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Biomedical subjects

I Engström

Publications and source records attributed to I Engström.

At least 19 recordsLinked to original sources
PubMed1996

Influence of breathing pattern on transcutaneous oxygen and carbon dioxide tension during histamine provocation in children with bronchial asthma.

The influence of the breathing pattern on transcutaneous blood gases was evaluated in 18 boys and 8 girls 7-18 years of age, with bronchial asthma, during bronchial provocation with histamine-HCl. Transcutaneous oxygen tension (tcPO2), carbon dioxide tension (tcPCO2) and the breathing pattern assessed by the transthoracic impedance technique were continuously monitored during the provocation. At reaction, when the fall in the forced expiratory volume in 1 s (FEV1) was 20% or more, the tcPO2 fell by 15% or more below the baseline in 22/26 and by 20% or more in 14/26 children. In some children, a marked fall in the tcPO2 was already noted after the saline inhalation and the first histamine dose steps without simultaneous changes in the FEV1. This early fall in the tcPO2 correlated to changes in the breathing pattern and was interpreted as a sign of compensatory hypoventilation secondary to the hyperventilation observed during the inhalations. We conclude that transcutaneous oxygen tension can be used as an indicator of a bronchial reaction during bronchial provocation tests in children only if one takes account of the fact that the breathing pattern during the inhalation of the challenge compound per se has an effect on the oxygen tension.

Administration, Inhalation↗
PubMed1996

Activation of AMP deaminase in human erythrocytes by calcium ions.

We examined 5'-AMP aminohydrolase (AMP deaminase, EC 3.5.4.6. AMPD) together with metabolite changes in intact red blood cells from normal human adults under different incubation conditions. Moderate changes occurred in erythrocyte adenylates upon incubation for 1 h at 37 degrees C in the absence of glucose and the concentration of IMP was negligible. Calcium in the incubation medium, at concentrations up to 1.50 mmol l-1 did not influence the nucleotide pattern. Inclusion of the ionophore A 23187 in the incubation medium resulted in a sharp decrease of ATP content at 60 min and increases in AMP and ADP concentrations. A maximally low level of ATP was observed at 60 min of incubation in the presence of both the ionophore and 0.25 mmol l-1 of external calcium. With increasing concentrations of calcium up to 1.50 mmol l-1 in the presence of the ionophore, a significant rise occurred in both IMP and ATP concentrations, whether glucose was present or not, and significant correlations existed between the concentrations of calcium and IMP. The presence of the ionophore together with glucose but without extra calcium in the incubation medium produced the highest concentrations of lactate, indicative of an enhanced glycolytic flux under these conditions. The stimulatory effect of intracellular calcium ions on AMPD activity is discussed.

AMP Deaminase↗
PubMed1995

Alzheimer amyloid beta-peptides exhibit ionophore-like properties in human erythrocytes.

There is growing evidence that the amyloid beta-peptide (beta 1-40) is involved in the aetiology of Alzheimer's disease also implicating an altered calcium homeostasis of affected cells. Beta 1-40 has been proposed to form calcium channels in synthetic bilayer membranes [1]. We wanted to investigate in the present study whether beta 1-40 (or fragments thereof) could act as ionophores in a biological membrane like the one in human erythrocytes. Incubation of the cells for 2 h and 4 h at 37 degrees C together with 6 mumol L-1 of beta 1-40 or of fragments beta 1-28 and beta 25-35, resulted in a significantly decreased energy charge qualitatively similar to the one obtained by a known calcium ionophore (A 23187, 0.05 mumol L-1). Moreover, beta 1-40 and its two fragments induced a significant alteration of 45Ca permeability in human red blood cells of the same type as the one achieved by the calcium ionophore. The ionophoric action of beta 1-40 and its two fragments may lead to an increase of the intracellular calcium ion concentration, in turn resulting in enhanced Ca(2+)-ATPase activity and a decrease in energy charge. This may be valid also for neuronal plasma membranes and could, therefore, be a possible aetiological mechanism in Alzheimer's disease.

Adenosine Diphosphate↗
PubMed1993

Dissipation of the calcium gradient in human erythrocytes results in increased heat production.

