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Biomedical subjects

A Afek

Publications and source records attributed to A Afek.

At least 19 recordsLinked to original sources
PubMed1999

Enhancement of atherosclerosis in beta-2-glycoprotein I-immunized apolipoprotein E-deficient mice.

We have previously shown that low density lipoprotein receptor-deficient (LDL-RD) mice immunized with beta2-glycoprotein I (beta2GPI; a target of autoimmune anticardiolipin antibodies) developed enhanced early atherosclerosis, when fed a normal chow diet. The current study was undertaken to evaluate the effect of immunization with beta2GPI and the addition of a high fat diet on the progression of atherosclerosis in the apolipoprotein E (ApoE)-deficient mouse. Six-week-old female ApoE-deficient mice (n = 10) were immunized subcutaneously with either human beta2GPI or with ovalbumin, both emulsified in complete Freund's adjuvant and fed a high fat diet for 6 weeks. The beta2GPI-immunized mice were found to develop accelerated atherosclerosis when compared with their ovalbumin-immunized littermates (aortic lesion area of 137,500 +/- 13,801 vs. 72,444 +/- 14,465 microm2, respectively; p = 0.0067). The beta2GPI-immunized mice developed high titers of anti-beta2GPI antibodies, 10 days after the procedure, which were sustained until the sacrifice. LDL extracted from both study groups displayed similar susceptibility to ex vivo oxidation. These results confirm our previous study in which we found increased atherosclerosis in beta2GPI-immunized LDL-RD mice fed a chow diet. In the current study we show that the proatherogenic effect of beta2GPI immunization is maintained despite high cholesterol levels and is not associated with increased susceptibility of LDL to ex vivo oxidation.

Animals↗
PubMed1999

A mouse model for heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) occurs in 1% to 3% of patients receiving heparin and results from the development of antibodies that recognize heparin-platelet factor 4 (H-PF4) complexes that form on the surface of activated platelets and on the vascular endothelium. With the aim of studying the pathogenic importance of these anti-H-PF4 antibodies in vivo, we attempted to create an animal model of HIT. Such a model was produced by immunization of naive mice with affinity-purified IgG anti-H-PF4 antibodies from two patients with HIT. The immunized mice developed specific antibodies (anti-idiotypic) against the human anti-H-PF4 antibodies and 2 months later, anti-anti-idiotypic antibodies appeared, which functionally resembled the human HIT antibody. Indeed, when the animals bearing anti-anti-idiotypic antibodies were injected with heparin for 4 days, a significant decrease in their platelet counts was observed; however, heparin treatment was not associated with thrombosis in any of the immunized mice. Similar to the observation in HIT patients, injections of equivalent doses of low-molecular-weight (LMW) heparin to the immunized animals did not induce thrombocytopenia. The results of this study support the importance of anti-H-PF4 antibodies in the pathogenesis of HIT. The mouse HIT model may provide a convenient system for studies on the immunoregulation of anti-H-PF4 expression and for evaluation of potential therapeutic modalities.

Animals↗
PubMed1998

Induction of early atherosclerosis in LDL-receptor-deficient mice immunized with beta2-glycoprotein I.

