Qualitative study investigating the underlying motivations of healthy participants in phase I clinical trials

OBJECTIVES

If patients are to reap the benefits of continued drug development, an understanding of why healthy participants take part in phase I clinical trials is imperative. The current study aimed to explore the nature of these underlying motivations which may, in turn, improve the overall participant experience and assist in the development of more effective recruitment and retention strategies.

DESIGN

This study used a qualitative design based on the theory of planned behaviour. Specifically, it explored healthy participants' underlying behavioural, control and normative beliefs which influence their participation in phase I clinical trials.

SETTING

This study took place at a company that specialises in conducting phase I and phase II clinical trials in the Australian state of Queensland.

PARTICIPANTS

Participants (n=31) were either currently undergoing a phase I clinical trial or had previously taken part in a phase I clinical trial.

RESULTS

Results showed that the motivations were varied and not solely centred on financial gains. Reported advantages of participation included altruism, while inconvenience was most often reported as a disadvantage. Friends were reported as those most likely to approve, while one's mother was reported as most likely to disapprove. Having a suitable time frame/flexible scheduling and feeling comfortable taking part in the trial were both the most commonly reported facilitators, while inflexible scheduling/time commitment was the most commonly reported barrier.

CONCLUSIONS

Practical implications included the need for organisations involved in clinical trials to be mindful of inflexible scheduling and exploring the possibility of making educational materials available to family members who may be concerned about the risks associated with participation. Overall, it is anticipated that the results of this study will improve the understanding of factors that influence phase I clinical trial participation which may, ultimately, help develop new therapeutics to improve patient health.

Fasting increases serum bilirubin levels in clinically normal, healthy males but not females: a retrospective study from phase I clinical trial participants

AIM

To examine if fasting affects serum bilirubin levels in clinically healthy males and females.

METHODS

We used retrospective data from phase I clinical trials where blood was collected in either a fed or fasting state at screening and predosing time points and analysed for total bilirubin levels as per standard clinical procedures. Participants were clinically healthy males (n=105) or females (n=30) aged 18-48 inclusive who participated in a phase I clinical trial in 2012 or 2013.

RESULTS

We found a statistically significant increase in total serum bilirubin levels in fasting males as compared with non-fasting males. The fasting time correlated positively with increased bilirubin levels. The age of the healthy males did not correlate with their fasting bilirubin level. We found no correlation between fasting and bilirubin levels in clinically normal females.

CONCLUSIONS

The recruitment and screening of volunteers for a clinical trial is a time-consuming and expensive process. This study clearly demonstrates that testing for serum bilirubin should be conducted on non-fasting male subjects. If fasting is required, then participants should not be excluded from a trial based on an elevated serum bilirubin that is deemed non-clinically significant.

Phase 1 safety and immunogenicity trial of the Plasmodium falciparum blood-stage malaria vaccine AMA1-C1/ISA 720 in Australian adults

A Phase 1 trial was conducted in malaria-naïve adults to evaluate the recombinant protein vaccine apical membrane antigen 1-Combination 1 (AMA1-C1) formulated in Montanide ISA 720 (SEPPIC, France), a water-in-oil adjuvant. Vaccinations were halted early due to a formulation issue unrelated to stability or potency. Twenty-four subjects (12 in each group) were enrolled and received 5 or 20 microg protein at 0 and 3 months and four subjects were enrolled and received one vaccination of 80 microg protein. After first vaccination, nearly all subjects experienced mild to moderate local reactions and six experienced delayed local reactions occurring at Day 9 or later. After the second vaccination, three subjects experienced transient grade 3 (severe) local reactions; the remainder experienced grade 1 or 2 local reactions. All related systemic reactogenicity was grade 1 or 2, except one instance of grade 3 malaise. Anti-AMA1-C1 antibody responses were dose dependent and seen following each vaccination, with mean antibody levels 2-3 fold higher in the 20 microg group compared to the 5 microg group at most time points. In vitro growth-inhibitory activity was a function of the anti-AMA1 antibody titer. AMA1-C1 formulated in ISA 720 is immunogenic in malaria-naïve Australian adults. It is reasonably tolerated, though some transient, severe, and late local reactions are seen.

Menstrual cycle-dependent changes of Toll-like receptors in endometrium

BACKGROUND

Rapid innate immune defences against infection usually involve the recognition of invading pathogens by specific pattern recognition receptors recently attributed to the family of Toll-like receptors (TLRs). Reports from our laboratory and others have demonstrated the existence of TLRs 1-6 in the female reproductive tract. However, little has been done to identify TLRs 7-10 in the female reproductive tract, particularly in the uterus. Also little information exists regarding variation in TLRs in the female reproductive tract during the menstrual cycle.

METHOD

The distribution of TLR7-10 protein was detected by immunostaining in timed endometrial biopsies from normal women. RT-PCR was used to show the existence of TLR1-10 genes in endometrial tissue and real-time PCR analysis to investigate the relative expression of these genes during the menstrual cycle in normal human endometrium.

RESULTS

TLR7-10 proteins were detected in endometrial epithelium and stroma. TLR1-10 genes were expressed in human endometrial tissue, and the mean relative expression of TLR2-6, 9 and 10 genes was significantly higher during the secretory phase compared with other phases of the menstrual cycle.

CONCLUSIONS

TLR7-10 localization is not limited to endometrial epithelium but is also present in the stroma of the endometrial tissue. Endometrial TLR2-6, 9 and 10 genes are cyclically expressed during the menstrual cycle.

Long-term effects of spinal cord injury on sexual function in men: implications for neuroplasticity

STUDY DESIGN

Secure, web-based survey.

OBJECTIVES

Elicit specific information about sexual function from men with spinal cord injuries (SCI).

SETTING

World-wide web.

METHODS

Individuals 18 years or older living with SCI obtained a pass-code to enter a secure website and then answered survey questions.

RESULTS

The presence of genital sensation was positively correlated with the ability to feel a build up of sexual tension in the body during sexual stimulation and in the feeling that mental arousal translates to the genitals as physical sensation. There was an inverse relationship between developing new areas of arousal above the level of lesion and not having sensation or movement below the lesion. A positive relationship existed between the occurrence of spasticity during sexual activity and erectile ability. Roughly 60% of the subjects had tried some type of erection enhancing method. Only 48% had successfully achieved ejaculation postinjury and the most commonly used methods were hand stimulation, sexual intercourse, and vibrostimulation. The most commonly cited reasons for trying to ejaculate were for pleasure and for sexual intimacy. Less than half reported having experienced orgasm postinjury and this was influenced by the length of time postinjury and sacral sparing.

CONCLUSION

SCI not only impairs male erectile function and ejaculatory ability, but also alters sexual arousal in a manner suggestive of neuroplasticity. More research needs to be pursued in a manner encompassing all aspects of sexual function.

The impact of spinal cord injury on sexual function: concerns of the general population

STUDY DESIGN

Secure, web-based survey.

OBJECTIVES

Obtain information from the spinal cord injured (SCI) population regarding sexual dysfunctions, with the aim of developing new basic science and clinical research and eventual therapies targeting these issues.

SETTING

Worldwide web.

METHODS

Individuals 18 years or older living with SCI. Participants obtained a pass-code to enter a secure website and answered survey questions. A total of 286 subjects completed the survey.

