Rakesh K. Kumar

Desmoplastic reaction in pancreatic cancer: role of pancreatic stellate cells.

Objectives: Pancreatic cancer has a very poor prognosis, largely due to its propensity for early local and distant spread. Histopathologically, most pancreatic cancers are characterized by a prominent stromal/fibrous reaction in and around tumor tissue. The aims of this study were to determine whether (1) the cells responsible for the formation of the stromal reaction in human pancreatic cancers are activated pancreatic stellate cells (PSCs) and (2) an interaction exists between pancreatic cancer cells and PSCs that may facilitate local and distant invasion of tumor. Methods: Serial sections of human pancreatic cancer tissue were stained for desmin and glial fibrillary acidic protein (stellate cell selective markers) and &agr;-smooth muscle actin (&agr;SMA), a marker of activated PSC activation, by immunohistochemistry, and for collagen using Sirius Red. Correlation between the extent of positive staining for collagen and &agr;SMA was assessed by morphometry. The cellular source of collagen in stromal areas was identified using dual staining methodology, ie, immunostaining for &agr;SMA and in situ hybridization for procollagen &agr;1I mRNA. The possible interaction between pancreatic cancer cells and PSCs was assessed in vitro by exposing cultured rat PSCs to control medium or conditioned medium from 2 pancreatic cancer cell lines (PANC-1 and MiaPaCa-2) for 24 hours. PSC activation was assessed by cell proliferation and &agr;SMA expression. Results: Stromal areas of human pancreatic cancer stained strongly positive for the stellate cell selective markers desmin and GFAP (indicating the presence of PSCs), for &agr;SMA (suggesting that the PSCs were in their activated state) and for collagen. Morphometric analysis demonstrated a close correlation (r = 0.77; P < 0.04; 8 paired sections) between the extent of PSC activation and collagen deposition. Procollagen mRNA expression was localized to &agr;SMA-positive cells in stromal areas indicating that activated PSCs were the predominant source of collagen in stromal areas. Exposure of PSCs to pancreatic cancer cell secretions in vitro resulted in PSC activation as indicated by significantly increased cell proliferation and &agr;SMA expression. Conclusions: Activated PSCs are present in the stromal reaction in pancreatic cancers and are responsible for the production of stromal collagen. PSC function is influenced by pancreatic cancer cells. Interactions between tumor cells and stromal cells (PSCs) may play an important role in the pathobiology of pancreatic cancer.

Adhesives and plastics based on soy protein products

Significance of eco-friendly materials based on easily renewable natural resources, and the finite nature of petrochemical resources, has necessitated the development of polymers from agricultural processing by products such as soy proteins from oil processing. Although, considerable work was done in the early part of last century on polymers based on soy protein, there was almost no activity in this field for the last fifty years. There is a need to critically analyse the available literature on soy protein based polymeric materials. Therefore, an attempt is made to review the state-of-the-art of the polymeric materials with emphasis on adhesives and plastics derived from soy protein, a renewable resource abundantly available in nature.

An improved murine model of asthma: selective airway inflammation, epithelial lesions and increased methacholine responsiveness following chronic exposure to aerosolised allergen

BACKGROUND Existing murine models of asthma lack many of the inflammatory and epithelial changes that are typical of the human disease. Moreover, these models are frequently complicated by allergic alveolitis. METHODS High IgE responder BALB/c mice were systemically sensitised to ovalbumin and chronically challenged with low particle mass concentrations of aerosolised ovalbumin. Titres of anti-ovalbumin IgE in serum were measured at two weekly intervals by enzyme immunoassay, accumulation of inflammatory cells and histopathological abnormalities of the epithelium were quantified morphometrically in the trachea and the lungs, and airway reactivity was assessed by measuring bronchoconstriction following intravenous administration of methacholine. RESULTS Mice sensitised by two intraperitoneal injections of ovalbumin developed high titres of IgE antibodies to ovalbumin. Following exposure to low concentrations of aerosolised antigen for up to eight weeks these animals developed a progressive inflammatory response in the airways, characterised by the presence of intraepithelial eosinophils and by infiltration of the lamina propria with lymphoid/mononuclear cells, without associated alveolitis. Goblet cell hyperplasia/metaplasia was induced in the intrapulmonary airways, while epithelial thickening and subepithelial fibrosis were evident following chronic exposure. In parallel, the mice developed increased sensitivity to induction of bronchospasm, as well as increased maximal reactivity. Non-immunised mice exposed to aerosolised ovalbumin had low or absent anti-ovalbumin IgE and did not exhibit inflammatory or epithelial changes, but developed airway hyperreactivity. CONCLUSIONS This experimental model replicates many of the features of human asthma and should facilitate studies of pathogenetic mechanisms and of potential therapeutic agents.

