Renin in critically ill patients

The renin-angiotensin system (RAS) constitutes one of the principal mechanisms to maintain hemodynamic and fluid homeostasis. However, most research until now on RAS primarily focuses on its relationship with hypertension and its role in critically ill hypotensive populations is not well understood. With the approval of angiotensin II (Ang II) in the United States and Europe, following a phase 3 randomized controlled trial showing efficacy in catecholamine-resistant vasodilatory shock, there is growing interest in RAS in critically ill patients. Among the fundamental components of RAS, renin acts as the initial stimulus for the entire system. In the context of hypotension, its release increases in response to low blood pressure sensed by renal baroreceptors and attenuated negative Ang II feedback loop. Thus, elevated renin could reflect disease severity and predict poor outcomes. Studies investigating this hypothesis have validated the prognostic accuracy of renin in various critically ill populations, with several reports indicating its superiority to lactate for mortality prediction. Accordingly, renin reduction has been used to assess the effectiveness of Ang II administration. Furthermore, renin holds potential to identify patients who might benefit from Ang II treatment, potentially paving the way for personalized vasopressor management. Despite these promising data, most available evidence is derived from retrospective analysis and necessitates prospective confirmation. The absence of a rapid, point-of-care and reliable renin assay presents another hurdle to its integration into routine clinical practice. This narrative review aims to describe the current understanding and future directions of renin as a biomarker during resuscitation of critically ill patients.

Intensive Care Unit-Like Care of Nonhuman Primates with Ebola Virus Disease

BACKGROUND

Ebola virus disease (EVD) supportive care strategies are largely guided by retrospective observational research. This study investigated the effect of EVD supportive care algorithms on duration of survival in a controlled nonhuman primate (NHP) model.

METHODS

Fourteen rhesus macaques were challenged intramuscularly with a target dose of Ebola virus (1000 plaque-forming units; Kikwit). NHPs were allocated to intensive care unit (ICU)-like algorithms (n = 7), intravenous fluids plus levofloxacin (n = 2), or a control group (n = 5). The primary outcome measure was duration of survival, and secondary outcomes included changes in clinical laboratory values.

RESULTS

Duration of survival was not significantly different between the pooled ICU-like algorithm and control groups (8.2 vs 6.9 days of survival; hazard ratio; 0.50; P = .25). Norepinephrine was effective in transiently maintaining baseline blood pressure. NHPs treated with ICU-like algorithms had delayed onset of liver and kidney injury.

CONCLUSIONS

While an obvious survival difference was not observed with ICU-like care, clinical observations from this model may aid in EVD supportive care NHP model refinement.

A nurse-led paediatric oncology fast-track clinic proves a successful ambulatory intervention for patients

AIM

To assess the impact of a pilot nurse-led paediatric oncology fast-track clinic (OFTC) for complications and side effects following chemotherapy within a paediatric tertiary hospital.

METHODS

Prospective clinical data from the first 100 patients seen in the OFTC were compared with retrospective data of oncology patient presentations to the emergency department (ED) (over a 1-year period, n = 196) who would have been eligible for review in the OFTC. Parent and patient satisfaction of clinical care were also assessed via surveys pre- and post-OFTC implementation.

RESULTS

Analysis which achieved statistical difference was a reduction in the number of blood tubes taken in OFTC (average 1.9 for those discharged from clinic, 2.9 for those admitted from clinic) in comparison to those seen in the ED (average 3.2) (p = 0.0027). The average number of interventions per patient seen in the ED were 2.1 (standard deviation 1.64) compared with 1.7 (standard deviation 1.55) interventions per patient seen in the OFTC, and who were not admitted following review. This result approached statistical significance with p = 0.0963. Other results which did not meet statistical significance included a reduction in treatment times, hospital admissions and medical oncology reviews.

CONCLUSION

Our pilot study implementing an OFTC for the triage and assessment of chemotherapy-related complications has proven successful from an operational and consumer perspective. The clinic improved care by ensuring expedited review, more streamlined interventions, and less overall hospital admissions. The improvements in efficiency were also mirrored by increased parent and patient satisfaction.

Delayed immune-related adverse events in assessment for dose-limiting toxicity in early phase immunotherapy trials

BACKGROUND

Immunotherapy (IO) agents can cause late-onset immune-related adverse events (irAEs). In phase I trials, observation for dose-limiting toxicities (DLTs) is typically limited to the first cycle. The incidence of delayed-onset DLTs and their potential impact on dose determination have not been fully elucidated.

