Directed graph mapping is able to distinguish between the true and false rotors in a complex in-silico excitation pattern

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Supported in part by Dirección General de Polı́tica Cientı́fica de la Generalitat Valenciana PROMETEU 2020/043

Background

In realistic in-silico studies (Figure1, top row) it was shown that phase mapping PM (Figure 1, A) can detect the correct rotor as well as phantom rotors as an artefact of interpolation or due to the far field (Figure 1, B). After interpretation of the LAT, the far field detections could not be distinguished from the true rotor driving the excitation pattern. This can contribute to failure in Atrial Fibrillation (AF) ablation procedures.

Objective

We tested if the recently developed tool Directed Graph mapping (DGM) is less prone to far-field effects and interpolation artefacts than PM on the same in-silico data. DGM represents the excitation pattern as a directed network, from which the rotational activity is detected as cycles in that network.

Methods

Starting from the electrograms (EGMs) of the 64 electrode basket catheter, we interpolated to 957 equidistant electrodes and calculated local activation times (LATs) of the interpolated EGMs (Figure 1, C). We varied the minimal allowed conduction velocity and calculated the corresponding networks for the complete simulation time. Detections were considered as correct if they were located in the same region of the true core of the phasemaps. The false detections were classified in multiple different regions (Figure 1, D).

Results

We find that by proper choice of CVs in the graphs it is possible to achieve a 80% detection of true rotors with 26% detection of false rotors. Reducing restrictions on the CVs increased the detection rate of the false rotors. False rotors due to artifacts were not detected by DGM (Figure 1, last row).

Conclusion

DGM is able to distinguish between true and far field rotors. False detections due to interpolation artifacts as seen in the PM protocol were not observed. The velocity limits in the graph construction play a keyrole in eliminating the far field effects. Abstract Figure 1

Mental health consequences of the Covid-19 outbreak in Spain. A longitudinal study of the alarm situation and return to the new normality

AIMS

The objective is to conduct a longitudinal analysis of the effects of the pandemic and alarm situation on the mental health of the general population at three points in time: two weeks after beginning the confinement, after a month, and after two months, when the lockdown was lifted and the country returned to the new normality.

METHODS

The evaluations were carried out by means of an online survey, with a sample of 3480 persons in the first data collection and 1041 and 569 persons in the successive evaluation periods. The presence of depressive symptoms, anxiety and posttraumatic stress disorder (PTSD) was evaluated by means of screening tests. Sociodemographic data, Covid-19 variables, loneliness, psychological well-being, social support, discrimination and a sense of belonging, were collected.

RESULTS

Depressive symptoms increased significantly throughout the confinement, decreasing at the last assessment but not dropping to previous levels. In anxiety, there are no significant changes between the three evaluations, but a downward trend can be seen over time. Regarding the symptomatology of PTSD, a downward trend is observed throughout the three evaluations, with significantly lower scores between the first and third assessments. The different regression models developed reveal the importance of perceived loneliness and spiritual well-being as the main predictors of mental health, as well as the importance of the lower age for depression and the female gender for anxiety and PSTD.

CONCLUSIONS

This research shows that the pandemic has had a negative impact on our mental health, which still does not seem to be at pre-crisis levels, although it has improved as the emergency situation subsides. These results underline the importance of paying greater attention to mental health, and reveal key variables such as spiritual well-being and perceived loneliness in which to intervene from different care services, as well as younger people and women as vulnerable groups on which to focus more attention.

The usefulness of Olanzapine plasma concentrations in monitoring treatment efficacy and metabolic disturbances in first-episode psychosis

INTRODUCTION

The role of Olanzapine therapeutic drug monitoring is controversial. The present study explores the associations of Olanzapine plasma concentrations with clinical response and metabolic side effects in first episode psychosis (FEP) after 2 months of treatment.

METHODS

Forty-seven patients were included. Improvement in clinical symptomatology was assessed using the PANSS. Metabolic assessment included weight, blood pressure, waist circumference, blood glucose, total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides.

RESULTS

The Olanzapine plasma concentrations after 2 months of treatment were positively correlated with weight gain (r = 0.49, p = 0.003), and a concentration > 23.28 ng/mL was identified as a positive predictor of weight gain (≥ 7%). The Olanzapine concentration to dose (C/D) ratio was positively correlated with the percentage of improvement in the total PANSS (r = 0.46, p = 0.004), and a C/D ratio > 2.12 was identified as a positive predictor of a good response (percentage of improvement > 30%) after 2 months of treatment. We also identified several factors that could alter Olanzapine pharmacokinetics: gender (p = 0.03), diagnosis (p = 0.05), smoking habit (p = 0.05), and co-medications such as valproic acid (p = 0.05) and anxiolytics (p = 0.01).

