T Nation

It's an Abstract Number-How Many Grams?


#1

Can someone please tell me if they know how many grams they're talking about?

  1. Quadriceps muscle protein synthetic rate has been determined in healthy subjects in the post-absorptive (n = 18) and fed (n = 10) states and in patients with a variety of myopathies, by analysis of the enrichment of serial muscle biopsies taken during primed continuous infusion of L-[1-13C]leucine.

  2. Quadriceps protein synthetic rates in normal subjects were (mean +/- SD) 0.046 +/- 0.012 and 0.075 +/- 0.014%/h in the post-absorptive and fed states respectively. These results are significantly lower than we previously reported (M. J. Rennie et al., Clinical Science, 1982, 63, 519-523 [1]) but show the same relative differences of direction and magnitude, confirming the effects of feeding previously reported.

In patients with muscular dystrophy, muscle protein synthetic rate was, as previously reported [1], much lower in the fed state than in normal subjects. A new finding is that for patients with myotonic dystrophy the rate is also depressed in the post-absorptive state.

  1. We suggest that the present estimates in post-absorptive and fed normal subjects be used as reference values for quadriceps mixed muscle protein synthetic rate...

#2

Doesn't say


#3

It is probably a typographical problem.

At least one of the articles I've coauthored which has an abstract on Pubmed has a typographical problem of a symbol not being properly converted, and I've seen many other instances.

In other words, what appears as a percent sign, probably is not that in the actual article.


#4

Looks like it's reported in percent per hour. Is it percent based on bodyweight? Hard to tell without seeing the article.


#5

I suppose that could be. But it seems to me peculiar because, percent what?

It could be percent of the weight of the biopsied muscle tissue (but not I think bodyweight.) If that's a routine practice in the field, then okay, it could be understandable that they failed to to specify what the percentage is of. But it strikes me as weird. I still would tend to bet on a typographical conversion problem, but you could be right.


#6

I think i got what i was looking for thanks dudes

Myofibrillar protein synthesis in young and old men
S. Welle, C. Thornton, R. Jozefowicz and M. Statt
Department of Medicine, University of Rochester, New York 14620.

We tested the hypothesis that healthy older men (> 60 yr old) have a slower rate of myofibrillar protein synthesis than young men (< 35 yr old). Myofibrillar protein synthesis was determined by the in vivo incorporation of L-[1-13C]leucine into myofibrillar proteins obtained by muscle biopsy. Subjects were eight young (21-31 yr) and eight older (62-81 yr) men, all healthy and moderately active.

There was no significant difference in the mean height and weight of the two age groups, but the older group had 12% less lean body mass (determined by 40K counting) and 21% less muscle mass (estimated by urinary creatinine excretion). Upper leg strength was approximately one-third lower in the older subjects according to isokinetic dynamometry. The fractional rate of myofibrillar protein synthesis was 28% slower in the older group (0.039 +/- 0.009 vs. 0.054 +/- 0.010 %/h, mean +/- SD, P < 0.01).

Total myofibrillar protein synthesis, estimated as total myofibrillar mass (from creatinine excretion) times the fractional synthesis rate, was 44% slower in the older group (1.4 vs. 2.5 g/h, P < 0.001). Whole body protein synthesis, assessed as the difference between leucine disappearance rate and leucine oxidation, was marginally slower (8%, P = 0.10) in the older group, but not when the data were adjusted for lean body mass.

Myofibrillar protein synthesis was a smaller fraction of whole body protein synthesis in the older group (12 vs. 19%). Reduced myofibrillar protein synthesis may be an important mechanism of the muscle atrophy associated with aging.


#7

Yes, that does show that it is a known practice to state percent in this matter without mentioning what it is a percent of, from expectation that other workers in that same research would know what is meant. Apparently, percent of weight of the biopsied sample.