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1.
Phys Chem Chem Phys ; 21(5): 2365-2371, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30666332

RESUMO

Fluorescent proteins (FPs) have become fundamental tools for live cell imaging. Most FPs currently used are members of the green fluorescent protein super-family, but new fluorophores such as bilin-FPs are being developed and optimized. In particular, the UnaG FP incorporates bilirubin (BR) as a chromophore, enhancing its fluorescence quantum yield by three orders of magnitude relative to that in solution. To investigate the mechanism of this dramatic enhancement and provide a basis for further engineering of UnaG and other tetrapyrrole-based fluorophores, we performed picosecond fluorescence and femtosecond transient absorption measurements of BR bound to UnaG and its N57A site-directed mutant. The dynamics of wt-UnaG, which has a fluorescence QY of 0.51, are largely homogeneous, showing an excited state relaxation of ∼200 ps, and a 2.2 ns excited-state lifetime decay with a kinetic isotope effect (KIE) of 1.1 for D2O vs. H2O buffer. In contrast, for UnaG N57A (fluorescence QY 0.01) the results show a large spectral inhomogeneity with excited state decay timescales of 47 and 200 ps and a KIE of 1.4. The non-radiative deactivation of the excited state is limited by proton transfer. The loss of direct hydrogen bonds to the endo-vinyl dipyrrinone moiety of BR leads to high flexibility and structural heterogeneity of UnaG N57A, as seen in the X-ray crystal structure.


Assuntos
Bilirrubina/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Bilirrubina/química , Bilirrubina/efeitos da radiação , Sítios de Ligação , Fluorescência , Proteínas de Fluorescência Verde/química , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/efeitos da radiação , Ligação de Hidrogênio , Luz , Mutação , Ligação Proteica
2.
J Phys Chem A ; 122(46): 9084-9092, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30383967

RESUMO

The characterization of various intermediates in the ultrafast deactivation of photoexcited ( Z, Z)-bilirubin-IXα was carried out using different computational methods. Various excited states of ( Z, Z)-bilirubin-IXα and their respective vertical excitation energies were calculated using time-dependent density functional theory (TD-DFT) employing the Coulomb-attenuating method (CAM) combined with the B3LYP functional, which is known to predict accurate results on the charge transfer excitation process. Optimized geometries and absorption spectra were determined in chloroform solvent using the polarizable continuum model incorporating the integral equation formalism. The optimized geometries of different conformers of bilirubin ( ZZ, ZE, EZ, and EE) along with their relative energies and vertical excitation energies were obtained. The geometry of the first excited state, S1, for the ZZ conformer was optimized using TD-DFT. The computational study suggests that excited-state intramolecular proton transfer (ESIPT) plays a major role in the deactivation process of ( Z, Z)-bilirubin-IXα on a shorter time scale. The lactam-lactim tautomerism that arises from the ESIPT process gives rise to various intermediates of ( Z, Z)-bilirubin-IXα. The computational results nicely corroborate the experimental findings available in the literature.


Assuntos
Bilirrubina/química , Bilirrubina/efeitos da radiação , Modelos Químicos , Modelos Moleculares , Conformação Molecular , Prótons , Teoria Quântica , Estereoisomerismo
3.
J Photochem Photobiol B ; 185: 50-54, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29864726

RESUMO

As rhesus monkeys exhibit physiological jaundice during the neonatal period, we used rhesus monkey serum to examine changes in bilirubin photoisomers. Bilirubin-rhesus monkey serum solution was irradiated with blue light-emitting diode, and changes in the absorbance and bilirubin fraction were compared with those in bilirubin- human serum albumin (HSA) and bilirubin-rat albumin solutions. The λmax decreased with light irradiation. The mean production rate of cyclobilirubin IXα was 1.98, 199 and 0.76 × 10-2/min in rhesus monkey serum, HSA and rat albumin, respectively. There was no significant difference between rhesus monkey serum and HSA. The (ZE)-bilirubin IXα/(ZZ)-bilirubin IXα ratio was 0.33, 0.45, and 0.10, respectively, differing significantly among the groups. The (EZ)-bilirubin IXα/(ZZ)-bilirubin IXα ratio was 0.020, 0.010, and 0.062, respectively, with no significant difference between rhesus monkey serum and HSA. The production rate of (EZ)-cyclobilirubin XIIIα(= (ZE)-cyclobilirubin XIIIα) was 0.73, 1.60, and 0.51 × 10-2/min, respectively, with differing significantly among the groups. The (EZ)-bilirubin IIIα/(ZZ)-bilirubin IIIα ratio was significantly different among the groups at 0.20, 0.38, and 0.15, respectively. This is the first report demonstrating the photoisomerization of bilirubin in rhesus monkey serum and the animal with the same cyclobilirubin production rate as HSA.Rhesus monkeys may be used as an animal model for neonatal hyperbilirubinemia in humans to evaluate the efficacy of phototherapy.


