PubMed Health⌕ Search

Biomedical subjects

L Bäcklund

Publications and source records attributed to L Bäcklund.

At least 19 recordsLinked to original sources
PubMed1999

Exercise-induced bronchoconstriction in adults with asthma--comparison between running and cycling and between cycling at different air conditions.

The bronchial response to cycling and running was compared in six adult asthmatic persons. The effects of different air conditions during cycling regarding the induction of bronchoconstriction was studied. The exercise consisted of 6 minutes' work at an intensity of 80-85% of maximal heart rate. Heart rate, oxygen consumption and ventilation were measured to check that the exercise level was the same in all tests. Peak expiratory flow (PEF) was used to test for bronchoconstriction. Bicycling and treadmill running were performed under indoor conditions and bicycling while breathing cold, dry air (-18 degrees C) and room-tempered humid air (60% RH), respectively. No difference in bronchoconstriction was found between cycling and running under indoor conditions. However, bicycling exercise with inhalation of cold dry air provoked more bronchoconstriction than when inhalating humid air (PEF reductions of 19.4+/-6% and 6.1+/-2%, respectively). No differences were found between the exercise modes in heart rate, oxygen consumption, ventilation per minute, respiratory rate, carbon dioxide elimination or subjective ratings of perceived exertion and breathlessness. It is concluded that it is not the type of exercise, but the ventilation demand and humidity of the inspired air that are the main determinants of the occurrence and degree of bronchoconstriction.

Adult↗
PubMed1994

Subclinical disturbances in cardiac function at rest and in gas exchange during exercise are common findings after autologous bone marrow transplantation.

A study was undertaken to examine the effects of autologous bone marrow transplantation (BMT) on cardiac function at rest (n = 111) and pulmonary gas exchange during exercise (n = 110). Left ventricular cardiac ejection fraction (LVEF) was measured by radionuclide ventriculography before autologous BMT and after 6 months and 1, 3 and 5 years. Expired gas volume per oxygen consumption (VE/VO2) and transcutaneous PO2 were measured at rest and during submaximal exercise before and 6 and 12 months after autologous BMT, and the alveolar-arterial oxygen difference was calculated after 12 months. In lymphoma patients conditioned with BCNU, cyclophosphamide, etoposide and cytarabine, a long-lasting reduction in LVEF of 11 +/- 14% mean (+/- SD) was noted. The risk of cardiac deterioration was not increased by a subnormal LVEF before autologous BMT or total body irradiation (TBI). Impaired gas exchange during exercise was a common feature, but severe disturbances were uncommon. During exercise transcutaneous PO2 fell pathologically in 15% and 20% of the patients examined after 6 and 12 months, respectively, and the alveolar-arterial oxygen difference increased pathologically in 50% after 12 months. The VE/VO2 ratio increased significantly during exercise 6 months after autologous BMT in TBI-treated patients.

Adolescent↗
PubMed1994

Pulmonary function and complications subsequent to autologous bone marrow transplantation.

Risk factors for early pulmonary complications occurring within the first 3 months after autologous bone marrow transplantation (BMT) were analysed in 158 consecutive adults. The long-term effects of autologous BMT on pulmonary function were analysed in 102 patients, who had survived free of disease for > 6 months after autologous BMT. Pulmonary function tests were performed before, at 6 and 12 months after autologous BMT and thereafter annually. The median follow-up was 12 (6-60) months. The incidence of early pulmonary complications was 16% (26 of 158). Idiopathic interstitial pneumonitis was seen in 11% of patients treated with total body irradiation (TBI). Single dose TBI was the major risk factor as regards early pulmonary complications but restrictive pulmonary disturbances and impaired diffusing capacity prior to autologous BMT were also significant risk factors. In both non-TBI and TBI-treated patients a mild restrictive ventilatory dysfunction and impaired diffusing capacity was noted 6 months after autologous BMT. In non-TBI-treated patients, these disturbances had resolved completely within 2 years whereas the lung volumes of TBI-treated patients were persistently reduced by 10% of their pre-autologous BMT values during follow-up. However, dysfunctions rarely progressed 6 months after autologous BMT. In most patients, ventilatory dysfunction was slight and had no clinical significance.

Adolescent↗
PubMed1991

Renal function after autologous bone marrow transplantation.

