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Biomedical subjects

A Nygren

Publications and source records attributed to A Nygren.

At least 37 records · Page 2Linked to original sources
PubMed2000

Voltage-sensitive dye mapping of activation and conduction in adult mouse hearts.

A custom-made apparatus based on a charge-coupled-device camera has been used to monitor changes in fluorescence from Langendorff-perfused adult mouse hearts stained with a voltage-sensitive dye, di-4-ANEPPS. With this approach it is possible to monitor activation of the ventricles at high temporal (375 micros/frame) and spatial resolution (72 x 78 pixels, 100 x 100 microm/pixel). In sinus rhythm, activation occurred with a complicated breakthrough pattern on both ventricles, and a total activation time of 3.51+/-0.16 ms (32 degrees C). A stimulus applied near the apex of the left ventricle resulted in a single activation wave front with a total activation time of 8.18+/-0.25 ms. Pacing from a site near the middle of the left ventricular epicardial surface revealed anisotropic conduction, indicating that conduction occurs preferentially in the direction of the predominant fiber orientation. The total activation time in this configuration was 5.44+/-0.24 ms. The difference in total activation time between sinus rhythm and epicardial stimulation suggests an important role for transmural conduction (the Purkinje system) in the mouse heart. These findings provide much of the necessary background needed for studying conduction abnormalities in genetically altered mice and suggest that the comparison of sinus rhythm and epicardial pacing can be used to reveal transmural conduction abnormalities.

Animals↗
PubMed2000

Preoperative evaluation and surgery in isolated ventricular septal defects: a 21 year perspective.

OBJECTIVE: To study short and long term results after surgical closure of isolated ventricular septal defects (VSDs) from 1976 to 1996, especially in relation to changes in preoperative evaluation during this period. DESIGN: Retrospective study. SETTING: Tertiary referral centre for paediatric cardiac care. PATIENTS: All children under 18 years of age who had corrective surgery for VSD between 1976 and 1996. MAIN OUTCOME MEASURES: Preoperative evaluation, indications for surgery, diagnostic errors, and early and late results. RESULTS: A significant decrease in the use of invasive preoperative studies in favour of non-invasive methods was found; from 1976 to 1990, a total of 109/110 patients had preoperative invasive study as compared to 43/167 from 1991 to 1996 (p < 0.001). Pulmonary hypertension in small children, without detailed information on Qp:Qs ratio, as well as small or modest shunts without pulmonary hypertension, were more frequent indications for surgery in recent years. Early mortality after surgery occurred in 10 patients, with a significantly lower mortality rate found between 1991 and 1996 than between 1976 and 1990 (0.6% v 8.2%, p < 0.001). Children with large VSDs experienced perioperative complications significantly less often between 1991 and 1996 than between 1976 and 1990 (16/105 v 28/96, p < 0.05). Diagnostic errors showed a tendency to decrease between the two time periods. No late deaths occurred. CONCLUSIONS: Significant reductions in early mortality, perioperative complications, and diagnostic mistakes were seen during the study period, even though less invasive diagnostic procedures were being performed.

Adolescent↗
PubMed2000

Impact of occupation on respiratory disease.

OBJECTIVES: This study identified occupations with a marked impact on sick leaves due to respiratory disease. METHODS: A national sick-leave register containing information on all sick leaves exceeding 14 days, physicians' diagnoses, and the occupational status of all manual and service employees in the private sector in Sweden was studied. Sick leaves during 1992-1994 (N=210,755) were analyzed with special attention to respiratory disease and occupation. RESULTS: Respiratory disease accounted for 4.4% of the total number of sick leaves. The incidence of long-term (> or = 90 days) sick leaves due to respiratory disease was 3 times higher in occupations with a high incidence than in those with a low incidence. There was a high correlation (r=0.80) between the incidence of long-term sick leave due to respiratory disease and sick leave due to all other conditions; this finding suggests that market and selection factors may play an important role in determining the overall risk for sick leave in various occupations. The proportion of sick leaves due to long-term respiratory disease out of all long-term disease was compared between occupations. Agricultural workers had a 46% higher proportion of long-term respiratory disease than metal workers. Industrial workers, food industry workers, and painters were also occupations with an increased risk. These findings could not be explained by differences in age or smoking habits. CONCLUSIONS: Major differences were found among manual and service occupations regarding long-term sick leave due to respiratory disease. Several occupations, in which exposure to respiratory sensitizers and irritants are known to occur, were among those in which workers had an increased risk for long-term respiratory disease.

