Formation of photoproducts and cytotoxicity of bilirubin irradiated with turquoise and blue phototherapy light

AIM: To compare a new turquoise ("green") fluorescent phototherapy lamp (490 nm) with a conventional blue phototherapy lamp (450 nm) with respect to cytotoxicity and photochemical effects of bilirubin. METHODS: Mouse lymphoma cells (L5178Y-R) in the presence of bilirubin solutions were exposed to phototherapy light. Occurrence of necrosis and apoptosis, reduction of mitotic index and inhibited cell growth was assayed by appropriate methods. The presence of bilirubin and its photoisomers was measured by high-pressure liquid chromatography analysis and absorption spectroscopy. RESULTS: At constant and equal light irradiances, the cytotoxic effects in the presence of bilirubin bound to human serum albumin showed that the green lamp caused significantly less necrosis (n = 4, p < 0.05) and less inhibition of cell multiplication (n = 3, p < 0.05) than the blue lamp. A slightly lower apoptotic fraction, although not statistically significant, was observed in cells exposed to the blue lamp. Photo-oxidation of bilirubin was more prominent with blue light irradiation. The photoequilibria between geometric isomers of bilirubin were different for the two lamps; more geometric photoisomers were formed by blue irradiation (n = 6, p < 0.05). The amounts of the most water-soluble isomers (presumably mainly lumirubin) were rather similar for the two lamps. CONCLUSION: The two lamps were similar in the formation of therapeutically relevant photoproducts, but the blue lamp showed potential in forming more photo-oxidation products and in causing more severe cellular damage in the presence of bilirubin.     

Increased osmotic fragility of erythrocytes in chronically jaundiced rats after phototherapy

Littermate homozygous (jj) and heterozygous (Jj) Gunn rats, were irradiated with blue fluorescent light for 18 hours continuously. The incident irradiance was 1.5 mWatts/cm2 in the 420--480 nm band pass. The influence of the irradiance on circulating erthrocytes was studied by testing their osmotic fragility before and after the irradiance. The non-jaundiced, Jj, animals did not exhibit any increase in the osmotic fragility of their erythrocytes. The osmotic fragility of the erythrocytes from jaundiced, jj, animals was the same as the Jj animals prior irradiance. However, the fragility of the erythrocytes from the jj animals was significantly increased after the 18 hours of irradiance. The results indicated that the photodynamic action of bilirubin may be present in vivo.     

Fibreoptic phototherapy in the management of jaundice in low birthweight neonates

A fibreoptic phototherapy device has been compared with conventional white and special blue fluorescent phototherapy lamps to evaluate its efficacy in lowering serum bilirubin levels in low-birthweight neonates. Fibreoptic phototherapy was found to be as effective 21s white light and less effective than blue light, as assessed by (i) the bilirubin concentration after 24 h of phototherapy and at the end of phototherapy, (ii) the duration of phototherapy, (iii) the percentage daily decline rate and (iv) the overall percentage decline rate ( p < 0.05). There were no failures of phototherapy and the need for re-exposure was low (4.7% of the total sample), with no difference between groups. The fibreoptic approach represents a promising way to aggregate synergically the most recent optical technologies and develop a modern, efficient and caring phototherapy system for low-birthweight infants.     

Cells, bilirubin and light: formation of bilirubin photoproducts and cellular damage at defined wavelengths

Christensen T, Kinn G, Granli T, Amundsen I. Cells, bilirubin and light: formation of bilirubin photoproducts and cellular damage at defined wavelengths. Acta Paediatr 1994;83:7–12. Stockholm. ISSN 0803–5253
Cultured cells from one human and one murine cell line were treated with bilirubin and irradiated with visible light of different wavelengths, either from phototherapy lamps or from a Xenon/Mercury lamp equipped with a monochromator. Bilirubin bound to human serum albumin was also irradiated with light. After irradiation, the bilirubin and its photoisomers were extracted and analysed with High Pressure Liquid Chromatography. The formation of single strand breaks in the DNA of treated cells was studied using a fluorescence marker. Cytotoxicity in the mouse skin cell line was measured by loss of the ability to form visible colonies in vitro. Green light exposure favours the production of lumirubin, while blue light causes more DNA damage and cytotoxicity. Green light may be more efficient and safer than shorter wavelength exposure when treating jaundiced newborns with phototherapy.     

