An Active Bio-Based Food Packaging Material of ZnO@Plant Polyphenols/Cellulose/Polyvinyl Alcohol: DESIGN, Characterization and Application.

Active packaging materials protect food from deterioration and extend its shelf life. In the quest to design intriguing packaging materials, biocomposite ZnO/plant polyphenols/cellulose/polyvinyl alcohol (ZnPCP) was prepared via simple hydrothermal and casting methods. The structure and morphology of the composite were fully analyzed using XRD, FTIR, SEM and XPS. The ZnO particles, plant polyphenols (PPL) and cellulose were found to be dispersed in PVA. All of these components share their unique functions with the composite's properties. This study shows that PPL in the composite not only improves the ZnO dispersivity in PVA as a crosslinker, but also enhances the water barrier of PVA. The ZnO, PPL and cellulose work together, enabling the biocomposite to perform as a good food packaging material with only a 1% dosage of the three components in PVA. The light shielding investigation showed that ZnPCP-10 can block almost 100% of both UV and visible light. The antibacterial activities were evaluated by Gram-negative Escherichia coli (E. coli) and Gram-positive staphylococcus aureus (S. aureus), with 4.4 and 6.3 mm inhibition zones, respectively, being achieved by ZnPCP-10. The enhanced performance and easy degradation enables the biocomposite ZnPCP to be a prospect material in the packaging industry.

Evaluation of the PSMA-Binding Ligand 212Pb-NG001 in Multicellular Tumour Spheroid and Mouse Models of Prostate Cancer.

Radioligand therapy targeting the prostate-specific membrane antigen (PSMA) is rapidly evolving as a promising treatment for metastatic castration-resistant prostate cancer. The PSMA-targeting ligand p-SCN-Bn-TCMC-PSMA (NG001) labelled with 212Pb efficiently targets PSMA-positive cells in vitro and in vivo. The aim of this preclinical study was to evaluate the therapeutic potential of 212Pb-NG001 in multicellular tumour spheroid and mouse models of prostate cancer. The cytotoxic effect of 212Pb-NG001 was tested in human prostate C4-2 spheroids. Biodistribution at various time points and therapeutic effects of different activities of the radioligand were investigated in male athymic nude mice bearing C4-2 tumours, while long-term toxicity was studied in immunocompetent BALB/c mice. The radioligand induced a selective cytotoxic effect in spheroids at activity concentrations of 3-10 kBq/mL. In mice, the radioligand accumulated rapidly in tumours and was retained over 24 h, while it rapidly cleared from nontargeted tissues. Treatment with 0.25, 0.30 or 0.40 MBq of 212Pb-NG001 significantly inhibited tumour growth and improved median survival with therapeutic indexes of 1.5, 2.3 and 2.7, respectively. In BALB/c mice, no signs of long-term radiation toxicity were observed at activities of 0.05 and 0.33 MBq. The obtained results warrant clinical studies to evaluate the biodistribution, therapeutic efficacy and toxicity of 212Pb-NG001.

Fabrication of Thermosensitive Cyclic Brush Copolymer with Enhanced Therapeutic Efficacy for Anticancer Drug Delivery.

Adaptation of cyclic brush polymer for drug delivery applications remains largely unexplored. Herein, cyclic brush copolymer of poly(2-hydroxyethyl methacrylate-g-poly(N-isopropylacrylamide-st-N-hydroxyethylacrylamide)) (cb-P(HEMA-g-P(NIPAAm-st-HEAAm))), comprising a cyclic core of PHEMA and thermosensitive brushes of statistical copolymer of P(NIPAAm-st-HEAAm), is designed and synthesized successfully via a graft-from approach using atom transfer free radical polymerization from a cyclic multimacroinitiator. The composition of the brush is optimized to endow the resulting cyclic brush copolymer with a lower critical solution temperature (LCST) slightly above the physiological temperature, but lower than the localized temperature of tumor tissue, which is suitable for the hyperthermia-triggered anticancer drug delivery. Critical aggregation concentration determination reveals better stability for the unimolecular nanoparticle formed by the cyclic brush copolymer than that formed by the bottlebrush analogue. The dramatically increased size with elevated temperatures from below to above the LCST confirms hyperthermia-induced aggregation for both formulations. Such structural destabilization promotes significantly the drug release at 40 °C. Most importantly, the drug-loaded cyclic brush copolymer shows enhanced in vitro cytotoxicity against HeLa cells than the bottlebrush counterpart. The better stability and higher therapeutic efficacy demonstrates that the thermosensitive cyclic brush copolymer is a better formulation than bottle brush copolymer for controlled drug release applications.

