Dobutamine stress echocardiography in healthy adult male rats

Medical imaging market consists of several billion tests per year worldwide. Out of these, at least one third are cardiovascular procedures. Keeping in mind that each test represents a cost, often a risk, and a diagnostic hypothesis, we can agree that every unnecessary and unjustifiable test is one test too many. Small individual costs, risks, and wastes multiplied by billions of examinations per year represent an important population, society and environmental burden. Unfortunately, the appropriateness of cardiac imaging is extra-ordinarily low and there is little awareness in patients and physicians of differential costs, radiological doses, and long term risks of different imaging modalities. For a resting cardiac imaging test, being the average cost (not charges) of an echocardiogram equal to 1 (as a cost comparator), the cost of a CT is 3.1x, of a SPECT 3.27x, of a Cardiovascular Magnetic Resonance imaging 5.51x, of a PET 14.03x, and of a right and left heart catheterization 19.96x. For stress cardiac imaging, compared with the treadmill exercise test equal to 1 (as a cost comparator), the cost of stress echocardiography is 2.1x and of a stress SPECT scintigraphy is 5.7x. Biohazards and downstream long-term costs linked to radiation-induced oncogenesis should also be considered. The radiation exposure is absent in echo and magnetic resonance, and corresponds to 500 chest x rays for a sestamibi cardiac stress scan and to 1150 chest x rays for a thallium scan. The corresponding extra-risk in a lifetime of fatal cancer is 1 in 2000 exposed patients for a sestamibi stress and 1 in 1000 for a thallium scan. Increased awareness of economic, biologic, and environmental costs of cardiac imaging will hopefully lead to greater appropriateness, wisdom and prudence from both the prescriber and the practitioner. In this way, the sustainability of cardiac imaging will eventually improve.     

Incidence of mussel culture on biogeochemical fluxes at the sediment-water interface

Upward nutrient fluxes at the sediment-water interface were studied in a mussel farming zone (Carteau, Gulf of Fos, France) in order to estimate the impact of organic matter input from biodeposition. Nitrate, nitrite, ammonia, silicate, phosphate and oxygen were measured. Fluxes were estimated by means of polyacrylate benthic chambers placed at sites located under (UM) and outside (OM) the rope hanging structures. Transformation of biodeposited organic matter increases phosphate, silicate and ammonia fluxes. No variation in nitrite fluxes could be detected and only minor differences were observed in nitrate and the oxygen production/consumption equilibrium at the two stations. Phosphate and silicate fluxes, which were always higher at the UM than at the OM site, decreased from spring to winter. Ammonia fluxes were very high under mussel cultures in May and September and lower in November. The fact that ammonia flux was always higher at the UM than at the OM sites might be explained by degradation of mussel biodeposit, as well as by benthic macrafauna excretion. Discrepancies between fluxes of the nutrients studied at the UM and OM sites increased as organic particulate matter in the water column decreased. Variations of oxygen flux followed a different pattern, since they were correlated with presence and abundance of photosynthetic microphytes on the bottom and in the water. Bottom respiration exceeded production of oxygen only in May 1988 at the UM station.As it now stands, biodeposit input into the sediment under mussel ropes does not affect the ecosystem, although the flow of nutrients towards the water column is higher than in other areas.     

Stimulatory effect of synthetic progestins currently used for the treatment of prostate cancer on growth of the androgen-sensitive Shionogi tumor in mice

