Assessing the Impact of Chemical Algae Management Strategies on Anurans and Aquatic Communities

Pond management with chemical and biological agents that reduce overgrowth of algae is an important means of maintaining water quality in residential ponds, yet the effects on nontarget species are not fully understood. We assessed the impact of Aquashade (a common nontoxic pond dye) and copper sulfate (a toxic algaecide) on American toad (Anaxyrus americanus), northern leopard frog (Lithobates pipiens), and Cope's gray treefrog (Hyla chrysoscelis) metamorphosis in outdoor mesocosm experiments. We also evaluated the relative impact of tadpole grazing versus chemical treatment on phytoplankton and periphyton abundance. We found no significant effects of pond management treatment on anuran metamorphosis, suggesting that addition of Aquashade and copper sulfate at tested concentrations does not significantly impact anurans under these experimental conditions. Interestingly, we found that the presence of tadpoles more strongly reduced algal abundance than Aquashade or copper sulfate by significantly decreasing phytoplankton and periphyton abundance over time. The present study suggests that anuran tadpoles may be effective at maintaining water quality, and that Aquashade and copper sulfate may have minimal effects on amphibian metamorphosis. Environ Toxicol Chem 2023;42:213-224. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Evaluating the role of body size and habitat type in movement behavior in human‐dominated systems: A frog's eye view

Animal movement is a key process that connects and maintains populations on the landscape, yet for most species, we do not understand how intrinsic and extrinsic factors interact to influence individual movement behavior.

Land‐use/land‐cover changes highlight that connectivity among populations will depend upon an individual's ability to traverse habitats, which may vary as a result of habitat permeability, individual condition, or a combination of these factors.

We examined the effects of intrinsic (body size) and extrinsic (habitat type) factors on desiccation tolerance, movement, and orientation in three anuran species (American toads, Anaxyrus americanus; northern leopard frogs, Lithobates pipiens; and Blanchard's cricket frogs, Acris blanchardi) using laboratory and field studies to connect the effects of susceptibility to desiccation, size, and movement behavior in single‐habitat types and at habitat edges.

Smaller anurans were more vulnerable to desiccation, particularly for species that metamorphose at relatively small sizes. Habitat type had the strongest effect on movement, while body size had more situational and species‐specific effects on movement. We found that individuals moved the farthest in habitat types that, when given the choice, they oriented away from, suggesting that these habitats are less favorable and could represent barriers to movement.

Overall, our work demonstrated that differences in habitat type had strong impacts on individual movement behavior and influenced choices at habitat edges. By integrating intrinsic and extrinsic factors into our study, we provided evidence that population connectivity may be influenced not only by the habitat matrix but also by the condition of the individuals leaving the habitat patch.

A Vasopressin-Induced Change in Prostaglandin Receptor Subtype Expression Explains the Differential Effect of PGE2 on AQP2 Expression

Arginine vasopressin (AVP) stimulates the concentration of renal urine by increasing the principal cell expression of aquaporin-2 (AQP2) water channels. Prostaglandin E₂ (PGE₂) and prostaglandin_2α (PGF_2α) increase the water absorption of the principal cell without AVP, but PGE₂ decreases it in the presence of AVP. The underlying mechanism of this paradoxical response was investigated here. Mouse cortical collecting duct (mkpCCD_c14) cells mimic principal cells as they endogenously express AQP2 in response to AVP. PGE₂ increased AQP2 abundance without desmopressin (dDAVP), while in the presence of dDAVP, PGE₂, and PGF_2α reduced AQP2 abundance. dDAVP increased the cellular PGD₂ and PGE₂ release and decreased the PGF_2α release. MpkCCD cells expressed mRNAs for the receptors of PGE₂ (EP1/EP4), PGF₂ (FP), and TxB₂ (TP). Incubation with dDAVP increased the expression of EP1 and FP but decreased the expression of EP4. In the absence of dDAVP, incubation of mpkCCD cells with an EP4, but not EP1/3, agonist increased AQP2 abundance, and the PGE₂-induced increase in AQP2 was blocked with an EP4 antagonist. Moreover, in the presence of dDAVP, an EP1/3, but not EP4, agonist decreased the AQP2 abundance, and the addition of EP1 antagonists prevented the PGE₂-mediated downregulation of AQP2. Our study shows that in mpkCCD_c14 cells, reduced EP4 receptor and increased EP1/FP receptor expression by dDAVP explains the differential effects of PGE₂ and PGF_2α on AQP2 abundance with or without dDAVP. As the V2R and EP4 receptor, but not the EP1 and FP receptor, can couple to Gs and stimulate the cyclic adenosine monophosphate (cAMP) pathway, our data support a view that cells can desensitize themselves for receptors activating the same pathway and sensitize themselves for receptors of alternative pathways.

Technological Advances to Address Current Issues in Entomology: 2020 Student Debates

The 2020 Student Debates of the Entomological Society of America (ESA) were live-streamed during the Virtual Annual Meeting to debate current, prominent entomological issues of interest to members. The Student Debates Subcommittee of the National ESA Student Affairs Committee coordinated the student efforts throughout the year and hosted the live event. This year, four unbiased introductory speakers provided background for each debate topic while four multi-university teams were each assigned a debate topic under the theme 'Technological Advances to Address Current Issues in Entomology'. The two debate topics selected were as follows: 1) What is the best taxonomic approach to identify and classify insects? and 2) What is the best current technology to address the locust swarms worldwide? Unbiased introduction speakers and debate teams began preparing approximately six months before the live event. During the live event, teams shared their critical thinking and practiced communication skills by defending their positions on either taxonomical identification and classification of insects or managing the damaging outbreaks of locusts in crops.

