The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
Kenichi Kitani - One of the best experts on this subject based on the ideXlab platform.
-
effect of Leupeptin on the lateral mobility of proteins in the plasma membrane of hepatocytes of c57bl 6 mice frap studies on liver smears
Archives of Gerontology and Geriatrics, 1992Co-Authors: Kenichi Kitani, Imre Zs Nagy, Minoru Ohta, Setsuko Kanai, Yuko SatoAbstract:Abstract Four groups of male C57BL/6 mice (ages 2, 3.8, 11.8–12.5 and 24 months) were administered Leupeptin at 5 mg/100 g body weight/day via intraperitoneally implanted osmotic minipumps. Both untreated and saline-treated mice served as controls. The time and dose-dependence of the effects of Leupeptin on the lateral mobility of proteins in hepatocyte surface membranes were analyzed first in mice treated for 2, 5, 8, 11 and 14 days, respectively, by using the fluorescence recovery after photobleaching (FRAP) technique. The age dependence of the response to this treatment was also studied after 14 days of treatment in mice of various ages. The average lateral diffusion constant (D) and the fractional recovery (FR) were measured, and D × FR calculated. Leupeptin treatment at a daily dose of 5 mg/100g for 2 weeks increased plasma glutamic-pyruvlc transaminase levels 2-fold in all age groups. Leupeptin treatment caused a linear increase of D and a decrease of FR with respect to the duration of the treatment in adult mice. In all age groups about 30% of the membrane proteins became immobile after 14 days of treatment, whereas the still mobile fraction displayed a large increase of D. The values of D × FR in the Leupeptin-treated groups were slightly higher than those in the untreated mice until the age of 15 months but decreased after this age. The results are interpreted in terms of the known inhibitory effect of Leupeptin on cytoplasmic and lysosomal thiol proteases, causing a general slowing down of the protein turnover and, specifically, of proteins in the hepatocyte membrane.
-
intraventricular infusion of Leupeptin decreases bmax of the d2 receptor in the striatum of young rats
Life Sciences, 1992Co-Authors: Makiko Shibata, Minoru Ohta, Setsuko Kanai, M Asakura, Anri Aoba, Kazuo Hasegawa, Kenichi KitaniAbstract:Abstract Intraventricular infusion of a thiol protease inhibitor, Leupeptin, was previously shown to induce several morphological and immunochemical manifestations of normal and pathological aging in rat brain. The present study attempted to elucidate whether this treatment also perturbs another brain function which declines in aging, dopamine D2 receptor binding in striatum. Intraventricular infusion of Leupeptin (0.6 mg per day) for two weeks caused a significant (about 20%) reduction in the binding maximum (Bmax) of dopamine D2 receptors (as examined by [ 3 H] spiperone binding) in the striatum of young male Fischer-344 rats in comparison to (saline-infused) control rats. The apparent Kd values did not differ significantly between the control and Leupeptin-treated rat groups. The results suggest that decreased protein turnover may be a factor in the decline in Bmax of D2 receptors during aging.
-
Leupeptin causes an accumulation of lipofuscin like substances in liver cells of young rats
Mechanisms of Ageing and Development, 1991Co-Authors: Setsuko Kanai, Minoru Ohta, Yuko Sato, Koichiro Otsubo, Kenichi KitaniAbstract:Abstract Leupeptin, a thiol protease inhibitor, has previously been shown to cause a dense accumulation of substances resembling age pigment and called ceroid-lipofuscin, in brain cells of young rats [1]. Thus far, however, attempts to produce age pigments in hepatocytes of normal young rats with protease inhibitor(s) have not been successful. The present study provides the first demonstration that Leupeptin induces lipofuscin-like substances in normal young rat hepatocytes. Male Fischer-344 rats (age 4–6 weeks) were continuously infused with Leupeptin or saline i.p. for 2 weeks by an osmotic minipump (dosage, 1–50 mg/100 g per day). Liver tissues were then examined by light, fluorescence and electron microscopy. Both hepatocytes and non-parenchymal cells of livers treated with Leupeptin, but not saline, showed a dense accumulation of pigments which stained deeply with toluidine blue, were PAS-positive and were brightly autofluorescent. After UV excitation the pigments had an emission spectrum with a broad peak at 480–540 nm extending to 650 nm resembling the spectrum of age pigment from livers of normal aged rats. Electron microscopic examination revealed numerous lipofuscin-like deposits with heterogeneous morphology in the cytoplasm of both hepatocytes and non-parenchymal cells; lipid and myelin-like bodies were also present in hepatocytes. The results indicate that the perturbation of proteolytic activity in liver by Leupeptin causes an accumulation of substances which by several criteria resemble lipofuscin. These results thus provide further support for the ‘Protease Inhibitor Model of Lipofuscin Formation’ [2] as well as a potential experimental model for studying hepatocellular aging processes.