DISCUSSION

In conclusion, our results suggest that therapeutic drug monitoring of Olanzapine could be helpful to evaluate therapeutic efficacy and metabolic dysfunction in FEP patients treated with Olanzapine.

A web-based tool for the early identification and real time assessment of drug-induced proarrhythmic and torsade de pointes safety risk

Introduction

It is well recognized that early identification of drug-induced proarrhythmic safety risks is crucial to drug development for ethical, animal sparing and costs reduction considerations. The availability, however, of easily accessible, user-friendly tools for real time assessments of the proarrhythmic potential of chemical compounds has been lacking. The novel Tx index, implemented in the presented web-based tool, was applied to a dataset of 84 compounds.

Materials and methods

The tool is based on 206,766 cellular simulations of compound-induced effects on Action Potential Duration (APD) in isolated endocardial, midmyocardial, and epicardial cells and on 7,072 tissue simulations on QT prolongation in a virtual tissue. Simulations were performed by blocking the slow and the fast components of the delayed rectifier current (IKs and IKr, respectively) and the L-type calcium current (ICaL) at different levels. Based on these simulations, four Tx indices were defined as the ratio of drug concentration leading to a 10% prolongation of the APDendo, APDmid, APDepi or QT over the maximum Effective Free Therapeutic Plasma Concentration (EFTPC), respectively. A dataset of 44 non-torsadogenic and 40 torsadogenic drug compounds was used to validate the performance of the tool. The workflow of the web-based tool was built on the cloud environment, in compliance with the highest standards of security and privacy.

hERG test (positive response: hERG pIC50 >6) was applied to the 84 compounds to compare performances.

Results

Receiver operating characteristic (ROC) curves were constructed on the four estimated Tx indices for each compound in the dataset to enable the identification of torsadogenic potential cut-off values2. These were identified as 8, 8, and 6.4 for Tx-APDendo, Tx-APDmid, Tx-APDepi and as 9.2 for Tx-QT, respectively.

The classification of the 84 compounds resulted in an accuracy ranging between 87% and 88% for the four Tx indices Tx-APDendo, Tx-APDmid, Tx-APDepi and Tx-QT.

Discussion and conclusion

hERG block exhibits poor performance. When applying the hERG test to the 84 compounds, it exhibited a TPR of 55%, a TNR of 89%, and an A of 73%, in close agreement with previous studies. In comparison, the in silico Tx tests described in this study yield TPRs of 85%, TNRs of 86–89% and As of 86–87%.

This method does not include drug effects on Na+ channels, which is related to the misclassification of 3 compounds (quetiapine, ranolazine, and lamotrigine – significant Na+ channels blockers at EFTPC). Future work will include this channel.

The presented web-based tool is a highly innovative method for an accurate torsadogenic risk assessment. Each assessment required only a few seconds of computational time.

Illustration workflow of the web tool

Funding Acknowledgement

Type of funding source: None

Search for Nova Presolar Grains: γ-Ray Spectroscopy of ^{34}Ar and its Relevance for the Astrophysical ^{33}Cl(p,γ) Reaction

The discovery of presolar grains in primitive meteorites has initiated a new era of research in the study of stellar nucleosynthesis. However, the accurate classification of presolar grains as being of specific stellar origins is particularly challenging. Recently, it has been suggested that sulfur isotopic abundances may hold the key to definitively identifying presolar grains with being of nova origins and, in this regard, the astrophysical ^{33}Cl(p,γ)^{34}Ar reaction is expected to play a decisive role. As such, we have performed a detailed γ-ray spectroscopy study of ^{34}Ar. Excitation energies have been measured with high precision and spin-parity assignments for resonant states, located above the proton threshold in ^{34}Ar, have been made for the first time. Uncertainties in the ^{33}Cl(p,γ) reaction have been dramatically reduced and the results indicate that a newly identified ℓ=0 resonance at E_{r}=396.9(13)  keV dominates the entire rate for T=0.25-0.40  GK. Furthermore, nova hydrodynamic simulations based on the present work indicate an ejected ^{32}S/^{33}S abundance ratio distinctive from type-II supernovae and potentially compatible with recent measurements of a presolar grain.

