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Magnetic anisotropy measurements are becoming increasingly common to many studies within the different disciplines of geology, involving sedimentary, igneous and metamorphic rocks. A plethora of techniques exists for measuring magnetic anisotropy of rocks. Some are rapid and non-destructive while others are more labor-intensive or may result in alteration of the magnetic minerals. All, however, have the potential of revealing a wealth of information when measured and interpreted correctly. In broad terms, anisotropy techniques subdivide into measurements of susceptibility, remanence and torque; here we consider the first two of these. Anisotropy of magnetic susceptibility (AMS) is by far the most utilized, and measures composite fabrics. Magnetic susceptibilities in high fields and low temperatures, however, are being increasingly used to isolate the paramagnetic contribution to the fabrics. When distinguishing between fabrics carried by different ferromagnetic phases, or to separate these from the diamagnetic and paramagnetic contributions to the fabric, then remanence anisotropy techniques become necessary. Anisotropies of thermal remanence (ATRMs), of anhysteretic remanence (AARM) and of isothermal remanence (AIRM) are the most common examples. Remanence anisotropy may be measured over the full spectrum of magnetic coercivities or over a targeted range (e.g. partial or ApARM). Moreover, anisotropies may be calculated using only the resolved field-parallel component of the vector, in which case a minimum of six different orientations is necessary to obtain a complete symmetric tensor, or using the three components (full vector) of the measured magnetic vectors (e.g. AvARM), in which case three orthogonal applied magnetizations are the minimum requirement. In this study we utilize a variety of magnetic remanence room temperature techniques to measure remanence anisotropy of selected coarse and finer grained gneiss-granulitic specimens with well-pronounced fabrics. Results are compared to room temperature AMS and are interpreted in terms of the applicability of instrumentation/technique to specific rock-magnetic properties. [ABSTRACT FROM AUTHOR]

Abstract: Parkinson''s disease (PD) is characterised by the loss of dopaminergic neurones in the substantia nigra (SN) but the pathogenic mechanism remains unknown. Cell death involves oxidative stress and inflammatory mechanisms, and these may be altered by the actions of the glycosylated phosphoprotein osteopontin (OPN). OPN is present in the rat SN, but its presence in human and non-human primate brain has not been extensively studied. Both OPN mRNA and protein were present in the normal marmoset SN, and OPN protein was localised to nigral neurones although these were not dopaminergic cells and it was not present in glial cells. In contrast, OPN protein was found in dopaminergic neurones in the normal human SN but again not in glial cells with some accumulation in the extracellular matrix. Following MPTP treatment of common marmosets, OPN protein expression was decreased, although its mRNA levels were unchanged and it was not present in either activated microglia or astrocytes. In the SN in PD, OPN protein expression was decreased in the remaining dopaminergic neurones and it was present in activated microglia but not in astrocytes. This was not specific to PD as OPN protein expression was also decreased in the SN in multiple system atrophy and progressive supranuclear palsy with an identical localisation of the protein. The presence of OPN in the normal human and non-human primate SN coupled to its decreased expression following nigral cell degeneration suggests that it may play an important role in dopaminergic neurone survival. [Copyright &y& Elsevier]

Abstract: Adenosine A2a receptor antagonists may represent a novel non-dopaminergic approach to the treatment of Parkinson''s disease. However, there is little information available on their ability to reverse motor deficits in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine hydrochloride (MPTP)-treated primates. We have studied the effects of the novel A2a receptor antagonist 2-butyl-9-methyl-8-(2H-1,2,3-triazol 2-yl)-9 H-purin-6-ylamine (ST1535) alone and in combination with l-3, 4-dihydroxyphenylalanine (l-DOPA) in MPTP-treated common marmosets. ST1535 (10, 20 and 40 mg/kg, p.o.) when administered alone to MPTP-treated common marmosets produced a dose related increase in locomotor motor activity and tended to reverse motor disability. Treatment with a threshold dose of l-DOPA (2.5 mg/kg, p.o.) produced an increase in locomotor activity and again tended to reverse motor disability. When l-DOPA (2.5 mg/kg, p.o.) was administered in combination with ST1535 (20 mg/kg, p.o.), there was an enhancement in the intensity and duration of the effect of l-DOPA (2.5 mg/kg, p.o.) in reversing motor deficits as shown by both a further increase in locomotor activity and reversal of motor disability. The combination of l-DOPA (2.5 mg/kg, p.o.) plus ST1535 (20 mg/kg, p.o.) significantly increased “on time” in these animals. These data substantiate the evidence that adenosine A2a receptor antagonists are able to reverse motor deficits in a highly predictive model of clinical efficacy in Parkinson''s disease. The data suggests that ST1535 will be an effective anti-parkinsonian agent in combination with l-DOPA and allow a reduction in l-DOPA usage in the treatment of Parkinson''s disease. [Copyright &y& Elsevier]

