Tarek A. El-Tayeb

Chlorophyll derivative mediated PDT versus methotrexate: An in vitro study using MCF-7 cells

BACKGROUND Breast cancer is the most common cause of cancer deaths among women worldwide. Although chemotherapy is a standard method for the treatment of breast cancer, the photodynamic therapy (PDT) is a recent promising modality for cancer diagnosis and treatment. Its major advantages over chemotherapy are better selectivity of tumour tissue destruction and lack of severe local and systemic complications. This work is directed towards evaluation of the efficacy of Photodynamic therapy using chlorophyll derivative (CHL) as a photosensitizer in treatment of breast cancer. It also aims at investigation of the genetic safety of chlorophyll mediated PDT in comparison to the conventional chemotherapy. METHODS Both methotrexate (MTX) and light activated chlorophyll derivative were used to target MCF-7 breast cancer cell line. Standard karyotyping and alkaline single cell microgel electrophoresis assay (Comet assay) were applied on normal human peripheral blood lymphocytes (HPL) in order to investigate the respective possible mutagenic and genotoxic side effects that might result from application of each therapeutic modality. RESULTS Results obtained from this study showed that 50% of MCF-7 tumour cell death (LC(50)) was reached by using a concentration of chlorophyll derivative that is 138 times lower than MTX. Moreover, chlorophyll derivative exerted no genetic side effects as compared to MTX that resulted into several types of chromosomal breakages. CONCLUSIONS Compared to MTX, light activated chlorophyll derivative proved to be a better candidate for breast cancer cell toxicity, referring to its higher efficacy at tumour cells killing, safety to normal cells and simple method of extraction.

In vitro and in vivo antimicrobial activity of combined therapy of silver nanoparticles and visible blue light against Pseudomonas aeruginosa

Silver nanoparticles (AgNPs) have been used as potential antimicrobial agents against resistant pathogens. We investigated the possible therapeutic use of AgNPs in combination with visible blue light against a multidrug resistant clinical isolate of Pseudomonas aeruginosa in vitro and in vivo. The antibacterial activity of AgNPs against P. aeruginosa (1×105 colony forming unit/mL) was investigated at its minimal inhibitory concentration (MIC) and sub-MIC, alone and in combination with blue light at 460 nm and 250 mW for 2 hours. The effect of this combined therapy on the treated bacteria was then visualized using transmission electron microscope. The therapy was also assessed in the prevention of biofilm formation by P. aeruginosa on AgNP-impregnated gelatin biopolymer discs. Further, in vivo investigations were performed to evaluate the efficacy of the combined therapy to prevent burn-wound colonization and sepsis in mice and, finally, to treat a real infected horse with antibiotic-unresponsive chronic wound. The antimicrobial activity of AgNPs and visible blue light was significantly enhanced (P<0.001) when both agents were combined compared to each agent alone when AgNPs were tested at MIC, 1/2, or 1/4 MIC. Transmission electron microscope showed significant damage to the cells that were treated with the combined therapy compared to other cells that received either the AgNPs or blue light. In addition, the combined treatment significantly (P<0.001) inhibited biofilm formation by P. aeruginosa on gelatin discs compared to each agent individually. Finally, the combined therapy effectively treated a horse suffering from a chronic wound caused by mixed infection, where signs of improvement were observed after 1 week, and the wound completely healed after 4 weeks. To our knowledge, this combinatorial therapy has not been investigated before. It was proved efficient and promising in managing infections caused by multidrug resistant bacteria and could be used as an alternative to conventional antibiotic therapy.

Short-pulsed diode lasers as an excitation source for time-resolved fluorescence applications and confocal laser scanning microscopy in PDT

This article describes a setup for subcellular time-resolved fluorescence spectroscopy and fluorescence lifetime measurements using a confocal laser scanning microscope in combination with a short pulsed diode laser for fluorescence excitation and specimen illumination. The diode laser emits pulses at 398 nm wavelength with 70 ps full width at half maximum (FWHM) duration. The diode laser can be run at a pulse repetition rate of 40 MHz down to single shot mode. For time resolved spectroscopy a spectrometer setup consisting of an Czerny Turner spectrometer and a MCP-gated and -intensified CCD camera was used. Subcellular fluorescence lifetime measurements were achieved using a time-correlated single photon counting (TCSPC) module instead of the spectrometer setup. The capability of the short pulsed diode laser for fluorescence imaging, fluorescence lifetime measurements and time-resolved spectroscopy in combination with laser scanning microscopy is demonstrated by fluorescence analysis of several photosensitizers on a single cell level.

A study on the dynamics of Aedes caspius larval uptake and release of novel haematoporphyrin

Haematoporphyrin efficiency on Aedes caspius increased the larval mortality with the increase of haematoporphyrin formulation (HPF) concentration (1 × 103 M/l). Larval mortality increased with increase the solar simulator light irradiances (350–650 W/m2) and exposure times (45 min). Dynamics of HPF accumulation and release as a function of time feeding and consumption was investigated using confocal laser scanning microscopy (CLSM). HPF accumulation in the larval body reached its maximum level after incubation for 12 h. Remaining HPF concentration decreased as the time elapsed reaching its minimal level after 15 h of HPF removal from the treatment medium.

