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J D Boyer

Publications and source records attributed to J D Boyer.

At least 19 recordsLinked to original sources
PubMed2004

Any clinical benefit from the use of oncofoetal markers in the management of chemotherapy for patients with metastatic colorectal carcinomas?

AIMS: Computed tomography (CT) is the reference technique for evaluating response to chemotherapy. The potential helpfulness of tumour markers is debated. MATERIALS AND METHODS: From March 1997 to January 1999, 91 consecutive patients receiving chemotherapy for metastatic colorectal carcinoma underwent whole-body spiral CT, estimates of anti-carcinoembryonic antigen (CEA) and CA19-9 every 8 weeks. RESULTS: CEA and CA19-9 levels were above normal in 78 (85.7%) and 61 (67.5%) patients, respectively. Tumour response evaluation according to the RECIST criteria was obtained at 8-week evaluation in 83 (91%) patients. The positive predictive values (PPV) for response of a decrease of the marker levels were 53.8 for CEA and 41.7 for CA19-9 using a 30% decrease threshold, and 60/52.2, respectively, using a 50% decrease threshold. Meaningful PPV values (> 90%) for progression of an increase of the marker levels were only obtained using the 200% increase threshold for CEA alone or a combination of CEA and CA 19-9. A 100% CEA increase between baseline and the 8-week evaluation was correlated to overall survival (P = 0.0023). The need for a radiological confirmation of tumour progression could be avoided by the systematic dosage of tumour markers at baseline and after 8 weeks of treatment only in a sub-population of 13% of the patients with a 200% increase of CEA or CA 19-9 at 8 weeks. CONCLUSIONS: CEA, CA 19-9, or both should be used with caution for tumour response evaluation to chemotherapy in addition to CT in metastatic colorectal carcinoma.

Aged↗
PubMed2002

Issues for improving multiplasmid DNA vaccines for HIV-1.

Since the first reports of plasmid vaccines, there have been substantial changes made to the design of plasmid backbones, as well as to the antibiotic resistance markers chosen for clinical vectors compared with first generation vectors. These changes aid manufacturing, production and scale up and at the same time aid conceptual safety by limiting the ability of the vaccines to transfer useful genetic selection genes to other bacterial infectious agents. In contrast, there has been little change to the original promoters or polyadenlyation tracts in the last decade. We have learned that these first generation plasmid vaccines for HIV-1 appear very well tolerated in humans. However, while safe and immunogenic, improving the immune potency of DNA vaccines is a critical goal for this technology. The combination of antigens used should be carefully examined for possible immune interference. Such interference may only become apparent when each component of the vaccine is tested individually. This interference also suggests one mechanism of immune pathogenesis possibly by HIV-1. Optimization of the immune response can come through manipulation of the transfection efficiency, expression or through the use of various T cell and B cell plasmid adjuvants. It is likely that the combination of such advancements will significantly improve the clinical phenotype of this important vaccine modality.

AIDS Vaccines↗
PubMed2002

IL-4 increases Simian immunodeficiency virus replication despite enhanced SIV immune responses in infected rhesus macaques.

It is widely believed that a Th1 type CD4 response is critical for enhancement of CD8 immunity and for controlling HIV-1 infection. Th2 type responses, such as what might be seen in a chronic parasitic infection, would sacrifice cellular immunity and thus benefit the virus at the expense of the host. However, there has been little direct examination of the hypothesis in a primate model system. Accordingly, the simian immunodeficiency virus (SIV) infected rhesus macaque model was used to investigate the impact of immunisation with SIV expressing DNA constructs and co-injection with IL-4 on the SIV specific immunological responses, lymphocyte cell counts, as well as the impact on viral load. IL-4 is a Th2 type cytokine, which enhances antibody production and inhibits a CD4 Th1 phenotype. Rhesus macaques were infected with 10 AID50 of SIVmac239 and treated with 9-[2-(phosphonomethoxy)propyl]adenine (PMPA) 9 weeks post-infection. During PMPA treatment, animals were immunised with plasmids that expressed the SIV proteins, env, rev, gag and pol. In addition, they were immunised with a construct that encoded the gene for IL-4. IL-4 co-immunisation increased the neutralizing antibody titres in this group. Importantly, the viral loads in animals vaccinated with IL-4 expressing plasmid increased during the immunisation regimens despite the higher neutralizing antibody titres. In addition, neutralizing antibodies did not correlate with viral set point prior to PMPA treatment, however, there was a correlation between viral loads and antibody titres following the treatment with PMPA. Antibody titres decreased following the suppression of viral load. Importantly, vaccination in the absence of IL-4 protected CD4 levels without increasing viral load. The data support the hypothesis that inappropriate immune bias toward a Th2 pathway would ultimately enhance disease progression.

