Antibacterial activity and antibacterial mechanism of flavaspidic acid BB against Staphylococcus haemelyticus.

BACKGROUND: Staphylococcus haemolyticus (S. haemolyticus) is the main etiological factor in skin and soft tissue infections (SSTI). S. haemolyticus infections are an important concern worldwide, especially with the associated biofilms and drug resistance. Herein, we investigated the inhibitory effect of Flavaspidic acid BB obtained from plant extractions on clinical S. haemolyticus strains and their biofilms. Moreover, we predicted its ability to bind to the protein-binding site by molecular simulation. Since the combination of Hsp70 and RNase P synthase after molecular simulation with flavaspidic acid BB is relatively stable, enzyme-linked immunosorbent assay (ELISA) was used to investigate Hsp70 and RNase P synthase to verify the potential antimicrobial targets of flavaspidic acid BB. RESULTS: The minimum inhibitory concentrations (MIC) of flavaspidic acid BB on 16 clinical strains of S. haemolyticus was 5 ~ 480 µg/mL, and BB had a slightly higher inhibitory effect on the biofilm than MUP. The inhibitory effect of flavaspidic acid BB on biofilm formation was better with an increase in the concentration of BB. Molecular simulation verified its ability to bind to the protein-binding site. The combination of ELISA kits showed that flavaspidic acid BB promoted the activity of Hsp70 and inhibited the activity of RNase P, revealing that flavaspidic acid BB could effectively inhibit the utilization and re-synthesis of protein and tRNA synthesis, thus inhibiting bacterial growth and biofilm formation to a certain extent. CONCLUSIONS: This study could potentially provide a new prospect for the development of flavaspidic acid BB as an antibacterial agent for resistant strains.

Carbopol emulgel loaded with ebastine for urticaria: development, characterization, in vitro and in vivo evaluation.

Urticaria affects all age groups of a population. It is triggered by allergens in foods, insect bites, medications, and environmental conditions. Urticaria is characterized by itching, a burning sensation, wheals and flares, erythema, and localized edema. The aim of this study was to develop a polymeric dosage form of ebastine using Carbopol 940 and mixture of span and tween. The emulsion was prepared, the gelling agent was added and the desired emulgel loaded with active drug was formulated. The formulations were subjected to physical stability, pH, viscosity, spreadability, drug content analysis, thermal analysis, in vitro drug release, and in vivo anti-allergic activity in animal model. The formulated emulgel exhibited good physical stability. The pH of the formulation was in the range of 5.2 ± 0.17 to 5.5 ± 0.20 which is suitable for topical application. Insignificant changes (p > .05) were observed in viscosity and spreadability of stored emulgels. The drug content was in the official limit of Pharmacopeia (i.e. 100 ± 10%). DSC measurements predicted that there is no interaction between the active moiety and excipients in emulgel formulation. The optimized formulation (ES3) released 74.25 ± 1.8% of ebastine after 12 h. The ebastine emulgel showed significant (p < .05; ANOVA) in vivo anti-allergic activity as compared to commercial product Benadryl® in histamine-induced allergy in rabbits. This study concluded that a topical drug delivery of ebastine-loaded emulgel could be well tolerated and safe for the treatment of urticaria/hives.

Haloperidol Metabolite II Valproate Ester (S)-(-)-MRJF22: Preliminary Studies as a Potential Multifunctional Agent Against Uveal Melanoma.

Increased angiogenesis and vascular endothelial growth factor (VEGF) levels contribute to higher metastasis and mortality in uveal melanoma (UM), an aggressive malignancy of the eye in adults. (±)-MRJF22, a prodrug of the sigma (σ) ligand haloperidol metabolite II conjugated with the histone deacetylase (HDAC) inhibitor valproic acid, has previously demonstrated a promising antiangiogenic activity. Herein, the asymmetric synthesis of (R)-(+)-MRJF22 and (S)-(-)-MRJF22 was performed to investigate their contribution to (±)-MRJF22 antiangiogenic effects in human retinal endothelial cells (HREC) and to assess their therapeutic potential in primary human uveal melanoma (UM) 92-1 cell line. While both enantiomers displayed almost identical capabilities to reduce cell viability than the racemic mixture, (S)-(-)-MRJF22 exhibited the highest antimigratory effects in endothelial and tumor cells. Given the fundamental contribution of cell motility to cancer progression, (S)-(-)-MRJF22 may represent a promising candidate for novel antimetastatic therapy in patients with UM.

