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Biomedical subjects

I M Nielsen

Publications and source records attributed to I M Nielsen.

At least 19 recordsLinked to original sources
PubMed2004

Cholestasis Familiaris Groenlandica/Byler-like disease in Greenland--a population study.

OBJECTIVES: Cholestasis Familiaris Groenlandica (CFG, or progressive familiar intrahepatic cholestasis type 1 (PFIC1)) is a very common lethal recessive inherited disease in Greenland. A missense mutation, 1660G>A (asp554asn) in the gene ATP8B1 causes the disease (Klomp et al. 2000). STUDY DESIGN: A family study examining medical files from the period 1951-2003 from East Greenland resulted in 46 cases of PFIC1 and more than 220 relatives showing carrier status. Further, random blood sample testing 953 anonymous persons from 11 major cities or districts all over Greenland have been analysed for carrier status of the mutation. METHODS: A sensitive PCR method is developed to distinguish between normal and mutant alleles for ATP8B1 in the Greenland population. RESULTS: The mutation 1660G>A is found in all areas of Greenland, and the frequency of the mutant allele vary all over the country. A shockingly high frequency for the mutant allele is found in East Greenland in Ittoqqortoormiit (0.16) and in Tasiilaq (0.077), whereas in Northwest Greenland lower frequencies are found in Uummannaq and Ilulissat (0.032), and Maniitsoq (0.005). CONCLUSIONS: The high frequency of the mutation in East and Northwest Greenland strongly indicates that routine screening of the population for carrier status should be done.

Adenosine Triphosphatases↗
PubMed2004

Cholestasis Familiaris Groenlandica: an epidemiological, clinical and genetic study.

OBJECTIVES: Accumulation of Cholestasis Familiaris Groenlandica (CFG) or progressive familial intrahepatic cholestasis type 1 (PFIC1) occurs in indigenous Inuit families in Greenland. It is an autosomal recessive inherited liver disease. From early childhood the children suffer from failure to thrive, jaundice, pruritus and enlarged liver. Affected persons generally die very young. STUDY DESIGN: Patients' information has been collected from the Greenlandic death register and hospital records. METHODS: Detailed genealogy including clinical description and examination if possible. Interviews of parents and relatives, linkage and DNA analysis of the probands and the closest relatives have been studied. RESULTS: 46 affected cases from a highly inbred population have been diagnosed since 1943. The disease is caused by a missense mutation in the FIC1 gene ATP8B1, chromosome 18q21. Six affected children are alive aged 1-21 years. Among the tested relatives 220 are heterozygote. One prenatal diagnosis has been performed. CONCLUSION: The mutation causing Cholestasis Familiaris Groenlandica is widespread in Greenland, but accumulation is seen in certain areas. The disease is burdensome for the child, the parents and the Greenlandic society. Genetic counselling and carrier screening are strongly recommended.

Adenosine Triphosphatases↗
PubMed2004

Epilepsy among children in Greenland.

INTRODUCTION: Epilepsy has been considered to be more frequent in Greenland than in Denmark, where the prevalence among children is 0.40%. STUDY DESIGN: Evaluation of the prevalence, diagnosis and treatment of epilepsy among children in Greenland aged 0-15 years. METHODS: During autumn 2000, 13 out of 18 hospitals in Greenland were visited. The population of children in the areas visited was 11,965 of a total of 15,226 in Greenland. All children with the diagnosis of epilepsy were referred for evaluation and the diagnosis was confirmed. When possible, informed consent was obtained to collect data from medical records. RESULTS: 43 children (18 boys) had the diagnosis of epilepsy. For 38 (15 boys) further data were obtained. Mean age was 8.5 years (3-14) for boys and 7.9 years (2-14) for girls. The age at diagnosis was 4.9 years (1-11) for boys and 4.2 years (0-10) for girls. The prevalence of epilepsy was 0.34%. In 31 cases an electroencephalograph (EEG) recording was done, comprising sleep recordings in 26 cases. Medication was according to recommendations in Denmark. CONCLUSION: The prevalence of epilepsy in children and the medical treatment of epilepsy among children in Greenland is the same as in Denmark.