RESULTS

The majority of participants stated that their SCI altered their sexual sense of self and that improving their sexual function would improve their quality of life (QoL). The primary reason for pursuing sexual activity was for intimacy need, not fertility. Bladder and bowel concerns during sexual activity were not strong enough to deter the majority of the population from engaging in sexual activity. However, in the subset of individuals concerned about bladder and/or bowel incontinence during sexual activity, this was a highly significant issue. In addition, the occurrence of autonomic dysreflexia (AD) during typical bladder or bowel care was a significant variable predicting the occurrence and distress of AD during sexual activity.

CONCLUSION

Sexual function and its resultant impact on QoL is a major issue to an overwhelming majority of people living with SCI. This certainly constitutes the need for expanding research in multiple aspects to develop future therapeutic interventions for sexual health and SCI.

Spinal cord injury influences psychogenic as well as physical components of female sexual ability

STUDY DESIGN

Secure, web-based survey.

OBJECTIVES

Elicit specific information about sexual function from women with spinal cord injuries (SCI).

SETTING

World-wide web.

METHODS

Individuals 18 years or older living with SCI obtained a pass code to enter a secure website and then answered survey questions.

RESULTS

Bladder and/or bowel incontinence during sexual activity and/or sexual intercourse were significant concerns and prevented some women from seeking sexual activity. Autonomic dysreflexia (AD) during sexual activity was interpreted negatively by many and was found to interfere with sexual activity. Most subjects reported difficulty becoming psychologically aroused as well as physically aroused, which were both correlated with feeling that their SCI had altered their sexual sense of self. An inverse relationship existed between developing new areas of arousal above the level of lesion and not having sensation or movement below the lesion. The most commonly reported sexual stimulation leading to the best arousal involved stimulation of the head/neck and torso areas. The majority of subjects reported having experienced intercourse postinjury. Most participants reported difficulty with positioning during foreplay and intercourse, vaginal lubrication, and spasticity during intercourse. Almost half reported experiencing orgasm postinjury and this was positively associated with the presence of genital sensation.

CONCLUSION

SCI significantly impairs psychological and physical aspects of female sexual arousal. In addition, bladder and bowel incontinence as well as AD negatively impact sexual activity and intercourse.

Selecting the future doctors: the role of graduate medical programmes

Graduate-entry medical programmes have been introduced in many Australian states. This has coincided with the introduction of learner-centred, problem-orientated medical courses and has resulted in a need to develop new selection pathways. Medical schools have complemented their primary selection tool of academic performance with tests of personal attributes considered important in future doctors. Schools with graduate-entry programmes now employ a combination of the results of the applicant's undergraduate degree, a semistructured interview and a psychometric test (the Graduate Australian Medical School Admissions Test) to select students. Rationale for the change to graduate entry and the outcomes of this change will be discussed.

Determining virological, serological and immunological parameters of EBV infection in the development of PTLD

Post-transplant lymphoproliferative disease (PTLD) in Epstein-Barr virus (EBV) seronegative solid organ transplant recipients remains a significant problem, particularly in the first year post-transplant. Immune monitoring of a cohort of high-risk patients indicated that four EBV seronegative transplant recipients developed early-onset PTLD prior to evidence of an EBV humoral response. EBV status has been classically defined serologically, however these patients demonstrated multiple parameters of EBV infection, including the generation of EBV-specific CTL, outgrowth of spontaneous lymphoblastoid cell lines, and elevated EBV DNA levels, despite the absence of a classic EBV antibody response. As EBV serology is influenced by both immunosuppression and cytomegalovirus immunoglobulin treatment, both the EBV-specific CTL response and elevated EBV levels are more reliable indicators of EBV infection post-transplant.

Durable complete clinical responses in a phase I/II trial using an autologous melanoma cell/dendritic cell vaccine

Advanced metastatic melanoma is incurable by standard treatments, but occasionally responds to immunotherapy. Recent trials using dendritic cells (DC) as a cellular adjuvant have concentrated on defined peptides as the source of antigens, and rely on foreign proteins as a source of help to generate a cell-mediated immune response. This approach limits patient accrual, because currently defined, non-mutated epitopes are restricted by a small number of human leucocyte antigens. It also fails to take advantage of mutated epitopes peculiar to the patient's own tumour, and of CD4+ T lymphocytes as potential effectors of anti-tumour immunity. We therefore sought to determine whether a fully autologous DC vaccine is feasible, and of therapeutic benefit. Patients with American Joint Cancer Committee stage IV melanoma were treated with a fully autologous immunotherapy consisting of monocyte-derived DC, matured after culture with irradiated tumour cells. Of 19 patients enrolled into the trial, sufficient tumour was available to make treatments for 17. Of these, 12 received a complete priming phase of six cycles of either 0.9x10(6) or 5x10(6) DC/intradermal injection, at 2-weekly intervals. Where possible, treatment continued with the lower dose at 6-weekly intervals. The remaining five patients could not complete priming, due to progressive disease. Three of the 12 patients who completed priming have durable complete responses (average duration 35 months+), three had partial responses, and the remaining six had progressive disease (WHO criteria). Disease regression was not correlated with dose or with the development of delayed type hypersensitivity responses to intradermal challenge with irradiated, autologous tumour. However, plasma S-100B levels prior to the commencement of treatment correlated with objective clinical response ( P=0.05) and survival (log rank P<0.001). The treatment had minimal side-effects and was well tolerated by all patients. Mature, monocyte-derived DC preparations exposed to appropriate tumour antigen sources can be reliably produced for patients with advanced metastatic melanoma, and in a subset of those patients with lower volume disease their repeated administration results in durable complete responses.

Reconstitution of the latent T-lymphocyte response to Epstein-Barr virus is coincident with long-term recovery from posttransplant lymphoma after adoptive immunotherapy

BACKGROUND

Adoptive transfer of Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTLs) has been used to treat EBV-induced posttransplant lymphoproliferative disease (PTLD) in solid-organ recipients. This study defines, in detail, the temporal relationship between adoptive transfer and the clinical response, EBV DNA load, and CTL response to EBV latent and lytic antigens in a patient with a subcutaneous PTLD presentation treated with adoptive transfer of autologous CTL.

METHODS

A heart transplant patient developed multiple subcutaneous PTLD deposits and was treated with a total of six doses (20 x 106 CTL per dose) of cultured autologous polyclonal EBV-specific CTL by adoptive transfer.

RESULTS

Complete regression occurred after the sixth CTL dose, and the patient has remained disease-free from 47 weeks to the present (136 weeks). Real-time polymerase chain reaction analysis showed a reduction in viral load after therapy. Enzyme-linked immunospot analysis using defined EBV CTL epitopes showed that the CTL precursor frequency (pCTL) toward a lytic antigen epitope was elevated early in the course of disease but tended to decrease to lower levels after long-term regression of PTLD. The most dramatic result was seen in relation to three latent CTL epitopes studied. Long-term regression of PTLD was characterized by high pCTL toward the latent antigens.

CONCLUSIONS

Increased pCTL reactivity to latent EBV CTL epitopes is coincident with recovery from disease after adoptive transfer of autologous CTL. Furthermore, the results are compatible with the belief that activation of a sustained CTL response to EBV latent epitopes is protective and may be a characteristic of patients in long-term remission from PTLD.

