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Biomedical subjects

G Mor

Publications and source records attributed to G Mor.

At least 37 records · Page 2Linked to original sources
PubMed1998

Plasmid DNA: a new era in vaccinology.

DNA vaccination is a novel approach for inducing an immune response. Purified plasmid DNA containing an antigen's coding sequences and the necessary regulatory elements to express them is introduced into the tissue via intramuscular injection or particle bombardment. Once the DNA reaches the tissue, the antigen is expressed in enough quantity to induce a potent and specific immune response and to confer protection against further infections. The effectiveness of DNA vaccines against viruses, parasites, and cancer cells has been demonstrated in numerous animal models. This new approach comes as an aid for the prevention of infectious diseases for which the conventional vaccines have failed. Research on DNA vaccines is providing new insights into some of the basic immunological mechanisms of vaccination such as antigen presentation, the role of effector cells, and immunoregulatory factors. In addition, DNA vaccines may enable us to manipulate the immune system in situations where the response to agents is inappropriate or ineffective. The study of the potential deleterious effects of DNA vaccines is furthering our knowledge regarding the relationship between bacterial DNA and the immune system, as well as its potential application for the study of neonatal tolerance and autoimmunity.

Humans↗
PubMed1998

A monoclonal antibody to oestradiol potentiates the stimulation of the specific activity of the brain type creatine kinase by oestrogen in vivo and in vitro.

We described previously the in vivo immunoneutralization effects of a high affinity anti-oestradiol antibody clone 15 in blocking ovulation and synaptic remodeling in cycling female rats. In the present study we report the enhancing effects of this antibody. Treatment of ovariectomized female rats or female derived skeletal cell cultures in vitro with anti-E2 15 plus oestrogen (E2) potentiated the specific activity of the brain type creatine kinase (CK) response to E2 in the rat tissues or skeletal cells. The enhancing CK response of anti E2 15 plus E2 was time- and dose-dependent in the uterus, thymus, epiphysis and diaphysis of ovariectomized female rats. In the pituitary, on the other hand, anti-E2 15 blocked the stimulatory CK response to E2. Two other high affinity anti-E2 antibodies, clones 8D9 and 11B6, had no effect in augmenting the response of CK to E2 in rat tissues. Moreover, the enhancing CK response in rat tissues was specific to anti-E2 15 plus E2 since the intact anti-E2 in the presence of other oestrogen mimetics, such as oestriol or stilbestrol or tamoxifen did not potentiate the CK response in rat tissues. In this model system the Fab' monomer of anti-E2 15 abolished the CK response to E2 in rat tissues and not to anti-E2 15 plus E2 whereas tamoxifen completely blocked the CK response to anti E2 plus E2. Anti E2 15 may therefore serve as a specific carrier in delivering E2 to oestrogen sensitive rat tissues or cells containing functional oestrogen receptors and thereby increasing the magnitude of E2 effects in vivo and in vitro.

Animals↗
PubMed1998

Macrophages, estrogen and the microenvironment of breast cancer.

Estrogen is a major mitogenic stimulus to established breast cancer. Estrogen sources include ovarian, extraglandular sites and breast tissue. Which source primarily maintains benign and breast cancer tissue estrogen concentrations remains unclear. While macrophages may comprise up to 50% of the mass of breast carcinomas, previous studies neglected to study them as possible sources of estrogen. We present evidence that breast macrophages constitute an in situ source of estradiol and that the amount produced is sufficient to mediate cellular proliferation. We utilized immunohistochemistry and RT-PCR to study cell-specific aromatase expression in (i) 29 breast biopsies, (ii) human monocytes/macrophages and (iii) a myeloid cell line (THP-1) capable of differentiating into macrophages. Use of a breast cancer cell line (MCF-7) provided biologic confirmation of the role of aromatization in cell proliferation. We demonstrated considerable amounts of immunoreactive-aromatase (irARO) in breast tissue macrophages and a positive correlation between the proportion of irARO present in macrophages and lesion severity. Using in vitro techniques, we demonstrated that monocytes and THP-1 cells require differentiation into macrophages to produce aromatase in amounts approaching placental levels. The amount of estrogen produced by THP-1 cells stimulated MCF-7 cells to proliferate, an effect blocked by aromatase inhibitors. Estrogen production by macrophages in breast tissue appears sufficient to stimulate the proliferation of adjacent epithelial cells and to autoregulate cytokine production. These findings represent a new dimension of cellular regulation in breast tissue with major biologic implications, amenable to pharmacological manipulation.

