Search PubMed⌕ Search

Biomedical subjects

T Stijnen

Publications and source records attributed to T Stijnen.

At least 145 records · Page 8Linked to original sources
PubMed1992

Forces applied during laryngoscopy and their relationship with patient characteristics. Influence of height, weight, age, sex and presence of maxillary incisors.

The relationships between patients' height, weight, age, body mass index, gender and presence of maxillary incisors and a series of laryngoscopic factors have been studied. These included the duration of laryngoscopy, maximally applied force, mean applied force and the integral of force over time. There was a positive correlation between height and weight and laryngoscopic factors. Sex and age also showed a positive correlation but these could be explained by differences in height, weight and the presence of maxillary incisors. This latter factor was the dominant patient characteristic influencing the measured laryngoscopic factors. Use of these laryngoscopic factors as a measure of difficulty of laryngoscopy is discussed.

Adolescent↗
PubMed1992

Cardiovascular effects of forces applied during laryngoscopy. The importance of tracheal intubation.

The relationship between the forces applied during laryngoscopy and cardiovascular changes were studied in patients undergoing laryngoscopy with or without intubation. This enabled us to differentiate between the cardiovascular effects of laryngoscopy and the effects of tracheal intubation. The forces applied during laryngoscopy were only weakly related to the cardiovascular changes, whereas tracheal intubation had a major influence. The many difficulties encountered in interpreting results from these studies are discussed. It is concluded that tracheal intubation causes more cardiovascular changes than laryngoscopy in routine uncomplicated procedures.

Adolescent↗
PubMed1992

Reproductive behaviour following spontaneous loss of pregnancy after prenatal diagnosis.

One hundred and fifty-eight women of advanced maternal age with complete follow up who experienced spontaneous fetal loss after prenatal diagnosis were studied for reproductive behaviour as well as prenatal diagnosis in a subsequent pregnancy. A higher rate of subsequent pregnancies amongst women who experienced an early spontaneous abortion after chorionic villus sampling (CVS) was expected compared with women who lost a pregnancy later during pregnancy after amniocentesis. Of the 92 women who underwent CVS in a previous pregnancy, 57 (62%) became pregnant again. Of the 66 women who underwent amniocentesis in the pregnancy that ended in fetal loss, 34 women (52%) had a subsequent pregnancy. The cumulative incidence of subsequent pregnancies was significantly influenced by maternal age but not by parity or the method of prenatal testing. Most women who decided on a new pregnancy opted for prenatal diagnosis. There was a preference for amniocentesis if the patient had previously undergone CVS. However, the reverse was not the case.

Abortion, Spontaneous↗
PubMed1992

Effect of chorionic villus sampling on utilization of prenatal diagnosis in women of advanced maternal age.

The effect of the introduction of chorionic villus sampling on the utilization rate of prenatal diagnosis in advanced maternal age was studied during the period 1 January 1985-1 January 1991. On the first of January 1985, the age limit for prenatal diagnosis in The Netherlands was lowered from 38 to 36 years of age. The overall uptake rate during the studied period increased significantly, but only because of the increased uptake rate in the group 36 and 37 years. In the maternal age group of 42 years and older, an uptake rate as low as 15.9% was established. This was mainly determined by the relatively high percentage (73.0%) of women from ethnic minorities in this age group. The number of CVS procedures increased significantly during the study period, but the utilization rate was not influenced, since the number of amniocenteses decreased accordingly. An increase in acceptability of prenatal diagnosis by women of advanced maternal age due to early testing and early termination of pregnancy could not be substantiated in the present study.

Adult↗
PubMed1992

CT scan prediction of neurological deficit in thoracolumbar burst fractures.

In 139 patients with burst fractures of the thoracic, thoracolumbar or lumbar spine, the least sagittal diameter of the spinal canal at the level of injury was measured by computerised tomography. By multiple logistic regression we investigated the joint correlation of the level of the burst fracture and the percentage of spinal canal stenosis with the probability of an associated neurological deficit. There was a very significant correlation between neurological deficit and the percentage of spinal canal stenosis; the higher the level of injury the greater was the probability. The severity of neurological deficit could not be predicted.

