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Biomedical subjects

T Kuusela

Publications and source records attributed to T Kuusela.

At least 19 recordsLinked to original sources
PubMed2003

Reduced heart rate variability in hypertension: associations with lifestyle factors and plasma renin activity.

Limited information exists on the relations between heart rate variability, hypertension, lifestyle factors and renin-angiotensin-aldosterone system. A total of 191 newly diagnosed yet untreated hypertensive men and women, 35-54 years of age, were compared with an age- and gender-stratified random population sample of 105 normotensive men and women to find out independent determinants of heart rate variability. Heart rate variability was computed from 5-min ECG time series using the standard deviation of normal-to-normal RR intervals (SDNN), the square root of the mean of squared differences between adjacent normal RR intervals (RMSSD) and the fast Fourier transform spectral analysis. All absolute measures of heart rate variability were reduced in hypertension (P<0.001 for each, ANOVA). In multivariate regression analyses, reduced heart rate variability was independently associated with higher heart rate (P<0.001 for all absolute measures of heart rate variability), higher age (P=0.001 for SDNN, total and LF powers; P<0.001 for RMSSD and HF power) and higher mean arterial pressure (P<0.05 for total power, P<0.01 for the other absolute measures) but not with sodium and alcohol intakes, body mass index and smoking. Increased plasma renin activity (PRA) was an independent attributor of reduced HF power (P<0.05) and reduced RMSSD (P<0.01). Increased blood pressure and heart rate are associated with decreased heart rate variability without any direct effects on heart rate variability of lifestyle factors. High PRA is an independent determinant of diminished modulation of vagal activity.

Adult↗
PubMed2002

Cardiovascular effects of ophthalmic 0.5% timolol aqueous solution and 0.1% timolol hydrogel.

The objective of this randomized, double-masked, cross-over study was to compare the cardiovascular effects of two glaucoma formulations, ophthalmic 0.5% timolol aqueous solution and 0.1% timolol hydrogel. Twenty-four young healthy subjects received for 2 weeks either twice daily 0.5% timolol solution or once daily 0.1% timolol hydrogel. Heart rate (HR), blood pressure, atrio-ventricular conduction (PR interval), corrected QT time (QTc) and heart rate variability (HRV) were measured in supine position and during head-up tilted position. The mean peak concentrations of timolol in plasma were significantly higher after administration of 0.5% aqueous solution than after 0.1% hydrogel. A 0.5% timolol aqueous solution decreased HR on average by 3 bpm in supine position and by 7 bpm in head-up tilted position while no significant effects were observed with 0.1% timolol hydrogel. During tilt test HR was significantly lower after administration of timolol aqueous solution than after timolol hydrogel (mean +/- SD, 77 +/- 11 bpm versus 86 +/- 13 bpm, P < 0.05). Timolol aqueous solution slightly decreased QTc during tilt (5.9 +/- 5.6 ms, P < 0.01). During tilt tests, timolol aqueous solution slightly increased atrio-ventricular conduction (7.2 ms, P = 0.02). No significant differences were found in HRV. These results indicate that in healthy volunteers, ophthalmic 0.5% timolol aqueous solution produces more pronounced cardiac beta-blocking effects than 0.1% timolol hydrogel.

Adult↗
PubMed2001

The effects of amitriptyline, citalopram and reboxetine on autonomic nervous system. A randomised placebo-controlled study on healthy volunteers.

RATIONALE: In therapeutic use, amitriptyline, reboxetine and citalopram have all been associated with apparent anticholinergic-like side effects (dry mouth, constipation, etc.), despite the very low antimuscarinic activity of reboxetine and citalopram in vitro. OBJECTIVES: We hypothesised that the spectral analysis of heart rate variability (HRV) might detect differences between amitriptyline, citalopram and reboxetine in their anticholinergic activities following a single peroral administration. METHODS: In this double-blind, cross-over study, amitriptyline (75 mg), citalopram (20 mg), reboxetine (4 mg) and placebo were randomly given at 1-week intervals to eight healthy male volunteers. Drug and catecholamine concentrations in plasma were determined repeatedly. The drug effect was assessed with periodic recordings of electrocardiogram (ECG) and blood pressure, and with measurements of salivary secretion. The ECG recordings were subjected to spectral analysis of HRV, in which the high frequency (HF) power of R-R interval (RRI) variability was supposed to reflect cardiac parasympathetic tone. RESULTS: Reboxetine increased heart rate and blood pressure and reduced the HF power of RRI and 3,4-dihydroxyphenylglycol (DHPG) plasma concentrations. Amitriptyline diminished salivary secretion and had a prominent sedative action. Measurements after citalopram did not differ significantly from placebo. CONCLUSIONS: Reboxetine, despite its low antimuscarinic activity in vitro, had distinct effects on the HF power of RRI, consistent with anticholinergic activity in vivo. Amitriptyline had a measurable anticholinergic effect in the salivary glands, but, surprisingly, not in the heart. We suggest that the sedative effect of amitriptyline could alter cardiac sympathovagal balance and, therefore, counteract the anticholinergic drug effect.

