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Biomedical subjects

R E Olson

Publications and source records attributed to R E Olson.

At least 145 records · Page 8Linked to original sources
PubMed1975

Introductory remarks: nutrient, hormone, enzyme interactions.

Homeostasis of the internal environment in mammals is accomplished by a series of feedback mechanisms in a variety of tissues. Homeostasis of cell structure and function during marked changes in the environment is equally important. Both types of homeostasis are dependent on adjustments in endocrine function and changes in enzyme activity. In some instances the intracellular servomechanisms required for homeostasis match in vigor and range the perturbations of the external environment. The regulation of cell metabolism is accomplished by enzymatic, membranous and genetic mechanisms. Most peptide hormones act by combining with a specific receptor in the membrane of sensitive cells, which activates adenyl cyclase to produce cyclic AMP which in turn has selective second messenger functions. Insulin and somatotropin appear to be exceptions and may act via cyclic GMP. Steroid hormones, on the other hand, pass through the cell membrane and combine with a specific receptor protein in the cytoplasm of sensitive cells. This receptor then serves as a transport system for movement of the hormone to the nucleus where it stimulates specific protein synthesis. Nutritional effects on enzyme synthesis are partially direct and partially mediated by the endocrine system. Trace nutrients, especially the fat-soluble vitamins, appear to act directly to modify specific protein syntheses, whereas the bulkier constituents of the diet (carbohydrate, fat protein) exert their effects principally through altered rates of secretion of insulin, glucagon, and the glucocortioids. Protein-calorie malnutrition is the result of a massive assault on homeostatic and adaptive mechanisms designed to conserve nutrients and preserve life. The pathogenesis of marasmus and kwashiorkor is discussed in the light of these adaptive mechanisms.

Animals↗
PubMed1975

Plasma vitamin A, retinol-binding protein and prealbumin concentrations in protein-calorie malnutrition. III. Response to varying dietary treatments.

Plasma vitamin A, retinol-binding protein, and prealbumin concentrations have been studied in 38 northern Thai children with protein-calorie malnutrition (PCM). The 4-week study period consisted of 1 week of stabilization followed by 3 weeks of treatment with formula diets varying in their protein and calorie content. The stabilization period comprised 7 days of initial treatment with fluids, antibiotics, and a gradually increasing intake of protein and calories to a final level of 1 g protein and 100 kcal/kg of body weight. During this period vitamin A, retinol-binding protein and prealbumin levels all showed significant increases compared to admission values, whereas plasma albumin and total protein did not change. During the subsequent 3 weeks, the effects of four different dietary regimens, with daily calorie and protein intakes of 100 or 175 kcal/kg and 1 or 4 g/kg, respectively, were studied. Significant increases in plasma total protein concentration were seen in each of the four test groups, and increases in plasma albumin and prealbumin were also seen in three of the four test groups, and increases in plasma albumin and prealbumin were also seen in three of the four test groups (all but the 175 kcal-1 g protein group). Significant increases in plasma vitamin A levels were not seen in any of the groups. The higher protein regimens (4 g/kg per day) resulted in much greater increases in plasma albumin and total protein levels than did the lower protein regimens. No significant differences in the changes in retinol-binding protein or vitamin A levels were apparent between the test groups. Sixteen additional children with both clinical vitamin A deficiency and protein-calorie malnutrition showed significant increases in total plasma vitamin A concentrations 24 hours after the intramuscular injection of 100,000 IU water-miscible vitamin A palmitate, without a change in plasma retinol-binding protein concentrations. These studies demonstrate that plasma retinol-binding protein and prealbumin concentrations are more rapidly responsive and sensitive to dietary protein intake than is plasma albumin concentration. Furthermore, the absence of a 24-hour rise in plasma retinol-binding protein after parenteral vitamin A provides further evidence that hepatic retinol-binding protein synthesis is impaired in protein-calorie malnutrition.

Blood Proteins↗
PubMed1975

Effects of vitamin K deficiency, warfarin, and inhibitors of protein synthesis upon the plasma levels of vitamin K-dependent clotting factors in the chick.

Two-week-old chicks adequate in vitamin K showed a relative lack of vitamin K-dependent clotting factors when compared with the rat, cow, and man. Chick prothrombin was 50%, IX 8%, and X 6% of respective levels in the rat. Factor VII was not detectable in chick plasma. When 1-day-old chicks were fed a vitamin K-deficient diet, prothrombin levels fell to 5% in 5 days, whereas factors IX and X fell to only 60% of normal. After warfarin administration to normal chicks, prothrombin levels fell to 20% in 6 hours, whereas factors IX and X fell to 60%. When cycloheximide was given to normal chicks, all vitamin K-dependent factors fell at the same relative rate with a half time of 2 hours. Cycloheximide also completely blocked the effect of physiological doses (10 mug) of phylloquinone upon prothrombin synthesis, but only partially blocked the effect of pharmacological doses (2.5 mg) of phylloquinone, suggesting an antagonism between cycloheximide and vitamin K at the ribosomal level. Puromycin was effective in blocking the action of vitamin K at both physiological and pharmacological doses. In the chick, unlike the rat, it appears that (1) cycloheximide is fully effective in blocking the action of physiological doses of vitamin K and (2) the regulatory systems for factors IX and X appear to have a higher affinity for vitamin K and a lower affinity for warfarin than the regulatory system for prothrombin.

Animals↗
PubMed1975

Orthosurgical teamwork.

A series of orthognathic cases illustrates the potential service that is available to young adult and adult patients. These patients have problems that are not within the therapeutic possibilities of orthodontics alone. From a variety of viewpoints--length of time, appliance wear, iatrogenic damage, and patient concern--such procedures may well be preferred and ultimately more successful and stable than alternate conventional orthodontic therapy. Surgical procedures, in combination with orthodontics and prosthetics, have now achieved a level of sophistication that permits correction of almost any type of facial deformity quickly, with minimum pain, and relatively few unfavorable sequelae.12.13.15.

Adolescent↗
PubMed1975

Secretory and serum IgA in children with protein-calorie malnutrition.

The local immune system of children suffering protein-calorie malnutrition (PCM) was investigated by analyzing the amount of immunoglobulins in the nasal washing on admission, repeatedly during 84 days of hospital therapy, and on follow-up, one to two years later. Although measured concentrations of total protein, IgG, and albumin in nasal washings were reduced in children with PCM, only secretory IgA concentrations were significantly lower (P less than .01) in PCM compared to normal children. Mean secretory IgA concentrations were significantly reduced on admission through hospital day 70 and returned to near normal thereafter. At one to two years after hospital discharge, mean concentrations of secretory IgA in nasal secretions were within normal limits. The concentrations of secretory IgA in nasal washings were lowest at a time when serum IgA was markedly elevated; serum IgA concentrations fell to normal values during dietary treatment. The possible role of secretory IgA deficiency in PCM and infection is discussed.

Albumins↗