Heat production rates were measured by a microcalorimetric method in suspended human erythrocytes in the absence and presence of different concentrations of the divalent cationophore A23187. Determinations were carried out during 60 min under static conditions on erythrocytes incubated in various isotonic media at 37 degrees C, pH 7.35. In incubations containing the ionophore, time-power curves showed an early peak followed by a descending slope levelling off at a steady state after 30-60 min. In contrast, the controls lacked the early peak, showing hyperbolic ascending curve profiles before reaching steady state. The appearance of the early peak in the presence of ionophore was dependent upon the composition of the medium, both Mg2+ ions and glucose being decisive. Likewise, dose-response relationships concerning heat production at 60 min depended on the composition of the media. In a basic incubation medium lacking Mg2+ and glucose, no effect was seen on heat production by the ionophore (1-3 mumol/l). Rather modest effects were obtained by the ionophore at 2 and 3 mumol/l when Mg2+ was present. A clear-cut dose-response relationship was observed in a Mg2+ and glucose enriched medium for the ionophore from 1-3 mumol/l. The significant increase in heat production observed at 60 min with 2 mumol/l of A23187 in the Mg2+ and glucose enriched medium was abolished by 1 mmol/l EGTA. Calmidazolium, a calmodulin antagonist, could only marginally reduce the ionophoric effect on heat production. It was concluded that the appearance of the early peak was not the result of an increase in glycolytic rate but rather a consequence of the ionophoric action on the Ca2+ gradient.

Adenosine Triphosphate↗
PubMed1993

Respiratory resistance and transcutaneous PO2 during histamine provocation in children with bronchial asthma.

Bronchial reactivity was assessed in 66 children with bronchial asthma (aged 8-15 years) by provocation with histamine-HCl during a symptom-free period. A significant bronchial reaction to histamine was defined as a 50% increase in the resistance of the respiratory system (Rrs) determined by the forced oscillation technique. The provocative dose causing a 50% increase in the Rrs (PD50Rrs) was interpolated from the log dose-response curve. The mean PD50Rrs was significantly lower in children with asthma (0.22 mg/mL) compared with a group of healthy children in the same age range (1.55 mg/mL) (P < 0.001). In children with clinically severe asthma, the mean PD50Rrs was lower (0.13 mg/mL) than in children with mild asthma (0.34 mg/mL) (P < 0.001). Transcutaneous PO2 (PtcO2) was monitored in 25 of the children with asthma. In this group the proportion of mild and severe asthma, the baseline lung function variables, and the PD50Rrs were not significantly different from those of the whole group of children. During the reaction, the PtcO2 fell on average by 29% of the baseline value (P < 0.001); in 88% of the children, the fall in PtcO2 was 20% or more of the baseline value. We conclude that histamine provocation tests using the forced oscillation technique and transcutaneous PO2 to assess a bronchial reaction have a good discriminatory capacity for different degrees of clinical severity of asthma in children.

Adolescent↗
PubMed1993

Ionophore A23187 reduces energy charge by enhanced ion pumping in suspended human erythrocytes.

Washed human erythrocytes were basically incubated in phosphate-buffered saline at 37 degrees C with different concentrations (1-5 mumol l-1) of the divalent cationophore A23187. This ionophore induced a decrease by about 75% of ATP content and energy charge (EC) and a concomitant increase in ADP and AMP contents in a dose-dependent fashion such that an inverse ATP/ADP relationship developed. EGTA at 1 mumol l-1 annihilated the effect of A23187 on energy status. When glucose was added to the basic incubation medium A23187 inclusion resulted in an elevated lactate production concomitantly with a partial restoration of EC. Introduction of Mg2+ to basic incubation medium containing glucose and the ionophore resulted in a sharp increase in lactate production with an energy state that was maintained at a control level. It is concluded that the low EC of erythrocytes obtained by this ionophore is the result of runaway ATPases dissociated from glycolysis. Since human erythrocytes are devoid of organelles other than the plasma membrane it is concluded that the ionophoric effect is exerted in the plasma membrane.

Adenosine Diphosphate↗
PubMed1993

Effects of the ionophore gramicidin D on energy metabolism in human erythrocytes.

