Efficiency Of Phototherapy Research Articles

A tumor-microenvironment-activated nanoplatform of modified SnFe2O4 nanozyme in scaffold for enhanced PTT/PDT tumor therapy

Phototherapy has attracted widespread attention for cancer treatment due to its noninvasiveness and high selectivity. However, severe hypoxia, overexpressed glutathione and high levels of hydrogen peroxide (H2O2) of tumor microenvironment limit the antitumor efficiency of phototherapy. Herein, inspired by the specific response of nanozymes to the tumor microenvironment, a simple and versatile nanozyme-mediated synergistic dual phototherapy nanoplatform is constructed. In this study, tin ferrite (SnFe2O4, SFO) nanozyme as a photosensitizer was surface modified with polydopamine (denoted as P-SFO) and incorporated into poly(l-lactide) to fabricate an antitumor scaffold fabricated by selective laser sintering. On one hand, SFO nanozyme could act as a photoabsorber to convert light energy into heat for photothermal therapy (PTT). On the other hand, it played a role of photosensitizer in transferring the photon energy to generate reactive oxygen species (ROS) for photodynamic therapy (PDT). Importantly, its multivalent metal ions redox couples would decompose H2O2 into O2 for enhancing O2-dependent PDT and consume glutathione to relieve antioxidant capability of the tumors. Besides, polydopamine as a photothermal conversion agent further enhanced the photothermal performance of SFO. The results revealed the PLLA/P-SFO scaffold possessed a photothermal conversion efficiency of 43.52% for PTT and a high ROS generation capacity of highly toxic ·O2− and ·OH for PDT. Consequently, the scaffold displayed a prominent phototherapeutic effect with antitumor rate of 96.3%. In addition, the PLLA/P-SFO scaffolds possessed good biocompatibility for cell growth. These advantages endow PLLA/P-SFO scaffold with extensive applications in biomedical fields and opened up new avenue towards nanozyme-mediated synergistic phototherapy.

Porphyrin-based porous organic polymer coated ZIF-8 nanoparticles as tumor targeted photosensitizer for combination cancer photodynamic/photothermal therapy

The issue of low tumor-targeting and easy aggregation of small-molecule photosensitizers (PSs), as well as the heterogeneity and complexity of tumor tissue, greatly limit the therapeutic efficiency of phototherapy. Herein, a porphyrin-based organic polymer (POP) coated zeolitic imidazolate framework-8 (ZIF-8) hybrid nanoparticles (POP@ZIF-8) was developed, for delivering photosensitizer (porphyrin-based POP) specifically into tumor sites. The low-cost, biocompatible, tumor-specific POP@ZIF-8 with core-shell structure was prepared via a simple but efficient covalent surface-coating strategy, in which the pH-responsive ZIF-8 functioned as templates, finely controlling the nanometer size of the hybrid and ensuring targeted delivery of PSs to tumor tissue. Moreover, a direct covalently coated polymer-based PSs on ZIF-8 can better preserve optical properties compared to conventional physical adsorption methods. Under laser irradiation, the resulting hybridization not only efficiently converts light into local heat, causing severe photothermal damage to tumor tissue, but also synergistically promotes the production of strongly toxic 1O2, which exerts a photodynamic treatment on tumor sites. Therefore, this special POP@ZIF-8 hybrid presented a cooperatively enhanced synergistic photodynamic/photothermal anticancer efficacy, as demonstrated both the in vitro and in vivo assay, systematically. This study presents a practicable and reliable strategy to develop stable and high-efficiency cancer phototherapy agents which could simultaneously manipulate the structural characteristics and performance of targeted materials for promising noninvasive multi-mode anti-cancer.

Acrylate-functionalized porphyrin-covalent organic framework for bacterial-targeted and reaction-enhanced synergistic phototherapy/chemotherapy toward sterilization and wound healing.

