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Biomedical subjects

A E Meinders

Publications and source records attributed to A E Meinders.

At least 19 recordsLinked to original sources
PubMed2007

Cardiovascular risk factors after bariatric surgery: Do patients gain more than expected from their substantial weight loss?

BACKGROUND: While it has been established that even limited weight loss (5-10%) improves obesity-associated cardiovascular risk factors, it is not known if considerable weight loss following laparoscopic adjustable silicone gastric banding (LASGB) results in a cardiovascular risk profile that is comparable, worse, or even better than that of matched control subjects. METHODS: Cardiovascular risk factors were compared in three groups of 24 women each: an index group that had lost considerable weight following LASGB for morbid obesity (BMI>40 kg/m(2)), a control group with the same BMI that the index group achieved after weight loss, and a pre-weight loss group of women with a BMI above 40 kg/m(2). Anthropometric measures, fasting serum glucose, insulin, lipids, C-reactive protein, and homocysteine levels were determined and insulin sensitivity was estimated using a homeostasis model assessment index (HOMA-IR). RESULTS: After bariatric surgery, the index group had a BMI of 32.0+/-0.8 kg/m(2). This resulted in a significantly better cardiovascular risk profile than that of the pre-weight loss group (BMI 42.8+/-0.6 kg/m(2)). Unexpectedly, after weight loss, the index group had significantly lower systolic blood pressure, fasting serum insulin, and HOMA-IR than the BMI-matched (32.8+/-0.9 kg/m(2)) control group. Although not significant, diastolic blood pressure, LDL-cholesterol, and CRP levels were also lower. CONCLUSION: Considerable weight loss following bariatric surgery leads to a greater improvement in cardiovascular risk factors than might be expected from the weight loss.

Journal Article↗
PubMed2006

[Thyroid function, activities of daily living and survival in extreme old age: the 'Leiden 85-plus Study'].

OBJECTIVE: To determine the relationship between differences in thyroid function, changes in the activities of daily living and survival in the extremely-old segment of the general population in order to see whether screening for and treatment of subclinical thyroid-function disorders in the elderly will have a positive effect. DESIGN: Prospective observational population study among 85-year-olds. METHOD: As part of the 'Leiden 85-plus Study', all persons were followed who had their 85th birthday during the period from 1 September 1997 to 31 August 1999 (average length of time followed: 3.7 years; SD: 1.4). There were 558 participants. The thyroid function of these subjects was determined and the limitations in the activities of daily living, depressive symptoms, cognitive function and mortality were recorded annually. RESULTS: At the age of 85, there was no relation between the serum levels of thyroid-stimulating hormone (TSH) or free thyroxine (FT4) and limitations in the activities of daily living, the occurrence of depressive symptoms and cognitive deterioration. Neither was any relationship found during the period of follow-up. A higher TSH-level was associated with a lower mortality, even after correction for the differences in performance and health during the base measurement (mortality risk: 0.77 per SD-increase in TSH; 95% CI: 0.63-0.94). The mortality risk per SD-increase in FT4 was 1.16 (95% CI: 1.04-1.30). CONCLUSION: From the age of 85, there was no relationship between thyroid function and limitations in the activities of daily living, the occurrence of depressive symptoms or a deterioration in cognitive functions. Moreover, elderly persons with a less active thyroid gland lived longer. This raises the question whether the screening for and treatment of subclinical thyroid-function disorders in persons of extreme old age, as recommended, will have any positive effects.

Activities of Daily Living↗
PubMed2005

The metabolic syndrome: a vascular perspective.

The metabolic syndrome (MS) is a clustering of cardiovascular risk factors. Current definitions of MS use hypertension, waist circumference, fasting glucose, triglyceride and HDL-cholesterol levels as defining variables. The prevalence of MS is increasing in our society due to lifestyle changes that result in decreased physical activity and increased body weight. Patients with MS have a three times greater risk of coronary heart disease and stroke, and a two to four times greater risk of dying from atherosclerotic coronary heart disease than those without MS. Imaging studies have shown an increased burden and progression of atherosclerosis. Also, MS patients seem to be more vulnerable to events at comparable levels of atherosclerosis. First-line treatment for MS is therapeutic lifestyle intervention, including exercise and weight reduction. Medical intervention strategies using blood pressure-lowering medication, statins, fibrates and metformin seem the most appropriate to date. The effects of thiazolidinediones on cardiovascular endpoints have not been studied to a large extent in the setting of MS. Evidence regarding risk assessment and optimal medical strategies will be an important aspect of vascular research in the coming years.

