The effects of acid exposure on the ion regulation and seawater adaptation of coho salmon (Oncorhynchus kisutch) parrs and smolts

Smolts exhibited decreases in plasma Na+ levels after 7 days and lower Na+, K+-ATPase activities 14 days after acid exposure. Parrs exhibited decreased plasma Na+ after 24 hr acid exposure. Plasma Na+ increased and Na+, K+-ATPase decreased in smolts after transfer to seawater. Parrs exhibited increased plasma Na+ as well as Na+, K+-ATPase activity immediately after transfer to seawater. It was concluded that acid exposure prior to entry into seawater was detrimental to coho salmon with regard to the length of acid exposure and stage of development. A possible mechanism by which fish die from acid stress is inhibition of gill Na+, K+-ATPase concomitant with decreases in plasma Na+ levels.     

The effect of pH and/or calcium-enriched freshwater on gill Ca2+-ATPase activity and osmotic water inflow in rainbow trout (Salmo gairdneri)

Rainbow trout (Salmo gairdneri) were exposed to pH 5.0-5.1, 6.6 and/or calcium-enriched freshwater for 14 days. Hematocrit, gill Ca2+-ATPase enzyme activities, gill osmotic water inflow, plasma calcium and osmolarity were measured. No significant changes in plasma calcium ion levels were found. The typical increase in hematocrit usually associated with exposure of fish to acidified water was not found in the present study and is discussed. Plasma osmolarity decreased in fish exposed to calcium-enriched freshwater (60 mg Ca2+ X 1(-1) ) in comparison to fish exposed to control freshwater conditions (2 mg Ca2+ X 1(1) ), irrespective of the pH level. Gill Ca2+-ATPase enzyme activities were measured for both low affinity (3 mM Ca2+) and high affinity (100 microM) activity. Exposure of rainbow trout to low pH (pH 5.0-5.1) did not affect the specific activity of Ca2+-ATPase enzyme. However, low affinity Ca2+-ATPase activity in fish exposed to calcium-enriched freshwater did show a significant reduction. The increase in gill osmotic water permeability in fish exposed to calcium-enriched freshwater is interpreted as a result of the increase in osmolarity of the ambient media.     

Proposed follow up programme after curative resection for lower third oesophageal cancer

Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy.