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Martin Bergmann - One of the best experts on this subject based on the ideXlab platform.
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spontaneous Recrudescence of spermatogenesis in the photoinhibited male djungarian hamster phodopus sungorus
Biology of Reproduction, 1995Co-Authors: Stefan Schlatt, M De Geyter, Sabine Kliesch, Eberhard Nieschlag, Martin BergmannAbstract:Photosensitive rodents exposed to inhibitory short photoperiods become insensitive to this environmental factor after prolonged exposure. During the following process of spontaneous Recrudescence, the animals that have adapted to the winter season show a return of all seasonal parameters. In the Djungarian hamster, obvious photoperiod-dependent changes are reinitiation of the reproductive organs, a 20-30% increase in body weight, and a moult from whitish fur into brown summer fur. This study was designed to analyze the morphological and endocrinological changes occurring during spontaneous testicular Recrudescence in male Djungarian hamsters under prolonged short photoperiods. Two experiments were performed 1) to analyze the time-dependentchanges in groups of hamsters exposed to short photoperiods and 2) to observe testicular and humoral changes in individual animals during spontaneous Recrudescence. Regrowth of the testes and seminal vesicles did not begin before Week 18 in short photoperiods. While serum testosterone did not increase before Week 24, serum FSH had already returned to normal values from Week 18 onwards. Individual analysis by enzyme histochemistry revealed that 3,-hydroxysteroid-dehydrogenase activity in Leydig cells was not restored before testicular weights of more than 400 mg were observed and the first wave of spermatogenesis had reached the stage of elongated spermatids. This indicates that the testicular testosterone production was low until a status of testicular Recrudescence had been achieved, at which point the testis showed complete qualitative spermatogenesis and a restoration of the Sertoli cell actin filaments. These data suggest that the process of early spontaneous Recrudescence in male Djungarian hamsters appears to be initiated by the restoration of serum FSH rather than by testosterone.
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spontaneous Recrudescence of spermatogenesis in the photoinhibited male djungarian hamster phodopus sungorus
Biology of Reproduction, 1995Co-Authors: Stefan Schlatt, M De Geyter, Sabine Kliesch, Eberhard Nieschlag, Martin BergmannAbstract:Photosensitive rodents exposed to inhibitory short photoperiods become insensitive to this environmental factor after prolonged exposure. During the following process of spontaneous Recrudescence, the animals that have adapted to the winter season show a return of all seasonal parameters. In the Djungarian hamster, obvious photoperiod-dependent changes are reinitiation of the reproductive organs, a 20-30% increase in body weight, and a moult from whitish fur into brown summer fur. This study was designed to analyze the morphological and endocrinological changes occurring during spontaneous testicular Recrudescence in male Djungarian hamsters under prolonged short photoperiods. Two experiments were performed 1) to analyze the time-dependent changes in groups of hamsters exposed to short photoperiods and 2) to observe testicular and humoral changes in individual animals during spontaneous Recrudescence. Regrowth of the testes and seminal vesicles did not begin before Week 18 in short photoperiods. While serum testosterone did not increase before Week 24, serum FSH had already returned to normal values from Week 18 onwards. Individual analysis by enzyme histochemistry revealed that 3 beta-hydroxysteroid-dehydrogenase activity in Leydig cells was not restored before testicular weights of more than 400 mg were observed and the first wave of spermatogenesis had reached the stage of elongated spermatids. This indicates that the testicular testosterone production was low until a status of testicular Recrudescence had been achieved, at which point the testis showed complete qualitative spermatogenesis and a restoration of the Sertoli cell actin filaments. These data suggest that the process of early spontaneous Recrudescence in male Djungarian hamsters appears to be initiated by the restoration of serum FSH rather than by testosterone.
Stefan Schlatt - One of the best experts on this subject based on the ideXlab platform.
