Showing papers by "University of Ioannina published in 1996"

Dilatonic black holes in higher curvature string gravity

Abstract: We give analytical arguments and demonstrate numerically the existence of black hole solutions of the 4D effective superstring action in the presence of Gauss-Bonnet quadratic curvature terms. The solutions possess nontrivial dilaton hair. The hair, however, is of "secondary type," in the sense that the dilaton charge is expressed in terms of the black hole mass. Our solutions are not covered by the assumptions of existing proofs of the "no-hair" theorem. We also find some alternative solutions with singular metric behavior, but finite energy. The absence of naked singularities in this system is pointed out.

Mixed monoclonal cryoglobulinemia and monoclonal rheumatoid factor cross-reactive idiotypes as predictive factors for the development of lymphoma in primary Sjögren's syndrome.

Abstract: Objective. To prospectively investigate whether mixed monoclonal cryoglobulinemia (MMC) and monoclonal rheumatoid factor (mRF)–associated crossreactive idiotypes (CRI) serve as predictive factors for the development of lymphoma in patients with primary Sjogren's syndrome (SS). Methods. One hundred three consecutive patients with primary SS were evaluated from 1986 to 1991. In all patients, the amount of cryoglobulin was measured by ultraviolet absorption at 280 nm and 260 nm. The type of cryoglobulinemia was identified by agarose gel electrophoresis, combined with immunofixation. Sera from all patients were evaluated by enzyme-linked immunosorbent assay, using the corresponding monoclonal or polyclonal antibodies, for the presence of immunoglobulins bearing the idiotypes 17109 (VκIIIb associated), G-6 (VH1 associated), and 3rd SS (a rabbit polyclonal antibody raised against the Fab fragment of an IgMκ mRF from a patient with primary SS). Data analysis was performed by logistic regression. Results. Eighteen of the patients with primary SS (17.4%) had MMC during the first evaluation. There was a statistically significant correlation between the presence of MMC and a higher prevalence of autoantibodies to Ro/SS-A and La/SS-B, as well as extraglandular manifestations. During a 5-year period, 7 patients developed lymphoma. Six of the 7 (86%) had MMC before the appearance of lymphoma, compared with 12 of 96 (12.4%) of the remainder (r = 0.421, P < 0.0009). Patients who developed lymphoma had higher amounts of cryoglobulin than those who did not (mean ± SD 53.4 ± 44.7 mg/dl versus 26.8 ± 20.6 mg/dl). CRIs 17109 and G-6 were also correlated with lymphoma development (r = 0.321, P < 0.006 and r = 0.22, P < 0.03, respectively). For both CRIs, this correlation was dependent on the presence of MMC, since a stepwise multiple comparison analysis revealed that their individual significance was abolished when their correlation with lymphoma in association with MMC was assessed. Conclusion. The determination of MMC can be used as a laboratory predictive factor for lymphoma development in primary SS. CRIs 17109 and G-6 may also be used to predict lymphoma development, especially when the monoclonal component is absent.

Neutrinoless double beta decay within the quasiparticle random-phase approximation with proton-neutron pairing.

Abstract: We have investigated the role of proton-neutron pairing in the context of the quasiparticle random phase approximation formalism. This way the neutrinoless double beta decay matrix elements of the experimentally interesting A = 48, 76, 82, 96, 100, 116, 128, 130, and 136 systems have been calculated. We have found that the inclusion of proton-neutron pairing influences the neutrinoless double beta decay rates significantly, in all cases allowing for larger values of the expectation value of light neutrino masses. Using the best presently available experimental limits on the half lifetime of neutrinoless double beta decay we have extracted the limits on lepton number violating parameters. \textcopyright{} 1996 The American Physical Society.

