Studies on the protective immune response to Plasmodium chabaudi in mice

Inbred strains of C5731 and NIH nice infected with the A/S strain of Plasmodium chaubaudi usually developed high parasitaemias but infections were rarely fatal in immunocompetent mice and in most mice the parasites could be eradicated within 53 days or less. The immune response of C57B1 and NTH mice to infection with the A/S strain of P. chabaudi was studied. The principle method used in this study for investigating the immune response of the mice was to examine the immunity conferred on syngeneic mice, either X-irradiated or non-irradiated, by transferring to them lymphoid cells or serum from immune or semi-immune donors. The lymphoid cell populations examined were unfractionated spleen cells, nylon wool column enriched subpopulations of thymus-derived lymphocytes (T cells) and the so-called bursa-derived lymphocytes (B cells), bone marrow cells and phagocytic cells. In the course of these experiments observations were made on the effect of X-irradiation on the subsequent growth and multiplication of the parasite. In addition, an in vitro assay for antibody-dependent cell mediated cytotoxicity was used to investigate the activity of splenic K cells during malaria infection. K cells are lymphoid cells which may include lymphocytes of an undefined category, but possess receptors for the Fc portion of antibody on their surface and have the ability to non-specifically lyse target cells coated in antibodies. a) The adoptive transfer of immunity to P.chabaudi with immune spleen cells. Spleen cells from mice which had previously been infected with P.chabaudi were able to confer some immunity on syngeneic mice which had been irradiated with 600 or 800 rads. The protection was detected as a shortened patent parasitaemia in immune cell recipients compared to controls. The early experiments indicated the value of using irradiated recipients rather than non-irradiated recipients. In irradiated mice, a) smaller numbers of immune cells were required to promote detectable immunity than in non-irradiated mice, b) there was an amplification of the difference in the duration of primary parasitaemias in recipients of immune cells and normal cells compared to non-irradiated mice and c) as the irradiated host is immunodepressed, the protective effect of donor cells can be examined with a reduced contribution by the hosts own immune system. An initial non-specific resistance to P.chabaudi infection was observed in irradiated mice, although the infection in most of these mice was subsequently more severe than in non-irradiated mice. The non-specific resistance could be reduced or abolished by injecting lymphoid cells into mice shortly after irradiation or by infecting irradiated mice more than 15 days after irradiation. Other workers suggest that following irradiation, the reticulo-endothelial system is stimulated at the time that the non-specific resistance to P.chabaudi was observed. b) the adoptive transfer of immunity in syngeneic mice with enriched subpopulations of splenic immune T cells, B. cells, bone marrow cells and phagocytes. Immunity to P.chabaudi could be adoptively transferred with enriched spleen subpopulations of immune T cells or immune B cells in mice which had been irradiated 600 or 300 rads. The protective effects of unfractionated immune cells was, however, usually better than that of either immune T or F cell subpopulations. In most experiments enriched immune T cell recipients were more likely to suffer relapsing patent parasitaemias than either enriched immune B cell recipients or unfractionated immune cell recipients. In one experiment a comparison was made of the course of P.chabaudi infection in mice which had been irradiated with either 600 rads or 300 rads and which received injections of different immune cells. A dose of 600 rads permits the immune system of mice to recover from the effects of irradiation, but a dose of 800 rads is lethal to mice unless lymphoid cells are injected after irradiation. It was found that in recipients of enriched immune T or B cells, which had been irradiated with 600 rads, the parasitaemia became subpatent before their equivalents irradiated with 800 rads, but that there was little difference in parasitaemias between recipients of unfractionated immune cells given 600 or 800 rads. Experiments in which enriched immune T cells and B cells were recombined and injected into syngeneic mice gave inconclusive results as to whether the immune subpopulations acted synergistically. Similar experiments in which immune subpopulations of lymphoid cells were recombined with normal subpopulations of lymphoid cells demonstrated that the latter cells did not enhance the protective effect of the former cells. Bone marrow cells from immune mice were able to confer some protection on syngeneic recipients, but were not as protective as enriched immune T cells or B cells. The results obtained in adoptive transfer experiments using phagocytic cells from the spleen of immune mice depended on the length of time spleen cells were incubated in petri-dishes at 37° C before harvesting the phagocytes. Using C57B1 mice, phagocytes harvested after 15 hours incubation were as protective as unfractionated immune cells in a cell transfer experiment, but phagocytes harvested after 16 hours incubation were not protective. Examination of NIH phagocytic cells after 2.5 hours incubation at 37°C, which were as protective as unfractionated immune spleen cells in a cell transfer experiment, demonstrated that the petri-dish adherent cells may have contained B lymphocytes. c) The passive transfer of immunity with serum from P.chabaudi infected mice. The passive transfer of serum from C57B1 mice which had been previously infected with P.chabaudi to normal or irradiated syngeneic mice demonstrated that the serum recipients were initially protected from infection. Irradiated mice, however, were delayed longer in the onset of parasitaemia compared to non-irradiated mice. Using NIH mice, sera were collected from unfractionated immune spleen cell recipients, enriched immune T cell recipients and normal spleen recipients on the 11th day of a P.chabaudi infection, just after peak parasitaemia, and also on the 14th day of infection. On day 14, all immune cells recipients and most of the enriched immune T cell recipients had become subpatent but all normal cell recipients still had patent infections. Sera collected from the different spleen cell recipients on the 11th day of infection and passively transferred to irradiated mice demonstrated little protection. Sera collected on the 14th day of infect ion, however, reflected the immune status of the donors in their protective properties in mice infected with P.chabaudi. The serum from unfractionated immune cell recipients was the most protective of the 3 sera when compared to normal NIH serum and the serum from enriched immune T cell recipients was slightly protective, but the serum from normal cell recipients produced an enhanced infection in mice infected with P.chabaudi. d) Antibody-dependent cell-mediated cytotoxicity of spleen cells in P.chabaudi infected mice. In a preliminary investigation of K cell activity in the spleens of P.chabaudi infected mice, it was found that there was an increased activity of K cells collected at around peak parasitaemia compared to the activity of K cells in non-infected mice, and that this increased activity could also be found in mice which had recently become subpatent. As the target cell for antibody-dependent cell-mediated cytotoxicity employed was the thick red blood cell, it is not known whether the K cell is involved in the killing of P.chabaudi parasites. These results suggest that both T cells and B cells and antibody may be important in the immune response to P.chabaudi in mice. Primed T cells may act as helper cells in the production of malarial antibodies, but, as enriched primed T cells could confer protection on immunodepressed mice, it is possible that a cell-mediated mechanism of immunity may also exist.

