Acute effects of corticosterone injection on paternal behavior in California mouse (Peromyscus californicus) fathers

Glucocorticoids are thought to mediate the disruption of parental behavior in response to acute and chronic stress. Previous research supports their role in chronic stress; however, no study has experimentally tested the effects of acute glucocorticoid elevation on paternal behavior. We tested the prediction that acute corticosterone (CORT) increases would decrease paternal behavior in California mouse fathers and would lead to longer-term effects on reproductive success, as even short-term increases in CORT have been shown to produce lasting effects on the hypothalamic-pituitary-adrenal axis. First-time fathers were injected with 30 mg/kg CORT, 60 mg/kg CORT or vehicle, or left unmanipulated. Interactions between the male and its pup(s) were recorded 1.5–2 h after injection and scored for paternal and non-paternal behavior. Treatment groups were combined into control (unmanipulated + vehicle, n = 15) and CORT (30 mg/kg + 60 mg/kg, n = 16) for analysis based on resulting plasma CORT concentrations. CORT treatment did not alter paternal or non-paternal behaviors or any long-term measures (male body mass or temperature, pup growth rate, pup survival, interbirth interval, number or mass of pups born in the second litter). Fathers showed a significant rise in body mass at day 30 postpartum, followed by a decrease in body mass after the birth of the second litter; however, this pattern did not differ between the CORT and control groups. In summary, acute elevation of plasma CORT did not alter direct paternal behavior, body mass, or reproductive outcomes, suggesting that acute CORT elevation alone does not overtly disrupt paternal care in this biparental mammal.     

Effect of corticosterone on growth and welfare of broiler chickens showing long or short tonic immobility

Tonic immobility (TI) test is commonly used to assess fear. Animals showing different TI durations demonstrate distinct behavior and biochemical responses to stress. However, less is known about how TI phenotype affects growth and welfare of domestic fowl. In this study, broiler chickens (Gallus gallus) were classified into short and long TI duration (STI and LTI) phenotypes and treated chronically with vehicle (CON) or corticosterone (CORT). STI broilers demonstrated significantly higher growth rate with higher breast muscle yield (P < 0.05) and liver weight relative to BW tended to be lower (P = 0.053), which was accompanied by higher serum concentration of CORT (P < 0.05) and uric acid (P < 0.01), but lower serum level of T4 (P = 0.01). CORT severely reduced body weight, as well as the relative weight of muscle, bursa of Fabricius and spleen (P < 0.001), but relative liver weight was increased (P < 0.001). CORT-treated chickens had reduced serum CORT, elevated heterophile/lymphocyte ratio, and increased serum levels of total and free T3. STI broilers displayed more preening behavior (P < 0.05), yet CORT elicited more walking behavior (P < 0.05). No difference was observed in the welfare assessment scores between STI and LTI phenotypes under basal situation, while LTI chickens showed significantly increased incidence of pad dermatitis compared to STI under CORT exposure. The results suggest that STI broilers demonstrate better growth performance and higher adaptability to stress compared to LTI chickens.     

Chronic corticosterone treatment enhances extinction-induced depression in aged rats

Withdrawal and avoidance behavior are common symptoms of depression and can appear as a consequence of absence of reward, i.e. extinction-induced depression (EID). This is particularly relevant for the aged organism subjected to pronounced loss of former rewards. Avoidance of the former site of reward and increased withdrawal into a distant compartment accompany extinction of food-rewarded behavior in rodent models. During extinction, behavioral markers for re-learning dissociate from indicators of extinction-induced depression. Here we examined the effect of a chronic treatment with corticosterone (CORT), a well-known inducer of depression-related behavior, on EID in adult and aged rats. Adult (3–4 months) and aged (18 months) male rats were treated with CORT via drinking water for 3 weeks prior to extinction of a cued food-reward task. CORT treatment increased the distance from the site of reward and decreased goal tracking behavior during extinction, especially in the aged rats. Plasma hormone levels measured before and after restraint stress showed a decline in basal ACTH- and CORT-levels after chronic CORT treatment in aged animals. The treatment significantly impaired the HPA-axis activation after acute stress in both, adult and aged animals, alike. Altogether, these findings show an enhancement of EID after chronic CORT treatment in the aged organism, which may be mediated by an impaired HPA-axis sensitivity. These findings may have special relevance for the investigation of human geriatric depression.     

