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W F Riesen

Publications and source records attributed to W F Riesen.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effect of thyroid function on concentrations of lipoprotein(a)

The effect of thyroid hormones on concentrations of lipoprotein(a) [Lp(a)] was analyzed in 60 patients with active thyroid dysfunction (hyperthyroidism 30 cases, hypothyroidism 32 cases, and 2 cases with opposite changes) and after normalization of the thyroid state. Treatment of hyperthyroidism increased the mean Lp(a) concentrations by 60% (from 73 to 102 mg/L, P < 0.002); at the same time, low-density lipoprotein cholesterol (LDL-C) increased by 53% (from 2.6 to 3.7 mmol/L, P < 0.0001) and apolipoprotein B (apo B) by 35% (from 0.91 to 1.17 g/L, P < 0.0005). In hypothyroidism, the opposite changes were observed: mean Lp(a) decreased from 136 to 114 mg/L (10%, P < 0.02), LDL-C from 4.6 to 3.9 mmol/L (13%, P < 0.01), and apo B from 1.51 to 1.20 g/L (14%, P < 0.01). Although the changes in Lp(a) concentrations did correlate with changes of LDL-C during treatment of hyperthyroidism (r = 0.43, P < 0.05), and with changes in apo B during thyroxine-substitution therapy for hypothyroidism (r = 0.46, P < 0.05), we observed no associations between Lp(a) and LDL-C or apo B in the euthyroid state. These data cannot rule out the possibility that the thyroid hormone-induced increase in LDL-C receptor activity was responsible for the decreased concentrations of Lp(a) in hyperthyroidism. Given that LDL-C is approximately 30% of the Lp(a) molecule but the changes in Lp(a) concentrations are comparable with those in LDL-C (60% vs 53%), and given that Lp(a) is metabolized by an LDL-C-receptor-independent pathway, the present data suggest a direct effect of thyroid hormones on Lp(a) synthesis.

Adult↗
PubMed1993

Development and evaluation of a reagent carrier with a new reaction sequence for the determination of creatinine in blood, plasma, serum and urine.

After a short outline of the history of creatinine determination methods we describe the development of a dry-reagent-carrier system for the reflometric determination of the creatinine concentration in blood, plasma, serum and urine (Reflotron Creatinine (new)). The method is based on a sequence of enzymatically catalyzed reactions producing H2O2, but which in contrast to the previously used procedure do not lead to the formation of creatine as an intermediate. Hence, pretreatment of sample material to eliminate endogenous creatine is no longer necessary. In the indicator reaction, use is made of an imidazole derivative as the chromogen. The dye formed in the presence of peroxidase can be measured by reflectance photometry beyond the long-wave absorption bands of haemoglobin and bilirubin at 642 nm. We present in detail the results of the multicentre evaluation of the analytical properties of this new test principle. The data obtained show that Reflotron Creatinine (new) correlates well with the routine method Creatinine PAP, which was used as a comparison method, with respect to accuracy and precision and even surpasses it with respect to specificity. Advantages over the first generation of Reflotron Creatinine are: shorter reaction time, longer stability of the reagent carrier, no interference by bilirubin and reduced interference by haemoglobin.

Blood Chemical Analysis↗
PubMed1993

Multicenter evaluation of Reflotron direct dry-chemistry assay of high-density lipoprotein cholesterol in venous and fingerstick specimens.

The Reflotron HDL Cholesterol test (Boehringer Mannheim GmbH) directly separates and analyzes high-density lipoprotein (HDL) cholesterol in plasma collected with EDTA in an integrated dry-reagent system suitable for alternative site testing of lipoproteins. We describe a multicenter evaluation of this test by two US and six European laboratories experienced in lipid analysis. Each laboratory compared the Reflotron with the same conventional wet-chemistry method, Boehringer phosphotungstate-Mg2+ precipitation with enzymatic cholesterol assay. Imprecision was within accepted guidelines, with CVs of < or = 8% for fresh and frozen plasmas (median CV 1.7-3.9%) and for lyophilized sera (median CV 3.8-4.7%), similar to those of the conventional method. Results of linear-regression analysis were as follows: Reflotron HDL Cholesterol = 1.03 conventional - 3.9 mg/L, r = 0.987. The Reflotron results were somewhat low in the two US laboratories, demonstrating the need for general standardization of methods for measuring HDL cholesterol. Results from capillary fingerstick plasma agreed well with those from venous-derived plasma; capillary = 1.04 venous + 4.5 mg/L, r = 0.967. The system is relatively insensitive to interference from hemoglobin (< or = 0.75 g/L), ascorbic acid (< or = 0.3 g/L), bilirubin (< or = 50 mg/L), cholesterol (< or = 3.5 g/L), and triglycerides (< or = 4 g/L). The relative ease of operation and the rapid availability of results (within 90 s for plasma collected in EDTA) make the method appropriate for use by well-trained, but not necessarily technical, operators in the physician's office or other alternative sites.

