Spontaneous regression of human cancer cells in vitro: potential role of disruption of Cdk1/Cdk4 co-expression.

BACKGROUND: Although well-acknowledged in vivo, spontaneous death of cancer cells in vitro is less widely appreciated. MATERIALS AND METHODS: Colony formation was studied in untreated control plates of standard clonogenic assays and measurements of actual and potential doubling times performed in asynchronous cultures of human cancer cells lines. Western blotting of lung large cell carcinoma, COR-L23 cells actively undergoing spontaneous cell death was also carried out. RESULTS: Catastrophic disintegration of mature colonies could be seen in the untreated plates of lung large cell carcinoma, H460 and colon adenocarcinoma, SW620 human cancer cell lines and a significant cell loss factor was present in the cell lines growing as adherent cells in continuous culture. Western blotting demonstrated alterations of relative cyclin dependent kinase (Cdk)1 to Cdk4 protein expression in dying COR-L23 cells. CONCLUSION: The phenomenon of spontaneous cell death should be considered a hallmark of cancer and may be the result of failure to stabilise unstable, fully developed cancer cells due to the disruption of Cdk1/Cdk4 co-expression in those cells.

Comparison of radiolucent and fracture tables in the treatment of slipped capital femoral epiphysis.

A retrospective study was undertaken to see whether there was any difference in the time required and the accuracy of pin placement between slips pinned on a fracture table and those pinned on a radiolucent table. All patients were treated by single screw fixation of stable slipped capital femoral epiphysis (SCFE), 36 on a fracture table and 29 on a radiolucent table. Mean operating room time on the fracture table (63 minutes) was greater than that on the radiolucent table (51.2 minutes) (P <0.05). Mean surgery time for the fracture table (38.55 minutes) was greater than that on the radiolucent table (24.8 minutes) (P <0.05). The deviation of screw placement from the ideal for the two tables was not significantly different in the anteroposterior or lateral planes. The use of the radiolucent table, with manipulation of the limb to obtain lateral images of the hip, is a useful alternative to use of the fracture table for pinning of SCFE.

40Ar/39Ar dates from the West Siberian Basin: Siberian flood basalt province doubled.

Widespread basaltic volcanism occurred in the region of the West Siberian Basin in central Russia during Permo-Triassic times. New 40Ar/39Ar age determinations on plagioclase grains from deep boreholes in the basin reveal that the basalts were erupted 249.4 +/- 0.5 million years ago. This is synchronous with the bulk of the Siberian Traps, erupted further east on the Siberian Platform. The age and geochemical data confirm that the West Siberian Basin basalts are part of the Siberian Traps and at least double the confirmed area of the volcanic province as a whole. The larger area of volcanism strengthens the link between the volcanism and the end-Permian mass extinction.

Earth's biggest 'whodunnit': unravelling the clues in the case of the end-Permian mass extinction.

The mass extinction that occurred at the end of the Permian period, 250 million years ago, was the most devastating loss of life that Earth has ever experienced. It is estimated that ca. 96% of marine species were wiped out and land plants, reptiles, amphibians and insects also suffered. The causes of this catastrophic event are currently a topic of intense debate. The geological record points to significant environmental disturbances, for example, global warming and stagnation of ocean water. A key issue is whether the Earth's feedback mechanisms can become unstable on their own, or whether some forcing is required to precipitate a catastrophe of this magnitude. A prime suspect for pushing Earth's systems into a critical condition is massive end-Permian Siberian volcanism, which would have pumped large quantities of carbon dioxide and toxic gases into the atmosphere. Recently, it has been postulated that Earth was also the victim of a bolide impact at this time. If further research substantiates this claim, it raises some intriguing questions. The Cretaceous-Tertiary mass extinction, 65 million years ago, was contemporaneous with both an impact and massive volcanism. Are both types of calamity necessary to drive Earth to the brink of faunal cataclysm? We do not presently have enough pieces of the jigsaw to solve the mystery of the end-Permian extinction, but the forensic work continues.