Simultaneous defeat of MCF7 and MDA-MB-231 resistances by a hypericin PDT-tamoxifen hybrid therapy

Currently the greatest challenge in oncology is the lack of homogeneity of the lesions where different cell components respond differently to treatment. There is growing consensus that monotherapies are insufficient to eradicate the disease and there is an unmet need for more potent combinatorial treatments. We have previously shown that hypericin photodynamic therapy (HYP-PDT) triggers electron transport chain (ETC) inhibition in cell mitochondria. We have also shown that tamoxifen (TAM) enhances cytotoxicity in cells with high respiration, when combined with ETC inhibitors. Herein we introduce a synergistic treatment based on TAM chemotherapy and HYP-PDT. We tested this novel combinatorial treatment (HYPERTAM) in two metabolically different breast cancer cell lines, the triple-negative MDA-MB-231 and the estrogen-receptor-positive MCF7, the former being quite sensitive to HYP-PDT while the latter very responsive to TAM treatment. In addition, we investigated the mode of death, effect of lipid peroxidation, and the effect on cell metabolism. The results were quite astounding. HYPERTAM exhibited over 90% cytotoxicity in both cell lines. This cytotoxicity was in the form of both necrosis and autophagy, while high levels of lipid peroxidation were observed in both cell lines. We, consequently, translated our research to an in vivo pilot study encompassing the MDA-MB-231 and MCF7 tumor models in NOD SCID-γ immunocompromised mice. Both treatment cohorts responded very positively to HYPERTRAM, which significantly prolonged mice survival. HYPERTAM is a potent, synergistic modality, which may lay the foundations for a novel, composite anticancer treatment, effective in diverse tumor types.

Pharmacophore-based discovery of 2-(phenylamino)aceto-hydrazides as potent eosinophil peroxidase (EPO) inhibitors

There is an increasing interest in developing novel eosinophil peroxidase (EPO) inhibitors, in order to provide new treatment strategies against chronic inflammatory and neurodegenerative diseases caused by eosinophilic disorder. Within this study, a ligand-based pharmacophore model for EPO inhibitors was generated and used for in silico screening of large 3 D molecular structure databases, containing more than 4 million compounds. Hits obtained were clustered and a total of 277 compounds were selected for biological assessment. A class of 2-(phenyl)amino-aceto-hydrazides with different substitution pattern on the aromatic ring was found to contain the most potent EPO inhibitors, exhibiting IC₅₀ values down to 10 nM. The generated pharmacophore model therefore, represents a valuable tool for the selection of compounds for biological testing. The compounds identified as potent EPO inhibitors will serve to initiate a hit to lead and lead optimisation program for the development of new therapeutics against eosinophilic disorders.

The diverse roles of glutathione-associated cell resistance against hypericin photodynamic therapy

The diverse responses of different cancers to treatments such as photodynamic therapy of cancer (PDT) have fueled a growing need for reliable predictive markers for treatment outcome. In the present work we have studied the differential response of two phenotypically and genotypically different breast adenocarcinoma cell lines, MCF7 and MDA-MB-231, to hypericin PDT (HYP-PDT). MDA-MB-231 cells were 70% more sensitive to HYP PDT than MCF7 cells at LD50. MCF7 were found to express a substantially higher level of glutathione peroxidase (GPX4) than MDA-MB-231, while MDA-MB-231 differentially expressed glutathione-S-transferase (GSTP1), mainly used for xenobiotic detoxification. Eighty % reduction of intracellular glutathione (GSH) by buthionine sulfoximine (BSO), largely enhanced the sensitivity of the GSTP1 expressing MDA-MB-231 cells to HYP-PDT, but not in MCF7 cells. Further inhibition of the GSH reduction however by carmustine (BCNU) resulted in an enhanced sensitivity of MCF7 to HYP-PDT. HYP loading studies suggested that HYP can be a substrate of GSTP for GSH conjugation as BSO enhanced the cellular HYP accumulation by 20% in MDA-MB-231 cells, but not in MCF7 cells. Studies in solutions showed that L-cysteine can bind the GSTP substrate CDNB in the absence of GSTP. This means that the GSTP-lacking MCF7 may use L-cysteine for xenobiotic detoxification, especially during GSH synthesis inhibition, which leads to L-cysteine build-up. This was confirmed by the lowered accumulation of HYP in both cell lines in the presence of BSO and the L-cysteine source NAC. NAC reduced the sensitivity of MCF7, but not MDA-MB-231, cells to HYP PDT which is in accordance with the antioxidant effects of L-cysteine and its potential as a GSTP substrate. As a conclusion we have herein shown that the different GSH based cell defense mechanisms can be utilized as predictive markers for the outcome of PDT and as a guide for selecting optimal combination strategies.

