Three-dimensional miniature endoscopy.
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Animals↗
Biomedical subjects
T Hasan
Publications and source records attributed to T Hasan.
Methotrexate used in combination with aminolaevulinic acid for photodynamic killing of prostate cancer cells.
Photodynamic therapy (PDT) using 5-aminolaevulinic acid (ALA) to drive production of an intracellular photosensitiser, protoporphyrin IX (PpIX), is a promising cancer treatment. However, ALA-PDT is still suboptimal for thick or refractory tumours. Searching for new approaches, we tested a known inducer of cellular differentiation, methotrexate (MTX), in combination with ALA-PDT in LNCaP cells. Methotrexate alone promoted growth arrest, differentiation, and apoptosis. Methotrexate pretreatment (1 mg l(-1), 72 h) followed by ALA (0.3 mM, 4 h) resulted in a three-fold increase in intracellular PpIX, by biochemical and confocal analyses. After exposure to 512 nm light, killing was significantly enhanced in MTX-preconditioned cells. The reverse order of treatments, ALA-PDT followed by MTX, yielded no enhancement. Methotrexate caused a similar relative increase in PpIX, whether cells were incubated with ALA, methyl-ALA, or hexyl-ALA, arguing against a major effect upon ALA transport. Searching for an effect among porphyrin synthetic enzymes, we found that coproporphyrinogen oxidase (CPO) was increased three-fold by MTX at the mRNA and protein levels. Transfection of LNCaP cells with a CPO-expressing vector stimulated the accumulation of PpIX. Our data suggest that MTX, when used to modulate intracellular production of endogenous PpIX, may provide a new combination PDT approach for certain cancers.
Aminolevulinic Acid↗
Targeted optical imaging and photodynamic therapy.
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Neoplasms↗
Patch test reactions to cosmetic allergens in 1995-1997 and 2000-2002 in Finland--a multicentre study.
Contact sensitivity to cosmetics is common, but the sensitizing chemicals vary between countries and study periods. The present survey aimed at revealing the recent trends in patch test sensitivity with cosmetic chemicals in Finland. We report a retrospective multicentre survey of patch test reactions focusing on cosmetic-related substances and comparing the test results in 1995-97 with those in 2000-02. The most striking increases in the frequency of the patch test sensitivity were found with balsam of Peru and propolis from 4.0% to 6.2% (P < 0.001) and from 0.5% to 1.4% (P < 0.001), respectively, whereas the most prominent decreases were found with methylchloro/methylisothiazolinone and chlorhexidine diglugonate from 2.4% to 1.3% (P < 0.001) and from 1.2% to 0.5% (P < 0.001), respectively. The level of patch test sensitivity to methyldibromo glutaronitrile increased, although not significantly, from 1.0% to 1.5%. An increasing tendency was also found with hair dye chemicals 4-aminophenol and toluene-2,5-diamine or toluene-2,5-diamine sulfate from 1.3% to 3.8% and from 1.4% to 5.2%, respectively, while such a tendency was not found among permanent wave chemicals. The sensitivity level of fragrance mix remained the same (6% - 7%). We conclude that surveys revealing the state of sensitivity to cosmetic chemicals should be performed periodically in different countries.
Allergens↗
Occupational IgE-mediated allergy to a common house spider (Tegenaria domestica).
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Animals↗
Seasonal variation of disease activity of systemic lupus erythematosus in Finland: a 1 year follow up study.