Adolescent↗
PubMed2000

High incidence of propionic acidemia in greenland is due to a prevalent mutation, 1540insCCC, in the gene for the beta-subunit of propionyl CoA carboxylase.

Propionyl CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme involved in the catabolism of amino acids, odd-chain fatty acids, and other metabolites. PCC consists of two subunits, alpha and beta, encoded by the PCCA and PCCB genes, respectively. Inherited PCC deficiency due to mutations in either gene results in propionic acidemia (PA), an autosomal recessive disease. Surprisingly, PA is highly prevalent among Inuits in Greenland. We have analyzed reverse transcriptase-PCR products of the beta-subunit mRNA, to characterize the responsible mutation(s). A 3-bp insertion, 1540insCCC, was found in homozygous form in three patients and in compound heterozygous form in one patient. The resulting PCC has no measurable activity, and the mutant beta-subunit appears to be very unstable. To test the hypothesis that a common mutation is responsible for PA in the Greenlandic Inuit population, 310 anonymous DNA samples of Inuit origin were screened for 1540insCCC. We found a carrier frequency of 5%, which is very high compared with those of most other autosomal recessive diseases. Analysis of alleles of a very closely linked marker, D3S2453, revealed a high degree of linkage disequilibrium between one specific allele and 1540insCCC, suggesting that this mutation may be a founder mutation.

Alleles↗
PubMed2000

A missense mutation in FIC1 is associated with greenland familial cholestasis.

Greenland familial cholestasis is a severe form of intrahepatic cholestasis described among indigenous Inuit families in Greenland. Patients present with jaundice, pruritus, bleeding episodes, and steatorrhea, and die in childhood due to end-stage liver disease. We investigated the possibility that Greenland familial cholestasis is caused by a mutation in FIC1, the gene defective in patients with progressive familial intrahepatic cholestasis type 1 and many cases of benign recurrent intrahepatic cholestasis. Using single-strand conformation polymorphism analysis and sequencing of the FIC1 exons, a missense mutation, 1660 G-->A (D554N), was detected and was shown to segregate with the disease in Inuit patients from Greenland and Canada. Examination of liver specimens from 3 Inuit patients homozygous for this mutation revealed bland canalicular cholestasis and, on transmission electron microscopy, coarsely granular Byler bile, as previously described in patients with progressive familial intrahepatic cholestasis type 1. These data establish Greenland familial cholestasis as a form of progressive familial intrahepatic cholestasis type 1 and further underscore the importance of unimpeded FIC1 activity for normal bile formation.

Adenosine Triphosphatases↗
PubMed2000

Linkage of Cholestasis Familiaris Groenlandica/Byler-like disease to chromosome 18.

In East Greenland (Tasiilaq) a common recessive disease, Cholestasis Familiaris Groenlandica (CFG)/Byler-like disease, occurs in Eskimo children. Samples from 123 persons, from a large consanguineous pedigree in East Greenland including 7 affected and 3 small families from West Greenland with a total of 4 affected children, have been collected for linkage and homozygosity studies. An earlier hint of linkage to chromosome 18q (lod score of 1.5 to blood group JK) is now raised to a multipoint lod score of Z = 3.25 in the area of the DNA markers D18S851 and D18S858. Different haplotypes follow the disease gene among Inuits in West Greenland and a possibility of locus heterogeneity of CFG between East and West Greenland exist.

Child↗
PubMed1997

Deprotonation and hydride shifts in nitrenium and iminium forms of aminoimidazole-azaarene mutagens.