Evaluation of the protective effects of kolaviron on Kolanut-induced oxidative stress in developing rat brain

The brain is exposed throughout life to oxidative stress, and certain diseases of the brain and nervous system are thought to involve free radical processes and oxidative damage. This study is aimed at evaluating the effect of kolaviron on kolanut-induced oxidative stress in developing rat brain. Twenty-five adult pregnant Wistar rats weighing between 160 and 180g were used for the experiment. They were randomly divided into five groups of five animals each. The animals were fed with standard diets of mice cubes and water provided ad libitum. The control rats received water and cornoil, while the experimental animals received 200 mg/kg body weight of kolanut (kn), 200 mg/kg of kolaviron (kv), and 200 mg/kg body weight of vitamin E which served as a standard antioxidant with cornoil as vehicle orally in pre- and post-natal life. After birth, gross morphometry and behavioural changes of the pups of days 1, 7, 14, 21 and 28 postpartum were evaluated. Blood samples were collected from pups of day 21 for hematological, liver and renal function analyses, while the brains of pups of day 21 postpartum were preserved in phosphate buffer at a temperature of 4oC and pH 7.4 for biochemical analysis. There were significant alterations in the gross morphometry and behavioural parameters studied in the treated animals compared with the control at p< 0.05. There were elevated levels of RBC, WBC and platelets in the treated group compared with the control at p< 0.05. However, no significant change was observed in the PCV, Hb, liver and renal function parameters studied at p>0.05. A non-significant increase in levels of malondialdehyde, MDA, a bye-product of lipid peroxidation in the kolanut group was observed. However, administration of kolaviron and vitamin E non-significantly (p>0.05) reversed these changes. In conclusion, maternal consumption of kolanut induced mild oxidative stress and the administration of kolaviron and vitamin E decreased the rate at which kolanut induced oxidative stress in developing rat brain.

