Genetic redox dysregulation induces behavioural deficits in the adult mouse: an animal model for schizophrenia

Background: Glutathione (GSH), a major cellular redox regulator and antioxidant, is decreased in cerebrospinal fluid and prefrontal cortex of schizophrenia patients. The gene of the key GSH-synthesizing enzyme, glutamate-cysteine ligase, modifier (GCLM) subunit, is associated with schizophrenia, suggesting that the deficit in the GSH system is of genetic origin. Using the GCLM knock-out (KO) mouse as model system with 60% decreased brain GSH levels and, thus, strong vulnerability to oxidative stress, we have shown that GSH dysregulation results in abnormal mouse brain morphology (e.g., reduced parvalbumin, PV, immuno-reactivity in frontal areas) and function. Additional oxidative stress, induced by GBR12909 (a dopamine re-uptake inhibitor), enhances morphological changes even further. Aim: In the present study we use the GCLM KO mouse model system, asking now, whether GSH dysregulation also compromises mouse behaviour and cognition. Methods: Male and female wildtype (WT) and GCLM-KO mice are treated with GBR12909 or phosphate buffered saline (PBS) from postnatal day (P) 5 to 10, and are behaviourally tested at P 60 and older. Results: In comparison to WT, KO animals of both sexes are hyperactive in the open field, display more frequent open arm entries on the elevated plus maze, longer float latencies in the Porsolt swim test, and more frequent contacts of novel and familiar objects. Contrary to other reports of animal models with reduced PV immuno-reactivity, GCLM-KO mice display normal rule learning capacity and perform normally on a spatial recognition task. GCLM-KO mice do, however, show a strong deficit in object-recognition after a 15 minutes retention delay. GBR12909 treatment exerts no additional effect. Conclusions: The results suggest that animals with impaired regulation of brain oxidative stress are impulsive and have reduced behavioural control in novel, unpredictable contexts. Moreover, GSH dysregulation seems to induce a selective attentional or stimulus-encoding deficit: despite intensive object exploration, GCLM-KO mice cannot discriminate between novel and familiar objects. In conclusion, the present data indicate that GSH dysregulation may contribute to the manifestation of behavioural and cognitive anomalies that are associated with schizophrenia.

Prévention des adhérences péricardiques avec une membrane biorésorbable [Prevention of pericardial adhesions with a bioresorbable membrane]

A bioresorbable membrane made of sodium hyaluronate and carboxymethycellulose, has been reported to prevent peritoneal adhesion. This study was designed to test its efficiency in the prevention of pericardial adhesions. Two groups of six pigs (mean weight 72 +/- 8 kg) were chosen for the experiment. The heart was exposed through a left thoracotomy and a wide patch of pericardium was excised. In the test group (n = 6), the left ventricular area without pericardium was divided into two areas: area A where six stitches of Prolene were performed, and area B which was left intact. The membrane was applied on the both areas as well as on the adjacent area covered with pericardium (area C). In the control group (n = 6), the same protocol was performed except for the membrane application. The animals were sacrificed one month later. The adhesion status as well as the visibility of the coronary anatomy was assessed according to severity scores ranging from 0 to 3 for the adhesions and from 0 to 2 for the visibility. The difference between groups was considered significant when p < 0.05. The adhesion score of the area A was 1.7 +/- 0.5 in the test group versus 2.5 +/- 0.5 in the control group (p = 0.02) and the visibility score was 1.3 +/- 0.8 and 2 +/- 0 respectively (p = 0.07). In the area B, the adhesion score was 1 +/- 0 in the test group versus 2 +/- 0.6 in the control group (p = 0.03) and the visibility score was 0.7 +/- 0.5 and 2 +/- 0 respectively (p = 0.001). Lastly, in the area C, the adhesion score was 1 +/- 0 in both groups (n.s.) and the visibility score was 0.7 +/- 0.4 in the test group versus 0.5 +/- 0.5 in the control group (n.s.). In this animal model, the role of the bioresorbable membrane in the prevention of pericardial adhesions is limited to the areas without pericardial cover and without foreign material. The presence of foreign material neutralizes its effect.

