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At least 631 records · Page 35Linked to original sources
PubMed2005

One-portal endoscopically assisted fasciotomy for exertional compartment syndrome.

A newly described method of single-incision endoscopically assisted fasciotomy for chronic exertional compartment syndrome is outlined. The procedure affords a small 2- to 3-cm incision with visualization of the anterior compartment fascia, lateral compartment fascia, superficial peroneal nerve, perforating vessels, and underlying muscle. The single-portal endoscopically assisted fasciotomy for chronic exertional compartment syndrome in the anterior and lateral compartments of the lower leg is a safe and reliable technique with excellent outcomes and patient satisfaction. Moreover, this technique affords the patient an expeditious recovery because of the small incision and decreased soft tissue trauma throughout the lower leg.

Arthroscopy↗
PubMed2003

Copper-induced oxidative damage on astrocytes: protective effect exerted by human high density lipoproteins.

In the present study, we confirmed that copper ions induce oxidative damage in human astrocytes in culture, as demonstrated by the significant increase in the levels of hydroperoxides and in the fluorescence intensity of the fluorescent probe dichloro-dihydrofluorescein diacetate (H(2)DCFDA). The compositional changes were associated with a significant decrease in cell viability in astrocytes treated with 10 microM Cu(++) with respect to control cells. Astrocytes incubated with copper ions in the presence of high density lipoproteins (HDL) isolated from plasma of normolipemic subjects showed lower levels of hydroperoxides and a higher cell viability with respect to cells oxidized alone. Moreover, a significant decrease in the levels of hydroperoxides was observed in oxidized astrocytes treated with HDL. These results demonstrate that HDL exert a protective role against lipid peroxidation. The protective effect could be related to the ability of HDL to bind metal ions at the lipoprotein surface and/or to a stimulation of the efflux of lipid hydroperoxides from cell membranes as demonstrated in other cell types. Oxidative damage of astrocytes was induced at a copper concentration similar to that observed in cerebrospinal fluid (CSF) of patients affected by neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's diseases (PD). Lipoprotein particles similar for density and chemical composition to plasma HDL were recently isolated in human CSF, therefore, the protective role exerted by HDL against Cu(++)-induced oxidative damage of astrocytes could be of physiological relevance.

Astrocytes↗
PubMed2004

2-ClATP exerts anti-tumoural actions not mediated by P2 receptors in neuronal and glial cell lines.

We investigated the effects of the ATP analogue and P2 receptor agonist 2-ClATP on growth and survival of different neuronal (PC12, PC12nnr5 and SH-SY5Y) and glial (U87 and U373) cell lines, by the use of direct count of intact nuclei, fluorescence microscopy, fluorescence-activated cell sorter analysis (FACS) and high pressure liquid chromatography (HPLC). 2-ClATP lowered the number of cultured PC12nnr5, SH-SY5Y, U87 and U373 cells to almost 5%, and of PC12 cells to about 35% after 3-4 days of treatment. EC(50) was in the 5-25 microM range, with 2-ClATP behaving as a cytotoxic or cytostatic agent. Analysis of the biological mechanisms demonstrated that pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (P2 receptor antagonist and nucleotidases inhibitor), but not Caffeine or CGS-15493 (P1 receptor antagonists) effectively prevented 2-ClATP-induced toxicity. 2-ClATP metabolic products (2-ClADP, 2-ClAMP, 2-Cladenosine) and new synthesis derivatives (2-CldAMP, 2-Cldadenosine-3',5'-bisphosphate and 2-CldATP) exerted similar cytotoxic actions. Inhibition of both serum nucleotidases and purine nucleoside transporters strongly reduced 2-ClATP-induced cell death, which was conversely increased by the nucleotide hydrolyzing enzyme apyrase. The adenosine kinase inhibitor 5-iodotubericidin totally prevented 2-ClATP or 2-Cladenosine-induced toxicity. In summary, our findings indicate that 2-ClATP exerts either cell cycle arrest or cell death, acting neither on P2 nor on P1 receptors, but being extracellularly metabolized into 2-Cladenosine, intracellularly transported and re-phosphorylated.