Phase 1 trial of ralimetinib (LY2228820) with radiotherapy plus concomitant temozolomide in the treatment of newly diagnosed glioblastoma

BACKGROUND AND PURPOSE

This phase 1 trial aimed to determine the maximum tolerated dose (MTD; primary objective) of a p38-MAPK inhibitor, ralimetinib, with radiotherapy (RT) and chemotherapy (TMZ), in the treatment of newly diagnosed glioblastoma (GBM) patients.

MATERIALS AND METHODS

The study was designed as an open-label dose-escalation study driven by a Tite-CRM design and followed by an expansion cohort. Ralimetinib was administered orally every 12 h, 7 days a week, for 2 cycles of 2 weeks at a dose of 100, 200 or 300 mg/12 h. Patients received ralimetinib added to standard concurrent RT (60 Gy in 30 fractions) with TMZ (75 mg/m²/day) and 6 cycles of adjuvant TMZ (150-200 mg/m² on days 1-5 every 28 days).

RESULTS

The MTD of ralimetinib was 100 mg/12 h with chemoradiotherapy. The three patients treated at 200 mg/12 h presented a dose-limiting toxicity: one patient had a grade 3 face edema, and two patients had a grade 3 rash and grade 3 hepatic cytolysis (66%). Of the 18 enrolled patients, 15 received the MTD of ralimetinib. At the MTD, the grade ≥ 3 adverse events during concomitant chemoradiotherapy were hepatic cytolysis (2/15 patients), dermatitis/rash (1/15), lymphopenia (1/15) and nausea/vomiting (1/15). No interaction of TMZ and ralimetinib when administrated concomitantly has been observed. Inhibition of pMAPKAP-K2 (-54%) was observed in peripheral blood mononuclear cells.

CONCLUSION

This phase 1 trial is the first trial to study the combination of a p38-MAPK inhibitor, ralimetinib, with radiotherapy (RT) and chemotherapy (TMZ), in the treatment of newly diagnosed glioblastoma (GBM) patients. The MTD of ralimetinib was 100 mg/12 h. The most frequent dose-limiting toxicities were hepatic cytolysis and rash.

Prilling of API/fatty acid suspensions: Screening of additives for drug release modification

Current study screened additives which could modify the drug release from prills made of an active pharmaceutical ingredient/fatty acid (API/FA) suspension, without negatively influencing the processability and/or stability of the formulation. Therefore, 11 additives (i.e. emulsifiers, pore-formers and FA-based lubricants) were added in a 20% concentration to a paracetamol/behenic acid formulation. Two additives, Kolliphor® P338 and P407 provided complete drug release in less than 1 h, as their thermoreversible gel formation resulted in a disintegration of the prills. Lower Kolliphor® P338 or P407 concentrations (2.5-10%) resulted in a complete but slower drug release in 24 h as the prills no longer disintegrated and the release mechanism was dominated by pore-formation. Prills with a robust drug release profile (i.e. independent of pH and surfactant concentration of the dissolution medium) were obtained after the addition of ≥5% Kolliphor® P338 or P407 to the FA-based formulation. Based on a 6-month stability study, it was concluded that Kolliphor® P407 was a suitable additive to modify the drug release profile of API/FA suspension-based prills when formulations were stored below 25 °C at low relative humidity.

Prilling of API/fatty acid suspensions: Processability and characterisation

Current study evaluated the processability and characteristics of prills made of an active pharmaceutical ingredient/fatty acid (API/FA) suspension instead of previously studied API/FA solutions to enlarge the application field of prilling. Metformin hydrochloride (MET) and paracetamol (PAR) were used as model APIs while both the effect of drug load (10-40%) and FA chain length (C14-C22) were evaluated. API/FA suspensions were processable on lab-scale prilling equipment without thermal degradation, nozzle obstruction or sedimentation in function of processing time. The collected prills were spherical (AR ≥ 0.898) with a smooth surface (sphericity ≥ 0.914) and a particle size of ±2.3 mm and 2.4 mm for MET and PAR prills, respectively, independent of drug load and/or FA chain length. In vitro drug release evaluation revealed a faster drug release at higher drug load, higher API water solubility and shorter FA chain length. Solid state characterisation via XRD and Raman spectroscopy showed that API and FA crystallinity was maintained after thermal processing via prilling and during storage. Evaluation of the similarity factor indicated a stable drug release (f₂ > 50) from MET and PAR prills after 6 months storage at 25 °C or 40 °C.

P14.76 Characteristics of anaplastic oligodendrogliomas short-term survivors: a POLA network study

BACKGROUND

Although patients with 1p/19q codeleted anaplastic oligodendrogliomas (AO) usually have a prolonged survival, some patients have a poorer outcome. The aim of the present study was to analyze their characteristics.

MATERIAL AND METHODS

The characteristics of AO patients with a survival < 5 years included in the POLA network were analyzed and compared to those of AO patients with a survival > 5 years.

