Use of histological samples for assessing skeletal calcium.

Bone samples were decalcified using 5% formic acid. Their calcium content was then quantified by analysing the calcium extracted in the decalcification solution. This was correlated with matched samples digested in hydrochloric acid. No significant differences were found. This indicates that bone biopsy specimens taken for histological analysis can be used for the direct assessment of skeletal calcium. The method can therefore simplify investigations into metabolic bone diseases and provide a direct correlation between skeletal calcium and bone histology.

Hair chromium concentrations in adult insulin-treated diabetics.

Hair chromium concentrations have been measured in age- and sex-matched groups of insulin-treated diabetics and normal controls. Average concentration (+/- S.E.M.) was reduced in female (2.9 +/- 0.5 compared with 5.1 +/- 0.7 nmol/g) but not in male diabetics.

The relation between plasma unconjugated oestriol and cystine aminopeptidase concentrations and uterine contractions.

The relation between maternal plasma unconjugated oestriol (E3) concentrations and uterine activity was investigated by very frequent, carefully timed determinations of E3 during synchronously recorded uterine contractions in six normal subjects. There was an initial rise (10 to 50 per cent above the mean) in E3 levels reaching a peak coincident with the contraction peak (range 20 seconds before to 15 seconds after) followed by a fall of similar magnitude below the mean reaching a nadir about 80 seconds (range 60 to 105 seconds) after the contraction peak. Although the pattern of E3 fluctuation was most marked in labour the overall degree of variation was no greater than at other times. Cystine aminopeptidase (CAP) concentrations in the same serum samples showed no significant correlation with uterine contractions. The reasons for, and practical applications of, the E3 results are discussed.

Plasma unconjugated oestriol and unconjugated oestradiol-17 beta in late pregnancy: individual fluctuation of concentrations from day to day and every 10 minutes.

Plasma unconjugated oestriol (E3) and unconjugated oestradiol-17 beta (E2) were determined by radioimmunoassay. In ten normal women in their last month of pregnancy the individual fluctuation of E3 concentrations (mean of the coefficients of variation, CV) from day to day (over 5 days) was 15.6% (range 6.4--26.2%). The individual fluctuation of E2 determined in eight of these women was 16.9 (10.4--25.5) %. In six of the same women who had blood samples collected every 10 min (for 3 h) the individual fluctuation of E3 concentrations was 13.8 (7.0--25.1) %, and of E2 was 16.1 (11.3--26.0) %. The degree of fluctuation of E3 in individuals was in proportion to the mean concentration, unlike E2, suggesting that in clinical practice individual changes in E3 values would be as easy to interpret at low levels as at high levels. The finding that concentrations of plasma unconjugated E3 fluctuate in individuals no more than for E2 or than reported for total E3, and less than reported for 24-h urinary oestrogens, lends practical support to the theoretical preference for the assay of plasma unconjugated E3 to assess fetoplacental function.

Plasma unconjugated oestriol in late pregnancy: circadian variation and the effect of meals and a glucose load.

Plasma unconjugated oestriol (E3) concentrations were determined by radioimmunoassay in 10 normal subjects in late pregnancy, throughout a normal day and night, and after a 50 g oral glucose load. There was a circadian pattern in E3 concentration characterized by an abrupt increase of 15 per cent at night. There was no significant rhythm during the day or night, taken separately. However there was a 10 to 11 per cent reduction in E3 concentrations soon after some meals and after a glucose load, possibly due to expansion of the plasma volume. Excluding the effect of meals, the fluctuation of E3 concentrations in individuals (median of the coefficients of variation) was 11.5 per cent in the day. Overall, it was 13.2 per cent in the day, 12.1 per cent at night and 15.9 per cent over the whole period studied. Since the variation in plasma unconjugated E3 concentrations through 24 hours was no greater than random fluctuations or day-to-day variation there is no need to restrict the time of blood sampling in clinical practice.