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This paper describes refinements to an instrument for determining the viscoelastic properties of a solid material isothermally, with a single apparatus, over 10 decades of time and frequency. Torque is applied electromagnetically to a specimen fixed at one end. Specimen deformation is determined via a laser beam reflected from the other end upon a split diode detector. Phase resolution is improved by the use of a lock-in amplifier at high frequency and by the use of Lissajous figures to measure phase, allowing the study of materials of moderate loss (0.008≤ tan δ≤0.2) in addition to materials with high loss (tan δ≊1). The rigidity of the instrument is increased by modifications in the specimen support geometry. The range of equivalent frequency for torsion is from less than 10−6 Hz to more than 104 Hz. Digital methods are incorporated in the creep measurements and in the phase measurements.

Typically, if a material possesses the stiffness necessary to be considered a structural material, its damping is low. Conversely, materials with high damping usually do not possess the stiffness necessary to be considered a structural material. Candidate materials for the high stiffness-low damping phase exist in abundance, whereas candidate materials for the moderate stiffness-high damping phase remain to be identified. One possible class of candidate materials for the moderate stiffness-high damping phase is metals at high homologous temperatures. Shear moduli of the specimens at 100 Hz are as follows: 4.1 GPa for indium, 5.7 GPa for lead, 15.7 GPa for tin, and 20.7 GPa for cadmium. Considering the behavior typical of metals, one may think of In and Pb as relatively compliant, while Sn and Cd could be called moderately stiff. The results are of some technological interest in view of the utility of materials with moderately high stiffness and damping. The combination of moderate stiffness and reasonably high loss tangent makes Cd the most promising metal tested with respect to technological applications. The shear modulus of Cd was highest of the metals tested (and very near that of aluminum (G = 27 GPa), which exhibits a loss tangent ofmore » about 0.001 at room temperature). The loss tangent of Cd at audio-frequencies was as high or higher than that of the other metals. In addition, frequency dependence of loss tangent was not as large as that observed in the other metals. No clear pattern relating damping to melting point emerged. An understanding in terms of viscoelastic mechanisms is not forthcoming at this time. Among the metal studied, cadmium exhibited a substantial loss tangent of 0.03 to 0.04 over much of the audio range, combined with a moderate stiffness, G = 20.7 GPa.« less

The piezoelectric ultrasonic composite oscillator technique (PUCOT), operating near 80 kHz, was used to measure the temperature dependence, in the range 23–1000 °C, of dynamic Young's modulus,E, and internal friction,Q−1 in three compositions of low-pressure plasma-sprayed NiCrAlY: Ni-15.6Cr-5.2Al-0.20Y (16-5), Ni-17.2Cr-11.6Al-0.98Y (17−12), and Ni-33Cr-6.2 Al-0.95 Y (33−6). Ambient temperature (23 °C) dynamic Young's moduli for the three alloys were 205.0, 199.8, and 231.0 GPa, respectively. In each case, dE/dT was found to be — 0.06 GPa °C−1 over temperature ranges 23–800, 23–400 and 600–900, and 23–700 °C, respectively. Internal friction was essentially independent of temperature to about 600 °C (700 °C for the 16−5 alloy), at which point a temperature dependence of the formQ−1 =A exp (C/RT) was observed. The constantA for the three alloys was determined to be 62.7, 555, and 2.01 × 106, respectively. The constantC for the three alloys was determined to be 82.8, 111, and 170 kJ/mol−1, respectively. While the physical mechanism is not fully understood, both the pre-exponential constantA and the activation energyC correlate with durability in thermal barrier coatings (TBCs) wherein these alloys are used as bond coats.

