Food-dependent Cushing's syndrome: characterization and functional role of gastric inhibitory polypeptide receptor in the adrenals of three patients

In the present work, the presence of gastric inhibitory polypeptide (GIP) receptors and their functional role in the adrenal cells of three patients with food-dependent Cushing's syndrome were studied. RT-PCR and in situ hybridization studies demonstrated the presence of GIP receptor in the adrenals of the three patients. The presence of this receptor was also demonstrated in two human fetal adrenals, but not in two normal adult human adrenals or in the adrenals of one patient with nonfood-dependent Cushing's syndrome. Freshly isolated cells from patient adrenals responded in a dose-dependent manner to the steroidogenic action of both ACTH and GIP, whereas cells from normal adrenals responded only to ACTH. Treatment of cultured normal adrenal cells with ACTH, but not with GIP, increased the messenger ribonucleic acid (mRNA) levels of cholesterol side-chain cleavage cytochrome P-450, P450c17, and 3beta-hydroxysteroid dehydrogenase, whereas both hormones enhanced these mRNAs in patients' adrenal cells, although the effects of ACTH were greater than those of GIP. Moreover, pretreatment with ACTH enhanced the steroidogenic responsiveness of both normal and patient adrenal cells, whereas GIP caused homologous desensitization, and this was associated with a marked reduction of GIP receptor mRNA levels, as demonstrated by RT-PCR and in situ hybridization. Finally, both ACTH and GIP inhibited DNA synthesis in one patient's adrenal cells, whereas in normal adrenal cells only ACTH had this effect. In conclusion, the present data demonstrate that ectopic expression of functional GIP receptors is the main cause of food-dependent Cushing's syndrome.     

Method of determining the thermophysical properties of orthotropic materials from the solution of a two-dimensional inverse heat-conduction problem

An unsteady two-dimensional inverse coefficient problem of heat conduction is formulated mathematically and solved.Translated from Inzhenefno-Fizicheskii Zhurnal, Vol. 56, No. 3, pp. 483–491, March, 1989.     

Stretched polytene chromosomes--model for studying the functional organization of eukaryotic chromosomes

To localize functional loci on cytological maps of polytene chromosomes we propose to use 10-100 times stretched chromosomes. Three different ways of stretchening are briefly considered: the squash tissue preparation, when chromosomes are stretched by hydrodynamical forces; the treatment of isolated polytene chromosomes in 10-minus 4M EDTA OR 0.8M NaCL with subsequent change of these solution for saline when abrupt structural changes occur in chromosomes and they become morphologically homogeneous threads (Gruzdev and Belaya, 1973); and, finally, the use of microneedles of the micromanipulator. After an intense (ca. 100 times) stretchening, the autoradiography is sufficient to localize the loci within one micron length of double helical DNA molecule.