The Experts below are selected from a list of 408 Experts worldwide ranked by ideXlab platform

Haruhiro Yamashita - One of the best experts on this subject based on the ideXlab platform.

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Connie A. Cummings
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essentia...

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Connie A. Cummings, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Yu Wang
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essential to maintain the homeostasis of the photoreceptor layer and is regulated by melatonin signaling. Therefore, reduced photoreceptor outer segment disc shedding and subsequent lower number of phagosomes in the RPE and alterations in the melatonin pathway may have contributed to the increased incidences of retinal degeneration observed in F344/N rats in the 2-year KKE bioassay.

  • chemical exacerbation of light induced retinal degeneration in f344 n rats in national toxicology program rodent bioassays
    Toxicologic Pathology, 2016
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Mark J Hoenerhoff, Robert C Sills, Arun R Pandiri
    Abstract:

    Retinal degeneration due to chronic ambient light exposure is a common spontaneous age-related finding in albino rats, but it can also be related to exposures associated with environmental chemicals and drugs. Typically, light-induced retinal degeneration has a central/hemispherical localization whereas chemical-induced retinal degeneration has a diffuse localization. This study was conducted to identify and characterize treatment-related retinal degeneration in National Toxicology Program rodent bioassays. A total of 3 chronic bioassays in F344/N rats (but not in B6C3F1/N mice) were identified that had treatment-related increases in retinal degeneration (Kava Kava Extract, acrylamide, and leucomalachite green). A retrospective light microscopic evaluation of the retinas from rats in these 3 studies showed a dose-related increase in the frequencies of retinal degeneration, beginning with the loss of photoreceptor cells, followed by the inner nuclear layer cells. These dose-related increased frequencies of...

Mark J Hoenerhoff - One of the best experts on this subject based on the ideXlab platform.

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Connie A. Cummings
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essentia...

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Connie A. Cummings, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Yu Wang
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essential to maintain the homeostasis of the photoreceptor layer and is regulated by melatonin signaling. Therefore, reduced photoreceptor outer segment disc shedding and subsequent lower number of phagosomes in the RPE and alterations in the melatonin pathway may have contributed to the increased incidences of retinal degeneration observed in F344/N rats in the 2-year KKE bioassay.

  • chemical exacerbation of light induced retinal degeneration in f344 n rats in national toxicology program rodent bioassays
    Toxicologic Pathology, 2016
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Mark J Hoenerhoff, Robert C Sills, Arun R Pandiri
    Abstract:

    Retinal degeneration due to chronic ambient light exposure is a common spontaneous age-related finding in albino rats, but it can also be related to exposures associated with environmental chemicals and drugs. Typically, light-induced retinal degeneration has a central/hemispherical localization whereas chemical-induced retinal degeneration has a diffuse localization. This study was conducted to identify and characterize treatment-related retinal degeneration in National Toxicology Program rodent bioassays. A total of 3 chronic bioassays in F344/N rats (but not in B6C3F1/N mice) were identified that had treatment-related increases in retinal degeneration (Kava Kava Extract, acrylamide, and leucomalachite green). A retrospective light microscopic evaluation of the retinas from rats in these 3 studies showed a dose-related increase in the frequencies of retinal degeneration, beginning with the loss of photoreceptor cells, followed by the inner nuclear layer cells. These dose-related increased frequencies of...

Connie A. Cummings - One of the best experts on this subject based on the ideXlab platform.

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Connie A. Cummings
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essentia...

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Connie A. Cummings, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Yu Wang
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essential to maintain the homeostasis of the photoreceptor layer and is regulated by melatonin signaling. Therefore, reduced photoreceptor outer segment disc shedding and subsequent lower number of phagosomes in the RPE and alterations in the melatonin pathway may have contributed to the increased incidences of retinal degeneration observed in F344/N rats in the 2-year KKE bioassay.

Shyamal D Peddada - One of the best experts on this subject based on the ideXlab platform.

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Connie A. Cummings
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essentia...

  • reduced disc shedding and phagocytosis of photoreceptor outer segment contributes to Kava Kava Extract induced retinal degeneration in f344 n rats
    Toxicologic Pathology, 2018
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Kevin Gerrish, Connie A. Cummings, Mark J Hoenerhoff, Keith R. Shockley, Deloris Sutton, Yu Wang
    Abstract:

    There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava Kava Extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essential to maintain the homeostasis of the photoreceptor layer and is regulated by melatonin signaling. Therefore, reduced photoreceptor outer segment disc shedding and subsequent lower number of phagosomes in the RPE and alterations in the melatonin pathway may have contributed to the increased incidences of retinal degeneration observed in F344/N rats in the 2-year KKE bioassay.