Dynamic elastic moduli and mechanical damping were measured with the PUCOT (piezoelectric ultrasonic composite oscillator) technique at room temperature for ceramic-matrix composites (CMCs) of the following compositions: PRD-166 (fibres)/N51A glass (matrix), PRD-166 fibres coated with SnO2/glass, Nextel 480 fibres/glass, Nextel 480 fibres coated with SnO2/glass, and Nextel 480 fibres coated with BN/glass. The fibres were continuous, and the volume fractions varied from 0.24 to 0.43. Some of the mechanical-property measurements correlated with the thickness of one of the coating materials, and with microstructural observations of the misorientation angle of the fibres and normalized fibre length. With increasing volume fractions of fibres, the fraction of broken fibres increased. For the PRD-166/glass and PRD-166/SnO2/glass, a substantial fraction of the fibres were misoriented by angles of up to 15 °. Assessments were made of the measured properties in terms of the rule of mixtures and other theoretical estimations.

Anemia is a common symptom associated with a variety of diseases, disorders, and dietary deficiencies. A review of hemoglobin and hematocrit levels may not be sufficient to determine the severity of the underlying problem. This article gives the reader an enhanced understanding of red cell morphology and reviews some of the common problems associated with anemia.

An analysis combining data from several clinical trials has raised concern that tamoxifen therapy may increase the risk of a subsequent colorectal malignancy. We conducted a nested case-control study to test this hypothesis.A cohort of women diagnosed with breast cancer in 1978-1992 was identified from the western Washington population-based cancer registry. Cases included women who subsequently developed colorectal cancer prior to 1995. Controls were a random sample of the cohort who did not develop a second primary malignancy, matched to cases on age, stage, and year of initial cancer diagnosis. Tamoxifen use was ascertained by medical record abstraction and physician questionnaires.Thirty-six percent of the 122 cases for whom information could be obtained received tamoxifen versus 38% of 194 controls. Relative to non-users and adjusted for receipt of other therapies, there was no increased risk of colorectal cancer associated with tamoxifen use in general (matched odds ratio [mOR] = 0.9, 95% CI 0.6-1.6), longer durations of use (foror =37 months, mOR = 0.8, 95% CI 0.4-1.9), higher cumulative doses of therapy (foror =15 g, mOR = 0.8, 95% CI 0.4-1.6), or use that started at least 5 years prior to the end of study follow-up (mOR = 1.1, 95% CI 0.3-3.7).We found no overall increased risk for colorectal cancer among tamoxifen users.

To examine the incidence of colorectal cancer among Asian residents of the United States according to country of birth.We determined the incidence of colorectal cancer during 1973-1986 among Asian residents in three areas of the western United States (Hawaii, San Francisco/Oakland SMSA, and western Washington state) in relation to country of birth. Numerators for the rates were obtained from the Surveillance, Epidemiology and End Results (SEER) program; a special tabulation of the 1980 US Census was used to estimate the size and composition of the population at risk.US-born Japanese men experienced incidence rates of colorectal cancer twice as high as foreign-born Japanese men and about 60% higher than those of US-born white men. Incidence among US-born Japanese women was about 40% higher than that among Japanese women born in Japan or US-born white women. Foreign-born Chinese men had about the same incidence of colorectal cancer as US-born white men, while US-born Chinese men experienced slightly reduced rates. Chinese women had rates that were generally 30-40% lower than that of US-born white women, regardless of place of birth. Incidence rates for both US-born and foreign-born Filipinos were 20-50% those of US-born whites.These findings suggest that one or more exposures or characteristics that differ between Japanese migrants and their descendants affect the development of colorectal cancer.

The reported mutagenic and carcinogenic effects of some chemicals present in hair dyes have raised concern that hair dye use could increase breast cancer risk. This case-control study evaluated how detailed aspects of hair coloring and hair spray application by reproductive-age women may affect breast cancer risk.Cases were white female residents of three counties of western Washington state 45 years of age or less, who were diagnosed with breast cancer between 1983 and 1990 (n = 844). A sample of similarly aged women residing in the same counties served as controls (n = 960). Information on hair coloring and hair spray use, as well as other exposures, was ascertained during in-person interviews.Breast cancer cases were slightly more likely than controls to report ever having used some type of hair coloring application, including use of rinses, semi-permanent or permanent dyes, as well as bleaching then dyeing or frosting their hair (relative risk [RR] = 1.3, 95% CI = 1.0-1.6, adjusted for age, fullterm pregnancies, family history of breast cancer, and weight). In subgroup analyses, women with exclusive use of just one of these methods of hair coloring application had no elevation in risk (similarly adjusted RR = 1.1, 95% CI = 0.9-1.3), whereas women who used two or more of these methods did have an elevated risk (RR = 1.9, 95% CI = 1.4-2.5). Hair spray use was not related to the risk of breast cancer (ever versus never users: RR = 1.0, 95% CI = 0.8- 1.3).The lack of an association between exclusive use of a single type of hair coloring application and breast cancer risk argues that hair coloring application does not influence breast cancer risk among reproductive-age women. Thus, the results of the present study, as well as negative ones from most (but not all) prior studies, are most consistent with the conclusion that neither hair coloring application nor hair spray application influences breast cancer risk.