Molecular determinant of substrate binding and specificity of cytochrome P450 2J2.

Cytochrome P450 2J2 (CYP2J2) is responsible for the epoxidation of endogenous arachidonic acid, and is involved in the metabolism of exogenous drugs. To date, no crystal structure of CYP2J2 is available, and the proposed structural basis for the substrate recognition and specificity in CYP2J2 varies with the structural models developed using different computational protocols. In this study, we developed a new structural model of CYP2J2, and explored its sensitivity to substrate binding by molecular dynamics simulations of the interactions with chemically similar fluorescent probes. Our results showed that the induced-fit binding of these probes led to the preferred active poses ready for the catalysis by CYP2J2. Divergent conformational dynamics of CYP2J2 due to the binding of each probe were observed. However, a stable hydrophobic clamp composed of residues I127, F310, A311, V380, and I487 was identified to restrict any substrate access to the active site of CYP2J2. Molecular docking of a series of compounds including amiodarone, astemizole, danazol, ebastine, ketoconazole, terfenadine, terfenadone, and arachidonic acid to CYP2J2 confirmed the role of those residues in determining substrate binding and specificity of CYP2J2. In addition to the flexibility of CYP2J2, the present work also identified other factors such as electrostatic potential in the vicinity of the active site, and substrate strain energy and property that have implications for the interpretation of CYP2J2 metabolism.

PI3Kδ Inhibition as a Potential Therapeutic Target in COVID-19.

The spread of the novel human respiratory coronavirus (SARS-CoV-2) is a global public health emergency. There is no known successful treatment as of this time, and there is a need for medical options to mitigate this current epidemic. SARS-CoV-2 uses the angiotensin-converting enzyme 2 (ACE2) receptor and is primarily trophic for the lower and upper respiratory tract. A number of current studies on COVID-19 have demonstrated the substantial increase in pro-inflammatory factors in the lungs during infection. The virus is also documented in the central nervous system and, particularly in the brainstem, which plays a key role in respiratory and cardiovascular function. Currently, there are few antiviral approaches, and several alternative drugs are under investigation. Two of these are Idelalisib and Ebastine, already proposed as preventive strategies in airways and allergic diseases. The interesting and evolving potential of phosphoinositide 3-kinase δ (PI3Kδ) inhibitors, together with Ebastine, lies in their ability to suppress the release of pro-inflammatory cytokines, such as IL-1ß, IL-8, IL-6, and TNF-α, by T cells. This may represent an optional therapeutic choice for COVID-19 to reduce inflammatory reactions and mortality, enabling patients to recover faster. This concise communication aims to provide new potential therapeutic targets capable of mitigating and alleviating SARS-CoV-2 pandemic infection.

Antihistamine Drug Ebastine Inhibits Cancer Growth by Targeting Polycomb Group Protein EZH2.

Enhancer of zester homolog 2 (EZH2), a histone lysine methyltransferase and the catalytic component of polycomb repressive complex 2, has been extensively investigated as a chromatin regulator and a transcriptional suppressor by methylating H3 at lysine 27 (H3K27). EZH2 is upregulated or mutated in most cancers, and its expression levels are negatively associated with clinical outcomes. However, the current developed small-molecule inhibitors targeting EZH2 enzymatic activities could not inhibit the growth and progression of solid tumors. Here, we discovered an antihistamine drug, ebastine, as a novel EZH2 inhibitor by targeting EZH2 transcription and subsequently downregulating EZH2 protein level and H3K27 trimethylation in multiple cancer cell lines at concentrations below 10 µmol/L. The inhibition of EZH2 by ebastine further impaired the progression, migration, and invasiveness of these cancer cells. Overexpression of Ezh2 wild-type and its mutant, H689A (lacking methyltransferase activity), rescued the neoplastic properties of these cancer cells after ebastine treatment, suggesting that EZH2 targeted by ebastine is independent of its enzymatic function. Next-generation RNA-sequencing analysis also revealed that C4-2 cells treated with 8 µmol/L ebastine showed a gene profiling pattern similar to EZH2-knockdown C4-2 cells, which was distinctively different from cells treated with GSK126, an EZH2 enzyme inhibitor. In addition, ebastine treatment effectively reduced tumor growth and progression, and enhanced progression-free survival in triple-negative breast cancer and drug-resistant castration-resistant prostate cancer patient-derived xenograft mice. Our data demonstrated that ebastine is a novel, safe, and potent anticancer agent for patients with advanced cancer by targeting the oncoprotein EZH2.

