Biomedical subjects

B Turan

Publications and source records attributed to B Turan.

29 records · Page 2Linked to original sources

PubMed1997

Effect of medication on biomechanical properties of rabbit bones: heparin induced osteoporosis.

The aim of this controlled study is to investigate the effect of heparin on osteoporosis initiation and of calcitonin and tamoxifen on the progress of osteoporosis induced by heparin through biomechanical means and, thus, to assist in clinical usage of these drugs. 32 four-month-old female New Zealand white rabbits were divided into four different experimental groups. The animals in group A were administered heparin (Liquemine) intraperitoneally at the dosage of 1000 IU/kg/day. The animals in group B were injected the same amount of heparin as those of group A, and in addition, were given calcitonin at the dosage of 100 IU/kg/day. The animals in group C were medicated the same way as group B but 2 mg/kg/day tamoxifen (Nolvadex) was orally added into their intestine via cannula, one side connected to the injector. The animals in group D were the control. The experiment lasted 8 weeks. The animals in all experimental groups showed the same growth pattern as that of the control group. Whole-bone femur, humerus and tibia specimens were subjected to 3-point bending tests while sections from the proximal ends of the same specimens were subjected to compression tests. The data, recorded as load vs deflection, were converted into stress vs strain using the strength of materials formulae. The data obtained from the bending and the compression experiments were treated separately. The stiffness of the bones of the medicated groups were compared with those of the control groups. Our data indicated that the tamoxifen treated humera, femora and tibiae attained the largest bending stiffness in all cases investigated. However, this was not the case for compression. None of the drug administered groups attained the stiffness of the control group except for the case of tamoxifen treated femora which attained stiffness close to that of the controls. The results show that heparin altered the mechanical properties of bones indicating osteoporosis, tamoxifen was effective in reducing the effect of heparin while calcitonin yielded no conclusive result.

Animals↗

PubMed1997

Dietary selenium- and vitamin E-induced alterations in some rabbit tissues.

The present study was designed to investigate and compare the effects of dietary selenium (Se) and vitamin E on some physiological parameters and histological changes in liver, heart, and skin tissues, as well as the blood parameters and the related enzymes. Both sex young rabbits were fed with deficient (9.8 micrograms/kg diet), adequate (225 micrograms/kg diet), and rich (4.2 mg/kg diet) Se and vitamin E diets for 12-15 wk for this purpose. As the plasma Se levels and the erythrocyte glutathione (GSH) peroxidase activity decreased (79.8 +/- 9.4 ng/mL and 2.0 +/- 0.3 U/g Hb, respectively) in the deficient group, these values increased (100.4 +/- 2.7 ng/mL and 14.5 +/- 4.3 U/g Hb) in the rich group significantly with respect to the control group. The other antioxidant enzyme activities and the related element levels did not change significantly in either one of the experimental groups. Although the platelet counts of the two experimental groups were not different from the control values, the collagen and the adenosine diphosphate (ADP) stimulated platelet aggregation rate and intensity increased in the deficient group (p < 0.05) and decreased very significantly (p < 0.001) in the rich group. In both of the experimental groups, as the percentage values of the neutrophils decreased, the lymphocytes and the eosinophils increased significantly. According to the light microscopic investigations, the observed lesions of considerable intensity within the tissues that elicit cell degenerations were more pronounced in the animals fed with the rich diet than in those fed with the deficient diet. The deficiency as well as toxicity of Se and the deficiency of vitamin E caused several alterations in the physiological functions of the tissues, and these alterations were supported by the histological lesions within these tissues.

Animals↗

PubMed1997

Oxidants increase intracellular free Zn2+ concentration in rabbit ventricular myocytes.

Oxidative stress may alter cardiac function by affecting intracellular free Zn2+ concentrations ([Zn2+]i). Rabbit ventricular myocytes loaded with fura 2 were used to fluorometrically measure resting [Zn2+]i (0.23 +/- 0.03 nM) and intracellular Ca2+ concentration ([Ca2+]i) (36 +/- 7 nM). Fluorescence quenching by the heavy metal chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine was used to quantitate [Zn2+]i. The thiol-reactive oxidants hypochlorous acid (0.1 mM) and selenite (1 mM) increased [Zn2+]i to 7.7 +/- 1.7 and 6.1 +/- 1.7 nM, respectively, within 5 min. Dithiothreitol (0.5 mM), a disulfide-reducing agent, rapidly restored normal [Zn2+]i. The oxidants did not affect [Ca2+]i. However, depolarization-induced Ca2+ transients and Ca2+ currents were zinc dependent. [Zn2+]i-associated fluorescence was substantial and, if ignored, it led to overestimation of [Ca2+]i by approximately twofold before oxidant treatment and by approximately eightfold after oxidants. The results demonstrate that [Zn2+]i 1) can be greatly increased by thiol-reactive oxidants; 2) may contribute to oxidant-induced alterations of excitation-contraction coupling; and 3) has strong fura 2 fluorescence which, if overlooked, can lead to significant overestimation of [Ca2+]i.

