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Object: An approach toward the treatment of intracranial gliomas was developed in a rat experimental model. The authors investigated the ability of "professional" antigen-presenting cells (dendritic cells) to enhance host antitumor immune responses when injected as a vaccine into tumor-bearing animals., Methods: Dendritic cells, the most potent antigen-presenting cells in the body, were isolated from rat bone marrow precursors stimulated in vitro with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4. Cultured cell populations were confirmed to be functional antigen-presenting cells on the basis of expressed major histocompatibility molecules, as analyzed by fluorescence-activated cell sorter cytofluorography. These dendritic cells were then pulsed (cocultured) ex vivo with acid-eluted tumor antigens from 9L glioma cells. Thirty-eight adult female Fischer 344 rats harboring 7-day-old intracranial 9L tumors were treated with three weekly subcutaneous injections of either control media (10 animals), unpulsed dendritic cells (six animals), dendritic cells pulsed with peptides extracted from normal rat astrocytes (10 animals), or 9L tumor antigen-pulsed dendritic cells (12 animals). The animals were followed for survival. At necropsy, the rat brains were removed and examined histologically, and spleens were harvested for cell-mediated cytotoxicity assays. The results indicate that tumor peptide-pulsed dendritic cell therapy led to prolonged survival in rats with established intracranial 9L tumors implanted 7 days prior to the initiation of vaccine therapy in vivo. Immunohistochemical analyses were used to document a significantly increased perilesional and intratumoral infiltration of CD8+ and CD4+ T cells in the groups treated with tumor antigen-pulsed dendritic cells compared with the control groups. In addition, the results of in vitro cytotoxicity assays suggest that vaccination with these peptide-pulsed dendritic cells can induce specific cytotoxic T lymphocytes against 9L tumor cells., Conclusions: Based on these results, dendritic antigen-presenting cells pulsed with acid-eluted peptides derived from autologous tumors represent a promising approach to the immunotherapy of established intracranial gliomas. which may serve as a basis for designing clinical trials in patients with brain tumors.

The bradykinin analog, RMP-7, was investigated for its ability to increase selectively the transport of 68Ga ethylenediamine tetraacetic acid (EDTA) into recurrent malignant gliomas in nine patients. For each patient, two position emission tomography (PET) studies (one with and one without RMP-7) were performed. For studies with RMP-7, 10 to 300 ng/kg of the compound was infused into the supraophthalmic carotid artery over 15 minutes. In each PET study, a sequence of PET scans was initiated simultaneously with an intravenous bolus of 68Ga EDTA (5-10 mCi). Arterial samples were taken to provide the input function. All PET scans were coregistered to the magnetic resonance (MR) images of the patient. Regions of interest were defined for tumor and normal tissue regions on MR images and were copied to the coregistered PET dynamic images to provide brain tissue-time activity curves. The constant (Ki) for the transport of gallium-68 from plasma to brain tissue was determined using a simple compartmental model. Intracarotid infusion of RMP-7 significantly increased transport into tumor regions with an average increase of 46 +/- 42% (mean +/- standard deviation, p < 0.05). Permeability in normal tissue regions was not significantly increased. Tumors in three of six patients treated with 300 ng/kg RMP-7 and carboplatin had at least a 50% reduction in tumor volume as measured by MR imaging. Intracarotid infusion of RMP-7 is a novel technique for selective delivery of antitumor compounds into brain tumors.

The bradykinin analog, RMP-7, was investigated for its ability to selectively increase uptake of molecular tracers in RG2 glial tumors. When infused in low doses (0.1 microgram/kg/min) through the intracarotid artery ipsilateral to RG2 gliomas in rats, RMP-7 significantly increased the permeability of tumor capillaries to methotrexate and to four other tracers of varying molecular weights, compared to intracarotid infusion of vehicle alone. Tracers used to examine permeability included radiolabeled alpha-aminoisobutyric acid (M(r) 103 D), sucrose (M(r) 342 D), methotrexate (M(r) 454.5 D), inulin (M(r) 5000 D), and dextran (M(r) 70,000 D). Permeability was expressed as the unidirectional transfer constant, Ki (microliters/gm/min). The permeability (Ki) of tumors in the RMP-7 group compared to the vehicle control group was as follows: alpha-aminoisobutyric acid, 35.3 +/- 9.11 versus 12.7 +/- 4.56 (p < 0.001); sucrose, 16.5 +/- 3.83 versus 9.28 +/- 3.12 (p < 0.05); methotrexate, 26.3 +/- 10.3 versus 8.98 +/- 6.78 (p < 0.005); inulin, 13.5 +/- 3.23 versus 6.55 +/- 4.32 (p < 0.005); dextran, 15.2 +/- 3.42 versus 1.47 +/- 1.24 (p < 0.001). The permeability of RG2 gliomas to high-molecular-weight dextran (70,000 D) was 10.3-fold higher in the RMP-7 group than in the vehicle control group. Intracarotid infusion of RMP-7 did not significantly increase the blood volume in tumor or brain tissue. The permeability of normal brain capillaries was unaffected by intracarotid infusion of 0.1 microgram/kg/min RMP-7 relative to that achieved in tumor. These data support the idea that intracarotid infusion of RMP-7 will be a useful technique for selective delivery of antitumor compounds to brain tumors.