Adolescent↗
PubMed2001

Time domain, geometrical and frequency domain analysis of cardiac vagal outflow: effects of various respiratory patterns.

The purpose of this study was to compare the applicability of four different measures of heart rate variability (HRV) in the assessment of cardiac vagal outflow, with special reference to the effect of breathing pattern. The anticholinergic effects of an intravenous glycopyrrolate infusion (5 microg x kg(-1) x h(-1) for 2 h) during spontaneous and controlled (15 min(-1)) breathing rate were investigated in eight volunteers, and the effects of different fixed breathing rates (6-15-24 min(-1)) and hyperventilation in 12 subjects. Cardiac vagal activity was assessed by ECG recordings in which the following measures of HRV were computed: the high-frequency (HF) spectral component, the instantaneous RR interval (RRI) variability (SD1) analysed from the Poincaré plots, the percentage of differences between successive RRIs greater than 50 ms (pNN50), and the square root of the mean squared differences of successive RRIs (RMSSD). On average, glycopyrrolate reduced the HF spectral component by 99.8%, SD1 by 91.3%, pNN50 by 100% and RMSSD by 97.0%. The change of breathing pattern from controlled to spontaneous decreased significantly the HF component and pNN50, but did not affect SD1 or RMSSD. Rapid breathing rate (24 min(-1)) decreased the HF component, but had no effects on the other measures. A controlled breathing rate is needed for a reliable assessment of cardiac vagal outflow by the spectral analysis technique. The quantitative geometrical analysis of short-term RRI variability from the Poincaré plots and the time domain measure RMSSD were not significantly affected by changes in the breathing rate, suggesting that these indices are more suitable for the measurement of cardiac vagal outflow during the 'free-running' ambulatory conditions.

Adult↗
PubMed2001

Spontaneous baroreflex sensitivity as a dynamic measure of cardiac anticholinergic drug effect.

1. In this study, the analysis of spontaneous baroreflex sensitivity (BRS) was applied to the dynamic assessment of cardiac anticholinergic drug effect in healthy male volunteers. 2. The anticholinergic effects of single intravenous (i.v.) injections of atropine (10 microg kg(-1)), glycopyrrolate (5 microg kg(-1)) and scopolamine (5 microg kg(-1)), as well as a 2-h infusion of glycopyrrolate (5 microg kg(-1) h(-1)) were investigated. Baroreflex sensitivity, a validated measure of cardiac parasympathetic reflex regulation, was repeatedly measured from 5-min recordings of electrocardiogram (ECG) and continuous blood pressure by using the sequence technique, a method based on detection of spontaneous fluctuations in blood pressure and heart rate. 3. Single injections of atropine, glycopyrrolate and scopolamine decreased the mean BRS by 71 +/- 32, 68 +/- 23 and 27 +/- 45%, respectively, whereas the slow glycopyrrolate infusion gradually decreased BRS (up to 83 +/- 11% reduction) and increased both systolic (SAP) and diastolic arterial pressures (DAP) (on an average, by 9 mmHg). 4. During the withdrawal of the parasympathetic blockade (indicated by increasing BRS), the proportion of baroreflex sequences in the recordings increased transiently from 10 up to 20-25%, probably reflecting the restoration of the baroreflex integrity and the baroreflex-induced attempt to counteract the blood pressure increase. 5. The sequence method to study BRS seems to be feasible in the assessment of cardiac anticholinergic drug effects, and it also provides good time resolution for the dynamic measurements.

Adult↗
PubMed2000

The effect of estrogen replacement therapy on cardiac autonomic regulation.