Chromomycin A3-staining as an indicator of protamine deficiency and fertilization

Abstract: Mature mammalian spermatozoa have a compact and stable nuclear structure conferred by protamines instead of histones, which are present in all other cellular types. Chromomycin A3 (CMA3) is a useful tool for the detection of protamine deficiency in sperm chromatin. The purpose of this study was to correlate the percentage of spermatozoa staining positively for CMA3 with sperm parameters and in-vitro fertilization of human oocytes. Spermatozoa were collected from 56 fertile and 18 infertile men, and washed twice in PBS, fixed in two changes of methanol : acetic acid (3 : 1 v : v) spread on rinsed slides treated with APES and dried. Twenty-four of the semen samples were subjected to both Percoll and swim-up, and were stained subsequently with CMA3. CMA3-stained spermatozoa were expressed as a percentage in a count of 200 spermatozoa. A substantial variation in the percentage of CMA3-stained cells was observed in ejaculated human spermatozoa, varying between 8% and 77%. A strong negative correlation (r = -0.64, p < 0.001) was found between sperm count and the percentage of CMA3-stained spermatozoa. No correlation was found between CMA3-stained spermatozoa and their motility, while excessive sperm morphological abnormalities were related positively to CMA3-staining. Spermatozoa in samples exhibiting low (8-62%) CMA3-staining had significantly higher fertilizing rates in vitro than did samples exhibiting high (49-77%) CMA3-staining. The mean percentage of CMA3-stained spermatozoa after swim-up or Percoll preparation (26% vs 31%) did not differ significantly. These results demonstrate a close relationship between CMA3-staining, fertilization and sperm count, and suggest potential application of this marker for the prediction of sperm quality and fertilizing capacity.

Heat transfer of a micropolar fluid by the presence of radiation

Abstract: An analysis of the steady flow of a micropolar fluid past an unmoving plate by the presence of radiation is considered. Numerical solution for temperature field has been derived and the effect of the radiation parameter on the temperature field is discussed.

Model Investigations for Vanadium-Protein Interactions. Synthetic, Structural, and Physical Studies of Vanadium(III) and Oxovanadium(IV/V) Complexes with Amidate Ligands.

