Neonatal period

Fatal hereditary disorder that typically presents in the neonatal period. Clinical features include an array of hepatic, renal and neurological dysfunctions. Patients with Zellweger syndrome rarely survive the first year of life. The disease is caused by mutations in the Pex proteins leading to an defective import of peroxisomal matrix proteins and consequently to a loss of most peroxisomal metabolic pathways. 

The severe X-linked form of centronuclear myopathy is often associated with reduced fetal movement and hydramnios, and may be fatal in the neonatal period due to respiratory failure. Children may survive for several years but often only with assisted ventilation. In only a few reported cases has the condition allowed any form of active life. Female relatives may show a carrier state characterized by the presence of some small myotubelike type 1 fibers in an otherwise normal muscle fiber population. 

Vieira 1, Sonnier M, Cresteil T. 1996. Developmental expression of CYP2E1 in the human liver Hypermethylation control of gene expression during the neonatal period. Eur J Biochem 238 476-483. 

Eye movements were noted to be deviant in 25 percent of the infants during the neonatal period. Nystagmus and darting eye movements were seen. Also, a glazed stare associated with total body stillness was frequently seen during the first 6 weeks. 

The classification listed in Table 1 will be utilized throughout this chapter. Caution must be exercised when referring to observations in the neonatal period, however, since premature and/or very low birth weight neonates often have drug responses and disposition significantly different from those of full-term neonates. These differences will be clearly identified in the text. 

Drugs absorbed by active transport mechanisms appear to have a delayed rate, but not extent of absorption, in the neonatal period [20]. The absorption of vitamin K depends, to some extent, on the development of intestinal flora. 

The renal excretion of drugs depends on glomerular filtration, tubular secretion, and tubular absorption. A twofold increase in glomerular filtration occurs in the first 14 days of life [36], The glomerular filtration rate continues to increase rapidly in the neonatal period and reaches a rate of about 86 mL/min per 1.73 m2 by 3 months of age. Children 3-13 years of age have an average clearance of 134 mL/min per 1.73 m2 [37]. Tubular secretion approaches adult values between 2 and 6 months [11], There is more variability observed in maturation of tubular reabsorption capacity. This is likely linked to fluctuations in urinary pH in the neonatal period [38],... 

Transformed cells expressing tumour-specific surface antigens that closely resemble normal surface antigens may not induce an immune response. Furthermore, some tumour antigens, although not usually expressed in adults, were expressed previously during the neonatal period (i.e. just after birth) and are thus believed by the immune cells to be self . 

Medina, J. M. The role of lactate as an energy substrate for the brain during the early neonatal period. Biol. Neonate 48 237-244,1985. 

An aminoaciduria usually results from the congenital absence of an enzyme needed for metabolism of an amino acid. Aminoacidopathies typically involve an inherited deficiency of an enzyme that is important for the metabolism of a particular amino acid (Table 40-1). The concentration of that amino acid and its metabolites consequently rise sharply in blood, urine and body tissues, including the brain. When the enzymatic deficiency is nearly complete, the onset of disease tends to occur in infancy, even in the neonatal period. Partial enzyme deficiencies may not become apparent until later in life [1,2]. 

Patients who survive the neonatal period can be maintained with a low-protein diet and sodium benzoate. A useful therapeutic adjunct for citrullinemia and argininosuccinic aciduria is dietary arginine supplementation, which enhances the ability to eliminate nitrogen as either citrulline or argininosuccinate. Maintaining normal arginine levels also facilitates protein synthesis. 

The role of fatty acids as oxidizable fuels for brain metabolism is negligible, but ketone bodies, derived from fatty acid oxidation, can be utilized, particularly in the neonatal period. Diseases of carbohydrate and fatty acid metabolism may affect the brain directly or indirectly [1,10]. 

Defects of substrate utilization. Pyruvate dehydrogenase (PDH) deficiency can cause alterations of pyruvate metabolism, as can defects of pyruvate carboxylase, as discussed earlier. Over 200 patients have been described with a disturbance of the PDH complex (PDHC) [15,16]. The clinical picture includes several phenotypes ranging from a severe, devastating metabolic disease in the neonatal period to a benign, recurrent syndrome in older children. There is considerable overlap clinically and biochemically with other disorders (see below). 

Glutaric aciduria type II, which is a defect of P-oxida-tion, may affect muscle exclusively or in conjunction with other tissues. Glutaric aciduria type II, also termed multiple acyl-CoA dehydrogenase deficiency (Fig. 42-2), usually causes respiratory distress, hypoglycemia, hyperammonemia, systemic carnitine deficiency, nonketotic metabolic acidosis in the neonatal period and death within the first week. A few patients with onset in childhood or adult life showed lipid-storage myopathy, with weakness or premature fatigue [4]. Short-chain acyl-CoA deficiency (Fig. 42-2) was described in one woman with proximal limb weakness and exercise intolerance. Muscle biopsy showed marked accumulation of lipid droplets. Although... 

Talamantes, F. and H. Jang. 1977. Effects of chlordane isomers administered to female mice during the neonatal period. Jour. Toxicol. Environ. Health 3 713-720. 

Sensitivity of the immune system to Pb appears to differ across life stages, and studies in rodents suggest that the gestational and neonatal periods are the most sensitive. Compared to adults, the increased dose sensitivity of the embryo-fetus would appear to fall in the range of 3-12X depending upon the immune endpoint considered. Recent studies have suggested that exposure of embryos to Pb producing neonatal BLLs below 10 pg/dL can also produce later-life immunotoxicity (Table 12.2). Furthermore,... 

Tellez R, Chacon PM, Crump KS, Blount BC, Gibbs JP (2005) Chronic environmental exposure to perchlorate through drinking water and thyroid function during pregnancy and the neonatal period. Thyroid 15 963-975... 

The US daily allowances-The US daily allowances for vitamin K have not been officially established, but have been estimated to be 10 to 20 meg for infants, 15 to 100 meg for children and adolescents, and 70 to 140 meg for adults. Usually, dietary vitamin K will satisfy these requirements, except during the first 5 to 8 days of the neonatal period. 

Diagnosis of medium-chain acyl-coenzyme A dehydrogenase deficiency in the neonatal period by measurement of medium-chain fatty acids in plasma and filter paper blood samples. 

Neonatal period The first 4 weeks after birth. [NIH]... 

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