Adult↗
PubMed1999

A general approach to modeling conduction and concentration dynamics in excitable cells of concentric cylindrical geometry.

This paper discusses mathematical approaches for modeling the propagation of the action potential and ion concentration dynamics in a general class of excitable cells and cell assemblies of concentric cylindrical geometry. Examples include myelinated and unmyelinated axons, single strands of interconnected cardiac cells and outer hair cells. A key feature in some of the cells is the presence of a small working volume such as the periaxonal space between the myelin sheath and the axon in the myelinated axon and the extracisternal space between the plasma membrane and the subsurface cisterna of the outer hair cell. Proper treatment of these cell types requires a modeling approach which can readily address these anatomical properties and the non-uniform biophysical properties of the concentric membranes and the ionic composition of the volumes between the membranes. An electrodiffusion approach is first developed in which the Nernst-Planck equation is used to characterize axial ion fluxes. It is then demonstrated that this "full" model can be stepwise reduced, eventually becoming equivalent to the standard cable equation formulation. This is done in a manner that permits direct comparisons between the full and simplified models by running simulations using a single parameter set. An intermediate approach where the contributions of the axial currents to ion concentration changes and the effect of varying ion concentrations on solution conductivities are ignored is derived and is found adequate in many cases. Two application examples are given: a "cardiac strand" model, for which the intermediate formulation is shown sufficient and a model of the myelinated axon, for which the full electrodiffusion formulation is clearly necessary. The latter finding is due to spatial inhomogeneities in the anatomy and distribution of ion channels and transporters in the myelinated axon and the restricted periaxonal space between the myelin sheath and the axon.

Action Potentials↗
PubMed1999

A physiotherapy test package for assessing back and neck dysfunction--discriminative ability for patients versus healthy control subjects.

BACKGROUND AND PURPOSE: A physiotherapy test package of 10 tests designed for assessing dysfunction due to back or neck pain was tested for its ability to discriminate between back- or neck-pain sufferers and healthy control subjects. Twenty-seven patients and 26 healthy control subjects participated in the study. METHOD: Fifteen patients suffering from back or neck pain and 15 matched healthy control subjects were assessed using the package to compare the results between the groups. The results from a further 12 back- or neck-pain sufferers and 11 unmatched healthy control subjects were analysed with respect to sensitivity and specificity, cluster formation and correlation with ratings of pain and perceived exertion. RESULTS: The differences in the test results for the patients and the matched healthy control subjects were highly significant in all variables but one. High sensitivity for cut-off points of clinical relevance was found in all variables but one, whereas specificity was moderate in most variables. CONCLUSIONS: Despite the small sample size, the significant differences between patients and healthy control subjects, with the sensitivity and specificity figures, suggest that the content validity of the test package is satisfactory.

Adult↗
PubMed1999

Intra- and inter-rater reliability of an 11-test package for assessing dysfunction due to back or neck pain.