Leukotriene C4 (LTC4) increases vascular permeability in systemic, brain tumor, and ischemic brain capillaries, but not in normal brain capillaries. This study examines whether the abundance of gamma-glutamyl transpeptidase (gamma-GTP) in normal brain capillaries might act as an enzymatic barrier to vasoactive leukotrienes in the brain. Blood-brain barrier (BBB) permeability was determined by quantitative autoradiography using 14C-aminoisobutyric acid. Ischemia was produced by occluding the middle cerebral artery. Seventy-two hours after occlusion, gamma-GTP activity in ischemic brain disappeared, and LTC4 (4-micrograms total dose), which was infused into the carotid artery ipsilateral to the occlusion, selectively increased permeability, Ki, approximately twofold within core ischemic tissue and adjacent tissue, compared to vehicle alone in seven brains (15.53 +/- 6.03 vs. 7.29 +/- 3.36, p < 0.05, and 8.76 +/- 4.02 vs. 4.32 +/- 2.65, p < 0.05, respectively). No effect on BBB was seen in nonischemic brain tissue. Twenty-four hours postocclusion, gamma-GTP activity was still present, and LTC4 infusion did not increase permeability within ischemic tissue. However, inhibition of gamma-GTP with acivicin allowed LTC4 to increase permeability even 24 hours after occlusion in ischemic core and adjacent tissue compared to vehicle alone in seven brains (17.21 +/- 16.32 vs. 8.23 +/- 6.58, p < 0.05, and 11.78 +/- 7.96 vs. 4.56 +/- 1.93, p < 0.01, respectively). Acivicin almost completely blocked both the histochemical activity of gamma-GTP in brain capillaries and the metabolism of LTC4 in isolated bovine capillaries. These findings suggest that gamma-GTP may help normal brain capillaries resist the vasoactive effects of LTC4. In contrast, gamma-GTP is lost in injured brain capillaries, which allows LTC4 (in combination with other factors) to increase vascular permeability in ischemic brain and brain tumors.

Twenty-six patients with petroclival lesions were operated on via a petrosal approach designed to preserve hearing. The surgical pathology included 14 meningiomas, three chordomas, three epidermoid cysts, four vertebrobasilar aneurysms, and two pontine cavernous malformations. The approach allowed complete resection of 14 of 20 tumors and definitive treatment of all six vascular lesions. Complications included cerebrospinal fluid leakage in three patients, high-frequency sensorineural hearing loss in three, meningitis in one, and cranial nerve palsies (which were usually transient). This approach allows a wide exposure of the petroclival region with decreased operating distance. Cerebellar and temporal lobe retraction are minimized, dural sinus patency is maintained, and the inner ear structures are not sacrificed. The approach is suitable for neoplastic or vascular lesions involving the petroclival region, the ventral pons, or the basilar artery trunk. The surgical technique, indications, and neuro-otological considerations are discussed.

