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Studies on urea cycle enzyme levels in the human fetal liver at different gestational ages
M Mukarram Ali Baig1, C M Habibullah, M Swamy
1Department of Gastroenterology, Osmania General Hospital, Hyderabad Andhra, Pradesh, India.
Insights
Urea cycle enzyme activity, crucial for ammonia detoxification, is present in fetal liver by 13 weeks gestation. This activity progressively increases, reaching near-adult levels by 36 weeks.
Area of Science:
- Biochemistry
- Developmental Biology
- Hepatology
Background:
- Ammonia detoxification is vital for preventing hyperammonemia.
- The urea cycle is the primary pathway for ammonia metabolism in the liver.
- Understanding the developmental expression of urea cycle enzymes is crucial for fetal health.
Purpose of the Study:
- To investigate the developmental expression and activity of urea cycle enzymes in fetal liver.
- To determine the onset and progression of urea cycle enzyme activity during gestation.
- To compare fetal urea cycle enzyme activity with adult levels.
Main Methods:
- Liver tissue samples were obtained from fetuses (13-36 weeks gestation) and adult controls.
- Enzyme activity assays were performed on surgical wedge biopsies.
- Activity levels were measured across different gestational ages and compared to adult controls.
Main Results:
- Significant urea cycle enzyme activity was detected as early as 13 weeks of gestation.
- Enzyme activity showed a gradual increase with advancing gestational age.
- By 36 weeks gestation, fetal liver enzyme activity reached approximately 90% of adult levels.
Conclusions:
- Urea cycle enzymes are expressed early in fetal development.
- The fetal liver progressively develops ammonia detoxification capacity throughout gestation.
- The urea cycle is largely functional in the late third trimester, approaching adult capacity.
Abstract:
Urea cycle enzymes involved in the detoxification of ammonia were studied in liver tissues of 57 male and 49 female fetuses of different age groups ranging from 13 to 36 wk of gestation. Surgical wedge biopsies of liver from 18 male and 12 female adults were used as controls. Significant enzyme activity was found to be present as early as the 13th wk of gestation. As gestational age advanced, enzyme activity gradually increased, reaching about 90% of the adult activity by the 36th wk of gestation.