RESULTS

In January 2019, among the 519 patients AO patients included in the POLA network, 55 patients were short-term survivors and 146 patients had a survival > 5 years. Among the 55 AO short-term survivors, 44 patients (80%) died from tumor progression and 11 patients (20%) from another cause (suicide n=2, toxicity n=2, intercurrent disease n=6, other n=1). Compared to > 5 years survivors, short-term survivors were older (57 years vs 48 years, p<0.001) and less frequently presented with isolated seizures (9% vs 33%, p=0.0017). They presented with tumors that more frequently involved multiple lobes (66% vs 47%, p=0.03), had a higher rate of nuclear atypia (80% vs 48%, p<0.001), a higher proliferative index (Ki67, 26% vs 18%, p<0.001), a higher level of p53 expression (10.8% vs 3.9% p<0.001), and had a higher rate of chromosomal abnormalities (91% vs 71% p=0.008). Compared to > 5 years survivors, short-term survivors less frequently underwent a surgical resection (64% vs 89% p<0.001) and their initial treatment more frequently consisted in temozolomide chemotherapy alone (41% vs 20% p=0.008).

CONCLUSION

AO short-term survivors are associated with distinct clinical, radiological, histological and molecular characteristics at diagnosis.

P14.81 Importance of early spectral variations during a longitudinal 60-month follow-up MRI and 1H-MRS in 135 treated glioblastoma patients

BACKGROUND

To better understand glioblastomas tumor metabolism and metabolic responses to chemotherapy, radiotherapy and antiangiogenic treatments during a longitudinal 60-month follow-up MRI and 1H-MRS in 135 treated glioblastoma patients.

MATERIAL AND METHODS

135 patients all biopsied and treated by surgery and STUPP protocol underwent MRI (Sagittal T1, FLAIR, T2*, Diffusion, Perfusion, CoronalT2 and 3DT1 post-Gadolinium) and 1H-MRS (PRESS with multiple TEs: 35ms, 144ms and 288ms on a 6 to 12cm3 volume) exams on 1.5T and 3T GEMS. 92/135 patients underwent resection. MRS data were processed under jMRUI yielding amplitudes, areas under curves and ratios of tCho/tCr, tNAA/tCr, Lip+Lact/tCr, Lact/tCr, Glc/tCr, Glx/tCr and Gln/tCr. Statistical analysis of longitudinal MRI perfusion and spectroscopic data (every 2–3 months above 30 months and 6–9 months over).

RESULTS

Spectroscopic profiles and ratios improve under STUPP protocol and then worsen depending on the percentage of resection. Biopsied patients: a progressive decrease in ratios of tCho/tCr (0–24 months), Lact/tCr (0–18 months) and Glc/tCr (0–18 months) and Glx/tCr (0–12 months) and then increase at respectively 24, 18, 28 and18 months. Resected patients: a progressive decrease in ratios of tCho/tCr (0–9 months), Lact/tCr (0–15 months) and Glc/tCr (0–15 months) and Glx/tCr (0 and 18 months) and then increase at respectively 32, 20, 18 and 24 months. MRI Gadolinium enhancing tumor and necrosis volumes, Diffusion and FLAIR volumes changed less compared to spectroscopic profiles and ratios which do change more.

CONCLUSION

1H-MRS allows non-invasive follow-up of treated glioblastomas tumors. Despite inter-subjects variability, spectroscopic and metabolic changes often come well before clinical deterioration and sometimes before clinical improvement. Therefore, 1H-MRS could be more sensitive and could detect changes earlier than MRI and sometimes is predictive of survival and response to treatment. The analysis of spectral profiles of long survivors is interesting and could help to better understand tumor metabolism and therapeutic responses.

P14.91 Study glycolytic metabolism in 1H-MRS monovoxel in the most aggressive part of 62 glioblastomas before and after 18 months of treatment

BACKGROUND

To study the relationship between glycolytic metabolism, tumor proliferation, survival and treatment response in patients with glioblastoma (GBM).

MATERIAL AND METHODS

Patients: 62 patients with glioblastoma, all having a STUPP Protocol (radiotherapy and concomitant chemotherapy), were selected and separated into 2 groups: Biopsies (30) and resections (32). In total, 269 NMR spectra (PRESS at GE 1.5T and 3T; multi-TEs TE=35ms and TE=144ms) were acquired. Processing: MRS data were processed with jMRUI software and quantitated using HLSVD and QUEST algorithms. Statistical analysis of longitudinal MRS data (every 3 months)

RESULTS

1H-MRS glucose (Glc/tCr) and lactate (Lac/tCr) measurements are highly correlated before the beginning of treatment. This correlation is less obvious after 3, 6, 9 and 12 months of treatment. Proliferation is also strongly correlated with Lactate and Glucose before the beginning of treatment in both groups, whereas these correlations decrease in resected patients.The variability of ratios follow-up is higher in biopsied patients. Tumoral proliferation (tCho/tCr) and Glucose ratio (Glc/tCr) levels decreased along the follow-up. Although, the Lac/tCr ratio progressively decreased, its level remains high until 6 months. After 15 months of treatment, glucose increased although the lactate decreased.

CONCLUSION

The study of glycolytic metabolism in GBM could be used to evaluate the response to treatment. Being able to have a treatment response biomarker at 3 months, especially for patients who could not be resected could help to monitor and adapt treatment. The increase of Glucose at the end of the follow-up shows the interest of spectral and metabolic follow-up of glioblastoma after 18 months of treatment.

P14.122 Integrin α5 is a poor prognostic factor in patients with glioblastoma treated by the Stupp protocol

BACKGROUND

Integrin α5β1 was suggested to be involved in glioblastoma (GBM) aggressiveness through preclinical studies and genomic analysis of several cohorts of patients. However, protein expression data are still missing to confirm this hypothesis. Our aim was to investigate the prognostic value of integrin α5 protein expression level in GBM.