Journal Article↗
PubMed2005

Factors predicting the blood glucose lowering effect of a 30-day very low calorie diet in obese Type 2 diabetic patients.

OBJECTIVE: To identify factors which predict the blood glucose lowering effect of monotherapy with a 30-day very low calorie diet (VLCD) in obese Type 2 diabetic patients. A responder was a priori defined as a patient with a fasting plasma glucose (FPG) level < 10 mmol/l on day 30. RESEARCH DESIGN AND METHODS: In 17 obese patients (BMI 37.6 +/- 5.6 (mean +/- SD) kg/m(2)) with Type 2 diabetes, all blood glucose lowering medication (including insulin) was discontinued on day -1 followed by a 30-day VLCD. On day 2 and 30 of the VLCD an intravenous glucose tolerance test (IVGTT) was performed. RESULTS: Of the 14 patients who completed the 30-day VLCD, eight qualified as responder. Responders and non-responders could be distinguished by day 2. Responders had a shorter duration of Type 2 diabetes and higher fasting serum insulin, C-peptide and HOMA-beta-values. In addition, responders displayed a more prominent second-phase insulin response following i.v. glucose loading and higher k-values. In a stepwise discriminant analysis, the change in FPG from day 0 to day 2 (responders +0.64 +/- 2.3, non-responders +4.15 +/- 3.3 mmol/l, P = 0.035) in combination with the area under the curve of insulin (AUC) above baseline during an IVGTT on day 2 (responders 571 +/- 236, non-responders 88 +/- 65 mU*50 min, P < 0.001), distinguished responders completely from non-responders. CONCLUSION: Preservation of the capacity of beta-cells to secrete insulin predicts a favourable metabolic response to a VLCD in obese Type 2 diabetic patients.

Area Under Curve↗
PubMed2005

Vasopressin: physiology and clinical use in patients with vasodilatory shock: a review.

Vasopressin is a nonapeptide synthesised in the hypothalamus and released upon stimulations such as hyperosmolality, hypotension and hypovolaemia. In acute shock states serum vasopressin levels increase rapidly and decrease in prolonged septic shock. The administration of vasopressin in healthy subjects has little effect, whereas in vasodilatory shock it increases the mean arterial pressure through V1 receptors and decreases the cardiac output. Vasopressin stimulates the V2 receptors in the kidney leading to reabsorption of water through aquaporin 2. However, in vasodilatory shock the antidiuretic effects are overcome by the effect vasopressin has on the kidneys: improvement of renal blood flow leading to water excretion. Twenty-four studies on the use of vasopressin in patients with vasodilatory shock are reviewed. They show that vasopressin potentiates norepinephrine effects, increases blood pressure significantly in patients with vasodilatory shock and may improve renal function. Side effects ranging from ischaemic skin lesions to possible intestinal ischaemia should not be underestimated. Above a dose of 0.04 U/min it may lead to cardiac arrest. Effects on mortality cannot be interpreted from these studies. Broad clinical use should await controlled trials to clarify its effects on clinical outcomes such as organ failure and mortality.

Animals↗
PubMed2004

[The value and limitations of the body mass index (BMI) in the assessment of the health risks of overweight and obesity].

--The Body Mass Index (BMI) is used as a measure of overweight and obesity. In epidemiological studies age, sex and ethnic background all have to be taken into consideration, particularly when determining the health risk caused by the amount of body fat. --Caution should be observed when using the BMI as a measure for interpreting overweight and obesity as body composition can be highly variable yet have the same BMI. Therefore, BMI is not a reliable measurement of body composition in individuals particularly in older and younger people. --Excess body fat in the visceral depot poses a separate health risk. The BMI does not give any insight into regional body fat distribution. Waist circumference is a valid index of visceral fat accumulation and can therefore be used as an indicator of health risks associated with visceral obesity.

Adipose Tissue↗
PubMed2004

Impact of meal timing and frequency on the twenty-four-hour leptin rhythm.

OBJECTIVE: To study the influence of changes in meal timing and frequency on the diurnal rhythm of leptin and on the 24-hour profile of insulin and glucose. PATIENTS AND METHODS: Five obese women were studied twice during a weight-maintaining diet in either 3 daily or 8 day and night equal portions. Blood was sampled for 24-hour profiles of leptin and insulin. RESULTS: During the 8-meal intervention, the 24-hour rhythm of leptin changed significantly: the amplitude decreased (p = 0.0089) and the acrophase was delayed by 168 min (p = 0.021). Also, 8 small insulin secretion peaks occurred instead of the 3 postprandial high insulin peaks. CONCLUSION: The dispersion of food intake over 24 h affects the diurnal leptin rhythm. These changes could not be attributed to changes in circadian timing or energy balance. Instead, changes in daily insulin secretion profiles might play a role.

