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Biomedical subjects

J Szabo

Publications and source records attributed to J Szabo.

At least 19 recordsLinked to original sources
PubMed2005

Nongenomic effect of thyroid hormone on free-radical production in human polymorphonuclear leukocytes.

Over the past few years increasing evidence has suggested the nongenomic effects of thyroid hormone, such as the activation of the signal transduction pathways and the activation of nuclear factor-kappaB by the induction of oxidative stress. The present study was undertaken to investigate the effect of thyroid hormone on human polymorphonuclear leukocytes (PMNLs) which are known as important sources of reactive oxygen species in the circulation. The production of superoxide anion (O2-) and the activity of myeloperoxidase were determined in the presence and absence of several inhibitors of the signalling pathway. L-thyroxine (T4) l-3,5,3'-tri-iodothyronine (T3) and L-3,5-di-iodothyronine (T2) stimulated O2- production in PMNLs in a dose-dependent manner within a few minutes of addition to cells. Thyroid hormone-stimulated O2- production was partially inhibited by pertussis toxin, an inhibitor of GTP-binding G protein, and was completely abolished by the protein kinase C inhibitors calphostin C and Ro-32-0432, and by a calcium chelator (BAPTA; bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid). Thyroid hormone stimulated myeloperoxidase activity and induced 125I- incorporation into PMNLs. Furthermore, thyroid hormone pre-incubation enhanced O2- production for n-formyl-methionyl-leucyl- phenylalanine (FMLP) stimulation. In conclusion, novel nongenomic actions of thyroid hormone, the induction of superoxide anion production and the stimulation of myeloperoxidase activity in PMNLs were demonstrated. The induction of O2- production requires calcium and is mediated by a pertussis toxin-sensitive G protein via stimulation of protein kinase C(s). These results suggest the existence of a membrane-bound binding site for thyroid hormone in PMNLs and a physiological role for thyroid hormone in the cellular defence mechanisms by stimulating free-radical production.

Adult↗
PubMed2002

In vitro cell irradiation systems based on 210Po alpha source: construction and characterisation.

One way of studying the risk to human health of low-level radiation exposure is to make biological experiments on living cell cultures. Two 210Po alpha-particle emitting devices, with 0.5 and 100 MBq activity, were designed and constructed to perform such experiments irradiating monolayers of cells. Estimates of dose rate at the cell surface were obtained from measurements by a PIPS alpha-particle spectrometer and from calculations by the SRIM 2000, Monte Carlo charged particle transport code. Particle fluence area distributions were measured by solid state nuclear track detectors. The design and dosimetric characterisation of the devices are discussed.

Alpha Particles↗
PubMed2002

SPECT using 99mTc-DTPA for the assessment of disease activity in Graves' ophthalmopathy: a comparison with the results from MRI.

Currently available methods for the estimation of disease activity in the orbits of patients with Graves' ophthalmopathy (GO) have the disadvantages of being either expensive or time consuming. The aim of this study was to develop a quick, reliable method using Tc labelled diethylenetriaminepentaacetic acid (DTPA) and four-headed single photon emission computed tomography (SPECT) for this purpose. The theoretical basis of the method is that the high capillarization and oedema in the orbit may be reflected on Tc-DTPA images in GO. SPECT data of 28 orbits of 14 patients with GO were compared with magnetic resonance imaging (MRI) T2 relaxation time scores. Based on the number of 'active' muscles with T2 relaxation times of more than 70 ms in a given orbit, an MRI score of 0 (no active muscle) to 4 (all rectus muscles active) was assigned to the orbit. With MRI, 18 orbits were inactive, and 10 were active. Thirty minutes after the intravenous administration of 7 MBq.kg Tc-DTPA, 128 projections were acquired by a four-headed SPECT. On the sum of six transaxial slices containing the entire bulbar region of the skull, a triangle-like region of interest (ROI) was drawn (OR ROI). This ROI was 'slipped' to the right temporal region of the brain as reference site (B ROI). The count ratios of OR/B were calculated and compared to MRI score values. In the group of 18 inactive orbits (an MRI score of zero on both sides), in the transaxial plane, the mean OR/B value was 6.4+/-1.17, and in the group of 10 active orbits (an MRI score of 1-3) 8.30+/-2.08, the difference being significant (P <0.05). Tc-DTPA orbital SPECT is a promising method for the estimation of disease activity in the orbits of patients with Graves' ophthalmopathy.

Adult↗
PubMed2001

Dealing with emergencies in rural areas of Europe: proceedings from WONCA Europe 2000.

On 4 July 2000, two workshops on handling emergencies in rural areas of Europe were held at the WONCA (World Organisation of National Colleges and Academies of Family Medicine/General Practice) conference in Vienna under the auspices of EURIPA (European Rural and Isolated Practitioners' Association). Papers submitted covered varying patterns of service provision and examples of short intensive training for emergencies at resident and general practitioner levels. Ways of collecting data routinely for accident prevention were also discussed. The workshops concluded that there was a need for more research in the application of emergency skills, that lack of confidence in dealing with emergencies may contribute to recruitment problems, and that further work towards a document detailing training requirements for emergencies was needed. This will be developed at a EURIPA workshop at WONCA in Tampere, June 2001.

Accident Prevention↗
PubMed2001

High throughput cell-based assay of hematopoietic progenitor differentiation.

