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Biomedical subjects

E Länsimies

Publications and source records attributed to E Länsimies.

At least 19 recordsLinked to original sources
PubMed2001

Continuous mean arterial pressure measurement in the fingers: the influence of local arm cooling.

Two different methods were studied for non-invasive beat-to-beat finger mean arterial pressure (MAP) measurement in 14 healthy volunteers during local arm cooling to 17 degrees C. Fingertip skin blood flow was recorded by a laser Doppler instrument. The difference between the oscillometric beat-to-beat blood pressure measurement device (UT9201) and volume clamp monitor (Finapres) before cooling was -1.5+/-1.1 mmHg, and, although statistically significant, (p< 0.01), this difference cannot be considered clinically meaningful. The results obtained using the two devices during arm cooling showed a systematic disagreement in the continuously recorded MAP. After a 30s period of cooling, the group-averaged difference of UT9201 minus Finapres, calculated as change from the baseline, reached (mean +/- SD) 8.8+/-6.3 mmHg (statistically significant, p< 0.01).

Adult↗
PubMed2001

Heart rate variability and its determinants in patients with severe or mild essential hypertension.

How cardiac autonomic nervous control is related to the severity of essential hypertension in patients receiving long-term antihypertensive therapy is not well known. The aim of this study was to examine heart rate variability (HRV), a non-invasive measure of cardiac autonomic function, in patients with long-term and medically treated mild and severe essential hypertension and healthy control subjects, and to assess the clinical determinants of HRV in these patients. Thirty-four patients with severe essential hypertension (SEHT) and 29 with mild essential hypertension (MEHT) as well as healthy age- and sex-matched control subjects were studied. HRV was assessed from 10 min ECG-recordings during paced (0.2 Hz) breathing at rest and expressed as time and frequency domain measures. In the SEHT group time (SDNN, RMSSD) and frequency domain measures (total power, low-frequency (LF) power and high-frequency (HF) power of HRV in absolute units, and LF and HF power of HRV in normalized units) of HRV were significantly lower when compared with those of the control group. The MEHT and control groups did not differ from each other with respect to time or frequency domain measures of HRV. Comparison between the hypertensive groups showed that SDNN, total power, LF power and HF power were lower in the SEHT group compared with the MEHT group (P<0.05 for all). Among hypertensive patients RR-interval, age, gender, systolic finger blood pressure and diastolic office blood pressure as well as 24-h blood pressure were significant determinants of HRV. In conclusion, we found that the severity of chronic essential hypertension seems to be related to the severity of impairment of cardiac autonomic control.

Adult↗
PubMed2001

The nurse's workload in care situations.

AIM: The aim of this study was to describe the nurse's workload in care situations and on different work shifts on surgical and medical wards. Changes in heart rate, shoulder-neck muscle tension and perceived exertion were measured in these care situations. DESIGN: Nurses' physical fitness was tested using a clinical exercise test. RESULTS: Transportation of a patient to the operating theatre was the most strenuous care situation on morning and evening shifts. Primary care, and situations related to practical nursing procedures were the second most strenuous situations regardless of the shift. Workload in primary care situations and in transporting the patient can be classified as medium heavy based on heart rate and relative workload, whereas in other situations it can be classified on average as moderate or light. The nurse's good physical fitness was reflected in relative workload in care situations so that in primary care and practical nursing procedures there was a statistically significant difference between those who scored high on a fitness test and those who scored low. Transferring tasks and practical nursing procedures involved more shoulder-neck muscle tension than other care situations.

Adaptation, Psychological↗
PubMed2000

Effects of prematurity, intrauterine growth status, and early dexamethasone treatment on postnatal bone mineralisation.

AIM: To examine the hypothesis that, apart from prematurity, intrauterine growth status (expressed as gestational age specific birth weight standard deviation scores), neonatal factors, and duration of dexamethasone treatment influence bone mineralisation in early infancy. METHODS: In this prospective study, groups consisted of 15 preterm small for gestational age infants (SGA group) and 43 preterm appropriate for gestational age infants (AGA group). A reference group contained 17 term infants. Body size is known to affect bone mineral content (BMC), therefore postnatal bone mineralisation was measured when the study infants and controls had attained a similar body size. Bone mineral density (BMD) and BMC were determined by dual energy x ray absorptiometer of the lumbar spine (L2-L4). RESULTS: Both preterm groups had significantly lower BMC and BMD than the weight matched term reference group, but no difference was found in BMC and BMD between preterm SGA and AGA infants. In stepwise regression analysis, bone area, duration of dexamethasone treatment, weight at examination, and weight gain per week were the most significant factors, explaining 54% of the variance of the BMC values. CONCLUSION: In particular, weight at examination, prematurity, and possibly dexamethasone treatment, but not intrauterine growth status, affect postnatal bone mineralisation.