Aminopyrine↗
PubMed1992

[Diagnostic value of autoantibodies against microsomal thyroid peroxidase (anti-TPO)].

With the identification of thyroid peroxidase (TPO) as the main antigen of the thyroid microsomal fraction, the development of a sensitive and specific assay for detection of these antibodies became possible. The diagnostic value of the anti-TPO assay was evaluated in patients with different types of thyroid disease and in controls. 65% of patients with thyroiditis had elevated anti-TPO values. The frequency of elevated anti-TPO levels in patients with active autoimmune thyroiditis was 90% (clinical diagnosis Hashimoto thyroiditis) compared to 64% in patients with overt hyperthyroidism (clinical diagnosis Graves' disease). None of the controls or the patient with non-thyroidal illness showed elevated anti-TPO levels.

Autoantibodies↗
PubMed1992

[Current strategies in the diagnosis and therapy of hyperlipoproteinemias].

The determination of total cholesterol (and eventually triglycerides) is sufficient for screening purposes. Values below 5.2 mmol/l (200 mg/dl) may be considered ideal, where as higher values need a differentiated diagnostic evaluation which should include the measurement of triglycerides and of HDL-cholesterol after 12 h fasting. The decision for a drug therapy should consider other risk factors such as hypertension, smoking, diabetes mellitus, male sex, positive family anamnesis for myocardial infarction already existing and coronary heart disease. The treatment of a dyslipoproteinemia should always start with dietary measures. If these are not successful, a lipid-regulating drug therapy should be started in addition to the diet. The choice of the drug depends on the type of dyslipoproteinemia and its genetic and metabolic cause and on the individual side effects.

Cholesterol↗
PubMed1992

Insulin-like growth factor-I improves glucose and lipid metabolism in type 2 diabetes mellitus.

Hyperglycemia, hyperinsulinemia, and insulin resistance cause vascular disease in type 2 diabetes mellitus. Dietary treatment alone often fails and oral drugs or insulin enhance hyperinsulinemia. In previous studies, an intravenous bolus of recombinant human insulin-like growth factor-I (rhIGF-I) caused normoglycemia in insulin-resistant diabetics whereas rhIGF-I infusions lowered insulin and lipid levels in healthy humans, suggesting that rhIGF-I is effective in insulin-resistant states. Thus, eight type 2 diabetics on a diet received on five treatment days subcutaneous rhIGF-I (2 x 120 micrograms/kg) after five control days. Fasting and postprandial glucose, insulin, C-peptide, proinsulin, glucagon, triglyceride, insulin-like growth factor-I and -II, and growth hormone levels were determined. RhIGF-I administration increased total IGF-I serum levels 5.3-fold above control. During the control period mean (+/- SD) fasting glucose, insulin, C-peptide, and total triglyceride levels were 11.0 +/- 4.3 mmol/liter, 108 +/- 50 pmol/liter, 793 +/- 250 pmol/liter, and 3.1 +/- 2.7 mmol/liter, respectively, and decreased during treatment to a nadir of 6.6 +/- 2.5 mmol/liter, 47 +/- 18 pmol/liter, 311 +/- 165 pmol/liter, and 1.6 +/- 0.8 mmol/liter (P < 0.01), respectively. Postprandial areas under the glucose, insulin, and C-peptide curve decreased to 77 +/- 13 (P < 0.02), 52 +/- 11, and 60 +/- 9% (P < 0.01) of control, respectively. RhIGF-I decreased the proinsulin/insulin ratio whereas glucagon levels remained unchanged. The magnitude of the effects of rhIGF-I correlated with the respective control levels. Since rhIGF-I appears to improve insulin sensitivity directly and/or indirectly, it may become an interesting tool in type 2 diabetes and other states associated with insulin resistance.

Adult↗
PubMed1992

Swiss hypertension treatment programme with verapamil and/or enalapril in diabetic patients.

