Effects of epibiotic algae on the survival, biomass and recruitment of mussels, Mytilus L. (Bivalvia : Mollusca)

Habitats composed of living 'ecosystem engineers', such as mussels, are subject to direct and indirect interactions with organisms that live among them. These interactions may affect the presence and structure of habitat, and hence, the associated taxa. We examined the direct effects of epibiotic algae on the Survival, biomass and recruitment of mussels (Mytilits L.) on the west coast of Ireland. A field experiment showed that the presence of epibiotic fucoid algae reduced the likelihood of survival of mussels during storms. We also found that the strength of attachment of mussels did not increase in the presence of epibionts. Another in situ experiment revealed that the presence of ephemeral epibiotic algal mats had no effect on the biomass of host mussels, suggesting no effect on mussel growth or production. The abundance of small mussels (

Insulin-releasing and metabolic effects of small molecule GLP-1 receptor agonist 6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline

Much recent attention has focused on the GLP-1 receptor as a potential target for antidiabetic drugs. Enzyme resistant GLP-1 mimetics such as exenatide are now employed for the treatment of type 2 diabetes, but must be administered by injection. The present study has examined and compared the in vitro and in vivo metabolic actions of a small molecule GLP-1 receptor agonist 6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline (DMB), with native GLP-1, exenatide and liraglutide. DMB significantly stimulated in vitro insulin secretion from BRIN-BD11 cells but with decreased molar potency compared to native GLP-1 or related mimetics. Administration of DMB in combination with glucose to mice significantly (P

Effects of nateglinide on the secretion of glycated insulin and glucose tolerance in type 2 diabetes

Aims: Glycation of insulin has been demonstrated within pancreatic beta-cells and the resulting impaired bioactivity may contribute to insulin resistance in diabetes. We used a novel radioimmunoassay to evaluate the effect of nateglinide on plasma concentrations of glycated insulin and glucose tolerance in type 2 diabetes. Methods. Ten patients (5 M/5 F, age 57.8 +/- 1.9 years, HbA(1c), 7.6 +/- 0.5%,, fasting plasma glucose 9.4 +/- 1.2 mmol/l, creatinine 81.6 +/- 4.5 mumol/l) received oral nateglinide 120 mg or placebo, 10 min prior to 75 g oral glucose in a random, single blind, crossover design, 1 week apart. Blood samples were taken for glycated insulin, glucose, insulin and C-peptide over 225 min. Results: Plasma glucose and glycated insulin responses were reduced by 9% (P = 0.005) and 38% (P = 0.047), respectively, following nateglinide compared with placebo. Corresponding AUC measures for insulin and C-peptide were enhanced by 36% (P = 0.005) and 25% (P = 0.007) by nateglinide. Conclusions: Glycated insulin in type 2 diabetes is reduced in response to the insulin secretagogue nateglinide, resulting in preferential release of native insulin. Since glycated insulin exhibits impaired biological activity, reduced glycated insulin release may contribute to the anti hyperglycaemic action of nateglinide. (C) 2003 Elsevier Ireland Ltd. All rights reserved.

Degradation and glycemic effects of His(7)-glucitol glucagon-like peptide-1(7-36)amide in obese diabetic ob/ob mice