Humans↗
PubMed1991

Assessment of medial thinning in atherosclerosis by intravascular ultrasound.

This study investigated the in vitro (40 MHz) and in vivo (30 MHz) feasibility of intravascular ultrasound to document the influence of atherosclerotic lesions on the typical 3-layered appearance of muscular arteries. The in vitro images of 39 arteries were compared with the corresponding histologic sections. Media and lesion thickness were measured at the areas of minimal and maximal lesion thickness. The median media thickness was 0.8 mm in the absence of a lesion, decreasing to 0.3 mm in the area of maximal atherosclerosis. The ultrasonic data correlated closely with histologic measurements (0.6 and 0.3 mm, respectively). The in vivo study was performed in 29 patients undergoing coronary or peripheral vascular procedures. A total of 150 still-frames were selected for quantitative analysis. The median media thickness was 0.6 mm in the absence of a lesion, decreasing to 0.1 mm in the area with maximal atherosclerosis. This study revealed that intravascular ultrasound imaging accurately determines that media thickness of muscular arteries is inversely related to lesion thickness. In vitro data, verified with histology, can be translated to humans in vivo.

Arteries↗
PubMed1991

Effect of epithelial denudation, inflammatory mediators and mast cell activation on the sensitivity of isolated human airways to methacholine.

In asthmatics, both the continuous release of mast cell-derived inflammatory mediators and damage of the airway epithelium may be related to the degree of bronchial responsiveness. We therefore evaluated the effect of inflammatory mediators and mast cell activation on the cholinergic responsiveness of strips of human bronchioles with and without epithelium. Cumulative concentration-response curves to methacholine were generated from strips with or without epithelium before, during and after incubation with threshold doses of either methacholine (3 x 10(-7) M, controls), histamine (3 x 10(-7) M), the thromboxane A2 analogue, U46619 (10(-9) M), prostaglandin (PG) D2 (3 x 10(-7) M), PGF2 alpha (3 x 10(-7) M), leukotriene (LT) C4 (10(-9) M), or anti-human immunoglobulin E (24.4 +/- 4.0 micrograms.ml-1). Strips without epithelium were 1.6 times more sensitive to methacholine than strips with epithelium (-log EC50:5.76 +/- 0.04 vs. 5.97 +/- 0.04, P less than 0.0001). The average contraction in response to identical doses of anti-IgE in strips without epithelium was 3 times greater than the contraction in strips with epithelium (P less than 0.05). Threshold concentrations of histamine, U44619 and PGD2 caused a similar non-parallel leftward shift of the concentration-response curve of strips with or without epithelium to methacholine (P less than 0.05). Together, epithelial denudation and low levels of mediators caused a 4.0- to 9.1-fold increase in sensitivity based on the -log EC10 and a 1.8- to 3.0-fold increase in sensitivity based on the -log EC50.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Placebo-controlled, double-blind, cross-over trial of growth hormone treatment in prepubertal children with chronic renal failure.

Stunted growth is a serious problem for children with chronic renal failure (CRF) despite normal endogenous growth hormone secretion and normal or elevated plasma concentrations of insulin-like growth factors (IGF) I and II. Biosynthetic growth hormone (GH) was given to 20 prepubertal children (eleven boys, nine girls; mean age 9.5 years, range 4-16) with CRF and severe growth retardation in a placebo-controlled, double-blind, cross-over trial. 6 months of subcutaneous injection of GH (4 IU/m2 per day) was either preceded or followed by 6 months of placebo injection. The patients had a full examination every 3 months. Sixteen children completed the study. Height velocity improved significantly with GH therapy (p less than 0.0001) and placebo (p less than 0.04), but the GH-induced height-velocity increase exceeded that of placebo by 2.9 cm per 6 months. There was a positive relationship between prestudy height velocity and height-velocity increase. Bone maturation was not affected. GH caused a significant increase in IGF-I and a moderate increase in IGF-II plasma concentrations. The pretreatment elevation of IGF-binding protein-1 decreased by almost 50% during GH therapy, while IGF-binding protein-3 increased significantly in concentration, although this increase was significantly smaller than the GH-induced increase in IGF-I. Fructosamine, lipid, and parathyroid concentrations remained constant. Renal function deterioration did not accelerate. Impressive height-velocity increase can be achieved with GH therapy in children with CRF and growth retardation without changes in renal function. Bone maturation appears unaffected suggesting improved final height. Treatment is best started before growth retardation becomes considerable.

