Biomedical subjects

T Stijnen

Publications and source records attributed to T Stijnen.

At least 163 records · Page 9Linked to original sources

PubMed1990

Blood flow velocity waveforms from the fetal external iliac artery as a measure of lower extremity vascular resistance.

Blood flow velocities were recorded in the external iliac artery (EIA) and umbilical artery (UA) in 94 normal pregnancies and in 14 with intrauterine growth retardation (IUGR) between 25 and 36 weeks gestation. In normal pregnancy the pulsatility index (PI) in both vessels decreased significantly with advancing gestational age, reflecting a reduction in lower extremity and placental vascular resistance. The EIA PI/UA PI ratio also decreased significantly with gestational age suggesting that vascular resistance is more pronounced in the lower extremities. In the pregnancies with IUGR, PI values from both vessels were nearly always above the upper limit (+2 SD) of the normal curve reflecting increased vascular resistance at lower extremity and placental level. In two pregnancies, absent end-diastolic flow velocities in the umbilical artery were associated with reversed end-diastolic flow velocities in the external iliac artery.

Blood Flow Velocity↗

PubMed1990

Congenital diaphragmatic hernia: impact of prostanoids in the perioperative period.

A prospective study of 10 neonates with congenital diaphragmatic hernia and five controls to determine the importance of prostanoid concentrations perioperatively and the relation with persistent pulmonary hypertension (PPH) is reported. In neonates with congenital diaphragmatic hernia postoperative concentrations of the vasoconstrictor thromboxane B2 rose significantly and were higher during episodes of PPH; this rise may provoke PPH and subsequent right to left shunting.

6-Ketoprostaglandin F1 alpha↗

PubMed1990

Relation between small airways disease and parenchymal destruction in surgical lung specimens.

The relation between small airways disease and parenchymal destruction was investigated in lungs and lobes removed at surgery from 27 patients aged 15-70 years. Eight of the 27 patients were life-long non-smokers. The degree of small airways disease was assessed by semi-quantitative grading (SAD score) and by measuring diameter and wall thickness of membranous bronchioles. Parenchymal destruction was measured in three ways. Firstly, the number of alveolar attachments on membranous bronchioles per millimetre of circumference (AA/mm) was counted; the number of broken attachments was subtracted from the total AA/mm to give the numbers of intact attachments (normal AA/mm). Secondly, a point counting technique was used to give a destructive index (DI). Thirdly, the mean linear intercept (Lm) was determined. Total and normal AA/mm correlated negatively with the SAD score of membranous bronchioles (rs = -0.48 and -0.51) and with wall thickness (rs = -0.37 and -0.45) and DI correlated with wall thickness (rs = 0.5) and with the SAD score of respiratory bronchioles (rs = 0.53). Lm did not correlate with indices of small airway disease and total and normal AA/mm did not correlate with diameter. Multiple regression analyses showed that the correlation of total AA/mm with the SAD score of membranous and respiratory bronchioles and with wall thickness were not confounded by age or smoking. It is concluded that small airways disease is related to destruction of peribronchiolar alveoli, and it is postulated that small airways disease has a direct role in the causation of centrilobular emphysema.

Adolescent↗

PubMed1990

Effects of inflammatory mediators on the responsiveness of isolated human airways to methacholine.

Several studies have suggested that in asthmatics the quantities of inflammatory mediators such as histamine, thromboxane A2 (TxA2), prostaglandin D2 (PGD2), prostaglandin F2 alpha (PGF2 alpha), and leukotriene C4 (LTC4) that are present in the airway lumen are related to the degree of bronchial responsiveness to inhaled methacholine (MCh). Therefore, we studied the effect of these mediators on the cholinergic responsiveness of isolated human airway segments. Lung tissue collected at thoracotomy from 30 patients was studied. Dose-response curves to MCh were obtained from bronchial segments before, during, and after incubation with either a subthreshold or a threshold concentration of histamine (10(-10) or 10(-8) M), the stable TxA2 analogue U46619 (10(-11) or 10(-9) M), PGD2 (5 x 10(-9) or 5 x 10(-7) M), PGF2 alpha (10(-9) or 10(-7) M), or LTC4 (10(-11) or 10(-9) M). With the exception of LTC4, the presence of any of these mediators at either concentration increased the sensitivity to MCh by a factor of 1.1 to 2 (p less than 0.05, ANOVA). This increase did not depend on the dose of the mediator (p greater than 0.05, ANOVA). These data indicate that mediator-induced muscle hypersensitivity can explain a small part of the leftward shift of the dose-response curve to inhaled MCh as observed in asthma.