The in vitro efficacy of drug candidates relative to hematopoietic stem cell proliferation and differentiation is currently assayed through use of the clonogenic "colony assay." The extremely low throughput of this assay precludes its use in library screening and much drug discovery work. A rapid-throughput assay of progenitor cell differentiation based on the quantification of hematopoietic lineage-specific markers has been developed. The CELISA assay employs a single incubation with a lanthanide-conjugated primary antibody and subsequent time-resolved fluorescence spectroscopy. The rapid-throughput nature of this assay is enhanced by the use of cell culture-compatible filter plates to reduce the number of manipulations as compared to currently available cell-based assays. The culture and assay are done in 96-well plates, and the quantitation process requires approximately 1 hour. The myeloid, erythroid, and megakaryocytic lineages can be objectively quantified; data from the assay correlate extremely well with data generated through use of the traditional colony assay. This assay makes possible both rapid-throughput drug discovery and toxicity screening in the area of hematopoiesis.

Antigens, CD34↗
PubMed2001

Growth and development in preterm infants fed long-chain polyunsaturated fatty acids: a prospective, randomized controlled trial.

OBJECTIVES: A randomized, masked, controlled trial was conducted to assess effects of supplementing premature infant formulas with oils containing the long-chain polyunsaturated fatty acids, arachidonic acid (AA; 20:4 n6), and docosahexaenoic acid (DHA; 22:6 n3) on growth, visual acuity, and multiple indices of development. METHODS: Infants (N = 470) with birth weights 750 to 1800 g were assigned within 72 hours of the first enteral feeding to 1 of 3 formula groups with or without long-chain polyunsaturated fatty acids: 1) control (N = 144), 2) AA+DHA from fish/fungal oil (N = 140), and 3) AA+DHA from egg-derived triglyceride (egg-TG)/fish oil (N = 143). Infants were fed human milk and/or Similac Special Care with or without 0.42% AA and 0.26% DHA to term corrected age (CA), then fed human milk or NeoSure with or without 0.42% AA and 0.16% DHA to 12 months' CA. Infants fed exclusively human milk to term CA (EHM-T; N = 43) served as a reference. RESULTS: Visual acuity measured by acuity cards at 2, 4, and 6 months' CA was not different among groups. Visual acuity measured by swept-parameter visual-evoked potentials in a subgroup from 3 sites (45 control, 50 AA+DHA [fish/fungal]; 39 AA+DHA [egg-TG/fish]; and 23 EHM-T) was better in both the AA+DHA (fish/fungal; least square [LS] means [cycle/degree] +/- standard error [SE; octaves] 11.4 +/- 0.1) and AA+DHA (egg-TG/fish; 12.5 +/- 0.1) than control (8.4 +/- 0.1) and closer to that of the EHM-T group (16.0 +/- 0.2) at 6 months' CA. Visual acuity improved from 4 to 6 months' CA in all but the control group. Scores on the Fagan test of novelty preference were greater in AA+DHA (egg-TG/fish; LS means +/- SE, 59.4 +/- 7.7) than AA+DHA (fish/fungal; 57.0 +/- 7.5) and control (57.5 +/- 7.4) at 6 months' CA, but not at 9 months' CA. There were no differences in the Bayley Mental Development Index at 12 months' CA. However, the Bayley motor development index was higher for AA+DHA (fish/fungal; LS means +/- SE, 90.6 +/- 4.4) than control (81.8 +/- 4.3) for infants </=1250 g. When Spanish-speaking infants and twins were excluded from the analyses, the MacArthur Communicative Development Inventory revealed that control infants (LS means +/- SE, 94.1 +/- 2.9) had lower vocabulary comprehension at 14 months' CA than AA+DHA (fish/fungal) infants (100.6 +/- 2.9) or AA+DHA (egg-TG/fish) infants (102.2 +/- 2.8). There were no consistent differences in weight, length, head circumference, or anthropometric gains. CONCLUSION: These results showed a benefit of supplementing formulas for premature infants with AA and DHA from either a fish/fungal or an egg-TG/fish source from the time of first enteral feeding to 12 months' CA.

Apgar Score↗
PubMed2001

The impact of increased blood flow rates on recirculation in central venous hemodialysis catheters.

A recent practice change in our unit from Quinton dual lumen PermCaths to Vas-Cath Optiflow central venous catheters resulted in the routine achievement of bloodflow rates (BFR) of 500 ml/min. Previously BFRs of 300-400 ml/min were the norm. The increased BFR was achieved without any apparent increase in venous pressure, prompting us to consider the possibility that increased recirculation was occurring. This paper presents the results of a study designed to answer the following questions: (a) What is the difference in recirculation rates between Quinton dual lumen PermCaths and Vas-Cath Optiflow dual lumen catheters? and (b) What is the impact of increased BFR on recirculation rates in Optiflow hemodialysis catheters? The study documented recirculation rates in two groups of patients. In Group 1, the Optiflow group, recirculation rates were calculated for 10 subjects, first at 350 ml/min and then at 500 ml/min. In Group 2, the PermCath Group, recirculation rates were calculated for 10 subjects at 300 ml/min. Paired t-tests were performed to compare Group 1 at 350 ml/min with Group 2. No significant differences were found within or between groups suggesting that recirculation rates were not affected by increased BFR.

Blood Circulation Time↗
PubMed2000

Acoustic radiation from an elastic baffled rectangular plate covered by a decoupling coating and immersed in a heavy acoustic fluid

The vibroacoustic behavior of an elastic, simply supported rectangular plate covered by a locally reacting decoupling layer supporting thickness deformation is presented. The model simulates the vibration and acoustic response of the system immersed in water and subjected to a point force disturbance. A simplified version of the theory is derived in the limiting case of a large decoupling (low mechanical impedance of the layer/high frequency). An appropriate vibratory indicator, representative of the acoustic attenuation provided by the decoupling treatment, and independent of the structure dimensions, is also investigated from the perspective of small-scale laboratory characterization.

Journal Article↗