BACKGROUND AND PURPOSE: The intra- and inter-rater reliability of 11 tests assembled by physiotherapists for clinical purposes was investigated. Forty-five patients and 23 healthy volunteers participated in the study. METHOD: Twenty-one patients were tested simultaneously and independently by two physiotherapists to determine inter-rater reliability for two raters. Twenty-four patients and 11 healthy volunteers were tested by one physiotherapist three times in a week to determine intra-rater reliability over time. Twelve healthy volunteers were tested by three different physiotherapists in a week to determine inter-rater reliability for three raters. RESULTS: Inter-rater agreement for two simultaneous raters was clinically acceptable. Repeatability on three test occasions was clinically acceptable in six of the 11 tests. There were no systematic differences between occasions. CONCLUSIONS: Intra- and inter-rater reliability was acceptable for six of the 11 tests in the form described here: three gait tests, two functional lifting tests and a functional muscular endurance test in the right leg. If these tests are to be used as outcome measures, account must be taken of the size of the typical fluctuation in measurements shown. The repeatability figures given may be used as guidelines for interpreting the clinical value of possible changes in test values.

Adult↗
PubMed1999

Effect of furosemide or mannitol before injection of a non-ionic contrast medium on intrarenal oxygen tension.

Oxygen tension (pO2) in rat renal cortex and outer medulla was studied after an intravenous injection of mannitol or furosemide, followed 10 minutes later by an intravenous injection of the non-ionic X-ray contrast medium (CM) iopromide (370 mg iodine/ml). Ten minutes after mannitol injection, before injection of CM, pO2 in the medulla had decreased from a control level of 32 +/- 3 to 28 +/- 4 mm Hg. The addition of CM caused a further decrease, to 24 +/- 5 mm Hg, which was a significant reduction. Ten minutes after furosemide injection the pO2 in the medulla had increased significantly, from a control value of 32 +/- 2 to 44 +/- 4 mm Hg. Injection of CM caused a significant decrease in pO2 to 37 +/- 3 mm. Ringer's solution (n = 6) caused no changes. We conclude that pretreatment with mannitol or furosemide does not prevent the CM-induced decrease in pO2 in the outer medulla.

Animals↗
PubMed1999

Behavioral effects of a comprehensive, multifactorial program for lifestyle change after percutaneous transluminal coronary angioplasty: a prospective, randomized controlled study.

A group of 93 coronary patients recently treated with percutaneous transluminal coronary angioplasty (PTCA) were randomly assigned to either an intervention or a control group. Subjects in the intervention group participated in a comprehensive behaviorally oriented program aimed at achieving significant long-term changes in risk factor-related lifestyle behavior. Assessments of lifestyle behaviors, psychological factors, biological risk factors, and rehabilitation as well as secondary prevention endpoints were carried out, at inclusion and after 12 months. Results showed that the intervention patients, as compared with controls, improved significantly on measures assessing smoking, exercise, and diet habits. These self-rated changes were confirmed by weight reductions and improved exercise capacity, as well as by between-group differences in subclinical chest pain during an exercise test. However, few effects were found on the different psychological variables, as well as on morbidity or return to work.

Adult↗
PubMed1999

Low molecular weight heparin (dalteparin) as adjuvant treatment of thrombolysis in acute myocardial infarction--a pilot study: biochemical markers in acute coronary syndromes (BIOMACS II).

OBJECTIVES: This randomized, double blind, placebo-controlled pilot trial evaluated the effect of dalteparin as an adjuvant to thrombolysis in patients with acute myocardial infarction regarding early reperfusion, recurrent ischemia and patency at 24 h. BACKGROUND: Low-molecular-weight heparin, given subcutaneously twice daily without monitoring, might be an attractive alternative to conventional intravenous heparin in the treatment of acute myocardial infarction. METHODS: In 101 patients dalteparin/placebo 100 IU/kg was given just before streptokinase and a second injection 120 IU/kg after 12 h. Monitoring with continuous vector-ECG was done to obtain signs of early reperfusion and later ischemic episodes. Blood samples for myoglobin were obtained at start and after 90 min to evaluate signs of reperfusion. Coronary angiography was performed after 20-28 h to evaluate TIMI-flow in the infarct-related artery. RESULTS: Dalteparin added to streptokinase tended to provide a higher rate of TIMI grade 3 flow in infarct-related artery compared to placebo, 68% versus 51% (p = 0.10). Dalteparin had no effects on noninvasive signs of early reperfusion. In patients with signs of early reperfusion, there seemed to be a higher rate of TIMI grade 3 flow, 74% versus 46% (myoglobin) (p = 0.04) and 73% versus 52% (vector-ECG) (p = 0.11). Ischemic episodes 6-24 h. after start of treatment were fewer in the dalteparin group, 16% versus 38% (p = 0.04). CONCLUSIONS: When dalteparin was added as an adjuvant to streptokinase and aspirin, there were tendencies for less ECG monitoring evidence of recurrent ischemia and better patency at 24 h, warranting further study.

