Sudden Acquired Retinal Degeneration in the Dog: Clinical and Morphologic Characterization of the Silent Retina Syndrome

Adult dogs occasionally become suddenly, totally and permanently blind. If examined soon after the onset of blindness, the dogs show no ophthalmologic evidence of disease sufficient to account for their problem and are usually in otherwise good health. The hallmark of this sudden, acquired retinal degeneration (SARD), that establishes it as a retinopathy, and distinguishes it from neurological disease, is the extinguished electroretinogram. The syndrome has been termed Silent Retina Syndrome and Metabolic Toxic Retinopathy . Although uncommon, SARD has been diagnosed with increased frequency in recent years. Little retinal tissue has, however, become available for histopathologic characterization of the disease. This report reviews twenty six cases of SARD examined by the authors at the Veterinary Hospital, University of Pennsylvania (VHUP). The histopathology and ultrastructural morphology of four cases are described

Isoform-specific requirement for Akt1 in the developmental regulation of cellular metabolism during lactation

SummaryThe metabolic demands and synthetic capacity of the lactating mammary gland exceed that of any other tissue, thereby providing a useful paradigm for understanding the developmental regulation of cellular metabolism. By evaluating mice bearing targeted deletions in Akt1 or Akt2, we demonstrate that Akt1 is specifically required for lactating mice to synthesize sufficient quantities of milk to support their offspring. Whereas cellular proliferation, differentiation, and apoptosis are unaffected, loss of Akt1 disrupts the coordinate regulation of metabolic pathways that normally occurs at the onset of lactation. This results in a failure to upregulate glucose uptake, Glut1 surface localization, lipid synthesis, and multiple lipogenic enzymes, as well as a failure to downregulate lipid catabolic enzymes. These findings demonstrate that Akt1 is required in an isoform-specific manner for orchestrating many of the developmental changes in cellular metabolism that occur at the onset of lactation and establish a role for Akt1 in glucose metabolism