Long-term river invertebrate community responses to groundwater and surface water management operations.

River flow regimes have been transformed by groundwater and surface water management operations globally, prompting widespread ecological responses. Yet, empirical evidence quantifying the simultaneous effects of groundwater and surface water management operations on freshwater ecosystems remains limited. This study combines a multi-decadal freshwater invertebrate dataset (1995-2016) with groundwater model outputs simulating the effects of different anthropogenic flow alterations (e.g. groundwater abstraction, effluent water returns) and river discharges. A suite of flow alteration- and flow-ecology relationships were modelled that tested different invertebrate community responses (taxonomic, functional, flow response guilds, individual taxa). Most flow alteration-ecology relationships were not statistically significant, highlighting the absence of consistent, detectable ecological responses to long-term water management operations. A small number of significant statistical models provided insights into how flow alterations transformed specific ecological assets; including Ephemeroptera, Plecoptera and Trichoptera taxa which are rheophilic in nature being positively associated with groundwater abstraction effects reducing river discharges by 0-15%. This represents a key finding from a water resource management operation perspective given that such flow alteration conditions were observed on average in over two-thirds of the study sites examined. In a small number of instances, specific invertebrate responses displayed relative declines associated with the most severe groundwater abstraction effects and artificial hydrological inputs (predominantly effluent water returns). The strongest flow-ecology relationships were recorded during spring months, when invertebrate communities were most responsive to antecedent minimum and maximum discharges, and average flow conditions in the preceding summer months. Results from this study provide new evidence indicating how groundwater and surface water resources can be managed to conserve riverine ecological assets. Moreover, the ensemble of flow alteration- and flow-ecology relationships established in this study could be used to guide environmental flow strategies. Such findings are of global importance given that future climatic change and rising societal water demands are likely to further transform river flow regimes and threaten freshwater ecosystems.

Macroinvertebrate Taxonomic and Functional Trait Compositions within Lotic Habitats Affected By River Restoration Practices.

The widespread degradation of lotic ecosystems has prompted extensive river restoration efforts globally, but many studies have reported modest ecological responses to rehabilitation practices. The functional properties of biotic communities are rarely examined within post-project appraisals, which would provide more ecological information underpinning ecosystem responses to restoration practices and potentially pinpoint project limitations. This study examines macroinvertebrate community responses to three projects which aimed to physically restore channel morphologies. Taxonomic and functional trait compositions supported by widely occurring lotic habitats (biotopes) were examined across paired restored and non-restored (control) reaches. The multivariate location (average community composition) of taxonomic and functional trait compositions differed marginally between control and restored reaches. However, changes in the amount of multivariate dispersion were more robust and indicated greater ecological heterogeneity within restored reaches, particularly when considering functional trait compositions. Organic biotopes (macrophyte stands and macroalgae) occurred widely across all study sites and supported a high alpha (within-habitat) taxonomic diversity compared to mineralogical biotopes (sand and gravel patches), which were characteristic of restored reaches. However, mineralogical biotopes possessed a higher beta (between-habitat) functional diversity, although this was less pronounced for taxonomic compositions. This study demonstrates that examining the functional and structural properties of taxa across distinct biotopes can provide a greater understanding of biotic responses to river restoration works. Such information could be used to better understand the ecological implications of rehabilitation practices and guide more effective management strategies.

When is the best time to sample aquatic macroinvertebrates in ponds for biodiversity assessment?

Ponds are sites of high biodiversity and conservation value, yet there is little or no statutory monitoring of them across most of Europe. There are clear and standardised protocols for sampling aquatic macroinvertebrate communities in ponds, but the most suitable time(s) to undertake the survey(s) remains poorly specified. This paper examined the aquatic macroinvertebrate communities from 95 ponds within different land use types over three seasons (spring, summer and autumn) to determine the most appropriate time to undertake sampling to characterise biodiversity. The combined samples from all three seasons provided the most comprehensive record of the aquatic macroinvertebrate taxa recorded within ponds (alpha and gamma diversity). Samples collected during the autumn survey yielded significantly greater macroinvertebrate richness (76% of the total diversity) than either spring or summer surveys. Macroinvertebrate diversity was greatest during autumn in meadow and agricultural ponds, but taxon richness among forest and urban ponds did not differ significantly temporally. The autumn survey provided the highest measures of richness for Coleoptera, Hemiptera and Odonata. However, richness of the aquatic insect order Trichoptera was highest in spring and lowest in autumn. The results illustrate that multiple surveys, covering more than one season, provide the most comprehensive representation of macroinvertebrate biodiversity. When sampling can only be undertaken on one occasion, the most appropriate time to undertake surveys to characterise the macroinvertebrate community biodiversity is during autumn, although this may need to be modified if other floral and faunal groups need to be incorporated into the sampling programme.