MATERIAL AND METHODS

We retrospectively determined the protein expression level of integrin α5 using immunochemistry in tumors from patients treated in 6 French centers. Paraffin sections of GBM were labeled by immunofluorescence and analyzed by confocal microscopy. The corresponding clinical and survival data have been identified and analyzed. The primary end-point was overall survival (OS).

RESULTS

Out of 297 patients newly diagnosed with GBM between 2006 and 2013, 152 met the inclusion criteria (scheduled for initial treatment with the Stupp protocol, age > 18 years) and 95 tumor samples were suitable for immunohistochemical analysis. The median age is 58 years, (64 men, 34 women). Most of patients received macroscopic (43%) or partial (36%) surgery. In univariate analysis using the Log Rank test, high integrin α5 expression level was associated with poor prognosis (PFS: hazard ratio (HR) = 1,696, p=0,0355; OS: HR=1,598, p = 0,0508). Corresponding median OS were 15,6 versus 19,2 months. Similarly, OS was significantly reduced with age (> 60 years), lower resection degree, higher RPA (recursive partitioning analysis) score and non-methylated MGMT (O-6-methylguanine-DNA methyltransferase) promoter. In the subgroup of patients who received the full initial protocol (temozolomide treatment together with radiotherapy and later as adjuvant treatment; n=58) mean OS was strongly reduced when integrin α5 expression level was high (15,6 versus 22,8 months, p=0,0162) suggesting an impact of integrin signaling on temozolomide response in GBM.

CONCLUSION

Our study validates for the first time that the high protein level expression of α5 integrin is associated with poor prognosis in GBM. It also confirms its potential as a therapeutic target and its likely role in resistance to temozolomide as previously shown in preclinical study.

P14.92 Study of Glutaminergic and Glutamatergic Metabolism in 1H-MRS Monovoxel in the Most Aggressive Part of 62 Glioblastoma Before and After 18 months Treatment

BACKGROUND

To study the relationships between glutaminergic metabolism (Glx/tCr), tumor proliferation (tCho/tCr) and other metabolic activities in patients with glioblastoma (GBM).

MATERIAL AND METHODS

Patients: 62 patients with glioblastoma, all having a STUPP Protocol (radiotherapy and concomitant chemotherapy), were selected and separated into 2 groups: Biopsies (30) and resections (32). In total, 269 NMR spectra (PRESS at GE 1.5T and 3T; multi-TEs TE=35ms and TE=144ms) were acquired. Processing: MRS data were processed with jMRUI software and quantitated using HLSVD and QUEST algorithms. Statistical analysis of longitudinal MRS data (every 3 months)

RESULTS

Glx/tCr and Lac/tCr ratios are correlated with the tumoral proliferation (tCho/tCr) before the beginning of treatment. This correlations decreases over time in biopsied and resected patients. In biopsied patients, the evolution of lactate (Lac/tCr) and Glx (Glx/tCr) ratios is similar along the follow-up with a progressive decrease in tumor proliferation (tCho/tCr). However, in resected patients, the evolution of lactate (Lac/tCr) and Glx (Glx/tCr) ratios is similar until 6 months and differ above: a progressive decrease of Lac/tCr and Glx/tCr until 18 months with a higher level of Glx/tCr.

CONCLUSION

Despite the difficulties to separate glutamine from glutamate (post-processing improvement is ongoing), spectroscopic measurements of Glx changes before clinical deterioration. The increase of Glx is longer (in time) than the Lactate increase after 6 months of treatment in the resected patients could be predictive of the observed increase of tumor proliferation at 12 months of treatment.The study of glutaminergic metabolism in the GBM could be used to evaluate the response to treatment. Being able to predict the increase of tumor proliferation in resected patients could allow a faster treatment adaptation.

Long-term survival in patients with recurrent glioblastoma treated with bevacizumab: a multicentric retrospective study

PURPOSE

Recurrence of glioblastoma (GB) occurs in most patients after standard concomitant temozolomide-based radiochemotherapy (CTRC). Bevacizumab (BV), an anti-VEGF antibody, has an effect on progression-free survival (PFS) but not on overall survival (OS). However, a small part of the patients experience a survival, longer than expected. This retrospective study aims to characterize long responder (LR) patients treated with BV for a first or second GBM recurrence.

METHODS

Medical records from patients (814) who received BV for a first or second recurrence of primary glioblastoma between September 2010 and September 2015, and initially treated by CTRC were analyzed. Patients, who had at least a stable disease according to RANO criteria at 12 months from the start of BV, were included. Patients who had, a secondary GB, or received BV in neoadjuvant or adjuvant setting were excluded.

RESULTS

We focused on 65 LR patients without progression 12 months after the first injection of BV (8%). Median PFS was 21.7 months [95% CI (19.3; 27.2)] and median OS was 31.1 months [95% CI (24.3; 37.5)] from the start of BV. No prognostic factor was associated with OS in multivariate analysis. Karnofsky performance status, neurological status and corticosteroid dose were stable at 12 months.

CONCLUSIONS

Our results highlight that among patients receiving bevacizumab in first or second recurrence, one patient out of twelve could be classified as LR. A median OS of 31.1 months from the start of BV could be expected in this subpopulation. These findings reinforce the potential benefit of the use of BV in the situation of recurrence. 256 words.

