Serhat Elcicek

Conjugation, characterization and toxicity of lipophosphoglycan-polyacrylic acid conjugate for vaccination against leishmaniasis

Research on the conjugates of synthetic polyelectrolytes with antigenic molecules, such as proteins, peptides, or carbohydrates, is an attractive area due to their highly immunogenic character in comparison to classical adjuvants. For example, polyacrylic acid (PAA) is a weak polyelectrolyte and has been used in several biomedical applications such as immunological studies, drug delivery, and enzyme immobilization. However, to our knowledge, there are no studies that document immune-stimulant properties of PAA in Leishmania infection. Therefore, we aimed to develop a potential vaccine candidate against leishmaniasis by covalently conjugating PAA with an immunologically vital molecule of lipophosphoglycan (LPG) found in Leishmania parasites. In the study, LPG and PAA were conjugated by a multi-step procedure, and final products were analyzed with GPC and MALDI-TOF MS techniques. In cytotoxicity experiments, LPG-PAA conjugates did not indicate toxic effects on L929 and J774 murine macrophage cells. We assume that LPG-PAA conjugate can be a potential vaccine candidate, and will be immunologically characterized in further studies to prove its potential.

The use of platensimycin and platencin to fight antibiotic resistance

Infectious diseases are known as one of the most life-threatening disabilities worldwide. Approximately 13 million deaths related to infectious diseases are reported each year. The only way to combat infectious diseases is by chemotherapy using antimicrobial agents and antibiotics. However, due to uncontrolled and unnecessary use of antibiotics in particular, surviving bacteria have evolved resistance against several antibiotics. Emergence of multidrug resistance in bacteria over the past several decades has resulted in one of the most important clinical health problems in modern medicine. For instance, approximately 440,000 new cases of multidrug-resistant tuberculosis are reported every year leading to the deaths of 150,000 people worldwide. Management of multidrug resistance requires understanding its molecular basis and the evolution and dissemination of resistance; development of new antibiotic compounds in place of traditional antibiotics; and innovative strategies for extending the life of antibiotic molecules. Researchers have begun to develop new antimicrobials for overcoming this important problem. Recently, platensimycin – isolated from extracts of Streptomyces platensis – and its analog platencin have been defined as promising agents for fighting multidrug resistance. In vitro and in vivo studies have shown that these new antimicrobials have great potential to inhibit methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae by targeting type II fatty acid synthesis in bacteria. Showing strong efficacy without any observed in vivo toxicity increases the significance of these antimicrobial agents for their use in humans. However, at the present time, clinical trials are insufficient and require more research. The strong antibacterial efficacies of platensimycin and platencin may be established in clinical trials and their use in humans for coping with multidrug resistance may be allowed in the foreseeable future.

Adipose tissue-derived mesenchymal stem cells as a new host cell in latent leishmaniasis.

Some protozoan infections such as Toxoplasma, Cryptosporidium, and Plasmodium can be transmitted through stem cell transplantations. To our knowledge, so far, there is no study about transmission of Leishmania parasites in stem cell transplantation and interactions between parasites and stem cells in vitro. Therefore, the aim of this study was to investigate the interaction between different species of Leishmania parasites and adipose tissue-derived mesenchymal stem cells (ADMSCs). ADMSCs have been isolated, cultured, characterized, and infected with different species of Leishmania parasites (L. donovani, L. major, L. tropica, and L. infantum). Infectivity was examined by Giemsa staining, microculture, and polymerase chain reaction methods. As a result, infectivity of ADMSCs by Leishmania parasites has been determined for the first time in this study. According to our findings, it is very important that donors are screened for Leishmania parasites before stem cell transplantations in regions where leishmaniasis is endemic.

Aldehyde Dehydrogenase: Cancer and Stem Cells

Aldehyde dehydrogenases (ALDH) belong to the oxidoreductase family, which catalyze the conversion of aldehydes to their corresponding acids. As a group of NAD(P)+-dependent enzymes, aldehyde dehydrogenases (ALDHs) are involved in oxidation of a large number of aldehydes into their weak carboxylic acids (Moreb, et al., 2012). ALDH is found in every subcellular region such as cytosol, endoplasmic reticulum, mitochondria, and the nucleus, with some even found in more than one location (Marchitti, et al., 2008).

Generation of avirulent Leishmania parasites and induction of nitric oxide production in macrophages by using polyacrylic acid.

Polyacrylic acid (PAA) is one of the anionic synthetic polyelectrolytes and is used in various immunological and pharmaceutical applications. PAA has been used as adjuvant in veterinary vaccines, in particular. However, to our knowledge, there are no studies that document immunostimulant properties of PAA in Leishmania infection. The main aim of this study was to investigate the interaction of Leishmania parasites with PAA: the possible effects on the infectivity of Leishmania promastigotes; and, induction of nitric oxide (NO) production in macrophages in vitro. The cytotoxicity of PAA on both macrophages and Leishmania infantum promastigotes were determined by MTT assay. NO production in the macrophage culture supernatant was measured by the Griess method. A significant, dose-dependent and time-dependent decrease in the infection index was observed after PAA exposure. The value of this decrease was found to be between 93% and 100% for all concentration and time points. PAA (molecular weight (MW) 30, 100 kDa at 1mg/1h)-exposed parasites stimulate NO production significantly at 48 h post-infection (PI), when compared to the control. This study demonstrates that Leishmania parasites lost their virulence upon interaction with PAA, and this interaction induced NO production in infected macrophages. These results may have important implications in the development of anti-leishmanial vaccines and amelioration of immune response.

