Comparison between the impact of morning and evening doses of rivaroxaban on the circadian endogenous coagulation rhythm in healthy subjects.

UNLABELLED: ESSENTIALS: It is unknown whether single rivaroxaban doses should best be administered in the morning or evening. Circadian rhythm of coagulation/fibrinolysis was measured after morning or evening intake of rivaroxaban. Evening intake of rivaroxaban leads to prolonged exposure to rivaroxaban concentrations. Evening intake of rivaroxaban better matches the morning hypofibrinolysis. BACKGROUND: A circadian variation of the endogenous coagulation system exists with hypercoagulability and hypofibrinolysis and a corresponding peak of cardiovascular thromboembolic events in the morning. So far, no information is given as to whether single daily doses of the new oral anticoagulant drug rivaroxaban should best be administered in the morning or the evening. MATERIALS AND METHODS: Sixteen healthy male or female volunteers with a mean age of 26 ± 7 years were included in this randomized, controlled, analyst-blinded cross-over clinical trial. All subjects were given three morning and three evening single doses of 10 mg rivaroxaban. Circadian rhythms of prothrombin fragment 1 + 2, plasminogen activator inhibitor, and plasmin-antiplasmin complex were measured before any medication intake, as well as after morning or evening medication intake. Rivaroxaban concentrations were determined by an anti-activated factor X assay and liquid chromatography-mass spectrometry. MAIN RESULTS: Concentrations of rivaroxaban were higher 12 h after evening intake of rivaroxaban than 12 h after morning intake (53.3 ng mL(-1) [95% confidence interval 46.0-67.8] vs. 23.3 ng mL(-1) [19.4-29.1, respectively]). Rivaroxaban intake in the evening reduced morning F1+2 concentrations better at 8:00 AM than did administration on awakening (85 ± 25 nmol L(-1) vs. 106 ± 34 nmol L(-1) , CI: 9.4-32.1). In addition, this suppression effect was longer lasting after evening intake. CONCLUSIONS: Evening intake of rivaroxaban leads to prolonged exposure to rivaroxaban concentrations and better matches the morning hypofibrinolysis. These results might help to further improve the efficacy and safety of rivaroxaban treatment.

Destruxins: fungal-derived cyclohexadepsipeptides with multifaceted anticancer and antiangiogenic activities.

Destruxins (Dtx) are secondary metabolites of the entomopathogenic fungus Metarhizium anisopliae. Recently, Dtx came into focus of interest as anticancer therapeutics. However, data on human and especially on cancer cells are fragmentary. In order to successfully establish novel anticancer therapeutics, a broad knowledge on the cellular and molecular mechanisms underlying their activity is essential. Consequently, this study aimed to investigate the impact of the most common Dtx derivatives A, B and E on human cancer cell growth and survival with a focus on colon cancer cell models. Summarizing, the experimental data showed that (i) Dtx A and B exert potent antiproliferative activity in the micromolar and Dtx E in the nanomolar range in KB-3-1, A549, CaCo-2, and especially in HCT116 colon cancer cells, (ii) all three Dtx derivatives cause imbalance of cell cycle distribution, (iii) their cytostatic/cytotoxic effects are widely p53-independent but reduced by p21- and bax-deletion, respectively, (iv) cytotoxicity is based on intrinsic apoptosis induction and associated with phosphoinositide-3-kinase (PI3K)/Akt pathway inhibition, (v) anticancer activity of Dtx E but not Dtx A and B involves disturbance of the intracellular redox balance, (vi) Dtx inhibit the migration and tube formation of human endothelial cells indicating antiangiogenic potential, and (vii) all three Dtx derivatives possess ionophoric properties not differing in conductivity, ion selectivity and single channel kinetics. Thus, Dtx represent feasible, multifunctional anticancer drug candidates for preclinical development especially against colorectal cancer.

Development and validation of a rapid ultra-high performance liquid chromatography diode array detector method for Vitex agnus-castus.