Assuntos
Bilirrubina/química , Luz , Soro/química , Animais , Bilirrubina/análogos & derivados , Bilirrubina/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Humanos , Isomerismo , Macaca mulatta , Ratos , Albumina Sérica/química , Albumina Sérica Humana/química , Espectrofotometria
5.
Pharmazie ; 70(4): 225-30, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26012251

RESUMO

Degradation of bilirubin in aerobic methanol solution by continuous UV-B irradiation has been investigated in this work. The purpose of this study was to shed more light on bilirubin interaction with the UV-B component of natural sunlight, since bilirubin is a very efficient UV-B absorber located in the skin epidermis. The degradation products have been detected and studied by a combined method of Ultra High Performance Liquid Chromatography-Electrospray Ionization Mass Spectrometry (UHPLC-ESI-MS). Bilirubin, a toxic pigment which itself is a product of (hemoglobin) degradation in organisms, undergoes its own degradation under aerobic conditions of UV-B continuous irradiation (e.g. photooxidation) that can be partly self-sensitized. Two dipyrrolic structures have been identified as a result of the bilirubin degradation, not including the bilirubin derivative biliverdin whose increase in the irradiated system is synchronous with a time dynamics of bilirubin degradation. It appears that one of dipyrrolic products originates directly from bilirubin and biliverdin molecules, while the other one is probably connected to bilirubin self-sensitized degradation. The precursor role of biliverdin in the degradation process--related to the detected dipyrroles--has not been confirmed.


Assuntos
Bilirrubina/química , Bilirrubina/efeitos da radiação , Metanol/química , Biliverdina/química , Biliverdina/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Solventes , Espectrometria de Massas por Ionização por Electrospray , Estereoisomerismo , Raios Ultravioleta
6.
Ann Clin Biochem ; 49(Pt 6): 595-9, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23086977

RESUMO

BACKGROUND: Measured unbound bilirubin concentration is influenced by bilirubin photoisomers. Bilirubin photoisomers are produced even with only a slight light exposure, and clinical samples are inevitably exposed to light. The objective of the study was to evaluate the influence of bilirubin photoisomers on the measurement of unbound bilirubin using serum of jaundiced neonates during blue light phototherapy. METHODS: Five neonates treated with phototherapy for hyperbilirubinaemia were enrolled. The samples were taken 12 h after initiation of phototherapy. Samples were processed by irradiation with blue light, by indoor ceiling light, by both blue light and indoor ceiling light or shaded. Bilirubin subfractions, total bilirubin and unbound bilirubin were measured. RESULTS: Compared with the non-irradiated samples, the (EZ)-cyclobilirubin concentration and (ZE)-bilirubin/(ZZ)-bilirubin ratio significantly increased in the blue light-irradiated samples, the (ZE)-bilirubin/(ZZ)-bilirubin ratio significantly increased in the indoor ceiling light-irradiated samples, and the (EZ)-cyclobilirubin, (EZ)-bilirubin and (ZE)-bilirubin/(ZZ)-bilirubin ratio significantly increased in the samples irradiated with both lights. No change was noted in unbound bilirubin in any group. CONCLUSIONS: We consider that changes in bilirubin photoisomers induced by light exposure during clinical practice do not influence the measured unbound bilirubin concentration.


