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Biomedical subjects

A Hardy

Publications and source records attributed to A Hardy.

70 records · Page 4Linked to original sources
PubMed1987

Plasma concentrations of ovarian steroids in the freshwater European silver eel (Anguilla anguilla L.): effects of hypophysectomy and transfer to sea water.

Intact and hypophysectomized freshwater (FW) silver eels were transferred to tanks of FW or artificial sea water (SW; salinity = 0.60 osmol/l) which were simultaneously renewed twice a week. Fish were killed 2 months after transfer and plasma was assayed for ovarian steroids. In all fish, 5 alpha-androstane-3 beta,17 beta-diol was present, while 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 alpha,17 beta-diol were undetectable. In intact FW eels, plasma levels of testosterone, 5 alpha-androstane-3 beta,17 beta-diol and oestradiol-17 beta were approximately 0.15 nmol/l. In intact SW eels, no change in plasma levels of testosterone and 5 alpha-androstane-3 beta,17 beta-diol was found, whereas the concentration of oestradiol-17 beta was increased significantly (P less than 0.01), indicating stimulation of aromatase activity. In hypophysectomized compared with intact FW fish, plasma levels of testosterone and 5 alpha-androstane-3 beta,17 beta-diol were decreased (P less than 0.05) and there was a slight but significant (P less than 0.01) augmentation of the plasma concentration of oestradiol-17 beta which may have involved the removal of pituitary-dependent inhibition of aromatase activity, possibly by 5 alpha-reduced compounds. In hypophysectomized compared with intact SW fish, plasma levels of testosterone, 5 alpha-androstane-3 beta,17 beta-diol and oestradiol-17 beta were decreased (P less than 0.05); in the case of oestradiol-17 beta, this may have reflected the diminished ovarian synthesis of testosterone, its precursor. The plasma level of oestradiol-17 beta was, however, higher in SW than in FW fish, even in hypophysectomized eels. This suggests that extra-pituitary mechanisms mediate, at least partly, the effects of transfer to SW on aromatase activity.

Androgens↗
PubMed1986

Ovarian metabolic pathways of steroid biosynthesis in the European eel (Anguilla anguilla L.) at the silver stage.

Ovarian slices of the European eel at the silver stage were incubated with 4 tritiated precursors (pregnenolone, progesterone, androstenedione, testosterone) in the presence or not of an inhibitor of 11 beta-hydroxylase activity, metopirone. Ether extracts were submitted to a gradient elution chromatography on celite columns. Isolated peaks were identified by isopolarity on TLC, microchemical reactions and recrystallization to constant specific activity. Interpretation of the results shows that the ovary of the European eel contains the following enzymes: a 3 beta-hydroxysteroid dehydrogenase, 5----4-ene-isomerase complex, a 17 alpha-hydroxylase, a C21-C19 desmolase, a 17 beta-hydroxysteroid oxidoreductase, a 5 alpha-reductase, a 3 beta-hydroxysteroid oxidoreductase and an aromatase complex. Metopirone effect indicates the presence of an 11 beta-hydroxylase activity. At this stage, 5 beta-reductase, 20 beta-reductase and 21-hydroxylase activities are not detected in the ovary. Water-soluble steroids were formed from all the precursors used. It appears that the ovarian biosynthesis is orientated towards the production of 5 alpha-reduced compounds and that this might limit the production of 17 beta-estradiol by lowering the amount of disposable endogenous precursors.

Aging↗
PubMed1986

Radiation environments and absorbed dose estimations on manned space missions.

In order to make an assessment of radiation risk during manned missions in space, it is necessary first to have as accurate an estimation as possible of the radiation environment within the spacecraft to which the astronauts will be exposed. Then, with this knowledge and the inclusion of body self-shielding, estimations can be made of absorbed doses for various body organs (skin, eye, blood-forming organs, etc.). A review is presented of our present knowledge of the radiation environments and absorbed doses expected for several space mission scenarios selected for our development of the new radiation protection guidelines. The scenarios selected are a 90-day mission at an altitude (450 km) and orbital inclinations (28.5 degrees, 57 degrees and 90 degrees) appropriate for NASA's Space Station, a 15-day sortie to geosynchronous orbit and a 90-day lunar mission. All scenarios chosen yielded dose equivalents between five and ten rem to the blood forming organs if no large solar particle event were encountered. Such particle events could add considerable exposure particularly to the skin and eye for all scenarios except the one at 28.5 degrees orbital inclination.

Cosmic Radiation↗
PubMed1985

[Plasma levels, metabolic clearance rates, and rates of secretion of testosterone and estradiol-l7 beta in the silver eel (Anguilla anguilla L.)].

