Rise and fall: increasing temperatures have nonlinear effects on aggression in a tropical fish

Environmental conditions are fundamental drivers of animal behaviour. Aggression in ectotherms is a marked example and is often considered positively correlated with temperature. However, many studies exploring this relationship, and its important consequences, focus on a few temperatures and implicitly assume a linear relationship between the two variables. This may limit our understanding of the influence of temperature on aggression. We measured levels of aggression in Neolamprologus pulcher, a cichlid fish commonly used as a model in studies of aggression-based social hierarchy, across a range of temperatures in a mirror aggression test. We used temperatures expected from their natural range with a 2 °C extension on either end. As predicted by thermal performance curves, rates of aggression increased with temperature at the lower end of the temperature range. After reaching a peak, any further increase in temperature resulted in a considerable drop in rates of aggression. Exploring responses at a finer temporal scale, we found that the influence of high temperatures changed dramatically during the 25 min trials. Early in the trials the frequency of aggression increased linearly with temperature, across all temperatures. The initially high levels of aggression at the higher temperatures were not sustained and dropped with increasing duration of exposure to the mirror at high temperatures. Together these findings provide a more comprehensive understanding of the influence of short-term exposure to different temperatures on aggression, such as acute exposure to increased temperatures caused by global warming and associated rapid thermal fluctuations, in African rift lake fishes and in ectotherms more generally. Moreover, our results highlight the importance of measuring aggression across a range of temperatures or otherwise account for nonlinear changes in thermal performance

Effects of Sex and Whole Life Cycle UVB Irradiation on Performance and Mineral and Vitamin D3 Contents in Feeder Crickets (Gryllus bimaculatus)

Captive insectivore nutrition is challenging due to the differing nutritional profiles of wild and captive diets and an incomplete understanding of both. Ultraviolet B (UVB)-irradiation has recently been explored as a means of improving prey-insect vitamin D3 and Ca content. Although short-term irradiation has been successful in some species, it has been unsuccessful in black field crickets (Gryllus bimaculatus)—a commonly cultured feeder insect. We exposed crickets to UVB irradiation from hatchling to adult stages and measured the vitamin D3 and mineral contents of crickets by sex. We did not detect vitamin D3 (detection limit 0.5 iU/g) or an effect of UVB irradiation on mineral content under either UV+ or UV− conditions. We identified large differences between sexes in Ca, K, Mg and P (females higher) and Cu, Fe, S and Zn (males higher), likely linked to reproductive investment. The differences do not straddle the minimum recommended concentrations of minerals for vertebrate growth and thus may be most relevant to animal nutrition in contexts of particular sensitivity or need. We demonstrate a UV-linked trade-off in cricket performance between individual cricket size and the numbers of crickets produced and characterise the energy costs associated with UVB provision. Our results do not support the use of UVB lighting for G. bimaculatus to improve nutrition but demonstrate previously unreported differences in the nutritional profiles between sexes in this species

Failure to improve calcium content of earthworms (Dendrobaena veneta) through three methods of gut-loading

The diets provided to many captive insectivores are deficient in calcium and high in phosphorus, which can lead to nutritional disease. Husbandry professionals may address this imbalance through supplementation, but the efficacy of different methods varies between invertebrate taxa. Earthworms are frequently used for aquatic and fossorial insectivores and this along with their rapidly shed mucus layer makes dusting with supplements ineffective; gut loading is likely the only available route to improving nutritional quality. Moreover, earthworms are often considered a good source of calcium, though data exist only for some taxa and results are mixed with regards to calcium content. The present study analysed the calcium and phosphorus content of Dendrobaena veneta earthworms, a species commonly commercially reared and sold for insectivore food, gut loaded on three diets (fresh vegetables, fortified instant porridge oats and a commercial gut loading diet) and quantified the zinc, copper and magnesium content of fasted worms. Dendrobaena worms contained sufficient zinc, copper and magnesium to meet the general requirements of domestic birds, mammals and other vertebrates for these metals. However, calcium and calcium:phosphorus ratios of worms were deficient and did not improve after being offered fortified diets. Insufficient calcium in the diets, unpalatability of food and habituation effects also potentially contributed to this result. Unless better means of improving calcium content of Dendrobaena can be developed, husbandry professionals should be circumspect in their use of this species in a diet and ensure that dietary items with sufficient calcium are also provided

The effects of two calcium supplementation regimens on growth and health traits of juvenile mountain chicken frogs (Leptodactylus fallax)

