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Rapid detection of transferrin receptor expression on glioma cell lines by using magnetic microspheres.

A rapid method for detecting the presence of transferrin receptors (TR) on human glioblastoma-derived cell lines is presented. The development of new treatment modalities, such as immunotoxins for central nervous system cancer, requires the identification of appropriate surface antigens on tumor cells. Seven established human glioblastoma-derived cell lines were assayed for the presence of TR with antibody-coated magnetic microspheres (immunobeads). The immunobeads bound to glioblastoma cells in the presence of human anti-TR monoclonal antibodies to a significantly greater degree than to control cell lines (P < 0.0001). The expression of TR was confirmed by standard immunocytochemical techniques. A 9L rat gliosarcoma cell line was used as a nonhuman control and did not demonstrate TR expression by either the immunobead assay or immunocytochemistry. This assay represents a simple, sensitive way to detect TR expression on malignant cells, which may be useful for the identification of other cell surface antigens that can be exploited by targeted therapies.

Brain Neoplasms↗

Histological heterogeneity of human glioblastomas investigated with an unsupervised neural network (SOM).

The histological variability of Glioblastomas (GB) precludes the modern assimilation of theses tumors into a single histological tumor group. As an alternative to statistical histological evaluation, we investigated 1489 human GB in order to discover whether they could be correctly classified using Self-Organizing Maps (SOM). In all tumors 50 histological features, as well as the age and sex of the patients, were examined. Four clusters of GB with a significance of 52 (maximal significance 60) were found. Cluster C1 contained 37.47% of all GB and 41.09% of all polymorphic glioblastomas (PG). Cluster C2 included 35.06% of all GB and 44.96% of all giant cell glioblastomas (GCG). Cluster C3 contained 16.45% of all GB with a significant component of astroblasts, glioblasts and oligodendroglia. Cluster C4 included 11.01% of all GB, 87.80% of the gliosarcomas (GS) and 36.72% of all GCG. Placing a series of component windows with their maps side by side allows the immediate recognition of the dependencies on variables and the determination of variables necessary to build the specific clusters. The SOM allow a realistic histological classification, comparable to the actual classification by the WHO. In addition, we found new, small subclusters of human GB which may have a clinical significance. With SOM one can learn to discriminate, discard and delete data, select histological and clinical or genetic variables that are meaningful, and consequently influence the result of patient management.

Adolescent↗

Metronomic photodynamic therapy as a new paradigm for photodynamic therapy: rationale and preclinical evaluation of technical feasibility for treating malignant brain tumors.

The concept of metronomic photodynamic therapy (mPDT) is presented, in which both the photosensitizer and light are delivered continuously at low rates for extended periods of time to increase selective tumor cell kill through apoptosis. The focus of the present preclinical study is on mPDT treatment of malignant brain tumors, in which selectivity tumor cell killing versus damage to normal brain is critical. Previous studies have shown that low-dose PDT using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) can induce apoptosis in tumor cells without causing necrosis in either tumor or normal brain tissue or apoptosis in the latter. On the basis of the levels of apoptosis achieved and model calculations of brain tumor growth rates, metronomic delivery or multiple PDT treatments, such as hyperfractionation, are likely required to produce enough tumor cell kill to be an effective therapy. In vitro studies confirm that ALA-mPDT induces a higher incidence of apoptotic (terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate, sodium salt nick-end labeling positive) cells as compared with an acute, high-dose regimen (ALA-aPDT). In vivo, mPDT poses two substantial technical challenges: extended delivery of ALA and implantation of devices for extended light delivery while allowing unencumbered movement. In rat models, ALA administration via the drinking water has been accomplished at very high doses (up to 10 times therapeutic dose) for up to 10 days, and ex vivo spectrofluorimetry of tumor (9L gliosarcoma) and normal brain demonstrates a 3-4 fold increase in the tumor-to-brain ratio of PpIX concentration, without evidence of toxicity. After mPDT treatment, histological staining reveals extensive apoptosis within the tumor periphery and surrounding microinvading colonies that is not evident in normal brain or tumor before treatment. Prototype light sources and delivery devices were found to be practical, either using a laser diode or light-emitting diode (LED) coupled to an implanted optical fiber in the rat model or a directly implanted LED using a rabbit model. The combined delivery of both drug and light during an extended period, without compromising survival of the animals, is demonstrated. Preliminary evidence of selective apoptosis of tumor under these conditions is presented.

Apoptosis↗

Mechanisms of transport of p-borono-phenylalanine through the cell membrane in vitro.

