Pituitary atrophy in Korean (epidemic) hemorrhagic fever: CT correlation with pituitary function and visual field

Eleven patients with Korean (epidemic) hemorrhagic fever were each studied three times with high-resolution CT in order to demonstrate necrosis of the pituitary gland and to correlate the CT findings with the patients' pituitary function and visual fields. Seven of the 11 patients showed varying degrees of progressive decrease in the height of the pituitary gland: one severe, two moderate, and four mild. The visual fields of all the patients were checked at the time of the third (last) follow-up CT. Six of the 11 patients had bitemporal superior quadrantanopsia. In five patients, the decreased height (atrophic change) of the pituitary gland and the visual-field defect were coincidental. The visual-field defects in those patients were not improved on follow-up examination 5 weeks later. Two patients in whom a 1-year follow-up examination was performed showed no interval changes in the defects. Pituitary function tests were performed in nine of the 11 patients (six with atrophic pituitary glands and three without atrophic changes) at the time of the third CT. Five of the six patients with atrophy showed decreased pituitary reserve function for follicle-stimulating hormone, cortisol, or human growth hormone, while only one patient showed decreased reserve function for cortisol among the three patients without atrophic change. The pituitary atrophic changes observed on follow-up sellar CT are thought to be the result of the ischemic necrosis of the gland. The high probability (five of seven) of visual-field defects in those patients with atrophic glands suggests optochiasmatic and pituitary ischemia as the basic pathogenesis.

Carbonic anhydrase II deficiency identified as the primary defect in the autosomal recessive syndrome of osteopetrosis with renal tubular acidosis and cerebral calcification

The clinical, radiological, and pathological findings in three siblings affected with the autosomal recessive syndrome of osteopetrosis with renal tubular acidosis and cerebral calcification have been reported. In an effort to explain the pleiotropic effects of the mutation producing this disorder, we postulated a defect in carbonic anhydrase II (CA II), the only one of the three soluble isozymes of carbonic anhydrase that is known to be synthesized in kidney and brain. We report here biochemical and immunological evidence for the virtual absence of CA II in erythrocytes of patients affected with this condition, whereas CA I level is not reduced. Levels of CA II in erythrocyte hemolysates from asymptomatic obligate heterozygotes are about half of normal. These findings: (i) elucidate the basic defect in one form of inherited osteopetrosis; (ii) provide genetic evidence implicating CA II in osteoclast function and bone resorption; (iii) explain previous observations that carbonic anhydrase inhibitors block the normal parathyroid hormone-induced release of calcium from bone; (iv) clarify the role of renal CA II in urinary acidification and bicarbonate reabsorption; and (v) suggest a method to identify heterozygous carriers for the gene for this recessively inherited syndrome.

Amino acid substitution and chemical characterization of a Japanese variant of carbonic anhydrase I: CA I Hiroshima-1 (86 Asp replaced by Gly)

An electrophoretic variant of red cell carbonic anhydrase I, designated CA I Hiroshima-1, has been observed in 12 apparently unrelated individuals during a survey of 13,019 individuals from the cities of Hiroshima and Nagasaki, Japan. Analyses of tryptic and chymotryptic peptide patterns of this CA I variant purified from 8 of the 12 individuals revealed the same altered peptides in each case. Examination of the amino acid sequence of an altered tryptic peptide purified from one of the variants showed that the aspartic acid residue at position 86 was replaced by a glycine residue. Thermostability studies demonstrated that all samples of CA I Hiroshima-1 were less stable than normal CA I. The specific esterase (p-nitrophenyl acetate) activities of the normal and variant CA I isozymes were essentially the same. The difference spectra of the normal and variant enzymes were essentially the same. The isoelectric focusing patterns of CA I Hiroshima-1 showed a different pattern of minor bands to those produced by normal CA I. The relative amounts of the normal and variant enzymes purified from single heterozygous individuals were similar.

Chemical characterization of a new Japanese variant of carbonic anhydrase I, CA INagasaki 1 (76 arg leads to gln)

A new inherited variant of carbonic anhydrase I (CA I), designated CA INagasaki 1 (CA INGS 1), was discovered during a survey of hemolysates from 5852 individuals from the cities of Hiroshima and Nagasaki in Japan. Analysis of the amino acid composition of a tryptic peptide from the CA INGS 1 variant indicated that a glutaminyl residue was substituted for an arginyl residue at position 76. Heat degradation studies showed that the CA INGS 1 variant was less stable than normal CA I. The CO2 hydrase and esterase activities of the normal and variant carbonic anhydrases I, as well as the relative amounts of the two enzymes in heterozygotes, were similar.