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Biomedical subjects

T de Boo

Publications and source records attributed to T de Boo.

At least 37 records · Page 2Linked to original sources
PubMed1995

Urinary prostaglandin and prostaglandin metabolite excretion in patients with essential hypertension or hypertension with renal artery stenosis.

BACKGROUND: Recent studies have reported elevated prostaglandin levels in patients with renal artery stenosis and hypertension. To investigate whether a distinction between essential hypertension and hypertension with renal artery stenosis is possible by measuring eicosanoid excretion, we studied the excretion of these compounds in patients with essential hypertension and in hypertensives with concomitant renal artery stenosis. METHODS: The 24-h urinary excretion of metabolites of prostaglandin I2, prostaglandin E2 and metabolites of thromboxane A2 was sampled under standardised conditions, in 15 patients with essential hypertension and in 15 patients with unilateral renal artery stenosis with hypertension. Also clinical and biochemical characteristics of the subjects were analysed. RESULTS: The patients with renal artery stenosis had significantly lower excretion of prostaglandin I2 than did the essential hypertensive patients. However, the overlap in the values was large, thus not allowing a diagnostic differentiation according to urinary prostaglandin I2 levels. The excretion of prostaglandin E2 and of metabolites of thromboxane A2 showed no significant differences among the groups. CONCLUSIONS: Measurement of urinary prostaglandin or prostaglandin metabolite excretion did not contribute to the non-invasive detection of the presence of a renal artery stenosis in the patients in this study.

Adult↗
PubMed1994

The effects of single oral doses of 17 beta-oestradiol and progesterone on finger skin circulation in healthy women and in women with primary Raynaud's phenomenon.

The effects of sex, the menstrual cycle, oral contraceptives, pregnancy, and the menopause on skin perfusion in healthy women and in patients with Raynaud's phenomenon suggest a role of female sex hormones. However, no clear relation between skin blood flow and circulating concentrations of oestrogens or progestogens has yet been found. The aim of this study was to investigate the effect of orally administered 17 beta-oestradiol and progesterone on finger skin blood flow before and during heat and cold challenge in 17 healthy normotensive women and in 12 women with Raynaud's phenomenon. In each subject standardized finger heating (45 degrees C water bath, 10 min) and cooling tests (15 degrees C water bath, 5 min and 20 min recovery) were performed twice on the second (or third) day of two consecutive menstrual cycles. 17 beta-Oestradiol (9 mg) or progesterone (300 mg) were given before the second test, after a first test with placebo. Both hormonal doses resulted in (high) physiological concentrations. Fingertip skin temperature and laser Doppler flux were measured. There were no significant differences in the test results after placebo and after progesterone. Although values of fingertip skin temperature and laser Doppler flux after 17 beta-oestradiol tended to be higher only the precooling values in the healthy subjects reached significance: fingertip skin temperature respectively with placebo and with oestradiol (mean (SD)): 32.7 (1.0) and 33.1 (0.8) degrees C; laser Doppler flux with placebo and with oestradiol: 33.6 (11.7) and 42.2 (9.5) perfusion units; both P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1993

Circulating soluble tumor necrosis factor receptors, interleukin-2 receptors, tumor necrosis factor alpha, and interleukin-6 levels in rheumatoid arthritis. Longitudinal evaluation during methotrexate and azathioprine therapy.