Changes in macroinvertebrate community structure provide evidence of neutral mine drainage impacts.

Contamination of aquatic environments as a consequence of metal mining is an international issue. Most historic studies have considered the impact of acid mine drainage (pH < 6) on instream communities and comparatively little attention has been given to sites where drainage is typically circum-neutral (6 > pH < 8). Here, the impacts of historic mining activities on the benthic macroinvertebrate community of a circum-neutral river in Central Wales are assessed. Biotic and diversity indices, widely used for biomonitoring purposes, indicate aquatic macroinvertebrate assemblages within the Afon Twymyn to be in a good condition, despite severe metal contamination of bed sediments and river water. However, Canonical Correspondence Analysis identifies differences in community structure between mining impacted and unimpacted reaches of the river associated with chalcophile (Zn, Pb, Cu, Cd) and common (Fe and Mn) metals. Stream pH was not a significant factor structuring the macroinvertebrate community. Widely utilised macroinvertebrate indices failed to identify impacts at the community level because they either seek to identify impacts of a specific contaminant or are dependent on a model community response to a given stress. The nature of metal mine discharges is temporally complex, having highly variable chemical signatures and as a result, care is advised when interpreting and modelling community impacts. The use of standard macroinvertebrate biotic and diversity indices in the context of the EU Water Framework Directive could lead to erroneous classifications of aquatic ecosystem health when used for bio-monitoring rivers affected by neutral mine drainage where other indicators are unavailable.

Evidence needed to manage freshwater ecosystems in a changing climate: turning adaptation principles into practice.

It is widely accepted that climate change poses severe threats to freshwater ecosystems. Here we examine the scientific basis for adaptively managing vulnerable habitats and species. Our views are shaped by a literature survey of adaptation in practice, and by expert opinion. We assert that adaptation planning is constrained by uncertainty about evolving climatic and non-climatic pressures, by difficulties in predicting species- and ecosystem-level responses to these forces, and by the plasticity of management goals. This implies that adaptation measures will have greatest acceptance when they deliver multiple benefits, including, but not limited to, the amelioration of climate impacts. We suggest that many principles for biodiversity management under climate change are intuitively correct but hard to apply in practice. This view is tested using two commonly assumed doctrines: "increase shading of vulnerable reaches through tree planting" (to reduce water temperatures); and "set hands off flows" (to halt potentially harmful abstractions during low flow episodes). We show that the value of riparian trees for shading, water cooling and other functions is partially understood, but extension of this knowledge to water temperature management is so far lacking. Likewise, there is a long history of environmental flow assessment for allocating water to competing uses, but more research is needed into the effectiveness of ecological objectives based on target flows. We therefore advocate more multi-disciplinary field and model experimentation to test the cost-effectiveness and efficacy of adaptation measures applied at different scales. In particular, there is a need for a major collaborative programme to: examine natural adaptation to climatic variation in freshwater species; identify where existing environmental practice may be insufficient; review the fitness of monitoring networks to detect change; translate existing knowledge into guidance; and implement best practice within existing regulatory frameworks.

Cortisol clearance and associations with insulin sensitivity, body fat and fatty liver in middle-aged men.