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spontaneous Recrudescence of spermatogenesis in the photoinhibited male djungarian hamster phodopus sungorus
Biology of Reproduction, 1995Co-Authors: Stefan Schlatt, M De Geyter, Sabine Kliesch, Eberhard Nieschlag, Martin BergmannAbstract:Photosensitive rodents exposed to inhibitory short photoperiods become insensitive to this environmental factor after prolonged exposure. During the following process of spontaneous Recrudescence, the animals that have adapted to the winter season show a return of all seasonal parameters. In the Djungarian hamster, obvious photoperiod-dependent changes are reinitiation of the reproductive organs, a 20-30% increase in body weight, and a moult from whitish fur into brown summer fur. This study was designed to analyze the morphological and endocrinological changes occurring during spontaneous testicular Recrudescence in male Djungarian hamsters under prolonged short photoperiods. Two experiments were performed 1) to analyze the time-dependentchanges in groups of hamsters exposed to short photoperiods and 2) to observe testicular and humoral changes in individual animals during spontaneous Recrudescence. Regrowth of the testes and seminal vesicles did not begin before Week 18 in short photoperiods. While serum testosterone did not increase before Week 24, serum FSH had already returned to normal values from Week 18 onwards. Individual analysis by enzyme histochemistry revealed that 3,-hydroxysteroid-dehydrogenase activity in Leydig cells was not restored before testicular weights of more than 400 mg were observed and the first wave of spermatogenesis had reached the stage of elongated spermatids. This indicates that the testicular testosterone production was low until a status of testicular Recrudescence had been achieved, at which point the testis showed complete qualitative spermatogenesis and a restoration of the Sertoli cell actin filaments. These data suggest that the process of early spontaneous Recrudescence in male Djungarian hamsters appears to be initiated by the restoration of serum FSH rather than by testosterone.
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spontaneous Recrudescence of spermatogenesis in the photoinhibited male djungarian hamster phodopus sungorus
Biology of Reproduction, 1995Co-Authors: Stefan Schlatt, M De Geyter, Sabine Kliesch, Eberhard Nieschlag, Martin BergmannAbstract:Photosensitive rodents exposed to inhibitory short photoperiods become insensitive to this environmental factor after prolonged exposure. During the following process of spontaneous Recrudescence, the animals that have adapted to the winter season show a return of all seasonal parameters. In the Djungarian hamster, obvious photoperiod-dependent changes are reinitiation of the reproductive organs, a 20-30% increase in body weight, and a moult from whitish fur into brown summer fur. This study was designed to analyze the morphological and endocrinological changes occurring during spontaneous testicular Recrudescence in male Djungarian hamsters under prolonged short photoperiods. Two experiments were performed 1) to analyze the time-dependent changes in groups of hamsters exposed to short photoperiods and 2) to observe testicular and humoral changes in individual animals during spontaneous Recrudescence. Regrowth of the testes and seminal vesicles did not begin before Week 18 in short photoperiods. While serum testosterone did not increase before Week 24, serum FSH had already returned to normal values from Week 18 onwards. Individual analysis by enzyme histochemistry revealed that 3 beta-hydroxysteroid-dehydrogenase activity in Leydig cells was not restored before testicular weights of more than 400 mg were observed and the first wave of spermatogenesis had reached the stage of elongated spermatids. This indicates that the testicular testosterone production was low until a status of testicular Recrudescence had been achieved, at which point the testis showed complete qualitative spermatogenesis and a restoration of the Sertoli cell actin filaments. These data suggest that the process of early spontaneous Recrudescence in male Djungarian hamsters appears to be initiated by the restoration of serum FSH rather than by testosterone.
Hume Field - One of the best experts on this subject based on the ideXlab platform.
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recrudescent infection supports hendra virus persistence in australian flying fox populations
PLOS ONE, 2013Co-Authors: Hsiaohsuan Wang, N Y Kung, William E. Grant, J C Scanlan, Hume FieldAbstract:Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of Recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic Recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-Recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of Recrudescence merits increased attention.
Hsiaohsuan Wang - One of the best experts on this subject based on the ideXlab platform.
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recrudescent infection supports hendra virus persistence in australian flying fox populations
PLOS ONE, 2013Co-Authors: Hsiaohsuan Wang, N Y Kung, William E. Grant, J C Scanlan, Hume FieldAbstract:Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of Recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic Recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-Recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of Recrudescence merits increased attention.
