Time-Dependent Magnons from First Principles.

We propose an efficient and non-perturbative scheme to compute magnetic excitations for extended systems employing the framework of time-dependent density functional theory. Within our approach, we drive the system out of equilibrium using an ultrashort magnetic kick perpendicular to the ground-state magnetization of the material. The dynamical properties of the system are obtained by propagating the time-dependent Kohn-Sham equations in real time, and the analysis of the time-dependent magnetization reveals the transverse magnetic excitation spectrum of the magnet. We illustrate the performance of the method by computing the magnetization dynamics, obtained from a real-time propagation, for iron, cobalt, and nickel and compare them to known results obtained using the linear-response formulation of time-dependent density functional theory. Moreover, we point out that our time-dependent approach is not limited to the linear-response regime, and we present the first results for nonlinear magnetic excitations from first principles in iron.

Kinetic-Energy Density-Functional Theory on a Lattice.

We present a kinetic-energy density-functional theory and the corresponding kinetic-energy Kohn-Sham (keKS) scheme on a lattice and show that, by including more observables explicitly in a density-functional approach, already simple approximation strategies lead to very accurate results. Here, we promote the kinetic-energy density to a fundamental variable alongside the density and show for specific cases (analytically and numerically) that there is a one-to-one correspondence between the external pair of on-site potential and site-dependent hopping and the internal pair of density and kinetic-energy density. On the basis of this mapping, we establish two unknown effective fields, the mean-field exchange-correlation potential and the mean-field exchange-correlation hopping, which force the keKS system to generate the same kinetic-energy density and density as the fully interacting one. We show, by a decomposition based on the equations of motions for the density and the kinetic-energy density, that we can construct simple orbital-dependent functionals that outperform the corresponding exact-exchange Kohn-Sham (KS) approximation of standard density-functional theory. We do so by considering the exact KS and keKS systems and comparing the unknown correlation contributions as well as by comparing self-consistent calculations based on the mean-field exchange (for the effective potential) and a uniform (for the effective hopping) approximation for the keKS and the exact-exchange approximation for the KS system, respectively.

Transient Charge and Energy Flow in the Wide-Band Limit.

The wide-band limit is a commonly used approximation to analyze transport through nanoscale devices. In this work we investigate its applicability to the study of charge and heat transport through molecular break junctions exposed to voltage biases and temperature gradients. We find by comparative simulations that while the wide-band-limit approximation faithfully describes the long-time charge and heat transport, it fails to characterize the short-time behavior of the junction. In particular, we show that the charge current flowing through the device shows a discontinuity when a temperature gradient is applied, while the energy flow is discontinuous when a voltage bias is switched on and even diverges when the junction is exposed to both a temperature gradient and a voltage bias. We provide an explanation for this pathological behavior and propose two possible solutions to this problem.

Functional theories of thermoelectric phenomena.

We review the progress that has been recently made in the application of time-dependent density functional theory to thermoelectric phenomena. As the field is very young, we emphasize open problems and fundamental issues. We begin by introducing the formal structure of thermal density functional theory, a density functional theory with two basic variables-the density and the energy density-and two conjugate fields-the ordinary scalar potential and Luttinger's thermomechanical potential. The static version of this theory is contrasted with the familiar finite-temperature density functional theory, in which only the density is a variable. We then proceed to constructing the full time-dependent non equilibrium theory, including the practically important Kohn-Sham equations that go with it. The theory is shown to recover standard results of the Landauer theory for thermal transport in the steady state, while showing greater flexibility by allowing a description of fast thermal response, temperature oscillations and related phenomena. Several results are presented here for the first time, i.e. the proof of invertibility of the thermal response function in the linear regime, the full expression of the thermal currents in the presence of Luttinger's thermomechanical potential, an explicit prescription for the evaluation of the Kohn-Sham potentials in the adiabatic local density approximation, a detailed discussion of the leading dissipative corrections to the adiabatic local density approximation and the thermal corrections to the resistivity that follow from it.

The adiabatic limit of the exact factorization of the electron-nuclear wave function.

We propose a procedure to analyze the relation between the exact factorization of the electron-nuclear wave function and the Born-Oppenheimer approximation. We define the adiabatic limit as the limit of infinite nuclear mass. To this end, we introduce a unit system that singles out the dependence on the electron-nuclear mass ratio of each term appearing in the equations of the exact factorization. We observe how non-adiabatic effects induced by the coupling to the nuclear motion affect electronic properties and we analyze the leading term, connecting it to the classical nuclear momentum. Its dependence on the mass ratio is tested numerically on a model of proton-coupled electron transfer in different non-adiabatic regimes.

