Human chorionic gonadotropin-like substance in nonendocrine tissues of normal subjects.

By means of two assay systems, a beta chain human chorionic gonadotropin radioimmunoassay and a radioreceptor gonadotropin assay, a chorionic gonadotropin-like substance was demonstrated in extracts of liver and colon obtained at autopsy from three patients who died of nonneoplastic disease. In contrast to placental chorionic gonadotropin, colon and liver chorionic gonadotropin was not bound to concanavalin A-Sepharose columns, indicating that this substance possessed little or no carbohydrate. Previous workers demonstrated that desialylated human chorionic gonadotropin possesses little or no bioactivity in vivo but retains full radioreceptor and radioimmunoassay activity in vitro. Our data suggest that the genome responsible for the human chorionic gonadotropin production is not completely suppressed in adult nonendocrine tissues, and that the chorionic gonadotropin produced by colon and liver has little or no bioactivity in vivo because of its low carbohydrate content. Since many normal tissues produce chorionic gonadotropin, bioactivity may be modulated by regulation of carbohydrate content.

Pituitary gland: site of short-loop feedback for luteinizing hormone in the rabbit.

The development of a species specific radioimmunoassay for rabbit luteinizing hormone (LH) has permitted the direct demonstration of LH feedback control of LH secretion (short-loop feedback control). In previous studies we showed that small bolus injections of human LH (hLH) intravenously administered to castrate female rabbits suppressed rabbit LH for 20-30 min. Human LH had no effect on rabbit follicle-stimulating hormone secretion. This control system was responsive to amounts of hLH estimated to be present in blood of eugonadal men and women. These studies were designed to determine whether this feedback control was exerted at a pituitary or hypothalamic level. Two groups of studies were carried out: (a) in vivo studies: Rabbit LH was quantified in the blood of castrated female New Zealand White rabbits receiving either constant hLH perfusion (2.75 IU/min) or saline perfusion, plus a bolus injection of 0.5, 6, or 20 mug of gonadotropin-releasing hormone (GnRH). Human LH decreased the response to 6 and 20 mug of GnRH by 31 and 36%, respectively, and abolished the response to 0.5 mug, GnRH. (b) in vitro studies: Rabbit pituitary slices were incubated in the presence of medium alone, medium plus hLH (25 mIU/ml), medium plus GnRH (20 mug/ml), and medium plus both GnRH and hLH. hLH decreased basal rabbit LH release into the medium and abolished GnRH-stimulated rabbit LH release. hLH had no effect on rabbit follicle-stimulating hormone release. From these results we conclude that a direct and specific feedback control of LH on LH exists at a pituitary level.

Some effects of adrenalectomy in the fatty rat.

Function of the pituitary-adrenal axis was examined in lean and genetically obese fatty (Zucker) rats. The diurnal rhythms of plasma corticosterone and plasma ACTH were similar in both groups. The secretion of corticosterone by adrenal glands incubated in vitro with graded doses of ACTH was also comparable in lean and fatty rats. Adrenalectomy reduced food intake and weight gain in the fatty rats to levels similar to those in the lean animals and raised plasma ACTH to the same level. The injection of corticosterone (2 and 10 mg/day) increased food intake more in adrenalectomized fatty rats than in the corresponding lean ones. Progesterone increased food intake similarly in both groups. The enhanced responsiveness to corticosterone could account for many of the metabolical defects in the fatty rat.

Short loop feedback system for the control of follicle-stimulating hormone in the rabbit.

Studies were designed to assess whether a short loop feedback control for FSH existed in the rabbit. Castrated adult female animals bearing chronically implanted Silastic catheters to permit frequent blood sampling were studied without anesthesia. Ovine FSH was administered as an iv bolus in doses ranging between 0.1-500 micrograms. Endogenous rabbit FSH was quantified using a RIA that did not cross-react with ovine FSH. Blood samples were obtained before and 5, 10, 15, 30, 60, 120, 180, 240, and 300 min after the injection. Each animal was tested at two or more dose levels on different days. Ovine FSH produced suppression of rabbit FSH secretion within 5 min after injection. The minimum effective dose was 1 microgram; maximal suppression occurred with 50-100 micrograms ovine FSH. This short loop feedback control system was specific for FSH; ovine FSH, even at high doses, failed to suppress endogenous rabbit LH. This is the first direct demonstration of a negative short loop feedback control for FSH and the first entirely specific control for the FSH system to be described.

