Showing papers by "University of Ioannina published in 1991"

Constitutive expression of heat-shock protein 70 in mammalian cells confers thermoresistance.

Abstract: A 70-kDa heat-shock-protein (hsp70) expression vector which contains the human hsp70 gene linked to the human β-actin promoter, was constructed and used to transfect CV1 monkey cells. Stably transfected CV1 clones were isolated which constitutively synthesized increased amounts of hsp70 at normal temperature. It is shown that these clones are resistant to elevated temperature. This finding indicates that hsp70 is involved in the protection of the cells against a lethal heat treatment and maybe responsible for the phenomenon of thermotolerance.

T cell subpopulations in the labial minor salivary gland histopathologic lesion of Sjögren's syndrome.

Abstract: The majority of T cells constituting the focal lymphocytic infiltrates in the labial minor salivary glands of patients with Sjogren's syndrome bear the helper phenotype (CD4); activation is expressed by class II (HLA-DR) MHC products. In our immunohistologic study of snap frozen minor salivary gland biopsies from 16 patients with primary Sjogren's syndrome, it was shown that the majority (77%) of the infiltrating T cells exhibit the memory helper/inducer phenotype (UCHL-1) and express LFA-1 molecules. In addition most of the T cells express the alpha beta receptor while only 2.8% express the gamma delta receptor. Our findings suggest that these T cell infiltrates in patients with primary Sjogren's syndrome may explain the intense B lymphocyte hyperreactivity observed in the exocrine glands of patients with Sjogren's syndrome.

The main immunogenic region (MIR) of the nicotinic acetylcholine receptor and the anti-MIR antibodies.

Abstract: Myasthenia gravis (MG) is caused by autoantibodies against the nicotinic acetylcholine receptor (AChR) of the neuromuscular junction. The anti-AChR antibodies are heterogeneous. However, a small region on the extracellular part of the AChR α subunit, called the main immunogenic region (MIR), seems to be the major target of the anti-AChR antibodies, but not of the specific T-cells, in experimental animals and possibly in MG patients. The major loop of the overlapping epitopes for all testable anti-MIR monoclonal antibodies (MAbs) was localized within residues 67–76 (WNPADYGGIK forTorpedo and WNPDDYGGVK for human AChR) of the α subunit. The N-terminal half of α67–76 is the most critical, Asn68 and Asp71 being indispensable for binding. Yet anti-MIR antibodies are functionally and structurally quite heterogeneous. Anti-MIR MAbs do not affect channel gating, but they are very potent in mediating acceleration of AChR degradation (antigenic modulation) in cell cultures and in transferring experimental MG in animals. Fab fragments of anti-MIR MAbs bound to the AChR prevent the majority of the MG patients' antibodies from binding to and causing loss of the AChR. Whether this inhibition means that most MG antibodies bind on the same small region or is a result of broad steric/allosteric effects is under current investigation.

The dynamics of some discrete population models

Abstract: IN THIS paper we are interested in providing sufficient conditions guaranteeing the fact that all positive solutions of the discrete delay difference equation A II+1 = AA, + F(A,_,) (E) converge as n + 00. In (E), A is a constant real number with 0 0 sufficiently small. Thus, formally, equation (E) comes from x(t + h) x(t) h = -yx(t) + D(x(t r)) for small h. If we set ~,z(f) := x(ht), then the preceding equation for t = n and r/h = m becomes yh@ + 1) = (1 ?‘h)Y, (n) + hD(Y,(n m)), which is of the form (E), where A := 1 yh and F(u) := hD(u), u 2 0. Clearly h > 0 is small if and only if A E (0, 1). 1069 @h)

Quantitative computed tomography for bone mineral measurement: technical aspects, dosimetry, normal data and clinical applications