2-Chloroadenosine↗
PubMed2005

Aptameric GT oligomers need to be complexed to ethoxylated polyethylenimine as pre-paired duplexes to efficiently exert their cytotoxic activity in human lymphoblastic cancer cells.

The aptameric oligonucleotides GT were found to exert a selective, specific and dose-dependent cell growth inhibition effect on a variety of human cancer cells by recognising specific nuclear proteins and among these in particular an isoform of the eukaryotic elongation factor 1A1 (EEF1A1). The potential development of these aptameric oligomers needs that they retain serum and intracellular stabilities. Polycations are safe non-viral carriers of the nucleic acids. We demonstrated that a weakly basic polycation, the ethoxylated polyethylenimine (EPEI), can efficiently deliver cytotoxic GT oligomers when they were complexed as partial pre-paired duplex. In this way, nuclease-resistance of the oligomer was markedly improved and the administration of the duplex complexed with EPEI to lymphoblastic cancer cells caused a specific cytotoxic effect at concentrations lower than that of naked GT. However, the cytotoxic activity of the oligomer-EPEI complex resulted strictly related to the GC content and Tm of the duplex region. The single-stranded GT and the duplex with high GC content and Tm, although complexed with EPEI failed to exert cytotoxicity. Overall results indicated that aptameric oligomers complexed with polycations can be efficiently delivered into the cells and display the desired biological effect designing a balanced partial duplex whose stability can allow oligomer release from the polycation under the physiological cellular conditions.

Base Sequence↗
PubMed2006

Pharmacological induction of heat shock protein exerts neuroprotective effects in experimental intracerebral hemorrhage.

Heat shock proteins (HSPs) are reported to reduce inflammation and apoptosis in a variety of brain insults. Geranylgeranylacetone (GGA), developed as an antiulcer in Japan, has been known to induce HSP70 and to exert cytoprotective effects. In this study, we investigated whether GGA, as a specific HSP inducer, exerts therapeutic effects in experimentally induced intracerebral hemorrhage (ICH). ICH was induced with male Sprague-Dawley rats via the collagenase infusion. GGA (800 mg/kg) was administered via oral tube according to various schedules of treatment. The treatment with GGA, beginning before the induction of ICH and continuing until day 3, showed the reduction of brain water content and the increased level of HSP70 protein, as compared to the treatment with vehicle, although GGA started after the induction of ICH or administered as a single dose before ICH failed to up-regulate HSP70 and to reduce brain edema. The rats treated with GGA exhibited better functional recovery than those treated with vehicle. In the pre- and post- treatment group, inflammatory cells and cell death in the perihematomal regions were found to have been decreased. The treatment of GGA inhibited the mRNA expression of MMP-9, uPA, IL-6 and MIP-1, with concomitant increment of eNOS and phosphorylated STAT3 and Akt after ICH. We demonstrated that GGA induced a reduction in the brain edema along with marked inhibitory effects on inflammation and cell death after ICH.

Analysis of Variance↗
PubMed2005

The red wine polyphenol, resveratrol, exerts acute direct actions on guinea-pig ventricular myocytes.

Epidemiological evidence suggests that moderate consumption of red wine may be cardioprotective, although the precise mechanism(s) responsible remains poorly understood. We hypothesized that the red wine polyphenol, resveratrol, may exert direct actions on the heart and thus potentially contribute to cardioprotection. We show that resveratrol acutely decreases Ca2+ transient amplitude in isolated cardiac myocytes. Intriguingly, resveratrol simultaneously increases cell shortening in half the cells tested, while decreasing shortening in the other half. The former could be attributed to heightened myofilament Ca2+ sensitivity. This was no longer observed in myocytes that had been incubated with the oestrogen receptor antagonist, ICI 182,780, suggesting an oestrogen-receptor dependent mechanism of action. In addition, resveratrol significantly decreased action potential duration and the peak L-type Ca2+ current. Our findings provide evidence that resveratrol exerts multiple direct actions on cardiac myocytes, the net result of which is no overall change in cell contraction. The clinical significance of these results remains to be determined.

