Life sciences and Bio-engineering

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Life Sciences are among the most exciting areas of biological research, comprising all fields of science that involve the study of living organisms: plants, animals, human beings and microorganisms. Biology, plant and animal ecology, agriculture and medicine are the main centerpieces of the life sciences. Modern research employing molecular biology and biotechnology has extended the life sciences to diverse specializations, with real-life applications in health, agriculture, ecology as well as in bio-industries.

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Rise in erythropoietin concentrations in experimental Trypanosoma congolense infection of calves
(Elsevier Ltd, 1995-11) Buza, Joram; Logan-Henfrey, Linda; Andrianarivo, Aurélie; Williams, Diana
A bioassay was used to measure erythropoietin (EPO) concentrations in calves with haemorrhagic anaemia due to blood loss and in calves with anaemia due to Trypanosoma congolense infection. The bioactivity of EPO was measured in the assay by its stimulatory effect on 125I-deoxyuridine incorporation in spleen cells from phenylhydrazine-treated mice. Erythropoietin concentrations in blood-volume-depleted calves were elevated 6h after blood loss, maximal (1225 mU/ml) at 33 h and below detection limits at 72 h. Reticulocytes (0·05±0·1%) appeared in blood by 72 h, peaked at 120 h and disappeared from the circulation by 7 days after bleeding. The packed cell volume (PCV) started increasing at 120 h and reached near prebleeding values by 14 days. In T. congolense-infected calves, parasites were first detected in the peripheral blood 12 days post-infection (dpi). Parasitaemia peaked (5×105 trypanosomes/ml of blood) at 15–18 dpi and, thereafter, several waves of parasitaemia were observed, but the peaks gradually diminished. Undiluted plasma from T. congolense-infected calves suppressed 125I-deoxyuridine incorporation into spleen cells from 13 dpi onwards. The suppressive effect of plasma was partly negated by five-fold dilution, which made possible the detection of increased EPO concentrations during the acute and chronic stages of the anaemia. The highest EPO peaks, reaching 2300 mU/ml in one calf, were detected during the chronic stage of the infection. At 15–39 dpi, there was a transient bone-marrow erythropoietic response characterized by an increase in mean corpuscular volume and a decrease in mean corpuscular haemoglobin concentration but with few reticulocytes (0·4%). However, from 76 dpi onwards, this response waned despite low PCV and elevated EPO concentrations. These results suggest that there is an ineffective erythroid response in the face of elevated EPO concentrations during bovine trypanosomiasis. The negative effect of plasma and serum from trypanosome-infected calves on the in-vitro bioactivity of EPO suggests the presence of inhibitory factors.
Modifications of the hydrophilicity of heterocyclic methacrylate copolymers for protein release
(Elsevier, 1995-12) Downesa, S.; Patel, M.; Di Silvio, L.; Swai, Hulda; Davy, K.; Braden, M.
A series of copolymers comprising ethyl methacrylate (EM) and tetrahydrofurfuryl methacrylate (THFMA) gelled with either THFMA monomer or hydroxyethyl methacrylate (HEMA) monomer have been developed. In this paper, we examine the water uptake characteristics of the polymer systems and address the possibility of increasing the hydrophilicity of the systems by changing the ratios of the copolymers. We have investigated whether protein release from the polymers is related to the composition of the polymer systems. More protein was released from the polymers gelled with the more hydrophilic monomer (HEMA) than with THFMA. This was consistent with the calculated diffusion coefficients, which were 10 times greater for the polymers gelled with HEMA than those gelled with THFMA. Interestingly, the water uptake and protein release profiles were not dependent on the ratio of EM and THFMA in the copolymers. This is probably due to the conflicting roles of THFMA in the copolymer; it is both the more hydrophilic component as well as a cross-linking agent. In addition, it would appear that the structural and surface topography of these polymers had more significant effects on protein release than copolymer composition.