Effects of albumin infusion therapy on total and unbound bilirubin values in term infants with intensive phototherapy

BACKGROUND: The purpose of the present study was to evaluate the effect of intravenous albumin administration on the serum total and unbound bilirubin values in term non-hemolytic hyperbilirubinemic neonates during intensive phototherapy. METHODS: Fifty-eight infants (gestational age 39.4 +/- 1.4 weeks; birth weight 3,245 +/- 435 g) were given phototherapy with similar light energy. Twenty infants (control group) received only phototherapy, while 38 others (albumin-treated group) were also given human albumin at 1 g/kg bodyweight, i.v., during the first 2 h of phototherapy. RESULTS: When comparing changes in total and unbound bilirubin values 0, 2, 6 and 24 h after entering the study between the albumin-treated group and the control group, there was a significant reduction in the serum unbound bilirubin values at the end of albumin treatment and at 6 and 24 h. However, there was no significant reduction in total serum bilirubin values during the study period. In the albumin-treated group, the mean serum unbound bilirubin reduction from the baseline level at the end of albumin treatment and at 6 and 24 h was 0.40 +/- 0.19, 0.41 +/- 0.20 and 0.43 +/- 0.20 microg/dL, respectively. CONCLUSIONS: The results suggest that albumin priming may be effective for an immediate reduction in serum unbound bilirubin values, the fraction that is potentially neurotoxic.     

Randomized controlled trial of oral versus intravenous fluid supplementation on serum bilirubin level during phototherapy of term infants with severe hyperbilirubinaemia

OBJECTIVE: To compare the rates of decrease in serum bilirubin levels in severely jaundiced healthy term infants given oral or intravenous fluid supplementation during phototherapy. METHODS: A randomized controlled study was carried out in the neonatal intensive care unit (NICU) of Hospital Universiti Kebangsaan Malaysia over a 12-month period. Fifty-four healthy term infants with severe hyperbilirubinemia were randomized to receive either solely enteral feeds (n = 27) or both enteral and intravenous (n = 27) fluid during phototherapy. RESULTS: There were no significant differences in the mean birthweight, mean gestational age, ethnic distribution, gender distribution, modes of delivery and types of feeding between the two groups. Similarly, there was no significant difference in the mean indirect serum bilirubin (iSB) level at the time of admission to the NICU between the enteral (359 +/- 69 micromol/L [mean +/- SD]) and intravenous group (372 +/- 59 micromol/L; P = 0.4). The mean rates of decrease in iSB during the first 4 h of phototherapy were also not significantly different between the enteral group (10.4 +/- 4.9 micromol/L per h) and intravenous group (11.2 +/- 7.4 micromol/L per h; P = 0.6). There was no significant difference in the proportion of infants requiring exchange transfusion (P = 0.3) nor in the median duration of hospitalization (P = 0.7) between the two groups. No infant developed vomiting or abdominal distension during the study period. CONCLUSION: Severely jaundiced healthy term infants had similar rates of decrease in iSB levels during the first 4 h of intensive phototherapy, irrespective of whether they received oral or intravenous fluid supplementation. However, using the oral route avoided the need for intravenous cannulae and their attendant complications.     

