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Biomedical subjects

T de Boo

Publications and source records attributed to T de Boo.

At least 55 records · Page 3Linked to original sources
PubMed1989

Occlusion of unilateral stenosed renal arteries--relation to medical treatment.

In 78 patients we studied retrospectively the occurrence of occlusion in unilateral renal artery stenosis during antihypertensive drug treatment. Complete occlusion occurred in 14 patients (18%). In a multivariate analysis the following characteristics were included: blood pressure, aetiology of the stenosis, serum creatinine, the degree of the stenosis, anti-hypertensive medication, standing renal vein renin ratio and age. In this analysis the combination of a diuretic and an ACE-inhibitor, during the observation period, showed an independent relation to the development of an occlusion (P less than 0.05). Also the ACE-inhibitor alone showed a relation (P = 0.06). In the 14 patients who developed an occlusion only three showed a significant rise in serum creatinine. We conclude that special attention should be given to the follow-up of patients with renal artery stenosis who have ACE-inhibitors in their treatment regimen, especially when in combination with a diuretic.

Adolescent↗
PubMed1988

Impaired vasodilation during long-term beta 1-selective beta-blockade in hypertensive patients.

In eight patients with essential hypertension the effect of 50 mg atenolol, once daily for 6 months, on vasodilation during epinephrine infusion and submaximal dynamic exercise was studied. The normal decrease of diastolic blood pressure during bicycle exercise, reflecting a decrease in total peripheral resistance not mediated by circulating epinephrine, disappeared during atenolol treatment. Low-dose infusion of epinephrine had no influence on systolic blood pressure both before and after atenolol. However, the decrease of diastolic blood pressure occurring before atenolol was abolished and the increase in heart rate was attenuated during atenolol treatment. Forearm vascular resistance decreased before and during atenolol to the same extent. So the normal physiologic vasodilation during submaximal dynamic exercise seems impaired during long-term treatment with atenolol. In addition the normal vasodilating response to an increase of circulating epinephrine to levels occurring during daily life stress seems impaired even with the low dose of this beta 1-selective beta-blocker.

Adult↗
PubMed1988

Normal diastolic filling patterns of the left ventricle.

Pulsed Doppler measurements on both sides of the mitral valve and M-mode left ventricular echocardiograms were performed in 215 healthy subjects, 120 males and 95 females, between one and 65 years old, in order to evaluate normal diastolic filling patterns of the left ventricle. The relation between the maximum blood velocity during early passive filling (E wave) and during atrial contraction (A wave) was computed from the Doppler spectra obtained proximal and distal to the mitral valve, resulting in the EA ratio. The influence on the EA ratio of age, gender, body surface area, blood pressure, heart rate, PR interval, respiration, wall thickness and basal wall mass of the left ventricle was investigated. The study showed that the EA ratio measured proximal to the mitral valve (in the left atrium) was significantly smaller than the EA ratio measured distal (in the left ventricle) and that the only prominent relations with the EA ratio were those with age and heart rate. The EA ratio declines with age: proximal to the mitral valve from approximately (medians) 2.5 to 1 and distal to it from 3.5 to 1.5. All other physiological variables are weakly related or unrelated to the EA ratio in this group of healthy subjects.

Adolescent↗
PubMed1988

Reference values for pulsed Doppler signals from the blood flow velocity on both sides of the pulmonary valve.

Pulsed Doppler signals were recorded from the pulmonary artery and the right ventricular outflow tract in 215 healthy subjects (120 males, 95 females; 1-65 years). Amplitude spectra from these Doppler signals were stored in digital form together with adjustment data for the instrument and the simultaneously recorded ECG. From these Doppler spectra the median of the maximal velocity (Vmax), the maximal acceleration (Amax) and the dispersion of the velocity distribution around Vmax (width) were calculated. These three median values were used to characterize the Doppler spectra and to define normal values for bloodflow velocities. Thus, calculations were made without observer interacting using a well-defined computer program. The effect of age, gender, body surface area and heart rate were studied. Reference ranges were calculated. There is a slight decrease of the median value of Vmax and Amax in the pulmonary artery during lifetime from 80 to 70 cm s-1 and from 1,200 to 800 cm s-2, respectively. On the other hand, there is no correlation between age and Vmax and Amax in the right ventricular outflow tract. The width of the spectra increases with age at both sites. No significant changes with age were seen with the other variables.

Adolescent↗
PubMed1987

Combined transcutaneous oxygen, carbon dioxide tensions and end-expired CO2 levels in severely ill newborns.

