Ossified posterior longitudinal ligament with an atypical clinical presentation in an Indian male. A case report.

Ossification of the posterior longitudinal ligament is an uncommon disorder mostly seen in the Japanese population and hence termed by some the "Japanese disease". Ossification of the posterior longitudinal ligament is more common in the cervical spine (2). Clinically it is usually asymptomatic, but serious neurological deficits have been seen in some patients (2). The ossified mass composed of lamellar bone and focal calcified cartilage expands in volume causing spinal canal stenosis and cord compression. Morphologically, four forms of ossification of the posterior longitudinal ligament have been described: continuous, segmental, mixed and rarely a focal retrodiscal form (4). CT scan is the method of choice for detecting the presence and extent of the ossified mass. MR imaging is helpful in depicting the nature of cord compression such as myelomalacia, edema, demyelination or cyst formation and root sleeve involvement.

Early nonspecific immune responses and immunity to blood-stage nonlethal Plasmodium yoelii malaria.

The early role of natural killer cells and gamma delta T cells in the development of protective immunity to the blood stage of nonlethal Plasmodium yoelii infection was studied. Splenic cytokine levels were measured 24 h after infection of natural killer cell-depleted immunodeficient and littermate mice or transiently T-cell-depleted normal mice. Splenic gamma interferon levels were significantly increased above background in immunodeficient and littermate mice 24 h after infection. Depletion of natural killer cells resulted in markedly depressed gamma interferon levels and poor control of parasitemia, particularly in severe combined immunodeficient mice. In the littermates, gamma interferon levels were partially reduced, but parasitemias were resolved normally. However, in athymic mice, natural killer cell depletion had no effect on gamma interferon production. Levels of tumor necrosis factor alpha were increased in all animals 24 h after infection, and responses were not affected by natural killer cell depletion. However, in T-cell-depleted animals, both gamma interferon and tumor necrosis factor alpha levels were decreased 24 h after infection, and depleted mice were unable to control their parasitemia. These results suggest that the early production of both cytokines is important in the early control of parasitemia and that both natural killer and gamma delta T cells contribute equally towards their production. The data also suggest that the subsequent resolution of infection requires early production of gamma interferon, which might act by switching on the appropriate T-helper-cell subsets and other essential parasitotoxic effector mechanisms.