Comparison of the efficacy of conventional special blue light phototherapy and fiberoptic phototherapy in the management of neonatal hyperbilirubinaemia

The efficacy and usefulness of two types of phototherapy differing in the source, wavelength and irradiance of the light, conventional phototherapy consisting of special blue light and fiberoptic phototherapy, were compared in a relatively larger series of term newborns with non-haemolytic and more significant hyperbilirubinaemia than those in previous studies. In total, 108 newborns were allocated sequentially to receive either conventional phototherapy consisting of five special blue lamps or fiberoptic phototherapy. The average spectral irradiance measured at the skin surface level of newborns during the study period was significantly greater in the conventional phototherapy group. The special blue lamp of the conventional phototherapy unit had an emission spectrum almost identical to the bilirubin absorption spectrum, whereas the tungsten-halogen lamp of the fiberoptic phototherapy had a broad emission through the blue and green wavelengths (mainly in the green spectrum). Phototherapy was more effective in the conventional phototherapy group; the duration of exposure to phototherapy (h) was significantly shorter, and the overall bilirubin decline rate (as micromol/l/h and %/h) was significantly greater in the conventional phototherapy group. According to the nursing personnel, fiberoptic phototherapy was more comfortable than the conventional phototherapy frame because of the easier accessibility and handling of the infants during phototherapy. They complained of giddiness, nausea, glare, temporary blurring of vision and difficulty in detecting the skin colour changes of newborns with the blue light of the conventional phototherapy unit. Conventional phototherapy consisting of special blue fluorescent lamps with approximately twofold higher irradiance and an emission spectrum almost identical to the bilirubin absorption spectrum is preferable to fiberoptic phototherapy in the standard treatment of term newborns with non-haemolytic hyperbilirubinaemia.     

When should phototherapy be stopped? A pilot study comparing two targets of serum bilirubin concentration

Objective: The objective of this study was to compare the outcome of two groups of jaundiced newborns randomized to one of the two targets of total serum bilirubin (TSB) for phototherapy discontinuation.
Design: Infants treated with phototherapy were assigned to two groups: in the 'high-threshold' group, phototherapy was interrupted when TSB decreased to ≥1 mg/dL (17 μmol/L) below the limit requiring phototherapy and in the 'low-threshold' group when TSB decreased to ≥3 mg/dL (51 μmol/L) below the same limit.
Results: Fifty-two infants were enrolled, 25 in the high- and 27 in the low-threshold group. Phototherapy duration was significantly shorter in the high- than in the low-threshold group (22.3 ± 13 vs. 27.6 ± 12 h, respectively, p = 0.03). Length of hospital stay was 84±30 h in the high- and 94 ± 24 h in the low-threshold group (p = 0.05). Additional phototherapy was required in 20% of the high- versus 18% of the low-threshold group (p = 0.58). In the presence of haemolysis or G6PD deficiency, 28% of the infants required re-phototherapy and 8.3% when such factors were absent (p = 0.06).
Conclusion: Phototherapy duration may be shortened by using higher TSB limits for interruption. When hyperbilirubinaemia is accompanied by risk factors, the infants should be followed for longer periods, since some of them will need re-phototherapy.     

Acute management of extreme neonatal jaundice–––the potential benefits of intensified phototherapy and interruption of enterohepatic bilirubin circulation

Abstract Increasing numbers of neonates are being admitted to hospital because of extreme jaundice. Phototherapy should be very effective in such infants, because the efficacy of phototherapy is proportional to the concentration of bilirubin in the skin. Here, I report on four infants who were admitted for indirect serum bilirubin levels of >500 µmol/1 (>>30mg/dl). In one of them, unrecognized Rhesus immunization was the main cause of hyperbilirubinemia, while in the other three increased enterohepatic circulation of bilirubin was thought to be an important contributory factor. In all four infants phototherapy (11–14 µW/cm²/nm) with whole body exposure plus ad lib feeding with milk were initiated immediately upon admission to the nursery. After 2h serum bilirubin values were reduced by 170–185 µmol/1 (10-11mg/dl) in the first three infants, while in the fourth infant a reduction of 195 µmol/1 (11.3mg/dl) was seen in the 5h interval between the first and second bilirubin measurement. This experience suggests that in some infants with extreme jaundice, intensified phototherapy plus feeding with milk may be very effective in reducing serum bilirubin levels. Even if an exchange transfusion is performed, using this strategy in the waiting period may be beneficial, as both the rapid reduction in serum bilirubin levels as well as the conversion of significant amounts of bilirubin into water-soluble isomers may reduce the risk of neurotoxicity.     