OBJECTIVES: To study the role of different seasons in the disease activity of patients with systemic lupus erythematosus (SLE). Additionally, to evaluate whether the outdoor behaviour during the summer or a photoprovocation test affects disease activity. METHODS: 33 patients with SLE were examined by a rheumatologist and a dermatologist at a university hospital in winter, spring, and summer. The activity of SLE was assessed by the ECLAM index. Their outdoor behaviour was recorded by a questionnaire during the summer. In the winter, 12 patients were photoprovoked by ultraviolet A and B radiation on a small skin area. RESULTS: The ECLAM scores were higher in spring and tended to be higher in summer than in winter (p = 0.006 and p = 0.051). This finding, as well as the outdoor behaviour, were independent of the patients' own impression of their photosensitivity. Overall, the sun protection actions were inadequate. The photoprovocation had no statistical effect on disease activity, but one patient had a violent exacerbation of SLE manifestations shortly after the photoprovocation. CONCLUSIONS: In the northern climate SLE may be activated during the sunny season. Therefore, more effort should be focused on sun protection of patients with SLE.
Acute Disease↗
Pegylation of charged polymer-photosensitiser conjugates: effects on photodynamic efficacy.
Conjugates between photosensitisers (PS) and charged polymeric carriers are under investigation for photodynamic therapy of cancer and may allow targeting to certain cell types or compartments in tumours. Covalent attachment of polyethylene glycol to macromolecules (pegylation) may alter their pharmacokinetics, cell type targeting, and photophysical properties. Macrophages may take up large amounts of aggregated PS, thus lessening the selectivity for cancer cells in tumours. We investigated the effect of pegylation on the uptake and phototoxicity of poly-L-lysine chlorin(e6) conjugates with either cationic or anionic charges in two cell lines, human ovarian cancer cells and mouse macrophages. The cationic conjugate after pegylation became less aggregated, consumed less oxygen and had reduced cellular uptake. However, the phototoxicity corrected for cellular uptake increased three- to five-fold. In contrast, the anionic succinylated conjugate on pegylation became more aggregated, consumed similar amounts of oxygen, and had higher cellular uptake. The anionic conjugate showed the highest relative phototoxicity towards both the cell lines (compared to the other three conjugates) and it decreased most towards the macrophages after pegylation. Pegylation reduced the amount of oxygen consumed per chlorin(e6) molecule when photosensitised cells were illuminated. These in vitro studies suggest that pegylation alters the phototoxicity of PS conjugates depending on the effect produced on the aggregation state.
Animals↗
Differentiation enhances aminolevulinic acid-dependent photodynamic treatment of LNCaP prostate cancer cells.
Photodynamic therapy using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) may be applied to the treatment of neoplasms in a variety of organs. In order to enhance existing regimens of photodynamic therapy, we investigated the effects of adding differentiation therapy to photodynamic therapy in human prostate cancer cells in vitro. The objective of differentiation therapy per se is to reverse the lack of differentiation in cancer cells using pharmacological agents. The motivation for this study was to exploit the differentiation-dependent expression of some heme enzymes to enhance tumour cell toxicity of ALA-photodynamic therapy. A short course of differentiation therapy was applied to increase PpIX formation during subsequent ALA exposure. Using the synthetic androgen R1881, isomers of retinoic acid, and analogues of vitamin D for 3 to 4 days, exogenous ALA-dependent PpIX formation in LNCaP cells was increased, along with markers for growth arrest and for differentiation. As a consequence of higher PpIX levels, cytotoxic effects of visible light exposure were also enhanced. Short-term differentiation therapy increased not only the overall PpIX production but also reduced that fraction of cells that contained low PpIX levels as demonstrated by flow cytometry and fluorescence microscopy. This study suggests that it will be feasible to develop protocols combining short-term differentiation therapy with photodynamic therapy for enhanced photosensitisation.
Aminolevulinic Acid↗
Pegylation of a chlorin(e6) polymer conjugate increases tumor targeting of photosensitizer.
