Plasma variation of atrial natriuretic peptide in central hypervolemia (diurnal or nocturnal) induced by antiorthostatic decubitus at -6 degrees

Plasma levels of ANP were measured during a 4 hrs head-down tilt at -6 degrees in 5 healthy male volunteers (aged 20-22 M.2). The experiments took place from 8 to 14 hrs, (day), and from 22 to 7 hrs (night). The control period was 1 hr. in a seated position (8 to 9 hrs. for day and 22 to 23 hrs. for night). Blood samples were collected at 9 and 23 hrs. and every 20 min. during the first hours, and every hours thereafter. Electroencephalograms were continuously recorded during night. Our results showed a similar increase in ANP during both experimental conditions. During night there was no correlations between ANP and sleep stages. Finally the differences observed in renal responsiveness to central volume expansion during day or night could not be explained by a difference in renin, aldosterone, vasopressin (previously demonstrated in several studies) or ANP secretion.     

Variation in plasma lipids during the reproductive cycle of male and female desert tortoises,Gopherus agassizii

Plasma triacylglycerol, phospholipid, cholesterol, cholesterol esters, fatty acids, and total lipids were measured in 30 female and 20 male desert tortoises (Gopherus agassizii) during the annual reproductive cycle in the eastern Mojave desert, Nevada. Blood samples were collected at monthly intervals from April to October. All lipid fractions, with the exception of free fatty acids, were significantly higher in female plasma than in male plasma in all months of the year. In contrast, free fatty acids were higher in male plasma than in female plasma in all months. The seasonal pattern in estradiol secretion mirrored that of triacylglycerol, phospholipid, cholesterol, and total lipid, all of which showed a significant correlation with the hormone. Estradiol and the vitellogenesis-associated lipids were all significantly higher in August, September, October, and April than in June. The seasonal variation in cholesterol ester levels in females did not correlate with any of the reproductive events and did not appear to be involved in yolk precursor formation. Total lipid in males showed a negative correlation with testosterone and spermatogenesis. Individual fatty acids in the June and August samples (at the highest and lowest estradiol levels) were compared in male and female plasma. The percent of C18:3n3, C18:2n6, C18:1n9, C20:5n3, and C22:5 were significantly higher in the June female plasma sample than in the August sample. Docosahexanoic (C22:6n3) acid was barely detectable in female plasma in either month.     

Plasma aldosterone and renal function in runners during a 20-day road race

To evaluate the effects that repeated long-distance running has on plasma aldosterone concentration and urinary excretion of solutes, fifteen male runners were studied during a 20-day, 500-km road race. Venous blood samples were taken on day 1 prior to running, on day 11 after 10 days of running, on day 13 after a 70-h rest, and on day 18 after an additional five days of running. Overnight urine samples were obtained on day 10 before and after running and on days 11, 12, and 13 during the 70-h rest period. Plasma sodium concentrations on days 13 and 18 and plasma potassium concentrations on days 11 and 13 were decreased (P less than 0.05). Plasma aldosterone levels were increased on days 11 and 18 after running and returned to pre-race levels on day 13 after 70 h of rest. Plasma cortisol concentrations were not altered. The urinary excretion rates of sodium were elevated and of aldosterone were decreased after 70 h of rest. Increase in excretion rate of urinary sodium correlated with decrease in concentration of plasma aldosterone. These findings show that plasma aldosterone levels are chronically elevated with repeated long-distance running, resulting in a decrease in urinary excretion rate of sodium.     

