Atypical antipsychotics attenuate MK801-induced social withdrawal and hyperlocomotion in the RHA rat model of schizophrenia-relevant features

RATIONALE

The administration of NMDA receptor (NMDAR) antagonists constitutes a widely used model that produce both positive (e.g., hyperactivity) and negative (e.g., social withdrawal) symptoms relevant for schizophrenia in rodents. These effects can be reversed with the administration of atypical (second and third generation) antipsychotics.

OBJECTIVES

In this study we combined the NMDAR-antagonist model with the Roman High-Avoidance (RHA) strain, a psychogenetically selected model of schizophrenia-relevant features. We also studied whether some atypical antipsychotic drugs (clozapine, ziprasidone, and aripiprazole) would be able to attenuate or reverse the behavioural alterations induced by MK801 and whether such effects might be dependent on the rat strain.

METHODS

MK801 dose-response study was conducted in RHA and Roman Low-Avoidance (RLA) male rats. After that, the 0.15 mg/kg MK801 dose was selected to carry out pharmacological studies versus atypical antipsychotics.

RESULTS

In the first experiment we establish that MK801 (dizocilpine), a NMDAR antagonist, produces dose-related hyperactivity and social withdrawal, which are more marked in RHA than RLA rats. The administration of the atypical antipsychotics clozapine (2.5 mg/kg) or ziprasidone (2.5 mg/kg) partially reversed or attenuated some of the social behaviour deficits and hyperactivity induced by the administration of MK801. Aripiprazole (3 mg/kg), a third-generation antipsychotic, reversed or attenuated the social preference deficit, the hyperactivity and the impairment of social latency induced by MK801.

CONCLUSIONS

These results seem to be in line with previous studies with the NMDAR-antagonist model and add face (MK801-induced social withdrawal and hyperactivity) and predictive (attenuation of MK801-induced effects by atypical antipsychotics) validity to the RHA rat strain as a model of schizophrenia-relevant features.

Decreased activation of parvalbumin interneurons in the medial prefrontal cortex in intact inbred Roman rats with schizophrenia-like reduced sensorimotor gating

Prepulse inhibition (PPI) allows assessing schizophrenia-like sensorimotor gating deficits in rodents. Previous studies indicate that PPI is modulated by the medial prefrontal cortex (mPFC), which is in agreement with our findings showing that PPI differences in the Roman rats are associated with divergences in mPFC activity. Here, we explore whether differences in PPI and mPFC activity in male Roman rats can be explained by (i) differences in the activation (c-Fos) of inhibitory neurons (parvalbumin (PV) interneurons); and/or (ii) reduced excitatory drive (PSD-95) to PV interneurons. Our data show that low PPI in the Roman high-avoidance (RHA) rats is associated with reduced activation of PV interneurons. Moreover, the RHA rats exhibit decreased density of both PV interneurons and PSD-95 puncta on active PV interneurons. These findings point to reduced cortical inhibition as a candidate to explain the schizophrenia-like features observed in RHA rats and support the role of impaired cortical inhibition in schizophrenia.

Inquilinus limosus isolated from a patient with chronic cystic fibrosis. First report in Mexico and evidence that co-infection with Pseudomonas aeruginosa promotes the accelerated and increased formation of extracellular neutrophil traps

Cystic fibrosis is characterized by abnormal mucous secretions in the lungs that favor the proliferation of colonizing bacteria, with Pseudomonas aeruginosa and Staphylococcus aureus being the most isolated, however, other less known species could also have an impact on the health of the patient. Here we demonstrate the isolation and antibiotic resistance profiles of Inquilinus limosus, a rarely reported multidrug resistant bacterium, and compare them to a co-infectant strain of Pseudomonas aeruginosa. Likewise, we found that co-infection with both bacteria promotes increased formation of neutrophil extracellular traps, which can have an impact on the disease severity and make treatment difficult.