CD5+ B lymphocytes are the main source of antibodies reactive with non-parasite antigens in Trypanosoma congolense-infected cattle
(Blackwell Science Ltd, 1997) Buza, Joram; Sileghem, Maarten; Gwakisa, Paul; Naessens, Jan
Mice infected with African trypanosomes produce exceptionally large amounts of serum IgM, a major part of which binds to non-trypanosome antigens such as trinitrophenol and single-strand DNA. In this paper, we describe that in cattle infected with Trypanosoma congolense and T. vivax, similar antibodies are found, although they bind mainly to protein antigens, such as b-galactosidase, ovalbumin and ferritin. The parasite non-specific IgM antibodies appear around the same time as the parasite-specific antibodies, but their origin and function are not clear.We tested the hypothesis that CD5+ B cells (or B-1 cells), which increase during trypanosome infections in cattle, are responsible for production of antibodies to non-trypanosome antigens. Splenic CD5+ and CD5− B cells from infected cattle were sorted and tested in a single cell blot assay. The numbers of immunoglobulin-secreting cells were similar in both B-cell populations. However, antibodies with reactivity for non-trypanosome antigens were significantly more prevalent in the CD5+ B-cell fraction and were exclusively IgM. The preference for production of these antibodies by CD5+ B cells and the expansion of this subpopulation during infections in cattle, strongly suggest that CD5+ B cells are the main source of trypanosome non-specific antibodies. We propose that these antibodies are natural, polyreactive antibodies that are predominantly secreted by CD5+ B cells. Since B-1 cells are up-regulated in many states of immune insufficiency, the immunosuppression associated with trypanosome infections may be responsible for the increase of this subset and the concomitant increase in trypanosome non-specific antibodies.
The water uptake of poly(tetrahydrofurfuryl methacrylate)
(Elsevier, 1999-03) Riggs, P. D.; Braden, M.; Tilbrook, D. A.; Swai, Hulda; Clarke, R. L.; Patel, M. P.
Poly(tetrahydrofurfuryl methacrylate) possesses some unique characteristics with respect to its biocompatibility and behaviour in water. The water uptake is high (>70%) and very slow (over 3 yr), but the material remains rigid throughout the process. The mechanism behind the uptake is in two stages; an initial Fickian stage, then as the matrix approaches saturation (about 3 wt%) a second clustering mechanism takes over. The rate of uptake of the second stage of the uptake is controlled by creep (or stress relaxation), and the chemical potential driving the uptake from clustering of the furfuryl rings of the polymer. If clustering or the creep is prevented (by appropriate co-polymerisation) the polymer behaves in an ideal, Fickian manner.
Trypanosome non-specific IgM antibodies detected in serum of Trypanosoma congolense-infected cattle are polyreactive
(Elsevier Science, 1999-07-01) Buza, Joram; Naessens, Jan
Serum Ig from Trypanosoma congolense-infected cattle were affinity-purified using immobilised trypanosome or non-trypanosome antigens (ß-galactosidase, cytochrome C and ferritin). The bound and unbound IgG and IgM fractions were collected and tested in ELISA for reactivity to each antigen. The results indicated that the presence of reactivity to non-parasite antigens in serum of infected cattle is due to polyreactive IgM antibodies. However, the IgG fraction only bound to trypanosome antigens and was only present in post-infection sera, indicating that it was induced by the infecting trypanosomes. Since the polyreactive IgM antibodies were also present in pre-infection sera, it is probable that they were natural antibodies that were not induced but only amplified by the trypanosome infection.
A polymeric system for the intra-oral delivery of an anti-fungal agent
(Elsevier Science Ltd., 2001) Patel, M.P.; Cruchley, A.T.; Coleman, D.C.; Swai, Hulda; Braden, M.; Williams, D.M.
Oral candidal infections are often persistent and intractable and thus the aim of this study was to develop a polymeric sustained release device to improve the topical treatment of these infections. A self curing system based on poly(ethyl methacrylate) and tetrahydrofurfuryl methacrylate (PEM/THFM) was used with chlorhexidine diacetate (CX) added at levels between 0 and 12% w/w. Water uptake by the device was assessed gravimetrically and CX release measured by UV spectrometry. Anti candidal activity was established by culturing azole sensitive and resistant strains of Candida albicans in the presence of the polymeric delivery device with and without CX. Candidal growth was measured by turbidimetry or surviving colony-forming unit (CFU) formation. There was an initial high release of CX over 24 h followed by a slow di!usion up to 7 days. CX inhibited candidal growth and survival markedly in vitro, with the test samples showing less than 0.5 10 CFU/ml compared to controls (3}4 10 CFU/ml). These results indicate the potential of a chlorhexidine containing PEM/THFM polymeric system in the treatment of persistent candidal infections. 2001 Elsevier Science Ltd. All rights reserved.