Cardiorenal-endocrine responses to head-out immersion at night

Cardiorenal-endocrine responses to 3-h head-out immersion (HOI) (water temperature = 34.5 +/- 0.5 degrees C) were studied during day (0900-1400 h) and night (2300-0400 h) in six hydropenic male human subjects. Although HOI induced a reversible increase in urine flow in all subjects, the response was faster and greater in magnitude during the day compared with night (P less than 0.05). Na excretion and osmolal clearance (Cosm) also followed the identical response pattern as urine flow, and in fact, the HOI-induced diuresis was entirely accounted for by the increased Cosm. Endogenous creatinine clearance was not different between the day and the night and remained unchanged during HOI. Both plasma renin activity and aldosterone concentration and urinary aldosterone excretion were nearly twofold greater during the day compared with night before HOI but decreased to the same level during HOI in both daytime and the nighttime series (P less than 0.05). There was no correlation between the Na excretion rate and renin-aldosterone levels either before or during HOI. Plasma antidiuretic hormone (ADH) level was comparable between day and night before HOI and decreased to a similar level during HOI in both daytime and nighttime series (P less than 0.05 for nighttime HOI). Cardiac output increased from 3.3 1/min before HOI to 5-6 1/min during HOI without showing any significant circadian difference. Hematocrit, hemoglobin, and plasma concentrations remained unchanged under all conditions. It is concluded that the renal response to HOI is subject to nocturnal inhibition, which cannot be attributed to circadian differences in the degree of HOI-induced central blood pooling, renin-aldosterone, or ADH responses.     

Effect of sex and age on serum aldosterone and thyroid hormones in the laboratory rat

Serum levels of aldosterone, tri-iodo thyronine (T3) and thyroxine (T4) were measured in male and female rats aged 3 months, 12 months, and 18 months. Female rats were found to have higher aldosterone and T3 levels, and lower T4 level than the male. No age-related change was observed in serum aldosterone in either sex. In contrast, serum T4 were found to decrease with age in both sexes while serum T3 showed an age-associated diminution in the male only. Serum testosterone was also measured in the male rats and was found to decline with age.     

Aromatase inhibition by R 76713: experimental and clinical pharmacology

R 76713 is a new non-steroidal compound which inhibits aromatase in vitro and in vivo with a potency of at least 1000-fold that of aminoglutethimide. In male cynomolgus monkeys peripheral conversion of labeled androstenedione to estrone is decreased by 85%, 4-5 h after a single intravenous dose of 0.003 mg/kg of R 76713, without altering steroid metabolic clearance rates. In rats fed a sodium-depleted diet for 3 weeks, plasma levels of aldosterone and plasma renin activity remain unchanged 2 h after a single oral dose of up to 20 mg/kg of R 76713. This confirms previous data on the selectivity of R 76713 for aromatase inhibition as compared to inhibition of other enzymes involved in steroid biosynthesis. In male volunteers, a single oral dose of 5 or 10 mg of R 76713 lowers median plasma estradiol levels from 70 pM to the detection limit of the assay (30 pM) 4 and 8 h after intake, whereas no important changes are detected after placebo administration. In 15 premenopausal female volunteers receiving a single oral dose of 20 mg of R 76713, mean plasma estradiol levels decrease from 415 pM (before) to 179, 149 and 185 pM respectively 4, 8 and 24 h after intake whereas they remain above 380 pM after placebo (n = 7).     

Life history of hawthorn spider mite Amphitetranychus viennensis (Acarina: Tetranychidae) on various apple cultivars and at different temperatures

Development duration and reproduction rate of hawthorn spider mite Amphitetranychus viennensis (Zacher) were carried out on five different apple cultivars (Amasya (local cultivar), Golden Delicious, Granny Smith, Starking Delicious and Starkrimson Delicious) at 25 degrees C, 65 +/- 10% RH and 16:8 L:D. In addition, the same parameters were determined on Golden Delicious leaves at three constant temperatures (20, 30 and 35 degrees C, 65 +/- 10% RH and 16:8 L:D) in the laboratory. A. viennensis showed a better performance on Golden Delicious than on the other apple cultivars. This was mainly due to a short development time (10.7 days), high daily egg production (5.2 eggs/female/day) and early reproduction peak. The highest intrinsic rate of natural increase (rm) was determined on the variety Golden Delicious (rm = 0.247/day), while the lowest one was observed on the variety Starking Delicious (rm = 0.215/day). The developmental periods of A. viennensis varied from 7.4 to 18.8 days at 35 and 20 degrees C for females, while it varied from 7.9 to 17.2 days at 30 and 20 degrees C for males. The development threshold of the eggs and pre-adult stages were 9.72 and 9.07 degrees C, total effective temperature was 72.99 and 185.18 degree-days, respectively. The mean generation time (To) of the population ranged from 16.13 days at 30 degrees C to 29.15 days at 20 degrees C. The net reproductive rate (R0) increased from 54.33 female/female at 20 degrees C to 78.34 female/female at 25 degrees C, and decreased to 75.71 female/female at 30 degrees C. The highest intrinsic rate of increase (rm) was reached at 30 C (rm = 0.268/day), the lowest one at 20 degrees C (rm = 0.136/day).     