Adult↗
PubMed1999

Two-year results of a controlled study of residential rehabilitation for patients treated with percutaneous transluminal coronary angioplasty. A randomized study of a multifactorial programme.

AIMS: In a multifactorial lifestyle behaviour programme, of 2 years duration, to study the maintenance of achieved behaviour and risk factor-related changes. METHODS AND RESULTS: Out of a consecutive population of 151 patients treated with percutaneous transluminal angioplasty under 65 years of age, 87 were randomly allocated to an intervention group (n=46) or to a control group (n=41). The programme started with a 4 week residential stay, which was focused on health education and the achievement of behaviour change. During the first year of follow-up, a maintenance programme included regular contacts with a nurse, while no further rehabilitative efforts were offered during the second year. One patient died (control). During the second year the proportion of hospitalized patients was lower in the intervention group (4% vs 20%;P<0.05). Patients in the intervention group improved several lifestyle dependent behaviours: diet (index at 0, 12 and 24 months): 10.5+/-3. 4, 12.9+/-2.5 and 12.4+/-2.6 in the intervention group (I) vs 10. 1+/-3.2, 10.7+/-3.0 and 11.8+/-3.2 in the control group (C);P<0.05, exercise sessions per week: 2.5+/-2.3, 4.5+/-1.9 and 4.4+/-2.1 (I) vs 3.1+/-2.2, 3.5+/-2.3 and 3.7+/-2.7 (C);P<0.05, and smoking; 18%, 6% and 9% (I) vs 12%, 21% and 18% (C);P<0.05. This corresponded to improvement in exercise capacity (0, 12 and 24 months): 156+/-42, 174+/-49 and 165+/-47 W (I) vs 164+/-40, 163+/-49 and 156+/-48 watts (C);P<0.05. There were no significant differences between the two groups with regard to serum cholesterol levels at 0 and 24 months: 5. 4+/-0.8 and 5.2+/-0.9 mmol. l(-1)(I) vs 5.4+/-1.0 and 4.9+/-0.9 mmol. l(-1)(C); ns, low density lipoprotein cholesterol level: 3.6+/-0.8 and 3.4+/-0.8 mmol. l(-1)(I) vs 3.7+/-0.9 and 3.3+/-0.7 mmol. l(-1)(C); ns, triglyceride level: 2.2+/-1.6 and 1.8+/-1.3 mmol. l(-1)(I) vs 2.2+/-1.4 and 1.6+/-0.6 mmol. l(-1)(C); ns, body mass index (0, 12 and 24 months): 27.5+/-4.5, 27.0+/-4.3 and 27.4+/- 4.5 kg. m(-2)(I) vs 26.8+/-2.8, 26.9+/-2.7 and 26.9+/- 3.2 kg. m(-2)(C); ns, waist/hip ratio or blood pressure. The two groups did not differ in quality of life, or psychological factors. Return to work after 12 and 24 months was 74% and 78% (I) vs 68% and 61% (C); ns. CONCLUSION: This rehabilitation programme influenced important lifestyle behaviour and reduced some, but not all, important risk factors

Aged↗
PubMed1999

Multifactorial evaluation of a program for lifestyle behavior change in rehabilitation and secondary prevention of coronary artery disease.

