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Biomedical subjects

J H de Vries

Publications and source records attributed to J H de Vries.

At least 19 recordsLinked to original sources
PubMed2002

[Comparable case finding percentages of osteoporosis despite diverging reasons for ordering bone densitometry by general practitioners and specialists].

OBJECTIVE: To assess the use of bone densitometry in practice. DESIGN: Retrospective. METHOD: General practitioners who had ordered bone densitometry for their patients were asked to fill in a questionnaire on the reasons for the request and the subsequent treatment they prescribed. For a similar number of patients from the outpatient clinics of general internal medicine and endocrinology, the medical records were examined to obtain the same information. RESULTS: In 9 months, general practitioners requested 150 bone density measurements; for 117 of these the data were complete. In one year, 150 measurements were requested by the outpatient clinics. Marked differences in the reasons for the request were seen in loss of body height, back pain and requests from the patient (indications for general practitioners) and in osteoporotic fractures and the use of corticosteroids (indications for specialists). The average result of the measurements, however, was the same, with mean T-scores in the lumbar spine of -2.26 and -2.19, respectively and case-finding percentages of osteoporosis of 21% on the basis of the lumbar spine and 40% on the basis of the spine or hip. Bone densitometry carried out after an osteoporotic fracture was associated with the lowest mean bone mineral density, followed by measurement on the basis of abnormal X-rays. Bone densitometry at the patient's request was associated with the highest bone density. The percentage of patients found to have osteoporosis turned out to be dependent on the site of measurement, the used reference ranges, and the method of reporting, especially for patients older than 70 years. When the bone density corresponded to a diagnosis of osteoporosis, nearly all patients were treated, mainly with a bisphosphonate. Treatment was also frequently started when the bone density was reduced, i.e. in case of osteopenia. Some patients with normal bone density were treated as well. The reason for such treatment was not always clear. CONCLUSION: General practitioners and specialists used different risk factors in deciding whether bone densitometry was indicated. However, the two groups used this diagnostic tool with equal efficiency, since both the percentages of osteoporosis detected and the average bone densities were the same.

Absorptiometry, Photon↗
PubMed2001

Serum lithium as a compliance marker for food and supplement intake.

BACKGROUND: Analyzing 24-h urine for lithium after consumption of lithium-tagged foods or supplements provides a validated compliance marker but is laborious. OBJECTIVE: Most studies involve blood sampling; therefore, we tested whether serum lithium concentration could be used as a compliance marker. DESIGN: We used serum lithium as a compliance marker in a dietary trial and an evaluation study. RESULTS: In the dietary trial, 78 volunteers consumed 500 mL yogurt tagged with lithium (250 micromol/d) for 6 wk. Serum lithium increased from 0.9+/-0.3 to 6.6+/-1.5 micromol/L, which was close to the predicted concentration, indicating that the subjects were highly compliant. However, the interindividual variability in serum lithium concentration was large. To test whether this variability resulted from compliance differences or natural variability, we performed an evaluation study: 12 subjects took a lithium supplement (250 micromol/d) for 13 d under supervision. Serum lithium increased from 0.14+/-0.03 to 3.9+/-0.8 micromol/L (range: 2.6-5.4 micromol/L); thus, there was wide interindividual variation in serum lithium despite 100% compliance. However, within-subject variability was small, with a CV of 7% for serum lithium measured on 4 different days. We checked whether taking half the dose on each of 2 d (125 micromol lithium/d) would significantly lower serum lithium. Indeed, serum lithium dropped in all subjects, by a mean of 1.0 micromol/L on the first day (P<0.0001) and by another 0.3 micromol/L on the second day (P = 0.0004). Thus, changes in serum lithium concentration of > or =1.0 micromol/L suggest altered compliance. CONCLUSION: Serum lithium concentrations after intake of lithium-tagged foods or supplements can be used to assess compliance in dietary trials.

Adult↗
PubMed2001

Red wine is a poor source of bioavailable flavonols in men.

Red wine is a source of polyphenolic antioxidants, of which flavonols such as quercetin are representatives. Red wine might therefore prevent LDL oxidation and atherosclerosis. However, data on the bioavailability of flavonols from wine are lacking. Therefore, we compared the bioavailability of flavonols, especially quercetin, from red wine with that from the major dietary sources, yellow onions and black tea. Twelve healthy men consumed 750 mL red wine, 50 g fried onions or 375 mL of black tea, each for 4 d in random order. These supplements provided similar amounts of quercetin (14-16 mg). There was a washout period of 3 d between each period of supplementation. The plasma quercetin concentration after the consumption of wine was lower than that after onions (P: < 0.05) and not different from that after tea. Urinary excretion of quercetin after wine did not differ from that after onions and was higher than that after tea (P: < 0.05). We conclude that flavonols from red wine are absorbed. However, because one glass of red wine provides fewer available flavonols than one portion of onions or one glass of tea, red wine appears to be a poorer source of flavonols than these other two sources.