Bone response of broiler chickens (Gallus gallus domesticus) induced by corticosterone

Experiments were conducted with chickens exposed to corticosterone (CORT), with the aim of determining its effects on bone characteristics. At 7 d of age, the experimental birds were injected daily with CORT (4 mg/kg of body mass) for 1 week. CORT administration significantly decreased the body weight while increasing relative liver weight of the chickens and the bone parameters were also decreased. Histology and immunohistochemistry of type X collagen revealed that CORT reduced the lengths of proliferative and prehypertrophic zone in growth plate and the number of positive chondrocytes in the prehypertrophic zone. In conclusion exposure to CORT depressed the growth performance and retarded the longitudinal growth of the long bones by inhibiting the proliferation and differentiation of chondrocytes in growth plate in broilers.     

Neuroendocrinology of context-dependent stress responses: vasotocin alters the effect of corticosterone on amphibian behaviors

The ability of an animal to respond with appropriate defensive behaviors when confronted with an immediate threat can affect its survival and reproductive success. In the roughskin newt (Taricha granulosa), exogenous corticosterone (CORT) rapidly blocks and vasotocin (VT) enhances reproductive behaviors (mainly clasping behavior). Electrophysiological studies have shown that pretreatment of male Taricha with VT counteracts the inhibitory effects of CORT on neuronal activity in the medulla. To test whether similar interactions between VT and CORT influence reproductive behaviors in Taricha, we recorded the time spent and incidence of clasping in males injected with VT or vehicle at 60 min and then CORT or vehicle at 5 min before presentation of a female. This study found that clasping behavior is suppressed in males that received vehicle and then CORT, but is not suppressed in males that received VT and then CORT. Considering these results and the possibility that the performance of clasping behaviors might cause increases in endogenous VT activity, we tested whether the suppressive effects of CORT administration on clasping behavior would occur in males that had recently clasped females. The study found that, in contrast to males that had been isolated from females, CORT administration did not suppress clasping behavior in males that had been allowed to clasp females for 60 min prior to the hormone injection. Our results suggest that, at least in this amphibian and perhaps in other animals, the neuroendocrine regulation of alternative behavioral responses to threats involves functional interactions between corticosteroids and VT-like peptides.     

Endocrine responses and milk emission characteristics in high yielding Alpine dairy goats under once daily milking management