Field implementation using chlorophyll derivatives with sunlight for malaria, filaria and dengue fever vectors control in infested Africa swamps

In this work, we present the successful field implementation of using Photodynamic modality to control Malaria, Filaria and Dengue Fever vectors in infested epidemic swamps in Uganda, Ethiopia and Sudan. As the Photodynamic technique has become a major approach for the control of human parasites and noxious insects. Field investigations were carried out based on laboratory and semi-field results. In these trials, chlorophyll derivatives were added to the infested swamps to be taken by the mosquito larvae and the accumulated photoactive compound (photosensitizer) inside the larvae body induces upon sunlight exposure an oxidation stress, that results in organism death. As example in Kasangati and Namanve cities of Wakiso a district in Uganda , chlorophyll derivatives , as sunlight active photosensitizers was applied to cover 250 000 square meter of infected swamps and sand pits (4 gm/ m2).The infected cities were mapped for this field study using Geographical Positioning System (GPS). All the biotic and a-biotic factors were measured before and after treatment. Confocal laser scanning microscopy measurements were used to monitor the concentration and the dynamic distribution of chlorophyll derivatives inside the larvae of Anopheles gambiae mosquito. The results reveal that from 85% to 100% mortality of larvae population are obtained at different concentrations of Chlorophyll derivatives (0.1 -100µM). Other biological beneficiary organisms, such as the dragon fly larvae and mosquito predator larvae, which were present in the same treated swamps were not affected (target selectivity). The field trials are the result of three years continuous and persistent work, which showed promising success in controlling Malaria, Filaria and Dengue Fever vectors by cutting the mosquito’s life cycle without new generation, formation, or reinfestation.

The effect of diode laser and light emitting diode on the bacterial contamination of semen medium for artificial insemination.

Animal artificial insemination (AI) suffers from bacterial contamination of semen media which results in decreased success of the process of artificial insemination. It is difficult to treat the semen extender medium to reduce the bacterial growth in the presence of semen using the conventional techniques of bacterial inhibition. In the present work, a new optical method developed for bacterial growth inhibition in semen containing extender medium using diode laser (DL) and commercial cheap light emitting diode (LED) is presented. Certain wavelengths and exposure times suitable for the process of artificial insemination are found to be optimum at reducing bacterial growth with a minimum significant effect on the semen motility and viability.

Photodynamic Control of Malaria Vector, Noxious Insects and Parasites

It is well documented that PDT has become a major approach for diagnosis and treatment of cancer. However, PDT was early discovered as a photodynamic antimicrobial chemotherapy and it has recently received considerable attention from researchers due to the fact that it has shown promise in the treatment of various tropical pathogens. In addition, PDT has been utilized successfully in recent years as a novel modality for noxious insects and parasite control, which is the subject of this chapter. The different classes of noxious insects, namely the activity of medical insects of vector borne- diseases such as Malaria, Filaria, and Dengue fever and agro-insects and pests which cause considerable damage to agro-economics, will be discussed in this chapter.

Sunlight active formulated extract (SAFE): an Egyptian invention for malaria vector control

This invention introduces an innovative modality for malaria vector control that combines both effectiveness and efficiency with the highest levels of human safety and environment friendliness. The Novality of this (PCT) patent lies in developing a new ecologically safe modality using a natural plant extract (chlorophyll derivatives) and mosquito larvae attractant as sunlight active photo-larvicide for outdoors control of the larvae of Anopheles gambiae, Culex pipiens and Aedes aegypti. In this context, the accumulated photoactive compound (photosensitizer) in the larvae body induces, upon sunlight exposure, an oxidation stress that results in organism death. The obtained results reveal that SAFE is highly effective as it ensures up to 100% mortality of mosquitoes larvae. The effectiveness of SAFE accumulation in the larvae bodies was qualitatively and quantitatively investigated using the Confocal Laser Scanning Microscopy (CLSM) technique. The active ingredient of SAFE (chlorophyll derivative) exhibit several advantages: they are low cost, natural products extracted from green plants and endorsed by the Food and Drug Administration (FDA) as food additives. In addition, they are used in very low concentrations (µM), can be easily applied in the field by being dissolved in an aquatic environment and most importantly they are highly effective.

Characterization of biophysical properties of rabbit auricle reshaped via diode laser (λ =980 nm)

Laser cartilage reshaping is a temperature dependent process that results in stress relaxation with subsequent formation of a new and stable specimens geometry. This temperature dependent process results in mechanical stress relaxation and is characteristic of a phase transformation. The objective of this study was to quantitavely measure changes in tensile elongation and elastic modulus of rabbit auricle cartilage reshaped via diode laser (980 nm) and irradiated in two different protocols. The results revealed that the laser irradiation parameter used in cartilage reshaping does not produce significant irreversible changes in mechanical properties of the cartilage tissue. So diode laser can be considered as one of efficient tools in cartilage reshaping.