Abstract: Reaction of the amide ligand N-[2-((2-pyridylmethylene)amino)phenyl]pyridine-2-carboxamide (Hcapca) with VCl(3) affords the compound trans-[VCl(2)(capca)] (1), the first example of a vanadium(III) complex containing a vanadium-deprotonated amide nitrogen bond, while reaction of bis(pentane-2,4-dionato)oxovanadium(IV) with the related ligands N-[2-((2-phenolylmethylene)amino)phenyl]pyridine-2-carboxamide (H(2)phepca), 1-(2-hydroxybenzamido)-2-(2-pyridinecarboxamido)benzene (H(3)hypyb), and 1,2-bis(2-hydroxybenzamido)benzene (H(4)hybeb) yields the complexes [VO(phepca)] (2), Na[VO(hypyb)].2CH(3)OH (4.2CH(3)OH), and Na(2)[VO(hybeb)].3CH(3)OH (5.3CH(3)OH) respectively. The preparation of the complex {N-[2-((2-thiophenoylmethylene)amino)phenyl]pyridine-2-carboxamido}oxovanadium(IV) (3) has been achieved by reaction of N-(2-aminophenyl)pyridine-2-carboxamide and 2-mercaptobenzaldehyde with [VO(CH(3)COO)(2)](x)(). Oxidation of complex 5.3CH(3)OH with silver nitrate gives its vanadium(V) analogue (8.CH(3)OH), which is readily converted to its corresponding tetraethylammonium salt (10.CH(2)Cl(2)) by a reaction with Et(4)NCl. The crystal structures of the octahedral 1.CH(3)CN, and the square-pyramidal complexes 3, 4.CH(3)CN, 5.2CH(3)OH, and 10 were demonstrated by X-ray diffraction analysis. Crystal data are as follows: 1.CH(3)CN, C(18)H(13)Cl(2)N(4)OV.CH(3)CN M(r) = 464.23, monoclinic, P2(1)/n, a = 10.5991(7) A, b = 13.9981(7) A, c = 14.4021(7) A, beta = 98.649(2)(o), V = 2112.5(3) A(3), Z = 4, R = 0.0323, and R(w) 0.0335; 3, C(19)H(13)N(3)O(2)SV, M(r) = 398.34, monoclinic, P2(1)/n, a = 12.1108(10) A, b = 19.4439(18) A, c = 7.2351(7) A, beta = 103.012(3) degrees, V = 1660.0(4) A(3), Z = 4, R = 0.0355, and R(w) = 0.0376; 4.CH(3)CN, C(19)H(12)N(3)O(4)VNa.CH(3)CN, M(r) = 461.31, monoclinic, P2(1)/c, a = 11.528(1) A, b = 11.209(1) A, c = 16.512(2) A, beta = 103.928(4)(o), V = 2071.0(5) A(3), Z = 4, R = 0.0649, and R(w) = 0.0806; 5.2CH(3)OH, C(20)H(10)N(2)O(5)VNa(2).2CH(3)OH, M(r) = 519.31, triclinic, P1, a = 12.839(1) A, b = 8.334(1) A, c = 12.201(1) A, alpha = 106.492(2) degrees, beta = 105.408(2) degrees, gamma = 73.465(2) degrees, V = 1175.6(3) A(3), Z = 2, R = 0.0894, and R(w) = 0.1043; 10, C(28)H(32)N(3)O(5)V M(r) = 541.52, monoclinic, P2(1)/c, a = 11.711(3) A, b = 18.554(5) A, c = 12.335(3) A, beta = 95.947(9) degrees, V = 2666(2) A(3), Z = 4, R = 0.0904, and R(w) = 0.0879. In addition to the synthesis and crystallographic studies, we report the optical, infrared, magnetic, and electrochemical properties of these complexes. Electron paramagnetic resonance [of oxovanadium(IV) species] and (1)H, (13)C{(1)H}, and (51)V nuclear magnetic resonance [of oxovanadium(V) complex] properties are reported as well. This study represents the first systematic study of vanadium(III), V(IV)O(2+), and V(V)O(3+) species containing a vanadium-deprotonated amide nitrogen bond.

Searching for cold dark matter

Abstract: The differential cross section for the elastic scattering of the lightest supersymmetric particle (LSP) with nuclear targets is calculated in the context of currently fashionable supersymmetric theories (SUSY). An effective four-fermion interaction is constructed by considering (i) exchange, (ii) s-quark exchange and (iii) Higgs exchange. It is expressed in terms of the form factors (isoscalar) and and (isovector) which contain all the information of the underlining theory. Numerical values were obtained using representative input parameters in the constrained parameter space of SUSY phenomenology. Both the coherent and for odd-A nuclei the incoherent (spin) nuclear matrix elements were evaluated for nuclei of experimental interest. The spin matrix elements tend to dominate for odd light nuclei but the coherent matrix elements become more important in all other cases. For the coherent part the Higgs contribution is more important than the Z and s-quark contributions. Cross sections as high as have been obtained.

Childhood brucellosis in north-western Greece : a retrospective analysis

Abstract: Fifty-two cases of childhood brucellosis which occurred in north-western Greece during the 15-year period 1979–1993, are reviewed. It is believed that they represent very closely the total incidence of the disease in the region which has a population of 100,000 children aged 0–14 years old. Brucellosis-affected children were almost exclusively from goat-or shepherd families and of both sexes and all age groups. A broad spectrum of clinical manifestations ranging from malaise only to brain abscess was observed. Fever and arthralgia were the most common manifestations followed by malaise, myalgia, sweating, rash, cough, and gastro-intestinal, cardiac and CNS involvement. Splenomegaly was found more often than hepatomegaly and lymphadenopathy. Laboratory findings included anaemia, leukopenia, neutropenia, lymphocytopenia, monocytosis, eosinophilia, thrombocytopenia and pancytopenia. Leukocytosis and lymphocytosis were extremely rare and ESR and serum C-reactive protein levels were mildly elevated. All patients had positive Rose Bengal slide agglutination tests and standard tube agglutination titres of 1∶60 or more. When performed, blood culture was often diagnostic. The children were treated with streptomycin for 2 weeks plus either tetracyclines or trimethoprim-sulphamethoxazole for 3 weeks. Treatment was well tolerated. Relapse was observed in one case.