The authors have previously reported that intracarotid infusion of 5 micrograms leukotriene C4 (LTC4) selectively increases blood-tumor barrier permeability in rat RG-2 tumors. In this study, rats harboring RG-2 tumors were given 15-minute intracarotid infusions of LTC4 at concentrations ranging from 0.5 microgram to 50.0 micrograms (seven rats in each dose group). Blood-tumor and blood-brain barrier permeability were determined by quantitative autoradiography using 14C aminoisobutyric acid. The transfer constant for permeability (Ki) within the tumors was increased twofold by LTC4 doses of 2.5, 5.0, and 50.0 micrograms compared to vehicle alone (90.00 +/- 21.14, 92.68 +/- 15.04, and 80.17 +/- 16.15 vs. 39.37 +/- 6.45 microliters/gm/min, respectively; mean +/- standard deviation; p less than 0.01). No significant change in Ki within the tumors was observed at the 0.5-microgram LTC4 dose. Blood-brain barrier permeability was selectively increased within the tumors. At no dose in this study did leukotrienes increase permeability within normal brain. To determine the duration of increased opening of the blood-tumor barrier by LTC4 administration, Ki was measured at 15, 30, and 60 minutes after termination of a 15-minute LTC4 infusion (seven rats at each time point). The mean Ki value was still high at 15 minutes (92.68 +/- 15.04 microliters/gm/min), but declined at 30 minutes (56.58 +/- 12.50 microliters/gm/min) and 60 minutes (55.40 +/- 8.10 microliters/gm/min) after the end of LTC4 infusion. Sulfidopeptide leukotrienes LTC4, LTD4, LTE4 and LTF4 were infused to compare their potency in opening the blood-tumor barrier. The mean leukotriene E4 was the most potent, increasing the permeability value 3 1/2-fold compared with vehicle alone (139.86 +/- 23.95 vs. 39.37 +/- 6.45 microliters/gm/min).

To determine if leukotrienes are important mediators of vascular permeability in brain tumors, the effect of 5-lipoxygenase inhibitors on blood-tumor barrier permeability in rats harboring HK Walker 256 brain tumors was examined using quantitative autoradiography with alpha-14C-aminoisobutyric acid. The 5-lipoxygenase enzyme converts arachidonic acid to leukotrienes. Three 5-lipoxygenase inhibitors were utilized: BW755C, nordihydroguaiaretic acid, and AA-861. All three 5-lipoxygenase inhibitors significantly decreased vascular permeability both within the tumors and in brain adjacent to tumor. This suggests that capillary permeability in and adjacent to tumors is influenced by endogenous leukotrienes and that leukotrienes play an important role in brain tumor edema.

In order to determine the in vivo immune response in glioblastoma, monoclonal and polyclonal antibodies specific for inflammatory leukocytes and immunoregulatory products were utilized to stain tissue from four surgical specimens. The more activated the inflammatory cells, the more activated the tumors appeared to be. In the tumor with the largest infiltration (Case 3), inflammatory cells were stained for interferon-gamma, interleukin-2, interleukin-1 beta, lymphotoxin, tumor necrosis factor-alpha, and transforming growth factor-beta. The tumor cells also expressed interleukin-1 beta, interleukin-6, transforming growth factor-beta, tumor necrosis factor-alpha, and prostaglandin E. In contrast, in the tumor with the least inflammatory response (Case 1), the tumor cells did not express any cytokines. Expression of cytokines by glioma cells was modest in the two cases with modest inflammatory responses. Cellular inflammation, primarily consisting of T cells and macrophages with few or no B cells or natural killer cells, was two- to 15-fold greater outside the tumor than within. In contrast to leukocytes outside the tumor, which were activated and expressing class II major histocompatibility antigens, leukocytes within the tumor parenchyma or at the tumor's edge were negative for these antigens. In the four specimens studied here, the tumor cells themselves were also negative for class II major histocompatibility antigens. These findings, although preliminary, suggest that inflammatory cells within gliomas are inactivated and that glioma cells may increase the expression of immunosuppressive cytokines in response to an increased lymphocyte infiltrate. This observation, if corroborated by more extensive studies, may help to explain the failure of immune treatments in glioblastoma multiforme.

Malignant gliomas have been difficult to treat with chemotherapy. The most effective agent, BCNU (carmustine), has considerable systemic toxicity and a short half-life in serum. To obviate these problems, a method has been developed for the local sustained release of chemotherapeutic agents by their incorporation into biodegradable polymers. Implantation of the drug-impregnated polymer at the tumor site allows prolonged local exposure with minimal systemic exposure. In this Phase I-II study, 21 patients with recurrent malignant glioma were treated with BCNU released interstitially by means of a polyanhydride biodegradable polymer implant. Up to eight polymer wafers were placed in the resection cavity intraoperatively, upon completion of tumor debulking. The polymer releases the therapeutic drug for approximately 3 weeks. Three increasing concentrations of BCNU were studied; the treatment was well tolerated at all three levels. There were no adverse reactions to the BCNU wafer treatment itself. The average survival period after reoperation was 65 weeks for the first dose group, 64 weeks for the second dose group, and 32 weeks for the highest dose group. The overall mean survival time was 48 weeks from reoperation and 94 weeks from the original operation. The overall median survival times were 46 weeks postimplant and 87 weeks from initial surgery. Eighteen (86%) of 21 patients lived more than 1 year from the time of their initial diagnosis and eight (38%) of 21 patients lived more than 1 year after intracranial implantation of the polymer. Frequent hematology, blood chemistry, and urinalysis tests did not reveal any systemic effect from this interstitial chemotherapy. Since the therapy is well tolerated and safe, a placebo-controlled clinical trial has been started. The trial will measure the effect of the second treatment dose on survival of patients with recurrent malignant glioma.