Mechanical behaviour of bamboo and bamboo composite

The tensile, flexural and impact strengths of bamboo and bamboo fibre-reinforced plastic (BFRP) composite have been evaluated. The high strengths of bamboo, in the fibre direction, have been explained by its anatomical properties and ultra structure. Bamboo fibres and bamboo orthogonal strip mats (bamboo mat) have been used to reinforce epoxy resin. BFRP composites with unidirectional, bidirectional and multidirectional strengths have been made. In bamboo mat composites, the fibre volume fraction,Vf, achieved was as high as 65%. The tensile, flexural and impact strengths of bamboo along the fibres are 200.5 MN m−2, 230.09 MN m−2 and 63.54 kJ m−2, respectively, whereas those of bamboo fibre composites and bamboo mat composites are 175.27 M N m−2, 151.83 MN m−2 and 45.6 kJ m−2, and 110.5 MN m−2, 93.6 M N m−2 and 34.03 kJ m−2, respectively. These composites possess a close to linear elastic behaviour. Scanning electron microscopy studies of the fractured BFRP composite specimens reveal a perfect bonding between bamboo fibres and the epoxy. Furthermore, high strength, low density, low production cost and ease of manufacturing make BFRP composite a commercially viable material for structural applications.

Expression of the chemokine IP‐10 (CXCL10) by hepatocytes in chronic hepatitis C virus infection correlates with histological severity and lobular inflammation

The factors influencing lymphocyte trafficking to the liver lobule during chronic hepaititis C virus (HCV) infection are currently not well defined. Interferon‐γ‐inducible protein 10 (IP‐10), a chemokine that recruits activated T lymphocytes, has recently been shown by in situ hybridization to be expressed in the liver during chronic HCV infection. This study sought to define the cellular source of IP‐10 in the liver by immunohistochemistry, to examine the expression of its receptor, CXCR3, on T lymphocytes isolated from blood and liver tissue, and to correlate IP‐10 expression with the histological markers of inflammation and fibrosis. IP‐10 was expressed by hepatocytes but not by other cell types within the liver, and the most intense immunoreactivity was evident in the areas of lobular inflammation. The IP‐10 receptor was expressed on a significantly higher proportion of T lymphocytes in the liver compared with blood. CD8 T lymphocytes, which predominate in the liver lobule, were almost uniformly CXCR3‐positive. The expression of IP‐10 mRNA correlated with lobular necroinflammatory activity but not with inflammation or fibrosis in the portal tracts. These findings suggest that IP‐10 may be induced by HCV within hepatocytes and may be important in the pathogenesis of chronic HCV infection, as recruitment of inflammatory cells into the lobule is an important predictor of disease progression.

