Biomedical subjects

A Heinz

Publications and source records attributed to A Heinz.

At least 55 records · Page 3Linked to original sources

PubMed2002

Large angle elastic alpha scattering on a N=Z nucleus above A=40.

Scattering of alpha particles from 44Ti, the lightest unstable alpha-particle nucleus above A=40, has been measured at backward angles. The "anomalous" order-of-magnitude enhancement that is characteristic of 40Ca and other light alpha-particle nuclei is not observed. Instead, the backward yield is similar to that observed for other nuclei heavier than 40Ca, and is well described with average optical model parameters.

Journal Article↗

PubMed2002

Dopaminergic dysfunction in alcoholism and schizophrenia--psychopathological and behavioral correlates.

Dysfunction of central dopaminergic neurotransmission has been implicated in the pathogenesis of schizophrenia as well as drug and alcohol dependence. Different drugs of abuse stimulate dopamine release in the ventral striatum and thus reinforce drug consumption. Increased subcortical dopamine release has also been associated with the pathogenesis of positive symptoms in schizophrenia and may be driven by a prefrontal dopaminergic dysfunction. These seemingly heterogeneous findings may be explained by recent research in non-human primates. According to these studies, reward anticipation but not anticipated reward consumption is accompanied by a phasic dopamine release in the striatum and prefrontal cortex. In the striatum, phasic dopamine release primarily affects motivation, psychomotor activation and reward craving, while in the prefrontal cortex, dopaminergic stimulation is involved in the activation of working memory and reward anticipation. In alcoholism, previously neutral stimuli that have been associated with alcohol intake can become conditioned cues which activate phasic dopamine release and reward craving. In schizophrenia, stress-induced or chaotic activation of dopamine release may attribute incentive salience to otherwise irrelevant stimuli and thus be involved in the pathogenesis of delusional mood and other positive symptoms. Studies in humans and non-human primates emphasize the role of dopaminergic neurotransmission in reward anticipation and its dysfunction in different neuropsychiatric diseases.

Alcoholism↗

PubMed2002

Stimulus-induced craving and startle potentiation in abstinent alcoholics and controls.

Abstinent alcoholics often deny craving for alcohol but still show a high level of relapse. The eyeblink response to startling noise was used as an indicator of the emotional response to alcohol-related, positive, negative and neutral visual stimuli in abstinent alcoholics, social drinkers and rarely drinking controls. The cognitive evaluation of the stimuli was assessed by ratings of subjective craving, valence and arousal. The startle response of the alcoholics to alcohol-related stimuli was significantly inhibited despite an aversive overt stimulus-evaluation. These findings indicate that alcohol-related stimuli may have appetitive incentive salience for alcoholics in spite of verbal reports of craving and valence to the opposite.

Acoustic Stimulation↗

PubMed2002

Development of alcohol-associated cues and cue-induced brain activation in alcoholics.

The objective of this study was to develop new standardized alcohol-associated cues and assess their effects on brain activation with functional magnetic resonance imaging (fMRI). Pictures of alcoholic and neutral beverages and affectively neutral pictures were presented to 44 abstinent alcoholics and 37 age-matched healthy control subjects. We assessed the skin conductance response, and the elicited arousal and valence. Alcoholics and control subjects did not differ in arousal, valence or skin conductance response evoked by alcohol-associated and affectively neutral stimuli, while nonalcoholic beverages were rated as more unpleasant and arousing by alcoholics compared with control subjects. In the fMRI pilot study, alcohol and abstract pictures were presented to six abstinent alcoholics and induced a significant activation of brain areas associated with visual emotional processes such as the fusiform gyrus, parts of the brain reward system (basal ganglia and orbitofrontal gyrus) and further brain regions in the frontal and parietal cortices associated with the attention network. These observations suggest that standardized pictures of alcoholic beverages can be used to assess brain circuits involved in the processing and evaluation of alcohol cues.

Adult↗

PubMed2002

Thyroid hormones, serotonin and mood: of synergy and significance in the adult brain.