A comprehensive, multifactorial lifestyle behavior change program was developed for rehabilitation and secondary prevention of subjects with coronary artery disease. The purpose of the present report is to describe this intervention model and to analyze results achieved in a first group of consecutive participants. Main inclusion criteria for the 292 subjects were a recent history of acute myocardial infarction, coronary artery bypass surgery, or percutaneous transluminal coronary angioplasty. The program commenced with a 4-week residential stay, with the focus on health education and the achievement of behavior change in major lifestyle areas. During the year of follow-up a systematic maintenance program included regular contact with a nurse. Morbidity and mortality was low. Self-reported quality of life improved and there were significant improvements in blood lipids, exercise capacity and body mass index. There were also significant changes both in psychological variables such as Type A behavior, anger, hostility, and in major lifestyle areas such as stress reactions, diet, exercise and smoking. These changes compared favorably with data from relevant samples from the Swedish normal population. This program had a considerable effect on a number of important factors for rehabilitation and secondary prevention of coronary artery disease.

Analysis of Variance↗
PubMed1999

Impairment and work disability due to whiplash injury following traffic collisions. An analysis of insurance material from the Swedish Road Traffic Injury Commission.

A study was set up to determine the trends in medical impairment and work disability ratings for persons affected by whiplash associated disorders (WAD) and other injuries secondary to road traffic collisions, and into the influence of age, gender, professional status, and final medical impairment rating on final work disability. A cross-sectional study was carried out of insurance files of 2,523 subjects in 1989 and 3,223 subjects in 1994 judged to have a permanent medical impairment of 10% or more and work disability due to road traffic injury. Files were obtained from the Swedish Road Traffic Injury Commission. The main outcome measures were the crude frequency and age-specific, standardized percentage of traffic injuries with a medical impairment of 10% or more for the years 1989 and 1994. Final work disability status was analysed with respect to age, gender, type of injury, degree of medical impairment, and professional status. The proportion of medical impairment due to WAD was found to have increased from 16% in 1989 to 28% in 1994, but the proportion of work disability was found to have remained the same. Age over 40 years, low professional status, and having a medical impairment judgement of 15% or more were independently associated with reduced or full work disability.

Accidents, Traffic↗
PubMed1999

Hypoperfusion in the renal outer medulla after injection of contrast media in rats.

PURPOSE: The effect on regional renal blood was studied after injection of nonionic iso-osmolar iotrolan or ionic high-osmolar iothalamate. MATERIAL AND METHODS: Laser-Doppler flowmetry was used to measure outer medullary (OMBF) and superficial cortical blood flow (CBF) simultaneously in anesthetized rats. Iotrolan (320 mOsm/kg H2O) was injected i.v. at a dose of 600 mg I/kg b.w. (normal dose) over 2 min or 1,600 (high dose) mg I/kg b.w. over 2 or 8 min. Iothalamate (2,580 mOsm/kg H2O) was injected i.v. at a dose of 1,600 (high dose) or 2,900 (extremely high dose) mg I/kg b.w. over 2 min. RESULTS: At the normal dose and 2-min injection of iotrolan, OMBF was reduced by 25+/-9% over 20 min. The high dose of iotrolan injected over 8 min resulted in a reduction in OMBF slightly smaller (17+/-9%) than that induced by the normal dose but lasting longer (30 min). Compared to the normal dose, the high dose and fast (2 min) injection of iotrolan resulted in a greater and more prolonged decrease in OMBF (32+/-6% lasting 50 min). After the high dose of iothalamate (1,600 mg I/kg) there was a decrease in OMBF by 21+/-6%, lasting 30 min. An extremely high dose (2,900 mg I/kg b.w.) gave a heterogeneous response with a mean increase in OMBF of 48+/-24% occurring 60 min after the injection. CONCLUSION: Iso-osmolar and high-osmolar contrast media (CM), at normal and high doses, decrease OMBF, while an extremely high dose of iothalamate may result in an increase. The depression of outer medullary perfusion may have implications for CM-induced acute renal failure in view of the vulnerability of this region to a decrease in oxygen tension.

Animals↗
PubMed1998

The haemodynamic effects of iodinated water soluble radiographic contrast media: a review.