Four Synthetic Cathinones: 3-Chloromethcathinone, 4-Chloromethcathinone, 4-Fluoro-α-Pyrrolidinopentiophenone, and 4-Methoxy-α-Pyrrolidinopentiophenone Produce Changes in the Spontaneous Locomotor Activity and Motor Performance in Mice with Varied Profiles.

Two chloromethcathinones, 3-chloromethcathinone (3-CMC) and 4-chloromethcathinone (4-CMC), and two para-substituted α-pyrrolidinophenones, 4-methoxy-α-pyrrolidinopentiophenone (4-MeO-PVP) and 4-fluoro-α-pyrrolidinopentiophenone (4-F-PVP), represent synthetic cathinones, the second most frequently abused group of new psychoactive substances (NPSs), which has aroused a worldwide health concern in the last decade. Synthetic cathinones act as psychostimulants by elevating extracellular levels of monoaminergic neurotransmitters. This study investigates effects of 3-CMC, 4-CMC, 4-MeO-PVP, and 4-F-PVP on the spontaneous locomotor activity and motor performance of mice. Additionally, neurotoxicity of substituted methcathinones against SH-SY5Y neuroblastoma cells was evaluated. All test cathinones stimulate in a dose-dependent manner horizontal locomotor activity of mice. Consistently to our prior findings, pyrrovalerones, but not methcathinone derivatives, produce dose-dependent elevation of vertical locomotor activity (rearing behavior). None of the tested compounds decreases the time spent on the accelerating rotarod, pointing to the lack of considerable motor disability in mice after acute exposition. Only 4-MeO-PVP at the high tested dose (20 mg/kg) increases motor performance of mice. Considering that α-pyrrolidinophenones are highly potent and selective DA uptake inhibitors, while chloromethcathinones enhance non-selective DA/5-HT release, we suggest that the increase of vertical locomotor activity and performance on rotarod in mice may serve as a behavioral indicator of the monoaminergic profile of synthetic cathinones. Finally, this study gives first insights into cytotoxicity of both 3-CMC and 4-CMC displayed against SH-SY5Y cells, which emerges and intensifies after prolonged incubation, suggesting the indirect mechanism of action, unrelated to interactions with monoamine transporters.

Phloroglucinol Derivatives from Dryopteris crassirhizoma as Potent Xanthine Oxidase Inhibitors.

Dryopteris crassirhizoma rhizomes are used as a traditional medicine in Asia. The EtOAc extract of these roots has shown potent xanthine oxidase (XO) inhibitory activity. However, the main phloroglucinols in D. crassirhizoma rhizomes have not been analyzed. Thus, we investigated the major constituents responsible for this effect. Bioassay-guided purification isolated four compounds: flavaspidic acid AP (1), flavaspidic acid AB (2), flavaspidic acid PB (3), and flavaspidic acid BB (4). Among these, 1 showed the most potent inhibitory activity with a half-maximal inhibitory concentration (IC50) value of 6.3 µM, similar to that of allopurinol (IC50 = 5.7 µM) and better than that of oxypurinol (IC50 = 43.1 µM), which are XO inhibitors. A comparative activity screen indicated that the acetyl group at C3 and C3' is crucial for XO inhibition. For example, 1 showed nearly 4-fold higher efficacy than 4 (IC50 = 20.9 µM). Representative inhibitors (1-4) in the rhizomes of D. crassirhizoma showed reversible and noncompetitive inhibition toward XO. Furthermore, the potent inhibitors were shown to be present in high quantities in the rhizomes by a UPLC-QTOF-MS analysis. Therefore, the rhizomes of D. crassirhizoma could be used to develop nutraceuticals and medicines for the treatment of gout.

Extracellular Signal-Regulated Kinase Mediates Ebastine-Induced Human Follicle Dermal Papilla Cell Proliferation.

