| Abstract: |
Discusses the short- and long-term effects of overnutrition, acute protein-calorie malnutrition, famine and chronic undernutrition on human growth and maturation during the prenatal and postnatal period of development. Suggests that there is a synergistic relationship between malnutrition and infection, whereby malnutrition predisposes the organism to infections either through low production of immunoglobulins or inhibition of the cell-mediated immune response. \bAcute protein-caloric malnutrition\b There are two major clinical entities: marasmus and kwashiorkor \uMarasmus\u Characterized by a chronic summetrical reduction of both proteins and calories. It origin is traceable to the prenatal period and is usually manifested during the first year of postnatal life. Children are retarded in all areas of physical growth and exhibit a marked reduction of body tissue such as muscle and subcutaneous fat. \uKwashiorkor\u Characterized by an acute reduction of proteins in the presence of relatively adequate calorie intake derived from foods rich in carbohydrates but poor in proteins. Disease is manifested after the first or second year of postnatal life, and is characterized by reduction in stature, weight and body composition. The term marasmus-kwashiorkor us used to designate conditions where signs of both syndromes are present. The development of the vrain follows three phases of growth: 1) hyperplasia - an increase in brain, weight, protein content, and DNA 2) hyperplasia + hypertrophy - increase in DNA content falls behind the increase in brain protein content and weight 3) hypertrophy - no additional increase in DNA content, but the existing cells enlarge in size and result in an increase in net protein synthesis The brain growth spurt is by far the most vulnerable period for the occurrence of both quantitative and qualitative physical distortion. This is because the myelinization process and the synaptic arborization occurs during the first year and therefore shortage of nutrients can have far reaching cosequences to brain growth. The brain-growth spurt in humans begins during the last trimester of the prenatal period to the end of the first year. Conversely, the effects of malnutrition on brain growth nd structural disortions after the second year would not be permanent.
|