Malignant pleural mesothelioma from nonoccupational asbestos exposure in Metsovo (north-west Greece): slow end of an epidemic?

Abstract: Inhabitants of the Metsovo area, north-west Greece have been exposed since childhood to inhalation of asbestos, from a material containing tremolite, used for whitewashing ("luto soil"). This has resulted in endemic pleural calcifications (47% of adult population) and increased incidence of malignant pleural mesothelioma (MPM). In 1987, we reported that the incidence of MPM between 1981-1985 was around 300 times higher than expected in a nonasbestos exposed population (seven cases in 5 yrs in a population of 4,000-5,000). The present study is an updated report regarding this "mesothelioma epidemic", in conjunction with the diminished use and final abandonment of "luto soil" in the early 1980s. It appears that the incidence of MPM in Metsovo has dropped considerably since our first report. Between 1985-1994, we diagnosed six such cases (incidence rate = 1.4 cases per 10,000 person-years), whilst between 1980-1984 eight cases had been diagnosed (incidence rate = 3.7 cases per 10,000 person-years). Although, because of the small number of cases, this did not reach statistical significance (p = 0.08), we note that the incidence is now considerably lower than before. Had it remained unchanged, we would have expected 17 cases of MPM instead of six. This drop follows the diminished use of "luto" whitewash (by 92% of the population in 1950 and only 18% in 1980). If we take into account a 30-40 year latency period for mesothelioma, we expect that the "Metsovo mesothelioma epidemic" will fade away by the year 2020-2030, since the material has not been used since 1985.

Charged current neutrino-nucleus reaction cross sections at intermediate energies.

Abstract: Inclusive and semi-inclusive neutrino-nucleus reaction cross sections at intermediate energies (20 MeV\ensuremath{\le}${\mathit{E}}_{\ensuremath{ u}}$\ensuremath{\le}500 MeV) are calculated throughout the Periodic Table for the most interesting nuclei from an experimental point of view. The method used had previously proved to be very accurate in calculating the inclusive reaction cross section for light nuclei ${(}^{12}$C and $^{16}\mathrm{O}$) and in the study of other similar processes and has been further improved to deal with low energy neutrinos. The electron neutrino (${\ensuremath{ u}}_{\mathit{e}}$) and muon neutrino (${\ensuremath{ u}}_{\mathrm{\ensuremath{\mu}}}$) cross sections weighted by their energy distributions are also calculated and discussed in conjunction with the existing experimental results at LAMPF and the KARMEN Collaboration. \textcopyright{} 1996 The American Physical Society.

An evaluation of the Y2O3:Eu3+ scintillator for application in medical x-ray detectors and image receptors.

Abstract: The suitability off a Y2O3:Eu3+ scintillator for use in radiation detectors and medical image receptors was studied. Y2O3:Eu3+ was used in the form of laboratory prepared screens of different coating thicknesses. The x-ray luminescence efficiency of the screens was measured for tube voltages between 50-200 kVp and in both transmission and reflection modes of observation. The intrinsic x ray to light conversation efficiency (nc) and other parameters of the Y2O3:Eu3+ phosphor material related to optical scattering, absorption, and reflection were determined. These were used in the calculation of the image transfer characteristics, MTF and zero frequency DQE, for various screen coating thicknesses and x-ray tube voltages. The light emission spectrum of Y2O3:Eu3+ was measured (narrow band peak at 613 nm) and its spectral compatibility to the spectral sensitivity of several commonly employed optical photon detectors was determined. The x-ray luminescence efficiency varied with x-ray tube voltage, attaining maximum value at about 80 kVp for all screen thicknesses. It also varied with coating thickness reaching 25 microW m(-2)/mR s(-1) and 18 microW m(-2)/mR s(-1) at 175 mg/cm2 for reflection and transmission modes, respectively. The intrinsic x ray to light conversion efficiency and the image transfer characteristics were found to be comparable to several commercially used phosphors: nc = 0.095, MTF0.05 ranged between 10 and 25 line pairs per mm and peal values of DQE(0) varied between 0.33 and 0.14 in the coating thickness and kVp ranges useful for x-ray imaging. Spectral compatibility to some red sensitive optical photon detectors was excellent (0.9 or better). Results indicated that Y2O3:Eu3+ is a medium to high overall performance material that could be used in medical x-ray detectors and image receptors.