Identification of biodegradation products formed by L-phenylalanine based segmented polyurethaneureas

The degradation of novel biodegradable segmented polyurethanes was investigated with a view to determining the cleavage points within the polymer backbones targeted by the enzyme chymotrypsin. While the materials were developed with specific enzyme cleavage sites designed into the polymer chains, the nature of their degradation had not yet been determined. In this work, two segmented polyurethaneureas containing L-phenylalanine residues in the chain extender and two control polymers were subjected to degradation in the presence of chymotrypsin. Samples were collected for analysis over a time period from 1 day to 8 weeks. The degradation products from these materials were isolated using solid phase extraction and reversed phase high pressure liquid chromatography, and identified using mass and tandem mass spectrometry. Three hard segment related degradation products were identified and provide important insight into the polyurethane backbone cleavage sites. Cleavage of urea, ester and urethane bonds were observed. The results confirmed that chymotrypsin was able to cleave ester bonds adjacent to phenylalanine residues contained within the novel chain extender.

Prime boost vaccination strategies: CD8 T cell numbers, protection, and Th1 bias

Vaccination strategies involving priming with DNA and boosting with a poxvirus vector have emerged as a preferred combination for the induction of protective CD8 T cell immunity. Using IFN-gamma ELISPOT and a series of DNA plasmid, peptide, and modified vaccinia Ankara (MVA) vaccine combinations, we demonstrate that the DNA/MVA combination was uniquely able to enhance IFN-gamma secretion by Ag-specific CD8 T cells. However, CD8 T cell populations induced by DNA/MVA vaccination failed to show an enhanced capability to mediate protection in an IFN-gamma-independent influenza challenge model. The DNA/MVA vaccine strategy was also not unique in its ability to induce high numbers of CD8 T cells, with optimal strategies simply requiring the use of vaccine modalities that individually induce high numbers of CD8 T cells. These experiments argue that rivals to DNA/poxvirus vaccination strategies for the induction of optimal protective CD8 T cell responses are likely to emerge.

Asymptomatic primary Epstein-Barr virus infection occurs in the absence of blood T-cell repertoire perturbations despite high levels of systemic viral load

Primary infection with the human herpesvirus, Epstein-Barr virus (EBV), may result in subclinical seroconversion or may appear as infectious mononucleosis (IM), a lymphoproliferative disease of variable severity. Why primary infection manifests differently between patients is unknown, and, given the difficulties in identifying donors undergoing silent seroconversion, little information has been reported. However, a longstanding assumption has been held that IM represents an exaggerated form of the virologic and immunologic events of asymptomatic infection. T-cell receptor (TCR) repertoires of a unique cohort of subclinically infected patients undergoing silent infection were studied, and the results highlight a fundamental difference between the 2 forms of infection. In contrast to the massive T-cell expansions mobilized during the acute symptomatic phase of IM, asymptomatic donors largely maintain homeostatic T-cell control and peripheral blood repertoire diversity. This disparity cannot simply be linked to severity or spread of the infection because high levels of EBV DNA were found in the blood from both types of acute infection. The results suggest that large expansions of T cells within the blood during IM may not always be associated with the control of primary EBV infection and that they may represent an overreaction that exacerbates disease.

Rural training and the state of rural health services: effect of rural background on the perception and attitude of first-year medical students at the university of melbourne

The aim of this project is to investigate the relationship between medical students' background and their perception of the state of rural health services; willingness to undertake internship training or work as a doctor in a rural hospital; expected benefits and disadvantages of training or working as a doctor in a rural hospital; and factors interfering with acceptance of a job as a doctor in rural areas. A questionnaire-based survey was distributed to 100 first-year medical students attending the Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne at the end of semester 1. The response rate was 97%, including 44 males and 53 females. A strong relationship was found between rural background and an intention to undertake internship training in a rural hospital (86% of students from a rural background expressed this desire vs 30% of students from an urban background). Furthermore, all students from a rural background expressed a desire to work as a doctor in a rural hospital after completing postgraduate training. Compared to urban students, students from a rural background showed a more positive attitude towards health services in rural areas including public hospitals ( P = 0.02), private general practice ( P = 0.004), ambulance service ( P = 0.0002) and baby health centres ( P = 0.005). Citizenship or gender was not significantly related to the perception of any of these services. The ranking of factors interfering with acceptance of a job as a doctor in rural areas were different for rural and urban students. Students from rural backgrounds reported spouse/partner needs (76% vs 49%, P = 0.038) and school availability for children (59% vs 30%, P = 0.023) as barriers more frequently than urban students, respectively). On the other hand, urban students rated the following factors higher: personal factors (76% vs 53%, respectively), education opportunities (56% vs 24%), social/cultural facilities (50% vs 41%) and the need for frequent travel (29% vs 12%). None of these interfering factors were significantly different. Urban students were more likely than rural students to report that their views were a result of adverse media reports. In conclusion, students from a rural background were more willing to be trained or to work as doctors in rural areas. This was associated with a greater adverse influence by the media upon students.

Assessment in problem-based learning: the role of the tutor

INTRODUCTION

Problem-based learning (PBL) in medicine emphasises the tutor's role in facilitating collaborative and integrated learning. While it is widely recognised that tutors come to know their students, they traditionally play little part in the formal assessment process. We introduced tutor assessment into a problem-based medical curriculum and examined the patterns of tutor marks in four subjects, in terms of within semester consistency and their relation to other forms of assessment in the course.

MATERIALS AND METHOD

Seventy-four tutors assessed 187 students twice (formative assessment in mid-semester, summative assessment at the end of semester) in each semester, using an assessment tool that focussed on communication and learning skills. Tutor marks were examined using correlations, cluster analysis and chi-square coefficients.

RESULTS

There were consistent trends in the patterns of cluster membership for pairs of marks in high, average and low clusters from mid-semester formative to end-of-semester summative assessment. Cluster membership for pairs of marks was predominantly consistent. Most movement was from lower to higher clusters over the two assessments, reflecting student improvement after tutors' feedback and tutor responsiveness to feedback to them. There was little variance in the marks of different tutors. Tutor marks correlated moderately and significantly with other forms of assessment in each subject.

CONCLUSION

Tutor marks contribute useful, distinctive dimensions to assessment in a problem-based medical curriculum.

Effect of pre-existing cytotoxic T lymphocytes on therapeutic vaccines

Therapeutic vaccines which aim to induce CD8(+) cytotoxic T lymphocyte (CTL) responses will often be required to perform in the presence of pre-existing CTL which recognize epitopes within the vaccine. Here we explore the ability of a viral vaccine vector presenting several co-dominant CTL epitopes to prime CTL responses in animals that have a pre-existing CTL response to one of the epitopes in the vaccine. The vaccine was usually capable of inducing multiple new responses, suggesting that immunodomination effects of pre-existing CTL may generally be minimal following vaccination. However, when large numbers of pre-existing CTL were present, a novel type of immune modulation was observed whereby (1) the vaccine failed to prime efficiently new CTL responses that were restricted by the same MHC gene as the pre-existing responses, and (2) vaccine-induced CTL responses restricted by other MHC genes were enhanced. These results may have implications for therapeutic multi-epitope vaccines for diseases like HIV and melanoma, which aim to broaden CTL responses.

