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Biomedical subjects

S Michalak

Publications and source records attributed to S Michalak.

At least 19 recordsLinked to original sources
PubMed2001

The effect of short-term treatment with interferon beta 1a on acute experimental allergic encephalomyelitis.

The clinical and histological picture and immunocytochemical expression of some cytokines on infiltrates in the central nervous system of Lewis rats were studied in adult rats in the course of short-term therapy of acute experimental allergic encephalomyelitis with interferon beta 1a (IFN beta 1a). There was established the beneficial effect of the short-term treatment of EAE with IFN beta 1a, applied at the early onset of the experimental disease. The effect of IFN beta 1a on EAE seems likely to be associated with the inhibition of proinflammatory cytokines and stimulation of anti-inflammatory ones.

Acute Disease↗
PubMed2000

Mouse alpha-fetoprotein-specific DNA-based immunotherapy of hepatocellular carcinoma leads to tumor regression in mice.

BACKGROUND & AIMS: alpha-Fetoprotein (AFP) is a tumor-associated protein that is frequently expressed at high levels in hepatocellular carcinoma (HCC). The aim of the study was to characterize self-reactive cytotoxic T lymphocytes (CTLs) directed against murine AFP (mAFP) after DNA-based immunization in mice. METHODS: To study CTL responses, mAFP-expressing recombinant vaccinia viruses were generated. An HCC tumor model was established in C57L/J mice by injection of syngeneic endogenously mAFP-expressing Hepa1-6 cells. RESULTS: Gene gun and intramuscular coimmunizations of DNA expression vectors encoding mAFP with plasmids encoding murine interleukin (IL)-12, granulocyte-macrophage colony-stimulating factor, or IL-18 induced weak CTL activity against mAFP in different mouse strains. Some mice developed anti-mAFP antibody responses, suggesting breaking of immunologic ignorance. No hepatocyte damage was detectable despite low-level endogenous hepatic mAFP expression. Therapeutic immunizations of mice bearing mAFP-expressing murine HCCs induced partial regression of tumors. A significant survival benefit was observed in mice immunized with mAFP expression vector DNA but not in untreated mice or in mice immunized with mock/cytokine plasmid DNA. CONCLUSIONS: The data show that AFP may be used as a potential self tumor antigen to induce CTL and CD4(+) T cell-mediated regression of AFP-expressing HCC by DNA-based immunization.

Alanine Transaminase↗
PubMed2000

[Osseous leiomyosarcoma of the mandible. Case report and review of the literature].

Primary leiomyosarcoma localized in the mandibular bone is exceptional. We report a case with active intraosseous development and review eight other cases in the literature. The clinical signs at discovery were nonspecific. Radiological imaging showed osteolysis with no periosteal reaction. MRI was required to study extension to soft tissues and was useful for guiding wide excision. The risk is dominated by distant metastasis rather than locoregional extension. The histological diagnosis is difficult and requires an immunohistochemistry study. No therapeutic consensus has been established.

Adult↗
PubMed2000

The effect of moderate hypoxia on free sterols: content and pattern in white matter.

Wistar rats underwent moderate hypoxia by exposing them to a respiratory gas mixture containing 7% oxygen, for 30 min. The myelin was analyzed at 4 h 24 h, day 14, and day 60 after hypoxia. The group of neutral lipids isolated from myelin was analyzed by GC-MS (gas chromatography-mass spectrometry) to separate and measure free sterols. In the myelin of hypoxia treated animals the pattern of free sterols was variable. Cholesterol concentration decreased with the changes in the content and composition of sterols present in smaller amounts. These changes may indicate the disturbances in some steps of cholesterol biosynthesis and metabolism in pathologic conditions. The appearance of sterols characteristic for plants (beta-sitosterol) was noticed in myelin of experimental animals. The possible reason for the presence of this sterol in animals may be the result of its intake during feeding, however, biosynthesis can not be excluded.

Animals↗
PubMed1999

Human non-germinal center B cell interleukin (IL)-12 production is primarily regulated by T cell signals CD40 ligand, interferon gamma, and IL-10: role of B cells in the maintenance of T cell responses.