BACKGROUND: Immunization with beta2-glycoprotein I (beta2GPI), the probable target of autoimmune anticardiolipin antibodies, results in experimental antiphospholipid syndrome in different mouse strains. The present study was undertaken to evaluate the effect of beta2GPI immunization on the progression of atherosclerosis. METHODS AND RESULTS: In the first experiment, 3 groups of LDL receptor-deficient (LDL-RD) mice (n=15 per group) were immunized with either beta2GPI or ovalbumin or were not immunized and were fed a chow diet for 12 weeks. In a second experiment, 3 groups of LDL-RD mice (n=10 per group) were immunized similarly and fed an atherogenic diet for 6 weeks. All beta2GPI-immunized mice developed high titers of anti-beta2GPI antibodies as well as a specific lymph node proliferation to beta2GPI. The average cholesterol levels did not differ between the mice fed similar diets, regardless of the immunization protocol. Atherosclerosis was enhanced in the beta2GPI-immunized mice (mean aortic lesion, 26 000+/-5700 microm2) in comparison with their ovalbumin-immunized (mean, 3000+/-1099 microm2; P<0.01) and nonimmunized (mean, 2250+/-700 microm2; P<0.01) littermates. The average lesion size in the beta2GPI-immunized mice fed an atherogenic diet (mean, 98 000+/-8305 microm2) was larger than the ovalbumin-immunized mice (mean, 81 250+/-12 933 microm2; P=NS) or the nonimmunized controls (mean, 75 625+/-7281 microm2; P=NS). The atherosclerotic plaques in the beta2GPI-immunized mice appeared to be more mature, and denser infiltration of CD4 lymphocytes was present in the subendothelium of the aortic sinuses from this group of mice. CONCLUSIONS: The results of the present study provide the first direct evidence for the proatherogenic effect of ss2GPI immunization and establish a new model for immune-mediated atherosclerosis.

Animals↗
PubMed1998

Clinical characteristics of ruptured chordae tendineae in hospitalized patients: primary tear versus infective endocarditis.

BACKGROUND: Several etiologies have been associated with the rupture of chordae tendineae. The leading causes are infective endocarditis, primary rupture, and the association with various connective tissue disorders. HYPOTHESIS: In order to define the attributes of these patients, a retrospective study was conducted that investigated the medical files of hospitalized patients in the Sheba Medical Center, Tel-Hashomer, Israel. METHODS: Twenty patients (17 men, 3 women) with ruptured chordae were detected. Primary rupture of the chordae tendineae had been diagnosed in 11 patients, while infectious endocarditis was the cause for the tear of the chordae tendineae in 9 patients. The patients who had primary rupture of the chordae were older than the patients with endocarditis (67.4 +/- 11.3 vs. 57 +/- 9.3 years, respectively, p < 0.05). RESULTS: The posterior mitral valve cusp was more commonly involved (15 patients). Six of the patients with posterior mitral valve cusp involvement manifested atrial fibrillation. Mitral valve prolapse (MVP) was detected among seven patients, six of whom belonged to the group with infective endocarditis. CONCLUSION: Primary tear and infective endocarditis are leading etiologies of ruptured chordae tendineae in hospitalized patients. Particularly among the patients with infective endocarditis, concomitant MVP was frequently detected. It is the authors' opinion that this coexistence implies that MVP may predispose to the rupture of chordae tendineae.

Aged↗
PubMed1998

Hyperimmunization of apo-E-deficient mice with homologous malondialdehyde low-density lipoprotein suppresses early atherogenesis.

The role of the immune system in modulating atherosclerosis has recently been the subject of intensive research. Several previous authors have put forward a paradigm of the autoimmune process occurring in the vicinity of the plaque. Two recent studies have shown that immunization of rabbits with homologous modified low-density lipoprotein (LDL) led to suppression of atherosclerosis. In the current study we evaluated the effects of homologous malondialdehyde (MDA)-LDL immunizations on atherogenesis in apo-E-deficient mice. Two groups of female chow-diet-fed, apo-E-deficient mice (n = 10) were either immunized with homologous MDA-LDL or with phosphate buffer saline (PBS) at 2-week intervals. The mice were sacrificed 12 weeks following the primary immunization. The MDA-LDL-immunized mice were shown to develop high titers of anti-MDA-LDL antibodies. Atherosclerosis, determined by the lesion size at the aortic sinus, was significantly suppressed in the MDA-LDL-immunized mice as compared with their littermates immunized with PBS (mean area +/- S.D.; 74000 +/- 17300 microm2 versus 158000 +/- 12800 microm2; P < 0.01). No differences were found between the groups with respect to the cellular composition of the atherosclerotic plaques. The results of this study show that immunization with MDA-LDL has a protective effect in apo-E-deficient mice, and further suggests that this mouse model is suitable for studies of immunomodulation.

Animals↗
PubMed1998

Malignant thymoma associated with autoimmune diseases: a retrospective study and review of the literature.

