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The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with hadron beams, achieving luminosities of up to 1.0×10^{34} cm^{-2} s^{-1} in the center-of-mass energy range of 20-140 GeV. To achieve such high luminosity, the EIC will employ small and flat beams at the interaction point. In the hadron storage ring of the EIC, the ratio of horizontal to vertical emittances is approximately 11â¶1. In contrast, in previous or existing hadron colliders, the horizontal and vertical emittances are typically similar or closely matched. At the Relativistic Heavy Ion Collider (RHIC), we experimentally demonstrated a large transverse emittance ratio of 11â¶1 with gold ion beams at a particle energy of 100 GeV per nucleon, thanks to stochastic cooling and fine decoupling. Furthermore, we demonstrated collisions with flat beams, featuring a transverse beam size ratio of 3â¶1 for the first time at the RHIC.
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BACKGROUND: Impairments of social cognition are considered core features of schizophrenia and are established predictors of social functioning. However, affective aspects of social cognition including empathy have far less been studied than its cognitive dimensions. The role of empathy in the development of schizophrenia remains largely elusive. METHODS: Emotional and cognitive empathy were investigated in large sample of 120 individuals at Clinical High Risk of Psychosis (CHR-P) and compared with 50 patients with schizophrenia and 50 healthy controls. A behavioral empathy assessment, the Multifaceted Empathy Test, was implemented, and associations of empathy with cognition, social functioning, and symptoms were determined. RESULTS: Our findings demonstrated significant reductions of emotional empathy in individuals at CHR-P, while cognitive empathy appeared intact. Only individuals with schizophrenia showed significantly reduced scores of cognitive empathy compared to healthy controls and individuals at CHR-P. Individuals at CHR-P were characterized by significantly lower scores of emotional empathy and unspecific arousal for both positive and negative affective valences compared to matched healthy controls and patients with schizophrenia. Results also indicated a correlation of lower scores of emotional empathy and arousal with higher scores of prodromal symptoms. CONCLUSION: Findings suggest that the tendency to 'feel with' an interaction partner is reduced in individuals at CHR-P. Altered emotional reactivity may represent an additional, early vulnerability marker, even if cognitive mentalizing is grossly unimpaired in the prodromal stage. Different mechanisms might contribute to reductions of cognitive and emotional empathy in different stages of non-affective psychotic disorders and should be further explored.
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Cognición , Empatía , Trastornos Psicóticos/psicología , Psicología del Esquizofrénico , Cognición Social , Adulto , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Síntomas Prodrómicos , Adulto JovenRESUMEN
Under certain conditions, coercive interventions in psychotic patients can help to regain insight and alleviate symptoms, but can also traumatize subjects. This study explored attitudes towards psychiatric coercive interventions in healthy individuals and persons suffering from schizophrenia, schizoaffective or bipolar disorder. The impact of personal history of coercive treatment on preferences concerning clinical management of patients unable to consent was investigated. Six case vignettes depicting scenarios of ethical dilemmas and demanding decisions in favour of or against coercive interventions were presented to 60 healthy volunteers and 90 patients. Structured interviews focusing on experienced coercion were performed in conjunction with the Coercion Experience Scale and the Admission Experience Survey. Symptom severity, psychosocial functioning and insight into illness were assessed as influencing variables. Student's t tests compared patients' and controls' judgments, followed by regression analyses to define the predictive value of symptoms and measures of coercion on judgments regarding the total patient sample and patients with experience of fixation. Patients and non-psychiatric controls showed no significant difference in their attitudes towards involuntary admission and forced medication. Conversely, patients more than controls significantly disapproved of mechanical restraint. Subjective experience of coercive interventions played an important role for the justification of treatment against an individual's "natural will". Factors influencing judgments on coercion were overall functioning and personal experience of treatment effectiveness and fairness. Qualitative and quantitative aspects of perceived coercion, in addition to insight into illness, predicted judgments of previously fixated patients. Results underline the importance of the quality of practical implementation and care, if coercive interventions cannot be avoided.