The mutagenicity of many 2-aminoimidazole-azaarenes (AIA) is thought to be mediated by the nitrenium form of the exocyclic amine. This hypothesis is supported by the numerous correlations found between calculated and experimentally-measured chemical properties for the nitreniums and the mutagenic potencies of the nitreniums and their parent amines. One factor favoring high mutagenic potency is the presence of a methyl substituent in the 1- or 3-imidazole position. In this paper, we investigate both the deprotonation of the imidazole ring nitrogens in non-N-methylated AIA mutagens and the plausibility of a chemical pathway involving a 1-4 hydride shift to form an iminium ion, thereby stabilizing the cationic N-methyl substituted AIA mutagens. It has been widely noted that factors that stabilize the nitrenium moiety lead to significantly higher mutagenic potency; hence, the transformation of the nitrenium to a more stable species might be expected to increase the potency, provided that it does not eliminate the electrophilic reactivity of the compound. Using ab initio quantum chemistry and polarizable continuum solvation models, we find that the imidazole ring nitrogens of the nitrenium ions are extremely acidic. This suggests that upon formation of the exocyclic nitrenium these sites will deprotonate to form a neutral imine. We have also studied the 1-4 hydride shift from an imidazole ring methyl to the exocyclic nitrenium to form an iminium. We predict that for AIA mutagens with just two fused rings the resulting iminium species are more stable in the gas phase than the corresponding nitreniums. For mutagens with larger conjugated systems, the nitrenium is stabilized by resonance and is more stable than the corresponding iminium. In the aqueous phase, however, the iminium form is predicted to be more stable than the nitreniums for all polycyclic compounds studied. Although equilibrium calculations favor the iminium form, these have been experimentally shown to be short-lived and their actual concentration will depend on the complex kinetics of AIA mutagen metabolism. The quantum chemical results also show a strong correlation between the relative iminium-nitrenium energy difference and the charge on the exocyclic nitrogen.

Aza Compounds↗
PubMed1996

Microvascular free flaps in the treatment of defects of the lower legs.

Thirty-four microvascular free flaps were used to treat defects in the lower extremities after injuries. Twenty patients (74%) had severe open fractures (Gustilo type III B & C). Latissimus dorsi (n = 16) and iliac osteocutaneous (n = 7) flaps were most commonly used for coverage, and the overall failure rate was 9% (3/34). At follow up 29 of the patients (94%) had a reduced range of movement of the ankle, nine (29%) had some swelling and oedema, and 13 (42%) had occasional pain in the leg. Sixteen (52%) of the patients were limping, but 26 (84%) could walk one kilometre or more with no problems. No legs were amputated. The unemployment rate increased from 1/34 (3%) to 6/31 (19%) at follow up. Twenty-seven (87%) of our patients were satisfied with the results, despite the considerable and persistent limitation of function, and the increase in the unemployment rate.

Adolescent↗
PubMed1995

Measurements of tissue oxygen tension in vascularised jejunal autografts in pigs.

Tissue oxygen measurements were evaluated as a monitor of the jejunal flap in seven female landrace pigs. A small polarographic sensor (diameter 0.55 mm) was used in which interstitial tissue oxygen tension was measured continuously in a jejunal flap and a muscle flap (rectus abdominis) during arterial and venous occlusion. Mean (SEM) tissue oxygen tension in the two types of flap were 44(9) mmHg (jejunal flap) and 47(8) mmHg (rectus flap). After arterial occlusion for 30 minutes the values dropped to 17(4) mmHg for the jejunal flap and 12(2) mmHg for the muscle flap. The decline became significant after five minutes. During venous occlusion (30 minutes) the values fell to 20(4) mmHg and 14(1) mmHg. The arterial occlusion was undetectable by the naked eye, but the enteric tissue after venous occlusion became severely congested and blue-black in colour. The condition returned to normal after release of the clamp. We conclude that direct measurement of tissue oxygen tension in a jejunal flap is a reliable method of detecting impaired perfusion. This method may in the future be used to monitor vascularised jejunal autografts.

Animals↗
PubMed1994

Juvenile Kearns-Sayre syndrome initially misdiagnosed as a psychosomatic disorder.

We have investigated a 15 year old girl with progressive external ophthalmoplegia, including bilateral ptosis and retinal rod and cone cell dysfunction with atypical retinal pigmentation, complicated by cerebellar ataxia, partial cardiac conduction block, and diabetes mellitus. In infancy she had a severe crisis of bone marrow depression, and as a child she suffered from hypersensitivity to light, increasing fatigue, and vertigo, signs that were initially though to be psychosomatic. Histological examination showed mitochondrial myopathy, and subsequent mitochondrial DNA (mtDNA) analysis showed a deletion of approximately 5500 base pairs in 35 to 40% of her muscle mtDNA. We therefore conclude that this patient has developed the Kearns-Sayre syndrome after a Pearson syndrome-like crisis in her first year of life.