Potential protective role of reactive astrocytes in the periventricular parenchyma in congenital hydrocephalus

Background Cerebrospinal fluid accumulation in hydrocephalus produces an elevation of intraventricular pressure with pathological consequences on the periventricular brain parenchyma including ischemia, oedema, oxidative stress, and accumulation of metabolic waste products. Here we studied in the hyh mouse, an animal model of congenital hydrocephalus, the role of reactive astrocytes in this clinical degenerative condition. Materials and Methods Wild type and hydrocephalic hyh mice at 30 days of postnatal age were used. Three metabolites related to the oxidative and neurotoxic conditions were analysed in ex vivo samples (glutathione, glutamine and taurine) using High Resolution Magic Angle Spinning (HR-MAS). Glutathione synthetase and peroxidase, glutamine synthetase, kidney-type glutaminase (KGA), and taurine/taurine transporter were immunolocated in brain sections. Results Levels of the metabolites were remarkably higher in hydrocephalic conditions. Glutathione peroxidase and synthetase were both detected in the periventricular reactive astrocytes and neurons. Taurine was mostly found free in the periventricular parenchyma and in the reactive astrocytes, and the taurine transporter was mainly present in the neurons located in such regions. Glutamine synthetase was found in reactive astrocytes. Glutaminase was also detected in the reactive astrocytes and in periventricular neurons. These results suggest a possible protective response of reactive astrocytes against oxidative stress and neurotoxic conditions. Conclusions Astrocyte reaction seems to trigger an anti-oxidative and anti-neurotoxic response in order to ameliorate pathological damage in periventricular areas of the hydrocephalic mice.

Innovation diffusion in the portuguese and italian clothing industry

Doutoramento em Economia

Protective effect of (-)-epigallocatechin gallate on ultraviolet b-induced skin damage in hairless mice

Purpose: To investigate the protective effect of green tea (-)-epigallocatechin gallate (EGCg) on ultraviolet B (UV-B)-induced skin damages in hairless mice in order to develop a natural sunscreen compound for use in skin care products and cosmetics. Methods: EGCg was dissolved in acetone at concentrations of 1.0, 10.0 and 50.0 mg/mL, and topically applied to the skin of hairless mice at doses of 0.2 mL/cm2, with acetone as control. The mice were then irradiatd m2 UV-B for 30 min daily. EGCg treatment and UV-B irradiation were carried out daily for 28 consecutive days. The mice were then sacrificed and their dorsal skin examined by transmission electron microscopy (TEM) on the 28th day. Results: UV-B irradiation induced severe macroscopic skin damage including chapping, cracking and abnormal desquamation in the treated hairless mice. EGCg showed dose-dependent protective effects against UV-B induced damage on the skin. Treatments with 10.0 and 50.0 mg/mL EGCg alleviated UVB-induced skin damage by suppressing both keratinocyte apoptosis and mitochondrial dysfunction, along with inhibiting the production of melanin pigment. Conclusion: Topical application of green tea EGCg shows dose-dependent protective effect against UV-B-induced damage on hairless mouse skin. Thus, the plant compound can potentially be used as an alternative agent for photoprotection against UV-B exposure.

Protective effect of Rhizoma drynariae extract on osteoporosis in ovariectomized rat model