Seventy-two out of 102 consecutive patients autografted for various hematologic and lymphoid malignancies had a relapse-free survival of greater than 6 months after autologous bone marrow transplantation (ABMT) and were evaluated for long-term effect of the treatment on the renal function. The myeloablative therapy included total body irradiation (TBI) in a single fraction of 7.5 Gy in 41/72 patients. Mean glomerular filtration rate (GFR) showed a significant decrease (p less than 0.01) and serum creatinine and serum urea an increase (p less than 0.05) 6 months after ABMT. Twelve of 72 patients (17%) developed renal dysfunction defined as greater than 25% decrease in GFR, in most cases accompanied by hematuria and proteinuria. Onset was 3-6 months after ABMT. Some patients have later improved considerably, but others continue to deteriorate in renal function. The single most important risk factor for renal dysfunction after ABMT was irradiation. Renal damage was most frequent in lymphoma patients conditioned with BEAC (carmustine [BCNU], etoposide, cytarabine, cyclophosphamide) followed by irradiation, suggesting that this drug combination might have potentiated the toxicity of irradiation. Nephrotoxic antibiotics probably contributed to renal damage in individual cases. Young age did not appear to be a risk factor. Our data indicate that combined treatment with BEAC and TBI should be used with caution and that renal function should be monitored in all patients after bone marrow transplantation to detect any new toxicity patterns of the various conditioning regimens currently used.

Adolescent↗
PubMed1990

Blood flow and pulse amplitude in the mucosa of the human maxillary sinus in relation to body posture.

The paranasal sinuses are non-collapsible ventilated gas pockets without any known function. They should, however, be adequately ventilated to stay healthy. Persons lying in a recumbent body position compared to persons sitting or standing upright have reduced antral mucosal blood flow, a reduction of 35%, and a congested mucosa which reduces both the mucosal gas exchange and the perostial ventilation, creating a more anaerobic antral gas mixture facilitating pathogenic bacterial growth and reduced ciliary activity. It is, therefore, recommendable for patients with sinusitis to treat themselves or be treated in an upright or semi-recumbent body position.

Adult↗
PubMed1989

The relationship between body posture and pressure in occluded maxillary sinus of man.

One of the most common symptoms in sinusitis is pain over the infected cavity increasing when the patient is bending forward or lying down. It is commonly thought that this increase in pain is a result of increased pressure in the paranasal cavities when bending forward. In this investigation we have found that changing the body position from sitting to recumbent or even to "head between knees" gives a manometrical pressure rise in the sinus that is too small to cause a pressure-mediated pain. The pain is probably caused by a dilation in the blood vessels of the infected mucosa when the patient is bending forward or lying down.

Adult↗
PubMed1989

The effect of physical work on the mucosal blood flow and gas exchange in the human maxillary sinus.

The paranasal sinuses are lined with respiratory mucosa of principally the same structure as in the nasal mucosa but somewhat thinner. This mucosa has a rich blood flow and advanced system of blood vessels regulated mostly by the autonomous nervous system but also by other factors as acid/base balance and endocrine activity. The thickness of the nasal mucosa regulates the nasal breathing resistance and varies with among other factors, body activity. In this investigation we have studied the effect of physical work on the human maxillary sinus mucosa. The investigation shows that, as in the nose, the blood flow and the pulse amplitude are considerably reduced during physical work, in situations of heavy work falling to about half of the normal level, and probably result in the redistribution of blood from the respiratory mucosa. The gas exchange in the paranasal sinus is reduced only to a small extent, the reduction being too small to change the antral gas composition towards pathological conditions.

Adult↗
PubMed1983

Inulin single injection clearance. Microsample technique useful in children for determination of glomerular filtration rate.

The agreement between single injection inulin (polyfructosan) clearance and two reference methods for glomerular filtration rate (GFR) determination, namely standard inulin constant infusion clearance and 51-Cr-EDTA single injection clearance, was investigated. Studies were also made to see whether different results were obtained when capillary and venous blood samples were used in the single injection clearance method. The investigation was made in children from one year of age, adult patients and volunteers. For the single injection technique with inulin or 51-Cr-EDTA, five to seven blood samples were taken in a period of up to 180 min after injection. A bi-exponential plasma disappearance curve was used for calculations of single injection clearances. Good agreement was obtained between venous inulin single injection clearance on the one hand, and standard inulin clearance (correlation coefficient r = 0.86) and 51-Cr-EDTA single injection clearance on the other (r = 0.85). With use of capillary blood samples in inulin single injection clearance, similar good agreement was obtained both with venous 51-Cr-EDTA and with venous inulin single injection clearance (r = 0.85 and r = 0.89 respectively). From these results we conclude that inulin single injection clearance is a reliable method for GFR determinations. This method is recommended, especially in children, as capillary blood samples can be used.