PATIENTS AND METHODS

Consecutive patients enrolled in early phase IO trials at Princess Margaret Cancer Centre between August 2012 and September 2016 were retrospectively reviewed, applying trial-specific definitions for DLTs. A clinically significant AE (csAE) was defined as a treatment-related adverse event requiring corticosteroids, hormone replacement, IO delay or discontinuation.

RESULTS

A total of 352 consecutive trial enrolments in 21 early phase clinical trials were included. Two-hundred seventy-eight patients (79%) received monotherapy and 74 (21%) received combination IO. Two hundred sixty (74%) patients experienced irAEs. There were two protocol-defined DLTs. Twenty (5.7%) patients had 24 csAEs qualifying as DLTs except for occurrence after the protocol-specified DLT period. One-hundred and six (10%) of irAEs were csAEs, including endocrine (26%), respiratory (14%), gastrointestinal (11%), general (10%), dermatological (8%), hepatic (8%), musculoskeletal (6%), pancreatic (6%), haematological, metabolic, neurological, cardiac (each 2%), infective and ocular (each 1%) events. The highest risk of first-onset csAE was during the first 4 weeks compared with the period from 4 weeks to end of treatment (odds ratio 3.13, 95% confidence interval 1.95-5.02). The median time to first onset csAE was significantly shorter with combination than monotherapy IO (32 vs. 146 days, P < 0.001).

CONCLUSIONS

In our series of early phase IO trials, the risk of csAE was highest during the initial 4 weeks on IO treatment, supporting the use of the conventional DLT period for dose escalation decision. However, there were 24 clinically significant late-onset DLTs in 5.7% of patients. Combination IO was associated with greater risk of and also earlier onset for csAE, which may need to be considered for early phase trial design.

Attenuation of pulmonary ACE2 activity impairs inactivation of des-Arg9 bradykinin/BKB1R axis and facilitates LPS-induced neutrophil infiltration

Angiotensin-converting enzyme 2 (ACE2) is a terminal carboxypeptidase with important functions in the renin-angiotensin system and plays a critical role in inflammatory lung diseases. ACE2 cleaves single-terminal residues from several bioactive peptides such as angiotensin II. However, few of its substrates in the respiratory tract have been identified, and the mechanism underlying the role of ACE2 in inflammatory lung disease has not been fully characterized. In an effort to identify biological targets of ACE2 in the lung, we tested its effects on des-Arg⁹ bradykinin (DABK) in airway epithelial cells on the basis of the hypothesis that DABK is a biological substrate of ACE2 in the lung and ACE2 plays an important role in the pathogenesis of acute lung inflammation partly through modulating DABK/bradykinin receptor B1 (BKB1R) axis signaling. We found that loss of ACE2 function in mouse lung in the setting of endotoxin inhalation led to activation of the DABK/BKB1R axis, release of proinflammatory chemokines such as C-X-C motif chemokine 5 (CXCL5), macrophage inflammatory protein-2 (MIP2), C-X-C motif chemokine 1 (KC), and TNF-α from airway epithelia, increased neutrophil infiltration, and exaggerated lung inflammation and injury. These results indicate that a reduction in pulmonary ACE2 activity contributes to the pathogenesis of lung inflammation, in part because of an impaired ability to inhibit DABK/BKB1R axis-mediated signaling, resulting in more prompt onset of neutrophil infiltration and more severe inflammation in the lung. Our study identifies a biological substrate of ACE2 within the airways, as well as a potential new therapeutic target for inflammatory diseases.

Abstract P324: Reduction in Excreted Sodium Load in Obese Sheep: Role of Antenatal Betamethasone and Sex

Our previous studies have demonstrated the programmed impairment of sodium excretion in lean antenatal betamethasone exposed sheep whereby the males exhibited blunted excretion of a sodium load when compared to control males or control or antenatal betamethasone exposed females. Obesity has been recognized as a risk factor for developing early stage kidney failure in individuals exposed to unfavorable intrauterine conditions by virtue of fetal programming. We hypothesize that obesity (second hit) can accentuate the impairment of sodium excretion in antenatal betamethasone exposed offspring in a sex specific manner.

Pregnant ewes received either betamethasone or vehicle at 80-81 days gestation. The male (n=6 per group) or female (n=5 per group) offspring were overfed to become obese (40% weight gain over a course of 3 months) at age of 1.5 years. Acute sodium load (sodium chloride: 0.13g/kg) was administrated intravenously. Sodium excretion (excreted sodium load), blood pressure (BP), renal plasma flow (RPF), and glomerular filtration rate (GFR) were measured. Data for sodium excretion are expressed as percentage of excreted sodium load. ANOVA and Student’s t test were used for data analysis.