Animals↗
PubMed2004

Cortistatin-17 and -14 exert the same endocrine activities as somatostatin in humans.

Cortistatin (CST) is a neuropeptide, which binds with high affinity all somatostatin (SS) receptor subtypes and shows high structural homology with SS itself. A receptor specific for CST only, i.e., not recognized by SS, has been recently described in agreement with data reporting that not all CST actions are shared by SS. Interestingly, CST but not SS also binds ghrelin receptor (GHS-R1a) in vitro, suggesting a potential interplay between CST and ghrelin system. The aim of this study was to investigate in humans the endocrine and metabolic activities of human CST-17 in comparison with rat CST-14 that has previously been shown to exert the same endocrine actions of SS in healthy volunteers. To this aim, in six healthy male volunteers (age [median, 3rd-97th centiles]: 28.5; 23.6-34.3 years; Body Mass Index: 23.5; 21.0-25.1 kg/m(2)), we studied the effects of human CST-17 (2.0 microg/kg/h iv over 120 min), rat CST-14 (2.0 microg/kg/h iv over 120 min) and SS-14 (2.0 microg/kg/h iv over 120 min) on: (a) spontaneous GH, ACTH, PRL, cortisol, insulin and glucose levels; (b) the GH responses to GHRH (1.0 microg/kg iv at 0 min); (c) the GH, PRL, ACTH, cortisol, insulin and glucose responses to ghrelin (1.0 microg/kg iv at 0 min). CST-17 inhibited (p < 0.01) basal GH secretion to the same extent of CST-14 and SS-14. Spontaneous PRL, ACTH and cortisol secretion were not significantly modified by CST-17, CST-14 or SS-14. CST-17 as well as CST-14 and SS-14 also inhibited (p < 0.05) spontaneous insulin secretion to a similar extent. None of these peptides modified glucose levels. The GH response to GHRH was inhibited to the same extent by CST-17 (p < 0.01), CST-14 (p < 0.01) and SS-14 (p < 0.05 ). The ghrelin-induced GH response was higher than that elicited by GHRH (p < 0.01) and inhibited by CST-17 (p < 0.05) as well as by CST-14 (p < 0.05) and SS-14 (p < 0.01). The PRL, ACTH and cortisol responses to ghrelin were unaffected by CST-17, CST-14 or SS-14. On the other hand, the inhibitory effect of ghrelin on insulin levels was abolished by CST-17, CST-14 or SS-14 (p < 0.05) that, in turn, did not modify the ghrelin-induced increase in glucose levels. In conclusion, this study demonstrates that human CST-17 and rat CST-14 exert the same endocrine activities of SS in humans. The endocrine actions of human and rat CST therefore are likely to reflect activation of classical SS receptors.

Adult↗
PubMed2006

Influence of the moment exerted by the athlete on the pole in pole-vaulting performance.

Current studies on pole-vaulting focus mostly on energy transfer data [Ekevad, M., Lundberg, B., 1995. Simulation of "smart" pole vaulting. Journal of Biomechanics 28, 1079-1090; Ekevad, M., Lundberg, B., 1997. Influence of pole length and stiffness on the energy conversion in pole-vaulting. Journal of Biomechanics, 30, 259-264; Linthorne, N.P., 2000. Energy loss in the pole vault take-off and the advantage of the flexible pole. Sports Engineering 3, 205-218; Schade, F., Arampatzis, A., Bruggemann, G.P., 2006. Reproducibility of energy parameters in the pole vault. Journal of Biomechanics 39, 146-147.] and often fail to take into account the actions exerted on the pole [Arampatzis, Schade, Bruggemann, 2004. Effect of the pole-human body interaction on pole-vaulting performance. Journal of Biomechanics 37, 1353-1360]. The present study integrates the 3D kinematics data of the athlete but also the actions measured at the end of the pole in the planting box and on the track during the last stride before take-off. It proposes a mechanical model allowing determination of the pole-vaulter's actions on the pole. The model is based on a global mechanical approach. The pole-vaulter's action on his upper and lower hand is concentrated on one middle point to solve the dynamics problem. The model was applied to seven experienced pole-vaulters. The force and the moment exerted on the pole by the pole-vaulter during the last stride before take off and during jump stage, were calculated. This analysis of the compressive force and bending moment for seven pole-vaulters helps to highlight the impact of the moment in the performance. The conclusion is confirmed by an additional comparative study carried out on two pole-vaulters, with comparable morphologies and performing with the same pole.