Adolescent↗
PubMed1991

The value of immunohistochemistry for collagen IV expression in colorectal carcinomas.

The Dukes' classification has well-established prognostic value in colorectal cancer patients. Yet, in each Dukes' class, the survival of individual patients may vary considerably. Recent studies show prognostic significance of genetic alterations in colorectal carcinoma. However, the importance of tumor stromal components noted in the surrounding tissue may have been overlooked by the methods used. Therefore, in a longitudinal study of 154 patients with colorectal cancer operated on between 1967 and 1974, the authors determined the influence on prognosis of lymphocytic infiltration and expression of collagen type IV in tumor stroma. Also, age, sex, Dukes' classification, grade of tumor differentiation, vasoinvasion, and the number of positive lymph nodes were analyzed. Follow-up was at least 15 years. Lymphocytic infiltration and collagen IV expression were scored as mild, moderate, or severe. Survival was analyzed by a Cox proportional-hazards model. The density of lymphocytic invasion showed no significant influence on survival. Collagen IV expression analyzed as a single variable was significantly (P = 0.038) related to better prognosis in colorectal cancer patients. By multi-variate analysis collagen IV expression showed a trend toward better prognosis that was not statistically significant (P = 0.12). Dukes' classification (P less than 0.001), the presence of vasoinvasion (P = 0.009), and lymph node status (P = 0.04) significantly influenced survival. In conclusion immunohistochemistry for collagen IV is an important additional staining technique with prognostic value. In addition, collagen IV immunostaining facilitates recognition of vascular invasion by highlighting the basement membrane of vessels.

Adenocarcinoma↗
PubMed1991

Prenatal diagnosis in advanced maternal age. Amniocentesis or CVS, a patient's choice or lack of information?

Ninety-six women of advanced maternal age were interviewed about the way they obtained information on prenatal diagnosis and about how the decision was made as to what procedure was to be performed (transabdominal chorionic villus sampling (TA-CVS) or amniocentesis). In the CVS group, women visited their physician or midwife earlier in pregnancy (mean 7.1 weeks) than those in the amniocentesis group (mean 10.7 weeks). The availability of prenatal diagnosis was not mentioned during the first antenatal visit in 55 per cent of women from the amniocentesis group as opposed to 25 per cent from the TA-CVS group. Approximately 40 per cent of women eligible for prenatal diagnosis did not receive any information from the referring body prior to counselling at our centre. Only 29 per cent of women who underwent amniocentesis had actually chosen this procedure; 71 per cent were too late to undergo TA-CVS at 12 weeks. It is concluded that information to the patient must be improved in order to ensure early referral for prenatal diagnosis.

Adult↗
PubMed1991

Effect of fetal breathing movements on fetal cardiac hemodynamics.

Maximum flow velocity waveforms were studied at atrioventricular and outflow tract level in 12 cases during fetal breathing activity and in 12 cases during fetal apnea matched for maternal and gestational age and maternal parity. Gestational age ranged between 27 and 40 weeks (median 30 weeks). All flow velocity waveforms were obtained using a mechanical sector scanner with a pulsed Doppler system (carrier frequency 3.5 MHz). Time-averaged flow velocities were clearly different between inspiration and expiration at all four recording levels, reflecting changes in venous return as a result of fluctuations in intrathoracic pressure during fetal breathing activity. Percentage change between inspiration and expiration at outflow tract level was positively correlated with gestational age. Time-averaged flow velocity at mitral level and ascending aorta level was significantly higher during fetal breathing activity than during apnea, suggesting increased shunting of blood flow through the foramen ovale. Acceleration time at outflow tract level demonstrated very little change relative to inspiration and expiration.