Adult↗
PubMed2000

Impact of Mediterranean diet education versus posted leaflet on dietary habits and serum cholesterol in a high risk population for cardiovascular disease.

OBJECTIVE: To investigate the impact of intensive group education on the Mediterranean diet on dietary intake and serum total cholesterol after 16 and 52 weeks, compared to a posted leaflet with the Dutch nutritional guidelines, in the context of primary prevention of cardiovascular disease (CVD). DESIGN: Controlled comparison study of an intervention group given intensive group education about the Mediterranean diet and a control group of hypercholesterolaemic persons given usual care by general practitioners (GPs). SETTING: A socioeconomically deprived area in the Netherlands with an elevated coronary heart disease (CHD) mortality ratio. SUBJECTS: Two hundred and sixty-six hypercholesterolaemic persons with at least two other CVD risk factors. RESULTS: After 52 weeks, the intervention group decreased total and saturated fat intake more than the control group (net differences were 1.8 en% (95%CI 0.2-3.4) and 1.1 en% (95%CI 0. 4-1.9), respectively). According to the Mediterranean diet guidelines the intake of fish, fruit, poultry and bread increased in the intervention group, more than in the control group. Within the intervention group, intake of fish (+100%), poultry (+28%) and bread (+6%) was significantly increased after 1 year (P < 0.05). The intensive programme on dietary education did not significantly lower serum cholesterol level more (-3%) than the posted leaflet (-2%) (net difference 0.06 mmol l-1, 95%CI -0.10 to 0.22). Initially, the body mass index (BMI) decreased more in the intervention group, but after 1 year the intervention and control group gained weight equally (+1%). CONCLUSIONS: Despite beneficial changes in dietary habits in the intervention group compared with the control group, after 1 year BMI increased and total fat and saturated fat intake were still too high.

Adult↗
PubMed2000

Associations of alpha-linolenic acid and linoleic acid with risk factors for coronary heart disease.

BACKGROUND: Prevention of coronary heart disease (CHD) in high-risk subjects. OBJECTIVE: To investigate the associations of dietary intake of alpha-linolenic acid (ALA) and linoleic acid (LA) as assessed by food frequency questionnaire and in the plasma cholesteryl ester (CE), with CHD risk factors. DESIGN: Baseline data of a double-blind, randomized placebo-controlled trial. Subjects have hypercholesterolemia (6.0-8.0 mmol/l) and at least two other CHD risk factors (n=266). RESULTS: The reported dietary ALA and LA intakes and the LA/ALA ratio were associated with the contents in the CE (r=0.37, r=0.21, and r=0.42, respectively; P<0.01). In multivariate analysis, CE ALA was inversely associated with diastolic blood pressure (r=-0.13; P<0.05) and positively with serum triacylglycerol (r=0.13; P<0.05), and CE LA was inversely associated with serum triacylglycerol (r=-0.32; P<0.01). The CE LA/ALA ratio was strongly inversely associated with CE ALA (r=-0.95; P<0.01). In the lowest quintile of CE ALA, mean dietary intake was 0.4 energy % ALA (1.2 g/day), 8.4 energy % LA and an LA/ALA ratio of 21, and in the highest quintile 0.6 energy % ALA (1.7 g/day), 6.8 energy % LA and 12 (ratio). In the lowest quintile of CE ALA the diastolic blood pressure was 4 mm Hg lower (P trend<0.05), and the serum triacylglycerol 0.3 mmol/l higher (P trend NS) when compared with the top quintile. CONCLUSIONS: In a CHD high-risk population with LA-rich background diet, these cross-sectional data suggest that replacing LA in the diet by ALA may decrease diastolic blood pressure, and may increase serum triacylglycerol concentration.

Adult↗
PubMed1999

The sugar moiety is a major determinant of the absorption of dietary flavonoid glycosides in man.