Alfred Stracher - One of the best experts on this subject based on the ideXlab platform.
-
Leupeptin reduces impulse noise induced hearing loss
Journal of Occupational Medicine and Toxicology, 2011Co-Authors: Haim Gavriel, Alfred Stracher, Abraham Shulman, Haim SohmerAbstract:Background Exposure to continuous and impulse noise can induce a hearing loss. Leupeptin is an inhibitor of the calpains, a family of calcium-activated proteases which promote cell death. The objective of this study is to assess whether Leupeptin could reduce the hearing loss resulting from rifle impulse noise.
-
Leupeptin protects cochlear and vestibular hair cells from gentamicin ototoxicity
Hearing Research, 2002Co-Authors: Dalian Ding, Alfred Stracher, Richard SalviAbstract:Abstract Calpains, a family of calcium-activated proteases that breakdown proteins, kinases, phosphatases and transcription factors, can promote cell death. Since Leupeptin, a calpain inhibitor, protected against hair cell loss from acoustic overstimulation, we hypothesized that it might protect cochlear and vestibular hair cells against gentamicin (GM) ototoxicity. To test this hypothesis, mouse organotypic cultures from the cochlea, maculae of the utricle and the crista of the semicircular canal (P1–P3) were treated with different doses of GM (0.1–3 mM) alone or in the presence of Leupeptin (0.1–3 mM). The percentage of outer hair cells (OHCs) and inner hair cells (IHCs) decreased with increasing doses of GM between 0.1 and 3 mM. The addition of 1 mM of Leupeptin significantly reduced GM-induced damage to IHCs and OHCs; this protective effect was dose-dependent. GM also significantly reduced hair cell density in the crista and utricle in a dose-dependent manner between 0.1 and 3 mM. The addition of 1 mM of Leupeptin significantly reduced hair cell loss in the crista and utricle for GM concentrations between 0.1 and 3 mM. These results suggest that one of the early steps in GM ototoxicity may involve calcium-activated proteases that lead to the demise of cochlear and vestibular hair cells.
-
Leupeptin protects sensory hair cells from acoustic trauma
Neuroreport, 1999Co-Authors: Jian Wang, Alfred Stracher, Abraham Shulman, Dalian Ding, Richard SalviAbstract:Calpains, a family of calcium activated proteases, promote the breakdown of cellular proteins, kinases, phosphatases and transcription factors. Calpain inhibitors attenuate some neurodegenerative processes in certain cell types. Here we show that Leupeptin, a potent calpain inhibitor, protects the sensory hair cells in the inner ear from acoustic overstimulation (48 h, 100 or 105 dB SPL, octave band noise at 4 kHz). Acoustic overstimulation caused a significant increase in calpain immunolabeling in the sensory epithelium suggesting a possible role in noise-induced cochlear degeneration. Infusion of Leupeptin into the inner ear significantly reduced the amount of sensory cell loss from acoustic overstimulation. However, Leupeptin did not protect against hair cell loss from the ototoxic drug, carboplatin.
-
Neuromuscular recovery after peripheral nerve repair: effects of an orally-administered peptide in a primate model.
Journal of Reconstructive Microsurgery, 1995Co-Authors: Marie A. Badalamente, Lawrence C. Hurst, Alfred StracherAbstract:Oral delivery of the tripeptide calpain inhibitor, Leupeptin, after median nerve transection and epineural nerve repair in primates (Cebus apella) was studied for its potential benefits to neuromuscular recovery. Results of a controlled, dose-response study indicated that Leupeptin was absorbed into plasma by the oral route of administration. When plasma Leupeptin concentrations were 3 μg/ml or greater, morphologic and functional motor recovery were facilitated after nerve repair. Serial testing in hematology, clotting, and serum biochemistry showed that there were no adverse effects, when Leupeptin was administered twice daily for 6 months following nerve repair. These data indicate that Leupeptin is an effective and safe pharmaceutic adjunct to nerve repair and may have clinical benefits in humans, where the oral route is a much preferred method of delivery.