The purpose of the present study was to assess the efficacy and tolerability of diuretic-free antihypertensive therapy with a calcium antagonist and/or an angiotensin converting enzyme (ACE) inhibitor in patients with diabetes mellitus. 54 hypertensive [blood pressure (BP) above 140/90mm Hg] patients with diabetes mellitus type 1 (n = 7) or 2 (n = 47) and normal serum creatinine levels (mean 82 +/- 6 mumol/L) received either verapamil or enalapril after a 2-week washout and a 4-week placebo phase. If BP remained elevated, both agents were combined. Verapamil or enalapril alone normalised diastolic BP (to less than 90mm Hg) in 36 patients; verapamil decreased BP from 159/98 to 147/87mm Hg (n = 19, p < 0.001) and enalapril decreased BP from 166/99 to 146/88mm Hg (n = 17, p < 0.001). In 18 patients who remained hypertensive after 10 weeks of monotherapy, a combination of both drugs decreased BP from 169/104 to 151/90mm Hg (p < 0.001). Overall, 87% of patients achieved a target BP response at 30 weeks. Urinary albumin as related to creatinine excretion (UAE; micrograms albumin:mg creatinine) was on average not significantly changed after verapamil or enalapril treatment, alone or combined. Nevertheless, in patients with initial microalbuminuria, UAE decreased (p < 0.05) during enalapril treatment. Serum potassium, total lipids, high density lipoprotein cholesterol, low density lipoprotein cholesterol, glycosylated haemoglobin, serum C peptide and fructosamine levels were not significantly modified by treatment. Subjective tolerability of the drugs was also generally good. Thus, in hypertensive patients with diabetes, a diuretic-free therapy based on the calcium antagonist verapamil or the ACE inhibitor enalapril, alone or combined, can effectively decrease BP without adversely affecting carbohydrate and lipid metabolism.

Adolescent↗
PubMed1991

[Lipoprotein (a)--link between lipid metabolism and coagulation system?].

Lipoprotein(a) is a dimer consisting of one low density lipoprotein molecule joined by a disulfide bridge to apolipoprotein(a). Apo(a) shows a considerable structural homology to plasminogen, the zymogen of the proteolytic enzyme plasmin, which dissolves fibrin clots. Apo(a) may compete with plasminogen in several manners, but itself displays no proteolytic activity. It therefore may potentially interfere with fibrinolysis. On the other hand it may also be atherogenic, as indicated by its presence in atherosclerotic plaques. Although lipoprotein(a) consists of one molecule of LDL it does not appear to be regulated by the same mechanism as LDL. Likewise, cholesterol feeding does not appear to increase levels of Lp(a), although it does increase levels of LDL cholesterol. In addition, most lipid regulating drugs that do have an effect on lowering LDL cholesterol levels have little effect on Lp(a) thus also indicating regulation under different metabolic control. Lp(a) seems to constitute a genetic risk factor for coronary atherosclerosis which is independent of all other parameters and of exogenous factors.

Apolipoproteins A↗
PubMed1991

[Effects and side effects of a 1-year treatment of primary hypercholesterolemia with simvastatin].

The HMG-CoA-reductase inhibitors lovastatin, pravastatin and simvastatin (statins) represent a new group of drugs for the treatment of hypercholesterolemia. The present study was performed with simvastatin, the first statin introduced in Switzerland, and involved 46 patients with primary hypercholesterolemia during one year. The dose of simvastatin was adjusted according to the serum cholesterol level; during treatment with 10, 20 and 40 mg, total cholesterol was lowered by 18, 26 and 27% respectively and LDL cholesterol by 27, 38 and 35% respectively, after one year. A combination of 40 mg simvastatin with a bile acid sequestrant or a nicotinic acid derivative resulted in a cholesterol lowering of 38% and an LDL lowering of 48% respectively. The serum triglycerides decreased only at a dose of 10 mg. The changes in LDL and HDL cholesterol were accompanied by parallel alterations in apoprotein B and A1 concentrations. Although none of the patients showed a significant increase (greater than 3 x UNL) in serum ASAT, ALAT or CK, all these values increased slightly but significantly. Tolerance of the drug was otherwise excellent; gastrointestinal side effects were only rarely reported. Therefore, simvastatin is an effective and well tolerated cholesterol-lowering drug. Whether prevention of coronary heart disease is possible, however, is not yet proven.

Anticholesteremic Agents↗
PubMed1991

Antihypertensive therapy with Ca2+. Antagonist verapamil and/or ACE inhibitor enalapril in NIDDM patients.