This study was done to verify if the lack of increase of milk fat content observed in Alpine dairy goats under once daily milking (ODM) compared to twice daily milking (TDM), results from disturbances of animals and/or milk ejection reflex. In this respect, we determined the milk yield and composition in the same 12 multiparous Alpine dairy goats when they were managed first under TDM (period 1: P1) and then under ODM (period 2: P2). Furthermore, oxytocin (OT) and cortisol (CORT) releases and milk emission kinetic of these goats were measured at morning milking 2 and 4 times in P1 and P2, respectively.ODM compared to TDM, caused 18 and 23% reductions, respectively in daily milk yield and milk fat content without milk protein content modification.Although baseline concentration of blood OT was lower under ODM than TDM management (7.0 pg/mL vs 17.8 ± 2.0 pg/mL, respectively), ODM did not modify the total amount of OT released during milking (15,484 pg/mL/32 min vs 18,996 ± 2865.3 pg/mL/32 min, respectively), the peak concentration of OT (57.2 pg/mL vs 73.6 ± 10.5 pg/mL, respectively) or the time to reach it (3.0 min vs 2.0 ± 0.5 min, respectively) by comparison to TDM.ODM compared to TDM, never modified the baseline concentrations of CORT (6.1 ng/mL vs 7.1 ± 1.1 ng/mL, respectively), the total amount of CORT released (11,727 ng/mL/32 min vs 10,073 ± 1522.2 ng/mL/32 min, respectively), the peak concentrations of CORT (16.1 ng/mL vs 15.1 ± 2.1 ng/mL, respectively) and the time to reach it (13.1 min vs 11.0 ± 1.5 min).During ODM, milk flow latency was reduced (−61%) while the mean flow rate was increased (+28%) by comparison to TDM. ODM compared to TDM management, did not modify the maximum flow rate (1.6 L/min vs 1.6 ± 0.2 L/min, respectively) or the time to reach this maximum (103.0 s vs 95.0 ± 10.0 s, respectively). The total milking duration at morning milking was not different (250.0 s vs 221.0 ± 22.0 s, respectively) although the morning milk yield was significantly higher under ODM management (2.63 kg/d vs 1.87 ± 0.1 kg/d, respectively).This results show that milk emission is improved under ODM management in Alpine goats without inhibition or disturbance of neuro-hypophyseal OT release pattern and lack of activation of the hypothalamic–pituitary–adrenal axis and plasma cortisol increase, disproving our initial hypotheses of a disturbance of animals and/or incomplete milk ejection to explain the low fat content of milk under ODM in this breed.     

In vitro evaluation of the fermentation characteristics of the carbohydrate fractions of hulless barley and other cereals in the gastrointestinal tract of pigs

An in vitro model was used to study the fermentation characteristics of carbohydrate fractions of hulless barley (hB), in comparison to hulled barley (HB), hulled oat and oat groats (OG) in the pig intestine. For this purpose, 6 hulless barley cultivars (hB), varying in β-glucan content (36–99 g/kg DM), were compared to 3 HB cultivars, 2 oat groat samples (OG), 3 oat varieties and a reference sample of wheat. The residue of a pepsin–pancreatin hydrolysis was incubated in a buffered mineral solution inoculated with pig faeces. Gas production, proportional to the amount of fermented carbohydrates, was measured for 48 h and kinetics modelled. The fermented solution was subsequently analyzed for microbial production of short-chain fatty acids (SCFA) and ammonia. In vitro dry matter degradability varied according to ingredient (P<0.001). Higher values were observed for OG, ranging from 0.88 to 0.99 as compared to oat, hB and HB, for which degradability ranged from 0.63 to 0.73, 0.68 to 0.80 and 0.69 to 0.71, respectively. A “cereal type” effect (P<0.05) was observed on fermentation kinetics parameters. Total gas production was higher (P<0.05) with hB (224 ml/g DM incubated) than with HB and oat (188 and 55 ml/g DM incubated, respectively). No difference was observed between hB cultivars (P>0.05) for total gas production but differences (P<0.001) were found for lag time and the fractional rate of degradation. Hulless barley cultivar CDC Fibar (waxy starch) and CDC McGwire (normal starch) started to ferment sooner (lag time of 0.7 and 0.9 h, respectively) than SH99250 (high amylose starch; 1.7 h). The fractional rate of degradation was similar in both hB and OG (0.15/h on average), which was higher than that of HB (0.12/h). The production of SCFA was also higher (P<0.05) with hB (6.1 mmol/g DM incubated, on average) than with HB and oat (4.9 and 2.9 mmol/g DM incubated, respectively). Similar trends were found for SCFA production expressed per g fermented carbohydrates, with higher butyrate and lower acetate ratio. In contrast, oat fermentation generated higher (P<0.05) ammonia concentration (1.4 mmol/g DM incubated, on average) than hB (1.0 mmol/g DM incubated). In summary, hulless barleys, irrespective of cultivar type had higher in vitro fermentability and produced more SCFA and less ammonia than hulled barley and oat. Thus, hulless barleys have a better potential to be used in pig nutrition to manipulate the fermentation activity in the intestine of pigs.     