Glucagon-like peptide-1(7-36)amide (tGLP-1) has attracted considerable potential as a possible therapeutic agent for type 2 diabetes. However, tGLP-1 is rapidly inactivated in vivo by the exopeptidase dipeptidyl peptidase IV (DPP IV), thereby terminating its insulin releasing activity. The present study has examined the ability of a novel analogue, His(7)-glucitol tGLP-1 to resist plasma degradation and enhance the insulin-releasing and antihyperglycemic activity of the peptide in 20-25-week-old obese diabetic ob/ob mice. Degradation of native tGLP-1 by incubation at 37 degreesC with obese mouse plasma was clearly evident after 3 h (35% intact). After 6 h, more than 87% of tGLP-1 was converted to GLP-1(9-36)amide and two further N-terminal fragments, GLP-1(7-28) and GLP-1(9-28). In contrast, His7-glucitol tGLP-1 was completely resistant to N-terminal degradation. The formation of GLP-1(9-36)amide from native tGLP-1 was almost totally abolished by addition of diprotin A, a specific inhibitor of DPP IV. Effects of tGLP-1 and His7-glucitol tGLP-1 were examined in overnight fasted obese mice following i.p. injection of either peptide (30 nmol/kg) together with glucose (18 mmol/kg) or in association with feeding. Plasma glucose was significantly lower and insulin response greater following administration of His7-glucitol tGLP-1 as compared to glucose alone. Native tGLP-1 lacked antidiabetic effects under the conditions employed, and neither peptide influenced the glucose-lowering action of exogenous insulin (50 units/kg). Twice daily s.c. injection of ob/ob mice with His(7)-glucitol tGLP-1 (10 nmol/kg) for 7 days reduced fasting hyperglycemia and greatly augmented the plasma insulin response to the peptides given in association with feeding. These data demonstrate that His(7)-glucitol tGLP-1 displays resistance to plasma DPP IV degradation and exhibits antihyperglycemic activity and substantially enhanced insulin-releasing action in a commonly used animal model of type 2 diabetes. (C) 2001 Elsevier Science B.V. All rights reserved.

Age-specific reproductive investment in female burying beetles: independent effects of state and risk of death

1.How much should an individual invest in reproduction as it grows older? Answering this question involves determining whether individuals measure their age as the time left for future reproduction or as the rate of deterioration in their state. Theory suggests that in the former case individuals should increase their allocation of resources to reproduction as opportunities for future breeding dwindle, and terminally invest when they breed for the last time. In the latter case they should reduce their investment in reproduction with age, either through adaptive reproductive restraint or as a passive by-product of senescence.
2.Here we present the results of experiments on female burying beetles, Nicrophorus vespilloides, in which we independently manipulated the perceived risk of death (by activating the immune system) and the extent of deterioration in state (by changing age of first reproduction and/or prior investment in reproduction).
3.We found that the risk of death and state each independently influenced the extent of reproductive investment. Specifically, we found a state-dependent decline in reproductive investment as females grew older that could be attributed to both adaptive reproductive restraint and senescence. A perceived increase in the risk of death, induced by activation of the immune system, caused females to switch from a strategy of reproductive restraint to terminal investment. Nevertheless, absolute reproductive investment was lower in older females, indicating constraints of senescence.
4.Our results show that a decline in reproductive investment with age does not necessarily constitute evidence of reproductive senescence but can also result from adaptive reproductive restraint.
5.Our results further suggest that the extent of reproductive investment is dependent on several different intrinsic cues and that the particular blend of cues available at any given age can yield very different patterns of investment. Perhaps this explains why age-related reproductive investment patterns seen in nature are so diverse.

A Community Study of the Psychological Effects of the Omagh Car Bomb on Adults

Background: The main aims of the study were to assess psychological morbidity among adults nine months after a car bomb explosion in the town of Omagh, Northern Ireland and to identify predictors of chronic posttraumatic stress disorder symptoms.

Method: A questionnaire was sent to all adults in households in The Omagh District Council area. The questionnaire comprised established predictors of PTSD (such as pre-trauma personal characteristics, type of exposure, initial emotional response and long-term adverse physical or financial problems), predictors derived from the Ehlers and Clark (2000) cognitive model, a measure of PTSD symptoms and the General Health Questionnaire.

Results: Among respondents (n = 3131) the highest rates of PTSD symptoms and probable casesness (58.5%) were observed among people who were present in the street when the bomb exploded but elevated rates were also observed in people who subsequently attended the scene (21.8% probable caseness) and among people for whom someone close died (11.9%). People with a near miss (left the scene before the explosion) did not show elevated rates. Exposure to the bombing increased PTSD symptoms to a greater extent than general psychiatric symptoms. Previously established predictors accounted for 42% of the variance in PTSD symptoms among people directly exposed to the bombing. Predictors derived from the cognitive model accounted for 63%.