OBJECTIVE: To assess whether circulating concentrations of soluble tumor necrosis factor receptors (sTNFR; p55 and p75), soluble interleukin-2 receptors (sIL-2R), tumor necrosis factor alpha (TNF alpha), and interleukin-6 (IL-6) reflect clinical response and whether changes are dependent on the drug used in rheumatoid arthritis (RA) patients taking methotrexate (MTX) or azathioprine (AZA). METHODS: These cytokines and soluble receptors were assessed in 20 control subjects and serially for up to 48 weeks in 61 RA patients, by bioassay (IL-6) and immunoassays (sTNFR, sIL-2R, TNF alpha, and IL-6). RESULTS: Concentrations of p55 and p75, sIL-2R, and TNF alpha (but not IL-6) were significantly higher in RA patients than in controls. Significant decreases in sIL-2R and p55 concentrations were associated with clinical improvement and were observed in patients treated with MTX, but not AZA. Both treatments induced decreases in IL-6 concentrations, but circulating AZA (or its metabolites) appears to interfere with the measurement of IL-6 bioactivity. TNF alpha and p75 levels did not show significant changes. CONCLUSION: Measurement of circulating sIL-2R, p55, and IL-6 may be useful in the evaluation of RA disease activity and response to therapy. Interference by circulating levels of drugs must be ruled out when bioassays are used to evaluate cytokine levels.

Arthritis, Rheumatoid↗
PubMed1993

A standardized finger cooling test for Raynaud's phenomenon: diagnostic value and sex differences.

In 99 patients with primary Raynaud's phenomenon (RP), in 97 with secondary RP and in 101 healthy subjects, finger skin temperature and laser Doppler flux were measured before, during and after immersion of the hand in a 16 degrees C water bath. We determined the baseline value, the values at the end of the cooling period and after 12 and 20 min of recovery, the percentual decrease during cooling and the mean values during cooling, during recovery and during the whole test. Most of the finger skin temperature and laser Doppler flux parameters were significantly lower in females than in males in all three groups. There were no significant differences between patients with either primary or secondary RP. In both sexes, all test parameters (with the exception of the percentual decrease during cooling) were significantly lower in the patients with RP than in healthy subjects. With a diagnostic specificity of 70%, the sensitivity varied between 55% and 81% for the different test parameters. Although, in both sexes, finger skin temperature and laser Doppler flux values before, during and after cooling were significantly lower in patients with RP than in healthy subjects, the considerable overlap between both groups limits the diagnostic value in individual cases.

Adult↗
PubMed1992

Factors affecting magnitude and time course of neuromuscular block produced by suxamethonium.

This study was designed to identify factors that significantly alter the magnitude and duration of suxamethonium-induced neuromuscular block in patients with an apparently normal genotype for pseudocholinesterase. One hundred and fifty-six adults (ages 18-65 yr) were allocated to 13 subgroups. Patients in each subgroup received suxamethonium 50-2000 micrograms kg-1. The mechanographic response of the adductor pollicis brevis muscle to ulnar nerve stimulation was recorded. The ED50 was found to be 167 micrograms kg-1, ED90 was 316 micrograms kg-1 and ED95 was 392 micrograms kg-1. The duration of action (delta t) was in agreement with earlier published results. The magnitude of block was dose-related and decreased with increasing onset time (ton) and pseudocholinesterase activity (PChA). Neither age nor gender affected the degree of suxamethonium-induced block. Delta t was dose-related, decreased with increasing PChA, and was shorter for women. Age and ton had no effect on delta t.

Adolescent↗
PubMed1992

Research in 'prostatitis syndromes': the use of alfuzosin (a new alpha 1-receptor-blocking agent) in patients mainly presenting with micturition complaints of an irritative nature and confirmed urodynamic abnormalities.

A double-blind, placebo-controlled study in 20 patients with 'prostatitis syndromes' and confirmed urodynamic abnormalities using the alpha 1-receptor-blocking compound alfuzosin is reported. Flow rate recordings are probably the most reliable and useful objective variables in this type of investigation. There is a significant beneficial effect in the group using an active compound concerning maximal flow (p = 0.01), flow time (p = 0.03) and time to maximal flow (p = 0.01). However, compared with the group using a placebo, only the change in the maximal flow rate appeared to be significantly different. Subjective effects were more pronounced in the alfuzosin group, but the spurious nature of the subjective observations is stressed. Based on objective parameters, alfuzosin seems to be effective compared to placebo in the treatment of these patients with micturition complaints of an irritative nature and urodynamic abnormalities, while only minor side effects were noticed.