AIMS/HYPOTHESIS: The regulation of cortisol metabolism in vivo is not well understood. We evaluated the relationship between cortisol metabolism and insulin sensitivity, adjusting for total and regional fat content and for non-alcoholic fatty liver disease. MATERIALS AND METHODS: Twenty-nine middle-aged healthy men with a wide range of BMI were recruited. We measured fat content by dual-energy X-ray absorptiometry and magnetic resonance imaging (MRI), liver fat by ultrasound and MRI, the hypothalamic-pituitary-adrenal axis by adrenal response to ACTH(1-24), unconjugated urinary cortisol excretion, corticosteroid-binding globulin, and cortisol clearance by MS. We assessed insulin sensitivity by hyperinsulinaemic-euglycaemic clamp and by OGTT. RESULTS: Cortisol clearance was strongly inversely correlated with insulin sensitivity (M value) (r = -0.61, p = 0.002). Cortisol clearance was increased in people with fatty liver compared with those without (mean+/-SD: 243 +/- 10 vs 158 +/- 36 ml/min; p = 0.014). Multiple regression modelling showed that the relationship between cortisol clearance and insulin sensitivity was independent of body fat. The relationship between fatty liver and insulin sensitivity was significantly influenced by body fat and cortisol clearance. CONCLUSIONS/INTERPRETATION: Cortisol clearance is strongly associated with insulin sensitivity, independently of the amount of body fat. The relationship between fatty liver and insulin sensitivity is mediated in part by both fatness and cortisol clearance.

Non-esterified fatty acid concentrations are independently associated with hepatic steatosis in obese subjects.

AIMS/HYPOTHESIS: We tested the hypothesis that NEFA concentrations are higher in obese subjects with fatty liver than in obese subjects without fatty liver. MATERIALS AND METHODS: We recruited 22 obese (BMI>30 kg/m(2)) men aged 42-64 years, in whom liver fat was assessed by ultrasound and classified into categories of no, mild to moderate and severe fatty liver by two independent radiologists. Regional and visceral abdominal fat were assessed by dual-energy X-ray absorptiometry and magnetic resonance imaging, and endogenous glucose production, whole-body glucose disposal during an insulin clamp, and NEFA concentrations were measured, along with NEFA suppression (percent (%) suppression and insulin sensitivity index for NEFA during an OGTT). RESULTS: Seven subjects had no evidence of fatty liver, nine had mild or moderate fatty liver and six had severe fatty liver. The amount of visceral fat was not associated with the degree of fatty liver. Whole-body glucose disposal was inversely associated with fatty liver (38.4, 26.5 and 23.9 mumol kg(-1) min(-1) for the groups with no fatty liver, mild to moderate fatty liver and severe fatty liver, respectively, p=0.004). NEFA suppression during the OGTT was decreased (62.5, 50.8 and 41%, p=0.03, for no, mild to moderate, and severe fatty liver, respectively) and the insulin sensitivity index for NEFA was decreased (0.80, 0.40 and 0.34, p<0.0001). Regression modelling suggested that NEFA concentrations were associated with fatty liver independently of whole-body glucose production and disposal measurements. CONCLUSIONS/INTERPRETATION: In obese men, NEFA concentrations during an OGTT are associated with fatty liver independently of classic measures of insulin sensitivity determined by the hyperinsulinaemic clamp. The contribution to this association by factors regulating NEFA concentrations requires further study.

Exposure of the fetus and infant to hens' egg ovalbumin via the placenta and breast milk in relation to maternal intake of dietary egg.

BACKGROUND: Maternally derived allergens may be transferred to the developing infant during pregnancy and lactation. However, it is not known how manipulation of environmental allergen levels might impact on this early-life exposure. OBJECTIVE: To measure dietary egg allergen (ovalbumin (OVA)) in gestation-associated environments, in relation to maternal dietary egg intake. METHOD: OVA was measured by allergen-specific ELISA in maternal blood collected throughout pregnancy, infant blood at birth (umbilical cord) and in breast milk at 3 months post-partum. Samples derived from pregnant women undergoing diagnostic amniocentesis at 16-18 weeks gestation who were not subject to any dietary intervention, and from pregnant women, with personal or partner atopy, randomized to complete dietary egg exclusion or an unmodified healthy diet before 20 weeks gestation as a primary allergy prevention strategy. Maternal dietary egg intake was monitored closely throughout the study period by diary record and serial measurement of OVA-specific immunoglobulin G concentration. RESULTS: Circulating OVA was detected throughout pregnancy in 20% of women and correlated with both presence (P<0.001) and concentration (r=0.754, P<0.001) of infant OVA at birth (umbilical cord). At 3 months post-partum OVA was detected in breast milk samples of 35% women, in higher concentrations than measured in blood. Blood and breast milk OVA were not related to maternal dietary intake or atopic pre-disposition. CONCLUSIONS: Rigorous dietary egg exclusion does not eliminate trans-placental and breast milk egg allergen passage. This early-life exposure could modulate developing immune responses.

