Experimental and numerical analysis of Tm2+excited-states dynamics and luminescence in CaX2(X= Cl, Br, I).

The prospect of using Tm2+-doped halides for luminescence solar concentrators (LSCs) requires a thorough understanding of the temperature dependent Tm2+excited states dynamics that determines the internal quantum efficiency (QE) and thereby the efficiency of the LSC. In this study we investigated the dynamics in CaX2:Tm2+(X= Cl, Br, I) by temperature- and time-resolved measurements. At 20 K up to four distinct Tm2+emissions can be observed. Most of these emissions undergo quenching via multi-phonon relaxation below 100 K. At higher temperatures, only the lowest energy 5d-4f emission and the 4f-4f emission remain. Fitting a numerical rate equation model to the data shows that the subsequent quenching of the 5d-4f emission is likely to occur initially via multi-phonon relaxation, whereas at higher temperatures additional quenching via interband crossing becomes thermally activated. At room temperature only the 4f-4f emission remains and the related QE becomes close to 30%. Possible reasons for the quantum efficiency not reaching 100% are provided.

The safety and tolerability of candesartan cilexetil in CHF.

The management of congestive heart failure (CHF) continues to represent a major therapeutic challenge. The primary goal of any treatment is the improvement of symptoms with a reduction in CHF related morbidity and a neutral or beneficial effect on mortality. The number of hospitalisations is considered an important measure of morbidity and quality-of-life in these patients. This pooled safety analysis was performed on adverse event data from five placebo-controlled studies involving a total of 1893 patients, 1287 of whom received candesartan cilexetil and 606 of whom received placebo. These were the only placebo-controlled phase II and III studies of candesartan safety available at the time of the analysis, and investigated the efficacy and safety of candesartan cilexetil in patients with CHF. None was designed as an endpoint trial. A blinded, independent review of all adverse event data was performed to assess all-cause mortality and unexpected deaths, and hospitalisations for acute deterioration of CHF, chronic progression of CHF, other intercurrent events, or accidental injury/attempted suicide. The descriptive analysis included crude and cumulative incidence rates for mortality and cardiac and non-cardiac morbidity using the Kaplan-Meier method and the log-rank test. The sample population was predominantly (approximately two thirds) male, with a median age of 61 years (range: 20-89 years). The median age for women in the sample population was 66 years (range: 26-86 years). Patients received candesartan cilexetil, 2-32 mg, over a median period of 84 days (range: 1-418 days), or placebo over a median period of 85 days (range: 1-398 days). The results demonstrated a clinically non-significant trend for all relevant events (deaths and hospitalisations, whether related to CHF or not) to occur less frequently in patients receiving candesartan cilexetil than in patients receiving placebo (deaths - candesartan cilexetil: 1.6%, placebo: 1.8%; hospitalisations - candesartan cilexetil: 7.2%, placebo: 10.9%). There was a significant treatment difference in CHF hospitalisations (candesartan cilexetil: 3.0% vs. placebo: 5.6%). The time to event analysis revealed that significantly fewer hospitalisations due to CHF occurred in the group receiving candesartan cilexetil than in the group receiving placebo. This treatment difference persisted throughout therapy (log-rank test; p < 0.028). These results show the safety of candesartan cilexetil, compared with placebo, in the treatment of patients with CHF.

Lisuride treatment of Alzheimer's disease. A preliminary placebo-controlled clinical trial of safety and therapeutic efficacy.