Description of a new artificial diet for rearing ant colonies as Iridomyrmex humilis, Monomorium pharaonis and Wasmannia auropunctata (Hymenoptera, Formicidae)

A diet which does not desiccate was developed for rearing various ant species. this diet was found to be very attractive forIridomyrmex humilis. Monomorium pharaonis andWasmannia auropunctata in which species it permitted the rearing of colonies for long periods and the regular production of sexuals. Nous présentons la recette d'une nourriture artificielle élaborée pour élever des fourmis en laboratoire. Cette nourriture ne se dessèche pas et s'est avérée adéquate pour l'élevage de plusieur espèces telles queIridomyrmex humilis, Monomorium pharaonis etWasmannia auropunctata. Des sexués mâles et femelles ont été régulièrement produits dans ces sociétés.

Redox dysregulation in the pathophysiology of schizophrenia and bipolar disorder: insights from animal models.

Abstract Significance: Schizophrenia (SZ) and bipolar disorder (BD) are classified as two distinct diseases. However, accumulating evidence shows that both disorders share genetic, pathological, and epidemiological characteristics. Based on genetic and functional findings, redox dysregulation due to an imbalance between pro-oxidants and antioxidant defense mechanisms has been proposed as a risk factor contributing to their pathophysiology. Recent Advances: Altered antioxidant systems and signs of increased oxidative stress are observed in peripheral tissues and brains of SZ and BD patients, including abnormal prefrontal levels of glutathione (GSH), the major cellular redox regulator and antioxidant. Here we review experimental data from rodent models demonstrating that permanent as well as transient GSH deficit results in behavioral, morphological, electrophysiological, and neurochemical alterations analogous to pathologies observed in patients. Mice with GSH deficit display increased stress reactivity, altered social behavior, impaired prepulse inhibition, and exaggerated locomotor responses to psychostimulant injection. These behavioral changes are accompanied by N-methyl-D-aspartate receptor hypofunction, elevated glutamate levels, impairment of parvalbumin GABA interneurons, abnormal neuronal synchronization, altered dopamine neurotransmission, and deficient myelination. Critical Issues: Treatment with the GSH precursor and antioxidant N-acetylcysteine normalizes some of those deficits in mice, but also improves SZ and BD symptoms when given as adjunct to antipsychotic medication. Future Directions: These data demonstrate the usefulness of GSH-deficient rodent models to identify the mechanisms by which a redox imbalance could contribute to the development of SZ and BD pathophysiologies, and to develop novel therapeutic approaches based on antioxidant and redox regulator compounds. Antioxid. Redox Signal. 18, 1428-1443.

Establishment of animal models to analyze the kinetics and distribution of human tumor antigen-specific CD8⁺ T cells.

Many patients develop tumor antigen-specific T cell responses detectable in peripheral blood mononuclear cells (PBMCs) following cancer vaccine. However, measurable tumor regression is observed in a limited number of patients receiving cancer vaccines. There is a need to re-evaluate systemically the immune responses induced by cancer vaccines. Here, we established animal models targeting two human cancer/testis antigens, NY-ESO-1 and MAGE-A4. Cytotoxic T lymphocyte (CTL) epitopes of these antigens were investigated by immunizing BALB/c mice with plasmids encoding the entire sequences of NY-ESO-1 or MAGE-A4. CD8(+) T cells specific for NY-ESO-1 or MAGE-A4 were able to be detected by ELISPOT assays using antigen presenting cells pulsed with overlapping peptides covering the whole protein, indicating the high immunogenicity of these antigens in mice. Truncation of these peptides revealed that NY-ESO-1-specific CD8(+) T cells recognized D(d)-restricted 8mer peptides, NY-ESO-181-88. MAGE-A4-specific CD8(+) T cells recognized D(d)-restricted 9mer peptides, MAGE-A4265-273. MHC/peptide tetramers allowed us to analyze the kinetics and distribution of the antigen-specific immune responses, and we found that stronger antigen-specific CD8(+) T cell responses were required for more effective anti-tumor activity. Taken together, these animal models are valuable for evaluation of immune responses and optimization of the efficacy of cancer vaccines.

