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Biomedical subjects

R W Phillips

Publications and source records attributed to R W Phillips.

At least 199 records · Page 11Linked to original sources
PubMed1975

Should I be using amalgam or composite restorative materials?

Composite materials were first introduced for use in Class III and Class V cavities. They have now been accepted as the most popular material for the restoration of Class IV cavities and of fractured incisors and their use in Class I and Class II cavities has been advocated. Laboratory investigation of the physical properties of the composite materials suggests that with the exception of hardness, the values recorded are comparable with those for amalgam. In their favour are a lower coefficient of thermal conductivity and superior aesthetics. It has been claimed that a Class II composite restoration can be placed more easily and more rapidly than an amalgam but if comparable contour and adaptation is to be achieved, this claim cannot be substantiated. In contrast to laboratory studies, clinical research has shown that composite materials have some shortcomings. Their colour tends to become more yellow with time and their ability to resist marginal percolation is inferior to that of amalgam. Under clinical conditions their resistance to abrasion is unsatisfactory because of the failure of the bond between the filler particles and the resin. On balance, at the present time amalgam is preferable to composites for Class I and Class II restorations except in cases where aesthetics is the overriding consideration.

Chemical Phenomena↗
PubMed1975

Changes in plasma glucose and lactate concentrations and enzyme activities in the neonatal calf with diarrhea.

Plasma glucose and lactate concentrations and glutamate-pyruvate transaminase (SGPT), glutamate-oxalacetic transaminase (SGOT), alkaline phosphatase (AP), aldolase (ALD), creatine phosphokinase (CPK), and hydroxybutyrate dehydrogenase (HBD) activities were determined before, throughout the incubation period, and during the course of a viral-induced diarrhea in the neonatal calf. Hypoglycemia with a glucose concentration less than 40 mg/dl of plasma was observed in 3 of 10 calves. Plasma lactate concentration increased to 1.84 plus or minus 0.1 times normal in 7 and 6 to 7 times normal in 2 of the animals. The major change in both glucose and lactate concentrations during diarrhea occurred during the 24 hours preceding death. Changes in SGPT, SGOT, or AP activities were not observed, indicating the absence of marked hepatic damage. The ALD, CPK, and HBD activities were increased in 2 calves and the CPK alone was increased in 2 others, indicating cardiac and possibly skeletal muscle damage.

Alanine Transaminase↗
PubMed1975

Plasma corticoid changes during diarrhea in neonatal calves.

An acute, and usually fatal, diarrhea was induced in 11 healthy neonatal dairy calves by oral administration of an enteropathogenic viral inoculum. Fluid and electrolyte therapy was administered to several affected calves. Plasma corticoid values were determined by radio-immunoassay and competitive protein-binding assay, after purification of the plasma by paper chromatography. Statistical comparisons between control and diarrheic groups of calves were made on 5 corresponding experimental days. Plasma aldosterone values of 2 groups of diarrheic calves which died with and without treatment were greater (P less than 0.01) just before death than those of controls and diarrheic calves which recovered. Plasma hydrocortisone and progesterone values in the calves not treated were higher (P less than 0.05) on the day preceding death than in the controls. Plasma corticosterone concentration was increased (P less than 0.05) throughout the disease in both groups of calves that recoverd. These results indicate that the adrenal cortex of the neonatal calf can respond to the severe stressor influences and fluid-electrolyte losses of diarrhea.

Adrenal Cortex Hormones↗