Antineoplastic Agents↗
PubMed1998

Fas-fas ligand system-induced apoptosis in human placenta and gestational trophoblastic disease.

PROBLEM: The low frequency of maternal immune responses to paternally inherited fetal antigens raises the following question: What regulates the immunobiology of pregnancy? Data suggest that this state is the result of peripheral immune-tolerance, an active process of immune-regulation in which activated T cells undergo apoptosis. We studied Fas ligand (FasL) expression and apoptosis in normal and pathologic placentas to find out whether the Fas-FasL-induced apoptosis takes place during implantation. METHOD OF STUDY: FasL expression in paraffin sections was detected using specific antibodies and confirmed with reverse transcriptase-polymerase chain reaction of total RNA from frozen placentas. Apoptosis was detected using the terminal deoxy (d)-UTP nick end-labeling assay. RESULTS: FasL was found in the normal placenta and in gestational trophoblastic disease. Apoptotic leukocytes were localized to the maternal-fetal interface corresponding in localization with the distribution of FasL. CONCLUSIONS: We propose that FasL expression in the placenta is a mechanism responsible for the development of maternal immune tolerance specific for paternal alloantigens and operates in pathologic states characterized by trophoblastic invasion/proliferation.

Apoptosis↗
PubMed1998

Estrogen-receptor expression and function in thymocytes in relation to gender and age.

The expression of estrogen receptor (ER) in thymocytes was studied in young, middle-aged, and old (2, 12, and 24 months, respectively) female and male C57BL/6J mice. Western immunoblots prepared from the thymocytes of females of all age groups showed the presence of a 67-kD protein band, which has been associated with the apparent MW of denatured ER. Flow cytometry analysis of cells stained with a monoclonal anti-ER antibody (clone 13H2) disclosed ER expression in both females and males of all age groups. In vivo treatment with estradiol (E2) led to an increase in the specific activity of thymic creatine kinase (CK) in the female mice, whereas the male thymocytes responded with an increase in CK activity only on treatment with dihydrotestosterone (DHT). The data show no differences in ER expression between male and females, but the receptor appears not to be functional in males. Interestingly, when estradiol was applied to co-cultures of lymphoid-depleted fetal thymus (FT) explants and bone-marrow cells, or thymocytes, from young and old females, it resulted in increased cellularity of cultures containing cells of the young, and not those of the old. The proportion of CD4/CD8 phenotypes of the developing cells in these cultures was not affected by E2 treatment. These observations provide a new insight into ER expression and function in T-cell development in relation to gender and age.

Age Factors↗
PubMed1998

Raloxifene induces neurite outgrowth in estrogen receptor positive PC12 cells.

OBJECTIVE: It is well established that gonadal steroids have direct in vivo and in vitro effects on neurons. To further study these effects, we used rat PC 12 cells to examine the effects of estrogen receptor (ER) ligands on neuronal morphology. DESIGN: PC 12 cells constitutively express ER beta, but only strongly express ER alpha after long-term priming with nerve growth factor (NGF). We therefore primed PC12 cells with NGF for 14 days before testing them for estradiol (10(-9)M)- and/or raloxifene (10(-7) M)-induced neurite growth. Neurite growth was assessed by quantitative light microscopy. As control, ER status of the PC12 cells was assessed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In this study, both estradiol and raloxifene induced the outgrowth of neurites in NGF-treated PC 12 cells (p < 0.05). The combination of estradiol- and raloxifene-induced neurite growth was statistically greater than the effects of either agent alone. RT-PCR confirms that NGF-treated PC 12 cells express both ERalpha and ERbeta. CONCLUSIONS: This report is the first on the neurotrophic effect of raloxifene. At 10(-7) M, raloxifene's effect equaled that of estradiol; moreover, raloxifene did not block the neurite growth of simultaneously estradiol-treated PC 12 cells, despite its functional antiestrogenic effects in vivo. We conclude that raloxifene is estrogen agonistic in this animal model and therefore studies are warranted to delineate the relationship between steroidal estrogen and raloxifene.

Animals↗
PubMed1997

Do DNA vaccines induce autoimmune disease?