Absence of bilirubin binding competitors during phototherapy for neonatal jaundice

Bilirubin-albumin binding was quantitated (peroxidase method) before, during, and after phototherapy in 21 jaundiced infants. Binding was analyzed at two different serum dilutions (1: 1.8 and 1 : 57) to determine whether binding competitors are present during phototherapy. No significant changes in binding were found at either dilution during phototherapy, regardless of birthweight, gestational age, or illness. Serum binding of bilirubin does not appear to be altered during phototherapy.     

Cholestatic pruritus: effect of phototherapy on pruritus and excretion of bile acids in urine

Pruritus associated with hepatic cholestasis may cause significant morbidity and its correlation to retention of bile acids in skin is inconsistent. Available treatment modalities are only partially effective and can have several adverse effects. Phototherapy has recently been reported to improve cholestatic pruritus, but has not been evaluated previously in children, and its mechanism is still unclear. We report the outcome of multiple Daylite phototherapy treatments over two years in a seven-year-old child with chronic hepatic cholestasis that was resistant to other therapeutic modalities. Bile acid levels in urine were used as markers of effectiveness in parallel with clinical response. Night phototherapy alone increased the bile acids/creatinine ratio in urine from 1.54 & 0.04 pmol/mg at baseline to 2.07 ± 0.29 pmol/mg. Continuous phototherapy combined with night diuresis raised the ratio further to 2.28 ± 0.55 μmol/mg. Night diuresis alone had no effect. Continuous phototherapy combined with night diuresis raised the bile acids/creatinine ratio by 44% on the first day and by 61 % on the second day, but declined to baseline on the third day of treatment. A marked clinical improvement was noted for one week following two days of phototherapy. This schedule has been repeatedly effective in improving pruritus for approximately one year and may be due to the ability of phototherapy to enhance excretion of bile acids and other possible pruritogens into urine.     

胆红素对新生儿脐血单核细胞凋亡的影响

目的 探讨胆红素对新生儿脐血单核细胞(CBMC)凋亡的影响.方法 采用纤维连接蛋白结合法分离新生儿CBMC.经含有不同浓度胆红素(6 mG/dl、9 mg/dl、12.9 mg/dl和18 mg/dl)的牛血清白蛋白溶液孵育1 h,再给予脂多糖(LPS,1μg/m1)刺激48 h,收集细胞.采用TUNEL法检测细胞的凋亡率.结果 LPS和低浓度(6 mg/dl)胆红素单独作用对CBMC的凋亡率均无影响.低浓度胆红素(6 mg/dl)与LPS共同作用不升高CBMC的凋亡率;较高浓度和高浓度胆红素(9 mg/dl、12.9 mg/dl、18 mg/dl)与LPS共同作用可升高CBMC的凋亡率,且这种作用随胆红索浓度的升高而增加.结论 较高浓度和高浓度胆红素可以升高CBMC的凋亡率,此种抑制作用可能与胆红素引起细胞膜破坏、Ca2+内流增多、线粒体功能障碍有关.     

