Showing papers by "University of Ioannina published in 1992"

Magnetic properties of ultrafine iron particles.

Abstract: The magnetic and morphological properties of fine Fe particles have been studied. Ultrafine particles of Fe were prepared using a vapor deposition technique under an argon atmosphere. The argon pressure was varied from 0.5 to 8 Torr during evaporation, and samples with a median diameter in the range 50--200 \AA{} were obtained having a log-normal distribution. The dependence of magnetic properties on particle size and temperature (10 KT300 K) were studied using superconducting-quantum-interference-device magnetometry and M\"ossbauer spectroscopy. Samples with particle diameter below 90 \AA{} showed a superparamagnetic behavior below room temperature. The saturation magnetization of the particles varied from 25 to 190 emu/g, with the higher values corresponding to larger particles. For these larger particles, a coercivity of 1.05 kOe was obtained at room temperature. The magnetic and structural data suggested a core-shell type of structure, where the core consists of metallic Fe and the shell is composed of Fe oxides.

Clear evidence that long-term, low-dose tamoxifen treatment can induce ocular toxicity. A prospective study of 63 patients.

Abstract: The current study has prospectively investigated the incidence and course of ocular toxicity after low-dose tamoxifen treatment. Sixty-three patients with cancer who could be examined were analyzed. Tamoxifen was administered on a 20-mg daily dose. Median duration of treatment was 25 months. Median total tamoxifen dose was 14.4 gr. Four patients had retinopathy and/or kera-topathy 10, 27, 31, and 35 months, respectively, after tamoxifen initiation (an incidence of 6.3%). Ophthalmo-logic findings consisted of decreased visual acuity, bilateral macular edema, yellow-white dots in the para-macular and fovea areas in all patients as well as corneal opacities in one patient. After tamoxifen withdrawal almost all ocular abnormalities were found to be reversible, except for the retinal opacities. This is the first prospective study in the literature indicating that even conventional low-dose tamoxifen treatment can induce ocular toxicity. In addition, the authors review and discuss the literature of the last decades.

Rheumatoid arthritis in Greek and British patients. A comparative clinical, radiologic, and serologic study.

Abstract: OBJECTIVE To compare the clinical, radiologic, and serologic expression of rheumatoid arthritis (RA) in 2 different populations. METHODS Standard protocols and assessment criteria were used in this study of 108 Greek and 107 British patients with RA. RESULTS British patients had more severe articular involvement than did Greeks, as judged by the duration of morning stiffness (P less than 0.005), grip strength (P less than 0.0001), and the numbers of swollen (P less than 0.001) and tender (P less than 0.0001) joints. The British RA patients also had more severe joint damage on radiologic examination, as evidenced by Steinbrocker stage III (P less than 0.005) and IV (P less than 0.025) disease and had more extraarticular manifestations (P less than 0.0001), including rheumatoid nodules (P less than 0.0001) and Raynaud's phenomenon (P less than 0.05). Greek RA patients, however, more frequently presented with sicca manifestations (P less than 0.001) and serum antibodies to Ro/SS-A (P less than 0.025). Furthermore, Ro/SS-A antibodies were associated with a high incidence of side effects to D-penicillamine only in the Greeks. CONCLUSION Genetic and environmental factors may be responsible for these striking differences in disease expression between these 2 European populations with RA.

HLA Class ii sequence polymorphisms and susceptibility to rheumatoid arthritis in greeks. the hla–drβ shared‐epitope hypothesis accounts for the disease in only a minority of greek patients