-
Recovery after delayed nerve repair : influence of a pharmacologic adjunct in a primate model
Journal of Reconstructive Microsurgery, 1992Co-Authors: Marie A. Badalamente, Lawrence C. Hurst, Alfred StracherAbstract:Inhibition of calpains in skeletal muscle by the tripeptide, Leupeptin, after median-nerve transection in the mid-forearm and a delayed nerve repair of 3-weeks duration, was studied in a primate (Cebus apella) model. Results indicated that Leupeptin facilitates axon regrowth and neuromuscular recovery after delayed nerve repair. Toxicologic testing showed that Leupeptin, administered at 18 mg/kg intramuscularly, twice daily for 24 weeks after delayed nerve repair, did not adversely affect hematology, clotting, blood chemistry, or echocardiogram profiles. These data indicate that Leupeptin is an effective and safe adjunct to delayed nerve repair.
Takenobu Kamada - One of the best experts on this subject based on the ideXlab platform.
-
protective effect of the protease inhibitor Leupeptin against myocardial stunning
Journal of Cardiovascular Pharmacology, 1993Co-Authors: Yasushi Matsumura, Hideo Kusuoka, Michitoshi Inoue, Masatsugu Hori, Takenobu KamadaAbstract:Summary To elucidate whether activation of intracellular protease causes the contractile dysfunction of postishemic reperfused heart (stunned myocardium), the effect of Leupeptin, a cysteine-protease inhibitor, was evaluated in isolated guinea pig hearts. Left ventricular (LV) isovolumic pressure was measured in hearts reperfused after global ischemia (15 min, 37°C). Recovery of developed pressure during reperfusion in hearts treated with 50 μM Leupeptin was significantly greater than that in untreated hearts [94.3 φ 3.2% of control, n = 11 (mean φ SEM] vs. 78.1 φ 3.1%, n = 14), and was almost identical to that in nonischemic control (93.5 φ 1.6%, n = 11). Maximal Ca2+-activated pressure, the intact-heart correlate of maximal Ca2+-activated force, was also evaluated at the end of experiments during tetani elicited by rapid pacing after exposure to ryanodine. Maximal Ca2+ -activated pressure in hearts treated with Leupeptin (168 φ 4.6 mm Hg) was significantly higher than in untreated stunned hearts (144.5 φ 5.7 mm Hg), but significantly lower than in nonischemic control (198.4 φ 5.5 mm Hg). These results indicate that Leupeptin has a protective effect against myocardial stunning. In coupling with previous reports of transient increase in intracellular [Ca2+] during ischemia and/or reperfusion, activation of proteases by Ca2+ overload is suggested to play a significant role in myocardial stunning.
Ghislaine Gayanramirez - One of the best experts on this subject based on the ideXlab platform.
-
Leupeptin inhibits ventilator induced diaphragm dysfunction in rats
American Journal of Respiratory and Critical Care Medicine, 2007Co-Authors: Karen Maes, Dries Testelmans, Scott K Powers, Marc Decramer, Ghislaine GayanramirezAbstract:RATIONALE: Controlled mechanical ventilation (CMV) has been shown to result in elevated diaphragmatic proteolysis and atrophy together with diaphragmatic contractile dysfunction. OBJECTIVES: To test whether administration of Leupeptin, an inhibitor of lysosomal proteases and calpain, concomitantly with 24 hours of CMV, would protect the diaphragm from the deleterious effects of mechanical ventilation. METHODS: Rats were assigned to either a control group or 24 hours of CMV; animals in the ventilation group received either a single intramuscular injection of saline or 15 mg/kg of the protease inhibitor, Leupeptin. MEASUREMENTS AND MAIN RESULTS: Compared with control animals, mechanical ventilation resulted in a significant reduction of the in vitro diaphragm-specific force production at all stimulation frequencies. Leupeptin completely prevented this reduction in force generation. Atrophy of type IIx/b fibers was present after CMV, but not after treatment with Leupeptin. Cathepsin B and calpain activities were significantly higher after CMV compared with the other groups; this was abolished by treatment with Leupeptin. Significant inverse correlations were found between diaphragmatic force generation and cathepsin B and calpain activity, and illustrate the deleterious role of proteolysis in diminishing diaphragmatic force production after prolonged CMV. CONCLUSIONS: Administration of the protease inhibitor Leupeptin concomitantly with mechanical ventilation completely prevented ventilation-induced diaphragmatic contractile dysfunction and atrophy.
Setsuko Kanai - One of the best experts on this subject based on the ideXlab platform.