Propagation velocity kinetics and repolarization alternans in a free-behaving sheep model of pacing-induced atrial fibrillation.

AIMS: Experimental models have reported conflicting results regarding the role of dispersion of repolarization in promoting atrial fibrillation (AF). Repolarization alternans, a beat-to-beat alternation in action potential duration, enhances dispersion of repolarization when propagation velocity is involved. METHODS AND RESULTS: In this work, original electrophysiological parameters were analysed to study AF susceptibility in a chronic sheep model of pacing-induced AF. Two pacemakers were implanted, each with a single right atrial lead. Right atrial depolarization and repolarization waves were documented at 2-week intervals. A significant and gradual decrease in the propagation velocity at all pacing rates and in the right atrial effective refractory period (ERP) was observed during the weeks of burst pacing before sustained AF developed when compared with baseline conditions. Right atrial repolarization alternans was observed, but because of the development of 2/1 atrioventricular block with far-field ventricular interference, its threshold could not be precisely measured. Non-sustained AF was not observed at baseline, but appeared during the electrical remodelling in association with a decrease in both ERP and propagation velocity. CONCLUSION: We report here on the feasibility of measuring ERP, atrial repolarization alternans, and propagation velocity kinetics and their potential in predicting susceptibility to AF in a free-behaving model of pacing-induced AF using the standard pacemaker technology.

Tigecycline in combination with other antimicrobials: a review of in vitro, animal and case report studies.

Tigecycline has been investigated in combination with other antibacterials against a wide range of susceptible and multiresistant Gram-positive and Gram-negative bacteria. Combinations have been analysed in vitro, in animal models and in human case reports. In vitro, tigecycline combined with other antimicrobials produces primarily an indifferent response (neither synergy nor antagonism). Nevertheless, synergy occurred when tigecycline was combined with rifampicin against 64-100% of Enterococcus spp., Streptococcus pneumoniae, Enterobacter spp. and Brucella melitensis isolates. Combinations of tigecycline with amikacin also showed synergy for 40-100% of Enterobacter spp., Klebsiella pneumoniae, Proteus spp. and Stenotrophomonas maltophilia isolates. Moreover, bactericidal synergisms occurred with tigecycline plus amikacin against problematic Acinetobacter baumannii and Proteus vulgaris, and with colistin against K. pneumoniae. Data from animal experiments and case reports, although limited, displayed consistent beneficial activity of tigecycline in combination with other antibacterials against multiresistant organisms, including vancomycin against penicillin-resistant S. pneumoniae in experimental meningitis, gentamicin against Pseudomonas aeruginosa in experimental pneumonia, daptomycin against Enterococcus faecium endocarditis, and colistin against K. pneumoniae bacteraemia and P. aeruginosa osteomyelitis. Antagonism was extremely rare in vitro and was not reported in vivo. Thus, tigecycline may be combined with a second antimicrobial as part of a combination regimen.

Wear of two artificial tooth materials in vivo: a 12-month pilot study.