Investigating the role of the growth hormone-insulin-like growth factor (GH-IGF) axis as a determinant of male bone mineral density (BMD).

INTRODUCTION: The GH-IGF axis has profound effects on bone metabolism and may be important in the etiology of idiopathic osteoporosis. Serum IGF-I is often low in men with osteoporosis, which may be attributable to GH hypo-secretion or hepatic GH insensitivity. We studied the GH-IGF axis in depth to look for evidence to support these hypotheses. MATERIALS AND METHODS: 28 healthy 60- to 70-year-old men with low, intermediate, or normal BMD were studied. GH secretion was measured by overnight urine collection. GH reserve was assessed by exercise and glucagon stimulation tests. Hepatic IGF-I production was investigated using a GH-IGF-I generation test. Data were analyzed using Pearson's correlation coefficient, linear regression, and analysis of variance. RESULTS: Serum IGF-I was reduced in subjects with low BMD (P = 0.009). There was no difference in GH secretion or reserve between the groups. Overall, GH reserve and IGF-I were positively related but this was attenuated in the low BMD group. However, no statistically significant difference in IGF-I generation capacity between BMD groups was found. CONCLUSIONS: Men with reduced BMD have low IGF-I but normal GH secretion and reserve. Our data suggested, but could not confirm, hepatic resistance to GH as a mechanism for this association.

Cortisol secretion and rate of bone loss in a population-based cohort of elderly men and women.

Although excessive glucocorticoids are a well-recognized cause of osteoporosis, little is known about the role of endogenous glucocorticoids in determining skeletal mass. We have performed a detailed study of the hypothalamic-pituitary-adrenal (HPA) axis to explore the relationships between cortisol secretion and adult bone mass in 151 healthy men and 96 healthy women aged 61 to 73 years. At baseline and 4-year follow-up, bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at the lumbar spine and proximal femur; a lifestyle questionnaire was completed; and height, weight, and waist and hip circumferences were measured. At follow-up subjects underwent a very low-dose (0.25 mg) dexamethasone suppression test, a low-dose (1 microg) short synacthen test, and a 24-hour urine collection for measurement of cortisol and its metabolites. In men, elevated peak plasma cortisol was associated with accelerated loss of mineral density in the lumbar spine (r = 0.16, P = 0.05). This relationship remained significant after adjustment for testosterone, estradiol, 25-hydroxyvitamin D, and parathyroid hormone levels (r = 0.22, P = 0.01) and after additional adjustment for age, (BM), activity, cigarette and alcohol consumption, and Kellgren/Lawrence score (r = 0.19, P = 0.03). In contrast in women, elevated peak plasma cortisol was associated with lower baseline BMD at the femoral neck (r = -0.23, P = 0.03) and greater femoral neck loss rate (r = 0.24, P = 0.02). There was no association between plasma cortisol concentrations after dexamethasone or urinary total cortisol metabolite excretion and bone density or bone loss rate at any site. These data provide evidence that circulating endogenous glucocorticoids influence the rate of involutional bone loss in healthy individuals.

Diurnal patterns of salivary cortisol and cortisone output in chronic fatigue syndrome.

BACKGROUND: The aim of the present study was to obtain a naturalistic measure of diurnal hypothalamic-pituitary-adrenal (HPA) axis output in CFS patients unaffected by medication or comorbid psychiatric disorder likely to influence the axis. METHOD: Cortisol and cortisone levels were measured in saliva samples collected from 0600 h to 2100 h at 3-h intervals in CFS patients and healthy controls. RESULTS: Mean cortisol and cortisone concentrations were significantly lower in patients than controls across the whole day, as were levels at each individual time point except 2100 h. Cosinor analysis showed a significant diurnal rhythm of cortisol and cortisone that was not phase-shifted in CFS compared to controls. However, there was a lower rhythm-adjusted mean and a lower amplitude in CFS patients. The cortisol/cortisone ratio showed no diurnal rhythm and did not differ between CFS subjects and controls. LIMITATIONS: The sample size was relatively small, and drawn from specialist referral patients who had been ill for some time; generalisation of these results to other populations is therefore unwarranted. CONCLUSION: The main findings of this study are to provide further evidence for reduced basal HPA axis function in at least some patients with CFS and to show for the first time that salivary cortisone is also reduced in CFS and has a diurnal rhythm similar to that of cortisol. We have also demonstrated that the cortisol/cortisone ratio remains unchanged in CFS, suggesting that increased conversion of cortisol to cortisone cannot account for the observed lowering of salivary cortisol.