OBJECTIVE: To assess the efficacy and tolerance of a diuretic-free antihypertensive therapy with a Ca2+ antagonist and an angiotensin-converting enzyme (ACE) inhibitor in patients with non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: After a 2-wk washout and a 4-wk placebo phase, 47 hypertensive patients with NIDDM randomly received verapamil or enalapril alone and, if blood pressure remained elevated, both agents combined over 30 wk. RESULTS: Verapamil or enalapril alone normalized blood pressure to less than 90 mmHg diastolic in 30 patients; verapamil decreased mean +/- SE blood pressure from 159/98 +/- 3/1 to 146/87 +/- 3/2 mmHg (n = 18, P less than 0.001) and enalapril from 166/99 +/- 5/2 to 146/86 +/- 3/1 mmHg (n = 12, P less than 0.001). In 17 patients who were still hypertensive after 10 wk of monotherapy, combination of both drugs decreased blood pressure from 170/104 +/- 4/2 to 152/90 +/- 4/2 mmHg (P less than 0.001). Fasting plasma glucose, glycosylated hemoglobin, serum fructosamine, total lipids, high-density and low-density lipoprotein cholesterol, apolipoproteins A-I and B, creatinine, and urinary albumin-creatinine ratio were not significantly modified. CONCLUSIONS: In hypertensive patients with NIDDM, a diuretic-free therapy based on the Ca2+ antagonist verapamil and/or the ACE inhibitor enalapril can effectively decrease blood pressure without adversely affecting carbohydrate and lipid metabolism.

Blood Glucose↗
PubMed1991

Fifteen-year changes in exercise, aerobic power, abdominal fat, and serum lipids in runners and controls.

To describe effects of past as well as current exercise, aerobic power, and subcutaneous fat on the serum lipid profile, two groups of former elite athletes (N = 27 runners, N = 9 bobsledders) and a control group of normal men (N = 23) were investigated. Analysis of variance indicated a significant effect of the type of sports activity on HDL cholesterol, apolipoprotein A-I, and triglyceride levels and on the LDL/HDL cholesterol and apolipoprotein B/A-I ratios, with the most favorable values seen in runners and the least favorable values seen in controls. Of the 27 former elite runners, one third (N = 9) had given up or strongly reduced training. This subgroup showed the steepest 15-yr decrease (from 1973 to 1988) in maximum aerobic power and the largest 15-yr increase in subcutaneous fat, and the lipid profile (measured in 1988) corresponded more to the one of bobsledders and controls than to the one of runners who had remained active. Separate correlational analyses of all runners (N = 27) and nonrunners (N = 32) showed that, in both cohorts, i) the 1988 measurements of exercise, aerobic power, and subcutaneous fat were more predictive for the lipid profile in 1988 than the corresponding 1973 values, ii) anthropometric characteristics, especially abdominal fat, had a stronger relation with serum lipid concentrations than exercise and aerobic power, and iii) 15-yr changes in anthropometric characteristics were, but 15-yr changes in exercise and aerobic power were not, associated with triglyceride, lipoprotein, and apolipoprotein levels in 1988.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1990

[How reliable is the Reflotron-HDL-cholesterol determination method?].

The newly introduced Reflotron-HDL-cholesterol determination was compared with conventional precipitation by phosphotungstate/Mg2+ and quantitation of HDL cholesterol in the supernatant by means of the CHOD PAP method. Accuracy and precision were analyzed by means of three different control materials (Precinorm L, Kontrollogen LP, Reflotron-HDL-Precinorm), which were assessed daily in multiple determinations (n = 10 and 5 respectively) for 5 days. In addition, 100 patient samples, (EDTA plasma) which covered a range from 0.35 to 2.50 mmol/l were compared by both methods. The values of the control sera gave a difference of less than 5% from the target values, and the values from the patients' samples showed less than 3% difference between the two methods. The precision within series was always below 6.5%, and the interassay precision below 3.2%. Reflotron-HDL cholesterol determination appears to meet quality requirements on condition that it is performed by well-trained laboratory personnel.

Cholesterol, HDL↗
PubMed1990

Therapeutic efficacy of the HMG-CoA-reductase inhibitor pravastatin in hyperlipoproteinaemia type II.

