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Biomedical subjects

E Evans

Publications and source records attributed to E Evans.

At least 127 records · Page 7Linked to original sources
PubMed1982

Estrogen-receptor--DNA interaction. Difference between activation by estrogen and antiestrogen.

We have compared the interaction of the cytosol estrogen receptor with calf thymus DNA after its binding to [3H]estradiol or 4-hydroxy[3H]tamoxifen, a high-affinity antiestrogen, in an attempt to find a difference in the nature of these two complexes. The activation of the receptor and its binding to DNA were simultaneously obtained during an 18-h incubation at 0 degree C. The binding of a constant concentration of estrogen receptor to increasing concentrations of adsorbed DNA was examined. Scatchard representation of the data showed that the antiestrogen--receptor complex has a twofold lower affinity for DNA than the estradiol--receptor complex, while the proportion of receptor able to bind DNA was the same whether bound to estradiol or antiestrogen. Similar results were obtained by using soluble DNA and separation of the unbound and DNA-bound receptor on sucrose gradients. These results indicate that the estrogen receptor binds in vitro to non-specific double-stranded DNA with a lower affinity when it has been activated by an antiestrogen than when activated by estradiol.

Animals↗
PubMed1981

Thermoelasticity of large lecithin bilayer vesicles.

Micromechanical experiments on large lecithin bilayer vesicles as a function of temperature have demonstrated an essential feature of bilayer vesicles as closed systems: the bilayer can exist in a tension-free state (within the limits of experimental resolution, i.e., less than 10(-2) dyn/cm). Furthermore, because of the fixed internal volume, there is a critical temperature at which the vesicle becomes a tension-free sphere. Below this temperature, thermoelastic tension builds up in the membrane and the vesicle's internal pressure increases while the surface area remains constant. Above this temperature, the vesicle's surface area increases while the tension and internal pressure are negligible. Without mechanical support, the vesicles fragment into small vesicles because they have insufficient surface rigidity. In the upper temperature range we have measured the increase of surface area with temperature. These data established the thermal area expansivity to be 2.4 X 10(-3)/degrees C. At constant temperature, we used either pipet aspiration with suction pressures up to 10(4) dyn/cm2 or compression against a flat surface with forces up to 10(-2) dyn to produce area dilation of the vesicle surface on the order of 1%. The rate of increase of membrane tension with area dilation was calculated, which established the elastic area compressibility modulus to be 140 dyn/cm. The tension limit that produced lysis was observed to be 3-4 dyn/cm (equivalent to 2-3% area increase). The product of the elastic area compressibility modulus, the thermal area expansivity, and the temperature gives the reversible heat of expansion at constant temperature for the bilayer. This value is 100 ergs/cm2 at 25 degrees C, or approximately 5 kcal/mol of lecithin. Similarly, the product of the thermal area expansivity multiplied by the area compressibility modulus determines the rate of increase of thermoelastic tension with decrease in temperature when the area is held constant, i.e., -0.34 dyn/cm/degrees C.

Elasticity↗
PubMed1981

Affinity of red blood cell membrane for particle surfaces measured by the extent of particle encapsulation.

An experimental technique and a simple analysis are presented that can be used to quantitate the affinity of red blood cell membrane for surfaces of small beads or microsomal particles up to 3 micrometers Diam. The technique is demonstrated with an example of dextran-mediated adhesion of small spherical red cell fragments to normal red blood cells. Cells and particles are positioned for contact by manipulation with glass micropipets. The mechanical equilibrium of the adhesive contact is represented by the variational expression that the decrease in interfacial free energy due to a virtual increase in contact area is balanced by the increase in elastic energy of the membrane due to virtual deformation. The surface affinity is the reduction in free energy per unit area of the interface associated with the formation of adhesive contact. From numerical computations of equilibrium configurations, the surface affinity is derived as a function of the fractional extent of particle encapsulation. The range of surface affinities for which the results are applicable is increased over previous techniques to several times the value of the elastic shear modulus. It is shown that bending rigidity of the membrane has little effect on the analytical results for particles 1--3 micrometers Diam and that results are essentially the same for both cup- and disk-shaped red cells. A simple analytical model is shown to give a good approximation for surface affinity (normalized by the elastic shear modulus) as a function of the fractional extent of particle encapsulation. The model predicts that a particle would be almost completely vacuolized for surface affinities greater than or equal to 10 times the elastic shear modulus. Based on an elastic shear modulus of 6.6 x 10(-3) dyn/cm, the range for the red cell-particle surface affinity as measured by this technique is from approximately 7 x 10(-4) to 7 x 10(-2) erg/cm2. Also, an approximate relation is derived for the level of surface affinity necessary to produce particle vacuolization by a phospholipid bilayer surface which possesses bending rigidity and a fixed tension.