Abstract: Objective. In Northern Europeans, rheumatoid arthritis (RA) is strongly associated with a relatively conserved pentapeptide sequence of HLA–DRβ found notably in the HLA–DR4 subtypes Dw4 and Dw14 and in DR1. A previous serologic study of HLA class II polymorphism in a Greek population with RA failed to show significant associations with any antigen. Methods. We characterized HLA–DRB polymorphisms in Greek patients with RA and in control subjects by restriction fragment length polymorphism analysis. Allelic DRB subtypes were examined by polymerase chain reaction amplification and oligonucleotide hybridization. Results. DNA analysis in the RA patients showed that although individual HLA–DR allelic associations were weak, a relatively conserved HLA–DRβ motif was significantly associated with RA in this population of Greek patients. The third hypervariable region amino acid sequences QRRAA, QKRAA, or RRRAA were found in the HLA–DRβ1 of 43.5% of the RA patients versus 15.5% of the controls (unconnected P = 0.00004). Conclusion. Sequences shown to influence susceptibility to RA in patients in the UK also play a role in patients in Greece. However, 57% of Greek patients lack the putative HLA–DRβ motif, which suggests that considerable immunogenetic heterogeneity underlies disease susceptibility in this population.

Global attractivity in nicholson's blowflies

Abstract: We established sufficient conditions for the global attractivity of the positive equilibrium of the delay differential equation [Ndot](t) ≡ −δN(t) + PN(t–τ)e−aN(t–τ) which was used by Gurney, Blythe and Nisbet [1] in describing the dynamics of Nicholson's blowflies

Pulmonary and gastrointestinal manifestations of Sjögren's syndrome

Abstract: The respiratory system is frequently involved in primary SS but this involvement is rarely clinically significant. Its manifestations are secondary to desiccation of the tracheobronchial tree and lymphocytic infiltration of the lung parenchyma. The desiccation of the tracheobronchial tree gives rise to the most important clinical manifestation, dry cough (xerotrachea), but is rarely a cause of infection and obstructive airways disease. The lymphocytic infiltration of the lung parenchyma starts as lymphocytic alveolitis in a very large number of SS patients but rarely evolves into frank lymphocytic interstitial pneumonitis and fibrosis. Even more rare is the evolution of pseudolymphoma into malignant lymphoma. Pleurisy with or without effusion is not a frequent manifestation of primary SS. It occurs often in secondary SS and is due to the underlying rheumatic disorder. In general, secondary SS rarely has significant pulmonary manifestations other than those of the disorder it accompanies. The manifestations from the gastrointestinal system in patients with SS include mucosal dryness, accelerated dental decay, and enlargement of the major salivary glands, as well as dysphagia, nausea, epigastric pain, and dyspepsia. The dysphagia is probably secondary to esophageal dysfunction, and the gastric symptoms might be attributable to chronic atrophic gastritis. Whether the small bowel is affected in SS patients is not clear. Pancreatic involvement usually is being expressed as subclinical acute or chronic pancreatitis. Finally, the liver could be involved in SS patients, and some studies indicate that the pathogenic process responsible for the hepatic damage and for the salivary gland destruction could be similar.

Lymphoma in Sjogren's syndrome.

Abstract: Sjogren's syndrome is an autoimmune disease with a known predisposition for lymphoma development. Eight of 120 patients with primary Sjogren's syndrome followed at the University of Ioannina over the past 7 years developed non-Hodgkin's lymphoma diagnosed according to the Kiel classification. The lymphomas differed by location and grading. Six were called low grade (immunocytoma) and two intermediate grade non-Hodgkin's lymphomas. Five of the immunocytomas involved the minor salivary or lacrimal glands. Immunoperoxidase staining for light chains revealed monoclonal populations. Two patients showed spontaneous regression not previously reported in Sjogren's syndrome. Thus, in Sjogren's syndrome, low grade non-Hodgkin's lymphomas and especially immunocytomas are the most common lymphomas. These lymphomas tend to evolve very slowly and may regress spontaneously. Given these facts, a conservative approach to treatment is indicated in those patients with only localized disease.

Tin in pharmacy and nutrition

Abstract: The occurrence of tin in plants, animals and humans is discussed in relation to its abundance in the lithosphere and hydrosphere and the range of different tin(II) and tin(IV) complexes formed. A reasoned consideration of the essentiality or otherwise of tin for living species is given and it is concluded that tin is beneficial even if not yet proved to be an essential element. After reference to the chemistry of tin compounds, there is a detailed discussion of their toxicity in animals and humans. Feasible routes for tin intake and uptake into humans are described. The use of tin pharmaceuticals in previous and current times is reviewed and areas for which they are currently permitted for use in man as dentifrices and mouth washes, as radiopharmaceuticals and for the treatment of jaundiced newborns are described. A detailed review of tin-coating antitumour agents as representative tin pharmaceuticals is given. Finally, a range of tin compounds having other specific pharmaceutical applications and which are currently being investigated are listed.

