our first study, the control sample range was 0.25 IU/l, although four samples had activities of 35-85 IU/l. Elevated values did not correlate with the activities in the fetal or maternal circulations. Electrophoresis revealed the presence of the BB isozyme of creatine kinase rather than just the MM form as expected. This suggested that the source of the elevated enzyme activity was from the myometrium, damaged by insertion of the trocar and cannula. In a further series the first 2 ml of amniotic fluid withdrawn yielded a much higher creatine kinase activity than a second aliquot. A control series of such second samples (first 2 ml discarded) gave an activity range of 0-7 IU/l with no spuriously high values. This compares favourably with a series from single samplings taken by amniocentesis. Normal creatine kinase activities were found in the amniotic fluids from 20 pregnancies at risk of Duchenne muscular dystrophy. We conclude that for accurate measurement of amniotic fluid enzyme activity the first portion withdrawn should be discarded. Amniotic fluid creatine kinase activity is of no value for the prenatal diagnosis of Duchenne muscular dystrophy.
Amniocentesis↗
Errors in plasma creatine kinase estimations on fetal blood samples resulting from contamination with amniotic fluid and maternal blood: relevance for the prenatal diagnosis of Duchenne muscular dystrophy.
This paper presents a detailed analysis of the calculation of fetal plasma CK activity in fetal blood samples contaminated with amniotic fluid and maternal blood. The seemingly simple formula for this calculation, first presented by Mahoney et al. (1977), is actually more complex than it appears; values for up to nine variables, two of which can only be assumed, are needed. Small variations in certain variables may result in very large errors in the final calculated value of fetal plasma CK activity. Examples of diluted blood samples are considered and the effects of allowing for reasonable errors in the variables is explored. The main source of error is in the measurement of CK activities in the diluted blood sample and in the amniotic fluid. Contamination by blood originating from the maternal circulation can also be a large source of error, especially if the mother is a carrier of DMD and maintains a high level of plasma CK activity during pregnancy. Fetal blood indices have to be assumed; these may be a source of significant error, depending on the difference between the actual and assumed values. The measurement of fetal plasma CK activity by the indirect calculation method is discussed in the context of the prenatal diagnosis of DMD.
Amniocentesis↗
Creatine kinase estimation in pure fetal blood samples for the prenatal diagnosis of Duchenne muscular dystrophy.
This paper compares the results of a survey of plasma creatine kinase (CK) activity measured in fetuses at-risk for Duchenne muscular dystrophy (DMD) with a reliable control series. Only pure fetal blood samples obtained by fetoscopy at between 17-24 weeks gestational age were used. Of the at-risk group 19 male pregnancies, mostly at low risk for DMD, proceeded to term with a normal outcome; there was no significant difference between their fetal plasma CK activities and the control group. Another 21 male pregnancies were terminated. This group included the highest risk mothers and hence was expected to contain a significant proportion of affected fetuses. The fetal plasma CK activity range was overlapping but significantly higher than the control group. No grossly elevated CK value was obtained. We conclude that, on average, DMD fetuses at this gestational age have higher plasma CK activity than controls. The problems of applying this finding to the prenatal diagnosis of DMD are discussed.
Creatine Kinase↗
Dental materials: 1995 literature review.
This critical review of the published literature on dental materials for the year 1995 has been compiled by the Dental Materials Panel of the United Kingdom. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. Emphasis has been placed upon publications which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, resin composites, dentine bonding, dental amalgam, endodontic materials, casting alloys, investment materials, resin-bonded bridges and ceramo-metallic restorations, all ceramic restorations, denture base and soft lining materials, impression materials, dental implants, orthodontic materials and biomechanics). Three hundred and thirty articles published in 68 titles have been reviewed.
Biomechanical Phenomena↗
An examination of the stress distribution in a soft-lined acrylic resin mandibular complete denture by finite element analysis.
PURPOSE: The aim of this study was to calculate the effect of a soft liner on stress distribution within a mandibular complete denture. Although patients have welcomed soft-lined complete dentures, early fracture is one of the main reasons for failure. To minimize and prevent prosthesis fracture, the understanding of the stress distribution within a prosthesis is important. MATERIALS AND METHODS: A 3-dimensional finite element model of a mandibular complete denture for a severely reduced residual alveolar ridge was constructed. The stress was calculated with linear static finite element analysis. The stress distribution in the soft-lined acrylic resin mandibular complete denture was compared with that of a conventional acrylic resin denture. The resulting stresses were displayed in terms of von Mises equivalent stress and the major principal stresses according to 5 different loading conditions: vertical loads in premolar, molar, and incisor regions; and oblique loads in premolar and molar regions. RESULTS: Oblique loads produced higher levels of stress in the labial notch regions than vertical loads, where tension was the primary mode of stress. Significantly reduced levels of von Mises stress were calculated in soft-liner layers under all loading conditions. Acrylic resin denture base portions, however, exhibited higher levels of von Mises stress in soft-lined complete dentures. CONCLUSION: Three-dimensional finite element analysis gave a realistic explanation of denture fractures and patient response to mandibular complete dentures with and without soft linings. Control of excess lateral occlusal contact might be helpful to reduce the probability of a fracture in soft-lined mandibular complete dentures.
Acrylic Resins↗
The effect of cavity wall taper on fracture resistance of teeth restored with resin composite inlays.
The effect of a range of cavity wall tapers on fracture resistance of teeth restored with an indirect composite restoration (ICR) system has been investigated, using two methods of application of the fracturing force. The fracture load data are similar in both cases, and in neither case does ANOVA suggest a statistically significant difference in performance with cavity taper. However, the mean values are lower for the 6 degrees taper specimens, and linear regression suggests a significant decrease, which is confirmed by the mode data for the bar loading condition, which indicates a greater incidence of severe fractures for the 6 degrees taper. Since technical difficulties were encountered in the construction of inlays for the 2 degrees taper preparations, the most appropriate taper of the range assessed would appear to be 4 degrees, at least when considered with regard to fracture resistance.
Analysis of Variance↗