Animals↗
PubMed2002

Assessment of tumour response to chemotherapy for metastatic colorectal cancer: accuracy of the RECIST criteria.

Evaluation of tumour size modifications in response to treatment is a critical issue in the management of advanced malignancies. In 1981, the World Health Organization (WHO) established guidelines for tumour response assessment. These WHO1981 criteria were recently simplified in a revised version, named RECIST (Response Evaluation Criteria in Solid Tumours), which uses unidimensional instead of bidimensional measurements, a reduced number of measured lesions, withdrawal of the progression criteria based on isolated increase of a single lesion, and different shrinkage threshold for definitions of tumour response and progression. In order to validate these new guidelines, we have compared results obtained with both classifications in a prospective series of 91 patients receiving chemotherapy for metastatic colorectal cancer. Data from iterative tomographic measurements were fully recorded and reviewed by an expert panel. The overall response and progression rates according to the WHO1981 criteria were 19% and 58%, respectively. Using RECIST criteria, 16 patients were reclassified in a more favourable subgroup, the overall response rate being 28% and the progression rate 45% (non-weighted kappa concordance test 0.72). When isolated increase of a single measurable lesion is not taken into account for progression with the WHO1981 criteria, only 7 patients were reclassified and the kappa test was satisfying, i.e. > or =0.75, for the whole population as well as for each of the responding and progressive subgroups. Since it provides concordant results with a simplified method, the use of RECIST criteria is recommended for evaluation of treatment efficacy in clinical trials and routine practice.

Adenocarcinoma↗
PubMed2001

Protection from immunodeficiency virus challenges in rhesus macaques by multicomponent DNA immunization.

Multicomponent DNA vaccines were used to elicit immune responses, which can impact viral challenge in three separate rhesus macaque models. Eight rhesus macaques were immunized with DNA vaccines for HIV env/rev and SIV gag/pol and were challenged intravenously with 10 animal infective doses (AID(50)) of cell-free SHIV IIIB. Three of eight immunized rhesus macaques were protected, exhibiting no detectable virus. Animals protected from nonpathogenic SHIVIIIB challenge were rested for extended periods of time and were rechallenged first with pathogenic SIV(mac239) and subsequently with pathogenic SHIV89.6P viruses. Following the pathogenic challenges, all three vaccinated animals were negative for viral coculture and antigenemia and were negative by PCR. In contrast, the control animals exhibited antigenemia by 2 weeks postchallenge and exhibited greater than 10 logs of virus/10(6) cells in limiting dilution coculture. The control animals exhibited CD4 cell loss and developed SIV-related wasting with high viral burden and subsequently failed to thrive. Vaccinated animals remained virus-negative and were protected from the viral load, CD4 loss, disease, and death. We observed strong Th1-type cellular immune responses in the protected macaques throughout the study, suggesting their important roles in protection. These studies support the finding that multicomponent DNA vaccines can directly impact viral replication and disease in a highly pathogenic challenge system, thus potentially broadening our strategies against HIV.

AIDS Vaccines↗
PubMed2001

Undermining in cutaneous surgery.

BACKGROUND: Benefits, risks, and technical aspects of undermining in cutaneous surgery are presented and reviewed in order to facilitate the execution of this fundamental task of cutaneous surgery. METHODS: The authors' extensive experience with thousands of cutaneous reconstructions and literature consultation form the basis of this review. RESULTS: Literature review and practical experience indicate that undermining reduces wound closing tension. Pertinent anatomic considerations, benefits, risks, as well as sharp and blunt undermining techniques and regional undermining recommendations are discussed. CONCLUSIONS: It is concluded that judicious undermining, properly performed by surgeons knowledgeable of cutaneous anatomy facilitates the execution and enhances cosmesis in cutaneous reconstruction. It is the authors' opinion that sharp undermining technique is the optimal method for most cutaneous reconstructions.

Animals↗
PubMed2000

Therapeutic immunization of HIV-infected chimpanzees using HIV-1 plasmid antigens and interleukin-12 expressing plasmids.

