Infants. 105 factors affecting

Both maternal and infant factors determine the final amount of drug present in the nursing child s body at any particular time. Variations in the daily amount of milk formed within the breast (e.g., changes in blood flow to the breast) as well as alterations in breast mUk pH wUl affect the total amount of drug found in mUk. In addition, composition of the milk will be affected by the maternal diet for example, a high-carbohydrate diet will increase the content of saturated fatty acids in milk. 

Oral nutrient intake requirements for infants have been established from (1) analysis of body composition (2) direct clinical studies on various feeding regimens or (3) analysis of the nutrient content of mature human milk. There are, however, marked differences between intravenous and oral requirements. For example, when determining oral requirements, the various factors affecting nutrient utilization, such as bioavailability and rates of absorption, have to be considered (Fomon et aL, 1977). 

Determine the factors affecting the exposure of infants and toddlers to pesticides and PAHs as well as the relationship between dust exposure and biomarkers. 

Diagnosis and alleviation of the cause, if possible, is of primary importance. Often, however, this is not possible and therapy is used to alleviate the inconvenience and pain of diarrhea. These compounds usually only mask the underlying factors producing the problem. Diarrhea may cause significant dehydration and loss of electrolytes and is a particularly serious problem in infants. Antidiarrheals do not usually prevent the loss of fluids and electrolytes into the large bowel and, although these may prevent frequent defecation, often the serious imbalance of body electrolytes and fluids is not significantly affected. 

Infants with salt-losing crisis and adrenal insufficiency in infancy may have adrenal hypoplasia congenita. This can be of two types recessive, for which the cause has not been defined and which affects mostly the fetal zone, and X-linked, which is caused by mutations in the DAX-1 gene, which (with steroidogenic factor-1) controls definitive zone development and steroidogenesis [71]. GC-MS analysis of patients with the disorder show variant patterns from absence of neonatal A5 steroids, appropriate for the recessive form [81], to extremely low cortisol production and transient 11/Lhy-droxylase deficiency, as evidenced through increased THS excretion (Malunowicz, personal communication). 

Available time to sleep for infants, children, and adults is influenced by a range of environmental and societal factors. In infancy, caretaking practices affect sleep infants sleeping with their mothers have more arousals and less quiet sleep (70), and breast-fed infants wake up more often during the night to nurse (71). Additionally, a small number of researchers have reported that socioeconomic status and other family factors may have an impact on children s sleeping patterns. For example, Sadeh and colleagues (72) assessed the sleep patterns, disruptions, and sleepiness in 140 7-13-year-olds from two-parent,... 

In humans, the conversion of ALA to EPA and DHA is extremely slow, with only about 15% and 5% of ALA converted to EPA and DHA, respectively (Cunnane, 1995). This conversion appears to be affected by a number of dietary factors. For example, a diet rich in linoleic acid has been found to reduce this conversion by as much as 40% (Emken, 1995). In addition, saturated and lruns fatty acids also interfere with ALA desaturation and elongation steps (Ackman and Cunnane, 1992 HouwelingenandHornstra, 1994). DHA can be reconverted back to EPA, although in humans it appears to be a very minor pathway (Brossard et al., 1996). DHA appears to play an important in the brain and retina and was found to be incorporated during the last trimester of pregnancy and the first year of life. Visual acuity was shown to develop much faster in preterm infants fed formulas rich in DHA compared with standard infant formulas low in long chain n-3 fatty acids (Jorgensen et al., 1996). 

The report of a WHO Expert Committee (1) emphasized the need for information on the bioavailability of zinc, since the recommended intake was dependent on this important factor. Although zinc deficiency in humans was initially reported from Iran and Egypt, adverse effects of marginal or low intakes of zinc by infants and children have subsequently been reported from other parts of the world (2). Apparently the zinc intakes in Iran and Egypt were adequate but the bioavailability was adversely affected by the high level of phytate and fibre in the diet (2). The zinc content of the modern diet is decreased by the use of refined... 

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