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Coerción , Hospitales Psiquiátricos , Trastornos Mentales/psicología , Trastornos Mentales/terapia , Restricción Física/métodos , Restricción Física/psicología , Adolescente , Adulto , Femenino , Voluntarios Sanos/psicología , Humanos , Juicio , Masculino , Trastornos Mentales/clasificación , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Escalas de Valoración Psiquiátrica , Psicoterapia/métodos , Encuestas y Cuestionarios , Adulto JovenRESUMEN
BACKGROUND: Post-coercion review has been increasingly regarded as a useful intervention in psychiatric inpatient setting. However, little is known about its effect on perceived coercion. METHODS: A multicenter, two-armed, randomized controlled trial was conducted, aiming at analyzing the effect of post-coercion review on perceived coercion. People with severe mental disorders, who experienced at least one coercive measure during inpatient treatment, were randomized using Zelen's design to an intervention group receiving standardized post-coercion review, or a control group treated as usual. The MacArthur admission experience scale (AES) and the coercion ladder (CL) were used to assess perceived coercion during inpatient treatment. The coercion experience scale (CES) measured experienced coercion during the coercive intervention. Analyses of covariance were performed to determine group differences. RESULTS: Of 422 randomized participants, n = 109 consented to participate in the trial. A restricted intention-to-treat analysis of all individuals who consented revealed no significant effect of the intervention on perceived coercion. A significant interaction effect between the factors gender and intervention on the AES scores was found. Sensitivity analysis revealed significant effects of the intervention on both AES and CL scores and an interaction effect between intervention and gender, indicating a higher efficacy in women. No effect of the intervention on CES scores was found. CONCLUSIONS: Standardized post-coercion review sessions did not alleviate the subjective perception of coercion in the total sample. However, post hoc analysis revealed a significant effect of the intervention in women. Results indicate the need to further address gender-specific issues related to coercion.
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Coerción , Trastornos Mentales , Femenino , Hospitalización , HumanosRESUMEN
Prejudices can lead to discrimination, social exclusion, and violence particularly among young male adults. Previous findings suggest that the degree of holding prejudices is linked to low levels of empathy, while low levels of empathy have been associated with alexithymia, the inability to experience one's own feelings. We tested the hypothesis that the impact of a lack of empathy on reporting blatant and subtle prejudices is moderated by the inability to identify one's own feelings. In a sample of n = 136 young male adults aged 21 years (mean = 21.5 years; sd = 0.3), we conducted correlation and moderator analyses to determine possible relationships between prejudices, empathy, and alexithymia as assessed by self-report questionnaires. Prejudices were assessed by the Blatant and Subtle Prejudice Scale (BSPS), empathy was assessed by the German modified version of the Interpersonal Reactivity Index (IRI), and alexithymia by the 20-item Toronto Alexithymia Scale (TAS-20). Self-reported empathy levels were correlated with the strength of subtle and blatant prejudices. The moderation analyses revealed that the negative association between empathy and subtle prejudice increased with decreasing alexithymia. The negative association between empathy and blatant prejudice, on the other hand, was significant only for participants with low levels of alexithymia. These results suggest that empathy can limit the expression of blatant and to some degree also subtle prejudice when subjects are capable to identify their own feelings in a group of young males.
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Emociones , Empatía , Adulto , Síntomas Afectivos , Humanos , Masculino , Prejuicio , Encuestas y Cuestionarios , Adulto JovenRESUMEN
BACKGROUND: The role of the brain-derived neurotrophic factor (BDNF) in the pathogenesis of affective disorders such as depression has been controversial. Mounting evidence comes from structural imaging, that the functional BDNF Val66Met polymorphism influences the hippocampal volume with carriers of the 66Met allele (Val/Met and Met/Met group) having smaller hippocampi. Given that stress-induced atrophy of the hippocampus is associated with the pathogenesis of affective disorders, the functional BDNF Val66Met polymorphism could be an incremental risk factor. METHOD: Eighty-seven healthy Caucasian participants underwent structural imaging and were genotyped for the BDNF Val66Met polymorphism. Data were analysed by means of voxel-based morphometry (VBM). RESULTS: Region of interest (ROI) analyses revealed an association between the 66Met allele and smaller parahippocampal volumes and a smaller right amygdala. In addition, the whole-brain analysis showed that the thalamus, fusiformus gyrus and several parts of the frontal gyrus were smaller in 66Met allele carriers. CONCLUSIONS: This study demonstrates that the impact of the BDNF Val66Met polymorphism is not confined to the hippocampus but also extends to the parahippocampal gyrus and the amygdala.