This report examines whether plasmid DNA vaccines induce the production of anti-DNA or anti-muscle cell autoantibodies. A three-fold increase in the number of B cells secreting immunoglobulin G (IgG) anti-DNA autoantibodies was detected in BALB/c mice immunized and boosted with any of three DNA plasmids (p < 0.004). This correlated with a transient increase in serum anti-DNA autoantibody titers but was not associated with the development of glomerulonephritis or autoimmune disease. None of the DNA vaccines examined stimulated the production of anti-muscle cell autoantibodies or the development of myositis. The effect of DNA vaccines on the development of nascent autoimmunity in lupus-prone (NZB x NZW)F1 mice was also examined. Repeated vaccination did not alter the onset or course of disease in these animals. These findings suggest that DNA vaccines neither initiate nor accelerate the development of systemic autoimmunity.

Animals↗
PubMed1997

DNA vaccines: safety and efficacy issues.

DNA technology has been harnessed to produce a variety of plasmid-based vaccines designed to prevent viral, bacterial and parasitic infections. The rapid adoption and implementation of this novel vaccine strategy carries with it important safety and efficacy concerns. This review will focus on whether DNA vaccines (1) are likely to induce systemic or organ-specific autoimmune disease, (2) have the potential to induce tolerance rather than immunity, and (3) are as effective in individuals with depressed immune function as they are in healthy adults.

Aging↗
PubMed1997

Estrogen stimulation of creatine kinase B specific activity in 3T3L1 adipocytes after their differentiation in culture: dependence on estrogen receptor.

We have demonstrated previously that rat adipose tissue showed sex and depot-specific responses to gonadal steroids. The epididymal fat pad in males responded exclusively to androgens by increased specific activity of the brain type isozyme of creatine kinase (CK). In females, the parametrial adipose tissue responded exclusively to estrogens. The present study was undertaken to follow the responsiveness to steroid hormones, and the presence of estrogen receptors (ER), in 3T3L1 cells during their differentiation from pre-adipocytes to adipocytes. In pre-adipocytes in which the basal CK specific activity is low, there was no CK response to 17beta estradiol (E2) or dihydrotestosterone (DHT). Differentiation of the cells into adipocytes was accompanied by increased basal CK activity which was stimulated by E2, but not by DHT. Responsiveness to E2 began 5 days after switching pre-adipocytes to differentiation medium. Upon differentiation, ER became demonstrable in the cell nuclei by staining with FITC labeled anti-idiotypic antibody (clone 1D5) directed against the steroid binding domain of ER. The response to E2 was time-dependent and blocked completely by cycloheximide or actinomycin D. 1D5 itself, which has an estrogen mimetic effect, stimulated CK activity in the cells similarly to E2. The antiestrogen tamoxifen which also stimulated CK activity in the adipocytes, completely blocked E2 action. The 'pure' antagonist of E2, ICI 164,384 and the tissue-selective antiestrogens, raloxifene or tamoxifen methiodide were also complete antagonists with no agonistic effects. The response of the 3T3L1 adipocytes to E2 was upregulated by 1,25(OH)2D3. Moreover, IGF1 was also a potent stimulator of CK in these cells, and therefore may mediate partially the stimulation by E2. Transient transfection of the pre-adipocytes with ER permitted E2 induction of CK. Thus, the appearance of ER and concomitant responsiveness to E2 is another hormone-related change occurring in 3T3L1 cells during differentiation, in addition to changes such as development of insulin responsiveness. The interactions in this system provide a useful in vitro model for investigating the development of responsiveness to E2.

3T3 Cells↗
PubMed1997

The beneficial effects of treatment with tamoxifen and anti-oestradiol antibody on experimental systemic lupus erythematosus are associated with cytokine modulations.

In an attempt to elucidate the role of oestrogens in systemic lupus erythematosus (SLE) we investigated the effects of treatment with an oestrogen antagonist-tamoxifen and a monoclonal anti-oestradiol (anti-E2) antibody on mice in which experimental systemic lupus erythematosus (SLE) was induced by a human monoclonal anti-DNA antibody bearing the 16/6 idiotype (16/6 Id). Thus, groups of BALB/c female mice were immunized with the 16/6 Id and 3 weeks following the booster injection, when antibody titres were elevated in the injected mice, treatment protocols with anti-oestradiol or tamoxifen were initiated. Control groups that were not immunized with the 16/6 Id but were similarly treated with the above agents were included in the study. The treatment with the above agents had no effect on the total autoantibody titres; however, a decrease in the immunoglobulin G (IgG)2a/IgG1 ratio of the anti-DNA antibodies was determined in the 16/6 Id immunized and treated mice. Further both the anti-oestradiol and tamoxifen had beneficial effects on the clinical manifestations (white blood cell counts, levels of protein in the urine and immune complex deposits in the kidneys) of the 16/6 Id immunized and treated mice. We have previously observed a significant elevation in interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha) secretion in mice with experimental SLE and a reduction in IL-2, IL-4 and interferon-gamma (INF-gamma) levels as compared with the levels detected in healthy controls. Treatment with either the anti-oestradiol antibody or with tamoxifen restored the levels of all the above cytokines to the normal levels observed in the control mice. These findings suggest that cytokine modulation may be the basis for the therapeutic effects of both anti-oestrogens in experimental SLE.

