Showing papers by "University of Ioannina published in 2001"

Replication validity of genetic association studies.

Abstract: The rapid growth of human genetics creates countless opportunities for studies of disease association. Given the number of potentially identifiable genetic markers and the multitude of clinical outcomes to which these may be linked, the testing and validation of statistical hypotheses in genetic epidemiology is a task of unprecedented scale. Meta-analysis provides a quantitative approach for combining the results of various studies on the same topic, and for estimating and explaining their diversity. Here, we have evaluated by meta-analysis 370 studies addressing 36 genetic associations for various outcomes of disease. We show that significant between-study heterogeneity (diversity) is frequent, and that the results of the first study correlate only modestly with subsequent research on the same association. The first study often suggests a stronger genetic effect than is found by subsequent studies. Both bias and genuine population diversity might explain why early association studies tend to overestimate the disease protection or predisposition conferred by a genetic polymorphism. We conclude that a systematic meta-analytic approach may assist in estimating population-wide effects of genetic risk factors in human disease.

Completeness of Safety Reporting in Randomized Trials: An Evaluation of 7 Medical Areas

Abstract: ContextRandomized trials with adequate sample size offer an opportunity to assess the safety of new medications in a controlled setting; however, generalizable data on drug safety reporting are sparse.ObjectiveTo scrutinize the completeness of safety reporting in randomized trials.Design, Setting, and PatientsSurvey of safety reporting in 192 randomized drug trials 7 diverse topics with sample sizes of at least 100 patients and at least 50 patients in a study arm (N = 130074 patients). Trial reports were identified from comprehensive meta-analyses in 7 medical areas.Main Outcome MeasuresAdequate reporting of specific adverse effects and frequency and reasons for withdrawals due to toxic effects; article space allocated to safety reporting and predictors of such reporting.ResultsSeverity of clinical adverse effects and laboratory-determined toxicity was adequately defined in only 39% and 29% of trial reports, respectively. Only 46% of trials stated the frequency of specific reasons for discontinuation of study treatment due to toxicity. For these 3 parameters, there was significant heterogeneity in rates of adequate reporting across topics (P = .003, P<.001, and P = .02, respectively). Overall, the median space allocated to safety results was 0.3 page. A similar amount of space was devoted to contributor names and affiliations (P = .16). On average, the percentage of space devoted to safety in the results section was 9.3% larger in trials involving dose comparisons than in those that did not (P<.001) and 3.8% smaller in trials reporting statistically significant results for efficacy outcomes (P = .047).ConclusionsThe quality and quantity of safety reporting vary across medical areas, study designs, and settings but they are largely inadequate. Current standards for safety reporting in randomized trials should be revised to address this inadequacy.

Perinatal Transmission of Human Immunodeficiency Virus Type 1 by Pregnant Women with RNA Virus Loads <1000 Copies/mL

Abstract: In a collaboration of 7 European and United States prospective studies, 44 cases of vertical human immunodeficiency virus type 1 (HIV-1) transmission were identified among 1202 women with RNA virus loads 500 copies/mL. Perinatal HIV-1 transmission occurs in only 1% of treated women with RNA virus loads <1000 copies/mL and may be almost eliminated with antiretroviral prophylaxis accompanied by suppression of maternal viremia.

Luteolin Inhibits an Endotoxin-Stimulated Phosphorylation Cascade and Proinflammatory Cytokine Production in Macrophages

Abstract: Flavonoids are naturally occurring polyphenolic compounds with a wide distribution throughout the plant kingdom. In the present study, we compared the ability of several flavonoids to modulate the production of proinflammatory molecules from lipopolysaccharide (LPS)-stimulated macrophages and investigated their mechanism(s) of action. Pretreatment of RAW 264.7 with luteolin, luteolin-7-glucoside, quercetin, and the isoflavonoid genistein inhibited both the LPS-stimulated TNF-alpha and interleukin-6 release, whereas eriodictyol and hesperetin only inhibited TNF-alpha release. From the compounds tested luteolin and quercetin were the most potent in inhibiting cytokine production with an IC(50) of less than 1 and 5 microM for TNF-alpha release, respectively. To determine the mechanisms by which flavonoids inhibit LPS signaling, we used luteolin and determined its ability to interfere with total protein tyrosine phosphorylation as well as Akt phosphorylation and nuclear factor-kappaB activation. Pretreatment of the cells with luteolin attenuated LPS-induced tyrosine phosphorylation of many discrete proteins. Moreover, luteolin inhibited LPS-induced phosphorylation of Akt. Treatment of macrophages with LPS resulted in increased IkappaB-alpha phosphorylation and reduced the levels of IkappaB-alpha. Pretreatment of cells with luteolin abolished the effects of LPS on IkappaB-alpha. To determine the functional relevance of the phosphorylation events observed with IkappaB-alpha, macrophages were transfected either with a control vector or a vector coding for the luciferase reporter gene under the control of kappaB cis-acting elements. Incubation of transfected RAW 264.7 cells with LPS increased luciferase activity in a luteolin-sensitive manner. We conclude that luteolin inhibits protein tyrosine phosphorylation, nuclear factor-kappaB-mediated gene expression and proinflammatory cytokine production in murine macrophages.