Detection of antileishmanial antibodies in blood sampled from blood bank donors in Istanbul.

AIMS According to the WHO, only 5-20% of the total cases of leishmaniasis are symptomatic leishmaniasis; the other cases are identified as asymptomatic leishmaniasis. In recent studies, it has been demonstrated that donor blood plays an important role in the epidemiology of asymptomatic leishmaniasis. However, the number of the studies on this subject is still insufficient. Additionally, donor blood samples obtained from Istanbul, which is the biggest metropolitan area in Turkey, have not been investigated with regard to Leishmania. Moreover, there is no information about the sensitivity of noninvasive serological methods that are used in the detection of leishmaniasis donor blood samples. Accordingly, this study aimed to investigate the presence of antileishmanial antibodies in blood samples obtained from blood bank donors in Istanbul, by using different serologic methods, and to determine the most sensitive detection method. MATERIALS & METHODS Blood samples were taken from 188 healthy blood bank donors to the Capa Turkish Red Crescent Blood Bank (Istanbul, Turkey), and the presence of antileishmanial antibodies was measured by indirect immunofluorescent antibody test (IFAT), ELISA, immunochromatographic dipstick rapid test, and western blot (WB). RESULTS Antileishmanial antibodies were determined in 12 out of 188 samples by IFAT (6.4%), and six out of these 12 donors were found to be positive at diagnostic titer 1:128 (3.2%). One hundred and eighty eight samples were investigated by ELISA and one (0.5%) of them gave a positive result. None of 188 samples provided a positive result by immunochromatographic test. WB applied to the 12 seroreactive donors showed that three out of 12 donors were positive. CONCLUSION In this study, the presence of antileishmanial antibodies in blood samples of blood bank donors from Istanbul has been demonstrated by using feasible and low-cost serological methods. Additionally, in comparison with other simple and low-cost detection methods, WB was used for confirmation. IFAT has a higher sensitivity and therefore may be preferred as a prescreening method in endemic or nonendemic areas.

Glucose-6-Phosphate Dehydrogenase Deficiency and Malaria: A Method to Detect Primaquine-Induced Hemolysis in vitro

© 2012 Allahverdiyev et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Glucose-6-Phosphate Dehydrogenase Deficiency and Malaria: A Method to Detect Primaquine-Induced Hemolysis in vitro

Effect of Human Urine on Cell Cycle and Infectivity of Leismania Species Promastigotes In Vitro

In vitro cultivation of Leishmania parasites plays an important role in diagnosis and treatment of leishmaniasis and in vaccine and drug development studies. Conversely, long-term cultivation of Leishmania parasites usually results in decreased infectivity potential. Some studies reported a stimulatory effect of human urine in Leishmania promastigotes. However, there is no information about the effects of urine within culture on the infectivity of Leishmania parasites. Analysis of the effect of urine have showed that proliferation indexes were significantly increased in culture medium supplemented with human urine (L. tropica = 38.17 ± 5.12, L. donovani = 34.74 ± 5.6, L. major = 34.22 ± 4.66, and L. infantum 35.88 ± 6.40) than in controls. Infection indexes were 13 ± 1.7 for L. tropica, 55 ± 2.2 for L. infantum, 41 ± 3.14 for L. donovani, and 49 ± 3.26 for L. major. Our results showed that human urine increased the infectivity and proliferation of Leishmania parasites.

Utility of the Microculture Method in Non-Invasive Samples Obtained from an Experimental Murine Model with Asymptomatic Leishmaniasis

The sensitivity of diagnostic methods for visceral leishmaniasis (VL) decreases because of the low number of parasites and antibody amounts in asymptomatic healthy donors who are not suitable for invasive sample acquisition procedures. Therefore, new studies are urgently needed to improve the sensitivity and specificity of the diagnostic approaches in non-invasive samples. In this study, the sensitivity of the microculture method (MCM) was compared with polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescent antibody test (IFAT) methods in an experimental murine model with asymptomatic leishmaniasis. Results showed that the percent of positive samples in ELISA, IFAT, and peripheral blood (PB) -PCR tests were 17.64%, 8.82%, and 5.88%, respectively, whereas 100% positive results were obtained with MCM and MCM-PCR methods. Thus, this study, for the first time, showed that MCM is more sensitive, specific, and economic than other methods, and the sensitivity of PCR that was performed to samples obtained from MCM was higher than sensitivity of the PCR method sampled by PB.

Development of New Antiherpetic Drugs Based on Plant Compounds

Herpes simplex virus (HSV) infections comprise one of the most important health problems worldwide. HSV-1 and HSV-2 that are the types most frequently seen in disease, manifested by sores and blisters on the mouth, tongue, skin, and genitals of infected individuals. Moreover, herpetic infections can reach life-threatening levels; for instance, HSV-2 prevalence has increased greatly in human immunodeficiency virus-positive patients. This indicates that the herpetic infection could be a major cause of morbidity in immunosuppressed patients. Unfortunately, resistance against antiherpetic drugs has recently been reported. Therefore there is an immediate need to search for new antiviral agents in order to cope with HSV infections. Recently, it has been demonstrated that traditional medicinal plants have strong antiviral activity and some are already being used in the treatment of viral infections, including herpes simplex infections. Accordingly, this chapter aims to present published information on various herbal compounds, investigate the antiherpetic effectiveness of these compounds, and determine the potential of plants as herpetic treatments in the future.