Adult↗
PubMed2004

Pulsatile LH release is diminished, whereas FSH secretion is normal, in hypocretin-deficient narcoleptic men.

Hypocretin (orexin) peptides are involved in the regulation of energy balance and pituitary hormone release. Narcolepsy is a sleep disorder characterized by disruption of hypocretin neurotransmission. Pituitary LH secretion is diminished in hypocretin-deficient animal models, and intracerebroventricular administration of hypocretin-1 activates the hypothalamo-pituitary-gonadal axis in rats. We evaluated whether hypocretin deficiency affects gonadotropin release in humans. To this end, we deconvolved 24-h serum concentrations of LH and FSH in seven hypocretin-deficient narcoleptic males (N) and seven controls (C) matched for age, body mass index, and sex. Basal plasma concentrations of testosterone, estradiol, and sex hormone-binding globulin were similar in both groups. Mean 24-h LH concentration was significantly lower in narcolepsy patients [3.0 +/- 0.4 (N) vs. 4.2 +/- 0.3 (C) U/l, P = 0.01], which was primarily due to a reduction of pulsatile LH secretion [23.5 +/- 1.6 (N) vs. 34.3 +/- 4.9 (C) U.l(-1).24 h(-1), P = 0.02]. The orderliness of LH and FSH secretion, quantitated by the approximate entropy statistic, was greater in patients than in controls. In contrast, all other features of FSH release were similar in narcoleptic and control groups. Also, LH and FSH secretions in response to intravenous administration of 100 microg of GnRH were similar in patients and controls. These data indicate that endogenous hypocretins are involved in the regulation of the hypothalamo-pituitary-gonadal axis activity in humans. In particular, reduced LH release in the face of normal pituitary responsivity to GnRH stimulation in narcoleptic men suggests that hypocretins promote endogenous GnRH secretion.

Adult↗
PubMed2004

[Tetany due to excessive use of alcohol: a possible magnesium deficiency].

Two alcoholic patients, a woman aged 64 and a man aged 69 years, were admitted with tetany. Both had severe electrolyte disorders, with low plasma levels of calcium, magnesium and potassium. Following mineral supplementation both patients recovered. Hypomagnesaemia plays a central role in the pathophysiology of this syndrome. Chronic alcohol abuse results in hypomagnesaemia in 30% of patients by decreasing renal tubular reabsorption. Hypomagnesaemia leads to suppression of parathyroid-hormone secretion, parathyroid-hormone resistance and vitamin-D suppression, resulting in hypocalcaemia. Hypomagnesaemia also causes kaliuresis leading to hypokalaemia. Supplementation with magnesium is crucial in the treatment of this combined electrolyte disorder.

Aged↗
PubMed2004

Glucose homeostasis in abdominal obesity: hepatic hyperresponsiveness to growth hormone action.

It has been suggested that (abdominally) obese individuals are hypersensitive to growth hormone (GH) action. Because GH affects glucose metabolism, this may impact glucose homeostasis in abdominal obesity. Therefore, we studied the effect of GH on glucose metabolism in abdominally obese (OB) and normal-weight (NW) premenopausal women. A 1-h intravenous infusion of GH or placebo was randomly administered to six NW [body mass index (BMI) 21.1 +/- 1.9 kg/m(2)] and six OB (BMI 35.5 +/- 1.5 kg/m(2)) women in a crossover design. Insulin, glucagon, and GH secretion were suppressed by concomitant infusion of somatostatin. Glucose kinetics were measured using a 10-h infusion of [6,6-(2)H(2)]glucose. In both groups, similar physiological GH peaks were reached by infusion of GH. GH strongly stimulated endogenous glucose production (EGP) in both groups. The percent increase was significantly greater in OB than in NW women (29.8 +/- 11.3 vs. 13.3 +/- 7.4%, P = 0.014). Accordingly, GH responsiveness, defined as the maximum response of EGP per unit GH, was increased in OB vs. NW subjects (6.0 +/- 2.1 vs. 2.2 +/- 1.5 micromol.min(-1).mU(-1).l(-1), P = 0.006). These results suggest that the liver is hyperresponsive to GH action in abdominally obese women. The role of the somatotropic ensemble in the control of glucose homeostasis in abdominal obesity is discussed.