Flavonoids are antioxidants present in plant foods. They occur mainly as glycosides, i.e. linked with various sugars. It is uncertain to what extent dietary flavonoid glycosides are absorbed from the gut. We investigated how the nature of the sugar group affected absorption of one major flavonoid, quercetin. Quercetin linked with glucose, i.e. quercetin glucoside and quercetin linked with rutinose, i.e. quercetin rutinoside, both occur widely in foods. When we fed these compounds to nine volunteers, the peak concentration of quercetin (Cmax) in plasma was 20 times higher and was reached (Tmax) more than ten times faster after intake of the glucoside (Cmax = 3.5+/-0.6 microM (mean +/- SE); Tmax < 0.5 h) than after the rutinoside (Cmax = 0.18+/-0.04 microM; Tmax = 6.0+/-1.2 h). The bioavailability of the rutinoside was only 20% of that of the glucoside. We suggest that quercetin glucoside is actively absorbed from the small intestine, whereas quercetin rutinoside is absorbed from the colon after deglycosylation. Absorption of other food components might also be enhanced by attachment of a glucose group.

Absorption↗
PubMed1998

Plasma concentrations and urinary excretion of the antioxidant flavonols quercetin and kaempferol as biomarkers for dietary intake.

Flavonols are antioxidants that may reduce the risk of heart disease. Two major flavonols in the diet are quercetin and kaempferol, and their main sources in The Netherlands are tea and onions. We investigated whether plasma concentrations and urinary excretion of quercetin and kaempferol in humans could be used as biomarkers of intake. We provided 15 subjects with strong black tea (1600 mL/d) or fried onions (129 g/d) for 3 d each in random order separated by a 4-d washout period. The tea provided 49 mg quercetin and 27 mg kaempferol daily and the onions provided 13 mg quercetin and no kaempferol. Flavonols from both foods were clearly absorbed. However, the excretion of unmodified quercetin was 0.5% of intake after tea and 1.1% after onions. Thus, the absorption of quercetin from tea was half of that from onions. The onion treatment was repeated 7-14 d later to estimate within-subject CVs as a measure of reproducibility when the same treatment is given twice. CVs for quercetin were 30% in plasma and 42% in urine. The magnitude of these variations relative to actual variations of approximately 60% between free-living subjects indicates that concentrations of quercetin in plasma and urine are applicable as biomarkers of its intake. We conclude that flavonols in plasma and urine reflect short-term flavonol intake and that they could be used as biomarkers to distinguish between high and low flavonol consumption in epidemiologic studies.

Adult↗
PubMed1997

Relative bioavailability of the antioxidant flavonoid quercetin from various foods in man.

Quercetin is a strong antioxidant and a major dietary flavonoid. Epidemiological studies suggest that consumption of quercetin protects against cardiovascular disease, but its absorption in man is controversial. We fed nine subjects a single large dose of onions, which contain glucose conjugates of quercetin, apples, which contain both glucose and non-glucose quercetin glycosides, or pure quercetin-3-rutinoside, the major quercetin glycoside in tea. Plasma levels were then measured over 36 h. Bioavailability of quercetin from apples and of pure quercetin rutinoside was both 30% relative to onions. Peak levels were achieved less than 0.7 h after ingestion of onions, 2.5 h after apples and 9 h after the rutinoside. Half-lives of elimination were 28 h for onions and 23 h for apples. We conclude that conjugation with glucose enhances absorption from the small gut. Because of the long half-lives of elimination, repeated consumption of quercetin-containing foods will cause accumulation of quercetin in blood.

Adult↗
PubMed1997

Fatty acids in serum cholesteryl esters as quantitative biomarkers of dietary intake in humans.

The fatty acid composition of serum cholesteryl esters is used as a qualitative biomarker of fatty acid intake, but quantitative data are scarce. Between 1987 and 1992, the authors fed various fatty acids in four controlled trials to 232 healthy Dutch volunteers and measured the proportion of fatty acids in participants' cholesteryl esters. Each 10% of energy fed as linoleic acid (18:2) raised the proportion of linoleic acid in cholesteryl esters by 9.3 g per 100 g of fatty acids (standard deviation (SD) 3.1). For oleic acid (cis-18:1), this figure was 6.5 g/100 g (SD 1.7); for trans fatty acids (trans-18:1), it was 1.1 (SD 0.5); for stearic acid (18:0), 1.0 (SD 0.4); for palmitic acid (16:0), 1.7 (SD 0.5); for myristic acid (14:0), 2.1 (SD 0.7); and for a mixture of saturated fatty acids (12:0, 14:0, and 16:0), it was 2.2 g/100 g (SD 1.0). The coefficient of variation of the responses was fairly constant, indicating that changes in intake for each of these fatty acids can be monitored with similar precision. These data can be used to estimate the degree of compliance in experimental studies involving exchanges of single dietary fatty acids. Most fatty acids in cholesteryl esters may also be used in observational studies to estimate differences in intake. However, because of multiple simultaneous differences in fatty acid intake between free-living individuals and between populations, such data cannot provide information on absolute intake of fatty acids.