Freeze-dried plasma proteins are stable at room temperature for at least 1 year

Thirty human EDTA plasma samples from male and female subjects ranging in age from 24 to 74 years were collected on ice, processed ice cold and stored frozen at ?80 °C, in liquid nitrogen (LN2), or freeze dried and stored at room temperature in a desiccator (FDRT) or freeze dried and stored at ?20 °C for 1 year (FD-20). In a separate experiment, EDTA plasma samples were collected onto ice, processed ice cold and maintained on ice ± protease inhibitors versus incubated at room temperature for up to 96 h. Random and independent sampling by liquid chromatography and tandem mass spectrometry (LC–ESI–MS/MS), as correlated by the MASCOT, OMSSA, X!TANDEM and SEQUEST algorithms, showed that tryptic peptides from complement component 4B (C4B) were rapidly released in plasma at room temperature. Random sampling by LC–ESI–MS/MS showed that peptides from C4B were undetectable on ice, but peptides were cleaved from the mature C4B protein including NGFKSHALQLNNR within as little as 1 h at room temperature. The frequency and intensity of precursors within ± 3 m/z of the C4B peptide NGFKSHALQLNNR was confirmed by automated targeted analysis where the precursors from MS/MS spectra that correlated to the target sequence were analyzed in SQL/R. The C4B preproprotein was processed at the N terminus to release the mature chain that was cleaved on the carboxyl side of the isoprene C2 domain within a polar C terminal sequence of the mature C4B protein, to reveal the thioester reaction site, consistent with LC–ESI–MS/MS and Western blot. Random sampling showed that proteolytic peptides from complement component C4B were rarely observed with long term storage at ? 80 °C in a freezer or in liquid nitrogen (LN2), freeze drying with storage at ? 20 °C (FD-20 °C) or freeze drying and storage at room temperature (FDRT). Plasma samples maintained at room temperature (RT) showed at least 10-fold to 100-fold greater frequency of peptide correlation to C4B and measured peptide intensity compared to samples on ice for up to 72 h or stored at ? 80 °C, LN2, FDRT or FD-20 °C for up to a year.     

Prolactin in the marsupial Macropus eugenii, during the estrous cycle, pregnancy and lactation

An heterologous double antibody radioimmunoassay (RIA) using a guinea-pig antiserum (33-9) raised against human prolactin and 125I-ovine prolactin has been developed to measure prolactin (Prl) in plasma and pituitary preparations of marsupials. In this system, purified tammar and kangaroo Prl preparations showed parallel dose-response curves as did serial dilutions of crude pituitary homogenates of tammar, possum and eastern grey kangaroo. Serial dilutions of plasma from ovariectomized and lactating female and castrate male tammars showed immunoreactivity, and plasma Prl levels increased after injection of TRH. The assay has been used to monitor changes in plasma Prl in female tammars in various reproductive states. Plasma Prl remained at basal concentrations of 20 to 30 ng/ml throughout the estrous cycle, at estrus and during pregnancy. However, just prior to parturition, there was a 2- to 3-fold increase in Prl concentrations which declined to basal levels after birth. During early lactation, Prl levels were low but increased to maximum concentration in the second half of lactation.     

