324 research outputs found

    Gravity survey of the Mt. Toondina impact structure, South Australia

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    The Mt. Toondina impact structure is located in northern South Australia, about 45 km south of the town of Oodnadatta. Only the central uplift is exposed. The outcrops at Mt. Toondina reveal a remarkable structural anomaly surrounded by a broad expanse of nearly flat-lying beds of the Bulldog Shale of Early Cretaceous age. A gravity survey was undertaken in 1989 to determine the diameter of the impact structure, define the form of the central uplift, and understand the local crustal structure. Data were collected along two orthogonal lines across the structure. In addition to the profiles, a significant number of measurements were made on and around the central uplift. The 1989 gravity data combined with 1963 gravity data and the seismic reflection data provide an excellent data base to interpret the subsurface structure of the Mt. Toondina feature

    Synthesis, antiproliferative activity, and mechanism of action of a series of 2-{[2E]-3-phenylprop-2-enoylamino}benzamides

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    Several new 2-{[2E]-3-phenylprop-2-enoylamino}benzamides 12a-s and 17t-v were synthesized by stirring in pyridine the (E)-3-(2-R1-3-R2-4-R3-phenyl)acrylic acid chlorides 11c-k and 11t-v with the appropriate anthranilamide derivatives 10a-c or the 5-iodo anthranilic acid 13. Some of synthesized compounds were evaluated for their in vitro antiproliferative activity against the full NCI tumor cell line panel derived from nine clinically isolated cancer types (leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate and breast). COMPARE analysis, effects on tubulin polymerization in cells and with purified tubulin, and effects on cell cycle distribution for 17t, the most active of the series, indicate that these new antiproliferative compounds act as antitubulin agent

    Lunar Simple Crater Impact Melt Volumes

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    Impact melt is observed in simple lunar craters having diameters as small as less than 200 m. The presence of ponds of impact melt on the floor of such small craters is interpreted to indicate vertical impacts. Data from the LRO LROC and LOLA experiments allow quantitative estimates of the volume of impact melt in simple crater. Such estimates allow for validation of theoretical models of impact melt generation and examination of target effects. Preliminary data have considerable scatter but are broadly consistent with the models

    Role of cannabinoids in the treatment of Tinnitus

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    Tinnitus is a frequent symptom in audiological clinical practice characterized by an abnormal noise perceived in one or both ears or in the head, in which a patient has a conscious hearing percept in absence of external sound. Tinnitus might be caused by a homeostatic response of central dorsal cochlear nucleus auditory neurons that makes them hyperactive in compensation to auditory input loss. One hypothesis suggests that tinnitus is a sensory form of epilepsy that involves the cochlear nucleus and the inferior colliculus, which display impairment in the electrical activity in the auditory system. This alteration determines a synaptic plasticity in the dorsal cochlear nucleus that becomes a target for pharmacological compounds able to treat tinnitus. There is no effective drug treatment for tinnitus, but different studies propose the use of cannabinoid receptors agonist for their anti-epileptic activity, although their practical effects are still unclear. In this review, we want to analyze the emerging pharmacological approaches of cannabinoid receptor agonists to the therapy of tinnitus

    Acetaldehyde effects in the brain

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    The effects of alcohol have been widely studied during the past century as alcohol abuse is a major health problem in Western society. In the last years, a growing body of evidence indicates that acetaldehyde, the first oxidation product of ethanol, is one of the mediators of peripheral and central effects of ethanol. Indeed, acetaldehyde has been recently taken into account as the mediator of the rewarding properties of alcohol. The role of acetaldehyde in ethanol-related properties has been proved by enzymatic manipulation studies in which the inactivation of acetaldehyde potentially synthesized in the brain produces the same results as blocking the formation of acetaldehyde by inhibiting brain catalase activity. Moreover, electrophysiological and pharmacological analyses showed that acetaldehyde is able to stimulate dopamine release in the nucleus accumbens through enhancement of firing rate, spikes/burst, and burst firing of ventral tegmental neurons. Thus, the aim of this review is to summarize latest results on the role of acetaldehyde as the mediator of ethanol-central effects

    Impact Melt in Small Lunar Highlands Craters

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    Impact-melt deposits are a typical characteristic of complex impact craters, occurring as thick pools on the crater floor, ponds on wall terraces, veneers on the walls, and flows outside and inside the rim. Studies of the distribution of impact melt suggested that such deposits are rare to absent in and around small (km to sub-km), simple impact craters. noted that the smallest lunar crater observed with impact melt was approximately 750 m in diameter. Similarly, theoretical models suggest that the amount of melt formed is a tiny fraction (<1%) of the total crater volume and thus significant deposits would not be expected for small lunar craters. LRO LROC images show that impact-melt deposits can be recognized associated with many simple craters to diameters down to approximately 200 m. The melt forms pools on the crater floor, veneer on the crater walls or ejecta outside the crater. Such melt deposits are relatively rare, and can be recognized only in some fresh craters. These observations indicate that identifiable quantities of impact melt can be produced in small impacts and the presence of such deposits shows that the material can be aggregated into recognizable deposits. Further, the present of such melt indicates that small craters could be reliably radiometrically dated helping to constrain the recent impact flux

    Suppression of survivin phosphorylation on Thr34 by flavopiridol enhances tumor cell apoptosis

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    Survivin is a member of the inhibitor of apoptosis gene family that is expressed in most human cancers and may facilitate evasion from apoptosis and aberrant mitotic progression. Here, exposure of breast carcinoma MCF-7 or cervical carcinoma HeLa cells to anticancer agents, including Adriamycin, Taxol, or UVB resulted in a 4-5-fold increased survivin expression. Changes in survivin levels after anticancer treatment did not involve modulation of survivin mRNA expression and were independent of de novo gene transcription. Conversely, inhibition of survivin phosphorylation on Thr(34) by the cyclin-dependent kinase inhibitor flavopiridol resulted in loss of survivin expression, and nonphosphorylatable survivin Thr(34)--\u3eAla exhibited accelerated clearance as compared with wild-type survivin. Sequential ablation of survivin phosphorylation on Thr(34) enhanced tumor cell apoptosis induced by anticancer agents independently of p53 and suppressed tumor growth without toxicity in a breast cancer xenograft model in vivo. These data suggest that Thr(34) phosphorylation critically regulates survivin levels in tumor cells and that sequential ablation of p34(cdc2) kinase activity may remove the survivin viability checkpoint and enhance apoptosis in tumor cells
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