All classes of iodinated water-soluble radiographic contrast media (RCM) are vasoactive with the iso-osmolar dimers inducing the least changes in the vascular tone. The mechanisms responsible for RCM-induced changes in the vascular tone are not fully understood and could be multifactorial. A direct effect on the vascular smooth muscle cells causing alterations in the ion exchanges across the cell membrane is thought to be an important factor in RCM-induced vasodilatation. The release of the endogenous vasoactive mediators adenosine and endothelin may also play a crucial role in the haemodynamic effects of RCM particularly in the kidney. In addition, the effects of RCM on blood rheology can cause a reduction in the blood flow in the microcirculation. The purpose of this review is to discuss the pathophysiology of the haemodynamic effects of RCM and to offer some insight into the biology of the endothelium and vascular smooth muscle cells as well as the pharmacology of the important vasoactive mediators endothelin and adenosine.

Adenosine↗
PubMed1998

Injection of low and iso-osmolar contrast medium decreases oxygen tension in the renal medulla.

The oxygen tension (PO2) in the renal cortex and outer renal medulla in 26 rats was studied by use of oxygen microelectrodes before and after injection of x-ray contrast media (CM). The CM, iopromide, ioxaglate and iotrolan were administrated intravenously in iodine equivalent doses (1,600 mg iodine/kg body wt). Ringer's solution was used as the control. In the outer medulla, all three CM induced a decrease in PO2: iopromide (N = 6) from 30 +/- 3 to 18 +/- 4 mm Hg; ioxaglate (N = 7) from 32 +/- 6 to 15 +/- 4 mm Hg; and iotrolan (N = 6) from 36 +/- 3 to 14 +/- 4 mm Hg. All these decreases were significant. After the injection of Ringer's (N = 7) there was an increase from 34 +/- 3 to 35 +/- 3 mm Hg. In the cortex a slight decrease was noted for injection of CM, but this was significant only after injection of iotrolan. All tested contrast media decrease PO2 in the outer renal medulla, which may partly explain contrast medium-induced acute renal failure.

Acute Kidney Injury↗
PubMed1998

Iodine concentrations in the rat kidney measured by X-ray microanalysis. Comparison of concentrations and viscosities in the proximal tubules and renal pelvis after intravenous injections of contrast media.

PURPOSE: To measure the iodine concentrations in the proximal tubules and renal pelvis after i.v. injections of contrast media (CM) at 1600 mg I/kg b.w., using a micropuncture technique and X-ray microanalysis. MATERIAL AND METHODS: The correlation between the viscosity of each CM and its iodine concentration was evaluated and the viscosity of the fluid in the proximal tubule and renal pelvis was estimated in rats. RESULTS: After iotrolan injection, the iodine concentration in the proximal tubular fluid had increased to values about three times higher than those reached with diatrizoate, iohexol and ioxaglate. Similarly, iotrolan tended to produce a higher iodine concentration in the renal pelvis than did the other CM. The urine viscosity in the renal pelvis was much higher after the iotrolan injection than after the other CM injections. CONCLUSION: High urine viscosity after iotrolan injection can at least partly explain our previous findings of a prolonged increase in tubular hydrostatic pressure and a prolonged decrease in the single nephron glomerular filtration rate after administration of this CM.

Animals↗
PubMed1998

Psychological patterns in patients with coronary heart disease, chronic pain and respiratory disorder.

Patients with coronary heart disease (CHD), chronic pain and respiratory disorder were investigated for different patterns of psychological factors. Several psychological factors were measured: depression (using Beck's 'BDI'), anxiety (using Spielberger's 'STAI'), anger (Spielberger's 'AX'), and cynicism (Greenglass & Julkunen's 'CD'). The special psychological pattern in patients with CHD was characterized by an increase in suppressed anger, overall experienced anger, and cynicism. Patients with chronic pain did not show any comparable pattern of elevated psychological factors. The pattern in patients with respiratory disorder was characterized by increased cynicism and, in women, also clinical depression.

Adult↗