Aged↗

PubMed1990

Blood flow velocity waveforms in the fetal cardiac outflow tract as a measure of fetal well-being in intrauterine growth retardation.

Maximum flow velocity waveforms were recorded in a longitudinal study from the fetal ascending aorta and fetal pulmonary artery in 46 normal pregnancies and, in addition, from the umbilical artery in 21 cases of intrauterine growth retardation between 19 and 33 wk gestation. In normal pregnancy, the mean peak systolic velocity (PSV) in the ascending aorta increased from 49.4 cm/s at 19 wk of gestation to 79.0 cm/s at 33 wk of gestation. The corresponding increase in PSV in the pulmonary artery was from 39.0 to 63.7 cm/s. The ratio for the PSV between the two arteries remained constant (1.25-1.29). Mean values of PSV in both arteries were linearly related to gestational age. Normal limits according to age were constructed by establishing the 5th and 95th percentiles. In intrauterine growth retardation, the PSV in the pulmonary artery was decreased (less than 5th percentile) in 95% of cases, PSV in the ascending aorta was reduced (less than 5th percentile) in only 57%. No relationship was established between PSV in both arteries and the presence or absence of end-diastolic flow velocities in the umbilical artery. The outcome of fetuses with intrauterine growth retardation, as expressed by Apgar score at 1 min and umbilical cord pH, bears no relationship to the PSV in ascending aorta and pulmonary artery.

Adult↗

PubMed1990

Twenty-four-hour plasma growth hormone (GH) profiles, urinary GH excretion, and plasma insulin-like growth factor-I and -II levels in prepubertal children with chronic renal insufficiency and severe growth retardation.

We studied 24-h plasma GH profiles, maximal GH responses to arginine provocation and insulin-like growth factor-I (IGF-I) and IGF-II levels in plasma in 22 euthyroid prepubertal children (mean age, 9.5 yr) with chronic renal insufficiency (glomerular filtration rate, less than 20 mL/min.1.73 m2) and severe growth retardation [mean (+/- SD) height SD score (SDS), -2.8 (1.1)]. The 24-h GH profiles were analyzed using the Pulsar program. Girls had significantly higher 24-h GH secretion than boys (P less than 0.004). Children with end-stage nephrotic syndrome had higher baseline GH levels and total area under the curve (AUCo) than patients with dysplastic kidneys (P less than 0.05), while the area under the curve above baseline (AUCb) was similar in all types of renal diseases. The type of treatment (conservative, peritoneal, hemodialysis) did not significantly influence the 24-h GH secretion. No correlation was found between 24-h GH profiles and age, height SDS for chronological age, height velocity SDS for bone age, and weight for height. Fourteen children showed a normal 24-h GH profile, defined as a GH profile with well defined, regular GH peaks returning to baseline GH levels and a distinct day and night pattern (AUCb, 90-300 micrograms/L.24 h). Four children had low profiles, with GH peaks below 10 micrograms/L, returning to baseline GH levels and occurring almost exclusively during the night (AUCb, less than 90 micrograms/L.24 h). The remaining four children had elevated 24-h GH profiles, with GH peaks on top of elevated baseline GH levels of more than 3 micrograms/L (AUCb, 35-205 micrograms/L.24 h; AUCo greater than 300 micrograms/L.24 h). In all patients 24-h urinary GH and beta 2-globulin excretion was 100-1000 times higher than that in controls. The urinary GH excretion correlated significantly with all characteristics of the 24-h GH profiles (r = 0.57-0.59; P less than 0.05). The maximal GH response during the arginine tolerance test was normal in 66% of the children. The mean (+/- SD) SDS for bone age for the IGF-I plasma levels was +1.1 (1.9), and that for IGF-II was +3.6 (3.4). IGF-I levels correlated significantly with the AUCb, maximum GH, and GH peak characteristics of the 24-h GH profiles (r = 0.05-0.73; P less than 0.02-0.001). IGF-II levels did not show any correlation with the characteristics of the endogenous GH secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1990

Real and pseudo late asthmatic reactions after submaximal exercise challenge in patients with bronchial asthma. A new definition for late asthmatic responses after exercise challenge.