Relationship between ventilatory threshold and muscle fiber conduction velocity responses in trained cyclists

The relationship between surface electromyography (SEMG) amplitude and the ventilatory threshold has been extensively studied. However, previous studies of muscle fiber conduction velocity (MFCV) are scarce and present insufficient evidence concerning the relationship between MFCV and metabolic responses during cycling. Based on that fact, the purpose of this study is twofold: (1) to investigate the existence of a MFCV threshold (MFCVT) during cycling and (2) to verify if this possible breakpoint is correlated with the ventilatory threshold (VT) and the SEMG threshold (SEMGT). Eight trained male cyclists (age 36.0 ± 9.7 years) performed an incremental cycling test with initial workload of 150 W gradually incremented by 20 W min^?1 until the exhaustion. Gas analyses were conducted using a breath-by-breath open-circuit spirometry and SEMG were registered from vastus lateralis in each pedaling cycle with a linear array of electrodes. A bi-segmental linear regression computer algorithm was used to estimate VT, MFCVT and SEMGT respectively in the carbon dioxide production (VCO₂), MFCV and electromyography root mean square (EMG RMS) curves. The one way ANOVA for repeated measures did not reveal any significant difference among VT (77.1 ± 7.5% of VO₂max), MFCVT (80.3 ± 10.4% of VO₂max) and SEMGT (81.9 ± 11.7% of VO₂max). The Bland and Altman procedure confirmed a good concordance between SEMGT and VT (Bias = 5.5 of %VO₂max) as well as MFCVT and VT (Bias = 5.2 of %VO₂max). The present findings suggest that muscle fiber conduction velocity threshold is a valid and reliable non-invasive tool to obtain information about ventilatory threshold in trained cyclists.     

Synthesis of octyl-β-d-glucopyranoside catalyzed by Thai rosewood β-glucosidase-displaying Pichia pastoris in an aqueous/organic two-phase system

We explored the ability of a Thai rosewood β-glucosidase-displaying P. pastoris whole-cell biocatalyst (Pp-DCBGL) system to synthesize alkyl β-d-glucosides. The primary investigation centered on the synthesis of octyl-β-d-glucopyranoside (octyl-glu, OG). OG could be synthesized through reverse hydrolysis reaction with very low efficiency. Then, OG was synthesized between BG and octanol by a transglycosylation reaction. In a 2-ml reaction system, OG was synthesized with a conversion rate of 51.1% in 3 h when 5 mg/ml BG was utilized as the glucosyl donor under optimized conditions. And, even after being reused four times, the Pp-DCBGL was relatively stable. Additionally, a 500-ml-scale reaction system was conducted in a 2-L stirred reactor with a conversion rate of 47.5% in 1.5 h. Moreover, the conversion rate did not decrease after the whole-cell catalyst was reused two times. In conclusion, Pp-DCBGL has high reaction efficiency and operational stability, which is a powerful biocatalyst available for industrial synthesis.     

Environmental enrichment exerts anxiolytic effects in the Indian field mouse (Mus booduga)

Environmental enrichment (EE) is known to have behavioral and physiological anxiolytic effects in several animal models. However, it is as yet unclear how EE modulates behavior of wild animals and the underlying molecular mechanisms. The adult male field mouse Mus booduga (n = 42) captured at agricultural field, were housed in non-enriched standard condition (SC) for 7 days and considered as directly from wild (DW). Another two groups of mice were housed in either EE or SC for 30 days. Behavioral testing was carried out to assess their anxiety-like behavior in the elevated plus-maze (EPM). We found that on EPM, mice housed in EE display less anxiety like behavior when compared to mice housed in SC. Exposure to plus-maze did not increase the levels of corticosterone (CORT) in prefrontal cortex (PFC) and circulating CORT, and adrenocorticotropic hormone (ACTH) in the mice housed in EE but not in the mice housed in SC. We observed a trend in the EE induced inhibition of expression of corticotropin releasing hormone (CRH), glucocorticoid receptor (GR), E2 ubiquitin-conjugating enzyme (Ubc9) and steroid receptor coactivator-1 (SRC-1) mRNA levels, which are all known to be involved in the stress response signaling pathway. Our study suggests that EE exerts therapeutic and anxiolytic effects against stressors.     