The utility of three different methods for measuring urinary 18-hydroxycortisol in the differential diagnosis of suspected primary hyperaldosteronism.

OBJECTIVE: Urine 18-hydroxycortisol (18-OHF) measurements are claimed to discriminate between primary hyperaldosteronism due to Conn's syndrome/adrenal adenoma or idiopathic bilateral adrenal hyperplasia (BAH), and also to identify cases of glucocorticoid-suppressible hyperaldosteronism (GSH). We have evaluated three urine 18-OHF methods using a panel of urine samples from patients with hypertension. DESIGN: Clinical methods comparative study. METHODS: Urine samples from patients with primary hyperaldosteronism due to either adenoma (n = 6), BAH (n = 6), GSH (n = 9), or essential hypertension (n = 38) were analysed without knowledge of the diagnosis using three different methods in different laboratories. These included 'in-house' radioimmunoassay (RIA), 'in-house' time-resolved fluorometric assay (DELFIA), and gas chromatography mass spectrometry (GC-MS). RESULTS: The three assays showed good correlation, but there were large bias differences: RIA bias was greater than DELFIA which was greater than GC-MS. Discrimination between adenoma and BAH patients was best for the DELFIA method, with no overlap between results for these two groups. All three methods gave significantly elevated results for the GSH group compared with the BAH and essential hypertension groups. No assay distinguished BAH from essential hypertension. CONCLUSION: Measurement of urine 18-OHF may be a useful additional test in the differential diagnosis of primary hyperaldosteronism. The clinical diagnostic value of urinary 18-OHF measurements is method-dependent with the DELFIA assay having the best discriminatory value.

11beta-hydroxysteroid dehydrogenase type 1 activity in lean and obese males with type 2 diabetes mellitus.

Glucocorticoids play an important role in the pathogenesis of obesity and insulin resistance. Impaired conversion of cortisone (E) to cortisol (F) by the type 1 isoenzyme of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) in obesity may represent a protective mechanism preventing ongoing weight gain and glucose intolerance. We have studied glucocorticoid metabolism in 33 male subjects with type 2 diabetes mellitus [age, 44.2 +/- 13 yr; body mass index (BMI), 31.1 +/- 7.5 kg/m(2) (mean +/- sd)] and 38 normal controls (age, 41.4 +/- 14 yr; BMI, 38.2 +/- 12.8 kg/m(2)). Circulating F:E ratios were elevated in the diabetic group and correlated with serum cholesterol and homeostasis model assessment-S. There was no difference in 11beta-HSD1 activity between diabetic subjects and controls. In addition, 11beta-HSD1 activity was unaffected by BMI in diabetic subjects. However, in control subjects, increasing BMI was associated with a reduction in the urinary tetrahydrocortisol+5alpha-tetrahydrocortisol:tetrahydrocortisone ratio (P < 0.05) indicative of impaired 11beta-HSD1 activity. The degree of inhibition correlated tightly with visceral fat mass. Changes in 11beta-HSD1 activity could not be explained by circulating levels of adipocytokines. Impaired E to F metabolism in obesity may help preserve insulin sensitivity and prevent diabetes mellitus. Failure to down-regulate 11beta-HSD1 activity in patients with diabetes may potentiate dyslipidemia, insulin resistance, and obesity. Inhibition of 11beta-HSD1 may therefore represent a therapeutic strategy in patients with type 2 diabetes mellitus and obesity.

Alterations in placental 11 beta-hydroxysteroid dehydrogenase (11 betaHSD) activities and fetal cortisol:cortisone ratios induced by nutritional restriction prior to conception and at defined stages of gestation in ewes.