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Recrudescent Infection Supports Hendra Virus Persistence in Australian Flying-Fox Populations
2013Co-Authors: Hsiaohsuan Wang, N Y Kung, William E. Grant, J C Scanlan, Hume E. FieldAbstract:Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of Recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic Recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-Recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of recrudescenc
Eberhard Nieschlag - One of the best experts on this subject based on the ideXlab platform.
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spontaneous Recrudescence of spermatogenesis in the photoinhibited male djungarian hamster phodopus sungorus
Biology of Reproduction, 1995Co-Authors: Stefan Schlatt, M De Geyter, Sabine Kliesch, Eberhard Nieschlag, Martin BergmannAbstract:Photosensitive rodents exposed to inhibitory short photoperiods become insensitive to this environmental factor after prolonged exposure. During the following process of spontaneous Recrudescence, the animals that have adapted to the winter season show a return of all seasonal parameters. In the Djungarian hamster, obvious photoperiod-dependent changes are reinitiation of the reproductive organs, a 20-30% increase in body weight, and a moult from whitish fur into brown summer fur. This study was designed to analyze the morphological and endocrinological changes occurring during spontaneous testicular Recrudescence in male Djungarian hamsters under prolonged short photoperiods. Two experiments were performed 1) to analyze the time-dependentchanges in groups of hamsters exposed to short photoperiods and 2) to observe testicular and humoral changes in individual animals during spontaneous Recrudescence. Regrowth of the testes and seminal vesicles did not begin before Week 18 in short photoperiods. While serum testosterone did not increase before Week 24, serum FSH had already returned to normal values from Week 18 onwards. Individual analysis by enzyme histochemistry revealed that 3,-hydroxysteroid-dehydrogenase activity in Leydig cells was not restored before testicular weights of more than 400 mg were observed and the first wave of spermatogenesis had reached the stage of elongated spermatids. This indicates that the testicular testosterone production was low until a status of testicular Recrudescence had been achieved, at which point the testis showed complete qualitative spermatogenesis and a restoration of the Sertoli cell actin filaments. These data suggest that the process of early spontaneous Recrudescence in male Djungarian hamsters appears to be initiated by the restoration of serum FSH rather than by testosterone.
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spontaneous Recrudescence of spermatogenesis in the photoinhibited male djungarian hamster phodopus sungorus
Biology of Reproduction, 1995Co-Authors: Stefan Schlatt, M De Geyter, Sabine Kliesch, Eberhard Nieschlag, Martin BergmannAbstract:Photosensitive rodents exposed to inhibitory short photoperiods become insensitive to this environmental factor after prolonged exposure. During the following process of spontaneous Recrudescence, the animals that have adapted to the winter season show a return of all seasonal parameters. In the Djungarian hamster, obvious photoperiod-dependent changes are reinitiation of the reproductive organs, a 20-30% increase in body weight, and a moult from whitish fur into brown summer fur. This study was designed to analyze the morphological and endocrinological changes occurring during spontaneous testicular Recrudescence in male Djungarian hamsters under prolonged short photoperiods. Two experiments were performed 1) to analyze the time-dependent changes in groups of hamsters exposed to short photoperiods and 2) to observe testicular and humoral changes in individual animals during spontaneous Recrudescence. Regrowth of the testes and seminal vesicles did not begin before Week 18 in short photoperiods. While serum testosterone did not increase before Week 24, serum FSH had already returned to normal values from Week 18 onwards. Individual analysis by enzyme histochemistry revealed that 3 beta-hydroxysteroid-dehydrogenase activity in Leydig cells was not restored before testicular weights of more than 400 mg were observed and the first wave of spermatogenesis had reached the stage of elongated spermatids. This indicates that the testicular testosterone production was low until a status of testicular Recrudescence had been achieved, at which point the testis showed complete qualitative spermatogenesis and a restoration of the Sertoli cell actin filaments. These data suggest that the process of early spontaneous Recrudescence in male Djungarian hamsters appears to be initiated by the restoration of serum FSH rather than by testosterone.