Interleukin (IL)-12 is expressed mainly in antigen-presenting cells after challenge with microbial material or after CD40 activation. Although IL-12 was cloned from human Epstein-Barr virus (EBV)-transformed B cell lines, surprisingly, CD40 ligation on murine B cells did not lead to IL-12 production, suggesting that murine B cells do not produce IL-12. Here we demonstrate that a subset of human tonsillar B cells can be induced to express and secrete bioactive IL-12. The major stimulus to produce IL-12 in human B cells was CD40 ligation. In contrast, B cell receptor cross-linking did not induce IL-12. Expression of IL-12 after CD40 activation was restricted to CD38(-)IgD+/- non-germinal center (non-GC) B cells. CD40 ligation and interferon (IFN)-gamma exhibited synergistic effects on IL-12 production, whereas IL-10 abrogated and IL-4 significantly inhibited IL-12 production by these B cells. In contrast to IL-12, production of IL-6 is conversely regulated, leading to significant increase after CD40 ligation in the presence of the T helper type 2 (Th2) cytokine IL-4. Cord blood T cells skewed towards either a Th1 or a Th2 phenotype maintained their cytokine expression pattern when restimulated with allogeneic resting B cells. Blockade of CD40 and/or IL-12 during T-B interaction significantly reduced IFN-gamma production by the T cells. This suggests a model whereby B cells produce either IL-12 or IL-6 after contact with T cells previously differentiated towards Th1 or Th2. Furthermore, IL-12 and IL-6 might provide a positive feedback during cognate T-B interactions, thereby maintaining T cells' differentiation pattern during amplification of the immune response.

Antigen-Presenting Cells↗
PubMed1999

Herpetic salpingitis and fallopian tube prolapse.

AIM: We describe the unusual association of fallopian tubal prolapse and herpetic infection, an occurrence not previously reported to our knowledge. METHODS AND RESULTS: A 37-year-old woman presented with a small polypoid mass of the vaginal vault, 3 months after abdominal hysterectomy and abdominoplasty. The vaginal mass proved to be the fimbriated end of a fallopian tube, herniated into the vagina. Reintervention 3 months later with resection of a small vaginal 'polyp' revealed a residual portion of fallopian tube, with superimposed herpes simplex virus (HSV) infection and marked cytological atypia of surface epithelial cells. HSV-2 immunostaining of viral nuclear inclusions and of atypical cells confirmed the herpetic nature of the infection. CONCLUSION: Involvement of the genito-urinary tract by HSV may occur via an ascending infection from the cervix, but the fallopian tube, deeply located in the pelvis, is generally spared from herpetic infection. In the setting of fallopian tubal prolapse, direct exposure of the herniated fallopian tube to various pathogens in the vagina provides an unique clinical model for salpingitis. In herpetic tubal infections, special attention must be paid to cytological atypia of probable viral cytopathogenic origin, to avoid a misdiagnosis of malignancy.

Adult↗
PubMed1999

Intracellular retention of hepatitis B virus surface proteins reduces interleukin-2 augmentation after genetic immunizations.

We have previously shown that hepatitis B virus (HBV) surface antigens (HBsAgs) are highly immunogenic after genetic immunization. Compared to the secreted middle HBV surface proteins (MHBs) or small HBV surface proteins (SHBs), the nonsecreted large HBV surface protein (LHBs), however, induced significantly weaker humoral and cellular immune responses that could not be augmented by genetic coimmunizations with cytokine expression plasmids. In order to understand the mechanisms underlying this phenomenon, we examined the effect of coimmunizations with an interleukin-2 (IL-2) DNA expression plasmid on the immunogenicity at the B- and T-cell level of nonsecreted wild-type LHBs, a secreted mutant LHBs, wild-type SHBs, and a nonsecreted mutant SHBs. Coimmunizations of mice with plasmids encoding wild-type SHBs or the secreted mutant LHBs and IL-2 increased anti-HBs responses, helper T-cell proliferative activity and cytotoxic T-lymphocyte killing. By contrast, coimmunizations of plasmids encoding wild-type LHBs or nonsecreted mutant SHBs and IL-2 had no significant effects on immune responses. Interestingly, mice immunized with cytokine expression plasmids 14 days after the injection of the wild-type LHBs plasmid showed augmented immune responses compared to animals simultaneously injected with both expression constructs. Anti-HBs responses in mice injected with plasmids encoding secreted forms of HBsAgs were detectable about 10 days earlier than those in mice immunized with plasmids encoding nonsecreted forms of HBsAgs. Based on these observations, we conclude that cytokines produced by DNA plasmids at the initial site of antigen presentation cannot augment LHBs specific immune responses because LHBs is not produced at high enough levels or is not accessible for uptake by antigen-presenting cells.