An HLA-A2 Polyepitope Vaccine for Melanoma Immunotherapy

Epitope-based vaccination strategies designed to induce tumor-specific CD8 CTL are being widely considered for cancer immunotherapy. Here we describe a recombinant poxvirus vaccine that codes for ten HLA-A2-restricted epitopes derived from five melanoma Ags conjoined in an artificial polyepitope or polytope construct. Target cells infected with the melanoma polytope vaccinia were recognized by three different epitope-specific CTL lines derived from HLA-A2 melanoma patients, and CTL responses to seven of the epitopes were generated in at least one of six HLA-A2-transgenic mice immunized with the construct. CTL lines derived from vaccinated transgenic mice were also able to kill melanoma cells in vitro. Multiple epitopes within the polytope construct were therefore shown to be individually immunogenic, illustrating the feasibility of the polytope approach for melanoma immunotherapy. Tumor escape from CTL surveillance, through down regulation of individual tumor Ags and MHC alleles, might be overcome by polytope vaccines, which simultaneously target multiple cancer Ags.

An HLA-A2 polyepitope vaccine for melanoma immunotherapy

Epitope-based vaccination strategies designed to induce tumor-specific CD8 CTL are being widely considered for cancer immunotherapy. Here we describe a recombinant poxvirus vaccine that codes for ten HLA-A2-restricted epitopes derived from five melanoma Ags conjoined in an artificial polyepitope or polytope construct. Target cells infected with the melanoma polytope vaccinia were recognized by three different epitope-specific CTL lines derived from HLA-A2 melanoma patients, and CTL responses to seven of the epitopes were generated in at least one of six HLA-A2-transgenic mice immunized with the construct. CTL lines derived from vaccinated transgenic mice were also able to kill melanoma cells in vitro. Multiple epitopes within the polytope construct were therefore shown to be individually immunogenic, illustrating the feasibility of the polytope approach for melanoma immunotherapy. Tumor escape from CTL surveillance, through down regulation of individual tumor Ags and MHC alleles, might be overcome by polytope vaccines, which simultaneously target multiple cancer Ags.

Activation and adoptive transfer of Epstein-Barr virus-specific cytotoxic T cells in solid organ transplant patients with posttransplant lymphoproliferative disease

The treatment of Epstein-Barr virus (EBV)-associated lymphoproliferative disease (PTLD) in EBV seronegative solid organ transplant recipients who acquire their EBV infection after engraftment poses a considerable challenge because of underlying immunosuppression that inhibits the virus-specific cytotoxic T cell (CTL) response in vivo. We have developed a protocol for activating autologous EBV-specific CTL lines from these patients and show their potential use for immunotherapy against PTLD in solid organ transplant patients. Peripheral blood mononuclear cells from a panel of solid organ transplant recipients with and without active PTLD were used to assess EBV-specific memory CTL responses. The activation protocol involved cocultivation of peripheral blood mononuclear cells with an autologous lymphoblastoid cell line under conditions that favored expansion of virus-specific CTL and hindered the proliferation of allospecific T cells. These CTL consistently showed (i) strong EBV-specificity, including reactivity through defined epitopes in spite of concurrent immunosuppressive therapy, and (ii) no alloreactivity toward donor alloantigens. More importantly, adoptive transfer of these autologous CTLs into a single patient with active PTLD was coincident with a very significant regression of the PTLD. These results demonstrate that a potent EBV-specific memory response can be expanded from solid organ recipients who have acquired their primary EBV infection under high levels of immunosuppressive therapy and that these T cells may have therapeutic potential against PTLD.

Developing immunotherapeutic strategies for the control of Epstein-Barr virus-associated malignancies

Epstein-Barr virus (EBV) infection is associated with various physical human malignancies. The potential for immunotherapeutic treatment by cytotoxic T cells (CTL) depends on the degree of EBV-antigen expression, with the best prospect revolving around the immunoblastic lymphomas of organ transplant patients in which adoptive transfer of in vitro reactivated CTL has already been demonstrated to be effective. Opportunities for effective immunotherapy in the treatment of nasopharyngeal carcinoma (NPC) is reduced because the available targets are limited to relatively nonimmunogenic proteins. However, analysis of NPC cells has revealed normal expression of the major histocompatibility complex (MHC)-encoded peptide transporters TAP-1 and TAP-2, together with high levels of human leukocyte antigen (HLA) class I alleles on the cell surface. Burkitt's lymphoma (BL) displays downregulated expression of MHC class I and TAP-1 and TAP-2 proteins, whereas viral antigen expression is limited to a protein incapable of processing class I CTL epitopes. It therefore seems likely that effective treatment of BL will revolve around protocols designed to reverse its undifferentiated phenotype.

Immunogenicity of a human immunodeficiency virus (HIV) polytope vaccine containing multiple HLA A2 HIV CD8(+) cytotoxic T-cell epitopes

Compelling evidence now suggests that alphabeta CD8 cytotoxic T lymphocytes (CTL) have an important role in preventing human immunodeficiency virus (HIV) infection and/or slowing progression to AIDS. Here, we describe an HIV type 1 CTL polyepitope, or polytope, vaccine comprising seven contiguous minimal HLA A2-restricted CD8 CTL epitopes conjoined in a single artificial construct. Epitope-specific CTL lines derived from HIV-infected individuals were able to recognize every epitope within the construct, and HLA A2-transgenic mice immunized with a recombinant virus vaccine coding for the HIV polytope also generated CTL specific for different epitopes. Each epitope in the polytope construct was therefore processed and presented, illustrating the feasibility of the polytope approach for HIV vaccine design. By simultaneously inducing CTL specific for different epitopes, an HIV polytope vaccine might generate activity against multiple challenge isolates and/or preempt the formation of CTL escape mutants.

Female preferences in a fish genus without female mate choice

The evolution and the adaptive logic (if any) of female mate choice are subjects of lively debate. Whereas most researchers believe that females have evolved to recognize signs of male 'quality' (the ability to provide females or their offspring with direct or indirect genetic or material benefits), there is intriguing evidence that males can evolve to appeal to pre-existing female preferences. Evidence for these pre-existing biases is often ambiguous because phylogenetic reconstructions have usually failed to establish conclusively whether the female preference or the favored male traits evolved first. This potential difficulty is minimal in the mosquitofish genus Gambusia, none of whose 45 species appears to have a female-choice mating system in the wild, and none of which shows the male behavioral and morphological traits that are characteristic of female choice. Nevertheless, in an experimental situation in the laboratory, female Gambusia holbrooki readily chose between models of males and demonstrated significant and reliable preferences for a variety of exaggerated male traits that are not seen in their species or their genus. Other morphological alterations were not preferred. The latent willingness of females to choose traits in a genus without such traits and without evident female choice in the wild is remarkable and may indicate a pre-existing bias in females that is ready to drive male evolution, should the social system or the ecological variables that control it change.