Adult↗
PubMed1997

Bioavailability of the dietary antioxidant flavonol quercetin in man.

Quercetin, a dietary antioxidant flavonoid, has anticarcinogenic properties. We quantified the absorption of quercetin in ileostomists. Absorption was 52 +/- 5% for quercetin glucosides from onions, 17 +/- 15% for quercetin rutinoside, and 24 +/- 9% for quercetin aglycone. The plasma quercetin concentration in subjects with an intact colon, after ingestion of fried onions, apples and pure quercetin rutinoside, decreased slowly with elimination half-lives of about 25 h. Thus, repeated dietary intake of quercetin will lead to accumulation in plasma. The relative bioavailability of quercetin from apples and rutinoside was one-third of that from onions. Absorption kinetics and bioavailibility might be determined by the type of glycoside. Dietary quercetin could increase the antioxidant capacity of blood plasma.

Allium↗
PubMed1997

Consumption of quercetin and kaempferol in free-living subjects eating a variety of diets.

Quercetin and related flavonoids are anticarcinogenic in rats, but little is known about human intakes. The intake of five major flavonols and flavones was calculated using 1-day dietary records of 17 volunteers from 14 countries, and using both 3-day records and a food frequency questionnaire of eight Dutch adults. Total consumption (+/- SD) was 27.6 +/- 19.5 mg/day in the international subjects, 34.1 +/- 31.2 mg/day in the Dutch adults according to 3-day records, and 41.9 +/- 23.7 mg/day according to questionnaires. Quercetin contributed 68-73%, and kaempferol 22-29%, the major sources being tea and onions. A brief food frequency questionnaire may be a suitable method for ranking individuals by flavonol intake.

Adult↗
PubMed1997

CT before and after ERCP: detection of pancreatic pseudotumor, asymptomatic retroperitoneal perforation, and duodenal diverticulum.

BACKGROUND: A prospective study was done to investigate the occurrence of morphologic changes after ERCP that present as pancreatic pseudotumor on CT scan. Fifty-eight patients underwent CT before and after ERCP. In addition, post-ERCP complications and the value of routinely obtained CT before ERCP were assessed. RESULTS: Thirty-nine patients could be fully analyzed; 12 underwent a papillotomy (group 1). Pseudotumor of the pancreatic head was demonstrated on CT after ERCP in them (17%). No changes were seen in the 27 patients who underwent diagnostic ERCP (group 2) (p = 0.048). Asymptomatic retroperitoneal perforation after papillotomy was diagnosed in 3 patients (13%). Routinely obtained CT scans before ERCP defined a specific etiology of the biliary obstruction in 12% of patients not suggested by ultrasound. Duodenal diverticulum was found in 4 patients, resulting in a sensitivity of 36% and a specificity of 100% for CT. Oral contrast (600 ml) administered a few hours before endoscopy never hampered the endoscopist. CONCLUSION: Pancreatic pseudotumor on CT after ERCP occurred only when papillotomy was performed. CT remains a valuable diagnostic tool after diagnostic ERCP. Asymptomatic perforation may occur following ERCP with papillotomy. Routinely obtained CT before ERCP was not profitable for the endoscopist in more than 80% of our patients.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1997

A randomized trial of alcohol 70% versus alcoholic iodine 2% in skin disinfection before insertion of peripheral infusion catheters.

Skin disinfection before insertion of peripheral infusion catheters is standard practice, but a comparison in effectiveness of the two most widely used disinfectants is lacking. We compared alcohol 70% and alcoholic iodine 2% in a prospective randomized trial. Data from 109 patients on a pulmonary ward were analysed. Phlebitis occurred six times in the alcohol group and 12 times in the iodine group. This relative risk reduction of 53% failed to reach significance (P = 0.18). The power of the study, however, was only 0.55, meaning a 45% chance of missing a true difference. As countless catheters are inserted each year, a small difference in phlebitis rate could save discomfort to many patients. Thus, a larger trial seems warranted. The addition of theophylline to the prednisone infusion resulted in a significantly higher phlebitis rate: 27.3 versus 9.2% (P = 0.03).

Aged↗
PubMed1996

Absorption and disposition kinetics of the dietary antioxidant quercetin in man.