Washed human erythrocytes were incubated in phosphate-buffered saline at 37 degrees C with different concentrations (2-80 mg l-1) of the monovalent cationophore gramicidin D. The ionophore induced a decrease of ATP content and energy charge (EC) and a concomitant increase in ADP and AMP contents. At a concentration of 10 mg l-1 of the ionophore the reduction of EC and ATP concentration was about 50%. Increasing the concentration of the ionophore resulted in a substantial haemolysis with no further effect on the nucleotide levels. Lowering the concentration of the ionophore to 5 mg l-1 (to avoid haemolysis) lead to a similar effect on the energy status. Ouabain at 0.5 mmol l-1 in incubation medium distinctly blunted the ionophoric effect on EC and adenine nucleotides. Addition of glucose on the contrary reversed these effects by about 80%. Hence, the glucose-induced increase in glycolytic flux as evidenced by an increase in lactate production was not sufficient to restore energy state.

Adenosine Diphosphate↗
PubMed1992

Transcutaneous blood gas monitoring during salbutamol inhalations in young children with acute asthmatic symptoms.

The effect of salbutamol inhalations on transcutaneous blood gases was investigated in 23 children (aged 11 months-2.5 years) with asthmatic symptoms. After one salbutamol inhalation there was a mean increase in transcutaneous PO2 (tcPO2) of 0.5 kPa (P less than 0.01); after a second dose given 30 minutes later, the mean increase was 1.2 kPa (P less than 0.001). The increase in tcPO2 after only one dose of salbutamol was significantly correlated to age (P less than 0.01). No such correlation was observed after a second dose. The overall increase in tcPO2 after two salbutamol inhalations showed a negative correlation to the duration of the current symptomatic period (P less than 0.05). We conclude that salbutamol inhalations have beneficial effects in young children with acute asthmatic symptoms, even below the age of 18 months, provided that an adequate dose reaches the lung and preferably at an early stage of obstruction.

Acute Disease↗
PubMed1992

Mental health and psychological functioning in children and adolescents with inflammatory bowel disease: a comparison with children having other chronic illnesses and with healthy children.

Psychiatric disorders and behaviour problems were found to be commoner in children and adolescents with inflammatory bowel disease (IBD) than in matched comparison groups with tension headache and diabetes as well as in healthy children. Depression, anxiety and low self-esteem were common. Many children denied their problems. This may be due to the type of illness, its social consequences and the embarrassment experienced by the children. Discrepancies were found between the children's and their mothers' replies. These results are discussed in terms of their implication for paediatric practice.

Adolescent↗
PubMed1992

Characteristics and prognosis of hospital-treated obstructive bronchitis in children aged less than two years.

In a prospective study 101 children aged less than 2 years (median age 10 months), were examined the first time they were admitted to a paediatric ward for asthmatic symptoms. Two-thirds were boys and 58 had parents or siblings with allergic symptoms. During winter-spring, respiratory syncytial (RS) virus was verified in 50% of children. Other viral agents were adenovirus, parainfluenza 3, coxsackie B 2, ECHO 6 and rotavirus. At the acute stage, 54% of the children displayed changes on pulmonary X-ray. The total IgE value was greater than or equal to +2 SD score units in 14 children. At reinvestigation after 3-4.5 years, when the children were aged 3.3-6.3 years, 53% were free from asthmatic symptoms; the median age for the last episode was 2 years. A total of 33% had mild asthma, 8% moderate and 6% severe asthma. The factors which correlated significantly with persistent asthma were: (1) The need for daily medication for at least 6 months. (2) A young age in conjunction with the first wheezing episode and on the first admission to a paediatric ward because of asthmatic symptoms. (3) Other past or present atopic symptoms. Heredity, tobacco smoking at home, having a furry pet, RS virus infection, or high total IgE at the time of the first admission did not correlate significantly with the persistence of asthma 3-4.5 years later. The results emphasize the good overall prognosis of wheezing in early childhood, even when the wheezing is severe enough to lead to inpatient treatment.

Age Factors↗
PubMed1992

Elimination diet in young children with atopic dermatitis.

Thirteen children with severe current atopic dermatitis unresponsive to topical treatment were started on an elimination diet. One child was excluded because she could only keep to the diet for 3 days. Twelve children aged 0.8-4.1 years maintained the diet for 2-4 weeks. In six children the dermatologist's score showed a clear improvement while on diet, in 2 children there was a minor improvement and in 4 children the dermatologist's score did not change during elimination diet. Challenges were performed with egg, milk and wheat in 6 children and with milk and wheat in 2 children. The challenges were done in an open way except for the dermatologist, who was unaware of which food the child had received. No child in the study had an immediate reaction but 3 children had late reactions, one after egg, one after milk and one child after challenge with wheat.