The excreted sodium load was lower in obese male antenatal betamethasone exposed offspring (OMB) than in obese male vehicle exposed offspring (OMV) (13.5±3.1% vs. 33.2±9.9% p=0.04). However, the excreted sodium load was not significantly different between obese female antenatal betamethasone exposed offspring (OFB) and obese female vehicle exposed offspring (OFV) (60.4±6.2% vs. 72.0±8.2%, p=0.31). Compared male offspring with female offspring, the excreted sodium load was lower in male offspring (33.2±9.9% vs. 72.0±8.2%, p=0.001, OMV vs. OFV; 13.5±3.2% vs. 60.4±6.2%, p<0.0001, OMB vs. OFB). During the experiments BP, RPF and GFR did not change significantly. .

These data suggest that obesity, acting as a second hit, accentuates impairment of sodium excretion in antenatal betamethasone exposed male but not female offspring. Thus the sex specific effect of antenatal betamethasone on sodium excretion persists in in animals experiencing a secondary insult of obesity in adulthood.

Establishment of Early Endpoints in Mouse Total-Body Irradiation Model

Acute radiation sickness (ARS) following exposure to ionizing irradiation is characterized by radiation-induced multiorgan dysfunction/failure that refers to progressive dysfunction of two or more organ systems, the etiological agent being radiation damage to cells and tissues over time. Radiation sensitivity data on humans and animals has made it possible to describe the signs associated with ARS. A mouse model of total-body irradiation (TBI) has previously been developed that represents the likely scenario of exposure in the human population. Herein, we present the Mouse Intervention Scoring System (MISS) developed at the Veterinary Sciences Department (VSD) of the Armed Forces Radiobiology Research Institute (AFRRI) to identify moribund mice and decrease the numbers of mice found dead, which is therefore a more humane refinement to death as the endpoint. Survival rates were compared to changes in body weights and temperatures in the mouse (CD2F1 male) TBI model (6–14 Gy, ⁶⁰Co γ-rays at 0.6 Gy min^-1), which informed improvements to the Scoring System. Individual tracking of animals via implanted microchips allowed for assessment of criteria based on individuals rather than by group averages. From a total of 132 mice (92 irradiated), 51 mice were euthanized versus only four mice that were found dead (7% of non-survivors). In this case, all four mice were found dead after overnight periods between observations. Weight loss alone was indicative of imminent succumbing to radiation injury, however mice did not always become moribund within 24 hours while having weight loss >30%. Only one survivor had a weight loss of greater than 30%. Temperature significantly dropped only 2–4 days before death/euthanasia in 10 and 14 Gy animals. The score system demonstrates a significant refinement as compared to using subjective assessment of morbidity or death as the endpoint for these survival studies.

Significance of Bioindicators for Early Predictions on Diagnosis and Therapy of Irradiated Minipigs

Decisions on whether to start a therapeutic intervention for management of the Acute Radiation Syndrome (ARS) should be made early after exposure, and it should be based on readily available clinical signs and laboratory parameters. Here, the authors use the minipig to assess if early prediction of the later developing clinical outcome and necessity of therapeutic interventions can be determined within the first 3 d after exposure and whether it is comparable to human data. Retrospective analysis of data accumulated in the period 2009-2012 was used. Male Göttingen minipigs (age 4-5 mo, weight 9-10 kg) were irradiated (or sham-irradiated) bilaterally with gamma-photons (Co, 0.5-0.6 Gy min) in the dose range of 1.6-12 Gy. Complete blood counts, serum chemistry, and clinical symptoms were collected up to 60 d after irradiation in untreated minipigs. Changes in these early parameters (up to 3 d after exposure) were correlated with later occurrence (10-60 d after irradiation) of (1) hematological severity scores, (2) severe thrombocytopenia, (3) severe neutropenia, as well as need for (4) therapeutic intervention, (5) administration of cytokines/antibiotics, or (6) thrombocyte transfusions. Binary endpoints were analyzed using logistic regression analysis and calculating receiver operating characteristic (ROC) curves. Most predictive were decreased lymphocyte counts and increases in body temperature at 3 h after irradiation. These data corroborate earlier findings performed on human radiation victims suffering from severe hematological syndrome and provide further evidence for the suitability of the minipig model as a potential alternative non-rodent animal model.