Absorptiometry, Photon↗
PubMed1999

Determinants of bronchial responsiveness at school age in prematurely born children.

The bronchial challenge test using isocapnic hyperventilation of cold air (IHCA) was used to evaluate bronchial responsiveness in 63 offspring of multiple pregnancies when they were 8-15 years old. At birth, 27 (43%) children had had intrauterine growth retardation (IUGR, birth weight <-2 SD, or birth weight difference between twin pairs >1.3 SD). The median birth weight was 2,050 g (range, 800-3, 150), and the median gestational age was 35 weeks (range, 28-38). None of the children had asthma or suffered from asthma-like symptoms. In the interpretation of the IHCA test, a fall of 9% or more in the forced expiratory volume in 1 sec (FEV(1)) was considered as abnormal, and these children were classified as "cold air responders." The number of responders was 16 (25%); their baseline FEV(1)/forced vital capacity ratio (FEV(1)/FVC) and forced expiratory flow between 25-75% FVC (FEF(25-75)), but not FEV(1) were significantly lower than the corresponding values in nonresponders. No differences were found in perinatal or neonatal factors between responders or nonresponders. Eight (30%) of the 27 IUGR and 8 (22%) of the 36 appropriate for gestational age (AGA) children were IHCA responders. In particular, IUGR was not correlated with maximal FEV(1) falls following the IHCA test. Respiratory infections after the neonatal period were equally common in IUGR and AGA children; but infections were associated with subsequent IHCA responsiveness. Adenoidectomy, tonsillectomy, and/or myringotomy had been performed significantly more often in the responders than in the nonresponders. At least one of the above invasive procedures had been performed in 20 (32%) of the children; this group was termed the "ENT (ear, nose, throat) surgery group." Fifty-six percent of the responders, but only 26% of the nonresponders, belonged to the ENT surgery group (P = 0.02). We conclude that intrauterine growth retardation or prematurity is not associated with abnormal cold air responsiveness in the IHCA test.

Adolescent↗
PubMed1999

Mathematical modelling of non-invasive oscillometric finger mean blood pressure measurement by maximum oscillation criterion.

A mathematical study is performed to assess how the arterial pressure-volume (P-V) relationship, blood pressure pulse amplitude and shape affect the results of non-invasive oscillometric finger mean blood pressure estimation by the maximum oscillation criterion (MOC). The exponential models for a relaxed finger artery and for a partly contracted artery are studied. A new modification of the error equation is suggested. This equation and the results of simulation demonstrate that the value of pressure estimated by the MOC does not exactly agree with the value of the true mean blood pressure (the latter being defined as pressure corresponding to maximum arterial compliance). The error depends on the arterial pressure pulse amplitude, as well as on the difference between the arterial pressure pulse shape index and the arterial P-V curve shape index. In the case of contracted finger arteries, the MOC can give an overestimation of up to 19 mmHg, the pressure pulse shape index being 0.21 and the pulse amplitude 60 mmHg. In the case of relaxed arteries, the error is less evident.

Blood Pressure Determination↗
PubMed1999

A fractal approach for evaluation of pulmonary circulation in man at rest and during exercise.

Changes in pulmonary circulation caused by muscular exercise and body position are usual in daily life. By using first-pass radiocardiography and fractal analysis, pulmonary circulation in man was evaluated at rest and during muscular exercise. At rest, pulmonary circulation was heterogeneous as described by the relative dispersion (which is the coefficient of variation, i.e. the standard deviation of the pulmonary transit times divided by the mean transit time; RD = 0.51 +/- 0.06) and fractal in nature. During exercise, pulmonary circulation became more homogeneous (RD = 0.35 +/- 0.04; P < 0.001). The calculated fractal dimension decreases from 1.09 at rest to 1.06 during exercise. The model identifies a cubic-law response for circulation heterogeneity and a quarter-power law for resistance during muscular exercise.

Adult↗
PubMed1999

Transit time heterogeneity of bolus flow through the heart and lungs in patients with left-to-right intracardiac shunt.