In the placenta, cortisol is inactivated by NADP(+)- and NAD(+)-dependent isoforms of 11beta-hydroxysteroid dehydrogenase (11betaHSD). Decreased placental 11betaHSD activities have been implicated in intrauterine growth restriction (IUGR) and fetal programming of adult diseases. The objective of this study was to investigate whether placental 11betaHSD activities and fetal plasma cortisol:cortisone ratios could be affected by nutritional restriction of ewes (70% maintenance diet) throughout gestation, for specific stages of gestation, or prior to mating. Chronic nutritional restriction from day 26 of gestation onwards decreased NAD(+)-dependent 11betaHSD activities by 52 +/- 4% and 45 +/- 6% on days 90 and 135 of gestation respectively. Although the decreases in enzyme activities were associated with fetal IUGR, the cortisol:cortisone ratio in fetal plasma was unaffected by chronic nutritional restriction throughout pregnancy. Nutritional restriction confined to early (days 26-45), mid- (days 46-90) and late gestation (days 91-135), or the 30 days prior to mating, had no significant effect on NAD(+)-dependent, placental 11betaHSD activities, nor was there evidence of IUGR. However, nutritional restriction at each stage of pregnancy and prior to mating was associated with significant decreases in the fetal plasma cortisol:cortisone ratio (3.2 +/- 0.7 in control fetuses; 1.0 to 1.6 in fetuses carried by nutritionally restricted ewes). We conclude that nutritional restriction of pregnant ewes for more than 45 consecutive days can significantly decrease NAD(+)-dependent placental 11betaHSD activities in association with IUGR. While the cortisol:cortisone ratio in fetal plasma is sensitive to relatively acute restriction of nutrient intake, even prior to mating, this ratio does not reflect direct ex vivo measurements of placental 11betaHSD activities.

Serum insulin-like growth factor-I concentrations in late middle age: no association with birthweight in three UK cohorts.

BACKGROUND: Small body size at birth and during infancy is associated with an increased risk of adult osteoporosis and cardiovascular disease. Fetal programming of the growth hormone-insulin-like growth factor (GH-IGF) axis may provide a mechanism for these epidemiological findings. AIMS: To determine whether measurements of GH and IGF-I in late middle age were related to size at birth and in infancy. METHODS: Overnight urinary GH excretion and fasting serum IGF-I were measured in 309 men and 193 women from Hertfordshire (born 1920-1930) for whom birthweight and weight at 1 year were recorded. Serum IGF-I was measured in men and women from Preston (n=254, born 1935-1943) and Sheffield (n=215, born 1939-1940) whose birthweight and other birth measurements were recorded. RESULTS: Urinary GH and serum IGF-I were not related to birthweight, other measurements at birth, or weight at 1 year. CONCLUSION: In contrast to previous studies in children or young adults, these data do not support the hypothesis that IGF-I concentrations are programmed by intra-uterine events, as assessed by birthweight, in late middle age.

The effects of growth hormone deficiency and replacement on glucocorticoid exposure in hypopituitary patients on cortisone acetate and hydrocortisone replacement.