Local skin reaction (chancre) induced following inoculation of metacyclic trypanosomes in cattle by tsetse flies is dependent on CD4 T lymphocytes
(Blackwell Science Ltd, 2003) Naessens, Jan; Mwangi, Duncan; Buza, Joram; Moloo, Shamshudeen
The first visible response in livestock to the bite of a trypanosomeinfected tsetse fly is the formation of a localized skin reaction, also known as a chancre. This is an inflammatory response in the skin associated with swelling and an influx of cells. It is thought to be associated with an acquired immune response to the injected metacyclic trypanosomes. In this study, we examined the role of T lymphocytes in the development of the inflammatory response, by depleting cattle of T cell subpopulations and monitoring the development of chancres. Depletion of CD4 cells, but not CD8 cells, resulted in a significant reduction in chancre formation, confirming that an acquired response mediates the inflammatory response. In addition, it was established that the CD4 T cells mediate the generation of memory for immunity to a homologueous re-challenge. The inflammatory response in the skin did not affect further progress of the infection.
Mycobacterium bovis in rural Tanzania: Risk factors for infection in human and cattle populations
(Elsevier Ltd., 2007-01) Cleaveland, Sarah; Shawa, Darren; Mfinanga, Sayoki; Shirima, Gabriel; Kazwala, Rudovick; Eblatee, Ernest; Sharp, Michael
Although bovine tuberculosis is widespread throughout Africa, very little is known about risk factors for Mycobacterium bovis infection in either human or cattle populations. A human case–control study was conducted in northern Tanzania, comparing risk factors and prevalence of cattle interdermal test positives of cases (cervical adenitis cases from which M. bovis was isolated) with age- and sex-matched controls (selected at random from potential hospital attendees within the community). A cattle cross-sectional study was also set-up involving 27 villages selected at random in four districts, with 10,549 cattle and 622 herds tested, and questionnaire surveys conducted in 239 households. M. bovis was confirmed in seven of 65 (10.8%) human cervical adenitis cases, of which only one came from a household owning infected cattle. M. bovis in human patients was associated with families in which a confirmed diagnosis of tuberculosis had previously been made (p<0.001) and with households far (>100 m) from neighbours (p=0.003). In cattle, overall prevalence of intradermal test positives was low at 0.9% (0.70–1.06%), but widespread, with 11.8% (8.44–13.17%) herds containing at least one reactor. Prevalence of intradermal test positives increased significantly with cattle age (p<0.001). Herds with the following risk factors had a significantly greater prevalence of intradermal test positives: >50 cattle in the herd (p=0.024); herds housed inside at night (p=0.021) and herds in contact with wildlife (p=0.041). Furthermore, villages that experienced annual flooding had a higher prevalence of infection (p=0.043).
Genetic variants of CYP3A5, CYP2D6, SULT1A1, UGT2B15 and tamoxifen response in postmenopausal patients with breast cancer
(Springer Nature, 2007-01-23) Wegman, Pia; Sauli, Elingarami; Carstensen, John; Stål, Olle; Wingren, Sten
Introduction Tamoxifen therapy reduces the risk of recurrence and prolongs the survival of oestrogen-receptor-positive patients with breast cancer. Even if most patients benefit from tamoxifen, many breast tumours either fail to respond or become resistant. Because tamoxifen is extensively metabolised by polymorphic enzymes, one proposed mechanism underlying the resistance is altered metabolism. In the present study we investigated the prognostic and/or predictive value of functional polymorphisms in cytochrome P450 3A5 CYP3A5 (*3), CYP2D6 (*4), sulphotransferase 1A1 (SULT1A1; *2) and UDP-glucuronosyltransferase 2B15 (UGT2B15; *2) in tamoxifen-treated patients with breast cancer. Methods In all, 677 tamoxifen-treated postmenopausal patients with breast cancer, of whom 238 were randomised to either 2 or 5 years of tamoxifen, were genotyped by using PCR with restriction fragment length polymorphism or PCR with denaturing high-performance liquid chromatography. Results The prognostic evaluation performed in the total population revealed a significantly better disease-free survival in patients homozygous for CYP2D6*4. For CYP3A5, SULT1A1 and UGT2B15 no prognostic significance was observed. In the randomised group we found that for CYP3A5, homozygous carriers of the *3 allele tended to have an increased risk of recurrence when treated for 2 years with tamoxifen, although this was not statistically significant (hazard ratio (HR) = 2.84, 95% confidence interval (CI) = 0.68 to 11.99, P = 0.15). In the group randomised to 5 years' tamoxifen the survival pattern shifted towards a significantly improved recurrence-free survival (RFS) among CYP3A5*3-homozygous patients (HR = 0.20, 95% CI = 0.07 to 0.55, P = 0.002). No reliable differences could be seen between treatment duration and the genotypes of CYP2D6, SULT1A1 or UGT2B15. The significantly improved RFS with prolonged tamoxifen treatment in CYP3A5*3 homozygotes was also seen in a multivariate Cox model (HR = 0.13, CI = 0.02 to 0.86, P = 0.03), whereas no differences could be seen for CYP2D6, SULT1A1 and UGT2B15. Conclusion The metabolism of tamoxifen is complex and the mechanisms responsible for the resistance are unlikely to be explained by a single polymorphism; instead it is a combination of several mechanisms. However, the present data suggest that genetic variation in CYP3A5 may predict response to tamoxifen therapy.