SuperCam Calibration Targets: Design and Development

SuperCam is a highly integrated remote-sensing instrumental suite for NASA's Mars 2020 mission. It consists of a co-aligned combination of Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), Visible and Infrared Spectroscopy (VISIR), together with sound recording (MIC) and high-magnification imaging techniques (RMI). They provide information on the mineralogy, geochemistry and mineral context around the Perseverance Rover. The calibration of this complex suite is a major challenge. Not only does each technique require its own standards or references, their combination also introduces new requirements to obtain optimal scientific output. Elemental composition, molecular vibrational features, fluorescence, morphology and texture provide a full picture of the sample with spectral information that needs to be co-aligned, correlated, and individually calibrated. The resulting hardware includes different kinds of targets, each one covering different needs of the instrument. Standards for imaging calibration, geological samples for mineral identification and chemometric calculations or spectral references to calibrate and evaluate the health of the instrument, are all included in the SuperCam Calibration Target (SCCT). The system also includes a specifically designed assembly in which the samples are mounted. This hardware allows the targets to survive the harsh environmental conditions of the launch, cruise, landing and operation on Mars during the whole mission. Here we summarize the design, development, integration, verification and functional testing of the SCCT. This work includes some key results obtained to verify the scientific outcome of the SuperCam system.

Fractionated electrograms and rotors detection in chronic atrial fibrillation using model-based clustering

The identification of atrial fibrillation (AF) substrates is needed to improve ablation therapy guided by electrograms, although mechanisms that sustain AF are not fully understood. Detection of complex fractionated atrial electrograms (CFAE) is used for this purpose. Nonetheless, efficacy of this method is inadequate in the case of chronic AF. Recent hypothesis proposes the rotors as fibrillatory substrate. Novel approaches seek to relate CFAE with rotor; nevertheless, such methods are not able to identify the associated substrate. Furthermore, the patterns that characterize CFAE generated by rotors remain unknown. Thus, tracking of rotors is an unsolved issue. In this paper, we propose a non-supervised method to find patterns associated with fibrillatory substrates in chronic AF. We extracted two features based on local activation wave detection and one feature based on non-linear dynamics. Gaussian mixture model-based clustering was used to discriminate CFAE patterns. Resulting clusters are visualized in an electroanatomic map. We assessed the proposed method in a real database labeled according to the level of fractionation and in a simulated episode of chronic AF in which a rotor was detected. Our results indicate that the method proposed can separate different levels of fractionation in CFAE, and provide evidence that clustering can be used to locate the vortex of the rotors. Provided approach can support ablation therapy procedures by means of CFAE patterns discrimination.

Reduction of negative social attributions towards people with mental illness through a combination of treatments

Introduction

Stigma towards people with mental illness can have very negative consequences for the persons that experience it. So, it becomes strongly necessary to combat this problem.

Objectives/Aims

Evaluate the effectiveness of multiple interventions to reduce stigma against mental illness in a group of high school students.

Methods

Quasi-experimental study. Seventy-six students between 16 to 19 years old from 3 schools of southern Madrid State participated. No significant differences in age and gender between groups were found. The quasi-control group was obtained from 3 different classrooms (1 in each school). This group did not go through any treatment. The experimental group had 2 treatments. Treatment “A” consisted in 1 psychoeducation session. Treatment “B” was 1 visit (real or virtual) to the Thyssen-Bornemisza museum. Persons exercising as museum guides had been diagnosed with mental illness. They already were participants in the PCEA program of the CRPS Latina. The instrument to assess stigma was the AQ-27, validated in Spanish.

Results

We found significant reductions of stigma in all dimensions explored: Anger (A vs BC; P < 0.001), Threat (A vs BC; P < 0.001), Fear (A vs BC; P < 0.001), Coercion (A vs BC; P < 0.001) Segregation (A vs BC; P < 0.001) and Avoidance (A vs BC; P < 0.001).