Back to the roots: photodynamic inactivation of bacteria based on water-soluble curcumin bound to polyvinylpyrrolidone as a photosensitizer

Photodynamic inactivation (PDI), the light-induced and photosensitizer-mediated overproduction of reactive oxygen species in microorganisms, represents a convincing approach to treat infections with (multi-resistant) pathogens. Due to its favourable photoactive properties combined with excellent biocompatibility, curcumin derived from the roots of turmeric (Curcuma longa) has been identified as an advantageous photosensitizer for PDI. To overcome the poor water solubility and the rapid decay of the natural substance at physiological pH, we examined the applicability of polyvinylpyrrolidone curcumin (PVP-C) in an acidified aqueous solution (solubility of PVP-C up to 2.7 mM) for photoinactivation of Gram(+) and Gram(-) bacteria. Five micromolar PVP-C incubated for 5 minutes and illuminated using a blue light LED array (435 ± 10 nm, 33.8 J cm(-2)) resulted in a >6 log10 reduction of the number of viable Staphylococcus aureus. At this concentration, longer incubation periods result in a lower phototoxicity, most likely due to degeneration of curcumin. Upon an increase of the PVP-C concentration to 50 μM (incubation for 15 or 25 min) a complete eradication of Staphylococcus aureus can be achieved. As expected for a non-cationic photosensitizer, cell wall permeabilization with CaCl2 prior to addition of 50 μM PVP-C for 15 min is necessary to induce a drop in the count of the Gram(-) Escherichia coli for more than 3 log10. As both constituents of the formulation, curcumin (E number E100) and polyvinylpyrrolidone (E1201), have been approved as food additives, a PDI based on PCP-C might allow for a very sparing clinical application (e.g. for disinfection of wounds) or even for employment in aseptic production of foodstuffs.

How to make hypericin water-soluble

Hypericin, isolated from Hypericum perforatum, is an effective photodynamic substance as demonstrated by various studies. Practical forms of applications of hypericin solutions for systemic use and introduction into body cavities are, however, lacking. We developed an aqueous solution of hypericin non-covalently bound to polyvinylpyrrolidone (PVP). PVP is a poly-N-vinylamide of various degrees of polymerization and forms of intermolecular crosslinks suitable for diagnostic and therapeutic applications. We used PVP (molecular weights of PVP between 10 kD and 40 kD) as a complex forming agent to prepare hypericin for photodynamic therapy and diagnostics. In pure water, hypericin forms aggregates which are non-soluble and non-fluorescent. The hypericin-PVP complex binds more than 1000 mg of hypericin in presence of 100 g PVP or less and is soluble in 1 liter of pure water. Aqueous complex solutions of hypericin-PVP display a characteristic absorption spectrum and fluorescence emission band around 600 nm wavelength. Varying concentrations of hypericin do not cause a blue- or red-shift in the absorption maximum at 595 nm. Excitation at 200 nm to 500 nm leads to emission at 590 nm; a property conducive to diagnostic investigations both in vitro and in vivo. Furthermore, hypericin-PVP exhibits high photostability in the presence of oxygen and broad band light which ensures reproducible photodynamic therapy and diagnosis.

