Ganglioside-hydrolyzing sialidase activity was solubilized from rat brain particulate fraction by using Triton X-100 plus sodium deoxycholate. When chromatographed on AH-Sepharose 4B, the solubilized activity was resolved into two peaks, which were designated sialidases I and II in order of elution. The two sialidases were purified by using sequential chromatographies on Octyl-Sepharose CL-4B, Phenyl-Sepharose CL-4B, and Sephadex G-200. Sialidase II was purified further by Mono Q-FPLC. Overall purification was 450- and 2,150-fold, for sialidases I and II, respectively. Purified sialidases I and II were maximally active at near pH 5.0 and exhibited M = 70,000 by gel filtration. Sialidase I hydrolyzed gangliosides but scarcely other substrates including 4-methylumbelliferyl-NeuAc (4MU-NeuAc). Sialidase II hydrolyzed oligosaccharides, glycoproteins, and 4MU-NeuAc although gangliosides appeared to be preferential substrates. Sialidase II cleaved GM2 much faster than sialidase I. An antibody raised in rabbits against sialidase I reacted with only sialidase I and an antibody against sialidase II reacted with only sialidase II. A subcellular distribution study suggested sialidase I in the synaptosomal membrane and sialidase II in the synaptosomal and lysosomal membranes, and this was verified by using the above antibodies.

Cytosolic sialidase was purified from rat skeletal muscle, and the purified enzyme migrated as a single band of Mr 43,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A polyclonal antibody raised against the enzyme inhibited and immunoprecipitated rat liver cytosolic sialidase as well as the muscle enzyme but failed to cross-react with the intralysosomal sialidase of rat liver and membrane sialidases I (synaptosomal) and II (lysosomal) of rat brain. The antibody against brain membrane sialidase I (anti-I) and that against sialidase II (anti-II), which could be useful to discriminate the two enzymes, did not cross-react with the intralysosomal and cytosolic sialidases of liver. Although more than 90% of liver plasma membrane sialidase was immunoprecipitated with anti-I, only 60% of liver lysosomal membrane sialidase was immunoprecipitated with anti-II, the remainder being immunoprecipitated with anti-I. In confirmation of these data, liver lysosomal membrane exhibited two peaks of ganglioside sialidase corresponding to the membrane sialidases I and II on Aminohexyl-Sepharose chromatography while only one peak of ganglioside sialidase corresponding to sialidase I was observed for liver plasma membrane. These results indicate that the four types of rat sialidase are proteins distinct from one another and that the three kinds of antisera described above are useful for discriminating these sialidases qualitatively and probably quantitatively.

The substrate specificity and subcellular location of the major sialidases of three types of rat blood cells were characterized and compared with those of the known three types of rat liver sialidase, which have been designated intralysosomal, cytosolic, and plasma membrane-associated sialidases. Platelets and leucocytes contain mainly an acid sialidase, which is highly active towards oligosaccharides and 4MU-NeuAc, and erythrocytes possess a high level of a sialidase acting on gangliosides. A Percoll gradient centrifugation study showed that the former is located in lysosomes and the latter in plasma membrane. When the sialidase was solubilized and partially purified from erythrocyte ghosts, the enzyme was found to hydrolyze actively gangliosides but only poorly other substrates such as 4MU-NeuAc, oligosaccharides, and glycoproteins. The sialidase partially purified from rat liver membrane fraction exhibited the same substrate specificity. It is concluded that the major sialidase of platelets and leucocytes corresponds to hepatic intralysosomal sialidase while erythrocytes contain almost exclusively a ganglioside sialidase which corresponds to hepatic plasma membrane sialidase.