Conclusions

The combination of treatments for intervention on stigma in samples of school students seems to be a very effective option to reduce stigma.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Assessment of the formation of inorganic oxidation by-products during the electrocatalytic treatment of ammonium from landfill leachates

This work investigates the formation of oxidation by-products during the electrochemical removal of ammonium using BDD electrodes from wastewaters containing chlorides. The influence of the initial chloride concentration has been experimentally analyzed first, working with model solutions with variable ammonium concentration and second, with municipal landfill leachates. Two different levels of chloride concentration were studied, i) low chloride concentrations ranging between 0 and 2000 mg/L and, ii) high chloride concentrations ranging between 5000 and 20,000 mg/L. Ammonium removal took place mainly via indirect oxidation leading to the formation of nitrogen gas and nitrate as the main oxidation products; at high chloride concentration the formation of nitrogen gas and the rate of ammonium removal were both favored. However, chloride was also oxidized during the electrochemical treatment leading to the formation of free chlorine responsible of the ammonium oxidation, together with undesirable products such as chloramines, chlorate and perchlorate. Chloramines appeared during the treatment but they reached a maximum and then started decreasing, being totally removed when high chloride concentrations were used. With regard to the formation of chlorate and perchlorate once again the concentration of chloride exerted a strong influence on the formation kinetics of the oxidation by-products and whereas at low chloride concentrations, chlorate appeared like an intermediate compound leading to the formation of perchlorate, at high chloride concentrations chlorate formation was delayed significantly and perchlorate was not detected during the experimental time. Thus this work contributes first to the knowledge of the potential hazards of applying the electro-oxidation technology as an environmental technology to deal with ammonium oxidation under the presence of chloride and second it reports efficient conditions that minimize or even avoid the formation of undesirable by-products.

Effects of late sodium current enhancement during LQT-related arrhythmias. A simulation study

Long QT syndrome is a repolarization disorder characterized by marked prolongation of QT interval. A clear consequence of long QT syndrome is the occurrence of a polymorphic ventricular tachycardia called Torsade de Pointes, which has been related to early after depolarizations (EADs) formation. This repolarizing disorder has been observed under pathological situations, such as heart failure, oxidative stress, ventricular hypertrophy and/or in the presence of pure class III antiarrhythmics. Under such pathologies electrophysiological changes affect the electrical activity of the cell. Lately, the enhancement of late sodium current (I(NaL)) and its role has become a source of interest. In this work, a mathematical model of I(NaL) has been proposed and incorporated to the ten Tussher model of the human ventricular action potential (AP), specifically in M cells. We simulated and analyzed the effects of I(NaL) enhancement in combination with LQT-related pathologies and administration of I(Kr) blockers, on the AP. This study demonstrates that I(NaL) prolongs AP duration (APD) in a rate-dependent manner. Indeed, a 10-fold increase of I(NaL) prolongs APD in 80% for a stimulation rate of 1 Hz and 100% for 0.25 Hz. Also, intracellular sodium concentration [Na(+)](i) significantly increases in the presence of enhanced I(NaL), increasing the probability of EADs formation through calcium overload in cells prone to develop EADs.

Human and rabbit inter-species comparison of ionic mechanisms of arrhythmic risk: A simulation study

Experimental studies of pro-arrhythmic mechanisms are scarcely performed in humans due to the limited availability of human cardiomyocytes. Subsequently, extrapolation of animal experimental research to humans is widely extended. Our aim is to systematically compare the ionic mechanisms of the main cellular biomarkers of arrhythmic risk between human and rabbit using computer simulations. For this purpose four stimulation protocols were applied to the Mahajan et al. rabbit ventricular action potential (AP) model for control conditions and for ± 15 and ± 30% variations in the ionic current conductances of the main repolarization currents to quantify cellular biomarkers. Sensitivity of every simulated biomarker to every parameter modification was compared to that obtained for human in our previous work. Our results show that the ionic mechanisms involved in AP triangulation, systolic intracellular calcium concentration and AP duration (APD) accommodation to abrupt changes of pacing rate are very similar in both species. Unfortunately, significant differences were found in the ionic mechanisms related to APD, restitution properties and rate dependence of intracellular calcium and sodium concentrations. In conclusion, extrapolation of experimental research in rabbit to humans is limited by the existence of species dependent ionic mechanisms. In addition, this analysis is very useful for understanding and improvement of mathematical models.