The late asthmatic reaction after exercise challenge remains a controversial issue. In this study, 21 patients recorded peak expiratory flow rate (PEFR) on two control days without performing exercise. There was no difference between both control days when PEFR at 1 h was compared with baseline PEFR and when PEFR at 4 to 13 hours was compared with baseline PEFR. After analyzing variation coefficients of baseline PEFR on a control day and exercise day, PEFR was not allowed to differ more than 15.3 percent in the same patient when comparing exercise day and control day for the late fall in PEFR in the study. In 17 of 81 patients, a late asthmatic reaction after exercise challenge was present when PEFR fall was greater than or equal to 20 percent compared with baseline PEFR value. In eight of the 17 patients, a real late asthmatic reaction to exercise challenge was present with a PEFR fall greater than or equal to 20 percent on at least three successive time points and who had a PEFR fall greater than or equal to 20 percent compared with corresponding clocktime on a control day. The late asthmatic reaction to exercise challenge is characterized not as a nonspecific epiphenomenon, but as a fall in PEFR of greater than or equal to 20 percent compared with baseline PEFR value and with corresponding clocktime on a control day on at least three successive time points. Graphic illustration of airway responses following exercises may facilitate the detection of a late asthmatic response.

Adult↗

PubMed1989

Complications from long-term indwelling central venous catheters in hematologic patients with special reference to infection.

Forty-three evaluable patients with hematologic malignancies, mainly acute leukemia, were prospectively randomized to receive a double lumen central venous catheter or a totally implantable venous access system. The mean catheter stay was 166 days (median, 104 days) for the 23 double lumen catheters and 164 days (median, 65 days) for implanted systems. Exit site infections were not encountered in double lumen catheters, but there were two proven infections around the injection port of implanted devices. Tunnel infections did not occur. Seven double lumen catheters and four implanted systems were removed because of infection. Staphylococcus epidermidis was the predominant microorganism cultured from these catheters. Five of nine patients with double lumen catheters and catheter-related S. epidermidis infection and the two patients with implanted systems in whom S. epidermidis was cultured were on selective gut decontamination. The pattern of infection did not seem to be influenced by this regimen. Totally implantable systems proved to be as safe as double lumen central venous lines.

Acute Disease↗

PubMed1989

Noninvasive axial and peripheral assessment of bone mineral content: a comparison between osteoporotic women and normal subjects.

We compared different methods of bone densitometry in women with spinal osteoporosis and normal subjects to assess their discriminatory capability. The methods used included: quantitative computed tomography of the spine (QCT) specified as to trabecular (QCTtrab) and cortical bone (QCTcort), dual-photon absorptiometry of the spine (DPAspine), single-photon absorptiometry of the distal and proximal forearm (SPAdist and SPAprox), and quantitative roentgen microdensitometry of the phalanx (QMD). A total of 25 postmenopausal osteoporotic women and 24 healthy comparison subjects matched for age and years since menopause were studied. In the osteoporotic group an average decrement of the axial bone mineral density of -50% (p less than 0.001) and -20% (p less than 0.001) were observed for QCTtrab and QCTcort, respectively. For DPAspine, SPAdist, SPAprox, and QMD the difference between normal and osteoporotic subjects was -20% (p less than 0.001), -12% (p less than 0.05), -7% (NS), and -6% (NS), respectively. With the peripheral measurements (SPA and QMD), alone or in combination, no adequate discrimination between women with or without vertebral compression fractures could be obtained. Although QCTtrab showed the highest diagnostic sensitivity (81%), it appears not to be superior to DPAspine. Combinations of the various axial and peripheral measurements did not result in an essentially better sensitivity. In normal women as well as in osteoporotic individuals the trabecular and cortical QCT measurements showed two opposite trends, suggesting an increase in cortical and a decrease in trabecular density from L1 to L3.

Absorptiometry, Photon↗

PubMed1989

The effect of a manometer on the mean airway pressure during hand ventilation, an in vitro study.

