Parathyroid hormone secretion: effect of estradiol and progesterone

Previous studies have shown that estrogen therapy in postmenopausal women results in an increase in serum immunoreactive parathyroid hormone (iPTH) levels. It has been assumed that this effect of estrogen on PTH secretion is indirect, being mediated via mild hypocalcemia resulting from an inhibition of bone resorption. We evaluated the direct effect of 17 beta-estradiol (E2) and of progesterone (Prog) on secretion of PTH from bovine parathyroid tissue in vitro. Both E2 and Prog caused a significant stimulation of PTH secretion within one hour, which was progressive for the three-hour observation period. The responses were dose-related from 10(-7) to 5 X 10(-10) mol/L. There was no PTH response to 10(-7) mol/L alpha-E2, 3-methoxy estriol, estrone, testosterone, or 20-alpha-hydroxy progesterone, indicating specificity of the responses to E2 and Prog. There was a minimal PTH secretory response to 10(-6) mol/L cortisol and 10(-6) mol/L estrone. The E2 receptor antagonist tamoxifen did not inhibit the E2 effect on PTH secretion. This observation plus the rapid PTH response suggests that this hormonal effect may not be via the conventional intracellular E2 receptor. Therefore, E2 and Prog can stimulate PTH secretion by rapid, direct, and specific effects on parathyroid cells. These gonadal hormones may, therefore, be important in calcium homeostasis via their direct stimulatory effect on PTH secretion.

Effects of estradiol and progesterone on calcitonin secretion

Estrogen therapy has been used to inhibit bone resorption and prevent osteoporosis in postmenopausal women. Previous studies have disagreed as to whether the mechanism of estrogen action involves stimulation of calcitonin (CT) secretion. We evaluated the direct effects of 17 beta-estradiol (E2) and progesterone (Prog) on CT secretion from the thyroid C cells of 8-day-old rats in vitro. Both E2 and Prog caused a significant stimulation of CT secretion within 1 h, which was progressive for the 3-h observation period. The responses were dose related from 10(-7) to 5 X 10(-10) M. There was no CT response to 10(-7) M alpha-estradiol, estriol, 3-methoxyestriol, estrone, testosterone, or 20 alpha-hydroxyprogesterone, indicating specificity of the responses to E2 and Prog. There was a minimal CT secretory response to 10(-6) M cortisol. The E2 receptor antagonist tamoxifen did not inhibit the E2 effect on CT secretion. This observation plus the rapid CT response suggest that this hormonal effect may not be via the conventional intracellular E2 receptor. Therefore, E2 and Prog can stimulate CT secretion by rapid, direct, and specific effects on the thyroid C cell. The gonadal hormones may, therefore, be important in inhibiting bone resorption via their direct stimulatory effect on CT secretion.

Precipitation of fibrinogen, fibrinogen degradation products and fibrin monomer by histone H3

Incubation of histone H3 with normal citrated plasma resulted in the formation of insoluble aggregates, as determined by turbidity measurements. The precipitate was subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis, confirming that fibrinogen was a major component. Purified fibrinogen precipitated rapidly as determined with turbidity experiments and experiments with radioiodinated protein. The amount of fibrinogen precipitation was strongly dependent on H3 concentration. Variation of ionic strength (0.2-0.84) and pH (5.3-7.4), however, had little or no effect on the reaction. Fibrinogen subjected to gelatin-Sepharose chromatography or dialysis against 3.3M urea reacted equivalently with H3. Precipitation of 125I-fibrinogen by H3 was strongly favored by increasing temperature (4 degrees-45 degrees C). Precipitation of fibrinogen by protamine was maximized by decreasing the temperature. In addition, formation of insoluble fibrinogen-protamine aggregates was highly dependent on ionic strength and pH, suggesting that different types of protein-interaction are involved in the two studied precipitation reactions. Of the fibrinogen degradation products, only fragment X precipitated significantly when incubated with H3. Radioiodinated fibrin monomer also precipitated when incubated with H3 in solutions of sufficient ionic strength to prevent spontaneous polymerization. The extent of precipitation was equivalent for fibrin monomer and fibrinogen. Fragment D inhibited the precipitation of fibrinogen by H3 or protamine. These studies indicate that the proteins termed "paracoagulants" are not all equivalent and that the hydrophobic domain of H3 plays a critical role in fibrinogen precipitation.

Tracheal agenesis and associated malformations: a comparison with tracheoesophageal fistula and the VACTERL association

Tracheal agenesis is a rare malformation of the lower respiratory tract. Investigation of a patient with multiple congenital anomalies and tracheal agenesis prompted a review of the literature which uncovered 42 previously published cases, most of whom had other defects. The presence in our patient of a tracheal abnormality in association with radial hypoplasia, single umbilical artery, tetralogy of Fallot, and left hydroureter initially suggested presence of the VACTERL association. However, numerical classification of malformation patterns in the reported patients with tracheal agenesis and in a series of patients with tracheoesophageal fistula and other components of the VACTERL association suggests that tracheal agenesis does not occur in the VACTERL association and may be part of another pattern of malformations which includes laryngeal atresia, complex congenital heart anomalies, radial ray defects, and duodenal atresia.

Chondro-osseous changes in Cerebro-Oculo-Facial-Skeletal (COFS) syndrome

Radiological and pathological findings were described in three cases of COFS syndrome. Early diagnosis of this syndrome is possible by the recognition radiologically of the characteristic proximal displacement of second metatarsals and pathologically by the extensive cell necrosis in the iliac crest biopsy. Pathological findings, including the presence of nuclear bodies in chondrocytes and amianthoid fibres surrounding necrotic cartilage cells, are compatible with a primary degenerative/deformative disorder. The aetiology of this syndrome is unknown.

Acute respiratory failure following severe arsenic poisoning

A 47-year-old man had an episode of severe respiratory failure after acute intoxication with arsenic. Features of the initial clinical presentation included nausea, vomiting, and diarrhea, acute psychosis, diffuse skin rash, and marked pancytopenia. A peripheral neuropathy then developed which resulted in severe weakness of all muscles of the limbs, the shoulder and pelvis girdles, and the trunk. The neuropathy continued to progress despite treatment with dimercaprol (BAL in oil). Five weeks after the initial exposure, the patient was no longer able to maintain adquate ventilation and required mechanical ventilatory support. Improvement in the patient's neuromuscular status permitted successful weaning from the ventilator after one month of mechanical ventilation. Long-term follow-up revealed no further respiratory difficulty and slow improvement in the strength of the peripheral muscles.

Two levels of inferential behavior in young children

5- and 6-year-old children made inferences about the spatial locations of animals and people in a series of 3 experiments. The tasks employed manipulable models to represent the spatial relations involved and were made as simple as possible. 2 levels of inferential behavior were found. The first constituted the ability to draw an inference consistent with information given, but with minimal understanding of the way in which inferences can assist in decisions between alternative outcomes. At the second level, children succeeded in discriminating inferences which were logically necessary from those which were merely consistent with the premises. Most 5-year-olds were at the first level, most 6-year-olds at the second level. 2 criteria for the identification of young children's behavior as inferential were established, and the results of the present study were discussed in terms of recent related work with both younger and older children.