A rapid ultra-high performance liquid chromatography diode array detector (UHPLC-DAD) method was developed and validated for the simultaneous determination of all classes of non-volatile phytochemicals (iridoids, flavonoids and diterpenes) in Vitex agnus-castus (Lamiaceae) fruits, a traditional medicinal plant used against premenstrual symptoms (PMS) and other disorders. Seven marker compounds, 3,4-dihydroxybenzoic acid, p-hydroxybenzoic acid, agnuside, 5-hydroxykaempferol-3,6,7,4'-tetramethylether, 1,2-dibenzoic acid glucose, methoxy-vitexilactone, and vitetrifolin D were isolated from the methanol extract of V. agnus-castus to be used as reference substances. Chromatographic separation was performed on a Zorbax Eclipse XDB-C18 (50mm×2.1mm) UHPLC column with 1.8µm particle size, within 20min. A solvent gradient from 0.5% acetic acid to acetonitrile at a flow rate of 0.6mL/min was used as mobile phase. Analyte detection and quantification was realized at 210nm and 260nm. The UHPLC-DAD assay was validated for the quantitative analysis of agnuside, isovitexin, casticin, 5-hydroxykaempferol-3,6,7,4'-tetramethylether and vitetrifolin D. It was found to be specific, accurate, precise, and reproducible for the quantification of these compound within a concentration range of 0.7-500.0µg/mL for casticin and 5-hydroxykaempferol-3,6,7,4'-tetramethylether, 1.4-1000.0µg/mL for isovitexin and agnuside, and 12.4-1000.0µg/mL for vitetrifolin D. Intra- and inter-day variations showed relative standard deviations (RSD) of less than 3.9% and 6.4%, respectively. Tentatively assignment of 62 chromatographic features found in the UHPLC-DAD assay was carried out by coupling the UHPLC instrument to a quadrupole time-of-flight mass spectrometer via an electrospray ionization interface (ESI-QTOF-MS) operated in positive and negative ion mode. By using the established quantitative UHPLC-DAD assay to asses agnuside, isovitexin, casticin, 5-hydroxykaempferol-3,6,7,4'-tetramethylether and vitetrifolin D in V. agnus-castus derived preparations as extracts, tinctures and tablets, the applicability of the developed assay to phytopharmaceuticals was successfully proven.

Teicoplanin pharmacokinetics in critically ill patients on continuous veno-venous hemofiltration.

Pharmacokinetics of teicoplanin (TP) was assessed in critically ill patients on continuous veno-venous hemofiltration (CVVH), in eleven patients, after the first dose and in another four after repeated administration. The TP peak concentration amounted to 55.44 +/- 15.90 microg/ml and 81.28 +/- 28.55 microg/ml (mean +/- SD), the trough concentration 6.4 +/- 1.7 microg/ml and 21.3 +/- 5.0 microg/ml, the half-life 15.7 +/- 5.7 and 35.1 +/- 12.3 h, the apparent volume of distribution 0.84 +/- 0.22 and 0.48 +/- 0.09 l/kg and the TP clearance 39 +/- 12 and 11 +/- 4 ml/h/kg after the first dose and after repeated administration, respectively. The mean sieving coefficient of TP was 0.15. After a 1,200 mg loading dose, daily maintenance doses of 600 - 1,800 mg were required for achieving trough levels of 15 - 25 microg/ml. Therapeutic drug monitoring is indispensable during CVVH because of a considerable variability of TP pharmacokinetics.

Antifungal stilbenoids from Stemona collinsae.

Fifteen new stilbenoids including 11 phenylbenzofurans, the stemofurans A-K (1-11), and four dihydrostilbenes, the stilbostemins A (15), C (17), E (19), and F (20), were isolated and identified from a methanolic extract of Stemona collinsae roots together with five known derivatives, the stilbenes pinosylvin (13) and 4'-methylpinosylvin (14), the dihydrostilbenes, stilbostemins B (16) and D (18), and the dihydrophenanthrene racemosol (12) as well as (+)-sesamin, coniferyl alcohol, and stigmasterol. Bioautographic tests with Cladosporium herbarum displayed antifungal activity for stilbenoids of all four structural types. Ten derivatives were tested against five microfungi using the microdilution technique linked with digital image analysis of germ tubes.

Functional magnetic resonance imaging evidence for right-hemisphere involvement in processing unusual semantic relationships.

Brain areas active in generating usual (typical) or unusual (atypical) noun-verb relations were examined using functional magnetic resonance imaging. Seven adults generated the 1st verb to come to mind (usual verb) in response to novel and repeated nouns (priming test) and then generated either an unusual verb or the 1st verb to come to mind in response to novel nouns (unusual test). The left inferior prefrontal cortex (LIPC) and right cerebellum were more active when generating usual verbs to novel nouns than to repeated nouns. When participants generated unusual verbs, there was no increased activation in LIPC, but there was increased activity in the right middle and superior frontal gyri, left middle frontal gyrus, and bilateral cerebellum. Results support theories that the right hemisphere is involved in the processing of distant associations that may be useful in creative thought and problem solving.

Hemispheric asymmetries and individual differences in visual concept learning as measured by functional MRI.

Dynamic changes in brain regions active while learning novel visual concepts were examined in humans using functional magnetic resonance imaging. Participants learned to distinguish between exemplars of two categories, formed as distortions of different unseen prototype stimuli. Regions of the right hemisphere (dorsolateral prefrontal and inferior parietal areas) were active early in learning and throughout task performance, whereas homologous portions of the left hemisphere were active only in later stages of learning. Left dorsolateral prefrontal activation was found only in participants who showed superior conceptual learning. Such a progression from initial right-hemisphere processing of specific instances to bilateral activity as left-hemisphere conceptual processes are recruited may underlie the development of many forms of visual knowledge.

