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Guido F. Smoorenburg – One of the best experts on this subject based on the ideXlab platform.

  • ultrastructural changes in the Albino Guinea Pig cochlea at different survival times following cessation of 8 day cisplatin administration
    Acta Oto-laryngologica, 2004
    Co-Authors: Remco M Cardinaal, Guido F. Smoorenburg, J. C. M. J. De Groot, Eh Huizing, J. E. Veldman
    Abstract:

    Objective To investigate the effect of cisplatin administration on the ultrastructural morphology of the organ of Corti, stria vascularis and spiral ganglion. Material and Methods Forty-eight Guinea Pigs were treated with cisplatin by daily i.p. injection at a dose of 1.5 mg/kg for eight consecutive days. Electrocochleography was performed at various survival times after the final application of cisplatin. The cochleae were subsequently examined using electron microscopy. Results Ultrastructural examination corroborated that, in cochlear turns showing complete loss of outer hair cells (OHCs) at the light microscopic level, OHCs were indeed missing and had been completely replaced by supporting cells. OHC loss, the number of affected OHCs and the degree of intracellular pathology in the OHCs in the 1-day, 1-week and 2-week survival groups were considerably higher than in the 4- and 8-week survival groups. All degenerated OHCs demonstrated ultrastructural features commonly associated with necrosis. No morph…

  • Partial recovery of cisplatin-induced hearing loss in the Albino Guinea Pig in relation to cisplatin dose.
    Hearing research, 2002
    Co-Authors: Sjaak F.l. Klis, Frank P.t. Hamers, J. C. M. J. De Groot, Stephen J O'leary, Jeroen Wijbenga, Guido F. Smoorenburg
    Abstract:

    The objective of the present study was to further characterize cochlear recovery after cisplatin damage. We equipped Albino Guinea Pigs with permanent round window electrodes. Cisplatin was injected i.p. on a daily basis at either 1.5 or 2.0 mg/kg/day. Treatment was stopped when the criterion of > or =40 dB loss in the compound action potential iso-response level at 8 kHz had occurred. Either shortly (1-3 days) or long (4 weeks or more) after this stop, the endocochlear potential (EP) was measured and all animals were sacrificed for histology. At a cisplatin dose of 2.0 mg/kg/day, the time needed to reach the criterion hearing loss varied from 5 to 11 days. With 1.5 mg/kg/day this period lasted longer, the cumulative dose being the first-order predictor. The cochlear potentials gradually recovered in the first 2 weeks after treatment. At the lower frequencies, recovery was often complete. At the higher frequencies complete recovery was never seen. EP was depressed when measured just after treatment but had normal values long after. Basal outer hair cell (OHC) loss was found for both the short and the long post-treatment period. Thus, loss and recovery of cochlear potentials can for a large part be explained by loss and recovery of the EP. Recovery is limited by permanent OHC loss.

  • histological effects of co administration of an acth 4 9 analogue org 2766 on cisplatin ototoxicity in the Albino Guinea Pig
    Hearing Research, 2000
    Co-Authors: Remco M Cardinaal, J. C. M. J. De Groot, J. E. Veldman, Eh Huizing, Guido F. Smoorenburg
    Abstract:

    Cisplatin is one of the most potent antineoplastic drugs presently known, but its therapeutic efficacy is seriously limited by several side effects such as ototoxicity. Several compounds that are known for their nephroprotective effects also seem to reduce the incidence and severity of cisplatin-induced ototoxicity. Hamers et al. (1994) and De Groot et al. (1997) investigated the possibly protective effect of concomitant administration of the ACTH((4-9)) analogue ORG 2766 upon cisplatin ototoxicity in Guinea Pigs. Animals were treated with cisplatin at a daily dose of 2.0 mg/kg for 8 consecutive days and ORG 2766 at a daily dose of 75 mcg/kg for 9 days. Concomitant administration of cisplatin plus ORG 2766 resulted in a bimodal distribution of the electrophysiological data (compound action potential and cochlear microphonics amplitudes) and the histological data (outer hair cell (OHC) counts). It was surmised that this dichotomy might occur at a certain cisplatin dose. We investigated whether this protective effect of ORG 2766 could be enhanced by reducing the daily dose of cisplatin while maintaining the same dose of ORG 2766. Thirty-six animals were treated with daily i.p. injections of cisplatin at a dose of 1.0 mg/kg (n=18) or 1.5 mg/kg (n=18) for 8 consecutive days. When comparing the mean OHC counts of the different experimental groups, treatment with cisplatin at a daily dose of 1.5 mg/kg for 8 consecutive days resulted in a considerable loss of OHCs, which was significantly reduced after co-administration of ORG 2766. Co-treatment with ORG 2766 did not result in a change in the volume of the scala media. The present results are in agreement with the electrophysiological results published earlier (Stengs et al., 1998b).

