Laser Photolysis of Bilirubin

SummaryMonochromatic light was provided by a continuous wave Argon ion laser. We chose to study the in vitro effects of light at 457.9, 465.8, 476.5, 488.0, 501.7, and 514.5 nm as representative of a reasonably evenly spaced samplig across the blue-green spectrum. The in vivo experiments were conducted at 457.9, 476.5, 488.0, and 514.5 nm.In vitro light at 488.0 nm appeared to be more effective than the others studied.After 24 h of irradiance, the in vivo decline in serum bilirubin concentration produced by light at 488.0 nm was one-and-one-half, two, and four times as effective as light at 457.9, 476.5 and 514.5 nm, respectively. By 48 h of exposure, the declines produced by light at 457.9 nm and 488.0 nm are significantly superior to that at 476.5 nm and 514.5 nm, but they do not differ from one another.The photon-induced chemical alteration of bilirubin has been demonstrated by various light sources both in vitro and in vivo. The clinical application of this phenomenon has been widely used as phototherapy in the treatment of neonatal hyperbilirubinemia. Investigations designed to delineate the effective wavelengths have employed broad spectrum light sources and have indicated that irradiance with light of wavelengths of 425-475 nm is maximally effective both in vitro (2,7,8,10, 13,25,31) and in vivo (1,11,17,24,29,33,36). But one study performed in vitro with a relatively narrow spectral source suggested wavelengths at 490 nm might also be efficacious (10). More recently, Lilien et al. (27) have performed experiments that also suggest that wavelengths of light beyond the 425475 nm range are efficacious in vitro.Radiant energies within the 400-500 nm range exhibit potential for inducing damage to tissues. Light from standard fluorescent lamps causes breaks in DNA strands in vitro (3, 35) and increases sister chromatid exchanges and other chromosomal alterations in cultured cells (4,18,21,23,32,35,37). An increased frequency of sister chromatid exchange has been reported in some infants after phototherapy (12). Although we know of no reports regarding any increase in sister chromatid exchange in vivo in response to monochromatic light, the occurrence seems likely; thus, the widespread use of phototherapy has generated concern regarding the potential for long-term mutagenic and carcinogenic effects. Inasmuch as most published data suggest that the offending wavelengths are principally in the ultraviolet range, some recent work has implicated light of wavelengths exceeding 300 nm (9) and, indeed, some alterations appear to occur maximally in response to wavelengths of light between 420-500 nrn (35). Although the magnitude of these latter risks has not been quantitated as they may relate to the clinical setting, it seems desirable to more precisely define the most efficacious wavelengths for the photoalteration of bilirubin that results in its enhanced excretion. This is particularly needed in the design of future phototherapy instruments to be used in the management of neonatal hyperbilirubinemia. Preliminary po...

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“…Since the preparation of this manuscript, Sbrana, et al (34) have confirmed our earlier in vitro observations.…”

Section: Addendumsupporting

confidence: 76%

The in Vitro and in Vivo Photoreactivity of Bilirubin: I. Laser-Defined Wavelength Dependence

1983

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“…In our previous investigation in vitro (12) we reached different results and proved that wavelengths longer than 500 nm are still largely efficient. In this paper we report the results obtained by using green light in the management of hyperbilirubinemia in low-birth-weight infants.…”

Section: Discussionmentioning

confidence: 99%

“…These wavelengths have been found to be equally effective in obtaining u p to a 30% drop in the bilirubin concentration (12).…”

Section: Discussionmentioning

confidence: 99%

Green Light in Phototherapy

et al. 1983

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SummaryPhotodegradation of bilirubin in vivo has been investigated by using green fluorescent sources according to the suggestions obtained in a previous study in vitro. Two groups of 50 jaundiced low-birth-weight infants were exposed to fluorescent light in phototherapy units under similar irradiant conditions. One group was exposed for 24 h to standard green tubes, the other, to daylight lamps. Newborns of the two groups were similar for gestational age, birthweight, and initial bilirubin concentration. A greater decrease in the serum concentration of bilirubin was found in subjects exposed to the green light when compared with infants exposed to daylight lamps.The use of green light is strongly suggested instead of the white, blue, and special blue lamps, because of the real efficiency, power and range of wave lengths.

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“…Despite the widespread use of photother apy for the treatment of neonatal jaundice [1,2,13], debate continues over the most effective wavelength, the intensity of the light, the duration of irradiation and long term biological effects [25,29], Until recent ly, it was assumed that photodegradation of bilirubin was responsible for the decline in scrum bilirubin during phototherapy [9], It has now become apparent that several pho tochemical reactions of bilirubin, i.e. geo metric [10] and structural photoisomeriza tion as shown in figure 1 [11, 12, 16-18.…”

Section: Introductionmentioning

confidence: 99%

Wavelength Dependence of the Geometric and Structural Photoisomerization of Bilirubin Bound to Human Serum Albumin

Itoh¹,

Onishi²,

Isobe³

et al. 1987

Neonatology

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The two quantitatively important photoisomers in bilirubin metabolism during phototherapy are (ZE)-bilirubin and (EZ)-cyclobilirubin. We describe in vitro studies on the wavelength dependence for the geometric (Δ⁴Z, Δ¹⁵Z → Δ⁴Z, Δ¹⁵E) and structural (endovinyl cyclization) photoisomerization of bilirubin bound to human serum albumin by a high performance liquid chromatography method. For the geometric photoisomerization from (ZZ)-bilirubin to (ZE)-bilirubin, the most effective wavelength in vitro was 410 nm. For the structural photoisomerization, green light at 510 nm is the most efficient for causing cyclization of (ZZ)-bilirubin to (EZ)-cyclobilirubin via (EZ)-bilirubin and this may depend on a larger cross-section of (EZ)-bilirubin than (ZZ)-bilirubin in this spectral region and/or on a larger quantum yield for cyclization than geometric photoisomerization.

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Laser Photolysis of Bilirubin

Cited by 17 publications

References 9 publications

The in Vitro and in Vivo Photoreactivity of Bilirubin: I. Laser-Defined Wavelength Dependence

The in Vitro and in Vivo Photoreactivity of Bilirubin: I. Laser-Defined Wavelength Dependence

Green Light in Phototherapy

Wavelength Dependence of the Geometric and Structural Photoisomerization of Bilirubin Bound to Human Serum Albumin

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