Quercetin is a dietary antioxidant that prevents oxidation of low-density lipoproteins in vitro by scavenging to free oxygen radicals. Its intake was inversely associated with coronary heart mortality in Dutch elderly men. However, data on absorption of quercetin in man are scarce and contradictory. We studied the time course of the plasma quercetin concentration in two subjects after ingestion of fried onions containing quercetin glucosides equivalent to 64 mg of quercetin aglycone. Peak plasma levels of 196 ng/ml were reached after 2.9 h, with a half-life of absorption of 0.87 h. The half-life of the distribution phase was 3.8 h, and of the subsequent elimination phase 16.8 h. After 48 h the plasma concentration was about 10 ng/ml. We conclude that quercetin glucosides from onions are absorbed and are eliminated slowly throughout the day. Thus, the dietary antioxidant quercetin could increase the antioxidant capacity of blood plasma.

Adult↗
PubMed1995

Positional distribution of fatty acids in dietary triglycerides: effects on fasting blood lipoprotein concentrations in humans.

We examined the effect of the positional distribution of fatty acids within dietary triglycerides on serum lipoproteins. Sixty subjects consumed two diets of equal fatty acid composition for 3 wk each. In the palm oil diet 82% of palmitic acid was attached to the outer two carbon atoms of glycerol, and 18% to the middle carbon. In the diet rich in enzymatically modified palm oil these figures were 35% and 65%, respectively. On the modified-fat diet, average lipoprotein concentrations showed nonsignificant (P > 0.13) increases of 0.06 mmol/L for total, 0.03 mmol/L for HDL, and 0.04 mmol/L for LDL cholesterol compared with palm oil. The small increases in total and LDL cholesterol were statistically significant in the men (n = 23) but not in the women (n = 37). The ratio of HDL to LDL cholesterol and serum triglyceride concentrations were unchanged. Thus, a large difference in dietary fatty acid configuration had little effect on lipoprotein concentrations in humans.

Adult↗
PubMed1995

Absorption of dietary quercetin glycosides and quercetin in healthy ileostomy volunteers.

Quercetin is a dietary antioxidant that prevents oxidation of low-density lipoproteins in vitro. Intake of quercetin was inversely associated with coronary heart disease mortality in elderly Dutch men. However, the extent of absorption of quercetin in humans is unclear. The aim of this study was to quantify absorption of various forms of quercetin. Nine healthy ileostomy subjects were studied, to avoid losses caused by colonic bacteria. They followed a quercetin-free diet for 12 d; on days 4, 8, and 12 they received a supplement of fried onions at breakfast (rich in quercetin glucosides) equivalent to 89 mg aglycone, pure quercetin rutinoside (the major quercetin compound in tea) equivalent to 100 mg aglycone, or 100 mg pure quercetin aglycone, in random order. Subsequently, participants collected ileostomy effluent and urine for 13 h. In vitro incubations of quercetin or its glycosides with gastrointestinal fluids showed minimal degradation. Absorption of quercetin, defined as oral intake minus ileostomy excretion and corrected for 14% degradation within the ileostomy bag, was 52 +/- 15% for quercetin glucosides from onions, 17 +/- 15% for quercetin rutinoside, and 24 +/- 9% for quercetin aglycone. Mean excretion of quercetin or its conjugates in urine was 0.5% of the amount absorbed; quercetin excretion in urine was negatively correlated with excretion in ileostomy effluent (r = -0.78, n = 27). We conclude that humans absorb appreciable amounts of quercetin and that absorption is enhanced by conjugation with glucose.

Adult↗
PubMed1994

Underestimation of energy intake by 3-d records compared with energy intake to maintain body weight in 269 nonobese adults.

We assessed how accurately participants in dietary trials reported their free-living energy intake. We compared self-reported energy intake, calculated from 3-d food records, with actual intakes needed to maintain body weight during controlled trials lasting 6-9 wk. In 269 free-living healthy male (n = 119) and female (n = 150) adults with mean body weights close to ideal values (mean +/- SD body mass index in kg/m2, 22.1 +/- 2.4), energy intake reported in food records was 1.2 +/- 1.6 MJ/d (277 +/- 378 kcal/d) lower than actual energy requirements during the experiments. The relative bias was significantly smaller (P = 0.01) for men (-8.0 +/- 13.4%) than for women (-12.2 +/- 13.7%). Body mass index, daily energy intake, and age were not significantly related to the extent of underestimation. We conclude that food records systematically underestimate energy needs in young, nonobese well-educated adults.

Adolescent↗