Adrenergic alpha-Antagonists↗
PubMed1992

Immunoglobulin G, A and M light chain ratio in children.

Values for the kappa/lambda light chain ratio in immunoglobulins G, A and M and the total kappa/lambda ratio, measured by enzyme linked immunosorbent assay, were evaluated in serum samples from different age groups (114 children, aged from 1 month to 15 years, and 20 adults). The IgG kappa/lambda ratio decreased in the first 6 months and subsequently increased slowly during childhood towards the adult value of 2.0. The IgM kappa/lambda ratio increased at a greater rate than IgG kappa/lambda ratio in the first years of life and thereafter rose slightly throughout childhood to reach an adult value of 1.7. A decreasing IgA kappa/lambda ratio was found from 1 month of age onwards to an adult value of 1.1. The pattern of total kappa/lambda ratio was similar to the IgG kappa/lambda ratio with an adult value of 2.0.

Adolescent↗
PubMed1992

Doppler ultrasound scanning in the detection of renal artery stenosis in hypertensive patients.

The diagnostic accuracy of Doppler ultrasound in the detection of renal arterial disease has been assessed in a prospective study of 61 hypertensive patients. The findings of Doppler ultrasound were compared with the results of renal angiography. In 15 patients (24.5%) no accurate Doppler signs could be obtained and the Doppler ultrasound examination was considered a technical failure. Of the remaining 46 patients, 24 had renal artery stenosis. Nine of the stenoses were not detected by Doppler ultrasound and in three patients a false positive diagnosis of renal artery stenosis was made. The sensitivity of Doppler ultrasound was 62.5%, the specificity 86.4% and the overall diagnostic accuracy was 73.9%. By comparing the 15 patients in whom Doppler ultrasound failed with the 46 in whom it was successful, age appeared to be higher and creatinine clearance lower in the failure group. By comparing the 34 patients with true positive and true negative results with the 12 patients with false results, no significant differences were found. In a multivariate analysis, higher age showed a significant relation to failure of Doppler ultrasound. Doppler ultrasound has limited value in the screening of hypertensive patients for renal artery stenosis.

Female↗
PubMed1992

First dose hypotension after captopril; can it be predicted? A study of 240 patients.

We have studied prospectively the acute blood pressure lowering effect on an oral dose of captopril, 25 mg in 240 hypertensive patients. The mean relative reduction of systolic and diastolic BP was 16 and 15% respectively and the mean time to the mean arterial pressure nadir was 59 minutes. Systolic BP fell by more than 30% in 4.6% of patients and diastolic BP and mean arterial pressure dropped by more than 30% in 4.2 and 3.3% of patients respectively. Patients over 60 years of age showed a significantly larger fall in systolic and diastolic BP. Patients with renal artery stenosis reached the BP nadir in a significantly shorter time compared with patients with essential hypertension (50.5 vs. 59.7 minutes, P less than 0.05) and showed a significantly larger fall in systolic BP (20.7 vs. 15.4%, P less than 0.05). A forward stepwise regression analysis showed that only baseline plasma renin activity had a significant relation to the fall in BP (P less than 0.01, R = 0.57). We conclude that according to our definition of a greater than 30% decrease of the mean arterial pressure, a first dose hypotension after captopril was seen in 3.3% of 240 patients. Captopril treatment should be introduced carefully since not all those patients at risk of hypotension can be identified in advance.

Aldosterone↗
PubMed1991

Determination of kappa and lambda light chains in serum immunoglobulins G, A and M.

An enzyme-linked immunosorbent assay is described for measuring kappa and lambda light chains within each of the serum immunoglobulin classes G, A and M. The detection limit was 0.06 U/L for total IgG, IgG kappa and IgG lambda, 0.2 U/L for total IgA, IgA kappa and IgA lambda and 0.5 U/L for total IgM, IgM kappa and IgM lambda. The concentrations of kappa plus lambda light chains from the three different immunoglobulins correlated well within those of total immunoglobulin G, A and M as measured by enzyme-linked immunosorbent assay or by immunonephelometry. Adult values for the kappa/lambda light chain ratio were found to be 2.0 for IgG kappa/lambda, 1.1 for IgA kappa/lambda and 1.7 for IgM kappa/lambda.

