Nonsense mutation of feline beta-hexosaminidase beta-subunit (HEXB) gene causing Sandhoff disease in a family of Japanese domestic cats.

G(M2) gangliosidoses are inherited metabolic disorders and are caused by severely reduced enzymatic activity of lysosomal beta-hexosaminidase. In the present study, the open reading frame (ORF) of the HEXB gene in a family of Japanese domestic cats with G(M2) gangliosidosis variant 0 (Sandhoff disease) was determined. Two types of abnormal cDNA clones were obtained from the liver of an affected cat tissue. One showed a single nucleotide substitution from C to T at nucleotide position 667 of the HEXB ORF. In the deduced amino acid sequence, the codon of arginine was altered to a stop codon. The genotyping, using PCR-primer introduced restriction analysis confirmed that Sandhoff disease in this family is associated with this nonsense mutation. Discovery of the nonsense mutation will permit the confirmation of the clinical diagnosis of Sandhoff disease in conjugation with the already established enzyme-based test.

Emperipolesis-like invasion of neoplastic lymphocytes into hepatocytes in feline T-cell lymphoma.

Twelve cases of feline malignant lymphoma with emperipolesis-like invasion of neoplastic lymphocytes were examined microscopically, immunohistochemically and ultrastructurally. Intracytoplasmic invasion of neoplastic cells varied in severity between the cases, between hepatic lobules and between areas within the lobules. The number of infiltrating neoplastic cells ranged from one to several per hepatocyte. Neoplastic cells exhibited widely varying morphology from case-to-case and cell-to-cell within each case, and contained eosinophilic cytoplasmic granules in four cases. Immunohistochemical examination revealed that neoplastic cells in 11 of the 12 cases expressed one or both T-cell markers (CD3 and TIA-1). Diagnosis of T-cell lymphoma was also confirmed by assessment of clonality by polymerase chain reaction. Ultrastructural analysis revealed that the neoplastic lymphocytes were contained within an invagination of the cell membrane of the hepatocyte, rather than directly infiltrating into the cytoplasm of the cell. There was no evidence that the invasive neoplastic lymphocytes had a cytotoxic effect.

A new method of thoracocentesis using CT guidance in patients with a small amount of pleural fluid.

A new technique of CT-guided diagnostic thoracocentesis (CT-TC) for patients with a small amount of pleural fluid was performed in 52 patients. More than 10 ml of pleural fluid was obtained successfully without any complications in all cases; 14 patients were found to have malignant cells in the pleural fluid. The main points of the CT-TC procedure are as follows: (1) The patient is placed supine with two radiolucent blocks underneath the shoulders and hips in order to make space for inserting the needle from the back (below). (2) Serial CT images are obtained to determine the insertion route and to measure the depth of the fluid level below the skin. (3) The needle is bent at the appropriate angle and length and is advanced upward slowly from the skin entry point on the back. CT-TC can also be used therapeutically in debilitated patients who can not maintain a sitting position or when the pleural fluid needs to be drained completely.