The mountain chicken frog (Leptodactylus fallax) is among the 42 % of amphibians threatened with extinction and is dependent upon ex situ populations to recover in the wild. Amphibian captive husbandry is not fully understood and empirical data are required to optimise protocols for each species in captivity. Calcium metabolism and homeostasis are areas of importance in captive husbandry research and have been identified as a challenge in maintaining ex situ populations of L. fallax. We trialled two frequencies (twice and seven times weekly) of calcium supplementation via dusting of feeder insects in two groups of L. fallax juveniles and measured growth and health effects through morphometrics, radiography, ultrasonography and blood and faecal analysis over 167 days, followed by a further 230 days of monitoring on an intermediate diet informed by the initial dataset. We showed that supplementation treatment did not affect growth or health status as measured through blood analysis, radiography and ultrasonography. More frequent supplementation resulted in significantly more radiopaque endolymphatic sacs and broader skulls. Frogs fed more calcium excreted twice as much calcium in their faeces. The intermediate diet resulted in previously lower supplementation frogs approximating the higher supplementation frogs in morphometrics and calcium stores. Comparison with radiographic data from wild frogs showed that both treatments may still have had narrower skulls than wild animals, but mismatching age class may limit this comparison. Our data may be used to inform dietary supplementation of captive L. fallax as well as other amphibians

Hypertension in Diabetes Study (HDS): II. Increased risk of cardiovascular complications in hypertensive type 2 diabetic patients.

OBJECTIVE: To determine the degree to which hypertension is a risk factor for macrovascular and microvascular complications in type 2 diabetes. DESIGN: Observational prospective study. SUBJECTS: Newly diagnosed Type 2 diabetic patients recruited into the UK Prospective Diabetes Study (n = 3648; mean age 52 years), 40% of whom were hypertensive (blood pressure > or = 160 mmHg systolic and/or > or = 90 mmHg diastolic or already being treated for hypertension). MEASUREMENTS: The incidence of fatal and non-fatal major diabetes- and hypertension-related clinical events was determined over a median of 4.6 years' follow-up. The 3-year change in prevalence of subclinical indices of macrovascular and microvascular disease was assessed, including ECG abnormalities (Minnesota coding), left ventricular hypertrophy (ECG and chest x-ray), microalbuminuria (albumin/creatinine ratio) and moderately severe retinopathy (grading of retinal photographs). RESULTS: The hypertensive patients had (1) a greater incidence than normotensive patients of death from diabetes-related, mainly cardiovascular events (age-adjusted odds ratio 1.82) and (2) a greater incidence of diabetes-related death and major morbidity combined, including myocardial infarctions, angina, strokes and amputation (age-adjusted odds ratio 1.56). These associations were still present after allowance for other risk factors present at the time diabetes was diagnosed. The change in the prevalence of microvascular disease over 3 years was similar in both hypertensive and normotensive subjects. CONCLUSIONS: Hypertension is a major risk factor for cardiovascular morbidity and mortality in type 2 diabetes. Comparison with other studies suggests that patients with both hypertension and diabetes have approximately four times the cardiovascular risk of non-diabetic non-hypertensive subjects. Antihypertensive therapy may provide greater benefit in this high-risk group than in the general population

Tight blood pressure control and risk of macrovascular and microvascular complications in type 2 diabetes: UKPDS 38. UK Prospective Diabetes Study Group.

