Modern organisms commonly use the same set of 20 genetically coded amino acids for protein synthesis with very few exceptions. However, earlier protein synthesis was plausibly much simpler than modern one and utilized only a limited set of amino acids. Nevertheless, few experimental tests of this issue with arbitrarily chosen amino acid sets had been reported prior to this report. Herein we comprehensively and systematically reduced the size of the amino acid set constituting an ancestral nucleoside kinase that was reconstructed in our previous study. We eventually found that two convergent sequences, each comprised of a 13-amino acid alphabet, folded into soluble, stable and catalytically active structures, even though their stabilities and activities were not as high as those of the parent protein. Notably, many but not all of the reduced-set amino acids coincide with those plausibly abundant in primitive Earth. The inconsistent amino acids appeared to be important for catalytic activity but not for stability. Therefore, our findings suggest that the prebiotically abundant amino acids were used for creating stable protein structures and other amino acids with functional side chains were recruited to achieve efficient catalysis.
Nitric oxide (NO) is a potent vasodilator produced by endothelial cells. Endothelin 1 (ET-1), another agent made by endothelial cells, is the most potent vasoconstrictor known to date. Endogenous NO and ET-1 may play a part in the normal physiological pulmonary vascular changes during the postnatal period. However, the changes of NO and ET-1 in healthy neonates have not been defined. We determined serum NO metabolites, i.e., nitrites and nitrates, and plasma ET-1 in 19 healthy neonates at birth (cord blood) and at ages 5 and 30 days. The sums of serum nitrite and nitrate (NOx) levels were 27.5 ± 12.8,53.8 ± 14.2, and 38.3 ± 13.2 μmol/l at birth, age 5 days, and age 30 days, respectively. The plasma ET-1 concentrations were 3.9 ± 1.6, 1.1 ± 0.2, and 1.1 ± 0.2 × 106 μmol/l at birth, age 5 days, and age 30 days, respectively. These changes in healthy neonates suggest the presence of active physiological roles for NO and ET-1 in circulatory adaptation to extra-uterine life.
We describe a case of cord blood harvest for autologous transfusion in a neonate weighing 3,992 g with a giant sacrococcygeal teratoma. The umbilical vein was pierced with an 18-gauge needle, and placental blood was withdrawn into two 50-ml syringes filled with 4 ml of citrate-phosphate-dextrose solution. Resection of the sacrococcygeal teratoma was performed on day one. During the operation the infant lost 46 ml of whole blood, more than 15% of the estimated total blood volume, and thus underwent autologous transfusion with 27.8 ml of packed red cells obtained from autologous cord blood. Consequently, she could avoid homologous blood transfusion during the hospital stay. This case highlights the safety of this procedure, with no evidence of consumption coagulopathy, hemolysis or bacterial infection.
ELBW infants are still the population at greatest risk for repeated blood transfusions after introduction of erythropoietin treatment. If labor develops, it is often impossible to extend the pregnancy period, therefore efforts should be made to increase hemoglobin level at birth.
An infant born in the 34th week of gestation weighing 5,355 g with a massive sacrococcygeal (SC) tumor was delivered by elective cesarean section. An ultrasonographic examination showed solid and cystic components in the tumor. Resection was successfully undertaken with insertion of a Nélaton catheter into the rectum to avoid unnecessary impairment of the viscera. The tumor weighed 2,380 g, measured 25 x 14 x 11 cm, and was clinicopathologically diagnosed to be a SC teratoma. This experience and other publications show that several considerations including control of hemorrhage and coagulopathies, visceral protection, and avoidance of wound infection are necessary to facilitate the surgical management of massive SC tumors. Several suggestions are made concerning the pre- and intraoperative management of this rare tumor.
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