Photocatalytic Degradation of Selected s-Triazine Herbicides and Organophosphorus Insecticides over Aqueous TiO2 Suspensions

Abstract: The photocatalytic degradation of selected s-triazine herbicides and organophosphorus insecticides was carried out in aqueous TiO2 suspensions under simulated solar light. The tested herbicides from the s-triazines group were atrazine, propazine, cyanazine, prometryne, and irgarol. The tested insecticides from the organophosphorus group were ethyl parathion, methyl parathion, ethyl bromophos, methyl bromophos, and diclofenthion. Degradation kinetics followed first-order reaction and has been monitored through gas chromatography. The degradation was fast with half-lives varying from 10.2 to 38.3 min depending on the nature and the structure of compounds. The generated transformation products (TPs) were formed via oxidation, dealkylation, and dechlorination for s-triazines and via oxidation and photohydrolysis for organophosphates. The TPs of irgarol, bromophos, and dichlofenthion were identified using solid-phase extraction (SDB-disks) and GC-MS techniques, and possible degradation routes were proposed showing similar degradation pathways as for other triazines and organophosporus pesticides. This work points out to the necessity of extended knowledge of the successive steps in a solar-assisted detoxification process.

Photodegradation of selected herbicides in various natural waters and soils under environmental conditions

Abstract: The photochemical degradation of herbicides belonging to different chemical groups has been investigated in different types of natural waters (ground, river, lake, marine) and distilled water as well as in soils with different texture and composition. Studied herbicides and chemical groups included atrazine, propazine, and prometryne (s-triazines); propachlor and propanil (acetanilides); and molinate (thiocarbamate). The degradation kinetics were monitored under natural conditions of sunlight and temperature. Photodegradation experiments were performed in May through July 1998 at low concentrations in water samples (2-10 mg/L) and soil samples (5-20 mg/kg), which are close to usual field dosage. The photodegradation rates of all studied herbicides in different natural waters followed a pseudo-first order kinetics. The half-lives of the selected herbicides varied from 26 to 73 calendar days in waters and from 12 to 40 d in soil surfaces, showing that the degradation process depends on the constitution of the irradiated media. The presence of humic substances in the lake, river, and marine water samples reduces degradation rates in comparison with the distilled and ground water. On the contrary, the degradation in soil is accelerated as the percentage of organic matter increases. Generally, the photodegradation process in soil is faster than in water. The major photodegradation products identified by using gas chromatography-mass spectrometry (GC-MS) techniques were the hydroxy and dealkylated derivatives for s-triazines, the dechlorinated and hydroxy derivative for the anilides, and the keto-derivative for the thiocarbamate, indicating a similar mode of degradation for each chemical category.

The presence of proprioceptive mechanoreceptors in the remnants of the ruptured ACL as a possible source of re-innervation of the ACL autograft.

Abstract: This study investigated the presence of neural mechanoreceptors in the remnants of the ruptured ACL as a possible source of reinnervation of the ACL autologous graft. The remainder of the torn ACL was selected for further histological investigation from 17 patients during ACL reconstruction 3 months to 3.5 years after injury. Perioperatively two types of ACL remnant were identified. Fifteen patients had portions of ACL adapted at the PCL. In all of these patients we found mechanoreceptors (I and II). In five patients we found mushroomlike remnants which included either none or small numbers of mechanoreceptors. Free neural ends were found in both patient groups. There was a significant difference between the groups in regard to the mean number of mechanoreceptors I and II per slice. In conclusion, in patients with an ACL remnant adapted to the PCL, mechanoreceptors exist even 3 years after injury. If we accept that restoration of proprioception is the result of reinnervation of the ACL, leaving the ACL remnants as a source, if this is surgically possible without risk of Cyclop's lesion, may be of potential benefit to the patient.