STATEMENT OF PROBLEM: Wear of methacrylate artificial teeth resulting in vertical loss is a problem for both dentists and patients. PURPOSE: The purpose of this study was to quantify wear of artificial teeth in vivo and to relate it to subject and tooth variables. MATERIAL AND METHODS: Twenty-eight subjects treated with complete dentures received 2 artificial tooth materials (polymethyl methacrylate (PMMA)/double-cross linked PMMA fillers; 35%/59% (SR Antaris DCL, SR Postaris DCL); experimental 48%/46%). At baseline and after 12 months, impressions of the dentures were poured with improved stone. After laser scanning, the casts were superimposed and matched. Maximal vertical loss (mm) and volumetric loss (mm(3)) were calculated for each tooth and log-transformed to reduce variability. Volumetric loss was related to the occlusally active surface area. Linear mixed models were used to study the influence of the factors jaw, tooth, and material on adjusted (residual) wear values (alpha=.05). RESULTS: Due to drop outs (n=5) and unmatchable casts (n=3), 69% of all teeth were analyzed. Volumetric loss had a strong linear relationship to surface area (P<.001); this was less pronounced for vertical loss (P=.004). The factor showing the highest influence was the subject. Wear was tooth dependent (increasing from incisors to molars). However, these differences diminished once the wear rates were adjusted for occlusal area, and only a few remained significant (anterior versus posterior maxillary teeth). Another influencing factor was the age of the subject. CONCLUSIONS: Clinical wear of artificial teeth is higher than previously measured or expected. The presented method of analyzing wear of artificial teeth using a laser-scanning device seemed suitable.

Relatedness influences signal reliability in evolving robots.

Communication is an indispensable component of animal societies, yet many open questions remain regarding the factors affecting the evolution and reliability of signalling systems. A potentially important factor is the level of genetic relatedness between signallers and receivers. To quantitatively explore the role of relatedness in the evolution of reliable signals, we conducted artificial evolution over 500 generations in a system of foraging robots that can emit and perceive light signals. By devising a quantitative measure of signal reliability, and comparing independently evolving populations differing in within-group relatedness, we show a strong positive correlation between relatedness and reliability. Unrelated robots produced unreliable signals, whereas highly related robots produced signals that reliably indicated the location of the food source and thereby increased performance. Comparisons across populations also revealed that the frequency for signal production-which is often used as a proxy of signal reliability in empirical studies on animal communication-is a poor predictor of signal reliability and, accordingly, is not consistently correlated with group performance. This has important implications for our understanding of signal evolution and the empirical tools that are used to investigate communication.

Allostatic working memory processing in schizophrenia: Human and animal model coherence

The most evident symptoms of schizophrenia are severe impairment of cognitive functions like attention, abstract reasoning and working memory. The latter has been defined as the ability to maintain and manipulate on-line a limited amount of information. Whereas several studies show that working memory processes are impaired in schizophrenia, the specificity of this deficit is still unclear. Results obtained with a new paradigm, involving visuospatial, dynamic and static working memory processing, suggest that schizophrenic patients rely on a specific compensatory strategy. An animal model of schizophrenia with a transient deficit in glutathione during the development reveals similar substitutive processing, masking the impairment in working memory functions in specific test conditions only. Taken together, these results show coherence between working memory deficits in schizophrenic patients and in animal models. More generally, it is possible to consider that the pathological state may be interpreted as a reduced homeostatic reserve. However, this may be balanced in specific situations by efficient allostatic strategies. Thus, the pathological condition would remain latent in several situations, due to such allostatic regulations. However, to maintain a performance based on highly specific strategies requires in turn specific conditions, limitating adaptative resources in humans and in animals. In summary, we suggest that the psychological and physical load to maintain this rigid allostatic state is very high in patients and animal subjects.

Establishment of a reliable laser-Induced Choroidal Neovascularization Animal Model

