| Research Abstract |
1. Understanding the hemoglobin switching regulation mechanism in extremely premature infants is paricularly important for understanding the extrauterine adaptation of the infants. (1) Aging is required for hemoglobin switching. (2) Switching in premature infants (27 to 32 weeks) is delayed at least 3 weeks in comparison with full-term infants. (3) A delay in the switching of fetal hemoglobin to adult hemoglobin was confirmed in IUGR (intrauterine growth retardation) infants. However, there is a compensatory increase in 2, 3-DPG for adaptation after birth. (4) A delay in 2, 3-DPG increase was observed in RDS (respiratory distress syndrome) infants, and oxygen affinity remained high. 2. The results you have just seen shed light on the development of the fetus and neonate from the viewpoint of the transport of substances in the cell membrane -- the brush borders -- of the placenta and kidney. 1) The amounts transported are significantly larger in the final stage of pregnancy compared to
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the early stage, due to the increase in the number of carriers. 2) In the fetal stage, the glucose-alanine cycle found in adults does not function. 3) The reabsorption capacity of the convoluted tubule of the kidney is still undeveloped in premature neonates, so electrolytes, amino acids and glucose are excreted in the urine. As a result, the concentration in the blood decreases. 3. Throughout the gestational period, a non-specific immune response is fully developed at an early stage. With regard to specific immunity, T cell MHC recognition and other functions which form the foundation of the immune system are developed at an early stage. however, the mitogenic blast forming reaction and production of antibodies requiring coordination of more advanced T cells and B cells are markedly reduced, thus characterizing an immature immune system. The turning point in the development of the fetal immune system is apparently the 32nd gestational week. In premature neonates born before this point, the neutrophil, macrophage, NK cell function, complementary system, and immunoglobulin levels are all less developed than in full term neonated, and strict measures are required to prevent infection. Less
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