Experiments on cell cultures demonstrated that isolated cells of clinically inert pituitary tumors release several hormones in small amounts into the medium: luteinizing and follicle-stimulating hormones, alpha-subunit of glycoprotein hormones, prolactin, and growth hormone. Multihormonal secretion of these cells indicates their poor morphofunctional differentiation. In contrast to normal pituitary cells, cells of clinically inert pituitary tumors respond nonspeciflcally to hypothalamic thyrotropin releasing hormone: by increased secretion of prolactin, gonadotropins, glycoprotein hormone alpha-subunit, and growth hormone. This capacity of tumor cells detected in vitro agrees with the probability of increased levels of gonadotropins and glycoprotein hormone alpha-subunit in the serum of patients with clinically inert pituitary tumors during pharmacodynamic thyrotropin releasing hormone test.

The authors discuss the experimental and clinical data on the origin, properties, and diagnostic value of serum immunoreactive prolactin (irPRL) with a high molecular mass (macroprolactin, 100K-PRL). This form predominates in the blood of about 25% of women of a reproductive age with hyperprolactinemia. Comparison of the biochemical, immunochemical, and functional characteristics of the blood serum 100K-PRL and the monomeric fraction irPRL (23K-PRL) showed them to differ in principle. A low biological activity of 100K-PRL explains the absence of typical clinical signs of hyperprolactinemia in many women with macroprolactinemia. In contrast to 23K-PRL, 100K.-PRL weakly reacts to stimulants and inhibitors of PRL secretion by the pituitary. PRL-binding protein, apparently an immunoglobulin, is the basis of fraction 100K-PRL. The authors consider that analysis of not only total irPRL in the blood, but of its high and low-molecular forms be included in the algorithm of diagnostic search in some forms of hyperprolactinemia. This will help determine the treatment policy, because moderate hyperprolactinemia with predominating 100K- PRL as a rule cannot be corrected by dopamine agonists.

The authors discuss the experimental and clinical data on the origin, properties, and diagnostic value of serum immunoreactive prolactin (irPRL) with a high molecular mass (macroprolactin, 100K-PRL). This form predominates in the blood of about 25% of women of a reproductive age with hyperprolactinemia. Comparison of the biochemical, immunochemical, and functional characteristics of the blood serum 100K-PRL and the monomeric fraction irPRL (23K-PRL) showed them to differ in principle. A low biological activity of 100K-PRL explains the absence of typical clinical signs of hyperprolactinemia in many women with macroprolactinemia. In contrast to 23K-PRL, 100K.-PRL weakly reacts to stimulants and inhibitors of PRL secretion by the pituitary. PRL-binding protein, apparently an immunoglobulin, is the basis of fraction 100K-PRL. The authors consider that analysis of not only total irPRL in the blood, but of its high and low-molecular forms be included in the algorithm of diagnostic search in some forms of hyperprolactinemia. This will help determine the treatment policy, because moderate hyperprolactinemia with predominating 100K- PRL as a rule cannot be corrected by dopamine agonists.

Binding of 125I-labeled prolactin in the sera of women with different forms of hyperprolactinemia was studied. Antiprolactin autoantibodies were detected in the blood of 24% of women with idiopathic hyperprolactinemia. In contrast to idiopathic hyperprolactinemia, there were no autoantibodies to prolactin in pregnant women with physiological hyperprolactinemia and in hyperprolactinemia of tumor origin. These data indicate that the presence of these antibodies in circulating blood can be one cause of idiopathic hyperprolactinemia. Moreover, the prevalence of high-molecular form of immunoreactive prolactin in the blood can be due to binding of an appreciable amount of prolactin monomer to antiprolactin autoantibodies.

Pituitary tumors are a fairly common and often very severe form of neuroendocrine pathology. They make up about 10% of all intracranial tumors detected in clinical practice. They are found at autopsy in 10-20% of cases. Therefore, elucidation of the fundamental mechanisms of the pathogenesis of various types of pituitary tumors, the characteristics of their cellular biology and the development on this basis of effective approaches to their diagnosis, monitoring and treatment are one of the priorities in endocrinology.

The pumping effect of a rotating truncated cone partially immersed in a viscous liquid is evaluated for both laminar and turbulent regimes. A mathematical model is constructed within a boundary layer approximation taking into account the effect of gravity on the amount of the liquid lifted by the partially immersed cone. Analytical and experimental results are in satisfactory agreement.

The history of discovery of low-molecular xenobiotics of peptide and поп-peptide origin selectively stimulating growth hormone (GH) secretion is presented and the properties of this family are described. Results of study of these synthetic GH secretogogues, their physiological effects and mechanisms of in vitro and in vivo action, relationships with GH releasing hormone (GH- RH) and somatostatin (SS), classical natural regulators of GH secretion, underlie the discovery of a heretofore unknown physiological system regulating normal pulsatile secretion of GH in interactions with GH-RH and SS and their receptors. This system includes a unique G-protein coupled receptor which was detected in the pituitary, hypothalamus, and hippocampus and was recently cloned, and endogenous ligand of this receptor, apparently a structural and functional analog of the above xenobiotics.