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Alelos , Amígdala del Cerebelo/patología , Factor Neurotrófico Derivado del Encéfalo/genética , Trastorno Depresivo/genética , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Giro Parahipocampal/patología , Polimorfismo Genético/genética , Adulto , Atrofia , Encéfalo/patología , Mapeo Encefálico , Trastorno Depresivo/diagnóstico , Dominancia Cerebral/genética , Femenino , Lóbulo Frontal/patología , Tamización de Portadores Genéticos , Predisposición Genética a la Enfermedad/genética , Genotipo , Hipocampo/patología , Humanos , Masculino , Valores de Referencia , Factores de Riesgo , Tálamo/patología , Adulto JovenRESUMEN
Imaging studies have demonstrated that prefrontal and parietal regions are activated during working memory (WM) tasks. Recently some molecular genetic studies reported associations between a functional promoter polymorphism of the tryptophan hydroxylase 2 gene (TPH2), that regulates the synthesis of serotonin, and attention. In 49 healthy Caucasian subjects the role of the TPH2 -703 G/T polymorphism for WM was tested by means of an imaging genomics approach in an n-back task. fMRI data showed an increased activation for the 2-back as compared to the 0-back condition for a large network in prefrontal and parietal areas. Although behavioural data showed no performance differences between the genotype groups of the -703 G/T a significantly stronger activation of the TT genotype carriers in BA 6, BA 46, and BA 40 was visible in contrast to the GT and GG groups. Present findings in congruence with previous findings support the hypothesis that TT carriers compensate deficits in executive control functions by increased brain activity.
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Memoria a Corto Plazo/fisiología , Triptófano Hidroxilasa/genética , Adulto , Atención/fisiología , Encéfalo/anatomía & histología , Química Encefálica/genética , Química Encefálica/fisiología , Cognición/fisiología , ADN/genética , Femenino , Genotipo , Humanos , Imagen por Resonancia Magnética , Masculino , Oxígeno/sangre , Polimorfismo Genético/genética , Polimorfismo de Nucleótido Simple/genética , Desempeño Psicomotor/fisiología , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
BACKGROUND: Increasing evidence indicates impairments of empathic abilities in schizophrenia that may impact outcome and course of the disease. While there is consensus on the presence of deficits in 'theory of mind' in this disorder, i.e. cognitive aspects of mental state attribution, the ability to infer emotional experiences of others, i.e. affective empathy, has not been investigated so far. METHODS: We assessed multiple dimensions of empathy in 45 schizophrenic patients and 45 healthy controls, matched for age and gender, with a self-rating instrument, the Interpersonal Reactivity Index (IRI). To control for modulating effects of cognitive deficits, a neuropsychological test battery was employed. RESULTS: Schizophrenic patients showed significantly lower scores in cognitive empathy ('perspective taking': F=12.176, df=1, p=0.001) but more self-related aversive feelings in response to the distress of others ('personal distress: F=16.477, df=1, p<0.001). Self-ratings of affective empathy, i.e. concern for others, did not differ between groups. Results in the domains of empathy were not explained by symptoms or neurocognition as revealed by regression analysis. However, lower scores in 'perspective taking' were found with advancing duration of illness (r=-0.453, p=0.002). CONCLUSIONS: Results indicate reductions of cognitive empathy but relatively preserved emotional empathic abilities in schizophrenia. Although previous studies observed deficits in emotion perception and expression, our findings support the concept of differentially disturbed abilities in cognitive and emotional empathy in schizophrenia.