Stable steady state of some population models

Abstract: Applying an analytical method and several limiting equations arguments, some sufficient conditions are provided for the existence of a unique positive equilibriumK for the delay differential equationx=−γx+D(xt), which is the general form of many population models. The results are concerned with the global attractivity, uniform stability, and uniform asymptotic stability ofK. Application of the results to some known population models, which shows the effectiveness of the methods applied here, is also presented.

Antimitochondrial (pyruvate dehydrogenase) autoantibodies in autoimmune rheumatic diseases.

Abstract: Anti-pyruvate dehydrogenase (PDH) antibodies were determined in 1451 sera of patients with primary biliary cirrhosis (PBC) and several autoimmune rheumatic conditions by ELISA and immunoblotting. They were detected in sera of 93% of the patients with PBC (179 of 192 patients) in 60 of 277 (22%) patients with Sjogren's syndrome (SjS), 34 of 437 (8%) patients with scleroderma, 33 of 191 patients with SLE (17%), and 5 of 55 (10%) patients with rheumatoid arthritis (RA) but in none of the patients with polymyositis or the antiphospholipid syndrome. The ELISA studies were confirmed by immunoblots showing binding of autoimmune rheumatic sera to the same epitope (74 kd) of mitochondria that the PBC sera reacted with. The identical binding characteristics were also confirmed by protein competition assays with purified PDH. In 4 of 53 patients with SjS who were positive for anti-PDH, high titers as in PBC were detected. The anti-PDH antibodies in Sjogren's patients were associated with deranged liver function tests and extraglandular features but did not correlate with any other non-organ-specific antibody. Follow-up studies confirmed the association of the emergence of anti-PDH antibodies with defects in liver function tests. The antibodies were more prevalent in SLE and RA when they were associated with Sjogren's syndrome (30 and 18.8%, respectively). Among patients with different forms of scleroderma, anti-PDH antibodies were noted in subjects with systemic sclerosis, morphea, and Raynaud's phenomenon. The incidence was much more significant among patients with calcinosis, Raynaud's, esophageal dysmotility, sclerosis, and telangiectasia (CREST) (8/34), in whom antibodies were detected in 5 who had already developed PBC. The relationship among anti-PDH antibodies, PBC, and development of other autoimmune rheumatic conditions is discussed. It is proposed that the early detection of anti-PDH antibodies in patients with rheumatic conditions may predict the future development of PBC. This observation may have therapeutic implications.

uPA/uPAR downregulation inhibits radiation-induced migration, invasion and angiogenesis in IOMM-Lee meningioma cells and decreases tumor growth in vivo.

Abstract: Meningioma is a well-known tumor of the central nervous system, and is treated by surgical resection and/or radiation. Recently, ionizing radiation has been shown to enhance invasiveness of surviving tumor cells, and several proteolytic enzyme molecules, including urokinase plasminogen activator (uPA), seem to be upregulated after radiation. uPA and its receptor (uPAR) have been strongly implicated in tumor invasion, angiogenesis and progression. Hence, the tumor-associated uPA-uPAR system is considered a potential target for cancer therapy. In the present study, we show that radiation increases uPA levels in the IOMM-Lee meningioma cells, and subsequently, increases tumor invasion, migration and angiogenesis in vitro. Studies with signaling molecule inhibitors AG1478, U0126 and SB203580 (specific inhibitors of EGFR, MEK1/2 and p38 respectively) showed inhibition of uPA levels in both basal and irradiated-IOMM-Lee cells. The PI3K inhibitor (LY294002) and the AKT inhibitor (AKT inhibitor IV) also partially decreased uPA expression, whereas SP600125, a JNK inhibitor, did not affect uPA levels in either radiated or non-radiated cells. Further, a bicistronic plasmid construct with small interfering RNA (siRNA) against uPA and its receptor inhibited tumor invasion, migration and angiogenesis in radiation-treated IOMM-Lee cells. In addition, siRNA against uPA and its receptor inhibited subcutaneous tumor growth in athymic nude mice in combination with radiation in a synergistic manner. Thus, the specific targeting of proteases via RNA interference could augment the therapeutic effect of radiation and prevent the adverse effects resulting from tumor cells that receive sublethal doses of radiation within the tumor mass.