The mechanisms of transport of p-(dihydroxyboryl)-phenylalanine (BPA) through the cell membrane were investigated in vitro, evaluating especially the systems responsible for the transport of neutral amino acids as potential carriers for BPA. Rat 9L gliosarcoma cells and Chinese hamster V79 cells were exposed to BPA under controlled conditions and in a defined medium that was free of amino acids. The time course of (10)B (delivered by BPA) uptake and efflux was measured under different conditions. To analyze the intracellular boron content, direct-current plasma atomic emission spectroscopy (DCP-AES) was used after separating the cells from extracellular boron in the cell medium using an oil filtration technique. The dependence of factors such as cell type, temperature, composition and concentration of amino acids and specific substrates for amino acid transport systems in the culture medium or in intracellular compartments on BPA uptake and efflux were studied. The results of this study support the hypothesis that BPA is transported by the L system and that transport can be further stimulated by amino acids preaccumulated in the cell by either the L or A amino acid transport system.

Animals↗

[Uptake and localization of neocarzinostatin in malignant glioma. Experimental study by immunofluorescent staining method].

The authors studied the localization of neocarzinostatin (NCS) in cultured cells and in tumor-bearing rats by means of immunofluorescent staining. Anti-NCS antibody was obtained through immunization of rabbits with NCS. Cellular uptake of NCS was dose-dependent (1.0 to 1000 micrograms/ml) in 9L rat gliosarcoma cells in monolayer. In monolayer cells of 9L, KMG-4 (derived from human glioblastoma), and KMS II (human ependymoma) treated with 1 mg/ml of NCS, drug uptake occurred within a few seconds. Accumulation was much higher in the cytoplasm than in the nucleus and, although nuclear uptake increased slightly over time, there appeared to be no increase in total cellular uptake. Mitotic cells, which were spherical in culture, showed greater intracellular accumulation than other cells. There was no significant difference in uptake among non-mitotic cells. Cells surviving 20 hours of treatment retained accumulation as high as that in killed cells. In KMG-4 monolayers, cytoplasmic and nuclear NCS distribution still differed, whereas 9L monolayers exhibited more even intracellular distribution. In 9L spheroid models treated with 1 mg/ml of NCS, the drug permeated almost all layers within 10 minutes, and at 120 minutes had heavily accumulated in the central necrotic areas. In rats with transplanted brain tumors, NCS selectively accumulated in neoplastic tissues following intra-arterial administration. However, NCS uptake by arterial endothelium was also seen, which suggests the potential for vascular toxicity. The therapeutic value of NCS is discussed in terms of its pharmacokinetic characteristics.

Animals↗

Thermotolerance and radiation sensitizing effects of long duration, mild temperature hyperthermia.

Clinical application of long duration hyperthermia at temperatures < 42 degrees C has traditionally been avoided because of the possibility of chronic thermotolerance development, such as is observed with rodent cells. In support of long duration hyperthermia, both rodent and human cells have been shown to be sensitized to low dose-rate irradiation by simultaneous heating at 40 or 41 degrees C. The relationship between these supposed contradictory responses to hyperthermia were investigated in rat 9L gliosarcoma cells in vitro. Thermotolerance developed during 41 degrees C heating with or without concurrent low dose-rate irradiation. Thermotolerance reached a maximum within 6 h during 41 degrees C heating and remained stable for at least 24 h. When cells were returned to 37 degrees C after heating at 41 degrees C for 6 h, thermotolerance remained stable for at least 12 h. The time course of thermotolerance development correlated with that of induction of 41 degrees C radiation sensitization. Radiation sensitization, on the other hand, was shown to be independent of thermotolerance because the protein synthesis inhibitor cycloheximide prevented thermotolerance induction but had no effect on radiation sensitization. We conclude that thermotolerance development during concurrent clinical application of long duration mild temperature hyperthermia and low dose-rate irradiation should not be a factor in altering treatment outcome.

Animals↗

Analysis and distribution of etoposide in rat brain tumor model: intracarotid versus intracarotid with angiotensin II-induced hypertension.

