Chikara Shimizu

Sp1 elements in SULT2B1b promoter and 5'-untranslated region of mRNA : Sp1/Sp2 induction and augmentation by histone deacetylase inhibition

The steroid/sterol sulfotransferase gene (SULT2B1) encodes for two isozymes of which one (SULT2B1b) sulfonates cholesterol and is selectively expressed in skin. The human SULT2B1 gene contains neither a TATAAA nor a CCAAT motif upstream of the coding region for SULT2B1b; however, this area is GC‐rich. Of five Sp1 elements identified two had regulatory activity utilizing immortalized human keratinocytes: one element is located above the ostensible transcription initiation site, whereas the other is located within the 5′‐untranslated region of the SULT2B1b mRNA. Sp1 and Sp2 transcription factors identified by supershift analyses induced reporter gene activity, an effect markedly augmented by histone deacetylase inhibition.

A rare case of Gitelman’s syndrome presenting with hypocalcemia and osteopenia

Gitelman’s syndrome (GS), an autosomal recessive disorder caused by a defect of the thiazide-sensitive NaCl cotransporter (TSC) at the distal tubule, is characterized by hyperreninemic hyperaldosteronism with normal or low blood pressure, hypokalemia, metabolic alkalosis, hypomagnesemia and hypocalciuria. An 18-yr-old Japanese man was admitted to our hospital with a history of muscle weakness and transient tetanic episodes. He showed hypocalcemia in addition to hypokalemia, severe hypomagnesemia, hypocalciuria and hyperreninemic hyperaldosteronism with normal blood pressure. Furthermore, bone mineral density at the lumbar spine revealed osteopenia. A diagnosis of GS was made on the basis of clinical features, laboratory data and renal function test. The electrolyte imbalance was corrected and bone mineral density was slightly increased with chronic treatment of magnesium and potassium salts. Genetic analysis revealed that TSC gene of the patient has a heterozygous C to A nucleotide substitution at position 545 in exon 4, which causes a threonine (Thr) to lysine (Lys) substitution at position 180. This is a rare case of GS with hypocalcemia and osteopenia which could be caused by severe hypomagnesemia.

A case of reversed pituitary dysfunction with intrasellar mass

Hypopituitarism can be caused by tumor, inflammation, granuloma and injuries. Once pituitary function is disturbed, hormone replacement therapy is necessary for the remaining life span in most cases. We have experienced a rare case of a unique intrasellar mass associated with pituitary dysfunction in which both spontaneously reversed. A 61-yr-old woman developed hypoadrenalism and central diabetes insipidus (cDI). Magnetic resonance (MR) imaging revealed a lobular, strong hypointense lesion with spotty signal in the middle of the hypophysis. This spotty lesion showed isointensity on T1- and high-intensity on T2-weighted MR images. The spotty signal as well as the normal pituitary lobe were enhanced by the administration of gadolinium. As replacement therapies for hypoadrenalism and cDI, 10 mg of hydrocortisone and 2.5 μg of desmopressin acetate were prescribed. Three months later, slight shrinkage of intrasellar mass and spontaneous improvement of pituitary functions were found. Hydrocortisone was then discontinued. Furthermore, because polyuria and polydipsia were improved nine months later, desmopressin acetate was stopped. Currently, the intrasellar mass continues to shrink, and the patient shows no symptoms without medication. Based upon the unique features of MR images, we suspect that the origin of the mass is an intrasellar hemangioma.