Engineering mammalian cells for solid-state sensor applications

A fundamental advance in the development and application of cell- and tissue-based biosensors would be the ability to achieve air-dry stabilization of mammalian (especially human) cells with subsequent recovery following rehydration. The would allow for the preparation of sensors with extended shelf lives, only requiring the addition of water for activation. By understanding and subsequently employing the tactics used by desiccation-tolerant extremophiles, it may be possible to design stabilized mammalian cell-based biosensors. The approaches required to realize this goal are discussed and illustrated with several examples.

Percentage of CD3+CD4-CD8-gammadeltaTCR- T cells is increased HIV disease

HIV patients given highly active antiretroviral therapy (HAART) experience a rapid rise in alphabetaT cell numbers, but changes in gammadeltaT cell populations have not been described. Here we investigate the effects of immune reconstitution and immune restoration diseases (IRDs) on expression of a pan-gammadeltaT cell receptor (TCR) marker on double-negative (CD3(+)CD4(-)CD8(-)) T cells and T cells expressing CD4 or CD8. IRDs are inflammatory disorders associated with preexisting infections in patients who have achieved immune reconstitution after HAART. Proportions of CD3(+)CD4(-)CD8(-) T cells and total gammadeltaT cells were not affected by CD4(+) T cell counts, HAART, or a history of IRD, but levels of CD4(-)CD8(-)gammadeltaTCR(-) T cells were higher in patients with <15% CD4(+) T cells.

The central MHC gene, BAT1, may encode a protein that down-regulates cytokine production

BACKGROUND

BAT1 belongs to the DEAD-box family of RNA-binding proteins and is encoded in the central MHC. To determine whether it affects immune responses and hence diseases influenced by MHC haplotypes, U937, THP1 and Jurkat cells were stably transfected with anti-sense DNA corresponding to exons 2-5 of BAT1 using a retroviral vector.

RESULTS

Anti-sense transfectants carried anti-sense DNA and expressed anti-sense mRNA. After mitogenic stimulation, they produced higher levels of TNFalpha, IL-1 and IL-6 than equivalent cells carrying the vector alone, suggesting that BAT1 may down-regulate acute phase cytokine production. Polyclonal antibodies raised against a peptide in exon 8 of BAT1 recognized approximately 50 kDa and approximately 38 kDa proteins in all cell lines tested, including the anti-sense transfectants. Expression was localized to the nucleolus in dividing fibroblasts. However the immunochemistry may be confounded by a recently described gene, DDXL, on chromosome 19, which shares a 89% amino acid identity with BAT1. RT-PCR analyses established that BAT1 and DDXL mRNA are expressed in resting U937, THP1 and Jurkat cells. BAT1 and DDXL are divergent in the exons selected for the anti-sense study.

CONCLUSIONS

BAT1 is a negative regulator of inflammation. Future studies should address how its functions relate to those of DDXL.

MHC haplotypes affect the expression of opportunistic infections in HIV patients

This study explores whether MHC genes affect manifestations of opportunistic infections in HIV patients not treated with highly active antiretroviral therapy (HAART) and immunopathologic responses to pre-existing infections in patients who achieved immune reconstitution following HAART (i.e., "immune restoration diseases" or IRD). HLA-B27 and B17 were relatively rare in all HIV patients, but no HLA-B alleles significantly affected cytomegalovirus (CMV) or Mycobacterium avium complex (MAC) disease in patients who had not received HAART. However coexpression of alleles previously defined as the 44.1 ancestral haplotype (HLA-A2, -B44, and -DR4) was more common in the MAC and CMV patients. After HAART, HLA-B44 and (HLA-A2, -B44, -DR4) were found in 66% and 33%, respectively, of patients who experienced an IRD manifested as CMV retinitis and/or encephalomyelitis. This was confirmed by examination of microsatellite alleles, where the C1_2_5 locus in the class I region was most concordant with the 44.1 haplotype in the patients. HLA-B44 was not associated with IRD initiated by Mycobacterium sp, cutaneous VZV or HSV, or HCV infections, suggesting distinct pathologic mechanisms are responsible. CMV retinitis/encephalomyelitis IRD patients had marginally lower pretreatment CD4 T-cell counts, but indices of immune reconstitution were similar in all groups and independent of HLA-B44.