Neurobehavioral and neurodevelopmental profiles of a heuristic genetic model of differential schizophrenia- and addiction-relevant features: The RHA vs. RLA rats

The Roman High- (RHA) and Low-(RLA) avoidance rat lines/strains were generated through bidirectional selective breeding for rapid (RHA) vs. extremely poor (RLA) two-way active avoidance acquisition. Compared with RLAs and other rat strains/stocks, RHAs are characterized by increased impulsivity, deficits in social behavior, novelty-induced hyper-locomotion, impaired attentional/cognitive abilities, vulnerability to psychostimulant sensitization and drug addiction. RHA rats also exhibit decreased function of the prefrontal cortex (PFC) and hippocampus, increased functional activity of the mesolimbic dopamine system and a dramatic deficit of central metabotropic glutamate-2 (mGlu2) receptors (due to a stop codon mutation at cysteine 407 in Grm2 -cys407*-), along with increased density of 5-HT2A receptors in the PFC, alterations of several synaptic markers and increased density of pyramidal "thin" (immature) dendrític spines in the PFC. These characteristics suggest an immature brain of RHA rats, and are reminiscent of schizophrenia features like hypofrontality and disruption of the excitation/inhibition cortical balance. RHA rats represent a promising heuristic model of neurodevelopmental schizophrenia-relevant features and comorbidity with drug addiction vulnerability.

Decreased social interaction in the RHA rat model of schizophrenia-relevant features: Modulation by neonatal handling

The Roman-Low (RLA) and High-Avoidance (RHA) rat strains have been bidirectionally selected and bred, respectively, for extremely poor vs. rapid acquisition of the two-way active avoidance task. Over 50 years of selective breeding have led to two strains displaying many differential specific phenotypes. While RLAs display anxious-related behaviours, RHA rats show impulsivity, and schizophrenia-like positive and cognitive symptoms or phenotypes. Neonatal handling (NH) is an environmental treatment with long-lasting anxiolytic-like and anti-stress effects. NH also reduces symptoms related to schizophrenia, such as pre-pulse inhibition (PPI) impairment and latent inhibition (LI) deficits, and improves spatial working memory and cognitive flexibility. The present work was aimed at exploring whether RHAs also display negative schizophrenia-like symptoms (or phenotypes), such as lowered preference for social interaction (i.e. asociality), and whether NH would reduce these deficits. To this aim, we evaluated naïve inbred RHA and RLA rats in a social interaction (SI) test after either long- or short-term habituation to the testing set up (studies 1-2). In Study 3 we tested untreated and NH-treated RHA and RLA rats in novel object exploration (NOE) and SI tests. Compared with RHAs, RLA rats displayed increased anxiety-related behaviours in the NOE (i.e. higher behavioural inhibition, lesser exploration of the novel object) and SI (i.e. higher levels of self-grooming) tests which were dramatically reduced by NH treatment, thus supporting the long-lasting anxiolytic-like effect of NH. Remarkably, RHA rats showed decreased social preference in the SI test compared with RLAs, evidencing that RHAs would present a relative asociality, which is thought to model some negative symptomatology (i.e. social withdrawal) of schizophrenia. NH increased absolute levels of social behaviour in both strains, but with a more marked effect in RHA rats, especially in the first 5 min of the SI test. Thus, it is hypothesized that, apart from its effects on anxiety-related behaviours, NH might have long-lasting positive effects on behavioural and neurobiological processes that are impaired in schizophrenia.

Increased thin-spine density in frontal cortex pyramidal neurons in a genetic rat model of schizophrenia-relevant features

The cellular mechanisms altered during brain wiring leading to cognitive disturbances in neurodevelopmental disorders remain unknown. We have previously reported altered cortical expression of neurodevelopmentally regulated synaptic markers in a genetic animal model of schizophrenia-relevant behavioral features, the Roman-High Avoidance rat strain (RHA-I). To further explore this phenotype, we looked at dendritic spines in cortical pyramidal neurons, as changes in spine density and morphology are one of the main processes taking place during adolescence. An HSV-viral vector carrying green fluorescent protein (GFP) was injected into the frontal cortex (FC) of a group of 11 RHA-I and 12 Roman-Low Avoidance (RLA-I) male rats. GFP labeled dendrites from pyramidal cells were 3D reconstructed and number and types of spines quantified. We observed an increased spine density in the RHA-I, corresponding to a larger fraction of immature thin spines, with no differences in stubby and mushroom spines. Glia cells, parvalbumin (PV) and somatostatin (SST) interneurons and surrounding perineuronal net (PNN) density are known to participate in FC and pyramidal neuron dendritic spine maturation. We determined by stereological-based quantification a significantly higher number of GFAP-positive astrocytes in the FC of the RHA-I strain, with no difference in microglia (Iba1-positive cells). The number of inhibitory PV, SST interneurons or PNN density, on the contrary, was unchanged. Results support our belief that the RHA-I strain presents a more immature FC, with some structural features like those observed during adolescence, adding construct validity to this strain as a genetic behavioral model of neurodevelopmental disorders.

