Search results for "Lawson"

Lawsone derivatives target the Wnt/β-catenin signaling pathway in multidrug-resistant acute lymphoblastic leukemia cells.

2017

Abstract Multidrug resistance (MDR) represents a serious problem in cancer treatment. One strategy to overcome this obstacle is to identify agents that are selectively lethal to MDR cells. The aim of this study was to discover novel compounds against MDR leukemia and to determine the molecular mechanisms behind collateral sensitivity. A library of 1162 compounds was tested against parental, drug-sensitive CCRF-CEM cells using the resazurin assay. A total of 302 compounds showed reasonable activity (less than 50% cell viability). Eleven out of 30 lawsone derivatives revealed considerable collateral sensitivity in MDR P-glycoprotein (Pgp)-overexpressing CEM/ADR5000 cells. They reduced β-caten…

Origin of potassic postcollisional volcanic rocks in young, shallow, blueschist-rich lithosphere

2020

Unusually high Th/La in K-rich orogenic rocks may indicate shallow blueschist-rich sources in accretionary settings.

Crystal structure of SrMn2(Si2O7)(OH)2 H2O, a new mineral of the lawsonite type

1992

Crystal with the composition SrMn 2 [Si 2 O 7 ](OH) 2 .H 2 O were found in a sugilite, serandite-pectolite rich sample from the Wessels Mine, Kalahari, South Africa. The crystal structure of the nex compound with space group Cmcm, a = 6.255(1), b = 9.034(2), c = 13.397(2) A, Z = 4 was determined from X-ray single-crystal data (R = 0.048). The structure is of the lawsonite type where Al is completely replaced by Mn 3+ and Ca by Sr. [Mn 3+ O 6 ] octahedra forming edge-sharing chains parallel to a exhibit a Jahn-Teller distortion with four short and two long Mn 3+ -O distances. Sr is in eight-fold coordination and H 2 O is disordered on a split position. Together with orientite, macfallite, ru…

Baltic Journal of English Language, Literature and Culture, N 6

2016

Geochemical characteristics of lawsonite blueschists in tectonic mélange from the Tavşanlı Zone, Turkey: Potential constraints on the origin of Medit…

2019

Constraints on the sources of post-collisional K-rich magmatism: The roles of continental clastic sediments and terrigenous blueschists

2017

Abstract The possible role of continental sediments in the generation of potassium-enriched lavas of the Alpine-Himalayan belt depends on their melting behaviour either during subduction or during post-collisional relaxation. Although usually classed as orogenic lavas, these volcanic rocks may result from re-melting of newly formed mantle lithosphere 30–40 million years after collision ends, and can thus be considered as the first stage of intraplate volcanism. The potassic component in these volcanics is characterized by a high Th/La signature for which there are two competing explanations: melting of subducted continental clastic sediments, and the involvement of lawsonite blueschists in …

Site-selectivity control in hetero-Diels-Alder reactions of methylidene derivatives of lawsone through modification of the reactive carbonyl group: a…

2019

A new perspective on the reactivity of hydroxyquinones was revealed as an acetal derivative of lawsone was synthesized, isolated, and used in tandem Knoevenagel/hetero-Diels-Alder reactions catalyzed by S-proline. The intermediate alkylidene-1,3-diones that were formed in situ reacted with electron rich alkenes to predominantly afford pyrano-1,2-naphthoquinone (β-lapachone) derivatives along with the isomeric pyrano-1,4-naphthoquinone (α-lapachone) derivatives in high to excellent total yields. Interestingly, the highly reactive arylidene-1,3-dione derivatives were found to be stable and isolable. DFT calculations suggest that these hetero-Diels-Alder reactions have a high polar character, …

1,4-Naphthoquinones as inducers of oxidative damage and stress signaling in HaCaT human keratinocytes.

2010

Selected biological effects of 1,4-naphthoquinone, menadione (2-methyl-1,4-naphthoquinone) and structurally related quinones from natural sources--the 5-hydroxy-naphthoquinones juglone, plumbagin and the 2-hydroxy-naphthoquinones lawsone and lapachol--were studied in human keratinocytes (HaCaT). 1,4-naphthoquinone and menadione as well as juglone and plumbagin were highly cytotoxic, strongly induced reactive oxygen species (ROS) formation and depleted cellular glutathione. Moreover, they induced oxidative DNA base damage and accumulation of DNA strand breaks, as demonstrated in an alkaline DNA unwinding assay. Neither lawsone nor lapachol (up to 100 microM) were active in any of these assay…

Matemaattinen formalismi taloustieteessä : Tony Lawsonin ja Deirdre McCloskeyn uusklassisen taloustieteen metodologian analyysit

2012

Tutkielmassani tarkastelen modernissa taloustieteessä valta-asemassa olevan uusklassisen koulukunnan metodologiaa ja sen teoreettisia taustaoletuksia kahden huomattavimmista uusklassisen taloustieteen kriitikoista, Tony Lawsonin ja Deirdre McCloskeyn, projektien, kriittisen realismin ja taloustieteen retoriikan, kautta. Tarkoituksenani on löytää heidän uusklassisen metodologian kritiikkinsä oleelliset piirteet ja tarkastella sitä, missä määrin ne ovat yhteneviä, missä määrin toisilleen vastakkaisia ja missä määrin taas toisiaan täydentäviä. Ensimmäisessä osassa tarkastelen toisaalta Lawsonin ja McCloskeyn teorioden taustaoletuksia, heidän ontologisia ja epistemologisia/metodologisia näkemyk…