Neonatal jaundice, phototherapy

The forms of phototherapy in common use include (i) the phototherapy of jaundice (neonatal hyperbilirubinemia) in the newborn, and especially in the prematurely born 5 (ii) the treatment of psoriasis using light in the UV-A range (320 100 nm) and an administered photosensitizer, such as 8-methoxypsoralen 6 (iii) the treatment of the wet form of age-related macular degeneration with a photosensitizer such as a benzoporphyrin derivative (VISUDYNE ), and a laser light source 7 and (iv) the treatment of certain cancers with a photosensitizer such as a porphyrin derivative, and red light.8... 

Outline the importance the photochemistry of C=C bonds in the phototherapy of infants with neonatal jaundice, the process of vision and the effects of ultraviolet radiation on DNA. 

Phototherapy is the generic term covering therapies which use light either with or without a sensitiser. Those that do not require a sensitiser use the natural chromophores within the tissue to perform this function e.g. treatment of vitamin D deficiency in rickets, and neonatal jaundice). Those that do use an added sensitiser include photochemotherapy (largely psoriasis and skin disorders) and photodynamic therapy (currently mainly cancer). Photodynamic therapy is differentiated from photochemotherapy by its additional requirement for the presence of oxygen at molecular or ambient levels.In this text we will deal only with photodynamic therapy since, at the present time, this is the main driving force in phototherapy. ° ... 

Special illuminating conditions need to be considered during the blue-lamp phototherapy for neonatal jaundice (hyperbilirubinemia). In practice, the neonate is placed under a blue fluorescent lamp having a at about 450 nm, at an irradiance level between 4 and 6 pW/cm. This procedure is very effective in decreasing serum bilirubin concentrations. The high irradiance levels used in phototherapy may also enhance the degradation of drugs in concurrent use. 

Photoprocesses in biliverdin dimethyl ester in ethanol have been studied by laser-induced optoacoustic spectroscopy." The picosecond kinetics of excited-state relaxation of this ester have also been reported." " Isophorcarubin is a conformationally restricted and highly fluorescent bilirubin." " The phototherapy for neonatal jaundice has stimulated investigations of configurational isomers of bilirubin" and of stereospecific and regioselective photoisomerization of bilirubin." ... 

Treatment of neonatal jaundice is usually by phototherapy. A decrease in bilirubin production in the neonatal period can also be achieved by inhibiting the rate-limiting enzyme of bilimbin formation from heme, namely, the heme oxygenase. A potent competitive inhibitor of heme oxygenase is the synthetic heme analogue tin (Sn" +) protoporphyrin. When administered parenterally, the tin protoporphyrin safely decreases bilimbin formation. Exchange transfusions also rapidly decrease plasma bilimbin levels. 

Bile pigments, stereochemistry and photochemistry of 83AG670. Molecular mechanisms of neonatal jaundice phototherapy 84ACR417. Pyrrole pigments from seaweed 81 MI 13. 

McDonagh. A. F Palma, L. A. (1982a). Phototherapy for neonatal jaundice, configurational isomers of bilirubin, J. Am. Chem. Soc., 104 6865. 

Lucey, J.F. (1970). Phototherapy of jaundice 1969 (1970). Birth Defects Orig. Artie. Sen 6 (2) 63-70 Lucey, J. (1972). Neonatal phototherapy uses, problems and questions. Semin. Hematol. 9 (2) 127-135... 

Rozdilsky, B. and Olszewski, J. (1961). Experimental study of the toxicity of bihmbin in newborn animals. J. Neuropathol. Exp. Neurol. 20 193-208 Salih, F.M. (2001). Can sunlight replace phototherapy units in the treatment of neonatal jaundice ... 

Schutta, H.S. and Johnson, L. (1971). Fine structure observations on acute bilirubin encephalopathy in Gunn rats induced by sulfadimethoxine. Lab. Invest. 24 82-96 Siegfied, E.C., Stone, M.S., Madison, K.C. (1992). Ultraviolet light burn a cutaneous complication of visible light phototherapy of neonatal jaundice. Pediatr. Dermatol. 9 (3) 278-282 Tenhunen, R., Marver, H.S., and Schmid, R. (1968). The enzymatic conversion of heme to bilimbin by microsomal heme oxygenase. Proc. Natl. Acad. Sci. USA. 61 748-755... 

Neonatal jaundice occurs in a newborn baby due to deposition of yellow pigment bilirubin in brain cells and skin because of abnormal liver function. It occurs due to rapid breakdown of hemoglobin to bUimbin in red blood cells compared to breakdown of bilimbin in liver. Untreated baby suffers from the damage of central nervous system. For treatment of this disease, the affected baby is subjected to phototherapy with visible bluish-green light. 

The complex formation of bilirubin with human serum albumin was investigated by Sinclair et al. 72) using 347 nm ruby laser flash photolysis technique. A high bilirubin level is found in new bom babies who suffer from jaundice (neonatal hyperbilirubinemia)73). Phototherapy has been found to be suitable for lowering the bilirubin level. In order to understand the mechanism of the phototherapy, investigation into the photophysics of bilirubin is essential. It is strongly bound to human serum albumin, lipids and cell membranes. 

Zammarchi, E., La Rosa, S., Pierro, U., Lenzi, G., Bartolini, R, and Falomi, S., Free tryptophan decrease in jaundiced newborn infants during phototherapy, Biol. Neonate, 55, 224, 1989. 

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