Modeling the proteome of a Marek's disease transformed cell line: a natural animal model for CD30 overexpressing lymphomas.
(Proteomics, 2007-04-18) Buza, Joram; Burgess, Shane
Marek's disease (MD) in the chicken, caused by the highly infectious MD alpha-herpesvirus (MDV), is both commercially important and a unique, naturally occurring model for human T-cell lymphomas overexpressing the Hodgkin's disease antigen, CD30. Here, we used proteomics as a basis for modeling the molecular functions and biological processes involved in MDV-induced lymphomagenesis. Proteins were extracted from an MDV-transformed cell line and were then identified using 2-D LC-ESI-MS/MS. From the resulting 3870 cellular and 21 MDV proteins we confirm the existence of 3150 "predicted" and 12 "hypothetical" chicken proteins. The UA-01 proteome is proliferative, differentiated, angiogenic, pro-metastatic and pro-immune-escape but anti-programmed cell death, -anergy, -quiescence and -senescence and is consistent with a cancer phenotype. In particular, the pro-metastatic integrin signaling pathway and the ERK/MAPK signaling pathways were the two predominant signaling pathways represented. The cytokines, cytokine receptors, and their related proteins suggest that UA-01 has a regulatory T-cell phenotype.
CD14+ cells are required for IL-12 response in bovine blood mononuclear cells activated with Toll-like receptor (TLR) 7 and TLR8 ligands
(Elsevier, 2008) Buza, Joram; Benjamin, Ponn; Zhu, Jianzhung; Wilson, Heather; Lipford, Grayson; Krieg, Arthur; Babiuk, Lorne; Mutwiri, George
Single-stranded viral RNA (ssRNA) was recently identified as the natural ligand for TLR7 and TLR8. ssRNA sequences from viruses, as well as their synthetic analogues stimulate innate immune responses in immune cells from humans and mice, but their immunostimulatory activity has not been investigated in ruminants. In the present investigations, we tested whether synthetic RNA oligoribonucleotides (ORN) can activate immune cells from cattle. In vitro incubation of bovine peripheral blood mononuclear cells (PBMCs) with ORN-induced production of IL-12, IFN-g and TNF-a. No significant induction of IFN-a was observed. Depletion of CD14+ cells from PBMC abrogated the IL-12 response and consequently the IFN-g response, suggesting that CD14+ cells are required for PBMC immune activation with ORN. Consistent with these findings, the putative receptors for ORN (TLR7 and TLR8) were expressed at higher levels in the CD14+ fraction than the CD14 PBMC fraction. Pre-treatment of PBMC with bafilomycin (an inhibitor of phagosomal acidification) prior to stimulation with ORN abolished the cytokine responses, confirming that the receptor(s) which mediate the ORN-induced responses are intracellular. These results demonstrate for the first time that the TLR7/8 agonist ORN’s have strong immune stimulatory effects in cattle, and suggest that further investigation on the potential of TLR7/8 ligands to activate innate and adaptive immune responses in domestic animals are warranted.
The neoplastically transformed (CD30hi) Marek’s disease lymphoma cell phenotype most closely resembles T-regulatory cells
(Springer-Verlag, 2008-02-07) Shack, Leslie; Buza, Joram; Burgess, Shane
Introduction Marek’s disease (MD), a herpesvirus-induced lymphoma of chickens is a unique natural model of CD30- overexpressing (CD30hi) lymphoma. We have previously proposed that the CD30hi neoplastically transformed CD4+ T cells in MD lymphomas have a phenotype antagonistic to cell mediated immunity. Here were test the hypothesis that the CD30hi neoplastically transformed MD lymphoma cells have a phenotype more closely resembling T-helper (Th)-2 or regulatory T (T-reg) cells. Materials and methods We separated ex vivo-derived CD30hi, from the CD30lo/¡ (non-transformed), MD lymphoma cells and then quantiWed the relative amounts of mRNA and proteins for cytokines and other genes that deWne CD4+ Th-1, Th-2 or T-reg phenotypes. Results and discussion Gene Ontology-based modeling of our data shows that the CD30hi MD lymphoma cells having a phenotype more similar to T-reg. Sequences that could be bound by the MD virus putative oncoprotein Meq in each of these genes’ promoters suggests that the MD herpesvirus may play a direct role in maintaining this T-reg-like phenotype.
Genotype-Dependent Tumor Regression in Marek’s Disease Mediated at the Level of Tumor Immunity
(Springer, 2008-03-18) Kumar, Shyamesh; Buza, Joram; Burgess, Shane
Marek’s disease (MD) of chickens is a unique natural model of Hodgkin’s and Non Hodgkin’s lymphomas in which the neoplastically-transformed cells over-express CD30 (CD30hi) antigen. All chicken genotypes can be infected with MD virus and develop microscopic lymphomas. From 21 days post infection (dpi) microscopic lymphomas regress in resistant chickens but, in contrast, they progress to gross lymphomas in susceptible chickens. Here we test our hypothesis that in resistant chickens at 21 dpi the tissue microenvironment is pro T-helper (Th)-1 and compatible with cytotoxic T lymphocyte (CTL) immunity but in susceptible lines it is pro Th-2 or pro T-regulatory (T-reg) and antagonistic to CTL immunity. We used the B2, non-MHC-associated, MD resistance/susceptibility system (line [L]61/line [L]72) and quantified the levels of key mRNAs that can be used to define Th-1 (IL-2, IL-12, IL-18, IFNγ), Th-2 (IL-4, IL-10) and T-reg (TGFβ, GPR-83, CTLA-4, SMAD-7) lymphocyte phenotypes. We measured gene expression in both whole tissues (represents tissue microenvironment and tumor microenvironment) and in the lymphoma lesions (tumor microenvironment) themselves. Gene ontology-based modeling of our results shows that the dominant phenotype in whole tissue as well as in microscopic lymphoma lesions, is pro T-reg in both L61 and L72 but a minor pro Th-1 and anti Th-2 tissue microenvironment exists in L61 whereas there is an anti Th-1 and pro Th-2 tissue microenvironment in L72. The tumor microenvironment per se is pro T-reg, anti Th-1 and pro Th-2 in both L61 and L72. Together our data suggests that the neoplastic transformation is essentially the same in both L61 and L72 and that resistance/susceptibility is
Germination of Invasive Plant Seeds after Digestion by Horses in California
(Natural Areas Journal, 2008-10) Quinn, Lauren D.; Kolipinski, Mietek; Coelho, Vânia R.; Davis, Bonnie; Vianney, John-Mary; Batjargal, Orgiltuya; Alas, Monika; Ghosh, Sibdas
Using a unique sterile design intended to eliminate outside seed contamination of horse feces, we investigated whether weed seeds germinate after digestion by horses. Feces were collected from selected National Parks and other locations in central and northern California. All potted fecal samples were irrigated and grown in an enclosed sterile nursery environment. Thirty-two plant species emerged from these fecal samples, 24 of which were not native to California. None of these were identified on the California Department of Agriculture’s Noxious Weed List, which is used as a basis to certify equine feed as weed free. However, seven of the non-native species are identified as moderately invasive on the California Invasive Plant Council’s (Cal-IPC) list. These species are: Hirschfeldia incana, Hordeum marinum, Lolium multiflorum, Mentha pulegium, Rumex acetosella, Trifolium hirtum, and Vulpia myuros. In addition, the following four non-native plants are listed at the limited invasiveness level on the Cal-IPC list: Hypochaeris glabra, Lythrum hyssopifolium, Medicago polymorpha, and Poa pratensis. Because we did not survey invasive plant cover in locations from which we sampled, we cannot guarantee that species identified in our samples would have also germinated in the field. Our results add to a growing body of literature documenting germination of seeds after passing through the digestive system of horses and suggest that conscientious horse owners should select feed sources that are free of weeds. We also find that the current list of noxious weeds used to certify weed-free feed for equines should be comprehensive.