Adolescent↗
PubMed1989

Fatal familial cholestatic syndrome in Greenland Eskimo children. A histomorphological analysis of 16 cases.

We report the first detailed study of hepatic morphology in 28 biopsies from 16 Greenland Eskimo children with fatal familial cholestatic syndrome. The changes were categorized as early, intermediate and late. In the early stage, until 5 months of age, changes were restricted to zone 3, consisting of cholestasis and rosette formation without fibrosis. In the intermediate stage, from 5 to 14 months, cholestasis persisted and rosette formation increased, both with further extension into zone 2. Perisinusoidal fibrosis developed, first in zone 3 and later in zone 1. The late stage, from 17 to 60 months, showed a further increase in cholestasis and rosette formation, and fibrosis of zones 3 and 1 in nearly all biopsies. Portal to portal and portal to central fibrosis was evident with resulting cirrhosis in 2 of 7 patients. The morphological features can be summarized as pure cholestasis with prominent rosette formation followed by zone 3 fibrosis, zone 1 fibrosis, and, cirrhosis. Other characteristics are the virtual absence of inflammation and the lack of anatomical abnormalities such as paucity of bile ducts. The changes and their progression resemble those of Byler disease. Clinical and biochemical features are also largely similar, except for the presence of thrombocytosis in many of the Eskimo patients.

Biopsy↗
PubMed1989

Hemoglobinopathies in Danish families.

Based on cases referred for investigation, as well as a questionnaire sent to all medical and pediatric departments in Denmark, 48 cases of hemoglobinopathy in 15 families of Danish ancestry are reviewed. 18 Danes in six families have been identified as having beta-thalassemia, and remarkably one - a homozygote - has beta-thalassemia intermedia requiring treatment with iron-chelation therapy. A further 36 Danes in 9 families have a hemoglobin variant: five unstable hemoglobins (Volga, Niteroi, and three unidentified), one hereditary methemoglobinemia (M-Arhus), one polycythemia (Ty Gard) and 2 asymptomatic (Athens-Georgia and Hafnia). Although rare in Danish families, a hemoglobinopathy should be considered in families with an unexplained chronic hemolytic anemia, cyanosis or polycythemia.

Denmark↗
PubMed1988

Derivatives of 2-methylenepropane-1,3-diol as new antagonists of platelet activating factor.

Two new achiral platelet activating factor (PAF) antagonists, N-[5-[[2-methylene-3- [[(octadecylamino)carbonyl]oxy]propoxy]carbonyl]pentyl]pyridinium bromide and 3-[6-[[2-methylene-3- [[(octadecylamino)carbonyl]oxy]propoxy]carbonyl]hexyl]thiazolium bromide were synthesized from 2-methylenepropane-1,3-diol. Platelet aggregation in platelet-rich plasma from rabbits, induced by racemic C16-PAF, was competitively antagonized by 9 or 10. At concentrations less than or equal to 10(-4) M, neither compound 9 nor compound 10 caused platelet aggregation, nor did they inhibit platelet aggregation induced by collagen or adenosine diphosphate. Bronchoconstriction in the guinea pig and hypotension in the rat, induced by racemic C16-PAF, were also effectively antagonized by 9 and 10. Both appear to be more potent as PAF antagonists than Takeda's CV-3988.

Animals↗
PubMed1988

The fate of the split thickness skin graft in neovaginas. A pathologic study of 21 cases and a review of the literature.

Twenty-one cases of congenital absence of the vagina corrected by McIndoe's procedure were examined. The longest follow-up was 21 years (average 10.5 years). Vaginal biopsies showed a spectrum of changes, ranging from an almost normal vaginal mucous membrane to a skin-like mucous membrane. Neither hormonal status nor postoperative complication, nor the time the graft had been in place, correlated to histology, and we suggest that the varied appearance of the graft epithelium depends on the amount of corium included in the transplant.

Adolescent↗