Effect of post-trochanteric groove support on stance control associated with the pelvic-lumbar system: A preliminary study.

BACKGROUND: Many stroke and neuromuscular patients with paraplegia or severe hemiparesis cannot control trunk balance. OBJECTIVE: To support the pelvis/hip of paresis patients, a new pelvic/hip support system was developed bearing a convex pressing member placed over the post-trochanteric groove, a cutaneous landmark sited on the lateral portion of the gluteus maximus muscle and indicating the posterior aspect of the greater trochanter. STUDY DESIGN: Preliminary study. METHODS: Stance control differences in two paretic patients (Guillain-Barré syndrome and stroke sequelae) with or without post-trochanteric groove support were examined. The contact pressure on the post-trochanteric groove was examined in eight healthy volunteers using an impact force sensor. The pelvic-lumbar movement was also examined using three-dimensional motion analysis, and the gluteus muscles activity was evaluated using surface electromyography. RESULTS: Without post-trochanteric groove support, total three-dimensional displacement of the sacral marker was longer in the paresis patients than in normal controls, while post-trochanteric groove support decreased this distance. Post-trochanteric groove support provided compression pressure on the post-trochanteric groove, and all subjects showed a more upright trunk position, providing more anterior pelvic tilting. Six of eight subjects showed increased lumbar lordosis. Five of eight subjects showed gluteus maximus and/or gluteus medius muscle activation. CONCLUSION: The mechanisms of post-trochanteric groove support were suggested to be spino-pelvic coordination and gluteal muscle activation. CLINICAL RELEVANCE: The post-trochanteric groove is a cutaneous landmark located behind the pelvis/hip joint. Applying pressure to the post-trochanteric groove from behind pushes the trunk to adopt a more upright position, leading to improved stance control. Underlining mechanisms appear to be spino-pelvic coordination and gluteal muscle activation.

Necrotic pathway in human osteosarcoma Saos-2 cell death induced by chloroacetaldehyde.

Chloroacetaldehyde, a metabolite of the anticancer drug ifosfamide, may be responsible for serious adverse effects like encephalopathy in ifosfamide chemotherapy. In this study, we demonstrate that chloroacetaldehyde, but not ifosfamide, induces cell death in human osteosarcoma Saos-2 cells and we investigated the mechanism by which this occurs. Chloroacetaldehyde above 30 micromol/l induced significant cell death in a time-dependent manner. Thiol compounds such as N-acetyl cysteine, glutathione and dithiothreitol protected the cells against chloroacetaldehyde-induced cell death, although other nonthiol compounds and the antioxidative enzymes superoxide dismutase and catalase did not, suggesting that reactive oxygen species might not mediate cell death. In cells exposed to chloroacetaldehyde, levels of both total thiols and glutathione were significantly reduced. Chloroacetaldehyde also collapsed the mitochondrial membrane potential of these cells, induced the release of cytochrome c from mitochondria to the cytosol and significantly reduced cellular ATP levels during the course of death. The mitochondrial potential collapse was also prevented by thiol compounds. Flow cytometric analyses by means of annexin-V and propidium iodide double staining and immunofluorescence staining of active caspase-3 revealed that cells subjected to a lethal dose of chloroacetaldehyde displayed features characteristic of necrosis and that caspase-3 was not activated in response to chloroacetaldehyde. Taken together, these findings suggest that Saos-2 cells exposed to chloroacetaldehyde die by necrosis resulting from a decrease in intracellular thiols, disruption of the mitochondrial membrane potential and the depletion of cellular ATP.

Ascorbate-mediated iron release from ferritin in the presence of alloxan.