The use of thyroid hormones as an effective adjunct treatment for affective disorders has been studied over the past three decades and has been confirmed repeatedly. Interaction of the thyroid and monoamine neurotransmitter systems has been suggested as a potential underlying mechanism of action. While catecholamine and thyroid interrelationships have been reviewed in detail, the serotonin system has been relatively neglected. Thus, the goal of this article is to review the literature on the relationships between thyroid hormones and the brain serotonin (5-HT) system, limited to studies in adult humans and adult animals. In humans, neuroendocrine challenge studies in hypothyroid patients have shown a reduced 5-HT responsiveness that is reversible with thyroid replacement therapy. In adult animals with experimentally-induced hypothyroid states, increased 5-HT turnover in the brainstem is consistently reported while decreased cortical 5-HT concentrations and 5-HT2A receptor density are less frequently observed. In the majority of studies, the effects of thyroid hormone administration in animals with experimentally-induced hypothyroid states include an increase in cortical 5-HT concentrations and a desensitization of autoinhibitory 5-HT1A receptors in the raphe area, resulting in disinhibition of cortical and hippocampal 5-HT release. Furthermore, there is some indication that thyroid hormones may increase cortical 5-HT2 receptor sensitivity. In conclusion, there is robust evidence, particularly from animal studies, that the thyroid economy has a modulating impact on the brain serotonin system. Thus it is postulated that one mechanism, among others, through which exogenous thyroid hormones may exert their modulatory effects in affective illness is via an increase in serotonergic neurotransmission, specifically by reducing the sensitivity of 5-HT1A autoreceptors in the raphe area, and by increasing 5-HT2 receptor sensitivity.

Affect↗

PubMed2002

Relationship between cortisol and serotonin metabolites and transporters in alcoholism [correction of alcolholism].

BACKGROUND: Stress hormone activation may induce clinical depression via an interference with central serotonergic neurotransmission. In alcoholics, a reduction in serotonin transporters was associated with clinical depression, and an activation of cortisol secretion is frequently found during detoxification. We assessed the interaction between stress hormone activation, serotonin transporters, monoamine metabolites in the cerebrospinal fluid (CSF), and mood states in male and female alcoholics and healthy control subjects. METHODS: The availability of serotonin transporters was measured with [I-123]beta-CIT and SPECT in the raphe area of the brainstem in 31 alcoholics after four weeks of abstinence and in 25 age-matched healthy volunteers. Concentrations of plasma cortisol were measured on the day of the SPECT scan. Within one week after the SPECT scan, we assessed monoamine metabolites and corticotropin-releasing factor (CRF) in the CSF. RESULTS: Clinical depression was associated with a reduction in serotonin transporter availability among male alcoholics. Among male alcoholics and healthy volunteers, CSF 5-HIAA and plasma cortisol concentrations were inversely correlated with the availability of raphe serotonin transporters and positively correlated with the severity of clinical depression. No significant correlations were observed between raphe serotonin transporters and HVA, MHPG and CRF concentrations in the CSF. CONCLUSION: Our findings support the hypothesis of an interaction between reduced serotonin transporters, stress hormone activation and clinical depression. They confirm the hypothesis that serotonergic neurotransmission dysfunction in alcoholism is limited to male alcoholics. The observed interactions between high cortisol concentrations and reduced serotonin transporter availability warrant further studies in major depression and other neuropsychiatric diseases with implied cortisol activation and serotonergic dysfunction.

Adult↗

PubMed2001

Identification of the I(pi) = 10(+) Yrast rotational state in 24Mg.

Spins and parities of high spin states above the particle-binding threshold in 24Mg were determined with a basis expansion technique using triple and quadruple angular correlations between alpha particles and gamma rays. The first unambiguous identification of a 10(+) state is reported. Located at 19.2(1) MeV, this state decays predominantly by alpha emission, although a candidate gamma-decay branch with a 5.927 MeV transition connecting this 10(+) level to the rotational 8(+) state at 13.2 MeV was identified as well. The corresponding gamma-alpha branching ratio is 7(3)x10(-4).

Journal Article↗

PubMed2001

Rotational bands in the proton emitter (141)Ho.

Rotational bands feeding the ground state and the isomeric state in the proton emitter (141)Ho were observed using the recoil-decay tagging method. This constitutes direct evidence that (141)Ho is deformed. A quadrupole deformation of beta(2) = 0.25(4) was deduced for the ground state from the extracted dynamic moment of inertia. Based on observed band crossings and signature splittings the 7/2(-)[523] and 1/2(+)[411] configurations were proposed for the ground state and the isomeric state, respectively. Comparison with particle-rotor calculations for beta(2) = 0.25 indicates, however, that (141)Ho may have significant hexadecapole deformation and could be triaxial in the 7/2(-)[523] ground state.

Journal Article↗

PubMed2001

[History and prospects of transcultural psychiatry and psychotherapy].

Transcultural psychiatry and psychotherapy gained importance with the presence of immigrants and refugees in contemporary society. Transcultural psychiatry examines the interaction of culture with the symptoms and course of mental disorders. It focuses on communication and knowledge transfer between professionals and patients and reflects cultural limits in the perception and classification of psychiatric diseases. The past, present, and future of transcultural psychiatry were discussed during a symposium held in Berlin at a meeting of the Society for Philosophy and the Psychological Sciences and the German Society for Anthropological Medicine, Psychology, and Psychotherapy.

Berlin↗

PubMed2001

Alcohol-associated stimuli activate the ventral striatum in abstinent alcoholics.