Blood Flow Velocity↗
PubMed1991

Risk factors for Alzheimer's disease: overview of the EURODEM collaborative re-analysis of case-control studies. EURODEM Risk Factors Research Group.

Studies of risk factors for Alzheimer's disease have been hampered by low statistical power. The data from 11 case-control studies were pooled and re-analysed to evaluate the evidence for the association of Alzheimer's disease with family history of dementia and related disorders, parental age, medical history, and environmental factors. This paper gives a brief description of the participating studies and discusses the strategy that has been followed in the collaborative analysis.

Adult↗
PubMed1991

Effects of hyperosmolarity on human isolated central airways.

1. We studied the effect of hyperosmolarity on human isolated airways because a better understanding of the effect of hyperosmolarity on the human airway wall may improve insight into the pathophysiology of hyperosmolarity-induced bronchoconstriction in asthma. 2. In cartilaginous bronchial rings dissected from fresh human lung tissue, hyperosmolar krebs-Henseleit buffer (450 mosM, extra sodium chloride added) evoked a biphasic response: a rapid relaxation phase (peak after 5.0 +/- 0.3 min) followed by a slow contraction phase (peak after 25.4 +/- 0.8 min). 3. With the histamine (H1) receptor antagonist mepyramine, the contraction phase was reduced to 41.2% of the control value (P less than 0.001), with atropine to 50.0% (P less than 0.01), with the local anaesthetic lignocaine to 48.7% (P less than 0.05) and with mepyramine together with atropine to 19.2% (P less than 0.001). 4. With the inhibitor of neutral metalloendopeptidase, phosphoramidon, the contraction phase increased to 128.0% of the control value (P less than 0.05) and after removal of the epithelium to 131.8% (P less than 0.05). 5. Indomethacin, the leukotriene C4/D4 (LTC4/D4) antagonist FPL 55712 or the blocker of nerve conduction, tetrodotoxin, had no effect on the contractile phase. 6. The relaxation phase was not altered by any of these drugs nor by epithelial denudation. The relaxation phase was also unchanged in the presence of alpha-chymotrypsin, which degrades muscle relaxing peptides such as vasoactive intestinal peptide. 7. Hyperosmolar buffer slightly increased the sensitivity and maximal response to methacholine as well as the cholinergic twitch to electric field stimulation. 8. We conclude that hyperosmolarity releases acetylcholine, histamine and neuropeptides in the human airway wall in sufficient quantities to contract airway smooth muscle. This release itself or its effect on airway muscle is modulated by the airway epithelium. The mechanism of the relaxation phase may be an unknown smooth muscle relaxing substance or a direct effect on the airway muscle, related to ion fluxes.

Acetylcholine↗
PubMed1991

Uptake and degradation of soluble aggregates of IgG by monocytes of patients with rheumatoid arthritis: relation to disease activity.