Effect of phototherapy on thyroid stimulatory hormone and free thyroxine levels

Objective : To study the effect of phototherapy for neonatal hyperbilirubinaemia on thyroid function as neonatal thyroid screening is sometimes performed during exposure to phototherapy. Methodology : Infants with non-haemolytic hyperbilirubinaemia were sequentially allocated to fibre-optic phototherapy, conventional daylight phototherapy, or a combination of both. Bilirubin concentration was monitored 12 hourly by capillary blood sampling; venous blood was sampled for thyroid stimulating hormone (TSH) and free thyroxine (fT₄) determinations, at start of exposure, at 24 h, end of exposure and 1 day later. Comparable unexposed infants served as controls. Results : All 123 study infants and 25 controls remained well during the study. Bilirubin levels declined during phototherapy, being most rapid in the combination group. The TSH and fT₄ values at start of exposure were 3.86 ± 0.41 mU/L (mean ± SEM) and 33.20 ± 1.16 pmol/L, respectively, in the fibre-optic group, 3.62 ± 0.38 mU/L and 37.22 ± 1.76 pmol/L in the daylight group, and 4.40 ± 0.48 mU/L and 29.91 ± 1.13 pmol/L in the combined group, compared with 5.77 ± 0.40 mU/L and 34.46 ± 1.68 pmol/L in the control group. The TSH and fT₄ values declined with increasing age in the phototherapy and control groups with end of exposure values of 2.90 ± 0.28mU/L and 27.71 ± 0.71 pmol/L, 2.77 ± 0.31 mU/L and 33.52 ± 1.22pmol/L, and 3.44 ± 0.30 mU/L and 27.54 ± 0.88 pmol/L, respectively, compared with 4.21 ± 0.61 mU/L and 27.19 ± 2.33 pmol/L (at 72 h) in the control group. The pattern of TSH and fT₄ decline in the exposed and control groups was similar, being related to increasing age. Conclusions : The validity of neonatal thyroid screening is not affected by fibre-optic or conventional phototherapy or by both combined.     

新生儿高胆红素血症光疗不良反应研究进展

光疗作为一种有效的新生儿高胆红素血症的治疗手段,在临床得到广泛应用。最近研究显示,新生儿期光疗可通过氧化应激、DNA损伤等机制增加极低出生体质量儿病死率,并与儿童期肿瘤、黑色素痣、过敏性疾病及癫痫等有相关联系。因此需要进一步探索和优化光疗光源设备、改变光疗方式等,减少光疗的不良反应。文章就新生儿高胆红素血症光疗的不良反应研究进展进行综述。     

强光疗治疗新生儿高胆红素血症的疗效及安全性

目的 探讨采用强光疗治疗新生儿高胆红素血症的疗效及安全性。方法 对144 例新生儿高胆红素血症患儿进行前瞻性随机分组,其中强光疗组和传统光疗组各72 例,对两组疗效及并发症等情况进行比较。结果 光疗后12 h 内强光疗组患儿血总胆红素水平明显低于传统光疗组(P<0.05),且胆红素下降幅度明显高于传统光疗组(P<0.05)。强光疗组患儿总光疗时间明显短于传统光疗组(P<0.05)。两组患儿光疗后发热、腹泻、皮疹、低钙血症发生率及光疗后血钙水平和血红蛋白下降水平等比较差异均无统计学意义。结论 强光疗在光疗开始初期可迅速有效降低高胆红素血症患儿血中胆红素水平,缩短总光疗时间,且不增加不良反应的发生率,是一种优于传统光疗的治疗措施。     

胆红素对大鼠海马CA3区长时程增强影响的研究

目的研究胆红素的神经系统毒性。方法用电生理方法观察了急性注射胆红素对大鼠海马ＣＡ３区长时程增强的影响情况。结果对照组给予高频刺激后第１、３、５、１０、１５、３０、４５、６０、９０和１２０分钟群体峰电位变化率显著增加（ＤｕｎｎｅｔＴ临界值为２．８０９，Ｐ＜０．０５），而两个实验组的群体峰电位变化率在刺激前后均无明显改变（Ｐ＞０．０５）；高频刺激后第３、５、１０、４５、６０和１２０分钟，对照组群体峰电位变化率较当时的两个实验组明显增大（Ｐ＜０．０５），在其他时刻则未发现明显改变，未发现两个实验组之间的群体峰电位变化率存在差别。结论胆红素能抑制长时程增强的形成     