Assuntos
Bilirrubina/sangue , Bilirrubina/química , Testes de Química Clínica/métodos , Luz , Bilirrubina/efeitos da radiação , Humanos , Hiperbilirrubinemia Neonatal/diagnóstico , Hiperbilirrubinemia Neonatal/terapia , Recém-Nascido , Isomerismo , Fototerapia
7.
Pediatr Res ; 71(1): 77-84, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22289854

RESUMO

INTRODUCTION: This study was a two-center, stratified, parallel-group randomized trial comparing the effects of aggressive vs. conservative phototherapy on brainstem auditory evoked response (BAER) latencies in infants with extremely low birth weight (ELBW, ≤ 1,000 g). RESULTS: BAER latencies of 751-1,000 g birth-weight infants were shorter by 0.37 ms (95% confidence interval (CI) = 0.02, 0.73) for wave V, 0.39 ms (0.08, 0.70) for wave III, and 0.33 ms (0.01, 0.65) for wave I after aggressive phototherapy at one center. Interwave intervals did not differ significantly. Similar nonsignificant trends were recorded for 501-750 g birth-weight infants. At the other participating center, no significant differences were recorded, cautioning against overgeneralizing these results. DISCUSSION: The effects of bilirubin on the auditory pathway in ELBW infants depend on a complex interaction of bilirubin exposure, newborn characteristics, and clinical management. METHODS: Aggressive phototherapy was initiated sooner and continued at lower bilirubin levels than conservative phototherapy. A total of 174 ELBW infants were enrolled in the study; 111 infants were successfully tested at 35 weeks postmenstrual age (PMA); 57 died; and 6 were not successfully tested.


Assuntos
Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Recém-Nascido de Peso Extremamente Baixo ao Nascer/fisiologia , Fototerapia/métodos , Tempo de Reação/fisiologia , Bilirrubina/efeitos da radiação , Peso ao Nascer , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Masculino
8.
Pediatr Emerg Care ; 27(9): 884-9, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21926893

RESUMO

It is estimated that about two thirds of newborns will appear clinically jaundiced during their first weeks of life. As newborns and their mothers spend fewer days in the hospital after birth, the number of infants readmitted yearly in the United States for neonatal jaundice over the last 10 years has increased by 160%. A portion of these infants present to the emergency department, requiring a careful history and physical examination assessing them for the risk factors associated with pathologic bilirubin levels. Although the spectrum of illness may be great, the overwhelming etiology of neonatal jaundice presenting to an emergency department is physiologic and not due to infection or isoimmunization. Therefore, a little more than a good history, physical examination, and indirect/direct bilirubin levels are needed to evaluate an otherwise well-appearing jaundiced newborn. The American Academy of Pediatrics' 2004 clinical practice guidelines for "Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation" are a helpful and easily accessible resource when evaluating jaundiced newborns (available at http://aappolicy.aappublications.org/cgi/content/full/pediatrics;114/1/297). There are several exciting developments on the horizon for the diagnosis and management of hyperbilirubinemia including increasing use of transcutaneous bilirubin measuring devices and medications such as tin mesoporphyrin and intravenous immunoglobulin that may decrease the need for exchange transfusions.


Assuntos
Hiperbilirrubinemia Neonatal , Bilirrubina/análise , Bilirrubina/metabolismo , Bilirrubina/efeitos da radiação , Incompatibilidade de Grupos Sanguíneos/complicações , Incompatibilidade de Grupos Sanguíneos/diagnóstico , Aleitamento Materno , Diagnóstico Diferencial , Emergências , Eritroblastose Fetal/diagnóstico , Transfusão Total , Feminino , Hemoglobinopatias/complicações , Hemoglobinopatias/diagnóstico , Humanos , Hiperbilirrubinemia Neonatal/diagnóstico , Hiperbilirrubinemia Neonatal/epidemiologia , Hiperbilirrubinemia Neonatal/etiologia , Hiperbilirrubinemia Neonatal/fisiopatologia , Hiperbilirrubinemia Neonatal/terapia , Imunoglobulinas Intravenosas/uso terapêutico , Recém-Nascido , Icterícia Neonatal/diagnóstico , Icterícia Neonatal/epidemiologia , Kernicterus/etiologia , Kernicterus/prevenção & controle , Masculino , Erros Inatos do Metabolismo/complicações , Erros Inatos do Metabolismo/diagnóstico , Metaloporfirinas/uso terapêutico , Fototerapia , Guias de Prática Clínica como Assunto , Gravidez , Isoimunização Rh , Sepse/complicações , Sepse/diagnóstico
9.
Eur J Pediatr ; 170(10): 1247-55, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21455834