Ebastine is a second-generation histamine H1 receptor antagonist that is used to attenuate allergic inflammation. Ebastine has also shown to affect hair loss; however, the immunoregulatory effect of ebastine cannot completely exclude the possibility of spontaneous hair regrowth in ebastine-treated mice. In this study, we examined the effects of ebastine on the growth of human follicle dermal papilla cells (HFDPC) using a WST-1 cell proliferation assay and a bromodeoxyuridine incorporation assay. Ebastine was shown to significantly increase the proliferation of HFDPC. The expression levels of cell-cycle regulatory proteins and an antiapoptotic protein were increased in ebastine-treated HFDPC. Furthermore, elevated expression levels of phospho-AKT and phospho-p44/42 extracellular signal-regulated kinase (ERK) were observed in ebastine-treated HFDPC. Ebastine-mediated HFDPC growth was completely reversed by blocking ERK kinase. The results from our present study suggest that the regulation of HFDPC proliferation by ebastine might be directly involved in hair regrowth through the ERK signaling pathway.

Antibacterial activity of Morinda citrifolia Linneo seeds against Methicillin-Resistant Staphylococcus spp.

In traditional medicine, Morinda citrifolia (Noni) is used to treat various ailments, including skin and respiratory-tract infections. In this work, a bio-directed study (seed extracts) with five bacteria was carried out against four clinical isolates of Methicillin-Resistant Staphylococcus (MRS) and Staphylococcus aureus ATCC 29213 strain to find molecules capable of inhibiting them. Three organic extracts were obtained by maceration of the noni seeds with ascending polarity solvents (n-hexane, dichloromethane and methanol) that were evaluated as antibacterial in the model of bioautography and broth microdilution techniques. The results showed that the methanolic extract was the most active against all bacteria (MIC = 16 mg/mL). The chromatographic fractionation performed on this extract allowed obtaining six fractions (EMF1-EMF6), of which F1, F2 and F5 exhibited activity against some of the bacteria. EMF1 fraction reached an MIC of 25 µg/mL against S. haemolyticus twice as much as the positive control, in which the chemical content is mainly composed of a mixture of γ-butyrolactones (1-2) and esterified fatty acids (3-9); chemical characterization of the nine compounds was carried out based on gas chromatography coupled to masses. EMF2 fraction, presented an MIC of 200 µg/mL against S. aureus 0198 and S. haemolyticus 562B, where a coumarin known as scopoletin (10) was isolated and active against S. aureus 0198 (MIC = 100 µg/mL). EMF5 fraction demonstrated an MIC of 200 µg/mL against S. aureus 0198, S. haemolyticus 562B and S. epidermidis 1042, in which a neolignan known as americanin A (11) was identified, showing activity against S. haemolyticus 562B and S. epidermidis 1042 (MIC = 100 µg/mL). The chemical characterization of isolated compounds 10 and 11 was performed by the analysis of 1H and 13C NMR. Therefore, the methanolic extract, identified and isolated compounds showed important antibacterial activity against the MRS, validating its use in traditional medicine.

Effects of anesthesia on renal function and metabolism in rats assessed by hyperpolarized MRI.

PURPOSE: Anesthesia is necessary for most animal studies requiring invasive procedures. It is well documented that various types of anesthesia modulate a wide variety of important metabolic and functional processes in the body, and as such, represent a potential limitation in the study design. In the present study, we aimed to investigate the renal functional and metabolic consequences of 3 typical rodent anesthetics used in preclinical MRI: sevoflurane, inaction, and a mixture of fentanyl, fluanisone, and midazolam (FFM). METHODS: The renal effects of 3 different classes of anesthetics (inactin, servoflurane, and FFM) were investigated using functional and metabolic MRI. The renal glucose metabolism and hemodynamics was characterized with hyperpolarized [1-13 C]pyruvate MRI and by DCE imaging. RESULTS: Rats receiving sevoflurane or FFM had blood glucose levels that were 1.3-fold to 1.4-fold higher than rats receiving inactin. A 2.9-fold and 4.8-fold increased 13 C-lactate/13 C-pyruvate ratio was found in the FFM mixture anesthetized group compared with the sevoflurane and the inactin anesthetized groups. The FFM anesthesia resulted in a 50% lower renal plasma flow compared with the sevoflurane and the inactin anesthetized groups. CONCLUSION: This study demonstrates different renal metabolic and hemodynamic changes under 3 different anesthetics, using hyperpolarized MR in rats. Inactin and sevoflurane were found to affect the renal hemodynamic and metabolic status to a lesser degree than FFM. Sevoflurane anesthesia is particularly easy to induce and maintain during the whole anesthesia procedure, and as such, represents a good alternative to inaction, although it alters the blood glucose level.

