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Biomedical subjects

K Asayama

Publications and source records attributed to K Asayama.

At least 109 records · Page 6Linked to original sources
PubMed1989

Antioxidant enzyme status and lipid peroxidation in various tissues of diabetic and starved rats.

The effect of short term (2-wk) diabetes induced by streptozotocin and starvation (1-wk) on antioxidant enzymes and lipid peroxidation in the liver, kidney and heart of rats was investigated. The activity of mitochondrial oxidative markers was increased in diabetic liver and kidney, while the activity in tissues of starved rats tended to be decreased. Immunoreactive manganese superoxide dismutase was increased only in diabetic liver and was unchanged or decreased in the rest of the tissues. Glutathione peroxidase activity was increased in tissues of diabetic but not starved rats. The changes in copper-zinc superoxide dismutase and catalase in diabetic rats were similar to those in starved rats. In both groups, copper-zinc superoxide dismutase was decreased in liver, while catalase activity was decreased in liver and kidney, and increased in heart. The lipid peroxide level was increased in diabetic kidney and in the heart of starved rats, and decreased in the rest of the tissues. Insulin treatment in diabetic rats and refeeding in starved rats restored most of the abnormalities toward normal. These results suggest that accelerated mitochondrial oxidative metabolism not accompanied by induction of manganes superoxide dismutase results in oxidative injury in the hypertrophied kidney at an early stage of diabetes and possibly contributes to the development of nephropathy. Peroxidative myocardial damage in starved rat appears to be mediated by a catabolic process.

Animals↗
PubMed1988

Involvement of fibronectin in in vitro regeneration of retinal pigment epithelium.

Argon laser photocoagulation was placed on the confluent monolayer of cultured chick retinal pigment epithelial cells as a model of the regeneration process of retinal pigment epithelium after laser burn. The intense fibrillar net immunofluorescent pattern of fibronectin appeared on the burnt area from 2 h after the laser application, before the beginning of tissue reconstruction. Fibronectin was observed for several days, then became undetectable before the complete regeneration of retinal pigment epithelial cells. This indicates that fibronectin is involved in the early regeneration process of retinal pigment epithelium.

Animals↗
PubMed1987

Superoxide dismutases, glutathione peroxidase, and catalase in neuromuscular disease.

Studies in experimental muscular dystrophy indicate a possible role for anomalous redox metabolism in the genesis of these disorders, prompting a retrospective review of changes in redox-active enzymes in Duchenne muscular dystrophy (DMD). Both manganous and copper-zinc superoxide dismutase (Mn and CuZn SOD) content and glutathione peroxidase and catalase activities were measured in muscle biopsy specimens taken from normal individuals and from patients with Duchenne muscular dystrophy and other neuromuscular diseases. Muscle from patients with Duchenne dystrophy differed from the norm in that both Mn SOD and CuZn SOD were decreased and glutathione peroxidase was increased. This profile differed from that in anterior horn cell diseases in that CuZn SOD was not decreased in these disorders and from polymyositis, where CuZn SOD was decreased without an increase in glutathione peroxidase. Thus, there appears to be disease-specific changes in these enzymes in DMD. These data support the concept that changes in redox-active enzymes may be associated with the genesis of DMD.

Adult↗
PubMed1987

Lipid peroxidation and free radical scavengers in thyroid dysfunction in the rat: a possible mechanism of injury to heart and skeletal muscle in hyperthyroidism.

This study was designed to determine if peroxidation of biomembrane lipid and the protective system can be modified by the change in oxidative metabolism induced by thyroid dysfunction. The free radical scavengers (i.e. cuprozinc cytosolic and mangano mitochondrial superoxide dismutases, glutathione peroxidase, and catalase), mitochondrial oxidative marker enzymes (cytochrome c oxidase and fumarase), and lipid peroxide were measured in liver, heart, soleus (slow oxidative), and extensor digitorum longus (fast glycolytic) muscles. Rats were rendered hyper- or hypothyroid for 4 weeks and then killed. Superoxide dismutases were detected by specific RIAs: catalase by polarography, and lipid peroxide by fluorimetry. Hypothyroid rats failed to grow, while hyperthyroid rats had hypertrophied hearts but no growth failure. An increase in lipid peroxide was observed in the soleus and heart muscles of hyperthyroid rats. This was accompanied by an increase in mitochondrial superoxide dismutase and oxidative markers. No such change was observed in either fast glycolytic muscle or liver. Glutathione peroxidase decreased in all tissues of hyperthyroid rats, and there was a parallel decrease in catalase in most tissues. On the other hand, hypothyroidism induced a reduction in oxidative markers and mitochondrial superoxide dismutase in heart and skeletal muscles, but only a marginal change in lipid peroxidation. The cytosolic superoxide dismutase did not change in relation to either oxidative metabolism or lipid peroxidation. These results suggest that the enhanced oxidative metabolism and decreased glutathione peroxidase in hyperthyroidism result in an increase in lipid peroxidation and, in slow oxidative and heart muscle, possible organ damage. No adverse reaction mediated by active oxygen species was found in hypothyroid rat tissues.