CONCLUSION

Hypericin forms liquid molecular chromophore complexes in water when bound to PVP thus allowing investigations in biological media.

Hypericin - The Facts About a Controversial Agent

Hypericin is a naturally occurring substance found in the common St. John's Wort (Hypericum species) and can also be synthesized from the anthraquinone derivative emodin. As the main component of Hypericum perforatum, it has traditionally been used throughout the history of folk medicine. In the last three decades, hypericin has also become the subject of intensive biochemical research and is proving to be a multifunctional agent in drug and medicinal applications. Recent studies report antidepressive, antineoplastic, antitumor and antiviral (human immunodeficiency and hepatitis C virus) activities of hypericin; intriguing information even if confirmation of data is incomplete and mechanisms of these activities still remain largely unexplained. In other contemporary studies, screening hypericin for inhibitory effects on various pharmaceutically important enzymes such as MAO (monoaminoxidase), PKC (protein kinase C), dopamine-beta-hydroxylase, reverse transcriptase, telomerase and CYP (cytochrome P450), has yielded results supporting therapeutic potential. Research of hypericin and its effect on GABA-activated (gamma amino butyric acid) currents and NMDA (N-methyl-D-aspartat) receptors also indicate the therapeutic potential of this substance whereby new insights in stroke research (apoplexy) are expected. Also in the relatively newly established fields of medical photochemistry and photobiology, intensive research reveals hypericin to be a promising novel therapeutic and diagnostic agent in treatment and detection of cancer (photodynamic activation of free radical production). Hypericin is not new to the research community, but it is achieving a new and promising status as an effective agent in medical diagnostic and therapeutic applications. New, although controversial data, over the recent years dictate further research, re-evaluation and discussion of this substance. Our up-to-date summary of hypericin, its activities and potentials, is aimed to contribute to this process.

Photodynamic effect of hypericin and a water-soluble derivative on isolated crayfish neuron and surrounding glial cells

Hypericin (Hyp) has been proposed as a fluorochrome for fluorescence diagnostics and as a photosensitizer for photodynamic therapy of cancer. However, its insolubility in water is a serious drawback. A novel water-soluble hypericin derivative (Hyp-S) has been constructed, using polyvinylpyrrolidone as a carrier. We used the crayfish stretch receptor, consisting of receptor neuron and satellite glial cells, for comparison of the photodynamic effects of Hyp and Hyp-S. Hyp-S was more toxic in the dark than Hyp and inactivated the neurons at concentrations exceeding 4 microM while Hyp was toxic to the neurons only at the concentrations larger than 20 microM. Electrophysiological investigations revealed polyphasic neuron responses to photosensitization with Hyp as well as with Hyp-S (1 microM concentration, 30 min incubation; irradiation with filtered light from a lamp with an emission maximum near 600 nm and an intensity of 0.2 W/cm2). In the concentration range 1-4 microM Hyp-S was more phototoxic than Hyp. Fluorescence microscopy showed that both sensitizers were predominately localized in the glial envelope surrounding the neuron. A minor fraction of hypericin was found in the neuron perinuclear area rich in cytoplasm organelles. This suggests the potential application of Hyp and Hyp-S for visualization and selective photodynamic treatment of malignant gliomas.

Dehydroascorbic acid in urine as a possible indicator of surgical stress

BACKGROUND/AIM

L-Ascorbic acid (AA) is the predominant circulating form of vitamin C found in human blood. It has been hypothesized that surgical stress increases the vitamin C metabolite dehydroascorbic acid (DHAA). Vitamin C is mainly excreted through the kidneys. In this study, the ratio of AA to DHAA excreted in urine was determined in patients who had undergone total hip joint endoprosthesis surgery (n = 12), and the results were compared with data obtained from healthy controls (n = 12).