Adolescent↗
PubMed1991

The value of tests predicting renovascular hypertension in patients with renal artery stenosis treated by angioplasty.

The aim of this study was to evaluate tests predicting renovascular hypertension. This was done by relating the results of renal vein renin tests, the captopril test, and renal scintigraphic tests to the blood pressure outcome 12 months after relief of renal artery stenosis by percutaneous transluminal renal angioplasty in 31 patients. Cure was seen in eight (26%). Improved blood pressure was obtained in 12 patients (39%), and in 11 patients (35%), the result for blood pressure was a failure. The accuracies of the two mathematical models used to analyze the renal vein renin assays were 44% and 60%. The captopril test showed a sensitivity of 36% and an accuracy of 43%. Renal captopril technetium Tc 99m-labeled pentetic acid scintigraphy gave a sensitivity of 60%. Stepwise logistic regression analysis of clinical variables in relation to blood pressure response revealed age as the only factor significantly related to blood pressure outcome. We conclude that the tests used are unfit for helping select patients for percutaneous transluminal renal angioplasty and that age may have an important influence on outcome.

Adolescent↗
PubMed1990

Hemodynamic effects of atrial natriuretic factor in young and elderly subjects.

Because levels of plasma atrial natriuretic factor (ANF) increase with advancing age, a diminished hemodynamic responsiveness to ANF in the elderly has been hypothesized in the literature. Therefore hemodynamic effects after two infusion rates (0.25 and 2.0 micrograms/min) of atrial natriuretic factor (99-126) were investigated in young (n = 8) and elderly (n = 9) volunteers in a double-blind, randomized, and placebo-controlled protocol. After low-rate infusion, ANF concentrations increased to the upper normal range, and only minor effects were observed. In contrast, high-rate infusion resulted in a decrease in blood pressure and forearm vascular resistance, whereas an increase in heart rate was observed in both groups. Between young and elderly subjects, a significant difference was observed in the ANF-induced decrease in systolic blood pressure (mean +/- SD, -4% +/- 4% versus -12% +/- 7%, p less than 0.05) and mean arterial pressure (-6% +/- 5% versus -11% +/- 4%, p less than 0.05) during the high rate infusion. When compared with the concentrations of the young subjects, the ANF concentrations reached at both ANF dosages were higher in the elderly subjects; this was the result of a diminished ANF clearance in the elderly subjects. After correction of the changes of systolic blood pressure and mean arterial pressure for the higher ANF levels reached within this elderly group, no difference between young and elderly subjects remained. We conclude that a diminished cardiovascular responsiveness to ANF with advancing age could not be demonstrated. In contrast, the high-rate infusion of ANF induced an increased hemodynamic response in the elderly subjects, but this seems to be the result of the higher ANF levels reached within this group.

Adult↗
PubMed1990

The captopril test in the detection of renovascular disease in hypertensive patients.

A number of reports share the conclusion that the captopril test is an adequate screening procedure for the detection of renovascular disease among hypertensive patients. Therefore, we prospectively studied the value of this test in 149 consecutive hypertensive patients. The test was considered positive if plasma renin activity, after an oral dose of 25 mg of captopril, rose by more then 4.44 ng.L-1.s-1 (16.0 ng/mL per hour). The sensitivity of the test was 39%, the specificity was 96%, the positive predictive value was 81%, and the negative predictive value was 79%. No clinically important cutoff point identifying patients with renal artery stenosis could be detected in the values of baseline and stimulated plasma renin activity nor in baseline blood pressure or changes after captopril testing. The low sensitivity makes the captopril test unfit to be used as a screening procedure in an unselected hypertensive population.