Porphyrinic covalent organic frameworks (COFs) have emerged as prospective materials in photodynamic and photothermal sterilization. However, it is still a great challenge to construct an efficient COF-based sterilizing agent with good photothermal and photodynamic properties and bacterial targeting ability. Herein, we report a multifunctional porphyrin-COF for bacterial-targeted and reaction-enhanced synergistic phototherapy/chemotherapy for sterilization and wound healing. The ordered crystal structure of the porphyrin-COF not only effectively avoids the self-aggregation-induced quenching of the porphyrin monomer, but also facilitates the storage and transport of singlet oxygen. The acrylate substituent in the other monomer serves as a bacterial targeting moiety and the in situ reaction site with the sulfhydryl group of the bacterial surface protein via a Michael addition reaction, thus fixing the bacteria on the surface of COF and making them lose the colonization ability. Furthermore, the bonding of COF and bacteria further amplifies the therapeutic efficiency of phototherapy. Therefore, the developed multifunctional sterilization platform not only provides a new strategy for the design of novel bactericidal materials but also broadens the biological applications of COF-based materials.

Periodic change of body position under phototherapy in term and preterm neonates with hyperbilirubinaemia.

Phototherapy is the mainstay of treatment of neonatal hyperbilirubinaemia. Periodic change in position of the neonate under phototherapy (from supine to prone or lateral positions) may improve the efficiency of phototherapy by hastening the access of phototherapy light to bilirubin deposited in different parts of the skin and subcutaneous tissue. To evaluate the effects of periodic change of body position during phototherapy as compared to no prescribed change in body position, on serum total bilirubin level and duration of treatment in neonates with unconjugated hyperbilirubinaemia during the first 28 days of life. Secondary objectives of the review included evaluation of the efficacy of periodic change of body position on the need for or number of exchange transfusions, incidence of bilirubin-induced neurological damage (BIND), side effects of phototherapy, and sudden infant death syndrome (SIDS). We used the standard search strategy of Cochrane Neonatal to run comprehensive searches in the Cochrane Central Register of Controlled Trials (CENTRAL; 2021, Issue 3) in the Cochrane Library and Ovid MEDLINE and Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Daily and Versions on 5 March 2021. We also searched clinical trials databases and the reference lists of included studies and relevant reviews for randomised controlled trials (RCTs) and quasi-RCTs. We included RCTs and quasi-RCTs if they enrolled neonates (term and preterm) of either gender with unconjugated hyperbilirubinaemia requiring phototherapy and compared periodic change of the body position of the infant under phototherapy with no prescribed change in body position. Two review authors independently assessed trial quality and extracted data, consulting with a third review author in the case of disagreement. We used standard Cochrane methodological procedures, including assessing the risk of bias of included studies. We used the GRADE approach to assess the certainty of evidence. Primary outcomes were the duration of phototherapy and rate of fall of serum bilirubin at 24 hours. Secondary outcomes included the need for exchange transfusion, number of exchange transfusions, incidence of BIND, and SIDS. We included five studies (343 neonates) with an overall high risk of bias in the review. The body position under phototherapy was changed every two hours or every two-and-a-half hours in two studies each, and every three hours in one study. Three of the five studiesincluded healthy term neonates, whilst the other two studies also included preterm neonates (≥ 33 weeks' gestation); however, separate data about review outcomes in preterm neonates were not available. Periodic change in body position may lead tolittle or no difference in the duration of phototherapy (mean difference (MD) 1.71 hours, 95% confidence interval (CI) -3.17 to 6.59 hours; I² = 58%; 4 studies, 231 participants; low certainty evidence). Only one study reported the rate of fall of serum total bilirubin at 24 hours of starting the phototherapy. Periodic change in body position may lead tolittle or no difference in the rateof fall of serum total bilirubin at 24 hours(MD0.02 mg/dL/h, 95% CI -0.02 to 0.06 mg/dL/h; 1 study, 100 participants; low certainty evidence). We downgraded the certainty of evidence to low due to risk of bias and imprecision. None of the included studies reported the need for or number of exchange transfusions, incidence of BIND, or SIDS. Lack of separate data precluded subgroup analysis. The available evidence is insufficient to determine the effects of periodic change of body position compared with no prescribed change of body position under phototherapy. There is low certainty evidence that there may be little or no difference in the duration of phototherapy andrate of fall in bilirubin at 24 hours of starting phototherapy between periodic change in body position and no prescribed change of body position under phototherapy in term and preterm neonates. None of the included studies reported the effect of change of position on the need for or number of exchange transfusions, incidence of BIND, or SIDS. One study is awaitingclassification and could not be included in the review. Further studies are needed to evaluate theeffectof periodic change in body position under phototherapy, especially in neonates with haemolytic hyperbilirubinaemia and in very preterm neonates. The results of this systematic review apply mainly to neonates born at late-preterm or term gestation receiving phototherapy for non-haemolytic hyperbilirubinaemia.