Counteracting vasopressin-mediated water reabsorption by ATP, dopamine, and phorbol esters: mechanisms of action

Water homeostasis is regulated by a wide variety of hormones. When in need for water conservation, vasopressin, released from the brain, binds renal principal cells and initiates a signaling cascade resulting in the insertion of aquaporin-2 (AQP2) water channels in the apical membrane and water reabsorption. Conversely, hormones, including extracellular purines and dopamine, antagonize AVP-induced water permeability, but their mechanism of action is largely unknown, which was investigated here. Addition of these hormones to mpkCCD cells decreased total and plasma membrane abundance of AVP-induced AQP2, partly by increasing its internalization to vesicles and lysosomal degradation. This internalization was ubiquitin dependent, because the hormones increased AQP2 ubiquitination, and the plasma membrane localization of AQP2-K270R, which cannot be monoubiquitinated, was unaffected by these hormones. Both hormones also increased AQP2 phosphorylation at S261, which followed ubiquitination, but was not essential for hormone-induced AQP2 degradation. A similar process occurs in vivo, as incubation of dDAVP-treated kidney slices with both hormones also resulted in the internalization and S261 phosphorylation of AQP2. Both hormones also reduced cAMP and AQP2 mRNA levels, suggesting an additional effect on AQP2 gene transcription. Interestingly, phorbol esters only reduced AQP2 through the first pathway. Together, our results indicate that ATP and dopamine counteract AVP-induced water permeability by increasing AQP2 degradation in lysosomes, preceded by ubiquitin-dependent internalization, and by decreasing AQP2 gene transcription by reducing the AVP-induced cAMP levels.

Regulation of AQP2 localization by S256 and S261 phosphorylation and ubiquitination

Vasopressin-induced water reabsorption coincides with phosphorylation of aquaporin-2 (AQP2) at S256 (pS256), dephosphorylation at S261, and its translocation to the apical membrane, whereas treatment with the phorbol ester 12-tetradecanoylphorbol-13-acetate (TPA) induces AQP2 ubiquitination at K270, its internalization, and lysosomal degradation. In this study we investigated the relationship between S256 and S261 phosphorylation in AQP2 and its ubiquitination and trafficking in MDCK cells. Forskolin stimulation associated with increased pS256 and decreased pS261 AQP2, indicating that MDCK cells are a good model. After forskolin stimulation, TPA-induced ubiquitination of AQP2 preceded phosphorylation of AQP2 at S261, which in the first instance occurred predominantly on ubiquitinated AQP2. Forskolin-induced changes in pS261 were also observed for AQP2-S256A and AQP2-S256D, which constitutively localize in vesicles and the apical membrane, respectively. Although pS261 varies with forskolin as with wild-type AQP2, AQP2-S256A is not increased in its ubiquitination. Our data reveal that pS261 occurred independently of AQP2 localization and suggest that pS261 follows ubiquitination and endocytosis and may stabilize AQP2 ubiquitination and intracellular localization. The absence of increased ubiquitination of AQP2-S256A indicates that its intracellular location is due to the lack of pS256. Furthermore, AQP2-S261A and AQP2-S261D localized to vesicles, which was due to their increased ubiquitination, because changing K270 into Arg in both mutants resulted in their localization in the apical membrane. Although still increased in its ubiquitination, AQP2-S256D-S261D localized in the apical membrane. AQP2-S256D-K270R-Ub, however, localized to intracellular vesicles. Although our localization of AQP2-S261A/D is different from that of others, these data indicate that constitutive S256 phosphorylation counterbalances S261D-induced ubiquitination and internalization or changes its structure to allow distribution to the apical membrane. The vesicular localization of AQP2-S256D-K270R-Ub, however, indicates that the dominant apical sorting of S256D can again be overruled by constitutive ubiquitination. These data indicate that the membrane localization of AQP2 is determined by the balance of the extents of phosphorylation and ubiquitination.

A LabVIEW® based generic CT scanner control software platform

UGCT, the Centre for X-ray tomography at Ghent University (Belgium) does research on X-ray tomography and its applications. This includes the development and construction of state-of-the-art CT scanners for scientific research. Because these scanners are built for very different purposes they differ considerably in their physical implementations. However, they all share common principle functionality. In this context a generic software platform was developed using LabVIEW® in order to provide the same interface and functionality on all scanners. This article describes the concept and features of this software, and its potential for tomography in a research setting. The core concept is to rigorously separate the abstract operation of a CT scanner from its actual physical configuration. This separation is achieved by implementing a sender-listener architecture. The advantages are that the resulting software platform is generic, scalable, highly efficient, easy to develop and to extend, and that it can be deployed on future scanners with minimal effort.

Effect of the cGMP pathway on AQP2 expression and translocation: potential implications for nephrogenic diabetes insipidus

BACKGROUND

Arginine vasopressin (AVP) binding to the V2 receptor (V2R) in renal collecting duct principal cells induces a cAMP signalling cascade resulting in the activation of protein kinase A (PKA), translocation of aquaporin-2 (AQP2) to the apical membrane and an increase in AQP2 expression. Consequently, concentration of urine is initiated. X-linked nephrogenic diabetes insipidus (NDI), characterized by the inability to concentrate urine in response to AVP, is caused by mutations in the V2R gene. Initiation of AQP2 translocation, while circumventing the V2R-cAMP-PKA pathway has been suggested as a putative therapy for these patients. In this respect, the activation of a cAMP-independent and cGMP-dependent pathway for AQP2 membrane insertion by different cyclic guanosine monophosphate (cGMP) pathway activators, such as atrial natriuretic peptide (ANP), l-arginine and 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP), has been put forward. However, it is unclear whether they can increase AQP2 expression.