OBJECTIVE: 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta HSD1) converts inactive cortisone to active cortisol. 11 beta HSD1 activity is increased in GH deficiency and inhibited by GH and IGF-I in acromegaly. However it is not known whether these changes in cortisol metabolism exert significant effects during hydrocortisone therapy, and the effect has not been studied in patients taking cortisone acetate. We have studied the effect of GH induced 11 beta HSD1 inhibition in hypopituitary adults with severe GH deficiency to determine whether this inhibition has a different magnitude of effect when patients are taking different forms of glucocorticoid replacement therapy. DESIGN, PATIENTS AND MEASUREMENTS: We have taken the ratio of 11-hydroxy/11-oxo cortisol metabolites (Fm/Em), an established measure of net 11 beta HSD activity to reflect the likely balance of cortisol to cortisone exposure in tissues expressing 11 beta HSD1, principally the liver and adipose tissue. We recruited 10 hypopituitary adults all on established glucocorticoid replacement therapy, but who were not receiving GH. Patients were treated with their standard hydrocortisone therapy for one week and an equivalent dose of cortisone acetate in its place for one week in random order. Serial serum cortisol assessments and urine steroid profiles were performed on each treatment. All patients were then established on GH therapy for at least three months before the two-week cycle was repeated. Fm/Em was also measured in a control population (20F, 20M). RESULTS: Prior to GH, the ratio Fm/Em was greater with hydrocortisone compared with cortisone acetate replacement (1.17 +/- 0.28 and 0.52 +/- 0.09 respectively, P < 0.001) or with normal subjects (normal males: 0.81 +/- 0.24, females 0.66 +/- 0.14). Following GH replacement Fm/Em fell in patients on hydrocortisone and cortisone acetate (Pre-GH: 0.84 +/- 0.40, Post-GH: 0.70 +/- 0.34, P < 0.05) confirming the inhibition of 11 beta HSD1 by GH/IGF-I. Conversely, the ratio of urinary free cortisol/cortisone did not change indicating unchanged 11 beta HSD2 activity. Mean circulating cortisol also fell in all subjects after GH. This effect was greater during cortisone acetate treatment (-18.7%, P < 0.0001), than during hydrocortisone replacement (-10.9%, P < 0.05). CONCLUSIONS: Our data suggest that tissue exposure to glucocorticoid is supra-physiological in hypopituitary patients with untreated GH deficiency taking hydrocortisone replacement therapy. This situation is ameliorated by GH replacement therapy. However, local and circulating cortisol concentrations are more vulnerable to the inhibitory effect of GH on 11 beta HSD1 in patients taking cortisone acetate, such that serum cortisol assessments should be made in patients taking cortisone acetate after GH therapy to ensure that glucocorticoid replacement remains adequate.

Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 lowers intraocular pressure in patients with ocular hypertension.

BACKGROUND: Intraocular pressure (IOP) is maintained by a balance between aqueous humour (AH) production (dependent on sodium transport across a ciliary epithelial bi-layer) and drainage (predominantly through the trabecular meshwork). In peripheral epithelial tissues, sodium and water transport is regulated by corticosteroids and the 11beta-hydroxysteroid dehydrogenase (11beta-HSD) isozymes (11beta-HSD1 activating cortisol from cortisone, 11beta-HSD2 inactivating cortisol to cortisone). AIM: To analyse expression of 11beta-HSD in the human eye and investigate its putative role in AH formation. DESIGN: Multipart prospective study, including a randomized controlled clinical trial. METHODS: The expression of 11beta-HSD1 in normal human anterior segments was evaluated by in situ hybridization (ISH). RT-PCR for 11beta-HSDs, glucocorticoid and mineralocorticoid receptors (GR, MR) was performed on human ciliary body tissue. AH cortisol and cortisone concentrations were measured by radioimmunoassay on specimens taken from patients with primary open-angle glaucoma (POAG) and age-matched controls. Randomized, placebo-controlled studies of healthy volunteers and patients with ocular hypertension (OHT, raised IOP but no optic neuropathy) assessed the effect of oral carbenoxolone (CBX, an inhibitor of 11beta-HSD) on IOP. RESULTS: ISH defined expression of 11beta-HSD1 in the ciliary epithelium, while RT-PCR analysis of ciliary body tissue confirmed expression of 11beta-HSD1, with additional GR and MR, but not 11beta-HSD2 expression. In both POAG patients and controls, AH concentrations of cortisol exceeded those of cortisone. The CBX-treated healthy volunteers who demonstrated the largest change in urinary cortisol metabolites, indicative of 11beta-HSD1 inhibition, had the greatest fall in IOP. Patients with OHT showed an overall reduction of IOP by 10% following CBX administration, compared to baseline (p<0.0001). DISCUSSION: CBX lowers IOP in patients with ocular hypertension. Our data suggest that this is mediated through inhibition of 11beta-HSD1 in the ciliary epithelium. Selective and topical inhibitors of 11beta-HSD1 could provide a novel treatment for patients with glaucoma.

Ovarian modulators of type 1 11beta-hydroxysteroid dehydrogenase (11betaHSD) activity and intra-follicular cortisol:cortisone ratios correlate with the clinical outcome of IVF.

