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H Agren

Publications and source records attributed to H Agren.

At least 19 recordsLinked to original sources
PubMed2002

X-ray emission spectroscopy of hydrogen bonding and electronic structure of liquid water.

We use x-ray emission spectroscopy to examine the influence of the intermolecular interaction on the local electronic structure of liquid water. By comparing x-ray emission spectra of the water molecule and liquid water, we find a strong involvement of the a(1)-symmetry valence-orbital in the hydrogen bonding. The local electronic structure of water molecules, where one hydrogen bond is broken at the hydrogen site, is separately determined. Our results provide an illustration of the important potential of x-ray emission spectroscopy for elucidating basic features of liquids.

Journal Article↗
PubMed2002

Interference quenching of nu(")=1 vibrational line in resonant photoemission of N2: a possibility to obtain geometrical information on the core-excited state.

An interference quenching of the nu(")=1 vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N2 is observed and analyzed. The intensity ratio between the nu(")=1 and nu(")=0 vibrational levels of the X2Sigma(+)(g) final state shows a surprising nonmonotonous variation as a function of frequency detuning, going through a minimum with a complete suppression of nu(")=1. We have developed a simple model which shows a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance R(0)(c) of the core-excited state. A new way is thus established of determining the equilibrium bond distance for the core-excited state with a precision deltaR(0)(c)<10(-3) A.

Journal Article↗
PubMed2001

Subjective lack of social support and presence of dependent stressful life events characterize patients suffering from major depression compared with healthy volunteers.

The aim of this study was to characterize and compare patients with major depression and healthy volunteers concerning stressful negative life events, social support and social network occurring during a 12-month period. Forty outpatients who fulfilled DSM-IV criteria for major depression and 19 healthy volunteers were included in the study. The results showed no significant differences between the patients and the volunteers concerning the number of independent life events, perceived sufficient persons in the network, the number of family members, having a partner, and perceiving family members as offering the best support. Thus, there were differences in the number of both dependent stressful life events, especially increased arguments with partner and family members, and life events including personal illness. The patient group had experienced a greater number of these events compared with the volunteer group. Comparisons between the two groups revealed differences concerning social support and social network. Fewer patients, especially women, felt they had sufficient social support, had fewer persons in the network, less contact with persons in the network, and fewer confidants compared with the volunteers.

Adult↗
PubMed2001

Aggression in the general Swedish population, measured with a new self-rating inventory: The Aggression Questionnaire--revised Swedish version (AQ-RSV).

The aim of the present study was to develop a Swedish self-rating instrument for clinical aggression research based on the American Aggression Questionnaire (AQ), which measures physical aggression, verbal aggression, anger, and hostility. To test this adapted Aggression Questionnaire--revised Swedish version (AQ-RSV), it was mailed to 781 randomly selected individuals, aged 20-40 year. A total of 497 (64%) evaluable AQ-RSV inventories were obtained and analyzed statistically. Drop-out analysis showed that non-responders were most often male and significantly older than responders. Among the responders, AQ-RSV showed significant sex differences in all aggression subscales except Hostility. Aggression was found to vary with age, geographical region, and size of home community. The AQ and the AQ-RSV were comparable in correlations between the four aggression subscales and in alpha coefficients, which indicated considerable internal consistency. Development of the aggression-measuring instrument for Swedish conditions is important not only to study subtraits of aggression but to enable analyses of their relationships to neurobiological and psychiatric variables.

Adolescent↗
PubMed2001

Tau and Abeta42 in cerebrospinal fluid from healthy adults 21-93 years of age: establishment of reference values.

BACKGROUND: Tau protein and the 42-amino acid form of beta-amyloid (Abeta42) measured in cerebrospinal fluid (CSF) have been proposed as potential biochemical diagnostic markers for Alzheimer disease. For the introduction of these assays in clinical practice, adequate reference values are of importance. METHODS: CSF samples were obtained from 231 neurologically and psychiatrically healthy individuals, 21-93 years of age, all with a MiniMental State examination score of 28 or above. Standardized ELISAs were used to measure tau and Abeta42 in CSF. Following IFCC recommendations, we used a rank-based method; the 0.90 and 0.10 fractiles were estimated to establish reference values for CSF-tau and CSF-Abeta42, respectively. Putative confounding factors, such as the influence of the passage of proteins from peripheral blood to CSF, influence of dysfunction of the blood-brain barrier, and freezing and thawing of CSF, were investigated. RESULTS: A correlation with age was found for CSF-tau (r = 0.60; P <0.001). Therefore, separate reference values for different age groups were established for CSF-tau: <300 ng/L in the group 21-50 years of age, <450 ng/L in the group 51-70 years of age, and <500 ng/L in the group 71-93 years of age. CSF-Abeta42 did not correlate with age (r = -0.045), and the reference value was set to >500 ng/L. No correlation was found between blood-brain barrier function and CSF-tau or CSF-Abeta42. CONCLUSIONS: These reference values can be applied when using CSF-tau and CSF-Abeta42 in clinical practice.