OBJECTIVE: To assess HIV-1 DNA vaccination and co-immunization with interleukin (IL)-12 and IL-10 as immunotherapy in the HIV-1 infected chimpanzee model system. METHODS: Four chimpanzees that were infected with HIV-1-IIIB for longer than 4 years and remained symptom free were immunized with HIV-1 plasmid vaccines. Two chimpanzees were immunized with DNA plasmids that encoded env/rev, gag/pol along with a plasmid that encoded both chains of human IL-12. A third animal was immunized with HIV-1 DNA vaccine constructs and co-immunized with an IL-10 expressing plasmid. Finally a control animal received the HIV-1 DNA vaccine constructs alone. RESULTS: There was no evidence of systemic toxicity associated with the administration of the DNA vaccines or the cytokine-expressing plasmids. We observed that the IL-12/HIV-1 DNA vaccinated animals had enhanced proliferative responses to multiple HIV-1 antigens at multiple time points. The animal that was co-immunized with HIV-1 and IL-10 did not have any changes in the proliferative responses. Finally, the control chimpanzee demonstrated moderate increases in the proliferative responses to HIV-1 antigens. The animal that received HIV-1 vaccines alone and the animals co-immunized with IL-12 all had declines in viral load over the course of the study, however, the decrease in viral loads were transient in all animals. CONCLUSION: Immunization of HIV-1 infected chimpanzees with DNA based vaccines containing the env, gag and pol genes can transiently boost the env specific proliferative responses. Co-administration of IL-12 expressing plasmids further leads to transient boosting of the proliferative response to the core protein, p24 as well. However, at these doses the impact on viral load is minimal.

AIDS Vaccines↗
PubMed2000

The chimpanzee and other non-human-primate models in HIV-1 vaccine research.

Animal models are of great importance for the study of disease pathogenesis, particularly non-human-primate models of infectious diseases. The role of non-human primates in HIV-1 research is continually discussed and debated. Here, we examine three primate models: chimpanzee-HIV-1, rhesus macaque-simian immunodeficiency virus and rhesus macaque-SHIV, and discuss immunological similarities and differences, safety and monetary issues, and ethical concerns.

AIDS Vaccines↗
PubMed2000

Vaccination of seronegative volunteers with a human immunodeficiency virus type 1 env/rev DNA vaccine induces antigen-specific proliferation and lymphocyte production of beta-chemokines.

There is a pressing need to test novel vaccine concepts in an effort to develop an effective vaccine for human immunodeficiency virus (HIV) type 1. A phase I clinical study was done to test the immunogenicity of an HIV env/rev DNA vaccine, which was administered intramuscularly to HIV-1-seronegative persons. Subjects received 3 doses of vaccine at a single concentration (100 or 300 microgram) at 0, 4, 8, and 24 weeks. In at least 1 of multiple assays, the 6 subjects who received the 300-microgram dose had DNA vaccine-induced antigen-specific lymphocyte proliferative responses and antigen-specific production of both interferon-gamma and beta-chemokine. Furthermore, 4 of 5 subjects in the 300 microgram-dose group responded to both the rev and env components of the vaccine. The responses did not persist within inoculated individuals and scored in different individuals at different times in the trial. This study supports that HIV-1 DNA vaccine antigens can stimulate multiple immune responses in vaccine-naive individuals, and it warrants additional studies designed to enhance DNA vaccine immunogenicity.

AIDS Vaccines↗
PubMed2000

Modulation of antigen-specific humoral responses in rhesus macaques by using cytokine cDNAs as DNA vaccine adjuvants.

An important limitation of DNA immunization in nonhuman primates is the difficulty in generating high levels of antigen-specific antibody responses; strategies to enhance the level of immune responses to DNA immunization may be important in the further development of this vaccine strategy for humans. We approached this issue by testing the ability of molecular adjuvants to enhance the levels of immune responses generated by multicomponent DNA vaccines in rhesus macaques. Rhesus macaques were coimmunized intramuscularly with expression plasmids bearing genes encoding Th1 (interleukin 2 [IL-2] and gamma interferon)- or Th2 (IL-4)-type cytokines and DNA vaccine constructs encoding human immunodeficiency virus Env and Rev and simian immunodeficiency virus Gag and Pol proteins. We observed that the cytokine gene adjuvants (especially IL-2 and IL-4) significantly enhanced antigen-specific humoral immune responses in the rhesus macaque model. These results support the assumption that antigen-specific responses can be engineered to a higher and presumably more desirable level in rhesus macaques by genetic adjuvants.