The efficacy of U-74006F and U-78517F in the treatment of blood-tumor barrier permeability and tumor-associated neurological dysfunction was evaluated in a brain-tumor model in rats. U-74006F is a 21-aminosteroid and U-78517F is a 2-methylamino chroman. Rats with stereotactically implanted Walker 256 tumors were treated with methylprednisolone, U-74006F, U-78517F, or vehicle (0.05 N HCl) on Days 6 through 10 following implantation. Neurological function and vascular permeability were assessed on Day 10. Methylprednisolone and U-74006F were equally effective at preventing neurological dysfunction compared to the control group (p less than 0.01); U-78517F was slightly less effective than U-74006F and methylprednisolone but was significantly better than vehicle in preventing neurological dysfunction. Delivery of methylprednisolone resulted in a significant decrease in tumor vascular permeability (p less than 0.006) while U-74006F and U-78517F had no effect on permeability. This suggests that U-74006F and U-78517F prevented tumor-associated neurological dysfunction by a mechanism other than decreasing permeability in tumor capillaries, and that U-74006F or U-78517F could prove useful in the treatment of brain tumors.

Intracarotid infusions of leukotriene C4 (LTC4) were used to selectively open the blood-tumor barrier in rats with RG-2 gliomas. Blood-brain and blood-tumor permeability was determined by quantitative autoradiography using 14C aminoisobutyric acid. Leukotriene C4 (4 micrograms total dose) infused into the carotid artery ipsilateral to the tumor increased twofold the unidirectional transfer constant for permeability within the tumor while no effect on permeability was seen in normal brain. No gamma glutamyl transpeptidase (gamma-GTP) activity was seen in tumor capillaries in contrast to high gamma-GTP in normal brain capillaries. These findings suggest that normal brain capillaries may resist the vasogenic effects of LTC4, while LTC4 will increase permeability in tumor capillaries. This could relate to the ability of gamma-GTP to act as an enzymatic barrier and inactivate leukotrienes in normal brain capillaries. Intracarotid LTC4 infusion may be a useful tool to selectively open the blood-tumor barrier for delivery of antineoplastic compounds.

A quantitative preoperative technique using thallium-201 single-photon emission computerized tomography is described which predicts whether specific gliomas are of high- or low-grade malignancy. An index, based on the ratio of thallium uptake in the tumor versus the homologous contralateral brain, was calculated and compared with tumor histology. The index in 14 patients with low-grade malignant gliomas was 1.27 +/- 0.40 in contrast to an index of 2.40 +/- 0.61 in 11 patients with high-grade malignant gliomas (p less than 0.0005). Whether gliomas were of low- or high-grade malignancy could be predicted with 89% accuracy using a threshold of 1.5. Low-grade gliomas with an index higher than 1.5 acted biologically more like high-grade tumors, and no tumor histologically classified as being of high-grade malignancy had an index lower than 1.7. This technique could help to reduce unrecognized sampling errors during needle biopsies of brain tumors, particularly of high-grade lesions classified in error as low-grade tumors due to inadequate biopsy material.

A patient with herniated thoracic discs in tandem is reported. The previous literature is reviewed. Difficulties with the preoperative diagnosis and the surgical approach to these lesions are discussed.

The effect of standard parenteral nutritional formulas on cold-induced vasogenic edema formation in cats was examined and compared to the effects of 5% dextrose, 0.9% saline, and 40.5% mannitol. The amount of vasogenic edema formed during a 3-hour period of fluid infusion following cold injury was quantified by a computerized graphics tablet determination of the volume of Evans blue-dyed white matter. Specific gravity measurements were taken as a measure of white matter water content. Serum osmolality, urine output, arterial blood gases, hematocrit, body temperature, and systolic blood pressure were measured periodically throughout the infusion period. Parenteral nutritional formulas and a 40.5% mannitol solution produced greater changes in serum osmolality than did 5% dextrose or 0.9% saline. Greater changes in serum osmolality were associated with larger calculated volumes of edema in the injured hemisphere and lower water contents in the uninjured hemisphere. The data indicate that hyperosmolar solutions may potentiate vasogenic edema formation when the blood-brain barrier is open.