Abdomen↗
PubMed2004

Effect of atorvastatin on impaired vascular function in healthy old men.

OBJECTIVE: This study was initiated to examine the effect of cholesterol-lowering therapy with 40 mg atorvastatin on vascular function in healthy old and young men. METHODS: We selected healthy normolipidaemic, elderly subjects (n = 8, mean age 80.1 years) and young subjects (n = 7, mean age 21.8 years). All had a normal electrocardiograph and blood pressure, and signs or symptoms of cardiovascular disease were absent. The subjects were studied for 2 days, with 6 weeks of atorvastatin treatment in between. Forearm blood flow (FBF) was measured by computerized venous occlusion plethysmography upon intra-arterial infusion of acetylcholine (ACh; 30 and 90 ng/kg/min) and 5-hydroxytryptamine (5-HT; 0.3 and 0.9 ng/kg/min) as endothelium-dependent vasodilators, and sodium nitroprusside (SNP; 30 and 90 ng/kg/min) as an endothelium-independent vasodilator. RESULTS: At baseline, the mean absolute FBF in the elderly was 2.6 mL/min/100 mL and in the young 4.3 mL/min/100 mL tissue (P = 0.01). The mean serum total cholesterol levels were 5.2 and 3.8 mmol/L, respectively (P = 0.007). The endothelium-dependent vasodilatation induced by ACh and 5-HT was significantly lower in the elderly compared with the young (both P < 0.01), whereas the endothelium-independent vasodilatation induced by SNP was not significantly lower in the elderly compared with the young. Atorvastatin treatment decreased the serum total cholesterol level with a mean of 38 and 28% in the elderly and the young, respectively (P < 0.001). Impaired endothelium-dependent vasodilatation, however, was not modified (P > 0.65). CONCLUSIONS: Healthy old men have an impaired endothelium-dependent vascular response but this impairment is not restored by treatment with atorvastatin.

Acetylcholine↗
PubMed2003

[Overweight and obesity; recommendations from the National Health Council].

The Health Council of the Netherlands has issued a report on overweight and obesity. These are considered major threats to personal health, the public health care services and economic welfare. Overweight and obesity are no longer considered variations of the norm, but as a disease. As genetically predisposing factors cannot be influenced, major initiatives to contain further deterioration of the problem must be on environmental factors i.e. on macronutrient intake and physical exercise. Special target groups (young people, people of low socioeconomic status and immigrants) need to be defined. Government, health care organisations, industry and the general public should work together to combat overweight and obesity. The chances of success are not predictable but are certainly big enough to justify action.

Body Weight↗
PubMed2003

[Atherosclerosis and inflammation: the role of C-reactive protein].

C-reactive protein (CRP) is an acute phase protein, the serum concentration of which can increase up to a 1000-fold after the onset of a stimulus. It plays a role in the aspecific immune response to bacteria and fungi and the clearance of apoptotic cell material. Inflammation plays an important role in the aetiology and pathogenesis of atherosclerosis and plaque formation. Approximately fifty percent of acute coronary syndromes are the consequence of unstable plaques rupturing, followed by thrombus formation. A characteristic of these unstable plaques is an increase in inflammatory cells (macrophages and T lymphocytes). The serum concentration of CRP might reflect the amount of inflammation within atherosclerotic plaques and thus might provide an indirect measurement of the instability of the plaques. CRP could therefore have a predictive value for the occurrence of plaque rupture. Furthermore, there are indications that CRP itself is active in the inflammatory process. Prospective studies have shown that so-called high-sensitivity CRP (hsCRP) measurements could be used as a tool for determining the risk for acute coronary syndromes. The inflammation-inhibiting characteristics of statins and acetylsalicylic acid (especially the reduction of the hsCRP level) might contribute to reducing the risk of plaque rupture.

Acute Disease↗
PubMed2003

Strong decrease of high sensitivity C-reactive protein with high-dose atorvastatin in patients with type 2 diabetes mellitus.