Animals↗
PubMed1999

[Intraneural perineurioma: an unusual nerve sheath tumor].

We report a case of intraneural perineurioma, developed in the left cubital nerve, in a five-year old girl. This intraneural tumor is rare and shows a typical histologic appearance: concentric whorls of perineurial cells EMA+, PS100-, around nerve fibers. This tumor must be distinguished from extraneural or soft tissue perineurioma, also composed of perineurial cells, with distinct clinical presentation and histological appearance.

Child, Preschool↗
PubMed1998

Immunopathological mechanisms underlying the time-course of Trichinella spiralis cardiomyopathy in rats.

The present study shows that isolated, perfused hearts from rats orally infected with Trichinella spiralis have a reduced left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). This reduction is considerably enhanced by a single bolus (100 pM) of PAF (platelet activating factor, an eosinophil activator), especially at 21 days post-infection (d.p.i.), which is the time of the maximum increase in blood and tissue eosinophilia. Helminthic DNA analysis shows that, from 21 d.p.i. onwards, the morphological and functional changes in the myocardium cannot be ascribed to the parasite's presence, whereas its antigens and the attendant immunopathological reactions might have a role in the induction of myocardial damage and dysfunction. Some perivascular inflammatory cells (eosinophils and mast cells) appear to undergo degranulation. All these data suggest a complex sequence of events, from acute myocarditis (21 d.p.i.) which may lead in time (48 d.p.i. onwards) to a dilating cardiomyopathy.

Animals↗
PubMed1998

[Bladder paraganglioma (pheochromocytoma): a rare tumor in children. Apropos of a case].

The authors report the first case of bladder paraganglioma in a child admitted to their department successfully treated by partial cystectomy. The diagnosis was established histologically, after failure of clinical diagnosis. Retrospectively' the authors think that preoperative diagnosis should have been possible and emphasize the importance of a thorough clinical examination.

Child↗
PubMed1997

CD40-activated human B cells: an alternative source of highly efficient antigen presenting cells to generate autologous antigen-specific T cells for adoptive immunotherapy.

Multiple clinical trials have shown the efficacy of adoptively transferred allogeneic antigen-specific T cells for the treatment of viral infections and relapsed hematologic malignancies. In contrast, the therapeutic potential of autologous antigen-specific T cells has yet to be established since it has been technically difficult to generate sufficient numbers of these T cells, ex vivo. A major obstacle to the success of this objective derives from our inability to simply and rapidly isolate and/or expand large numbers of highly efficient antigen presenting cells (APCs) for repetitive stimulations of antigen-specific T cells in vitro. We show that autologous CD40-activated B cells represent a readily available source of highly efficient APC that appear to have several important advantages over other APCs for ex vivo T cell expansion including: (a) methodological simplicity necessary to generate continuously large numbers of APCs from just 50 cm3 of peripheral blood without loss of APC function; (b) capacity to induce high peak T cell proliferation and interferon-gamma production without IL-10 production; (c) ease in cryopreservation; and (d) markedly reduced cost. We, therefore, contend that CD40-activated B cells are an alternative source of highly efficient APCs with which to generate antigen-specific T cells ex vivo for autologous adoptive immunotherapy.

3T3 Cells↗
PubMed1997

In vivo expression of B7-1 and B7-2 by follicular lymphoma cells can prevent induction of T-cell anergy but is insufficient to induce significant T-cell proliferation.