Derivative discontinuity and exchange-correlation potential of meta-GGAs in density-functional theory.

We investigate fundamental properties of meta-generalized-gradient approximations (meta-GGAs) to the exchange-correlation energy functional, which have an implicit density dependence via the Kohn-Sham kinetic-energy density. To this purpose, we construct the most simple meta-GGA by expressing the local exchange-correlation energy per particle as a function of a fictitious density, which is obtained by inverting the Thomas-Fermi kinetic-energy functional. This simple functional considerably improves the total energy of atoms as compared to the standard local density approximation. The corresponding exchange-correlation potentials are then determined exactly through a solution of the optimized effective potential equation. These potentials support an additional bound state and exhibit a derivative discontinuity at integer particle numbers. We further demonstrate that through the kinetic-energy density any meta-GGA incorporates a derivative discontinuity. However, we also find that for commonly used meta-GGAs the discontinuity is largely underestimated and in some cases even negative.

Density-functional theory of thermoelectric phenomena.

We introduce a nonequilibrium density-functional theory of local temperature and associated local energy density that is suited for the study of thermoelectric phenomena. The theory rests on a local temperature field coupled to the energy-density operator. We identify the excess-energy density, in addition to the particle density, as the basic variable, which is reproduced by an effective noninteracting Kohn-Sham system. A novel Kohn-Sham equation emerges featuring a time-dependent and spatially varying mass which represents local temperature variations. The adiabatic contribution to the Kohn-Sham potentials is related to the entropy viewed as a functional of the particle and energy density. Dissipation can be taken into account by employing linear response theory and the thermoelectric transport coefficients of the electron gas.

Transverse spin-gradient functional for noncollinear spin-density-functional theory.

We present a novel functional for spin-density-functional theory aiming at the description of noncollinear magnetic structures. The construction of the functional employs the spin-spiral-wave state of the uniform electron gas as reference system. We show that the functional depends on transverse gradients of the spin magnetization; i.e., in contrast with the widely used local spin density approximation, the functional is sensitive to local changes of the direction of the spin magnetization. As a consequence the exchange-correlation magnetic field is not parallel to the spin magnetization and a local spin torque is present in the ground state of the Kohn-Sham system. As a proof of principle, we apply the functional to a Chromium monolayer in the noncollinear 120°-Néel state.

Enhanced vulnerability of PARK6 patient skin fibroblasts to apoptosis induced by proteasomal stress.

Proteasomal dysfunction and apoptosis are major hallmarks in the pathophysiology of Parkinson's disease (PD). PARK6 which is caused by mutations in the mitochondrial protein kinase PINK1 is a rare autosomal-recessively inherited disorder mimicking the clinical picture of PD. To investigate the cytoprotective physiological function of PINK1, we used primary fibroblasts from three patients homozygous for G309D-PINK1 as well as SHEP neuroblastoma cells stably overexpressing GFP-tagged wild type (wt) PINK1. Here we demonstrate that overexpression of wt PINK1 inhibits activation of Bax and release of cytochrome c, thereby diminishing caspase 9 processing and effector caspase activity after induction of proteasomal stress with the proteasome inhibitor (PI) MG132 in SHEP cells. Conversely, effector caspase activation induced by PIs, but not by the unrelated apoptotic stimulus staurosporine was potently enhanced in primary fibroblasts from homozygous PARK6 patients in comparison to those of heterozygous carriers or unaffected siblings. SHEP cells overexpressing wt PINK1 showed an elevated expression of the cytoprotective gene parkin, whereas PARK6 fibroblasts displayed significantly decreased expression of parkin in comparison to wild type control cells. Interestingly, overexpressed GFP-PINK1 was exclusively localized in the mitochondria of SHEP cells, but was redistributed to the cytoplasm under conditions of proteasomal stress. Our data indicate that PINK1 plays an important and specific physiological role in protecting cells from proteasomal stress, and suggest that PINK1 might exert its cytoprotective effects upstream of mitochondria engagement.

Early- and delayed antipsychotic response and prediction of outcome in 528 severely impaired patients with schizophrenia treated with amisulpride.