Conclusions: High rates of chronic PTSD were observed in individuals exposed to the bombing. Psychological variables that are in principle amenable to treatment were the best predictors of PTSD symptoms. Teams planning treatment interventions for victims of future bombings and other traumas may wish to take these results into account.

The Pleiotropic Effects of Simvastatin on Retinal Microvascular Endothelium Has Important Implications for Ischaemic Retinopathies

Background: Current guidelines encourage the use of statins to reduce the risk of cardiovascular disease in diabetic patients; however the impact of these drugs on diabetic retinopathy is not well defined. Moreover, pleiotropic effects of statins on the highly specialised retinal microvascular endothelium remain largely unknown. The objective of this study was to investigate the effects of clinically relevant concentrations of simvastatin on retinal endothelium in vitro and in vivo.

Methods and Findings: Retinal microvascular endothelial cells (RMECs) were treated with 0.01–10 µM simvastatin and a biphasic dose-related response was observed. Low concentrations enhanced microvascular repair with 0.1 µM simvastatin significantly increasing proliferation (p<0.05), and 0.01 µM simvastatin significantly promoting migration (p<0.05), sprouting (p<0.001), and tubulogenesis (p<0.001). High concentration of simvastatin (10 µM) had the opposite effect, significantly inhibiting proliferation (p<0.01), migration (p<0.01), sprouting (p<0.001), and tubulogenesis (p<0.05). Furthermore, simvastatin concentrations higher than 1 µM induced cell death. The mouse model of oxygen-induced retinopathy was used to investigate the possible effects of simvastatin treatment on ischaemic retinopathy. Low dose simvastatin(0.2 mg/Kg) promoted retinal microvascular repair in response to ischaemia by promoting intra-retinal re-vascularisation (p<0.01). By contrast, high dose simvastatin(20 mg/Kg) significantly prevented re-vascularisation (p<0.01) and concomitantly increased pathological neovascularisation (p<0.01). We also demonstrated that the pro-vascular repair mechanism of simvastatin involves VEGF stimulation, Akt phosphorylation, and nitric oxide production; and the anti-vascular repair mechanism is driven by marked intracellular cholesterol depletion and related disorganisation of key intracellular structures.

Conclusions: A beneficial effect of low-dose simvastatin on ischaemic retinopathy is linked to angiogenic repair reducing ischaemia, thereby preventing pathological neovascularisation. High-dose simvastatin may be harmful by inhibiting reparative processes and inducing premature death of retinal microvascular endothelium which increases ischaemia-induced neovascular pathology. Statin dosage should be judiciously monitored in patients who are diabetic or are at risk of developing other forms of proliferative retinopathy.

Effect of Aspirin or Resistant Starch on Colorectal Neoplasia in the Lynch Syndrome

Background: Observational and epidemiologic data indicate that the use of aspirin reduces the risk of colorectal neoplasia; however, the effects of aspirin in the Lynch syndrome (hereditary nonpolyposis colon cancer) are not known. Resistant starch has been associated with an antineoplastic effect on the colon.

Differential effects of reduced glycoprotein VI levels on activation of murine platelets by glycoprotein VI ligands

We have investigated the effects of decreased levels of the complex between glycoprotein VI (GPVI) and the Fc receptor gamma-chain (FcRgamma) on responses to collagen and GPVI-specific ligands in murine platelets. We show that levels of GPVI-FcRgamma of the order of 50 % and 20 % of wild-type levels caused 2- and 5-fold shifts to the right respectively in the dose-response curve for aggregation in response to collagen, the snake toxin convulxin and the monoclonal antibody JAQ1. In addition, there is a delay in the onset of aggregation in response to collagen. In contrast, the stimulation of protein tyrosine phosphorylation by collagen (as measured after 150 s) and adhesion to a collagen-coated surface under static conditions were unaffected in platelets with 50 % and 20 % of wild-type levels of GPVI. In contrast, responses to a collagen-related peptide (CRP), made up of repeat glycine-proline-hydroxyproline motifs, were markedly inhibited and abolished in platelets expressing 50 % and 20 % of wild-type levels of GPVI respectively. We suggest that the marked effect of a reduction in GPVI levels on the CRP-induced activation of platelets is due to the multivalent nature of CRP and the fact that GPVI is its sole receptor on platelets. Thus it appears that the interaction of CRP with GPVI is determined by a combination of affinity and avidity. The observation that collagen does not behave like CRP in platelets expressing reduced levels of GPVI, even in the combined presence of blocking antibodies against integrin alpha2beta1 and GPV, suggests that collagen has a greater affinity than CRP for GPVI, and/or that other receptors are involved in its binding to platelets. The clinical significance of these results is discussed.