BACKGROUND: Follicular fluid (FF) contains compounds that can modulate NADP(+)-dependent oxidation of cortisol by type 1 11beta-hydroxysteroid dehydrogenase (11betaHSD). The objective of this study was to investigate the relationships between levels of the ovarian modulators of type 1 11betaHSD, intra-follicular cortisol:cortisone ratios and the clinical outcome of IVF cycles. METHODS: A single random sample of FF was aspirated from each of 132 patients undergoing gonadotrophin-stimulated IVF. Components of FF, resolved using C18 column chromatography, were evaluated for effects on NADP(+)-dependent cortisol oxidation in rat kidney homogenates. Intra- follicular steroid concentrations were measured by radioimmunoassays. Clinical pregnancies were confirmed by ultrasonography at 6 weeks post-embryo transfer. RESULTS: Levels of the hydrophilic ovarian 11betaHSD stimuli were significantly lower (P<0.0001) and levels of the hydrophobic ovarian 11betaHSD inhibitors were significantly higher (P<0.002) in conception versus non-conception cycles. Intra-follicular cortisol:cortisone ratios increased with the degree of inhibition of 11betaHSD by the hydrophobic FF fractions. FF obtained from conception cycles had significantly higher cortisol:cortisone ratios than samples from non-conception cycles (12.9+/-0.3 versus 8.5+/-0.2, respectively; P<0.0001). CONCLUSIONS: Conception by IVF is associated with elevated intra-follicular cortisol:cortisone ratios, which reflect low levels of ovarian stimuli and/or high levels of ovarian inhibitors of type 1 11betaHSD.

Higher cortisol:cortisone ratios in the preovulatory follicle of completely unstimulated IVF cycles indicate oocytes with increased pregnancy potential.

BACKGROUND: Conception following gonadotrophin-stimulated IVF and embryo transfer has been associated with a higher intrafollicular cortisol:cortisone ratio and decreased metabolism of cortisol to cortisone. The role of glucocorticoids in human oocyte maturation is not fully understood, but active glucocorticoid (cortisol) may be important. This study relates intrafollicular cortisol and cortisone concentrations to oocyte fertilization and embryo implantation in unstimulated cycles. METHODS: Patients aged <40 years with favourable sperm underwent unstimulated IVF-embryo transfer. Study 1 related intrafollicular cortisol levels to oocyte and IVF outcome: (i) fertilized, pregnant (n = 9); (ii) fertilized, not pregnant (n = 21); and (iii) unfertilized (n = 12). Study 2 was a case-control study of 27 patients (same outcome groups of equal size) which measured intrafollicular cortisol, cortisone and the cortisol:cortisone ratio. RESULTS: Conception cycles demonstrated higher cortisol concentrations compared with the fertilized group (study 1) [median (95% confidence interval): 299 (249-330) versus 227 nmol/l (185-261); P < 0.05] and higher cortisol:cortisone ratios when compared with the unfertilized group (study 2) [7.38 (5.23-9.19) versus 3.56 (1.75-7.46) respectively; P = 0.02]. Of the women with cortisol:cortisone ratios greater than the outcome independent mean of 5.90, 58% conceived compared with only 13% with ratios <5.90 (P < 0.02). CONCLUSION: Higher cortisol:cortisone ratios in conception cycles suggest that active glucocorticoid may be important for final oocyte maturation and embryo implantation in unstimulated cycles.

The use of salt dilution gauging techniques: ecological considerations and insights.

The salt dilution (gulp injection) technique is a well established and widely used technique to measure stream discharge, flow velocity and water residence characteristics in small headwater streams. However, the impact of the technique on water quality and instream ecology has been largely ignored in field investigations. A series of experiments were undertaken in a regulated and groundwater-dominated river to examine the effects on aquatic invertebrate drift at high, medium and low discharges. In the groundwater-dominated river, drift significantly increased as a result of the introduction of the saline solution under all flows. Drift increased at the regulated site under low and intermediate flow but not during high flows, probably due to a natural increase in drift associated with spate conditions. Following the application of the saline solution several taxa absent or infrequently occurring in background samples, such as the cased caddisfly, Agapetus fuscipes, were recorded. The wider implications of the technique are discussed in relation to short-term pulsed pollution episodes and the management of riverine ecosystems.