Vulnerability for reentry in a three dimensional model of human atria: a simulation study

Atrial tachycardias are the most common cardiac arrhythmias in clinical practice, which induce changes in atrial properties that help to perpetuate them. These changes are called "atrial remodeling". Recent studies have shown that rapid ectopic activity principally on the pulmonary veins can trigger reentrant mechanisms and lead to atrial tachycardias. However, the influences of ectopic foci location, the number of ectopic beats and its frequency on the likelihood of triggering reentries are not well known. In this work the effects of electrical remodeling were incorporated in an atrial cell model and integrated in a three-dimensional model of human atria, to develop a study of vulnerability for reentries. To carry out the study, an ectopic beat and a burst of six ectopic beats at two different frequencies were applied in six different locations in the atria. The results show greater vulnerability in the left pulmonary veins when we applied a single ectopic beat. When we increase the number of ectopic beats to six, a greater width of the vulnerable window was observed when ectopic focus frequency was high. The location, the number of ectopic beats and their frequency affect the vulnerability for reentry.

Ring electrode for radio-frequency heating of the cornea: modelling and in vitro experiments

Radio-frequency thermokeratoplasty (RF-TKP) is a technique used to reshape the cornea curvature by means of thermal lesions using radio-frequency currents. This curvature change allows refractive disorders such as hyperopia to be corrected. A new electrode with ring geometry is proposed for RF-TKP. It was designed to create a single thermal lesion with a full-circle shape. Finite element models were developed, and the temperature distributions in the cornea were analysed for different ring electrode characteristics. The computer results indicated that the maximum temperature in the cornea was located in the vicinity of the ring electrode outer perimeter, and that the lesions had a semi-torus shape. The results also indicated that the electrode thickness, electrode radius and electrode thermal conductivity had a significant influence on the temperature distributions. In addition, in vitro experiments were performed on rabbit eyes. At 5 W power, the lesions were fully circular. Some lesions showed non-uniform characteristics along their circular path. Lesion depth depended on heating duration (60% of corneal thickness for 20 s, and 30% for 10 s). The results suggest that the critical shrinkage temperature (55-63 degrees C) was reached at the central stroma and along the entire circular path in all the cases.

Experimental measurement of the statistics of the scattered intensity from particles on surfaces

We analyze the statistics of the co-polarized and cross-polarized scattered intensity from a flat substrate contaminated with spherical particles including multiple scattering between them. Both Gaussian and non-Gaussian regimes are considered. In particular, we focus on both the cross-polarized component and the probability of detecting zeros in the cross-polarized intensity, P(Icross=0). As it is shown, the latter gives information about particle interaction and can be measured with higher accuracy than other statistical parameters. A theoretical model for P(Icross=0) is presented for spherical Rayleigh scatterers. An scattering experiment was carried out to verify this model.

Relation between the bowel electromyogram and the intestinal pressure wave. An experimental study in dogs

OBJECTIVE

A linear regression study is made of the parameters identifying the electrical activity of the small bowel, with the aim of determining those variables most closely related to the type I pressure waves.

PATIENTS AND METHODS

A computer system was used for the simultaneous and real time acquisition of the manometric activity (using microballoons implanted in the bowel mucosa) and electromyogram of the intestine (employing bipolar electrodes implanted in the intestinal serosa) in dogs.

RESULTS

Of the electromyogram intestinal parameters studied, those determining signal energy (root mean square voltage and energy) yielded the highest correlation coefficients (0.71 +/- 0.08 in the jejunum and 0.78 +/- 0.06 in the duodenum) to bowel pressure. Peak-to-peak voltage also shows good correlation, though to a lesser degree. The rest of the parameters studied, such as those that measure the duration of the action potential or its number of peaks, yielded poor correlations to pressure.

CONCLUSIONS

It is concluded that the energy of the intestinal electromyogram represents the mechanical activity of the small bowel, reflecting intestinal motility, and that the recording of this parameter is not subjected to subjective cutoff values or threshold levels. On the other hand, and unlike in the case of manometric recordings, the signal obtained is free of background interference and noise.

Ectopic activity in ventricular cells induced by early afterdepolarizations developed in Purkinje cells

The development of early afterdepolarizations (EADs) in Purkinje fibers and their propagation to ventricular muscle cells are studied by computer modeling. The Purkinje-ventricular system has been simulated by a two-dimensional model of a Purkinje fiber (PF) connected to a thin sheet of ventricular muscle tissue (VMT). EADs are induced in the PF by enhancing the fast second inward current, iCa,f, and blocking the delayed K+ current, iK, while the VMT is kept under physiological conditions. Different phenomena are observed depending on the EAD conditions applied. For 70% iK blockade and iCa,f enhancement greater than 60%, a single phase 3 EAD developed in the PF propagates to the VMT generating an ectopic beat. For 80% iK blockade and iCa,f enhancement in the range from 0% to 70%, multiple ectopic beats appear in the VMT. However, for iK blockades over 80%, action potentials in PF cells do not repolarize and the ectopic activity in the VMT disappears. In our simulations, the ionic mechanism underlying phase 3 EAD development is the reactivation of the fast sodium current in the PF. Our results demonstrate that there exists a critical range of EAD conditions that favor the development of EADs in the PF and their propagation to the VMT as ectopic activity. This phenomenon could underlie the genesis of some triggered arrhythmias.