Adult↗
PubMed2000

No evident neuronal damage after electroconvulsive therapy.

Electroconvulsive therapy (ECT) is regarded as one of the most effective treatments for major depressive disorder but has also been associated with cognitive deficits possibly reflecting brain damage. The aim of this study was therefore to evaluate whether ECT induces cerebral damage as reflected by different biochemical measures. The concentrations in the cerebrospinal fluid (CSF) of three established markers of neuronal/glial degeneration, tau protein (tau), neurofilament (NFL) and S-100 beta protein, were determined in nine patients who fulfilled DSM-IV criteria for major depression. CSF samples were collected before and after a course of six ECT sessions. The CSF/serum (S) albumin ratio reflecting potential blood-brain barrier (BBB) dysfunction was also determined at these time points. The treatment was clinically successful with a significant decline of depressive symptoms in all patients as assessed by the Montgomery-Asberg Rating Scale for Depression. Several patients had signs of BBB dysfunction and/or neuronal damage before the start of treatment. Levels of CSF-tau, CSF-NFL and CSF-S-100 beta levels were not significantly changed by ECT. Also the CSF/S albumin ratio was found to be unchanged after the course of ECT. In conclusion, no biochemical evidence of neuronal/glial damage or BBB dysfunction could be demonstrated following a therapeutic course of ECT.

Adult↗
PubMed2000

Observation of a continuum-continuum interference hole in ultrafast dissociating core-excited molecules.

The femtosecond dissociation of HCl after core excitation has been studied through the resonant Auger decay. The spectra contain contributions from decay occurring at both "molecular" and "atomic" internuclear distances. We have observed a new interference mechanism in these spectra: An atomic spectral line develops into a negative spectral contribution, a "hole," when detuning the excitation energy from the maximum of the Cl2p(-1)sigma(*) resonance. Resonant x-ray scattering theory quantitatively explains this behavior as due to a novel destructive continuum-continuum interference between molecular and atomic contributions to the Auger decay.

Journal Article↗
PubMed2000

Doppler splitting of In-flight auger decay of dissociating oxygen molecules: the localization of delocalized core holes

By exploiting the core-excitation-induced dissociation of O2, we find that the Auger emission exhibits a Doppler-like energy shift. We show this to be a manifestation of localization of the core hole and propose that the problem of core-hole localization versus delocalization in core-hole spectroscopies may be resolved by considering the nature of the measurement.

Journal Article↗
PubMed2000

[When disease insight is halting. II. The neurobiological underpinnings].

This review examines the neurobiological underpinnings of impaired insight and awareness in psychosis. Crucial mainly dopaminergic pathways are discussed in relation to delusions and hallucinations. Thirty percent of psychotic patients with impaired insight will not respond to traditional neuroleptic drug treatment, and the possibility that multifocal brain etiology might underlie such cases is discussed. It is suggested that severe cases of thought process disorder in psychosis may result from such multifocal processes.

Adaptation, Psychological↗
PubMed2000

Reduced brain norepinephrine and dopamine release in treatment-refractory depressive illness: evidence in support of the catecholamine hypothesis of mood disorders.