Comparison of postoperative ciliary body changes associated with the use of 23-gauge and 20-gauge system for pars plana vitrectomy.

BACKGROUND: To compare the ciliary body changes associated with the use of 23-gauge (23G) and 20-gauge (20G) systems for pars plana vitrectomy. METHODS: A total of 60 patients (60 eyes) with idiopathic epiretinal membrane who were scheduled for surgical treatment were selected and randomly assigned to 20G group or 23G group. Time required for incision making, vitrectomy, and incision closure was compared between the two groups. Changes in ciliary body were evaluated by ultrasound microscopy (UBM). Anterior chamber inflammation was assessed with laser flare meter instrument. RESULTS: Incision-making time (4.5 ± 0.9 min) and incision-closure time (2.8 ± 0.7 min) in the 23G group were significantly shorter than those in the 20G group (10.1 ± 1.5 min and 11.3 ± 2.2 min, respectively). No significant intergroup difference was observed with respect to time required for vitrectomy (21.6 ± 3.3 min and 20.7 ± 3.2 min, respectively). Ciliary body thickness in the 23G group recovered back to preoperative levels after 4 weeks, as against 8 weeks in the 20G group. Postoperative ciliary body thickness in the 20G group was significantly higher than that in the 23G group (p < 0.05). The aqueous protein concentration in 23G group recovered back to preoperative levels after 2 weeks, as against 4 weeks in the 20G group. Postoperative aqueous protein concentration in the 20G group was significantly higher than that in the 23G group (p < 0.05). CONCLUSIONS: The use of 23G system was associated with significantly milder injury to the ciliary body as compared to that associated with the use of 20G system. TRIAL REGISTRATION: The study was retrospectively registered on Chinese Clinical Trial Registry. The clinical study registration number was ChiCTR-INR-17011082 . Date of registration: 2017-04-07.

Morphological and biochemical characteristics associated with autophagy in gastrointestinal diseases.

Autophagy is a cellular catabolic process characterized by the formation of double-membrane autophagosomes. Transmission electron microscopy is the most rigorous method to clearly visualize autophagic engulfment and degradation. A large number of studies have shown that autophagy is closely related to the digestion, secretion, and regeneration of gastrointestinal (GI) cells. However, the role of autophagy in GI diseases remains controversial. This article focuses on the morphological and biochemical characteristics of autophagy in GI diseases, in order to provide new ideas for their diagnosis and treatment.

Phospholipase C-γ1 expression correlated with cancer progression of potentially malignant oral lesions.

BACKGROUND: Phospholipase C-γ1 (PLCγ1) is required for cellular migration during tumor progression and invasion of oral squamous cell carcinoma (OSCC) cells. The objective of the current study was to determine immunoexpression pattern of PLCγ1 in oral potentially malignant lesions (OPLs) and evaluate PLCγ1 usefulness as a biomarker for predicting clinical behavior in the carcinogenesis of OPL. METHODS: In a retrospective follow-up study, the expression pattern of PLCγ1 protein was determined using immunohistochemistry in samples from 68 patients, including untransformed cases (n = 38) and malignant-transformed cases (n = 30). The corresponding post-malignant lesions (OSCCs) were also performed. RESULTS: We observed that elevated expression of PLCγ1 in 40 of 68 (59%) general OPLs and 23 of 30 (77%) OSCCs compared with that in normal oral mucosa. Kaplan-Meier analysis revealed that patients with PLCγ1 positivity had a significantly higher incidence of OSCC than those with PLCγ1 negativity. Cox regression analysis revealed that PLCγ1 expression patterns were significantly associated with increased risk of malignant progression. In addition, the correlation between PLCγ1 expression in pre-malignant OPL and that in post-malignant OSCC was significant (P = 0.004). CONCLUSION: These data indicate that PLCγ1 expression in OPL correlated with oral cancer progression, and PLCγ1 may serve as a useful marker for the identification of high-risk OPL into OSCC.