Cathepsin G activity lowers plasma LDL and reduces atherosclerosis

Cathepsin G (CatG), a serine protease present in mast cells and neutrophils, can produce angiotensin-II (Ang-II) and degrade elastin. Here we demonstrate increased CatG expression in smooth muscle cells (SMCs), endothelial cells (ECs), macrophages, and T cells from human atherosclerotic lesions. In low-density lipoprotein (LDL) receptor-deficient (Ldlr^–/–) mice, the absence of CatG reduces arterial wall elastin degradation and attenuates early atherosclerosis when mice consume a Western diet for 3 months. When mice consume this diet for 6 months, however, CatG deficiency exacerbates atherosclerosis in aortic arch without affecting lesion inflammatory cell content or extracellular matrix accumulation, but raises plasma total cholesterol and LDL levels without affecting high-density lipoprotein (HDL) or triglyceride levels. Patients with atherosclerosis also have significantly reduced plasma CatG levels that correlate inversely with total cholesterol (r = –0.535, P < 0.0001) and LDL cholesterol (r = –0.559, P < 0.0001), but not with HDL cholesterol (P = 0.901) or triglycerides (P = 0.186). Such inverse correlations with total cholesterol (r = –0.504, P < 0.0001) and LDL cholesterol (r = –0.502, P < 0.0001) remain significant after adjusting for lipid lowering treatments among this patient population. Human CatG degrades purified human LDL, but not HDL. This study suggests that CatG promotes early atherogenesis through its elastinolytic activity, but suppresses late progression of atherosclerosis by degrading LDL without affecting HDL or triglycerides.     

Mensurations échographiques de la thyroïde chez des enfants de zéro à 15 ans de la ville de Ouagadougou

Among the methods used to carry out measurements of thyroid, echography is the best because it is noninvasive and more specific. The goals of this study were to determine the normal thyroid volume of the Burkinabe child; to study the parameters which induce a variation of thyroid volume and to compare our values with those from other localities. Through a cross-sectional study, 240 children from the town of Ouagadougou benefited from a thyroid echography. Thus the height (h), the transverse diameter (dt) and the thickness (e) were measured. Volume (vl) of each lobe was estimated by: vl = h × dt × e × 3.14/6. The total volume (VT) is the sum of the volumes of each lobe, the isthmus being neglected. A correlation set at the threshold p < 0.001 has been carried out between VT and some anthropometric parameters. The following averages were observed: before one year, the average volume is of 0.51 L ± 0.21; from one to three years, it is of 0.95 mL ± 0.33; from four to six years, the average volume is of 1.35 mL ± 0.43; from seven to nine years, it is of 1.95 mL ± 0.62. From 10 to 12 years, the average volume is of 3.01 mL ± 1.08 and it is of 5.32 mL ± 2.07 from 13 to 15 years. It stands out that the VT is positively associated with the age (r = 0.82), with the size (r = 0.73), with the weight (r = 0.81) and with body surface (r = 0.78). Moreover, the VT is higher among boys than in girls beyond one year of age. This parameter varies according to the area of origin. Lastly, compared with the American, European and Asian averages, our values are smaller. This study enabled us to establish our own standards which we will be able from now on to use in daily practice. However, multicentric studies associated with thyroid and sexual hormones blood levels measurements must be undertaken to ascertain these data.     