Photodynamic therapy is emerging as a viable modality for the treatment of many cancers. A limiting factor in its use against intracavity tumors such as disseminated ovarian cancer is insufficient selectivity of the photosensitizer for tumor compared with normal tissue. We report on an approach to improve tumor targeting by exploiting differences between cell types and by chemical modification of a photosensitizer conjugate. Attachment of polyethylene glycol (pegylation) to a polyacetylated conjugate between poly-l-lysine and chlorin(e6) increased the relative phototoxicity in vitro toward an ovarian cancer cell line (OVCAR-5) while reducing it toward a macrophage cell line (J774), compared with the nonpegylated conjugate. Surprisingly, the increased phototoxicity of the pegylated conjugate correlated with reduced oxygen consumption. Pegylation also reduced the tendency of the conjugate to aggregate and reduced the consumption of oxygen when the conjugates were illuminated in solution in serum containing medium, suggesting a switch in photochemical mechanism from type II (singlet oxygen) to type I (radicals or electron transfer). Pegylation led to more mitochondrial localization as shown by confocal fluorescence microscopy in OVCAR-5 cells, and, on illumination, produced a switch in cell death mechanism toward apoptosis not seen with J774 cells. Conjugates were injected i.p. into nude mice bearing i.p. OVCAR-5 tumors, and the pegylated conjugate gave higher amounts of photosensitizer in tumor and higher tumor:normal tissue ratios and increased the depth to which the chlorin(e6) penetrated into the peritoneal wall. Taken together, these results suggest that pegylation of a polymer-photosensitizer conjugate improves tumor-targeting and may increase the efficacy of photodynamic therapy for ovarian cancer.
Animals↗
Epidermal growth factor receptor-targeted immunophotodiagnosis and photoimmunotherapy of oral precancer in vivo.
Immunophotodiagnosis uses a fluorescence-labeled monoclonal antibody (MAb) that recognizes a tumor-associated antigen to image the fluorescence emitted from the fluorophore-bound MAb that has localized in the tissue. It may be used to diagnose malignant or precancerous lesions, to delineate the margins for tumor resection, or as a feedback mechanism to assess response to treatment. In oral precancer, the epidermal growth factor receptor (EGFR) is overexpressed and could be used as a marker for early detection or as a target for therapy. The goal of this study was to test an anti-EGFR MAb (C225) coupled to either the near-infrared fluorescent dye N,N'-di-carboxypentyl-indodicarbocyanine-5,5'-disulfonic acid for detection or a photochemically active dye (chlorin(e6)) for therapy of early premalignancy in the hamster cheek pouch carcinogenesis model. Fluorescence levels in the carcinogen-treated tissue correlated with the histological stage of the lesions when the C225-N,N'-di-carboxypentyl-indodicarbocyanine-5,5'-disulfonic acid conjugate was used but did not do so with the irrelevant conjugates. Discrete areas of clinically normal mucosa with high fluorescence (hot spots) were subsequently shown by histology to contain dysplastic areas. The best contrast between normal and carcinogen-treated cheek pouches was found at 4-8 days after injection. To test the potential of immunophotodiagnosis as a feedback modality for therapeutic intervention, experiments were conducted with the same MAb conjugated to chlorin(e6) followed by illumination to reduce expression of the EGFR by a photodynamic effect. Subsequent immunophotodiagnosis showed that this treatment led to a significant reduction in fluorescence in the carcinogen-treated cheek pouch compared with nonilluminated areas. This difference between illuminated and dark areas was not seen in the normal cheek pouch. Taken together, the results demonstrate the potential for development of immunophotodiagnosis as a diagnostic tool and as a method of monitoring response to therapy and that the EGFR may be an appropriate target in head and neck cancer.
Animals↗
Selection of cell binding and internalizing epidermal growth factor receptor antibodies from a phage display library.
