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Biomedical subjects

R H Houwen

Publications and source records attributed to R H Houwen.

At least 19 recordsLinked to original sources
PubMed2001

FIC1, the protein affected in two forms of hereditary cholestasis, is localized in the cholangiocyte and the canalicular membrane of the hepatocyte.

BACKGROUND/AIMS: FIC1 (familial intrahepatic cholestasis 1) is affected in two clinically distinct forms of hereditary cholestasis, namely progressive familial intrahepatic cholestasis type 1 (PFIC1) and benign recurrent intrahepatic cholestasis. Here we examined the subcellular localization of this protein within the liver. METHODS: Antibodies raised against different epitopes of human FIC1 were used for immunoblot analysis and immunohistochemical detection of FICI. RESULTS: Immunoblot analysis of intestine and liver tissue extracts from human, rat and mouse origin indicated that the antibodies raised against FIC1 specifically detected FIC1 as a 140-kDa protein. In the liver homogenate of a PFIC1 patient, FIC1 could not be detected. Analysis of isolated rat liver membrane vesicles indicated that this protein is predominantly present in the canalicular membrane fraction. Immunohistochemical detection of the protein in liver sections confirmed that FIC1 was present in the canalicular membrane, whereas no staining was observed in the PFIC1 patients liver. Double label immunofluorescence of murine liver revealed that FIC1 colocalized with cytokeratin 7 in cholangiocytes. CONCLUSIONS: The localization of FIC1 in the canalicular membrane and cholangiocytes suggests that it may directly or indirectly play a role in bile formation since mutations in FICI are associated with severe symptoms of cholestasis.

Adenosine Triphosphatases↗
PubMed2001

FIC1 disease: a spectrum of intrahepatic cholestatic disorders.

FIC1 disease collectively refers to a group of autosomal-recessive familial liver disorders characterized by intrahepatic cholestasis due to mutations in the ATP8B1 gene (initially named FIC1). Classically, FIC1 disease comprises two different disorders: progressive familial intrahepatic cholestasis type 1 (PFIC1) and benign recurrent intrahepatic cholestasis (BRIC). However, we now view these two disorders as two ends of a continuum. Current therapeutic strategies for FIC1 disease, both medical and surgical, may relieve symptoms, but are presently insufficiently evaluated. ATP8B1 encodes a protein belonging to a recently defined subfamily of P-type ATPases. The biochemical and cellular functions of its product, FIC1, and the mechanisms by which its absence or dysfunction leads to cholestasis are currently elusive. Further studies to elucidate FIC1's function will be essential to unravel the pathogenesis of FIC1 disease. Such studies will also have a general impact on our understanding of the molecular mechanisms of bile formation and may therefore improve clinical management of both hereditary and acquired forms of cholestasis.

Adenosine Triphosphatases↗
PubMed2001

The tissue transglutaminase gene is not a primary factor predisposing to celiac disease.

OBJECTIVES: The aim of this study was to determine whether the tissue transglutaminase (tTG) gene is a causal factor in the pathogenesis of celiac disease (CD). METHODS: A total of 147 Dutch families with at least one patient with biopsy-proven CD were available for this study. In all patients, CD was diagnosed according to the revised European Society for Pediatric Gastroenterology and Nutrition criteria. A microsatellite marker in a noncoding region of the tTG gene was investigated for both linkage and association. Linkage was tested by determining the amount of allele sharing between affected brothers and sisters (affected sibling [sib] pair analysis). Association was determined by comparing transmission of certain tTG alleles from parents to CD patients to the nontransmitted alleles by the transmission/disequilibrium test. RESULTS: Linkage analysis did not show cosegregation of the tTG gene with celiac disease in our families, and there was no association between certain tTG alleles and celiac disease. Furthermore, the tTG gene could be excluded as a CD susceptibility gene. CONCLUSION: Our results indicate that the tTG gene can be excluded as a major primary genetic factor in CD pathogenesis.

Adult↗
PubMed2000

Congenital sodium diarrhea is an autosomal recessive disorder of sodium/proton exchange but unrelated to known candidate genes.