Functional CT imaging of the acute hyperemic response to radiation therapy of the prostate gland: early experience

PURPOSE

Functional CT can measure perfusion and permeability. We hypothesized that acute changes could be measured in these indexes following radiation therapy (RT) to the prostate gland.

METHOD

Twenty-two patients with prostatic cancer were studied before and 1-2 and 6-12 weeks after RT. A single section through the prostate was repeatedly scanned after contrast medium bolus injection. Contrast agent clearance per unit volume (alpha/V) and fractional vascular volume (fvv) were calculated using Patlak graphical analysis. Perfusion was calculated as the ratio between maximal rate of tissue enhancement and peak arterial enhancement.

RESULTS

Significant increases in all indexes occurred after RT. Mean perfusion rose from 0.122 to 0.263 ml/min/ml at 1-2 weeks, mean alpha/V increased from 0.0012 to 0.0016 ml/min/ml at 1-2 weeks, and mean fvv increased from 13.7 to 21% at 1-2 weeks. All three indexes remained elevated at 6-12 weeks after the start of RT.

CONCLUSION

Functional CT demonstrated an acute hyperemic response following RT to the prostate gland.

Cholangiocarcinoma and the role of radiation and chemotherapy

Cholangiocarcinoma is a rare tumor. Many cases are localized while metastatic disease within the liver and abdomen do occur. There is as yet no standard therapy for advanced bile duct tumors. Radiotherapy and chemotherapy are not curative modalities in this condition but are being assessed adjuvantly following surgery, and as palliative treatment in an attempt to either extend progression-free and overall survival or to palliate symptoms. Advances may be made by: (i) The combined use of radiation and chemotherapy, (ii) High dose conformal radiotherapy, (iii) Novel chemotherapeutic agents. Patients should be given the opportunity to participate in clinical trials.

Assessment of immune function by lymphoproliferation underestimates lymphocyte functional capacity in HIV patients treated with highly active antiretroviral therapy

The objective of this study was to evaluate T cell responses in HIV-infected patients after highly active antiretroviral therapy (HAART), using four assays of immune function, and to determine which best reflects the presence of CD4(+) T cells able to respond to CMV antigen. Peripheral blood mononuclear cells from 41 HIVinfected patients and 31 healthy HIV-seronegative controls were cultured with mitogen (PMA/Ca(2+) ionophore) or antigen (CMV). Production of interferon gamma (IFN-gamma) determined by ELISpot assay was compared with lymphoproliferation, IFN-gamma production assessed by ELISA, and CD69 expression and intracellular IFN-gamma assessed by flow cytometry. Cells from patients whose CD4(+) T cells counts increased 4-fold or to >200 cells/microl after HAART responded as well as control cells when assessed by IFN-gamma production and CD69 expression after mitogenic stimulation, but lymphoproliferation responses were depressed by about 52%. Patients who did not meet these criteria for immune reconstitution had lymphoproliferative responses up to 30-fold lower than control subjects, while intracellular IFN-gamma and CD69 expression and ELISpot counts were less than 3-fold lower. Responses to CMV antigen could not be detected by flow cytometry, but were readily detected by ELISpot in CMV-seropositive patients whose CD4(+) T cell counts had increased after HAART. This included patients with low responses assessed by lymphoproliferation. Moreover, ELISpot responses measured with fresh and frozen cells were comparable, while lymphoproliferation assays required fresh cells. In conclusion, the ELISpot assay is a sensitive and efficient technique for detecting CMV-specific IFN-gamma responses in samples that display poor responses when assessed by lymphoproliferation assays.