Knowledge of the contributions of transit time heterogeneity to the cardiopulmonary system is important for understanding cardiopulmonary function in patients with intracardiac shunt. We determined the heterogeneity of blood transit times occurring between the right atrium and the left ventricle. Eighty two patients with suspected left-to right shunt were investigated with first-pass 99mTc-labelled red blood cell radiocardiography at supine rest. Forty two of them had a pulmonary-to-systemic flow ratio (Qp:Qs) of less than 1.2 and they served as a control group. The remaining study subjects had a Qp:Qs ratio of 1.7 +/- 0.3 (mean +/- SD). The patients with shunt had significantly greater (p < 0.001) heterogeneity of transit times (49 +/- 9%) than in the controls (39 +/- 7%). Overall heterogeneity of cardiopulmonary transit times in patients with shunt showed a curvature relationship; the highest values were centred in patients with moderate to severe shunt (1.5 < Qp:Qs < 2.5). The results suggest that the increased heterogeneity of transit times mainly occurs within the pulmonary capillary bed in patients with intracardiac shunt. This is probably due to the recruitment of the open capillaries without vessel distension.

Adolescent↗
PubMed1999

Effect of radiochemical purity of 99Tcm-Q12 on myocardial SPET image quality.

In myocardial perfusion SPET studies with 99Tcm-Q12, we observed that some patients had high liver uptake that interfered significantly in the assessment of the inferior wall. The aim of this study was to assess the effects of the radiochemical purity of 99Tcm-Q12 on liver uptake. Thirty-one patients undergoing routine myocardial infarction perfusion studies were evaluated. The radiochemical purity of 99Tcm-Q12 was determined using HPLC. Venous blood samples taken 50 min after injection of 99Tcm-Q12 during peak exercise were also analysed. Liver uptake was expressed as the liver-to-heart ratio. In addition, the SPET images were classified by two experienced nuclear medicine specialists into three groups representing high-quality images (n = 7), images with high general background activity (n = 13) and images with high liver and/or intestinal uptake (n = 11). The liver-to-heart ratio correlated inversely with the radiochemical purity of 99Tcm-Q12 (r = -0.65, P < 0.001) and unchanged 99Tcm-Q12 in plasma (r = -0.44, P < 0.02). The radiochemical purity of 99Tcm-Q12 was significantly lower in the group with high liver uptake (60.1 +/- 4.2%) than in the group with good-quality images (81.8 +/- 5.6%, P < 0.01) or with high background activity (82.3 +/- 2.5%, P < 0.01). In conclusion, the radiochemical purity of 99Tcm-Q12 has a significant inverse correlation with the liver-to-heart ratio; thus, the high radiochemical purity of 99Tcm-Q12 should be confirmed to prevent interference by liver uptake.

Chromatography, High Pressure Liquid↗
PubMed1999

Sympathovagal balance is major determinant of short-term blood pressure variability in healthy subjects.

Short-term blood pressure variability (BPV) has been suggested to provide important information about cardiovascular regulation. However, the background of BPV, its determinants, and physiological correlates have remained obscure. The aim of this study was to characterize physiological correlates of BPV and to investigate associations between BPV and neural and hormonal regulatory systems at rest in healthy subjects. We studied 117 healthy, normal-weight, nonsmoking male and female subjects aged 23-77 yr. Spectral analysis of BPV and heart rate variability (HRV) was performed from 5-min blood pressure (Finapres) and electrocardiogram recordings during controlled breathing. Baroreflex sensitivity (BRS) was measured using the phenylephrine method. In addition, plasma concentrations of norepinephrine, epinephrine, and arginine vasopressin and plasma renin activity were measured. We found that the ratio between the low- and high-frequency components of HRV, an index of cardiac sympathovagal balance, correlated positively with total power and very low- and low-frequency components of systolic and diastolic BPV and inversely with high-frequency components of systolic and diastolic BPV. BRS, predominantly a measure of cardiac vagal regulation, correlated inversely with BPV. Furthermore, age, gender, body mass index, and systolic blood pressure contributed to BPV. Vasoactive hormones were not significant correlates of BPV. We conclude that sympathovagal balance of cardiovascular regulation is the major determinant of BPV. Other factors associated with BPV are age, gender, body mass index, blood pressure, and BRS.

Adult↗
PubMed1999

Evaluation of scatter correction using a single isotope for simultaneous emission and transmission data. Phantom and clinical patient studies.