We evaluated reproductive risk factors for mucinous and non-mucinous tumors in a population-based case-control study of epithelial ovarian cancer among women ages 20-79 years. We observed a reduction in risk of tumors of both types in association with one or more full-term pregnancies and with use of oral contraceptives for 5 or more years. While findings of some previous studies support the hypothesis that certain aspects of a woman's reproductive life have a different impact on the risk of these subtypes of ovarian epithelial cancer, our data suggest that this issue is not yet resolved.

We examined the incidence of gastric carcinoma in Chinese, Japanese, and Filipino residents of the United States to obtain additional information about the etiology of this disease.The age, race, and birthplace of residents of Hawaii, San Francisco/Oakland, and northwestern Washington who were diagnosed with gastric carcinoma during the period 1973-1986 were obtained from population-based registries, and a special tabulation from the 1980 Census was used to estimate the number of person-years at risk for each category of resident.The incidence of gastric carcinoma in Japanese-Americans was three to six times higher than that of US-born whites, with the highest rates occurring in those persons born in Japan. The rate in US-born Chinese and Chinese men who immigrated to the US was similar to that of whites, whereas the rate in Chinese female migrants was twice that of white American women. Filipino men, regardless of birthplace, were only at 60% the risk of US-born white men, while their female counterparts had a rate very similar to that of US-born white women. The high incidence observed among Japanese-Americans and Chinese female immigrants was largely restricted to sites other than the gastric cardia.Our findings suggest that dietary and other lifestyle differences between the different generations of Japanese-Americans, and between Japanese residents of the US and Japan may provide clues regarding the etiologies of stomach cancers that arise beyond the gastric cardia.

The risks of anal and vulvar cancer are strongly related to cigarette smoking. Smokers are exposed to a substantial quantity of tobacco-specific nitrosamines, including 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). NNK is present in the mucus of the female genital tract. The enzyme debrisoquine 4-hydroxylase (CYP2D6) activates NNK and is present in foreskin kerotinocytes and cervical epithelial cells. A polymorphism for the gene CYP2D6 exists, and persons who possess alleles that are associated with reduced levels of CYP2D6 activity might be expected to be at a relatively lower risk of cancers arising from NNK exposure. To test this hypothesis, we conducted a case-control study to examine the association of CYP2D6 genotype and the incidence of anal and vulvar cancer among cigarette smokers in western Washington State. We tested for 14 alleles (*1-*12, *14, and *17) among cases (25 men and 43 women with anal cancer, 64 women with vulvar cancer) and controls (30 men and 110 women). Contrary to the hypothesis, cases were not less likely than controls to have one (43.9 versus 40.7%) or two (6.8 versus 4.3%) inactivating alleles (*3, *4, *5, *6, *7, *8, *11, or *12). There was a suggestion that, if anything, the combined anal and vulvar cancer risk increased (rather than decreased) with an increasing number of CYP2D6 inactivation alleles: odds ratio = 1.2, 95% confidence interval = 0.7-2.0 with one inactivating allele; odds ratio = 1.8, 95% confidence interval = 0.6-5.4 with two inactivating alleles. These results provide no support for the hypothesis that cigarette smokers who carry the CYP2D6 alleles that result in a low activity phenotype have a decreased risk of anogenital cancer.