Potential of treating tuberculosis with a polymeric nano-drug delivery system
(Elsevier, 2008-12-18) Swai, Hulda; Semete, B.; Kalombo, Lonji; Chelule, P.
An effective therapeutic regimen is available for the treatment of tuberculosis (TB), however in developing countries; patient non-compliance due to high dose frequency and the lengthy duration of treatment, presents a major challenge, thus resulting in treatment failure. To address this challenge, the project seeks to develop a nano-drug delivery system whereby anti-TB drugs can be administered in a single dose that maintains an active level of the drug for at least one week.
Rooting and growth potential of Leucadendron laxum (proteaceae) using different rooting mediums and indoleacetic acid growth regulators
(Sabinet African Journals About Sabin, 2009-01-01) Laubscher, Charles Petrus; Ndakidemi, Patrick A.
Leucadendron laxum (Proteaceae) is a South African plant species with a high commercial value as a flowering potted plant. Limited research information on the culture and propagation of this species is available in South Africa. The application of rooting hormone indole acetic acid (IAA) in various rooting mediums in L. laxum was tested. The treatments included: control, 500, 1000, 2000 and 4000 ppm, and four rooting mediums: a) bark / polystyrene; b) peat moss / polystyrene; c) bark / river sand / polystyrene; and d) perlite / river sand. A randomised block design with three replicates was used. Compared with other mediums, bark and polystyrene had the highest significant results in root and shoot growth, and the percentage that callused, rooted and survived. The IAA treatments at different concentrations had significant effects on rooting, callusing, shoot growth, root lengths and numbers of roots per cutting.
Occurrence of patulin in various fruit juices from South Korea: An exposure assessment
(Springer Nature Switzerland AG., 2010-02-28) Cho, Mi Sook; Kim, Kyeongyeol; Seo, Eunkyoung; Kassim, Neema; Mtenga, Adelard B.; Shim, Won-Bo; Lee, Soo-Hyung; Chung, Duck-Hwa
To determine patulin in various fruit juices, high performance liquid chromatography (HPLC) method was optimized and validated. For validation of HPLC method, a linearity, accuracy, precision, detection limit, and quantification limit were determined. Linearity (R2 = 0.99995), accuracy (96.1–115.7%), precision (3.31–9.52), detection limit (6 ng/mL), and quantification limit (8 ng/mL) were in agreement with performance criteria for patulin as set by the European Commission hence proved that HPLC can be used to detect patulin in fruit juices. After validation, the method was applied to estimate the prevalence of patulin in fruit juices (apple, grape, and orange juices). Nine samples (12.5%, 3 apple, 2 orange, and 4 grape juices) of 72 samples were positive for patulin in the range 2.8 to 30.9 ng/mL. According to the monitoring results, daily intake was estimated to be 0.17 ng/kg BW/day which was lower than the provisional maximum tolerable daily intake (0.4 μg/kg) established by Joint Expert Committee on Food Additives. These results indicate that the detection method coincides with the performance criteria and is appropriate for analysis of patulin, and continuous monitoring of patulin in various fruit juices from Korea is necessary.
Evaluation of housing as a means to protect cattle from Culicoides biting midges, the vectors of bluetongue virus.
(The Royal Entomological Society, 2010-03-01) Baylis, Matthew; Parkin, H; Kreppel, Katharina; Carpenter, S; Mellor, P S; McIntyre, K M
The housing of animals at night was investigated as a possible means of protecting them from attack by Culicoides biting midges (Diptera: Ceratopogonidae), the vectors of bluetongue. Light-trap catches of Culicoides were compared inside and outside animal housing, in the presence and absence of cattle. A three-replicate, 4 x 4 Latin square design was used at four farms in Bala, north Wales, over 12 nights in May and June 2007, and the experiment repeated in October. In the two studies, respectively, >70 000 and >4500 Culicoides were trapped, of which 93% and 86%, respectively, were of the Culicoides obsoletus group. Across the four farms, in May and June, the presence of cattle increased catches of C. obsoletus by 2.3 times, and outside traps caught 6.5 times more insects than inside traps. Similar patterns were apparent in October, but the difference between inside and outside catches was reduced. Catches were strongly correlated with minimum temperature and maximum wind speed and these two variables explained a large amount of night-to-night variation in catch. Outside catches were reduced, to a greater extent than inside catches, by colder minimum temperatures and higher maximum wind speeds. These conditions occur more frequently in October than in May and June, thereby suppressing outside catches more than inside catches, and reducing the apparent degree of exophily of C. obsoletus in autumn. The results suggest that the risk of animals receiving bites from C. obsoletus is reduced by housing at both times of year and the benefit would be greatest on warm, still nights when outside catches are at their greatest.