Potentiation Effect of Iodine Species on the Antimicrobial Capability of Surfaces Coated with Electroactive Phthalocyanines.

The spreading of different infections can occur through direct contact with glass surfaces in commonly used areas. Incorporating the use of alternative therapies in these materials seems essential to reduce and also avoid bacterial resistance. In this work, the capability to kill microbes of glass surfaces coated with two electroactive metalated phthalocyanines (ZnPc-EDOT and CuPc-EDOT) is assessed. The results show that both of these materials are capable of producing reactive oxygen species; however, the polymer with Zn(II) (ZnPc-PEDOT) has a singlet oxygen quantum yield 8-fold higher than that of the Cu(II) containing analogue. This was reflected in the in vitro experiments where the effectiveness of the surfaces was tested in bacterial suspensions, monitoring single microbe inactivation upon attachment to the polymers, and eliminating mature biofilms. Furthermore, we evaluated the use of an inorganic salt (KI) to potentiate the photodynamic inactivation mediated by an electropolymerized surface. The addition of the salt improved the efficiency of phototherapy at least two times for both polymers; nevertheless, the material coated with ZnPc-PEDOT was the only one capable of eliminating >99.98% of the initial microbes loading under different circumstances.

The recent progress on metal-organic frameworks for phototherapy.

Some infectious or malignant diseases such as cancers are seriously threatening the health of human beings all over the world. The commonly used antibiotic therapy cannot effectively treat these diseases within a short time, and also bring about adverse effects such as drug resistance and immune system damage during long-term systemic treatment. Phototherapy is an emerging antibiotic-free strategy to treat these diseases. Upon light irradiation, phototherapeutic agents can generate cytotoxic reactive oxygen species (ROS) or induce a temperature increase, which leads to the death of targeted cells. These two kinds of killing strategies are referred to as photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. So far, many photo-responsive agents have been developed. Among them, the metal-organic framework (MOF) is becoming one of the most promising photo-responsive materials because its structure and chemical compositions can be easily modulated to achieve specific functions. MOFs can have intrinsic photodynamic or photothermal ability under the rational design of MOF construction, or serve as the carrier of therapeutic agents, owing to its tunable porosity. MOFs also provide feasibility for various combined therapies and targeting methods, which improves the efficiency of phototherapy. In this review, we firstly investigated the principles of phototherapy, and comprehensively summarized recent advances of MOF in PDT, PTT and synergistic therapy, from construction to modification. We expect that our demonstration will shed light on the future development of this field, and bring it one step closer to clinical trials.

Efficiency of phototherapy in patients with mycosis fungoides: preliminary results of a comparative non-randomized study