Serum Is the Preferred Clinical Specimen for Diagnosis of Human Brucellosis by PCR

Abstract: Human brucellosis poses a significant public health problem in many developing countries and requires fast and accurate diagnosis. A PCR assay amplifying part of the 31-kDa Brucella abortus antigenic protein gene sequence was developed and applied to whole-blood and serum samples from 31 brucellosis patients and 45 healthy individuals. All patients except one had detectable Brucella DNA in either whole blood or serum (combined sensitivity, 97%), but the assay sensitivity was higher with serum samples (94%) than with whole-blood samples (61%). The assay specificity was excellent (100%). A confirmatory PCR assay targeting another Brucella gene region (omp-2) was also developed but lacked sensitivity. Serum is the optimal specimen for the diagnosis of brucellosis by PCR, a choice that leads to assay simplification and shortens turnaround time.

Laparoscopic surgery-induced changes in oxidative stress markers in human plasma

Abstract: Background: The induction of the pneumoperitoneum increases intraabdominal pressure (IAP), causing splanchnic ischemia, whereas its deflation normalizes IAP and splanchnic blood flow. This procedure appears to represent an ischemia-reperfusion model in humans. Methods: Thirty laparoscopic cholecystectomies (LC) were performed in 30 patients with a mean age of 54.6 ± 15.6 years. A group of 20 patients mean age, 57.3 ± 9.65 who underwent open cholecystectomy (OC) was also studied. Vein plasma levels of thiobarbituric acid-reactive substances (TBARS), a marker of free radical production; plasma total antioxidant status (TAS); and uric acid (UA) levels were measured preoperatively, 5 min after deflation of the pneumoperitoneum or at the end of operation, and 24 h postoperatively. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TBL) levels were measured preoperatively and 24 h after the operation. Results: In the LC group, significant elevations in the concentration of TBARS were observed in the early postoperative measurements in comparison with the preoperative measurements. TAS and UA levels were decreased significantly 24 h postoperatively compared to preoperative levels. The postoperative levels of AST, ALT, and TBL increased significantly in comparison with the preoperative levels. In the OC group, no alterations in the concentration of TBARS were observed in the postoperative period. The other parameters had changes similar to those recorded for the LC group. Conclusions: Free radical-induced lipid peroxidation associated with a decrease in plasma antioxidant capacity and UA levels as well as altered hepatic function is observed after deflation of the pneumoperitoneum. These results suggest that free radicals are generated at the end of a laparoscopic procedure, possibly as a result of an ischemia-reperfusion phenomenon induced by the inflation and deflation of the pneumoperitoneum.

Varied pore organization in mesostructured semiconductors based on the [SnSe4](4-) anion.

Abstract: Open framework metal chalcogenide solids, with pore sizes in the nano- and mesoscale, are of potentially broad technological and fundamental interest in research areas ranging from optoelectronics to the physics of quantum confinement1,2. Although there have been significant advances in the design and synthesis of mesostructured silicas3,4, the construction of their non-oxidic analogues still remains a challenge. Here we describe a synthetic strategy that allows the preparation of a large class of mesoporous materials based on supramolecular assembly of tetrahedral Zintl anions [SnSe4]4- with transition metals in the presence of cetylpyridinium (CP) surfactant molecules. These mesostructured semiconducting selenide materials are of the general formulae (CP)4-2xMxSnSe4 (where 1.0 < x < 1.3; M=Mn, Fe, Co, Zn, Cd, Hg). The resulting materials are open framework chalcogenides and form mesophases with uniform pore size (with spacings between 35 and 40 A). The pore arrangement depends on the synthetic conditions and metal used, and include disordered wormhole, hexagonal and even cubic phases. All compounds are medium bandgap semiconductors (varying between 1.4 and 2.5 eV). We expect that such semiconducting porous networks could be used for optoelectronic, photosynthetic and photocatalytic applications.

Lipid profile in subclinical hypothyroidism: is L-thyroxine substitution beneficial?