The H2(b) haplotype modifies the production of pro-inflammatory cytokines: implications for immunopathology

Congenic strains of mice which differ only in their H2 haplotype were used to examine the effects of MHC genes on production of pro-inflammatory cytokines, as we have shown previously that H2(b) mice produce low levels of T cell cytokines compared to congenic H2(k) and H2(d) mice. RNase protection assays were used to assess cytokine mRNA and cytokine protein was assessed by ELISA or bioassay. Concanavalin A or phorbol myristate acetate/calcium ionophore/anti-CD3 stimulation of spleen cells from H2(b) congenic mice induced less IL-1, IL-2, IFN-gamma and MIF mRNA and/or protein than the equivalent cells from H2(d) mice. However, following stimulation with lipopolysaccharide or phorbol myristate acetate/calcium ionophore, peritoneal cells from H2(b) mice synthesised significantly more IL-1 beta, TNF-alpha, TNFR and IFN-gamma protein and IFN-gamma mRNA than cells from congenic H2(k) or H2(d) mice. These differences were evident in congenic C57BL/10 and/or BALB/c strains. We suggest that the low IL-1 production in H2(b) spleen cultures is secondary to lower T cell activation. Evidence that the H2(b) haplotype carries an immunoregulatory allele which affects cytokine production warrants further investigation.

What does positron emission tomography offer oncology?

The origins of positron emission tomography (PET) date back 70 years. Since the 1970s, however, its use has increased exponentially in the fields of neurology, cardiology and oncology. [18F]-Fluorodeoxyglucose (FDG) whole-body scanning is by far the most widely utilised and recognised application of PET in oncology. However, PET is a very versatile and powerful imaging modality capable of helping bridge the gap between the laboratory and the clinic. This article reviews the history and current applications of PET in oncology and then explores some of the newer applications and potential future uses of this versatile technology particularly in the area of cancer research.

Topical treatment: which dressing to choose

Wounds have existed since the beginning of time. The interest in this subject has been stimulated in the main by conflict and war that have necessitated the development of new ways of managing wounds. In the 1960s the development of new materials that maintained a moist environment in the wound area encouraged a number of commercial companies to produce a wide variety of new materials with physical and chemical properties that might provide a moist environment. However the data to support the use of such materials are limited if one requires evidence that they have produced more rapid healing in chronic wounds kept moist as to those kept dry. Is this due to a problem with the outcome measure rather than a problem with the materials themselves? Rather than seeing this as justification for not using such materials, it should instead lead clinicians to question the validity of endpoint studies in wound healing experiments. There is a lack of evidence regarding the ability of such materials to improve the speed of healing in chronic wounds. Nevertheless considerable clinical experience, obtained from treating many patients, has indicated that not only are such new treatments cost effective, but that they are also proving to be extremely beneficial and acceptable to patients, on account of their ability to reduce pain, odour or leakage from a wound.

Raltitrexed ('Tomudex') and radiotherapy can be combined as postoperative treatment for rectal cancer

BACKGROUND

The optimal adjuvant therapy for operable rectal cancer is likely to be a combination of radiotherapy and chemotherapy. Raltitrexed ('Tomudex') is a specific thymidylate synthase inhibitor with a convenient administration schedule, acceptable and manageable toxicity, radiosensitising properties, and proven efficacy in the treatment of advanced colorectal cancer. It may, therefore, offer advantages compared with standard 5-FU chemotherapy regimens used in colorectal cancer. The aim of this phase I, dose-escalation study was to determine the recommended dose of raltitrexed for use with postoperative pelvic radiotherapy in patients with rectal cancer.

PATIENTS AND METHODS

Patients with resected Dukes' stage B or C rectal cancer were treated with a combination of raltitrexed and radiotherapy (50.4 Gy at 1.8 Gy per fraction over five to six weeks). At least three patients were treated at each of three escalating raltitrexed dose levels (2.0, 2.6 and 3.0 mg/m2) once every three weeks. Toxicity was assessed by the recording of WHO adverse events and biochemistry and haematology determinations.