In order to assess the androgenic activity of synthetic progestins currently used as "antiandrogens" for the treatment of prostate cancer in men, the effect of a series of these compounds has been studied in mice on the growth of the androgen-sensitive Shionogi tumor. Female mice (DD/S strain) were inoculated subcutaneously with 10(6) viable cells and divided into groups who received, respectively, the synthetic "progestins" medroxyprogesterone acetate (MPA), megestrol acetate (MEG), cyproterone acetate (CPA) or chlormadinone acetate (CMA), compared with the non-steroidal antiandrogen Flutamide (Flu), each administered at the twice-daily dose of 250 micrograms. Each synthetic "progestin" exerted a marked stimulatory effect on the growth of the tumor. The most impressive effect on growth was observed with MPA. In fact, in MPA-treated mice, tumor size was 17 times larger than control at 4.92 +/- 0.36 cm2/mouse 21 days after inoculation. CPA, CMA and MEG also stimulated the growth of this androgen-sensitive tumor, the percentages of stimulation of tumor size being 3.1-, 3.2- and 11.0-fold above control, respectively, on day 21, while Flu had no significant stimulatory effect. The present data clearly show that all the above-mentioned progestins have variable levels of stimulatory activity on the growth of the androgen-sensitive Shionogi tumor and indicate that such drugs are unlikely to be recommendable for the treatment of prostate cancer.     

Biosynthesis of hepatic corticosteroid-binding globulin: ontogeny and effect of thyroid hormone.

The present study reports on the ontogeny and the effect of thyroid hormones on liver corticosteroid-binding globulin (CBG) biosynthesis, in relation to plasma CBG binding capacity in the rat. We show that mRNACBG contents were high in liver of 18-day-old fetuses and decreased with age to reach almost undetectable levels by postnatal day 1. Interestingly, at the latter time point plasma CBG concentration remained elevated and disappeared thereafter from the circulation with a half-life of about 3 days. The messenger was localized in parenchymatous cells and not in hematopoietic ones, although the latter constitute the major cell population in fetal liver. It is not until after 10 days of age that mRNACBG and plasma CBG levels increased in concert, with a sex-difference being noticed by postnatal day 30. Treatment of rats with 3,3',5-triiodo-L-thyronine (T3), but not reverse T3 (rT3) (the predominant form present in fetal serum), enhanced CBG biosynthesis. These findings show that liver mRNACBG contents undergo dramatic changes during ontogeny and suggest the existence of a differential regulation of the messenger in fetal and neonatal rats.     

Restriction fragment length polymorphism in the mitochondrial DNA of cloned cattle

The clonal origin of 4 Holstein bulls was determined by hybridization experiments with 2 different minisatellite probes, and all 4 animals showed identical genomic DNA fingerprints, hence confirming monozygosity. Extra-chromosomal differences were observed among these 4 Holstein bulls. Mitochondrial DNA restriction fragment length polymorphisms with restriction endonucleases Avall and Hhal sites were found, and these polymorphisms can be explained by the loss of a single site for each of these 2 enzymes. Since mitochondrial DNA are maternally transmitted, all 4 bulls would produce genetically equivalent spermatozoa and offspring. The combination of embryo cloning and specific cytoplasmic markers would provide an ideal system for the study of maternal cytoplasmic effects on quantitative traits.     

“Animals Like Us”: Identifying with Nonhuman Animals and Support for Nonhuman Animal Rights

While anthropomorphizing nonhuman animals has been shown to increase identification with them and, by extension, concern for their wellbeing, little research has directly tested whether identifying with nonhuman animals is similarly associated with concern for their wellbeing. We tested hypotheses related to this premise across three cross-sectional studies. In study 1 (n = 224), we tested the hypothesis that therians—a group of people who self-identify with nonhuman animals, show greater concern for nonhuman animal rights than non-therian furries—people with a fan-like interest in media featuring anthropomorphized animal characters. In study 2 (n = 206), we further tested this hypothesis using implicit and explicit measures of identification with nonhuman animals to predict behavioral intentions to support nonhuman animal rights. In study 3 (n = 182), we tested the generalizability of our findings in a sample of undergraduate students. Taken together, the studies show that explicit, but not implicit, identification with nonhuman animals predicts greater support for their rights. The implications of these findings for research on anthropomorphism and animal rights activism are discussed, as well as the limitations of these findings and possible avenues for future research.     