UNLABELLED: Photon scatter is one of the most important factors degrading the quantitative accuracy of SPECT images. Many scatter correction methods have been proposed. The single isotope method was proposed by us. AIM: We evaluate the scatter correction method of improving the quality of images by acquiring emission and transmission data simultaneously with single isotope scan. METHOD: To evaluate the proposed scatter correction method, a contrast and linearity phantom was studied. Four female patients with fibromyalgia (FM) syndrome and four with chronic back pain (BP) were imaged. Grey-to-cerebellum (G/C) and grey-to-white matter (G/W) ratios were determined by one skilled operator for 12 regions of interest (ROIs) in each subject. RESULTS: The linearity of activity response was improved after the scatter correction (r = 0.999). The y-intercept value of the regression line was 0.036 (p < 0.0001) after scatter correction and the slope was 0.954. Pairwise correlation indicated the agreement between nonscatter corrected and scatter corrected images. Reconstructed slices before and after scatter connection demonstrate a good correlation in the quantitative accuracy of radionuclide concentration. G/C values have significant correlation coefficients between original and corrected data. CONCLUSION: The transaxial images of human brain studies show that the scatter correction using single isotope in simultaneous transmission and emission tomography provides a good scatter compensation. The contrasts were increased on all 12 ROIs. The scatter compensation enhanced details of physiological lesions.

Back Pain↗
PubMed1998

Fentanyl decreases beta-CIT binding to the dopamine transporter.

Evidence from animal studies suggest that centrally acting opiates increase synaptic dopamine (DA) concentration. However, the interaction between mu-opioid receptors and the DA system is unclear. We report here an effect of fentanyl on striatal [123I]beta-CIT binding to the DA transporter in a patient and in rats. A female patient underwent [123I]beta-CIT single-photon emission tomography (SPET) study after intrathecal injection of fentanyl for her back pain. After a 2-week drug-free period, the SPET study was repeated. In the experimental study, male Wistar rats were treated with fentanyl either acutely (50 micrograms/kg, i.p.) before imaging study or subacutely for 4 days (10 micrograms/kg, twice a day, i.p.). Brain planar imaging was performed at 3.5 hours after an intravenous injection of [123I]beta-CIT with gamma camera with a pinhole collimator. In a female patient, [123I]beta-CIT binding in the basal ganglia was decreased by 37% during fentanyl as compared to the binding after 2-week drug-free period. Similarly in rats, acute fentanyl treatment decreased [123I]beta-CIT binding to the striatum by 30% as compared to that of with the control rats. After subacute administration of fentanyl, no significant difference was observed compared to the control group. According to the present data, fentanyl decreases [123I]beta-CIT binding in the basal ganglia both in human and rats, suggesting that opiates possibly directly affect DA reuptake.

Adult↗
PubMed1998

Effects of intrauterine growth retardation and prematurity on spirometric flow values and lung volumes at school age in twin pairs.

Lung volumes and pulmonary expiratory flow values were investigated in 67 children from multiple pregnancies (30 twins, one set of triplets, one set of quadruplets) at the age of 7-15 years. At birth, 30 of 67 children (44%) had intrauterine growth retardation (IUGR, birth weight <-2 SD or birth weight difference between twin-pairs >1.3 SD). The median gestational age was 35 weeks (range, 28-38 weeks), and the median birth weight was 2,050 g (800-3,150 g). Lung functions were measured with a heated pneumotachograph. Data were standardized using height-based reference equations. No differences were found in lung volumes between children with IUGR and those children who had normal birth weight. Gestational age did not correlate with either airway flow rates or lung volumes. Maximum mid-expiratory flow (FEF50) did not correlate with standardized birth weight or with gestational age. In discordant twin pairs, the IUGR twins had significantly lower FEF50 than their normal birth weight counterparts (p=0.03, Z=-2.13). In the whole study group (67 children), children with IUGR had significantly lower FEF50 than children with normal birth weight (p=0.04; CI, 0.3-19.9). We propose that IUGR has the most pronounced effect on the growth of airways, and no detectable influence on lung volumes. This study confirms the crucial effect of appropriate intrauterine growth on subsequent growth on pulmonary airways.

Birth Weight↗
PubMed1998

Iodine-123 labeled nor-beta-CIT as a potential tracer for serotonin transporter imaging in the human brain with single-photon emission tomography.

Iodine-123 labelled 2beta-carbomethoxy-3beta-(4-iodophenyl) (nor-beta-CIT) is an analogue of beta-CIT, which has high affinity to the serotonin transporter. Initial single-photon emission tomography (SPET) studies with [123I]nor-beta-CIT were performed in five healthy volunteers. In addition, its metabolism in plasma was investigated with gradient high performance liquid chromatography. [123I]nor-beta-CIT was prepared by a method which gave a specific radioactivity of more than 180 GBq/micromol. Unchanged [123I]nor-beta-CIT in plasma accounted for 43% and 19% of total radioactivity after 30 and 180 min, respectively. The dynamic SPET studies demonstrated a high and rapid uptake of radioactivity in the brain (6%/ID at 30 min). Highest accumulation was observed in the striatum, the mid-brain and the thalamus. The specific binding in the mid-brain was 33% higher compared with that of [123I]beta-CIT. The high radioactivity in the mid-brain is assumed to represent the accumulation of [123I]nor-beta-CIT in the serotonin transporter-rich regions, which indicates that [123I]nor-beta-CIT might be a potential tracer for visualization of serotonin transporter sites in the human brain with SPET.

