Abrogation of the radiation-induced G2 checkpoint by the staurosporine derivative UCN-01 is associated with radiosensitisation in a subset of colorectal tumour cell lines

Ionising radiation is commonly used in the treatment of colorectal cancer. Tumour cells with mutant p53 undergo cell cycle arrest at G2/M after ionising radiation and evidence suggests that abrogation of this G2 arrest can lead to a premature, aberrant mitosis, thus enhancing ionising radiation-induced cell killing. The G2 checkpoint inhibitor UCN-01 was thus investigated to determine whether it would abrogate the G2 checkpoint induced by 5 Gy ionising radiation in a range of colorectal tumour cell lines. Data presented show that, at doses that are alone non-toxic to the cells, UCN-01 inhibits the ionising radiation-induced G2 checkpoint in five colorectal tumour cell lines with mutant p53. The ability of UCN-01 to sensitise cells to ionising radiation-induced growth inhibition and apoptosis was also investigated and UCN-01 was found to radiosensitise two out of five cell lines. These results were confirmed by long-term colony forming efficiency studies. These results demonstrate that abrogation of the ionising radiation-induced G2 checkpoint is not necessarily associated with sensitisation to ionising radiation, however, some colorectal tumour cell lines can be radiosensitised by UCN-01. Although the mechanism of radiosensitisation is not clear, this may still be an important treatment strategy

Biodiversity inventories in high gear: DNA barcoding facilitates a rapid biotic survey of a temperate nature reserve

Comprehensive biotic surveys, or ‘all taxon biodiversity inventories’ (ATBI), have traditionally been limited in scale or scope due to the complications surrounding specimen sorting and species identification. To circumvent these issues, several ATBI projects have successfully integrated DNA barcoding into their identification procedures and witnessed acceleration in their surveys and subsequent increase in project scope and scale. The Biodiversity Institute of Ontario partnered with the rare Charitable Research Reserve and delegates of the 6th International Barcode of Life Conference to complete its own rapid, barcode-assisted ATBI of an established land trust in Cambridge, Ontario, Canada

The molecular logic of endocannabinoid signalling

The endocannabinoids are a family of lipid messengers that engage the cell surface receptors that are targeted by Δ9-tetrahydrocannabinol, the active principle in marijuana (Cannabis). They are made on demand through cleavage of membrane precursors and are involved in various short-range signalling processes. In the brain, they combine with CB1 cannabinoid receptors on axon terminals to regulate ion channel activity and neurotransmitter release. Their ability to modulate synaptic efficacy has a wide range of functional consequences and provides unique therapeutic possibilities. © 2003, Nature Publishing Group. All rights reserved

An analogue CMOS front-end for a D2-MAC TV decoder

This paper describes the analog front-end of a fully integrated CMOS TV decoder, suitable for the reception of terrestrial as well as satellite signals, based on the D2-MAC transmission system. While the video reconstruction is undertaken using DSP, the front-end subsystem incorporates many linear and non-linear analog functions, including amplitude measuring, AGC, clamping, data slicing, clock recovery and of course, A/D conversion for the MAC signal processing. The chip is fabricated in 1-u CMOS, and operates from a single 5-V supply

Muhamed İkbal in Aşk Görüşü

This paper presents the design of an experimental first-order modulator with 4 quantization, fabricated in a 1.5-um space-qualified radiation-hard partially depleted sapphire (SOS) digital CMOS process. This converter architecture has been chosen investigation into the design of a range of common analog functions with two key one of technology and one environmental. First, both the architecture and the circ optimized using a variety of unconventional techniques to account for the influence bias-dependent, radiation-induced threshold-voltage shifts of up to 1V, as well as noise. Second, the circuitry is specially adapted to accommodate the floating-body type of process, wherein drain conductance varies considerably with drain bias and design techniques are directly applicable to very large-scale-integration silicon-on-design, where similar device phsics are encountered. Notwithstanding the severe the design, the fabricated circuit provides 9.7 bits of dynamic range in a 63-kHz si only degrading to 9.1 bits after 23 Mrad(Si) of total dose radiation