[Clinical evaluation of quality of vision with age-related cataract of different morphologies].

OBJECTIVE: To investigate influence of cataract morphology on quality of vision in measurement of straylight and contrast sensitivity (CS), and to determine which type of cataract presents higher impairment of quality of vision. METHODS: In a cross-sectional study, 76 eyes of 76 age-related cataract patients who treated in the Eye Hospital of China Medical University from February 2010 to December 2010 with a best corrected visual acuity (BCVA) of 0.5 or better, were classified into 3 groups: cortical cataract group (33 eyes of 33 subjects), nuclear cataract group (20 eyes of 20 subjects), posterior cataract group (23 eyes of 23 subjects), as well as normal control group (26 eyes of 26 subjects). BCVA, CS and intraocular straylight were respectively measured with phoropter, C-Quant straylight meter and CSV-1000E contrast sensitivity tester. Subjective quality of vision was examined with visual function index-14 (VF-14). RESULTS: Age, BCVA, straylight levels and CS at 3, 6, 12 and 18 c/d were 66.1 ± 6.7, 0.58 ± 0.10, 1.50 ± 0.24, 1.33 ± 0.19, 1.21 ± 0.18, 1.01 ± 0.19, and 0.50 ± 0.09 in the cortical group, 67.6 ± 5.0, 0.62 ± 0.11, 1.46 ± 0.11, 1.38 ± 0.19, 1.28 ± 0.19, 1.09 ± 0.18, and 0.54 ± 0.09 in the nuclear group, 60.6 ± 7.1, 0.57 ± 0.09, 1.85 ± 0.26, 1.11 ± 0.12, 1.04 ± 0.13, 0.89 ± 0.13, 0.34 ± 0.11 in the posterior group, and 63.9 ± 7.3, 1.00 ± 0.11, 1.28 ± 0.17, 1.58 ± 0.19, 1.72 ± 0.21, 1.53 ± 0.19, and 0.71 ± 0.11 in the normal eyes, respectively (F = 9.983, F = 103.925, F = 31.760, F = 28.871, F = 65.889, F = 66.453, F = 61.540; P = 0.000). In SNK-q test, BCVA, levels of straylight and CS at each spatial frequency in the normal eyes were significantly different from that in cataracts of different morphologies (P < 0.05); BCVA did not differ significantly for cataract of the 3 types (P > 0.05); age, straylight levels and CS at each spatial frequency in posterior cataract had significant differences compared with that in cortical and nuclear cataracts (P < 0.05); no significant differences were found between the cortical and nuclear cataracts (P > 0.05). The mean visual function index-14 (VF-14) showed significantly differences (F = 10.211, P = 0.000). When controlling for ages, there were no significant correlation between BCVA and straylight in cortical, nuclear and posterior cataracts (r = -0.227, r = -0.279, r = -0.373; P > 0.05). Correlations between BCVA and CS at 3, 6, 12 and 18 c/d were: r = 0.569, r = 0.517, r = 0.500, r = 0.449 (P < 0.01) in cortical cataracts; r = 0.657, r = 0.542, r = 0.513, r = 0.492 (P < 0.05) in nuclear cataracts; however, BCVA had no significant correlation with CS at spatial frequency any in posterior cataracts (P > 0.05). VF-14 significantly correlated with BCVA, straylight and CS in cortical and nuclear cataracts (r = 0.670, r = -0.740, r = 0.811, r = 0.826, r = 0.809, r = 0.720, P < 0.01; r = 0.731, r = -0.721, r = 0.816, r = 0.769, r = 0.738, r = 0.728, P ≤ 0.01); VF-14 correlated with straylight and CS (r = -0.910, r = 0.879, r = 0.896, r = 0.874, r = 0.844; P < 0.001), whereas VF-14 did not correlate with BCVA in posterior cataracts (r = 0.370, P = 0.090). CONCLUSIONS: Since visual acuity could underestimate the influence of cataract morphology on quality of vision, most notably in posterior cataract, straylight and CS are sensitive, complementary to BCVA when estimating real-world quality of vision of cataracts, and should be taken into account when considering therapy and cataract surgery.

