[Remission criteria in schizophrenia]

BACKGROUND

Recent research shows that there is a considerable variation in the incidence and course of schizophrenia. The illness therefore can best be defined in terms of changeability and plasticity.

AIM

An internationally accepted standard definition of symptomatic remission.

METHOD

Two international panels of experts have wrestled with the problem of whether or how symptomatic remission in persons diagnosed with schizophrenia can be defined. A draft definition was published recently.

RESULTS

The proposed definition is conceptually viable and can be incorporated easily into both clinical practice and clinical research. Acceptance of the remission concept can raise expectations about treatment outcome to a higher level than is possible when a patient is merely defined as being 'stable', can improve the quality of treatment documentation and facilitate the dialogue concerning treatment expectations. The availability of validated outcome measures based on remission should enhance the reporting and the comparability of clinical research and should facilitate the design and interpretation of new research into the relation between symptomatic remission and functional outcomes.

CONCLUSION

The introduction of standard remission criteria can create many opportunities for clinical practice, clinical research and cumulative records of results; at the same time it can facilitate a dialogue with patients and help to clarify the diagnosis of schizophrenia.

Double-blind, placebo-controlled trial of selegiline transdermal system (STS) for the treatment of cocaine dependence

Cocaine dependence is a major public health problem for which there is no FDA-approved pharmacological treatment. Selegiline is an irreversible selective inhibitor of monoamine oxidase type B (MAO-B) which may affect cocaine addiction through several potential mechanisms. In this study, selegiline transdermal system (STS) was compared to placebo as a treatment for cocaine dependence. This multi-site, double-blind trial of 300 subjects with cocaine dependence assessed the efficacy of selegiline using subject self-reported cocaine use substantiated by urine benzoylecgonine (BE) as the primary outcome measure. Analysis of the data did not show a significant effect for selegiline over placebo. This study does not support a role for selegiline in treating cocaine dependence. The contrast of this result to earlier, promising preclinical and human pilot data could be due to factors associated with sample size, patient characteristics, dose, or poor predictive validity of preclinical models.

Bupropion reduces methamphetamine-induced subjective effects and cue-induced craving

Bupropion is an antidepressant with stimulant properties, which inhibits the reuptake of dopamine (DA) and norepinepherine, and is purported to enhance DA neurotransmission. Bupropion is considered an appealing candidate medication for the treatment of methamphetamine dependence. The current laboratory study was set forth to assess the impact of bupropion treatment on the subjective effects produced by methamphetamine in the laboratory. We also assessed the effects of bupropion treatment on craving elicited by exposure to videotaped methamphetamine cues. A total of 26 participants were enrolled and 20 completed the entire study (n=10 placebo and n=10 bupropion, parallel groups design). Bupropion treatment was associated with reduced ratings of 'any drug effect' (p<0.02), and 'high' (p<0.02) following methamphetamine administration. There was also a significant bupropion-by-cue exposure interaction on General Craving Scale total score (p<0.002), and on the Behavioral Intention subscale (p<0.001). Overall, the data reveal that bupropion reduced acute methamphetamine-induced subjective effects and reduced cue-induced craving. Importantly, these data provide a rationale for the evaluation of bupropion in the treatment of methamphetamine dependence.

Intravenous Cocaine and QT Variability

BACKGROUND

Dynamic instability in cardiac repolarization may contribute to drug-induced arrhythmogenesis. We hypothesized that intravenous cocaine would significantly destabilize repolarization as measured by QT variability.

METHODS AND RESULTS

Twenty-nine cocaine-experienced volunteers not seeking treatment for cocaine addiction received randomized, sequential intravenous infusions of placebo or cocaine (20 and 40 mg). Five-minute epochs of digitized ECG were recorded 10 minutes before, during, and at intervals following the infusions. QT variability was measured using a semiautomated method and expressed as the log ratio of normalized QT variance to normalized heart rate variance (QTVI). Seventeen subjects received a repeat course of cocaine infusions 1 week later. Placebo infusion resulted in a small but significant increase in QTVI, while cocaine caused a highly significant, dose-dependent increase in QTVI that peaked at 10 minutes and dissipated by 45 minutes following infusion (P < 0.0001). The increase in QTVI was reproducible at 1 week (P = 0.8).

CONCLUSIONS

Cocaine injection results in a significant dose-dependent increase in QT variability as indexed by QTVI. This destabilizing effect on repolarization may increase vulnerability to reentrant arrhythmias and may partially explain an increased risk of sudden cardiac death associated with cocaine use.

Safety of intravenous methamphetamine administration during treatment with bupropion

RATIONALE

Methamphetamine dependence is a growing problem for which no medication treatments have proven effective.