Purpose: To investigate the therapeutic effect of Rhizoma drynariae extract (RDE) on ovariectomyinduced osteoporosis in rats. Methods: Female Sprague-Dawley rats were randomly assigned to a sham-operated group (control) and five ovariectomy (OVX) subgroups: OVX with vehicle (OVX), OVX with 17ß-estradiol (E2, 25 μg/kg/day), and OVX with RDE doses (40, 80, and 160 mg/kg/day). Daily oral administration of E2 or RDE started 4 weeks after OVX and lasted for 16 weeks. The bone mineral density (BMD) of the L4 vertebrae and right femurs was estimated. The length of each femur was measured with a micrometer gauge, and the center of the diaphysis determined. Three representatives L4 vertebrae were selected to evaluate the trabecular microarchitecture. Serum alkaline phosphatase (ALP), urinary calcium (U-Ca), urinary phosphorus (U-P), urinary creatinine (Cr) and osteocalcin (OC) levels were measured. Results: The study showed that high-dose of RDE significantly inhibited the bone mineral density (BMD) reduction of L4 vertebrae (0.20 ± 0.02 g/cm3, p < 0.05) and femurs (0.18 ± 0.02 g/cm3, p < 0.05) caused by OVX and prevented the deterioration of trabecular microarchitecture (p < 0.05), which were accompanied by a significant decrease in skeletal remodeling (p < 0.05) as evidenced by the lower levels of bone turnover markers. High-dose of RDE improved morphometric parameters, namely, Tb-N (3.8 ± 0.2 mm, p < 0.05), Tb-Th (0.083 ± 0.011 mm, p < 0.05) and Tb-Sp (0.19 ± 0.01 mm, p < 0.05) in L4 vertebrae significantly. The present study indicates that the administration of RDE at higher doses over a 16-week period can prevent OVX-induced osteoporosis in rats without hyperplastic effects on the uterus. Conclusion: Thus, RDE is a potential natural alternative for postmenopausal osteoporosis treatment in elderly women.

Protective effect of rhamnopyranosyl vanilloyl isolated from Scrophularia ningpoensis Hemsl (Scrophulariaceae) root against acute liver injury in mice

Purpose: To investigate the protective effect of rhamnopyranosyl vanilloyl (RV) from Scrophularia ningpoensis root against tetrachloromethane (CCl4)-induced acute liver injury (ALI) in mice. Methods: RV was isolated from S. ningpoensis by column chromatography. ALI model of mice was established by intraperitoneal injection of CCl4. Liver index, liver function indices, as well as serum alanine transaminase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) were evaluated. Lipid peroxidation (LPO)-related indices, including malonaldehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Apoptotic proteins (Bcl-2, Bax and caspase-3) in liver tissue were determined by enzyme-linked immunosorbent assay (ELISA) and Western blot. Results: After treatment with RV (10, 20 or 40 mg/kg), liver index (5.65 - 5.21 vs. 6.68 %), ALT (90.18 - 79.68 vs. 112.47 U/L), AST (64.44 - 57.63 vs. 75.41 U/L) and TBIL (2.68 - 1.95 vs. 3.21 U/L) activities, as well as MDA (3.58 - 2.88 vs. 4.13 μmol/g), Bax and caspase-3 levels significantly (p < 0.05 or 0.01) decreased, compared with those in control group. After treatment with RV (10, 20 or 40 mg/kg), GSH (16.58 - 22.14 vs. 12.34 μmol/g), Bcl-2, SOD (86.45 - 107.61 vs. 68.43 U/mg) and GSH-Px (295.64 - 329.47 vs. 268.49 U/mg) levels or activities significantly (p < 0.05 or 0.01) increased, compared with those in control group. Conclusion: RV has protective effect against CCl4-induced ALI in mice, and the mechanisms involve the inhibition of LPO and apoptosis in liver cells. Thus, RV is a potential drug for the treatment of liver injury

Gender Differences in the Influence of Protective Factors, Risk Factors, and Health Risk Behaviors on HIV Risk Behaviors Among Youth in South Florida