OBJECTIVE: To study the effects of estrogen replacement therapy (ERT) and sleep stage on autonomic cardiac regulation. SRUDY DESIGN: Seventy-one healthy postmenopausal women received transdermal ERT and placebo separated by a washout in a randomized, placebo-controlled, double-blind, cross-over trial. Polysomnography was conducted at the end of each treatment. Heart rate variability (HRV) was assessed in epochs of the awake state, stage 2, slow wave and REM sleep. The effects of estradiol and sleep stages on HRV were analyzed. RESULTS: ERT decreased heart rate in the awake state and quiet sleep, but not in REM sleep. ERT did not change the heart rate variability. Heart rate decreased and HRV increased during stage 2 and slow wave sleep compared with the awake state with placebo. In REM sleep, similarly, heart rate increased above awake values and the values of HRV parameters fell back to awake levels. CONCLUSIONS: The results suggest that ERT increases vagal tone, but does not change cardiac vagal modulation. Changes in HRV suggest a strong vagal influence in non-REM and a sympathetic influence in REM sleep.

Administration, Cutaneous↗
PubMed1999

Spectral analysis of heart rate variability as a quantitative measure of parasympatholytic effect--integrated pharmacokinetics and pharmacodynamics of three anticholinergic drugs.

The time course and concentration-effect relationship of parasympatholytic effects of three anticholinergic drugs were investigated using spectral analysis of heart rate (HR) variability. Single intravenous (i.v.) doses of atropine (10 microg/kg), glycopyrrolate (5 microg/kg), scopolamine (5 microg/kg), and placebo were given to eight healthy volunteers in a double-blind, randomized cross-over study. Electrocardiogram (ECG) was recorded at baseline and 2.5, 5, 10, 20, and 30 minutes, and 1, 1.5, 2, 3, 4, 5, and 6 hours after drug administration, while the subjects breathed at a fixed 0.25 Hz frequency. The powers of two frequency bands (low frequency [LF] = 0.07-0.15 Hz and high frequency [HF] = 0.15-0.40 Hz) were calculated using stationary time series of R-R intervals (RRI) free from ectopic beats. To perform pharmacokinetic-pharmacodynamic (PK-PD) modeling, venous plasma drug concentrations were measured. Atropine and glycopyrrolate, and, to a lesser extent, scopolamine induced decreases in HF power and increases in LF/HF ratio of HR variability, indicating parasympatholytic activity and corresponding changes in sympathovagal balance. Maximal average decreases in HF power were 99%, 94%, and 82%, respectively, but in two scopolamine subjects, a parasympathomimetic effect was dominant. Interindividual variability was least for the Hayano index of HF power (square root (RRI HF-power)/RRI*100), and profound and consistent decreases were seen after atropine and glycopyrrolate. Pharmacokinetics were best fitted to a two-compartment open model, and effect compartment link modeling using the Hayano index was performed with the atropine and glycopyrrolate data. The best description of the PK-PD relationship for both drugs was achieved using the sigmoidal Emax model. Mean (+/-SD) EC50, sigmoidicity factor (gamma), and equilibration rate constant (k(e0)) estimates were 1.35 (+/-0.27) ng/mL, 6.07 (+/-1.98) and 11.0 (+/-5.28) l/h for atropine and 1.35 (+/-0.49) ng/mL, 4.34 (+/-1.55) and 2.26 (+/-0.81) l/h for glycopyrrolate. Spectral analysis of HR variability appears to be a powerful tool in monitoring parasympatholytic drug activity. A sigmoidal Emax model with an extremely steep concentration-response relationship was revealed for atropine and glycopyrrolate. The effects of scopolamine were more incongruous.

Adult↗
PubMed1999

Improving the false nearest neighbors method with graphical analysis.

We introduce a graphical presentation for the false nearest neighbors (FNN) method. In the original method only the percentage of false neighbors is computed without regard to the distribution of neighboring points in the time-delay coordinates. With this presentation it is much easier to distinguish deterministic chaos from noise. The graphical approach also serves as a tool to determine better conditions for detecting low-dimensional chaos, and to get a better understanding on the applicability of the FNN method.

Journal Article↗
PubMed1998

Observer variation in classifying chest radiographs for small lung opacities and pleural abnormalities in a population sample.

