Effects of in-vitro fertilization, culture, freezing and transfer on the ability of mouse embryos to implant and survive

The survival after transfer of frozen-thawed mouse blastocysts obtained from culture of in-vitro fertilized oocytes or 1- and 2-cell ova was compared. About 10% of transferred embryos developed to term in each group and there was no difference between embryos fertilized in vitro or in vivo. In addition to embryonic loss due to transfer, in-vitro cultivation and freezing reduced the proportion of fetuses considered viable at Day 15 of pregnancy (29.8 versus 50.7% and 26.3 versus 50.7% respectively). When used together these procedures had an additive effect on fetal wastage (18.4 versus 50.7%). In-vitro culture also entailed a significant increase of resorbing implantation sites (10.2 versus 4.3%). The re-expansion rate after freezing and thawing of blastocysts grown in vitro was paradoxically greater than that of blastocysts grown in vivo (85.8 versus 54.6%).

Induction of implantation in the rat by intraparametrial injection of uterine RNA from oestrogen-treated animals

Crude RNA preparations from uteri of oestradiol-treated rats induced the implantation of delayed blastocysts when injected into the parametrium of ovariectomized pregnant rats. Treatment of donor animals with labelled oestradiol showed that this effect could not be due to contamination of the RNA extracts by oestradiol. RNase digestion of these extracts suppressed their capacity to induce implantation. Purified poly (A)-rich RNA from oestrogen-treated uteri failed to elicit implantation although it was capable of increasing epithelial height when repeatedly injected into uterine horns of ovariectomized rats. These results suggest that uterine RNA synthesis might somehow mediate the effects of oestrogen in causing implantation and that RNAs other than messenger RNA might be involved.

Increased serum thyroglobulin levels in patients with nontoxic goiter

Thyroglobulin (Tg) levels were found to be elevated in 30 to 35 patients with euthyroid sporadic goiter and in 15 of 37 patients with euthyroid endemic goiter. The elevated Tg levels in the goitrous patients did not correlate with either goiter size, TSH levels, or urinary iodine excretion, but did correlate with the triiodothyronine to thyroxine ratio. It was concluded, therefore, that in both sporadic and endemic euthyroid goiters, factors other than goiter size and TSH, such as hypoiodination of Tg may be responsible for the elevated Tg secretion.

Serum thyrotrophin determination on day 5 of life as screening procedure for congenital hypothyroidism

In 327 newborns cord blood thyroxine (T4) was 11.8 +/- 0.4 mug/100 ml (SEM) (151.9 +/- 5.1 nmol/l), and serum thyrotrophin (TSH) 6.7+/-1.0 muU/ml. Variability was marked for both T4 and TSH. Remeasured in the same patients on the fifth day of life, the TSH level was 3.7 +/- 1.0 muU/ml, lower than at birth (P less than 0.001), while scattering of TSH values was much smaller, with 99.4 % of values less than 12 muU/ml...

Adverse effect of amniofetography on fetal thyroid function

Amniofetography is a valuable tool for the diagnosis of fetal malformations. This technique is being used routinely in pregnancies carrying a high risk of external fetal malformations. There are very few published data concerning the effect of radiopaque dyes, containing large amounts of iodide, on fetal thyroid function. We have performed serial determinations of serum thyrotropin and thyroxine in seven newborn infants to assess the effect of amniofetogrpahy on fetal thyroid function. This work demonstrates that amniofetography induces a transient impairment of fetal thyroid function.

Paradoxical modulation of thyrotrope responsiveness to TRH during the treatment of thyrotoxic patients: apparent absence of feed-back regulation

Eight patients with active thyrotoxicosis have been followed up to one year after the onset of antithyroid treatment. At different time intervals during the investigation period, TRH tests were performed and total T4 and T3 basal levels were measured. The TRH-induced TSH release was delayed in all patients in spite of a normalization of the circulating levels of thyroid hormones. The delay varied according to the patients and lasted, in some cases, for as long as 24 weeks after the normalization of the thyroid hormone levels. Administration of thyroid hormones, together with methimazole, did not seem to prevent the pituitary thyrotropes responsiveness; moreover, it did not provoke an inhibition of the TRH-induced TSH release once the thyrotropes reactivity was fully restored. The feed-back mechanism does not seem to be the main modulator of the pituitary responsiveness to TRH in these circumstances.

Sequential study of the impairment of thyroid function in the early stage of subacute thyroiditis

A sequential study of various parameters of thyroid metabolism has been carried out in 2 patients during the weeks following the clinical onset of subacute thyroiditis, the aim being to define the nature and extent of the anomalies of thyroid function. In the early stage, serum thyroxine, protein bound iodine and T3 resin uptake levels were in the thyrotoxic range. In both cases, the serum thyroxine values further decreased with a half-life of 7 days and reached the hypothyroid range at the 6–7th week. Both 131I uptake and TSH plasma levels were found to be low and concomitantly rose at the 6–7th week. In one patient the serum thyroglobulin level was strikingly elevated at the beginning and then fell fairly rapidly; however in both patients, the serum thyroglobulin values remained abnormal. The present study confirmed the concept of a sudden release of preformed hormone stores. Furthermore, the following points were evident: a) marked and transient release of thyroglobulin; b) interruption of the secretory activity during at least 7 weeks; c) adequate functioning of the pituitary-thyroid control mechanism and d) partial recovery of the thyroidal iodine uptake at a time when the hormone secretion was still undetectable.

Modifications of thyroid function induced by chronic administration of iodide in the presence of "autonomous" thyroid tissue

Fourteen patients were studied before and during administration of a daily supplement of 0.5 mg of iodide over a period of 3 to 10 months. Only a slight increase in PBI was observed in three patients with a non-toxic goitre and in two myxoedematous patients under treatment.

The same supplements of iodine induced a marked rise in PBI in four euthyroid patients with a typical thyroid »hot« nodule. In the four cases, the PBI values reached the thyrotoxic range after only a few weeks. These elevated values were maintained throughout the period of iodine administration; data for the thyroxine content of the serum were strictly correlated with the PBI values. The T3-resin test measurements also gave values characteristic of hyperthyroidism. Later on, three of these patients developed definite symptoms of hyperthyroidism, although not until several months after the appearance of the biological picture.

Finally a definite increase in PBI was also observed, albeit to a lesser extent, in five thyrotoxic patients previously treated with radioiodide or with methimazole. A progressive fall in the PBI was found in four patients after iodine supplements were discontinued.

These observations indicate that chronic iodine supplementation leads to marked over-production of thyroid hormones in two pathological conditions characterized by the presence of autonomous thyroid tissue. It is concluded that, in the absence of an adequate feed-back control mechanism, the amount of dietary iodine may be one of the main regulatory factors involved in thyroid activity in human subjects.