BACKGROUND & AIMS: Congenital sodium diarrhea (CSD) is caused by defective sodium/proton exchange with only 6 sporadic cases reported. The genetics of the disease have not been established. We studied 5 infants with secretory diarrhea, identified in a circumscribed rural area in Austria, to define the mode of transmission and the involvement of candidate genes known to encode for sodium/proton exchangers (NHEs). METHODS: We collected clinical and laboratory data from 5 affected patients, analyzed the pedigrees of their families, and performed homozygosity mapping and multipoint linkage analysis studies in 4 candidate regions known to contain NHE genes. RESULTS: The diagnosis of CSD in 4 of 5 patients was based on daily fecal sodium excretion between 98 and 190 mmol/L, hyponatremia, metabolic acidosis, and low-to-normal urinary sodium concentrations. Pedigree analysis of the affected 2 CSD families revealed parental consanguinity and a common single ancestor 5 generations ago. Homozygosity mapping and/or multipoint linkage analysis excluded the NHE1 locus on chromosome 1, NHE2 locus on chromosome 2, NHE3 locus on chromosome 5, and NHE5 locus on chromosome 16 as potential candidate genes for CSD in this pedigree. Results on NHE4 were inconclusive because the precise chromosomal location of this NHE gene in humans is currently unknown. CONCLUSIONS: Our data indicate that CSD is an autosomal recessive disorder but is not related to mutations in the NHE1, NHE2, NHE3, and NHE5 genes encoding for currently known sodium/proton exchangers.

Chromosome Mapping↗
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↗
PubMed1999

[Recurrent familial intrahepatic cholestasis in the Faroe Islands].

Recurrent familial intrahepatic cholestasis is an autosomal recessive disorder characterized by episodes of severe pruritus and jaundice lasting for weeks to months without extrahepatic bile duct obstruction. Symptom-free intervals may last for months to years, and chronic liver damage does not develop. We recently studied four of the five patients from the Faeroe Islands described by us 30 years ago (one had recently died), and a further five patients who were identified after the initial report. The episodes of cholestasis were more frequent and severe in patients with early onset, but tended to reduce in frequency with age. The youngest patient, aged 25 years, who had had 16 episodes, each lasting about six months, had a liver transplant after which no further episodes were recorded (one year after surgery). Signs of chronic liver disease were absent in all patients. The FIC1 gene was investigated for mutations in the surviving patients. A single mutation (I661T) was found on both chromosomes in all 9 patients, indicating that they are genetically identical for the disease causing defect. Nevertheless, considerable differences between patients were observed clinically.

Adult↗
PubMed1999

[Diagnosis of celiac disease in children; guidelines for pediatric gastroenterologists. Section of Pediatric Gastroenterology, Dutch Society of Pediatrics].

For the diagnosis of coeliac disease (CD) to be made in children and for the prescription of a gluten-free diet, clear histological changes in the small bowel biopsy sample have to be found. Serological testing for antibodies against endomysium and gliadin has only a preliminary significance. In children with strong clinical suspicion of CD, histological investigation of a small bowel biopsy should be performed independently of the results of serological screening (endomysium and gliadin antibodies). In children with less clear clinical suspicion of CD, serological screening may be used to select those who need investigation of small bowel histology. The number of small bowel biopsies that should be performed has been changed. In children < 2 years with clinical symptoms and small bowel villous atrophy, CD is confirmed when symptoms and atrophy significantly improve during gluten-free diet, while small bowel histology significantly deteriorates during gluten challenge. In children > 2 years with clinical symptoms combined with abnormal serology and villous atrophy, CD is confirmed when during gluten-free diet the symptoms disappear and serology improves. In case of family screening, diseases associated with CD or Down's syndrome, CD is confirmed when symptoms (if any), and previous abnormal serology and small bowel histology significantly improve during gluten-free diet.

Adolescent↗
PubMed1999

Recurrent familial intrahepatic cholestasis in the Faeroe Islands. Phenotypic heterogeneity but genetic homogeneity.

Recurrent familial intrahepatic cholestasis is an autosomal recessive disorder characterized by episodes of severe pruritus and jaundice lasting for weeks to months without extrahepatic bile duct obstruction. Symptom-free intervals may last for months to years, and chronic liver damage does not develop. We recently studied four of the five patients from the Faeroe Islands described by us 30 years ago (one had recently died) and an additional five patients that were identified after the initial report. The episodes of cholestasis were more frequent and severe in patients with early onset, but tended to reduce in frequency with age. The youngest patient, aged 25 years, who had had 16 episodes each lasting about 6 months, had a liver transplant after which no further episodes were recorded (1 year after surgery). Signs of chronic liver disease were absent in all patients. The FIC1 gene was investigated for mutations in the surviving patients. A single mutation (I661T) was found on both chromosomes in all nine patients, indicating that they are genetically identical for the disease-causing defect. Nevertheless, considerable differences among patients were observed clinically.

Adenosine Triphosphatases↗
PubMed1999

Skinfold measurements in children with cystic fibrosis: monitoring fat-free mass and exercise effects.