Expression of B7 family costimulatory molecules on B cells defines their capacity to function as antigen presenting cells (APCs). B cells that do not express B7 costimulatory molecules induce T-cell tolerance. Therefore, the expression of B7 costimulatory molecules on malignant B cells might be critical for their recognition by anti-tumor-specific T cells. Here we show that virtually all germinal center (GC)-derived B-cell lymphomas including follicular lymphoma (FL) and diffuse large cell lymphoma, but not mantle cell lymphoma or small lymphocytic lymphomas (SLL/CLL), express B7-1 (CD80) and B7-2 (CD86) on their cell surface in situ, although at extremely low levels. Despite their expression of low levels of B7-1 and B7-2, FL cells could not induce significant allogeneic T-cell proliferation. However, B7 costimulatory molecules on FL appeared to be functional because they were capable of increasing T-cell proliferation of preactivated T cells in a secondary allogeneic mixed lymphocyte response. Moreover, low B7 expression was sufficient to prevent the induction of alloantigen-specific anergy in vitro. Therefore, we postulate that whereas low-level expression of B7 is not sufficient to initiate a productive antilymphoma T-cell response, it might be sufficient to prevent T-cell tolerance in vivo.

Antigens, CD↗
PubMed1997

Autologous tumor infiltrating T cells cytotoxic for follicular lymphoma cells can be expanded in vitro.

Follicular lymphomas (FLs) rarely induce clinically significant T-cell-mediated responses. We showed that freshly isolated tumor infiltrating T cells (T-TILs) lack tumor-specific cytotoxicity. Stimulation of these T cells with FL cells in the presence of interleukin-2 (IL-2) and/or costimulation via CD28 does not lead to T-cell activation and expansion. In contrast, when stimulated with FL cells preactivated via CD40, autologous T-TILs can be expanded by the addition of exogenous IL-2. These T cells can be further expanded in vitro by the addition of exogenous IL-4, IL-7, or interferon-gamma, but not IL-12. Once activated, these T cells showed FL-directed cytotoxicity in four of five patients tested. We concluded that autologous cytotoxic anti-FL-specific T cells exist, but can only be detected in vitro under optimized conditions for T-cell stimulation and expansion. This suggests that their frequency in vivo is either very low or that the microenvironment does not provide the necessary signals to activate these T cells. This model system allows dissection of the requisite conditions for activation and expansion of lymphoma-directed cytotoxicity and may permit expansion of previously activated cytotoxic T cells for adoptive transfer.

B-Lymphocytes↗
PubMed1997

[Paraneoplastic encephalomyeloneuritis with anti-Hu antibodies and cancer of the rectum].

We report the case of a 62-year-old man affected by anti-Hu-associated paraneoplastic encephalomyelitis. The underlying tumor was a neuroendocrine cancer of the rectum expressing Hu antigen. The neurologic presentation was limited to moderate sensitive neuropathy associated with two complex partial seizures (dreamy state) without any further signs of limbic encephalopathy. A paraneoplastic etiology should be considered in patients with moderate symptomatology. Paraneoplastic encephalomyelitis with anti-Hu antibodies is not always associated with small-cell lung cancer.

Antibodies↗
PubMed1997

[Adenoid basal carcinoma and adenoid cystic carcinoma of the uterine cervix].

Adenoid basal carcinoma and adenoid cystic carcinoma are rare primary cervical neoplasms occurring in postmenopausal women. They are generally regarded as distinct entities on the basis of their distinctive morphology and a different biological behaviour. Although the separation of these two entities is still mandatory, some rare complex cases may show overlapping pathological features and are difficult to classify. We report a case of composite cervical tumor with both types of carcinoma, an in situ epidermoid carcinoma and a hitherto undescribed clear cell component, each with a different morphology and immunophenotype. The adenoid basal component is mainly immunoreactive for cytokeratin KL1. The adenoid cystic component is strongly stained for smooth muscle actin and is associated with a hyaline stroma immunostained for collagen IV.

Adenocarcinoma, Clear Cell↗