Pituitary and plasma lipotropins: demonstration of the artificial nature of betaMSH.

Evidence has been presented by others that betaMSH immunoreactivity in human plasma is due to beta and gamma lipotropin rather than betaMSH. We have studied this question in normal subjects utilizing a sensitive human betaMSH radioimmunoassay capable of quantifying betaMSH in unextracted plasma with a sensitivity of 7.5 pg/ml. Purified human beta lipotropin cross-reacted 30% on a molar basis with synthetic human betaMSH in this assay. ACTH related peptides showed less than 0.1% cross-reactivity. Normal values at 0800 h were 19.6+/-2.4 pg/ml and suppressed to 9.3+/-1.3 pg/mol following dexamethasone. Metyrapone increased 0800 h values to 379.6+/-89.9 pg/ml. Chromatographic studies on Sephadex G-50 demonstrated no betaMSH per se in human pituitaries, plasma from metyrapone treated normals, patients with Cushing's disease. Nelson's syndrome, or Addison's disease. betaMSH immunoreactivity showed the elution pattern of beta lipotropin.

Calcitonin in nonthyroidal cancer.

A blind prospective study was undertaken to determine the use of calcitonin (CT) as a tumor marker. After final diagnosis, results revealed elevated plasma CT (greater than 150 pg/ml) in common cancers as follows: lung, 38%; colon, 24%; breast, 38%; pancreas, 42%; and gastric, 30%. Fifty-eight percent of oat cell carcinomas were associated with elevated plasma CT. CT immunoreactivity was detected in 14% of tumor extracts and was not detectable in normal tissue other than thyroid. Hypercalcemia was not the cause of hypercalcitonemia. Incubation studies of [125I]human CT in cancer plasma and tumor extracts demonstrated that measurements were not an artifact of label degradation. In a survey of control patients with nonneoplastic disease, elevated CT was noted in renal failure, acute gastrointestinal bleeding, and in some patients with chronic obstructive lung disease. In conclusion, plasma CT is elevated in a substantial proportion of common neoplasms and is useful as a tumor marker.

Circulating levels of plasma adrenocorticotropin in polycystic ovary disease.

Excessive adrenal androgen production contributes to hyperandrogenism in polycystic ovarian disease (PCO). This study was performed to determine the concentration of basal plasma ACTH in PCO patients and normal women and correlate its level with that of circulating adrenal androgen. In PCO patients, significant increases in serum testosterone, androstenedione, and dehydroepiandrosterone sulfate were noted compared to levels in normal women. The mean circulating plasma ACTH in PCO patients (22 +/- 2 pg/ml) was not different from that in normal controls (20 +/- 2 pg/ml). The mean ratio of dehydroepiandrosterone sulfate to ACTH in individual PCO patients was significantly greater than that in normal subjects, whereas the cortisol to ACTH ratio was similar in both groups. These results suggest that increased adrenal androgen production in PCO patients is not due to abnormal ACTH secretion but arises from either altered adrenal responsiveness to ACTH or abnormal adrenal stimulation by a factor(s) other than ACTH.

ProACTH: use for early detection of lung cancer.

ProACTH was identified by radioimmunoassay and column chromatography in extracts of 38 lung carcinomas. One hundred patients were evaluated because of abnormalities on chest roentgenograms; 53 (72 per cent) of 74 with lung cancers had increased plasma ACTH immunoreactivity; all 26 with benign abnormalities had normal ACTH. Of 101 patients with obstructive lung disease, five of 20 with elevated plasma ACTH levels and two of 81 with normal plasma ACTH levels had lung cancer within two years. In three of 31 patients with granulomatous lung disease plasma ACTH levels were elevated during acute exacerbation of the disease, but they returned to normal after recovery. We conclude that plasma ACTH immunoreactivity is frequently increased early in the course of lung carcinoma.

Ectopic production of lipotropin by cancer.