Hyperjaponol H, A New Bioactive Filicinic Acid-Based Meroterpenoid from Hypericum japonicum Thunb. ex Murray.

Hyperjaponol H (1), a new filicinic acid-based meroterpenoid, with a 6/6/10 ring system trans-fused by hetero-Diels-Alder cycloaddition between a germacrane sesquiterpenoid and a filicinic acid moiety, was isolated from aerial parts of Hypericum japonicum. The elucidation of its structure and absolute configuration were accomplished by the analyses of extensive spectroscopic data and the comparison of Cotton effects of electron circular dichroism (ECD) with previously reported ones. The bioactivity assay showed that hyperjaponol H exhibited a moderate inhibitory efficacy on lytic Epstein-Barr virus (EBV) DNA replication in B95-8 cells.

Natural products as sources of new fungicides (IV): Synthesis and biological evaluation of isobutyrophenone analogs as potential inhibitors of class-II fructose-1,6-bisphosphate aldolase.

Several recently identified antifungal compounds share the backbone structure of acetophenones. The aim of the present study was to develop new isobutyrophenone analogs as new antifungal agents. A series of new 2,4-dihydroxy-5-methyl isobutyrophenone derivatives were prepared and characterized by 1H, 13C NMR and MS spectroscopic data. These products were evaluated for in vitro antifungal activities against seven plant fungal pathogens by the mycelial growth inhibitory rate assay. Compounds 3, 4a, 5a, 5b, 5e, 5f and 5g showed a broad-spectrum high antifungal activity. On the other hand, for the first time, these compounds were also assayed as potential inhibitors against Class II fructose-1,6-bisphosphate aldolase (Fba) from the rice blast fungus, Magnaporthe grisea. Compounds 5e and 5g were found to exhibit the inhibition constants (Ki) for 15.12 and 14.27 µM, respectively, as the strongest competitive inhibitors against Fba activity. The possible binding-modes of compounds 5e and 5g were further analyzed by molecular docking algorithms. The results strongly suggested that compound 5g could be a promising lead for the discovery of new fungicides via targeting Class II Fba.

The new designer drug buphedrone produces rewarding properties via dopamine D1 receptor activation.

Substituted cathinones are synthetic analogs of the active components of natural products and are widely abused worldwide. However, the rewarding properties of these agents have not yet been evaluated. In this study, we investigated the abuse potential of buphedrone [2-(methylamino)-1-phenylbutan-1-one, α-methylamino-butyrophenone] and its effects on the mesolimbic dopaminergic system in mice using conditioned place preference (CPP) analysis, a self-administration test, a locomotor activity test, a behavioral sensitization test and Western blot analysis. Treatment with buphedrone supported CPP and self-administration, enhanced locomotor activity and produced behavioral sensitization when mice were challenged with methamphetamine. SCH23390, a D1 dopamine antagonist, prevented buphedrone-induced CPP, whereas raclopride, a D2 dopamine antagonist, had no effect. SCH23390 also blocked locomotor activity increase by buphedrone, while raclopride partially attenuated locomotor activation. Western blot analysis revealed that repeated buphedrone treatment increased D1 dopamine receptor expression in the dorsal striatum and nucleus accumbens in mice. Collectively, these findings suggest the abuse potential of buphedrone and demonstrate the involvement of the dopaminergic system in the establishment of its rewarding properties.