OBJECTIVES: To determine whether malignant thymoma is associated with high rates of concomitantly occurring autoimmune diseases. METHODS: Sheba Medical Center computer records from 1966 to 1995 were reviewed to identify patients with malignant thymoma, either type I (invasive thymoma) or type II (thymic carcinoma). All patients who had malignant thymoma and autoimmune phenomena were analyzed. The diagnosis of thymic neoplasm was confirmed by two independent pathologists. The diagnosis of autoimmune diseases was based on both clinical and serological findings. RESULTS: Six of 22 (27%) cases of malignant thymoma had an autoimmune disease. Five patients had type I malignant thymoma and either myasthenia gravis (four patients) or Graves' disease (one patient). Only one patient had type II malignant thymoma with Sjögren's syndrome. The diagnosis of autoimmune disease preceded the diagnosis of thymic neoplasm in four cases, and was diagnosed simultaneously in two. CONCLUSIONS: Malignant thymomas are highly associated with autoimmune diseases, as are benign thymomas. To our knowledge, we report the first documented cases of a patient with thymic carcinoma and Sjögren's syndrome, and another with invasive thymoma and Graves' disease.

Adult↗
PubMed1998

Massive proteinuria as a main manifestation of primary antiphospholipid syndrome.

Renal involvement in antiphospholipid syndrome (APS) is increasingly reported. So far, massive proteinuria as the principal feature of primary APS (PAPS) has not been well documented. We describe 3 patients with PAPS and massive proteinuria. Renal biopsy was performed in all 3, and features consistent with membranous and focal segmental glomerulopathy were disclosed. These histological lesions were not yet reported in PAPS. We conclude that the spectrum of renal lesions in PAPS is diverse and that it should be considered in the differential diagnosis of patients with massive proteinuria.

Adult↗
PubMed1998

Dietary polyunsaturated fatty acids decrease anti-dsDNA and anti-cardiolipin antibodies production in idiotype induced mouse model of systemic lupus erythematosus.

OBJECTIVE: To examine the effect of diets with different polyunsaturated fatty acid contents, including linseed oil which contains 70% omega-3 fatty acids, on autoantibody production in idiotype induced mouse model of systemic lupus erythematosus (SLE). METHODS: Five different fats were fed to mice with induced SLE and antibody titers to anti-DNA and anti-cardiolipin were determined and histological examination of kidneys were carried out. RESULTS: SLE mice fed linseed oil showed lower titers of antibodies to DNA and to cardiolipin and less severe kidney damage than mice fed other diets, including fish oil. CONCLUSION: Use of linseed oil may attenuate the severity of SLE and this diet may be recommended for other auto-immune diseases as well.

Animals↗
PubMed1998

Immunomodulation of murine experimental SLE-like disease by interferon-gamma.

The objective of this study was to assess the impact of murine recombinant IFN-gamma and anti-IFN-gamma monoclonal antibody on the BALB/c mice experimental model of lupus. BALB/c female mice were immunized with a human anti-DNA antibody that carries the 16/6 idiotype. These mice were divided into several therapeutic groups according to different treatment strategies; injection with mouse recombinant IFN-gamma, anti-IFN-gamma mAb, phosphate-buffered saline (PBS), irrelevant mouse IgG and control groups that were neither treated nor immunized with the human anti-DNA antibody. The administration of IFN-gamma, intensified the degree of clinical, histological and serological parameters in this model of BALB/c murine lupus. This immunomanipulation decreased the mice longevity. All the laboratory parameters reflected acceleration of the disease in the IFN-gamma treated group as an elevated sedimentation rate, decreased white blood cell count and the development of massive proteinuria. One month after the boost injection, all the mice that were immunized with the anti-DNA antibody, developed high titers of autoantibodies; however, following an additional month, their levels declined in the IFN-gamma treated group. These findings were in concordance with an increased glomerular deposition of immune complexes in the IFN-gamma treated mice. IFN-gamma upregulated the levels of IL-4 and increased the number of IL-4 and IL-6 secreting splenocytes. In conclusion IFN-gamma administration can aggravate the clinical and laboratory outcome of 16/6 id induced lupus in BALB/c mice.

