Comparison of shear strength, fracture patterns, and microleakage among unfilled, filled, and fluoride-releasing sealants.
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Analysis of Variance↗
Biomedical subjects
K Park
Publications and source records attributed to K Park.
Upper gastrointestinal bleeding in an open-access dedicated unit.
The open-access high dependency bleeding unit in Aberdeen admits all patients with suspected gastrointestinal bleeding from a stable adult population of 468,000. The aim is to reduce mortality, morbidity and hospital stay, and create a prospective whole community database. An agreed management protocol is based on prompt resuscitation and early diagnosis. From October 1991 to September 1993 there were 1,602 consecutive admissions with suspected upper or lower gastrointestinal haemorrhage. Bleeding was confirmed in 1,098 of 1,324 patients with presumed upper gastrointestinal haemorrhage, (117 bleeding episodes per 100,000 per year). The overall 30-day mortality was 3.9%, with all deaths attributable to significant concurrent illness. Mortality from peptic ulcer bleeding was 5.3%, with an operation rate of 17% and surgical mortality of 8%. Rapid diagnosis allowed 48% of 523 patients with trivial bleeds to be discharged after a median stay of 24 hours. Centralised expertise and equipment is the essence of the unit's success. The interests of patient care are better served, nursing skills are better developed and teaching opportunities better structured. The major improvement in clinical care, welcomed by hospital colleagues, management and general practitioners, makes the unit an indispensable part of acute medical provision.
Adult↗
Differential effects and transport kinetics of ascorbate derivatives in leukemic cell lines.
In order to investigate the differential effects of ascorbate derivatives on leukemic cell growth, we examined their stabilities and transmembrane transport efficiencies. The growth of HL-60 and U937 cells was dose-dependently inhibited by ascorbic acid and sodium ascorbate, but not by dehydroascorbic acid and magnesium ascorbyl 2-phosphate up to 200 microM. The growth-suppression by ascorbic acid was dependent on its redox state, showing a complete or partial reversion by ascorbate oxidase or FeCl3 addition, respectively. Three different patterns of intracellular ascorbic acid accumulation were observed by HPLC according to the species of ascorbate derivative applied for the incubation. Compared with the reduced form of ascorbic acid, the oxidized forms (dehydroascorbic acid, ascorbic acid plus ascorbate oxidase or FeCl3) were rapidly transported into cells and readily degraded, while magnesium ascorbyl 2-phosphate, a stable derivative of ascorbic acid, slowly elevated the intracellular level of ascorbic acid, reaching a plateau at 24 hours. We also measured the differential kinetics of ascorbic acid levels In culture supernatants following the addition of ascorbate derivatives. Ascorbic acid at 40, 10, or 1 microM was observed 3 hours following treatment with 100 microM of ascorbic acid, ascorbic acid plus FeCl3, or magnesium ascorbyl 2-phosphate, respectively. No ascorbic acid was found in the culture supernatant treated with dehydroascorbic acid. This order of ascorbic acid concentrations in culture supernatant reflects their growth-inhibitory effects. Thus the growth inhibitory effect of ascorbic acid appears to be dependent on its concentration in culture medium rather than its intracellular concentration. In conclusion, the results in this study indicate that the differential effects of ascorbate derivatives appear to be due to the actual concentration differences of the reduced form of ascorbic acid in culture medium following their addition, which is determined by their stability and efficiency of cellular uptake.
Ascorbate Oxidase↗