Adolescent↗
PubMed1983

Evaluation of glomerular filtration rate in infants.

In the present study we investigated if inulin with single injection technique and capillary blood sampling can be used to determine glomerular filtration rate. Inulin single injection clearances using both venous and capillary samples were compared to standard inulin clearance (constant infusion) and to the clinical routine method, i.e. 51Cr-EDTA clearance. Good agreement was obtained between these different methods and it is concluded that the inulin single injection clearance is a reliable method for GFR estimation. Especially in children this method is recommended as capillary blood samples can be used and thus the high doses of radioactivity necessary for a 51Cr-EDTA capillary method can be avoided.

Adolescent↗
PubMed1980

Heart volumes and measures of the circulatory capacity in young and middle-aged men and women.

An acceptable method and equations for predicting the total heart volume from correlations to physiologic variables in young and middle-aged healthy persons are presented. Body weight gives more predictive information than body surface area. The use of the total hemoglobin mass and measures of physical work capacity as variables in addition to body weight will only increase the accuracy of the prediction relatively slightly.

Adult↗
PubMed1976

Renal function in experimental chronic hydronephrosis. V. Net acid excretion capacity in relation to renal pelvic volume after maximal loading with NH4Cl.

In 12 mongrel dogs intravenous loading with ammonium chloride (4 mmol NH4+/kg body weight) was performed before and 2-9 weeks after unilateral hydronephrosis had been produced by ligation of the ureter over an indwelling catheter. In an attempt to satisfy the demand for adequate, constant, alveolar ventilation a special respirator of the high-frequency positive-pressure ventilation (HFPPV) type was used. The acid-base status of the blood was determined before and after the loading and the acidification capacity of each kidney was assessed by measuring the amount of titratable acid and ammonium ions excreted in the urine. In the hydronephrotic kidney the excretion of both titratable acid and ammonium ions was statistically significantly reduced, both compared with the initial values in session I and compared with the healthy kidney in session II. After additional loading with ammonium chloride in session II, however, both kidneys increased their excretions to approximately similar extents. When the excretion was calculated per ml glomerular filtrate, no statistically significant changes were found between sessions I and II, either for the intact or the hydronephrotic kidney. The renal pelvic volume on the hydronephrotic side was measured and related to the reduction of the capacity of the kidney to excrete titratable acid and ammonium ions. No statistically significant correlation was obtained.

Acid-Base Equilibrium↗
PubMed1975

Renal function in experimental chronic hydronephrosis. I. Backflow studies with dextran.

By ligation of the ureter, causing partial ureteral stenosis, unilateral hydronephrosis was induced in 10 dogs. Renal function studies including creatine clearance and osmolality determination were performed both before and after the ureteral ligation. The renal function analysis after induction of hydronephrosis included pyelovenous and pyelolymphatic reflux studies, with deposition of dextran in the renal pelvis at different intrapelvic pressures. Analysis with respect to sodium, potassium, chloride and dextran in the thoracic duct lymph, peripheral blood and urine from the intact kidney were performed. The results show a reduction of the renal function in hydronephrosis, little transport of dextran via the lymph and blood, and no significant increase in the lymphatic transport of the studied ions on elevation of the intrapelvic pressure.

Animals↗
PubMed1975

Renal function in experimental chronic hydronephrosis. II. Backflow studies with radionuclides.

Studies of backflow in experimental unilateral chronic hydronephrosis in dogs with a known residual renal function and renal pelvic volume were performed with radioactively labelled substances with molecular weights of ca. 600, 5 200 and 68 000 placed in the hydronephrotic renal pelvis. Three different pressure levels in the renal pelvis were used. Isotope concentrations were determined in the thoracic duct lymph, 0lood and urine from the contralateral kidney. The greater part of the test substances appeared to pass to the blood circulation, while a smaller part was found in the lymphatic ducts. The largest molecule, however, was only able to leave the renal pelvis to any appreciable extent at the highest pressure. In kidneys with a low grade of hydronephrosis and well preserved function, a relatively large amount of test substance left the renal pelvis (ca. 10-15%). In more advanced grades of hydronephrosis with greater impairment of renal function, the backflow was considerably less.

Animals↗