The first step in developing a targeted cancer therapeutic is generating a ligand that binds to a receptor which is either tumor specific or sufficiently overexpressed in tumors to provide targeting specificity. For this work, we generated human monoclonal antibodies to the EGF receptor (EGFR), an antigen overexpressed on many solid tumors. Single chain Fv (scFv) antibody fragments were directly selected by panning a phage display library on tumor cells (A431) overexpressing EGFR or Chinese hamster ovary cells (CHO/EGFR cells) transfected with the EGFR gene and recovering endocytosed phage from within the cell. Three unique scFvs were isolated, two from selections on A431 cells and two from selections on CHO/EGFR cells. All three scFv bound native receptor as expressed on a panel of tumor cells and did not bind EGFR negative cells. Phage antibodies and multivalent immunoliposomes constructed from scFv were endocytosed by EGFR expressing cells as shown by confocal microscopy. Native scFv primarily stained the cell surface, with less staining intracellularly. The results demonstrate how phage antibodies binding native cell surface receptors can be directly selected on overexpressing cell lines or transfected cells. Use of a transfected cell line allows selection of antibodies to native receptors without the need for protein expression and purification, significantly speeding the generation of targeting antibodies to genomic sequences. Depending upon the format used, the antibodies can be used to deliver molecules to the cell surface or intracellularly.
Animals↗
A photobiological and photophysical-based study of phototoxicity of two chlorins.
To understand the fundamental determinants of phototoxic efficacy and absorbed photodynamic dose, the triplet state and photobleaching quantum yields in living cells, cellular uptake, intracellular localization, and correlation with cell viability were studied for the two purpurins tin ethyl etiopurpurin 1 (SnET2) and tin octaethylbenzochlorin (SnOEBC) in ovarian cancer cells (OVCAR5). Although the triplet yields of these two photosensitizers were not significantly affected by cellular incorporation, the photobleaching yields were shown to be 3 orders of magnitude higher for cellular-bound sensitizer than for free or albumin-bound photosensitizer and higher for SnET2 than for SnOEBC for all of the cases. The intracellular concentration of SnOEBC was half that of SnET2 after 3 h- and 24 h-incubation times for both 0.1 microM and 1.0 microM incubation concentrations. Despite the lower concentrations of SnOEBC, the phototoxicity of the two photosensitizers was comparable at 1-microM incubation concentration and was up to 10-fold higher for SnOEBC at the lower concentration. The subcellular localization established using confocal microscopy and molecular probes showed that both photosensitizers were primarily lysosomally localized. SnOEBC, however, had an extra-lysosomal, mitochondrial localization component. The photophysical measurements allowed calculation of the intracellular singlet oxygen production, which indicated that the photosensitizer-light dose reciprocity was limited by photobleaching for SnET2 but only minimally for SnOEBC, and this was confirmed through cell-survival studies. Taken together, these data indicate that the critical determinant of differences in phototoxicity between the two molecules was their relative rates of photobleaching and their subcellular localization. The study points to the importance of combining photosensitizer uptake and localization with photophysical measurements in the relevant biological milieu to reasonably interpret and/or predict photosensitization efficacies.
Cell Survival↗
A multicenter study of patch test reactions with dental screening series.
BACKGROUND: Dental products contain many allergens, and may cause problems both for patients undergoing dental treatment and for dental personnel because of occupational exposure. Individual patch test clinics may not study sufficient numbers of patients to collect reliable data on uncommon allergens. OBJECTIVE: To collect information on dental allergens based on a multicenter study. MATERIALS AND METHODS: The Finnish Contact Dermatitis Group tested more than 4,000 patients (for most allergens, 2,300 to 2,600 patients) with dental screening series. Conventional patch testing was performed. The total number and percentage of irritant (scored as irritant [IR] or doubtful [?]) and allergic (scored as +, ++, or +++) patch test reactions, respectively, were calculated, as well as the highest and lowest percentage of allergic patch test reactions recorded by the different patch test clinics. A reaction index (RI) was calculated, giving information on the irritancy of the patch test substances. RESULTS: The most frequent allergic patch test reactions were caused by nickel (14.6%), ammoniated mercury (13%), mercury (10.3%), gold (7.7%), benzoic acid (4.3%), palladium (4.2%) and cobalt (4.1%). 2-hydroxyethyl methacrylate (2.8%) provoked most of the reactions caused by (meth)acrylates. Menthol, peppermint oil, ammonium tetrachloroplatinate, and amalgam alloying metals provoked no (neither allergic nor irritant) patch test reactions. CONCLUSION: Patch testing with allergens in the dental screening series, including (meth)acrylates and mercury, needs to be performed to detect contact allergy to dental products.
