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Biomedical subjects

S Ahola

Publications and source records attributed to S Ahola.

6 recordsLinked to original sources
PubMed2006

Multiecho sequence for velocity imaging in inhomogeneous rf fields.

The unambiguous determination of velocities with spatial resolution in a multiecho PFG NMR sequence strongly depends on the homogeneity of the B1 field. This affects, in particular, the use of surface coils that bear considerable potential for on-line flow monitoring where a fast-imaging sequence can become vital. However, even with most rf coils dedicated for imaging applications, B1 inhomogeneities are sufficiently large to generate severe problems in performing velocity-imaging experiments. In this paper, the use of a combination of different phase cycles in Carr-Purcell sequences is discussed. The suggested phase cycling scheme tolerates large flip angle imperfections arising in inhomogeneous B1 fields, and thus allows acquisition of a maximum number of echoes within a pulse train. The performance of the velocity-imaging sequence is proven by using phantom samples developing known laminar flow patterns.

Journal Article↗
PubMed2002

Positive experiences and the relationship between stress and asthma in children.

UNLABELLED: Ninety children aged 6 to 13 y and suffering from chronic asthma were included in a prospective follow-up study lasting 18 mo in order to assess whether life events involving substantial positive effects on the child can protect against the increased risk associated with stressful life events. The main outcome measures included positive life events, positive long-term experiences, severely negative life events, chronic psychosocial stress and new asthma exacerbation. The results showed that, provided they occurred in close proximity to severely negative life events, positive life events, generally related to the child's own achievements, afforded protection against the increased risk of a new asthma exacerbation precipitated by severe events in children whose lives were marked by low to medium levels of chronic stress. No such effect was found in children exposed to high chronic stress nor did long-term positive experiences, such as when the child has a rewarding hobby, affect the asthma risk. CONCLUSION: Life events with a definite positive effect can counteract the increased risk of an asthma exacerbation precipitated by a severely negative life event, provided the chronic stress is only of low to medium level. Because this protective influence does not apply where there is high chronic stress, reducing this condition must be seen as a priority in children suffering from asthma, as these children are also more vulnerable to negative life events precipitating asthma exacerbation.

Adolescent↗
PubMed2000

The role of acute and chronic stress in asthma attacks in children.

BACKGROUND: High levels of stress have been shown to predict the onset of asthma in children genetically at risk, and to correlate with higher asthma morbidity. Our study set out to examine whether stressful experiences actually provoke new exacerbations in children who already have asthma. METHODS: A group of child patients with verified chronic asthma were prospectively followed up for 18 months. We used continuous monitoring of asthma by the use of diaries and daily peak-flow values, accompanied by repeated interview assessments of life events and long-term psychosocial experiences. The key measures included asthma exacerbations, severely negative life events, and chronic stressors. FINDINGS: Severe events, both on their own and in conjunction with high chronic stress, significantly increased the risk of new asthma attacks. The effect of severe events without accompanying chronic stress involved a small delay; they had no effect within the first 2 weeks, but significantly increased the risk in the subsequent 4 weeks (odds ratio 1.71 [95% CI 1.04-2.82], p < or = 0.05 for weeks 2-4 and 2.17 [1.32-3.57], p < or = 0.01 for weeks 4-6). When severe events occurred against the backdrop of high chronic stress, the risk increased sharply and almost immediately within the first fortnight (2.98 [1.20-7.38], p < or = 0.05). The overall attack frequency was affected by several factors, some related to asthma and some to child characteristics. Female sex, higher baseline illness severity, three or more attacks within 6 months, autumn to winter season, and parental smoking were all related to increased risk of new exacerbations; social class and chronic stress were not. INTERPRETATION: Severely negative life events increase the risk of children's asthma attacks over the coming few weeks. This risk is magnified and brought forward in time if the child's life situation is also characterised by multiple chronic stressors.

Acute Disease↗
PubMed1984

Acute fatty liver of pregnancy. Survival with early cesarean section.

We have cared for two women with acute fatty liver of pregnancy in the past two years. Both patients survived as did three of babies. This compares with published mortality rates of up to 85% with this condition. Both patients presented with symptoms and signs of impending liver failure during the third trimester of pregnancy. Both patients were jaundiced, had elevated aminotransferases, leukocytosis, hepatic encephalopathy, and disseminated intravascular coagulation. The diagnosis was confirmed by liver biopsy in both. We attribute the unusually good outcome of these women and their children to early recognition of their disorder and prompt delivery once the diagnosis was considered.

Acute Disease↗