Animals↗

PubMed1997

Systemic levels of the T cell regulatory cytokines IL-10 and IL-12 in Bechçet's disease; soluble TNFR-75 as a biological marker of disease activity.

OBJECTIVE: To analyze the levels of the T cell regulatory cytokines interleukin 10 (IL-10) and IL-12 in plasma of patients with Behçet's disease (BD), and to assess the value of cytokines and cytokine antagonists as biological markers of disease activity. METHODS: Sera/plasma of 66 consecutive outpatients with established diagnosis of BD were analyzed for the presence of IL-2R, IL-6, tumor necrosis factor-alpha (TNF-alpha), soluble (s) TNF receptor (R)-55, sTNFR-75, IL-10, and IL-12 using immunological methods. Additional laboratory measurements included erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Data from the history and clinical examination were recorded to correlate cytokine levels with clinical markers of disease activity. RESULTS: 18 patients had inactive (Group I), 36 had mildly active (Group II), and 12 patients had active BD (Group III). IL-10 was elevated in 42 plasma samples (64%). The percentage of samples containing IL-10 and the median levels of IL-10 of the 3 patient groups did not differ significantly. IL-12 was detectable in plasma of 9 patients: One from Group I (5%), 3 from Group II (8%), and 5 from Group III (41%). IL-12 correlated with disease activity (difference between Groups I and III, p = 0.02, between Groups II and III, p = 0.008). ESR in patients with active disease and mildly active disease was significantly higher than values in patients with inactive disease (p = 0.03, p = 0.02, respectively), while median CRP levels were significantly different between Group I and Group III only (p = 0.006). sTNFR-75 levels were significantly different between Groups II and III (p = 0.003) and between Groups I and III (p = 0.008). CONCLUSION: The elevation of plasma IL-10 in the majority of patients and the correlation of IL-12 plasma levels with disease activity suggest a pathogenic role of a TH1-type immune response in active disease. In addition, the correlation of sTNFR-75 levels with disease activity indicates that sTNFR-75 may serve as a biological marker of disease activity in BD.

Adolescent↗

PubMed1996

Oxidative effects of selenite on rat ventricular contractility and Ca movements.

OBJECTIVE: The study aimed at characterizing the effects of selenite, known for its reactivity with thiols, on cardiac contractility and excitation-contraction coupling. METHODS: The inotropic effects of selenite were studied on rat papillary muscles. Freshly isolated rat ventricular myocytes were used to determine the selenite-induced alterations in thiol contents, free Ca2+ levels (in fura-2 loaded cells), Ca2+ currents and contractile properties of skinned cells. RESULTS: Selenite, at concentrations > or = 0.1 mM, affected muscle contractions by inducing a transient positive inotropic effect (up to 120 +/- 3% of control in 1 mM selenite) followed by a gradual decline of developed tension together with an increase in resting tension (respectively to 37 +/- 3 and 166 +/- 5% of their control values after 20 min exposure). These changes, irreversible on washout, could be reversed by the disulfonic reducing agent dithiothreitol (DTT, 1 mM). Lowering temperature from 35 degrees to 22 degrees C or preincubating the muscles with the disulfonic stilbene SITS (0.2 mM) completely prevented the selenite-induced transient positive inotropy and rise in resting tension. In isolated myocytes, 10 min exposure to 1 mM selenite induced a 40 +/- 9% decrease of total sulfhydryl content. At this concentration, selenite rapidly caused a rise of basal [Ca2+]i together with a diminution of the Ca2+ spike amplitude (respectively to 165 +/- 15 and 45 +/- 9% of their control values after 5 min exposure). In addition, selenite significantly enhanced at each Ca2+ concentration the force generated by skinned myocytes. Ca2+ currents, measured at 22 degrees C, decreased by 28 +/- 8% in the presence of 1 mM selenite. These effects were reversed by DTT. CONCLUSIONS: The results demonstrate that selenite, through alterations of cellular thiol redox status, induced a dual action on muscle contraction that can be imputed to a combined action on Ca2+ channels, Ca2+ transporters and contractile proteins. Extracellular negative effects of selenite are due to a partial reduction of Ca2+ current magnitude. Intracellular effects are mediated both by a diminution of Ca2+ handing by intracellular organelles and by a sensitization of the contractile to Ca2+ ions. The results further indicate that selenite uptake into the cardiac cells occurs mainly through the temperature-sensitive anion exchanger.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗

PubMed1993

The effects of selenium supplementation on antioxidative enzyme activities and plasma and erythrocyte selenium levels.

Plasma and erythrocyte selenium levels in rabbits supplemented with therapeutic doses of selenium were studied by Zeeman graphite furnace atomic absorption spectrometry using a new palladium-ascorbic acid chemical modifier in order to achieve a higher precision. An improved coupled test procedure was used to determine the glutathione peroxidase (GSH-Px) activities. Superoxide dismutase activities were measured employing a method for the clinical assay of the enzyme. The selenium levels and GSH-Px activities both in the plasma and erythrocytes were higher in the supplemented group when compared to the controls. The SOD activities were increased in the erythrocytes but remained unchanged in the plasma. Or the other hand, a higher copper/zinc ratio was found both in the plasma and erythrocytes of the supplemented group. These findings support the importance of the dietary selenium intake in terms of the principal role of selenium in the cellular antioxidative mechanisms and imply that measurements of plasma selenium levels may be a notable sensitive indicator of the short-term selenium status.