Small bowel motility: relationship between smooth muscle contraction and electroenterogram signal

A study is made to correlate the electrical and mechanical activity of the smooth muscle of the small bowel. Bioelectrical signal recording from the intestinal serosa (electroenterogram) comprises a slow wave (SW) and spike burst (SB), though only the latter reflects intestinal pressure. The electroenterogram and smooth muscle pressure are simultaneously recorded in the canine small bowel. Spectral and time series analysis of the electroenterogram are performed to establish those electrical parameters that best reflect intestinal pressure. The results reveal an underlying correlation between the estimated parameters of electrical activity and smooth muscle pressure. In addition, parameters derived from the spectral techniques were closely correlated to pressure events in the intestine, even more so than the variables directly acquired from the classical time domain analyses. Specifically, spectral energy above 2 Hz and mean frequency (both calculated from the biosignal periodogram), are parameters that identify intestinal pressure. The extrapolation of these spectral parameters to long time periods could serve to define a motility index (MI) from electrical gut activity. In this context, electroenterogram recording and analysis can contribute to solve problems inherent to manometric recording, though the need for surgical intervention restricts electrical methods to experimental or surgical studies.

[Spanish version of the new World Health Organization Disability Assessment Schedule II (WHO-DAS-II): initial phase of development and pilot study. Cantabria disability work group]

The aim of the present paper is to present the initial phases of the development of the Spanish version of the "World Health Organization Disablement Assessment Schedule II" WHO-DAS-II and also to describe the quantitative and qualitative methodological strategies used in the elaboration process of an instrument: i) compatible with the new International Classification of Functioning and Disability -ICIDH-2- of the World Health Organisation; ii) with criteria of cross-cultural applicability and; iii) to allow us to assess the disability in all its dimensions.

[Validation of the Spanish version of PRIME-MD: a procedure for diagnosing mental disorders in primary care]

INTRODUCTION

Psychiatric disorders occurs in at least 20% of patients attending Primary Care settings, however, only 50% of them are detected by primary care physicians. Therefore a tool is required which can help primary care physicians to detect and diagnose psychiatric disorders. PRIME-MD (Primary Care Evaluation of Mental Disorders) is a questionnaire designed with this aim. In this article the results of the validation study of the Spanish version of this questionnaire are presented.

MATERIALS AND METHODS

312 patients were interviewed by primary care physicians using PRIME-MD and by psychiatrists using SCAN (Schedules for Clinical Assessment in Neuropsychiatry).

RESULTS

The time most frequently spent in questionnaire application by the physician was 10 minutes. PRIME-MD detected the presence of at least one psychiatric disorder in 44.3% of patients. PRIME-MD diagnoses agree well with SCAN diagnoses for mood disorders (coefficient of agreement: 0.50) and for anxiety disorders (coefficient of agreement: 0.35), but not for somatoform disorders or alcohol-related disorders.

CONCLUSIONS

The Spanish version of PRIME-MD questionnaire in a useful tool to identify and diagnose mood and anxiety disorders in Primary Care settings.

[Attempted suicide and previous contact with health system]

INTRODUCTION

Suicide behavior is an important health problem. Several works found have reported that the majority of completed suicides visited to the general practitioner in previous days.

METHOD

219 suicide attempts attended in a General Hospital were asked about their previous contact with health system.

RESULTS

The third part of the patients have visited the general practitioner in the previous month. 60% of the patients with personal antecedents of psychiatric diseases have visited to mental services in the previous month.

CONCLUSIONS

It is necessary to find risk suicide markers that allow identifying these patients in primary attention. The increment of the consultation periodicity is proposed as efficient risk suicide marker.

