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Biomedical subjects

D Foster

Publications and source records attributed to D Foster.

At least 109 records · Page 6Linked to original sources
PubMed1981

Acceleration of low-density lipoprotein catabolism in man by total parenteral nutrition.

Since insulin enhances the catabolism of low-density lipoprotein (LDL) by cultured human cells, a potential role of insulin in the regulation of plasma LDL levels in man is suggested. To evaluate the possible effect of insulin on LDL catabolism in vivo, the disappearance rates of injected 125I-labeled autologous LDL were determined before and after endogenous hyperinsulinemia was evoked by total parenteral nutrition. Multicompartmental analysis of plasma decay curves showed a 26% increase in the fractional catabolic rate of LDL after total parenteral nutrition was started. An associated reduction of plasma cholesterol levels resulted from changes in both LDl and high-density lipoprotein. These results suggest that the reduction of LDL levels during total parenteral nutrition is at least partly accounted for by enhanced LDL catabolism. It is postulated that the enhanced LDL catabolism may result from the hyperinsulinemia that accompanies total parenteral nutrition, via insulin stimulation of receptor-mediated LDL catabolism.

Cholesterol↗
PubMed1980

Visible physical impairment and psychological adjustment among pediatric cancer survivors.

Because psychological and psychiatric assessments of childhood cancer survivors have revealed a high rate of psychiatric sequelae, the authors investigated the relationship between the degree of physical unpairment resulting from cancer treatment and the psychosocial adjustment problems of survivors. Ratings of physical impairment were based on the visibility of physical residua as well as the functional limitations they imposed. The results indicated that the psychosocial adjustment of survivors is not significantly related to the severity of physical impairment.

Adaptation, Psychological↗
PubMed1979

Effects of behavioral and pharmacological weight loss programs on nutrient intake.

Behavior therapy is a widely used method for short-term weight control. Formal nutrition counseling is not included in many behavioral programs. To determine what types of diets were self-selected by patients and to see how they compared with individuals participating in a relaxation group with anorectic medication, the eating diaries compiled by participants in such a program were analyzed for 20 different nutrients. In general, pretreatment intakes were nutritious and typical for Americans. Both the behavioral and a relaxation-medication treatment produced weight loss and reduction in calorie intake. Both treatments were associated with the consumption of a fairly nutritious diet not much different from the pretreatment intake except for a reduction in the amount eaten.

Adult↗
PubMed1979

Zinc metabolism in humans after oral and intravenous administration of Zn-69m.

Seventeen patients were studied after separate oral and intravenous administration of 50 muCi Zn-69m to determine if Zn-69m is suitable for studying zinc metabolism in humans and to determine if the route of administration affects kinetics. Patients stayed on a metabolic ward for each study. Activity was measured in the total body, urine, feces, blood, plasma, red blood cells, and by detectors over liver and thigh. Five day urine to fecal ratios were 0.44 (intravenous), 0.018 (oral). Most activity went rapidly to liver, then followed two component exponential loss patterns in both cases. Thigh area doubling time was 5.7 days whether the zinc was given orally or intravenously. Plasma activity decreased to less than 2% of that injected by 24 hr after intravenous administration and decreased from a maximum of 1.2% of that ingested, 3 hr after oral administration to 0.7% by 24 hr. Red blood cell activity increased through the 5-day study period to maximum values of 6.4% of that injected after intravenous administration and 2.4% of that ingested after oral administration. Similar metabolic patterns were observed regardless of whether Zn-69m was administered intravenously or orally, suggesting that these patterns were not affected by the mode of administration for the cases studied.

Administration, Oral↗
PubMed1978

Effects of polyamines on partial reactions of membrane (Na+ + K+)-ATPase.

Spermine and spermidine inhibit the (Na+ + K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) reaction so that the effect increases as the ionic content due to Na+ and K+ in the reaction is reduced. Several other amines inhibit (Na+ + K+)-ATPase to varying degress and methylglyoxal-bis-(guanylhydrazone) was the most potent inhibitor among those tested. The inhibition by polyamines of the ATPase is uncompetitive with respect to Mg2+ and ATP activation of the reaction. Various naturally occurring polyamines and other amines inhibited Na+ activation of (Na+ + K+)-ATPase as well as Na+-dependent phosphoenzyme formation in an apparently competitive manner with respect to Na+. Likewise, K+-activation of (Na+ + K+)-ATPase as well as K+-p-nitrophenyl phosphatase was inhibited in an apparently competitive manner with respect to K+. Both the cation charge and structure (e.g., aliphatic chain length) may contribute to the inhibitory effects of the amines; however, Na+ sites appear to be more sensitive to cation charge than the aliphatic chain length of the amine, whereas the opposite appears to be true for K+ sites. The results do not indicate a specific effect of polyamines on (Na+ + K+)-ATPase or its partial reactions.