Systems Pharmacology Approach for Prediction of Pulmonary and Systemic Pharmacokinetics and Receptor Occupancy of Inhaled Drugs

Pulmonary drug disposition after inhalation is complex involving mechanisms, such as regional drug deposition, dissolution, and mucociliary clearance. This study aimed to develop a systems pharmacology approach to mechanistically describe lung disposition in rats and thereby provide an integrated understanding of the system. When drug‐ and formulation‐specific properties for the poorly soluble drug fluticasone propionate were fed into the model, it proved predictive of the pharmacokinetics and receptor occupancy after intravenous administration and nose‐only inhalation. As the model clearly distinguishes among drug‐specific, formulation‐specific, and system‐specific properties, it was possible to identify key determinants of pulmonary selectivity of receptor occupancy of inhaled drugs: slow particle dissolution and slow drug‐receptor dissociation. Hence, it enables assessment of factors for lung targeting, including molecular properties, formulation, as well as the physiology of the animal species, thereby providing a general framework for rational drug design and facilitated translation of lung targeting from animal to man.

Gaining a Critical Mass: A Dose Metric Conversion Case Study Using Silver Nanoparticles

Mass concentration is the standard convention to express exposure in ecotoxicology for dissolved substances. However, nanotoxicology has challenged the suitability of the mass concentration dose metric. Alternative metrics often discussed in the literature include particle number, surface area, and ion release (kinetics, equilibrium). It is unlikely that any single metric is universally applicable to all types of nanoparticles. However, determining the optimal metric for a specific type of nanoparticle requires novel studies to generate supportive data and employ methods to compensate for current analytical capability gaps. This investigation generated acute toxicity data for two standard species (Ceriodaphnia dubia, Pimephales promelas) exposed to five sizes (10, 20, 30, 60, 100 nm) of monodispersed citrate- and polyvinylpyrrolidone-coated silver nanoparticles. Particles were sized by various techniques to populate available models for expressing the particle number, surface area, and dissolved fraction. Results indicate that the acute toxicity of the tested silver nanoparticles is best expressed by ion release, and is relatable to total exposed surface area. Particle number was not relatable to the observed acute silver nanoparticle effects.

Abstract P169: Antenatal Betamethasone Attenuates the Angiotensin-(1-7)/Nitric Oxide Axis in Adult Male but not Female Renal Proximal Tubule Cells

Our studies have revealed a sex-specific effect of fetal programming on sodium (Na+) excretion in adult sheep whereby the males exhibit reduced Na+ excretion and an attenuated natriuretic response to Ang-(1-7) as compared to the females. We hypothesize that the renal proximal tubules are a key target for the early programming effects of glucocorticoids exposure to regulate Na+ handling in the adult males. Therefore, we isolated and cultured cortical proximal tubule cells (RPTC) from adult male and female sheep antenatally exposed to betamethasone (Beta) or vehicle. Na+ uptake and nitric oxide (NO) were assessed with Sodium Green and DAF fluorescence prior to and following a low dose of Ang-(1-7) (1x10-11 M) in isolated RPTC from sheep at ~1.5 years of age. Data are expressed as % of basal uptake or area under the curve (AUC) for Na+ or % of control for NO. Male Beta RPTC exhibit greater Na+ uptake than male vehicle cells (427±32%, n=13, vs. 315±28%, n=14, p<0.05; however, Beta had no effect on Na+ uptake in the female cells (242±18%, n=9, vs. 250±15%, n=10, p>0.05). Ang-(1-7) inhibited Na+ uptake in RPTC from vehicle male (255±40%) and from both vehicle (191±14%) and Beta (209±11%) females (Figure 1B), but failed to attenuate Na+ uptake in Beta male cells (Figure 1A). Beta exposure also abolished NO stimulation by Ang-(1-7) in male but not female RPTC (Figure 1C). We conclude that an Ang-(1-7)-NO-dependent pathway contributes to the sex-dependent consequences of programming on Na+ regulation in the proximal tubules of the kidney. Moreover, the RPTC retain both the sex and Beta-induced phenotype of the adult and may reflect an appropriate cell model of fetal programming.

Antenatal glucocorticoid treatment alters Na+ uptake in renal proximal tubule cells from adult offspring in a sex-specific manner

We have shown a sex-specific effect of fetal programming on Na(+) excretion in adult sheep. The site of this effect in the kidney is unknown. Therefore, we tested the hypothesis that renal proximal tubule cells (RPTCs) from adult male sheep exposed to betamethasone (Beta) before birth have greater Na(+) uptake than do RPTCs from vehicle-exposed male sheep and that RPTCs from female sheep similarly exposed are not influenced by antenatal Beta. In isolated RPTCs from 1- to 1.5-yr-old male and female sheep, we measured Na(+) uptake under basal conditions and after stimulation with ANG II. To gain insight into the mechanisms involved, we also measured nitric oxide (NO) levels, ANG II receptor mRNA levels, and expression of Na(+)/H(+) exchanger 3. Basal Na(+) uptake increased more in cells from Beta-exposed male sheep than in cells from vehicle-exposed male sheep (400% vs. 300%, P < 0.00001). ANG II-stimulated Na(+) uptake was also greater in cells from Beta-exposed males. Beta exposure did not increase Na(+) uptake by RPTCs from female sheep. NO production was suppressed more by ANG II in RPTCs from Beta-exposed males than in RPTCs from either vehicle-exposed male or female sheep. Our data suggest that one site of the sex-specific effect of Beta-induced fetal programming in the kidney is the RPTC and that the enhanced Na(+) uptake induced by antenatal Beta in male RPTCs may be related to the suppression of NO in these cells.