MOF and histone H4 acetylation at lysine 16 are critical for DNA damage response and double- strand break repair

ABSTRACT The human MOF gene encodes a protein that specifically acetylates histone H4 at lysine 16 (H4K16ac). Here we show that reduced levels of H4K16ac correlate with a defective DNA damage response (DDR) and double-strand break (DSB) repair to ionizing radiation (IR). The defect, however, is not due to altered expression of proteins involved in DDR. Abrogation of IR-induced DDR by MOF depletion is inhibited by blocking H4K16ac deacetylation. MOF was found to be associated with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a protein involved in nonhomologous end-joining (NHEJ) repair. ATM-dependent IR-induced phosphorylation of DNA-PKcs was also abrogated in MOF-depleted cells. Our data indicate that MOF depletion greatly decreased DNA double-strand break repair by both NHEJ and homologous recombination (HR). In addition, MOF activity was associated with general chromatin upon DNA damage and colocalized with the synaptonemal complex in male meiocytes. We propose that MOF, through H4K16ac (histone code), has a critical role at multiple stages in the cellular DNA damage response and DSB repair.

Virtual microscopy for learning and assessment in pathology.

Virtual slides are high‐magnification digital images of tissue sections, stored in a multi‐resolution file format. Using appropriate software, these slides can be viewed in a web browser in a manner that closely simulates examination of glass slides with a real microscope. We describe the successful implementation of teaching microscopic pathology with virtual slides and, for the first time, their use in summative assessment. Both students and teaching staff readily adapted to the use of virtual microscopy. Questionnaire feedback from students strongly indicated that virtual slides solved a number of problems in their learning, while providing good to excellent image quality. A deliberate policy of allocating two students per workstation promoted collaboration and helped to maintain interest in microscopic pathology. The use of a secure browser facilitated assessment using virtual slides, with no technical or security issues arising despite high peak demand. The new Medicine programme at the University of New South Wales will exclusively utilize virtual microscopy for the study of both histology and histopathology. We believe that the use of high‐quality learning resources such as virtual slides can ensure that microscopic examination of tissues remains both meaningful and interesting. Copyright

Role of interleukin‐13 in eosinophil accumulation and airway remodelling in a mouse model of chronic asthma

Background Interleukin‐13 is believed to be important in asthmatic inflammation and airway hyper‐reactivity.

Phosphorylation of Exo1 modulates homologous recombination repair of DNA double-strand breaks

DNA double-strand break (DSB) repair via the homologous recombination pathway is a multi-stage process, which results in repair of the DSB without loss of genetic information or fidelity. One essential step in this process is the generation of extended single-stranded DNA (ssDNA) regions at the break site. This ssDNA serves to induce cell cycle checkpoints and is required for Rad51 mediated strand invasion of the sister chromatid. Here, we show that human Exonuclease 1 (Exo1) is required for the normal repair of DSBs by HR. Cells depleted of Exo1 show chromosomal instability and hypersensitivity to ionising radiation (IR) exposure. We find that Exo1 accumulates rapidly at DSBs and is required for the recruitment of RPA and Rad51 to sites of DSBs, suggesting a role for Exo1 in ssDNA generation. Interestingly, the phosphorylation of Exo1 by ATM appears to regulate the activity of Exo1 following resection, allowing optimal Rad51 loading and the completion of HR repair. These data establish a role for Exo1 in resection of DSBs in human cells, highlighting the critical requirement of Exo1 for DSB repair via HR and thus the maintenance of genomic stability.

The adipocyte fatty acid–binding protein aP2 is required in allergic airway inflammation

The adipocyte fatty acid-binding protein aP2 regulates systemic glucose and lipid metabolism. We report that aP2, in addition to being abundantly expressed by adipocytes, is also expressed by human airway epithelial cells and shows a striking upregulation following stimulation of epithelial cells with the Th2 cytokines IL-4 and IL-13. Regulation of aP2 mRNA expression by Th2 cytokines was highly dependent on STAT6, a transcription factor with a major regulatory role in allergic inflammation. We examined aP2-deficient mice in a model of allergic airway inflammation and found that infiltration of leukocytes, especially eosinophils, into the airways was highly dependent on aP2 function. T cell priming was unaffected by aP2 deficiency, suggesting that aP2 was acting locally within the lung, and analysis of bone marrow chimeras implicated non-hematopoietic cells, most likely bronchial epithelial cells, as the site of action of aP2 in allergic airway inflammation. Thus, aP2 regulates allergic airway inflammation and may provide a link between fatty acid metabolism and asthma.