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Empatía , Teoría Psicológica , Esquizofrenia/epidemiología , Percepción Social , Encuestas y Cuestionarios , Adulto , Trastornos del Conocimiento/diagnóstico , Trastornos del Conocimiento/epidemiología , Demografía , Femenino , Humanos , Relaciones Interpersonales , Masculino , Pruebas NeuropsicológicasRESUMEN
Meyer [Phys. Rev. E 50, 1485 (1994)] analyzed the filtering mechanism of polarizing a stored beam by scattering from an internal polarized target. We noticed in Meyer's derivation of Eq. (4) of that paper that he had added a new twist to an old argument [W. Brückner, Physics with Antiprotons at LEAR in the ACOL Era: Proceedings of the Third LEAR Workshop, Tignes, Savoie, France, January 19-26, 1985 (Editions Frontières, Gif-sur-Yvette, France, 1985), p. 245] by allowing some particles that are spin flipped to be kept in the beam. We show that this invalidates the old result and leads to a more complicated expression for the buildup of polarization.
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Loss aversion is a decision bias, reflecting a greater sensitivity to losses than to gains in a decision situation. Recent neuroscientific research has shown that mesocorticolimbic structures like ventromedial prefrontal cortex and the ventral striatum constitute a bidirectional neural system that processes gains and losses and exhibits a neural basis of loss aversion. On a functional and structural level, the amygdala and insula also seem to play an important role in the processing of loss averse behavior. By applying voxel-based morphometry to structural brain images in N=41 healthy participants, the current study provides further evidence for the relationship of brain structure and loss aversion. The results show a negative correlation of gray matter volume in bilateral posterior insula as well as left medial frontal gyrus with individual loss aversion. Hence, higher loss aversion is associated with lower gray matter volume in these brain areas. Both structures have been discussed to play important roles in the brain's salience network, where the posterior insula is involved in interoception and the detection of salience. The medial frontal gyrus might impact decision making through its dense connections with the anterior cingulate cortex. A possible explanation for the present finding is that structural differences in these regions alter the processing of losses and salience, possibly biasing decision making towards avoidance of negative outcomes.
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Anticipación Psicológica , Corteza Cerebral/patología , Toma de Decisiones , Adulto , Amígdala del Cerebelo/patología , Femenino , Juego de Azar/patología , Sustancia Gris/patología , Humanos , Imagen por Resonancia Magnética , Masculino , Tamaño de los Órganos , Corteza Prefrontal/patología , Adulto JovenRESUMEN
Two recent studies from Australia and Germany have both shown that people who stutter (PWS) have elevated Neuroticism scores on the widely used NEO Five Factor Inventory (NEO-FFI) compared to individuals in a control sample. The two studies showed opposite results, however, for the personality traits Agreeableness and Conscientiousness. One reason for these opposing findings could be that the two studies were conducted in different cultural settings. Given that the effect of different cultural background on the relationship between the NEO-FFI and stuttering remains an open question, we investigated the NEO-FFI scores from 98 PWS and an age- and sex-matched control-group from a less widely studied cultural background (Iran). Overall, the present study showed, in line with a study from Germany, higher Agreeableness, but not Neuroticism, in PWS compared to normally fluent controls. To get further insights into these findings, we also contrasted both samples from Iran with a healthy matched sample from Germany. The resulting cross-cultural differences from these analyses are also discussed in the present paper. Although the present study is limited by a cross-sectional design, and so no causal conclusions can be drawn, the authors discuss whether the replicated elevated Agreeableness scores in PWS might represent a self-defense mechanism to cope with one's own speech handicap.
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Personalidad , Tartamudeo/psicología , Adolescente , Adulto , Estudios Transversales , Femenino , Humanos , Irán , Masculino , Modelos Psicológicos , Pruebas de Personalidad , Adulto JovenRESUMEN
BACKGROUND: Diffusion Tensor Imaging studies have repeatedly shown a decrease of the fractional anisotropy (FA) parameter in patients with schizophrenia. This has been interpreted as a disturbed microstructural integrity of white matter. However, FA is a relative parameter that is derived from eigenvalues of the diffusion tensor and FA reductions may be the result of decreases in parallel diffusivity (PD) or increases in radial diffusivity (RD). Despite the well-established FA reduction in schizophrenia, little is known what this reduction is based on. METHODS: Seventeen patients with schizophrenia were scanned with a DTI protocol and compared to a group of healthy control subjects. In addition to an FA comparison, a detailed analysis of PD and RD values was performed with two approaches to localize changes in diffusion values, i.e. a voxel-based analysis and an anatomically based tract specific analysis. RESULTS: We found significantly decreased FA values in the patient group when compared to healthy controls. FA decreases were based on an increase in RD, while we observed no significant changes of PD. These changes were predominantly localized in frontal and temporal areas. CONCLUSION: RD increases as the underlying change in FA decreases is suggestive of desintegration of myelin, which is in line with histopathological studies suggesting a disturbed myelination in schizophrenia.