Gunnar Lennerstrand – One of the best experts on this subject based on the ideXlab platform.

  • Contractile properties and histochemistry of extraocular muscle in the Pigmented and the Albino Guinea Pig.
    Acta ophthalmologica, 2009
    Co-Authors: Gunnar Lennerstrand
    Abstract:

    . The inferior oblique muscles of Pigmented and Albino Guinea Pigs were compared with respect to contractile and histochemical properties. No differences were found between the 2 kinds of animal in twitch and tetanic response or in fatigue properties. They also had the same fiber composition and fiber and capillary densities of their inferior obliques. These findings indicate that differences in eye muscle previously demonstrated and Siamese (Albino) cats are related to the state of binocular vision and not to genetic variations between Pigmented and Albino animals.

Sjaak F.l. Klis – One of the best experts on this subject based on the ideXlab platform.

  • Partial recovery of cisplatin-induced hearing loss in the Albino Guinea Pig in relation to cisplatin dose.
    Hearing research, 2002
    Co-Authors: Sjaak F.l. Klis, Frank P.t. Hamers, J. C. M. J. De Groot, Stephen J O'leary, Jeroen Wijbenga, Guido F. Smoorenburg
    Abstract:

    The objective of the present study was to further characterize cochlear recovery after cisplatin damage. We equipped Albino Guinea Pigs with permanent round window electrodes. Cisplatin was injected i.p. on a daily basis at either 1.5 or 2.0 mg/kg/day. Treatment was stopped when the criterion of > or =40 dB loss in the compound action potential iso-response level at 8 kHz had occurred. Either shortly (1-3 days) or long (4 weeks or more) after this stop, the endocochlear potential (EP) was measured and all animals were sacrificed for histology. At a cisplatin dose of 2.0 mg/kg/day, the time needed to reach the criterion hearing loss varied from 5 to 11 days. With 1.5 mg/kg/day this period lasted longer, the cumulative dose being the first-order predictor. The cochlear potentials gradually recovered in the first 2 weeks after treatment. At the lower frequencies, recovery was often complete. At the higher frequencies complete recovery was never seen. EP was depressed when measured just after treatment but had normal values long after. Basal outer hair cell (OHC) loss was found for both the short and the long post-treatment period. Thus, loss and recovery of cochlear potentials can for a large part be explained by loss and recovery of the EP. Recovery is limited by permanent OHC loss.

  • Reversible cisplatin ototoxicity in the Albino Guinea Pig.
    Neuroreport, 2000
    Co-Authors: Sjaak F.l. Klis, Stephen O'leary, Frank P.t. Hamers, J. C. M. J. De Groot, Guido F. Smoorenburg
    Abstract:

    Guinea Pigs implanted with round window electrodes received daily doses (2.0 mg/kg) of cisplatin until a profound hearing loss occurred (> 40 dB at 8 kHz). Afterwards, pronounced recovery occurred. Recovery progressed over intervals up to 3 weeks before it saturated. Loss and recovery involved both the compound action potential and, less pronounced, the cochlear microphonics. Cochlear potentials evoked by lower frequencies recovered more fully than those evoked by higher frequencies. Loss and recovery was found also in the endocochlear potential. Outer hair cell counts did not change over the recovery period. These findings confirm our previously reported results on the reversibility of cisplatin damage. Further, they implicate the vascular stria as an important target for cisplatin in the cochlea.