Adult↗
PubMed1998

Does plasma L-arginine level play a role in regulation of blood pressure during exercise and autonomic nervous function?

Little is known of L-arginine's role in autonomic nervous regulation and physiological responses to dynamic exercise. We assessed heart rate and blood pressure during a maximal bicycle ergometer test and heart rate variability at rest in 15 healthy male volunteers, age 22-38 years. Venous blood samples for plasma L-arginine measurements were taken when subjects were sitting at rest before and at the end of exercise. The autonomic nervous function was assessed with time and frequency domain analysis of heart rate variability. Plasma L-arginine level decreased during maximal exercise from 71.4 mumol l-1 to 51.0 mumol l-1 (P < 0.0001) for all subjects studied. The systolic blood pressure during the maximal exercise test was inversely correlated with plasma L-arginine level at rest (r = -0.70, P < 0.01). Normalized low frequency band of power spectral analysis of heart rate variability correlated with L-arginine level at rest (r = 0.66, P < 0.01). In conclusion, plasma L-arginine level decreased in physical exercise, and plasma L-arginine level at rest was positively associated with the sympathetic component of power spectral analysis of heart rate variability at rest, and inversely with systolic blood pressure during physical exercise.

Adult↗
PubMed1998

Determinants of bone mineral density in prematurely born children aged 6-7 years.

The aim of this study was to assess the long-term effects of prematurity and growth during the first year on bone mineralization in prematurely born children. The study group consisted of 38 prematurely born Finnish children (17M, 21F) examined at the age of 6-7 y. After birth, all children were fed with banked human milk until discharge from hospital. Thereafter, 27 children were partially breastfed until the age of 5-7 months. Infants with gestational age (GA) < or = 33 weeks (n = 25) received calcium 45-50 mg/100 kcal, phosphorus 40-45 mg/100 kcal, vitamin A 1000 IU/d, vitamin C 2 mg/d and vitamin D 400 IU/d until 2.5 kg. Infants born > 33 weeks received only vitamin D 400 IU/d. Bone mineral density (BMD) and bone mineral content (BMC) were measured by dual energy X-ray absorptiometry (DXA) of the lumbar spine (L2-L4) at 6-7 y of age. At examination, all children had normal height and weight. BMD values were within the confidence interval of the Finnish reference values. In regression analysis bone area, present weight, GA and weight at 1 y were the most significant factors explaining 77.1% of the variance of BMC. After adjusting for other independent variables the prematurely born children who were thinner at 1 y of age subsequently had higher BMC values when examined at the age of 6-7 y. This study shows that growth patterns during the first year of life have long-term effects on bone mineralization.

Absorptiometry, Photon↗
PubMed1998

Age and gender dependency of baroreflex sensitivity in healthy subjects.

We evaluated the correlates of baroreflex sensitivity (BRS) in healthy subjects. The study consisted of 117 healthy, normal-weight, nonsmoking male and female subjects aged 23-77 yr. Baroreflex control of heart rate was measured by using the phenylephrine bolus-injection technique. Frequency- and time-domain analysis of heart rate variability and an exercise test were performed. Plasma norepinephrine, epinephrine, insulin, and arginine vasopressin concentrations and plasma renin activity were measured. In the univariate analysis, BRS correlated with age (r = -0.65, P < 0.001), diastolic blood pressure (r = -0.47, P < 0.001), exercise capacity (r = 0.60, P < 0.001), and the high-frequency component of heart rate variability (r = 0.64, P < 0.001). There was also a significant correlation between BRS and plasma norepinephrine concentration (r = -0.22, P < 0.05) and plasma renin activity (r = 0.32, P < 0.001). According to the multivariate analysis, age and gender were the most important physiological correlates of BRS. They accounted for 52% of interindividual BRS variation. In addition, diastolic blood pressure and high-frequency component of heart rate variability were significant independent correlates of BRS. BRS was significantly higher in men than in women (15.0 +/- 1.2 vs. 10.2 +/- 1.1 ms/mmHg, respectively; P < 0.01). Twenty-four percent of women > 40 yr old and 18% of men > 60 yr old had markedly depressed BRS (< 3 ms/mmHg). We conclude that physiological factors, particularly age and gender, have significant impact on BRS in healthy subjects. In addition, we demonstrate that BRS values that have been proposed to be useful in identifying postinfarction patients at high risk of sudden death are frequently found in healthy subjects.

Adult↗