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Enfermedades Desmielinizantes/patología , Imagen de Difusión Tensora , Lóbulo Frontal/patología , Fibras Nerviosas Mielínicas/patología , Esquizofrenia/patología , Lóbulo Temporal/patología , Adulto , Anisotropía , Estudios de Casos y Controles , Femenino , Humanos , Interpretación de Imagen Asistida por Computador , Masculino , Persona de Mediana Edad , Técnicas de Trazados de Vías Neuroanatómicas , Adulto JovenRESUMEN
Recent functional imaging studies that examined functional connectivity in the resting brain have demonstrated various intrinsic connectivity networks (ICNs). Certain patterns of over- and underactivity in various ICNs have been hypothesized to form the neural basis of psychiatric disorders. Furthermore, activity in the ICNs does not reflect ongoing mental activity but the maintenance of neural circuits in a ready state suggesting not only relationships between ICNs and disorders but also correlations between ICNs and personality. In the present study, we assess the relationship between trait anxiety, a well established endophenotype of anxiety disorders, and functional connectivities within the insular salience ICN in a sample of healthy female subjects. Based on a previous study that demonstrated the functional relevance of the insular salience ICN for state anxiety, we used the harm avoidance scale from the Temperament and Character Inventory (TCI) as a trait marker to demonstrate increased functional connectivity within the insular salience ICN. Specifically, the functional connectivity between the anterior insula and the anterior cingulate and between the anterior insula and the dorsolateral prefrontal cortex were positively correlated with individual harm avoidance scores. The results fit into previous work, provide evidence for a potential biomarker of anxiety disorders and, most importantly, demonstrate a direct neural correlate of the personality trait harm avoidance in the absence of external stimulation.
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Mapeo Encefálico , Encéfalo/fisiología , Reducción del Daño/fisiología , Vías Nerviosas/fisiología , Descanso , Temperamento , Adolescente , Adulto , Encéfalo/irrigación sanguínea , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Individualidad , Imagen por Resonancia Magnética , Vías Nerviosas/irrigación sanguínea , Oxígeno , Inventario de Personalidad , Adulto JovenRESUMEN
The temporal lobe plays a major role in anxiety and depression disorders and is also of importance for trait anxiety in the non-pathological range. The present study investigates self-report data of personality dimensions linked to trait anxiety in the context of white matter tract integrity in the temporal lobes of the human brain in a large sample of N=110 healthy participants. The results show that especially in men values for fractional anisotropy of several white matter tracts in the temporal lobe of the left hemisphere correlate substantially with individual differences in trait anxiety (depending on the tract investigated between .40 and .49). The present study shows that not only data from functional magnetic resonance imaging (fMRI), but also from structural diffusion tensor imaging (DTI) provide interesting insights into the biological foundation of human personality traits.
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Ansiedad/patología , Individualidad , Fibras Nerviosas Mielínicas/patología , Caracteres Sexuales , Lóbulo Temporal/patología , Adolescente , Adulto , Anisotropía , Mapeo Encefálico , Imagen de Difusión Tensora , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , PersonalidadRESUMEN
The present fMRI study investigates individual differences in human brain activity during listening to one's favorite and one's most unlikeable song. In 33 participants, we found that the contrast of listening to pleasant versus unpleasant music revealed a robust activation of the ventral striatum, the caudate nucleus and the insula across a group of participants. Moreover, we could demonstrate that activity within the ventral striatum was modulated by the subscale 'self-forgetfulness' of the character dimension 'self-transcendence'.