Hydrogen peroxide induces p16(INK4a) through an AUF1-dependent manner.

Elevation of p16(INK4a) has been described as an important mechanism for hydrogen peroxide (H2O2)-induced replicative senescence. However, the mechanisms underlying remain unknown. In this study, we demonstrate an important role of RNA-binding protein AUF1-mediated mRNA turnover in H2O2-induced p16(INK4a) expression. The induction of p16 by H2O2 was accompanied with declined cytoplasmic AUF1 level. Accordingly, exposure of cells to H2O2 remarkably reduced the binding of AUF1 to p16 3'UTR and increased the half-life of an EGFP-p16-3'UTR chimeric transcript. In AUF1-silenced cells, the effect of H2O2 on p16 induction was abolished. Furthermore, in cells co-transfected with vectors expressing AUF1s, treatment with H2O2 failed to significantly reduce the expression of AUF1 and subsequently elevate the levels of p16. Moreover, HeLa cells overexpressing AUF1s were resistant to H2O2-induced senescence. Our results indicate that AUF1 is critical for H2O2-induced p16 expression and cellular senescence.

Photodynamic therapy with 5-aminolevulinic acid and diamino acid derivatives of protoporphyrin IX reduces papillomas in mice without eliminating transformation into squamous cell carcinoma of the skin.

Photodynamic therapy (PDT) is used to treat malignant and nonmalignant diseases. It is also used for cosmetological skin treatment. PDT is generally considered to have a low risk of carcinogenicity. However, instances of nonmalignant human tumors turning malignant have been linked to PDT. In this study, we used 5-aminolevulinic (ALA) acid and 3 water soluble photosensitizers-PP(Arg)(2), PP(Ser)(2)Arg(2), PP(Ala)(2)Arg(2), all diamino acid derivatives of protoporphyrin IX-to treat benign papillomas in FVB/N mice induced by 7,12-dimethylbenz(a)anthracene (DMBA)-12-O-tetradecanoyl-phorbol-13-acetate (TPA). Of these drugs, ALA and PP(Arg)(2) were found the most efficient. PDT reduced the number of papillomas, but with increasing effectiveness of the drugs, the risk of malignant transformation of the papillomas into squamous cell carcinomas increased. The underlying mechanisms are not clear and further investigations are needed.

A comparison of 5-aminolaevulinic acid- and its heptyl ester: dark cytotoxicity and protoporphyrin IX synthesis in human adenocarcinoma WiDr cells and in athymic nude mice healthy skin.

5-aminolevulinic acid heptyl ester was investigated in human adenocarcinoma WiDr cells and in healthy skin of athymic nude mice in comparison with 5-aminolevulinic acid (ALA). Incubation of WiDr cells with ALA and ALA heptyl ester resulted in production of protoporphyrin IX (PpIX). Concentrations higher than 0.01 mm of ALA heptyl ester and higher than 1 mm of ALA were cytotoxic. The dark cytotoxicity was not related to PpIX. Intracellular localization, photocytoxicity and photobleaching rate of PpIX were the same for both drugs, although a 100 times lower concentration of ALA heptyl ester (0.01 mm) was needed in comparison with ALA (1 mm) to induce the same level of PpIX. ALA heptyl ester, topically (but not systemically) applied, is a promising candidate for fluorescence diagnosis and photodynamic therapy. Special attention must be focused on the concentrations of ALA heptyl ester; as excess may lead to cytotoxicity and inefficient PpIX generation.

[Effects of three drying methods on the physical properties and drug delivery in chitosan microspheres].