Renal tubular acidosis in primary Sjögren's syndrome

Abstract: Renal tubular acidosis (RTA) is a frequent extraglandular manifestation of Sjogren's syndrome; however, no distinction on the incidence of this renal tubular defect between primary and secondary Sjogren's syndrome has been reported. This study was undertaken in order to define the frequency of RTA and the possible pathogenetic mechanisms in a group of 21 randomly selected primary Sjogren's syndrome patients. RTA was found in 7 (33%) patients. The incomplete type of the disorder was the most frequent. It seems that the etiology of RTA is multifactorial. Renal excretion of monoclonal proteins and the immunologically-induced interstitial inflammation are the main possible factors of this renal tubular defect.

Effects of substitution in perovskites La2−xSrxNiO4−λ on their catalytic action for the nitric oxide+carbon monoxide reaction

Abstract: The catalytic activity of the perovskite series La 2− x Sr x NiO 4−γ ( x = 0.00, 0.25, 0.50, 0.75, 1.00, 1.25 and 1.50) has been studied for the reduction of nitric oxide by carbon monoxide in equimolecular mixture. The conversion ( X %) of reactants approaches the value X NO / X CO = 2 at low temperatures and low degree of substitution of lanthanum by strontium but tends to unity at high temperatures and high degree of substitution. This behaviour is due to the change of the rate determining step of the reaction which at low temperature is the oxygen formation through decomposition of nitric oxide while at high temperatures it is the reaction between the adsorbed oxygen species and carbon monoxide. The apparent activation energies for the nitric oxide elimination drop with the process of substitution from x = 0.00 to x = 1.00 and increase thereafter. The controlling factor of the catalytic activity of the series seems to be the strength of adsorption of oxygen on the perovskite surface. Thus it is shown that the sum of the enthalpies of the metal-oxygen bonds in the material is closely related to the temperature where reaction switches mechanism. Besides, the differential mean electronegativity of the solids is related both to the reaction rate as well as to the apparent activation energy for nitric oxide reduction.

Ruled surfaces with vanishing second Gaussian curvature

Abstract: For a surface free of points of vanishing Gaussian curvature in Euclidean space the second Gaussian curvature is defined formally. It is first pointed out that a minimal surface has vanishing second Gaussian curvature but that a surface with vanishing second Gaussian curvature need not be minimal. Ruled surfaces for which a linear combination of the second Gaussian curvature and the mean curvature is constant along the rulings are then studied. In particular the only ruled surface in Euclidean space with vanishing second Gaussian curvature is a piece of a helicoid.

Serum-soluble interleukin-2 receptors in B-cell lymphoproliferative malignancies.

Abstract: The levels of soluble interleukin-2 receptors (sIL-2R) were determined in the serum of 53 patients with B-cell lymphoproliferative malignancies, including 31 patients with non-Hodgkin lymphomas (NHL), 16 with chronic lymphocytic leukemia (CLL), and 6 with multiple myeloma. In addition, serum samples from 40 patients with various solid tumors as well as from 53 healthy individuals were used as controls. It was found that the mean serum levels of sIL-2R were significantly increased (P less than 0.001) in NHL (mean +/- standard error of the mean 2,327 +/- 320 units/ml) and CLL patients (2517 +/- 451 units/ml) as compared to normal controls (207 +/- 17 units/ml). No such difference was observed when the serum sIL-2R levels of patients with multiple myeloma or solid tumors were analyzed. Serum sIL-2R levels were closely related to the clinical stage, the presence of B-symptoms, and the disease activity of patients with NHL and CLL. In fact, response to chemotherapy was followed by marked decrease or normalization of sIL-2R levels, while in a number of patients sIL-2R values were even able to predict disease relapse. Finally, no association with histologic grade in NHL patients, could be demonstrated. We conclude that serum sIL-2R (1) are increased only in B-NHL and B-CLL but not in myeloma patients, (2) are related to the tumor burden, and (3) can serve as a valuable tumor marker for the monitoring of patients treatment.