Planning following stroke: a relational complexity approach using the tower of london

Planning on the 4-disk version of the Tower of London (TOL4) was examined in stroke patients and unimpaired controls. Overall TOL4 solution scores indicated impaired planning in the frontal stroke but not non-frontal stroke patients. Consistent with the claim that processing the relations between current states, intermediate states, and goal states is a key process in planning, the domain-general relational complexity metric was a good indicator of the experienced difficulty of TOL4 problems. The relational complexity metric shared variance with task-specific metrics of moves to solution and search depth. Frontal stroke patients showed impaired planning compared to controls on problems at all three complexity levels, but at only two of the three levels of moves to solution, search depth and goal ambiguity. Non-frontal stroke patients showed impaired planning only on the most difficult quaternary-relational and high search depth problems. An independent measure of relational processing (viz., Latin square task) predicted TOL4 solution scores after controlling for stroke status and location, and executive processing (Trail Making Test). The findings suggest that planning involves a domain-general capacity for relational processing that depends on the frontal brain regions.

Gastrointestinal acute radiation syndrome in Göttingen minipigs (Sus scrofa domestica)

In the absence of supportive care, exposing Göttingen minipigs to γ-radiation doses of less than 2 Gy achieves lethality due to hematopoietic acute radiation syndrome. Doses of 2 to 5 Gy are associated with an accelerated hematopoietic syndrome, characterized by villus blunting and fusion, the beginning of sepsis, and a mild transient reduction in plasma citrulline concentration. We exposed male Göttingen minipigs (age, 5 mo; weight, 9 to 11 kg) to γ-radiation doses of 5 to 12 Gy (total body; (60)Co, 0.6 Gy/min) to test whether these animals exhibit classic gastrointestinal acute radiation syndrome (GI-ARS). After exposure, the minipigs were monitored for 10 d by using clinical signs, CBC counts, and parameters associated with the development of the gastrointestinal syndrome. Göttingen minipigs exposed to γ radiation of 5 to 12 Gy demonstrate a dose-dependent occurrence of all parameters classically associated with acute GI-ARS. These results suggest that Göttingen minipigs may be a suitable model for studying GI-ARS after total body irradiation, but the use of supportive care to extend survival beyond 10 d is recommended. This study is the first step toward determining the feasibility of using Göttingen minipigs in testing the efficacy of candidate drugs for the treatment of GI-ARS after total body irradiation.

Euthanasia assessment in ebola virus infected nonhuman primates

Multiple products are being developed for use against filoviral infections. Efficacy for these products will likely be demonstrated in nonhuman primate models of filoviral disease to satisfy licensure requirements under the Animal Rule, or to supplement human data. Typically, the endpoint for efficacy assessment will be survival following challenge; however, there exists no standardized approach for assessing the health or euthanasia criteria for filovirus-exposed nonhuman primates. Consideration of objective criteria is important to (a) ensure test subjects are euthanized without unnecessary distress; (b) enhance the likelihood that animals exhibiting mild or moderate signs of disease are not prematurely euthanized; (c) minimize the occurrence of spontaneous deaths and loss of end-stage samples; (d) enhance the reproducibility of experiments between different researchers; and (e) provide a defensible rationale for euthanasia decisions that withstands regulatory scrutiny. Historic records were compiled for 58 surviving and non-surviving monkeys exposed to Ebola virus at the US Army Medical Research Institute of Infectious Diseases. Clinical pathology parameters were statistically analyzed and those exhibiting predicative value for survival are reported. These findings may be useful for standardization of objective euthanasia assessments in rhesus monkeys exposed to Ebola virus and may serve as a useful approach for other standardization efforts.