METHODS

All subjects received 1,000 mg sodium ascorbate intravenously three times a day (every 8 h) for 8 days, starting 2 days prior to surgery. Total urine was collected daily while subsequent determinations of AA and DHAA were performed photometrically.

RESULTS

Administration of vitamin C led to average daily excretions of the combined products AA + DHAA of 2,343 +/- 438 mg/day (mean value +/- confidence intervals). The initial average ratio DHAA/AA of all 24 probands was 0.064 (6% DHAA; 153 +/- 76 mg/day). One day after surgery, an increase in the DHAA/AA ratio to 0.165 (15% DHAA; 332 +/- 107 mg/day) was measured in the patients. The ratio decreased 2 days after surgery and returned to normal within 5 days.

CONCLUSION

Our data indicate that surgery increases the oxidation of AA and urinary excretion of DHAA, as a result of the enhanced formation of free radicals.

Cold-knife conization versus photodynamic therapy with topical 5-aminolevulinic acid (5-ALA) in cervical intraepithelial neoplasia (CIN) II with associated human papillomavirus infection: a comparison of preliminary results

BACKGROUND

The optimal treatment of preinvasive cervical lesions is still not clear as all surgical techniques cause substantial cervical stroma destruction with the risk of a possible incompetent cervix. Photodynamic therapy can preserve fertility due to selective tissue destruction. The aim of the present study was to compare the efficacy of cold-knife conization versus photodynamic therapy with topical 5-aminolevulinic acid in eradicating cervical intraepithelial neoplasia (CIN) II and associated HPV infection.

PATIENTS AND METHODS

Eleven HPV-positive non-pregnant women were selected for photodynamic therapy (PDT). To be eligible for this procedure superficial cervical PAP smears as well as colposcopic biopsies performed before therapy had to show CIN II with the lesion involving at least 15% of the cervix and being colposcopically visible. The deep endocervical PAP smear had to show normal endocervical epithelium. The next (following each PDT) 11 HPV-positive women with CIN II treated with cold-knife conization were used as a control group. The cervical sampling for HPV DNA was performed 3 months after conization and PDT. Patients were followed-up for 1 year with cytological smears and colposcopy at the outpatient department of the hospital.

RESULTS

Follow-up at three months revealed that HPV was eradicated by both techniques in 73%. After 12 months follow-up, 100 vs. 91% (conization vs. PDT) of the patients were disease-free. No systemic side-effects and no local necrosis, sloughing or scarring occurred due to PDT. One patient treated with PDT presented with a relapsing suspicious PAP smear and an abnormal white colposcopic lesion after application of acetic acid 6 months post-PDT. A subsequent conization was performed and revealed a CIN I lesion. No statistically significant differences concerning HPV eradication (p > 0.05) and recurrence (p > 0.05) could be observed between the two methods.

CONCLUSION

The results presented in this study indicate that topical PDT with 5-ALA is in most cases a successful treatment of CIN II with comparable results to cold-knife conization. In contrast to cold-knife conization, PDT causes no substantial cervical stroma destruction with the risk of a possible subsequent incompetent cervix. Also the feasibility of topical PDT on an outpatient basis, the lack of significant post-treatment complications and the cost effectiveness make the topical approach with PDT preferable in selected circumstances. Due to the potential risk of invasive cancer with metastatic spread, patient's selection criteria must be strict and a pretreatment histological examination is obligatory.

Photodynamic action of some sensitizers by photooxidation of luminol

We report the development of a novel simple experimental method which allows the comparison of new photosensitizers based on their production of reactive oxygen species. A high-performance liquid chromatography (HPLC) assay permits the monitoring of several substances (sensitizer, reactant and oxidized end product) simultaneously on a single chromatogram. Photoreactions were monitored throughout their course by the HPLC assay surveying the sensitizers' efficiency of singlet oxygen production by the oxidative decomposition of luminol. Several photosensitizers were tested: Rose Bengal, Methylene Blue, Protoporphyrin IX, Photosan III, Photofrin, Hypericin and Pseudohypericin. Additionally, photoreactions were monitored by a standard pO(2) detection system. The measurements of the two detection methods were strongly correlated. Rose Bengal proved to be the most efficient photosensitizer, clearly decreasing the luminol concentration and causing a corresponding increase in aminophthalic acid. Our experiments show that when factors necessary for photochemical reactions are absent or are blocked (antioxidants), no reaction can be detected.