Patients with anticardiolipin antibodies with and without antiphospholipid syndrome: their clinical features and β2‐glycoprotein‐l plasma levels

Abstract: The clinical and serological features of 38 aCL-positive patients were compared to those of 45 aCL-negative patients. A significantly higher incidence of thrombophlebitis and livedo reticularis was found in aCL-positive patients. There were 13 aCL positive patients with thrombophlebitis and/or arterial thromboses and these 13 patients were designated as having the antiphospholipid syndrome (APS) while the remaining 70 patients were diagnosed as having Systemic Lupus Erythematosus (SLE). APS patients also had a high incidence of arterial occlusions, recurrent abortions and strokes compared to SLE patients. Patients with high levels of IgG-aCL were more likely to have APS, while patients with low levels of IgG-aCL or IgM-aCL only were more likely to have SLE without the clinical features of APS. Since aCL antibodies have recently been shown to interact with a phospholipid-binding plasma protein beta 2-glycoprotein-I (beta 2-GPI), we measured the beta 2-GPI levels in these patients and found that beta 2-GPI levels are significantly higher in APS compared to SLE patients negative for aCL antibodies. Since beta 2-GPI is known to exert multiple effects on coagulation processes the interaction of aCL antibodies with this glycoprotein may play a pathogenic role in APS.

Water as contrast medium for computed tomography study of colonic wall lesions.

Abstract: A tap water enema combined with intravenous iodine contrast medium was used for computed tomographic (CT) study of the entire clean colon in 35 patients. Thirty of them showed a high suspicion of rectal, colon, or cecal pathology at either clinical examination, barium enema study, or endoscopy. The remaining five patients were examined for suspected local recurrence of carcinoma. This CT technique detected the wall abnormality in all but one case with two small adenomatous polyps. This procedure, which is simple, inexpensive, and has a good acceptance and tolerance, can accurately detect mural wall abnormalities.

c-myc mRNA expression in minor salivary glands of patients with Sjögren's syndrome.

Abstract: c-myc protooncogene is implicated in the pathogenesis of B cell lymphoid malignancies and high levels of c-myc mRNA expression are observed in activated blood mononuclear cells. Sjogren's syndrome (SS) is characterized by lymphocytic infiltrates of exocrine glands, remarkable B cell hyperreactivity and a strong predisposition to B cell neoplasia. In this study, c-myc protooncogene mRNA expression in 29 labial minor salivary gland biopsies from patients with primary SS and 15 controls was examined using in situ hybridization histochemistry. Two 40mer oligonucleotides from the 1st and the 2nd exon of the c-myc gene, labeled with 35S, were used as probes. To detect the origin of the cell hybridized with a c-myc probe, a combined immunochemistry in situ hybridization histochemistry technique was used. High c-myc mRNA expression was detected on acinar epithelial cells. c-myc did not correlate with c-fos and c-jun protein expression. Stronger c-myc mRNA expression was detected in labial salivary glands of patients with longer disease duration (p less than or equal to 0.002) and more intense T lymphocyte infiltrates (p less than 0.05) although these patients revealed no hypergammaglobulinemia. No correlation was observed between c-myc mRNA and B lymphocyte monoclonicity or lymphoma. In conclusion, strong c-myc mRNA expression was observed on epithelial cells of labial salivary glands from patients with primary SS. Our findings may indicate the presence of a reactivated virus hosted in these cells.