Effects of Early Parenting on Growth and Development in a Small Primate

Abstract: We report here a study of the impact of caregiver-infant relationships on physical growth and behavioral development in a small primate, the common marmoset. Somatic growth was assessed from measurements of body weight, knee-heel length, head-tail length, head circumference, and pudendal pad width in females or testis volume in males obtained from unanesthetized monkeys. Behavioral information was gathered by focal animal samples for discrete rearing behaviors. Our data suggest that the frequency of positive parental behaviors during infancy is correlated with stature when the monkeys reach 10 and 20 wk of age. Furthermore, we found that juveniles that were mistreated by their parents during infancy were smaller in body weight, knee-heel length, and head-tail length, and they demonstrated abnormal social behavior. Finally, to address whether the apparent decreased growth observed in the young animals that had experienced negative parenting was also associated with alterations in hypothalamic-pituitary-adrenal (HPA) axis function, we examined the plasma ACTH and cortisol responses to synthetic ovine corticotropin-releasing hormone (oCRH) in these animals. We found that the incremental cortisol response to exogenous oCRH was significantly lower in the young adults that had experienced negative parenting during infancy compared with those who had nonabusive parents, indicating altered hypothalamic-pituitary-adrenal axis function in these animals. Our findings suggest that the quality of parental care influences later growth and behavior in the young marmoset.

Elevated interleukin‐1β in the circulation of patients with essential hypertension before any drug therapy: a pilot study

Abstract: Immune system disturbances have been implicated in the pathogenesis of essential hypertension. The aim of this study was to determine the levels of the interleukin-1 beta and soluble interleukin-2 receptors in serum samples from 114 hypertensive patients before any drug therapy because there are no well-established data regarding these immunologic mediators in essential hypertension. We found increased levels of interleukin-1 beta in 59.6% of patients, while soluble interleukin-2 receptors were not detected. The interleukin-1 beta levels were significantly higher in patients than in healthy controls (P = 0.0001). We conclude that patients with essential hypertension have high levels of interleukin-1 beta but not indicators of cellular immune activation in their sera. Further studies are in progress in order to confirm, explain and assess the clinical utility of the above findings.

Epitope mapping of the Ro/SSA60KD autoantigen reveals disease-specific antibody-binding profiles.

Abstract: Anti-Ro60KD autoantibodies are commonly found in sera from patients with primary Sjogren's syndrome (SS) and systemic lupus erythematosus (SLE). In order to identify the epitopes of this autoantigen, 22 -mer, synthetic peptides overlapping by eight residues, and covering the entire sequence of the Ro60KD autoantigen were prepared. Three groups of sera were evaluated according to their autoantibody specificities. The first group consisted of monospecific anti Ro60KD sera from four patients with SLE and one with SS, the second one was composed of anti-Ro60KD + anti-La(SSB)-positive sera from four patients with SS and the third group included three normal sera and one anti Ro52KD serum. It was found that sera from SLE patients interact with a common antigenic site spanning the sequence TKYKQRNGWSHKDLLRSHLKP (169–190) of the Ro60KD protein. On the other hand, sera from SS patients recognise the ELYKEKALSVETEKLLKYLEAV (211–232) region of this autoantigen. Determination of the minimal required peptide length for optimal antibody recognition showed that the defined epitopes can be shortened to the NGWSHKDLLR (175–184) and KALSVETEKLLKYLEAV (216–232) sequences respectively. Inhibition experiments using the Ro60KD antigen and soluble peptides corresponding to the 175–184 and 216–232 segments further confirmed the specific antibody binding. These results, although only a small number of sera were used, indicate that the Ro60KD autoantigen, which is not charac- terized by disease specificity, contains two discrete epitopes specifically recognized from SLE and SS patient sera. Finally, the sequence similarity of the NGWSHKDLLR (175–184) epitope with some of the HLA haplotypes, associated with anti-Ro response, deserves to be noted.