OBJECTIVE: To determine whether tight control of blood pressure prevents macrovascular and microvascular complications in patients with type 2 diabetes. DESIGN: Randomised controlled trial comparing tight control of blood pressure aiming at a blood pressure of <150/85 mm Hg (with the use of an angiotensin converting enzyme inhibitor captopril or a beta blocker atenolol as main treatment) with less tight control aiming at a blood pressure of <180/105 mm Hg. SETTING: 20 hospital based clinics in England, Scotland, and Northern Ireland. SUBJECTS: 1148 hypertensive patients with type 2 diabetes (mean age 56, mean blood pressure at entry 160/94 mm Hg); 758 patients were allocated to tight control of blood pressure and 390 patients to less tight control with a median follow up of 8.4 years. MAIN OUTCOME MEASURES: Predefined clinical end points, fatal and non-fatal, related to diabetes, deaths related to diabetes, and all cause mortality. Surrogate measures of microvascular disease included urinary albumin excretion and retinal photography. RESULTS: Mean blood pressure during follow up was significantly reduced in the group assigned tight blood pressure control (144/82 mm Hg) compared with the group assigned to less tight control (154/87 mm Hg) (P<0.0001). Reductions in risk in the group assigned to tight control compared with that assigned to less tight control were 24% in diabetes related end points (95% confidence interval 8% to 38%) (P=0.0046), 32% in deaths related to diabetes (6% to 51%) (P=0.019), 44% in strokes (11% to 65%) (P=0.013), and 37% in microvascular end points (11% to 56%) (P=0.0092), predominantly owing to a reduced risk of retinal photocoagulation. There was a non-significant reduction in all cause mortality. After nine years of follow up the group assigned to tight blood pressure control also had a 34% reduction in risk in the proportion of patients with deterioration of retinopathy by two steps (99% confidence interval 11% to 50%) (P=0.0004) and a 47% reduced risk (7% to 70%) (P=0.004) of deterioration in visual acuity by three lines of the early treatment of diabetic retinopathy study (ETDRS) chart. After nine years of follow up 29% of patients in the group assigned to tight control required three or more treatments to lower blood pressure to achieve target blood pressures. CONCLUSION: Tight blood pressure control in patients with hypertension and type 2 diabetes achieves a clinically important reduction in the risk of deaths related to diabetes, complications related to diabetes, progression of diabetic retinopathy, and deterioration in visual acuity

Cost effectiveness analysis of improved blood pressure control in hypertensive patients with type 2 diabetes: UKPDS 40

Objectives: To estimate the economic efficiency of tight blood pressure control, with angiotensin converting enzyme inhibitors or beta blockers, compared with less tight control in hypertensive patients with type 2 diabetes. Design: Cost effectiveness analysis incorporating within trial analysis and estimation of impact on life expectancy through use of the within trial hazards of reaching a defined clinical end point. Use of resources driven by trial protocol and use of resources in standard clinical practice were both considered. Setting: 20 hospital based clinics in England, Scotland, and Northern Ireland. Subjects: 1148 hypertensive patients with type 2 diabetes from UK prospective diabetes study randomised to tight control of blood pressure (n=758) or less tight control (n=390). Main outcome measure: Cost effectiveness ratios based on (a) use of healthcare resources associated with tight control and less tight control and treatment of complications and (b) within trial time free from diabetes related end points, and life years gained. Results: Based on use of resources driven by trial protocol, the incremental cost effectiveness of tight control compared with less tight control was cost saving. Based on use of resources in standard clinical practice, incremental cost per extra year free from end points amounted to £1049 (costs and effects discounted at 6% per year) and £434 (costs discounted at 6% per year and effects not discounted). The incremental cost per life year gained was £720 (costs and effects discounted at 6% per year) and £291 (costs discounted at 6% per year and effects not discounted). Conclusions: Tight control of blood pressure in hypertensive patients with type 2 diabetes substantially reduced the cost of complications, increased the interval without complications and survival, and had a cost effectiveness ratio that compares favourably with many accepted healthcare programmes

Efficacy of atenolol and captopril in reducing risk of macrovascular and microvascular complications in type 2 diabetes: UKPDS 39. UK Prospective Diabetes Study Group.

OBJECTIVE: To determine whether tight control of blood pressure with either a beta blocker or an angiotensin converting enzyme inhibitor has a specific advantage or disadvantage in preventing the macrovascular and microvascular complications of type 2 diabetes. DESIGN: Randomised controlled trial comparing an angiotensin converting enzyme inhibitor (captopril) with a beta blocker (atenolol) in patients with type 2 diabetes aiming at a blood pressure of <150/<85 mm Hg. SETTING: 20 hospital based clinics in England, Scotland, and Northern Ireland. SUBJECTS: 1148 hypertensive patients with type 2 diabetes (mean age 56 years, mean blood pressure 160/94 mm Hg). Of the 758 patients allocated to tight control of blood pressure, 400 were allocated to captopril and 358 to atenolol. 390 patients were allocated to less tight control of blood pressure. MAIN OUTCOME MEASURES: Predefined clinical end points, fatal and non-fatal, related to diabetes, death related to diabetes, and all cause mortality. Surrogate measures of microvascular and macrovascular disease included urinary albumin excretion and retinopathy assessed by retinal photography. RESULTS: Captopril and atenolol were equally effective in reducing blood pressure to a mean of 144/83 mm Hg and 143/81 mm Hg respectively, with a similar proportion of patients (27% and 31%) requiring three or more antihypertensive treatments. More patients in the captopril group than the atenolol group took the allocated treatment: at their last clinic visit, 78% of those allocated captopril and 65% of those allocated atenolol were taking the drug (P<0.0001). Captopril and atenolol were equally effective in reducing the risk of macrovascular end points. Similar proportions of patients in the two groups showed deterioration in retinopathy by two grades after nine years (31% in the captopril group and 37% in the atenolol group) and developed clinical grade albuminuria >=300 mg/l (5% and 9%). The proportion of patients with hypoglycaemic attacks was not different between groups, but mean weight gain in the atenolol group was greater (3.4 kg v 1.6 kg). CONCLUSION: Blood pressure lowering with captopril or atenolol was similarly effective in reducing the incidence of diabetic complications. This study provided no evidence that either drug has any specific beneficial or deleterious effect, suggesting that blood pressure reduction in itself may be more important than the treatment used

Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33)

Background Improved blood-glucose control decreases the progression of diabetic microvascular disease, but the effect on macrovascular complications is unknown. There is concern that sulphonylureas may increase cardiovascular mortality in patients with type 2 diabetes and that high insulin concentrations may enhance atheroma formation. We compared the effects of intensive blood-glucose control with either sulphonylurea or insulin and conventional treatment on the risk of microvascular and macrovascular complications in patients with type 2 diabetes in a randomised controlled trial.Methods 3867 newly diagnosed patients with type 2 diabetes, median age 54 years (IQR 48-60 years), who after 3 months' diet treatment had a mean of two fasting plasma glucose (FPG) concentrations of 6.1-15.0 mmol/L were randomly assigned intensive policy with a sulphonylurea (chlorpropamide, glibenclamide, or. glipizide) or with insulin, or conventional policy with diet. The aim in the intensive group was FPG less than 6 mmol/L. in the conventional group, the aim was the best achievable FPG with diet atone; drugs were added only if there were hyperglycaemic symptoms or FPG greater than 15 mmol/L. Three aggregate endpoints were used to assess differences between conventional and intensive treatment: any diabetes-related endpoint (sudden death, death from hyperglycaemia or hypoglycaemia, fatal or non-fatal myocardial infarction, angina, heart failure, stroke, renal failure, amputation [of at least one digit], vitreous haemorrhage, retinopathy requiring photocoagulation, blindness in one eye,or cataract extraction); diabetes-related death (death from myocardial infarction, stroke, peripheral vascular disease, renal disease, hyperglycaemia or hypoglycaemia, and sudden death); all-cause mortality. Single clinical endpoints and surrogate subclinical endpoints were also assessed. All analyses were by intention to treat and frequency of hypoglycaemia was also analysed by actual therapy.Findings Over 10 years, haemoglobin A(1c) (HbA(1c)) was 7.0% (6.2-8.2) in the intensive group compared with 7.9% (6.9-8.8) in the conventional group-an 11% reduction. There was no difference in HbA(1c) among agents in the intensive group. Compared with the conventional group, the risk in the intensive group was 12% lower (95% CI 1-21, p=0.029) for any diabetes-related endpoint; 10% lower (-11 to 27, p=0.34) for any diabetes-related death; and 6% lower (-10 to 20, p=0.44) for all-cause mortality. Most of the risk reduction in the any diabetes-related aggregate endpoint was due to a 25% risk reduction (7-40, p=0.0099) in microvascular endpoints, including the need for retinal photocoagulation. There was no difference for any of the three aggregate endpoints the three intensive agents (chlorpropamide, glibenclamide, or insulin).Patients in the intensive group had more hypoglycaemic episodes than those in the conventional group on both types of analysis (both p<0.0001). The rates of major hypoglycaemic episodes per year were 0.7% with conventional treatment, 1.0% with chlorpropamide, 1.4% with glibenclamide, and 1.8% with insulin. Weight gain was significantly higher in the intensive group (mean 2.9 kg) than in the conventional group (p<0.001), and patients assigned insulin had a greater gain in weight (4.0 kg) than those assigned chlorpropamide (2.6 kg) or glibenclamide (1.7 kg).Interpretation Intensive blood-glucose control by either sulphonylureas or insulin substantially decreases the risk of microvascular complications, but not macrovascular disease, in patients with type 2 diabetes. None of the individual drugs had an adverse effect on cardiovascular outcomes. All intensive treatment increased the risk of hypoglycaemia