Captopril↗
PubMed1990

Reference values of magnesium and potassium in mononuclear cells and erythrocytes of children.

Reference values for magnesium and potassium contents of mononuclear cells and erythrocytes were estimated in cord blood and in children from infancy through adolescence. No differences were detected between results for boys and girls. The mononuclear magnesium content was independent of age and was within the adult range of values. No significant correlation was shown between magnesium in serum and in mononuclear cells. Mononuclear potassium also showed no age-related differences. The correlation between magnesium and potassium contents in mononuclear cells was significant: however, the correlation was lower when the magnesium and potassium contents were expressed in terms of protein potent: micromoles or millimoles per gram of protein, respectively. The concentration of magnesium in erythrocytes was significantly lower in cord blood and during the first month of life, compared with that at older ages, and showed no significant correlation with serum magnesium. The concentration of erythrocyte potassium was independent of age and showed a low but significant correlation with erythrocyte magnesium content.

Adolescent↗
PubMed1989

[Hypotension following a one-time (initial) dose of captopril].

In a group of 269 untreated hypertensive patients the effect of a single oral dose of captopril (25 mg) on blood pressure was studied for 90-120 minutes. The systolic blood pressure decreased by more than 20% in 9.5% and by more than 30% in 1.1% of the patients. In 22.6% the diastolic blood pressure decreased by more than 20%; in 4.5% it fell more than 30%. The calculated mean arterial pressure (MAP) was reduced by more than 20% in 12.3% of the patients and by more than 30% in 3%. Three patients showed transient neurological deficits. Factors related to a strong blood pressure drop were: renal artery disease and resistant hypertension. However, a potentially dangerous fall in blood pressure, i.e. an acute fall of MAP of over 30%, was also observed in the absence of these risk factors. Therefore not all patients at risk can be identified in advance, and treatment with ACE-inhibitors has to be started under well-controlled circumstances especially in elderly patients.

Adult↗
PubMed1989

The influence of heart rate and age on diastolic blood flow velocity in the left ventricular inflow tract.

To investigate the relationship between age-related blood flow velocity and heart rate in the left ventricular inflow tract, we studied 118 healthy volunteers (age greater than 15 years). The maximal velocity (Vmax) of the transmitral diastolic flow during early ventricular filling (E) and during filling due to atrial contraction (A) was measured at 3 sites in the left ventricle with pulsed Doppler echocardiography. At all these sites a significant positive correlation was found between the VmaxA and the EA ratio and the interaction of heart rate and age. VmaxA increases if age and heart rate increase. The influence of the interaction of age and heart rate on VmaxA is most pronounced near the mitral annulus. VmaxA is only related to age and decreases with advancing age. Our observations contribute to the explanation of the more important role of the atrial contraction in the elderly.

Adolescent↗
PubMed1989

Disparate effects of mental stress on plasma noradrenaline in young normotensive and hypertensive subjects.

The response of blood pressure, heart rate and plasma catecholamines to a mental arithmetic and a cold pressor test was studied in 70 patients with mild essential hypertension and in 41 age- and sex-matched normotensives. Each group consisted of three prospectively stratified age classes: 20-29, 30-39 and 40-55 years. During mental arithmetic, hypertensives showed only a higher increment of systolic blood pressure (+17-19%) than normotensives (+12-15%). Plasma noradrenaline in the youngest normotensives (20-29 years) showed a small but significant decrease (-0.20 +/- 0.07 nmol/l) whereas the youngest hypertensives showed a small but significant increase of plasma noradrenaline (+0.14 +/- 0.04 nmol/l). The difference between both groups was highly significant (P less than 0.001). In the two older age classes there was no difference in plasma noradrenaline response between normo- and hypertensives. During the cold pressor test both the cardiovascular and plasma noradrenaline response were of the same magnitude in normo- and hypertensives. These data reinforce the concept that the increased sympathetic reactivity to mental stress in hypertensives may be restricted to the younger age.

Adult↗