Clinical reasoning. There is a need to optimize the use of UV-B-311 nm and PUVA-therapy in patients with mycosis fungoides to determine the duration of the treatment regimen, the number of sessions per week, and ultraviolet irradiation regimen.
 Goal of research. Evaluation of the effect of the type and duration phototherapy on efficacy in patients with mycosis fungoides.
 Principle. A comparative, non-randomized study of the effectiveness of phototherapy in patients with mycosis fungoides in the early stages. Evaluation of the effectiveness of UV-B-311 nm and PUVA therapy was performed using the BSA index (area of skin lesions) and Modified Severity-Weighted Assessment Tool (mSWAT), as well as according to the criteria proposed by the International Society for Skin Lymphomas (ISCL), the European Organization for the Study and Cancer Treatment (EORTC) and United States Cutaneous Lymphoma Consortium (USCLC).
 Results. The study included 14 patients with mycosis fungoides, 5 of whom received treatment with UV-B-311 nm, 9 PUVA therapy. A strong correlation was found between the duration of UV-B-311 nm therapy with mSWAT delta (R = 0.90; p = 0.038) and BSA delta (R = 0.90; p = 0.038), while similar correlation was not found in the PUVA-therapy group (mSWAT (R = 0.24; p = 0.527); BSA (R = 0.09; p = 0.823)). When comparing the effectiveness of therapy between the treatment group UV-B-311 nm and PUVA therapy, delta mSWAT and BSA at the 20th procedure, delta mSWAT and BSA after the end of therapy did not have a statistically significant difference between the UVB-311 nm and PUVA groups.
 Conclusion. Statistically significant correlation was found between the number of procedures and the effectiveness of therapy In the UV-B-311 nm group. An increase in the number of PUVA therapy procedures (after 20) does not lead to a statistically significant increase in the effectiveness of treatment. Additional research is needed to increase the level of evidence of the results and develop optimal phototherapy regimens.

Efficiency of phototherapy in patients with mycosis fungoides: preliminary results of a comparative non-randomized study

Clinical reasoning. There is a need to optimize the use of UV-B-311 nm and PUVA-therapy in patients with mycosis fungoides to determine the duration of the treatment regimen, the number of sessions per week, and ultraviolet irradiation regimen.
 Goal of research. Evaluation of the effect of the type and duration phototherapy on efficacy in patients with mycosis fungoides.
 Principle. A comparative, non-randomized study of the effectiveness of phototherapy in patients with mycosis fungoides in the early stages. Evaluation of the effectiveness of UV-B-311 nm and PUVA therapy was performed using the BSA index (area of skin lesions) and Modified Severity-Weighted Assessment Tool (mSWAT), as well as according to the criteria proposed by the International Society for Skin Lymphomas (ISCL), the European Organization for the Study and Cancer Treatment (EORTC) and United States Cutaneous Lymphoma Consortium (USCLC).
 Results. The study included 14 patients with mycosis fungoides, 5 of whom received treatment with UV-B-311 nm, 9 PUVA therapy. A strong correlation was found between the duration of UV-B-311 nm therapy with mSWAT delta (R = 0.90; p = 0.038) and BSA delta (R = 0.90; p = 0.038), while similar correlation was not found in the PUVA-therapy group (mSWAT (R = 0.24; p = 0.527); BSA (R = 0.09; p = 0.823)). When comparing the effectiveness of therapy between the treatment group UV-B-311 nm and PUVA therapy, delta mSWAT and BSA at the 20th procedure, delta mSWAT and BSA after the end of therapy did not have a statistically significant difference between the UVB-311 nm and PUVA groups.
 Conclusion. Statistically significant correlation was found between the number of procedures and the effectiveness of therapy In the UV-B-311 nm group. An increase in the number of PUVA therapy procedures (after 20) does not lead to a statistically significant increase in the effectiveness of treatment. Additional research is needed to increase the level of evidence of the results and develop optimal phototherapy regimens.

Metal-Organic Frameworks-Derived Carbon Nanoparticles for Photoacoustic Imaging-Guided Photothermal/Photodynamic Combined Therapy.