Effect of ambient temperatures during oocyte recovery on in vitro production of bovine embryos

Recovery of oocytes from ovaries collected at slaughter was carried out at three ambient temperatures (25 degrees, 30 degrees and 35 degrees C) to assess the effect on subsequent embryonic production in vitro. Oocytes recovered at each temperature were thereafter maintained at temperatures > or =35 degrees C as they were subjected to in vitro maturation, fertilization and culture (IVM/IVF/IVC). The oocytes and resulting embryos within each temperature group were subsequently evaluated for their rates of fertilization, cleavage and development to blastocysts, as well as for the number of cells/blastocyst. The results demonstrate that exposure of cumulus-ocyte-complexes (COCs) to temperatures below 35 degrees C during oocyte recovery is detrimental to optimal embryo production. Although the fertilization and cleavage rates of oocytes recovered at temperatures below 35 degrees C were not significantly lower than that of the controls, the percentage of oocytes recovered at 35 degrees C that developed to the blastocyst stage following fertilization and culture (33.7%) was significantly greater than those from oocytes recovered at either 25 degrees C (22.4%) or 30 degrees C (19.5%). The mean numbers of blastomeres/embryo were significantly lower in embryos derived from oocytes collected at either 25 degrees or 30 degrees compared with those collected at 35 degrees C. The results of this study suggest that exposure of COCs to temperatures below 35 degrees C during oocyte recovery may significantly decrease both the quantity and quality of embryos produced by in vitro methods.     

A parentage evaluation test in North American Elk (Wapiti) using microsatellites of ovine and bovine origin

DNA microsatellites originally detected in sheep and cattle are also detectable in North American elk (Wapiti) using polymerase chain reactions. We have developed a parentage test in elk using eleven microsatellite markers that are highly polymorphic and informative.     

Analysis of the androgenic activity of synthetic "progestins" currently used for the treatment of prostate cancer

In order to assess the androgenic activity of synthetic "progestins" currently used as "antiandrogens" for the treatment of prostate cancer in men, the effect of a series of these compounds has been measured following 14 days of treatment of adult castrated rats on specific and sensitive parameters of androgenic activity, namely ventral prostate weight and prostatic ornithine decarboxylase (ODC) activity. Medroxyprogesterone acetate (MPA) is almost equipotent with 5 alpha-dihydrotestosterone (DHT), a 49% increase in prostatic weight being observed at the low dose of 0.15 mg, twice daily (P less than 0.01). Megestrol acetate (Megace), chlormadinone acetate (CMA) and spironolactone were less potent but caused a 36-59% increase in prostatic weight at the highest dose used, namely 10 mg. At the 5 mg dose, cyproterone acetate (CPA) caused a 75% increase in prostatic weight. The androgenic activity of the compounds is even more clearly illustrated by their marked stimulatory effect on prostatic ornithine decarboxylase (ODC) activity. MPA, at the low dose of 0.15 mg, caused a 20-fold increase (relative to the effect of placebo) in the activity of the enzyme while the same dose of DHT caused a 15-fold stimulation of enzymatic activity. At the 10 mg dose, megestrol acetate, CMA and spironolactone caused 13.1, 11.8 and 8.6-fold stimulations of ODC activity, respectively. Flutamide, on the other hand, had no stimulatory effect on either ventral prostate weight or prostatic ODC activity. In agreement with glucocorticoid activity, MPA, megestrol acetate and CMA caused a marked inhibition (45-64%) of adrenal weight. The present data show that MPA is a highly potent androgen while megestrol acetate, CMA, CPA and spironolactone have lower but significant androgenic activity on all the parameters measured. It should be added that MPA, megestrol acetate and CMA are completely devoid of antiandrogenic activity while spironolactone shows weak antiandrogen action and CPA is a mixed agonist-antagonist. Flutamide, the compound used as reference, is the only compound devoid of any androgenic action and is thus acting as a pure antiandrogen on both ventral prostate weight and prostatic ODC activity. The present data have major implications for the choice of drug to be used for the treatment of androgen-sensitive diseases, especially prostate cancer. As shown by the present data, the synthetic "progestins" so-far available all possess variable levels of androgenic activity and are thus not recommended for the treatment of prostate cancer.