INTRODUCTION: 'Early-onset' studies have shown that symptomatic response often occurs early and that early symptomatic response is predictive for later outcome. Limiting factors of these studies include the restriction on symptomatic outcome, the inclusion of mostly moderately ill patients, and the use of various antipsychotics. METHODS: Response and remission rates were assessed in 528 severely ill patients with schizophrenia at baseline, week 2, 4 and 12 using PANSS, SWN-K, CGI-S, and SOFAS. The clinical measures were combined to one outcome criterion (CombOut). Predicitive validity was analyzed for CombOut using linear regression models. RESULTS: Rate and time to response differed markedly between outcome measures. 32% reached positive symptom response at week 2, 58% at week 4 and 85% at week 12. Non-response at week 4, but not at week 2 was predictive for later non-response. The combined outcome criterion was best predicted by early response in subjective wellbeing (T=-7.88, p<0.001) and social functioning (T=-7.43, p<0.001). DISCUSSION: Rate and time to response might depend on sample characteristics and outcome measure. In severely ill patients early antipsychotic response is possibly delayed from the first 2 to the first 4 weeks. Early response in subjective wellbeing and social functioning are strong predictors for overall outcome, which make them a useful supplementation to the assessment of symptomatic response.

Amisulpride doses and plasma levels in different age groups of patients with schizophrenia or schizoaffective disorder.

Because of a unique pharmacodynamic profile, amisulpride seems appropriate for treatment of elderly patients with schizophrenia. In a large-scale naturalistic therapeutic drug monitoring study, daily amisulpride dose, trough and dose-corrected amisulpride plasma levels, co-medication, clinical effectiveness (CGI) and side effects (UKU) were compared between age groups in 395 patients with schizophrenia or schizoaffective disorder (46% women; mean age 39.1 +/- 14.2 years, range 18-83 years) under amisulpride therapy. Mean amisulpride doses (574 +/- 269 mg/day), plasma levels (304 +/- 274 ng/mL), dose-corrected amisulpride plasma levels (C/D ratios, 0.52 +/- 0.41 ng/mL:mg), clinical response (at least moderate improvement, 71.6%), and side effects (any side effect, 32.2%; extrapyramidal symptoms, 14.9%) were comparable between age groups (P > 0.25). At higher age, significantly more benzodiazepines (P = 0.04), non-benzodiazepine hypnotics (P = 0.004) and non-psychotropic medications (P < 0.0001) were prescribed. The naturalistic study showed higher C/D ratios in women (P = 0.019) and a slight increase of C/D ratios with age (P = 0.026), but no substantial age-dependent effects on amisulpride doses or plasma levels. In patients above 60 years, clinical response was associated with lower amisulpride plasma levels (P = 0.016) at comparable doses. Neither the age-dependent decrease of amisulpride clearance nor the significantly higher prevalence of co-morbidity and co-medication seem to be the reasons for definite clinical concerns against amisulpride treatment of elderly if contraindications are seriously taken.

A pilot study of the safety and efficacy of amisulpride and risperidone in elderly psychotic patients.

OBJECTIVE: The primary objective of this randomised, active-controlled, parallel group, double-blind study was to evaluate the tolerability of treatment with either amisulpride or risperidone in elderly patients with schizophrenia aged over 65 years; evaluation of efficacy was a secondary objective. METHODS: The study included patients of either sex aged 65 years or older fulfilling DSM IV-diagnostic criteria for psychotic disorders and who presented psychotic symptoms severe enough to require antipsychotic medication. Subjects were randomly allocated to a flexible dose of either amisulpride (100-400mg/day) or risperidone (1-4 mg/day) for six weeks following a three- to six-day placebo wash-out period. Safety assessment involved adverse event reporting, physical examination, blood pressure, heart rate and ECG monitoring, and laboratory tests. Extrapyramidal symptoms were evaluated with the Simpson-Angus Scale, Barnes Akathisia Scale and the AIMS. Efficacy parameters were changes in score on the PANSS, BPRS, CDS and MMSE scores. RESULTS: Thirty-eight patients were randomised, 25 to amisulpride and 13 to risperidone. A total of 26 adverse events were experienced by 10 patients in the amisulpride group and five patients in the risperidone group. One patient in each group discontinued the study due to the emergence of a movement disorder. Changes in scores on the three measures of extrapyramidal symptoms were similar in the two groups. The PANSS total score decreased by 27.8% in the amisulpride group and by 29% in the risperidone group between inclusion and study end. CONCLUSION: Amisulpride and risperidone are generally well tolerated in elderly patients with schizophrenia. Both drugs appeared to be efficacious in this study population, with no differences in efficacy being observed. However, the sample size was too low to reveal potential inter-group differences. Both these atypical antipsychotics thus appear to be suitable for the treatment of schizophrenia in the elderly.