Avoiding the trap: Mechanisms developed by pathogens to escape neutrophil extracellular traps

Neutrophils are the first cells of the innate immune system that respond to infection by arriving at sites when pathogens have exceeded physical barriers. Among their response mechanisms against pathogens is the release of neutrophil extracellular traps (NETs), which are composed of deoxyribonucleic acid and antimicrobial proteins such as neutrophil elastase, myeloperoxidase, antimicrobial peptides, and other proteins in neutrophil granules. The formation of extracellular traps is considered an effective strategy to capture and, in some cases, neutralize pathogenic bacteria, fungi, parasites, or viruses. However, it is also known that pathogens can respond to NETs by expressing some virulence factors, thus evading the antimicrobial effect of these structures. These include the secretion of proteins to degrade the deoxyribonucleic acid scaffold, the formation of biofilms that impede the effect of NETs, or the modification of its membrane structure to avoid interaction with NETs. In this review, we discuss these mechanisms and summarize the different pathogens that employ one or more mechanisms to evade the NET-mediated neutrophil response.

Variation of δ18O in otoliths of Stellifer lanceolatus and Eucinostomus gula environmental change indicator in Terminos Lagoon, Mexico

Environmental changes have been associated with natural climatic variability or human activity. Water resources management is, perhaps, the most drastic change observed in the coastal environment. However, external forcings such as the El Niño event have important implications in the global and regional hydrological balance. These environmental changes have an impact on the density and biomass of the ichthyofauna in the Terminos Lagoon (TL) for the past 30 years, presumably, associated with variations in the temperature and surface salinity of the sea. Therefore, in the present study, δ¹⁸O was quantified in otoliths of two important species due to their dominance: Stellifer lanceolatus and Eucinostomus gula, and to understand the environmental changes reflected in both species. The δ¹⁸O was analyzed in otoliths of these two species captured in 1998/1997, 2006/2007 and 2016/2017 and were compared with in situ temperature and salinity data. Sea surface temperature and salinity increased by 2 °C and 9, respectively, between 1997 and 2017. Stellifer lanceolatus δ¹⁸O values was in isotopic equilibrium with seawater calcite; while, E. gula is not in isotopic equilibrium. The δ¹⁸O of S. lanceolatus and E. gula varied significantly with the increase in salinity (R² = 0.8987 and R² = -0.2964) and not with the sea surface temperature. S. lanceolatus is an excellent bioindicator of changes in sea surface salinity in this region of the Gulf of Mexico.

Dissociation between schizophrenia-relevant behavioral profiles and volumetric brain measures after long-lasting social isolation in Roman rats

Social isolation rearing of rodents is an environmental manipulation known to induce or potentiate psychotic-like symptoms and attentional and cognitive impairments relevant for schizophrenia. When subjected to a 28-week isolation rearing treatment, the Roman high-avoidance (RHA-I) rats display the common behavioral social isolation syndrome, with prepulse inhibition (PPI) deficits, hyperactivity, increased anxiety responses and learning/memory impairments when compared to their low-avoidance (RLA-I) counterparts. These results add face validity to the RHA-I rats as an animal model for schizophrenia-relevant behavioral and cognitive profiles and confirm previous results. The aim here was to further investigate the neuroanatomical effects of the isolation rearing, estimated through volume differences in medial prefrontal cortex (mPFC), dorsal striatum (dSt) and hippocampus (HPC). Results showed a global increase in volume in the mPFC in the isolated rats of both strains, as well as strain effects (RLA > RHA) in the three brain regions. These unexpected but robust results, might have unveiled some kind of compensatory mechanisms due to the particularly long-lasting isolation rearing period, much longer than those commonly used in the literature (which usually range from 4 to 12 weeks).

Spatial and trophic preferences of jumbo squid Dosidicus gigas (D'Orbigny, 1835) in the central Gulf of California: ecological inferences using stable isotopes

RATIONALE

The jumbo squid Dosidicus gigas is a fishery resource of considerable economic and ecological importance in the Mexican Pacific. Studies on its habitat preferences are needed to understand recent fluctuations in the abundance and availability of the species. Stable isotope analysis allows us to infer ecological aspects such as spatial distribution and trophic preferences.

METHODS

We used an isotope ratio mass spectrometer, automated for carbonate analysis, and coupled to an elemental analyzer, to determine the isotopic composition of statoliths (δ¹⁸ O and δ¹³ C values) and beaks (δ¹³ C and δ¹⁵ N values) from 219 individuals caught over two fishing seasons (2007 and 2009) off the coast of Santa Rosalía, in the central Gulf of California. We used these isotopic ratios to assess variation in spatial and trophic preferences by sex, size, and fishing season.