Biomechanical Phenomena↗
PubMed2006

Fluvoxamine, a selective serotonin reuptake inhibitor, exerts its antiallodynic effects on neuropathic pain in mice via 5-HT2A/2C receptors.

There is an association between depression and chronic pain, and some antidepressants exert antinociceptive effects in humans and laboratory animals. We examined the effects of fluvoxamine, a selective serotonin reuptake inhibitor, on mechanical allodynia and its mechanism of action in the mouse chronic pain model, which was prepared by partially ligating the sciatic nerve. The antiallodynic effect was measured using the von Frey test. Fluvoxamine produced antiallodynic effects following both systemic and intrathecal administration. In 5-hydroxytryptamine (5-HT)-depleted mice, prepared by intracerebroventricular injection of 5,7-dihyroxytryptamine, the fluvoxamine-induced antiallodynic effect was significantly attenuated. The antiallodynic effects of systemic fluvoxamine were also reduced by both systemic and intrathecal administration of ketanserin, a 5-HT2A/2C receptor antagonist. In addition, fluvoxamine also induced antinociceptive effect in the acute paw pressure test, and this effect was antagonized by the 5-HT3 receptor antagonist granisetron. These results indicate that fluvoxamine exerts its antiallodynic effects on neuropathic pain via descending 5-HT fibers and spinal 5-HT2A or 5-HT2C receptors, and the antinociception on acute mechanical pain via 5-HT3 receptors.

Analysis of Variance↗
PubMed2007

Expression of short hairpin RNAs against the coxsackievirus B3 exerts potential antiviral effects in Cos-7 cells and in mice.

Chemically synthesized small interfering RNA (siRNA) has been used as an anti-coxsackievirus B3 (CVB3) agent. Herein, we investigated whether vector-derived short hairpin RNAs (shRNA) targeting CVB3 can exert antiviral activities, prior to their further application to viral vector system for efficient in vivo administration. Employing transient transfection assays to in vivo mouse models as well as to in vitro Cos-7 cell cultures, we directly demonstrated the potential antiviral activity of shRNAs following challenges with infectious CVB3. Of the six shRNAs that we designed, three prevented cell death from CVB3 infection by suppressing viral replication and viral production in Cos-7 cells. These were shRNA 2, which targeted the capsid protein VP1, and shRNAs 4 and 5, which targeted two different regions of the RNA-dependent RNA polymerase 3D. Furthermore, shRNAs 2 and 5 also exerted strong antiviral effects in viral replication in vivo, accompanied by attenuated pancreatic tissue damage. Through this direct evaluation system we addressed the development and application of vector-derived shRNAs as an anti-CVB3 agent, revealing new target sequences.

Animals↗
PubMed1977

Exertional hypotension and postexertional ventricular fibrillation in stress testing.

Six men, clinically diagnosed as having coronary heart disease, had postexertional ventricular fibrillation after maximal exercise testing. The common featureof their treadmill performance was "exertional hypotension," that is, a decrease or a limited increase (10 mm Hg) in systolic blood pressure. All six men were successfully resuscitated with electircal defibrillation. The major indication for electrocardiographic monitoring is the detection of major ventricular arrhythmias and changes in QRS-ST-T of acute myocardial infarction or severe ischemia, all of which are urgent indications for stopping exertion. Close supervision both during and after exercise testing is essential, particularly in men with severe coronary artery disease; monitoring of changes in systolic pressure during and shortly after exercise testing is as important as searching for changes in the -S-T segment.

