In this review the authors discuss three immunologically unique aspects of the central nervous system (CNS). The first relates to whether the CNS is really an immunologically privileged site. ...Although still somewhat controversial, the answer to that question is that the CNS is, to a large extent, an immunologically privileged site. The second unique aspect of the CNS is the origin and significance of the microglial cell. Some microglial cells seem to originate from the systemic circulation, whereas other microglial cells seem to have a primary CNS origin. The function of the microglial cell is that of a macrophage. In addition it may play an important role in the immune response of the CNS. Present evidence suggests that the microglial cell can be classified as a lymphoreticular cell and as such is the only member of this cell type present in the CNS under normal circumstances. The final unique aspect of the central nervous system is the cerebrospinal fluid (CSF). Under normal circumstances this fluid is essentially acellular, and the only immunoglobulins present are those that are passively derived by diffusion from the systemic circulation. However, in pathological situations (i.e., demyelinating diseases, infections, and possibly even tumors) a local immune response occurs within the CNS and can result in the production of immunoglobulins. At present the detection of such local immune responses in CSF is predominately of diagnostic value only. However, these local CNS immune responses almost certainly play an important role in the pathogenesis of the diseases in which they occur.
Metrizamide (Amipaque) is a new water-soluble contrast agent for use in the intrathecal space. Extensive animal and clinical studies have demonstrated its low toxicity. The advantages to the use of ...metrizamide include the fact that it is miscible with cerebrospinal fluid and can fill narrow spaces, is sufficiently radiopaque to outline delicate structures within the central nervous system, is completely resorbed from the subarachnoid space, and, to date, has not been implicated in the formation of adhesive arachnoiditis. Application of metrizamide to the evaluation of neurologically diseased patients has included myelography, intracranial cisternography, and ventriculography, as well as various techniques in conjunction with computerized tomography. These various uses of metrizamide are discussed together with some indications and advantages. Metrizamide has now replaced Pantopaque and gas as the most commonly used intrathecal contrast agent at the University of Texas Health Science Center at Dallas.
The sublabial trans-sphenoidal approach for the ablation of pituitary tumors can cause denervation or pulp death of some of the anterior teeth. The problem results from the bone removal necessary for ...placement of the nasal retractor. When bone is removed close to the apices of the anterior teeth, root injury may occur. This complication may be avoided through preoperative evaluation of skeletal and dental morphology. This evaluation reveals the amount of bone between the tooth roots and the nasal floor and hence the ultimate access for the nasal retractor.
The communication between the subarachnoid space and the surgically created tumor cavity in glioma patients was evaluated by metrizamide cisternography. It was necessary to know the presence or ...absence of such a communication to determine the route of administration of autologous lymphocytes as a form of immunotherapy. The contrast injections were made either into the spinal subarachnoid space or directly into the tumor cavity. The presence of communication was demonstrated and followed by computerized tomographic (CT) scanning. The results were also corroborated by comparing the white cell counts in the fluid from the tumor cavity and the spinal subarachnoid space 24 hours after autologous lymphoid cell infusion. In only two of seven patients was a communication present. In the five patients without a communication, the blocks were at the tentorial hiatus (one patient), due to a nonpatent subarachnoid space over the cerebral convexity (two patients), and the result of adhesions at the pial margin of the tumor cavity (three patients). In addition, certain limitations in the use of computerized tomography in the evaluation of glioma patients are demonstrated. These problems include the effects of steroids on tumor size, the poor correlation between "enhancement" on CT scan and tumor recurrence, and the difficulty of differentiating metrizamide and hemorrhage by CT scan in the immediate postoperative period. (Neurosurgery, 5: 576--582, 1979).
The effect of polyadenylic acid, a potent inhibitor of mammalian and bacterial RNAses, on the binding of human liver RNAse to its antibody was studied. To do this, a human liver RNAse antibody was ...immobilized on Sepharose 4B. Examination of the ability of the enzyme to bind to the immobilized anti-RNAse in the presence or absence of polyadenylic acid indicated that enzyme-antibody binding was more sensitive to the presence of polyadenylic acid than was enzyme activity. Furthermore, the effect of polyadenylic acid on enzyme-antibody binding was specific since neither polycytidylic acid nor polyuridylic acid had much effect on the antigenicity of the enzyme. The metal cation, Mg2+, and the polyamine, spermidine, but not putrescine, readily reversed the effects of polyadenylic acid on enzyme-antibody binding.
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