METHODS

Mouse cortical collecting duct (mpkCCD) cells were incubated with ANP, l-arginine and 8-Br-cGMP for 2 h and subjected to immunocytochemistry and cell surface biotinylation assays to examine their effect on AQP2 translocation. To test the effect of cGMP pathway activators on AQP2 expression, the mpkCCD cells were treated with dDAVP, ANP and l-arginine for 4 days, or with 8-Br-cGMP for the last day. AQP2 protein levels were determined by immunoblotting.

RESULTS

ANP, l-arginine and 8-Br-cGMP induced the translocation of AQP2 in the mpkCCD cells. However, in contrast to dDAVP, ANP, l-arginine and 8-Br-cGMP did not increase the expression of AQP2.

CONCLUSIONS

Our results suggest that while activators of the cGMP pathway are likely beneficial in the treatment of X-linked NDI, their ability to relieve NDI in the patients may be improved when combined with agents stimulating AQP2 expression.

Realistic expectations: the changing role of paraprofessional health workers in First Nation communities in Canada

CONTEXT

First Nation communities in Canada rely on a mix of non-indigenous professionals and large numbers of indigenous paraprofessionals to deliver healthcare. Formerly allowed to perform controlled acts in emergencies, the direct care role of paraprofessionals is now restricted because of concerns about liability and accountability. As such, they are limited to health promotion and prevention activities.

OBJECTIVES

Focusing on the largest group of indigenous health workers, viz. Community Health Representatives (CHRs), for illustration purposes, this paper (1) examines the evolving role of First Nation health workers, and (2) discusses the proposed introduction of competency-based standards for their education, certification and regulation.

METHODS

The paper is informed by findings from open ended, semi-structured and focus group interviews, as well as qualitative survey data, derived from seven studies done in Ontario, Canada.

OUTCOMES

Paraprofessionals face conflicting and sometimes unrealistic expectations. Past practices have accustomed community members to hands-on care; however, professionals will no longer delegate tasks requiring clinical skills to them. Moreover, First Nation leaders are concerned about liability for their paraprofessional employees' actions. The paper discusses issues related to paraprofessional competence, preparation for practice, and continuing health education. It then presents the National Indian and Inuit Community Health Representatives Organization's proposal to establish a scope of practice and set of competencies that can form the basis for national practice and training standards, accreditation and regulation.

CONCLUSIONS

In Canada or elsewhere, changing practice environments may require adjustments in the roles played by indigenous health workers. The case of First Nation Community Health Representatives illustrates a strategy for role transformation.

Nucleotides downregulate aquaporin 2 via activation of apical P2 receptors

Vasopressin regulates water reabsorption in the collecting duct, but extracellular nucleotides modulate this regulation through incompletely understood mechanisms. We investigated these mechanisms using immortalized mouse collecting duct (mpkCCD) cells. Basolateral exposure to dDAVP induced AQP2 localization to the apical membrane, but co-treatment with ATP internalized AQP2. Because plasma membrane-bound P2 receptors (P2R) mediate the effects of extracellular nucleotides, we examined the abundance and localization of P2R in mpkCCD cells. In the absence of dDAVP, P2Y(1) and P2Y(4) receptors localized to the apical membrane, whereas P2X(2), P2X(4), P2X(5), P2X(7), P2Y(2), P2Y(11), and P2Y(12) receptors localized to the cytoplasm. dDAVP induced gene expression of P2X(1), which localized to the apical domain, and led to translocation of P2X(2) and P2Y(2) to the apical and basolateral membranes, respectively. In co-expression experiments, P2R activation decreased membrane AQP2 and AQP2-mediated water permeability in Xenopus oocytes expressing P2X(2), P2Y(2,) or P2Y(4) receptors, but not in oocytes expressing other P2R subtypes. In summary, these data suggest that AQP2-mediated water transport is downregulated not only by basolateral nucleotides, mediated by P2Y(2) receptors, but also by luminal nucleotides, mediated by P2X(2) and/or P2Y(4) receptors.

LIP5 interacts with aquaporin 2 and facilitates its lysosomal degradation

Vasopressin binding to the V2 receptor in renal principal cells leads to activation of protein kinase A, phosphorylation of aquaporin 2 (AQP2) at Ser256, and the translocation of AQP2 to the apical membrane, resulting in concentration of the urine. In contrast, phorbol ester-induced activation of protein kinase C pathway leads to ubiquitination of AQP2 at Lys270 and its internalization to multivesicular bodies, where it is targeted for lysosomal degradation or stored for recycling. Because little is known about the regulation of AQP2 trafficking, we used the carboxy-terminal tail of constitutively nonphosphorylated AQP2 (S256A) as a bait for interacting proteins in a yeast two-hybrid assay. We isolated lysosomal trafficking regulator-interacting protein 5 (LIP5) and found that LIP5 interacted with the proximal carboxy-terminal tail (L230-D243) of AQP2 in vitro but not with AQP3 or AQP4, which are also expressed in principal cells. Immunohistochemistry revealed that LIP5 co-localized with AQP2 in principal cells. LIP5 binding occurred independent of the state of Ser256 phosphorylation or Lys270 ubiquitination. LIP5 has been shown to facilitate degradation of the EGF receptor; here, LIP5 seemed to bind this receptor. Knockdown of LIP5 in mouse renal cells (mpkCCD) reduced the phorbol ester-induced degradation of AQP2 approximately two-fold. In summary, LIP5 binds cargo proteins and, considering the role of LIP5 in protein sorting to multivesicular bodies, plays a role in the degradation of AQP2, possibly by reducing the formation of late endosomes.