Adult↗
PubMedDate not supplied

Evaluating the effects of interface factors on the torque exertion capabilities of operating handwheels.

This study intends to assess factors affecting human torque exertion capabilities of operating valve handwheels (maximum volitional torque exertion of wrist radial/ulnar deviation, R/U MVTE). Forty student subjects (20 males and 20 females) participated in this study. In addition to gender and subject factors, gloves (one layer of cotton, two layers of cotton and rubber gloves), operating height (elbow, shoulder and overhead), handwheel size and shape were selected. Barehanded condition was also involved. The results indicate that all the main effects and the first order interactions were significant. The gloved R/U MVTEs were found to be greater than the barehanded R/U MVTE. For operating height, shoulder height gave the greatest R/U MVTE, followed by elbow and overhead heights. The handwheel diameters ranging from 75 to 95 mm for males and 65 to 80 mm for females were found to have the greater R/U shear force. The average R/U MVTE of operating valve handwheel for females was about 63% (3.8/6.05) of that of males.

Accidents, Occupational↗
PubMed1999

Thiol and redox reactive agents exert different effects on glutathione metabolism in HeLa cell cultures.

Glutathione protects cells against oxidative damage, free radical damage and other types of toxicity. The aim of the present study was to investigate the impact on glutathione metabolism exerted by different thiol or redox reactive agents. Intracellular concentrations of glutathione in HeLa cell cultures were lowered after addition of agents mainly exerting oxidative stress (homocysteine and hydrogen peroxide), whereas thiol reactive oxidative agents (mercury ions, copper ions and hydroquinone) in concentrations not affecting cell growth seemed to stimulate the production of glutathione. Possibly, the thiol reactive agents decrease the concentration of glutathione, thereby stimulating further synthesis of glutathione, since glutathione synthesis is subject to feedback regulation by glutathione on gamma-glutamylcysteine synthase. Redox changes after addition of thiol and redox reactive agents were also investigated. Copper ions lowered the concentrations of reduced forms of all extracellular thiols and of intracellular reduced cysteine in HeLa cell cultures. The addition of mercury ions, hydroquinone, homocysteine or hydrogen peroxide did not change the proportions between reduced and total thiol concentrations. After addition of buthionine sulfoxime, the total concentrations of intra- and extracellular glutathione were markedly decreased and the ratio between reduced and total glutathione concentrations was lowered. However, both cysteine and homocysteine exhibited normal ratios between the concentrations of reduced and total thiols in the presence of buthionine sulfoxime. This finding could be due to other cellular antioxidants, such as thioredoxin, ascorbic acid or tocopherols, maintaining redox status of these thiols.

Antioxidants↗
PubMed1980

Culture medium components modify the effects exerted by alpha-fetoprotein (AFP) on lymphocyte response.

Incorporation of [methyl-3H]thymidine to DNA of lymphocytes cultured in the presence of various concentrations of alpha-fetoprotein (AFP) from human cord blood serum was investigated. It was found that AFP by itself does not exert mitogenic effects. In phytohemagglutinin (PHA) stimulated cultures it may inhibit DNA biosynthesis or exert augmentative effects on this process dependent on the composition of the culture medium.

Animals↗
PubMed2001

AFM force measurements on microtubule-associated proteins: the projection domain exerts a long-range repulsive force.

Microtubule-associated proteins (MAPs) are thought to control spacing between microtubules. We propose that the projection domain is largely unstructured and exerts a long-range repulsive force that is predominantly entropic in origin, providing a physical mechanism for maintaining spacing. To test this hypothesis, we developed an experimental system where MAPs are electrostatically end-attached to a flat surface, such that the projection domains extend away from the surface. Atomic force microscopy force measurements on this system show that projection domains exert a long-range (>100 nm) repulsive force. This force depends on the ionic strength of the solution in a way that is consistent with a polyelectrolyte polymer brush.

Animals↗
PubMed2003

Hydrodynamic drag force exerted on activated sludge floc at intermediate Reynolds number.