Photodynamic action of meta-tetrahydroxyphenylchlorin (mTHPC) on an ovarian cancer cell line

Meta-tetrahydroxyphenylchlorin (mTHPC) exhibits significant cytotoxicity against a variety of human cells in culture in combination with light, but also in dark reaction. The ovarian cancer cell line SK-OV3 was incubated with various concentrations of mTHPC and in comparison with Taxol and Cisplatin: then the effect on cell growth was determined. mTHPC exhibited an IC50 of 0.9 muM after 24 hours incubation (IC50 of 1.25 after 2 hours), whereas Cisplatin and Taxol, which, have been used as first line agents for the treatment of ovarian carcinomas, inhibited cell proliferation with an IC50 concentration of 4.6 muM and 78 nM after 24 hours incubation, respectively. Incubation of SK-OV3 cells with mTHPC for 5 days resulted in cytostatic cytotoxicity at a concentration of 0.5 muM. The photodynamic effect of mTHPC depends/among other parameters/on the concentration of the dye present. In combination with light (approximately 15 J/cm2) a linear relationship between the dose of mTHPC and the amount of necrotic cells was observable. Higher concentrations of mTHPC caused necrosis of the ovarian tumor cells. The intracellular concentration of mTHPC showed a linear increase up to 28.6 nM (incubation concentration). In summary, these studies demonstrated that mTHPC exhibits potent antiproliferative activity by inducing necrosis after application of light. MTHPC might be a promising agent with cytostatic and photodynamic properties for the treatment of metastasing ovarian carcinomas. A sensitive PCR method was not able to show the induction of apoptosis in the SK-OV3 ovarian cell line. Using propidium staining, it could be proved that the cell death was caused by necrosis and not through apoptosis after irradiation with light.

5-aminolevulinic acid-mediated photodynamic therapy of intraepithelial neoplasia and human papillomavirus of the uterine cervix--a new experimental approach

The aim of this study was to treat patients for ectocervical dysplasia [cervical intraepithelial neoplasia (CIN) grades 1 and 2] and associated human papilloma virus (HPV) infections with photodynamic therapy (PDT). In 20 patients, 5-aminolevulinic acid (5-ALA, 12% w/v) was applied topically with a cervical cap 8 h prior to illumination. A thermal light source (150 W halogen lamp) emitting a broadband red light (total energy: 100 J/cm2, fluence rate: 90 mW/cm2) was used for superficial illumination of the portio. In addition, an Nd:YAG pumped dye laser (652 nm) was used to illuminate the cervical canal (total energy: 50 J/cm2, fluence rate: 300 mW/cm2). Preliminary results of follow-ups at 1, 3, 6, and 9 months posttherapy showed a cytological improvement in the grading of the PAP smears in 19 patients and the eradication of cervical HPV in 80%. These results demonstrate that ectocervical dysplasia and associated HPV infections can be treated by PDT.

Antagonistic effects of combination photosensitization by hypericin, meso-tetrahydroxyphenylchlorin (mTHPC) and photofrin II on Staphylococcus aureus