Abstract: A single KVp quantitative CT (QCT) technique was used for measuring the spinal trabecular bone density. The trabecular bone equivalent density (TBED) was expressed as the density of a K2HPO4 solution that exhibits a linear attenuation coefficient identical to that of trabecular bone. A field non-uniformity correcting factor was obtained from experiments on phantoms. The effective equivalent dose of the whole examination (four sections and a scout view) is 370 μSv. The in vivo short-term precision (reproducibility coefficient of variation) ranges from 1.4% to 4.1% depending on the TBED values of the normal subjects. The TBED was measured in 206 normal Greeks aged 30–69 years. Average TBED decreased with increasing age for both sexes. Analysis considering separately each vertebra showed a tendency to a caudal spinal TBED reduction. No correlation was found between the TBED values and the body habitus, milk consumption, smoking habits in men, and number of full-term pregnancies. A significant differ...

Alcohol and drug use, family situation and school performance in adolescent children of alcoholics

Abstract: A survey was conducted in a population of about 8000 Greek high school students (grades 9 and 12) in order to investigate factors possibly contributing to alcohol consumption. A self-rating multiple choice questionnaire was used. The present report focuses on students with alcoholic parents. Parameters studied include students' alcohol and drug use, school performance, family relationships, socioeconomic factors and parental control. In 3.3% of the sample parental alcoholism was reported. The results indicated that parental alcoholism is a strong predictor variable for the student's alcohol and drug use. Furthermore, predictability of the student's alcohol and drug use is increased when relatives' and friends' alcoholism are taken into account. Thus, family and/or peer actual alcohol use patterns appear to be a strong influence on adolescent alcohol and drug use. School performance is worse in children of alcoholics, and family situations (eg. divorces) as well as family dynamics (relationships with the family) are disturbed, in comparison with families of students with nonalcoholic parents. These results are discussed in terms of 'modelling' for drinking and drug behaviour and the socialisation process within the family.

Antibodies Against Hepatitis C Virus (Anti-HCV) in Haemodialysis Patients: Association with Hepatitis B Serological Markers

Abstract: Hepatitis C virus (HCV) seems to be the main causative agent of the parenterally transmitted non-A, non-B hepatitis and the detection of anti-HCV may be a marker of ongoing infection with this virus This study was undertaken to determine the frequency of anti-HCV in 51 haemodialysis patients of our renal unit In addition association of these antibodies to sex, history of blood transfusions, and duration on haemodialysis, as well as to serological markers of hepatitis B virus infection, was applied Enzyme-linked immunosorbent assay (ELISA), were used for the detection of all serological markers Nine of the 51 (176%) haemodialysis patients had anti-HCV The presence of anti-HCV was related to male sex Although seropositive patients were transfused more often than seronegatives, this difference is not statistically significant The presence of anti-HCV was associated with the duration of haemodialysis The majority of anti-HCV patients had serological markers of previous HBV infection, in contrast to seronegative patients

Matching factors for various light-source-photodetector combinations

Abstract: The matching between the spectral distribution of the light emitted from a light source and the spectral distribution of the sensitivity of a light detector is characterized by the “matching factor”. In the paper we present a table of 500 matching factors for the combination of various phosphors with the most common photodetectors.

A comparative study of the behavioral effects of d-amphetamine and apomorphine in the rat.

Abstract: A wide range of doses of d-amphetamine and apomorphine were injected into rats, in order to better characterize and compare dopaminergic agonist-induced behavioral effects. The study was carried out using a computerized technique for the quantification and analysis of various behavioral elements. Although both drugs increased motor activity and provided dose-dependent stereotyped responses, the whole pattern of behavior in the open field showed a different structure. d-Amphetamine in doses that did not produce stereotyped responses induced a wide range of varied behavioral elements with increased frequency but decreased mean duration, while apomorphine induced a more restricted behavioral profile. Furthermore, a higher frequency of freezing reaction was observed after d-amphetamine treatment in low doses but not after apomorphine treatment. Both drugs in high doses elicited a similar stereotyped syndrome characterized by repetitive movements of great duration, but at low doses the behavioral pattern was completely different. The apomorphine-induced syndrome was characterized mainly by moving and sniffing, interrupted by rearing, while the amphetamine-induced syndrome by sniffing and moving, interrupted by standing and freezing.