Peptide based cytotoxic T-cell vaccines; delivery of multiple epitopes, help, memory and problems

Synthetic CD8+ cytotoxic T-lymphocyte (CTL) peptide epitope based vaccines are being developed against a number of human diseases. Here we describe extensive preclinical testing of peptide epitope vaccines formulated with a protein as a source of CD4 help and Montanide ISA 720, an adjuvant currently in human clinical trials. Such water-in-oil formulations could effectively co-deliver several peptide epitopes and simultaneously induce multiple independent CTL responses. The efficiency of CTL induction by some peptides was, however, dependent on the aqueous buffer conditions, with poor performance correlating with non-covalent peptide oligomerisation. Any of a number of proteins currently used in human vaccines could supply CD4 help and no difference in CTL induction was obtained if the CD4 response was amnestic or a primary. Peptide immunisation was found to induce long term CTL memory and the recall of protective responses did not depend on an amnestic CD4 response. Slow pyroglutamic acid formation and rapid oxidation of methionine residues was observed in water-in-oil formulations, however, the latter had no effect on CTL induction. These data highlight the need to monitor for potential deleterious chemical events and interpeptide interactions, but illustrate that peptide based vaccination can effectively deliver multiple epitopes, in conjunction with any protein, and induce protective memory.

Crossreactive recognition of viral, self, and bacterial peptide ligands by human class I-restricted cytotoxic T lymphocyte clonotypes: implications for molecular mimicry in autoimmune disease

The immunodominant, CD8(+) cytotoxic T lymphocyte (CTL) response to the HLA-B8-restricted peptide, RAKFKQLL, located in the Epstein-Barr virus immediate-early antigen, BZLF1, is characterized by a diverse T cell receptor (TCR) repertoire. Here, we show that this diversity can be partitioned on the basis of crossreactive cytotoxicity patterns involving the recognition of a self peptide-RSKFRQIV-located in a serine/threonine kinase and a bacterial peptide-RRKYKQII-located in Staphylococcus aureus replication initiation protein. Thus CTL clones that recognized the viral, self, and bacterial peptides expressed a highly restricted alphabeta TCR phenotype. The CTL clones that recognized viral and self peptides were more oligoclonal, whereas clones that strictly recognized the viral peptide displayed a diverse TCR profile. Interestingly, the self and bacterial peptides equally were substantially less effective than the cognate viral peptide in sensitizing target cell lysis, and also resulted only in a weak reactivation of memory CTLs in limiting dilution assays, whereas the cognate peptide was highly immunogenic. The described crossreactions show that human antiviral, CD8(+) CTL responses can be shaped by peptide ligands derived from autoantigens and environmental bacterial antigens, thereby providing a firm structural basis for molecular mimicry involving class I-restricted CTLs in the pathogenesis of autoimmune disease.

Delivery of multiple CD8 cytotoxic T cell epitopes by DNA vaccination

Development of CD8 alphabeta CTL epitope-based vaccines requires an effective strategy capable of co-delivering large numbers of CTL epitopes. Here we describe a DNA plasmid encoding a polyepitope or "polytope" protein, which contained multiple contiguous minimal murine CTL epitopes. Mice vaccinated with this plasmid made MHC-restricted CTL responses to each of the epitopes, and protective CTL were demonstrated in recombinant vaccinia virus, influenza virus, and tumor challenge models. CTL responses generated by polytope DNA plasmid vaccination lasted for 1 yr, could be enhanced by co-delivering a gene for granulocyte-macrophage CSF, and appeared to be induced in the absence of CD4 T cell-mediated help. The ability to deliver large numbers of CTL epitopes using relatively small polytope constructs and DNA vaccination technology should find application in the design of human epitope-based CTL vaccines, in particular in vaccines against EBV, HIV, and certain cancers.

Delivery of Multiple CD8 Cytotoxic T Cell Epitopes by DNA Vaccination

Development of CD8 αβ CTL epitope-based vaccines requires an effective strategy capable of co-delivering large numbers of CTL epitopes. Here we describe a DNA plasmid encoding a polyepitope or “polytope” protein, which contained multiple contiguous minimal murine CTL epitopes. Mice vaccinated with this plasmid made MHC-restricted CTL responses to each of the epitopes, and protective CTL were demonstrated in recombinant vaccinia virus, influenza virus, and tumor challenge models. CTL responses generated by polytope DNA plasmid vaccination lasted for 1 yr, could be enhanced by co-delivering a gene for granulocyte-macrophage CSF, and appeared to be induced in the absence of CD4 T cell-mediated help. The ability to deliver large numbers of CTL epitopes using relatively small polytope constructs and DNA vaccination technology should find application in the design of human epitope-based CTL vaccines, in particular in vaccines against EBV, HIV, and certain cancers.

Selection of a diverse TCR repertoire in response to an Epstein-Barr virus-encoded transactivator protein BZLF1 by CD8+ cytotoxic T lymphocytes during primary and persistent infection

We investigated the CD8+ cytotoxic T lymphocyte (CTL) repertoire to an HLA B8-restricted peptide, RAKFKQLLQ, located in the Epstein-Barr virus (EBV) immediate-early protein, BZLF1. Repertoire selection was monitored by determining the TCR beta chain sequences of RAKFKQLLQ-specific CTL established from primary infected and healthy virus carriers. PCR analysis of spontaneous EBV-transformed lymphoblastoid cell lines (LCL) from three individuals with primary infection showed that two were infected with type A and one with type B EBV. Polyclonal and clonal CTL that were generated by stimulating peripheral blood mononuclear cells with an HLA B8+ homozygous LCL lysed T cell blasts pulsed with the peptide, RAKFKQLLQ; lysis of certain HLA B8+ LCL targets was associated with the abundance of BZLF1 transcripts. TCR beta analysis showed that while there was loop length restriction in the putative peptide contact site of all responding beta chains, diverse and unique (non-recurrent) TCR beta clonotypes were selected in individuals during primary infection and continued to emerge after long-term virus exposure. TCR-contact site heterogeneity was excluded as the selective force in diversity generation since the epitope-encoded sequences were found to be identical within endogenous virus isolates. In this first study of TCR repertoire selection for an EBV lytic antigen, a BZLF1-reactive component of diverse clonotypes was identified in primary type A or type B EBV infection which was sustained in the EBV-specific memory response throughout life-long infection. This diversity selection is likely to play a critical role in maintaining a balanced viral load throughout EBV persistence.

Dominant cytotoxic T lymphocyte response to the immediate-early trans-activator protein, BZLF1, in persistent type A or B Epstein-Barr virus infection

Five healthy human leukocyte antigen-B8 (HLA-B8)-positive virus carriers were studied to investigate the CD8+ cytotoxic T lymphocyte (CTL) response to an HLA-B8-restricted peptide, RAKFKQLLQ, located in the Epstein-Barr virus (EBV) immediate-early trans-activator protein, BZLF1. Of the 5 virus carriers, 4 were infected with type A and 1 with type B EBV. Using limiting-dilution analysis of peripheral blood mononuclear cells, a high RAKFKQLLQ-specific CTL precursor frequency was demonstrated after specific peptide or autologous lymphoblastoid cell line stimulation in both type A and type B EBV carriers. The RAKFKQLLQ-specific CTL precursor frequencies in all 5 persons were at least as dominant as those observed with two other EBV-associated, HLA-B8-restricted latent epitopes, FLRGRAYGL and QAKWRLQTL. These findings show that healthy virus carriers maintain a high frequency of BZLF1-specific memory T cells, potentially to control virus spread from lytically infected cells.

The methodology of cost-effectiveness analysis: avoiding common pitfalls

Clinicians need to be familiar with the core methodology of cost-effectiveness economic analysis, as this information will increasingly be used in clinical decision-making. Just as in clinical trials, there are rules to be followed, and many pitfalls for the novice.

