The cortex of the rabbit (Oryctolagus cuniculus) is rich in melatonin binding sites, and particularly abundant is the parietal cortex. Consequently, we characterized the putative melatonin receptor ...in the parietal cortex by a series of in vitro ligand-receptor binding experiments and biochemical and electrophysiological studies. The in vitro saturation and competition experiments demonstrated that the binding in the crude cortical membrane preparations was of high affinity and specificity. Guanine nucleotides (GDP, GTP, and GTP gamma S) inhibited the specific 2-125Iiodomelatonin binding in a dose-dependent manner. Coincubation with a nonhydrolyzable GTP analog provoked a shift in the binding affinity; the numerical values of the Kd increased from 20-30 to 200-600 pM. Melatonin, in nanomolar concentrations, was able to inhibit the forskolin-stimulated accumulation of cAMP in parietal cortex explants, and preincubation with pertussis toxin counteracted this effect of melatonin. Apparently, the melatonin binding site in the rabbit parietal cortex is linked to its second messenger via a pertussis toxin-sensitive G-protein, probably of the inhibitory Gi class, similar to what has been described for different parts of the brain of other vertebrates. The experiments on the spontaneous firing activity of single neurons in the third to fourth layer of the parietal cortex in anesthetized animals showed that melatonin and its potent agonist 2-iodomelatonin exhibited gamma-aminobutyric acid (GABA)-like effects and were able alone, in nanomolar concentrations, to significantly slow the neuronal firing activity. Moreover, both melatonin and 2-iodomelatonin potentiated the effect of GABA on the neuronal activity, leading to powerful inhibition of the tested neurons. Undoubtedly, the binding site in the rabbit parietal cortex possesses all of the characteristics of a functional receptor. We suggest that melatonin is involved in the control of fundamental cortical functions and that it acts in concert with GABA, one of the two major inhibitory neurotransmitters in the central nervous system.
Background and purpose
Language reorganization has been described in brain lesions with respect to their location and timing, but little is known with respect to their etiology. We used fMRI to ...investigate the effects of different types of left hemisphere lesions (GL = gliomas, TLE = temporal lobe epilepsy and CA = cavernous angioma) on the topographic intra-hemispheric language plasticity, also considering their location.
Methods
Forty-seven right-handed patients with 3 different left hemisphere lesions (16 GL, 15 TLE and 16 CA) and 17 healthy controls underwent BOLD fMRI with a verb-generation task. Euclidean distance was used to measure activation peak shifts among groups with respect to reference Tailarach coordinates of Inferior Frontal Gyrus, Superior Temporal Sulcus and Temporo-Parietal Junction. Mixed-model ANOVAs were used to test for differences in activation peak shifts.
Results
Significant activation peak shifts were found in GL patients with respect both to HC and other groups (TLA and CA). In addition, in the same group of patients a significant effect of tumor location (anterior or posterior) was detected.
Conclusions
We demonstrated that intra-hemispheric language plasticity is influenced by the type of lesion affecting the left hemisphere and that fMRI is especially valuable in the preoperative assessment of such reorganization in glioma patients.
Taraxacum kok-saghyz (Tks), also known as the Russian dandelion, is a recognized alternative source of natural rubber quite comparable, for quality and use, to the one obtained from the so-called ...rubber tree, Hevea brasiliensis. In addition to that, Tks roots produce several other compounds, including inulin, whose use in pharmaceutical and dietary products is quite extensive. Histone-modifying genes (HMGs) catalyze a series of post-translational modifications that affect chromatin organization and conformation, which, in turn, regulate many downstream processes, including gene expression. In this study, we present the first analysis of HMGs in Tks. Altogether, we identified 154 putative Tks homologs: 60 HMTs, 34 HDMs, 42 HATs, and 18 HDACs. Interestingly, whilst most of the classes showed similar numbers in other plant species, including M. truncatula and A. thaliana, HATs and HMT-PRMTs were indeed more abundant in Tks. Composition and structure analysis of Tks HMG proteins showed, for some classes, the presence of novel domains, suggesting a divergence from the canonical HMG model. The analysis of publicly available transcriptome datasets, combined with spatial expression of different developmental tissues, allowed us to identify several HMGs with a putative role in metabolite biosynthesis. Overall, our work describes HMG genomic organization and sets the premises for the functional characterization of epigenetic modifications in rubber-producing plants.
Backgrounds
Irradiation of the hippocampus plays a role in neurocognitive toxicity. Its delineation is complex and in practice different head position can vary hippocampus morphology on axial images; ...so atlas in a single standard position can result ineffective to describe different hippocampal morphologies in different head set-up. The purpose of our study was to develop a guide based on magnetic resonance imaging for hippocampus delineation in three different head set-ups.
Materials and methods
Three patients were selected to elaborate our guide. Patients were submitted to a planning computed tomography of the brain district in different head positions: 1° patient in neutral, 2° patient in over-extended and 3° patient in head hypo-extended position; axial images of 2-mm thickness were obtained. Computed tomography images were fused with diagnostic brain magnetic resonance images; then hippocampus was delineated according to RTOG atlas. Contours were revised by two neuro-radiologists with >5-year expertise in neuroimaging.
Results
A guide was developed for each of three head positions considered. RTOG atlas provided an easy and reliable guide for hippocampus delineation in neutral position of the head. Discrepancies were observed in cranial and caudal limit in case of head over/hypo-extension, as well as in hippocampal morphology near the encephalic trunk where hippocampus takes an oblong shape in over-extended set-up, and short and stocky in hypo-extension.
Conclusion
Our guide can represent a useful tool for hippocampal delineation in clinical practice and for different anatomic variations due to different head positions. Certainly, it should be validated in practice.
We have previously reported aspirin failure in suppressing enhanced thromboxane (TX) biosynthesis in a subset of episodes of platelet activation during the acute phase of unstable angina. The recent ...discovery of a second prostaglandin H synthase (PGHS-2), inducible in response to inflammatory or mitogenic stimuli, prompted us to reexamine TXA2 biosynthesis in unstable angina as modified by two cyclooxygenase inhibitors differentially affecting PGHS-2 despite a comparable impact on platelet PGHS-1.
We randomized 20 patients (15 men and 5 women aged 59+/-10 years) with unstable angina to short-term treatment with aspirin (320 mg/d) or indobufen (200 mg BID) and collected 6 to 18 consecutive urine samples. Urinary 11-dehydro-TXB2 was extracted and measured by a previously validated radioimmunoassay as a reflection of in vivo TXA2 biosynthesis. Metabolite excretion averaged 102 pg/mg creatinine (median value; n=76) in the aspirin group and 55 pg/mg creatinine (median value; n=99) in the indobufen group (P<.001). There were 16 samples (21%) with 11-dehydro-TXB2 excretion >200 pg/mg creatinine among patients treated with aspirin versus 6 such samples (6%) among those treated with indobufen (P<.001). In vitro and ex vivo studies in healthy subjects demonstrated the capacity of indobufen to largely suppress monocyte PGHS-2 activity at therapeutic plasma concentrations. In contrast, aspirin could only inhibit monocyte PGHS-2 transiently at very high concentrations.
We conclude that in unstable angina, episodes of aspirin-insensitive TXA2 biosynthesis may reflect extraplatelet sources, possibly expressing the inducible PGHS in response to a local inflammatory milieu, and a selective PGHS-2 inhibitor would be an ideal tool to test the clinical relevance of this novel pathway of arachidonic acid metabolism in this setting.
We evaluated whether therapeutic blood levels of meloxicam are associated with selective inhibition of monocyte cyclooxygenase (COX)-2 in vitro and ex vivo. Concentration-response curves for the ...inhibition of monocyte COX-2 and platelet COX-1 were obtained in vitro after the incubation of meloxicam with whole blood samples. Moreover, 11 healthy volunteers received placebo or 7.5 or 15 mg/day meloxicam, each treatment for 7 consecutive days, according to a randomized, double-blind, crossover design. Before dosing and 24 h after the seventh dose of each regimen, heparinized whole blood samples were incubated with lipopolysaccharide (10 microgram/ml) for 24 h at 37 degrees C, and prostaglandin E2 was measured in plasma as an index of monocyte COX-2 activity. The production of thromboxane B2 in whole blood allowed to clot at 37 degrees C for 60 min was assessed as an index of platelet COX-1 activity. The administration of placebo did not significantly affect plasma prostaglandin E2 (21. 3 +/- 7.5 versus 19.1 +/- 4 ng/ml, mean +/- S.D., n = 11) or serum thromboxane B2 (426 +/- 167 versus 425 +/- 150 ng/ml) levels. In contrast, the administration of 7.5 and 15 mg of meloxicam caused dose-dependent reductions in monocyte COX-2 activity by 51% and 70%, respectively, and in platelet COX-1 activity by 25% and 35%, respectively. Although the IC50 value of meloxicam for inhibition of COX-1 was 10-fold higher than the IC50 value of COX-2 in vitro, this biochemical selectivity was inadequate to clearly separate the effects of meloxicam on the two isozymes after oral dosing as a function of the daily dose and interindividual variation in steady-state plasma levels.