This paper delineates which lymph nodes should be dissected due to the high frequency of metastasis associated with different types of primarily lesions of the thoracic esophagus. In cancer involving the upper third of the esophagus (Iu), lymph flow was found to be primary from the superior mediastinal area to the cervical area; in that involving the middle third (Im), it was broadly distributed from the superior, middle, and inferior mediastinal region to the cervical and abdominal regions; and in that involving the lower third (Ei), it tended to extend from the inferior mediastinal region to the abdominal region, with single primary metastatic nodes also being noted in this area. The significance of the "top" nodes, namely, the nodes located along the right recurrent laryngeal nerve in the upper portion of the thorax, was also investigated, and it was confirmed that the prognosis for patients with metastases to both the top nodes and other nodes was unfavorable. An immunohistochemical study on mediastinal lymph flow using the anti-Su-Ps antibody demonstrated interactions between top nodes and cervical and/or thoracic nodes.

Sialidase and sialyltransferase activities were studied in JB6 mouse epidermal cells before and after exposure to phorbol ester, 12‐O‐tetradecanoyl phorbol‐13‐acetate (TPA), which irreversibly induces anchorage‐independent growth and tumorigenicity. JB6 cells exhibited sialidase activities toward 4‐methylumbelliferyl‐α‐d‐N‐acetylneuraminic acid (4MU‐NeuAc) and gangliosides at pH 4.5 in the particulate fraction but apparently not in the cytosol at pH 4.5 or 6.0. In JB6 cells exposed to TPA and in the anchorage‐independent transformants, the sialidase activity toward 4MU‐NeuAc was decreased and the activity toward gangliosides was increased compared with those in untreated JB6 cells. Immunological analysis with antisera against membrane‐associated sialidases I and II revealed that plasma membrane‐associated sialidase I was increased and lysosomal membrane‐associated sialidase II was decreased under these conditions. TPA treatment also affected the sialyltransferase activities of JB6 cells: an elevation of the transfer activities toward asialo‐orosomucoid and asialo‐porcine submaxillary mucin but a reduction of GM3 and GD3 synthase activities were observed on exposure to TPA and in cells transformed by TPA to retain anchorage‐independency. These results suggest that an increase in sialic acid bound to glycoproteins and a decrease in that bound to glycolipids may occur in JB6 cells exposed to TPA and in the anchorage‐independent transformants.

A highly malignant case of intrathyroidal thymic carcinoma showing morphological and biochemical evidence identical with mediastinal thymoma is presented. A 32-year-old female, who had previously undergone total colectomy with ileo-proctostomy due to familial adenomatous polypnosis, was operated on for a tumor (3.4 x 4.5 cm) originating from the left thyroid lobe. A minute focus (diam. 0.8 cm) of papillary adenocarcinoma also existed in the upper pole of the right lobe. The main tumor was morphologically an epithelial thymoma with scanty lymphocyte intermixing and showed medullary differentiation with apparent Hassall's corpuscles. Mitosis was frequent and numerous tumor thrombi were in the subcapsular veins. Five months after the total thyroidectomy and lymph node dissection, a subcutaneous recurrence of the tumour (diam. 2.3 cm) appeared in the anterior cervical region. The cystic contents of the recurrent tumor revealed a high titer of thymosin alpha 1-Other organs, including thymus, lungs, and adrenals, had all been free of neoplastic changes clinically and radiologically for 5 months after her first admission until the local tumor recurrence.

Rat liver participate fraction contains two types of membrane‐associated and gangliosides‐hydrolyzing sialidase, which have been shown to be identical to two membrane‐associated sialidases of rat brain (I and II) chromatographically, immunologically and in substrate specificity. Chromatography on AH‐Sepharose 4B of the membrane sialidases of rat primary hepatoma induced by 3′‐methyl‐4‐dimethylaminoazobenzene (MeDAB) further revealed that hepatocarcinogenesis induces a marked decrease in sialidase II but no decrease in sialidase I. Using antisera against sialidases I and II of rat brain, immunoprecipitation studies of the solubilized particulate fractions of rat liver and MeDAB‐hepatoma gave results similar to those obtained chromatographically. Using the same immunological technique, sialidase II but not sialidase I was found to be decreased in AH109 A hepatoma and in regenerating and fetal liver.

Administration of low concentrations of valine via the portal vein simultaneous with central venous administration of valine-depleted TPN solution may prevent fatty liver.