Uncertainty in multi-media fate and transport models: a case study for TNT life cycle assessment

Life cycle assessment (LCA) is an evaluation method used by decision-makers to help assess the relative environmental impacts of various industrial processes. Despite that many LCA methods remain sensitive to uncertain input data, which can reduce the utility of their results, uncertainty arising from constituent LCA models remains poorly understood. Here, we begin to address this problem by evaluating the extent to which parameter-value uncertainty affects the SimpleBox 2.0 fate and transport model, which serves as a backbone for many LCA ecotoxicological impact categories. Two Monte Carlo type sampling methods were used to evaluate dispersion in steady-state concentration values for three chemicals involved in grenade production: toluene, 2,4-dinitrotoluene (2,4-DNT), and 2,4,6-trinitrotoluene (TNT). Parameters were first sampled stochastically one-at-a-time, then by randomly exploring a local patch of the parameter space. We confirmed that global temperatures contribute primarily to the overall variance of model results, which at most spanned approximately 8 decades in magnitude. These results are consistent with previous results obtained for the whole of the LCA method. LCA methods carry out calculations iteratively; a reduction in the error of a single component, such as the fate and transport model, may therefore improve its performance and utility as a decision-making aid.

Turning the corner with the flash-lag illusion

Previous attempts to measure localization bias around a right-angle turn (L-trajectory) have found either no spatial bias off the trajectory (Whitney, Cavanagh, & Murakami, 2000) or a bias, in different experiments, both 'inside' and 'outside' the trajectory (Nieman, Sheth, & Shimojo, 2010). However, Eagleman and Sejnowski (2007) presented data showing that the perceived location of a brief feature on two moving stimuli could be predicted from the vector sum of their directions after the feature appeared. Such a vector sum with an L-trajectory could predict that the perceived position before the turn should be biased 'sideways' off the trajectory, in the direction of the final motion. With stimuli that particularly facilitated accurate vernier judgments, and measuring bias via the flash-lag illusion, this is indeed what we observed. Our data thus favour Eagleman and Sejnowski's (2007) supposition. Further, the bias occurred before the change in direction, rather than after it, supporting the contention that it is motion after a point being sampled that affects its perception (Bachmann et al., 2003; Eagleman & Sejnowski, 2007; Krekelberg & Lappe, 2000; Nieman, Sheth, & Shimojo, 2010).

Abstract 610: A Pepstatin-Sensitive Aspartyl Peptidase as an Early Urinary Marker of Renal Injury in the Diabetic Hypertensive mRen2.Lewis Female Rat

We previously reported that induction of diabetes in estrogen-depleted, hypertensive mRen2.Lewis (mRen2) female rats leads to significant albuminuria, proteinuria and tubulointerstial oxidative stress at 28 days. The current study assessed the time course for the development of proteinuria and peptidase activities in the urine of the diabetic hypertensive mRen2 to begin to establish potential biomarkers of renal injury in this model. Heterozygous mRen2 underwent ovariectomy and diabetes was induced by a single administration of streptozotocin (65 mg/kg; STZ) at 15 weeks of age. Urinary samples were taken prior to (day 0) and 5 and 28 days following STZ. Aspartyl peptidases were assayed with the quenched fluorescent substrate Mca-GWPILFFRLW(Dnp)R in the presence or absence of the inhibitor pepstatin. Enzyme activities were expressed as nmols Mca per 30 min per mg creatinine. Pepstatin-sensitive activity [IC50 ∼ 0.4 nM] was detectable in the pre-diabetic urines [26 ± 9; n=8]; however, the diabetic rats exhibited a significant increase in urinary activity at days 5 and 28 [184 ± 25 and 204 ± 53, respectively; p<0.05 vs. day 0]. In contrast, pepstatin-insensitive activity was markedly lower and decreased between days 0 and 5 [22 ± 2 vs. 12 ± 4; p<0.05], but was unchanged at day 28 [34 ± 12]. Proteinuria was similar at days 0 and day 5, but significantly increased by day 28. Aspartyl peptidases in the kidney and urine that are sensitive to pepstatin include cathepsins D and E, as well as the enzyme napsin. However, immunoblots of concentrated urine samples using selective cathepsin and napsin antibodies failed to match protein expression to the increased activities in the diabetic rats. Finally, we assessed peptidase activity in isolated cortical slices from diabetic mRen2 to determine the extent of enzyme release. Aspartyl peptidase activity was readily detectable in the perfusate of the isolated kidney [6 ± 0.3 pmols Mca per min release, n=3] and completely inhibited by pepstatin suggesting that the urinary activity is of renal origin. We conclude that a pepstatin-sensitive aspartyl peptidase, potentially distinct from cathepsin D/E and napsin may constitute an early marker of renal injury in the diabetic hypertensive mRen2 strain.

New twists for an old turning illusion

A Vernier-offset illusion induced by rotating lines, introduced by Matin et al (1976 Perception & psychophysics 20 138-142) was re-examined using onset, offset, and reverse trajectories inspired by flash-lag illusion research, with both Vernier and alignment-with-vertical judgments being recorded. The pattern of illusions found was generally in agreement with a differential latency of stimulus ends account described by those authors, although certain variants of modern spatial projection theories, and a differential latency of attribute account, could also accommodate much of the data.

