Exhaustive Exercise Increases Spontaneous but Not fMLP-Induced Production of Reactive Oxygen Species by Circulating Phagocytes in Amateur Sportsmen

Strenuous exercise alters the oxidative response of blood phagocytes to various agonists. However, little is known about spontaneous post exercise oxidant production by these cells. In this cross-over trial, we tested whether an exhaustive treadmill run at a speed corresponding to 70% of VO2max affects spontaneous and fMLP-provoked oxidant production by phagocytes in 18 amateur sportsmen. Blood was collected before, just after, and 1, 3, 5 and 24 h post exercise for determination of absolute and normalized per phagocyte count spontaneous (a-rLBCL, rLBCL) and fMLP-induced luminol-enhanced whole blood chemiluminescence (a-fMLP-LBCL, fMLP-LBCL). a-rLBCL and rLBCL increased by 2.5- and 1.5-times just after exercise (p < 0.05) and then returned to baseline or decreased by about 2-times at the remaining time-points, respectively. a-fMLP-LBCL increased 1.7- and 1.6-times just after and at 3 h post-exercise (p < 0.05), respectively, while fMLP-LBCL was suppressed by 1.5- to 2.3-times at 1, 3, 5 and 24 h post-exercise. No correlations were found between elevated post-exercise a-rLBCL, a-fMLP-LBCL and run distance to exhaustion. No changes of oxidants production were observed in the control arm (1 h resting instead of exercise). Exhaustive exercise decreased the blood phagocyte-specific oxidative response to fMLP while increasing transiently spontaneous oxidant generation, which could be a factor inducing secondary rise in antioxidant enzymes activity.

THE NEUROENDOCRINE SYSTEM RESPONSE OF 2-5 G COMMUNICATION ELECTROMAGNETIC FIELD ANIMAL EXPOSURE

Background. The neuroendocrine effect on the hypothalamus-pituitary-adrenal cortex axis is significant example stressor of electromagnetic exposure for biological object. Aim. The neuroendocrine effect investigation of multi-frequency electromagnetic field laboratory animals’ exposure from 2-5 generations cellular base stations Methods. The neuroendocrine status evaluated by corticosterone and adrenocorticotropic hormone (ACTH) concentrations in blood exposed and sham rats. ACTH and corticosterone rat blood assessed by immunoenzyme method. Results. The results of the multi-frequency electromagnetic field laboratory animals’ exposure from 2-5 generations cellular base stations in a chronic experiment showed wave-like changes in the hypothalamic-pituitary-adrenal function. These changes are manifested in an immediate increase in corticosteroids secretion and depression of the corticosteroid response to normal or subnormal levels. After 3 month chronic exposure there was a secondary rise in hormonal secretion.

GnRH Increases c-Fos Half-Life Contributing to Higher FSHβ Induction

GnRH is a potent hypothalamic regulator of gonadotropin hormones, LH and FSH, which are both expressed within the pituitary gonadotrope and are necessary for the stimulation of gametogenesis and steroidogenesis in the gonads. Differential regulation of LH and FSH, which is essential for reproductive fitness, is achieved, in part, through the varying of GnRH pulse frequency. However, the mechanism controlling the increase in FSH during the periods of low GnRH has not been elucidated. Here, we uncover another level of regulation by GnRH that contributes to differential expression of the gonadotropins and may play an important role for the generation of the secondary rise of FSH that stimulates folliculogenesis. GnRH stimulates LHβ and FSHβ subunit transcription via induction of the immediate early genes, Egr1 and c-Fos, respectively. Here, we determined that GnRH induces rapidly both Egr1 and c-Fos, but specifically decreases the rate of c-Fos degradation. In particular, GnRH modulates the rate of c-Fos protein turnover by inducing c-Fos phosphorylation through the ERK1/2 pathway. This extends the half-life of c-Fos, which is normally rapidly degraded. Confirming the role of phosphorylation in promoting increased protein activity, we show that a c-Fos mutant that cannot be phosphorylated by GnRH induces lower expression of the FHSβ promoter than wild-type c-Fos. Our studies expand upon the role of GnRH in the regulation of gonadotropin gene expression by highlighting the role of c-Fos posttranslational modification that may cause higher levels of FSH during the time of low GnRH pulse frequency to stimulate follicular growth.

Unique biphasic progestagen profile in parturient and non-parturient giant pandas (Ailuropoda melanoleuca) as determined by faecal hormone monitoring

The luteal phase of the giant panda has been exclusively assessed by studying urinary hormone patterns in a very few individuals. To better understand hormonal dynamics of protracted progestagen excretion in this endangered species, we monitored hormonal metabolites in the fibrous faeces of multiple females in the USA and China. Giant pandas that were anoestrual during the breeding season excreted baseline progestagen throughout the year. In contrast, there were two distinctive periods when progestagen excretion increased in females that experienced behavioural oestrus, the first being modest, lasting for 61–122 days, and likely reflecting presumptive ovulation. This increase was far surpassed by a secondary rise in progestagen excretion associated with a rejuvenated luteal capacity or hormone production from an extra-gonadal source. The duration of this ‘secondary’ rise in progestagen excretion averaged ∼45 days and terminated in a decline to baseline coincident with parturition or the end of a non-parturient luteal interval. Data revealed that, even with a complex, biphasic progestagen profile, the longitudinal patterns produced by giant pandas were relatively consistent among animals and across years within individuals. However, progestagen excretion patterns throughout this period could not be used to discriminate among non-pregnant, pregnant or pseudopregnant states.

Biochemical and Functional Characterization of PEGylated rVWF.