Combination of photothermal therapy (PTT) and photodynamic therapy (PDT) has become a promising cancer treatment in recent years. However, their applications are limited by complex synthetic protocols and low efficacy. Hence, optimizing experimental approach and improving the efficiency of phototherapy is the current research focus. In this work, various pyrolysis temperatures and sizes of zeolitic imidazolate framework-8 (ZIF-8) derived carbon nanoparticles (ZCNs) are obtained by a simple direct pyrolysis of the ZIF-8 nanoparticles. Meanwhile, the ZCNs can be used as photothermal agents and photosensitizers to produce heat and reactive oxygen species simultaneously upon near-infrared laser irradiation. Moreover, it is observed that the phototherapy effects and photoacoustic (PA) signal of ZCNs could be enhanced with the increase in the nanoparticle size. Subsequently, guided by PA imaging, the therapeutic effect of ZCNs is investigated on a small animal model, where tumors are entirely eliminated with minimal side effect, demonstrating the high efficacy of the larger size of ZCNs through combination of PTT and PDT. Therefore, it is expected that the ZCN is a simple and highly effective phototherapeutic platform for oncotherapy, and the concept of size-dependent enhanced behavior of phototherapy and PA imaging will be very useful in the development of nanomaterials for cancer therapy.

The physical and chemical properties of the skin and the action of therapeutic physical factors

This article discusses the importance of the physical and chemical properties of the skin subjected to the action of the therapeutic physical factors. The author presents the data illustrating the influence of alterations in skin permeability on the penetration of medicinal substances into the organs and tissues of the body under conditions of application of various physico-pharmacological methods based on the use of chemical ingredients of peloid therapy and other balneotherapeutic technologies. The effectiveness of skin permeability is known to be of special importance in the context of physical therapy since it determines the action of its individual components. The influence of skin pH values as the parameters determining the peculiar features of percutaneous electrophoresis of cations and anions is demonstrated. It is shown that the reduction of electrical resistance of the skin barrier significantly improves the electrophoretic propagation of medicinal substances; therefore, such alteration determines, in many respects, the choice of the dosimetric parameters for electropuncture and electro acupuncture. Special attention is given to the discussion of the opportunities through which the variation of the skin optical properties could be applied to enhance the efficiency of phototherapy. The need to continue research on this problem topical for physiotherapy is emphasized.

Pompon-like RuNPs-Based Theranostic Nanocarrier System with Stable Photoacoustic Imaging Characteristic for Accurate Tumor Detection and Efficient Phototherapy Guidance.

Even though numerous therapeutic methods exist for cancer treatment, many fail to achieve ideal outcomes or have severe side effects. Here, we describe a theranostic nanocarrier system with improved tumor vasculature detection and tumor margin quantification that increases the accuracy and guidance efficiency of phototherapy. Novel pompon-like RuNPs with superb photothermal properties and high encapsulation efficiency were first synthesized via the polyol reducing method. Based on these RuNPs, we then developed a multifunctional theranostic system, pRu-pNIPAM@RBT, composed of poly(N-isopropylacrylamide) as the thermal-response switch and of [Ru(bpy)2(tip)]2+ as the photosensitizer of PDT and the contrast agent of biomedical imaging. We demonstrate that the pRu-pNIPAM@RBT can generate intracellular hyperthermia and reactive oxygen species (ROS) for simultaneous photothermal therapy (PTT) and photodynamic therapy (PDT) by laser activation. In contrast to other studies, our work highlights the integration of quantitative analysis of infrared thermal imaging and PA imaging data, which can distinguish between tumor and healthy tissues and guide the destructive but precise phototherapy and decrease nonspecific tissue injury. Considering the excellent in vivo antitumor phototherapeutic effects, this strategy may help preclinical researchers gain insight into theoretical as well as practical aspects of precision cancer therapy.

PHOTOTHERAPY AND PHOTODYNAMIC THERAPY IN THE TREATMENT OF EXTRAGENITAL LICHEN SCLEROSUS

Abstract: Lichen sclerosus is a chronic inflammatory disease of the skin and mucous membranes coated with squamous nonkeratinizing epithelium. The etiology of this disease is not completely clear. The exact prevalence of the disease is quite difficult to establish due to a lack of awareness of medical staff about the disease and relatively few patients visit medical specialists. Many researchers lean towards autoimmune theory of the origin of the disease. This is the basis for the most common methods of treatment. We have the information that lichen sclerosus may be caused by trauma, hormonal disorders and infectious lesions. In some cases genetic predisposition is observed. Standard treatment for lichen sclerosus is the topical application of glucocorticosteroids. If this treatment is ineffective topical calcineurin inhibitors are used. However, in many cases both treatments of lichen sclerosus are ineffective. In response to the problem alternative therapies can be used. Efficiency of phototherapy and photodynamic therapy for some cutaneous diseases is well known, in this regard it is important to examine in depth possibilities of these methods for treatment of lichen sclerosus.