  • Cisplatin-induced ototoxicity; electrophysiological evidence of spontaneous recovery in the Albino Guinea Pig.
    Hearing Research, 1997
    Co-Authors: Cornelis H.m Stengs, Sjaak F.l. Klis, Egbert H. Huizing, Guido F. Smoorenburg
    Abstract:

    For 8 days Albino Guinea Pigs (n = 48) were treated with cisplatin (cis-diamminedichloroplatinum(II), 1.5 mg/kg body weight/day). Compound action potentials (CAP), cochlear microphonics (CM) and summating potentials (SP) were recorded from the apical surface of the cochlea in response to tone bursts ranging in frequency from 0.5 to 16 kHz. The recordings were collected in different groups of animals, 1 day, 1 week, 2, 4, 8 and 16 weeks after cisplatin treatment, respectively. One day after the 8-day treatment we found frequency-dependent loss in the amplitudes of the three cochlear potentials, with the larger losses occurring at the higher frequencies. In terms of threshold shift the losses were larger for the CAP than for the hair cell-related potentials SP and CM. A salient improvement in both CAP and CM amplitude occurred over the next 8 weeks. Also, the SP showed improvement. These results indicate that Guinea Pig cochlear transduction recovers spontaneously after cisplatin injury. Recovery of the hair cell-related potentials suggests that recovery occurs already at the hair cell level. The question whether this recovery originates with the formation of new hair cells or with repair of damaged hair cells should be answered on the basis of subsequent morphological investigations.

J. C. M. J. De Groot – One of the best experts on this subject based on the ideXlab platform.

  • ultrastructural changes in the Albino Guinea Pig cochlea at different survival times following cessation of 8 day cisplatin administration
    Acta Oto-laryngologica, 2004
    Co-Authors: Remco M Cardinaal, Guido F. Smoorenburg, J. C. M. J. De Groot, Eh Huizing, J. E. Veldman
    Abstract:

    Objective To investigate the effect of cisplatin administration on the ultrastructural morphology of the organ of Corti, stria vascularis and spiral ganglion. Material and Methods Forty-eight Guinea Pigs were treated with cisplatin by daily i.p. injection at a dose of 1.5 mg/kg for eight consecutive days. Electrocochleography was performed at various survival times after the final application of cisplatin. The cochleae were subsequently examined using electron microscopy. Results Ultrastructural examination corroborated that, in cochlear turns showing complete loss of outer hair cells (OHCs) at the light microscopic level, OHCs were indeed missing and had been completely replaced by supporting cells. OHC loss, the number of affected OHCs and the degree of intracellular pathology in the OHCs in the 1-day, 1-week and 2-week survival groups were considerably higher than in the 4- and 8-week survival groups. All degenerated OHCs demonstrated ultrastructural features commonly associated with necrosis. No morph…

  • Partial recovery of cisplatin-induced hearing loss in the Albino Guinea Pig in relation to cisplatin dose.
    Hearing research, 2002
    Co-Authors: Sjaak F.l. Klis, Frank P.t. Hamers, J. C. M. J. De Groot, Stephen J O'leary, Jeroen Wijbenga, Guido F. Smoorenburg
    Abstract:

    The objective of the present study was to further characterize cochlear recovery after cisplatin damage. We equipped Albino Guinea Pigs with permanent round window electrodes. Cisplatin was injected i.p. on a daily basis at either 1.5 or 2.0 mg/kg/day. Treatment was stopped when the criterion of > or =40 dB loss in the compound action potential iso-response level at 8 kHz had occurred. Either shortly (1-3 days) or long (4 weeks or more) after this stop, the endocochlear potential (EP) was measured and all animals were sacrificed for histology. At a cisplatin dose of 2.0 mg/kg/day, the time needed to reach the criterion hearing loss varied from 5 to 11 days. With 1.5 mg/kg/day this period lasted longer, the cumulative dose being the first-order predictor. The cochlear potentials gradually recovered in the first 2 weeks after treatment. At the lower frequencies, recovery was often complete. At the higher frequencies complete recovery was never seen. EP was depressed when measured just after treatment but had normal values long after. Basal outer hair cell (OHC) loss was found for both the short and the long post-treatment period. Thus, loss and recovery of cochlear potentials can for a large part be explained by loss and recovery of the EP. Recovery is limited by permanent OHC loss.