Clinical and cell kinetic data on the combination of cytosine arabinoside with daunorubicin, isosfamide, thioguanine, and vincristine for remission induction and maintenance in patients with acute myelocytic leukaemia (author's transl)]

31 adult patients (study A) with acute myelocytic leukaemia were treated for remission induction with cytosine arabinoside (ARA-C, 100 mg/m2/day) by a 7 (5) day continuous infusion. 3 (2) doses of daunorubicin (DNR, 45 mg/m2 i.v.) were added at daily intervals. For maintenance 5 day ARA-C was given monthly in sequential combination with DNR, thioguanine (TG), or ifosfamide (IFOS). 16 (52%) patients achieved complete remission (C.R.) after 1.8 (1-3) courses and 6.7 (3-10) weeks from treatment start. The median survival for responders and non-responders was 11.5 months, early death rate within 6 weeks was 3 (10%). Median remission duration was 13.5 months. Among 11 patients surving for 7-22 months 7 patients are in first remission for 5.5-20.5 months. DNR, IFOS and TG were given before the 3rd day of ARA-C infusion. In a previous group of 34 leukaemic patients and in 44 therapy courses DNA histograms of bone marrow cells using pulse cytophotometry showed marked accumulation in S-phase for 75% of courses. Also (G2 + M)-cells in the DNA distribution and thymidine pulse labelling indices were markedly increased in most cases, whereas thymidine uptake by scintillation counter was diminished and mitotic indices had not changed significantly. In now 15 patients (study B) the induction regimen was intensified by adding vincristine (VCR, 2 mg i.v.) and 3 doses of IFOS (600 mg/m2 i.v.). Preliminary results are 50% C.R. after 1,7 (1-2) courses and 6.8 (5-10) weeks from initiation of therapy. 2 patients died in the first 6 weeks.     

Early renal structure alteration in rat offspring from dams fed low protein diet

To investigate the early renal alterations due to severe maternal protein restriction (MPR) Wistar dams received 23% (normal protein, NP) or 5% (low protein, LP) chow during gestation and lactation periods. In NP offspring at birth, the cortex-to-medulla (C/M) ratio was 35% greater in female than in male offspring and the mature/immature glomeruli ratio was lower in both sexes of LP offspring than in the matched NP ones (by 20%). At birth and at weaning the kidney of the LP offspring showed fewer glomeruli (40% less) than the age-matched NP offspring. The NP female offspring had almost 20% fewer glomeruli than the matched male offspring. At weaning, the number of glomeruli was positively correlated with BM at birth (R=0.86; P<0.001). The effects of gender and maternal protein restriction, both individually and overall, based on biometrical and stereological parameters were: day 1, MPR largely responsible for the majority of alterations observed in LP groups, however gender influenced C/M ratio; day 21, MPR and gender interacted and modified the number of glomeruli per kidney. The early adverse of MPR effect on renal development is disproportionate between mature and immature glomeruli at birth leading to fewer glomeruli at weaning. This supports epidemiological data in humans underlying why fetuses with low birth weight carry an increased risk of mortality from chronic diseases in adulthood, including hypertension.     

Effects of long-term enalapril and losartan therapy of hypertension on cardiovascular aldosterone.

BACKGROUND: Plasma aldosterone escape is found during long-term angiotensin-converting enzyme inhibitor therapy. Evidence for aldosterone production in cardiovascular tissues raised the question of whether or not aldosterone escape occurs in these tissues. METHOD: Spontaneously hypertensive rats were treated with enalapril (20 mg/kg/day) and losartan (50 mg/kg/day) for 20 weeks; untreated spontaneously hypertensive and Wistar rats were used as positive and normal controls, respectively. Ex vivo mesenteric artery and heart perfusion, high-performance liquid chromatography, and radioimmunoassay for aldosterone were performed. RESULTS: The results showed that enalapril failed to significantly inhibit aldosterone production in mesenteric artery, myocardium and plasma. Losartan significantly inhibited aldosterone production to that of Wistar rats in the mesenteric artery, myocardium and plasma. CONCLUSION: This study provides the first evidence that long-term angiotensin-converting enzyme inhibition therapy induces aldosterone escape in hypertensive cardiovascular tissues, and angiotensin II subtype 1 receptor antagonist does not induce aldosterone escape in mesenteric artery, myocardium and plasma of spontaneously hypertensive rats.     