Release of iron from ferritin requires reduction of ferric to ferrous iron. The iron can participate in the diabetogenic action of alloxan. We investigated the ability of ascorbate to catalyze the release of iron from ferritin in the presence of alloxan. Incubation of ferritin with ascorbate alone elicited iron release (33 nmol/10 min) and the generation of ascorbate free radical, suggesting a direct role for ascorbate in iron reduction. Iron release by ascorbate significantly increased in the presence of alloxan, but alloxan alone was unable to release measurable amounts of iron from ferritin. Superoxide dismutase significantly inhibited ascorbate-mediated iron release in the presence of alloxan, whereas catalase did not. The amount of alloxan radical (A.(-)) generated in reaction systems containing both ascorbate and alloxan decreased significantly upon addition of ferritin, suggesting that A.(-) is directly involved in iron reduction. Although release of iron from ferritin and generation of A.(-) were also observed in reactions containing GSH and alloxan, the amount of iron released in these reactions was not totally dependent on the amount of A.(-) present, suggesting that other reductants in addition to A.(-) (such as dialuric acid) may be involved in iron release mediated by GSH and alloxan. These results suggest that A.(-) is the main reductant involved in ascorbate-mediated iron release from ferritin in the presence of alloxan and that both dialuric acid and A.(-) contribute to GSH/alloxan-mediated iron release.

Requirement of intracellular free thiols for hydrogen peroxide-induced hypertrophy in cardiomyocytes.

Reactive oxygen species (ROS) are by-products of aerobic metabolism and are implicated in the pathogenesis of several diseases. H(2)O(2) produces oxidative stress and acts as a second messenger in several cell types. We tested whether the effect of H(2)O(2) on cellular events could be altered by changes in the intracellular redox status in a cardiomyocyte cell line. Using flow cytometric measurements, we found that adding H(2)O(2) induced hypertrophy in control cells in a time-dependent manner. Pre-incubation of the cells with buthionine sulfoximine (BSO), an inhibitor of de novo GSH synthesis, induced increase in the number of cells of small sizes by the addition of H(2)O(2) as compared to non-BSO pre-incubated control cells, and exacerbated the decrease in viability. Total thiol and GSH levels in H9c2 cells pre-incubated with BSO were about 75 and 30% of control, respectively, and GSH levels fell to below the limitation of detection after the addition of H(2)O(2), although total thiol levels were not markedly decreased. In the cells pre-incubated with BSO, hypertrophy was not observed by the addition of H(2)O(2) at any level of concentration. N-acetyl-L-cysteine and cysteine not only prevented increase in the number of cells of small sizes caused by H(2)O(2) but also induced hypertrophy in cells pre-incubated with BSO. These results suggest that the intracellular free thiol levels determine whether cell death or hypertrophy occurs in cardiomyocytes in the presence of H(2)O(2). On the other hand, the hypertrophied cells did not become larger by adding H(2)O(2), but had high levels of cellular GSH, suggesting the possibility that the hypertrophied cells have tolerance to oxidative stress.

[Alloxan radical-induced generation of reactive oxygen species in the reaction system of alloxan with ascorbate].

The diabetogenic action of alloxan is thought to be initiated by generation of reactive oxygen species (ROS). Ascorbate can be an antioxidant in a predominantly aqueous environment, such as plasma and extracellular fluids. We have investigated the generation of ROS in the interaction of alloxan with ascorbate. Rapid oxygen consumption was observed in the reactin system of alloxan with ascorbate. The oxygen consumption was suppressed by superoxide dismutase and catalase, suggesting that superoxide and hydrogen peroxide could be generated in the reaction system. In addition, the generation of alloxan radical, an electron reductance of alloxan, and ascorbate free radical (AFR), an electron oxidant of ascorbate, was observed using electron spin resonance (ESR). Under anaerobic conditions, the ESR signal intensity of alloxan radical was significantly increased in comparison with that under aerobic conditions, whereas the intensity of AFR was significantly decreased. These results suggest that alloxan radical and AFR were generated in the reaction system of alloxan with ascorbate, and that the alloxan radical but not AFR reacted with molecular oxygen, resulting in the generation of ROS.

Lipid peroxidation induced by phenylbutazone radicals.