Remission of severely impaired subjective wellbeing in 727 patients with schizophrenia treated with amisulpride.

UNLABELLED: Studies of subjective wellbeing (SW) in schizophrenia have missed to define and to assess rate and predictors of SW response (SW-res) and SW remission (SW-rem). METHOD: A total of 727 patients with schizophrenia and severely impaired SW at entry (Subjective Wellbeing under Neuroleptics Scale, short version, SWN-K, total score < or =60) were treated with amisulpride over 12 weeks. SW-res was defined as SWN total score increase of at least 20% and by at least 10 points and SW-rem as total score of > or =80 points. RESULTS: Seventy percent fulfilled the SW-res criterion at week 4. At week 4 and week 12 (endpoint), the SW response criterion distinguished between patients with or without later SW remission and overall symptomatic and functional response. While 39% fulfilled the SW-rem criterion at endpoint, only 9.1% without early SW-res were in SW-rem at follow-up. Regression analyses indicated that SW-res was mainly predicted by greater severity of positive symptoms at baseline and SW-rem by lower severity of negative symptoms and better social functioning, and particularly by early SW-res. CONCLUSION: Patients with a risk of SW non-remission need to be identified early with subsequent treatment adaptation according to recommendations for incomplete remission and treatment resistance in schizophrenia.

Gender aspects in the clinical treatment of schizophrenic inpatients with amisulpride: a therapeutic drug monitoring study.

INTRODUCTION: It is assumed that female and male schizophrenic patients respond differentially to acute and chronic treatment with antipsychotics because of pharmacokinetic and pharmacodynamic factors linked to hormonal and constitutional gender differences. However, to date no empirical evidence exists in support of this notion. METHODS: In a naturalistic clinical study, we investigated gender differences in a sample of schizophrenic inpatients with acute exacerbation treated with the atypical antipsychotic amisulpride, a selective dopamine D2/D3 receptor antagonist with proven antipsychotic efficacy. Prescribed amisulpride dose, plasma level, clinical response (CGI), and side effects (UKU) were assessed in 99 patients (62 % male, age 18-66 years) under antipsychotic monotherapy with amisulpride at daily doses > or = 400 mg. RESULTS: Female patients were significantly older (38.5 +/- 11.8 years) than male patients (32.3 +/- 10.9 years; P = 0.01). Prescribed amisulpride doses were comparable for men (673 +/- 216 mg) and women (665 +/- 229 mg). However, dose-corrected steady-state amisulpride plasma levels (men 0.41 +/- 0.31 ng/mL/mg; women 0.60 +/- 0.39 ng/mL/mg; P = 0.007) were significantly higher in female patients even after age adjustment. No significant differences between men and women emerged with respect to clinical response (77 % vs. 79 %, respectively) and the occurrence of any side effect (41 % vs. 37 %, respectively). DISCUSSION: Except for higher dose-related plasma amisulpride levels in women, the explorative study unveiled no clinically relevant gender-specific aspects regarding prescribed dose, effectiveness, and side effects.

Competence to give informed consent to clinical studies. Statement by the taskforce on "ethical and legal questions" of the Association for Neuropsychopharmacology and Pharmacopsychiatry ("Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie [AGNP]").

Over the last 50 years, patient autonomy has become an increasingly important part of the principles of medical ethics, or rather of the ethics of the doctor-patient relationship. While the principle of charity and the associated paternalism became less important, the patient's active consent became more and more relevant (Sass, 1989; Bayer, 1998; Nedopil, 1998). This development was inevitably also accompanied by a demand for more detailed information prior to medical interventions (Appelbaum and Grisso, 1988; Weisstub, 1990; Kreussler, 1997; Ulsenheimer, 1995; Laufs, 1997; Sommer, 1997) and for complete information on medical procedures subsequent to interventions (e. g. Bender, 1997). Determination of a person's competence to give informed consent is a central problem in the assessment of his expression of consent to a medical intervention. The capacity to adequately express consent can be impaired at certain stages of life and during some illnesses. Patients in borderline situations, children, mentally ill patients and old people with dementia may either be limited in their capacity to give informed consent, or be completely unable to do so. This results in special ethical problems when such groups are included in research projects.