Animals↗
PubMed1996

Induction of neonatal tolerance by plasmid DNA vaccination of mice.

Plasmid DNA vaccines capable of preventing viral, bacterial, and parasitic infections are currently under development. Our labs have shown that a plasmid DNA vaccine encoding the circumsporozoite protein of the malaria parasite elicits protective immunity against live sporozoite challenge in adult BALB/c mice. We now find that the same DNA vaccine induces tolerance rather than immunity when administered to 2-5 d-old mice. Neonatally tolerized animals were unable to mount antibody, cytokine or cytotoxic responses when rechallenged with DNA vaccine in vitro or in vivo. Tolerance was specific for immunogenic epitopes expressed by the vaccine-encoded, endogenously produced antigen. Mice challenged with exogenous circumsporozoite protein produced antibodies against a different set of epitopes, and were not tolerized. These findings demonstrate important differences in the nature and specificity of the immune response elicited by DNA vaccines versus conventional protein immunogens.

Age Factors↗
PubMed1996

Synaptic remodeling in the arcuate nucleus during the estrous cycle is induced by estrogen and precedes the preovulatory gonadotropin surge.

We have shown that the ovarian cycle is accompanied by a fall in the axosomatic synapses on randomly selected neurons of the arcuate nucleus by the morning of estrus, with a return to the preovulatory levels by the morning of metestrus, indicating a possible role in positive feedback. However, it remains to be proven that the circulating estradiol is the actual regulator of this physiological synaptic plasticity, or that estrogen-induced synaptic retraction precedes in the surge of gonadotropins at midcycle. To resolve these questions, we used an estradiol-immunoneutralization protocol and studied arcuate nucleus axosomatic synapses during the critical points of the estrous cycle. In addition to blocking positive feedback, estrogen immunoneutralization abolished synaptic retraction in the arcuate nucleus. As a positive control, the nonbinding estrogen diethylstilbestrol maintained the gonadotropin surge and synaptic retraction in the antiestradiol-treated animals. Furthermore, in the diluent-treated cycling control females, the synaptic retraction was found to precede the preovulatory LH surge. We demonstrated that the midcycle synaptic retraction of arcuate nucleus synapses is induced by the preovulatory estradiol surge, and that these morphological events precede the preovulatory gonadotropin surge. Taken together, these observations strongly suggest that the hypothalamic mechanism underlying the physiological disinhibition of gonadotropins at midcycle (positive feedback) requires estrogen-induced synaptic retraction in the arcuate nucleus.

Animals↗
PubMed1996

Anti-idiotypic antibody as an oestrogen mimetic in vivo: stimulation of creatine kinase specific activity in rat animal models.

Previous studies indicated that the anti-idiotypic antibody (clone 1D5) significantly increased the specific activity of creatine kinase (CK) activity in the rat uterus, and in vitro in skeletal cells capable of responding to oestradiol (E2), suggesting that the antibody has oestrogenic-like activity. Moreover, the F(ab')2 dimer of clone 1D5 acted like an antagonist and completely inhibited the increase in CK specific activity by either E2 or clone 1D5 in these skeletal cells. In the present study, we examined the in vivo effects of clone 1D5 and its proteolytic fragment, the F(ab')2 dimer, E2 and dihydrotestosterone (DHT) on CK specific activity in the epiphyseal cartilage, diaphyseal bone, uterus, prostate, thymus and pituitary of immature or gonadectomized female and male rat animal models. In the intact immature animals, clone 1D5 caused an increase in CK in all organs of the female except in the pituitary. In the diaphyseal bone and prostate of male rats there was no stimulation by 1D5. The CK response in the uterus, epiphysis, and diaphysis of immature female rats was dose-dependent and was blocked by either the anti-oestrogen tamoxifen or the F(ab')2 dimer of clone 1D5. E2, DHT, as well as clone 1D5, stimulated CK specific activity in both the diaphysis and epiphysis of ovariectomized female and castrated male rats, whereas sex specificity in the CK response was observed also in the uterus and the prostate of gonadectomized animals. Collectively, these results suggest that, as in cell culture, an intact antibody is necessary for the observed stimulation of CK specific activity and the F(ab')2 dimer can act as an antagonist. Furthermore, the observed biological effects of clone 1D5 which are absolutely parallel to E2, imply that the anti-idiotypic antibody is able to penetrate the cell and reach the nuclear oestrogen receptor and transduces a signal to the nucleus, by as yet uncharacterized mechanisms.

