Catch crop strategy and nitrate leaching following grazed grass-clover

Cultivation of grassland presents a high risk of nitrate leaching. This study aimed to determine if leaching could be reduced by growing spring barley (Hordeum vulgare L.) as a green crop for silage with undersown Italian ryegrass (Lolium multiflorum Lam.) compared with barley grown to maturity with or without an undersown conventional catch crop of perennial ryegrass (Lolium perenne L.). All treatments received 0,60 or 120 kg of ammonium-N ha-1 in cattle slurry. In spring 2003, two grass-clover fields (3 and 5 years old, respectively, with different management histories) were ploughed. The effects of the treatments on yield and nitrate leaching were determined in the first year, while the residual effects of the treatments were determined in the second year in a crop of spring barley⁄perennial ryegrass. Nitrate leaching was estimated in selected treatments using soil water samples from ceramic cups. The experiment showed that compared with treatments without catch crop, green barley⁄Italian ryegrass reduced leaching by 163–320 kg Nha-1, corresponding to 95–99%, and the perennial ryegrass reduced leaching to between 34 and 86 kg Nha-1, corresponding to a reduction of 80 and 66%. Also, in the second growing season, leaching following catchcrops was reduced compared with the bare soil treatment. It was concluded that the green barley⁄Italian ryegrass offers advantages not only for the environment but also for farmers, for whom it provides a fodder high in roughage and avoids the difficulties with clover fatigue increasingly experienced by Danish farmers

11 beta-hydroxysteroid dehydrogenase type 1 regulates glucocorticoid-induced insulin resistance in skeletal muscle

OBJECTIVE: Glucocorticoid excess is characterized by increased adiposity, skeletal myopathy, and insulin resistance, but the precise molecular mechanisms are unknown. Within skeletal muscle, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts cortisone (11-dehydrocorticosterone in rodents) to active cortisol (corticosterone in rodents). We aimed to determine the mechanisms underpinning glucocorticoid-induced insulin resistance in skeletal muscle and indentify how 11beta-HSD1 inhibitors improve insulin sensitivity. \ud RESEARCH DESIGN AND METHODS: Rodent and human cell cultures, whole-tissue explants, and animal models were used to determine the impact of glucocorticoids and selective 11beta-HSD1 inhibition upon insulin signaling and action. \ud RESULTS: Dexamethasone decreased insulin-stimulated glucose uptake, decreased IRS1 mRNA and protein expression, and increased inactivating pSer$^{307}$ insulin receptor substrate (IRS)-1. 11beta-HSD1 activity and expression were observed in human and rodent myotubes and muscle explants. Activity was predominantly oxo-reductase, generating active glucocorticoid. A1 (selective 11beta-HSD1 inhibitor) abolished enzyme activity and blocked the increase in pSer$^{307}$ IRS1 and reduction in total IRS1 protein after treatment with 11DHC but not corticosterone. In C57Bl6/J mice, the selective 11beta-HSD1 inhibitor, A2, decreased fasting blood glucose levels and improved insulin sensitivity. In KK mice treated with A2, skeletal muscle pSer$^{307}$ IRS1 decreased and pThr$^{308}$ Akt/PKB increased. In addition, A2 decreased both lipogenic and lipolytic gene expression.\ud CONCLUSIONS: Prereceptor facilitation of glucocorticoid action via 11beta-HSD1 increases pSer$^{307}$ IRS1 and may be crucial in mediating insulin resistance in skeletal muscle. Selective 11beta-HSD1 inhibition decreases pSer$^{307}$ IRS1, increases pThr$^{308}$ Akt/PKB, and decreases lipogenic and lipolytic gene expression that may represent an important mechanism underpinning their insulin-sensitizing action

Antegrade pressure measurement as a diagnostic tool in modern pediatric urology

The antegrade pressure measurement (APM) or perfusion pressure-flow test (Whitaker test) is a method of antegrade measurement of pressure in the upper urinary tract. In this study, we present the long-term follow-up results of APMs performed in our institution in the late 1980s and early 1990s to see whether the diagnostic decisions that were based on the outcomes of the test prove to be correct in the long term. We conducted a retrospective study by searching our hospital's electronic database. We found a total of 16 APMs performed between 1987 and 1995 (10 boys, six girls; mean age 61 months). In nine cases, action was undertaken immediately after the APM had been performed; in seven cases, this was a surgical procedure (re-implantation/re-calibration or pyeloplasty) after obstruction was demonstrated. In two cases (both postoperative after previous pyeloplasty), absence of obstruction was demonstrated and nephrostomy tubes were subsequently closed. In one case, this resulted in hydronephrosis that had to be treated with a new JJ stent. In all the seven cases in which no action was deemed necessary as a result of the outcome of the APM, long-term follow-up showed that intervention had indeed not been necessary. Although not often used anymore, the APM seems to be a safe and valuable diagnostic tool in the work up for possible urinary tract obstruction in children, especially in cases in which there is serious doubt concerning conservative watchful waitin