Life history of the mealybug, Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), at constant temperatures

Important life history parameters of the mealybug, Maconellicoccus hirsutus (Green), were characterized on hibiscus (Hibiscus rosa-sinensis L.) cuttings at six constant temperatures between 15 and 35 degrees C. The development of M. hirsutus was the fastest at 27 degrees C, where the mealybugs completed development in approximately 29 d. The lower (T(min)) and upper (T(max)) developmental thresholds and the optimal developmental temperature (T(opt)) for the development of female mealybugs were estimated as 14.5, 35, and 29 degrees C, respectively. The thermal constant (K), which is the number of temperature-day or degree-day units required for development, of the females was 347 DD. The original distribution range prediction (based on T(min) = 17.5 degrees C and K = 300 DD) indicated that M. hirsutus could complete at least one generation in all of the continental United States. However, results of this study suggested that the distribution range of M. hirsutus may expand northward because of the lower T(min), and the predicted number of generations in a year may be lower because of the higher K required to complete each generation. The average cumulative survival rate of M. hirsutus at 25 and 27 degrees C was 72%, which was significantly higher than 51 and 62% at 20 and 30 degrees C, respectively. M. hirsutus reproduced sexually, with each mated female producing 260-300 eggs between 20 and 27 degrees C but only approximately 100 eggs at 30 degrees C. Female longevity was reduced from 28 d at 20 degrees C to 19-21 d at 25-30 degrees C. At 27 degrees C, the net reproductive rate (R(o)) was estimated at 165 female symbol/female symbol, the intrinsic rate of population increase (r(m)) was 0.119 (female symbol/female symbol/d), the generation time (T(G)) was 43 d, and the doubling time (DT) was 5.8 d. The life table statistics suggested that the currently released biological control agents, which have higher r(m) than M. hirsutus, will be able to complete more generations than the mealybug within the tested temperature range; thus, they are effective against M. hirsutus.     

Ontogenic corticosteroidogenesis of the domestic fowl: response of isolated adrenocortical cells

Ontogenic adrenocortical function of the domestic was investigated using adrenocortical cells isolated from embryonic chicks (18, 19, 20, and 21 days old) and male and female posthatch birds (1 day, 1 week, and 3 weeks old). Production of the predominant corticosteroids secreted by the chicken adrenal gland, corticosterone, cortisol, and aldosterone, was measured by radioimmunoassay after 2-hr incubation of cells with or without steroidogenic agents. Approaching hatch, basal and maximal ACTH-(1-24) (ACTH)-induced corticosteroid production increased steadily and peaked around 1 day posthatch (5-18 times and 3-9 times, respectively, the production values at 18 days embryonic life). Thereafter, corticosteroid production values decreased steadily to 3 weeks posthatch. Corticosterone predominated over the ages studied: Maximal ACTH-induced corticosterone production averaged 52 and 115 times the production values of aldosterone and cortisol, respectively. In addition, maximal ACTH-induced aldosterone production was roughly 2.2 times greater than cortisol production over the ages studied except for a short-lived, disproportionately greater aldosterone production at 1 day posthatch. In addition to perihatch and age-related differences in cellular corticosteroid production, there were also differences in cellular sensitivity to steroidogenic agents as indicated by the differences in half-maximal steroidogenic concentration values (ED50 values) of the steroidogenic agents. Sensitivity to ACTH increased 2.7 times from Day 18 of embryonic life to 1 day posthatch and then decreased steadily to 3 weeks posthatch. In addition, sensitivity to 8-bromo-cAMP (8-Br-cAMP) increased abruptly at 1 day posthatch (nearly 3 times) but then remained constant thereafter. However, a consistent change in cellular sensitivity to 25-hydroxycholesterol was not observed until 3 weeks posthatch (an increase in sensitivity of 3 times that at Day 18 of embryonic life). These data of cellular sensitivity suggest that there were distinct development and maturational alterations in the cellular loci at which ACTH, 8-Br-cAMP, and 25-hydroxycholesterol acted. Thus, during the transition from embryonic to postembryonic life of the domestic fowl, there are alterations in adrenocortical cell steroidogenic capacity and in the function of some cellular loci comprising the corticosteroidogenic pathway.     