The brain tissue distribution of etoposide has been investigated in 9L gliosarcoma-bearing rats with or without hypertension induced by angiotensin II (AT II). The rat brain tumor models were divided into the following two groups according to etoposide administration route: intracarotid injection (IC) group and intracarotid injection with hypertension induced by AT II (IHIC) group. Ten mg/kg of etoposide was given, and 30 min and 2, 4, 8, and 24 hr later the rats were sacrificed. The drug concentrations in the serum, tumor, and normal brain tissue were analyzed by high-pressure liquid chromatography. The etoposide concentration in the serum, tumor, and normal brain tissue peaked at 30 min in both groups. The serum concentration was similar between the two groups. The etoposide concentration in the tumor was at least 2.2 times higher in the IHIC group than in the IC group at 30 min and 2 hr. The area under drug concentration curve (AUC) in the tumor in the IHIC group was about 2.2 times higher than that in the IC group. The etoposide concentration in the normal brain on the drug injection side changed only slightly from 0.5 hr to 4 hr and was about 3 times higher in the IHIC group than in the IC group. The etoposide concentration in the contralateral normal brain was very low in both groups at 30 min and disappeared thereafter. Intracarotid injection of anticancer drugs with AT II-induced hypertension further increases the drug concentration and AUC in the tumor compared with intracarotid injection alone and can be useful in treatment of malignant brain tumors.

Angiotensin II↗

Stem cell studies of human malignant brain tumors. Part 2: Proliferation kinetics of brain-tumor cells in vitro in early-passage cultures.

The proliferation kinetics were studied in early-passage cultures of cells from 13 human malignant brain tumors and two specimens of normal brain under conditions similar to those used in clonogenic cell-survival studies. Autoradiography was performed in all but four cases to estimate the fraction of cells actively replicating deoxyribonucleic acid (DNA), the approximate cell cycle time, and the effect of low-dose tritiated thymidine on cell proliferation. The mean tumor cell doubling time (TD) was 53 hours for five glioblastomas, 46 hours for two ependymomas, and 83 hours for two medulloblastomas. A gliosarcoma grew fastest (TD = 22 hours) in culture and a pilocytic astrocytoma grew slowest (TD = 144 hours). The approximate cell cycle time ranged from 1 to 2.5 days for all tumors tested. This suggests that chemotherapeutic agents that predominantly kill proliferating cells should be administered in vitro for at least 2 to 2.5 days to achieve maximum cell kill. The approximate growth fraction ranged from 0.65 to 0.96 for all tumors except for the two medulloblastomas and the pilocytic astrocytoma, which had growth fractions of 0.34 and 0.35, respectively. Most laboratories investigating the chemosensitivity of primary or early-passage human tumor cells require that 40% to 70% of cells be killed to consider a drug active in vitro. The results of this study suggest that the cell-cycle-specific agents cannot achieve a high enough cell kill to be considered active for some tumors that grow slowly in culture. An estimate of the in vitro growth rate is necessary to reliably interpret cell-survival results with such agents. Tritiated thymidine appeared to slow cell proliferation in some of the cultures, presumably as a result of radiation-induced DNA damage caused by tritium that had been incorporated into DNA. The degree to which cell growth ws slowed in individual tumors correlated with the patient's clinical response to radiation therapy and postoperative survival time.

Brain Neoplasms↗

Effect of difluoromethylornithine on the antiglioma therapeutic efficacy of intra-arterial BCNU.

In an attempt to improve glioma management, an animal model was developed to evaluate the therapeutic efficacy of intra-arterial 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Furthermore, the model was used to study the antitumor activity of D,L-alpha-difluoromethylornithine (DFMO), a polyamine-biosynthesis inhibitor, used both as a single agent and in combination with intra-arterial BCNU. An N-methylnitrosourea-induced gliosarcoma (T9) was transplanted stereotaxically into the right caudate nucleus of male Fischer 344 rats. Animals receiving a single low-dose (5 mg/kg) intracarotid injection of BCNU 9 days following tumor implantation had a 57% increase in life span compared with untreated control rats (p less than 0.001). Intracarotid drug delivery was more effective than systemic (intraperitoneal) administration of the same dose of BCNU. When given as a single agent, DFMO demonstrated dose-dependent effectiveness. As part of a combined regimen, DFMO enhanced the antitumor therapeutic activity of both systemic (intraperitoneal) and intra-arterial BCNU. Survival times of animals receiving combined DFMO and intra-arterial BCNU were almost double those of untreated controls, and were significantly better than survival times of animals receiving combined DFMO and intraperitoneal BCNU. These findings suggest methods to optimize current clinical chemotherapy for glioma.

Animals↗

Enhancement of the efficacy of x-irradiation by pentobarbital in a rodent brain-tumor model.