We hung the activated sludge flocs on an elastic nylon stick and then subjected it to a uniform water flow and measured its displacement. The hydrodynamic drag force exerted on the floc was subsequently estimated, both for cationic flocculated flocs and for flocculated and then frozen/thawed flocs. A confocal laser scanning microscope (CLSM) was employed to probe the interior structure of flocs. Polyelectrolyte flocculation leads to a compact global structure, and hence high drag force exerted on the floc by water. The corresponding C(D)Omega value at Re=12-27 for flocs ranges from 1.58 to 3.61. Fast freezing would little affect the hydrodynamic drag force. Slow freezing, in contrast, considerably consolidated the floc structure and hence presented impermeable sphere-like behavior of the slowly frozen/thawed flocs.

Journal Article↗
PubMed1991

Cough, exertional, and other miscellaneous headaches.

We have discussed several miscellaneous headache disorders not associated with structural brain disease. The first group included those headaches provoked by "exertional" triggers in various forms. These include benign cough headache, BEH, and headache associated with sexual activity. The IHS diagnostic criteria were discussed. Benign exertional headache and cough headache were discussed together because of their substantial similarities. In general, BEH is characterized by severe, short-lived pain after coughing, sneezing, lifting a burden, sexual activity, or other similar brief effort. Structural disease of the brain or skull was the most important differential diagnosis for these disorders, with posterior fossa mass lesions being identified as the most common organic etiology. Magnetic resonance imaging with special attention to the posterior fossa and foramen magnum is the preferred method for evaluating these patients. Indomethacin is the treatment of choice. The headache associated with sexual activity is dull in the early phases of sexual excitement and becomes intense at orgasm. This headache is unpredictable in occurrence. Like BEH, the headache associated with sexual activity can be a manifestation of structural disease. Subarachnoid hemorrhage must be excluded, by CT scanning and CSF examination, in patients with the sexual headache. Benign headache associated with sexual activity has been successfully treated with indomethacin and beta-blockers. The second miscellaneous group of headache disorders includes those provoked by eating something cold or food additives, and by environmental stimuli. Idiopathic stabbing headache does not have a known trigger and appears frequently in migraineurs. Its occurrence may also herald the termination of an attack of cluster headache. Indomethacin treatment provides significant relief. Three headaches triggered by substances that are eaten were reviewed: ingestion of a cold stimulus, nitrate/nitrite-induced headache, and MSG-induced headache. For the most part, avoidance of these stimuli can prevent the associated headache. Lastly, we reviewed headache provoked by high altitude and hypoxia. The headache is part of the syndrome of AMS during its early or benign stage and the later malignant stage of HACE. The pain can be exacerbated by exercise. The best treatment is prevention via slow ascent and avoidance of respiratory depressants. Acetazolamide and dexamethasone have proved useful in preventing this syndrome.

Altitude↗
PubMed2000

Evidence that total extract of Hypericum perforatum affects exploratory behavior and exerts anxiolytic effects in rats.

Clinical trials have extensively reported the ability of Hypericum perforatum extracts to exert a significant antidepressant activity. Hypericin, the main constituent of H. perforatum extract, is no more regarded as the active principle of the antidepressant activity of the drug. Hence, the question of which constituents are involved in the basic activity of the total extract, is still waiting for an answer. In the present study we focused our attention on the potential anxiolytic activity of H. perforatum total extract, and of some pure components such as protohypericin and a fraction containing hypericin and pseudohypericin. Herein we report that the total extract of H. perforatum increases the locomotor activity in the open field and exerts anxiolytic activity in the light-dark test, whereas the single components did not show any effect. Interestingly, the anxiolytic activity of the total extract was blocked by pretreatment of rats with the benzodiazepine antagonist Flumazenil, hence suggesting an implication of benzodiazepine receptor activation in the anxiolytic effect of H. perforatum extract. Electrophysiological studies, performed to gain more information on the mechanism of action, showed that hypericin reduced the GABA-activated chloride currents, while pseudohypericin did an opposite effect. Furthermore, both hypericin and pseudohypericin inhibited the activation of NMDA receptors.

Animals↗