OBJECTIVE: The purpose of this study is to investigate the effects of different drying methods on the physical properties and drug delivery of chitosan microspheres. METHODS: Three types of drying methods were utilized, including air drying and freeze drying after freezing at -20 ℃ (slow cooling) and at -80 ℃ (fast cooling). The physical properties of microspheres were characterized. Utilizing bovine serum albumin (BSA) as the model drug, the in-vitro release behaviors of drug-loaded beads were investigated. RESULTS: By comparing the physical properties of the different drying methods, the microspheres' diameters, porosities, and surface area were observed to increase successively from air drying and slow cooling to fast cooling, whereas the pore size and the swelling and degradation rates varied. The drug-loading experiments revealed that the loading capacity of air-dried microspheres was the lowest and the release rate was the slowest. Although the loading capacity of fast cooling microspheres was high, an obvious burst release was observed. The loading capacity of slow cooling microspheres was similar to that of the fast cooling microspheres and the loaded BSA can be released continuously. CONCLUSIONS: The results indicate that different drying methods can affect the physical properties of chitosan microspheres, which further influence drug loading and release.

miR-211 promotes lens epithelial cells apoptosis by targeting silent mating-type information regulation 2 homolog 1 in age-related cataracts.

AIM: To detect the expression of miR-211 in age-related cataract tissue, explore the effects of miR-211 on lens epithelial cell proliferation and apoptosis, and identify its target gene. METHODS: This study used real-time quantitative polymerase chain reaction (RT-qPCR) to measure the expression of miR-211 and its predicted target gene [silent mating-type information regulation 2 homolog 1 (SIRT1)] in 46 anterior lens capsules collected from age-related cataract patients. Human lens epithelial cell line (SRA01/04) cells were transfected with either miR-211 mimics, mimic controls, miR-211 inhibitors or inhibitor controls, 72h after transfection, miRNA and protein expression of SIRT1 were measured using RT-qPCR and Western blotting; then cells were exposed to 200 µmol/L H2O2 for 1h, whereupon cell viability was measured by MTS assay, caspase-3 assay was performed. Dual luciferase reporter assay was performed to verify the relationship between miR-211 of SIRT1. RESULTS: Compared to the control group, expression of miR-211 was significantly increased (P<0.001), the miRNA and protein expression of SIRT1 were significantly decreased (P<0.001) in the anterior lens capsules of patients with age-related cataracts. Relative to the control group, SIRT1 miRNA and protein levels in the miR-211 mimic group were significantly reduced, cell proliferation activity significantly decreased, and caspase-3 activity was significantly increased (P<0.001). In the miR-211 inhibitor group, SIRT1 miRNA and protein expression were significantly increased, cell proliferation activity significantly increased, and caspase-3 activity was significantly decreased (P<0.001). A dual luciferase reporter assay confirmed that SIRT1 is a direct target of miR-211. CONCLUSION: miR-211 is highly expressed in the anterior lens capsules of patients with age-related cataracts. By negatively regulating the expression of SIRT1, miR-211 promotes lens epithelial cell apoptosis and inhibits lens epithelial cell proliferation.

miR-24-p53 pathway evoked by oxidative stress promotes lens epithelial cell apoptosis in age-related cataracts.

MicroRNA-24 (miR-24) serves an important role in cell proliferation, migration and inflammation in various types of disease. In the present study, the biological function and molecular mechanism of miR­24 was investigated in association with the progression of age­associated cataracts. To the best of our knowledge the present study is the first to report that the expression of miR­24 was significantly increased in human anterior lens capsules affected by age­associated cataracts as well as lens epithelial cells (LECs) exposed to oxidative stress. Overexpression of miR­24 induced p53 expression and p53 was verified as a direct target of miR­24. Overexpression of miR­24 enhanced LEC death by directly targeting p53. The present study revealed that oxidative stress induced the upregulation of miR­24 and enhanced LEC death by directly targeting p53. These results suggest that the miR­24­p53 signaling pathway is involved in a novel mechanism of age­associated cataractogenesis and miR­24 may be a useful therapeutic target for age-associated cataracts.

miR-211 regulates the antioxidant function of lens epithelial cells affected by age-related cataracts.