Radiation therapy is an important component of brain tumor treatment, but its efficacy is limited by its toxicity to the surrounding normal tissue. Pentobarbital acts as a cerebral radioprotectant, but the selectivity of its protection for the central nervous system has not been demonstrated. To determine if pentobarbital also protects tumor against ionizing radiation, five groups of Fischer 344 rats were observed after exposure to varying combinations of the presence or absence of implanted tumor, pentobarbital, and radiation treatment. The first three groups underwent cerebral implantations of a suspension of 9L gliosarcoma cells. Group 1 was left untreated and served as tumor-bearing controls. Group 2 received 30 Gy of whole-brain x-irradiation without anesthesia 8 days after tumor implantation. Group 3 received the same radiation treatment 15 minutes after pretreatment with 60 mg/kg of pentobarbital intraperitoneally. Groups 4 and 5 served as radiation controls, receiving 30 Gy of x-irradiation while awake and 30 Gy of x-irradiation after pentobarbital administration, respectively. Survival was calculated from the death of the last tumor-bearing rat. The mean survival time in tumor-bearing control rats was 20.8 +/- 2.6 days (+/- standard deviation). X-irradiation alone significantly enhanced the period of survival in rats implanted with the 9L tumor (29.7 +/- 5.6 days, p less than 0.03). Further significant prolongation of survival was seen with the addition of pentobarbital to the treatment regimen (39.9 +/- 13.5 days, p less than 0.01). Nontumor-bearing rats irradiated while awake (Group 4) survived 30.9 +/- 2.3 days. All of their pentobarbital-anesthetized counterparts in Group 5 survived. If pentobarbital had offered radioprotection to the tumor, then Group 3 would have had a shorter survival period than Group 2. This implies that the enhancement of survival time after irradiation results from selective protection of normal brain in this model.

Animals↗

Effect of pentobarbital on normal brain protection and on the response of 9L rat brain tumor to radiation therapy.

The authors attempted to confirm published reports that pentobarbital protects against radiation-induced damage to normal rat brain, as well as enhances radiotherapeutic efficacy in a rat brain tumor model. They evaluated animal survival in 9L gliosarcoma-burdened rats that received whole-brain radiation therapy (16, 24, 32, or 40 Gy) while under intraperitoneal pentobarbital (60 mg/kg) or intramuscular ketamine (60 mg/kg) sedation. The animals were examined at autopsy to attribute death to either intracranial tumor growth or normal brain toxicity in the absence of discernible tumor. There was no difference between the two anesthesia groups regarding the survival of unirradiated animals. Radiation therapy produced a significant dose-dependent prolongation in animal survival, which was limited by the development of normal tissue toxicity at the higher doses. When compared to ketamine anesthesia, pentobarbital anesthesia appeared to offer some protection (not statistically significant) against early (but not late) toxicity at selected radiation doses. A reduction in the number of deaths from tissue toxicity suggested an increased antitumor effect, but again this was not statistically significant. Only in one case was there even a marginal significant difference (p = 0.045) between overall therapeutic efficacy in rats sedated with pentobarbital versus ketamine. While there may be a radioprotective effect of pentobarbital in rat brains without intracranial tumor, there is no conclusive evidence for either radioprotection or significant improvement of radiotherapeutic efficacy in this 9L rat brain tumor model.

Animals↗

In vivo transfer of the human interleukin-2 gene: negative tumoricidal results in experimental brain tumors.

The authors have recently shown the feasibility of eradicating brain tumors using in vivo retroviral-mediated transduction of tumors with the herpes simplex thymidine kinase (HStk) gene and ganciclovir therapy. However, thymidine kinase-transduced subcutaneous tumors in immunocompromised (athymic) mice were less responsive to this therapy than in immunocompetent animals, suggesting a role of the immune system in the process of tumor eradication. Broad suppression of humoral and cell-mediated immunity is found in patients with malignant gliomas. Interleukin-2 (IL-2) production and IL-2 receptor expression are decreased in gliomas patients. These findings and the proposed association between lymphocytic infiltration of brain tumors and survival suggest that immune response modifiers may be useful in treating glioma patients. To evaluate the role of local cytokine expression by tumor cells, alone or combined with HStk gene transfer and ganciclovir therapy, the authors investigated the efficacy of tumor (9L gliosarcoma) eradication in Fischer rats by in vitro and in vivo tumor transduction with the IL-2 gene alone or with a combined vector carrying both the HStk and IL-2 genes. Tumors injected with HStk vector-producer cells alone, with or without ganciclovir, and rats inoculated in the brain and subcutaneously with 9L cells that had previously been transduced in vitro served as controls. Murine vector-producer cells (3 x 10(6)/50 microliters) were injected into the brain tumors 7 days after tumor inoculation. Ganciclovir (15 mg/kg) was administered intraperitoneally twice daily for 10 days to animals that received HStk with or without IL-2 vector-producer cells, starting 5 days after producer-cell injection. The experiment was repeated with continuous daily treatment of all rats with oral dexamethasone (0.5 mg/kg). Rats were sacrificed 21 days after tumor inoculation, and the brains were removed for histological and immunohistochemical analysis for IL-2. Within each experimental group, tumors were found in a similar proportion in the dexamethasone-treated and untreated rats. Large brain tumors developed in all 10 rats that had been inoculated with 9L cells which had been pretransduced in vitro with the IL-2 gene, whereas only three of eight rats receiving subcutaneous inoculation of similar cells developed palpable tumors. No enhancement of tumor eradication was observed by adding the IL-2 gene in the HStk vector construct compared to the use of the vector with HStk alone. Lymphocytic infiltration was absent in all dexamethasone-treated rats but was observed in all treatment groups not receiving steroids.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Toxicity studies in thymidine kinase-deficient herpes simplex virus therapy for malignant astrocytoma.