Effects of particle plasticity characteristics on local interface stress in particle reinforced composite during uniaxial tension

For elastoplastic particle reinforced metal matrix composites, failure may originate from interface debonding between the particles and the matrix, both elastoplastic and matrix fracture near the interface. To calculate the stress and strain distribution in these regions, a single reinforcing particle axisymmetric unit cell model is used in this article. The nodes at the interface of the particle and the matrix are tied. The development of interfacial decohesion is not modelled. Finite element modelling is used, to reveal the effects of particle strain hardening rate, yield stress and elastic modulus on the interfacial traction vector (or stress vector), interface deformation and the stress distribution within the unit cell, when the composite is under uniaxial tension. The results show that the stress distribution and the interface deformation are sensitive to the strain hardening rate and the yield stress of the particle. With increasing particle strain hardening rate and yield stress, the interfacial traction vector and internal stress distribution vary in larger ranges, the maximum interfacial traction vector and the maximum internal stress both increase, while the interface deformation decreases. In contrast, the particle elastic modulus has little effect on the interfacial traction vector, internal stress and interface deformation.

UNISTEP (University Students Exercise and Physical Activity) Study: A Pilot Study of the Effects of Accumulating 10,000 Steps on Health and Fitness Among University Students.

BACKGROUND: Recent public health initiatives have promoted accumulating 10,000 steps per day. Little previous research has evaluated its effects in young adults. The aim of this study was to determine the effects of taking 10,000 steps per day on fitness and cardiovascular risk factors in sedentary university students. METHODS: Healthy, sedentary students (mean age 21.16 ± SD 6.17) were randomly allocated to take 10,000 steps per day or to a control group who maintained their habitual activity. Members of the 10,000 step group wore a pedometer and reported daily step count in a diary. Outcome measurements (20-meter multistage shuttle run, BMI, and blood pressure) were measured before and after 6 weeks. RESULTS: There were no significant differences between the groups at baseline. After 6 weeks, the 10,000 steps group were taking significantly more steps (8824.1 ± SD 5379.3 vs. 12635.9 ± SD 6851.3; P = .03).No changes were observed in fitness, or BMI (P > .05). Significant reductions in blood pressure (P = .04) in the 10,000 step group. CONCLUSIONS: A daily target of 10,000 steps may be an appropriate intervention in sedentary university students to increase their physical activity levels. The positive health benefits of simple everyday physical activity should be promoted among health professionals.

Endocrine disrupting effects of zearalenone, alpha- and beta-zearalenol at the level of nuclear receptor binding and steroidogenesis.