Repair of rat gastric mucosa: effect of 16,16-dimethyl prostaglandin E2

Prostaglandins protect the gastric mucosa against a variety of injurious agents and may accelerate the recovery of the gastric mucosa following damage. In previous studies prostaglandins were given prior to the injurious agent, so it was not possible to distinguish their potential effects on accelerating repair or reducing initial damage. We have investigated the effect of 16,16-dimethyl prostaglandin E2 (dmPGE2) on the repair of the gastric mucosa after injury induced by several injurious agents. dmPGE2 was given orally 15 min prior to aspirin or sodium salicylate, or 30 min after aspirin, sodium salicylate, or ethanol. dmPGE2 delivered prior to injury reduced the aspirin-induced fall in mucosal potential difference (PD), but had no effect on that induced by sodium salicylate. dmPGE2 administered after ASA injury significantly increased recovery of PD (P < 0.05), but did not alter the rate of recovery of PD with other damaging agents. Histological damage was decreased in rats treated with dmPGE2 after aspirin compared to aspirin-only-treated rats (P < 0.02). Exogenous dmPGE2 protects and restores gastric mucosal integrity after aspirin damage but has no effect on the repair of sodium salicylate and ethanol injured mucosa, suggesting that repair of the gastric mucosa after aspirin damage is enhanced by dmPGE2 due to its ability to prevent ongoing damage, rather than directly enhancing repair processes.

Human leukocyte antigen phenotype imposes complex constraints on the antigen-specific cytotoxic T lymphocyte repertoire

The memory response to the immunodominant Epstein-Barr virus (EBV) epitope FLRGRAYGL, which associates with HLA B8, is exceptionally restricted, being dominated by cytotoxic T lymphocytes (CTL) with a single, public T cell receptor (TCR). CTL clones that express this receptor fortuitously cross-react with the alloantigen HLA B44. However, of the two major subtypes of this HLA, B*4402 and B*4403, that differ by a single amino acid, only the former is recognized by these mature CTL clones. Individuals heterozygous for HLA B8 and B*4402 use alternative TCR for the EBV determinant since the dominant TCR is potentially self-reactive. We now demonstrate that this clonotype is also essentially absent from the repertoire of CTL directed against the viral epitope in seven from seven unrelated individuals heterozygous for HLA B8 and B*4403. Thus immune tolerance of these CTL recognizing HLA B*4402 is associated with expression of either B*4402 or B*4403. This suggests that tolerance in the human T cell compartment requires a lower threshold of recognition than for effector function, thus providing a buffer zone minimizing the risk of autoimmunity. These data also illustrate the potential for non-restricting HLA molecules to bias dramatically the T cell repertoire used for specific immune responses. Such influences may be the basis of the "protective" effects of certain HLA alleles in susceptibility to autoimmune disorders.

Pharmacokinetics of midazolam in Vietnamese subjects

In order to examine the investigators' clinical suspicion that Vietnamese patients were more sensitive to the sedative effects of midazolam than were Caucasians, the pharmacokinetics of a single, weight-adjusted intravenous dose of midazolam (0.05 mg/kg) were compared in a group of healthy Caucasian and Vietnamese male volunteers. The Vietnamese group (n = 8) had a significantly lower height, lean body mass and mean weight (59.8 +/- 5.5 vs 72.1 +/- 8.1 kg, respectively) compared with the Caucasian group (n = 8). No significant differences were found between the Vietnamese and Caucasian groups with regard to distribution half-life of midazolam (8.38 +/- 13.1 vs 1.49 +/- 0.63 min, respectively), elimination half-life (2.49 +/- 1.80 vs 1.48 +/- 0.66 h, respectively), clearance (4.93 +/- 1.31 vs 5.90 +/- 2.12 mL/min per kg, respectively), steady state volume of distribution (0.863 +/- 0.497 vs 0.530 +/- 0.132 L/kg, respectively) or percentage of unbound drug in plasma (4.89 +/- 0.74 vs 4.11 +/- 1.08, respectively). This suggests that dosage of midazolam in Vietnamese should be based on total bodyweight. Two Vietnamese subjects who were brothers had marked elevation of distribution half-life and initial volume of distribution and lesser elevations in elimination half-life and volume of distribution at steady state. This suggests that the known subgroup of subjects who demonstrate dyshomogeneity in midazolam volume of distribution may be genetically determined.

Development of Epstein-Barr virus-specific memory T cell receptor clonotypes in acute infectious mononucleosis

The importance of cytotoxic T lymphocytes (CTLs) in the immunosurveillance of Epstein-Barr virus (EBV)-infected B cells is firmly established, and the viral antigens of CTL recognition in latent infection are well defined. The epitopes targeted by CTLs during primary infection have not been identified, however, and there is only limited information about T cell receptor (TCR) selection. In the present report, we have monitored the development of memory TCR-beta clonotypes selected in response to natural EBV infection in a longitudinal study of an HLA-B8+ individual with acute infectious mononucleosis (IM). By stimulating peripheral blood lymphocytes with HLA-B8+ EBV-transformed B lymphoblastoid cells, the primary virus-specific CTL response was shown to include specificities for two HLA-B8-restricted antigenic determinants, FLRGRAYGL and QAKWRLQTL, which are encoded within the latent EBV nuclear antigen EBNA-3. TCR-beta sequence analysis of CTL clones specific for each epitope showed polyclonal TCR-beta repertoire selection, with structural restrictions on recognition that indicated antigen-driven selection. Furthermore, longitudinal repertoire analysis revealed long-term preservation of a multiclonal effector response throughout convalescence, with the reemergence of distinct memory T cell clonotypes sharing similar structural restrictions. Tracking the progression of specific TCR-beta clonotypes and antigen-specific TCR-V beta family gene expression in the peripheral repertoire ex vivo using semiquantitative PCR strongly suggested that selective TCR-beta expansions were present at the clonotype level, but not at the TCR-V beta family level. Overall, in this first analysis of antigen-specific TCR development in IM, a picture of polyclonal TCR stimulation is apparent. This diversity may be especially important in the establishment of an effective CTL control during acute EBV infection and in recovery from disease.

Recombinant polyepitope vaccines for the delivery of multiple CD8 cytotoxic T cell epitopes

Development of epitope-based CD8 alpha beta CTL vaccines requires effective strategies for codelivery of large numbers of individual epitopes. We have designed an artificial "polyepitope" protein containing 10 contiguous minimal CTL epitopes, which were restricted by five MHC alleles and derived from five viruses, a parasite, and a tumor model. A recombinant vaccinia virus coding for this protein was capable of inducing MHC-restricted primary CTL responses to all 10 epitopes. Mice immunized with this recombinant vaccinia showed protection against murine cytomegalovirus, Sendai virus, and a tumor model. This simple generic approach to multiepitope delivery should find application in CTL-based vaccine design.

Recombinant polyepitope vaccines for the delivery of multiple CD8 cytotoxic T cell epitopes

Development of epitope-based CD8 alpha beta CTL vaccines requires effective strategies for codelivery of large numbers of individual epitopes. We have designed an artificial "polyepitope" protein containing 10 contiguous minimal CTL epitopes, which were restricted by five MHC alleles and derived from five viruses, a parasite, and a tumor model. A recombinant vaccinia virus coding for this protein was capable of inducing MHC-restricted primary CTL responses to all 10 epitopes. Mice immunized with this recombinant vaccinia showed protection against murine cytomegalovirus, Sendai virus, and a tumor model. This simple generic approach to multiepitope delivery should find application in CTL-based vaccine design.