BACKGROUND: The purpose of this study was to assess inter-and intraobserver variation in the radiographic categories of small lung opacities (profusion) and pleural abnormalities classified according to the ILO classification of pneumoconioses with some modifications. METHODS: Chest radiographs derived from a representative adult population sample (n = 7,095) were classified by two radiologists. Observer variation was assessed on the basis of kappa (kappa)-type statistics. RESULTS: The observers agreed on profusion categories in 69% of cases of the total material. Up to 98% of the classifications fell into the same category or deviated by no more than one category. The corresponding kappa (kappa) coefficient was 0.48 (95% CI = 0.46=0.49) and the weighted kappa 0.72. When a selected subsample was reclassified by the observers, the proportions of crude agreement on profusion of small opacities ranged from 42% to 47% (weighted kappa 0.52-0.55). The proportions of agreement on the main pleural abnormalities were 92% or over, and the corresponding kappa coefficients at least 0.73. CONCLUSION: The classification of lung opacities was subject to considerable observer variation, which calls for caution when results from different studies are compared. This variation, however, rarely exceeded one category, and thus appears to be small enough for meaningful comparisons between groups, at least within a single study.

Adult↗
PubMed1997

The acute effects of inhaled salbutamol on the beat-to-beat variability of heart rate and blood pressure assessed by spectral analysis.

AIMS: We wanted to study the effects of a 600 micrograms inhaled salbutamol dose on the cardiovascular and respiratory autonomic nervous regulation in eight children suffering from bronchial asthma. METHODS: In this randomized, double-blind, placebo-controlled, crossover study we continuously measured electrocardiogram, finger systolic arterial pressure (SAP) and flow-volume spirometry at baseline as well as 20 min and 2 h after the drug inhalation. The R-R interval (the time between successive heart beats) and SAP variabilities were assessed by using spectral analysis. Baroreflex sensitivity was assessed by using cross-spectral analysis. RESULTS: Salbutamol significantly decreased the total and low frequency (LF) variability of R-R intervals as well as the high frequency (HF) variability of R-R intervals and of SAP. Salbutamol significantly increased the LF/HF ratio of R-R intervals and of SAP, minute ventilation, heart rate and forced pulmonary function in comparison with placebo. The weight of the subjects significantly correlated positively with baroreflex sensitivity and negatively with heart rate after the salbutamol inhalation. CONCLUSIONS: We conclude that the acute salbutamol inhalation decreases cardiovagal nervous responsiveness, increases sympathetic dominance in the cardiovascular autonomic balance, and has a tendency to decrease baroreflex sensitivity in addition to improved pulmonary function.

Administration, Inhalation↗
PubMed1996

Radiographic small lung opacities and pleural abnormalities in relation to smoking, urbanization status, and occupational asbestos exposure in Finland.

The role of smoking and an urban living environment in the etiology of radiographic pleural and pulmonary abnormalities was studied in a population sample that was representative of the Finnish adult population. A total of 7095 full-size chest radiographs were classified according to the International Labor Organization's 1980 classification of radiographs of pneumoconioses, with some modifications. The risk of bilateral pleural plaques was significantly higher among urban men (RR, 2.0) and women (RR, 3.8), even when adjusted for age and probability of occupational asbestos exposure and smoking. The risks of small lung opacities and abnormalities of the visceral pleura were not higher in urban areas. Risks of small lung opacities and thickening of the visceral pleura were positively associated with smoking, and the risk of small lung opacities was also higher among smokers than never-smokers in the population fraction with unlikely occupational asbestos exposure.

Adult↗
PubMed1995

Radiographic small lung opacities and pleural abnormalities as a consequence of asbestos exposure in an adult population.

OBJECTIVES: The purpose of this study was to estimate the role of past asbestos exposure as a cause of radiographic small lung opacities and pleural abnormalities in the Finnish adult population. METHODS: The study was conducted in 1978-1981 and was based on a population sample (N = 8000) representative of the Finnish population aged 30 years or over. Full-size chest radiographs and a complete job title history were available for 3811 women and 3274 men. The radiographs were classified according to the 1980 classification of radiographs of pneumoconioses published by the International Labour Office and the work histories according to the probability of occupational asbestos exposure. Age- and smoking-adjusted relative risks of radiographic parenchymal and pleural abnormalities were calculated with the analysis of covariance according to the probability of asbestos exposure. RESULTS: About 13% of the men and 0.8% of the women were classified as probably exposed to asbestos. There was more than 90% agreement in the repeated work history evaluations. The risk of small lung opacities was significantly increased among the probably exposed men [risk ratio (RR) 1.7 for ILO profusion category 1/1 or more and RR 1.6 for profusion category 1/0]. The risk of pleural plaques was increased both among the men (RR 3.0) and the women (RR 4.8) with probable exposure. The risk of thickened horizontal interlobar fissure was also increased among the probably exposed men (RR 1.7). Among the men, the etiologic fraction attributable to occupational asbestos exposure was about 30% for small lung opacities, about 40% for pleural plaques, and about 20% for thickened horizontal fissure. Among the women the etiologic fractions for asbestos were similar for pleural abnormalities, but much lower for parenchymal ones. CONCLUSIONS: Occupational asbestos exposure has been common among Finnish men, and it plays a significant role in the etiology of both pleural and parenchymal abnormalities also at the level of the general population.