Simultaneous quantification of the organophosphorus pesticides dimethoate and omethoate in porcine plasma and urine by LC–ESI-MS/MS and flow-injection-ESI-MS/MS

Dimethoate is an organophosphorus toxicant used in agri- and horticulture as a systemic broad-spectrum insecticide. It also exhibits toxic activity towards mammalian organism provoked by catalytic desulfuration in the liver producing its oxon-derivative omethoate thus inhibiting acetylcholinesterase, initiating cholinergic crisis and ultimately leading to death by respiratory paralysis and cardiovascular collapse. Pharmaco- and toxicokinetic studies in animal models help to broaden basic understanding of medical intervention by antidotes and supportive care. Therefore, we developed and validated a LC–ESI-MS/MS method suitable for the simultaneous, selective, precise (RSD_intra-day 1–8%; RSD_inter-day 5–14%), accurate (intra-day: 95–107%; inter-day: 90–115%), and robust quantification of both pesticides from porcine urine and plasma after deproteinization by precipitation and extensive dilution (1:11,250 for plasma and 1:40,000 for urine). Accordingly, lower limits of quantification (0.24–0.49 μg/ml plasma and 0.78–1.56 μg/ml urine) and lower limits of detection (0.12–0.24 μg/ml plasma and 0.39–0.78 μg/ml urine) were equivalent to quite low absolute on-column amounts (1.1–2.1 pg for plasma and 2.0–3.9 pg for urine). The calibration range (0.24–250 μg/ml plasma and 0.78–200 μg/ml urine) was subdivided into two linear ranges (r² ≥ 0.998) each covering nearly two orders of magnitude. The lack of any interfering peak in 6 individual blank specimens from plasma and urine demonstrated the high selectivity of the method. Furthermore, extensive sample dilution causing lowest concentration of potentially interfering matrix ingredients prompted us to develop and validate an additional flow-injection method (FI-ESI-MS/MS). Validation characteristics were as good as for the chromatographic method but sample throughput was enhanced by a factor of 6. Effects on ionization provoked by plasma and urine matrix from 6 individuals as well as in the presence of therapeutics (antidotes) administered in an animal study were investigated systematically underling in the reliability of the presented methods. Both methods were applied to porcine samples derived from an in vivo animal study.     

Phase state and surface topography of palmitoyl-ceramide monolayers

In cell biology (and in many biophysical) studies there is a natural tendency to consider ceramide as a highly condensed, solid-type lipid conferring rigidity and close packing to biomembranes. In the present work we advanced the understanding of the phase behavior of palmitoyl-ceramide restricted to a planar interface using Langmuir monolayers under strictly controlled and known surface packing conditions. Surface pressure–molecular area isotherms were complemented with molecular area–temperature isobars and with observations of the surface topography by Brewster Angle Microscopy. The results described herein indicate that palmitoyl-ceramide can exhibit expanded, as well as condensed phase states. Formation of three phases was found, depending on the surface pressure and temperature: a solid (1.80 nm thick), a liquid-condensed (1.73 nm thick, likely tilted) and a liquid-expanded (1.54 nm thick) phase over the temperature range 5–62 °C. A large hysteretic behavior is observed for the S phase monolayer that may indicate high resistance to domain boundary deformation. A second (or higher) order S → LC phase transition is observed at about room temperature while a first order LC → LE transition occurs in a range of temperature encompassing the physiological one (observed above 30 °C at low surface pressure). This phase behavior broadens the view of ceramide as a type of lipid not-always-rigid but able to exhibit polymorphic properties.     

Comparative efficacy of different approaches to managing Meloidogyne incognita on green bean