Alcohol-associated cues may act as conditioned stimuli that activate the brain reward system and motivate alcohol intake in alcoholics. Alcohol-associated visual stimuli were presented during functional magnetic resonance imaging. An activation of the ventral putamen was observed in alcoholics but not in control subjects. Patients with a strong activation of the ventral putamen relapsed during the next three months. This observation supports the hypothesis that alcohol use affects areas involved in brain reward circuits and that their stimulus-induced activation may be associated with an increased risk for relapse.

Adult↗

PubMed2001

Psychopathological correlates of reduced dopamine receptor sensitivity in depression, schizophrenia, and opiate and alcohol dependence.

A dysfunction of central dopaminergic neurotransmission has been found in various neuropsychiatric diseases, and may be associated with a common psychopathological correlate. One hypothesis suggests that dopaminergic stimulation of the brain reward system reinforces behavior because it is experienced as pleasurable, and that dopaminergic dysfunction leads to anhedonia, the inability to experience pleasure. An alternative hypothesis assumes that dopaminergic stimulation does not promote pleasure or "liking" of a reward but rather mediates "wanting" of a reward, and suggests that dopaminergic dysfunction is associated with a failure to be motivated by stimuli that indicate reward. We measured negative symptoms, psychomotor slowing and dopamine receptor sensitivity in twelve drug-free patients with major depression, seventeen alcohol-dependent and sixteen opiate-dependent patients, ten schizophrenics with neuroleptic medication, and ten healthy controls. The sensitivity of central dopamine receptors was assessed with the growth hormone response to apomorphine application. Psychomotor slowing was measured in a reaction-time test and anhedonia and other negative symptoms were assessed with self-rating scales and the Scale for the Assessment of Negative Symptoms. Patients with major depression, alcohol dependence and neuroleptic medication displayed a reduced sensitivity of central dopamine receptors compared to control subjects. Anhedonia was not a common correlate of dopamine receptor dysfunction. Instead, affective flattening was associated with both dopamine receptor sensitivity and psychomotor slowing. Our findings thus do not support the anhedonia hypothesis of central dopaminergic dysfunction. Rather, affective flattening may result from the lack of an emotional response towards reward-indicating stimuli. These findings indicate that patients with dopaminergic dysfunction are not unable to experience pleasure, but may fail to be motivated by environmental stimuli to seek reward.

Adult↗

PubMed2001

Neuroimaging in alcoholism: ethanol and brain damage.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The co-chairs were Karl Mann and Ingrid Agartz. The presentations were (1) Neuropathological changes in alcohol-related brain damage, by Clive Harper; (2) Regional brain volumes including the hippocampus and monoamine metabolites in alcohol dependence, by Ingrid Agartz, Susan Shoaf, Robert R, Rawlings, Reza Momenan, and Daniel W Hommer; (3) Diffusion tensor abnormalities in imaging of white matter alcoholism, by Adolf Pfefferbaum and Edith V. Sullivan; (4) Use of functional MRI to evaluate brain activity during alcohol cue exposure in alcoholics: Relationship to craving, by Raymond F. Anton, David J. Drobes, and Mark S. George; and (5) mu-Opiate receptor availability in alcoholism: First results from a positron emission tomography study, by Karl Mann, Roland Bares, Hans-Juergen Machulla, Goetz Mundle, Matthias Reimold, and Andreas Heinz.

Alcoholism↗

PubMed2001

Serotonergic dysfunction, negative mood states, and response to alcohol.

BACKGROUND: Dysfunction of central serotonergic neurotransmission has been implicated in the pathogenesis and maintenance of alcoholism. Serotonergic dysfunction may be associated with three behavior patterns relevant for alcoholism: impulsive aggression, negative mood states, and a low response to alcohol intake. METHODS: We reviewed the literature on the psychopathological correlates of serotonergic dysfunction and focused on studies that assess the interaction between negative mood states and alcohol response. RESULTS: Prospective studies in nonhuman primates that underwent early separation stress found an association between a low serotonin turnover rate and the disposition to excessive alcohol intake and impulsive aggression. These findings seem to be relevant for a subgroup of alcoholics with a low serotonin turnover rate and antisocial personality traits. Cross-sectional data in humans also support a relationship between reduced serotonergic neurotransmission and aggressive behavior and indicate that the association of serotonergic dysfunction and aggression may be mediated by negative mood states. This hypothesis is in accordance with a large body of data linking anxiety and depression to serotonergic dysfunction. In human alcoholics, brain imaging has detected a reduction in serotonin transporter availability in association with depression. Serotonin transporter availability seems to be related to reduced GABA-ergic sedation and the acute response to alcohol intake, an important predictor of subsequent development of alcohol dependence. CONCLUSIONS: Several lines of evidence point to a relationship between serotonergic dysfunction, negative mood states, and excessive alcohol intake, which may be mediated in part by reduced alcohol-induced sedation.