Covalent modification of therapeutic proteins by polyethylene glycol derivatives is an established method for improving pharmacokinetic properties of therapeutic proteins. Highly purified rVWF expressed in CHO cells, was chemically modified via PEGylation of lysine residues at mild alkaline pH with PEG succinimidyl succinate (linear 5 kDa PEG). Increasing the amount of PEG used in the coupling procedure, the molecular size of VWF increased, as demonstrated in SDS-PAGE and by agarose gel electrophoreses indicating an increase in size of the bands resembling the VWF multimers. PEGylation of rVWF reduced platelet-aggregating and collagen-binding functions by 60% (VWF:RCo activity) and 40% (VWF:CB activity). While FVIII-binding capacity, measured by a FVIII binding ELISA, was reduced and reduction correlated with the amount of PEG bound to VWF, there was almost no effect on FVIII binding affinity which remained in the same order of magnitude as measured with non-PEGylated VWF. Similar results were obtained when rVWF was PEGylated via carbohydrate moieties after oxidation and subsequent derivatization with monomethoxy-PEG hydrazide. PEGylated rVWF was applied to VWF-deficient mice at a dose of 40 VWF:Ag U/kg and plasma levels were monitored for up to 24 hours. As a control, non-modified rVWF was applied to the animals. PEGylated VWF had substantially prolonged survival in the circulation compared with non-modified rVWF with an increase of the AUC by a factor of &gt;10. VWD mice substituted with human VWF show a secondary rise in FVIII bringing them into the FVIII levels measured in C57Bl/6 control mice. This secondary rise was sustained after treatment with PEGylated rVWF where FVIII levels above the starting level were measurable even 48 hours after injection while in the control group base line FVIII levels were reached already after 24 hours. rVWF is the largest protein ever PEGylated and PEGylation results in prolonged survival in the circulation while maintaining FVIII stabilizing functions of the VWF molecule in vivo.

Delayed depolarization of the cog-wheel valve and pulmonary-to-systemic shunting in alligators

SUMMARYAlligators and other crocodilians have a cog-wheel valve located within the subpulmonary conus, and active closure of this valve during each heart beat can markedly and phasically increase resistance in the pulmonary outflow tract. If this increased resistance causes right ventricular pressure to rise above that in the systemic circuit, right ventricular blood can flow into the left aorta and systemic circulation, an event known as pulmonary-to-systemic shunting. To understand better how this valve is controlled, anaesthetized American alligators (Alligator mississippiensis) were used to examine the relationships between depolarization of the right ventricle,depolarization/contraction of the cog-wheel valve muscle and the resultant right ventricular, pulmonary artery and systemic pressures. Depolarization swept across the right ventricle from the apex towards the base (near where the cog-wheel valve muscle is located) at a velocity of 91±23 cm s-1 (mean ± S.E.M., N=3). The cog-wheel valve electrocardiogram (ECG) (and thus contraction of the valve) trailed the right ventricular ECG by 248±28 ms (N=3), which was equivalent to 6-35 % of a cardiac cycle. This long interval between right ventricular and valve depolarization suggests a nodal delay at the junction between the base of the right ventricle and the cog-wheel valve. The delay before valve closure determined when the abrupt secondary rise in right ventricular pressure occurred during systole and is likely to strongly influence the amount of blood entering the pulmonary artery and thus to directly control the degree of shunting. Left vagal stimulation (10-50 Hz) reduced the conduction delay between the right ventricle and cog-wheel valve by approximately 20 % and reduced the integrated cog-wheel ECG by 10-20 %. Direct application of acetylcholine (1-2 mg) also reduced the integrated cog-wheel ECG by 10-100 %;however, its effect on the conduction delay was highly variable (-40 to +60%). When the cog-wheel valve muscle was killed by the application of ethanol,the cog-wheel ECG was absent, right ventricular and pulmonary pressures remained low and tracked one another, the secondary rise in right ventricular pressure was abolished and shunting did not occur. This study provides additional, direct evidence that phasic contraction of the cog-wheel valve muscle controls shunting, that nervous and cholinergic stimulation can alter the delay and strength of valve depolarization and that this can affect the propensity to shunt.

Skeletal muscle capillary hemodynamics from rest to contractions: implications for oxygen transfer

Muscle contractions evoke an immediate rise in blood flow. Distribution of this hyperemia within the capillary bed may be deterministic for muscle O2diffusing capacity and remains unresolved. We developed the exteriorized rat ( n = 4) spinotrapezius muscle for evaluation of capillary hemodynamics before (rest), during, and immediately after (post) a bout of twitch contractions to resolve (second-by-second) alterations in red blood cell velocity ( V RBC) and flux ( f RBC). Contractions increased (all P < 0.05) capillary V RBC (rest: 270 ± 62 μm/s; post: 428 ± 47 μm/s), f RBC (rest: 22.4 ± 5.5 cells/s; post: 44.3 ± 5.5 cells/s), and hematocrit but not the percentage of capillaries supporting continuous RBC flow (rest: 84.0 ± 0.7%; post: 89.5±1.4%; P > 0.05). V RBC peaked within the first one or two contractions, whereas f RBC increased to an initial short plateau (first 12–20 s) followed by a secondary rise to steady state. Hemodynamic temporal profiles were such that capillary hematocrit tended to decrease rather than increase over the first ∼15 s of contractions. We conclude that contraction-induced alterations in capillary RBC flux and distribution augment both convective and diffusive mechanisms for blood-myocyte O2 transfer. However, across the first 10–15 s of contractions, the immediate and precipitous rise in V RBC compared with the biphasic and prolonged increase of f RBC may act to lower O2 diffusing capacity by not only reducing capillary transit time but by delaying the increase in the instantaneous RBC-to-capillary surface contact thought crucial for blood-myocyte O2 flux.