UNLABELLED: Monitoring fat free mass (FFM), an indicator of nutritional status and a predictor of exercise performance in children, is particularly important in patients with cystic fibrosis (CF). We assessed validity of the skinfold method for measuring FFM, and its changes with exercise training, in children with CF. A total of 14 children with moderately severe symptoms of CF (age 10-18 years) were followed longitudinally and measured three times, before (at 0 and 6 months) and after exercise training (at 12 months). Separately, single measurements were conducted in 12 children with mild symptoms of CF and in 13 healthy controls. FFM was calculated from four skinfold measurements, and compared with estimations from total body water measured with deuterium dilution. The FFM calculated from skinfolds was 1.7% (P < 0.05) and 3.3% (P < 0.005) higher than that estimated with deuterium oxide dilution in patients with CF and controls, respectively. Limits of agreement were similar in patients with moderate and mild symptoms and in controls. The measurements in patients with moderate symptoms showed similar bias and limits of agreement at 6 and 12 months as compared to 0 months. Changes in FFM measured with both methods were significantly correlated before exercise (r = 0.82, P < 0.0005), and after exercise training (r = 0. 60, P < 0.05). CONCLUSION: In children with cystic fibrosis, skinfold measurements are applicable to monitor fat free mass irrespective of clinical severity of the disease, and repeated measurements at intervals of 6 months are applicable to monitor changes in fat free mass during exercise training.

Adolescent↗
PubMed1998

[Twenty years of childhood coeliac disease in the Netherlands: more diagnoses and a changed clinical picture].

OBJECTIVE: To assess the incidence of childhood coeliac disease in the Netherlands and to study the clinical features. DESIGN: Prospective. SETTING: Leiden University Medical Centre, Leiden, the Netherlands. METHOD: Cases of childhood coeliac disease in the Netherlands in 1993-1995 were identified by means of the Dutch Paediatric Surveillance Unit. Inclusion criteria were: birth in the Netherlands, diagnosis with at least one small bowel biopsy in 1993-1995 and age at diagnosis 0-14 years. The data were cross checked with the Dutch Network and National Database of Pathology and compared with data from a previous study on childhood coeliac disease, 1975-1990. RESULTS: 297 Coeliac patients were identified by means of the Surveillance Unit, another 32 through the National Database of Pathology. The mean crude incidence rate of diagnosed childhood coeliac disease was 0.51/1000 live births, which was in the range of rates found in other West European countries and significantly higher than the mean crude incidence rate of 0.18/1000 live births found in the Netherlands in 1975-1990. The clinical presentation was classic up to 1990: chronic diarrhoea, abdominal distention and growth failure. From 1993 onward, however, the number of children with chronic diarrhoea and abdominal distention decreased significantly and the number with weight loss, anaemia and abdominal pain increased. Associated disorders were present in 13.7% of the cases. CONCLUSIONS: The incidence of diagnosed childhood coeliac disease in the Netherlands showed a tendency to increase significantly during the past decade. In a period of 20 years a significant trend toward change in the clinical presentation of coeliac disease in Dutch children was observed.

Adolescent↗
PubMed1998

A gene encoding a P-type ATPase mutated in two forms of hereditary cholestasis.

Cholestasis, or impaired bile flow, is an important but poorly understood manifestation of liver disease. Two clinically distinct forms of inherited cholestasis, benign recurrent intrahepatic cholestasis (BRIC) and progressive familial intrahepatic cholestasis type 1 (PFIC1), were previously mapped to 18q21. Haplotype analysis narrowed the candidate region for both diseases to the same interval of less than 1 cM, in which we identified a gene mutated in BRIC and PFIC1 patients. This gene (called FIC1) is the first identified human member of a recently described subfamily of P-type ATPases; ATP-dependent aminophospholipid transport is the previously described function of members of this subfamily. FIC1 is expressed in several epithelial tissues and, surprisingly, more strongly in small intestine than in liver. Its protein product is likely to play an essential role in enterohepatic circulation of bile acids; further characterization of FIC1 will facilitate understanding of normal bile formation and cholestasis.

Adenosine Triphosphatases↗
PubMed1997

Total energy expenditure in infants with bronchopulmonary dysplasia is associated with respiratory status.