Animals↗
PubMed1997

Subcutaneous T-cell lymphoma in a patient with rheumatoid arthritis not treated with cytotoxic agents.

This case report describes an 81-year-old patient with prolonged rheumatoid arthritis (RA), which was complicated by the occurrence of a subcutaneous T-cell lymphoma. During the course of his illness the patient had not been treated with disease-modifying agents (i.e. cytotoxic agents), but only symptomatically with anti-inflammatory drugs. This finding demonstrates a previously undescribed association between RA and a rare from of subcutaneous T-cell lymphoma, which may add more information to the controversial issue of emergence of malignancy in RA.

Aged↗
PubMed1997

Pathogenicity of human anti-platelet factor 4 (PF4)/heparin in vivo: generation of mouse anti-PF4/heparin and induction of thrombocytopenia by heparin.

Heparin-induced thrombocytopenia/thrombosis (HIT) is a severe thrombotic disorder that occurs in approximately 1% of patients treated with heparin. Affected patients commonly develop antibodies that recognize PF4/heparin complexes that may form on the surface of activated platelets and on the endothelium. However, it has not been established that anti-PF4/heparin antibodies are responsible for the clinical manifestations of HIT. To address this issue, we employed a recently developed model of active immunity to study the effect of IgG anti-PF4/heparin antibody in vivo. In previous studies we have shown that it is possible to induce autoimmune diseases such as systemic lupus erythematosus (SLE), anti-phospholipid syndrome (APS) or vasculitis in naive mice by active immunization with anti-DNA, anti-cardiolipin and anti-neutrophil cytoplasmic antibodies, respectively. Immunized animals develop anti-idiotypic antibodies (Ab2) and, after 2-4 months, anti-anti-idiotypic antibodies (Ab3). Ab3s generated in this manner often simulate the binding activity of Ab1 and their expression correlates with the development of specific clinical manifestations typical of the respective human disease. Based on this experience, naive BALB/c mice were immunized with IgG anti-PF4/heparin antibodies isolated from two patients with HIT. The actively immunized mice developed mouse anti-PF4/heparin antibody (Ab3). Administration of unfractionated heparin, but not low molecular weight heparin (LMWH), to the actively immunized animals induced thrombocytopenia by day 4 of drug exposure. There was no evidence of thrombosis. The results of this study support the importance of anti-PF4/heparin antibodies in the pathogenesis of HIT. Further, this model may help to elucidate the factors responsible for thrombosis as well as providing means to assess new treatment options for patients with this disorder.

Animals↗
PubMed1997

Successful treatment of early secondary myelofibrosis in SLE with IVIG.

Myelofibrosis has been reported as a rare cause of pancytopenia in patients with autoimmune diseases. We describe a 54y old female patient who was admitted with severe anemia subsequently found to be due to marrow fibrosis. During the course of her hospitalization, relying both on her clinical symptoms as well as the results of a wide range of laboratory tests and diagnostic procedures, the diagnosis of systemic lupus erythematosus was established. The patient was treated with high dose steroids, but improvement of her clinical symptoms as well as normalization of her peripheral blood count were achieved only after high dose intravenous therapy with gamma globulin (IVIG) was instituted. Along with the improvement in the peripheral blood parameters normalization of the bone marrow architecture was recorded on a repeated bone marrow biopsy. IVIG therapy should be considered in extreme cases of bone marrow suppression in SLE.

Biopsy↗
PubMed1997

Atherosclerosis in LDL-receptor knockout mice is accelerated by immunization with anticardiolipin antibodies.