Photodynamic therapy involves the application of a photosensitizer activated by visible light to generate cytotoxic reactive oxygen. In addition to clinical investigations, in vitro studies concerning photodynamic potency of sensitizers as well as quantification of illumination procedures are necessary. In our investigation, the objective was to evaluate not only the effects of photosensitizer and light on Gram-positive Staphylococcus aureus, but also to investigate possible synergistic or antagonistic effects of these sensitizers. Therefore, we used hypericin, Photofrin II, porfimer sodium and meso-tetrahydroxyphenylchlorin (mTHPC) alone, as well as in combination. Log-phase cells of S. aureus exhibited a marked sensitivity to white thermal light irradiation in the presence of Photofrin II and mTHPC. However, hypericin caused a rather stimulated growth expressed in increased optical density (OD) and increase of total cell count (TCC) of the culture. Combination sensitization of S. aureus by Photofrin II and mTHPC with hypericin likewise caused a stimulation of bacterial growth. No synergistic effects were obtained by combination of Photofrin II and mTHPC; photoresponse of S. aureus was rather decreased by using combined porphyrins. In comparison, TCC and colony-forming units (CFU) were suppressed in the presence of mTHPC after an illumination procedure as well as in dark reactions. These effects were also obtained in the combination photosensitization by mTHPC and Photofrin II. In the presence the of hypericin, photodynamic effects of mTHPC and Photofrin II were inhibited. It was finally concluded that hypericin in our model is not a proper sensitizer for combination photo-sensitization due to antagonistic effects on photodynamic activity of mTHPC and Photofrin II.

Ambulant photodynamic therapy of superficial malignomas with 5-ALA in combination with folic acid and use of noncoherent light

This study reports our first results of ambulant photodynamic treatment with 5-aminolevulinic acid (5-ALA) in combination with folic acid and subsequent illumination with a noncoherent light source. The compound was topically applied to avoid total body skin sensitivity which occurs in the case of systemic administration. If no therapeutic response could be proved, we added folic acid to 5-ALA for a further treatment attempt. Illumination was performed by broad band red thermic light to also excitate reaction products with absorption bands located near to that of the sensitizer. As a result, we observed a response in all cases, however, in some cases only after the addition of folic acid.

Measurement of inotropic effects by a newly developed guinea pig papillary muscle bioassay

In order to measure inotropic influences of physiologically occurring substances and drugs we used a newly developed guinea pig papillary muscle (GPPM) bioassay. GPPM were suspended in air and surface coated with buffer (Krebs-Henseleit solution). The muscles were stimulated (pulsating direct current, 1.5 V; 0.5 Hz, 20 ms duration) which led to contraction. This method enables measurements of inotropic effects up to 5 days, contrary to previous studies (1 day), in which immersions of GPPM in buffer were performed. In order to investigate the comparability of the new method we measured the effect of metabolites (citric acid cycle), lactic acid, lactate, and extracellular pH on muscle contractility. The H(+)-dependent decrease of the contractile force of the GPPM can be compensated by an increased Ca(2+)-concentration. Further, the influence of catecholamines (isoproterenol) on the contractility was investigated. As a result, isoproterenol caused arrhythmias and extrasystoles as it was observed in clinical studies. Several pharmaceutical substances were tested to show the reproducibility and repeatability of the bioassay.

Hypericin in phototherapy

We describe the first local use of hypericin as photosensitizer for photodynamic therapy in a patient with recurrent malignant mesothelioma. Hypericin is a polycyclic quinone, which has been shown to possess in vivo and in vitro antiretroviral and photosensitizing activity; moreover, it is used in depressive disorders. The semiquinone radical, singlet oxygen, and superoxide anion radical are reported to be the toxic agents in hypericin phototherapy. Our first experience with locally applied hypericin in a superficial tumor-plate was performed 8 weeks after the systemic administration of hematoporphyrin derivatives. For tumor light illumination we used an argon pumped dye laser tuned to 632 nm. Owing to satisfactory results, we repeated the same therapy 4 weeks later- and no therapeutic effect was noted. Following this, we proved the interstitial application of HPD and the combination of interstitial HDP and superficially applied hypericin. The subsequent light illumination 6 hours later had no efficacy in the HDP-photosensitized area but there was tumor destruction in the field with both administered photosensitizers. Our first experience suggests a potentiation of two photosensitizers: hematoporphyrin derivatives and hypericin.