Lipid peroxidation was investigated to evaluate the deleterious effect on tissues by phenylbutazone (PB). PB induced lipid peroxidation of microsomes in the presence of horseradish peroxidase and hydrogen peroxide (HRP-H2O2). The lipid peroxidation was completely inhibited by catalase but not by superoxide dismutase. Mannitol and dimethylsulfoxide had no effect. These results indicated no paticipation of superoxide and hydroxyl radical in the lipid peroxidation. Reduced glutathione (GSH) efficiently inhibited the lipid peroxidation. PB radicals emitted electron spin resonance (ESR) signals during the reaction of PB with HRP-H2O2. Microsomes and arachidonic acid strongly diminished the ESR signals, indicating that PB radicals directly react with unsaturated lipids of microsomes to cause thiobarbituric acid reactive substances. GSH sharply diminished the ESR signals of PB radicals, suggesting that GSH scavenges PB radicals to inhibit lipid peroxidation. Also, 2-methyl-2-nitrosopropan strongly inhibited lipid peroxidation. R-Phycoerythrin, a peroxyl radical detector substance, was decomposed by PB with HRP-H2O2. These results suggest that lipid peroxidation of microsomes is induced by PB radicals or peroxyl radicals, or both.

Lipid peroxidation induced by indomethacin with horseradish peroxidase and hydrogen peroxide: involvement of indomethacin radicals.

Some of the side-effects of using indomethacin (IM) involve damage to the gastric mucosa and liver mitochondria. On the other hand, neutrophils infiltrate inflammatory sites to damage the tissues through the generation of reactive oxygen species by myeloperoxidase. The stomach and intestine have large amounts of peroxidase. These findings suggest that peroxidases are involved in tissue damage induced by IM. To clarify the basis for the tissue damage induced by IM in the presence of horseradish peroxidase (HRP) and H2O2 (HRP-H2O2), lipid peroxidation was investigated. When IM was incubated with liver microsomes in the presence of HRP-H2O2 and ADP-Fe3+, lipid peroxidation was time-dependent. Catalase and desferrioxamine almost completely inhibited lipid peroxidation, indicating that H2O2 and iron are necessary for lipid peroxidation. Of interest, superoxide dismutase strongly inhibited lipid peroxidation, and it also inhibited the formation of bathophenanthroline-Fe2+, indicating that reduction of the ferric ion was due to superoxide (O2-). ESR signals of IM radicals were detected during the interaction of IM with HRP-H2O2. However, the IM radical by itself did not reduce the ferric ion. These results suggest that O2- may be generated during the interaction of IM radicals with H2O2. Ferryl species, which are formed during the reduction of iron by O2-, probably are involved in lipid peroxidation.

Inactivation of creatine kinase induced by stilbene derivatives.

Compounds acting as antioxidants to lipids often have a prooxidant effect on DNA or protein. In this study, inactivation of creatine kinase was examined as an indicator of protein damage induced by antioxidative stilbene derivatives, including diethylstilboestrol, resveratrol and tamoxifen, with horseradish peroxidase and hydrogen peroxide (horseradish peroxidase-H2O2). Diethylstilboestrol and resveratrol, but not tamoxifen, rapidly inactivated creatine kinase. Also, creatine kinase in heart homogenate was inactivated by diethylstilboestrol and resveratrol. Tamoxifen, which has no phenolic hydroxyl groups in its structure, was about 10 times less active in protecting lipids and creatine kinase than diethylstilboestrol and resveratrol, suggesting that phenolic hydroxyl groups in diethylstilboestrol and resveratrol of stilbene derivatives are anti- and pro-oxidative. Absorption spectra of these stilbene derivatives rapidly changed during the reaction with horseradish peroxidase-H202. Diethylstilboestrol and resveratrol free radicals emitted electron spin resonance signals and creatine kinase effectively diminished the electron spin resonance signals. These results suggest that free radicals of diethylstilboestrol and resveratrol formed through reaction with horseradish peroxidase-H202 inactivated creatine kinase. Presumably, oxidation of essential cysteine and tryptophan residues lead to inactivation of creatine kinase. Other enzymes, including alcohol dehydrogenase and cholinesterase, were also sharply inhibited by diethylstilboestrol and resveratrol with horseradish peroxidase-H202. Free radicals of diethylstilboestrol and resveratrol seem to mediate between anti- and prooxidative actions.