In vivo uptake and acute immune response to orally administered chitosan and PEG coated PLGA nanoparticles
(Elsevier, 2010-09-17) Semete, B.; Booysen, L. I. J.; Kalombo, L.; Venter, J. D.; Katata, L.; Ramalapa, B.
Nanoparticulate drug delivery systems offer great promise in addressing challenges of drug toxicity, poor bioavailability and non-specificity for a number of drugs. Much progress has been reported for nano drug delivery systems for intravenous administration, however very little is known about the effects of orally administered nanoparticles. Furthermore, the development of nanoparticulate systems necessitates a thorough understanding of the biological response post exposure. This study aimed to elucidate the in vivo uptake of chitosan and polyethylene glycol (PEG) coated Poly, DL, lactic-co-glycolic Acid (PLGA) nanoparticles and the immunological response within 24 h of oral and peritoneal administration. These PLGA nanoparticles were administered orally and peritoneally to female Balb/C mice, they were taken up by macrophages of the peritoneum. When these particles were fluorescently labelled, intracellular localisation was observed. The expression of pro-inflammatory cytokines IL-2, IL-6, IL-12p70 and TNF-α in plasma and peritoneal lavage was found to remain at low concentration in PLGA nanoparticles treated mice as well as ZnO nanoparticles during the 24 hour period. However, these were significantly increased in lipopolysaccharide (LPS) treated mice. Of these pro-inflammatory cytokines, IL-6 and IL-12p70 were produced at the highest concentration in the positive control group. The anti-inflammatory cytokines IL-10 and chemokines INF-γ, IL-4, IL-5 remained at normal levels in PLGA treated mice. IL-10 and INF-γ were significantly increased in LPS treated mice. MCP-1 was found to be significantly produced in all groups in the first hours, except the saline treated mice. These results provide the first report to detail the induction of cytokine production by PLGA nanoparticles engineered for oral applications.
In vivo evaluation of the biodistribution and safety of PLGA nanoparticles as drug delivery systems
(Elsevier Inc., 2010-10) Semete, Boitumelo; Booysen, Laetitia; Lemmer, Yolandy; Kalombo, Lonji; Katata, Lebogang; Verschoor, Jan
The remarkable physicochemical properties of particles in the nanometer range have been proven to address many challenges in the field of science. However, the possible toxic effects of these particles have raised some concerns. The aim of this article is to evaluate the effects of poly(lactide-co-glycolide) (PLGA) nanoparticles in vitro and in vivo compared to industrial nanoparticles of a similar size range such as zinc oxide, ferrous oxide, and fumed silica. An in vitro cytotoxicity study was conducted to assess the cell viability following exposure to PLGA nanoparticles. Viability was determined by means of a WST assay, wherein cell viability of greater than 75% was observed for both PLGA and amorphous fumed silica particles and ferrous oxide, but was significantly reduced for zinc oxide particles. In vivo toxicity assays were performed via histopathological evaluation, and no specific anatomical pathological changes or tissue damage was observed in the tissues of Balb/C mice. The extent of tissue distribution and retention following oral administration of PLGA particles was analyzed for 7 days. After 7 days, the particles remained detectable in the brain, heart, kidney, liver, lungs, and spleen. The results show that a mean percentage (40.04%) of the particles were localized in the liver, 25.97% in the kidney, and 12.86% in the brain. The lowest percentage was observed in the spleen. Thus, based on these assays, it can be concluded that the toxic effects observed with various industrial nanoparticles will not be observed with particles made of synthetic polymers such as PLGA when applied in the field of nanomedicine. Furthermore, the biodistribution of the particles warrants surface modification of the particles to avoid higher particle localization in the liver. From the clinical editor: The aim of this study was to evaluate the effects of poly(lactide-co-glycolide) (PLGA) nanoparticles in vitro and in vivo compared to industrial nanoparticles including zinc oxide, ferrous oxide, and fumed silica. The authors concluded that the toxic effects observed with various industrial nanoparticles is unlikely to be observed with particles made of PLGA. The biodistribution of these particles warrants surface modification to avoid particle accumulation in the liver.

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