Practical considerations for conducting ecotoxicity test methods with manufactured nanomaterials: what have we learnt so far?

This review paper reports the consensus of a technical workshop hosted by the European network, NanoImpactNet (NIN). The workshop aimed to review the collective experience of working at the bench with manufactured nanomaterials (MNMs), and to recommend modifications to existing experimental methods and OECD protocols. Current procedures for cleaning glassware are appropriate for most MNMs, although interference with electrodes may occur. Maintaining exposure is more difficult with MNMs compared to conventional chemicals. A metal salt control is recommended for experiments with metallic MNMs that may release free metal ions. Dispersing agents should be avoided, but if they must be used, then natural or synthetic dispersing agents are possible, and dispersion controls essential. Time constraints and technology gaps indicate that full characterisation of test media during ecotoxicity tests is currently not practical. Details of electron microscopy, dark-field microscopy, a range of spectroscopic methods (EDX, XRD, XANES, EXAFS), light scattering techniques (DLS, SLS) and chromatography are discussed. The development of user-friendly software to predict particle behaviour in test media according to DLVO theory is in progress, and simple optical methods are available to estimate the settling behaviour of suspensions during experiments. However, for soil matrices such simple approaches may not be applicable. Alternatively, a Critical Body Residue approach may be taken in which body concentrations in organisms are related to effects, and toxicity thresholds derived. For microbial assays, the cell wall is a formidable barrier to MNMs and end points that rely on the test substance penetrating the cell may be insensitive. Instead assays based on the cell envelope should be developed for MNMs. In algal growth tests, the abiotic factors that promote particle aggregation in the media (e.g. ionic strength) are also important in providing nutrients, and manipulation of the media to control the dispersion may also inhibit growth. Controls to quantify shading effects, and precise details of lighting regimes, shaking or mixing should be reported in algal tests. Photosynthesis may be more sensitive than traditional growth end points for algae and plants. Tests with invertebrates should consider non-chemical toxicity from particle adherence to the organisms. The use of semi-static exposure methods with fish can reduce the logistical issues of waste water disposal and facilitate aspects of animal husbandry relevant to MMNs. There are concerns that the existing bioaccumulation tests are conceptually flawed for MNMs and that new test(s) are required. In vitro testing strategies, as exemplified by genotoxicity assays, can be modified for MNMs, but the risk of false negatives in some assays is highlighted. In conclusion, most protocols will require some modifications and recommendations are made to aid the researcher at the bench.

Neuronal nitric oxide synthase inhibition improves diastolic function and reduces oxidative stress in ovariectomized mRen2.Lewis rats

OBJECTIVE

The loss of estrogen in mRen2.Lewis rats leads to an exacerbation of diastolic dysfunction. Because specific neuronal nitric oxide synthase (nNOS) inhibition reverses renal damage in the same model, we assessed the effects of inhibiting neuronal nitric oxide on diastolic function, left ventricular remodeling, and the components of the cardiac nitric oxide system in ovariectomized (OVX) and sham-operated mRen2.Lewis rats treated with N5-(1-imino-3-butenyl)-L-ornithine (L-VNIO; 0.5 mg/kg per day for 28 d) or vehicle (saline).

METHODS

Female mRen2.Lewis rats underwent either bilateral oophorectomy (OVX; n = 15) or sham operation (or surgical procedure) (sham; n = 19) at 4 weeks of age. Beginning at 11 weeks of age, the rats were randomized to receive either L-VNIO or vehicle.

RESULTS

The surgical loss of ovarian hormones, particularly estrogen, led to exacerbated hypertension, impaired myocardial relaxation, diminished diastolic compliance, increased perivascular fibrosis, and increased relative wall thickness. The cardiac tetrahydrobiopterin-to-dihydrobiopterin levels were lower among OVX rats compared with sham-operated rats, and this altered cardiac biopterin profile was associated with enhanced myocardial superoxide production and decreased nitric oxide release. L-VNIO decreased myocardial reactive oxygen species production, increased nitrite concentrations, attenuated cardiac remodeling, and improved diastolic function.

CONCLUSIONS

Impaired relaxation, diastolic stiffness, and cardiac remodeling were found among OVX mRen2.Lewis rats. A possible mechanism for this unfavorable cardiac phenotype may have resulted from a deficiency in available tetrahydrobiopterin and subsequent increase in nNOS-derived superoxide and reduction in nitric oxide synthase metabolites within the heart. Selective nNOS inhibition with L-VNIO attenuated cardiac superoxide production and limited remodeling, leading to improved diastolic function in OVX mRen2.Lewis rats.