RESULTS

In the 2009 group, we observed significant differences in statolith δ¹³ C values and beak δ¹³ C and δ¹⁵ N values between males and females. Between size groups, we observed significant differences in statolith δ¹⁸ O and δ¹³ C values in 2007 and in beak δ¹³ C and δ¹⁵ N values during both seasons. Both seasons were characterized by high overlap in δ¹⁸ O and δ¹³ C values between sexes and in 2009 between size groups. We observed low trophic overlap between sexes in 2009 and between size groups during both seasons.

CONCLUSIONS

The isotopic ratios from statoliths and beaks indicate that D. gigas has changed its spatial and trophic preferences, a shift that is probably related to changes in the species' diet. This intraspecific variation in preferences could be related to characteristics such as size, which may influence squid distribution preferences.

Validation of the Pancreatic Donor Risk Index in Simultaneous Pancreas-Kidney Transplantation Performed in Córdoba Hospital From 2000 to 2015

BACKGROUND

The Pancreatic Donor Risk Index (PDRI) was developed in 2010 in the United States to predict graft survival after pancreas transplantation, based on donor characteristics and logistical and technical conditions. The aim of the study was to validate the utility of PDRI as a pancreas allograft survival predictor in simultaneous pancreas-kidney transplantation (SPK) transplants performed in our hospital between 2000 and 2015.

METHODS

This retrospective analysis of 126 SPK transplants was performed by the same surgical team from the years 2000 to 2015. Donor variables that are integrated in the PDRI were calculated (age, sex, race, creatinine serum levels, body mass index, height, cold ischemia time, cause of death, type of pancreas transplant). Pancreatic graft survival at 1 and 5 years was calculated by use of the Kaplan-Meier test. Comparison of survival curves between PDRI risk quartiles was calculated by use of the log-rank test. Association between graft survival and variables integrating the PDRI was calculated by use of univariate Cox regression analysis.

RESULTS

Log-rank analysis found no statistically significant association between global graft survival and PDRI quartiles. Univariate Cox regression analysis showed a statistically significant association between graft survival and cold ischemia time (P < .05).

CONCLUSIONS

PDRI was not a useful tool to predict pancreatic graft outcomes in a Spanish reference population.

Divergent effects of isolation rearing on prepulse inhibition, activity, anxiety and hippocampal-dependent memory in Roman high- and low-avoidance rats: A putative model of schizophrenia-relevant features

Social isolation of rats induces a constellation of behavioral alterations known as "isolation syndrome" that are consistent with some of the positive and cognitive symptoms observed in schizophrenic patients. In the present study we have assessed whether isolation rearing of inbred Roman high-avoidance (RHA-I) and Roman low-avoidance (RLA-I) strains can lead to the appearance of some of the key features of the "isolation syndrome", such as prepulse inhibition (PPI) deficits, increased anxious behavior, hyperactivity and memory/learning impairments. Compared to RLA-I rats, the results show that isolation rearing (IR) in RHA-I rats has a more profound impact, as they exhibit isolation-induced PPI deficits, increased anxiety, hyperactivity and long-term reference memory deficits, while isolated RLA-I rats only exhibit deficits in a spatial working memory task. These results give further support to the validity of RHA-I rats as a genetically-based model of schizophrenia relevant-symptoms.

A computational study of bulk porous two-dimensional polymers related to graphyne

We use density functional theory methods with periodic boundary conditions to investigate the stacking arrangements of the bulk 2D polymers multilayer porous graphyne, the analog in which the triple bonds are substituted by double bonds and the related carbon allotrope multilayer graphyne.

Association between prepulse inhibition of the startle response and latent inhibition of two-way avoidance acquisition: A study with heterogeneous NIH-HS rats

This study presents the first evaluation of the associations between responses in two paradigms related to schizophrenia in the genetically heterogeneous NIH-HS rat stock. NIH-HS rats are a stock of genetically heterogeneous animals that have been derived from eight different inbred strains. A rotational breeding schedule has been followed for more than eighty generations, leading to a high level of genetic recombination that makes the NIH-HS rats a unique tool for studying the genetic basis of (biological, behavioral, disease-related) complex traits. Previous work has dealt with the characterization of coping styles, cognitive and anxiety/fear-related profiles of NIH-HS rats. In the present study we have completed their characterization in two behavioral models, prepulse inhibition (PPI) and latent inhibition (LI) of the two-way active avoidance response, that appear to be related to schizophrenia or to schizophrenia-relevant symptoms. We have found that these rats display PPI for each of the four prepulse intensities tested, allowing their stratification in high, medium and low PPI subgroups. When testing these three subgroups for LI of two-way active avoidance acquisition it has been observed that the LowPPI and MediumPPI subgroups present impaired LI, which, along with the fact that the HighPPI group presents significant LI, allows us to hypothesize that responses in these two paradigms are somehow related and that selection of NIH-HS rats for Low vs HighPPI could make a promising animal model for the study of clusters of schizophrenia-relevant symptoms and their underlying neurobiological mechanisms.