Negative symptoms in schizophrenia: considerations for clinical trials. Working group on negative symptoms in schizophrenia.

There is little agreement about the methodology of clinical trials of antipsychotic drugs in patients with negative symptoms. A literature review revealed wide variation in experimental design, rating scales and study duration. This reflects differing views as to the definition and response to treatment of negative symptoms. Some degree of standardization would improve comparability of studies and aid the development of new compounds. Patients included in such studies should have displayed negative symptoms for at least 6 months. Depressive symptoms, positive schizophrenic symptoms and extrapyramidal signs may all influence or be confused with negative symptoms and may respond to treatment; they should be at a low level at baseline and should be measured during the study period. Studies should last at least 8 weeks. Several scales are available for measuring negative symptoms and are reviewed; a global impression score should be used additionally.

Pilot controlled double-blind study of the hypnotic effects of zolpidem in patients with chronic 'learned' insomnia: psychometric and polysomnographic evaluation.

In a pilot double-blind trial in 21 patients with learned or idiopathic insomnia (DSM-IIIR), patients received placebo for 1 week (nights 1-7), either active (zolpidem, 10 mg) or placebo treatment for 2 weeks (nights 8-21) and then placebo for a further week (nights 22-28). Variables to measure efficacy, rebound and withdrawal were assessed daily from day 1 to day 28. Polysomnographic recordings together with sleep cycle analysis were performed on nights 7, 21 and 28. Patients treated with 10 mg zolpidem for 2 weeks had significantly improved sleep efficiency at the end of the randomised double-blind phase compared with the placebo group. Fractionated sleep-cycle analysis showed an increase in slow-wave sleep during the first 2-hour cycle after sleep onset. During the withdrawal placebo week, most of the main sleep variables remained relatively stable in the zolpidem group (nights 22-28), and deteriorated further in the placebo group. At the end of the withdrawal phase, there was a statistically significant difference between groups, in favour of the zolpidem treatment, in sleep efficiency, total sleep time, absolute and percentage of time awake, and percentage of REM sleep. REM sleep, which was normal in both groups at baseline, decreased significantly in the placebo group between nights 22 and 28 (during the withdrawal placebo week) compared with the zolpidem treatment group, and the number of periods of time awake increased. Minor subjective complaints were recorded under zolpidem and were comparable with those under placebo. Zolpidem seemed to improve some important sleep variables, when assessed both objectively and subjectively. The sleep cycle analysis suggested a possible shift of slow-wave sleep to an earlier period of the night, with a more physiological sleep structure. There was no evidence for withdrawal or rebound after stopping the 2 weeks of zolpidem treatment, but rather signs that the effect of zolpidem outlasted active treatment. The present pilot study justifies a prospective confirmatory comparison of zolpidem with benzodiazepines in an adequate number of patients and withdrawal after 6-8 weeks of treatment.

Long-term polysomnographic study of the efficacy and safety of zolpidem in elderly psychiatric in-patients with insomnia.

The effects of 20 mg zolipidem were studied in an open, polysomnographically-monitored 179 day trial in 14 elderly psychiatric patients suffering from severe insomnia. After a placebo run-in of 7 days, zolpidem was given for 179 days followed by a 30-day wash-out period. Polysomnographic recordings (PSG) were performed just before active treatment; 30, 90 and 179 days into the treatment period; and at the end of the wash-out period. Statistically significant improvements in total sleep time, sleep efficiency and percentage of rapid eye movement sleep were observed after 30 days, all of which were maintained at 179 days. Sleep stages 1-4 all changed, with a significant decrease in percentage of stage 1, and a significant increase in both percentages of stage 2 and 3, and duration of stages 3 and 4 at the end of active treatment. After a 90-day follow-up period, only stage 3 sleep and sleep efficiency were no longer significantly changed compared to baseline, all other criteria showing maintenance of efficacy. Slow-wave sleep, which was increased during active treatment, decreased in the follow-up period. No serious adverse events were observed. These results suggest that, contrary to other hypnotics, zolpidem, after long-term administration, improves objective sleep parameters and may normalize a disturbed sleep architecture.