Shark cartilage contains inhibitors of tumor angiogenesis
by Lee, A. and Langer, R. 1983
Science 221:1185-7 (A peer-reviewed scientific journal)
Certain tissues such as cartilage are resistant to vascular invasion, yet no single tissue-derived molecule that can inhibit angiogenesis has been reported. A protein derived from cartilage was purified that inhibits angiogenesis in vivo and capillary endothelial proliferation and migration in vitro in three separate bioassays. This protein is also an inhibitor of mammalian collagenase. These findings may help elucidate the mechanism by which neovascularization is controlled in both normal and pathological states.
As you can see from this passage, these articles often contain a lot of complex terminology specific to a particular field. Scientists in the field have no difficulty understanding the terminology, but it can be very daunting to nonspecialists. Let's see what this abstract says in plain English (corresponding statements in the abstract are given in parentheses).
Some tissues such as cartilage do not allow blood vessels to grow into them (vascular invasion), yet there have been no reports in the scientific literature identifying a protein molecule taken from living tissue (tissue-derived) that can prevent the growth of blood vessels (inhibit angiogenesis). The authors of the paper purified a protein from cartilage (a protein derived from cartilage was purified). This protein prevents the growth of blood vessels in tissue in living organisms (in vivo), prevents the growth of the cells that line capillaries (capillary endothelial proliferation), and prevents the movement (migration) of these cells into other areas. The scientists used living cells that were not in a living organism (in vitro) to test the effect of the protein on growth and migration of the cells that line capillaries. The three different tests conducted by the scientists involved three different measures with living cells (bioassays). The protein decreases the ability of the enzyme collagenase from breaking down collagen. The results from this study may help scientists determine how the growth of new blood vessels (neovascularization) is controlled in both normal states and states associated with diseases (pathological).
Here is a section of the methods from the paper:
Capillary endothelial cells...were plated onto gelatin-coated 96-well tissue culture dishes (Nunc) on day 1. On day 2, cells were fed with Dulbecco's modified Eagle's medium (Gibco) with 5% calf serum (Hyclone) (DMEM/5) and aFGF (10 ng/ml) (FGF company), and increasing concentrations of freshly purified CDI.
As you have probably gathered from this passage, nonscientists would have a very difficult time evaluating the methods used in this study. Indeed, most scientists not working in the field addressed by the paper would have a difficult time evaluating the methods used!
Nonetheless, you may need to consult papers such as these to determine for yourself the validity of statements made by others referencing the primary literature. For example, consider the following statements made by I. William Lane when interviewed with Richard A. Passwater:
It is believed that all of the antiangiogenic factors in shark cartilage are proteins. In late 1992, two separate proteins, both with major antiogenicproperties have been identified, one, by Dr. Robert Langer, and a second, by Japanese researchers.
Lane implies (either purposefully or inadvertently that the protein identified by Langer came from shark cartilage. In fact, the study referenced in the interview and being discussed here was conducted with "...bovine scapular cartilage...." The word "bovine" means "of, or pertaining to, cattle." Thus, without examining the original paper, you might reach an erroneous conclusion about the effectiveness of shark cartilage in curing cancer.
If you need to consult the primary literature, you will be most successful if you do a lot of background reading in less technical sources (e.g., review articles, textbooks) and keep a dictionary handy.