Search results for "pine"

Synthesis and Dopamine Receptor Selectivity of the Benzyltetrahydroisoquinoline, (R)-(+)-nor-Roefractine

1998

(R)-(+)-nor-Roefractine (1) was synthesized by the Bischler-Napieralski route, using asymmetric reduction of the 1, 2-didehydro precursor imine with sodium (S)-N-CBZ-prolinyloxyborohydride. Compound 1 was able to displace [3H]-raclopride (a D2 dopamine receptor-selective ligand) from its specific binding sites in rat striatum with selectivity vs [3H]-SCH23390 (D1 dopamine receptor-selective ligand).

Synthesis and monoamine uptake inhibition of conformationally constrained 2β-carbomethoxy-3β-phenyl tropanes

2009

A series of 2beta-carbomethoxy-3beta-phenyl tropanes with conformationally constrained nitrogen substituents were synthesized as potential selective dopamine transporter ligands. These novel compounds were examined for their monoamine uptake inhibition potency at the human dopamine transporter (hDAT), the human serotonin transporter (hSERT) and the human noradrenalin transporter (hNET), stably expressed in human embryonic kidney cells (HEK). A SAR-study was conducted to determine the contribution of extended, 4-fluorinated, conformationally constrained C4 chains at the tropane nitrogen to human monoamine transporter affinity and selectivity.

α-Adrenoceptor Interaction of Tetrandrine and Isotetrandrine in the Rat: Functional and Binding Assays

1998

Abstract The action of 1S,1′S-tetrandrine, a bisbenzyltetrahydroisoquinoline alkaloid, on α1-adrenoceptors has been compared with that of its isomer 1R,1′S-isotetrandrine. The work includes binding assays to analyse the affinity of these products for the [3H]prazosin binding site of rat cerebral cortical membranes and functional studies on rat isolated aorta to examine the effects of both alkaloids on intracellular calcium processes related or not to α-adrenoceptor activation. A radioligand receptor-binding study showed that both compounds interacted with the α1-adrenoceptors displacing [3H]prazosin from the specific binding site. The Ki values (inhibition constants) were 0.69±0.12 and 1.6±…

Synthesis, benzodiazepine receptor binding and molecular modelling of isochromeno[4,3-c]pyrazol-5(1H)-one derivatives

2012

Abstract A series of isochromeno[4,3-c]pyrazole-5(1H)-one derivatives 7b–h were prepared and tested at 10 μM for their ability to displace specific [3H]flunitrazepam from bovine brain membranes. The substitution pattern of the above derivatives was shown to influence the receptor affinity. The most active compound of the series was 7e, showing a 54% inhibition of [3H]flunitrazepam binding. Compounds 7a–d,i were compared with the known isomers chromeno[4,3-c]pyrazole-4(1H)-ones 14a–d,i, showing that the isochromene/chromene isomerism influences the activity.

Behavioural stress reactivity in handling naive and handling-habituated adult male rats prenatally exposed to different benzodiazepine receptor agoni…

2001

Fine–grained spinel ferrites: From the reactivity to magnetic properties

1998

The oxidation at low temperature of fine-grained ferrites containing oxidizable cations such as Cu + , Fe 2+ , Mn 2+ , Mo 3+ , V 3+ , has led to new mixed-valent cation deficient ferrites with a large number of vacancies. It has been demonstrated by DTG analysis that each cation oxidizes at a specific temperature in close relation with the cation-oxygen distance. The kinetics oxidation of each oxidizable cation has been explained on the basis of a diffusion-induced stress effect when these stresses are generated by the chemical gradient induced during the oxidation process. When fine-grained ferrites contain some Co-cations, it has been revealed that the stresses have a significant influenc…

Changes in the cerebrovascular effects of endothelin-1 and nicardipine after experimental subarachnoid hemorrhage.

1993

The role of endothelium-related factors in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH) has gained interest since the discovery of endothelin-1 (ET-1). We have examined, before and after SAH, the responsiveness of the cerebrovascular bed of the goat to ET-1, the sources of Ca2+ in ET-1-induced responses, and the ability of the Ca2+ entry blocker nicardipine to counteract them. Before SAH, injection of ET-1 into the cerebral circulation increased cerebrovascular resistance, thereby producing dose-dependent reductions in cerebral blood flow (CBF), which were prevented by nicardipine. In isolated middle cerebral arteries, ET-1 induced concentration-dependent contr…

Freezing without surrounding cryomedium preserves the endothelium and its function in human internal mammary arteries

2005

Abstract Purpose Cryopreserved human blood vessels may become important tools in bypass surgery. Optimal cryopreservation of an arterial graft should, therefore, preserve both histological and physiological characteristics of smooth muscle and endothelium comparable to the unfrozen artery. Methods Rings from human internal mammary arteries (IMA) were investigated in vitro either unfrozen or after immersion into a cryomedium (RPMI 1640 containing 1.8 M Me2SO and 0.1 M sucrose) and cryostorage with and without surrounding medium. Results In unfrozen IMA, neither contractile responses to noradrenaline (NA) nor endothelium-dependent relaxant responses to acetylcholine (ACH) was modified after e…

Plant trait‐environment relationships in tundra are consistent across spatial scales

2023

Patterns and processes shaping ecosystems vary across spatiotemporal scales. As plant functional traits reflect ecosystem properties, investigating their relationships with environment provides an important tool to understand and predict ecosystem structure and functioning. This is particularly important in the tundra where a changing climate may trigger severe alterations in plant communities as both summer and winter conditions are changing. Here, we investigate the relationships between key environmental drivers including summer temperature, snow persistence, topographic position and soil pH, and species height, specific leaf area (SLA) and seed mass as plant traits. The study is carried…

Reliability of Short-Term Heart Rate Variability Indexes Assessed through Photoplethysmography

2018

The gold standard method to monitor heart rate variability (HRV) comprises measuring the time series of interbeat interval durations from electrocardiographic (ECG) recordings. However, due to the widespread use, simplicity and usability of photoplethysmographic (PPG) techniques, monitoring pulse rate variability (PRV) from pulse wave recordings has become a viable alternative to standard HRV analysis. The present study investigates the accuracy of PRV, measured as a surrogate of HRV, for the quantification of descriptive indexes computed in the time domain (mean, variance), frequency domain (low-to-high frequency power ratio LF/HF, HF band central frequency) and information domain (entropy…