[Pseudoseptic arthritis with foreign body synovitis in a patient with gout]

Monoarthritis is a diagnostic challenge for the clinician, as the list of associated conditions is quite long. It is accepted that in patients with a diagnosis of inflammatory joint disease monoarthritis represents exacerbation of the underlying disease. However, ignoring the systematized approach to monoarthritides may lead to omissions and mistaken diagnostic implications. This report describes the approach to a case of pseudoseptic arthritis that mimicked an acute episode of recurrent arthritis due to monosodium urate in a patient with retention of an intraarticular foreign body.

Toxicity in semiarid sediments influenced by tailings of an abandoned gold mine

The mining district of El Triunfo (ET-MD) has an estimated 800,000 t of mine wastes scattered in the environment, contaminating the sediment with potentially toxic elements such as As, Cd, Pb, and Zn. In order to estimate the toxicity of the sediment to the adjacent biota, the aims of our study are to calculate the mortality and inhibition through bioassays, using sediment, and test organisms such as Daphnia magna and Selenastrum capricornutum (Pseudokirchneriella subcapitata), respectively. The D. magna mortality was 31 ± 12% and the S. capricornutum growth inhibition was 53 ± 24%. The contamination of the sediment determines the high mortality of D. magna and the high inhibition of S. capricornutum in the system, indicating risk for the biota in the contaminated system.

Menstrual cycle and profiles of suicidal behaviour

The first (or menstrual) and fourth (or premenstrual) week of the menstrual cycle may be associated with many suicide attempts in women. The study sample included 113 Spanish women who attempted suicide and contacted an emergency service. Inclusion criteria were as follows: fertility; regular menstrual cycles; lack of oral contraceptives; and willingness to see a psychiatrist. The incidence of suicide attempts in the first week (36%) was significantly higher than that in the remaining weeks (second week, 19%; third week 16%; fourth week, 29%). A correspondence analysis suggested that suicide attempts were associated with differences in demographics and clinical profiles. In particular, suicide attempts in the third week were correlated with a severe history of psychiatric problems and a lower level of education. The limitations of this study are its exclusiveness to hospitalized cases and its use of patient reports to date menstruation.

Normal angiogram after myocardial infarction in young patients: a prospective clinical-angiographic and long-term follow-up study

This is an observational study in which we compared the clinical characteristics and the long-term course of young patients having acute myocardial infarction and angiographically normal coronary arteries and young patients showing significant coronary artery disease. In 87 patients aged < or = 40 years who suffered an acute myocardial infarction, enrolled in a prospective study over a period of 6.5 years, coronary anatomy was determined by angiography within a month of admission. The risk factors, clinical data, ventricular function and the long-term outcome were compared between patients with normal angiograms (Group 1, n = 12) and patients with coronary artery disease (Group 2, n = 75). Patients in Group 1 had a lower number of risk factors associated with them (17% vs. 64% with > 1 risk factor, P < 0.005), were younger (32 +/- 5 vs. 36 +/- 4, P < 0.01), lighter smokers (25% vs. 55% for > or = 2 packs per day, P < 0.05), had less frequent hypertension (0 vs. 25%, P < 0.05), hypercholesterolemia (17% vs. 52%, P = 0.02) and had a lower mean total cholesterol level (201 +/- 42 vs. 245 +/- 60 mg/100 ml, P < 0.05) than patients in Group 2. They also had a more common onset of their infarction during heavy physical exertion (67% vs. 17%, P < 0.001). A history of previous myocardial infarction, infarct location, global left ventricular function and regional wall motion were similar in both groups. After a mean follow-up period of 41 +/- 23 months, no patient died or had a second myocardial infarction in Group 1, and 4 patients had died in Group 2. The appearance of angina, less frequent in Group 1 than Group 2, tended to correlate with the extension of the coronary artery disease. We concluded that young patients with myocardial infarction have good prognosis irrespective of the coronary anatomy, although patients with normal coronary angiograms had less risk factors and less frequent new ischaemic events.