Verb generation priming involves conceptual implicit memory.

Brain activation patterns differ and generation latencies are reduced when generating verbs to repeated nouns (Raichle et al., 1994). Amnesic participants show normal magnitude of priming (Seger et al., 1997). Despite its importance in neuropsychology, verb generation priming is not well characterized psychologically. Six behavioral studies found that verb generation priming was specific to the verb rather than to the noun or the noun-verb pair, was equivalent after overt or covert generation and after reading verbs or generating verbs, was affected by levels of processing, and transferred completely across languages in bilinguals. These results indicate that verb generation priming involves priming of particular responses and happens at a conceptual level. These findings provide new insights about the significance of brain imaging and neuropsychological studies involving verb generation priming.

Striatal activation during acquisition of a cognitive skill.

The striatum is thought to play an essential role in the acquisition of a wide range of motor, perceptual, and cognitive skills, but neuroimaging has not yet demonstrated striatal activation during nonmotor skill learning. Functional magnetic resonance imaging was performed while participants learned probabilistic classification, a cognitive task known to rely on procedural memory early in learning and declarative memory later in learning. Multiple brain regions were active during probabilistic classification compared with a perceptual-motor control task, including bilateral frontal cortices, occipital cortex, and the right caudate nucleus in the striatum. The left hippocampus was less active bilaterally during probabilistic classification than during the control task, and the time course of this hippocampal deactivation paralleled the expected involvement of medial temporal structures based on behavioral studies of amnesic patients. Findings provide initial evidence for the role of frontostriatal systems in normal cognitive skill learning.

Structure of the active domain of the herpes simplex virus protein ICP47 in water/sodium dodecyl sulfate solution determined by nuclear magnetic resonance spectroscopy.

ICP47 encoded by herpes simplex virus (HSV) is a key factor in the evasion of cellular immune response against HSV-infected cells. By specific inhibition of the transporter associated with antigen processing (TAP), ICP47 prevents peptide transport into the endoplasmic reticulum and subsequent loading of major histocompatibility complex (MHC) class I molecules. Amino acid residues 3-34 have been identified as the active domain. This domain appeared to be unstructured in aqueous solution, whereas after binding to membranes an alpha-helical conformation was observed. Here, we have analyzed the structure of ICP47(2-34) in a lipidlike environment by nuclear magnetic resonance (NMR) spectroscopy. In micellar solution of deuterated sodium dodecyl sulfate, the viral TAP inhibitor adopts an ordered structure. There are two helical regions extending from residues 4 to 15 and from residues 22 to 32. Arg-16 is found on the C-terminus of the first helix, and Gly-33 serves as a terminator of the second helix. A loop between residues 17 and 21 is also evident in the structure. The relative orientation of the helices toward each other, however, could not be determined due to the paucity of NOEs from residues 18-21.

Independent judgment-linked and motor-linked forms of artificial grammar learning.

Three experiments investigated whether a motor-linked measure (string typing speed) and an judgment-linked measure (grammatical judgment of strings) accessed the same implicit learning mechanisms in the artificial grammar learning task. Participants first studied grammatical strings through observation or through responding to each letter by typing it and then performed typing and grammatical judgment tests. Grammatical judgment test performance was better after observation than after respond learning, whereas typing test performance on higher order relations was worse after observation than after respond learning (Experiment 1). Participants transferred grammatical knowledge across letter sets on the grammatical judgment test, but not on the typing test (Experiment 2). Typing speed did not differ for hits (grammatical strings classified by participants as grammatical) and misses (grammatical strings classified as nongrammatical, Experiment 3). These results are consistent with typing and grammatical judgment tests tapping independent mechanisms and indicate that implicit learning may consist of many different forms of learning rather than being a unitary learning mechanism.

Preserved verb generation priming in global amnesia.

In the verb generation task, participants are presented with nouns and generate for each one an appropriate verb. Raichle et al. (Cerebral Cortex, 1994, 4, 8-26) found that when participants generated verbs to repeated nouns, generation latencies were reduced and different patterns of brain activation were present. In order to examine whether verb generation priming is dependent or independent of declarative memory, verb generation priming was compared between 13 amnesic (seven with alcoholic Korsakoff's syndrome, six with other etiologies) and 19 control participants (10 with a history of alcoholism). Both amnesic and control participants became faster across blocks on repeated nouns and slowed when novel nouns were introduced. Priming was verb specific for both groups: it was equivalent whether generated to a repeated or a novel noun. Verb generation priming, therefore, can occur independently of declarative memory.