Adult↗
PubMed1994

Seven-year follow-up of white-finger symptoms and radiographic wrist findings in lumberjacks and referents.

OBJECTIVES: In 1978, a cross-sectional study of 279 lumberjacks exposed to hand-arm vibration and 178 unexposed referents was conducted. The aim of the present study was to provide a seven-year follow-up on (i) the changes in the white-finger symptoms among the lumberjacks and the referents, (ii) the effect of white-finger symptoms on the professional prognosis of the lumberjacks, and (iii) the relationship between hand-arm vibration and changes in wrist bones. METHODS: The methods consisted of a questionnaire, a routine clinical examination, and radiographs of the wrists and hands. The examinations were conducted as a field study using a mobile unit. RESULTS: The prevalence of white-finger symptoms was 18% among the lumberjacks and 3% among the referents in the original study. Seven years later 213 lumberjacks and 140 referents participated in the follow-up. The prevalence of white-finger symptoms was 24.9 among the lumberjacks and 5.7 among the referents, and the seven-year cumulative incidence was 14.7% among the lumberjacks and 2.3% among the referents. After allowance for age, there was no difference in the incidence of white-finger symptoms between the lumberjacks with fewer than 15 years of exposure and the referents, but the risk increased with increasing duration of exposure (risk ratio 8.9, 95% confidence interval 2.5-28.9 for those exposed at least 25 years). There was no difference between the two groups in the prevalence of radiographically detectable translucencies or osteoarthrotic changes in the wrists and hands. CONCLUSION: According to the results, white-finger symptoms are still a problem among lumberjacks who started chain-saw work before 1970.

Adult↗
PubMed1993

Acute dislocation of the patella: MR findings.

PURPOSE: The authors describe magnetic resonance (MR) imaging findings of acute traumatic dislocation of the patella. MATERIALS AND METHODS: MR imaging at 0.1 T was performed in 25 patients with an acute patellar dislocation, 24 of whom underwent surgery. All patients were young male conscripts, aged 18-22 years. RESULTS: Signal intensity abnormalities of bone, seen as areas of decreased signal intensity on T1-weighted images, were found in all 25 patients (100%). The lateral femoral condyle was involved in all cases. Signal intensity changes also appeared in the patella in eight patients and in the lateral tibial plateau in three. Osteochondral fragments seen at plain radiography and cartilage fissuring noted at arthroscopy were not visible at MR imaging. Injury of the medial patellar retinaculum was seen at MR in each case. All patients had a joint effusion. Lateral subluxation of the patella was a common finding. CONCLUSION: Constant findings at MR imaging were (a) contusion of the lateral femoral condyle, (b) tear of the medial retinaculum, and (c) joint effusion.

Acute Disease↗
PubMed1993

Degeneration of cervical intervertebral disks in fighter pilots frequently exposed to high +Gz forces.

This study investigated the occurrence and the degree of cervical disk degeneration among senior fighter pilots frequently exposed to high +Gz forces, compared with nonexposed controls matched for age and sex. A resistive magnetic resonance (MR) scanner operating at 0.1 T was used to image the cervical intervertebral disks. Sagittal MR images were obtained and disk degeneration was graded 0-6. Both the occurrence and the median degree of disk degeneration were greater among the pilots than among the controls. The greatest difference in the occurrence of disk degeneration (grades 1-6), which also reached statistical significance, was detected for the C3-4 disk: 88% among the fighter pilots and 64% among the controls, respectively. With respect to the moderate degenerative changes (grades 3 and 4) in the C3-4 disk, the difference in the occurrence (88% vs. 36%) was again statistically significant. There was no difference between the other disks. The median disk degeneration between the groups differed (2.0 vs. 1.0), the difference being the most remarkable (3.0 vs. 1.0) for the C3-4 disk. The differences in the median disk degeneration were also statistically significant. These findings suggest that frequent exposure to high +Gz forces may cause premature disk degeneration.

Adult↗