RESULTS

A total of 22 patients entered the study, 17 of whom had Dukes' stage C disease. All three patients entered at a dose level of 3.0 mg/m2 experienced dose-limiting toxicity (DLT) (2 patients had grade 3 leucopenia and 1 patient had grade 2 leucopenia and grade 3 diarrhoea); however, only 2 of 1 patients entered at a dose level of 2.6 mg/m2 experienced DLT (1 patient had grade 4 neutropenia and 1 patient died probably due to aspiration pneumonia unrelated to treatment). The most common haematological toxic events were leucopenia (8 patients) and anaemia (6 patients). Only four haematological or biochemical toxic events were of grade 3 or 4. Other common toxicities were diarrhoea and nausea, which occurred in 15 and 9 patients, respectively.

CONCLUSIONS

This study demonstrates that raltitrexed can be combined with postoperative radiotherapy for treatment of patients with Dukes' stage B or C rectal cancer. The recommended dose of raltitrexed in this setting is 2.6 mg/m2, which is close to the full monotherapy dose.

Management problems in oncology

Man has evolved sophisticated defence mechanisms over millions of years to combat insertion of foreign DNA into his cells. However, gene therapy carries huge potential for the treatment of cancer. The challenge is therefore to translate our scientific knowledge into a clinical reality.

Suicide risk assessment: a review of procedures

Suicide risk assessment is an important part of the nurse's role. Suicide screening is an integral component of the assessment process. It should be systematic and follow a prescribed procedure: client self assessment, holistic assessment and diagnosis. The Gatehouse Assessment Centre in Warrington, UK, a predominantly nurse led centre, was opened in 1995, operates 365 days, 9 am till 9 pm, with open referral. The Centre offers psychiatric assessment, short-term treatments or referral on without hospital beds. In line with local and national policy, the Gatehouse team have introduced suicide rating scales as part of their risk screening process. However, the team have encountered problems using their designated scale, adapted from the Suicide Intent Scale, Pierce (1981). The major problem with the use of a rating scale was that, as a one off scoring system, it did not reflect the dynamic nature of suicidal behaviour. Furthermore, it is questionable whether a tool developed for research purposes would be used in the same way in practice. From a clinical perspective, the tool was capable of measurement only and failed to assist a dynamic holistic assessment required by practitioners. It was, therefore, necessary to review and evaluate the risk assessment procedure. In order to address these problems an assessment procedure which is more than a once only 'score' was piloted. The procedure incorporated risk screeners. Rather than rely on a value weighting system, or a positive or negative conclusion, it took account of the continuum of risk which is contingent on a broad range of factors. It took account of the accumulation of risk factors which may be increased or reduced in the light of unfolding events. Details of the new procedure, how it has been incorporated into the assessment process and subsequent management plan, and methodological considerations for further study are detailed.

The mouse as a model for the effects of MHC genes on human disease

As mice are often used to model human major histocompatibility complex (MHC)-associated diseases, it is important to understand how their MHC regions differ at the DNA level. The sequencing of the mouse MHC (H2 region) has enabled a detailed map of this region to be assembled for comparison with the human MHC. Here, Richard Allcock and colleagues outline the similarities between the human and mouse MHC regions and discuss notable differences that might affect disease models.

Lymphocytes from H2 mice produce lower levels of several cytokines than congenic H2 or H2 mice