The efficacy and safety of the HMG-CoA-reductase inhibitor pravastatin was assessed in a double-blind, placebo controlled study. Thirty patients (51 y) with hyperlipoproteinaemia Type IIa (N = 22) or IIb (N = 8) received for 16 weeks either pravastatin 5 mg b.d. for 8 weeks followed by 10 mg b.d. for 8 weeks (Group I), or 10 mg b.d. for 8 weeks followed by 20 mg b.d. to 16 weeks (Group II), or placebo (Group III). In Groups I and II, mean serum total cholesterol was reduced by -26% and -22%, respectively; low-density lipoprotein (LDL)-cholesterol decreased by -28% and -27%, apolipoprotein B by -25% and -23%, and apolipoprotein E by -9% (NS) and -16%, respectively. Serum high-density lipoprotein (HDL)-cholesterol was increased by 11% in Group II, and so the total/HDL-cholesterol ratio fell by 33%. Apoprotein A1 and A2 were not significantly changed. No serious clinical and laboratory abnormalities were observed. The data suggest considerable therapeutic efficacy of pravastatin in the treatment of Type II hyperlipoproteinaemia.

Anticholesteremic Agents↗
PubMed1990

Effects of long-term, self-monitored exercise on the serum lipoprotein and apolipoprotein profile in middle-aged men.

To study the effects of long-term, self-monitored exercise on the serum lipid profile and body composition of middle-aged non-smoking males, a controlled study was conducted in 61 sedentary, middle-class Swiss men. Thirty-nine men were randomly allocated to jog 2 h/wk for 4 months on an individually prescribed, heart rate-controlled basis, whereas 22 men served as controls. Despite varying adherence to the exercise regimen, the following 4-month net changes (effect in exercise group minus effect in control group) in lipids were seen: HDL cholesterol (C) +0.12 mmol/l (95% CI 0.02, 0.22; P = 0.028), LDL-C +0.08 mmol/l (ns), VLDL-C -0.26 mmol/l (-0.45, -0.07; P = 0.009), total triglycerides (TT) -0.21 mmol/l (ns), HDL-C/total C +0.02 (0.001, 0.05; P = 0.047). The net changes in endurance capacity and resting heart rate in favour of exercisers were significant as well, whereas no significant changes in apolipoprotein levels were seen. Exploratory analyses revealed, for example, associations of the increase in total physical activity with an increase in the HDL-C/total C ratio (r = 0.46; P less than 0.001), and of the change in estimated body fat content with an opposed change in the HDL-C/total C ratio (r = -0.40; P less than 0.001), or an inverse relationship of the change in subcutaneous fat with a change in the HDL2-C level (r = -0.39; P less than 0.001). Multivariable regression analysis suggested that much of the effect of jogging on HDL-C was apparently mediated through a decrease in body fat content. A change in the waist/hip ratio was unrelated to lipoprotein changes but was related to the change of TT level (r = 0.22; P less than 0.05). This study confirms that individually prescribed, unsupervised jogging can increase HDL-C levels and improve the serum lipoprotein profile in self-selected nonsmoking males. Although the effect is modest, it may be relevant to preventive cardiology, given the evidence for a reduction in cardiovascular risk even after apparently small decreases in risk factor levels.

Age Factors↗
PubMed1990

Lipid screening in paediatrics for early detection of cardiovascular risks.

The purpose of the study was to try to detect at an early stage the important cardiovascular risk factors associated with increased concentrations of blood lipids, notably cholesterol. The trial was based on the screening of 102 families, including 219 children, 8-18 years of age and their parents. A group of young adults, 19-25 years of age, was included in the study. All subjects were derived from a paediatric practice. In addition to total cholesterol, VLDL-, LDL-, HDL-cholesterol and apolipoproteins A-I and B were also measured. The study identified a significant number of school-children and adolescents with hyperlipidaemia, predominantly hypercholesterolaemias type II-A. There was a close relationship between their blood lipids and those of their parents. The study demonstrates the importance of including parents in studies of this kind. Total cholesterol proved to be a reliable parameter for screening. The value of apolipoproteins in such screening is discussed.

Adolescent↗
PubMed1990

[The determination of apolipoproteins Apo A-I and Apo B. A comparative study of methods].

We compared the analytical performance of a new in house developed ELISA and the commercial TurbiTime system for the determination of Apo AI and Apo B. Six dilutions of a poolserum, whose concentration had been determined by two other independent methods, were used as test material. A serum from which the apolipoproteins had been removed by immunadsorption was used as a diluent. Six specimens with known true values of Apo AI and Apo B were thus prepared. We established the analytical precision, the regression function and the correlation with respect to the true values and we constructed precision profiles and bias profiles. We found that the precision of turbidimetry is superior for the determination of Apo AI with concentrations less than 1 g/l. With Apo B both systems are nearly equivalent, the results of the turbidimetric methods were a little too low, the results of the ELISA a little too high. Below a concentration less than 0.5 g/l both methods are unreliable.

Apolipoprotein A-I↗