OBJECTIVES

We evaluated bupropion, an antidepressant with beneficial effects for the treatment of nicotine dependence, in patients with methamphetamine dependence, to assess the safety and tolerability of methamphetamine administration during bupropion treatment.

METHODS

Twenty-six participants entered the study and 20 completed the protocol. Participants received intravenous methamphetamine (0, 15, and 30 mg) before and after randomization to twice-daily bupropion (150 mg SR) or matched placebo. Dependent measures included cardiovascular effects of methamphetamine, methamphetamine and amphetamine pharmacokinetics, and peak and trough plasma concentrations of bupropion and its metabolites.

RESULTS

Bupropion treatment was well tolerated, with bupropion- and placebo-treated groups reporting similar rates of adverse events. Methamphetamine administration was associated with expected stimulant cardiovascular effects, and these were not accentuated by bupropion treatment. Instead, there was a trend for bupropion to reduce methamphetamine-associated increases in blood pressure and a statistically significant reduction in methamphetamine-associated increases in heart rate. Pharmacokinetic analysis revealed that bupropion treatment reduced the plasma clearance of methamphetamine and also reduced the appearance of amphetamine in the plasma. Methamphetamine administration did not alter the peak and trough plasma concentrations of bupropion or its metabolites.

CONCLUSIONS

Methamphetamine administration was well tolerated during bupropion treatment. There was no evidence of additive cardiovascular effects when the drugs were coadministered. This study provides initial evidence for the safety of prescribing bupropion for the treatment of methamphetamine abuse and dependence. The impact of bupropion treatment in patients who abuse larger doses of methamphetamine remains undetermined.

The metabolic syndrome: time for a critical appraisal. Joint statement from the American Diabetes Association and the European Association for the Study of Diabetes

BACKGROUND

The term 'metabolic syndrome' refers to a clustering of specific cardiovascular disease (CVD) risk factors whose underlying pathophysiology is thought to be related to insulin resistance.

METHODS

Since the term is widely used in research and clinical practice, we undertook an extensive review of the literature in relation to the syndrome's definition, underlying pathogenesis, association with cardiovascular disease and to the goals and impact of treatment.

DISCUSSION

While there is no question that certain CVD risk factors are prone to cluster, we found that the metabolic syndrome has been imprecisely defined, there is a lack of certainty regarding its pathogenesis, and there is considerable doubt regarding its value as a CVD risk marker. Our analysis indicates that too much critically important information is missing to warrant its designation as a 'syndrome'.

CONCLUSION

Until much-needed research is completed, clinicians should evaluate and treat all CVD risk factors without regard to whether a patient meets the criteria for diagnosis of the 'metabolic syndrome'.

Structural and functional studies of FkpA from Escherichia coli, a cis/trans peptidyl-prolyl isomerase with chaperone activity

The protein FkpA from the periplasm of Escherichia coli exhibits both cis/trans peptidyl-prolyl isomerase (PPIase) and chaperone activities. The crystal structure of the protein has been determined in three different forms: as the full-length native molecule, as a truncated form lacking the last 21 residues, and as the same truncated form in complex with the immunosuppressant ligand, FK506. FkpA is a dimeric molecule in which the 245-residue subunit is divided into two domains. The N-terminal domain includes three helices that are interlaced with those of the other subunit to provide all inter-subunit contacts maintaining the dimeric species. The C-terminal domain, which belongs to the FK506-binding protein (FKBP) family, binds the FK506 ligand. The overall form of the dimer is V-shaped, and the different crystal structures reveal a flexibility in the relative orientation of the two C-terminal domains located at the extremities of the V. The deletion mutant FkpNL, comprising the N-terminal domain only, exists in solution as a mixture of monomeric and dimeric species, and exhibits chaperone activity. By contrast, a deletion mutant comprising the C-terminal domain only is monomeric, and although it shows PPIase activity, it is devoid of chaperone function. These results suggest that the chaperone and catalytic activities reside in the N and C-terminal domains, respectively. Accordingly, the observed mobility of the C-terminal domains of the dimeric molecule could effectively adapt these two independent folding functions of FkpA to polypeptide substrates.

CATS: a Cryogenic Automated Transfer System installed on the beamline FIP at ESRF

CATS allows users to mount and dismount their crystal samples remotely on the diffractometer, without entering the experimental hutch. CATS has been integrated into the automated control of FIP, allowing users to choose the wavelengths, optimize the beam intensity, mount and screen their crystal sample automatically and finally record diffraction data on the best sample(s).