UNLABELLED: Growth failure is a well-known problem in infants with bronchopulmonary dysplasia (BPD). We studied BPD infants' total daily energy expenditure (Ee), nutritional balance, and growth in relation to their past and current clinical status. Applying the doubly labelled water technique, Ee was measured in nine preterm infants with BPD receiving supplemental oxygen (postnatal age 61 +/- 13 days) and nine matched controls (36 +/- 21 days) during a 6-day period. Energy and protein balance, past and present respiratory status, and growth were assessed as well. The results show that Ee was higher in the BPD infants compared to controls (73 +/- 9 vs 63 +/- 8 kcal/kg/day, P < 0.05), but their faecal energy loss was lower (P < 0.01). Weight gain, energy intake, energy cost of growth, protein retention, and physical activity were not different. The respiratory frequency (RR) in the BPD infants was elevated in comparison with controls (P < 0.01). Within the BPD group, RR was positively correlated with energy expenditure (regression equation: Ee [kcal/kg/day] = 26.3 + 0.71*RR [min-1]; r2 = 0.82, P < 0.001), and was the single most significant determinant of Ee. CONCLUSION: Total energy expenditure in BPD infants is elevated and is strongly associated with their respiratory status. These findings could be of practical value for the nutritional management in infants with severe BPD.

Anthropometry↗
PubMed1997

Benign recurrent intrahepatic cholestasis (BRIC): evidence of genetic heterogeneity and delimitation of the BRIC locus to a 7-cM interval between D18S69 and D18S64.

Benign recurrent intrahepatic cholestasis (BRIC) is an autosomal recessive liver disease characterized by multiple episodes of cholestasis without progression to chronic liver disease. The gene was previously assigned to chromosome 18q21, using a shared segment analysis in three families from the Netherlands. In the present study we report the linkage analysis of an expanded sample of 14 BRIC families, using 15 microsatellite markers from the 18q21 region. Obligate recombinants in two families place the gene in a 7-cM interval, between markers D18S69 and D18S64. All intervening markers had significant LOD scores in two-point linkage analysis. Moreover, we identified one family in which the BRIC gene seems to be unlinked to the 18q21 region, or that represents incomplete penetrance of the BRIC genotype.

Cholestasis, Intrahepatic↗
PubMed1997

Twenty years of childhood coeliac disease in The Netherlands: a rapidly increasing incidence?

BACKGROUND: The incidence of coeliac disease varies internationally. AIMS: To assess the incidence of childhood coeliac disease in The Netherlands and to study the clinical features and the presence of associated disorders. SUBJECTS: Identified cases of childhood coeliac disease in The Netherlands in 1993-4 by means of the Dutch Paediatric Surveillance Unit. METHODS: Inclusion criteria were born in The Netherlands, diagnosed with at least one biopsy of the small bowel in 1993-4 and age at diagnosis 0-14 years. The data were cross checked by the Dutch Network and National Database of Pathology and compared with data from a previous study on childhood coeliac disease, 1975-90. RESULTS: A total of 193 coeliac patients were identified by means of the Surveillance Unit, another 20 through the National Database of Pathology. The mean crude incidence rate of diagnosed childhood coeliac disease was 0.54/1000 live births, which is in the range of rates found in other western European countries and significantly higher than the mean crude incidence rate of 0.18/1000 live births found in The Netherlands in 1975-90. The clinical presentation was classic: chronic diarrhoea, abdominal distension, and growth failure. Associated disorders were present in 11.7% of the cases. CONCLUSIONS: The incidence of diagnosed childhood coeliac disease in The Netherlands seems to have increased significantly during the past few years. In a period of 20 years no significant changes could be found in the clinical picture at preentation of coeliac disease in Dutch children.

Adolescent↗
PubMed1997

Low-dose versus high-dose ursodeoxycholic acid in cystic fibrosis-related cholestatic liver disease. Results of a randomized study with 1-year follow-up.

BACKGROUND: Ursodeoxycholic acid (UDCA) is beneficial in cholestasis related to cystic fibrosis (CF). High-dose treatment has been recommended to compensate for bile salt malabsorption. We compared the results of low-dose (10 mg/kg/day) and high-dose (20 mg/kg/day) UDCA treatment on liver biochemistry after 3 and 12 months' treatment. METHODS: Thirty CF patients (age > 5 years) with biochemical cholestasis and compensated liver disease were randomized for low-dose (n = 17) or high-dose (n = 13) UDCA. Baseline clinical variables were comparable. RESULTS: After 1 year one patient had died of liver failure (low dose), and three had dropped out because of pruritus (one in each group) or personal choice (low dose). In the high-dose group improvement in gamma-glutamyl transferase values was more pronounced after 3 months and 1 year (P < 0.004), and improvement of alanine aminotransferase was better after 1 yer (P < 0.02). Improvement of alkaline phosphatase and aspartate aminotransferase was comparable. Complete normalization of liver enzymes and bilirubin occurred more often in the high-dose group. CONCLUSION: High-dose UDCA induces a better response of liver biochemistry values than low-dose UDCA in CF patients with cholestatic liver disease.

Adolescent↗