BACKGROUND: The etiology of depressive illness has been linked with brain monoaminergic neuronal dysfunction, yet the development of sensitive markers of endogenous depression has proven difficult. METHODS: Using catheters placed in an internal jugular vein, we estimated the release of brain monoamine neurotransmitters in 19 healthy volunteers and in 9 patients with nonbipolar depressive illness refractory to medication at rest and following intravenous desipramine hydrochloride. Venoarterial plasma concentration gradients were used to quantify the amount of neurotransmitters stemming from the brain. Cerebral oxidative metabolism was assessed concurrently from measurements of oxygen and carbon dioxide gas exchange via the process of regional indirect calorimetry. RESULTS: The brains of these patients exhibited reduced venoarterial norepinephrine (4.0 +/- 2.7 nmol/L vs 0.7 +/- 1.3 nmol/L) and homovanillic acid concentration gradients (8.3 +/- 7.8 nmol/L vs 3.1 +/- 1.9 nmol/L), and used an energy source other than glucose. Internal jugular 5-hydroxyindoleacetic acid concentration gradients were not reduced in the patients with depressive illness. While both the reduction in norepinephrine turnover and the defect in cerebral metabolism were normalized following pharmacological blockade of the norepinephrine transporter with desipramine, paradoxically it was the brain's turnover of dopamine that bore a significant relation to the patients' clinical status (r(s) = 0.79, P =.02). The positive nature of this relationship remains difficult to reconcile. CONCLUSIONS: In accordance with the monoamine hypothesis, a deficit in brain norepinephrine and dopamine exists in patients with depressive illness. Moreover, the brains of these patients use an energy source other than glucose, a situation that is normalized following the acute pharmacological blockade of the norepinephrine transporter with the tricyclic antidepressant, desipramine.

Adult↗
PubMed2000

Sertraline versus paroxetine in major depression: clinical outcome after six months of continuous therapy.

reuptake inhibitors (SSRIs) during continuation therapy. This investigation reports the differential effect of 6 months of treatment with sertraline versus paroxetine for symptoms of depression, quality of life, and personality outcomes. Outpatients with unipolar major depression (DSM-III-R) were randomly assigned to receive 24 weeks of double-blind treatment with flexible doses of paroxetine (20-40 mg) or sertraline (50-150 mg). Assessments included the Montgomery-Asberg Depression Rating Scale (MADRS), the Clinical Global Impression Scale, the Battelle Quality of Life Questionnaire, and the Structured Clinical Interview for DSM-III-R Personality Disorders screen questionnaire. One hundred seventy-six patients (mean age, 43 years; 64% female; baseline MADRS, 30.3) were treated with sertraline and 177 patients (mean age, 42 years; 71% female; MADRS, 30.7) with paroxetine. Antidepressant efficacy during continuation therapy was sustained, with only 2% of patients receiving sertraline and 9% of patients receiving paroxetine suffering a relapse. Continuation therapy resulted in a substantial conversion of responders during short-term treatment to full remission: remitter rates increased from 52% to 80% for sertraline and from 57% to 74% for paroxetine. The improvements in quality of life were related to a reduced depression score. SSRI treatment had significant beneficial effects on both categorical and dimensional measures of personality. A logistic regression analysis identified early response (25% reduction in MADRS scores at week 2) as the most important predictor of treatment response, whereas high severity, chronicity, and poor baseline quality of life had no effect. Both treatments were well-tolerated, with sertraline having a somewhat lower side effect profile. Sertraline and paroxetine demonstrated comparable efficacy during short-term and continuation therapy. Treatment was associated with significant improvement in quality of life and with reductions in axis II personality psychopathology.

Adolescent↗
PubMed1999

The influence of prolactin response to d-fenfluramine on executive functioning in major depression.

BACKGROUND: The main purpose of this study was to assess the influence of serotonergic activity, as measured by prolactin response to d-fenfluramine, on executive functioning in major depression. METHODS: Forty-one persons between 22 and 71 years of age who met the DSM-IV criteria for major depressive episode were administered the Wisconsin Card Sorting Test (WCST) in computerized format, and d-fenfluramine was administered orally. Postfenfluramine blood samples for ascertaining plasma prolactin levels were obtained. RESULTS: The key finding was that prolactin response was positively related to four out of five selected WCST variables. Also, increasing age was associated with decreasing WCST performance. There was no interaction between prolactin response and age, indicating that the effects of prolactin response on the WCST generalized across the age range examined. CONCLUSIONS: The overall pattern of results suggests that there may be a relationship between serotonergic activity and executive functioning in major depression.

Adult↗
PubMed1999

[Non-profit networks for suicide prevention].

Survival groups and suicide clusters constitute new challenges for suicide prevention. Emergency ward and intensive care personnel and psychologists working in close co-operation with general practitioners are strategically important in such preventive endeavours. Scientists and health care personnel need to develop joint strategies for the purpose. Politicians and administrators are important target groups for information on suicide prevention. The foregoing are important findings in the first year's experience of the West Swedish Network for Suicide Prevention.

Crisis Intervention↗