Effect of treatment of synthetic zeolite-polymer membranes on their electrochemical-potential response characteristics

Abstract: The performance of synthetic-polymer membrane-electrodes for cation sensing is investigated by obtaining E versus pM graphs and E versus time curves of the same membrane type under different treatments or of membranes constructed by modified procedures. The slopes of E versus pM curves for the salts of monovalent cations show different values for the same membrane type as well as for the different membrane types and are found within the range of 43 to 57 mV per pM. The response time of the membrane is found to be slower when the membranes are plastic phase deficient. Generally, the detection limit is only slightly dependent on the composition of the membrane and the best value is obtained with the polished membranes which is close to the value of pM=5 while for the other membranes the values are within the range of pM 4 to 5. The range of linearity is also slightly dependent on the method of membrane construction and in general is shorter when the membranes are plastic phase deficient. The selectivity coefficients are found to depend significantly on the method of construction of the membrane but in general the selectivity of all the membranes studied in this report is poor. The asymmetry potential is found to be related to an ion exchange process and is developed slowly in 5A-type membranes. However, when the value of asymmetry potential is high, a longer time is needed to reach the final value of e.m.f. in measurements among different concentrations of the same metal ion and much longer is needed where there is switching of measurement from a monovalent cation to a divalent cation.

Research output evaluation of two University Departments in Greece with the use of bibliometric indicators

Abstract: The results of a study for evaluating research performance of two Greek University Departments of Mathematics are presented. In order to achieve this elements from the Sussex and Leiden methodologies of constructing and using bibliometric indicators were used. Comparison of the two groups were based on their similarities. The convergence of bibliometric indicators procedure as applied in Leiden methodology together with a number new bibliometric indicators were used. Results shown that bibliometric indicators if applied properly may give very interesting information on the research performance and nature of research carried out in University Departments.

Isolation and partial sequence of goat spleen prothymosin alpha.

Abstract: Goat prothymosin α, a highly acidic polypeptide of pl 3.5, 109 amino acid residues, has been isolated from lymphoid and non-lymphoid tissues of young female goats. Unlike rat, murine and porcine prothymosins α, goat prothymosin α appears at a higher concentration in the spleen compared with the thymus. The sequence of segments of the polypeptide involving known mutations has been determined, by automatic sequencing of its tryptic peptide fragments. The acidic amino acid-rich segment in the middle of the molecule, including residues 49–83, has not been sequenced. Goat prothymosin α closely resembles bovine prothymosin α, with only one substitution, proline for alanine at position 85. It also resembles human prothymosin α, with only three substitutions. It differs more significantly from rat and murine prothymosins α, by two deletions and three substitutions. The results show the highly conserved nature of the molecule, with substitutions at given positions only.

Chorea as a manifestation of the antiphospholipid syndrome in childhood.

Abstract: Chorea has been related to the presence of antiphospholipid antibodies (a-PL) in the context of systemic lupus erythematosus (SLE). Here we report the case of a 13-year-old girl with a-PL antibodies, who had developed thrombophlebitis at the age of 11 years and chorea two years later, in the absence of clinically evident SLE. Serological tests revealed a false positive test for syphilis, a prolonged activated partial thromboplastin time, hypocomplementaemia and positive anti-DNA antibodies.