Erythrocyte Membrane↗
PubMed1979

Nutrient intake.

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Body Weight↗
PubMed1978

Trophoblastic disease with coexistent fetus: a sonographic and clinical spectrum.

The sonographic and clinical spectrum of coexistent live fetus and trophoblastic disease is illustrated and discussed. Two patients with a single placenta with trophoblastic change and one patient with two placentas, one normal and one with a hydatidiform mole, are described. The clinical and sonographic abnormalities in all three patients were characteristic. In the two patients with single placenta, the histologic findings were minimal. The clinical and sonographic presentations of coexistent mole and fetus are described and etiology is discussed. The implication of the lack of histologic confirmation of hydatidiform mole suggests a spectrum of findings in trophoblastic disease.

Adult↗
PubMed1978

Contact dermatitis from an ostomy deodorant.

Two patients with contact dermatitis from an ostomy agent are described. Detailed patch testing revealed contact allergic dermatitis to one of the twelve groups of ingredients which largely comprised citronella oil. The problem of dermatitis is discussed in relation to the perfume ingredients of the ostomy agent.

Adult↗
PubMed1978

Effect of altitude on dietary-induced thermogenesis at rest and during light exercise in man.

Measurements of metabolic rate and the thermic response (specific dynamic action) of a 400-kcal liquid meal were made in six subjects at rest and during light exercise. The tests were conducted before (LA1) and after (LA2) a 3-wk sojourn (HA1, HA2, HA3) at 3,650 m on the Monte Rosa. Fasting metabolic rate at rest increased inittally and then fell, as did fasting and fed exercising metabolic rates. The fall in metabolic rates, but not the initial increases, can be ascribed to the change in body weight. Resting thermic responses at altitude were only slightly lower than normal, although peak values were significantly depressed at HA2 (P less than 0.05). The mean exercising thermic response was also significantly lower at HA2 (P less than 0.05) but recovered in HA3 and LA2. In the time taken for thermic responses to decrease and recover there were interindividual differences that were best explained by the previous altitude experience of the subjects. The possibility of a cardiovascular shift during hypoxic exercise causing depression of postprandial metabolism is discussed.

Acclimatization↗
PubMed1978

The effects on normal skin of adhesives from stoma appliances.

The irritancy of 7 adhesive plasters from different ostomy appliances was compared in 30 normal subjects. The adhesives were replaced both daily and weekly over a 21-day period. Using a clinical rating scale, the results slowed that "Stomahesive" had a significantly less irritating effect on the skin than the other plasters, both when removed daily and when removed weekly. The difference between daily and weekly removal reached statistical significance at the end of Weeks 2 and 3, and the results suggest that the nature of the adhesive is more important than the frequency of removal.

Adolescent↗
PubMed1978

Slimming aids.

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Appetite Depressants↗
PubMed1977

A prospective study of gastric and oesophageal carcinoma.

A prospective study of carcinoma of the stomach and oesophagus has been carried out for 2 1/2 years. Seventy-three cases of carcinoma of the stomach, and 16 cases of carcinoma of the oesophagus have been documented. For carcinoma of the stomach, operability rate was 72-6% and resectability rate was 41-9%; overall survival was poor, 20-9% at 12 months. For those who underwent resection, survival at 12 months was 45-5%. No cases of early gastric cancer are among those studied. For carcinoma of the oesophagus, four patients had a resection, and only one has survived for more than 12 months. In the clinical sphere there is a need for early endoscopic as well as radiological investigation of dyspeptic symptoms. In the research field there is a need for studies of chemotherapy in combination with surgery in the initial treatment of gastric carcinoma.

Adult↗