Peripheral benzodiazepine receptor ligands were utilized to selectively image intracerebrally implanted C6 gliomas, RG-2 gliomas, and Walker 256 metastatic tumors by means of quantitative autoradiography. Intravenous injections of 3H-PK11195 (1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide) or 3H-flunitrazepam in combination with clonazepam revealed high densities of peripheral benzodiazepine binding in glial tumors, with less binding in metastatic tumors. Peripheral binding was displaced by preadministration of excess PK11195. Topographical correlation was excellent between areas of histologically verified tumor and high densities of peripheral benzodiazepine binding. The choroid plexus, ependyma, and pineal gland also showed a moderate level of binding, but there was little binding in other normal brain structures or necrotic tissue. Binding densities were three- to fivefold higher in C6 glial tumors compared to normal cortex. Injection of 3H-flunitrazepam alone, which binds to both central and peripheral receptors, had the advantage of showing normal anatomic structures in addition to a clear definition of tumor topography. The potential value of peripheral benzodiazepine ligands in selectively imaging brain tumors in man with positron emission tomography is discussed.

The use of intraoperative color-flow Doppler sonography to image cerebral and spinal arteriovenous malformations (AVM's) and a giant aneurysm is reported in 10 patients. The technique is a useful adjunct in localizing vascular lesions, identifying feeding or draining vessels, and confirming intraoperative surgical excision of AVM's or ligation of giant aneurysms. Imaging of lesions deeper than 4 to 5 cm is, however, limited with the equipment design now commercially available.

Eicosapentaenoic acid (EPA) has been reported to improve postischemic cerebral blood flow (CBF). The present study was designed to determine whether sodium 5-(3'-pyridinylmethyl)benzofuran-2-carboxylate (U-63557A), a selective thromboxane synthetase inhibitor, could potentiate the effects of EPA on CBF in ischemic gerbils. Ischemia was produced by bilateral carotid artery occlusion for 15 minutes followed by reperfusion for 2 hours. Immediately after ischemia, gerbils were given either an intravenous bolus of 0.167 mg of EPA followed by a continuous infusion of EPA at 1 mg/hr, or U-63557A (10 mg/kg intraperitoneally), or U-63557A and EPA, or a saline infusion. Regional CBF was measured by the hydrogen clearance method, and brain water by the specific gravity technique. Brain prostaglandins were measured by radioimmunoassay. Preischemic CBF's ranged from 27.4 to 29.5 ml/100 gm/min for the four animal groups. After ischemia and 2 hours of reperfusion, CBF in the saline-infused gerbils was significantly decreased to 19.2 ml/100 gm/min. Gerbils treated with either EPA or U-63557A alone had a CBF of 23.7 and 21.6 ml/100 gm/min, respectively. Postischemic CBF in animals treated with both U-63557A and EPA was 30.0 ml/100 gm/min, significantly higher than in saline-infused gerbils. Brain levels of 6-keto prostaglandin (PG)F1 alpha (the metabolite of PGI2) were significantly higher in gerbils treated with U-63557A and EPA compared to gerbils given EPA alone. This study indicates that U-63557A potentiates the effects of EPA on postischemic CBF. This is probably due to the ability of U-63557A to increase prostacyclin formation in the vessel wall.

The authors report their recent experience with 14 meningomyelocele patients with the Arnold-Chiari II malformation. Three major types of fourth ventricle anomalies seen in the Arnold-Chiari II malformation are defined, based on preoperative magnetic resonance imaging and intraoperative ultrasound studies. The Type A deformity is defined as no cystic dilatation of the fourth ventricle. In the Type B anomaly, there is intracranial dilatation of the fourth ventricle. The Type C deformity involves intraspinal dilatation of the fourth ventricle, either dorsal to the cord or within the substance of the cord. The Type A deformity was most common in infants, and in two cases progression from a Type A to Type B deformity was documented. Recognition of the type of Arnold-Chiari II malformation aids in designing an operative approach more specific to that structural abnormality. Intraoperative ultrasound is a valuable adjunct in localization of the underlying anomalies and permits safe decompression of the fourth ventricle. The authors' indications for surgery now include failure to thrive due to either early respiratory and swallowing dysfunction, progressive spasticity, or upper-extremity weakness. Nine patients significantly improved following surgery and three patients with a progressively deteriorating course were stabilized by surgery. Decompression of the fourth ventricle by fenestration and internal shunting appears to be well tolerated, even in young infants, and is recommended in the treatment of the Arnold-Chiari II deformity.