HIV's evasion of the cellular immune response

Despite a strong cytotoxic T-lymphocyte (CTL) response directed against viral antigens, untreated individuals infected with the human immunodeficiency virus (HIV-1) develop AIDS, We have found that primary T cells infected with HIV-1 downregulate surface MHC class I antigens and are resistant to lysis by HLA-A2-restricted CTL clones. In contrast, cells infected with an HIV-1 in which the nef gene is disrupted are sensitive to CTLs in an MHC and peptide-specific manner. In primary T cells HLA-A2 antigens are downmodulated more dramatically than total MHC class I antigens, suggesting that nef selectively downmodulates certain MHC class I antigens. In support of this, studies on ceils expressing individual MHC class I alietes have revealed that nef does not downmodulate HLA-C and HLA-E antigens, This selective downmodulation allows Infected cells to maintain resistance to certain natural killer cells that lyse infected cells expressing low levels of MHC class I antigens. Downmodulation of MHC class I HLA-A2 antigens occurs not only in primary T cells, but also in B and astrocytoma cell lines. No effect of other HIV-1 accessory proteins such as vpu and vpr was observed. Thus Nef is a protein that may promote escape of HIV-1 from immune surveillance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75570/1/j.1600-065X.1999.tb01283.x.pd

Systematic review of factors influencing patient and practitioner delay in diagnosis of upper gastrointestinal cancer

As knowledge on the causation of cancers advances and new treatments are developed, early recognition and accurate diagnosis becomes increasingly important. This review focused on identifying factors influencing patient and primary care practitioner delay for upper gastrointestinal cancer. A systematic methodology was applied, including extensive searches of the literature published from 1970 to 2003, systematic data extraction, quality assessment and narrative data synthesis. Included studies were those evaluating factors associated with the time interval between a patient first noticing a cancer symptom and presenting to primary care, between a patient first presenting to primary care and being referred to secondary care, or describing an intervention designed to reduce those intervals. Twenty-five studies were included in the review. Studies reporting delay intervals demonstrated that the patient phase of delay was greater than the practitioner phase, whilst patient-related research suggests that recognition of symptom seriousness is more important than recognition of the presence of the symptom. The main factors related to practitioner delay were misdiagnosis, application and interpretation of tests, and the confounding effect of existing disease. Greater understanding of patient factors is required, along with evaluation of interventions to ensure appropriate diagnosis, examination and investigation

Radiosensitizing potential of the selective cyclooygenase-2 (COX-2) inhibitor meloxicam on human glioma cells

The COX-2 protein is frequently overexpressed in human malignant gliomas. This expression has been associated with their aggressive growth characteristics and poor prognosis for patients. Targeting the COX-2 pathway might improve glioma therapy. In this study, the effects of the selective COX-2 inhibitor meloxicam alone and in combination with irradiation were investigated on human glioma cells in vitro. A panel of three glioma cell lines (D384, U87 and U251) was used in the experiments from which U87 cells expressed constitutive COX-2. The response to meloxicam and irradiation (dose-range of 0–6 Gy) was determined by the clonogenic assay, cell proliferation was evaluated by growth analysis and cell cycle distribution by FACS. 24–72 h exposure to 250–750 μM meloxicam resulted in a time and dose dependent growth inhibition with an almost complete inhibition after 24 h for all cell lines. Exposure to 750 μM meloxicam for 24 h increased the fraction of cells in the radiosensitive G2/M cell cycle phase in D384 (18–27%) and U251 (17–41%) cells. 750 μM meloxicam resulted in radiosensitization of D384 (DMF:2.19) and U87 (DMF:1.25) cells, but not U251 cells (DMF:1.08). The selective COX-2 inhibitor meloxicam exerted COX-2 independent growth inhibition and radiosensitization of human glioma cells

Type distribution, viral load and integration status of high-risk human papillomaviruses in pre-stages of cervical cancer (CIN)

A series of 176 archival cervical intraepithelial neoplasia (CIN) was analysed for the presence, viral load and integration status of ‘high-risk' types of human papillomavirus (HR-HPV). The samples were assayed using newly developed methods based on real-time PCR. Two methods for the extraction of DNA from the paraffin-embedded biopsies were compared: a protocol based on the MagNA pure system (Roche) and a Qiagen spin column kit (Qiagen). It was possible to amplify 94% (166) of the samples. Of these, 36, 63 and 80% of the CIN I, II and III cases contained HR-HPV. HPV 16 was the most prevalent, and was found in 20, 28 and 46% of the CIN I, II and III cases, respectively. The second most frequent HR-HPV was type 33 group, and in CIN II it was as prevalent as HPV 16. The median number of copies of HR-HPV per cell was not significantly different in the CIN I, II and III cases, but there was a wide range of viral load values over several magnitudes, regardless of the grade of CIN. All samples were found to contain integrated forms of HPV 16, frequently mixed with an episomal form

A genomic analysis of the archaeal system Ignicoccus hospitalis-Nanoarchaeum equitans

Sequencing of the complete genome of Ignicoccus hospitalis gives insight into its association with another species of Archaea, Nanoarchaeum equitans

The human phylome

The human phylome, which includes evolutionary relationships of all human proteins and their homologs among thirty-nine fully sequenced eukaryotes, is reconstructed

Technical and Comparative Aspects of Brain Glycogen Metabolism.

It has been known for over 50 years that brain has significant glycogen stores, but the physiological function of this energy reserve remains uncertain. This uncertainty stems in part from several technical challenges inherent in the study of brain glycogen metabolism, and may also stem from some conceptual limitations. Factors presenting technical challenges include low glycogen content in brain, non-homogenous labeling of glycogen by radiotracers, rapid glycogenolysis during postmortem tissue handling, and effects of the stress response on brain glycogen turnover. Here, we briefly review aspects of glycogen structure and metabolism that bear on these technical challenges, and discuss ways these can be overcome. We also highlight physiological aspects of glycogen metabolism that limit the conditions under which glycogen metabolism can be useful or advantageous over glucose metabolism. Comparisons with glycogen metabolism in skeletal muscle provide an additional perspective on potential functions of glycogen in brain

From old organisms to new molecules: integrative biology and therapeutic targets in accelerated human ageing

Understanding the basic biology of human ageing is a key milestone in attempting to ameliorate the deleterious consequences of old age. This is an urgent research priority given the global demographic shift towards an ageing population. Although some molecular pathways that have been proposed to contribute to ageing have been discovered using classical biochemistry and genetics, the complex, polygenic and stochastic nature of ageing is such that the process as a whole is not immediately amenable to biochemical analysis. Thus, attempts have been made to elucidate the causes of monogenic progeroid disorders that recapitulate some, if not all, features of normal ageing in the hope that this may contribute to our understanding of normal human ageing. Two canonical progeroid disorders are Werner’s syndrome and Hutchinson-Gilford progeroid syndrome (also known as progeria). Because such disorders are essentially phenocopies of ageing, rather than ageing itself, advances made in understanding their pathogenesis must always be contextualised within theories proposed to help explain how the normal process operates. One such possible ageing mechanism is described by the cell senescence hypothesis of ageing. Here, we discuss this hypothesis and demonstrate that it provides a plausible explanation for many of the ageing phenotypes seen in Werner’s syndrome and Hutchinson-Gilford progeriod syndrome. The recent exciting advances made in potential therapies for these two syndromes are also reviewed