In this article, the authors examine the effect of lisuride on 22 patients with probable Alzheimer's disease (NINCDS/ADRDA criteria) in a randomized double-blind, placebo-controlled, parallel group design. Ten patients received lisuride and 12 patients received placebo. Lisuride was administered in a dose-finding phase of four weeks and an efficacy phase of eight weeks, with a maximum dose of 0.3 mg daily. Outcome measures included global clinical impression, general cognitive function, mood, verbal and visual memory, attention, and psychomotor function. Average decline in Mini-Mental State Examination score after 12 weeks treatment was less often statistically significant in lisuride treated patients than in patients receiving a placebo (p < 0.05). Patients treated with lisuride improved their average total score and short-delay cued recall score on the California Verbal Learning Test, a test of verbal memory, whereas placebo-treated patients showed worse performance compared with baseline. These differences approached statistical significance, with p = 0.06 and p = 0.05, respectively. No other differences between the treatment groups were evident. The authors failed to find a consistent effect of lisuride on symptoms of Alzheimer's disease. However, this study's sample size was relatively small, and larger studies are needed to ascertain the treatment effects of serotonergic antagonists on Alzheimer's disease.

The effects of a benzodiazepine receptor antagonist beta-carboline ZK-93426 on scopolamine-induced impairment on attention, memory and psychomotor skills.

The effects of a single dose of scopolamine alone and in combination with ZK 93426 (a beta-carboline antagonist at the GABAA/BZ receptor complex with weak inverse agonist activity) were tested in two studies. In one study (study 1) the emphasis of enquiry was on different stages of information processing measured by a psychometric battery; in the second study (study 2) performance at different stages of memory and psychomotor abilities was tested and electroencephalogram recordings and video-tracking were also performed. Each study consisted of two parts, part I in which scopolamine (0.5 mg; 1 ml) or placebo were administered subcutaneously, and part II in which scopolamine (0.5 mg; 1 ml) was administered subcutaneously followed by an intravenous injection of ZK 93426 (0.04 mg; 0.04 ml/kg) or placebo. Thirty-six volunteers, who were randomly allocated to receive one of the two treatments (n = 18 per treatment), participated in each part. In study 1 attention was measured by a continuous attention task and a rapid information processing task, vigilance was measured by a visual vigilance task, and working memory and reasoning were evaluated by a logical reasoning task. A visual memory task was also included to measure acquisition and retention. In study 2 acquisition and short term storage and retrieval were measured by a word lists-Buschke restricted reminding procedure, and retention was tested by delayed recall and recognition. Psychomotor performance was assessed by measuring tapping speed (related to gross motoric abilities) and a pegboard task (related to fine motoric abilities). A task to measure working memory, the Pauli test, was also included. In study 1 scopolamine significantly impaired performance in the attentional and vigilance tasks (P < 0.05), but there was no effect in the logical reasoning task main measurements of time and accuracy. In study 2, scopolamine also impaired performance in the psychomotor tasks (P < 0.05) and the Pauli test. ZK 93426 partially antagonised most of the effects of scopolamine on memory and attention, suggesting that an interaction between the GABA-ergic and cholinergic systems is reflected in measurements of both attention and memory. In general a dissociation was found in the effects of scopolamine on memory, i.e. scopolamine impaired performance during all acquisition measurements but left retention unaffected.

Scopolamine and lorazepam exert different patterns of effects in a test battery assessing stages of information processing.

The effects of a single dose of scopolamine (0.5 mg) SC and of lorazepam (2.5 mg) PO were tested in two independent studies for their effects on performance in a psychometric battery which measured functions related to different stages of information processing. Attention and vigilance were measured by a continuous attention task and a vigilance task, respectively. Working memory and reasoning were evaluated by the rapid information processing and logical reasoning task; memory acquisition and storage were measured by pre- and post-drug immediate and delayed recall using visual material. The following pattern of effects was revealed; both scopolamine and lorazepam impaired performance in attentional and vigilance tasks as well as in the rapid information processing task significantly (P < 0.05) when compared with their own placebo; in the logical reasoning task lorazepam significantly prolonged the time required to solve a problem; scopolamine did not have any effect on this task. Scopolamine impaired performance in the immediate recall but left delayed recall unaffected; lorazepam impaired only delayed recall, immediate recall remaining unaffected. These data suggest that scopolamine at this dose impaired mostly attention and early stages of information processes; lorazepam at the dose tested impaired also the later acquisition and encoding aspects of memory.