Molecular mobility of confined phases in model mesoporous (MCM-41) and microporous (AlPO(4)-5 zeolite) host materials

The considered host materials are well suited to confine quasi-(1d) molecular phases, seeing that their porosities are composed of parallel unconnected cylindrical pores. For such a simple geometry, confinement effects can be simply described by a single parameter, the pore diameter phi. Our study concerns medium and ultra confinement ranges ( 40 A >or= Ø >or= 7.3 A). The primary effect of such confinements is the decrease of the molecular interactions within the confined phase. As a consequence, we have observed strong triple point depressure Delta T(3t) effects for hydrogen and water confined phases in MCM-41 samples. In the limit case of (1d) phase (the neopentane/AlPO(4)-5 system) it seems that a molecular mobility is observed even at very low temperature T=5 K. The secondary confinement effect is an increase of the interactions between the host inner surface and the confined molecular assembly induced by the pore diameter decreasing. Such host material influence gives rise, for medium range confinement to the physisorption of a curved solid film on the inner surface before the capillary phase condensation (hydrogen/MCM-41 (24 A)) and for ultra confinement to the solidification of the confined phase when the molecular species are commensurate with the inner surface sites (methane/AlPO(4)-5).

High-phasing-power lanthanide derivatives: taking advantage of ytterbium and lutetium for optimized anomalous diffraction experiments using synchrotron radiation

Ytterbium and lutetium are well suited for optimized anomalous diffraction experiments using synchrotron radiation. Therefore, two lanthanide complexes Yb-HPDO3A and Lu-HPDO3A have been produced that are similar to the Gd-HPDO3A complex already known to give good derivative crystals. Derivative crystals of hen egg-white lysozyme were obtained by co-crystallization using 100 mM solutions of each lanthanide complex. De novo phasing has been carried out using single-wavelength anomalous diffraction on data sets collected on each derivative crystal at the L(III) absorption edge of the corresponding lanthanide (ff" = 28 e(-)). A third data set was collected on a Lu-HPDO3A derivative crystal at the Se K absorption edge with f"(Lu) = 10 e(-). The structures were refined and compared with the known structure of the Gd-HPDO3A lysozyme derivative. The quality of the experimental electron-density maps allows easy model building. With L(III) absorption edges at shorter wavelengths than the gadolinium absorption edge, lutetium and ytterbium, when chelated by a ligand such as HPDO3A, form lanthanide complexes that are especially interesting for synchrotron-radiation experiments in structural biology.

Three-dimensional structure of FEZ-1, a monomeric subclass B3 metallo-beta-lactamase from Fluoribacter gormanii, in native form and in complex with D-captopril

The beta-lactamases are involved in bacterial resistance to penicillin and related compounds. Members of the metallo-enzyme class are now found in many pathogenic bacteria and are thus becoming of major clinical importance. The structures of the Zn-beta-lactamase from Fluoribacter gormanii (FEZ-1) in the native and in the complex form are reported here. FEZ-1 is a monomeric enzyme, which possesses two zinc-binding sites. These structures are discussed in comparison with those of the tetrameric L1 enzyme produced by Stenotrophomonas maltophilia. From this analysis, amino acids involved in the oligomerization of L1 are clearly identified. Despite the similarity in fold, the active site of FEZ-1 was found to be significantly different. Two residues, which were previously implicated in function, are not present in L1 or in FEZ-1. The broad-spectrum substrate profile of Zn-beta-lactamases arises from the rather wide active-site cleft, where various beta-lactam compounds can be accommodated.

A new class of gadolinium complexes employed to obtain high-phasing-power heavy-atom derivatives: results from SAD experiments with hen egg-white lysozyme and urate oxidase from Aspergillus flavus

Seven gadolinium complexes are shown to be excellent compounds for the preparation of heavy-atom derivatives for macromolecular crystallography projects. De novo phasing has been carried out using single-wavelength anomalous diffraction (SAD) on a series of gadolinium-derivative crystals of two proteins: hen egg-white lysozyme and urate oxidase from Aspergillus flavus. Lysozyme derivative crystals were obtained by co-crystallizing the protein with the corresponding gadolinium complex at a concentration of 100 mM. Diffraction data were collected to a resolution of 1.7 A using Cu K(alpha) radiation from a rotating-anode generator, making use of the high anomalous signal of gadolinium at this wavelength. Urate oxidase derivative crystals were obtained by soaking native crystals in 100 mM gadolinium complex solutions. Diffraction data were collected to a resolution close to 3 A using X-rays at the Gd L(III) absorption edge, taking advantage of the sharp white line on that edge. For all urate oxidase derivative crystals and three of the lysozyme crystals, SAD phasing led to electron-density maps of very high quality, allowing unambiguous chain tracing. From this study, the binding effectiveness of the gadolinium complexes seems to be related to the nature of the precipitant used for crystallization. These gadolinium complexes represent a new class of high-phasing-power heavy-atom derivatives that may be used for high-throughput structure-determination projects.