Polycyclic aromatic hydrocarbons and mutagens in ambient air particles sampled in thessaloniki greece

Abstract: Seventy samples of airborne particulates were sampled from two sites in Thessaloniki, Greece, during the period of one year, starting in July 1987. Thessaloniki is located in the northeastern part of Greece and is the second most highly populated city of the country. The 24-h samples were taken by using high-volume samplers located in two monitoring sites — 1 and 2. Site 1 was located at the center of the city (main pollution sources were traffic and central heating), whereas site 2 was in the industrial zone of the city (main sources were industrial activities and traffic). The collected particulates were examined for their mutagenicity with the Ames test. The analysis of particulates to determine their content in polycyclic aromatic hydrocarbons (PAHs) was done by the gas chromatographic method. The column used to separate the various PAHs was a wide-bore capillary column. Ten PAHs were identified and quantified in the atmosphere of Thessaloniki. No essential differences were found between the mean values of PAH concentrations measured at the two sites, whereas the mutagenicity values at site 1 (central area) were higher than those measured at site 2 (industrial site). The PAH concentrations were moderate if compared with those found in other polluted cities in the world, whereas the mutagenic activity of particulates was low. Higher values of PAH concentrations and mutagenicity were found during winter. During Sundays the PAH concentrations were lower than those measured on weekdays. No significant linear correlation was found between PAH concentrations and mutagenicity for both sites of measurements. The main sources of PAHs were estimated to be the stationary sources in winter and the traffic in summer for both measuring sites. Higher values of both PAH concentrations and mutagenicity were found during days with light winds.

Gravitational Faraday rotation induced from interacting gravitational plane waves

Abstract: The polarization of gravitational plane waves is studied. In particular, it is found that each interacting gravitational plane wave can be split into two parts: the shock part and the impulsive part. The plane of the polarization for the plane gravitational shock waves usually gets rotated due to two kinds of interaction: one is the nonlinear interacton between the oppositely moving plane gravitational shock waves, and the other is the interaction between the gravitational shock wave and the matter fields which are present. The change of polarization due to the nonlinear interaction is exactly a gravitational analogue of Faraday rotation, but with the oppositely moving gravitational shock wave as the magnetic field and medium. The effect of the above two kinds of interaction on the impulsive gravitational plane waves is different from that on the shock waves. Only the interaction between the impulsive gravitational wave and the matter fields can change the polarization of the impulsive wave.

D-penicillamine toxicity in Greek patients with rheumatoid arthritis: anti-Ro(SSA) antibodies and cryoglobulinemia are predictive factors.

Abstract: Sixty-two consecutive patients, with rheumatoid arthritis (RA) who received D-penicillamine were studied retrospectively to identify predictive risk factors for D-penicillamine toxicity. Thirty-two developed side effects, while 30 did not. The clinical picture in both groups was similar, but the group with D-penicillamine toxicity was characterized by a high incidence of anti-Ro(SSA) antibodies (p less than 0.01) or circulating cryoglobulins (p less than 0.001). The presence of anti-Ro(SSA) antibodies was not correlated with the presence of circulating cryoglobulins (p greater than 0.5), while the coefficient of contingency (C) between anti-Ro(SSA) and cryoglobulins was 0.131. Men were predisposed to express more renal pathology (p less than 0.025), while anti-Ro(SSA) positive patients with RA more often expressed rashes (p less than 0.0001) and acute febrile reactions (p less than 0.05) than anti-Ro(SSA) negative patients. These observations should be considered when making therapeutic decisions at least for Greek patients with RA.

Autoantibodies in Greek juvenile chronic arthritis patients.

Abstract: The aim of this study was to investigate sera of Greek patients with juvenile chronic arthritis (JCA) for the presence of autoantibodies and correlate these antibodies with the clinical picture and disease activity. Sera from 69 JCA patients and sera from 66 healthy children matched for sex and age, were tested for antinuclear antibodies (ANAs), antibodies to extractable cellular antigens (ENAs), rheumatoid factor (RF), immunoglobulins (IgG, IgM), antibodies to double stranded (ds) DNA and anticardiolipin (CL). Our results indicate that: (a) autoantibodies to dsDNA are a not uncommon finding in JCA sera; (b) these autoantibodies have a low affinity for the antigen since they are found in low titers only by ELISA, while the Farr assay and Crithidia lucilliae immunofluorescence assay (IF) are negative; and (c) active JCA patients express many autoantibodies.