Differential effects of anxiolytic and non-anxiolytic benzodiazepine receptor ligands on performance of a differential reinforcement of low rate (DRL) schedule.

The effects of several drugs acting at central benzodiazepine receptors on performance of a differential reinforcement of low rate (DRL) 15s schedule of reinforcement for food reward were studied in rats. The non-selective full agonists diazepam (0.1, 1.25, 5 and 10mg/kg) and lorazepam (0.1, 0.25, 0.375 and 0.5mg/kg) increased total numbers of responses and decreased the numbers of reinforcements received, increased burst responding (responding within 3s of a previous response), and produced a shift in the interresponse time (IRT) distribution of responses towards shorter intervals. The beta-carboline anxiolytic abecarnil (0.039, 0.156, 0.313 and 0.625mg/kg) was more potent than the two benzodiazepines, but otherwise gave rise to similar changes in performance. Bretazenil (0.1, 1.0, 10 and 30mg/kg), a non-selective partial agonist, and CL 218872 (3, 10, and 30mg/kg), a partial agonist showing preference for the BZ1 receptor subtype, also increased response rates and decreased numbers of reinforcements, but failed to increase significantly burst responding, and had only weak effects in shifting the IRT distribution. Alpidem (1, 3, 10, 30 and 100mg/kg) and zolpidem (0.33, 1, 3 and 10mg/kg), two imidazopyridines showing BZ1 preference, but classified respectively as an anxiolytic and a selective hypnotic agent, non-significantly reduced response rates and significantly reduced the numbers of reinforcements, but did not influence burst responding, and had effects on IRT distribution only at single doses. Thus, in general, the effects of these compounds on DRL performance reflect their activity in conflict models. The differential effects on DRL performance of the benzodiazepine receptor ligands tested may be attributable to their abilities to interact selectively as agonists or partial agonists at different benzodiazepine receptor subtypes.

Terguride in fluctuating parkinsonian patients: a double-blind study versus placebo.

Terguride (TER), a semisynthetic derivative of lisuride, has been found to display dopamine (DA) agonist and DA antagonist effects in animals, depending on the experimental model used. TER (2 mg/day) was compared to placebo in 41 fluctuating Parkinson's disease patients to test its effect on akinesia and dyskinesia. Mean hours "off" decreased at weeks 6 and 12 (p < 0.05) in the TER group but the overall difference from the placebo group was not significant. Only the TER group displayed a decrease over time in mean Columbia University Rating Scale total score "on" and "off" (p = 0.001 and p = 0.03, respectively). Duration of involuntary movements and resulting disability were not significantly different between patients on TER and those on placebo administration. In the overall evaluation, patients preferred TER (p = 0.01). Tolerance of TER was very good in all but one patient whose wearing-off increased; no one dropped out because of side effects. This 3-month double-blind study showed that TER, added to stable doses of L-dopa, may have slight antiparkinsonian efficacy.

The pharmacokinetics and pharmacodynamics of lisuride in healthy volunteers after intravenous, intramuscular, and subcutaneous injection.

The plasma concentration of lisuride and prolactin have been measured in twelve healthy male volunteers after IV, IM or SC injection of 25 micrograms lisuride hydrogen maleate as an aqueous solution. After IV administration the plasma lisuride fell in two phases with half-lives of 14 min and 1.5 h. Total clearance was 13 ml.min-1.kg-1. After IM and SC injection the plasma concentrations peaked at 12 to 15 min and the profiles were similar to that found after IV administration. The systemic availabilities were 90% and 94%, respectively. Prolactin concentrations were reduced by a maximum of 60% relative to the normal circadian rhythm after all three routes of administration. The treatments were well tolerated, the only adverse reactions reported by some of the volunteers being mild, transient dizziness, tiredness, and nausea.