The mycotoxin zearalenone (ZEN) is a secondary metabolite of fungi which is produced by certain species of the genus Fusarium and can occur in cereals and other plant products. Reporter gene assays incorporating natural steroid receptors and the H295R steroidogenesis assay have been implemented to assess the endocrine disrupting activity of ZEN and its metabolites -zearalenol (-ZOL) and -zearalenol (-ZOL). -ZOL exhibited the strongest estrogenic potency (EC50 0.022 ± 0.001 nM), slightly less potent than 17- estradiol (EC50 0.015 ± 0.002 nM). ZEN was ~70 times less potent than -ZOL and twice as potent as -ZOL. Binding of progesterone to the progestagen receptor was shown to be synergistically increased in the presence of ZEN, -ZOL or -ZOL. ZEN, -ZOL or -ZOL increased production of progesterone, estradiol, testosterone and cortisol hormones in the H295R steroidogenesis assay, with peak productions at 10 M. At 100 M, cell viability decreased and levels of hormones were significantly reduced except for progesterone. -ZOL increased estradiol concentrations more than -ZOL or ZEN, with a maximum effect at 10 M, with -ZOL (562 ± 59 pg/ml) > -ZOL (494 ± 60 pg/ml) > ZEN (375 ± 43 pg/ml). The results indicate that ZEN and its metabolites can act as potential endocrine disruptors at the level of nuclear receptor signalling and by altering hormone production.

The effects of a volunteer mentoring programme on reading outcomes among eight- to nine-year-old children: A follow up randomized controlled trial

This article presents the findings of a randomized controlled trial evaluation of the effects of a revised version of the volunteer mentoring programme, Time to Read. Participating children received two 30-minute mentoring sessions per week from volunteer mentors who carried out paired reading activities with the children. The current trial involved 512 children aged eight to nine years from 50 primary schools. The programme was found to be effective in improving decoding skills (d=+.15), reading rate (d=+.22) and reading fluency (d=+.14) and there was some evidence of a positive effect in relation to the children’s aspirations for the future (d=+.11). However, no evidence was found of the programme having an effect on reading comprehension or reading confidence and enjoyment of reading. The article concludes by suggesting that mentoring programmes using non-specialist volunteers can be effective in improving foundational reading skills but would appear to be less effective in terms of improving higher-order skills such as comprehension. The article also suggests that such programmes are likely to be most effective if concentrating on core reading activities rather than attempting to address reading outcomes indirectly through improving children’s confidence or wider enjoyment of reading.

Differential effects of magnetic pulses on the orientation of naturally migrating birds

In migratory passerine birds, strong magnetic pulses are thought to be diagnostic of the remagnetization of iron minerals in a putative sensory system contained in the beak. Previous evidence suggests that while such a magnetic pulse affects the orientation of migratory birds in orientation cages, no effect was present when pulse-treated birds were tested in natural migration. Here we show that two migrating passerine birds treated with a strong magnetic pulse, designed to alter the magnetic sense, migrated in a direction that differed significantly from that of controls when tested in natural conditions. The orientation of treated birds was different depending on the alignment of the pulse with respect to the magnetic field. These results can aid in advancing understanding of how the putative iron-mineral-based receptors found in birds' beaks may be used to detect and signal the intensity and/or direction of the Earth's magnetic field.

Review and meta-analysis of the short-term effects of a vegetable oil emulsion on food intake

Several short-term studies have investigated the effects of a vegetable oil emulsion on subsequent food intake, although findings have been inconsistent. This work aimed to review all studies, and investigate differences in study outcomes based on methodology. All known studies were identified. Data were abstracted from published studies (n = 7). Details of unpublished studies were gained from investigators/sponsors (n = 5), or were unavailable for reasons of confidentiality (n = 4). Available data were combined using meta-analyses. A combined appetite suppressant effect of the emulsion compared with control was found for test meal intake at approximately 4, 12 and 36 h post-treatment: smallest combined mean difference (random effects model) = 0.53 MJ (95% confidence interval 0.20, 0.86), P < 0.01. However, considerable heterogeneity (variability) between study results was also found (smallest I2 = 94%, P < 0.01), questioning the predictive validity of the above findings. Meta-regression suggested this heterogeneity to be related to differences in the processed nature of the product, treatment dose and in particular year of study (smallest B = 0.54, 95% confidence interval 0.06, 1.03, P = 0.04), although again heterogeneity was found. The only consistent finding was a lack of effect on food intake 4 h post-preload in studies conducted after 2003. These results suggest a small but inconsistent appetite suppressant effect of the vegetable oil emulsion. However, due to the large heterogeneity, no definitive conclusions can be drawn.