Adjuvants, Immunologic↗
PubMed2000

Engineering of DNA vaccines using molecular adjuvant plasmids.

These studies support the view that additional goals of enhancing DNA vaccine technology will probably be at several levels. The ability to deliver antigens more efficiently to professional APCs is likely to have important implications for our studies of basic principles of immunology. Furthermore, there are simple practical approaches to vaccine enhancement that can be tested with the present group of DNA vaccines. These studies should include the use of cytokine molecular adjuvants as well as possible co-stimulatory molecules. It is expected that the delivery of these "adjuvanted" DNA vaccines will require additional safety evaluation; however, it is clear that studies can be easily designed to address the important safety issues associated with these novel vaccine adjuvants. Overall, the results indicate that further more precise quantitative studies and combination studies examining these additional promising adjuvant candidates are warranted.

AIDS Vaccines↗
PubMed1999

HIV-1 DNA vaccines and chemokines.

DNA vaccines have a demonstrated ability to induce humoral and cellular immune responses in animal models and humans. The technology, although it dates back to the 1950's, has had an insurgence of interest within the past few years following concurrent research papers. The basic technology is being applied broadly to viral, bacterial and parasitic infections. It has also been demonstrated that genes delivered via plasmid expression vectors result in expression of functional proteins in the inoculated host. Further, injection of plasmids encoding cytokine, chemokine or co-stimulatory molecules, also referred to as immunomodulatory plasmids can lead to the further expansion of this technology to include directed immunology. We have been developing DNA technology specifically with a focus as a vaccine against HIV-1 infection. We report that such vaccines can stimulate immune responses in a variety of relevant animal systems including humoral and cellular responses as well as the production of beta-chemokines. We describe that the beta-chemokines can both modulate the immune response induced by DNA vaccines and be modulated by the DNA vaccines in the murine and chimpanzee models as well as in humans.

AIDS Vaccines↗
PubMed1999

Enhancement of cellular immune response in HIV-1 seropositive individuals: A DNA-based trial.

A DNA-based vaccine containing HIV-1 Env and Rev genes was tested for safety and host immune response in 15 HIV-infected asymptomatic patients with CD4-positive lymphocyte counts >/=500/microl of blood and receiving no antiviral therapy. Successive groups of patients received three doses of vaccine at 30, 100, or 300 microg at 10-week intervals in a dose-escalation trial. Some changes were noted in cytotoxic T-lymphocyte activity against gp160-bearing targets. Importantly, enhanced specific lymphocyte proliferative activity against HIV-1 envelope was observed in multiple patients. Three of three patients in the 300-microg dose group also developed increased MIP-1alpha levels which were detectable in their serum. Interestingly patients in the lowest dose group showed no overall changes in the immune parameters measured. The majority of patients who exhibited increases in any immune parameters were contained within the 300 microg, which was the highest dose group. These studies support further investigation of this technology for the production of antigen-specific immune responses in humans.

AIDS Vaccines↗
PubMed1999

Systemic and mucosal immunity is elicited after both intramuscular and intravaginal delivery of human immunodeficiency virus type 1 DNA plasmid vaccines to pregnant chimpanzees.

DNA vaccines encoding human immunodeficiency virus type 1 (HIV-1) env/rev and gag/pol were delivered intravaginally (IVAG) and intramuscularly (IM) to 2 pregnant chimpanzees. Vaccination was well tolerated and each chimpanzee developed antibodies (up to 1 year later) to both vaccines. Placental transfer of anti-Env and anti-Gag IgG was demonstrated in both maternal/infant pairs. Specific IgG was also demonstrated in saliva, vaginal, and rectal washes after IVAG immunization. Predominantly anti-HIV-1 IgA was detected in the milk of both mothers after both IM and IVAG immunization. Cellular responses included Gag-specific proliferation of lymphocytes and cytotoxic T lymphocytes against both antigens. These data suggest a strategy for induction of mucosal and systemic responses after both IM and IVAG delivery of DNA vaccines in a primate model and could ultimately be useful in lowering maternal-to-fetal transmission of HIV-1, perinatally and through breastfeeding.

AIDS Vaccines↗
PubMed1999

In vivo modulation of vaccine-induced immune responses toward a Th1 phenotype increases potency and vaccine effectiveness in a herpes simplex virus type 2 mouse model.