Animals↗
PubMed1996

Hyperestrogenemia and presence of estrogen receptors associated with an epithelial ovarian tumor of low malignant potential.

An 80-year-old woman presented with breast congestion, tenderness and pain. Mammography was normal. Circulating estradiol was markedly elevated, while LH and FSH were low. Pelvic examination and imaging revealed an ovarian mass which was extirpated during total abdominal hysterectomy and bilateral salpingo-oophorectomy. Histopathology revealed an ovarian mucinous cystadenocarcinoma of low malignant potential, stage 1. The tumor was positively stained for estrogen receptors. Estradiol levels returned to normal post-operatively, with a corresponding adjustment of LH/FSH. Possible autocrine steroid production is discussed.

Aged↗
PubMed1995

Complexity of the cytokine and antibody response elicited by immunizing mice with Plasmodium yoelii circumsporozoite protein plasmid DNA.

The number, type, and location of cytokine- and Ab-secreting cells activated in mice immunized and boosted with plasmid DNA encoding the circumsporozoite protein of the malarial parasite Plasmodium yoelii (PyCSP) were monitored. The initial humoral response was localized to the draining lymph nodes and was characterized by production of IgG1 anti-PyCSP Abs and the Th2 cytokine IL-4. In contrast, the secondary response was dominated by IFN-gamma production (a Th1 cytokine) and the secretion of IgG2a anti-PyCSP Abs in the spleen. PyCSP DNA and mRNA were detected only in the quadriceps muscles (sites of plasmid injection), yet these sites lacked either cytokine- or Ab-secreting cells. These findings indicate that circulating lymphocytes encounter plasmid-encoded Ag in the muscle bed, initiate a humoral response in the draining lymph nodes, and then seed distal lymphoid organs. Profound differences were observed between the primary and secondary immune responses induced by plasmid immunization, which may influence vaccine efficacy.

Animals↗
PubMed1995

Phenotype and frequency of cells secreting IL-2, IL-4, IL-6, IL-10, IFN and TNF-alpha in human peripheral blood.

The phenotype and frequency of cells in normal human peripheral blood spontaneously secreting IL-2, IL-4, IL-6, IL-10, IFN and TNF-alpha ex vivo was determined using ELIspot assays. CD4+ T cells were the dominant source of IL-2 and IL-4 while multiple cell types (primarily CD8+ lymphocytes) produced IFN. Fewer than 0.05% of mononuclear cells were spontaneously secreting these T cell derived factors. By comparison, IL-6, IL-10 and TNF-alpha were produced by 0.7-20% of PBMC. The primary sources of the latter cytokines were CD14+ macrophages/monocytes. A significant positive correlation was found in the frequency of cells secreting IL-6, IL-10 and TNF-alpha ex vivo, suggesting that the release of such factors was coordinately regulated. No such correlation was found among IL-2, IL-4 and IFN secreting cells, indicating that the production of predominantly T cell derived cytokines was regulated independently.

Antigens, CD↗
PubMed1995

Menopause is associated with a significant increase in blood monocyte number and a relative decrease in the expression of estrogen receptors in human peripheral monocytes.

PROBLEM: The clinical significance of the differential expression of estrogen receptor (ER) in human monocytes was evaluated. METHOD: Two color flow cytometry analysis was used on peripheral blood samples of young and postmenopausal females and postmenopausal females treated with estrogen replacement therapy. In addition, the monocyte and lymphocyte counts and the blood estrogen levels of each patient were determine. RESULTS: During menopause there is a significant decrease in the percentage of ER positive monocytes, and an increase in blood monocyte number, which declines following estrogen replacement therapy to values of the young. CONCLUSIONS: These findings suggest that estrogen modulates the monocyte numbers and its effects may be mediated through the ER in the monocytes.

Adolescent↗