OBJECTIVE: Statins are known to reduce CRP concentrations, but whether high doses are more effective is not known. METHODS: In a prospective double-blind multicenter study in 186 DM2 patients without manifest coronary artery disease and with dyslipidemia, the effect of a 30-week treatment with 10 and 80 mg atorvastatin or placebo on the reduction of hs-CRP levels was measured. RESULTS: Median CRP levels increased with 6.6% in the placebo group and were reduced by 15 and 47%, respectively, with atorvastatin 10 and 80 mg (P<0.001; significantly different from 10 mg atorvastatin and from placebo (P<0.001). Variation in IL-6 and plasma lipids associated for 21 and 8%, respectively, with variation in CRP levels (P<0.001 and P=0.01). Of patients with a baseline CRP level above an arbitrary threshold of 3.0 mg/l, 56% in the 80 mg atorvastatin group reached a level of less than 3.0 mg/l, versus 23% randomized to 10 mg atorvastatin (P<0.01) and 17% in the placebo group (P<0.005). CONCLUSIONS: In DM2 patients high dose atorvastatin induced a strong reduction in CRP levels. The decrease in CRP was mainly independent of effects on lipid lowering and changes in IL-6 levels. The pleiotropic effect of high-dose atorvastatin on inflammation could add to its cardioprotective effect in high-risk patients.

Aged↗
PubMed2003

Decrease of hemostatic cardiovascular risk factors by aggressive vs. conventional atorvastatin treatment in patients with Type 2 diabetes mellitus.

BACKGROUND: Patients with Type 2 diabetes mellitus have increased levels of hemostatic risk variables for cardiovascular disease, such as fibrinogen, von Willebrand factor (VWF), factor (F)VIIa, d-dimer and plasminogen activator inhibitor-1 (PAI-1). OBJECTIVES: To evaluate the effect of aggressive vs. standard dose atorvastatin on hemostatic cardiovascular risk factors in patients with Type 2 diabetes mellitus. PATIENTS AND METHODS: The effect of 30 weeks of treatment with atorvastatin 10 and 80 mg on hemostatic cardiovascular risk factors was assessed in a randomized double-blind placebo-controlled trial on 217 patients with Type 2 diabetes mellitus and dyslipidemia. RESULTS AND CONCLUSIONS: Atorvastatin 10 and 80 mg dose-dependently reduced d-dimer (7.4% and 8.5%, respectively, P for trend = 0.004) and PAI-1 antigen levels (9.0% and 18%, respectively, P for trend = 0.021). Levels of fibrinogen, VWF, tissue-type plasminogen activator and FVIIa were not influenced by atorvastatin. In conclusion, in patients with Type 2 diabetes mellitus, atorvastatin dose-dependently improved the levels of the hemostatic risk variables d-dimer and PAI-1.

Aged↗
PubMed2003

Gall bladder dysmotility: a risk factor for gall stone formation in hypertriglyceridaemia and reversal on triglyceride lowering therapy by bezafibrate and fish oil.

BACKGROUND AND AIM: The aim of this study was to unravel the mechanisms responsible for the increased risk of gall stone disease in hypertriglyceridaemia (HTG) and to compare the effects of triglyceride lowering therapy by bezafibrate and fish oil on determinants of cholelithiasis (biliary lipid composition and gall bladder motility) in HTG patients. PATIENTS AND METHODS: Gall bladder motility (ultrasonography) was studied postprandially and during infusion of cholecystokinin (CCK). Determinants of cholelithiasis and serum lipids were compared between nine HTG patients and 10 age, sex, and body mass index matched normolipidaemic controls. The effects of bezafibrate and fish oil in HTG patients were studied in a randomised cross over trial. RESULTS: HTG patients showed 14-fold higher serum triglyceride (TG) levels than controls. Biliary lipid composition, fasting gall bladder volumes, and CCK levels did not differ between HTG patients and controls. Gall bladder emptying was reduced in HTG patients compared with controls during CCK infusion (-22%) as well as in response to a meal (-37%; both p<0.001). Postprandial CCK levels were significantly higher in HTG patients. Both bezafibrate and fish oil reduced serum TG levels (-68% and -51% v baseline, respectively; both p<0.01). Fasting CCK levels were not affected whereas CCK induced gall bladder emptying increased during bezafibrate (+29%; p<0.001) and tended to increase on fish oil therapy (+13%; p=0.07). Postprandial gall bladder motility improved on bezafibrate and fish oil (+47 and +25% v baseline, respectively; both p<0.02) at least partly due to increased gall bladder sensitivity to CCK (both p<0.05 v baseline). Bezafibrate but not fish oil increased the molar ratio of cholesterol to bile acids (+40%; p</=0.05) but no effects on cholesterol saturation index were seen with either treatment. CONCLUSIONS: We suggest that impaired gall bladder motility occurs in HTG patients due to decreased sensitivity to CCK, which may add to the enhanced risk of gall stone disease in HTG patients. Triglyceride lowering therapy by both fish oil and bezafibrate improve gall bladder dysmotility without adversely affecting biliary cholesterol saturation.

Analysis of Variance↗