  • chemical exacerbation of light induced retinal degeneration in f344 n rats in national toxicology program rodent bioassays
    Toxicologic Pathology, 2016
    Co-Authors: Haruhiro Yamashita, Shyamal D Peddada, Mark J Hoenerhoff, Robert C Sills, Arun R Pandiri
    Abstract:

    Retinal degeneration due to chronic ambient light exposure is a common spontaneous age-related finding in albino rats, but it can also be related to exposures associated with environmental chemicals and drugs. Typically, light-induced retinal degeneration has a central/hemispherical localization whereas chemical-induced retinal degeneration has a diffuse localization. This study was conducted to identify and characterize treatment-related retinal degeneration in National Toxicology Program rodent bioassays. A total of 3 chronic bioassays in F344/N rats (but not in B6C3F1/N mice) were identified that had treatment-related increases in retinal degeneration (Kava Kava Extract, acrylamide, and leucomalachite green). A retrospective light microscopic evaluation of the retinas from rats in these 3 studies showed a dose-related increase in the frequencies of retinal degeneration, beginning with the loss of photoreceptor cells, followed by the inner nuclear layer cells. These dose-related increased frequencies of...

Josef Krieglstein - One of the best experts on this subject based on the ideXlab platform.

  • Extract of Kava (Piper methysticum) and its methysticin constituents protect brain tissue against ischemic damage in rodents
    European Journal of Pharmacology, 1992
    Co-Authors: Cord Backhauβ, Josef Krieglstein
    Abstract:

    Abstract The purpose of the present study was to test whether Kava Extract and its constituents kawain, dihydrokawain, methysticin, dihydromethysticin and yangonin provide protection against ischemic brain damage. To this end, we used a model of focal cerebral ischemia in mice and rats. Ischemia was induced by microbipolar coagulation of the left middle cerebral artery (MCA). To quantify the size of the lesion in mice, the area of the infarct on the brain surface was assessed planimetrically 48 h after MCA occlusion by transcardial perfusion of carbon black. In the rat model infarct volume was determined 48 h after MCA occlusion by planimetric analysis and subsequent integration of the infarct areas on serial coronal slices. Compounds were administered i.p., except the Kava Extract, which was administered orally. The effects of the Kava Extract and its constituents were compared with those produced by the typical anticonvulsant, memantine. The Kava Extract, methysticin and dihydromethysticin produced effects similar to those of the reference substance memantine. The Kava Extract (150 mg/kg, 1 h before ischemia) diminished the infarct area (P

  • Extract of Kava piper methysticum and its methysticin constituents protect brain tissue against ischemic damage in rodents
    European Journal of Pharmacology, 1992
    Co-Authors: Cord Backhauβ, Josef Krieglstein
    Abstract:

    The purpose of the present study was to test whether Kava Extract and its constituents kawain, dihydrokawain, methysticin, dihydromethysticin and yangonin provide protection against ischemic brain damage. To this end, we used a model of focal cerebral ischemia in mice and rats. Ischemia was induced by microbipolar coagulation of the left middle cerebral artery (MCA). To quantify the size of the lesion in mice, the area of the infarct on the brain surface was assessed planimetrically 48 h after MCA occlusion by transcardial perfusion of carbon black. In the rat model infarct volume was determined 48 h after MCA occlusion by planimetric analysis and subsequent integration of the infarct areas on serial coronal slices. Compounds were administered i.p., except the Kava Extract, which was administered orally. The effects of the Kava Extract and its constituents were compared with those produced by the typical anticonvulsant, memantine. The Kava Extract, methysticin and dihydromethysticin produced effects similar to those of the reference substance memantine. The Kava Extract (150 mg/kg, 1 h before ischemia) diminished the infarct area (P less than 0.05) in mouse brains and the infarct volume (P less than 0.05) in rat brains. Methysticin, dihydromethysticin (both 10 and 30 mg/kg, 15 min before ischemia) and memantine (20 mg/kg, 30 min before ischemia) significantly reduced the infarct area in mouse brains. All other compounds failed to produce a beneficial effect on the infarct area in mouse brains. In conclusion, the Kava Extract exhibited neuroprotective activity, which was probably mediated by its constituents methysticin and dihydromethysticin.