Saturation Diving Alters Folate Status and Biomarkers of DNA Damage and Repair

Exposure to oxygen-rich environments can lead to oxidative damage, increased body iron stores, and changes in status of some vitamins, including folate. Assessing the type of oxidative damage in these environments and determining its relationships with changes in folate status are important for defining nutrient requirements and designing countermeasures to mitigate these effects. Responses of humans to oxidative stressors were examined in participants undergoing a saturation dive in an environment with increased partial pressure of oxygen, a NASA Extreme Environment Mission Operations mission. Six participants completed a 13-d saturation dive in a habitat 19 m below the ocean surface near Key Largo, FL. Fasting blood samples were collected before, twice during, and twice after the dive and analyzed for biochemical markers of iron status, oxidative damage, and vitamin status. Body iron stores and ferritin increased during the dive (P<0.001), with a concomitant decrease in RBC folate (P<0.001) and superoxide dismutase activity (P<0.001). Folate status was correlated with serum ferritin (Pearson r = −0.34, P<0.05). Peripheral blood mononuclear cell poly(ADP-ribose) increased during the dive and the increase was significant by the end of the dive (P<0.001); γ-H2AX did not change during the mission. Together, the data provide evidence that when body iron stores were elevated in a hyperoxic environment, a DNA damage repair response occurred in peripheral blood mononuclear cells, but double-stranded DNA damage did not. In addition, folate status decreases quickly in this environment, and this study provides evidence that folate requirements may be greater when body iron stores and DNA damage repair responses are elevated

Regulation of Lipogenesis by Glucocorticoids and Insulin in Human Adipose Tissue

Patients with glucocorticoid (GC) excess, Cushing's syndrome, develop a classic phenotype characterized by central obesity and insulin resistance. GCs are known to increase the release of fatty acids from adipose, by stimulating lipolysis, however, the impact of GCs on the processes that regulate lipid accumulation has not been explored. Intracellular levels of active GC are dependent upon the activity of 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) and we have hypothesized that 11β-HSD1 activity can regulate lipid homeostasis in human adipose tissue (Chub-S7 cell line and primary cultures of human subcutaneous (sc) and omental (om) adipocytes. Across adipocyte differentiation, lipogenesis increased whilst β-oxidation decreased. GC treatment decreased lipogenesis but did not alter rates of β-oxidation in Chub-S7 cells, whilst insulin increased lipogenesis in all adipocyte cell models. Low dose Dexamethasone pre-treatment (5 nM) of Chub-S7 cells augmented the ability of insulin to stimulate lipogenesis and there was no evidence of adipose tissue insulin resistance in primary sc cells. Both cortisol and cortisone decreased lipogenesis; selective 11β-HSD1 inhibition completely abolished cortisone-mediated repression of lipogenesis. GCs have potent actions upon lipid homeostasis and these effects are dependent upon interactions with insulin. These in vitro data suggest that manipulation of GC availability through selective 11β-HSD1 inhibition modifies lipid homeostasis in human adipocytes

Optimising sampling and analysis protocols in environmental DNA studies

Ecological surveys risk incurring false negative and false positive detections of the target species. With indirect survey methods, such as environmental DNA, such error can occur at two stages: sample collection and laboratory analysis. Here we analyse a large qPCR based eDNA data set using two occupancy models, one of which accounts for false positive error by Griffin et al. (2020), and a second that assumes no false positive error by Stratton et al. (2020). Additionally, we apply the Griffin et al. (2020) model to simulated data to determine optimal levels of replication at both sampling stages. The Stratton et al. (2020) model, which assumes no false positive results, consistently overestimated both overall and individual site occupancy compared to both the Griffin et al. (2020) model and to previous estimates of pond occupancy for the target species. The inclusion of replication at both stages of eDNA analysis (sample collection and in the laboratory) reduces both bias and credible interval width in estimates of both occupancy and detectability. Even the collection of >1 sample from a site can improve parameter estimates more than having a high number of replicates only within the laboratory analysis

Cross Adaptation - Heat and Cold Adaptation to Improve Physiological and Cellular Responses to Hypoxia

To prepare for extremes of heat, cold or low partial pressures of O2, humans can undertake a period of acclimation or acclimatization to induce environment specific adaptations e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. Whilst these strategies are effective, they are not always feasible, due to logistical impracticalities. Cross adaptation is a term used to describe the phenomenon whereby alternative environmental interventions e.g. HA, or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude. HA can attenuate physiological strain at rest and during moderate intensity exercise at altitude via adaptations allied to improved oxygen delivery to metabolically active tissue, likely following increases in plasma volume and reductions in body temperature. CA appears to improve physiological responses to altitude by attenuating the autonomic response to altitude. While no cross acclimation-derived exercise performance/capacity data have been measured following CA, post-HA improvements in performance underpinned by aerobic metabolism, and therefore dependent on oxygen delivery at altitude, are likely. At a cellular level, heat shock protein responses to altitude are attenuated by prior HA suggesting that an attenuation of the cellular stress response and therefore a reduced disruption to homeostasis at altitude has occurred. This process is known as cross tolerance. The effects of CA on markers of cross tolerance is an area requiring further investigation. Because much of the evidence relating to cross adaptation to altitude has examined the benefits at moderate to high altitudes, future research examining responses at lower altitudes should be conducted given that these environments are more frequently visited by athletes and workers. Mechanistic work to identify the specific physiological and cellular pathways responsible for cross adaptation between heat and altitude, and between cold and altitude, is warranted, as is exploration of benefits across different populations and physical activity profiles