RESUMO

Neonatal phototherapy (NNPT), a noninvasive, easily available therapy, has been widely used for the treatment of neonatal jaundice for more than half a century. Its efficiency in decreasing plasma bilirubin concentration is well documented, and NNPT leads to greatly reduced exchange transfusion rates for neonates with hyperbilirubinemia. It is generally accepted that the side effects of NNPT are not serious and seem to be well controlled. This review will focus on these possible side effects as well as the approaches to minimize them.


Assuntos
Icterícia Neonatal/terapia , Fototerapia/efeitos adversos , Bilirrubina/efeitos da radiação , Hidratação , Humanos , Doenças do Sistema Imunitário/etiologia , Recém-Nascido , Icterícia Neonatal/etiologia , Fototerapia/métodos , Medição de Risco , Fatores de Risco , Resultado do Tratamento , Desequilíbrio Hidroeletrolítico/etiologia , Desequilíbrio Hidroeletrolítico/terapia
10.
Pediatr Int ; 53(5): 689-693, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21410595

RESUMO

BACKGROUND: To evaluate the clinical effects of phototherapy for neonatal hyperbilirubinemia, it is necessary to measure the rate of cyclobilirubin production, which represents the main photochemical pathway of bilirubin metabolism. Since the Atom Phototherapy Analyzer can be used to calculate the theoretical relative light energy of irradiance as a means of assessing the cyclobilirubin production rate for each wavelength spectrum, the clinical effect of phototherapy can be evaluated regardless of the light source type. Using the Atom Phototherapy Analyzer, the correlation between the irradiance of various light sources with different peak wavelengths and the rate of cyclobilirubin production was investigated in vitro. We also investigated the utility of green LED in vitro. METHODS: A bilirubin-albumin complex solution was prepared, poured into tubes, and irradiated using various light sources. All light sources used were bed-type phototherapy devices; that is, green and blue LED and green and blue fluorescence tubes. The concentrations of photoisomers were measured after irradiation and compared with the irradiance of the light sources. RESULTS: The irradiance measured by the Atom Phototherapy Analyzer decreased in the following order: blue fluorescence tube > green LED > blue LED > green fluorescence tube. The cyclobilirubin production rates and irradiance values of the light sources were significantly positively correlated (R(2) = 0.93, P < 0.05). CONCLUSION: Our data indicate that the Atom Phototherapy Analyzer can be used to objectively evaluate the effects of phototherapy using various light sources. Further, the effects of green LED were similar to those of other light sources in vitro.


Assuntos
Fototerapia/instrumentação , Radiometria/instrumentação , Bilirrubina/análogos & derivados , Bilirrubina/efeitos da radiação , Humanos , Hiperbilirrubinemia Neonatal , Recém-Nascido , Albumina Sérica/efeitos da radiação , Albumina Sérica Humana
11.
Georgian Med News ; (180): 88-92, 2010 Mar.
Artigo em Russo | MEDLINE | ID: mdl-20413824

RESUMO

The aim of the study was establishment of mechanisms of bilirubin oxidation and their involvement in the physiological and pathological processes in the living body (EPR study of photoradiated bilirubin). The photosensitized formation of free radical of bilirubin with g=2.003 and DeltaH=1.0 mTl, under action of the blue light with lambda(max)=450 nm by means of electronic spin resonance (ESR) was shown. Irradiation of sample in vacuum by visible light does not cause formation of free radicals. Irradiation of powder of bilirubin and also of its solution in chloroform leads to formation of the radical of bilirubin. The analysis of a spectrum (ESR) as powder also its solution in chloroform, that induced free radical belongs to bilirubin but not of solution was shown. Irradiation of a solution of bilirubin in chloroform causes absorption spectrum with lambda(max)=650 nm, characterized for absorption of solutions biliverdin in chloroform.