On the individualization of therapeutic doses of optical radiation according to changes in the parameters of blood oxygenation

The effect of in vivo laser irradiation by optical radiation on blood from different patients is studied. The objects of research were three series of blood samples from patients whose treatment course included extracorporeal UV blood irradiation, intravenous laser blood irradiation and supra-venous blood laser irradiation. Before and after irradiation the results on optic oximetry and gas content of venous blood were compared. The results of positive and negative influence of blood irradiation on characteristics of an oxygen exchange in separate patients and on the maintenance of some products of metabolism are represented. It is shown that at the same power dose, their changes depend on individual, initial values of hemoglobin oxygen saturation of venous blood and its photoinduced changes which objectively reflect individual sensitivity of patients to the action of optical radiation on blood and can be used for assessment of the efficiency of phototherapy.

Smart human serum albumin-indocyanine green nanoparticles generated by programmed assembly for dual-modal imaging-guided cancer synergistic phototherapy.

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), is a light-activated local treatment modality that is under intensive preclinical and clinical investigations for cancer. To enhance the treatment efficiency of phototherapy and reduce the light-associated side effects, it is highly desirable to improve drug accumulation and precision guided phototherapy for efficient conversion of the absorbed light energy to reactive oxygen species (ROS) and local hyperthermia. In the present study, a programmed assembly strategy was developed for the preparation of human serum albumin (HSA)-indocyanine green (ICG) nanoparticles (HSA-ICG NPs) by intermolecular disulfide conjugations. This study indicated that HSA-ICG NPs had a high accumulation with tumor-to-normal tissue ratio of 36.12±5.12 at 24 h and a long-term retention with more than 7 days in 4T1 tumor-bearing mice, where the tumor and its margin, normal tissue were clearly identified via ICG-based in vivo near-infrared (NIR) fluorescence and photoacoustic dual-modal imaging and spectrum-resolved technology. Meanwhile, HSA-ICG NPs efficiently induced ROS and local hyperthermia simultaneously for synergetic PDT/PTT treatments under a single NIR laser irradiation. After an intravenous injection of HSA-ICG NPs followed by imaging-guided precision phototherapy (808 nm, 0.8 W/cm2 for 5 min), the tumor was completely suppressed, no tumor recurrence and treatments-induced toxicity were observed. The results suggest that HSA-ICG NPs generated by programmed assembly as smart theranostic nanoplatforms are highly potential for imaging-guided cancer phototherapy with PDT/PTT synergistic effects.

The special physiological importance of the UV-A spectrum for successful phototherapy

This article deals with the characteristics of the functioning of the human biological clock and the possibilities of its correction by light fluxes with different spectral characteristics in patients with seasonal depressions. Phototherapy as a nondrug method of treating seasonal depressive disorders has been used since the early 1980s. The investigation compares the efficiency of phototherapy with different spectral characteristics for correcting biorhythm disorders in subjects with seasonal depressions. Twenty-four patients with recurrent depressive disorders were examined in different years. In group 1, patients underwent a course of phototherapy according to the standard scheme (in the optical range); in group 2, patients underwent a course of phototherapy by the original method developed by the authors, with the light flux enriched in UV-A (360–380 nm) to model the structure of natural sunlight. The depth and rate of regression of symptoms in patients with seasonal depressions showed the higher efficiency of UV-A phototherapy compared to the phototherapy in the optical spectrum.

