Masakazu Nagasawa

Chronic corticosteroid administration causes mitochondrial dysfunction in skeletal muscle.

Abstract Corticosteroid myopathy is a major clinical problem in patients undergoing chronic corticosteroid treatment and shows insidious and progressive muscle atrophy in proximal limbs. Although several mechanisms underlying the pathophysiology of muscle injury have been postulated, precise pathogenesis is still not clear. We evaluated the mitochondrial functions in patients receiving corticosteroids compared with those in healthy controls or patients not receiving corticosteroids. The serum levels and total production of lactate were investigated by an aerobic exercise test using a bicycle ergometer. Mitochondrial respiratory activities and oxidative damage in biopsied skeletal muscles were also studied. The results of aerobic exercise tests revealed a significant overproduction of lactate in patients treated with corticosteroids (p < 0.005), which was positively correlated with total corticosteroid doses administered (p < 0.0001). In these patients, mitochondrial enzyme activity in complex I was significantly decreased (p < 0.05) and oxidative damage of biopsied skeletal muscle was remarkable both in mitochondrial and nuclear DNAs (p < 0.001). The results suggest that chronic corticosteroid administration induces mitochondrial dysfunction and oxidative damage in skeletal muscles, which may be the pathogenesis, at least in part, of corticosteroid-induced myopathy.

Neurotrophic sesquiterpene-neolignans from magnolia obovata: structure and neurotrophic activity

Abstract Novel sesquiterpene-neolignans, eudesobovatos A (1) and B (2), eudesmagnolol (3), eudeshonokiols A (4) and B (5), clovanemagnolol (6), and caryolanemagnolol (7), have been isolated from the bark of Magnolia obovata. Their structures were elucidated to be sesquiterpenes (eudesmol, 4,4,8-trimethyltricyclo [6.3.1.02,5] dodecane-1,9-diol, and clovanediol) combined through ether bond with neolignans such as obovatol, honokiol, and magnolol on the basis of spectral data, degradation, and/or synthesis. Compounds 1, 6, and 7 were found to exhibit interesting neurotrophic activity on a neuronal cell culture system derived from fetal rat hemisphere.

Oxidative damage to skeletal muscle DNA from patients with mitochondrial encephalomyopathies

To estimate the oxidative damage to skeletal muscle DNA in mitochondrial encephalomyopathies, we studied the amount of 8-hydroxy-deoxyguanosine (8-OH-dG) and the localization of superoxide dismutase (SOD) in the skeletal muscles of patients with progressive external ophthalmoplegia (PEO) or Kearns-Sayre syndrome (KSS). The molar ratio of 8-OH-dG/deoxyguanosine in skeletal muscle from PEO or KSS patients was significantly higher than the control value. The ratio from patients with polymyositis or Duchennes muscular dystrophy was not significantly elevated. Immunohistochemical staining for both Mn-SOD and Cu,Zn-SOD showed pronounced staining in the subsarcolemmal and intermyofibrillar regions of cytochrome-oxidase-negative ragged red fibers of KSS or PEO muscles. Our findings suggest that overproduction of 8-OH-dG and mitochondrial dysfunction with gene deletions are associated with each other in muscle cells of patients with PEO or KSS, and that free radicals may play an important role in the pathophysiology of mitochondrial encephalomyopathies.

Mitochondrial damage in patients with long-term corticosteroid therapy: development of oculoskeletal symptoms similar to mitochondrial disease

Abstract. Two patients with long-term corticosteroid administration sporadically developed limb muscle wasting followed by ophthalmoplegia, and the skeletal muscle pathology revealed ragged-red fibers (RRFs) with abnormal mitochondria, in addition to the findings of corticosteroid myopathy. The oculoskeletal symptoms of the present cases resemble those of chronic progressive external ophthalmoplegia, a type of mitochondrial disease. The ocular muscles have more RRFs than limb muscles, and large multiple deletions of mitochondrial DNA was detected in ocular and limb muscles of the two patients by PCR but not by Southern blotting. Immunohistochemistry demonstrated that 8-hydroxy-deoxyguanosine (8-OH-dG) and 4-hydroxy-2-nonenal were intensely stained in skeletal muscles of these patients particularly in RRFs. High-performance liquid chromatography with electrochemical detection analysis revealed an increase in 8-OH-dG from mitochondrial DNA. These findings may suggest that long-term corticosteroid administration potentially induces oxidative stress-mediated mitochondrial damage, resulting in the development of the oculoskeletal symptoms in some patients.

Cilostazol inhibits modified low-density lipoprotein uptake and foam cell formation in mouse peritoneal macrophages

Internalization of modified low-density lipoprotein (LDL) via macrophage scavenger receptors (e.g. scavenger receptor A and CD36) is thought to play a crucial role in the development of atherosclerotic lesions. Cilostazol, an antiplatelet agent with selective phosphodiesterase 3 inhibitory action, has been reported to ameliorate atherosclerosis in mouse models. However, the effect of cilostazol on modified LDL uptake in macrophages is not known. Thus, we investigated the effect of cilostazol on LDL uptake in mouse peritoneal macrophages (MPM). Cilostazol significantly inhibited oxidized and acetylated LDL uptake in MPM, while cyclic AMP (cAMP)-elevating agents, db-cAMP and other phosphodiesterase 3 or 4 inhibitors, did not inhibit the uptake. Cilostazol did not change cytosolic cAMP levels in MPM, and a protein kinase A (PKA) inhibitor did not influence the inhibitory effects of cilostazol. Cilostazol decreased scavenger receptor A but not CD36 expression. Moreover, cilostazol significantly inhibited foam cell formation, which was represented by an increase in esterified cholesterol content. In conclusion, cilostazol significantly inhibits the uptake of modified LDL and foam cell formation in mouse peritoneal macrophages, and the inhibitory effect of cilostazol can be induced in a cAMP- and PKA-independent manner.

Novel neurotrophic sesquiterpene-neolignans from magnolia obovata

Abstract Novel sesquiterpene-neolignans, eudesobovatols A (1) and B (2) isolated from Magnolia obovata have been assigned structures on the basis of detailed spectroscopic analyses and chemical degradation, and eudesobovatol A has been found to exhibit neurotrophic activity at 10 −5 M

Effect of Continuous Intravenous Infusion of Carteolol Chloride on Tissue Blood Flow in Rabbit Optic Nerve Head

10 −7 M on neuronal cell culture system of fetal rat cerebral hemisphere.

Determination of the ß-blocker carteolol in human plasma by a sensitive gas chromatographic—negative-ion chemical ionization high-resolution mass spectrometric method

Abstract A new type of sesquiterpenes, illicinolides A (1) and B (2) has been isolated from Illicium tashiroi. The structure of illicinolide A was established by X-ray analysis of the p-bromobenzoyl derivative. Illicinolide B was assigned the structure as 9α-hydroxyillicinolide A by spectral data compared with those of illicinolide A. They are biogenetically closely related to anisatin (3) and its derivative.