光疗对于黄疸新生儿肠道菌群及耐药基因的影响分析

目的 分析接受光疗的黄疸新生儿肠道菌群及其耐药基因的变化,探讨其临床意义。方法 通过宏基因组测序的方法,分析黄疸新生儿接受光疗后肠道菌群及其携带耐药基因的变化。结果 光疗24 h及48 h后肠道菌群丰度的α和β多样性差异无统计学意义(P>0.05)。菌种水平上,个别菌种相对丰度增多,包括梭状芽孢杆菌、粪肠球菌、嗜热链球菌(P<0.01)。新生儿肠道菌群携带大量耐药基因,共242种,主要是四环素类、β-内酰胺类、大环内酯类、磺胺类、氨基糖苷类耐药基因,同时还发现了较多大肠杆菌耐药基因。随着光疗时间延长,β-内酰胺类耐药基因(CTX-M-14)、氨基糖苷类耐药基因(aadA2)、四环素类耐药基因[tet(59)]、外排泵基因(efmA)、喹诺酮类耐药基因(QnrS2)、碳青霉烯酶基因(OXA-347)和磺胺类耐药基因(dfrA1)丰度发生显著增加;金黄色葡萄球菌调节耐药基因(mgrA)丰度在光疗后降低(P<0.05)。光疗48 h后,肠道菌群菌种水平的丰度与耐药基因呈显著正相关的有：梭状芽孢杆菌与氨基糖苷类耐药基因[APH(3’)-Ia],单形拟杆菌与β-内酰胺类耐药基因...     

Effect of phototherapy on blood endothelin and nitric oxide levels: clinical significance in preterm infants

Background  Phototherapy may have an adverse effect on the hemodynamics of preterm infants, and endothelin (ET) and nitric oxide (NO) are both the powerful vasoactive substances. This study was designed to observe the effect of phototherapy on blood levels of ET and NO in preterm infants. Methods  Sixty-four preterm infants with hyperbilirubinemia requiring phototherapy were studied. Among them, 31 patients were born at 32–36 weeks’ gestational age (GA), and 33 patients were ≤32 weeks GA. Control group included 26 full-term infants with hyperbilirubinemia requiring phototherapy. All patients were treated with continuous phototherapy for 24 hours. Blood samples were collected before and after phototherapy. The amount of ET in the blood samples was determined by radioimmunoassay, and NO levels were determined using nitrate reductase. Heart rate, respiratory rate, apnea, and mean arterial blood pressure (MABP) were monitored regularly (defined interval: hourly, 4 hours, etc) during phototherapy. Results  Blood ET levels measured after 24 hours of phototherapy were higher than the pretreatment values, as were blood NO levels measured after 12 hours and 24 hours of phototherapy. Both increases were statistically significant (P<0.05) in the GA≤32 weeks group. In the GA>32 weeks group, blood NO levels measured after 24 hours of phototherapy were higher than the pretreatment values; these changes were also statistically significant (P<0.05). In the GA≤32 weeks group, heart rate increased and the MABP decreased during phototherapy. The changes after 24 hours of phototherapy compared to the pretreatment values were statistically significant. A few episodes of apnea occurred during phototherapy in the GA≤32 weeks group. This was significantly higher than that in the other two groups. Conclusions  Under phototherapy, blood levels of ET and NO were significantly higher in preterm infants, especially in preterm infants of ≤32 weeks GA.     

Effect of melanin, oxyhemoglobin and bilirubin on transcutaneous bilirubinometry

To determine the effect of skin pigments on transcutaneous bilirubinometer readings, we measured the effect of bilirubin, melanin, and oxyhemoglobin solutions on transcutaneous bilirubinometer readings in vitro. Our results showed that the variability of the readings in vitro was related to the instrument's non-linear response to bilirubin and melanin concentration and an inacurate oxyhemoglobin correction factor. These factors should be considered in developing a more accurate non-invasive method of monitoring serum bilirubin concentration.