Abstract: An interaction between brain serotonergic and dopaminergic systems involving 5-HT1B receptors may contribute to motor complications arising from the drug treatment of neurological and psychiatric disorders. This study assessed the effects of treatment with a non-selective 5-HT1B/D receptor agonist and a selective 5-HT1B receptor antagonist on akinesia induced in marmosets by long-term treatment with haloperidol and on motor disability and l-3, 4-dihydroxyphenylalanine (l-DOPA)-induced dyskinesia in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated marmosets. In marmosets treated chronically with haloperidol, the 5-HT1B agonist SKF-99101-H reduced locomotor activity and induced motor disability, whereas the 5-HT1B antagonist SB-224289-A had no effect on motor behaviour. Haloperidol administration induced a suppression of locomotor activity which was not reversed by co-administration of either SKF-99101-H or SB-224289-A. In MPTP-treated common marmosets, neither SKF-99101-H nor SB-224289-A induced any significant change in motor function. However, SKF-99101-H inhibited l-DOPA-induced dyskinesia and the reversal of motor deficits whereas SB-224289-A was without effect. The results of this study indicate that the 5-HT1B receptor appears not to be an appropriate target for the treatment of Parkinson''s disease (PD) or for the control of drug-induced motor complications developed as a tong-term consequence of neuroleptic or l-DOPA treatment. [Copyright &y& Elsevier]

• Triassic limestones in eastern Tibet record three episodes of remagnetization. • The oldest is carried by authigenic magnetite after pyrite oxidization. • The second resides in authigenic hematite after further pyrite oxidization. • The latest is viscous overprint in magnetite and chemical remanence in pyrrhotite. • Rock magnetic and petrographic tests are key to identify carbonate remagnetization. Carbonate rocks, widely used for paleomagnetically quantifying the drift history of the Gondwana-derived continental blocks of the Tibetan Plateau and evolution of the Paleo/Meso/Neo-Tethys Oceans, are prone to pervasive remagnetization. Identifying remagnetization is difficult because it is commonly undetectable through the classic paleomagnetic field tests. Here we apply comprehensive paleomagnetic, rock magnetic, and petrographic studies to upper Triassic limestones in the eastern Qiangtang block. Our results reveal that detrital/biogenic magnetite, which may carry the primary natural remanent magnetization (NRM), is rarely preserved in these rocks. In contrast, authigenic magnetite and hematite pseudomorphs after pyrite, and monoclinic pyrrhotite record three episodes of remagnetization. The earliest remagnetization was induced by oxidation of early diagenetic pyrite to magnetite, probably related to the collision between the northeastern Tibetan Plateau and the Qiangtang block after closure of the Paleo-Tethys Ocean in the Late Triassic. The second remagnetization, residing in hematite and minor goethite, which is the further subsurface oxidation product of pyrite/magnetite, is possibly related to the development of the localized Cenozoic basins soon after India-Asia collision in the Paleocene. The youngest remagnetization is a combination of thermoviscous and chemical remanent magnetization carried by authigenic magnetite and pyrrhotite, respectively. Our analyses suggest that a high supply of organic carbon during carbonate deposition, prevailing sulfate reducing conditions during early diagenesis, and widespread orogenic fluid migration related to crustal shortening during later diagenesis, have altered the primary remanence of the shallow-water Tethyan carbonate rocks of the Tibetan Plateau. We emphasize that all paleomagnetic results from these rocks must be carefully examined for remagnetization before being used for paleogeographic reconstructions. Future paleomagnetic investigations of the carbonate rocks in orogenic belts should be accompanied by thorough rock magnetic and petrographic studies to determine the origin of the NRM. [ABSTRACT FROM AUTHOR]