In silico repurposing of antipsychotic drugs for Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is the most prevalent form of dementia and represents one of the highest unmet requirements in medicine today. There is shortage of novel molecules entering into market because of poor pharmacokinetic properties and safety issues. Drug repurposing offers an opportunity to reinvigorate the slowing drug discovery process by finding new uses for existing drugs. The major advantage of the drug repurposing approach is that the safety issues are already investigated in the clinical trials and the drugs are commercially available in the marketplace. As this approach provides an effective solution to hasten the process of providing new alternative drugs for AD, the current study shows the molecular interaction of already known antipsychotic drugs with the different protein targets implicated in AD using in silico studies. RESULT: A computational method based on ligand-protein interaction was adopted in present study to explore potential antipsychotic drugs for the treatment of AD. The screening of approximately 150 antipsychotic drugs was performed on five major protein targets (AChE, BuChE, BACE 1, MAO and NMDA) by molecular docking. In this study, for each protein target, the best drug was identified on the basis of dock score and glide energy. The top hits were then compared with the already known inhibitor of the respective proteins. Some of the drugs showed relatively better docking score and binding energies as compared to the already known inhibitors of the respective targets. Molecular descriptors like molecular weight, number of hydrogen bond donors, acceptors, predicted octanol/water partition coefficient and percentage human oral absorption were also analysed to determine the in silico ADME properties of these drugs and all were found in the acceptable range and follows Lipinski's rule. CONCLUSION: The present study have led to unravel the potential of leading antipsychotic drugs such as pimozide, bromperidol, melperone, anisoperidone, benperidol and anisopirol against multiple targets associated with AD. Benperidol was found to be the best candidate drug interacting with different target proteins involved in AD.

Preliminary assessment of midazolam, fentanyl and fluanisone combination for the sedation of rhesus macaques ( Macaca mulatta).

This study was undertaken to assess the suitability of fentanyl/fluanisone ('Hypnorm', VetaPharma; 0.315 mg/mL of fentanyl citrate and 10 mg/mL of fluanisone) alone or combined with midazolam in rhesus macaques. Fifteen rhesus macaques requiring sedation for veterinary procedures received an intramuscular (IM) dose range of Hypnorm from 0.01 mL/kg to 0.3 mL/kg either alone or combined with 0.5 mg/kg of midazolam. To reverse the sedation, flumazenil in combination with either naloxone, buprenorphine or butorphanol was administered intravenously (IV) or IM. Rhesus macaques were successfully sedated with 0.1 mL/kg of Hypnorm and 0.5 mg/kg of midazolam, and sedation was partially reversed by the administration of flumazenil and either naloxone or buprenorphine. However the primates remained slightly sedated and were only released into their home cage several hours post recovery. Butorphanol failed to induce recovery and caused marked respiratory depression. The neuroleptanalgesic combination, Hypnorm and midazolam, effectively immobilized rhesus macaques and was reversible with a combination of flumazenil and either naloxone or buprenorphine.

Comparing anesthesia with isoflurane and fentanyl/fluanisone/midazolam in a rat model of cardiac arrest.

Only one in ten patients survives cardiac arrest (CA), underscoring the need to improve CA management. Isoflurane has shown cardio- and neuroprotective effects in animal models of ischemia-reperfusion injury. Therefore, the beneficial effect of isoflurane should be tested in an experimental CA model. We hypothesize that isoflurane anesthesia improves short-term outcome following resuscitation from CA compared with a subcutaneous fentanyl/fluanisone/midazolam anesthesia. Male Sprague-Dawley rats were randomized to anesthesia with isoflurane (n = 11) or fentanyl/fluanisone/midazolam (n = 11). After 10 min of asphyxial CA, animals were resuscitated by mechanical chest compressions, ventilations, and epinephrine and observed for 30 min. Hemodynamics, including coronary perfusion pressure, systemic O2 consumption, and arterial blood gases, were recorded throughout the study. Plasma samples for endothelin-1 and cathecolamines were drawn before and after CA. Compared with fentanyl/fluanisone/midazolam anesthesia, isoflurane resulted in a shorter time to return of spontaneous circulation (ROSC), less use of epinephrine, increased coronary perfusion pressure during cardiopulmonary resusitation, higher mean arterial pressure post-ROSC, increased plasma levels of endothelin-1, and decreased levels of epinephrine. The choice of anesthesia did not affect ROSC rate or systemic O2 consumption. Isoflurane reduces time to ROSC, increases coronary perfusion pressure, and improves hemodynamic function, all of which are important parameters in CA models.NEW & NOTEWORTHY The preconditioning effect of volatile anesthetics in studies of ischemia-reperfusion injury has been demonstrated in several studies. This study shows the importance of anesthesia in experimental cardiac arrest studies as isoflurane raised coronary perfusion pressure during resuscitation, reduced time to return of spontaneous circulation, and increased arterial blood pressure in the post-cardiac arrest period. These effects on key outcome measures in cardiac arrest research are important in the interpretation of results from animal studies.