-
effect of Leupeptin on the lateral mobility of proteins in the plasma membrane of hepatocytes of c57bl 6 mice frap studies on liver smears
Archives of Gerontology and Geriatrics, 1992Co-Authors: Kenichi Kitani, Imre Zs Nagy, Minoru Ohta, Setsuko Kanai, Yuko SatoAbstract:Abstract Four groups of male C57BL/6 mice (ages 2, 3.8, 11.8–12.5 and 24 months) were administered Leupeptin at 5 mg/100 g body weight/day via intraperitoneally implanted osmotic minipumps. Both untreated and saline-treated mice served as controls. The time and dose-dependence of the effects of Leupeptin on the lateral mobility of proteins in hepatocyte surface membranes were analyzed first in mice treated for 2, 5, 8, 11 and 14 days, respectively, by using the fluorescence recovery after photobleaching (FRAP) technique. The age dependence of the response to this treatment was also studied after 14 days of treatment in mice of various ages. The average lateral diffusion constant (D) and the fractional recovery (FR) were measured, and D × FR calculated. Leupeptin treatment at a daily dose of 5 mg/100g for 2 weeks increased plasma glutamic-pyruvlc transaminase levels 2-fold in all age groups. Leupeptin treatment caused a linear increase of D and a decrease of FR with respect to the duration of the treatment in adult mice. In all age groups about 30% of the membrane proteins became immobile after 14 days of treatment, whereas the still mobile fraction displayed a large increase of D. The values of D × FR in the Leupeptin-treated groups were slightly higher than those in the untreated mice until the age of 15 months but decreased after this age. The results are interpreted in terms of the known inhibitory effect of Leupeptin on cytoplasmic and lysosomal thiol proteases, causing a general slowing down of the protein turnover and, specifically, of proteins in the hepatocyte membrane.
-
intraventricular infusion of Leupeptin decreases bmax of the d2 receptor in the striatum of young rats
Life Sciences, 1992Co-Authors: Makiko Shibata, Minoru Ohta, Setsuko Kanai, M Asakura, Anri Aoba, Kazuo Hasegawa, Kenichi KitaniAbstract:Abstract Intraventricular infusion of a thiol protease inhibitor, Leupeptin, was previously shown to induce several morphological and immunochemical manifestations of normal and pathological aging in rat brain. The present study attempted to elucidate whether this treatment also perturbs another brain function which declines in aging, dopamine D2 receptor binding in striatum. Intraventricular infusion of Leupeptin (0.6 mg per day) for two weeks caused a significant (about 20%) reduction in the binding maximum (Bmax) of dopamine D2 receptors (as examined by [ 3 H] spiperone binding) in the striatum of young male Fischer-344 rats in comparison to (saline-infused) control rats. The apparent Kd values did not differ significantly between the control and Leupeptin-treated rat groups. The results suggest that decreased protein turnover may be a factor in the decline in Bmax of D2 receptors during aging.
-
Leupeptin causes an accumulation of lipofuscin like substances in liver cells of young rats
Mechanisms of Ageing and Development, 1991Co-Authors: Setsuko Kanai, Minoru Ohta, Yuko Sato, Koichiro Otsubo, Kenichi KitaniAbstract:Abstract Leupeptin, a thiol protease inhibitor, has previously been shown to cause a dense accumulation of substances resembling age pigment and called ceroid-lipofuscin, in brain cells of young rats [1]. Thus far, however, attempts to produce age pigments in hepatocytes of normal young rats with protease inhibitor(s) have not been successful. The present study provides the first demonstration that Leupeptin induces lipofuscin-like substances in normal young rat hepatocytes. Male Fischer-344 rats (age 4–6 weeks) were continuously infused with Leupeptin or saline i.p. for 2 weeks by an osmotic minipump (dosage, 1–50 mg/100 g per day). Liver tissues were then examined by light, fluorescence and electron microscopy. Both hepatocytes and non-parenchymal cells of livers treated with Leupeptin, but not saline, showed a dense accumulation of pigments which stained deeply with toluidine blue, were PAS-positive and were brightly autofluorescent. After UV excitation the pigments had an emission spectrum with a broad peak at 480–540 nm extending to 650 nm resembling the spectrum of age pigment from livers of normal aged rats. Electron microscopic examination revealed numerous lipofuscin-like deposits with heterogeneous morphology in the cytoplasm of both hepatocytes and non-parenchymal cells; lipid and myelin-like bodies were also present in hepatocytes. The results indicate that the perturbation of proteolytic activity in liver by Leupeptin causes an accumulation of substances which by several criteria resemble lipofuscin. These results thus provide further support for the ‘Protease Inhibitor Model of Lipofuscin Formation’ [2] as well as a potential experimental model for studying hepatocellular aging processes.