Allergens↗
Experimental photoimmunotherapy of hepatic metastases of colorectal cancer with a 17.1A chlorin(e6) immunoconjugate.
Photoimmunotherapy (using a monoclonal antibody-targeted photosensitizer and red light) may be a strategy to overcome the limitations inherent in photodynamic therapy of liver tumors. The aims of this study were (a) to test the efficacy of selective treatment of hepatic metastases of colorectal cancer in an orthotopic murine xenograft using the murine monoclonal antibody 17.1A conjugated to the photosensitizer chlorin(e6), and (b) to compare the tumor response after the same light dose was delivered at two different fluence rates. Based on previous biodistribution studies that had shown that the photoimmunoconjugate with a polyanionic charge had both a higher absolute tumor chlorin(e6) content and a greater tumor:normal liver ratio than those obtained with a photoimmunoconjugate bearing a polycationic charge, mice were treated 3 h after i.v. injection of the polyanionic 17.1A chlorin(e6) conjugate or unconjugated photosensitizer. Red light was delivered into the liver tumor by an interstitial fiber, and tumor response end points were total tumor weight in the short term and survival in the long term. There was a highly significant reduction (<20% of controls; P = 0.0035) in the weight of the tumors in the mice treated with photoimmunotherapy, and the median survival increased from 62.5 to 102 days (P = 0.015). Photodynamic therapy with free chlorin(e6) produced a smaller decrease in tumor weight and a smaller extension of survival, neither of which were statistically significant. A comparison of photoimmunotherapy with 10 J of light delivered at 30 or 300 mW showed that the higher fluence rate prolonged survival significantly more than the lower fluence rate. This may have been because the high fluence rate gave a contribution of laser-induced hyperthermia to the photodamage. Correlation studies showed that the amount of normal liver remaining at necropsy correlated best with survival. Photoimmunotherapy shows efficacy in destroying liver tumors, and future studies should maximize selectivity to minimize the destruction of normal liver.
Animals↗
Synthetic inhibitor of matrix metalloproteinases (batimastat) reduces prostate cancer growth in an orthotopic rat model.
BACKGROUND: Increased concentrations of metalloproteinases are associated with the invasive and metastatic behavior of several human malignant tumors. Normally, enzymatic activity is tightly regulated by nonspecific mechanisms and specific inhibitors. The aim of the study was to determine the potential of a synthetic metalloproteinase inhibitor, batimastat, to show its in vitro effect on MatLyLu cancer cells and its in vivo effect on tumor growth in orthotopic cancer (R3327 Dunning tumor) in rats. METHODS: In vitro, a dose response curve of batimastat was generated over 4 days using the MTT assay. Prostate cancer was injected in vivo in male Copenhagen rats by inoculating R3327 Dunning tumor cells (MatLyLu) into the ventral prostatic lobe of 30 rats. Each of 10 rats received batimastat (30 mg/kg body weight) or vehicle administered once a day by i.p. application beginning the day of cell inoculation. Ten rats remained untreated. The effect on local tumor growth was evaluated by measuring tumor weights 20 days after tumor cell inoculation. RESULTS: Significant inhibition of tumor cell proliferation in vitro occurred at 400 and 4,000 ng/ml batimastat. After orthotopic cell inoculation, tumors grew to mean weights of 18.9 g in the control group without treatment, to 22.3 g in the vehicle group, and to 11.1 g in the treated group. In comparison to the control group and to the vehicle group, tumor weights increased significantly less under treatment with batimastat. CONCLUSIONS: Batimastat is able to reduce tumor growth in the standard prostate cancer model. Using this model, activity against cancer progression of future inhibitory agents can be reliably assessed.