Neglected congenital dislocation of the hip: Role of computed tomography and computer-aided design for total hip arthroplasty

Abstract: Computed tomography (CT) provides important three-dimensional anatomic details in congenital dislocation of the hip that are useful for total hip arthroplasty (THR) and are not obtainable with conventional radiographic evaluation. In this study, 84 patients (119 hips) with congenital dislocation of the hip were evaluated with CT before surgery. Specifically, both the acetabulum and the femur were analyzed to make the best selection of the prosthesis. The average anteversion of the acetabulum was 23°, with an opening of 30.9 mm and a depth of 14.7 mm. The bone stock of the true acetabulum was calculated and the average available diameter for the acetabular implant was 44.9 mm. The CT topogram revealed the true leg-length discrepancy (average, 0.5–1.9 cm), and the amount of a shortening osteotomy when necessary was determined. Finally, to determine the stem with optimum fit and fill, a three-dimensional reconstruction of the femoral canal using CT data and computer-aided design (CAD) was matched with a three-dimensional geometry of several stem designs and sizes obtained from a CAD system.

Abnormalities of ocular motility in myotonic dystrophy

Abstract: Are the oculomotor disturbances in myotonic dystrophy (MD), i.e. reduced smooth pursuit (SP) gain and reduced saccadic peak velocity (PV), of muscular or central origin? To answer this question the following two approaches were used. (i) The performance of SP was compared with the patient's ability to suppress the vestibulo-ocular reflex (VOR) visually (VOR suppression; VOR-S). In the latter task the SP system is involved, but the eyes hardly move within the orbits. A parallel impairment of SP and VOR-S would indicate a central dysfunction. (ii) Peak saccadic velocity was compared between two saccades performed to and fro in rapid succession. The intention was to measure any myotonic effect which might build up after the first saccade and slow down the second saccade. We studied 15 MD patients and 15 age-matched controls. Stimuli for slow eye responses consisted of sinusoidal horizontal rotations of the SP target and/or the vestibular rotation chair at frequencies between 0.1 and 0.8 Hz. Saccades were analysed in terms of PV. accuracy, duration and latency, comparing centripetal versus centrifugal saccades at short and long intersaccadic intervals (ISI; 400 ms and 900 ms, respectively). The SP gain was reduced in patients compared with the controls, the effect being most pronounced (32% less) at the highest stimulus frequency. Whereas VOR was normal in the patients, VOR-S was clearly impaired (50% worse at 0.8 Hz). Despite normal saccadic accuracy, peak saccadic velocity was significantly lower in the patient group (23% less for saccades of 12 degrees amplitude), similarly for centrifugal and centripetal saccades; all these differences were independent of the ISI. Latency was normal with centrifugal saccades, but was considerably increased with centripetal saccades at short ISI (67% longer compared with controls). The observation of a parallel degradation of SP and VOR-S in the patients is interpreted in terms of a central deficit in the SP pathways. Thus, it appears that slow eye movements were not impaired by muscle dystrophy and myotonia to a considerable degree in our patients. The increase in saccadic latency for centripetal saccades at the short ISI also reflects a central deficit. However, the observed slowing of saccades might have a myopathic or neural origin; a distinction was not possible at present. A myotonic origin of the saccade slowing seems unlikely, because the effect was independent of the presaccadic activation of the relaxing (antagonistic) eye muscle.