AIM: To investigate the effects and mechanism of miR-211 in mediating the antioxidant function of lens epithelial cells affected by age-related cataracts. METHODS: Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect miR-211 expression in the anterior lens capsules of healthy people, the anterior lens capsules of patients with age-related cataracts, and human epithelial cell line (SRA01/04) cells exposed to oxidative stress. A 2', 7'-dichloro-fluorescein diacetate (DCFH-DA) probe was used to measure the levels of endogenous reactive oxygen species (ROS) in human lens epithelial cells (hLECs) exposed to 400 µmol/L H2O2 for 1h. SRA01/04 cells were transfected with either miR-211 mimics, mimic controls, miR-211 inhibitors or inhibitor controls. After 72h, these cells were exposed to 400 µmol/L H2O2 for 1h, then p53 and Bax mRNA expression were measured using RT-qPCR. p53 and Bax protein expression were also measured by Western blotting analysis. Finally, cell viability was assessed using an MTS assay. RESULTS: Compared to the control group, expression of miR-211 in the anterior lens capsules of age-related cataract patients and in SRA01/04 cells exposed to oxidative stress was significantly increased (P<0.001). Levels of endogenous ROS were significantly elevated in hLECs exposed to oxidative stress (P<0.001). Compared to the mimic control group, the hLECs in the miR-211 mimic group expressed significantly higher levels of p53 and Bax mRNA and protein while cell viability was significantly reduced (P<0.001). Conversely, p53 and Bax mRNA and protein expression were significantly reduced in the miR-211 inhibitor group as compared to the control group, while the cells in this group had much higher levels of cell viability (P<0.001). CONCLUSION: miR-211 is upregulated in the anterior lens capsules of age-related cataract patients. miR-211 decreased the antioxidative stress capacity of lens epithelial cells by upregulating p53 and Bax, while inhibiting cell proliferation and repair. This finding suggests that miR-211 may play a key role in the development of age-related cataracts.

Fabrication of Reduction-Sensitive Amphiphilic Cyclic Brush Copolymer for Controlled Drug Release.

The cyclic brush polymers, due to the unique topological structure, have shown in the previous studies higher delivery efficacy than the bottlebrush analogues as carriers for drug and gene transfer. However, to the best of knowledge, the preparation of reduction-sensitive cyclic brush polymers for drug delivery applications remains unexplored. For this purpose, a reduction-sensitive amphiphilic cyclic brush copolymer, poly(2-hydroxyethyl methacrylate-g-poly(ε-caprolactone)-disulfide link-poly(oligoethyleneglycol methacrylate)) (P(HEMA-g-PCL-SS-POEGMA)) with reducible block junctions bridging the hydrophobic PCL middle layer and the hydrophilic POEGMA outer corona is designed and synthesized successfully in this study via a "grafting from" approach using sequential ring-opening polymerization (ROP) and atom transfer free radical polymerization (ATRP) from a cyclic multimacroinitiator PHEMA. The resulting self-assembled unimolecular core-shell-corona (CSC) micelles show sufficient salt stability and efficient destabilization in the intracellular reducing environment for a promoted drug release toward a greater therapeutic efficacy relative to the reduction-insensitive analogues. The overall results demonstrate the reducible cyclic brush copolymers developed herein provides an elegant solution to the tradeoff between extracellular stability and intracellular high therapeutic efficacy toward efficient anticancer drug delivery.

Photodynamic therapy with di-l-arginine protoporphyrinate on WiDr human colon adenocarcinoma xenografts in athymic nude mice.

The fluorescence kinetics of a new photosensitizer for photodynamic therapy, di-l-arginine protoporphyrinate (PP(Arg)2), was studied in the skin of healthy mice. Furthermore, induction of necrosis in WiDr human colon adenocarcinoma xenografts in athymic nude mice was studied after photodynamic therapy (PDT) with PP(Arg)2. After intravenous administration of PP(Arg)2 maximal fluorescence was reached after 72h in normal mouse skin. Complete elimination of the drug from the mouse skin was not found even after 32 days. Exposure of WiDr tumours in mice to red light (λ=632nm, fluence 150J/cm(2), fluence rate 250mW/cm(2)) 24 and 72h after intravenous administration of 10mg/kg of PP(Arg)2 caused extensive tumour necrosis. Epidermal damage and infiltration of inflammatory cells was seen 24h after light exposure but not after 72h.

