Surface-associated sialic acid is an immunological adjuvant

Serum sialic acid levels in patients with oral and maxillofacial malignancy

Serum sialic acid levels were measured using the thiobarbituric acid method in 80 healthy subjects and in 40 patients with benign and 61 with malignant tumors in the oral and maxillofacial region. It was shown that the cancer group had statistically higher sialic acid levels than control group and the group with benign disease (P less than .05), but no significant difference was noted between the normal control group and the patients with benign tumor (P greater than .05). Serum sialic acid levels were significantly higher in the patients with stages III and IV cancer than in those individuals with stage I and II cancer, but no differences were seen between stages I and II, and between stages III and IV cancer patients (P greater than .05). There was also no difference when considering the anatomic site of the malignant lesion. Furthermore, during the serial sialic acid determination in cancer patients before and following treatment, the sialic acid levels usually declined with remission of the disease and increased with recurrence, metastasis, or a poor prognosis. We conclude from this study that the sequential measurement of sialic acid level is particularly useful in monitoring patients with oral cancer, and sialic acid may prove to be a valuable tumor marker in oral and maxillofacial malignancy.

On the interaction of Trypanosoma cruzi neuraminidase and human lipoproteins

Binding and penetration of Trypanosoma cruzi to host cells is a process that preludes infection and is mediated by specific recognition molecules. Neuraminidase is one of the parasite molecules involved in infection and, in this review, we describe some of its biochemical characteristics, its interaction with human lipoproteins and its effect on infection of mammalian cells.

L-fucosidase treatment blocks myelin phagocytosis by macrophages in vitro

Myelin phagocytosis in nerves undergoing Wallerian degeneration has been shown to depend on their invasion by non-resident, hematogenous macrophages. This process can be studied in vitro using organ cultures of peripheral nerves exposed to cultured peritoneal macrophages. The present report concerns the role of cell surface carbohydrates in the invasion of degenerating nerves and in the recognition and ingestion of myelin by the phagocytic cells. Additional experiments explored the effect of pH, calcium and cytochalasin D on myelin phagocytosis. Organ cultures with peritoneal macrophages were treated with 14 simple or complex sugars or with eight sugar-splitting enzymes. Macrophage invasion was diminished by many simple or complex sugars, but exposure to sugars had no effect on the recognition or ingestion of myelin by the invading macrophages. Macrophage invasion was abolished upon treatment with beta-mannosidase. Exposure to L-fucosidase abolished the myelin phagocytic capacity of invading macrophages completely without affecting their capacity to ingest carbon or latex particles. The results indicate that the phagocytosis of myelin by macrophages is an L-fucosidase-sensitive process, probably by interaction with their complement receptor type C3.