Influence of electrical coupling on early afterdepolarizations in ventricular myocytes

Computer modeling is used to study the effect of electrical coupling between a myocardial zone where early afterdepolarizations (EAD's) can develop and the normal neighboring tissue. The effects of such coupling on EAD development and on the likelihood of EAD propagation as an ectopic beat are studied. The influence on EAD formation is investigated by approximating two partially coupled myocardial zones modeled as two active elements coupled by a junctional resistance R. For R values lower than 800 omega cm2, the action potentials are transmitted to the coupled element, and for R values higher than 850 omega cm2 they are blocked. In both ranges of R, when the electrical coupling increases, the EAD's appear at more negative takeoff potentials with higher amplitudes and upstrokes. The EAD's are not elicited if the electrical coupling is too high. In a separate model of two one-dimensional cardiac fiber segments partially coupled by a resistance R, critical R values exist, between 42 and 54 omega cm2, that facilitate EAD propagation. These results demonstrate that in myocardial zones favorable to the formation of EAD, the electrical coupling dramatically affects initiation of EAD and its spread to the neighboring tissue.

Decreased transcript expression coincident with impaired glycosylation in the beta2-adrenergic receptor gene does not result from differences in the primary sequence

Variants of the S49 mouse lymphoma cell line exhibit multiple lesions along the pathway of cyclic AMP generation in response to beta2-adrenergic stimulation. Two such variants, beta(p) and beta(d), are characterized by decreased receptor binding and mRNA expression, 50% and 25% of wild-type receptor expression, respectively. The rate of beta2-adrenergic receptor synthesis was measured and found to be decreased in the beta d cells vis-a-vis the rate in wild type cells. The molecular mass of the beta2-adrenergic receptor in the S49 wild-type, beta(p) and beta(d) variant cells was estimated by labeling the receptor with the photoaffinity probe [125I]iodocyanopindololdiazirine. Receptor size was found to be 67,000 and 47,000 Da in the wild-type and 60,000 and 42,000 in the two variant cells. This 6 kDa discrepancy in mass was abolished upon treatment of labeled cell extracts with N-glycosidase F, suggesting the possibility of either N-terminal truncation or altered glycosylation of the receptor in the variant cells. To distinguish between these possibilities, we sequenced the beta2-adrenergic receptor gene and two kilobases of the 5'-non-coding region. No differences were found in the coding region of the gene from wild-type, beta(p) and beta(d) S49 cells suggesting that both the diminished expression and the decreased size of beta2-adrenergic receptor in the beta(p) and beta(d) S49 variants are related to impaired glycosylation of the receptor. This hypothesis was substantiated by the reduced retention of the variant cells' beta2-adrenergic receptor on immobilized WGA. Furthermore, growth of the S49 cells in the presence of the alpha-mannosidase II inhibitor, swainsonine, preferentially impaired the ability of the receptors derived from the variant cells to bind to WGA. These results imply that altered expression and glycosylation of G-protein-linked receptors occur as a consequence of one or more mutations outside the receptor's open reading frame.

Double-blind comparison of fluoxetine versus clomipramine in the treatment of obsessive compulsive disorder

There is evidence of the clinical efficacy and safety of clomipramine and the newer selective serotonin reuptake inhibitors (SSRIs) for the treatment of obsessive-compulsive disorder (OCD). In the present study, we have compared the efficacy and safety of 40 mg/day of fluoxetine and 150 mg/day of clomipramine in patients with OCD, diagnosed according to DSM-IIIR. A total of 55 patients entered this 8-week, double-blind controlled study. Efficacy for both drugs was comparable. The primary efficacy criterion, the Y-BOCS Total score, did not show any significant differences between treatment arms. Response rate was higher with clomipramine, using a 25% decrease in Y-BOCS Total score as response threshold, but there were no significant differences between treatment arms using a 35% threshold. Overall safety and tolerability were good for both drugs, being slightly better for fluoxetine.

Alpha-blockade on blood pressure and on cardiac noradrenaline content in SHR and DOCA-salt rats

The current study was designed to explore the effects of peripherally administered alpha-adrenoceptor inhibiting drugs (either prazosin or yohimbine) in spontaneously hypertensive (SHR) and DOCA-salt hypertensive rats before the development of established hypertension, as well as to characterize changes induced by prazosin and/or yohimbine in the cardiac noradrenaline (NA) content that might be responsible for the development of hypertension in these strains. The alpha-adrenoceptor blockade can prevent hypertension in DOCA and salt-treated animals in such a way that their blood pressure stabilizes at levels significantly lower than those observed in similarly treated normotensive controls. Significantly lower cardiac NA content was observed in DOCA-salt rats under basal and experimental conditions. The blood pressure of the treated rats and the heart NA content of the SHR were unaltered by treatment. Thus, administration of the alpha-adrenoceptor blocking agents, prazosin and/or yohimbine, throughout the developmental stage of SHR hypertension failed to alter either the progressive rise in blood pressure or in NA content. There may be differences between the cardiac adrenergic mechanisms responsible for the development of hypertension in each of these two models of hypertension.

