Will the "MattLB" types now admit they are wrong?
- From: monty1945@xxxxxxxxx
- Date: Mon, 12 Nov 2007 21:15:51 -0800
In another thread, a "critic" posted a study that he/she thought
"proved" that the "EFA" claim is correct, despite it being directly
refuted in the 1940s. This was a study about how a cell dealt with a
particular kind of artificial diet. It was so absurd that at least I
got a good laugh out of it, but it set these people up for a "hard
fall." The problem for them is logic at its most basic level. That
is, if you are going to assert that a certain kind of study is very
important, and in this case, definitive, what happens when another
such study contradicts the one you cited? Logic dictates that you
have to "eat" some "humble pie," but this is not something "MattLB"
and the like will ever do, apparently. And that raises the question
about why they even post here, on a scientific forum, when they seem
so ignorant about the scientific method. Here are two studies
contradicting the one posted by MattLB (I think it was him/her, but
I'm not going to do a lot of searching to determine which "critic" it
was, specifically):
J Lipid Res. 1992 Nov;33(11):1719-26.
An in vitro model for essential fatty acid deficiency: HepG2 cells
permanently maintained in lipid-free medium.
Furth EE, Sprecher H, Fisher EA, Fleishman HD, Laposata M.
Department of Pathology and Laboratory Medicine, Hospital of the
University of Pennsylvania, Philadelphia 19104.
A stable essential fatty acid-deficient cell type, known as HepG2-EFD,
was derived from the lipoprotein-producing human hepatoma cell line
HepG2. These cells are particularly useful for quantitative studies
involving essential fatty acids (n-6 and n-3 fatty acids) in secreted
lipoproteins. Radiolabeled essential fatty acids can be delivered to
these cells without altering the specific activity of the fatty acids,
since the deficient cells contain no endogenous essential fatty acids.
Using these cells, radioactivity data (dpm) from metabolic studies can
be converted directly to mass, and masses as low as a few pmoles can
be accurately measured. HepG2-EFD cell cultures were established by
growing HepG2 cells in medium containing delipidated serum. After 10
days of growth in delipidated medium, HepG2 cells were completely
depleted of all essential fatty acids. Compensatory increases in
nonessential fatty acids (n-9 and n-7 fatty acids) including 20:3n-9
(the Mead acid), which is the hallmark fatty acid of essential fatty
acid deficiency, were also observed in HepG2-EFD cells. Despite the
lack of exogenous fatty acids in the medium and the lack of essential
fatty acids in the cells, export of very low density lipoprotein
(VLDL)-associated apolipoprotein B by HepG2-EFD was the same as
observed for parent HepG2 cells. However, the activity of beta-
oxidation of fatty acids in HepG2-EFD cells was much lower than in the
parent cell line.(ABSTRACT TRUNCATED AT 250 WORDS)
PMID: 1464755
J Invest Dermatol. 1992 Dec;99(6):703-8.
In vitro model of essential fatty acid deficiency.
Marcelo CL, Duell EA, Rhodes LM, Dunham WR.
University of Michigan Medical School, Department of Dermatology, Ann
Arbor 48109-0528.
The polyunsaturated fatty acids linoleic acid (18:2, n-6) and
arachidonic acid (20:4, n-6) are essential for normal skin function
and structure, both as eicosanoid precursors and as components of
lipids forming cell membranes. Adult human keratinocytes grow
optimally in serum-free medium (MCDB 153) that contains no fatty
acids. These keratinocytes expand rapidly and produce normal epidermis
upon in vivo grafting. Analysis of lipid extracts of epidermis and of
cultured keratinocytes was done to determine the fatty acid
composition of cells grown in essential fatty acid (EFA)-deficient
medium. Gas chromatography and high-performance liquid chromatography
analyses were done of the fatty acids in the entire cell and in a thin-
layer chromatography separated fraction containing those lipids that
form cellular membranes. Comparison of snap-frozen epidermis and
epidermal basal cell suspensions to passage 1 to 4 cultures shows that
the cells are in an extreme essential fatty acid-deficient state by
the first passage. The amount of the saturated fatty acids 16:0, 18:0,
and 14:0 is unchanged by culture. The polyunsaturated fatty acids are
found to be significantly decreased, the cells balancing their lack
with a significant increase in the relative abundance of the
monounsaturated fatty acids, 18:1 and 16:1. Greater than 85-90% of the
fatty acids was found in lipids associated with membranes and no
unusual fatty acids were detected. Because the serum-free medium is
fatty acid free and the cells cannot synthesize essential fatty acids,
the rapid division of the cells results in the predominance of an
extreme EFA-deficient cell type. The essential fatty acid-deficient
keratinocyte is an excellent adult, normal epidermal cell model that
can be used to study EFA deficiency and the effect of the eicosanoid
and fatty acids on cell function and structure.
PMID: 1469285
.
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