Field ecology and impact of the seed-feeding beetle Acanthoscelides macrophthalmus, a biological control agent of the invasive tree Leucaena leucocephala, in the KwaZulu-Natal coastal region.

M. Sc. University of KwaZulu-Natal, Pietermaritzburg 2014.Introduced for agroforestry, the Mexican tree Leucaena leucocephala (Fabaceae) has become invasive in several tropical and subtropical regions worldwide. In South Africa, the most notable infestations are located in the KwaZulu-Natal (KZN) coastal region. A seed-feeding beetle, Acanthoscelides macrophthalmus, originally imported from Mexico, was released in South Africa to control the plant’s excessive seed production and has become widely established in the KZN coastal region. By sampling plant populations monthly at selected field sites in this region, this study was intended to determine the: (i) seasonal (monthly) abundance of the beetle populations; (ii) levels of seed damage inflicted in relation to seed production by the plants; (iii) extent to which the beetle has recruited native parasitoids; (iv) incidence of non-target effects; and (v) ability of the beetle to regulate/control plant populations or limit their spread. Beetle numbers fluctuated greatly between months and between sites, resulting in erratic levels of seed damage ranging from 2-60%. Although ripe pods were available to the beetles throughout the year at one of the four study sites, this was not the case at the other three sites where ripe pods were virtually absent from November to January. High numbers of undamaged seeds found on the soil surface indicated the extent to which the seeds escape beetle predation. Parasitism of the beetle’s larval/pupal stages by native parasitoids was variable and relatively high (up to 40%). Ten species of parasitic wasps were reared from beetle-infested seeds, the most important of which originated from native Acacia plants. There were no instances of non-target effects involving the seeds of native Acacia species. There was a strong positive relationship between wasp numbers and beetle-infested seeds, indicating that the relationship is not incidental, and that the beetle has been adopted by the wasps as a new host. The relationship between the percentage of seeds damaged by A. macrophthalmus and seed availability was inversely density-dependent, with higher rates of seed damage occurring when fewer seeds were available. This negative relationship between seed damage and seed availability, as well as the relatively low levels of seed damage recorded, suggest that the beetle’s impact is negligible. The addition of other seed-feeding or seed-reducing agents to the L. leucocephala system may result in a more significant contribution from A. macrophthalmus

Experiences of living with visible difference: Individual and social reflections

Many health conditions impact upon an individual’s appearance and result in an altered appearance (“visible difference”). The presence of visible difference is associated with a variety of psychosocial difficulties and challenges, yet calls for an integrated theory of adjustment remain largely unanswered. This qualitative research, conducted in the United Kingdom, drew upon 22 interviews conducted with participants who had a variety of visible differences. It examined their experiences and reflections related to their difference and the impact that their visible difference had upon their lives. A thematic analysis produced two themes. The first of which was predominantly concerned with the impact of visible difference upon the individual whilst the second captured the inherently social nature of appearance and appearance based judgements. The analysis is considered in light of the contention that an integrated theory of adjustment to visible difference is required and participants’ experiences with healthcare professionals and the implications for those providing care are introduced

Intra-tumoral heterogeneity in metastatic potential and survival signaling between iso-clonal HCT116 and HCT116b human colon carcinoma cell lines.

BACKGROUND: Colorectal cancer (CRC) metastasis is a leading cause of cancer-related deaths in the United States. The molecular mechanisms underlying this complex, multi-step pathway are yet to be completely elucidated. Recent reports have stressed the importance of intra-tumoral heterogeneity in the development of a metastatic phenotype. The purpose of this study was to characterize the intra-tumoral phenotypic heterogeneity between two iso-clonal human colon cancer sublines HCT116 and HCT116b on their ability to undergo metastatic colonization and survive under growth factor deprivation stress (GFDS). MATERIALS AND METHODS: HCT116 and HCT116b cells were transfected with green fluorescence protein and subcutaneously injected into BALB/c nude male mice. Once xenografts were established, they were excised and orthotopically implanted into other male BALB/c nude mice using microsurgical techniques. Animal tissues were studied for metastases using histochemical techniques. Microarray analysis was performed to generate gene signatures associated with each subline. In vitro assessment of growth factor signaling pathway was performed under GFDS for 3 and 5 days. RESULTS: Both HCT116 and HCT116b iso-clonal variants demonstrated 100% primary tumor growth, invasion and peritoneal spread. However, HCT116 was highly metastatic with 68% metastasis observed in liver and/or lungs compared to 4% in HCT116b. Microarray analysis revealed an upregulation of survival and metastatic genes in HCT116 cells compared to HCT116b cells. In vitro analysis showed that HCT116 upregulated survival and migratory signaling proteins and downregulated apoptotic agents under GFDS. However, HCT116b cells effectively showed the opposite response under stress inducing cell death. CONCLUSIONS: We demonstrate the importance of clonal variation in determining metastatic potential of colorectal cancer cells using the HCT116/HCT116b iso-clonal variants in an orthotopic metastatic mouse model. Determination of clonal heterogeneity in patient tumors can serve as useful tools to identify clinically relevant biomarkers for diagnostic and therapeutic assessment of metastatic colorectal cancer