Inbred mice of congenic strains that differ only in their H2 haplotype were used to examine the effects of MHC genes on production of cytokines. Spleen and lymph node cells were stimulated with mitogens in vitro, and cytokine protein was assessed by ELISA and/or bioassays. Cells from H2b mice synthesized less IL-3, IL-4, IL-5, TNF and IL-10 (less clearly) than the equivalent cells from H2k or H2d mice. Production of IL-6 by H2b spleen and lymph node cells was lower than that by cells from H2d mice. In addition, lower lymphoproliferative responses were observed in lymph node cultures from H2b mice. These effects were evident in congenic B10 and BALB strains. B10 H2b mice stimulated in vivo with anti-CD3 had lower levels of IFN-gamma and IL-5 protein in their serum compared with equivalent H2k and H2d mice. Because class I- or II-mediated antigen presentation was not required in our model, an immunoregulatory gene in the central MHC is implicated. Preliminary studies of MHC recombinant mice suggested that the gene or genes responsible lie telomeric of IEbeta. Evidence that the H2b haplotype carries an immunoregulatory allele with a small but consistent effect on cytokine production warrants further investigation.

A novel locus affecting serum levels of IgG2a maps to the murine H2 region

The effects of genes in the murine H2 region on basal immunoglobulin levels were investigated and ratios of IgG1/IgG2a were calculated, as low ratios indicate a Th1 cytokine mileu. H2b mice with B10 or BALB genetic backgrounds had higher levels of IgG2a than H2k and H2d congenic strains, and hence had low IgG1/IgG2a ratios. B10 (H2b) mice generally had high levels of IgG2b, IgG3, IgA and IgM, but this outcome was more variable. The high IgG2a phenotype was denoted Igis1 (Immunoglobulin isotype-1) and mapped telomeric of IEbeta using B10.A(4R) mice (high IgG2a) and B10.A(3R) and B10.A(5R) mice (low IgG2a). Further mapping in B10.A(2R), B10.A(1R) and B10.A(18R) mice placed Igis1 in the 27kb region between G7c and G7e.

Structure and polymorphism of two stress-activated protein kinase genes centromeric of the MHC: SAPK2a and SAPK4

As MHC genes are potent determinants of susceptibility to immunopathological diseases, the mapping of SAPK2a (CSBP) and SAPK4 to chromosome 6p 21.2-21.3 suggested that these genes may mediate the effects of the MHC on disease. Here we describe the genomic structure and localisation of both genes approximately 2.3Mb centromeric of HLA-DP. Examination of the complete coding region and selected intronic regions of SAPK2a and SAPK4 from 22 human EBV-transformed B-cell lines of different MHC haplotypes and racial background revealed complete sequence conservation. There were no notable differences in levels of expression of SAPK2a and SAPK4 mRNA in cell lines of different MHC haplotypes or racial origin. Examination of the SAPK2a and SAPK4 sequences from two chimpanzees revealed 3 nucleotide differences between human and chimpanzee in each gene resulting in only one amino acid change in SAPK4, and 6 nucleotide substitutions plus 2 deletions in 600bp of intronic sequence from SAPK4. This highlights the selective pressure placed on these genes to maintain their protein sequence, but does not favour a role in genetic regulation of disease or provide evidence of linkage disequilibrium with the MHC.

A general method to correct PET data for tissue metabolites using a dual-scan approach

This article presents and analyses a general method of correcting for the presence of radiolabeled metabolites from a parent radiotracer in tissue during PET scanning. The method is based on a dual-scan approach, i.e., parent scan together with an independent supplementary scan in which the radiolabeled metabolite of interest itself is administered. The method corrects for the presence of systemically derived radiolabeled metabolite delivered to the tissues of interest through the blood.

METHODS

Data from the supplementary scan are analyzed to obtain the tissue impulse response function for the metabolite. The time course of the radiolabeled metabolite in plasma in the parent scan is convolved with its tissue impulse response function to derive a correction term. This is not a simple subtraction technique but 1 that takes account of the different time-activity curves of the radiolabeled metabolite in the 2 scans.

RESULTS

The method, its implications, and its limitations are discussed with respect to [11C]thymidine and its principal metabolite 11CO2.

CONCLUSION

The general method, based on a dual-scan approach, can be used to correct for radiolabeled metabolites in tissues of interest during PET scanning. The correction accounts for radiolabeled metabolites that are derived systemically and delivered to the tissues of interest through the blood.