Animals↗
PubMed1991

Parental distress and social interaction in families with children with inflammatory bowel disease.

Twenty families who had children with inflammatory bowel disease (IBD) and 20 comparison families with healthy children were studied concerning parental distress and social interaction. The mothers in the IBD group scored very high on parental distress, whereas the fathers did not differ from the comparison group. Both parents in the IBD group reported significantly lower scores on a social support scale. The dimension of social integration was normal, but deeper relations and attachment were negatively affected among parents in the IBD group. The mental health of the children with IBD correlated with the social support, especially the qualitative aspects.

Adaptation, Psychological↗
PubMed1991

Family interaction and locus of control in children and adolescents with inflammatory bowel disease.

This study showed that children and adolescents with inflammatory bowel disease (IBD) had a more external locus of control than did matched diabetic and healthy children. An external locus of control correlated with severity of physical illness and presence of psychiatric disorders. It also correlated significantly with family dysfunction, which was found to be more common in the IBD group than in the groups compared. Tendencies toward a tense and negative family climate were observed in the IBD families. Awareness of the interaction between physical and psychosocial factors in IBD is essential in the management of therapy.

Adolescent↗
PubMed1991

Psychological and respiratory physiological effects of a physical exercise programme on boys with severe asthma.

Ten boys 9-12 years of age with severe perennial asthma participated in a physical exercise programme lasting 8 months. Pulmonary function and psychological tests were performed before training, immediately after, and one year after the end of the exercise programme. Static lung volumes, flow-volume variables and histamine tolerance were used as indicators of pulmonary function. Ego structure, body image, social development and concentration capacity were used as indicators of personality development. Before the study, the group had high FRC (p less than 0.05) and RV (p less than 0.001), low FEV1, MEF50 and MEF25 (all p less than 0.001) and low histamine tolerance. They showed marked disturbances in their personality development with low scores in psychological variables. During the training period, MEF50 and MEF25 increased slightly (p less than 0.01). Marked improvement was observed in all psychological variables (p less than 0.001). The positive effects remained during the following year. The marked and lasting improvement in personality development was regarded as an essential factor behind the more modest positive clinical and pulmonary function changes. The results emphasize the importance of including exercise programmes in the treatment of children with asthma.

Asthma↗
PubMed1990

Long-term treatment with glucocorticoids/ACTH in asthmatic children. III. Effects on growth and adult height.

The effect on growth of long-term treatment with prednisolone and/or ACTH (tetracosactrin) depot preparation was studied in 40 children with severe bronchial asthma. Height velocity was subnormal before treatment. During treatment the group of 17 children primarily treated with ACTH showed a moderate increase in mean velocity. Their height was not significantly altered, and neither was the age at peak height velocity nor adult height. In the group of 23 children treated with prednisolone the mean velocity decreased, resulting in a relative decrease in height. Peak height velocity was delayed by about 2 years in the boys but occurred at the expected time in the girls, as did menarche. Mean adult height was lower than expected after adjustment for mid-parenteral height. In 10 children ACTH was substituted for prednisolone, and their height velocity increased but not enough to affect adult height, which was just as low as in the patients treated with prednisolone only.

Adrenocorticotropic Hormone↗
PubMed1990

Natural history of allergic diseases in children.

Questionnaire data from 1335 14-year-old children with a history of past or present asthma, allergic rhinitis or eczema were analysed regarding age at onset and cessation of symptoms. Incidence of asthma and eczema was highest during the first years of life. Early incidence of asthma was higher in boys than in girls but the sex ratio equalized gradually during childhood. Early incidence of eczema was equal between the sexes but the proportion of girls increased gradually with later age at onset. In 24% of the children more than one symptom was found. Cessation of symptoms was common in asthma (55%), in particular in those with early onset (74%), but less common in eczema (34%). Cessation of symptoms was less common in both diseases when associated with other allergic symptoms. Incidence of allergic rhinitis was fairly constant during childhood and cessation of symptoms was uncommon. A high risk of allergic airways disease was found after early eczema.

Adolescent↗