Stream segregation in the anesthetized auditory cortex.

Auditory stream segregation describes the way that sounds are perceptually segregated into groups or streams on the basis of perceptual attributes such as pitch or spectral content. For sequences of pure tones, segregation depends on the tones' proximity in frequency and time. In the auditory cortex (and elsewhere) responses to sequences of tones are dependent on stimulus conditions in a similar way to the perception of these stimuli. However, although highly dependent on stimulus conditions, perception is also clearly influenced by factors unrelated to the stimulus, such as attention. Exactly how 'bottom-up' sensory processes and non-sensory 'top-down' influences interact is still not clear. Here, we recorded responses to alternating tones (ABAB …) of varying frequency difference (FD) and rate of presentation (PR) in the auditory cortex of anesthetized guinea-pigs. These data complement previous studies, in that top-down processing resulting from conscious perception should be absent or at least considerably attenuated. Under anesthesia, the responses of cortical neurons to the tone sequences adapted rapidly, in a manner sensitive to both the FD and PR of the sequences. While the responses to tones at frequencies more distant from neuron best frequencies (BFs) decreased as the FD increased, the responses to tones near to BF increased, consistent with a release from adaptation, or forward suppression. Increases in PR resulted in reductions in responses to all tones, but the reduction was greater for tones further from BF. Although asymptotically adapted responses to tones showed behavior that was qualitatively consistent with perceptual stream segregation, responses reached asymptote within 2 s, and responses to all tones were very weak at high PRs (>12 tones per second). A signal-detection model, driven by the cortical population response, made decisions that were dependent on both FD and PR in ways consistent with perceptual stream segregation. This included showing a range of conditions over which decisions could be made either in favor of perceptual integration or segregation, depending on the model 'decision criterion'. However, the rate of 'build-up' was more rapid than seen perceptually, and at high PR responses to tones were sometimes so weak as to be undetectable by the model. Under anesthesia, adaptation occurs rapidly, and at high PRs tones are generally poorly represented, which compromises the interpretation of the experiment. However, within these limitations, these results complement experiments in awake animals and humans. They generally support the hypothesis that 'bottom-up' sensory processing plays a major role in perceptual organization, and that processes underlying stream segregation are active in the absence of attention.

Melperone but not bisoprolol or metoprolol is a clinically relevant inhibitor of CYP2D6: evidence from a therapeutic drug monitoring survey.

Cytochrome P450 enzymes (CYP) can be inhibited or induced by drugs, resulting in clinically significant drug-drug interactions that can cause unanticipated adverse reactions or therapeutic failures. The objective of the study was to analyze the in vivo inhibitory potential of the beta-blockers bisoprolol and metoprolol as well as the low-potency antipsychotic melperone on CYP2D6. By utilizing a large therapeutic drug monitoring database of 2874 samples, data from patients who had been treated with venlafaxine (VEN) either without (control group) or with a concomitant medication with bisoprolol, metoprolol or melperone were evaluated retrospectively to study the CYP2D6-catalyzed O-demethylation to O-desmethylvenlafaxine (ODVEN). Dose-adjusted serum levels (C/D) of VEN and ODVEN as well as the metabolic ratios (ODVEN/VEN) were computed for the four groups and compared using Kruskal-Wallis test. In total, 381 patients could be included for analysis. No significant difference was found in the median C/D (VEN), C/D (ODVEN) or C/D of the active moiety (VEN + ODVEN) in either the metoprolol (N = 103) or bisoprolol group (N = 101), compared to the control group (N = 108). In contrast, a significantly higher median C/D (VEN) (0.79 ng/ml/mg, range 0.13-5.73 ng/ml/mg) (P < 0.01) was found in the melperone group (N = 69), compared to the control group (0.46 ng/ml/mg, range 0.02-7.39 ng/ml/mg). A significant decrease (P < 0.01) was solely found in the median metabolic ratios of ODVEN/VEN between the melperone group (0.90, range 0.14-15.15), compared to the control group (2.39, range 0.06-15.31). The results of this study provided evidence that melperone but not bisoprolol or metoprolol has a clinically relevant inhibitory potential on CYP2D6.