Indomethacin damage to rat gastric mucosa is markedly dependent on luminal pH

1. There is good evidence that acid is a prerequisite for aspirin induced gastric mucosal damage; however, there is inconsistent information available for non-salicylate NSAID. The present study examines the effect of gastric luminal pH on indomethacin-induced gastric mucosal damage. 2. Macroscopic gastric mucosal damage induced by indomethacin (40 mg/kg) or vehicle, administered intraduodenally to male pylorus-ligated rats (n = 5-10/group), was assessed at four different levels of luminal pH (2,4,5.5 and 7) by means of digital planimetry. 3. There was a marked difference in the extent of damage induced by indomethacin at the different luminal pH levels (P = 0.001). There was no difference between the percentage of haemorrhagic lesions at pH 2 and 4 (P > 0.05), nor between pH 5.5 and 7 (P > 0.05). However, the damage at the high levels of luminal acidity (pH 2 and 4) was strikingly different from that at pH 5.5 and 7 (P < 0.05). 4. Gastric mucosal damage induced by indomethacin, a non-salicylate NSAID, is augmented by the presence of high concentration of acid in the gastric lumen. The main finding, that indomethacin injury is markedly less above pH 4, may have clinical implications in the prevention of NSAID-induced mucosal injury.

Correlation between transmucosal potential difference and morphological damage during aspirin injury of gastric mucosa in rats

The potential difference (PD) that is maintained across healthy gastric mucosa is thought to be due to asymmetric ion pumping combined with resistance to back-diffusion of the separated charge. However, the structures that are responsible for this have not been clearly defined. This study examined the temporal changes in PD in rat stomach after injury by a single dose of aspirin. Multiple linear regression was used to compare this with the time course of several parameters of histological damage: (i) the per cent mucosal length showing superficial (confined to surface and gastric pits), deep (involving the isthmus or deeper in oxyntic glands) and total damage; (ii) the number of discrete erosions; and (ii) the total area of erosions per cm sectioned. Mucosal PD fell during the first 30-60 min after aspirin. Superficial damage appeared early and was already recovering by this time. The time course of deep damage more closely matched the alterations in PD and stepwise regression analysis showed that this could be predicted by the amount of deep damage alone (P < 0.001). Changes in transmucosal PD after acute aspirin injury probably reflect damage to structures in the oxyntic glands and not just the breaking of the surface and pit cell 'barrier'.

Gastric mucosal adaptation to diclofenac injury

Adaptation occurs to the gastric injury produced by nonsteroidal antiinflammatory drugs during continued dosing. The aim of this study was to identify characteristics of this phenomenon that might help in the search for underlying mechanisms. The time frame for onset and offset of adaptation of diclofenac (damage assessed planimetrically) was examined in rats. Adaptation to oral diclofenac took three to five days to develop, and persisted for up to five days after the last dose. It was also demonstrable after subcutaneous dosing or when injury was measured by a change in mucosal potential difference. Diclofenac-adapted rats were protected against injury induced by subsequent exposure to ethanol, indomethacin, aspirin, or piroxicam, indicating that adaptation is not specific to injury by the adapting agent. This cross-adaptation was dose-dependent and characterized histologically by a reduction in deep damage. In conclusion, gastric adaptation to diclofenac is mediated by mechanisms that take several days to develop and be lost. The route of administration appears to be unimportant, but the development of both adaptation and cross-adaptation is influenced by dosage size.

Effect of erythrocyte binding on elimination of harmol by the isolated perfused rat liver

The effect on the hepatic elimination rate of drug bound to erythrocytes and to albumin was compared with harmol, a relatively hydrophilic drug of high hepatic intrinsic clearance, in the single-pass isolated perfused rat liver preparation (n = 12). The steady-state hepatic extraction ratio (E) of harmol (50 microM) was measured during three consecutive 35-min periods with three different perfusates: Krebs-Henseleit buffer, buffer containing bovine serum albumin (2%), and buffer containing washed human erythrocytes (10%) perfused at 5 mL/min/g liver in randomized order. The mean unbound fraction (fu) of harmol in the latter two perfusates was 0.55 +/- 0.07 and 0.62 +/- 0.08, respectively, and the mean E for the three perfusates were 0.85 +/- 0.06, 0.62 +/- 0.07, and 0.71 +/- 0.08, respectively. The sinusoidal model fitted the relationship between E and fu better than the venous equilibrium model. Four further experiments, with perfusates of buffer, buffer + 2% albumin, and buffer + 4% albumin, confirmed that harmol elimination conformed to the sinusoidal model. For each of the 12 experiments that used erythrocyte perfusate, E and fu data from each of the two non-erythrocyte perfusates were used to predict E for the erythrocyte perfusate at the observed fu of 0.62, with the sinusoidal model. There was no significant difference between the observed (0.71 +/- 0.08) and predicted (0.68 +/- 0.10) E values (p > 0.05). This result suggests that release of harmol from erythrocytes is not a rate-limiting factor in the hepatic elimination of harmol, and that plasma membrane permeability does not contribute readily to a red cell carriage effect, at least with moderately polar and small molecules.

Gastric microbleeding following single and repeated dosing with naproxen

BACKGROUND

Adaptation to gastric damage from nonsteroidal anti-inflammatory drugs (NSAID) has been observed during ongoing dosage in rats and humans. However, this does not always occur, and our previous data suggest that NSAID half-life may be a determining factor.

AIM

To investigate whether adaptation occurs during 1 week of naproxen administration in humans.

SUBJECTS

Thirteen healthy volunteers were studied at baseline, and after one or seven daily doses of naproxen 750 mg. Gastric microbleeding was measured 4 h after naproxen in gastric washings collected during a 30-min period. Serum thromboxane B concentrations were also assayed, as a marker of cyclo-oxygenase inhibition.

RESULTS

Mean blood loss after placebo was 0.60 microL/10 min (95% CI: 0.21-0.98). This rose to 2.15 (0.73-3.57) and 1.75 (0.74-2.76) microL/10 min after one and seven daily doses of naproxen, respectively (P < 0.05 vs. baseline; day 1 vs. 7 not significant). Thromboxane B concentrations were < 10% of control at both day 1 and 7 of dosing.

CONCLUSION

In accord with our findings in rats, adaptation to this moderately long acting NSAID in humans was not apparent. We conclude that any adaptation to naproxen is unlikely to be clinically important.

Cytogenetic response to alpha-interferon is predicted in early chronic phase chronic myeloid leukemia by M-bcr breakpoint location

Alpha-interferon (alpha-IFN) therapy is an effective agent in early chronic phase (ECP) chronic myeloid leukemia (CML), achieving hematologic control in the majority and major cytogenetic response (MCR) (reduction in Ph' +ve metaphases to < 35%) in a substantial minority. Currently no pretreatment markers exist to ascertain likelihood of meaningful response. The site of breakpoint in M-bcr and relationship to prognosis is controversial. Studies have been hampered by variation in definition of breakpoint and difference in treatment protocols. In this study of ECP CML patients, Southern analysis and reverse transcription polymerase chain reaction (RT-PCR) were used to determine breakpoint location. Patients received alpha-IFN (9 x 10(6) units/day) and dose-adjusted hydroxyurea (HU) to maintain granulocyte count between 1.0-2.0 x 10(9)/l for 6 months or more. Twelve of 31 patients entered on the study achieved a MCR. The Sokal index did not predict for cytogenetic response to alpha-IFN. Eight of 11 patients with 5' breakpoint achieved MCR compared to only four of 20 patients with 3' breakpoint (P = 0.007). These results suggest site of M-bcr rearrangement may be predictive of response to alpha-IFN therapy. If verified by further study, this may allow more appropriate use of alpha-IFN with respect to other modalities such as allogeneic transplant.