Animals↗

PubMed1993

The effects of in vivo selenium supplementation on the amplitude of the spontaneous contractions and the responses to acetylcholine in isolated rabbit ileum.

This study was carried out to investigate the effect of selenium supplementation at a therapeutic level on the isolated ileum contractions and the acetylcholine responses in New Zealand rabbits. While no difference with respect to the controls was found in the spontaneous ileum contraction frequencies a significant increase in the contraction amplitude was noted after 15 days of supplementation. Increasing concentrations of acetylcholine in the perfusion solution resulted in a significant increase of the contraction amplitudes in the supplemented animals as compared to controls. The tissue selenium levels and the gluthathione peroxidase activities were also found significantly higher than the controls. No difference was observed between the contraction numbers in the two groups. These findings indicate that selenium supplementation does not influence the smooth muscle resting potential.

Acetylcholine↗

PubMed1991

Selenium and Behçet's disease.

Behçet's disease is an inflammatory disorder of unknown etiology, characterized by recurrent oral and genital aphthous ulcers, ocular inflammation, and skin lesions of erythema nodosum and acneiform eruptions. Selenium (Se) affects all components of the immune system, i.e., the development and expression of nonspecific, humoral, and cell-mediated responses. In general, a deficiency in Se appears to result in immunosuppression, whereas supplementation with low doses of Se appears to result in augmentation and/or restoration of immunologic functions. In this study, the distribution of Se and IgG, IgM in serum were compared in samples from healthy adult control and Behçet's disease patients. The serum Se levels were measured by AA-30-40 Varian Spectra, and immunoglobulins were measured by immunodiffusion technique. The mean (SD) serum Se level of 54.24 +/- 8.06 ng/mL among Behçet's disease subjects was significantly different (P less than 0.01) from that in the control subjects (90.01 +/- 9.94 ng/mL). We also measured IgG and IgM as 10.01 +/- 2.74 mg/mL and 1.26 +/- 0.29 mg/mL, respectively for patients, and 15.08 +/- 4.73 mg/mL and 1.58 +/- 0.43 mg/mL for controls. The mean values of IgG and IgM for patients were significantly (P less than 0.05) different from the values of controls. It seems, therefore, that a deficiency in selenium impedes the humoral immune response.

Adult↗

PubMed1988

The quantitative investigation of infrared laser effects on the levels of copper and zinc in various tissues.

In order to study the effects of infrared laser irradiation on biological systems, the levels of copper and zinc in various irradiated tissues have been investigated. The zinc level in the muscle of the irradiated group increased (P less than 0.001) compared with the control group while in submandibular glands its level decreased (P less than 0.001). The copper levels in these two types of tissues decreased significantly (P less than 0.001). In irradiated skin, both copper and zinc levels increased compared with the control group (P less than 0.005). Quantitative determination of the trace elements copper and zinc indicated the necessity for more detailed studies of the effect of infrared laser irradiation at the cellular level.

Animals↗

PubMedDate not supplied

Serum selenium and glutathione-peroxidase activities and their interaction with toxic metals in dialysis and renal transplantation patients.

Selenium, aluminum, cadmium, and magnesium concentrations and glutathione-peroxidase activities in sera of 35 healthy individuals, 30 renal transplants, and 30 hemodialysis patients were measured. Serum selenium, aluminum, and cadmium concentrations in both groups of patients were higher than the controls (p less than 0.001), whereas the serum glutathione-peroxidase levels were lower (p less than 0.001). According to our results, it can be concluded that the patients receiving hemodialysis are subjected to more toxic elements than the transplantation patients. These findings imply that dietary selenium supplement may be suggested in renal failure for the detoxification of elements, such as cadmium and mercury. The essential trace element selenium takes part not only in the direct protection of endothelial cells against the accumulation of aggressive oxygen species, but also in the prevention of the toxic effects of cadmium or in the modulation of the active calcium transport.

Adolescent↗

PubMedDate not supplied

The use of fractional parameter in analyzing motor unit discharge pattern in stroke patients: a correlation with the functional independence measurement.

BACKGROUND: We have previously demonstrated that the fractional parameter has significant correlation with the muscle strength of patients with stroke. In this study, we have investigated whether fractional parameter can be used to objectively document stroke patients' functional level (using FIM scores). METHODS: Sixty motor units were recorded in abductor pollicis brevis, first dorsal interosseous, and abductor digiti minimi muscles in 18 stroke patients. Patients' FIM scores, obtained fractional parameters, and serial correlation coefficients were analyzed and statistical determination was made. RESULTS: Statistical significance was found between fractional parameters and motor items of FIMs (except selfcare category); no statistical significant correlation was found between SSC and FIM scores. CONCLUSION: Fractional parameter could be a useful tool for measuring motor function at a single motor unit level.

Activities of Daily Living↗