The effect of an on-line manometer on the variables of ventilation i.e. peak inspiratory pressure (PIP), mean airway pressure (MAP), positive end expiratory pressure (PEEP), and inspiratory to expiratory time ratio (I:E) was studied in vitro. Analysis of PIP, MAP, PEEP, and I:E was made during hand ventilation of a resuscitation mannequin at the preselected PIP of 15 and 25 cm water with and without a manometer. Use of the manometer decreased the range of variation in PIP, but the MAP was higher. This was due to an increased I:E while PEEP remained unchanged. An on-line manometer during hand ventilation prevents excessive PIP but may increase the MAP and therefore may not prevent development of a pneumothorax.

Air Pressure↗

PubMed1989

Should the Cytobrush be used in routine screening for cervical pathology?

In 632 women visiting a family planning clinic, paired cervical smears were taken using a wooden spatula and a Cytobrush. Of the spatula smears 7.8% were unreliable with too little or scanty material to allow a cytologic diagnosis (class 0); 17.7% of spatula smears were inadequate, lacking endocervical cells. Combined spatula/Cytobrush cytology reduced these figures significantly; 4.3% unreliable smears and 3.2% inadequate specimens. Seventy-three (11.6%) of the smears revealed some abnormality, in most cases Papanicolaou class IIIA, suggestive of mild dysplasia. In 10 cases, dysplastic cells were found only in the Cytobrush cytology. It is concluded that the Cytobrush adds to the improvement of smear quality and the accuracy of routine cervical cytology obtained by relatively inexperienced smear takers.

Contraceptives, Oral↗

PubMed1989

Treatment of acute myelogenous leukemia. An EBMT-EORTC retrospective analysis of chemotherapy versus allogeneic or autologous bone marrow transplantation.

In a retrospective analysis, patients with acute myelogenous leukemia (AML), treated in first complete remission (CR) with chemotherapy or with allogeneic or autologous bone marrow transplantation were compared with respect to their leukemia-free survival from CR. Two hundred and thirty-six patients treated with chemotherapy according to the EORTC AML-5 and AML-6 trials were included. The data of the transplanted patients were taken from two EBMT registries; 453 with an allogeneic and 182 with an autologous BMT. The very different sources of the data (trials and registries) forced us to be cautious in our conclusions. However, for the patient cohorts analyzed in the present study, BMT patients tended to have a better leukemia-free survival than chemotherapy patients. This was especially the case for the allogeneic BMT after 6 months of transplant.

Adolescent↗

PubMed1989

Renal transplant patients monitored by the cell-mediated lympholysis assay. Evaluation of its clinical value.

Donor-specific cytotoxic T cell activity was measured over a period of 5 years after transplantation using the cell-mediated lympholysis (CML) test in 124 recipients of unrelated kidney allografts who received conventional immunosuppressive therapy consisting of azathioprine and prednisone. Since patients with a functioning transplant frequently display donor-specific CML non-responsiveness in vitro, we addressed the question of whether the CML status has a predictive value regarding the graft prognosis at any time interval until 5 years posttransplantation. From log-rank type analyses we conclude that the estimated relative risk calculated over the whole follow-up period of a CML-responder in the category of transplant rejectors is 1.25 with 95% confidence bounds between 0.94 and 1.65. Measurements of CML responder status during follow-up seem to have only limited prognostic value, although the relative risk is borderline significant when the analysis is restricted to the period between 2 weeks and 6 months posttransplantation.

Cytotoxicity Tests, Immunologic↗

PubMed1989

Cerebral blood-flow velocity during the first week of life of preterm infants and neurodevelopment at two years.

Disturbances in perinatal cerebral perfusion appear to be associated with unfavourable neurodevelopmental outcome. Using transcutaneous Doppler technique, the authors investigated cerebral blood-flow velocity patterns in the anterior cerebral artery (ACA) of an intensive care-unit population of preterm infants during the first week of life. The results were correlated with neurodevelopmental outcome at two years of age. Children with major disability at two years of age had significantly higher pulsatility index (PI) values, mainly increased peak systolic flow velocity (PSFV), compared with children with normal or more favourable outcome. End diastolic flow velocity and area under the velocity curve values of the ACA did not differ between the groups, indicating that cerebrovascular resistance and cerebral blood-flow were not different. It is thought that the higher PI and PSFV values were caused by increased compliance of the vascular bed supplied by the ACA, possibly induced by congestion and oedema of the periventricular white-matter due to ischaemic lesions, which also cause periventricular leukomalacia.

