Biological gradient

Chen CJ, Yang HI, Su J, Jen CL, You SL, Lu SN, Huang GT, Iloeje UH (2006) Risk of hepatocellular carcinoma across a biological gradient of serum hepatitis B virus DNA level. JAMA 295(l) 65-73... 

Wang, C.-H., Jeng, J.-S., Yip, P.-K. el al. (2002) Biological gradient between long-term arsenic exposure and carotid atherosclerosis. Circulation, 105(15), 1804-9. 

Bledsoe, E.L., and Phlips, E.J. (2000) Relationships between phytoplankton standing crop and physical, chemical, and biological gradients in the Suwannee river and plume region, USA. Estuaries 23, 458-473. 

A spectrum of host responses should follow exposure to the hypothesized agent along a logical biologic gradient from mild to severe. 

Criteria similar to those listed by Adams (2003) are used to establish causality and are derivatives of Koch s postulates and Hume s criteria. The list includes (1) strength of association, (2) consistency of association, (3) specificity of association, (4) time order or temporality, (5) biological gradient over space and time, (6) experimental evidence available, and (7) biological plausibility. In many instances, especially at a regional scale and over long periods of time, meeting the requirements for each of these criteria can be difficult. 

Presence of a biological gradient A positive correlation between the stressor and response. 

There is a biological gradient that is the result of a strong correlation between the exposure and the outcome. 

Biologic gradient - is there evidence of dose- or duration-related risk ... 

Biological gradient. Basically, dose—response relationships exist. The toxic response can be direct, inverse, or simply inducible by some substance s presence. 

Adverse Effect Consistency Specificity S Temporality Biological Gradient (Dose—Response) Coherence Strength Plausibility Experimental Analogy... 

The biological gradient (dose—response) criterion can also be readily answered in the affirmative. Two points in appraising the enumerated toxic effects are that (1) the persistence of the dose—response relationships span relatively wide exposure ranges in many cases, e.g., neurotoxicity. 

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