A greenhouse study was conducted to compare the relative efficacy of different approaches to managing Meloidogyne incognita on green bean. These approaches included chemical (fumigant, non-fumigant, seed dressing, and seed dip), biological (the egg-parasitic fungus, Paecilomyces lilacinus and the mycorrhizal fungus Glomus sp.), physical (soil solarization), and cultural (chicken litter and urea) methods. Accordingly, nine different control materials and application methods plus nematode-infected and non-infected controls were compared. Two important parameters were considered: plant response (plant growth and root galling) and nematode reproduction (production of eggs and the reproduction factor Rf). The results showed that the use of chicken litter as an organic fertilizer severely affected the growth and survival of the plants. Therefore, this treatment was removed from the evaluation test. All of the other eight treatments were found to be effective against nematode reproduction, but with different levels of efficacy. The eight treatments decreased (38.9–99.8%) root galling, increased plant growth and suppressed nematode reproduction. Based on three important criteria, namely, gall index (GI), egg mass index (EMI), and nematode reproduction factor (RF), the tested materials and methods were categorized into three groups according to their relative control efficacy under the applied test conditions. The three groups were as follows: (1) the relatively high effective group (GI = 1.0–1.4, Rf = 0.07–0.01), which included the fumigant dazomet, the non-fumigant fenamiphos, soil solarization, and seed dip with fenamiphos; (2) the relatively moderate effective group (GI = 3.4–4.0, Rf = 0.24–0.60), which included seed dressing with fenamiphos and urea; and (3) the relatively less effective group (GI = 5.0, Rf = 32.2–37.2), which included P. lilacinus and Glomus sp.     

Muscle fibre conduction velocity and cardiorespiratory response during incremental cycling exercise in young and older individuals with different training status

We investigated the effect of ageing and training on muscle fibre conduction velocity (MFCV) and cardiorespiratory response during incremental cycling exercise. Eight young (YT; 24 ± 5 yrs) and eight older (OT; 64 ± 3 yrs) cyclists, together with eight young (YU; 27 ± 4 yrs) and eight older (OU; 63 ± 2 yrs) untrained individuals underwent to an incremental maximal test on a cycle ergometer. Ventilatory threshold (VT), respiratory compensation point (RCP) and maximal oxygen uptake (VO₂max) were identified and MFCV recorded from the vastus lateralis muscle using surface electromyography with linear arrays electrodes.In YT MFCV increased with the exercise intensity, reaching a peak of 4.99 ± 1.02 [m/s] at VT. Thereafter, and up to VO₂max, MFCV declined. In YU MFCV showed a similar trend although the peak [4.55 ± 0.53 m/s] was observed, at 75% of VO₂max an intensity higher than VT (66% of VO₂max). In both YT and YU MFCV did not decline until RPC, which occurred at 78% VO₂max in YU and at 92% VO₂max (P < 0.01) in YT. Differently from young individuals, MFCV in older subjects did not increase with exercise intensity. Moreover, maximal MFCV in OU was significantly lower [3.53 ± 0.40 m/s;] than that of YT (P < 0.005) and YU (P < 0.05).The present study shows that, especially in young individuals, MFCV reflects cardiorespiratory response during incremental dynamic cyclic exercise and hence can be used to investigate motor unit recruitment strategies.     

Metal complexes of crosslinked chitosans: Correlations between metal ion complexation values and thermal properties

A series of heavy metal complexes of crosslinked chitosans were evaluated by thermogravimetric studies. The metal complexes with Cu, Cd and Hg ions exhibiting the highest complexing ability to chitosans (Hg 354–364, Cu 100–112, and Cd 121–160, in mg/g chitosan), had the lowest onset of degradation temperatures (range 194–210 °C) and the lowest final degradation temperatures (generally less than 294–304 °C for Hg, 296–338 °C for Cu, and 305–368 °C for Cd complexes). Mn ion, with the lowest binding to chitosans (Mn 5–7 mg/g), showed the reverse behavior, having onset (240–248 °C) and final degradation temperatures (range 300–368 °C). Zn (binding 74–87 mg/g) and Pb (binding 39–62 mg/g) ions have a binding ability intermediate to Cu/Cd/Hg and Mn extremes, and therefore the effects on onset and final degradation temperatures are intermediate to these values.     

Reliability of mechanomyography and triaxial accelerometry in the assessment of balance

Reliability of high-resolution accelerometery (HRA) and mechanomyography (MMG) was evaluated for the assessment of single-leg balance. Subjects (5M/5F, 25 ± 3 yr; 169.4 ± 11.7 cm; 79.0 ± 16.9 kg) participated in fifteen (three randomized bouts of five repetitions) 15-s dominant leg stances. A single HRA was fixed superficial to L3/L4 segment to capture motions relative to the center-of-mass, and three-uniaxial accelerometers were fixed on the surface of the dominant leg correspondent to the vastus medialis (VM), vastus lateralis (VL), and soleus (SOL) muscles to record MMG. Triaxial signals from the HRA (s.r. = 625 Hz) were streamed to a base station, simultaneously with MMG (s.r. = 1000 Hz). Signals were sampled, recorded and later analyzed. HRAs were recorded in g’s for vertical (VT), medial/lateral (ML), anterior/posterior (AP) directions, and resultant (RES) scalar. Intraclass correlation coefficients (ICC) were computed for each and Pearson’s r was calculated for the relationships between MMG and HRA (α ? 0.05). Except for RES (ICC = 0.36), all measures demonstrated moderately strong reliability (ICC = 0.75, 0.73, 0.63, 0.87, 0.89, and 0.86 for VM, VL, SOL, VT, ML, and AP, respectively). HRA and MMG provide reliable information pertaining to balance, and may have application in evaluating postural control and stability.     

Does sex matter? Differential responses to corticosterone administration in the zebra finch

Because of potentially deleterious effects of chronic stress, physiological measurements of stress hormones (in birds, corticosterone (CORT)) are often used to determine the consequences of natural or human-induced change. Often, it is assumed that CORT levels will be similar between the sexes and the results are pooled. However, recent studies have reported sex differences in CORT concentrations in avian species. As zebra finches (Taeniopygia guttata) are one of the most widely used bird species in laboratory studies worldwide, potential sex-specific differences in hormone metabolism, as well as the clearance rate of oral doses of exogenous CORT, are highly relevant. The results of this study show that female zebra finches have a significantly higher baseline CORT than males, which could partially be a product of differential responses to semi-isolation. In addition, a single dose of exogenous CORT resulted in different blood profiles between the sexes over time, though exogenous CORT was cleared from blood within 90 min following treatment in both sexes. Interestingly, exposure to multiple doses of exogenous CORT resulted in elevated CORT levels 24 h after treatment in both sexes. These results highlight the need for further investigations into potential sex differences in hormone metabolism, as well as possible cumulative effects of repeated stress.     

Two seconds is all it takes: European starlings (Sturnus vulgaris) increase levels of circulating glucocorticoids after witnessing a brief raptor attack

Researchers typically study “acute” activation of the hypothalamic–pituitary–adrenal (HPA) axis by measuring levels of circulating glucocorticoids in animals that have been exposed to a predator or a cue from a predator (e.g., odor), or have experienced a standardized capture-and-restraint protocol, all of which are many minutes in duration. However, exposure to predators in the “wild”, either as the subject of an attack or as a witness to an attack, is generally much shorter as most depredation attempts upon free-living animals last < 5 s. Yet, whether a stimulus lasting only seconds can activate the HPA axis is unknown. To determine if a stimulus of a few seconds triggers a glucocorticoid response, we measured levels of corticosterone (CORT; the primary avian glucocorticoid) in wild-caught European starlings (Sturnus vulgaris) after they witnessed a brief (< 2–8 s) raptor attack upon a conspecific, a human “attack” (i.e., a researcher handling a conspecific), and an undisturbed control. Witnesses of a raptor attack responded with CORT levels comparable to that induced by a standardized capture-and-restraint protocol. Glucocorticoid levels of individuals following the control treatment were similar to baseline levels, and those that witnessed a human “attack” had intermediate levels. Our results demonstrate that witnessing a predator attack of very brief duration triggers a profound adrenocortical stress response. Given the considerable evidence of a role for glucocorticoids in learning and memory, such a response may affect how individuals learn to recognize and appropriately react to predators.