Several vaccines have been investigated experimentally in the herpes simplex virus type 2 (HSV-2) model system. While it is believed that CD4(+)-T-cell responses are important for protection in general, the correlates of protection from HSV-2 infection are still under investigation. Recently, the use of molecular adjuvants to drive vaccine responses induced by DNA vaccines has been reported in a number of experimental systems. We sought to take advantage of this immunization model to gain insight into the correlates of immune protection in the HSV-2 mouse model system and to further explore DNA vaccine technology. To investigate whether the Th1- or Th2-type immune responses are more important for protection from HSV-2 infection, we codelivered the DNA expression construct encoding the HSV-2 gD protein with the gene plasmids encoding the Th1-type (interleukin-2 [IL-2], IL-12, IL-15, and IL-18) and Th2-type (IL-4 and IL-10) cytokines in an effort to drive immunity induced by vaccination. We then analyzed the modulatory effects of the vaccine on the resulting immune phenotype and on the mortality and the morbidity of the immunized animals following a lethal challenge with HSV-2. We observed that Th1 cytokine gene coadministration not only enhanced the survival rate but also reduced the frequency and severity of herpetic lesions following intravaginal HSV challenge. On the other hand, coinjection with Th2 cytokine genes increased the rate of mortality and morbidity of the challenged mice. Moreover, of the Th1-type cytokine genes tested, IL-12 was a particularly potent adjuvant for the gD DNA vaccination.

Animals↗
PubMed1998

Molecular and immunological analysis of genetic prostate specific antigen (PSA) vaccine.

Nucleic acid immunization has been investigated as immunotherapy for infectious diseases as well as for treating specific types of cancers. In this approach, nucleic acid expression cassettes are directly inoculated into the host, whose transfected cells become the production source of novel and possibly immunologically foreign protein. We have developed a DNA vaccine construct which encodes for PSA by cloning a cDNA for PSA into a mammalian expression vector under control of a CMV promoter. We investigated and characterized the immunogenicity of PSA DNA expression cassettes in mice. PSA-specific immune responses induced in vivo by immunization were characterized by enzyme-linked immunosorbent assay (ELISA), T helper proliferation cytotoxic T lymphocyte (CTL), and flow cytometry assays. We observed a strong and persistent antibody response against PSA for at least 180 days following immunization. In addition, a significant T helper cell proliferation was observed against PSA protein. Using synthetic peptides spanning the PSA open frame, we identified four dominant T helper epitopes of PSA. Furthermore, immunization with PSA plasmid induced MHC Class I CD8+ T cell-restricted cytotoxic T lymphocyte response against tumor cell targets expressing PSA. The prostate represents a very specific functional organ critical for reproduction but not for the health and survival of the individual. Understanding the immunogenicity of PSA DNA immunization cassettes offers insight into the possible use of this tumor-associated antigen as a target for immunotherapy. These results demonstrate the ability of the genetic PSA to serve as a specific immune target capable of generating both humoral and cellular immune responses in vivo.

Animals↗
PubMed1998

CD8 positive T cells influence antigen-specific immune responses through the expression of chemokines.

The potential roles of CD8(+) T-cell-induced chemokines in the expansion of immune responses were examined using DNA immunogen constructs as model antigens. We coimmunized cDNA expression cassettes encoding the alpha-chemokines IL-8 and SDF-1alpha and the beta-chemokines MIP-1alpha, RANTES, and MCP-1 along with DNA immunogens and analyzed the resulting antigen-specific immune responses. In a manner more similar to the traditional immune modulatory role of CD4(+) T cells via the expression of Th1 or Th2 cytokines, CD8(+) T cells appeared to play an important role in immune expansion and effector function by producing chemokines. For instance, IL-8 was a strong inducer of CD4(+) T cells, indicated by strong T helper proliferative responses as well as an enhancement of antibody responses. MIP-1alpha had a dramatic effect on antibody responses and modulated the shift of immune responses to a Th2-type response. RANTES coimmunization enhanced the levels of antigen-specific Th1 and cytotoxic T lymphocyte (CTL) responses. Among the chemokines examined, MCP-1 was the most potent activator of CD8(+) CTL activity. The enhanced CTL results are supported by the increased expression of Th1 cytokines IFN-gamma and TNF-alpha and the reduction of IgG1/IgG2a ratio. Our results support that CD8(+) T cells may expand both humoral and cellular responses in vivo through the elaboration of specific chemokines at the peripheral site of infection during the effector stage of the immune response.

AIDS Vaccines↗