Exploring a brightness-drag illusion

A sudden luminance increment on a moving stimulus was perceived significantly along the trajectory, in the direction of motion, from its displayed position. A nonlinear relationship with stimulus speed, for a Fröhlich-like illusion, but not for the luminance-increment illusion, challenges certain models of spatial mislocalisation and argues for different processes underlying the two illusions.

The Magnocellular visual pathway and the flash-lag illusion

Determining how the visual system locates moving stimuli continues to be an experimental and theoretical challenge. By making a moving visual stimulus equiluminant with its background, and immersing it in luminance noise, the spatial lead it normal enjoys over a flashed stimulus (the flash-lag illusion) was completely eliminated (the illusion was actually reversed for 6 out of 11 participants). As this manipulation is typically used to reduce Magnocellular (M) visual pathway processing, this is strong evidence that processing in this pathway advances the moving stimulus' perceived position. However, when the flashed stimulus was also made equiluminant in luminance noise, the illusion reappeared, indicating that M pathway processing contributed to its perception too. The presence of the illusion when both stimuli were equiluminant in luminance noise indicates that the illusion can be generated in the absence of M cell activation. To explicate the result with moving stimuli, we displayed two adjacent moving stimuli, one luminance-modulated, and the other equiluminant in noise. The latter was perceived to significantly lag the former (an 'M-P-Hess' illusion), and 39% of the difference in flash-lag illusions, with comparable moving stimulus contrasts, could be accounted for by this illusion.

Characterization of a Moraxella species that causes epistaxis in macaques

Bacteria of the genus Moraxella have been isolated from a variety of mammalian hosts. In a prior survey of bacteria that colonize the rhesus macaque nasopharynx, performed at the Tulane National Primate Research Center, organisms of the Moraxella genus were isolated from animals with epistaxis, or "bloody nose syndrome." They were biochemically identified as Moraxella catarrhalis, and cryopreserved. Another isolate was obtained from an epistatic cynomolgus macaque at the U.S. Army Medical Research Institute of Infectious Diseases. Based on differences in colony and cell morphologies between rhesus and human M. catarrhalis isolates, we hypothesized that the nonhuman primate Moraxella might instead be a different species. Despite morphological differences, the rhesus isolates, by several biochemical tests, were indistinguishable from M. catarrhalis. Analysis of the cynomolgus isolate by Vitek 2 Compact indicated that it belonged to a Moraxella group, but could not differentiate among species. However, sequencing of the 16S ribosomal RNA gene from four representative rhesus isolates and the cynomolgus isolate showed closest homology to Moraxella lincolnii, a human respiratory tract inhabitant, with 90.16% identity. To examine rhesus macaques as potential hosts for M. catarrhalis, eight animals were inoculated with human M. catarrhalis isolates. Only one of the animals was colonized and showed disease, whereas four of four macaques became epistatic after inoculation with the rhesus Moraxella isolate. The nasopharyngeal isolates in this study appear uniquely adapted to a macaque host and, though they share many of the phenotypic characteristics of M. catarrhalis, appear to form a genotypically distinct species.

Prenatal betamethasone exposure alters renal function in immature sheep: sex differences in effects

Synthetic glucocorticoids are commonly given to pregnant women when premature delivery threatens. Antenatal administration of clinically relevant doses of betamethasone to pregnant sheep causes sex-specific compromises of renal function and increases in blood pressure in adult offspring. However, it is unclear whether such effects are present in immature lambs. Therefore, the aims of the present study were to determine whether antenatal betamethasone at 80-81 days of gestation increases blood pressure and adversely impacts renal function in adolescent ewes and rams. Prenatal steroid exposure increased blood pressure significantly in the young male (84 +/- 2 vs. 74 +/- 3 mmHg) and female sheep (88 +/- 5 vs. 79 +/- 4), but it did not alter basal glomerular filtration rate, renal blood flow (RBF), or sodium excretion in either sex. However, antenatal betamethasone exposure blocked increases in RBF (P = 0.001), and enhanced excretion of an acute Na load (P < 0.05) in response to systemic infusions of angiotensin (ANG)-(1-7) at 10 pmol.kg(-1).min(-1) in males. In females, the natriuretic response to combined ANG-(1-7), and Na load was significantly altered by prenatal betamethasone exposure. These findings indicate that blood pressure is increased in immature animals in response to antenatal steroid exposure and that sex-specific effects on renal function also exist. These changes may reflect greater risk for further loss of renal function with age.