Induction of protective cytotoxic T cells to murine cytomegalovirus by using a nonapeptide and a human-compatible adjuvant (Montanide ISA 720)

The use of synthetic peptides representing cytotoxic T-cell (CTL) epitopes for human vaccination requires the identification of a suitable adjuvant formulation. A single immunization with Montanide ISA720/tetanus toxoid/YPHFMPTNL protected mice against murine cytomegalovirus and induced epitope-specific CTL. Such formulations will find application in peptide-based CTL anti-viral vaccines.

Efficacy of 12 months' misoprostol as prophylaxis against NSAID-induced gastric ulcers. A placebo-controlled trial

We performed a 12-month, double-blind, randomised, placebo-controlled study to determine the long term effect of misoprostol (600-800 micrograms/d) in the prevention of gastric ulcers and gastroduodenal erosions in 83 arthritis patients on chronic NSAID therapy. Patients underwent endoscopy at 0, 3, 6 and 12 months. At the initial endoscopy, 12 patients had an ulcer (11 gastric), which was healed prior to randomization. Seventy eligible patients reached the 3 month endoscopy. Four (12.5%) of the 32 patients given misoprostol developed a gastric ulcer compared with 11 (28.9%) of the 38 on placebo (p < 0.05, life-table analysis). Six of the 11 patients with an initial gastric ulcer developed a further gastric ulcer, compared to 9 of 58 patients without an initial ulcer (p < 0.05). We conclude that misoprostol decreases the cumulative development of NSAID-induced gastric ulcers. Patients with a previous NSAID-ulcer have a higher risk of further ulceration.

Use of X-linked clonal analysis in acute promyelocytic leukemia

X-linked clonal analysis (XLCA) either using Glucose-6-phosphate dehydrogenase (G-6-P-D) polymorphisms or restriction fragment length polymorphisms (RFLP) and methylation analysis has provided considerable understanding of haematologic malignancy. Acute Promyelocytic Leukemia (APL) is characterized by a unique cytogenetic translocation t(15;17), frequent achievement of remission without a preceding phase of marrow hypocellularity after induction chemotherapy and a high rate of clinical response to all-trans retinoic acid (ATRA). In limited studies XLCA has provided insight into the pathogenesis and mechanism of drug action in this disease.

Discordant neutrophil alkaline phosphatase activity and cytogenetic response in chronic myeloid leukemia treated with alpha-interferon

Decreased neutrophil alkaline phosphatase (NAP) synthesis is a classical feature of Philadelphia (Ph) positive chronic phase chronic myeloid leukemia (CML). Whether this aberration is an integral leukemic property of the cell or results from mediation by other factors is unclear. During alpha-interferon (alpha-IFN) based therapy the relationship between Ph chromosome suppression and NAP synthesis was examined. Four categories of response were observed in 19 patients studied sequentially. Significantly, persistent low NAP activity was observed in one patient in complete cytogenetic remission, while a second group of 7 patients demonstrated normal NAP activity in spite of persistence of the Ph chromosome in 100% of metaphases. In the absence of various clinical influences that can modulate NAP activity in chronic phase CML, the results reinforce the observation that the BCR/ABL fusion gene product is not a key factor influencing NAP activity in CML.

The effect of hypoxia on propranolol clearance during antegrade and retrograde flow in the isolated perfused rat liver preparation

We investigated, using the single-pass isolated perfused rat liver preparation, whether the centrilobular location of hepatic oxidative drug metabolism could be a contributing factor to the marked sensitivity of drug oxidation to hypoxia. Livers (N = 7) were each perfused for 130 min with 2 micrograms/mL (+)-propranolol, a drug metabolized almost entirely by oxidation in the rat. The direction of flow was reversed after 60 min, the order of flow direction being randomized. Normal oxygenation was used during the first 30 min of antegrade and of retrograde perfusion, but in the second 30 min perfusate was equilibrated with a N2/O2 mixture designed to reduce hepatic oxygen delivery by half. During normal oxygenation there was no significant difference between antegrade and retrograde perfusion in hepatic oxygen delivery and physiological parameters such as oxygen consumption and extraction, perfusion pressure and bile flow. During hypoxia, mean oxygen delivery was slightly lower with retrograde perfusion (retrograde: mean = 2.37 mumol/min/g liver, range = 1.56-3.17; antegrade: mean = 2.90 mumol/min/g liver, range = 1.96-4.08; P = 0.04), but there was no significant difference in physiological parameters within each liver (P > 0.05). Propranolol clearance during normal oxygenation was similar to the perfusion rate (10 mL/min) and was the same for both directions of perfusion (antegrade 9.88 +/- 0.07 mL/min, retrograde 9.88 +/- 0.13 mL/min, P > 0.05). Hypoxia reduced propranolol clearance substantially, but the decrease was significantly greater with antegrade perfusion (5.65 +/- 1.89 mL/min) than with retrograde perfusion (6.76 +/- 1.95 mL/min, P = 0.014). Oxidative drug metabolism is located primarily in the centrilobular zone and sinusoidal oxygen concentration is lowest in the "downstream" zone with both antegrade and retrograde perfusion. These findings suggest that the centrilobular location of propranolol metabolism may influence the effect of hypoxia on propranolol elimination, but is not a major contributor to the marked sensitivity of propranolol elimination to hypoxia antegrade perfusion.

The effect of hypoxia and acidosis on propranolol clearance in the isolated perfused rat liver preparation

The effect of hypoxia and acidosis on the elimination of an oxidatively metabolized drug, S-propranolol, was examined in the single-pass isolated perfused rat liver (IPRL). The experiments (N = 6) consisted of four consecutive 30 min phases: normal pH (pH 7.4)/normal oxygen delivery, normal pH/hypoxia, hypercapnic acidosis (pH 7.1)/normal oxygenation and hypercapnic acidosis/hypoxia. Hypoxia and acidosis were produced by equilibrating the perfusate with appropriate mixtures of O2, N2 and CO2. With normal oxygen delivery there was no difference in hepatic clearance of propranolol between normal pH and acidosis (9.65 +/- 0.34 and 9.78 +/- 0.11 mL/min, respectively. P < 0.05). During hypoxia, propranolol clearance was impaired to a similar extent under both pH conditions (7.41 +/- 0.97 and 8.06 +/- 0.81 mL/min, respectively, P > 0.05). Therefore, respiratory acidosis does not affect the clearance of propranolol by the IPRL, nor does it influence the sensitivity of propranolol clearance to hypoxia. Neither acidosis nor hypoxia resulted in a significant reduction in bile flow compared with the normal pH/normal oxygen phase and there was no correlation between bile flow and perfusate bicarbonate concentration (P > 0.05).