Animals↗
Intraperitoneal photoimmunotherapy of ovarian carcinoma xenografts in nude mice using charged photoimmunoconjugates.
OBJECTIVE: The objective of this study was to compare the efficacy of photoimmunoconjugates with cationic and anionic molecular charges on intraperitoneal photoimmunotherapy of ovarian cancer xenografts in nude mice. METHODS: The photosensitizer chlorin(e6) (c(e6)) was conjugated via a poly-l-lysine linker to the F(ab')(2) fragment of the murine anti-ovarian cancer monoclonal antibody OC125, resulting in a photoimmunoconjugate with a pronounced cationic charge. Alternatively, by succinylating the poly-l-lysine conjugate, a photoimmunoconjugate with a pronounced anionic charge was obtained. A murine model of ovarian cancer derived from intraperitoneal inoculation of NIH:OVCAR-5 cells was employed. The conjugate was injected intraperitoneally followed after 3 h by red light delivered through a fiber into the peritoneal cavity. These photoimmunotherapy treatments were repeated three times, and the results obtained with the anionic and cationic photoimmunoconjugates were compared with those obtained with free c(e6) and control. The extent of residual macroscopic disease and death from disease were the evaluable outcomes for tumoricidal and survival studies, respectively. RESULTS: In contrast to other intraperitoneal photosensitizers, mice showed no systemic toxicity or morbidity from the treatment. In this initial study the mean residual tumor weights in all treatment groups ranged from 33 to 73 mg, as compared with 330 mg in untreated controls (P < 0.0001), and the response to the cationic conjugate was significantly better than that to the anionic conjugate or free c(e6) (P < 0.005). The median survival for mice treated with cationic photoimmunoconjugate was 41 days, compared with 35 days in controls (P = 0.009). CONCLUSION: Photoimmunotherapy with a cationic photoimmunoconjugate produces results superior to those obtained with an anionic conjugate, and further optimization of the treatment regimen may lead to a potential treatment for advanced ovarian cancer.
Animals↗
Laser-induced hyperthermia in rat prostate cancer: role of site of tumor implantation.
OBJECTIVES: To investigate the importance of the site of tumor implantation on the treatment response to laser-induced hyperthermia (LIH) of rat prostate cancer (PCa), because interventional manipulations of PCa have been reported to increase metastatic dissemination. METHODS: Seven to nine days after either subcutaneous or orthotopic implantation of MatLyLu cells, LIH (46.5 degrees C) was induced using pulsed irradiations of a neodymium:yttrium-aluminum-garnet laser. Both local control and distant metastases were evaluated. Plasma metalloproteinase 9 (MMP-9) was tested as a possible marker of PCa progression and LIH response. RESULTS: Twelve days after LIH treatment of subcutaneous tumors, the volumes were reduced by 64% after 8 minutes of irradiation, 73% after 10 minutes, 81% after 15 minutes, and 91.1% after 20 minutes. In the orthotopic model, the corresponding tumor reductions were 44% after 10 minutes, 61% after 20 minutes, and 65% after 30 minutes. Lung metastases were observed in only 1 animal with subcutaneous tumors. In contrast, 86% of the orthotopic tumor-bearing animals treated for 30 minutes had lung metastases compared with 23% of the untreated tumor-bearing rats. MMP-9 expression was detected in both orthotopic and subcutaneous tumor tissue and in the plasma of tumor-bearing rats. The prostate tissue of healthy rats and subcutaneous tumor-bearing rats was devoid of MMP-9. The plasma levels of MMP-9 showed a trend toward direct correlation with local tumor control but no correlation with the incidence of metastasis. CONCLUSIONS: These data emphasize the importance of the site of tumor implantation for evaluation of the efficacy of therapeutic interventions and may warrant further studies before widespread clinical application of LIH as monotherapy.
Animals↗