We characterize the incidence of adenocarcinoma of the prostate among Chinese, Japanese and Filipino immigrants to the United States and their descendants.Subjects included 1,511 Asian and 16,000 white residents of Hawaii, San Francisco/Oakland and western Washington diagnosed with primary adenocarcinoma of the prostate during 1973 through 1986, and identified from the Surveillance, Epidemiology and End Results program. The size and composition of the population at risk were provided by a special tabulation of the 1980 United States Census.Among Asian-Americans 45 to 69 years old the annual rate per 100,000 for Chinese (24.0), Japanese (29.6) and Filipino (56.8) men born in China, Japan and the Philippines, respectively, was approximately half that of United States born Chinese, Japanese and Filipino men (44.4, 42.2 and 111.3, respectively). For Japanese Americans 70 to 84 years old at diagnosis differences in incidence persisted between those born in Japan (238.0) and the United States (446.4), while for older Chinese Americans incidence rates were nearly the same for those born in China (428.3) and the United States (425.0). In contrast, older Filipino men born in the Philippines had a higher rate (400.1) than their United States born counterparts (264.9) but the latter rate was based on a small number of men. Among United States residents the annual incidence for all generations of Asian-Americans was roughly half that of white men born in the United States (215.9).These results suggest that, irrespective of birthplace or age, Asian-American men retain 1 or more genetic or lifestyle characteristics that make their risk of prostate cancer less than that of white residents of the United States.

To compare selected characteristics of women with and without augmentation mammaplasty to identify differences between these 2 groups of women.White women identified as controls in previously conducted population-based, case-control studies formed the study population for the present cross-sectional analysis (N=3570).Interview information on selected characteristics was compared between women who had received augmentation mammaplasty (n=80) and other women (n=3490) using the prevalence odds ratio (pOR) as the measure of association.Women with breast implants were more likely to drink a greater average number of alcoholic drinks per week (foror =7 drinks vs 0 drinks: pOR=2.9, 95% confidence interval [CI]=1.5-5.5), be younger at first pregnancy (for age20 years vs age 20-29 years: pOR=1.6, 95% CI=1.0-2.7), be younger at first birth (for age20 years vs age 20-29 years: pOR=1.9, 95% C1=1.1-3.3), have a history of terminated pregnancies (foror =1 termination vs 0 terminations: pOR=2.0, 95% CI=1.2-3.4), have ever used oral contraceptives (pOR=2.2, 95% CI=1.0-4.7), have ever used hair dyes (pOR=4.5, 95% CI=1.3-15.4), and have had a greater lifetime number of sexual partners (foror =14 partners vsor =4 partners: pOR=8.9, 95% CI=3.1-25.5) than other women. A history of smoking, lactation, high blood pressure, or thyroid disorders, as well as the number of pregnancies, full-term births, or miscarriages, differed little between women with and without implants. Women with breast augmentation were much less likely to be heavy than other women (foror =74 kg vs56 kg: pOR=0.1, 95% CI=0.03-0.3).The differences we found between women with and without breast implants suggest that consideration and evaluation of confounding factors in future studies will help to clarify some of the long-term health consequences of having breast implants.

The administration of any blood component carries with it the potential of an adverse reaction. Many times, these reactions can be blamed on the biological aspect of the blood. Because the antigen profile of blood varies among individuals, incompatabilities which are known as immune responses, may occur during transfusion. However, even when donor blood is a perfect antegenic match, it is possible for transfusion reactions to occur. These reactions are considered nonimmune, and may be linked to the collection, preparation or administration of the blood. Certain predisposing factors, such as liver or renal failure, patient size, or pre-existing disease may affect a patient's tolerance to donor blood. Nonimmune transfusion reactions involve not only refrigerated blood components, but also commercially prepared products. Below, nine reactions involving a nonimmune response are discussed.

The majority of reactions that occur during blood transfusion are stimulated when the recipient receives antigen from donor blood to which he has developed antibody. The reaction may be immediate or insidious in its onset. Side effects range from mild discomfort to death. The transfusionist needs to be able to distinguish symptoms of a reaction and be prepared to treat them immediately.