4-Nitrophenylphosphatase↗
PubMed1978

The influence of design on the transmission of torque across knee prostheses.

Knee prostheses of eight different designs were tested experimentally to determine the axial torque necessary to rotate the tibial component relative to the femoral component with the prosthesis positioned at or near full extension. The results represent transmitted torque as a function of axial rotation. For six designs, the transmitted torque was 11.3 newton-meters (100 inch-pounds) or greater at 6 degrees of rotation, with an axial load of 1556.8 newtons (350 pounds). These prostheses either had close conformation between femoral and tibial components, or were mechanically linked. In these prostheses, the geometry of the articulating surfaces was the primary determinant of torque. For the other two types, under similar loading conditions the transmitted torques were 2.5 newton-meters (twenty-two inch-pounds) at 6 degrees of rotation. These prostheses were designed to allow greater freedom for rotation, and hence for them the primary determinant of torque was friction between the articulating surfaces. The predictive value of this torque characteristic relative to the incidence of loosening will have to be determined by comparison with clinical experience.

Biomechanical Phenomena↗
PubMed1977

Herbert total knee prosthesis: combined laboratory and clinical assessment.

We tested the Herbert knee prosthesis, which was designed to restore intrinsic stability with limited degrees of freedom for rotation to severely damaged or deformed knees, in a knee simulator. These tests indicated a tendency for the prosthesis to fracture through the medial femoral housing after cycling for the equivalent of one to three years of normal use. In a clinical series of thirty-five knees treated with the prosthesis, there were five failures similar to those produced by laboratory testing. On the basis of this combined study, the Herbert prosthesis appears to have design characteristics that seriously limit its usefulness for long-term knee replacement. Testing in a knee simulator in this case appeared to be a valid predictor of clinical failure.

Biomechanical Phenomena↗
PubMed1976

Na+-dependent phosphorylation of the rat brain (Na+ + K+)-ATPase. Possible non-equivalent activation sites for Na+.

The steady state levels of Na+-dependent phosphoenzyme (E-P) in the (Na+ + K+)-ATPase (EC 3.6.1.3) of rat brain, obtained from a time course study of phosphoenzyme formation at 4 degrees C, were dependent on the concentration of Na+ in the reaction and were maximal in the presence of 64 mM Na+. The plot of phosphoenzyme vs. Na+ concentration gave a curve which on conversion to a double reciprocal plot (1/E-P vs. 1/Na+) gave a line with two breaks, yielding apparently three linear segments. This may be taken to indicate the presence of multiple Na+ sites for the formation of the phosphoenzyme. To test this hypothesis further, the following approach was taken. By making the assumption that the phosphoenzyme may represent bound Na+, it was possible to subject the data to rigorous multiple-site analysis by utilizing steady-state binding equations described by Klotz and Hunston (1971) (Biochemistry 10, 3065-3069), and by Scatchard (1949) (Ann. N.Y. Acad. Sci. 51, 660-672). The analysis of the data by these methods suggests that there may be three non-equivalent Na+ activation sites for the formation of Na+-dependent phosphoenzyme in the (Na+ + K+)-ATPase. The estimated intrinsic association constants (Ka) for activation by Na+ at each of the three sites were 3.4, 0.295, and 0.025 mM-1, respectively.

Adenosine Triphosphatases↗
PubMed1976

Death anxiety in normal children and adolescents.

Instruments devised to measure death anxiety, depression, and manifest anxiety in adults were administered to 75 junior high-school students, 111 senior high-school students, and 38 adults in an effort ot determine the nature of any developmental differences among these groups. A number of significant differences were noted, with the senior high-school students showing greater anxiety, depression, and death anxiety than the other groups. These results are discussed in the context of tasks of adolescent development, and an item analysis of the death anziety questionnaire is presented. Developmental differences in the origin of death anxiety are related to previous studies of death anxiety in adults.

Adolescent↗
PubMed1975

The psychological differentiation of male myopes and nonmyopes.

A comparison of 140 male myopes and 118 male nonmyopes of the entering class of Virginia Military Institute cadets in 1968 demonstrated that there are a number of Strong Vocational Interest Inventory test items which will clearly differentiate myopes from nonmyopes so that it is possible to identify 76% of the individuals falling into either class on the basis of a stepwise discriminant analysis based almost entirely on the Strong Vocational Interest Blank. The items which discriminate in favor of the myopes are essentially those which require academic achievement and individual creative performance, whereas the items which are in favor of the nonmyopes are those which require business and selling skills as well as outdoor types of activities. Further, the myopes are significantly more likely to achieve officer status and win more academic awards than the nonmyopes.

Factor Analysis, Statistical↗