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Mapeo Encefálico/psicología , Núcleo Caudado/fisiología , Corteza Cerebral/fisiología , Cuerpo Estriado/fisiología , Música/psicología , Inventario de Personalidad , Recompensa , Adulto , Percepción Auditiva/fisiología , Mapeo Encefálico/métodos , Femenino , Humanos , Individualidad , Imagen por Resonancia Magnética/métodos , Masculino , Vías Nerviosas/fisiologíaRESUMEN
The brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family and involved in nerve growth and survival. It has also become a major research focus in the investigation of both cognitive and affective processes in the human brain in the last years. Especially, a single nucleotide polymorphism on the BDNF gene called BDNF Val66Met gained a lot of attention, because of its effect on activity-dependent BDNF secretion and its link to negative emotionality and impaired memory processes. A well-replicated finding from genetic structural imaging showed that carriers of the less frequent 66Met allele show diminished gray matter volume in several areas of the temporal lobe. New imaging techniques like diffusion tensor imaging now allow investigating the influence of BDNF Val66Met on white matter integrity. We applied tract-based spatial statistics in a brain image dataset including n = 99 healthy participants. No significant differences between the 66Met and homozygous 66Val carriers were observed when correcting for multiple comparisons. In summary, the BDNF Val66Met polymorphism seems not to play a substantial role with respect to the modulation of the white matter integrity in healthy subjects. Although not in the focus of this study, we also investigated the influence of Eysenck's Personality Questionnaire on the white matter tracts. No significant results could be observed.
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Factor Neurotrófico Derivado del Encéfalo/genética , Encéfalo/anatomía & histología , Fibras Nerviosas Mielínicas/diagnóstico por imagen , Adulto , Encéfalo/diagnóstico por imagen , Femenino , Humanos , Masculino , Tamaño de los Órganos , Polimorfismo de Nucleótido Simple , Radiografía , Valores de Referencia , Adulto JovenRESUMEN
The Brookhaven Relativistic Heavy Ion Collider (RHIC) has been providing collisions of polarized protons at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the intrinsic spin resonances beyond 100 GeV are about a factor of 2 stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were first accelerated to the record energy of 205 GeV in RHIC with a significant polarization measured at top energy in 2005. This Letter presents the results and discusses the sensitivity of the polarization survival to orbit distortions.
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Porcine stored blood has been used in the in vitro feeding of the soft tick Ornithodoros moubata through a Parafilm membrane. The efficiency of the feeding decreased after storage of 5 weeks by -20 degrees C. Through addition of 10(-3) M ATP/l the feeding results with frozen blood for duration of storage up to 200 days well agreed with the results of feeding tests with fresh porcine blood: The nymphs (N)1-3 fed the 4-5fold, the N4-6 the 2.7fold and the adults (A) the 1.9fold of their body weight. The feeding rate was 98.6% (N1-3); 92.7% (N4-5) and 81.9% (A). The mortality rate was under 10%. Females laid 130 eggs after blood meal.
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Conservación de la Sangre , Criopreservación , Porcinos/sangre , Garrapatas/crecimiento & desarrollo , Animales , Medios de Cultivo , Femenino , Ninfa/crecimiento & desarrollo , Oviposición , Garrapatas/fisiologíaRESUMEN
Studies in humans and experimental animal models suggest that volume overload increases and volume underload decreases release of atrial natriuretic peptide (ANP), a hormone intimately linked to water and electrolyte homeostasis. This relationship was examined in dogs suffering from heart failure or dehydration and the data presented here are in support of this general concept. Plasma ANP concentration in dogs with congestive heart failure (CHF) was elevated with the severity of the disease (NYHA classification, class II: 21.4 +/- 9.2 fmol ANP/ml; class III: 65.5 +/- 72.6; class IV: 119.7 +/- 87.1; healthy dogs: 13.9 +/- 7.5). The increment in plasma ANP concentration in cardiac patients was also positively correlated with the plasma volume. The blood volume of dogs with moderate and severe CHF was significantly (P < 0.05) elevated and a normotonic blood pressure prevailed. In contrast, dehydrated dogs tend to display reduced ANP plasma concentration (7.7 +/- 5.6 fmol/ml) as well as significantly lower plasma volume and reduced blood pressure (P < 0.05). In dogs with severe CHF, ANP precursor material is present in the blood, which is normally undetectable. These data further support the concept of a regulatory function of ANP in volume homeostasis of dogs.