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J H Jonxis

Publications and source records attributed to J H Jonxis.

At least 19 recordsLinked to original sources
PubMed1996

Changes in vitamin-D metabolites and parathyroid hormone in plasma following cholecalciferol administration to pre- and postmenopausal women in the Netherlands in early spring and to postmenopausal women in Curaçao.

To study the effect on plasma 25-hydroxycholecalciferol (25(OH)D), 1,25-dihydroxycholecalciferol (1,25(OH)2D) and parathyroid hormone (PTH) we supplemented premenopausal (aged 30 (SD 7) years) and postmenopausal (aged 61 (SD 2) years) white women living in The Netherlands in late winter/early spring, and elderly black and white women (aged 75 (SD 6) years) living in Curaçao (Dutch Antilles) with either 10 or 20 micrograms cholecalciferol/d for 4, 5 and 9 weeks respectively. Baseline plasma 25(OH)D concentration of Dutch women was lower than that of Curaçao women. Postmenopausal Dutch women had a higher PTH concentration in plasma than premenopausal Dutch and postmenopausal Curaçao women. There were no differences in plasma 1,25(OH)2D. Cholecalciferol administration increased 25(OH)D in all groups, 1,25(OH)2D in postmenopausal Curaçao women and PTH in postmenopausal Curaçao women and premenopausal Dutch women. Serum and urinary Ca and phosphate concentrations did not change. There were no response differences between 10 and 20 microgram doses. Oral cholecalciferol administration (either 10 or 20 micrograms/d) to women living at northern latitudes in late winter/early spring increased 25(OH)D levels to the baseline levels of elderly people living in the tropics.

Administration, Oral↗
PubMed1993

Age-dependent vitamin D status and vertebral condition of white women living in Curaçao (The Netherlands Antilles) as compared with their counterparts in The Netherlands.

Plasma vitamin D metabolites and parathyroid hormone concentrations of two groups of white women, aged 26-46 and 63-83 y, in Curaçao were studied to evaluate the effect of yearlong abundant sunlight on frequency of vertebral compression fractures in elderly women. 25-Hydroxyvitamin D of the younger group (median, 116 nmol/L) was higher than that of the older group (75 nmol/L). Both groups had higher 25-hydroxyvitamin D compared with approximately age-matched counterparts in The Netherlands during autumn and winter (50 and 25 nmol/L, respectively). Similar differences were found for 1,25-dihydroxyvitamin D, although to a lesser extent. Parathyroid hormone concentrations of older women in Curaçao (4.3 pmol/L) were higher than those of the younger women (2.3 pmol/L). Roentgenographic analyses of the spines of the older women did not show vertebral compression fractures commonly encountered in women living at higher latitudes. Uninterrupted high plasma concentrations of vitamin D metabolites may reduce vertebral compression fractures in postmenopausal white women.

Adult↗
PubMed1987

Comparison of the fatty acid composition of human milk from mothers in Tanzania, Curacao and Surinam.

Fatty acid composition of mature human milk from Curacao (Netherlands Antilles), Surinam and Tanzania was determined by capillary gas chromatography. In the Curacaoan samples the cholesterol and alpha- and gamma-tocopherol concentrations were also determined. Remarkable differences were found in the fatty acid composition of breastmilk fat from the three countries. The differences in the levels of medium chain fatty acids between Curacao and Tanzania, and between Curacao and Surinam were significant. The mean sum of the essential fatty acids linoleic acid and linolenic acid showed the highest values in Curacao (16.1 g per cent). Mean values for Tanzania and Surinam were 14.9 and 12.7, respectively. The mean level of the docosahexaenoic acid was higher in the Curacaoan and Surinam samples compared with that from Tanzania. In the Curacaoan breastmilk samples the concentrations of cholesterol and alpha- and gamma-tocopherol were about twice as high as those reported for Western countries.

Cholesterol↗
PubMed1980

[Human milk].

Explore the source record for details and available documents.

Energy Intake↗
PubMed1977

The nutritional significance of inborn errors of amino acid metabolism.

Inborn errors of metabolism affect the metabolism of 7 out of 8 essential amino acids and a number of non-essential ones. Dietary treatment has been applied with varying success. The wide variations in the severity of symptoms in this group of diseases are discussed. Dietary treatment opens the possibility to collect information about the minimal requirements of most essential amino acids. These requirements are likely to be still lower than those mentioned in the WHO Report No. 522, 1976. Children who for years have lived on one of these restricted diets, provide the possibility to compare the effect of such a diet on their nutritional status with that of children living on a normal diet.

Amino Acid Metabolism, Inborn Errors↗