Abstract: Objective: The significance of dyslipidemia in subclinical hypothyroidism (SH) and the effect of thyroid substitution on lipids remain controversial. The present study aimed to assess the association of SH with lipid abnormalities and to quantify the effect of L-thyroxine therapy on serum lipid profiles. Design: Serum lipid parameters of 66 patients with SH and 75 age- and sex-matched euthyroid controls were evaluated in a cross-sectional study. Results: Patients with SH had higher total cholesterol (TC)O222^45 (S.D.) vs 190^32 mg=dlU; lowdensity lipoprotein cholesterol (LDL-C)O139^28 vs 118^39 mg=dlU; apolipoprotein BO149^21 vs 139^18 mg=dlU and lipoprotein (a) (Lp(a)) (median 12.5 (0.8 ‐ 101) mg/dl vs 7 (0.8 ‐ 44) mg/dl) levels compared with euthyroid controls (P , 0:05 for all comparisons). In a follow-up study including 37 patients with SH, all measurements were repeated after restoration of a euthyroid state with incremental doses of L-thyroxine. No significant changes in serum lipid profiles were observed except for a decrease in high-density lipoprotein cholesterol O59^15 to 55^14 mg=dl; P , 0:05U: However, patients with high pre-treatment TC ($240 mg/dl) showed a significant reduction in both TC O278^28 vs 257^36 mg=dl; P , 0:05U and LDL-C O192^23 vs 173^28 mg=dl; P , 0:01U levels. Similar but more pronounced changes were observed in a subgroup of patients with pre-treatment levels of TSH $10mU/ml. Thyroid autoimmunity had no effect on either the baseline or the posttreatment lipid profile. Conclusion: Although patients with subclinical hypothyroidism exhibit increased levels of the atherogenic parameters (mainly LDL-C and Lp(a)), thyroid substitution therapy does not seem to significantly improve dyslipidemia in the whole group of patients.

Single-sample cloud point determination of iron, cobalt and nickel by flow injection analysis flame atomic absorption spectrometry—application to real samples and certified reference materials

Abstract: A preconcentration methodology utilizing the cloud point phenomenon is described for the determination of iron, cobalt and nickel by flame atomic absorption spectrometry (FAAS). The method employs the formation of complexes of the metallic species with ammonium pyrrolidinedithiocarbamate (APDC), which are subsequently entrapped in the micelles of the surfactant TX-114, upon increase of the solution temperature to 70 °C. The surfactant micelles, after their dilution to an acidified methanolic solution, are delivered to the nebulizer of the FAAS by a flow injection analysis (FIA) manifold, allowing for the reproducible injection of a small volume of the sample. The ability to handle the final texture of the injected solution allows for the single-step determination of these metal ions, in a single sample, without interferences. Analytical curves were rectilinear up to concentrations of 350 µg l−1 for Fe, 200 µg l−1 for Co and 250 µg l−1 for Ni with detection limits of 19, 5 and 11 µg l−1, respectively. The method was applied to the analysis of several real and spiked samples yielding satisfactory results. The recoveries obtained were in the range of 97–103% for spiked samples and 98–99.5% for a Certified Reference Material (CRM).

On-the-Disk Development of the Halo Coronal Mass Ejection on 1998 May 2

Abstract: A halo coronal mass ejection (CME) was observed at 15:03 UT on 1998 May 2 by the Solar and Heliospheric Observatory Large-Angle Spectrometric Coronagraph. The observation of the CME was preceded by a major soft X-ray flare in NOAA Active Region 8210, characterized by a delta spot magnetic configuration and some activity in region 8214. A large transequatorial interconnecting loop (TIL) seen in the soft X-rays connected AR 8210 to a faint magnetic field region in the periphery of region 8214. Smaller loop systems were also connecting AR 8210 to other fainter bipolar magnetic structures, the interconnecting loop (IL) east of AR 8210 being one of the most visible. We present here a multiwavelength analysis of the large- and small-scale coronal structures associated with the development of the flare and of the CME, with emphasis placed on radio-imaging data. In the early phases of the flare, the radio emission sources traced the propagation paths of electrons along the TIL and the IL, which are accelerated in the vicinity of AR 8210. Furthermore, jetlike flows were observed in soft X-rays and in Hα in these directions. Significantly, the TIL and IL loop systems disappeared at least partially after the CME. An EUV Imaging Telescope (EIT) dimming region of similar size and shape to the soft X-ray TIL, but noticeably offset from it, was also observed. During the flash phase of the flare, new radio sources appeared, presenting signatures of destabilization and reconnection at discrete locations of the connecting loops. We interpret these as possible signatures of the CME liftoff on the disk. An Hα Moreton wave (blast wave) and an EIT wave were also observed, originating from the flaring AR 8210. The signatures in radio, after the wave propagated high into the corona, include type II-like emissions in the spectra. The radio images link these emissions to fast-moving sources, presumably formed at locations where the blast wave encounters magnetic structures. The opening of the CME magnetic field is revealed by the radio observations, which show large and expanding moving sources overlying the later-seen EIT dimming region.