The importance of removing leukocytes from the blood before transfusion has been recognized, but the complete value has not yet been totally ascertained. In this article, past accomplishments are reviewed and future uses are outlined.

It has been documented that biogenic amines can stimulate Na+, K+-ATPase from various tissue preparations. However, it is unclear whether or not this stimulation occurs in myocardial tissues. We have evaluated possible catecholamine stimulation of purified Na+, K+- ATPase preparations utilizing a bovine ventricular microsomal preparation. We have studied the dose response of the enzyme to ouabain and digitoxigenin in the presence and absence of propranolol and norepinephrine. Our results indicate that propranolol increases the sensitivity of Na+, K+-ATPase to inhibition by digitalis, and that stimulation of Na+, K+-ATPase in bovine myocardium is not mediated via an adrenergic mechanism. In addition, our results indicate that in myocardial tissue, both stereoisomers of propranolol produce a direct nonspecific membrane effect which can modify Na+, K+-ATPase activity.

The carboxylase activity of ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBPC/O) decreased when an anaerobic culture of Rhodospirillum rubrum was exposed to atmospheric levels of oxygen. From 70 to 80% of the activity was lost within 12 to 24 h. Inactivation was apparent when the enzyme was assayed in situ (in whole cells) and when activity was measured in dialyzed crude extracts. The quantity of enzyme protein, as estimated from sodium dodecyl sulfate-polyacrylamide gels or as quantified immunologically, did not decrease within 24 h of exposure to air. Following extended exposure to aerobic conditions (48 to 72 h), degradation of enzyme occurred. These results indicate that the inactivation of RuBPC/O in R. rubrum may be due to an alteration or modification of the preformed enzyme, followed by eventual degradation of the inactive enzyme. When shifted back to anaerobic conditions (under an argon atmosphere), the RuBPC/O activity increased rapidly. This increase appeared to be due to de novo synthesis of enzyme. The increase in activity was not observed when the culture was maintained in the dark or in the absence of a suitable carbon source. Thus, the oxygen-mediated inactivation of RuBPC/O appeared to be due to some form of irreversible modification. The cloned R. rubrum RuBPC/O gene, expressed in Escherichia coli, yielded functional enzyme that was not affected by oxygen, indicating that inactivation in R. rubrum is mediated by a gene product(s) not found in E. coli.

Separation by gel-filtration chromatography and enzyme assay with H2O2 and an organic hydroperoxide substrate were used to identify selenium (Se)-dependent and non-Se-dependent glutathione peroxidase (GSH-Px) in tissues of calves fed supplemented whole milk diets differing only in their Se content (0.03, 0.23, and 0.53 microgram/g of total solids). Spleen, cardiac muscle, erythrocytes, brain, thymus, adipose tissue, and striated muscles of calves were found to contain only the Se-dependent GSH-Px. Tissues having both enzymes included liver, lungs, adrenal glands, testes, kidney medulla, and kidney cortex. Hepatic tissue contained the highest percentage of non-Se-dependent GSH-Px activity of the calf tissues. For those tissues having Se-dependent and non-Se-dependent GSH-Px activity, the Se-dependent enzyme activity was generally lower for calves fed 0.03 microgram of Se/g of total solids as compared with activity in calves fed larger amounts of Se. The tissue ranking of non-Se-dependent GSH-Px activity, as a percentage of total GSH-Px activity, was not changed by differences in the Se content of the diets fed to the calves.

Ribulose 1,5-bisphosphate (RuBP) carboxylase/oxygenase (RuBPC/O) was inactivated in crude extracts of Rhodospirillum rubrum under atmospheric levels of oxygen; no inactivation occurred under an atmosphere of argon. RuBP carboxylase activity did not decrease in dialyzed extracts, indicating that a dialyzable factor was required for inactivation. The inactivation was inhibited by catalase. Purified RuBPC/O is relatively oxygen stable, as no loss of activity was observed after 4 h under an oxygen atmosphere. The aerobic inactivation catalyzed by endogenous factors in crude extracts was mimicked by using a model system containing purified enzyme, ascorbate, and FeSO4 or FeCl3. Dithiothreitol was found to substitute for ascorbate in the model system. Preincubation of the purified enzyme with RuBP led to enhanced inactivation, whereas Mg2+ and HCO3- significantly protected against inactivation. Unlike the inactivation catalyzed by endogenous factors from extracts of R. rubrum, inactivation in the model system was not inhibited by catalase. It is proposed that ascorbate and iron, in the presence of oxygen, generate a reactive oxygen species which reacts with a residue at the activation site, rendering the enzyme inactive.