Two forms of sequential implicit learning.

A serial reaction time (SRT) experiment tested the hypothesis that there are two independent forms of implicit learning: learning that is linked to making judgments about stimuli, and learning that is linked to motor processing. Participants performed 2, 6, or 12 blocks of single task SRT, dual task SRT, or observation with one of five sequence; each sequence had the same underlying structure. Participants then performed two implicit tests, SRT (a motor-linked test) and pattern judgment, as well as a generation test and an explicit knowledge test. There was a double dissociation of the effect of sequence surface structure on SRT and pattern judgment. SRT and pattern judgment competence developed independently of each other across length of acquisition task. Performance on both implicit tasks did not depend on explicit knowledge. These results indicate that the SRT and pattern judgment measures tap independent forms of implicit learning, which is consistent with the modular nature of memory and cognition.

Implicit learning.

Implicit learning is nonepisodic learning of complex information in an incidental manner, without awareness of what has been learned. Implicit learning experiments use 3 different stimulus structures (visual, sequence, and function) and 3 different dependent measures or response modalities (conceptual fluency, efficiency, and prediction and control). Implicit learning may require a certain minimal amount of attention and may depend on attentional and working memory mechanisms. The result of implicit learning is implicit knowledge in the form of abstract (but possibly instantiated) representations rather than verbatim or aggregate representations. Implicit learning shows biases and dissociations in learning different stimulus structures. The dependence of implicit learning on particular brain areas is discussed, some conclusions are drawn for modeling implicit learning, and the interaction of implicit and explicit learning is considered.

Transmission of bovine leukemia virus by Tabanus fuscicostatus.

Bovine leukemia virus (BLV) was transmitted by horse flies, Tabanus fuscicostatus, from a cow with a lymphocyte count of 31,500/mm3 to goats and dairy calves. As few as 10 and 20 flies transmitted BLV to goats and calves respectively, but the minimal number of flies required to transmit the infection was not established. Groups of 150 and 100 T fuscicostatus transmitted BLV to beef calves from a cow with a lymphocyte count of 14,600/mm3. These results support a role for horse flies in the horizontal transmission of BLV.

Medical record retention issues.

The author of this article carried out a survey of malpractice cases filed in Houston, TX. He discusses the outcome of the study and suggests a 10-year record retention policy.

Serological detection of multiple retroviral infections in cattle: bovine leukemia virus, bovine syncytial virus and bovine visna virus.

Individual experimental animals used in our studies on bovine leukemia virus (BLV) are routinely screened for the presence of antibodies to the three bovine lymphotropic retroviruses. We utilized these screening methods to examine frozen sera from eight herds for antibodies to BLV, bovine visna virus (BVV) and bovine syncytial virus (BSV). Serum samples from 235 animals in four dairy and four beef herds were analyzed. Detection methods used included indirect fluorescent antibody tests of virus-infected cell cultures (BLV, BSV, BVV) and agar gel immunodiffusion (BLV). Sera from the BLV-infected animals in the dairy herds showed the highest single (50%, 49/97) and multiple (30%, 29/97) infections compared with 5% (7/138) and less than 1% (1/138), respectively in the beef herds. Single BVV infections were not detected in the dairy herds, but 11% (11/97) of the sera contained antibodies to BVV plus BLV or BSV. Five sera from beef cattle had antibodies only to BVV and four were obtained from one herd. Only one beef serum of the 138 tested demonstrated multiple antibodies (BLV, BVV).

Characterization of infertility and bovine leukemia virus infection in beef bulls on southwestern Louisiana coastal range.

One hundred and twenty-six beef bulls on southwestern Louisiana coastal range were evaluated for breeding soundness. Samples were taken to determine the incidence of bovine leukemia virus (BLV) infection, and the prepuce was cultured for potential pathogens. A high incidence (47.6%) of questionable and unsatisfactory potential breeders resulted mainly from 37.0% of the bulls exhibiting high numbers of abnormal sperm cells in the semen. Only bulls in the 4-to 5-yr age group exhibited the expected incidence of normal spermiograms. Genital campylobacteriosis was not diagnosed but there was genital trichomoniasis in three of the seven herds. Hemophilus somnus , mycoplasma and ureaplasma were isolated from the prepuce of 13.3, 48.8 and 36.7% of the bulls, respectively. Isolation of these organisms from the prepuce did not appear to be associated with abnormal spermiograms. Of the bulls studied, 34.4% had positive AGID reactions for BLV. Bulls seropositive to BLV had an increased incidence of leukocyte counts that were above the normal range. There was no apparent relationship between BLV infection and abnormal spermiograms.