Possibilities of phototherapy use for correction of psychоvegetative disturbance in schoolchildren

Efficiency of phototherapy (10 sessions each lasting 30 minutes in the morning hours, light intensity 3300 lux) in 40 children with psychovegetative disorders, clinically represented by cephalalgic syndrome of different types is evaluated. Clinical symptoms, mood, vegetative status, level of thyroid hormones, hydrocortisone, prolactin in the blood, and excretion of catecholamines with diurnal urea are analyzed. After the course of phototherapy in 92,5% of children positive changes in psychovegetative and neuroendocrine spheres were found. The most pronounced positive effect of phototherapy is found in the group of children with chronic exercise-induced headache. Optimizing modulating influence of phototherapy on the content of stress-realizing hormones in childs body, on vegetative homeostasis, increasing adaptability of body are determined. Use of phototherapy for correction of psychovegetative disorders in children is reasoned.

Photodynamic activity of chlorin e 6 and chlorin e 6 ethylenediamide in vitro and in vivo

Several parameters of chlorin e 6 and its derivative chlorin e 6 ethylenediamide have been investigated as these compound are potential sensitizers for photodynamic therapy. A study carried out to compare the cellular uptake of the pigments indicates that chlorin e 6 ethylenediamide possesses an enhanced affinity for tumour cells and cellular membranes. Comparison of the uptake in induced sarcoma shows that chlorin e 6 ethylenediamide is a much better tumour localizer than chlorin e 6. The efficiency of phototherapy with chlorin e 6 ethylenediamide is higher than that with chlorin e 6. These data show the influence of the substitution of the carboxyl groups in chlorin e 6 by ester and amide groups on the photosensitizing properties of the pigments.

Influence of skin optical losses on configurational photoisomerization of bilirubin during phototherapy

Kubelka-Munk theory of radiation transfer in turbid media is applied to determine the influence of skin optical losses on the efficiency of phototherapy of neonatal hyperbilirubinemia. By using a multilayer model of the skin and a rate equation analysis of bilirubin photo-isomerization, the photon absorption rates of birilubin and of its configurational photoisomers and, in turn, the photoequilibrium concentrations and rise time are calculated for spectrally Gaussian light sources and fluorescent lamps used in phototherapy. It turns out that light absorption and scattering processes in the skin layers produce a 30 nm red-shift of the optimum value of the peak excitation wave-length of bilirubin absorption and photoequilibrium rise time. The comparative data on the phototherapeutical efficiency of different spectral regionsin vivo (Gunn rats and humans) are discussed.

Dependence of the efficiency of phototherapy on plasma bilirubin concentration.

407 newborns with idiopathic transitory hyperbilirubinaemia were examined with regard to the decrease in serum bilirubin levels during 24 hours of intermittent phototherapy (12 hours of light exposure). The photoeffect (i.e. decrease of serum bilirubin concentration after 24 hours of therapy) showed a unique and predictable nonlinear correlation with the plasma bilirubin concentration before treatment. This relationship can be used for individualizing the duration of phototherapy and the dose of light. The apparent effect of birth weight, gestational age, and postnatal age on the efficiency of phototreatment is only due to differing initial levels of bilirubin concentration. Intermittent illumination seemed to be more efficient than continuous.

Uptake of hematoporphyrin derivative and sensitized photoinactivation of C3H cells with different oncogenic potential

Four types of mouse embryo fibroblast cells of different oncogenic potential were investigated with respect to uptake of the tumor localizing agent hematoporphyrin derivative (Hpd) and sensitized photoinactivation. Cell size and cellular content of Hpd were measured simultaneously for single cells by means of flow cytofluorimetry. The more malignant cell types had a slightly higher porphyrin uptake per unit cellular volume than the untransformed type, while the photosensitivity of cells incubated with Hpd was equal for all the cell types. Since Hpd seems to concentrate in membranes, this may be related to the fact that the membrane areas of malignant cells are relatively larger than that of untransformed cells, due to the presence of more microvilli. The present study indicates that the preferential localization of Hpd in tumors, as well as the high efficiency of phototherapy reported in the literature, are due to extracellular differences between the tumors and normal tissue.