Anemia, iron deficiency, and stress fractures in female combatants during 16 months

Yanovich, R, Merkel, D, Israeli, E, Evans, RK, Erlich, T, and Moran, DS. Anemia, iron deficiency, and stress fractures in female combatants during 16 months. J Strength Cond Res 25(12): 3412-3421, 2011-The purpose of this study is to evaluate the hematological profile of military recruits in different settings and training programs and to investigate the link between anemia and iron deficiency with stress fracture (SF) occurrence. We surveyed 3 groups of recruits for 16 months: 221 women (F) and 78 men (M) from 3 different platoons of a gender-integrated combat battalion and a control group (CF) of 121 female soldiers from a noncombat unit. Data were fully collected upon induction and at 4 and 16 months from 48F, 21M, and 31CF. Blood tests, anthropometry, physical aerobic fitness, and SF occurrence were evaluated. On induction day, 18.0 and 19.0% of F and CF were found to be anemic, and 61.4 and 50.9%, respectively, were found to have iron deficiency, whereas 7.7% of M were found to be anemic and 10.2% iron deficient. During the 4 months of army basic training (ABT), anemia and iron deficiency prevalence did not change significantly in any group. After 16-months, anemia prevalence decreased by 8% among F and CF and abated in M. Iron deficiency was prevalent in 50.0, 59.4, and 18.8% of F, CF, and M, respectively. Stress fractures were diagnosed in 14 F during ABT, and they had a significantly higher prevalence (p < 0.05) of anemia and iron deficiency anemia compared to F without SFs. The observed link between anemia and iron deficiency on recruitment day and SFs suggests the importance of screening female combat recruits for these deficiencies. To minimize the health impact of army service on female soldiers, preventative measures related to anemia and iron deficiency should be administered. Further research is needed for evaluating the influence of low iron in kosher meat as a possible explanation for the high prevalence of iron deficiency among young Israeli recruits.     

Fertility and Developmental Toxicity Assessment in Rats and Rabbits with LY500307, a Selective Estrogen Receptor Beta (ERβ) Agonist

LY500307 is a selective estrogen receptor beta (ERβ) agonist that was developed for the treatment of benign prostatic hyperplasia. The in vitro functional selectivity of LY500307 for ERβ agonist activity is 32‐fold above the activity at the alpha receptor (ERα). LY500307 was evaluated in a series of male (M) and female (F) rat fertility and rat and rabbit embryo‐fetal development (EFD) studies, using 20 or 25 animals/group. LY500307 was administered daily by oral gavage starting 2 weeks (F) or 10 weeks (M) before mating, during cohabitation, until necropsy (M) or through gestation day (GD) 6 (F) in the fertility studies and from GD 6 to 17 (rats) or GD 7 to 19 (rabbits) in the EFD studies. Dosage levels of LY500307 ranged from 0.03 to 10 mg/kg/day for rats and from 1 to 25 mg/kg/day for rabbits. Fertility, estrous, maternal reproductive endpoints, conceptus viability, sperm parameters, organ weights, and histopathology were evaluated in the fertility studies. Maternal reproductive endpoints and fetal viability, weight, and morphology were evaluated in the EFD studies. Toxicokinetics were assessed in satellite animals. At 10 mg/kg/day in the male fertility study, findings included decreased body weight (BW); food consumption (FC); fertility, mating, and conception indices; sperm concentration; and reproductive tissue weight (associated with atrophic histologic changes). In the female fertility study, effects included decreased BW and FC at ≥0.3 mg/kg/day and persistent diestrus, delayed mating, and reduced fertility/conception indices at 3 mg/kg/day. In the rat EFD study, findings included decreased maternal BW and FC and increased incidences of adverse clinical signs, abortion, maternal mortality/moribundity, postimplantation loss, and fetal skeletal variations at 3 mg/kg/day. Effects in the rabbit EFD study were limited to decreases in maternal BW and FC at 25 mg/kg/day. In general, systemic maternal exposure increased proportionally with dosage in rats, but less than proportionally in rabbits. In conclusion, the no‐observed adverse effect levels following LY500307 administration were 1 mg/kg/day for male rat fertility, 0.3 mg/kg/day for female rat fertility and EFD, and 25 mg/kg/day for rabbit EFD. Adverse reproductive and developmental effects only occurred at or above parentally toxic dosage levels and were considered predominantly due to off‐target ERα effects.     