Experiments on primary cultures of human pituitary adenoma cells producing growth hormone (GH) or GH and prolactin showed that similarly to GH-releasing hormone (GHRH) synthetic hexapeptide GH-releasing peptide-2 (GHRP) directly enhance secretion of GH but not of prolactin by human pituitary cells. The effect of various doses of GHRP and GHRH applied in combination was additive or slightly synergistic in nature. Somatostatin inhibits secretion of GH induced by GHRP, GHRH, or their combination. A dissociation is found between the inhibitory effects of somatostatin on basal and stimulated GH secretion.

Somatoliberin stimulates secretion of growth hormone and has no effect on secretion of prolactin in primary cultures of hypophyseal adenoma cells obtained from acromegalic patients. A short-term contact of the cells with somatostatin inhibits secretion of growth hormone, while a long-term contact with this hormone inhibits prolactin production. Somatoliberin abolishes the inhibitory effect of somatostatin on the growth hormone secretion and at high concentrations stimulates it.

A nonisothermal process of highly volatile liquid evaporation on a rotary disk surface is discussed. A suggested model describes experimental results more correctly than an isothermal model.

The biochemical nature of a high-molecular-weight immunoreactive prolactin (HMW-irPRL) prepared by gel filtration of women's sera with predominance of this hormone form was studied. Immunochemical characteristics of HMW-irPRL are different from those of 23 kD prolactin (23 kD-PRL). A protein which specifically and reversibly binds to human [I-125]PRL is isolated from the pooled fractions of HMW-irPRL by affinity chromatography on prolactin-Sepharose. According to gel filtration, the binding protein (BP) has molecular weight about 150 kD, and it reversibly binds to protein A immobilized on Sepharose. Analysis by BP by SDS-PAGE resulted in two major protein bands, of 65-70 and similar to 150 kD. Both the bands, when transferred to nitrocellulose, interacted with [I-125]protein A. Binding of highly purified human pituitary prolactin to the BP significantly decreased the immunoreactivity of the hormone. The molecular weight of BP and its interaction with protein A and recognition by poly- and monoclonal antibodies against human (but not guinea pig) IgG indicate that BP may be an immunoglobulin. Thus, our data demonstrate that HMW-irPRL is formed by the binding of 23 kD-PRL to a specific serum protein which is probably an anti-prolactin IgG.

Antibodies to adeno-pituitary cell surface antigen (PCSA) were studied in 40 untreated children with idiopathic growth hormone (GH) deficiency to elucidate the role of autoimmune disorders in the pathogenesis of GH deficiency. Antibodies to rat PCSA were assayed by ELISA. PCSA was detected in 15% of patients with GH deficiency, in contrast to that in healthy children and children with autoimmune thyroid diseases. The authors consider that in some cases GH deficiency may be caused by autoimmune hypophysitis. A family study revealed PCSA in 25% of mothers of patients with GH deficiency. In a population of healthy women PCSA was detected in 5.7% cases. Hence, a hereditary background of autoimmune abnormality cannot be completely ruled out.

Thirty-two children with craniopharyngiomas aged 3.6 to 18.9 were examined. The patients were divided into 2 groups. Group 1 consisted of 16 children treated conservatively and group 2 of 16 children subjected to radical surgery. No release of growth hormone in response to clonidine stimulation (no more than 4,5 ng/ml) was observed in both groups; growth hormone release in response to administration of growth hormone releasing factor was reliably (p=0.003) higher in group 1 than in group 2 (7.5 3.9 and 2,5 5.1 ng/ml, respectively). At the same time, growth SDS was closer to the norm in group 2 than in group 1 (-1.27 1.3 and - 2.04 1.4, respectively), and growth rate in 8 out of 12 children in group 2, despite growth hormone insufficiency, was 6-12 cm/year. Comparison of the levels of serum prolactin in both groups showed no reliable differences, and the standard glucose tolerance test showed a high basal and stimulated level of insulin secretion in 8 children in group 2 and in 1 girl in group 1. The total, area under the curve representing insulin secretion (ACins) was 3016.0 4288.8 IU/l - min in group 1 and 5378.8 + 4511.2 IU/ 1 min in group 2, the correlation between ACins and growth SDS being 0.58 and between ACins and body weight index 0.61. Normal or high growth rate was observed in all the children with hyperinsulinism (ACins over 6000 IU/l min) and in 2 with normal insulin release after surgery, this permitting a conclusion on the principal role of insulin in growth stimulation in the presence of growth hormone insufficiency in these children.