  • histological effects of co administration of an acth 4 9 analogue org 2766 on cisplatin ototoxicity in the Albino Guinea Pig
    Hearing Research, 2000
    Co-Authors: Remco M Cardinaal, J. C. M. J. De Groot, J. E. Veldman, Eh Huizing, Guido F. Smoorenburg
    Abstract:

    Cisplatin is one of the most potent antineoplastic drugs presently known, but its therapeutic efficacy is seriously limited by several side effects such as ototoxicity. Several compounds that are known for their nephroprotective effects also seem to reduce the incidence and severity of cisplatin-induced ototoxicity. Hamers et al. (1994) and De Groot et al. (1997) investigated the possibly protective effect of concomitant administration of the ACTH((4-9)) analogue ORG 2766 upon cisplatin ototoxicity in Guinea Pigs. Animals were treated with cisplatin at a daily dose of 2.0 mg/kg for 8 consecutive days and ORG 2766 at a daily dose of 75 mcg/kg for 9 days. Concomitant administration of cisplatin plus ORG 2766 resulted in a bimodal distribution of the electrophysiological data (compound action potential and cochlear microphonics amplitudes) and the histological data (outer hair cell (OHC) counts). It was surmised that this dichotomy might occur at a certain cisplatin dose. We investigated whether this protective effect of ORG 2766 could be enhanced by reducing the daily dose of cisplatin while maintaining the same dose of ORG 2766. Thirty-six animals were treated with daily i.p. injections of cisplatin at a dose of 1.0 mg/kg (n=18) or 1.5 mg/kg (n=18) for 8 consecutive days. When comparing the mean OHC counts of the different experimental groups, treatment with cisplatin at a daily dose of 1.5 mg/kg for 8 consecutive days resulted in a considerable loss of OHCs, which was significantly reduced after co-administration of ORG 2766. Co-treatment with ORG 2766 did not result in a change in the volume of the scala media. The present results are in agreement with the electrophysiological results published earlier (Stengs et al., 1998b).

Shuangzhen Liu – One of the best experts on this subject based on the ideXlab platform.

  • Different roles of retinal dopamine in Albino Guinea Pig myopia.
    Neuroscience letters, 2016
    Co-Authors: Junfeng Mao, Shuangzhen Liu
    Abstract:

    Abstract Purpose To investigate whether the different role of ocular dopamine was involved in the myopic development between spontaneous myopia (SM) and form deprivation myopia (FDM) in Albino Guinea Pigs. Methods 55 myopic animals were randomly divided into SM, Levodapa (L-DOPA), L-DOPA + carbidopa and vehicle. 70 non-myopic animals were randomly divided into normal control, FDM, L-DOPA + FDM, L-DOPA + carbidopa + FDM and vehicle. Once per day, for 14 days, L-DOPA (10 mg/kg) was injected intraperitoneally, and carbidopa (1 μg) was injected at the same time into the peribulbar space of the right eye. Refractive parameters and dopamine content in neural retina and RPE/choroid complex were measured. Results In SM animals, high myopia was formed at 5 week of ages. L-DOPA treatment could reduce its myopic degree, and inhibit the increase of axial length and vitreous chamber depth with the increase of retinal dopamine in both eyes. Administration of carbidopa could prevent the increase of retinal dopamine induced by L-DOPA, but no influenced on its refractive state in the injected eyes. In non-SM animals, intraperitoneal L-DOPA could inhibit FDM, accompanied by the increase of retinal dopamine. Carbidopa treatment diminished the inhibition of FDM and prevented the increase in retinal dopamine by L-Dopa. Retinal dopamine was highly correlated with ocular refraction in FDM, but not in SM. There was no significant difference in dopamine content of RPE/choroid complex among all groups. Conclusions The role of retinal dopamine was different between SM and FDM in Albino Guinea Pigs. Although systemic L-DOPA could inhibit the development of SM and FDM, retinal dopamine was only involved in the L-DOPA inhibition on FDM, but not on SM.