Phenomenology of a new minimal supersymmetric extension of the standard model

Abstract: We study the phenomenology of a new minimally extended supersymmetric standard model (nMSSM) where a gauge singlet superfield is added to the MSSM spectrum. The superpotential of this model contains no dimensionful parameters, thus solving the ? problem of the MSSM. A global discrete R symmetry, forbidding the cubic singlet self-interaction, imposed on the complete theory, guarantees its stability with respect to generated higher-order tadpoles of the singlet and solves both the domain wall and Peccei-Quinn axion problems. We give the free parameters of the model and display some general constraints on them. Particular attention is devoted to the neutralino sector where a (quasipure) singlino appears to be always the LSP of the model, leading to additional cascades, involving the NLSP ? LSP transition, compared with the MSSM. We then present the upper bounds on the masses of the lightest and next-to-lightest—when the lightest is an invisible singlet—CP-even Higgs bosons, including the full one-loop and dominant two-loop corrections. These bounds are found to be much higher than the equivalent ones in the MSSM. Finally, we discuss some phenomenological implications for the Higgs sector of the nMSSM in Higgs boson production at future hadron colliders.

Indications and Selection for Digital Amputation and Replantation

Abstract: Even though replantation surgery has now become a routine procedure, it remains delicate and demanding surgery, requiring adequate training and expertise in microsurgical techniques. Well-defined selection criteria for replantation procedures have evolved over the past few years, including definitive guidelines for thumb, single digit, multiple digit and mid-palm amputations. For more complex cases, other techniques, including transpositional microsurgery and various secondary reconstructive procedures, such as toe-to-hand transfer, are now available. Although replantation procedures have been simplified, a second surgical team can save valuable surgical time by debriding and identifying the vessels in the amputated part, harvesting microvenous grafts, and performing bone fixation or tendon repair among other things, while the chief surgeon focuses on revascularization. Overall, the most significant guideline underlining the philosophy of digital replantation today reflects the aim of not only ensuring the survival of a digit, but its functional use as well. Experience dictates that this can be achieved only if the basic principles and indications of replantation surgery are adhered to.

Isolation and Characterization of Virgin Olive Oil Phenolic Compounds by HPLC/UV and GC-MS

Abstract: This research examined the phenolic fraction of extra virgin olive oil samples from Lianolia variety olives grown in the region of Preveza, Greece. Phenolic compounds were extracted from oil samples, separated by reversed-phase high-performance liquid chromatography (HPLC), and characterized by gas chromatography-mass spectrometry (GC-MS). Both simple and complex phenols were detected with the latter being the most abundant. 3- 4-Dihydroxyphenyl ethanol (hydroxytyrosol) and p-hydroxyphenyl ethanol (tyrosol) predominated among the simple phenols. Complex phenolic compounds were further separated by preparative HPLC and analyzed by GC-MS before and after hydrolysis. The presence of hydroxytyrosol and tyrosol derivatives was confirmed. Both derivatives were always present in greater quantities and made up an average exceeding 70% in all samples analyzed.

Treatment of avascular necrosis of the femoral head with vascularized fibular transplant.

Abstract: Two hundred twenty-eight hips in 187 patients with avascular necrosis of the femoral head were treated with vascularized fibular transplant from March 1989 to March 2000. The etiologic factors associated with the disease included corticosteroids in 84 patients (44%; 101 hips, trauma in 25 patients (13%; 29 hips), alcohol abuse in 24 patients (12%; 28 hips), and 41 hips (18%) were classified as idiopathic. Systemic disorders, including systemic lupus erythematosus, sickle cell anemia, inflammatory bowel disease, pregnancy, and dysbaric disease were observed in 12, nine, four, three, and one hip(s), respectively. Of the 228 hips operated on, 184 hips (152 patients) were assessed postoperatively with followup ranging from 1 to 10 years (mean, 4.7 years). Using the Steinberg classification system, 39 hips (21%) were in Stage II; 45 hips (25%) were in Stage III; 77 hips (42%) were in Stage IV; and 23 hips (12%) were in Stage V. Of the 184 hips treated, 101 (54%) remained stable postoperatively, whereas 69 (38%) had progression, and 14 hips (8%) were converted to total hip arthroplasty. Of the 69 hips that had progression, 44 (64%) did not progress until 6 to 10 years after the procedure, whereas 25 (36%) progressed within the first 5 years postoperatively. The best results were obtained in patients with Stage II osteonecrosis in whom 95% of the hips did not progress postoperatively. In contrast, only 39% of the hips in patients with Stage V osteonecrosis remained stable. Preoperative and postoperative clinical evaluation using the Harris hip score showed an increase from 85 to 96 points in hips with Stage II disease; from 74 to 91 points in hips with Stage III disease; from 69 to 85 points in hips with Stage IV disease; and from 61 to 76 in hips with Stage V disease. The current results show that the vascularized fibular graft is an excellent procedure for the precollapse stages and a valuable alternative for patients with Stages III, IV, and V of the disease.