Precipitin reactions of anti-human myoglobin serum with several human and animal muscle extracts

Myoglobin content of several human muscles was determined immunologically. The content of cardiac and skeletal muscle was similar. There was no antigenic difference noted between cardiac and skeletal muscle myoglobin. Uterine smooth muscle contained no myoglobin.

Details of the precipitin reaction between human myoglobin and its antiserum are presented. There may be approximately three regions on the human myoglobin molecule which acted as antigenic sites in a rabbit.

Several animal muscle extracts cross-reacted with the anti-human myoglobin. All primate skeletal muscle samples tested were equally potent, while beef, rodent and chicken thigh muscle extracts were poorer cross-reactors. It is postulated that these differences were due to differences in the myoglobin molecules of these species. Chicken breast muscle did not cross-react, and appeared to be deficient in myoglobin.

A quantitative study of the effects of progesterone and related steroids on the uterus:plasma concentration ratio for radioactive iodide in the rat

Optimal conditions for determining the quantitative effect of a single subcutaneous injection of progesterone in oil on the uterus:plasma concentration ratio for radioactive iodide were found to be measurement of this ratio 24 hr. after the injection of steroid in rats ovariectomized 7–10 days previously. Under these conditions there is a linear regression of response on log dose over the range of 156–2500 μg. progesterone.

Reduction of the 20-ketone group or the 4–5 double bond, introduction of 17α- or 21-hydroxyl groups or of an 11-oxo group into the molecule reduces the activity in this test. Steroids with predominantly glucocorticoid, androgenic or oestrogenic activity do not produce this response. The relative potencies of a variety of synthetic steroids derived from progesterone or 19-nortestosterone have been assessed. The results obtained in this test appear to be more closely related to the ability to maintain pregnancy than are those obtained in the usual assays for progestational activity. It is suggested that the uterus:plasma 131I ratio response could be made the basis of an accurate and potentially useful assay method for steroids with progestational properties.

Lysosomal enzymes and vitamin E deficiency. II. Gestation-resorption in the rat

1. Activities of β-glucuronidase, β-galactosidase, acid phosphatase and cathepsin were measured in the uterine contents of normal rats during gestation and of vitamin E-deficient rats during foetal resorption.

2. β-Glucuronidase activity reached a peak value on days 11 and 12, falling to lower values by day 14. Deficient rats showed slightly greater mean values than normal rats on days 11 and 12, but not after that time.

3. Vitamin E deficiency did not affect the activities of β-galactosidase, acid phosphatase and cathepsin, all of which showed a slow decrease during pregnancy.

4. The supernatant fraction of homogenates of uterine contents from deficient rats showed increased β-glucuronidase and β-galactosidase activity from day 14 to 17, suggesting some degree of rupture of the lysosomal membrane.

5. β-Glucuronidase and acid phosphatase activities were raised in the uteruses of some deficient rats towards the end of pregnancy, but serum β-glucuronidase was unaffected.

6. Changes in lysosomal hydrolases were not so marked during gestation–resorption as in some other vitamin E deficiency states, such as muscular dystrophy in the chick and rabbit.

Localization of 131-I-labelled antibody to relaxin

An antibody to relaxin labelled with 131I was injected into pregnant mice and rats. It was found to be localized in the ovaries, placenta, and uterus of the mouse. The localization in the ovary and placenta was apparent on day 10 of pregnancy, increased markedly to a plateau on days 14–15, and fell at parturition. In the uterus accumulation of 131I anti-relaxin antibody rose to a much smaller degree than in the other two tissues and fell before parturition. Analysis of rat tissues during pregnancy indicated a localization of the labelled antibody in the ovary, placenta, cervix and mammary gland. The localization of the antibody was competitively inhibited by simultaneous injection or preincubation with relaxin. The localized antibody was competitively extracted by saline solutions containing relaxin but not by saline alone.