Animals↗
PubMed1986

Differential effect of denervation on free-radical scavenging enzymes in slow and fast muscle of rat.

To determine the effect of denervation on the free-radical scavenging systems in relation to the mitochondrial oxidative metabolism in the slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles, the sciatic nerve of the rat was crushed in the midthigh region and the muscle tissue levels of five enzymes were studied 2 and 5 weeks following crush. Recently developed radioimmunoassays were utilized for the selective measurement of cuprozinc (cytosolic) and mangano (mitochondrial) superoxide dismutases. Total tissue content of cuprozinc superoxide dismutase showed a mild decrease after denervation in slow but not in fast muscle. Manganosuperoxide dismutase and fumarase decreased markedly at 2 weeks and returned toward control levels by 5 weeks, the changes appearing to be greater in slow than in fast muscle. At 2 weeks, cytochrome c oxidase decreased significantly in slow, but not in fast muscle. GSH-peroxidase at baseline was 10-fold higher in slow than in fast muscle, markedly decreased at 2 weeks in slow muscle, and returned toward control levels at 5 weeks, whereas the total enzyme activity in fast muscle did not change through 5 weeks. These data represent the first systematic report of free radical scavenging systems in slow and fast muscles in response to denervation. Selective modification of cuprozinc and manganosuperoxide dismutases and differential regulation of GSH-peroxidase was demonstrated in slow and fast muscle.

Animals↗
PubMed1986

Effect of vitamin E deficiency and selenium deficiency on insulin secretory reserve and free radical scavenging systems in islets: decrease of islet manganosuperoxide dismutase.

There is increasing evidence that islet beta cells may be susceptible to redox insult, and that this susceptibility may contribute to the pathogenesis of experimental models of diabetes mellitus. We investigated the effect of vitamin E deficiency, selenium deficiency, and combined deficiency on islet function and free radical scavenging systems. The tissue levels of glutathione peroxidase, catalase, and immunoreactive superoxide dismutases were measured in four groups of rats (i.e., controls and those with vitamin E, selenium, and combined deficiency). Glucose tolerance tests were performed for each animal before sacrifice. Superoxide dismutase concentrations in liver, heart, and skeletal muscle were within 20% of the control levels in all groups. However, the manganosuperoxide dismutase concentrations in islets were significantly lower than control levels in response to vitamin E, selenium, and combined deficiency. Combined deficiency appeared to have an additive effect. In contrast, cuprozinc superoxide dismutase concentration in islets was higher in the deficient groups than in controls. Insulin secretory reserve was decreased in each of the three deficient groups. This decrease was reflected as glucose intolerance only in the group with combined deficiency. Glutathione peroxidase activity was markedly decreased in selenium-deficient animals in all tissues studied. Catalase activity did not change significantly among groups in any tissue studied. Islets had the lowest glutathione peroxidase and cuprozinc and total superoxide dismutase levels among tissues studied.

Animals↗
PubMed1985

Rat superoxide dismutases. Purification, labeling, immunoassay, and tissue concentration.

This study determines the validity of utilizing radioimmunoassay of CuZn and Mn superoxide dismutase in the rat for defining mechanism of control over mammalian tissue superoxide dismutase concentrations. To accomplish this, rat Mn and CuZn superoxide dismutase were purified. The CuZn superoxide dismutase dimer had a specific activity of 3600 units/mg of protein and a subunit Mr of 17,000. The Mn superoxide dismutase tetramer had a specific activity of 3700 units/mg of protein and a subunit Mr of 22,000. Both enzymes provided a single discrete protein band on disc gel electrophoresis. The purified enzymes were utilized to develop sensitive (less than 2.5 ng/ml Mn superoxide dismutase and less than 3.12 ng/ml CuZn superoxide dismutase) reproducible immunoassays the specificity of which was confirmed by tissue homogenate dilution and column chromatography. Immunoassay of these enzymes in rat tissues permitted clarification of existing data based on activity assays and demonstrated a trend for higher Mn superoxide dismutase concentrations in tissues of high mitochondrial content (with relative tissue concentrations comparable to man) and low superoxide dismutase concentrations in islets (providing an explanation for their sensitivity to free radical damage). This represents the first report of a radioimmunoassay for rat Mn superoxide dismutase, and the second report of successful purification of rat Mn superoxide dismutase (with higher specific activity and apparent purity and stability). The data support the proposition that these radioimmunoassays in rats will provide a useful system for investigation of mechanisms of control over tissue superoxide dismutase concentrations in mammalian tissues.

Animals↗
PubMed1985

Purification and radioimmunoassays for superoxide dismutases in the mouse: tissue concentrations in different strains.