Purpose: Pathologic choroidal neovascularizations (CNV) are implicated in the wet form of age-related macular degeneration (ARMD). Abnormal vessel growth is also observed in disease when hypoxia and/or inflammation occur. Our goal is to establish a standard protocol of laser-induced CNV in mice that have different levels of pigmentation to identify the most reliable animal model.Methods: CNV was induced by 4 burns around the optic disk, using a green argon laser (100μm diameter spot size; 0,05 sec. duration) in C57/Bl6, DBA/1 and Balb/c to ascertain the efficacy of the method in function of retina pigmentation. Five different intensities were tested and Bruch's membrane disruption was identified by the appearance of a bubble at the site of photocoagulation. Fluorescein angiographies (FA) were undertaken 14 days post lesion and CNV area was quantified by immunohistochemistry on cryosections.Results: CNV retina area was related to spot intensity after laser injury. While 180mW and 200mW do not induce reliable CNV (respectively 27.85±0.35% and 29±1.67% of the retina surface), 260mW is required to induce 51,07±8.52% of CNV in C57/Bl6 mice. For the DBA/1 strain, less pigmented, 200mW was sufficient to induce 49.35±3.9% of CNV, indicating that lower intensity are required to induce CNV. Furthermore, an intensity of 180mW induced greater CNV (35.55±6.01%) than in C57/Bl6 mice. Nevertheless, laser did not induce reproducible 50% CNV in Balb/c albino mice for all intensities tested. Isolectin-B4 and GFAP stainings revealed neovessel formation and photoreceptor (PR) degeneration at the impact site. The presence of glia was observed throughout all the retinal layers and angiograms showed fluorescein leakage in pigmented mice.Conclusions: The establishment of a standard protocol to induce CNV and subsequent PR degeneration is of prime importance for the use of the laser-induced CNV model and will allow to evaluate the therapeutic potency of agents to prevent CNV and retinal degeneration.

A developmental in vivo 1H NMR study in mice with genetic redox dysregulation: an animal model with relevance to schizophrenia

Glutathione (GSH), a major redox regulator and anti-oxidant, is decreased in cerebrospinal fluid and prefrontal cortex of schizophrenia patients. The gene of the key GSH-synthesizing enzyme, glutamate-cysteine ligase, modifier (GCLM) subunit, is associated with schizophrenia, suggesting that the deficit in the GSH system is of genetic origin. Using the GCLM knock-out (KO) mouse model with 60% decreased brain GSH levels, we have shown that redox dysregulation results in abnormal brain morphology and function. Current theory holds that schizophrenia is a developmental disease involving progressive anatomical and functional brain pathology. Here, we used GCLM KO mice to investigate the impact of a genetically dysregulated redox system on the neurochemical profile of the developing brain. The anterior and posterior cortical neurochemical profile of male and female GCLM KO, heterozygous and wildtype mice was determined by localised in vivo 1H NMR spectroscopy at 14.1 T (Varian/Magnex spectrometer) on post-natal days 10, 20, 30, 60 and 90. We show, for the first time, (1) that high quality 1H NMR spectra can be acquired from early developing mouse brains and (2) that recurrent anaesthesia by itself when administered at the same developmental days has no adverse effects on brain metabolites nor on adult behaviour. (3) Most importantly, our results reveal genotype and age specific changes for a number of metabolites revealing insight into normal brain development and about the impact of genetic GSH dysregulation.

The GraftConnector experience. Long-term patency and histological work up in an animal model.

BACKGROUND: A device to perform sutureless end-to-side coronary artery anastomosis has been developed by means of stent technology (GraftConnector). The present study assesses the long-term quality of the GraftConnector anastomosis in a sheep model. METHODS: In 8 adult sheep, 40-55 kg in weight, through left anterior thoracotomy, the right internal mammary artery (RIMA) was prepared and connected to the left anterior descending artery (LAD) by means of GraftConnector, on beating heart, without using any stabilizer. Ticlopidine 250 mg/day for anticoagulation for 4 weeks and Aspirin 100 mg/day for 6 months were given. The animals were sacrificed after 6 months and histological examination of anastomoses was carried out after slicing with the connector in situ for morphological analysis. RESULTS: All animals survived at 6 months. All anastomoses were patent and mean luminal width at histology was 1.8 +/- 0.2 mm; mean myotomia hyperplasia thickness was 0.21 +/- 0.1 mm. CONCLUSIONS: Long-term results demonstrate that OPCABGs performed with GraftConnector had 100% patency rate. The mean anastomotic luminal width corresponds to mean LAD's adult sheep diameter. We may speculate that myotomia hyperplasia occurred as a result of local device oversizing.