The effects of ASI-222 HCl and digoxin on cardiac contractile force, dP/dt, heart rate and mean blood pressure in the dog were evaluated following i.v. administration. Additional studies were performed on isolated, electrically driven rabbit atria with both ASI-222 and digoxin. Our data show that ASI-222 (40 microgram/kg) in non-vagotomized dogs produced a two-fold greater increase in cardiac contractile force and dP/dt than did an equimolar dose of digoxin. ASI-222 caused a peak increase in contractile force and dP/dt 10 min after administration, whereas the peak to digoxin occurred at 30 min. ASI-222 was more effective in non-vagotomized dogs in increasing contractile force and dP/dt than in vagatonized dogs. The inotropic responses to digoxin were not reduced by vagotomy. Studies on isolated electrically driven rabbit atria indicate ASI-222 to be 7-8 times more potent than digoxin in increasing contractile force. These data demonstrate that ASI-222 produces an earlier and greater increase in contractile force and dP/dt than digoxin in equimolar doses.

In anesthetized dogs, structure activity relationships among three cardiotonic compounds were determined by comparing the cardiovascular effects of digotoxigenin (the genin) to digitoxigenin-galactose (a genin-neutral sugar combination) and to digitoxigenin-aminogalactose (ASI-222, a genin-aminosugar combination) using either bolus i.v. injections or constant i.v. infusions. We recorded the effects of these drugs upon cardiac rate, mean blood pressure, left ventricular dP/dt, cardiac index, systolic time intervals, tension-time index, therapeutic index, ventricular excitability and the ventricular refractory period. The addition of an aminosugar group to digitoxigenin or an amine group to galactose-digitoxigenin results in an agent with greater ability to reduce heart rate and to increase cardiac contractility and cardiac index without affecting the tension-time index. Moreover, the addition of an amino group significantly increased the therapeutic index and ventricular refractory period but reduced the toxic index (lethal dose/toxic dose) when compared to the neutral-sugar cardenolide and genin. Our data indicate that such a substitution confers greater potency, prolongs the duration of activity and results in a compound with a greater therapeutic index.

Three groups of 5 calves each were fed (from birth to 12 weeks of age) 3 vitamin-mineral supplemented whole milk diets differing only in their selenium (Se) content (0.03, 0.23, and 0.53 microgram/g of solids). Glutathione peroxidase (GSH-Px) activities and Se concentrations were determined in blood at weekly intervals and in selected tissues after 12 weeks. There were marked differences among the tissues in GSH-Px activity, most notably in the liver, lungs, and adrenal glands, depending on whether H2O2 or cumene hydroperoxide was used to assay the enzyme. Tissues having the highest GSH-Px activity on a weight basis, when assayed with the H2O2 substrate, were erythrocytes and testes. Enzyme activity in thymus, brain, striated muscle, adipose tissue, and blood plasma was lowest among the tissues analyzed. The Se concentration on a fresh tissue-weight basis was highest in kidney cortex, intermediate in kidney medulla, testes, liver, and spleen, and lowest in striated muscle, adipose tissue, and blood plasma. The Se concentration was increased in liver, kidney cortex, spleen, and heart, with increasing increments of dietary Se, whereas differences were not observed in testes and adipose tissue.

