[Hyperparathyroidism after radioactive iodine therapy for Graves' disease: a case report]

Herein we report a 36-year-old man with hyperparathyroidism and a past history of internal irradiation to the thyroid. Twelve years previously at age 24 years he had received 8 mCi of radioactive iodine for Graves' disease. An additional dose of 4 mCi was required 3 years later. A right lower parathyroid adenoma (28 X 23 X 20 mm, 5.7 g) was found at neck exploration. Although the association of external ionizing radiation to the head and neck and the subsequent development of hyperfunctioning parathyroid glands has been described in recent years, there are only 4 cases in the literature of parathyroid surgery for hyperparathyroidism secondary to earlier treatment with radioactive iodine for Graves' disease. In a long-term follow-up of 180 patients treated with radioactive iodine for Graves' disease, neither hypercalcemia nor hypophosphatemia was found. Whether internal radiation therapy can be a causative factor in the development of hyperparathyroidism should be elucidated in future. However, it seems reasonable to suggest that patients whose hyperthyroidism has been treated with radioactive iodine should have their serum calcium levels examined at 5-year intervals.

Bone scintigraphy in pulmonary alveolar microlithiasis: a comparative study of radioactivity and density distribution

A histologically proven case of pulmonary alveolar microlithiasis that demonstrated intense lung uptake of Tc-99m-MDP on a bone scan is presented. The spatial distribution within the lungs of the radioactivity and density was assessed either by single photon emission computed tomography (SPECT), or x-ray computed tomography (CT) respectively, and the regional magnitude of the two parameters were compared. The quantitative study of regional radioactivity and density revealed that both the parameters distributed symmetrically, showing gradual increase in magnitude from the upper to the lower lung regions. The radioactivity-density association observed in our patient may indicate on-going formation of microcalculi throughout the lungs, the degree of which is greater at the sites of more severe involvement.

A new fluorescence assay for dipeptidylpeptidase IV using tripeptide L-prolyl-L-prolyl-L-alanine as substrate

We have developed a new fluorescence assay for dipeptidylpeptidase IV using a tripeptide, L-prolyl-L-prolyl-L-alanine, which might be one of the potential natural substrates. The principle of the assay is based on the measurement of fluorescent adduct between alanine liberated from the tripeptide by enzymatic hydrolysis and o-phthaldialdehyde in the presence of 2-mercaptoethanol in aqueous alkaline medium. This new assay is sensitive enough to measure the enzyme activity in as little as 0.01 microliter of human serum and in crevicular fluid obtained from human gingival sulcus. The Km value for the tripeptide was 1.7 x 10(-5) M which is less than one-tenth of that obtained with other chromogenic or fluorogenic substrates. The interference by serum was overcome by simply incorporating the same amount of serum in the standards.

A new assay of X-prolyl dipeptidyl-aminopeptidase activity in human serum with glycylproline p-phenylazoanilide as substrate

A new assay procedure for X-prolyl dipeptidyl-aminopeptidase activity in human serum was developed with glycylproline p-phenylazoanilide tosylate as substrate. p-Phenylazoaniline liberated by the enzyme reaction was measured photometrically at 493 nm after stopping the reaction with acid. This assay was simple and sensitive, and less than 50 microliter of human serum was required for the assay. Km value was 2.5 mM and the optimum pH was 8.7. After disc gel electrophoresis of human serum, the enzyme activity could be distinctly observed as a reddish band on the gel when the gel was incubated with this substrate.

Prolyl hydroxylase activity in human normal skins and post-burn scars

Post-burn granulation tissues showed an extraordinary high prolyl hydroxylase (EC 1.14.11.2; proline, 2-oxoglutarate dioxygenase) activity, 25 to 50 times higher than the mean value of human normal skins from the frontal thighs of 15 subjects, 385 +/- 247 (S.D.) cpm/min/g of wet weight tissue. The activity in the scars decreased sharply within 4 to 5 months, and then gradually decreased to the normal range after 2 years or so. Well-aged scars tended to show lower values than the mean value of normal skins.