Plasma renin activity and aldosterone response to furosemide after chronic growth hormone administration to deficient subjects

The plasma renin activity (PRA) and aldosterone responses to furosemide-induced diuresis were measured in seven children with growth hormone deficiency prior to, during and after the admistration of clinical grade human growth hormone (hGH). The furosemide-stimulated increases in PRA were unchanged from baseline values after one and eight months of hGH administration, but the plasma aldosterone concentrations were significantly increased over control values after eight months of hGH administration.Plasma cortisol concentrations as determined by competitive protein binding assay were measured with the 30-minute cosyntropin (Cortrosyn) test. A normal response as defined by a final level of at least 20 ug/100 ml was found in all children. Resting cortisol concentrations were unchanged during treatment with hGH but the mean increment and final levels were significantly diminished after 8 months of hGH administration. These data have not elucidated the mechanism by which clinical grade hGH improves diuretic-induced aldosterone responsiveness but diminishes cosyntropin stimulation of the adrenal in childhood.     

Plasma hormonal responses at graded hypohydration levels during exercise-heat stress

The effects of graded levels of hypohydration (3, 5, and 7% of body weight) on hormonal responses to exercise in the heat were examined in six heat-acclimated male volunteers. On the day following dehydration, subjects performed light (approximately 25% maximal O2 consumption, 1.03 1 X min-1) exercise in a hot (49 degrees C, 20% relative humidity) environment for four consecutive 25-min intervals interspaced by 10-min rests; blood was obtained before exercise and at approximately 10 min before completion of each exercise period. During euhydration, plasma cortisol (PC) levels manifested significant decrements over time (e.g., time 0, 14.2 micrograms X 100 ml-1 vs. time 2, 8.9 micrograms X 100 ml-1), probably related to its diurnal periodicity. However, during hypohydration, levels of PC were increased and correlated with hypohydration intensity (e.g., time 0, 0, 3, 5, and 7% hypohydration, 14.2, 16.5, 19.8, and 36.2 micrograms X 100 ml-1, respectively). Plasma renin activity (PRA) was increased significantly by hypohydration (e.g., time 0, euhydrated vs. 3%, 3.7 vs. 6.2 units) but was unaffected by exercise in the heat. Plasma aldosterone (ALD) levels were generally increased by exercise in the heat (e.g., time 0 vs. time 4, 3% hypohydration, 12.1 vs. 18.7 ng X 100 ml-1). Regression analysis illustrated that graded intensities of hypohydration were correlated with incremented PRA and ALD through 5% hypohydration. Conversely, PC was incrementally elevated through 7% hypohydration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Developmental patterns of thyroid hormones and testosterone in ferrets

Plasma levels of thyroxine (T4) and triiodothyronine (T3) were measured in male and female ferrets at regular intervals between postnatal day 20 and 150 as well as in adult animals. In addition, testosterone level in male ferrets was measured. All hormones showed characteristic developmental patterns. There is a T4 maximum prior to a T3 maximum in subadult animals which in both cases surpasses adult levels. Testosterone level shows a different developmental pattern. There is an outstanding peak in subadult males around day 60-80, which, however, is surpassed by adult levels during the mating season.     

Circadian rhythm in plasma aldosterone concentration and its seasonal modulation in the camel (Camelus dromedarius) living in the Algerian Sahara desert

Five male camels dwelling in the Algerian Sahara were studied for circadian rhythmicity in plasma aldosterone concentration and its seasonal modulation. Blood was sampled at a frequency of 1 h or less for a span of 27 h during each season of the year. The mean plasma aldosterone concentration exhibited a significant circadian rhythmicity in every season of the year. Plasma aldosterone concentration was lowest in the morning, increased in the afternoon, and generally highest in the late evening. The peak of the circadian rhythm exhibited seasonal variation; it occurred at 20:04h in October, 16:41h in December, 20:40h in March, and 24:16h in June. The rhythm's 24h mean also exhibited seasonal variability, being significantly higher in March and June compared to October.