Abstract: Low-field magnetic susceptibility has been widely used to determine the pedostratigraphy of the Chinese loess/paleosol sequences. However, uncertainties remain in correlating between the loess magnetic susceptibility and the marine oxygen isotope records because susceptibility variations are affected by both global and local paleoclimatic changes. To provide a more sound paleoclimatic interpretation of magnetic susceptibility variations, age models across Marine Oxygen Isotope Stage (MIS) 5 for the Jiuzhoutai (JZT) and Yuanbao (YB) sections, western Chinese Loess Plateau, were constructed through an integrated approach by linking the major pedostratigraphic boundaries of the loess profiles to the SPECMAP oxygen isotope curve, and by correlating relative magnetic paleointensity records with both the SINT800 global paleointensity stack from marine sediments and 36Cl records from the GRIP ice core. Results indicate good correlation of SIRM60mT (a residual remanence of saturation isothermal remanent magnetization after a 60mT alternating field demagnetization) variations between these two sites, which agree well with fluctuations in subtropical Atlantic sea surface temperatures. All cooling events recorded by ice-core and Atlantic marine sediments within MIS5 have counterparts in SIRM60mT. SIRM60mT is partially controlled by the degree of low-temperature oxidation, which is strongly temperature dependent. However, strong pedogenesis can decrease SIRM60mT due to further oxidation of partially oxidized magnetites above some critical points. Therefore, we propose that SIRM60mT is best suited to record paleotemperature changes in loess profiles from the western Chinese Loess Plateau, where pedogenesis is the weakest. Furthermore, by inter-profile correlation between the YB and JZT sections, we note that the seemingly uniform sub-paleosol unit with a broad susceptibility peak (previously assigned to MIS5c) between ∼34.4 and ∼37.4m in the YB profile actually consists of two independent units (lower part of S1L1/MIS5b and S1S2/MIS5c). This indicates that susceptibility values can be strongly affected by local factors (e.g., mainly precipitation). Therefore, beside the simplistic traditional paleoclimatic interpretation of variations in loess susceptibility involving only cold/dry and warm/humid scenarios, cold/humid and warm/dry scenarios should also be considered. [Copyright &y& Elsevier]

Nonspecific monoamine reuptake inhibitors reverse motor abnormalities in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated marmosets without evoking established dyskinesia. However, it is not known whether dopamine reuptake inhibition alone explains these actions or whether noradrenaline and/or serotonin reuptake blockade also contributes. l-DOPA (12.5 mg/kg, p.o.) rapidly reversed the baseline locomotor deficits and motor disabilities, but evoked dyskinesia (especially limb chorea) in MPTP-treated common marmosets primed to exhibit involuntary movements. In contrast, the selective dopamine reuptake inhibitor 1-(2-(bis-(4-fluorophenyl)-methoxy)ethyl)-4-(3-phenylpropyl) piperazine dihydrochloride (GBR 12909) reversed motor deficits in a dose-dependent manner but, unlike l-DOPA, did not evoke established dyskinesia in these animals. Therefore, inhibition of dopamine reuptake does not evoke established dyskinesia in MPTP-treated primates. [Copyright &y& Elsevier]