Assuntos
Antioxidantes/metabolismo , Bilirrubina/metabolismo , Cálculos Biliares/metabolismo , Antioxidantes/química , Bilirrubina/química , Bilirrubina/efeitos da radiação , Clorofórmio/química , Espectroscopia de Ressonância de Spin Eletrônica , Cálculos Biliares/química , Humanos , Oxirredução , Espécies Reativas de Oxigênio/metabolismo
12.
Pediatr Int ; 49(3): 318-21, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17532828

RESUMO

BACKGROUND: The light-emitting diode is used as one of the new light sources for phototherapy. NeoBLUE (Atom Medical, Tokyo, Japan) incorporates blue light-emitting diodes for the treatment of neonatal hyperbilirubinemia. The authors compared the in vitro efficacy of neoBLUE with conventional phototherapy devices. METHODS: The three light devices used included neoBLUE and two conventional phototherapy devices with six blue-white (BW) or six green (GR) fluorescent tubes. A bilirubin/human serum albumin solution (15 mg/dL) in 200 x 300 mm elliptical bag was irradiated with each three light device. The average light intensity of neoBLUE, BW and GR was 22.5, 10.2 and 2.6 microW/cm(2) per nm, respectively, for the irradiated area. Bilirubin photoisomers and native bilirubin were measured by high-performance liquid chromatography. RESULTS: In neoBLUE, BW and GR, the respective production rate of cyclobilirubin was 6.0, 3.7 and 3.9 x 10(-2) mg/dL/min, and the respective (4Z, 15E)-bilirubin/(4Z, 15Z)-bilirubin ratio after irradiation was 0.44, 0.33 and 0.12; the (4Z, 15Z)-bilirubin reduction rate at 20 min after irradiation was 60, 68 and 82%, respectively. The reduction rate of (4Z, 15Z)-bilirubin correlated with the (4Z, 15E)-bilirubin/(4Z, 15Z)-bilirubin ratio. CONCLUSION: Phototherapy using the neoBLUE under high level may be clinically more effective than therapy using the conventional light source from the results of the production rate of cyclobilirubin.


Assuntos
Bilirrubina/biossíntese , Luz , Fototerapia/métodos , Bilirrubina/análogos & derivados , Bilirrubina/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta à Radiação , Humanos , Hiperbilirrubinemia/sangue , Hiperbilirrubinemia/terapia , Recém-Nascido , Isomerismo
13.
Appl Biochem Biotechnol ; 135(3): 209-18, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17299208

RESUMO

A rapid reversed-phase (RP) high-performance liquid chromatography method for the isolation of bilirubin from its photoproducts (e.g., biliverdin) is reported. The method is based on isocratic elution using methanol:water as the mobile phase. A 24 full-factorial experimental design approach was adopted. For the optimization, the best separation was obtained using a flow rate of 1.50 mL/min, a mobile phase of 99:1 methanol:water (v/v) at pH 3.60, and a 150 x 4.6 mm id RP (C18) column containing 5-microm particles. These conditions produced the fastest total retention time of 3.38 +/- 0.055 min, and other chromatographic parameters were acceptable. Under the optimum conditions, a linear calibration curve for bilirubin was obtained over the 1.0-40.0 microg/L concentration range studied. The limit of quantification was 0.79 g/L and the limit of detection was 0.24 microg/L. Bilirubin in solution was monitored by ultraviolet detection at 450 nm.


Assuntos
Bilirrubina/isolamento & purificação , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Bilirrubina/efeitos da radiação , Concentração de Íons de Hidrogênio , Luz , Microfluídica/métodos , Transição de Fase , Fotoquímica/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
15.
Semin Perinatol ; 28(5): 326-33, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15686263

RESUMO

Phototherapy is the most common therapeutic intervention used for the treatment of hyperbilirubinemia. Although it has become a mainstay since its introduction in 1958, a better understanding of the photobiology of bilirubin, characteristics of the phototherapy devices, the efficacy and safety considerations of phototherapy applications, and improvements in spectroradiometers and phototherapy devices are necessary for more predictable and improved clinical practices and outcomes. A step forward in instituting consistent, uniform, and effective use of phototherapy is the recent American Academy of Pediatrics clinical guideline on the management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation, which outlines a clinical strategy for the diagnosis of hyperbilirubinemia and contains direct recommendations for the application of phototherapy. This article reviews the parameters that determine the efficacy of phototherapy, briefly discusses current devices and methods used to deliver phototherapy, and speculates on future directions and studies that are still needed to complement our presently incomplete knowledge of the facets of this common mode of therapy.