Blood Flow Velocity↗

PubMed1989

Does caffeine affect cerebral blood flow in the preterm infant?

Caffeine, used for treatment of idiopathic apnea in preterm infants, may have a vasoconstrictive effect on cerebral vessels. The ensuing reduction in cerebral blood flow may play a role in the pathogenesis of ischemic brain damage. In 25 preterm infants possible changes in cerebral blood flow due to caffeine administration were assessed using Doppler ultrasound. During caffeine treatment PaCO2 was reduced. However, no changes were found in cerebral blood flow velocity suggesting absence of major changes in cerebrovascular resistance and actual cerebral blood flow following caffeine medication.

Apnea↗

PubMed1989

Antileukoprotease-containing bronchiolar cells. Relationship with morphologic disease of small airways and parenchyma.

Twenty-seven surgically removed lungs and lobes were studied to assess the relation between the abundance of bronchiolar epithelial cells containing antileukoprotease (ALP) (ALP-pos/mm) and the degree of small airways disease (SADscore) and emphysema (destructive index = DI, and number of normal alveolar attachments on membranous bronchioles = normal AA/min). Between subjects, ALPpos/mm correlated with SADscore in membranous bronchioles (rs = 0.75; p less than 0.001) and with normal AA/mm (rs = -0.38; p = 0.05). Evaluation within each subject revealed significant correlations of ALPpos/mm with SADscore in membranous as well as in respiratory bronchioles (p less than 0.001), and also with normal AA/mm (p = 0.005). In membranous and in respiratory bronchioles, ALPpos/mm correlated significantly with the ALP concentration in homogenized tissue, as measured by ELISA (rs = 0.55 and 0.57, respectively; p less than 0.01). It is concluded that disease in small airways and destruction of their alveolar attachments are associated with a rise of the number of ALP-containing epithelial cells. We hypothesize that this cellular increase is part of the general defense against inflammatory and destructive processes in distal human airways, leading to higher levels of proteinase inhibitor in order to minimize tissue damage.

Bronchi↗

PubMed1989

Cerebral blood flow velocity changes in preterm infants after a single dose of indomethacin: duration of its effect.

Indomethacin decreases cerebral blood flow velocity and blood flow in the preterm infant. The duration of this negative effect has not been established. Cerebral blood flow velocity was evaluated in 24 preterm infants with symptomatic patent ductus arteriosus before and during the first 12 hours after a single intravenous dose of indomethacin, 0.1 mg/kg. Cerebral blood flow velocity was estimated by serial Doppler investigations of the anterior cerebral arteries. Indomethacin administration led to an instantaneous decrease of peak systolic flow velocity, temporal mean flow velocity, and end-diastolic flow velocity of the anterior cerebral arteries in all infants, which was maximal between 2 and 40 minutes after indomethacin administration and was followed by a more sustained recovery of all velocities to baseline values. Temporal mean flow velocity was not different from pre-indomethacin values at 3 hours after the administration. It is concluded that indomethacin can impact the cerebral circulation of the preterm infant for at least 2 hours. This may have consequences in preterm infants with unstable hemodynamics and pulmonary function.

Blood Flow Velocity↗

PubMed1988

Graves' disease: immunological and immunogenetic indicators of relapse.

The use of measurements of antibody to the thyroid stimulating hormone receptor and HLA-DR3 phenotype for predicting relapse of hyperthyroidism in patients with Graves' disease receiving medical treatment is controversial. Fifty eight new patients with Graves' disease were followed up prospectively for up to 96 months after treatment with antithyroid drugs for 12 months. The presence of antibody to the thyroid stimulating hormone receptor before the start of treatment, measured as immunoglobulins inhibiting binding of thyroid stimulating hormone, was not associated with relapse. Patients who remained positive for antibodies after treatment tended to relapse within six months, but no relation with long term relapse was found. HLA-Cw7 but not HLA-DR3 was significantly associated with relapse. The presence of HLA-DR4 was significantly associated with remission and with absence of antibodies to thyroid stimulating hormone receptor. HLA-DR4 may therefore protect against relapse of thyrotoxicosis by immunomodulation triggered by antithyroid drugs, which results in the synthesis of antibodies to the thyroid stimulating hormone receptor being inhibited.

Adolescent↗