In 12 newborns combined transcutaneous PO2 and PCO2 levels were measured by means of a Sensor Medics Transend Transcutaneous Gas System simultaneously with the end-tidal PCO2 (PetCo2) values using an Angström Eliza CO2 analyzer. Although the individual correlation coefficients differed greatly, the diagnostic sensitivity of PtcO2 and PtcCO2 was satisfactory within specified limits. The PetCO2 did not agree well with the PaCO2 due to physiologic factors related to lung disorders. We conclude that PtcO2 and PtcCO2 values are very useful in monitoring severely ill newborns although arterial blood gas measurements remain necessary, but not as often as when the transcutaneous technique is not used.

Asphyxia Neonatorum↗
PubMed1987

Reference values for pulsed Doppler signals from the blood flow on both sides of the aortic valve.

Pulsed Doppler signals were recorded in 215 healthy subjects, 120 males and 95 females, between 1 and 65 years of age. The measurements were performed in the left ventricular outflow tract (LVOT) and in the ascending aorta (AAO). Amplitude spectra from the Doppler signals were stored in digital form together with adjustment data for the instrument, the simultaneously registered ECG and respiration signal. The maximum velocity (Vmax), the maximum acceleration (Amax) and the width of the velocity distribution around Vmax (width) were derived from these spectra and used for the characterization of the signals. These parameters were computed without observer interaction using a computer program. Effects of age, sex, body surface area, heart rate and respiration were studied. Reference ranges were calculated. The following conclusions can be drawn: Vmax and Amax in the AAO decrease clearly with increasing age from approximately 100 to 60 cm s-1 and from 2000 to 1000 cm s-2 (medians), respectively. The variation of the width in the AAO is greater for people over 45 years. Vmax, Amax and width in the LVOT increase slightly with advancing age from approximately 60 to 80 cm s-1, 800 to 1000 cm s-2 and 12 to 15 cm s-1 (medians), respectively. These parameters of flow were either unrelated or only weakly related to other physiological variables in this study group.

Adolescent↗
PubMed1986

Normal sympathetic neural activity in patients with mitral valve prolapse.

The hemodynamic and neurohumoral responses to head-up tilt and isometric exercise were studied in 14 mitral valve prolapse (MVP) patients with and 10 MVP patients without complaints and in 16 healthy control subjects. Plasma catecholamines at rest were not different between the three groups and neither were their changes during either test. The hemodynamic changes during head-up tilt were not different between the three groups. The symptomatic MVP patients showed a lower rise in diastolic blood pressure (14.3 +/- 6.4%) than the controls (22.9 +/- 9.6%) (p less than 0.05) during isometric exercise. In view of the fact that the neurohumoral responses to both tests were the same for all groups, we cannot support the suggestions from other studies that MVP patients have an impaired or enhanced sympathetic tone. Moreover, since there were no differences between symptomatic and asymptomatic MVP patients it is doubtful whether the complaints of symptomatic MVP patients are related to a high sympathetic neural activity.

Adult↗
PubMed1986

The influence of intrinsic sympathomimetic activity and beta-1 receptor selectivity on the recovery of finger skin temperature after finger cooling in normotensive subjects.

A double-blind randomized study was designed to investigate differences in the recovery of finger skin temperature after finger cooling during dosing with placebo or one of four beta-blockers: propranolol, atenolol, pindolol, and acebutolol. In 11 normotensive nonsmoking subjects, finger skin temperature was measured with a thermocouple before and 20 minutes after immersion of one hand in a water bath at 16 degrees C. This finger cooling test caused no significant changes in systemic hemodynamics such as arterial blood pressure, heart rate, and forearm blood flow. The recovery of finger skin temperature during propranolol dosing was better than that during pindolol and atenolol dosing. There were no differences between the recoveries of skin temperature during pindolol, atenolol, and acebutolol dosing. Thus we could demonstrate no favorable effect of intrinsic sympathomimetic activity or beta 1-selectivity on the recovery of finger skin temperature after finger cooling.

Acebutolol↗
PubMed1986

Hyperventilation syndrome: measurement of objective symptoms and subjective complaints.

In 303 subjects, amongst whom 250 patients suspected of suffering from the hyperventilation syndrome, lung functions were measured, a hyperventilation provocation test was performed and a questionnaire was taken. The subjects were subdivided into categories of nonhyperventilators, and 3 categories of hyperventilators, on the basis of objective measurable lung function parameters and the result of the provocation test. The outcome of the questionnaire in the various categories was evaluated. Some subjective complaints were related to age, sex, PaCO2 and lung function of the subjects. There was no clear correlation between PaCO2 and neurological signs. Hypoventilation after the provocation test occurred in only 5 subjects. No indications were found that hyperventilation might be an early sign of chronic obstructive lung disease.

Adolescent↗
PubMed1986

Measles, mumps and rubella: control by vaccination.