1
The isoprostane 8‐epi‐prostaglandin (PG)F2α is produced by free radical‐catalyzed peroxidation of arachidonic acid. It may also be formed as a minor product of the cyclo‐oxygenase activity of ...platelet PGH synthase (PGHS)‐1. We investigated 8‐epi‐PGF2α production associated with induction of the human monocyte PGHS‐2 and its pharmacological modulation.
2
Heparinized whole blood samples were drawn from healthy volunteers, 48 h following oral dosing with aspirin 300 mg to suppress platelet cyclo‐oxygenase activity. One ml aliquots were incubated with lipopolysaccharide (LPS: 0.1–50 μg ml−1) for 0–24 h at 37°C. PGE2 and 8‐epi‐PGF2α were measured in separated plasma by radioimmunoassay and enzyme immunoassay techniques.
3
Levels of both eicosanoids were undetectable (i.e. < 60 pg ml−1) at time 0. LPS induced the formation of PGE2 and 8‐epi‐PGF2α in a time‐ and concentration‐dependent fashion, coincident with the induction of PGHS‐2 detected by Western blot analysis of monocyte lysates. After 24 h at 10 μg ml−1 LPS, immunoreactive PGE2 and 8‐epi‐PGF2α averaged 10,480 ± 4,643 and 295 ± 140 pg ml−1 (mean ± s.d., n = 6), respectively.
4
Dexamethasone and 5‐methanesulphonamido‐6‐(2, 4‐difluorothiophenyl)‐1‐indanone (L‐745,337), a selective inhibitor of the cyclo‐oxygenase activity of PGHS‐2, reduced PGE2 and 8‐epi‐PGF2α production in response to LPS.
5
Isolated monocytes produced PGE2 and 8‐epi‐PGF2α in response to LPS (10 μg ml−1) in a time‐dependent fashion. Monocyte PGE2 and 8‐epi‐PGF2α production was largely prevented by dexamethasone (2 μm) and cycloheximide (10 μg ml−1) in association with suppression of PGHS‐2 but not of PGHS‐1 expression.
6
We conclude that the induction of PGHS‐2 in human monocytes is associated with cyclo‐oxygenase‐dependent generation of the vasoconstrictor and platelet‐agonist 8‐epi‐PGF2α.
Background
The aim of this study was to test the hypothesis that nimesulide, a nonsteroidal antiinflammatory drug, or its principal metabolite 4‐hydroxynimesulide, is a selective inhibitor of ...prostaglandin H synthase‐2 in human beings.
Methods
Heparinized whole blood samples obtained from healthy subjects were incubated with lipopolysaccharide (10 μg/ml) for 24 hours at 37° C and prostaglandin E2 was measured in plasma as an index of monocyte prostaglandin H synthase‐2 activity. The production of thromboxane B2 in whole blood allowed to clot at 37° C for 60 minutes was assessed as an index of platelet prostaglandin H synthase‐1 activity. We also measured the urinary excretion of 11‐dehydrothromboxane B2, prostaglandin E2, 6‐ketoprostaglandin F1α, and thromboxane B2 as in vivo indexes of cyclooxygenase activity. All prostanoids were measured by previously validated radioimmunoassay techniques.
Results
In the whole blood assays in vitro, nimesulide was twentyfold more potent than 4‐hydroxynimesulide toward the two isozymes and both compounds displayed a twentyfold preference for prostaglandin H synthase‐2 versus prostaglandin H synthase‐1. The administration of a single oral dose of 100 mg nimeslude to six healthy subjects significantly (p < 0.01) reduced monocyte prostaglandin H synthase‐2 and prostaglandin H synthase‐1 activity ex vivo by more than 90% and 50%, respectively, up to 6 hours. At 24 hours, prostaglandin H synthase‐2 but not prostglandin H synthase‐1 activity was significantly reduced by 49% (p < 0.05). Nimesulide significantly (p < 0.05) reduced the urinary excretion of 11‐dehydrothromboxane B2 and 6‐ketoprostaglandin F1α by approximately 30% and 25%, respectively, while not affecting that of prostaglandin E2 and thromboxane B2.
Conclusions
Nimesulide is a potent inhibitor of human monocyte prostaglandin H synthase‐2. However, despite a twentyfold selectivity ratio, therapeutic plasma levels of nimesulide are sufficiently high to cause detectable inhibition of platelet prostaglandin H synthase‐1.
Clinical Pharmacology & Therapeutics (1998) 63, 672–681; doi:
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