Assuntos
Icterícia Neonatal/terapia , Fototerapia , Bilirrubina/efeitos da radiação , Humanos , Recém-Nascido , Pele/efeitos da radiação
16.
Acta Paediatr ; 92(3): 327-31, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12725548

RESUMO

AIM: To evaluate the reliability of transcutaneous bilirubinometry (TcB) during and after phototherapy. METHODS: TcB was performed on the forehead and chest of infants with neonatal jaundice when capillary blood was sampled for bilirubin determination in a control group of 240 neonates. In a second group of 70 neonates exposed to phototherapy the same procedure was performed after at least 24 h of exposure: on the forehead, TcB was done in the centre of the unexposed area and also on the adjacent exposed area, and the exposed chest. During the post-phototherapy period, TcB was again done during the first and second days, at least 18-24 h after cessation of phototherapy. The results were then statistically evaluated and regression curves were plotted. RESULTS: A close correlation between TcB values and bilirubin levels was observed in the control group. In the phototherapy group, a correlation was also found between the TcB and the bilirubin values, but this correlation was significantly poorer than that of the controls; the correlation for the covered part of the forehead was significantly better than that of the exposed part but still poorer than that of the controls, though the difference was no longer significant. Skin colour recovered during the post-phototherapy period and correlation was better than that during exposure and no longer significantly different from that of the controls. CONCLUSION: Through its bleaching effect on the skin, phototherapy affects the correlation between TcB and the bilirubin values, but does not totally eliminate it. The unexposed parts show a better correlation, though this was still poorer than that of the controls. Recovery of skin colour occurred within 18-24 h after cessation of exposure.


Assuntos
Bilirrubina/análise , Bilirrubina/efeitos da radiação , Icterícia Neonatal/diagnóstico , Icterícia Neonatal/terapia , Fototerapia , Pele/química , Pele/efeitos da radiação , Administração Cutânea , Bilirrubina/sangue , Peso ao Nascer , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Icterícia Neonatal/sangue , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de Tempo
17.
Anal Bioanal Chem ; 375(6): 751-5, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12664173

RESUMO

Dilute aqueous and non-aqueous solutions of bilirubin were exposed to gamma radiation to examine the effects of ionizing radiation on the concentrations of a specimen of this nature. The ionising radiation emanated from a (137)Cs source, and was applied to 5.2 x 10(-2) mmol L(-1) solutions of the unconjugated specimen in 0.05 mol L(-1) aqueous NaOH and chloroform. Depletion of bilirubin after exposure was common to both solvents. Complete degradation was accomplished with doses in excess of 100 Gy. In the case of NaOH, it was found that the presence of molecular oxygen contributed more efficiently to the degradation process, than irradiation in air. When the experimental conditions were changed to nitrogen, the degradation process was suppressed. The sole by-product of merit originating from the NaOH work was the short-wavelength isomer of biliverdin, at 330 nm. In the case of chloroform, the exclusive product of interest was characterised as the long-wavelength isomer of biliverdin that absorbs in the broad region commencing from about 620 nm. The non-aqueous study was conducted in the presence and absence of molecular oxygen, with no significant changes in the results. Optimum production of the isomers in question occurred at a gamma dose of about 80 Gy. The general species of interest were monitored spectrophotometrically, and the results were treated mathematically to facilitate evaluation of the data. Our work represents the development of a facile gamma-ray method for the exclusive production of specific isomers of biliverdin, which are useful components in biosynthetic research.


