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Biomedical subjects

R Luyken

Publications and source records attributed to R Luyken.

At least 19 recordsLinked to original sources
PubMed1998

Rodent malaria in rats exacerbated by milk protein, attenuated by low-protein vegetable diet.

Young male Wistar rats were fed a purified, vegetable, low-protein diet containing 6% protein from maize gluten and 2% from soy protein isolate, or comparable diets in which maize gluten was replaced partly or completely by the equivalent amount of a milk protein concentrate. Diets with adequate protein level (16% or 22%) served as a control. At 21 or 31 days of age, the rats were infected with 3000 or 100000 erythrocytes parasitized with Plasmodium berghei. Results reported include body weight, mortality, paralysis and parasitaemia. Dietary replacement of part of the maize gluten protein by milk protein increased weight gain, but aggravated the malaria, as shown by increases in parasitaemia, paralysis and mortality. The aggravating effect of milk protein was dose-dependent. With only 4% milk protein in an 8% total protein diet, the disease symptoms were nearly as severe as with diets adequate in protein level. With a vegetable-only 8% protein diet symptoms were considerably less severe.

Animals↗
PubMed1992

Attenuation of malaria infection, paralysis and lesions in the central nervous system by low protein diets in rats.

Young Wistar rats developed a fulminant infection when inoculated with the rodent malaria parasite Plasmodium berghei. Rats that died during the infection exhibited a progressive paralysis of the extremities, a rapidly decreasing body temperature and minute haemorrhages in the brain. Increasing the level of protein in the diet from 4 to 8 and 16% was accompanied by an increase in morbidity and mortality from 15 to 40 and 90% respectively on day 6 of the infection. Increasing the level of dietary protein also increased the reticulocyte count of the peripheral blood in infected and non-infected rats. The attenuation of the cerebral syndrome in rats fed a diet low in protein may be related to changes in erythropoiesis or to changes in immune reactivity.

Animals↗
PubMed1990

Vitamin D status, parathyroid hormone and sunlight in Turkish, Moroccan and Caucasian children in The Netherlands.

At the end of the winter circulating concentrations of 25-hydroxyvitamin D (25-OHD) in Asian and Mediterranean immigrants in northwestern European countries are usually very low. This may lead to vitamin D deficiency and eventually to rickets. Children are more prone to develop vitamin D deficiency. The vitamin D status of 8-year-old Turkish, Moroccan and Caucasian children was assessed by measuring plasma concentrations of 25-OHD and parathyroid hormone (PTH) and related to the cumulated global sun radiation (CGSR). The study population was selected from school children in The Hague and Rotterdam (The Netherlands). In each city blood samples were examined from 40 migrant children and a Caucasian reference group (n = 40) (matched for age and sex). Children in The Hague were examined at the end of the winter and early spring (February/April) and those in Rotterdam in late spring and early summer (May/June). Mean plasma 25-OHD concentrations for the migrant children in both cities were significantly lower than for the Caucasian reference group. The lowest 25-OHD values were measured in migrant children in The Hague: 42 per cent of the Turkish and 23 per cent of the Moroccan children had plasma levels less than 20 nmol/l. In these groups hyperparathyroidism (PTH greater than 85 pmol/l) was significantly more prevalent. With all pooled data a significant correlation between plasma 25-OHD and PTH was observed (r = -0.24; P less than 0.001). Regression analysis indicated that the relationship between both variables did not differ among the three ethnic groups. As expected, 25-OHD concentrations were higher for increased CGSR. Differences in 25-OHD level are mainly explained by differences in skin pigmentation and calcium intake between Mediterranean and Caucasian children. The secondary hyperparathyroidism observed in some children confirms that migrant children have a higher risk of developing nutritional rickets when living in areas with a moderate climate.

Child↗
PubMed1986

The effects of a high-animal- and a high-vegetable-protein diet on mineral balance and bowel function of young men.

1. Twelve young men were given for periods of 20 d, each of three mixed diets, namely a low-protein (LP) diet (9% total energy as protein, 67% of animal origin), a high-animal-protein (HA) diet (16% total energy as protein, 67% of animal origin) and a high-vegetable-protein (HV) diet (16% total energy as protein, 67% of vegetable origin). Retention of calcium, magnesium, iron, zinc and copper as well as various bowel function indices were investigated during each dietary period. 2. Neither the HA diet nor the HV diet changed the retention of the minerals considerably. Only Fe balance decreased significantly on the HV diet. 3. Substituting the HV diet for the HA diet resulted in significant increases in faecal wet weight (17 g/d), defaecation frequency (0.12 stools/d), faecal volatile fatty acids (2.6 mmol/d) and a decrease in faecal bile acids (128 mumol/d). 4. It is concluded that a HV diet, rather than a HA diet is to be recommended with respect to bowel function, whereas the HV diet does not necessarily have a significant influence on mineral retention.

Adult↗