Monocytes from patients with rheumatoid arthritis (RA) and rheumatoid vasculitis have a diminished ability to degrade soluble complexes of aggregated IgG in the absence (mediated by Fc receptors) as well as in the presence of complement (C) (mediated by (Fc + C) receptors). To investigate whether a relation exists between the receptor mediated degradation of aggregated IgG by adherent monocytes and disease activity a longitudinal study was performed in 79 patients with RA and rheumatoid vasculitis over a period of 16 months. Adherent monocytes were incubated in vitro with 125I labelled IgG aggregates of restricted size in the absence or presence of fresh serum and the percentage of catabolised IgG aggregates was measured. Cross sectionally the degradation of aggregated IgG by monocytes, mediated by Fc and (Fc + C) receptors, correlated significantly with disease activity as scored by the Ritchie articular index, the presence of extra-articular features, and circulating immune complexes. A high number of Fc receptors on monocytes correlated with diminished degradation, whereas high numbers of complement receptors 1 and 3 correlated with enhanced degradation of aggregated IgG mediated by both Fc and (Fc + C) receptors. The degradation of aggregated IgG by monocytes did not correlate with disease activity in individual patients followed up longitudinally. When patient groups were formed according to the results of longitudinal studies, however, degradation of aggregated IgG mediated by Fc and (Fc + C) receptors was significantly decreased in patients with rheumatoid vasculitis and in patients with active RA in comparison with patients with inactive RA and healthy controls. Patients with active RA and rheumatoid vasculitis also expressed significantly more Fc receptors and less complement receptors on the monocytes than patients with inactive RA. Drug treatment did not correlate with receptor expression or the degradation of aggregated IgG by monocytes either in cross sectional or longitudinal studies. It is concluded that in RA disease activity is related to receptor expression and the degradation of soluble immune aggregates by monocytes.

Adult↗
PubMed1991

Standardization of grip strength measurements. Effects on repeatability and peak force.

The aim of our study was to test grip strength and assess the effects of various degrees of standardization on repeatability and level of peak force. Sixteen healthy persons and eight subjects with an impaired hand function have been tested using a strain-gauge dynamometer. We compared four measurement protocols: (A) the subject is free to assume a comfortable arm position; (B) the subject is also free to assume a comfortable arm position but in addition a challenging stimulus to exceed a previous maximal effort, is given; (C) the arm was held in a predescribed and partly fixated position, as recommended by the American Society of Hand Therapists; (D) the position of the dynamometer is standardized using two reference points both on the hand and on the dynamometer. We found high test-retest reliabilities for each measurement protocol without any significant difference. There were, however, significant differences in strength level. With measurements according to protocol B the highest peak values were noted. Since the measurement protocol B combined good reliability with realistic peak forces, this procedure seems most suitable for grip strength measurements.

Adolescent↗
PubMed1990

Low dose amitriptyline in chronic pain: the gain is modest.

In the double-blind placebo-controlled study presented here, the effects were investigated of a low dose of amitriptyline (75 mg) in patients with chronic pain of various origins. The active drug was superior to placebo in reducing pain intensity. The reduction was small. In the second treatment week, the amitriptyline treated patients slept longer. No differences between active drug and placebo were found with respect to daily activities or use of analgesics. Based on our data and those of other studies, it is concluded that amitriptyline (and other antidepressants) in low doses does have a positive effect on the intensity and some other aspects of chronic pain, but that the effect is modest. It must be kept in mind that chronic pain is a very treatment-resistant condition. Therefore, even modest positive effects may be worthwhile.

Adult↗
PubMed1990

Influence of biological factors on changes in mean cerebral blood flow velocity in normal ageing: a transcranial Doppler study.

Analysis of the blood flow velocities in the middle cerebral artery by transcranial Doppler ultrasonography was performed in 158 healthy volunteers (aged 14-70 years; 82 men and 76 women). In a subgroup of 38 men and 21 women the end-tidal [CO2] was also measured. The influence of biological factors such as age, sex, end-tidal [CO2], and pulsatility and resistance indices on the mean blood flow velocity in normal ageing was investigated by multiple regression analysis. In both sex groups the measured mean blood flow velocity decreased significantly with age (P values less than 0.0003 for women and less than 0.0001 for men). Women had significantly higher blood flow velocities than men (P = 0.008) and the age-corrected sex difference of 5.2 cm s-1 did not significantly depend on age (P = 0.93). The age-related linear decline of the mean blood flow velocity could not be explained by a concomitant decrease of the end-tidal [CO2]. In a group of subjects older than 50 years, the decrease of the mean blood flow velocity was significantly related to the increase of the pulsatility or resistance index.

Adolescent↗