Assuntos
Bilirrubina/química , Bilirrubina/efeitos da radiação , Raios gama , Soluções/química , Soluções/efeitos da radiação , Clorofórmio/química , Relação Dose-Resposta à Radiação , Humanos , Hidróxido de Sódio/química , Espectrofotometria , Água/química
18.
Photodermatol Photoimmunol Photomed ; 17(6): 272-7, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11722753

RESUMO

BACKGROUND/AIM: Light can be efficiently used for the treatment of neonatal jaundice. Sunlight, which covers a large portion of the light spectrum including the bilirubin-absorbing range, is abundant in the Middle East. Such advantages prompted the present study to investigate the efficiency of sunlight in isomerizing bilirubin. This may introduce a practical source of light for the treatment of hyperbilirubinic infants in areas where phototherapy units are not available. METHODS: The efficiency of sunlight was quantified by a comparison with a phototherapy unit. Aqueous bilirubin solutions were exposed to periodic sunlight over the entire year and the reduction of bilirubin concentration was monitored spectrophotometrically. Bilirubin solutions were also exposed to a phototherapy unit intensity comparable to that of sunlight (17 cm away from the source). RESULTS: The data indicated that at this comparable light intensity, the phototherapy unit was as effective as sunlight. However, for the treatment of neonatal jaundice, phototherapy units are usually operated at a distance of 50 cm (where the light intensity is six times less than that of sunlight). When this distance was tested, only 16% of bilirubin was isomerized in the first 5 min of exposure. In contrast, about 65% of bilirubin was isomerized when the phototherapy unit was placed at a distance of 17 cm and when the bilirubin solutions were exposed to sunlight for the same time period. The hourly and seasonal changes in sunlight intensity affected the reduction in bilirubin concentration significantly. CONCLUSION: Data revealed that sunlight is almost 6.5 times more effective than a phototherapy unit when operating at the ward geometry after taking isomerization efficiency and area of exposure into consideration. Moreover, sunlight is still more effective during the winter season, when its intensity is lower. Thus, sunlight may be considered an alternative phototherapy source for the treatment of neonatal jaundice, particularly in areas where conventional phototherapy units are unavailable.


Assuntos
Bilirrubina/efeitos da radiação , Icterícia Neonatal/radioterapia , Fototerapia , Luz Solar , Humanos , Técnicas In Vitro , Recém-Nascido , Isomerismo , Fototerapia/instrumentação , Doses de Radiação
19.
Radiat Res ; 148(4): 382-5, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9339954

RESUMO

The formation of triplet states of photosensitizers and singlet oxygen during reactions sensitized by protoporphyrin IX dimethyl ester (PPDME) and the products of its photo-oxidation in solution were studied by time-resolved spectroscopy. Irradiation with long-wavelength light (670 nm), which is absorbed by the products of photo-oxidation of PPDME, provides lower quantum yields of singlet oxygen than in sensitization with PPDME alone, which absorbs light with a wavelength of 630 nm. Spectroscopic measurements also confirmed the lower rate of sensitized photo-oxidation of bilirubin during irradiation with light with a wavelength of 670 nm.


Assuntos
Oxigênio/metabolismo , Fármacos Fotossensibilizantes/farmacologia , Protoporfirinas/farmacologia , Bilirrubina/efeitos da radiação , Lasers , Luz , Fotoquímica , Fotoquimioterapia , Oxigênio Singlete , Espectrofotometria Ultravioleta , Xenônio
20.
Chronobiol Int ; 14(3): 319-29, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9167892

RESUMO

The prevailing hypothesis for phototransduction is that visual (rod or cone) pigments mediate light's primary effects on biological clock systems. Common light-responsive chronobiological behavioral properties of plants and animals and some common molecular structures of plants and animals suggest the possibility that heme moieties and bile pigments in animals mediate some nonvisual influences of light on neuroactive gases and biological rhythms. As plant phytochrome resets the plant biological clock, the similar chromophore in bile pigments is proposed to transduce environmental light zeitgeber signals to endogenous biological clocks. The temporal association of plasma bilirubin and rapid-eye-movement (REM) sleep in populations, the correlation of secretion of biliary bilirubin with REM sleep among 10 different species (Spearman r = 0.89, p < 0.002), and the known responses of bilirubin to light lead to the hypothesis that bilirubin, in particular, plays an evolutionary role in the regulation of REM sleep and in mediating some of light's antidepressant effects.


Assuntos
Bilirrubina/fisiologia , Relógios Biológicos , Transdução de Sinal Luminoso/fisiologia , Modelos Biológicos , Sono REM/fisiologia , Animais , Bilirrubina/efeitos da radiação , Relógios Biológicos/efeitos da radiação , Evolução Biológica , Depressão/prevenção & controle , Humanos , Luz , Plantas , Sono REM/efeitos da radiação
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