Cloning and characterization of the 5'-flanking region of the human prolactin-releasing peptide receptor gene.

Recently a novel peptide which specifically stimulates the secretion of prolactin (PRL) was found and named PRL-releasing peptide (PrRP). To evaluate the regulation of human (h) PrRP-receptor (PrRP-R) gene expression, we cloned the 5'-flanking region of the hPrRP-R gene and determined the nucleotide sequence of 4.0 kilobase pairs (kb) upstream from the translation start site. Analysis of the hPrRP-R transcripts by means of 5'-rapid amplification of cDNA ends suggested that the hPrRP-R gene had multiple transcription start sites between -429 and -365 from the translation start site. There is no typical TATA or CAAT but a GC box and putative binding sites for several transcription factors including Pit-1 and pituitary homeobox 1 (Ptx1). However, transient transfection studies using a luciferase reporter gene demonstrated that 5'-flanking region exerts promoter activity in several non-pituitary cell lines as well as in GH(3) cells. The GC box located from -467 to -457 was identified as an important region for the basal expression of the hPrRP-R gene. Knowledge of the promoter region of the hPrRP-R gene, which was obtained in the present study, will facilitate the clarification of its transcriptional regulation.

Multifocal fibrosclerosis as a possible cause of panhypopituitarism with central diabetes insipidus.

Multifocal fibrosclerosis denotes a combination of similar fibrous disorders occurring at different anatomical sites. We encountered a 53-year-old male patient with orbital pseudotumor, chronic paranasal sinusitis, fibrous nodules of the lungs, intracranial pachymeningitis, and panhypopituitarism with central diabetes insipidus (DI) as a possible manifestation of multifocal fibrosclerosis. It has been reported that intracranial pachymeningitis or orbital pseudotumor associated with multifocal fibrosclerosis could invade the sella turcica causing a variety of anterior and/or posterior pituitary dysfunctions. In our case, intracranial pachymeningitis apparently involved the pituitary stalk and gland. Isolated gonadotropin deficiency, in addition to central DI, preceded panhypopituitarism. Although panhypopituitarism with central DI due to multifocal fibrosclerosis is quite rare and only one case has ever been reported, this systemic fibrotic disorder can be a possible cause of panhypopituitarism with central DI.

The excitability of a motoneuron pool assessed by the H-reflex method is correlated with the susceptibility of Ia terminals to repetitive discharges in humans.

The correlation of the degree of the Hoffmann (H-) reflex depression induced by a passive stretch of the soleus muscle (Sol) and the excitability of the motoneuron (MN) pool was investigated in 24 healthy human subjects. The excitability of the Sol MN pool was determined by the ratio of the slope of the H-reflex (Hslp) and M-response recruitment curves (Mslp). The Hslp/Mslp ratio was decreased by a passive stretch of the Sol given 1 s before the H-reflex stimulus, and was significantly correlated with the amount of the H-reflex depression. These results suggest that the excitability of the MN pool assessed by the H-reflex method depends on the presynaptic mechanism involved in the efficiency of transmission across the synapses of Ia afferents in response to repetitive discharge.

Cloning and characterization of the 5'-flanking region of the human growth hormone-releasing hormone receptor gene.

We cloned the 5'-flanking region of the human growth hormone-releasing hormone receptor (GHRH-R) gene and determined the nucleotide sequence of 2.7 kilobases upstream from the translation start site. RNase protection analysis showed the major transcription start site is 122 base pairs upstream from the translation start site. The 5'-end of the longest product of 5'-rapid amplification of cDNA ends was close to the site. There were no typical TATA homologies but several putative regulatory elements including Pit-1-binding site-like element. Transient transfection studies using a luciferase reporter gene demonstrated that 5'-flanking region had promoter activity in GH3 cells (derived from rat pituitary tumor) but not in nonpituitary cells, BeWo and HeLa cells. However, co-transfection of Pit-1 expression vector increased luciferase activity in BeWo cells. Deletion study showed that the regions from -310 to -130 and from -130 to -120 were important for the GHRH-R gene expression in GH3 cells, although the latter contributed less to the gene expression. In BeWo cells co-transfected with Pit-1 expression vector, the region from -310 to -130 was essential for the Pit-1-dependent expression of GHRH-R gene. The region from -310 to -120 has two putative Pit-1-binding sites, P1 and P2, located from -129 to -123 and from -171 to -160, respectively. Both mobility shift assay and DNase-I footprint analysis showed that P2 had much higher Pit-1 binding affinity than P1. Mutation of P2 decreased GHRH-R gene expression in GH3 cells. These findings were consistent with the results that the region from -310 to -130 is an important element for Pit-1-dependent expression of GHRH-R gene.

Severe insulin-resistant diabetes mellitus associated with hypereosinophilic syndrome.

We describe a 52-year-old male manifesting severe insulin resistance associated with hypereosinophilic syndrome (HES). Diabetes mellitus was initially well-controlled by an oral hypoglycemic agent, and thereafter by human insulin. Due to the progression of hypereosinophilia, hepatosplenomegaly and peripheral lymphoadenopathy, severe insulin resistance associated with diabetic ketoacidosis occurred repeatedly, despite intravenous administration of over 1,000 U per day of human insulin. A high plasma insulin-binding capacity as determined by Scatchard analysis was consistent with insulin antibody-mediated resistance. The diagnosis of HES was made due to the persistent elevation of eosinophil count and associated liver and cardiac damage. Glucocorticoid therapy successfully achieved both reducing clinical symptoms and improving glycemic control.

Development of simulation models for protein folding in a thermal annealing process--I: A simulation of BPTI folding by the pearl necklace model.

A model system is proposed to simulate the folding processes of proteins during thermal annealing. This system consists of four subsystems: (i) the pearl necklace model with isotropic inter-residue interactions; (ii) the extended pearl necklace model with anisotropic interaction potentials; (iii) molten globule phase dynamics; and (iv) final generation of the three-dimensional structure of a given protein. In this paper results obtained with the pearl necklace model are reported. This model consists of spherical elements and virtual bonds of 3.8 A in length and is intended to simulate dynamical processes at relatively high temperature where entropic terms play a dominant role. Inter-residue interactions are composed of spherical soft repulsive potentials and hydrophobic interactions inherent to respective residues. A simulation of folding processes of BPTI starting from the fully extended conformation indicated that intermediates, even at early stages of folding, are not randomly coiled but assume organized structures that resemble, to some extent, the native conformation.