Biomedical subjects

H Hákonarson

Publications and source records attributed to H Hákonarson.

3 recordsLinked to original sources

PubMed2001

[A mutation detection in a transcription factor for adipocyte development in children with severe obesity.].

OBJECTIVE: A substantial proportion of human obesity may be explained by genetic variability. Researchers have tried to identify the important genes in obesity with little sucsess. PPARg2 (peroxisome proliferator activated receptor g 2) is a transcription factor of the nuclear hormone receptor superfamily. It plays a key role in the developement and differentiation of adipocytes. Recently the mutation Pro115Gln in the PPARg2 gene was identified and shown to have a significant correlation with severe obesity. The actual prevalence and distribution of this mutation is not known. The aim of this study was to look for this mutation among Icelandic children suffering from severe obesity. MATERIAL AND METHODS: Thirty-five children and adolescents, aged 4-18, who have been diagnosed with severe obesity participated in the study. Eight parents and siblings aged 19-41 also participated. All study subjects had been obese since early childhood. Body mass index (BMI) was used to describe the phenotype of the subjects. The participants had a BMI of 28.0 to 52.2 kg/m(2). Genomic DNA was extracted from leucocytes. A 131 bp segment was amplified using polymerase chain reaction. The amplified product was digested with the restriction enzyme Hinc II, resolved on agarose gel and visualized under ultraviolet illumination after staining with ethidium bromide. To examine other mutations on the same 131 bp segment enzymatic mutation detection (EMD) was used. Finally the segments giving variable results using EMD were sequenced using the classic Sanger s method. RESULTS: The mutation Pro115Gln was not found in any of the specimens after analysis of the restriction fragment length polymorphism. The results of EMD indicated mutations or polymorphisms in three of the subjects but DNA sequencing failed to confirm these results. CONCLUSIONS: The mutation Pro115Gln or other genetic alternations within the exon examined do not appear to have a significant role in severe early - onset obesity in Icelandic children.

English Abstract↗

PubMed2001

[Common causes of sleep disturbances in Icelandic children who undergo sleep studies.].

INTRODUCTION: Sleep disturbances are common problems in children. Frequently, these problems are attributed to learned behavioral patterns, but little is known about organic causes of sleep disturbances in children. Obstructive sleep apnea (OSA) is a common cause of sleep disordered breathing in adults. Gastroesophageal reflux (GER) is also common in this population. Less is known about OSA and GER as potential causative agents of sleep disturbances in children, and these medical problems have not been addressed in Icelandic children. This study was designed to investigate the organic causes of sleep disordered breathing in Icelandic children, evaluate their severity and possible therapies. MATERIAL AND METHODS: One hundred and ninty children who were referred to the Pediatric Department at Reykjavik Hospital due to sleep disturbances were hospitalized over night and a sleep study was recorded, using the sleep equipment, EMBLA. The latter machine has 16 channels that record informations about sleep patterns and breathing. The children were 0-18 years of age. Informations were collected from EEGs, EMGs, and eye movements to determine sleep stages, and with respiratory belts with sensors on the chest and abdomen as well as an air-flow sensor that measures airflow through the nose and mouth. When GER was suspected, a pH meter was inserted and the pH values were measured in the upper and lower parts of the esophagus. RESULTS: The results demonstrate that a large number of children who suffer from sleep disturbances have an underlying disease. Of 61 children who underwent a sleep study and were suspected to have OSA, 46 had a positive study that resulted in a change in therapy. In addition, 69 of 89 children who underwent pH measurements in the esophagus were diagnosed with GER which prompted changes in therapy. CONCLUSIONS: The study demonstrates that both OSA and GER are common problems in children with sleep disturbances. We conclude that sleep studies are important in the overall workup of children with sleep disturbances, and can provide valuable informations regarding the causes, prevalence and severity of these medical problems. Sleep studies also facilitate the selection of children who require specific treatments such as operation of the oropharynx or CPAP/BiPAP treatment for OSA, or drug therapy for GER.

English Abstract↗

PubMed1995

Pulmonary function abnormalities in Prader-Willi syndrome.

OBJECTIVE: To determine whether individuals with Prader-Willi syndrome (PWS) have abnormalities in pulmonary function as a result of thoracic muscle weakness. DESIGN: Testing of spirometry, flow-volume curves, lung volumes, and static respiratory pressures was performed in patients with PWS who are followed at the University of Connecticut. All tests were performed in triplicate on two or more occasions. Only reproducible tests were accepted. Established normative data were applied for all test results. RESULTS: A total of 18 male subjects (age, 17.9 +/- 10.2 years (mean +/- SD); range, 5-39 years) and 17 female subjects (age, 23.5 +/- 13.0 years; range, 5-54 years) completed the tests. Forced vital capacity and forced expiratory volume in 1 second were reduced; the forced expiratory volume in 1 second/forced vital capacity ratio was normal, total lung capacity was in the low normal range, and residual volume was elevated. Maximum inspiratory (PImax) and expiratory (PEmax) pressures were markedly reduced in 32 subjects tested. Fifteen subjects had PEmax values and 20 subjects had PImax values < 60 cm H2O, respectively. There was a linear correlation between forced expiratory volume in 1 second and both PImax and PEmax (r = 0.71; r = 0.62, respectively), and between forced vital capacity and both PEmax and PImax (r = 0.62 and r = 0.74, respectively). There was an inverse relationship between both PImax and PEmax, and residual volume (r = 0.47 and r = 0.72, respectively). CONCLUSION: Children and adults with PWS have restrictive ventilatory impairment primarily as a result of respiratory muscle weakness. Efforts to improve thoracic muscle strength may be useful in improving pulmonary function in individuals with PWS.

Adolescent↗