Age-related changes of norepinephrine content in kidneys of spontaneously hypertensive and Wistar-Kyoto rats

Renal norepinephrine (NE) content was determined during the development of spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) rats in an attempt to correlate biochemical changes with the reported functional changes occurring in hypertension development in the SHR. In contrast to WKY rats, in which the levels of NE remained relatively constant with age, renal NE content in the SHR was highest at the 4th week of age, decreasing transiently during the 5th, 6th, and 7th weeks, and then again reaching a plateau during the 8th week. The fall in NE content in the kidney is associated with a rise in blood pressure with age in SHR and suggests a relationship between NE levels and hypertension.

Altered renal alpha-adrenoceptor regulation in DOCA-salt rats: chronic effects of alpha 1- and alpha 2-receptor blockers

Effects on the alpha-adrenoceptor binding in the kidneys of DOCA-salt rats were examined after a 6 week treatment of once-daily injections of prazosin, a selective alpha 1-adrenoceptor blocker; yohimbine, a selective antagonist for alpha 2-adrenoceptors; and prazosin plus yohimbine. alpha 1-Receptor binding was decreased by prazosin, while alpha 2-receptor binding was increased by simultaneous administration of prazosin + yohimbine. Equilibrium dissociation constants (KD) for [3H]prazosin and [3H]yohimbine were not significantly different (between groups). Since these drugs can prevent the development of hypertension in DOCA-salt rats, the present data strongly suggests that selective alteration of alpha-receptor-mediated physiological responses is unrelated to decreased or increased binding site densities. The mechanism of hypertension prevention may involve changes in the coupling of receptors to postreceptor events.

Effect of amphetamine and dopamine on oxygen uptake of rat brain slices in vitro

Effects of d-amphetamine and dopamine on rat brain cortical slices respiration were estimated to assess whether these drugs might modify membrane (Na+ + K+)-ATPase activity in intact cells as they do in isolate enzyme systems. d-Amphetamine, 10(-5) M (140%), 10(-6) M (123%) 10(-7) M (131%) and 10(-7) M (129%). These results may be related to estimates of (Na+ + K+)-ATPase activity in subcellular systems. In an incubation medium containing calcium, 10(-4) M ouabain does not modify brain slices respiration, but fully antagonizes oxygen consumption increases induced by d-amphetamine or dopamine, which might thus be mediated by membrane ATPase activity. Either phenoxybenzamine, oxprenolol or halo-peridol, nullify those metabolic effects of d-amphetamine and dopamine, by means of unspecific mechanisms rather than by a specific interaction at drug receptor sites. It is suggested that cell respiratory control is the final resultant of mechanisms which might be separately, and oppositely, modified by drugs.

Isolation of Fibrinogen Protomer by Partial Reduction of Disulfide Bonds in Concentrated Urea

Partial reduction of human and bovine fibrinogen (F). recently dissolved in 6 and 8M deionized urea, with different amounts of dithioeritritol (DTE) (10 to 60:100 DTE:F, w/w) has been carried out in nitrogen atmosphere. Disc gel electrophoresis in 0.1% SDS shows changing amounts of six molecular species depending on the reaction time and DTE:F ratio. Three bands are identical with those obtained by total reduction of fibrinogen, one with unreduced material, the remaining two show mobilities corresponding to molecular weights of 170.000-190.000 (band H, with yields up to 40-50%) and 130.000-140.000 (band N).

Total reduction of the isolated species H shows identical composition in fibrinogen chains as the original material. Stabilization by alkylation of this soecies is only successful in 0.1% SDS. Comparative ultracentrifugation studies show sedimentation coefficients of 6.8 S for fibrinogen incubated with SDS and 4.1 S for the H Species, which agree with a ratio 2:1 for their molecular weights.

These results confirm the existence of two protomer entities easily cleaved by partial reduction but the need of high concentration of urea to separate the protomer, suggests the existence of additional strong non-covalent interactions between the two hemimolecules.