Affect↗

PubMed2000

Entry distribution, fission barrier, and formation mechanism of 254102No

The entry distribution in angular momentum and excitation energy for the formation of 254No has been measured after the 208Pb(48Ca,2n) reaction at 215 and 219 MeV. This nucleus is populated up to spin 22Planck's over 2pi and excitation energy greater, similar6 MeV above the yrast line, with the half-maximum points of the energy distributions at approximately 5 MeV for spins between 12Planck's over 2pi and 22Planck's over 2pi. This suggests that the fission barrier is greater, similar5 MeV and that the shell-correction energy persists to high spin.

Journal Article↗

PubMed2000

A relationship between serotonin transporter genotype and in vivo protein expression and alcohol neurotoxicity.

BACKGROUND: Genetic variation of the promoter for the serotonin transporter (5-HTT) gene has been associated with its functional capacity. In vitro, carriers of a short allele (s-carriers) of the 5-HTT promoter display significant reduction in 5-HTT capacity. Dysfunction of 5-HTT has been observed in alcoholic individuals. We assessed whether the allelic constitution of the 5-HTT gene is associated with reduced serotonin transporter availability among alcoholic individuals. METHODS: We genotyped the 5-HTT promoter region and measured the availability of serotonin transporter protein with [I-123]beta-CIT SPECT in the raphe area in 14 abstinent male alcoholic subjects and 8 age-matched control subjects of European American descent. RESULTS: Among control subjects, the ratio of in vivo 5-HTT availability for ll-homozygous individuals relative to s-carriers was comparable to serotonin uptake ratios measured in vitro. There was a significant interaction of diagnosis and 5-HTT promoter genotype on 5-HTT availability (p <.01). Among controls, ll-homozygous individuals displayed a significant increase as compared with s-carriers. The availability of raphe 5-HTT was significantly reduced in ll-homozygous alcoholic individuals and was negatively correlated with their amount of alcohol consumption. Among s-carriers, 5-HTT availability did not differ significantly between control and alcoholic subjects. CONCLUSIONS: Our preliminary findings suggest an association between 5-HTT allelic constitution and in vivo measurements of human serotonin transporter availability, and a potentially selective susceptibility of ll-homozygous individuals to the neurotoxic effects of chronic excessive alcohol consumption.

Adult↗

PubMed2000

The 44Ti(alpha,p) reaction and its implication on the 44Ti yield in supernovae

Cross sections for the 44Ti(alpha,p)47V reaction which significantly affects the yield of 44Ti in supernovae were measured in the energy range 5.7 MeV</=E(c.m.)</=9 MeV, using a beam of radioactive 44Ti. The cross sections and the deduced astrophysical reaction rates are larger than the results from theoretical calculations by about a factor of 2. The implications of this increase in the reaction rate for the search of supernovae using space-based gamma detectors are discussed.

Journal Article↗

PubMed2000

[The dopamine hypothesis of schizophrenia. New findings for an old theory].

The dopamine hypothesis of schizophrenia was based on the neuroleptical blockade of central dopamine D2 receptors. Brain imaging studies, however, generally failed to demonstrate a significant increase in central D2 receptors among schizophrenic patients. Using a novel approach, the group of Laruelle and Abi-Dargham was now able to demonstrate that schizophrenic patients have increased synaptic dopamine concentrations in the striatum. Endogenous dopamine competes with a radioligand for binding at dopamine D2 receptors; compared to healthy control subjects, blockade of dopamine production in neuroleptic-naive schizophrenic patients induced a significantly higher increase in D2 binding of the infused radioligand, indicating higher endogenous synaptic dopamine. A similar increase in D2 binding was also observed in drug-free schizophrenics who had previously been treated with neuroleptics; these patients also showed an increased density of striatal D2 receptors, most likely due to counteradaptive upregulation of D2 receptors during neuroleptic medication. The Columbia study provides an important indication of hyperdopaminergic function in schizophrenia.

Corpus Striatum↗

PubMed2000

Standardized stimuli to assess drug craving and drug memory in addicts.

Due to conditioning processes, originally neutral stimuli become drug-associated cues and can initiate drug craving. Standardized stimuli are required to assess stimulus-induced activation of drug memory and craving in brain imaging and neurophysiology studies. We developed substance-specific visual and olfactory stimuli for alcohol, tobacco, opiate and cannabis abuse and tested them in subjects with the respective addiction and in healthy volunteers. Stimulus-related drug craving differed significantly between the diagnostic groups and indicated that the stimuli are suitable for craving studies.

Adult↗