Congenital nephrogenic diabetes insipidus: what can we learn from mouse models?

Aquaporins (AQPs) are central players in mammalian physiology, allowing efficient water transport through cellular membranes. To date, 13 different aquaporins have been identified in mammals (AQP0-AQP12). Knocking out genes in mice and identification of mutations in the human genes provided important information on the role of AQPs in normal physiology. While the physiological role of many AQPs only becomes clear when the putative function is challenged, the lack of AQP2 directly results in a disease phenotype. Aquaporin 2 is highly expressed in the principal cells of the renal collecting duct, where it shuttles between intracellular storage vesicles and the apical membrane. Upon hypernatraemia or hypovolaemia, the antidiuretic hormone vasopressin (AVP) is released from the pituitary into blood and binds to its type 2 receptor on renal principal cells. This initiates a cAMP signalling cascade resulting in the translocation of AQP2-bearing vesicles to the apical membrane. Subsequently, pro-urinary water reabsorption and urine concentration occurs. This process is reversed by a reduction in circulating AVP levels, which is obtained with the establishment of isotonicity. In humans, mutations in the AQP2 gene cause congenital nephrogenic diabetes insipidus (NDI), a disorder characterized by an inability to concentrate urine in response to vasopressin. Until the recent development of several congenital NDI mouse models, our knowledge on AQP2 regulation was primarily based on in vitro studies. This review focuses on the similarities between the in vitro and in vivo studies and discusses new insights into congenital NDI obtained from the mouse models.

Physiology and pathophysiology of the vasopressin-regulated renal water reabsorption

To prevent dehydration, terrestrial animals and humans have developed a sensitive and versatile system to maintain their water homeostasis. In states of hypernatremia or hypovolemia, the antidiuretic hormone vasopressin (AVP) is released from the pituitary and binds its type-2 receptor in renal principal cells. This triggers an intracellular cAMP signaling cascade, which phosphorylates aquaporin-2 (AQP2) and targets the channel to the apical plasma membrane. Driven by an osmotic gradient, pro-urinary water then passes the membrane through AQP2 and leaves the cell on the basolateral side via AQP3 and AQP4 water channels. When water homeostasis is restored, AVP levels decline, and AQP2 is internalized from the plasma membrane, leaving the plasma membrane watertight again. The action of AVP is counterbalanced by several hormones like prostaglandin E2, bradykinin, dopamine, endothelin-1, acetylcholine, epidermal growth factor, and purines. Moreover, AQP2 is strongly involved in the pathophysiology of disorders characterized by renal concentrating defects, as well as conditions associated with severe water retention. This review focuses on our recent increase in understanding of the molecular mechanisms underlying AVP-regulated renal water transport in both health and disease.

Short-chain ubiquitination mediates the regulated endocytosis of the aquaporin-2 water channel

To regulate mammalian water homeostasis, arginine-vasopressin (AVP) induces phosphorylation and thereby redistribution of renal aquaporin-2 (AQP2) water channels from vesicles to the apical membrane. Vice versa, AVP (or forskolin) removal and hormones activating PKC cause AQP2 internalization, but the mechanism is unknown. Here, we show that a fraction of AQP2 is modified with two to three ubiquitin moieties in vitro and in vivo. Mutagenesis revealed that AQP2 is ubiquitinated with one K63-linked chain at K270 only. In Madin-Darby canine kidney cells, AQP2 ubiquitination occurs preferentially when present in the apical membrane, is transiently increased with forskolin removal or PKC activation, and precedes its internalization. Internalization kinetics assays with wild type (wt) and ubiquitination-deficient (K270R) AQP2 revealed that ubiquitination enhances AQP2 endocytosis. Electron microscopy showed that a translational fusion of AQP2 with ubiquitin (AQP2-Ub) localized particularly to internal vesicles of multivesicular bodies (MVBs), whereas AQP2-K270R largely localized to the apical membrane, early endosomes, and the limiting membrane of MVBs. Consistent with this distribution pattern, lysosomal degradation was extensive for AQP2-Ub, low for AQP2-K270R, and intermediate for wt-AQP2. Our data show that short-chain ubiquitination is involved in the regulated endocytosis, MVB sorting, and degradation of AQP2 and may be the mechanism used by AVP removal and PKC-activating hormones to reduce renal water reabsorption. Moreover, because several other channels are also (short-chain) ubiquitinated, our data suggest that ubiquitination may be a general mediator for the regulated endocytosis and degradation of channels in higher eukaryotes.

Fibronectin is a hypoxia-independent target of the tumor suppressor VHL

The von Hippel-Lindau (VHL) tumor suppressor gene regulates the extracellular matrix by controlling fibronectin deposition. To identify novel VHL target genes, we subjected mRNA from VHL-deficient RCC cells (786-0-pRC) and a transfectant re-expressing wildtype VHL (786-0-VHL) to differential expression profiling. Among the differentially expressed genes, we detected that fibronectin is upregulated in the presence of VHL, while it is not affected by hypoxia. Thus regulation of fibronectin deposition by VHL occurs at the transcriptional level, irrespective of oxygen levels.