In anesthetized dogs, the effects of peripheral cardiac nerves upon cardiotonic steroid-induced contractile force increases were determined by comparing the effects seen with cardiac nerves intact, cardiac denervation, stellate ganglia removed or vagi sectioned. Additionally, structure-activity relationships among four cardiotonic steroids were determined by comparing the contractile force effects of bolus i.v. injections of digitoxigenin (the genin), digitoxigenin-galactose (genin-neutral sugar combination), digitoxigenin-aminogalactose (ASI-222, genin-aminosugar combination) and digoxin. The effects of these drugs upon cardiac rate, mean blood pressure and cardiac contractile force were recorded. Cardiotonic steroids differ in their interaction with cardiac nerves. Digitoxigenin, in addition to its direct contractile force effect on the myocardium, modulates contractile force through adrenergic mechanisms. In contrast, both digoxin and ASI-222 influence their direct inotropic responses through cholinergic mechanisms. Neither adrenergic nor cholinergic mechanisms significantly affect the peak inotropic response of digitoxigenin-galactose. Our data indicate that alterations in both the aglycone and the sugar moieties can significantly alter the contribution of the autonomic nervous system to the contractile force response.

It has been documented that biogenic amines can stimulate Na+, K+-ATPase from various tissue preparations. However, it is unclear whether or not this stimulation occurs in myocardial tissues. We have evaluated possible catecholamine stimulation of purified Na+, K+- ATPase preparations utilizing a bovine ventricular microsomal preparation. We have studied the dose response of the enzyme to ouabain and digitoxigenin in the presence and absence of propranolol and norepinephrine. Our results indicate that propranolol increases the sensitivity of Na+, K+-ATPase to inhibition by digitalis, and that stimulation of Na+, K+-ATPase in bovine myocardium is not mediated via an adrenergic mechanism. In addition, our results indicate that in myocardial tissue, both stereoisomers of propranolol produce a direct nonspecific membrane effect which can modify Na+, K+-ATPase activity.

A newborn infant with a history of umbilical artery catheterization had renal vascular hypertension and congestive heart failure. An abdominal ultrasound examination revealed aortic thrombosis extending from the celiac axis to the aortic bifurcation. Retroperitoneal aortic thrombectomy was performed without difficulty. The infant's hypertension and cardiac failure resolved. The retroperitoneal approach allowed excellent exposure of the aorta and avoided the postoperative gastrointestinal morbidity associated with a transperitoneal approach.

Atrial and junctional arrhythmias may occur after heart transplantation. Often these arrhythmias require intravenous beta-agonists or atrial pacing to improve posttransplant hemodynamic values. We describe a heart transplant patient with a hemodynamically significant junctional rhythm who responded to oral terbutaline with conversion to sinus rhythm.

A full-term pregnancy is associated with reduced endometrial cancer risk; however, whether the effect of additional pregnancies is independent of age at last pregnancy is unknown. The associations between other pregnancy-related factors and endometrial cancer risk are less clear. We pooled individual participant data from 11 cohort and 19 case-control studies participating in the Epidemiology of Endometrial Cancer Consortium (E2C2) including 16 986 women with endometrial cancer and 39 538 control women. We used one- and two-stage meta-analytic approaches to estimate pooled odds ratios (ORs) for the association between exposures and endometrial cancer risk. Ever having a full-term pregnancy was associated with a 41% reduction in risk of endometrial cancer compared to never having a full-term pregnancy (OR = 0.59, 95% confidence interval [CI] 0.56-0.63). The risk reduction appeared the greatest for the first full-term pregnancy (OR = 0.78, 95% CI 0.72-0.84), with a further similar to 15% reduction per pregnancy up to eight pregnancies (OR = 0.20, 95% CI 0.14-0.28) that was independent of age at last full-term pregnancy. Incomplete pregnancy was also associated with decreased endometrial cancer risk (7%-9% reduction per pregnancy). Twin births appeared to have the same effect as singleton pregnancies. Our pooled analysis shows that, while the magnitude of the risk reduction is greater for a full-term pregnancy than an incomplete pregnancy, each additional pregnancy is associated with further reduction in endometrial cancer risk, independent of age at last full-term pregnancy. These results suggest that the very high progesterone level in the last trimester of pregnancy is not the sole explanation for the protective effect of pregnancy.