Lipotropin (LPH) has been evaluated as a potential tumor marker using a sensitive beta melanocyte-stimulating hormone (beta MSH) radioimmunoassay. All 79 acetic acid extracts of carcinomas of lung, colon, stomach, esophagus and breast contained LPH in concentrations greater than blood; 61 of 79 extracts contained LPH in larger amounts than control tissues from patients without cancer. In a blind prospective study, plasma LPH was quantified in 107 patients admitted for work-up because of an abnormality on a chest roentgenogram. Thirty-one of 33 patients subsequently diagnosed as having benign lesions had plasma LPH within the 95 per cent confidence limits of normal subjects whereas 28 (36 per cent) of the 74 patients subsequently diagnosed histologically as having primary lung carcinoma had elevated levels. In control studies, 13 of 100 patients with chronic obstructive pulmonary disease had elevated plasma LPH levels; three of the 13 with elevated levels and four with normal levels have been diagnosed, during the two years of follow-up, as having lung carcinoma. In control studies of 23 patients with granulomatous lung disease, 22 had normal levels of LPH. In those with carcinoma of the colon elevated plasma LPH levels were observed in two of 21 untreated patients and in 11 of 61 patients receiving noncurative chemotherapy. Elevated plasma LPH levels were also observed in 10 of 59 patients with breast cancer, eight of 28 with pancreatic cancer, eight of 22 with gastric or esophageal cancer, six of 16 with renal cancer, four of eight with prostatic cancer, one of seven with cervical cancer and one of six with ovarian cancer. We conclude, an elevated LPH level is frequently observed in blood and tumor tissue from patients with various types of carcinoma.

The dose-response relationship of ACTH and cortisol in Cushing's disease.

The dose-response relationship between plasma ACTH and plasma cortisol was examined in normal subjects, patients with Addison's disease and patients with Cushing's disease. Plasma cortisol and ACTH levels were measured every half-hour from 06.00 h to 10.00 h and from 16.00 h to 18.00 h during a control day and during 1 to 3 days of continuous cortisol infusion. A plot of mean morning plasma ACTH versus the log of mean plasma cortisol revealed a similar dose-response relationship in normal and Addisonian subjects. Total plasma cortisol was four times more potent in suppressing mean morning ACTH in normal and Addisonian subjects, than in patients with Cushing's disease. When plasma cortisol was undetectable, there was no significant difference between mean morning ACTH concentrations in Addisonian patients and in adrenalectomized Cushing's patients. The glucocorticoid feedback control of ACTH in Cushing's disease had dose-response characteristics similar to those in Addison's disease and normal subjects, except for decreased sensitivity to cortisol feedback suppression of ACTH.

Improved iodination of peptides for radioimmunoassay and membrane radioreceptor assay.

Generally applicable methods for iodinating and purifying small peptide radiolabels for radioimmunoassay and membrane radioreceptor are described in detail. Resulting improvements in radioreceptor assay and radioimmunoassay, as well as results of analyses of specific activity, separation from unlabeled peptide, and storage characteristics, are presented for luliberin, corticotropin, melanotropin, and calcitonin.

Human chorionic gonadotropin--like material: presence in normal human tissues.

With the use of radioreceptor assay for gonadotropin and a beta-chain radioimmunoassay for human chorionic gonadotropin (hCG), we have been able to demonstrate the presence of hCG-like material in all normal human tissues tested. This activity was completely absorbed by a hCHG-antibody affinity column and was demonstrated to have altered carbohydrate content by studies showing this material did not bind to concanavalin A (con A)-Sepharose affinity columns. In identical studies greater than 90% of placental hCG was bound to con A. However, if placental hCG is rendered carbohydrate free it also does not bind to con A. It is known that carbohydrate-free hCG is cleared rapidly from the circulation and thus possesses little or no biological potency in vivo. Accordingly, we hypothesize: (1) that this hCG-like material in normal tissues has the protein structure of hCG but does not possess the carbohydrate moieties of placental hCG and probably has little or no bioactivity in vivo and (2) that the trophoblastic cell is not unique in its ability to synthesize hCG but has developed the ability to glycosylate hCG, transforming a ubiquitous cellular protein into a hormone, hCG might better be called human cellular gonadotropin.