Natural products derived from plants as potential drugs for the photodynamic destruction of tumor cells

Chlorophyll and some of its synthetically produced derivatives are important sensitizers in photodynamic cancer therapy. Other natural products from plants with light dependent activity include quinones like hypericin and fagopyrin. These compounds have extended pi-electron systems which upon photoexcitation with visible light are responsible for singlet oxygen production. Other plant constituents which show UV light induced photosensitizing activity are furanocumarins like psoralen and angelicin, aflatoxins and alkaloids, as well as thiophene derivatives, terthienyl and several polyacetylenes. The photodynamic properties of a chelidonium alkaloid derivative and data for its potential clinical applicability are given.

Wavelength-dependent photoresponse of biological and aqueous model systems using the photodynamic plant pigment hypericin

Photodynamic eradication of tumour cells in vivo depends on the presence of a photosensitizer, light delivery to the cells, and an oxygen supply. Hypericin, a polycyclic quinone with absorption maxima in the ultraviolet and visible ranges, was prepared for clinical use as a photosensitizer. Due to antitumoral and antineoplastic activities as well as the generation of singlet oxygen after photoexcitation, hypericin was applied in clinical oncology and photodynamic therapy. Hypericin was administered subcutaneously (20 micrograms hypericin in 200 microliters Nacl/pyridine solution) into the ante brachium (forearm) of two volunteers. After the diffusion and equilibration of 120 min phototesting was carried out using outdoor light exposure, halogen lamp, laser 514 nm (argon), laser 632 nm (argon dye) and laser 670 nm (diode laser), from 60 to 120 J cm-2. Positive phototests to outdoor light exposure, halogen lamp and laser 514 nm were characterized by rubescence, oozing, vesiculation and darting pain. Phototests with laser 632 nm and 670 nm showed no effects after irradiation. When hypericin was administered topically on skin, erythema and flaring could not be induced by any irradiation. These results suggest that hypericin is a potent photosensitizer only within the UV and green light ranges. This characteristic photoresponse could also be obtained in guinea pig papillary muscle (GPPM) bioassay, which may be established as a model for photosensitizer testing. Irradiation of hypericin-incubated GPPM with 514 nm (20 J cm-2) led to a decrease of the contractile force of about 31%. However, excitation with 632 nm and 670 nm did not cause inotropic effects on GPPM. In addition, hypericin and Photosan 3 were shown to be capable of sensitizing the photo-oxidation of sodium linoleate. This assay should be established for testing interactions between photosensitizers and light sources in vitro.

[Use of the proteinase inhibitor alpha 2-macroglobulin in synovial fluids of arthritis of different origins and its relation to serologic parameters]

Collagen and proteoglycan are major constituents of the articular cartilage. In rheumatic disorders joint damage is attributed to the excessive action of proteoglycan degrading proteinases (P) and specific collagenases, which are released by connective tissue- and inflammatory cells in the synovial compartment. Collagenase is secreted in a latent form, which requires activation by a variety of serine-proteinases. Thus, several different proteinases are involved in pathogenesis of joint disease. alpha 2-macroglobulin was shown to be the major inhibitor of proteinases in complex biological fluids. To assess the utilization of alpha 2M by proteinases in synovial fluids (SF) from different arthritides we have employed a newly introduced solid phase immuno-sorbent assay, which allows concentration of alpha 2M and its proteinase-complexes from biological fluids. Most pronounced utilization of alpha 2M (up to 50% of total SF alpha 2M) was found in marked joint inflammation as judged from RF, immunocomplexes, C3 complement activation and acute phase reactants. Supported by animal experiments, which revealed that alpha 2M.P complexes but not native alpha 2M induce synovitis in rabbits after repeated intra-articular administration, it is suggested that pathophysiological rise of alpha 2M.P may impair cellular functions in inflammatory connective tissue, e.g. synovial tissue.