Serum glyccylproline p-nitroanilidase activity in human hypertension

Glycylproline p-nitroanilidase activity in serum from patients with essential hypertension was significantly higher than that from normotensive healthy subjects. In contrast, serum leucine beta-naphthylamidase activity did not differ significantly between hypertensive patients and normotensive controls.

X-Prolyl dipeptidyl-aminopeptidase activity, with X-proline p-nitroanilides as substrates, in normal and pathological human sera

X-Prolyl dipeptidyl-aminopeptidase (no EC no. assigned) activity in normal and pathological human sera was assayed with several newly synthesized X-proline p-nitroanilides as chromogenic substrates. Normal values for 88 healthy subjects (15 to 81 years old), with glycylproline p-nitroanilide as substrate at pH 8.7, were 54.9 +/- 1.5 (SE) (range, 25.7 - 96.0) mumol/min per liter of serum at 37 degrees C. The results suggest that the enzyme activities with all X-proline p-nitroanilides were increased in patients with hepatitis and decreased in patients with gastric cancer. On Sephadex G-200 column chromatography, normal human sera showed a single peak of enzyme activity with glycylproline p-nitroanilide as the substrate, which coincided with the peak with glycylproline beta-naphthylamide but was different from the peaks with leucine beta-naphthylamide. Sera from patients with hepatitis or liver cirrhosis showed an increase in the normal peak and the appearance of another new peak with glycylproline p-nitroanilide as substrate.

X-Prolyl dipeptidyl-aminopeptidase activity, with X-proline p-nitroanilides as substrates, in normal and pathological human sera

X-Prolyl dipeptidyl-aminopeptidase (no EC no. assigned) activity in normal and pathological human sera was assayed with several newly synthesized X-proline p-nitroanilides as chromogenic substrates. Normal values for 88 healthy subjects (15 to 81 years old), with glycylproline p-nitroanilide as substrate at pH 8.7, were 54.9 +/- 1.5 (SE) (range, 25.7 - 96.0) mumol/min per liter of serum at 37 degrees C. The results suggest that the enzyme activities with all X-proline p-nitroanilides were increased in patients with hepatitis and decreased in patients with gastric cancer. On Sephadex G-200 column chromatography, normal human sera showed a single peak of enzyme activity with glycylproline p-nitroanilide as the substrate, which coincided with the peak with glycylproline beta-naphthylamide but was different from the peaks with leucine beta-naphthylamide. Sera from patients with hepatitis or liver cirrhosis showed an increase in the normal peak and the appearance of another new peak with glycylproline p-nitroanilide as substrate.

Separation of two PZ-peptidases from bovine dental follicle

Two PZ-peptidases (EC 3.4.-) (A and B) cleaving a synthetic substrate for collagenase, 4-phenylazobenzyloxycarbonyl-L-Pro-L-Leu-Gly-L-Pro-D-Arg (PZ-peptide) have been separated from the particulate fraction of bovine dental follicle. PZ-peptidase A had a molecular weight of 220 000, an optimum pH at 8.0-8.5, and a Km value of 67 muM toward PZ-peptide at pH 7.1, whereas PZ-peptidase B had a molecular weight of 20 000, an optimum pH at 6.5-6.7, and a Km value of 400 muM toward PZ-peptide at pH 7.1. Two similar enzymes were also isolated from the soluble fraction. Since the pH-activity curve of the crude tissue preparations such as homogenate, microsomes and soluble supernatant had two peaks at 6.5-6.7 and 8.0-8.5, both PZ-peptidase A and B may exist in situ as two independent active enzymes.

Glycylprolyl beta-naphthylamidase activities in serum, liver and kidney of rats in chronic carbon tetrachloride intoxication

Following chronic carbon tetrachloride intoxication in rats, the activity of glycylprolyl beta-naphthylamidase increased in serum and decreased in liver, suggesting that the enzyme is released from liver in hepatic injury. In contrast, the enzyme activity in kidney did not decrease when the enzyme level in liver decreased significantly.