A new method for photodynamic therapy of melanotic melanoma -- effects of depigmentation with violet light photodynamic therapy.

Melanotic melanomas have a poor response to photodynamic therapy (PDT). The reason for this is that melanin absorbs light over the entire wavelength region used for PDT (400-750 nm). Photobleaching of melanin is an approach to overcome this obstacle. In the present work, reflectance spectroscopy was applied to study depigmentation of human and murine skin with different melanin contents, and effects induced by PDT with topical application of methyl 5-aminolevulinate (MAL) on B16F10 melanotic melanomas transplanted to nude mice. Depigmentation and inhibition of tumor growth after violet light (420 nm) exposure, red light (634 nm) exposure, and combinations of both were studied. Reflectance spectroscopy was suitable for evaluation of the pigmentation of both human and murine skin. Skin depigmentation leads to increase in reflectance. PDT with violet light bleached some of the melanin in the skin above the B16F10 melanomas, and possibly also in the upper part of the melanomas. This resulted in a larger growth inhibition of tumors first given PDT with violet light and then with red light compared to treatments using the reverse order of illumination, namely, red light before violet light. It is concluded that violet light PDT can bleach melanin in melanotic tumors and therefore increase their sensitivity to red light PDT. This finding indicates a new PDT modality that can be further developed for treatment of superficial melanotic melanomas and possibly other diseases where pigmentation is a problem.

Biological activity of 5-aminolevulinic acid and its methyl ester after storage under different conditions.

5-Aminolevulinic acid (ALA) is a natural precursor of protoporphyrin IX (PpIX) and heme in cells. Photodynamic therapy (PDT) utilizes a metabolic imbalance in cancer cells, leading to increased PpIX generation from exogenous ALA. Due to chemical instability of ALA in therapeutic concentrations at pH values larger than 5.0 and at high temperatures, it looses its activity by spontaneous dimerization to 2,5-dicarboxyethyl-3,6-dihydropyrazine (DHPY). ALA esters are now supplementing ALA in PDT, but little is known about their stability. We have studied the stability of ALA and its methyl ester (MAL) stored under different conditions (temperatures, pH values) by measuring their ability to generate PpIX. 100mM solutions of both compounds were found to be stable at pH 4 and at 4 degrees C. However, at pH 5.5 they lost almost 10% of the initial activity during 5days of storage at 4 degrees C. The fastest decay of ALA and MAL was seen at pH 7.4 and at 37 degrees C, and followed first order kinetics. At pH 7.4 and at 4 degrees C MAL lost its PpIX producing ability more slowly than at 37 degrees C. Our work shows that solutions should be prepared immediately before use and stored at low temperatures. The pH of stock solutions should not exceed 5.

In vitro and in vivo photosensitization by protoporphyrins possessing different lipophilicities and vertical localization in the membrane.

Photodynamic therapy (PDT) is being evaluated in clinical trials for treatment of various oncologic and ophthalmic diseases. The main cause for cell inactivation and retardation of tumor growth after photoactivation of sensitizers is very short-lived singlet oxygen molecules that are produced and have limited diffusion distances. In this paper we show that the extent of biological damage can be modulated by using protoporphyrin, which was modified to increase its lipophilicity, and which also places the tetrapyrrole core deeper within the membrane by the carboxylate groups being anchored at the lipid:water interface. The uptake of the parent molecule (PPIX) and its diheptanoic acid analogue (PPIXC6) by WiDR and CT26 cells was investigated by fluorescence microscopy and by fluorescence intensity from the cells. The uptake of PPIXC6 increased almost linearly with incubation length for over 24 h, whereas for PPIX only 1 h was needed to reach maximal intracellular concentration. Fluorescence microscopy of both cell lines indicated that both drugs were distributed diffusely in the plasma membrane and cytoplasm, but remained outside the nucleus. The efficiency of in vitro inactivation of WiDr and CT26 cells increased with the length of the alkylcarboxylic chain. Tumors in mice that were treated with PPIX-PDT grew more slowly than control tumors. However, tumors that were given PPIXC6 followed by light exposure showed a significant delay in their growth.