George R. Kerr

Growth and Development of the Fetal Rhesus Monkey

Fatty acids of major phospholipids were evaluated in lung homogenate of rhesus monkeys. Studies were conducted at 5 fetal ages and in adult animals. The total concentrations of sphingomyelin, phosphotidyl ethanolamine and phosphatidyl choline increased progressively during fetal life, demonstrated at 2- to 3-fold increase during the 25-day period prior to full-term gestation, and remained at the same level or decreased in the lungs of adult animals. The predominant fatty acid esterifiedto sphingomyelin was stearic acid; that of phosphatidyl ethanolamine was oleic acid; and that of phosphotidyl choline was palmitic acid. These data and this species may be used to improve understanding of pulmonary development in the human fetus and the respiratory problems of prematurity.

Environmental deprivation: its effect on the growth of infant monkeys.

The nutritional intake of children with “deprivation dwarfism” has usually been reported to be normal, and in the absence of other etiologic explanations, their growth failure has been attributed to lack of environmental stimulation. Infant rhesus monkeys reared under conditions of total social isolation developed gross behavioral abnormalities, but grew at normal rates when fed an ad libitum diet. On the basis of these observations, inadequate nutrition would appear to be the most plausible explanation for the growth failure which may occur in children who are reared in deprived environments.

Phenylalanine: Transplacental centrations in Rhesus Monkeys

Arbino acids are actively transported across the mammalian placenta, crncentrations in fetal blood being higher than those in the maternal circu-Elevated concentrations of phenylalanine were induced by dietarv means blood of pregnant rhesus monkeys, and the active transport mechanism vident at both normal and elevated concentrations. A normal placental may thus magnify a maternal biochemical abnormality and produce a profound disturbance in the fetus.

The free amino acids of amniotic fluid during pregnancy of the rhesus monkey

Abstract The free amino acids of amniotic fluid were analyzed during pregnancy of the rhesus monkey. Samples of amniotic fluid and of fetal and maternal blood were obtained at cesarean section delivery at exactly 50, 75, 100, 125, and 150 days of gestational age. The total value of 19 amino acids in amniotic fluid decreased sequentially with advancing gestational age; the same trend was seen for most of the individual amino acids. Taurine was unique in showing the opposite trend, and demonstrated increasing levels at each subsequent stage of pregnancy. The free amino acids of amniotic fluid did not reflect the levels in the serum of either fetal or maternal blood.

The Development of Infant Monkeys Fed Low Phenylalanine Diets

Extract: The nutritional adequacy of a commercial low-phenylalanine diet (Diet LF) has been investigated in infant rhesus monkeys. All animals were fed a control diet (Diet CD) during the first month of life. Thereafter, animals in Group A were fed LF until seventy-five days of age. This diet was then supplemented with 0.1 g of L-phenylalanine per kilogram of body weight until 105 days of age and with 0.2 g of L-phenylalanine per kilogram from 105 to 135 days of age. Animals in Group B were fed LF supplemented with an amount of L-phenylalanine equal to that contained in CD (0.087 g/100 ml) from 30 to 135 days of age. For the remainder of the first year of life, all animals were again fed CD. Animals in Group A developed growth failure, anemia, hypoproteinemia, dermatitis, edema, hypophenylalaninemia and elevated levels of several other free amino acids in serum when fed LF. The addition of supplements of L-phenylalanine corrected hypoproteinemia, hypophenylalaninemia, and anemia, but improvement of dermatitis and growth rates were not seen until the animals were again fed CD. Animals in Group B developed dermatitis and elevated levels of several of the free amino acids in serum, but showed no other biochemical or clinical evidence of phenylalanine deficiency. After one year of age, all animals were evaluated for learning behavior. There was a significant decrease in the learning ability of animals in Group A, while that of animals in Group B was comparable with that of control animals.Speculation: Synthetic diets have been proposed as specific therapy for those inborn errors of metabolism that usually result in serious disability or death. Infant rhesus monkeys fed a commercial low-phenylalanine diet developed a syndrome of phenylalanine deficiency comparable with that which has been reported in some human infants fed the same diet. This study demonstrates the potential adverse effects of any diet deficient in essential nutrients and indicates that this subhuman primate may be of value in investigating the nutritional adequacy of other synthetic diets that may be proposed for use in children.

Growth and Development of the Fetal Rhesus Monkey ( Macaca mulatta ). II. Total Nitrogen, Protein, Lipid, Glycogen, and Water Composition of Major Organs

Extract: The developmental changes in the fractional nitrogen, protein, lipid, glycogen, and water content of major organs have been defined in the fetal rhesus monkey; the placenta, liver, brain, kidney, muscle, and lung were analyzed for each component at 50, 75, 100, 125, 150 and 175 days conceptual age, and the data were compared with those of healthy adult monkeys. Each organ was found to “mature” biochemically at characteristic rates. The relative water content of each organ showed a variable decrease with advancing fetal and postnatal life. The liver demonstrated the lowest value at each age studied, and the lung showed little change in its relative water content until structural maturation and extrauterine respiratory movements occurred. The value for fetal muscle showed the greatest rate of decrease with advancing gestation: the rate of change closely paralleled that previously reported for total body water during fetal life in this species.The relative nitrogen and protein content of all organs except the liver increased sequentially during fetal life; lung showed a marked increase in these values during late gestation and was the only organ which did not show an additional increase between birth and adult life. Muscle showed the steepest rate of increase in relative protein content during fetal life. The value for liver decreased between 75 and 100 days gestational age; thereafter little change was apparent until after 150 days, when a marked increase occurred.The relative lipid content of each fetal organ showed a characteristic pattern of change during fetal life; muscle and placenta demonstrated low values at all ages studied. The adult value for lung was reached by the time of full-term gestation. The relative lipid content of the liver was higher than those of other organs during the first half of pregnancy; little change occurred during fetal life, but major increases were seen between 150 and 175 days conceptual age, and between birth and adult life. The relative lipid content of the brain was greater than that of all other organs at the completion of fetal life; the level increased markedly during late gestation and continued after birth.The relative glycogen content of the kidney and brain was low at all ages studied; the lung had elevated levels early in gestation which fell with structural maturity. The value for fetal muscle rose progressively until 150 days gestational age, then fell to adult levels. Adult values for liver were reached prior to the time of full-term gestation, but a marked decrese occurred during the neonatal period. These data will provide control values for studies into the nutritional factors influencing fetal growth and development.Speculation: The patterns of physical, structural, biochemical, and behavioral development of the postnatal rhesus monkey are generally comparable to those of the postnatal human infant and child; enough data now exist to indicate that many of the processes of fetal biology of these two primate species are also similar. We suggest that investigations of agents which may be of benefit or detriment to the human fetus may be conducted during pregnancy in the rhesus monkey with some assurance that the resultant data may be relevant to events which occur during pregnancy in the human.