Transforming growth factor-β suppresses metastasis in a subset of human colon carcinoma cells.

BACKGROUND: TGFβ signaling has typically been associated with suppression of tumor initiation while the role it plays in metastasis is generally associated with progression of malignancy. However, we present evidence here for an anti-metastatic role of TGFβ signaling. METHODS: To test the importance of TGFβ signaling to cell survival and metastasis we compared human colon carcinoma cell lines that are either non-tumorigenic with TGFβ response (FET), or tumorigenic with TGFβ response (FETα) or tumorigenic with abrogated TGFβ response via introduction of dominant negative TGFβRII (FETα/DN) and their ability to metastasize. Metastatic competency was assessed by orthotopic transplantation. Metastatic colony formation was assessed histologically and by imaging. RESULTS: Abrogation of TGFβ signaling through introduction of a dominant negative TGFβ receptor II (TGFβRII) in non-metastatic FETα human colon cancer cells permits metastasis to distal organs, but importantly does not reduce invasive behavior at the primary site. Loss of TGFβ signaling in FETα-DN cells generated enhanced cell survival capabilities in response to cellular stress in vitro. We show that enhanced cellular survival is associated with increased AKT phosphorylation and cytoplasmic expression of inhibitor of apoptosis (IAP) family members (survivin and XIAP) that elicit a cytoprotective effect through inhibition of caspases in response to stress. To confirm that TGFβ signaling is a metastasis suppressor, we rescued TGFβ signaling in CBS metastatic colon cancer cells that had lost TGFβ receptor expression due to epigenetic repression. Restoration of TGFβ signaling resulted in the inhibition of metastatic colony formation in distal organs by these cells. These results indicate that TGFβ signaling has an important role in the suppression of metastatic potential in tumors that have already progressed to the stage of an invasive carcinoma. CONCLUSIONS: The observations presented here indicate a metastasis suppressor role for TGFβ signaling in human colon cancer cells. This raises the concern that therapies targeting inhibition of TGFβ signaling may be imprudent in some patient populations with residual TGFβ tumor suppressor activity

