Ossi Laitinen

Modifications of a specific assay for hydroxyproline in urine.

Abstract Several modifications of a specific chemical assay for hydroxyproline in urine are presented which make the procedure more rapid without reducing its specificity or accuracy. Also, a new method for measuring the recoveries in individual samples with hydroxyproline-14C is presented. Results obtained with the new procedure in two laboratories over a number of years are reviewed.

DOES FLUORIDATION OF DRINKING-WATER PREVENT BONE FRAGILITY AND OSTEOPOROSIS?

The incidence of femoral-neck fracture was compared in 2 Finnish towns of similar economic structure, Kuopio and Jyväskylä. Kuopio has fluoridated its drinking-water since 1959, whereas Jyväskylä has only trace amounts of fluoride in its drinking-water. The incidence of bone fragility (measured as femoral-neck fractures) was found to be significantly less in Kuopio than in Jyväskylä. This finding seems to be associated with a fluoride content of 1 mg/l in the drinking-water of Kuopio.

Studies with 14C-proline on the action of cortisone on the metabolism of collagen in the rat

Abstract The action of cortisone on the metabolism of collagen was studied by injecting 14 C-proline into rats and determining the effect of cortisone on the specific activity and total activity of 14 C-hydroxyproline in the urine and in the skin collagen fractions. In the first series of experiments the administration of cortisone was begun 10 days before the administration of 14 C-proline. Both the amount of hydroxyproline excreted and the specific activity of urine 14 C-hydroxyproline Were lower in the cortisonetreated rats than in the controls. The total activity of urine 14 C-hydroxyproline was therefore still more reduced, and during scme of the urine collection periods it decreased to almost half the value of the controls. The mean values for the specific activity and total activity of 14 C-hydroxyproline in the soluble collagen fraction of the skin were likewise lower in the cortisone-treated rats than in the controls. In the second series of experiments the 14 C-proline was injected 30 days before the start of cortisone administration. A small decrease occurred in the amount of hydroxyproline excreted in the urine in the cortisone-treated rats compared with the controls, but the total activity of urine 14 C-hydroxyproline remained unchanged. The total activity of 14 C-hydroxyproline in the skin collagen fractions was likewise not changed by the cortisone treatment. The results of the present study suggest that pharmacological doses of cortisone have an antianabolic action on the formation of soluble collagen, but no effect on the catabolism of the insoluble collagen fibres.

Collagen metabolism of the skin in Marfan's syndrome

Abstract 1. The metabolism of collagen in Marfans syndrome was studied by using punch biopsy specimens of skin from patients with Marfans syndrome and from healthy control subjects. In addition, the urinary hydroxyproline excretion of the patients with Marfans syndrome was measured. 2. 1. The skin specimens were subjected to extraction with 0.14 M and 1.0 M sodium chloride successively. In Marfans syndrome, the mean concentration of 0.14 M sodium chloride-soluble collagen was found to be 2–3-fold that of the control subjects. The mean concentration of 1.0 M sodium chloride-soluble collagen was also higher in Marfans syndrome, but the difference from the controls was smaller than in the 0.14 M sodium chloride-soluble collagen fractions. 3. 2. Despite the increased content of neutral salt-soluble collagen, the concentration of insoluble or total collagen was not significantly changed. 4. 3. The incorporation of [ 14 C]proline into [ 14 C]hydroxyproline of dermal collagen in vitro was greatly increased in Marfans syndrome. The increase in the uptake of the isotope was of about the same magnitude in both the soluble and insoluble collagen fractions of the skin. 5. 4. The urinary excretion of hydroxyproline was elevated in 2 of the 5 patients with Marfans syndrome. The results suggest that an increase in the turnover rate of collagen is the principal change in the metabolism of collagen in Marfans syndrome. However, a possible slight change in the rate of conversion of soluble collagen to insoluble, mature collagen fibres cannot be wholly excluded on the basis of the present results.

VERY HIGH MEASLES AND RUBELLA VIRUS ANTIBODY TITRES ASSOCIATED WITH HEPATITIS, SYSTEMIC LUPUS ERYTHEMATOSUS, AND INFECTIOUS MONONUCLEOSIS

Abstract 30 out of 12,269 sera which were sent to a virological laboratory to be screened against antibodies to several viruses showed very high measles or rubella antibodies although there had been no recent typical rubella or measles infection. 7 patients had chronic active hepatitis, 2 had chronic hepatitis, 6 had acute hepatitis, 4 had systemic lupus erythematosus, and 4 had infectious mononucleosis. The onset of acute hepatitis was in 2 cases associated with skin rash, whereas no other patients had skin manifestations. During the onset of acute hepatitis there occurred significant rises in the measles and/or rubella virus antibody titres in 4 cases and signs of continuous inflammation were observed in 3 cases. The findings confirm other reports that patients with chronic active hepatitis and systemic lupus erythematosus have raised titres to measles and rubella antigens. Furthermore, it seems that two other diseases, acute hepatitis and infectious mononucleosis, show in some cases very high antibody titres to measles and rubella antigens. Our data suggest that atypical viral infection plays an active role in the pathogenesis of at least some of the abovementioned conditions.