Adolescents engage in a range of risk behaviors during their transition from childhood to adulthood. Identifying and understanding interpersonal and socio-environmental factors that may influence risk-taking is imperative in order to meet the Healthy People 2020 goals of reducing the incidence of unintended pregnancies, HIV, and other sexually transmitted infections among youth. The purpose of this study was to investigate gender differences in the predictors of HIV risk behaviors among South Florida youth. More specifically, this study examined how protective factors, risk factors, and health risk behaviors, derived from a guiding framework using the Theory of Problem Behavior and Theory of Gender and Power, were associated with HIV risk behavior. A secondary analysis of 2009 Youth Risk Behavior Survey data sets from Miami-Dade, Broward, and Palm Beach school districts tested hypotheses for factors associated with HIV risk behaviors. The sample consisted of 5,869 high school students (mean age 16.1 years), with 69% identifying as Black or Hispanic. Logistic regression analyses revealed gender differences in the predictors of HIV risk behavior. An increase in the health risk behaviors was related to an increase in the odds that a student would engage in HIV risk behavior. An increase in risk factors was also found to significantly predict an increase in the odds of HIV risk behavior, but only in females. Also, the probability of participation in HIV risk behavior increased with grade level. Post-hoc analyses identified recent sexual activity (past 3 months) as the strongest predictor of condom nonuse and having four or more sexual partners for both genders. The strongest predictors of having sex under the influence of drugs/alcohol were alcohol use in both genders, marijuana use in females, and physical fighting in males. Gender differences in the predictors of unprotected sex, multiple sexual partners, and having sex under the influence were also found. Additional studies are warranted to understand the gender differences in predictors of HIV risk behavior among youth in order to better inform prevention programming and policy, as well as meet the national Healthy People 2020 goals.

Blessed are the Peacemakers: Transnational Alliance, Protective Accompaniment and the Presbyterian Church of Colombia

The purpose of this thesis was to explore how Christian networks enable strategies of transnational alliance, whereby groups in different nations strive to strengthen one another’s leverage and credibility in order to resolve conflicts and elaborate new possibilities. This research does so by analyzing the case of the Presbyterian Church of Colombia (IPC). The project examines the historical development of the IPC from the initial missionary period of the 1850s until the present. Specifically, the purpose of the study was to consider how the historical struggle to articulate autonomy and equality vis-à-vis the U.S. Presbyterians (PCUSA) and paternalist models of ecclesial relations has affected recent political strategies pursued by the IPC. Despite the paternalism of the early missionary model, changing conceptions of social transformation during the 60s contributed to a shift in relations. Over time the IPC and PCUSA negotiated relationships in which groups both acknowledge a problematic history and insist upon an ethnic of partnership and respect. Today, PCUSA groups, in concert with the IPC, collaborate on a range of transnational political strategies aimed at strengthening the IPC’s leverage in local struggles for justice and peace. A review of this case suggests that long-established Christian networks may have an advantage over other civil society groups such as NGOs in facilitating strategies of transnational alliance. Although civil society organizations often have better access to important resources needed for international advocacy initiatives, Christian networks, such as the one established between the IPC and U.S. Presbyterian communities, rely on a history of negotiating power-disparity in order to elaborate relationships based on listening and partnership. Such findings prove important not only to how we conceptualize transnational alliance but also to the ways that we think about the history and future of Christian networks.

Oral re-vaccination of Eurasian wild boar with Mycobacterium bovis BCG yields a strong protective response against challenge with a field strain

BACKGROUND Field vaccination trials with Mycobacterium bovis BCG, an attenuated mutant of M. bovis, are ongoing in Spain, where the Eurasian wild boar (Sus scrofa) is regarded as the main driver of animal tuberculosis (TB). The oral baiting strategy consists in deploying vaccine baits twice each summer, in order to gain access to a high proportion of wild boar piglets. The aim of this study was to assess the response of wild boar to re-vaccination with BCG and to subsequent challenge with an M. bovis field strain. RESULTS BCG re-vaccinated wild boar showed reductions of 75.8% in lesion score and 66.9% in culture score, as compared to unvaccinated controls. Only one of nine vaccinated wild boar had a culture-confirmed lung infection, as compared to seven of eight controls. Serum antibody levels were highly variable and did not differ significantly between BCG re-vaccinated wild boar and controls. Gamma IFN levels differed significantly between BCG re-vaccinated wild boar and controls. The mRNA levels for IL-1b, C3 and MUT were significantly higher in vaccinated wild boar when compared to controls after vaccination and decreased after mycobacterial challenge. CONCLUSIONS Oral re-vaccination of wild boar with BCG yields a strong protective response against challenge with a field strain. Moreover, re-vaccination of wild boar with BCG is not counterproductive. These findings are relevant given that re-vaccination is likely to happen under real (field) conditions.