Both murine cuprozinc and manganosuperoxide dismutases were purified to electrophoretic homogeneity from liver; the former (dimer) had a sp. act. of 2600 U/mg and a subunit mol. wt. of 17,000, the latter (tetramer) 2300 U/mg and mol. wt. 23,000. Heterologous radioimmunoassays had sensitivities of 3.1 ng/ml for the former enzyme and 2.5 ng/ml for the latter, and were appicable across murine genetic lines (Balb/c, ob/ob, db/db). Islets had the lowest concentrations of both enzymes among the tissues studied, and this could explain their vulnerability to free-radical damage.

Animals↗
PubMed1985

Physical fitness of paraplegics in full wheelchair marathon racing.

The wheelchair marathon is one of the most difficult sports for participants with much uncertainty regarding the security of the paraplegics. The physical fitness of paraplegics has been examined regularly since The Oita International Wheelchair Marathon (half marathon) was inaugurated (1981). A full marathon (42.195 km) was adopted at The 3rd Meeting (1983). The individual equations between heart rate (HR) and oxygen consumption VO2 were drawn from the preliminary test on the subjects who were expected to be among the top finishers in these races. VO2 during these races was indirectly estimated and showed a fairly low value (35.0 +/- 3.8 ml/kg/min in the full race, 32.7 +/- 6.3 ml/kg/min in the half race respectively) in comparison with able-bodied elite runners. However, the paraplegic participants had extremely high HR (171.6 +/- 20.5 beats/min, 168.1 +/- 9.8) continuously throughout the race. Though the ratio of active muscle mass of arms to legs in paraplegic athletes may approximate to near equal, paraplegic arms seem to exert physiologically and mechanically less efficient power. There were no significant differences in physical fitness between the full and the half marathon elite finishers. The cardiovascular function of paraplegic athletes may well be ranked among those of able-bodied athletes in their fitness. Full wheelchair marathon seems to be safe if it is held in an appropriate environment.

Adult↗
PubMed1985

Selective induction of manganous superoxide dismutase in human monocytes.

Radioimmunoassays for both human copper-zinc and manganous superoxide dismutases (Cu-Zn SOD and Mn SOD, respectively) have been developed, validated, and utilized to measure the concentrations of these enzymes in cultured monocytes. Monocyte Mn SOD increased 4.7-fold over basal during 3 days of culture, an increase that was markedly enhanced by stimulation with bacterial lipopolysaccharide (LPS). Cu-Zn SOD showed a transient decrease over the culture period but was unaffected by LPS. Stimulation with muramyl dipeptide had minimal effect on Mn SOD and no effect on Cu-Zn SOD during culture, even at a concentration capable of activating the monocytes, as defined by zymosan-induced superoxide production.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

Energy expenditure of paraplegic marathon runners measured during a wheelchair marathon.

Wheelchair bound paraplegics tend to spend a sedentary life. They seem to be vulnerable to prolonged strenuous exertion because of their many physical handicaps such as metabolic depression, cardiovascular instability, urinary incontinence, pressure sores and so on. In commemoration of The International Year of the Disabled, The First Oita International Wheelchair Marathon was held in Autumn of 1981. This paper is to review the results of an experiment made at this half marathon. The course length was 21.1 km. Ten competitors were selected at random as the subjects for measuring energy expenditure during the race. As a preliminary examination, a work load test was performed by using a wheelchair treadmill to obtain a regression equation of the individual relationship between oxygen uptake and heart rates. The oxygen uptake of individuals during the race was estimated from the heart rates which were recorded by the small memory box fixed beneath the wheelchair. Six subjects were successfully examined. The results revealed that paraplegics safely tolerated the prolonged strenuous exercise. Their average oxygen uptake, mean heart rate and the lap time during the race were 34.17 +/- 8.11 ml/kg/min (mean +/- SD), 167.6 +/- 15.8 beats/min and 87.1 +/- 9.1 min respectively. Heart rate of the subjects was always very high during the race, although oxygen consumption was fairly low in comparison to able-bodied elite marathon runners.

Adult↗
PubMed1984

Joint purification of mangano and cuprozinc superoxide dismutases from a single source--a simplified method.

Preliminary studies which raised questions as to the efficacy of ammonium sulfate precipitation in separating mangano from cuprozinc superoxide dismutase and the adequacy of cyanide sensitivity in monitoring such separation led to the use of electrophoresis with activity and protein staining to monitor purification. This, together with exploitation of the differing isoelectric points of the two enzymes permitting separate elution from the same DE-52 column, led to a simplified method for purification of these enzymes using the same starting material and purification steps initially. The specific activity was 2900 and 3200 units/mg protein and yields were 18 and 20% for mangano and cuprozine superoxide dismutase, respectively.

Electrophoresis, Polyacrylamide Gel↗