Testosterone (T) and 17 beta-estradiol (E2) plasma levels and metabolic clearance rates (MCR) were measured to investigate their ovarian production in immature silver eel. The dynamics of T and E2 metabolism were studied in catheterized eels using single injections of 0.2 to 0.5 microCi 3H-labeled steroid. The distribution volumes, biological half-life and MCR of nonconjugated tracers were calculated on the basis of a two-compartment model. At the end of the experiments, radioactivity was measured in different organs and tissues to localize the site of T and E2 catabolism. The volume of the inner compartment was 3.4% for T and E2. The outer compartment was larger for T (6.4%) than that for E2 (4.3%). The biological half-life was three to four times shorter for T (14.5 hr) than that for E2 (48.5 hr). The MCR for T (1.71 ml/kg body wt/hr) was higher than for E2 (0.51 ml/kg body wt/hr). Plasma levels were determined, using radioimmunoassay, on samples taken before injections of radiolabeled steroid. Free or protein-bound hormone levels were 0.12 and 0.31 ng/ml for T and E2, respectively. Conjugated T and E2 levels were, respectively, 0.13 and 0.23 ng/ml. Production rates were determined as the product of the MCR and the plasma concentration of the nonconjugated hormone. No significant differences were observed between the production rates of T and E2 (0.24 ng/kg body wt/hr). The liver was the principal site of metabolism for both hormones, which were excreted via the enterohepatic route. E2 injection gave rise to no metabolite in the plasma whereas after T injection a metabolite was produced, the concentration of which increased as a function of time. Its chromatographic properties were different from that of E2 or androstenedione, suggesting that no significant peripheral aromatization or 17-oxidoreduction occurs in the immature silver eel.

Animals↗
PubMed1984

[Bronchial asthma associated with anguilluliasis].

The authors present a case of a 46 year old man without any past history of allergy, who presented with severe asthma of recent onset associated with moderate eosinophilia, a raised total IgE level and a Larva currens type of dermatitis. Serology and stool culture revealed anguillulosis. The negative DLAC and the fact that the asthma disappeared after treatment of the parasitic infestation suggest that it was related to the anguillulosis.

Asthma↗
PubMed1983

Early infections in kidney, heart, and liver transplant recipients on cyclosporine.

Eighty-one renal, seventeen heart, and twenty-four liver transplant patients were followed for infection. Seventeen renal patients received azathioprine (Aza) and prednisone as part of a randomized trial of immunosuppression with 21 cyclosporine-and-prednisone-treated renal transplant patients. All others received cyclosporine and prednisone. The randomized Aza patients had more overall infections (P less than 0.05) and more nonviral infections (P less than 0.02) than the randomized cyclosporine patients. Heart and liver patients had more infections than cyclosporine renal patients but fewer infections than the Aza renal patients. There were no infectious deaths in renal transplant patients on cyclosporine or Aza, but infection played a major role in 3 out of 6 cardiac transplant deaths and in 8 out of 9 liver transplant deaths. Renal patients on cyclosporine had the fewest bacteremias. Analysis of site of infection showed a preponderance of abdominal infections in liver patients, intrathoracic infections in heart patients, and urinary tract infections in renal patients. Pulmonary infections were less common in cyclosporine-treated renal patients than in Aza-treated patients (P less than 0.05). Aza patients had significantly more staphylococcal infections than all other transplant groups (P less than 0.005), and systemic fungal infections occurred only in the liver transplant group. Cytomegalovirus (CMV) shedding or serological rises in antibody titer, or both occurred in 78% of cyclosporine patients and 76% of Aza patients. Of the cyclosporine patients, 15% had symptoms related to CMV infection. Serological evidence for Epstein Barr Virus infection was found in 20% of 65 cyclosporine patients studied. Three had associated symptoms, and one developed a lymphoma.

Adult↗
PubMed1975

[Telethermography of the breast].

Thermography has become indispensable for diagnosis of malignant and benign breast diseases. Technique and interpretation of the thermogram are described. The place of Thermography amongst the various breast investigations is discussed.

Breast Diseases↗
PubMedDate not supplied

Exotic myiasis with Lund's fly (Cordylobia rodhaini).

After a four-week holiday in East Africa, a woman was diagnosed with furuncular myiasis: a third-instar larva of the fly Cordylobia rodhaini (Lund's fly) was found in a skin lesion. This is the first report of exotic myiasis and importation of this species of fly into Australia, and reflects the increasing risk of introducing exotic flies of public health and veterinary importance to Australia.

Africa, Eastern↗
PubMedDate not supplied

[High risk factors of breast cancer].

The authors analyse the various high-risk factors for breast cancer which have been described by many authors and their relative importance and intricacies. Some of these factors are concerned with the age of the patient, some with the time the periods started, some with the time the menopause occured and whether this was natural or artificial.

Adolescent↗
PubMedDate not supplied

Neomycin inhibition of intestinal putrescine uptake.

Enhanced intestinal polyamine uptake was confirmed in tumor-bearing rats. Intestinal brush border membrane from rats bearing a Mat Lylu prostatic adenocarcinoma exhibited 46% increase in 14C putrescine uptake. After oral ingestion of 14C putrescine, radioactivity was recovered in the tumor (about 2% of total amount ingested) and was enhanced in liver and in blood. Radioactivity in tumor-bearing rat red blood cells (RBC) was two-fold higher than in healthy control rats indicating that polyamines originating in food can contribute to the enhancement of RBC polyamine levels observed after tumor development. Neomycin-induced inhibition of intestinal putrescine absorption was observed both in vitro and in vivo. In intestinal brush border membrane 500 microM neomycin inhibited putrescine uptake by 30-35%. In vivo, a single dose of neomycin given per os modified final 14C radioactivity distribution: a) The final accumulation of radioactivity in the tumor was reduced by 50%. b) Neomycin treatment lowered the high levels of radioactivity in the blood of cancerous animals. This reduction was correlated with a significant reduction of RBC polyamine levels. c) Radioactivity accumulated in the colon after neomycin treatment in both healthy and cancerous rats. The role of neomycin as an intestinal antibiotic and the presently described effect of this drug on intestinal polyamine uptake emphasize the importance of neomycin in polyamine deprivation treatments.

Adenocarcinoma↗