Two cases of cross-sensitivity in subjects allergic to paraphenylenediamine following ingestion of Polaronil

We report the cases of 2 women presenting allergy to paraphenylenediamine (PPD). Both patients had a history of eczema that worsened following the ingestion of the antihistamine Polaronil (dexamethasone/dexchlorpheniramine). This clinical presentation could be explained by cross-sensitivity to sulfanilic acid (4-aminobenzene sulfonic acid), a metabolite of sunset yellow (FD&C No. 6). Sunset yellow is an azo dye present in this tablet. Indeed, PPD-allergic subjects may suffer from cross-sensitivity to related compounds, especially to those that can be ingested such as azo dyes. Such compounds are used in some instances by the food and pharmaceutical industries, but their presence is often undisclosed.

BLAST Search Updater: a notification system for new database matches

BLAST Search Updater (BSU) can help molecular biologists perform large numbers of BLAST searches routinely and screen the results for novel matches. The search result files (HTML format) and delta files (novel matches) are WWW viewable and BSU also emails users alignments of new matches.

AVAILABILITY

BSU runs on UNIX machines and is freely available to academic users at http://athena.bioc.uvic.ca/genomes/. Additional figures and description are also available.

CONTACT

cupton@uvic.ca

Viral genome organizer: a system for analyzing complete viral genomes

The viral genome organizer (VGO) is designed to simplify the characterization and annotation of complete viral genomes (particularly those of large poxviruses) and to help researchers discover new genes and detect gene fragmentation. VGO is based on Genotator [Harris, N.L., 1997. Genome Res. 7, 754-762], an annotation workbench designed for the analysis of eukaryotic genomic sequences. VGO automates a number of database search routines (FASTA, BLASTP, PSI-BLAST and TBLASTN), processes the results through a multiple-alignment viewer (MView; [Brown, N.P., Leroy, C., Sander, C. , 1998. Bioinformatics 14, 380-381]) and serves to manage the hundreds of DNA, protein and database search results files that must be organized when dealing with large complete poxviral genomes. It also directs the generation a self-dotplot of the genome by Dotter [Sonnhammer, E.L.L., Durbin, R., 1995. A dot-matrix program with dynamic threshold control suited for genomic DNA and protein sequence analysis. Gene 167: GC1-10. http://www.sanger.ac. uk/Software/Dotter/] to uncover repeated genes and sequences and provides Internet links to programs for generation of restriction maps and analysis of potential PCR primers. The user-friendly graphical interface displays DNA and protein sequences, links to search results, ORFs, stop-start codons, restriction sites and flags of database searches. Currently, VGO and associated programs run in an X-windows environment on commonly available UNIX machines.

Adhesion molecule profiles in atopic dermatitis vs. allergic contact dermatitis: pharmacological modulation by cetirizine

BACKGROUND

Experimental data suggest that there is an imbalance between Th1 and Th2 cells in atopic dermatitis (AD) skin compared to allergic contact dermatitis (ACD). This imbalance (Th2 and Th1 predominance, respectively) implies the production of different cytokines in these two conditions leading to different expression of adhesion molecules on skin endothelial cells.

OBJECTIVE

The expression of VCAM-1 (IL-4/Th2-dependent) and ICAM-1 (INF-gamma/IL-1) on dermal vessels was compared in six patients with AD and six patients with ACD. The effect of cetirizine, a highly selective H1-receptor antagonist on the expressions was studied.

METHODS

Six patients with AD were challenged with Dermatophagoides pteronyssimus (DPT patch tests applied to clinically normal skin) and six patients with ACD challenged in the same way with allergens of the European standard series. Skin biopsies at challenged sites were performed before and 6, 24 and 48 h after challenge. The experiment was carried out under double-blind cross-over conditions during a 4-day treatment with a placebo and cetirizine.

RESULTS

In AD patients, the scores for both VCAM-1 and ICAM-1 were high before and after challenge. In ACD patients, the ICAM-1 score was high at each experimental time, but the VCAM-1 score, which was significantly lower before challenge, increased at 6, 24 and 48 h after challenge. The administration of cetirizine significantly reduced the VCAM-1 expression in AD patients at each experimental time.

CONCLUSION

It is concluded that the increased VCAM-1 expression in AD patients compared to ACD may reflect greater IL-4 and/or IL-13 production in situ. The study also confirms the existence of a modulating effect of cetirizine in vivo on adhesion molecule expression.

Strength through sharing: interdisciplinary teamwork in providing health and social services to northern native communities

The delivery of health and social services in Canada's northern First Nations is undermined by the fact that professionals from outside and para-professionals from the communities often fail to respect one another's capabilities or to understand one another's roles and, consequently, do not work well together. This paper explores the personal, professional, and situational causes, using examples of mental health care in the Sioux Lookout Zone of northwestern Ontario. Arguing that an interdisciplinary team approach is the ideal and, perhaps, the only real way in which essential services can be delivered, the authors suggest ways to achieve more effective collaboration.

Digital image analysis of the effect of topically applied linoleic acid on acne microcomedones

A major pathogenic factor of acne is the disturbed keratinization of the follicular infundibulum. It has been hypothesized that a relative decrease in linoleic acid in the sebum could be responsible, in part, for this. The aim of the present study was objectively to evaluate the effects of topically applied linoleic acid on the size of microcomedones in patients with mild acne. The design was a double-blind placebo-controlled randomized cross-over study. Evaluations were performed by digital image analysis of cyanoacrylate follicular biopsies. There was a significant effect of topically applied linoleic acid on the size of follicular casts and microcomedones, an almost 25% reduction in their overall size being achieved over a 1-month treatment period. In contrast, no change was found at placebo-treated sites. It is concluded that topical linoleic acid might play a role as a comedolytic agent in acne-prone patients.