Atherosclerosis is a process initiated by accumulation of macrophages in distinct areas of endothelial cell damage and uptake of large amounts of lipids. Recently, it has been shown that the immune system plays an active part in the progression of the atherosclerotic plaque although its precise role has not yet been elucidated. Anticardiolipin antibodies (aCL) are generally found in the sera of patients with the antiphospholipid syndrome (APS) and are associated with a prothrombotic state. Several authors have demonstrated that aCL can activate platelets and endothelial cells as well as increase oxidized low density lipoprotein (LDL) uptake by macrophages. In the present study we sought to assess the effect of immunization with aCL (Ab1, leading to the production of mouse aCL-Ab3) on the progression of atherosclerosis. Two groups of 8-weeks old female LDL-receptor knockout mice (n = 13 per group) were immunized with IgG purified from the serum of an APS patient or with normal human IgG, respectively. The aCL immunized mice developed high titres of 'self' aCL (detected using the standard aCL ELISA) as compared with the normal human IgG immunized mice, whereas no differences were noted between both study groups with respect to the serum lipid levels. The extent of fatty streak formation was significantly higher in the aCL immunized mice in comparison with the human IgG injected mice (mean aortic lesion size of 5308 +/- 471 microns2 vs 1027 +/- 184 microns2, respectively, P < 0.01). The immunohistochemical analysis of the atherosclerotic plaques from both mouse groups did not display differences in cellular composition. The results of the study show that mouse aCL induced by immunization with human aCL from an APS patient enhance atherogenesis in LDL-RKO mice and imply that these antibodies may play a role in atherosclerosis development in patients with the APS.

Animals↗
PubMed1996

Pathogenic role of anti-endothelial cell antibodies in vasculitis. An idiotypic experimental model.

Idiotypic manipulation of naive mice has previously been used for induction of systemic autoimmune diseases (e.g., antiphospholipid syndrome, systemic lupus erythematosus, and Wegener's granulomatosis). The aim of this study focused on the utilization of this technique to induce the production of anti-endothelial cells Abs (AECA) and autoimmune vasculitis in a murine model. AECA were derived from a Wegener's granulomatosis patient's plasma. IgG was purified by absorption on a proteinase-3 affinity column resulting in the depletion of anti-neutrophil cytoplasmic Ab activity. The absorbed IgG fraction displayed a high titer of AECA as evidenced by a cyto-ELISA against unfixed human umbilical vein endothelial cells. BALB/c mice were actively immunized with the purified AECA. Three months after a boost injection with the human AECA, mice developed endogenous AECA (AB), but not Abs to proteinase-3, cardiolipin, or DNA. Histologic examination of lungs and kidneys revealed both lymphoid cell infiltration surrounding arterioles and venules; as well as deposition of Igs at the outer part of blood vessel walls. This experimental animal model of vasculitis, a product of our method of idiotypic manipulation, provides the first direct proof for the pathogenicity of AECA.

Animals↗
PubMed1996

Prenatal ultrasonographic diagnosis of fetal hepatic hyperechogenicities: clinical significance and implications for management.

The clinical significance of sonographically detected fetal hepatic hyperechogenicities has not been fully established. The aim of this study was to assess various aspects of fetal hepatic hyperechogenicities detected in utero, including natural history, prenatal investigation and pregnancy outcome. In a retrospective survey of pregnant women presenting to the ultrasonographic unit, five fetuses with a mean gestational age of 20 weeks (range 14-24 weeks) were antenatally diagnosed as having hepatic hyperechogenicities. All cases underwent extensive investigation to establish the etiology and to determine the spectrum of ultrasonographic presentation. In three fetuses, only parenchymal lesions were found, while two had combined lesions: parenchymal and peritoneal. The earliest prenatal ultrasonographic diagnosis was made at 14 weeks' gestation in a fetus with combined hyperechogenic lesions, which, at 12 weeks' gestation, demonstrated unexplained fetal ascites. Associated abnormalities were found in only one fetus in which a solitary parenchymal lesion was associated with direct communication of the intrahepatic portion of the umbilical vein with the right atrium, and high output cardiac failure. In this case, termination of pregnancy confirmed ischemic hepatic necrosis. In the other four cases, no direct etiology could be determined, and all four pregnancies continued to term with normal neonatal follow up until 12 months of age. The present data suggest that in cases of fetal hepatic hyperechogenicities, where apparent intrauterine infection or neoplasia can be ruled out, a vascular disruption phenomenon is a putative etiology. If there are no associated morphological abnormalities or abnormal karyotypes, the prognosis may be favorable.

Adult↗