Doubly Labeled Water Is a Validated and Verified Reference Standard in Nutrition Research

ABSTRACT Thirty-seven steroids have been studied as orally effective inhibitors of ovulation in the mated oestrus rabbit. Norethisterone served as the reference standard and a dose response curve was established between the 0.31 and 1.25 mg dose levels. Nine highly active anti-ovulatory compounds are described listed in a decreasing order of potency with norethisterone having the arbitrary value of one: 6-chloro-Δ6-dehydro-17α-acetoxyprogesterone (35), 6α-methyl-Δ1-dehydro-17α-acetoxyprogesterone (≥ 10), 6-fluoro-Δ6-dehydro-17α-acetoxyprogesterone(9), 6-methyl-Δ6-dehydro-17α-acetoxyprogesterone (5), Δ6-dehydro-17α-acetoxyprogesterone (≥ 3), 6α-methyl-17α-acetoxyprogesterone (2.6), 6-chloro-Δ1,6-bisdehydro-17α-acetoxyprogesterone (≥ 2), 2-hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one (≥ 2), and 6α-fluoro-16α-methyl-17α-acetoxyprogesterone (≥ 1.25). The anti-ovulatory activity of a compound was not related necessarily to the progestational activity of a compound nor to the anti-gonadotrophic activity as measured in parabiotic rats. 6-Chloro-Δ60dehydro-17-acetoxyprogesterone was as effective by gavage as previously shown by subcutaneous injection. 2-Hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one was at least 2.5 times more active by gavage than by injection. While 17α-acetoxyprogesterone was a very weak anti-ovulatory steroid, modifications of the structure by addition of methyl or halogen at the 6α position with or without unsaturation greatly increased the activity. 6-Chloro-Δ6-dehydro-27α-acetoxyprogesterone was the most active compound in this series showing a relative potency of 3500 times that of the parent compound 17α-acetoxyprogesterone.

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BIOASSAY CHARACTERISTICS OF INDIVIDUAL URINARY GONADOTROPHIN EXTRACTS

Acta Endocrinologica ◽

10.1530/acta.0.0420214 ◽

1963 ◽

Vol 42 (2) ◽

pp. 214-224

Author(s):

Raymond C. Mellinger ◽

Jalileh A. Mansour ◽

Richmond W. Smith

Keyword(s):

Reference Material ◽

Young Women ◽

Reference Standard ◽

General Acceptance ◽

Modifying Factors ◽

Large Numbers ◽

The World ◽

Quantitative Bioassay ◽

Different Parts ◽

Age And Sex

ABSTRACT A reference standard is widely sought for use in the quantitative bioassay of pituitary gonadotrophin recovered from urine. The biologic similarity of pooled urinary extracts obtained from large numbers of subjects, utilizing groups of different age and sex, preparing and assaying the materials by varying techniques in different parts of the world, has lead to a general acceptance of such preparations as international gonadotrophin reference standards. In the present study, however, the extract of pooled urine from a small number of young women is shown to produce a significantly different bioassay response from that of the reference materials. Gonadotrophins of individual subjects likewise varied from the multiple subject standards in many instances. The cause of these differences is thought to be due to the modifying influence of non-hormonal substances extracted from urine with the gonadotrophin and not necessarily to variations in the gonadotrophins themselves. Such modifying factors might have similar effects in a comparative assay of pooled extracts contributed by many subjects, but produce significant variations when material from individual subjects is compared. It is concluded that the expression of potency of a gonadotrophic extract in terms of pooled reference material to which it is not essentially similar may diminish rather than enhance the validity of the assay.

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https://researchopenworld.com/category/nutrition-research-and-food-science/

10.31038/nrfsj ◽

2020 ◽

Keyword(s):

Food Science ◽

Nutrition Research

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Cultural Relevance of a Fruit and Vegetable Food Frequency Questionnaire

Canadian Journal of Dietetic Practice and Research ◽

10.3148/66.4.2005.231 ◽

2005 ◽

Vol 66 (4) ◽

pp. 231-236 ◽

Cited By ~ 3

Author(s):

Judy Paisley ◽

Marlene Greenberg ◽

Jess Haines

Keyword(s):

Food Frequency Questionnaire ◽

Dietary Assessment ◽

Cultural Relevance ◽

Assessment Tools ◽

Comparative Approach ◽

Fruit And Vegetable ◽

Food Frequency ◽

Research And Practice ◽

Vegetable Food ◽

Nutrition Research

Purpose: Canada’s multicultural population poses challenges for culturally competent nutrition research and practice. In this qualitative study, the cultural relevance of a widely used semiquantitative fruit and vegetable food frequency questionnaire (FFQ) was examined among convenience samples of adults from Toronto’s Cantonese-, Mandarin-, Portuguese-, and Vietnamesespeaking communities. Methods: Eighty-nine participants were recruited through community-based organizations, programs, and advertisements to participate in semi-structured interviews moderated in their native language. Data from the interviews were translated into English and transcribed for analysis using the constant comparative approach. Results: Four main themes emerged from the analysis: the cultural relevance of the foods listed on the FFQ, words with multiple meanings, the need for culturally appropriate portionsize prompts, and the telephone survey as a Western concept. Conclusions: This research highlights the importance of investing resources to develop culturally relevant dietary assessment tools that ensure dietary assessment accuracy and, more important, reduce ethnocentric biases in food and nutrition research and practice. The transferability of findings must be established through further research.

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