Adjunctive rifampicin for Staphylococcus aureus bacteraemia (ARREST): a multicentre, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Staphylococcus aureus bacteraemia is a common cause of severe community-acquired and hospital-acquired infection worldwide. We tested the hypothesis that adjunctive rifampicin would reduce bacteriologically confirmed treatment failure or disease recurrence, or death, by enhancing early S aureus killing, sterilising infected foci and blood faster, and reducing risks of dissemination and metastatic infection. METHODS: In this multicentre, randomised, double-blind, placebo-controlled trial, adults (≥18 years) with S aureus bacteraemia who had received ≤96 h of active antibiotic therapy were recruited from 29 UK hospitals. Patients were randomly assigned (1:1) via a computer-generated sequential randomisation list to receive 2 weeks of adjunctive rifampicin (600 mg or 900 mg per day according to weight, oral or intravenous) versus identical placebo, together with standard antibiotic therapy. Randomisation was stratified by centre. Patients, investigators, and those caring for the patients were masked to group allocation. The primary outcome was time to bacteriologically confirmed treatment failure or disease recurrence, or death (all-cause), from randomisation to 12 weeks, adjudicated by an independent review committee masked to the treatment. Analysis was intention to treat. This trial was registered, number ISRCTN37666216, and is closed to new participants. FINDINGS: Between Dec 10, 2012, and Oct 25, 2016, 758 eligible participants were randomly assigned: 370 to rifampicin and 388 to placebo. 485 (64%) participants had community-acquired S aureus infections, and 132 (17%) had nosocomial S aureus infections. 47 (6%) had meticillin-resistant infections. 301 (40%) participants had an initial deep infection focus. Standard antibiotics were given for 29 (IQR 18-45) days; 619 (82%) participants received flucloxacillin. By week 12, 62 (17%) of participants who received rifampicin versus 71 (18%) who received placebo experienced treatment failure or disease recurrence, or died (absolute risk difference -1·4%, 95% CI -7·0 to 4·3; hazard ratio 0·96, 0·68-1·35, p=0·81). From randomisation to 12 weeks, no evidence of differences in serious (p=0·17) or grade 3-4 (p=0·36) adverse events were observed; however, 63 (17%) participants in the rifampicin group versus 39 (10%) in the placebo group had antibiotic or trial drug-modifying adverse events (p=0·004), and 24 (6%) versus six (2%) had drug interactions (p=0·0005). INTERPRETATION: Adjunctive rifampicin provided no overall benefit over standard antibiotic therapy in adults with S aureus bacteraemia. FUNDING: UK National Institute for Health Research Health Technology Assessment

Intra-Tumoral Heterogeneity in Metastatic Potential and Survival Signaling between Iso-Clonal HCT116 and HCT116b Human Colon Carcinoma Cell Lines

<div><p>Background</p><p>Colorectal cancer (CRC) metastasis is a leading cause of cancer-related deaths in the United States. The molecular mechanisms underlying this complex, multi-step pathway are yet to be completely elucidated. Recent reports have stressed the importance of intra-tumoral heterogeneity in the development of a metastatic phenotype. The purpose of this study was to characterize the intra-tumoral phenotypic heterogeneity between two iso-clonal human colon cancer sublines HCT116 and HCT116b on their ability to undergo metastatic colonization and survive under growth factor deprivation stress (GFDS).</p> <p>Materials and Methods</p><p>HCT116 and HCT116b cells were transfected with green fluorescence protein and subcutaneously injected into BALB/c nude male mice. Once xenografts were established, they were excised and orthotopically implanted into other male BALB/c nude mice using microsurgical techniques. Animal tissues were studied for metastases using histochemical techniques. Microarray analysis was performed to generate gene signatures associated with each subline. <i>In vitro</i> assessment of growth factor signaling pathway was performed under GFDS for 3 and 5 days.</p> <p>Results</p><p>Both HCT116 and HCT116b iso-clonal variants demonstrated 100% primary tumor growth, invasion and peritoneal spread. However, HCT116 was highly metastatic with 68% metastasis observed in liver and/or lungs compared to 4% in HCT116b. Microarray analysis revealed an upregulation of survival and metastatic genes in HCT116 cells compared to HCT116b cells. <i>In vitro</i> analysis showed that HCT116 upregulated survival and migratory signaling proteins and downregulated apoptotic agents under GFDS. However, HCT116b cells effectively showed the opposite response under stress inducing cell death.</p> <p>Conclusions</p><p>We demonstrate the importance of clonal variation in determining metastatic potential of colorectal cancer cells using the HCT116/HCT116b iso-clonal variants in an orthotopic metastatic mouse model. Determination of clonal heterogeneity in patient tumors can serve as useful tools to identify clinically relevant biomarkers for diagnostic and therapeutic assessment of metastatic colorectal cancer.</p> </div

Results of orthotopic implantation of HCT116 and HCT116b tumor xenografts demonstrating the primary invasion and metastases based on histologic evaluation.

<p>Results of orthotopic implantation of HCT116 and HCT116b tumor xenografts demonstrating the primary invasion and metastases based on histologic evaluation.</p

Cell death response under growth factor deprivation stress (GFDS).

<p>(<i>A</i>) HCT116 cells are resistant to GFDS-induced cell death as determined by DNA fragmentation assay. However, HCT116b iso-clonal cells induce cell death under GFDS. (<i>B</i>) HCT116b cells induce cell death by time-dependent increase in PARP and caspase 3 cleavages and dephosphorylation of anti-apoptotic pBad protein.</p