In 1984, the Health Council of the Netherlands advised that a new vaccination strategy against measles, mumps and rubella (MMR) should be initiated. The use of a combined MMR vaccine, to be given at 14 months and 9 years of age was recommended. An analysis of this strategy based on mathematical models, predicted that rubella and mumps and very probably measles will be eliminated in The Netherlands before 1990. The use of a combined MMR vaccine has a number of logistical and financial advantages over immunization with separate vaccines. Another factor to be considered is of course the mutual interference regarding immune response or immunization reactions. Less obviously, and often not recognised as an important factor, is the possibility of an adverse effect on the incidence of the congenital rubella syndrome (CRS), when vaccine coverage is low or the natural force of infection of rubella is high. Vaccine induced herd immunity can act to the disadvantage of the unvaccinated individuals. Following earlier work we show that certain vaccination programmes could actually increase the incidence of serious cases. At first sight, this may seem inconceivable. Mathematical analysis, however, reveals that this is indeed a real possibility. Implementing a vaccination programme that is not sufficiently intensive to eradicate the infection in the population will ultimately lead to a new steady state in which the force of infection is lower than in the period before the start of the programme. As a consequence those who are not (effectively) vaccinated have a higher chance of contracting the infection at an older age. For many viral infections, the chance of serious complications is greater if the infection is acquired at an older age. Congenital rubella and measles encephalitis are striking examples (with respect to mumps the situation is less clear). When boys and girls are vaccinated around one year of age and MMR vaccine coverage is lower than approximately 50%, the total number of cases with the congenital rubella syndrome can increase in the long term. When the force of infection of rubella before implementing the vaccination programme is high - which may be the case in developing countries - the effect is more pronounced and even a relatively high vaccine uptake of 80-90% may not be sufficient to keep CRS incidence below the level prior to control.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1985

Survival probabilities of infants delivered prior to the 34th week of pregnancy as estimated by means of a logistic model.

Survival of 188 infants born alive before the 34th wk of pregnancy is assessed in relation both to birthweight and duration of pregnancy. A logistic model is used which describes, based on these parameters, probabilities of 1-yr survival of relatively small populations in a continuous way. Although there may be differences between measured and estimated birthweight, this method might enable the perinatologist to estimate before birth the survival probabilities if he knows the duration of pregnancy and estimated birthweight.

Birth Weight↗
PubMed1984

Rational antimicrobial prophylaxis on a urological ward.

The development of a policy for antimicrobial use on a urological ward is presented. The introduction of guidelines for rational antimicrobial use and the monitoring of their effect over a four-year period are described. As a result of the implementation of this policy, a reduction of over 60 percent in antibiotic consumption on the urological ward was achieved. Without interference in the quality of patient care, as determined by the incidence of postoperative wound infections and adverse effects, the overall number of patients treated with antimicrobial agents was reduced 50 percent, but proved to be age dependent. In addition, costs were diminished 20 percent. These results were achieved by intensive collaboration between the Departments of Urology and Clinical Pharmacy.

Adult↗
PubMed1983

Hemodynamic effects of isometric exercise and mental arithmetic in hypertension treated with selective and nonselective beta-blockade.

Hypertensive patients have an unfavorable pressor response to exogenous epinephrine during nonselective beta-blockade. We studied hemodynamics during epinephrine release induced by handgrip exercise and mental arithmetic to examine the clinical relevance of this phenomenon. Twenty-two hypertensive patients were examined in a double-blind crossover experiment with placebo, propranolol (240 mg daily), placebo-washout, and metoprolol (300 mg daily). Changes induced by stress tests for systolic and diastolic blood pressure, heart rate (HR), and forearm blood flow (FBF) were of the same order on both beta-blockers. Rises in HR and FBF were equally reduced by both drugs. Neither handgrip exercise nor mental arithmetic induced significant differences in reaction during selective and nonselective beta-blockade.

Adolescent↗
PubMed1982

Influence of pyridoxal-5'-phosphate on temperature relationship of aspartate aminotransferase and alanine aminotransferase.

The influence of pyridoxal-5'-phosphate on the temperature relationship of aspartate aminotransferase and alanine aminotransferase has been determined. On varying the reaction temperature from 25 degrees to 45 degrees both enzymes showed small but significant deviations from a linear Arrhenius relationship. Supplementation with pyridoxal-5'-phosphate in general enhanced the catalytic activity to the same degree over the entire temperature range. Our results corroborate the findings of Rej but not those of Jung et al.

Alanine Transaminase↗
PubMed1981

DDAVP test for assessment of renal concentrating capacity in infants and children.

The renal concentration capacity was tested by intranasal administration of DDAVP in 97 infants and children. The test was simple and reproducible. The renal concentrating capacity increased during approximately the first year of life. At the ages between 1 and 16 years the mean maximal osmolality of 991 mosm/kg was reached. The urine osmolality obtained in the DDAVP test was significantly lower than during the water deprivation test.

Adolescent↗