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Intestinal retinol esterification and serum retinol in children with cystic fibrosis
Insights
Children with cystic fibrosis (CF) often have low vitamin A levels. While acyl-CoA:retinol acyltransferase (ARAT) activity was measured, pancreatic enzyme deficiency is likely the primary cause of poor vitamin A absorption in CF patients.
Area of Science:
- Biochemistry
- Pediatrics
- Gastroenterology
Background:
- Children with cystic fibrosis (CF) frequently exhibit suboptimal vitamin A status.
- Reduced serum retinol levels are observed in older children diagnosed with CF.
- Vitamin A absorption involves retinol entering the intestinal lymph as retinyl esters, highlighting the potential role of acyl-CoA:retinol acyltransferase (ARAT).
Purpose of the Study:
- To investigate the activity of ARAT in the duodenal mucosa of children with CF.
- To determine if ARAT activity is significantly different in CF patients compared to healthy controls.
- To explore the contribution of ARAT to vitamin A malabsorption in CF.
Main Methods:
- Assaying ARAT activity in duodenal mucosal homogenates obtained from children with CF.
- Comparing ARAT activity levels in CF patients against a control group.
- Analyzing ARAT activity in patients with celiac disease and lactose intolerance.
Main Results:
- ARAT activity in the duodenal mucosa of children with CF showed considerable individual variation.
- Mean ARAT activity in CF patients was not significantly lower than in control subjects.
- Significant reductions in mean ARAT activity were observed in patients with celiac disease and lactose intolerance, which are mucosal disorders.
Conclusions:
- The primary factor contributing to reduced vitamin A absorption in cystic fibrosis is likely the deficiency of pancreatic enzymes, not diminished ARAT activity.
- While ARAT plays a role in retinol absorption, its activity appears preserved in CF patients.
- Mucosal disorders like celiac disease and lactose intolerance are associated with significantly reduced ARAT activity, suggesting a different mechanism of malabsorption compared to CF.
Abstract:
Children with cystic fibrosis (CF) often have a poor vitamin A status. We found in the present work a reduced level of serum retinol in older children with this disease. As retinol enters intestinal lymph as retinyl esters, the enzyme acyl-CoA:retinol acyltransferase (ARAT) may be of importance for retinol absorption. We have assayed ARAT activity in duodenal mucosal homogenate from children with CF. There was a large variation within the group. However, mean ARAT activity was not significantly decreased, as compared with controls. Thus, the lack of pancreatic enzymes probably is the main reason for reduced vitamin A absorption in CF. In celiac disease and in lactose intolerance--both mucosal disorders--a significant reduction of mean ARAT activity was found.