Action of growth hormone on the metabolism of collagen in the rat

Abstract The action of growth hormone on the metabolism of collagen was studied with 14 C-proline. (a) When 14 C-proline was injected 20 days after the beginning of growth hormone injections, the total activity of 14 C-hydroxyproline in the collagen fractions of the skin and in the nonfractionated collagen of the femurs was higher in the rats treated with growth hormone than in the controls. The distribution of 14 C-hydroxy-proline between the soluble and insoluble collagen of the skin was similar in the treated rats and the controls. The total activity of urinary 14 C-hydroxyproline was higher in the treated rats than in the controls, and this increase was of the same magnitude as in the 14 C-hydroxyproline of the skin and bone. (b) When 14 C-proline was injected 12 days before the beginning of growth hormone injections, administration of growth hormone caused an increase in the total activity of urinary 14 C-hydroxyproline compared to the controls. The results of the present study suggest that the rate of collagen synthesis was increased by growth hormone, and this effect was followed by an increased urinary excretion of hydroxyproline. No marked changes were found in the rate of conversion of soluble collagen into insoluble collagen or in the rate of catabolism of soluble collagen when expressed per unit of soluble collagen. The rate of catabolism of insoluble collagen was increased by growth hormone, and this effect contributed to the increased urinary hydroxyproline excretion.

Further evaluation of the significance of urinary hydroxyproline determinations in the diagnosis of thyroid disorders.

Abstract The urinary excretion of total hydroxyproline was determined in 262 patients with various thyroid disorders and in 47 euthyroid patients with elevated serum protein-bound iodine (PBI) but without thyroid disease. The values were compared with normal values (limits of ± 2 S.D.) in 92 children and in 72 adults 18 to 55 years of age, reported previously from our laboratory. In addition, normal values were determined in 53 adult euthyroid patients over 55 years of age. In adult patients, the urinary excretion of hydroxyproline was increased in hyperthyroidism above the upper limit of normal values in 107 out of 111 patients 18 to 65 years of age and in 10 out of 14 patients over 65 years of age. In hypothyroidism the urinary excretion of hydroxyproline was decreased below the lower limit of normal values in 22 out of 33 patients, and PBI was decreased in 24 of these patients. In the euthyroid patients with various thyroid disorders the urinary excretion of hydroxyproline was within the limits of normal values in 63 out of 68 patients. In an additional group of 47 patients with elevated PBI without hyperthyroidism, the urinary hydroxyproline values were within the limits of normal values in 46 cases. In children, the hydroxyproline values were above the upper limit of normal values in 10 out of 13 patients with hyperthyroidism, and below the lower limit of normal values in all 23 patients with hypothyroidism. The results support the earlier suggestion that determination of urinary hydroxyproline excretion may be a useful supplement to existing laboratory tests for the diagnosis of disturbances of thyroid function. The reliability of this test is high in cases of hyperthyroidism in a dult patients, and in cases of hypothyroidism in children.

Urinary free and total hydroxyproline in hyperparathyroidism and the effect of removal of parathyroid adenoma

Abstract The urinary excretion of total hydroxyproline was elevated above the upper limit of normal values in 8 out of 13 patients with surgically confirmed primary hyperparathyroidism. All patients with normal urinary total hydroxyproline excretion had normal plasma alkaline phosphatase levels and normal bone X-rays, whereas 3 of the 8 patients with increased total hydroxyproline excretion had increased plasma alkaline phosphatase levels, and 4 of these 8 patients showed evidence of bone involvement in X-rays. These results support the suggestion that the urinary excretion of total hydroxyproline may be a more sensitive index of bone involvement in hyperparathyroidism than plasma alkaline phosphatase or bone X-rays, but that even normal hydroxyproline excretion does not exclude bone involvement. After removal of the parathyroid adenoma, the urinary excretion of total hydroxyproline decreased in all 7 patients in whom this effect was studied, including 2 patients with initially normal urinary total hydroxyproline values.The ratio of free to total urinary hydroxyproline was determined in 9 patients with hyperparathyroidism, including 4 patients with normal urinary total hydroxyproline excretion. This ratio was found to be elevated in 8 out of 9 patients studied. The content of free serum hydroxyproline was normal in 3 of these 8 patients, suggesting that the increased ratio in the urine was probably due to renal effects of parathyroid hormone