Abstract: Olivine is an abundant orthosilicate in the solar system, in the upper mantle of rocky planets, in meteorites and interstellar dust. The magnetic properties of (Fe x , Mg1− x )2 SiO4 olivines result from the silicate matrix and its iron-rich inclusions and have not always been separated in previous studies. The properties of the matrix are important to understand mantle rocks'' anisotropy and their deformation, both in xenoliths and peridotite massifs, while the inclusions are potential paleomagnetic and paleointensity recorders. In this study, we performed new measurements on 7 natural and 23 synthetic ferromagnesian olivines, covering the whole range from forsterite Mg2SiO4 (Fo100) to fayalite Fe2SiO4 (Fo0) and from 4 to 310 K. Many of our specimens contain ferromagnetic inclusions (magnetite or maghemite), with magnetic sizes ranging from superparamagnetic to multidomain. The respective contributions of the matrix and the inclusions are systematically isolated using magnetic fields large enough to saturate the ferromagnetic component due to inclusions. At room temperature, as predicted by molecular field theory, while the forsterite end-member is diamagnetic (X HF =−6.8 10−10 m3/kg) and the fayalite end-member is paramagnetic (X HF =1.10 10−6 m3/kg), their magnetic properties do not vary linearly with iron content. These olivines also exhibit one or two magnetic transitions at composition-dependent low temperatures. At the Néel temperature (T N), olivines exhibit a first magnetic transition from paramagnetic to antiferromagnetic behavior, indicated by negative paramagnetic Curie temperatures (θ). A second transition (T t) occurs at lower temperatures for specimens with x ≥0.1, and could be attributed to a change from collinear to canted antiferromagnetic state. In the range Fo83–Fo93, corresponding to the Earth''s upper mantle, the anisotropy of magnetic susceptibility (AMS) is directionally consistent, with the AMS principal axes K 1, K 2 and K 3 respectively corresponding to the a, c and b crystallographic axes. At room temperature, the degree of anisotropy increases from 1.028 to 1.302 with decreasing iron content. The presence of small and submicroscopic iron-rich inclusions significantly complicates the investigation of olivine physical properties but also constitutes opportunities to record paleomagnetic field intensities. [Copyright &y& Elsevier]

l -DOPA is the gold-standard pharmacotherapy for treatment of Parkinson's disease (PD) but can lead to the appearance of troubling dyskinesia which are attributable to 'false neurotransmitter' release of dopamine by serotonergic neurons. Reducing the activity of these neurons diminishes l -DOPA-induced dyskinesia (LID), but there are currently no clinically approved selective, high efficacy 5-HT 1A receptor agonists. Here we describe the effects of NLX-112, a highly selective and efficacious 5-HT 1A receptor agonist, on LID in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated marmosets, a non-human primate model of PD. NLX-112 exhibited modest plasma half-life (~2h) and marked plasma protein binding (96%). When administered to parkinsonian marmosets with l -DOPA (7 mg/kg p.o.), NLX-112 (0.025, 0.1 and 0.4 mg/kg p.o.) reduced LID scores at early time-points after administration, whilst only minimally interfering with the l -DOPA-induced reversal of motor disability. In contrast, the prototypical 5-HT 1A receptor agonist, (+)8-OH-DPAT (0.6 and 2 mg/kg p. o.), reduced LID but also abolished l -DOPA's anti-disability activity. Administered by itself, NLX-112 (0.1, 0.2 mg/kg p.o.) produced very little dyskinesia or locomotor activity, but reduced motor disability scores by about half the extent elicited by l -DOPA, suggesting that it may have motor facilitation effects of its own. Both NLX-112 and (+)8-OH-DPAT induced unusual and dose-limiting behaviors in marmoset that resembled 'serotonin behavioral syndrome' observed previously in rat. Overall, the present study showed that NLX-112 has anti-LID activity at the doses tested as well as reducing motor disability. The data suggest that additional investigation of NLX-112 is desirable to explore its potential as a treatment for PD and PD-LID. • l -DOPA-induced dyskinesia (LID) develops in many Parkinson's disease patients. • NLX-112 is a highly selective and high efficacy serotonin 5-HT 1A receptor agonist. • In MPTP-treated marmosets NLX112 reduced LID without impairing therapeutic activity. • NLX-112 by itself exhibited antiparkinsonian activity (decreased motor disability). • NLX-112 is a promising drug candidate for treatment of Parkinson's disease. [ABSTRACT FROM AUTHOR]