Previous studies have shown that genetically engineered thymidine kinase (tk)-defective herpes simplex virus type 1 (HSV-1) can effectively and selectively destroy gliomas in animal models. The consequences of viral infection and tumor regression must be characterized before this therapy can be applied in human trials. To study the potential for long-term toxicity, immunocompetent rats harboring 9L gliosarcomas were injected intratumorally with a tk-defective HSV-1, KOS-SB, at titers that previously have been demonstrated to cause tumor regression. In animals surviving 3 months or longer following viral treatment, there was no evidence of persistent infection or inflammation in peritumoral brain tissue or in remote systemic organs studied with routine histological and immunocytochemical analyses. Polymerase chain reaction using primers specific for HSV-1 detected HSV-1 DNA in peritumoral tissue only in animals sacrificed within 3 months of viral injection. There was no evidence of HSV-1 DNA in systemic tissues at any time after treatment. We conclude that stereotactic intratumoral injection of tk-deficient HSV can be attempted for the treatment of brain tumors without risk of systemic infection or significant toxicity to normal brain or remote proliferating tissues.

Animals↗

Combined cimetidine and temozolomide, compared with temozolomide alone: significant increases in survival in nude mice bearing U373 human glioblastoma multiforme orthotopic xenografts.

OBJECT: Malignant gliomas consist of both heterogeneous proliferating and migrating cell subpopulations, with migrating glioma cells exhibiting less sensitivity to antiproliferative or proapoptotic drugs than proliferative cells. Therefore, the authors combined cimetidine, an antiinflammatory agent already proven to act against migrating epithelial cancer cells, with temozolomide to determine whether the combination induces antitumor activities in experimental orthotopic human gliomas compared with the effects of temozolomide alone. METHODS: Cimetidine added to temozolomide compared with temozolomide alone induced survival benefits in nude mice with U373 human glioblastoma multiforme (GBM) cells orthotopically xenografted in the brain. Computer-assisted phase-contrast microscopy analyses of 9L rat and U373 human GBM cells showed that cimetidine significantly decreased the migration levels of these tumor cells in vitro at concentrations at which tumor growth levels were not modified (as revealed on monotetrazolium colorimetric assay). Computer-assisted microscope analyses of neoglycoconjugate-based glycohistochemical staining profiles of 9L gliosarcomas grown in vivo revealed that cimetidine significantly decreased expression levels of endogenous receptors for fucose and, to a lesser extent, for N-acetyl-lactosamine moieties. Endogenous receptors of this specificity are known to play important roles in adhesion and migration processes of brain tumor cells. CONCLUSIONS: Cimetidine, acting as an antiadhesive and therefore an antimigratory agent for glioma cells, could be added in complement to the cytotoxic temozolomide compound to combat both migrating and proliferating cells in GBM.

Adjuvants, Immunologic↗

Bystander effect in uracil phosphoribosyltransferase/5-fluorouracil-mediated suicide gene therapy is correlated with the level of intercellular communication.

We examined whether a suicide gene/prodrug system using the uracil phosphoribosyltransferase (UPRT) of E. coli origin and 5-fluorouracil (5-FU) could achieve a bystander effect in two rodent tumor cell lines, murine colon carcinoma (Colon 26) and rat gliosarcoma (9L) cells. Cytotoxicity tests of mixed populations consisting of parent and transduced cells showed that the bystander effect was not produced in Colon 26 cells in either the UPRT/5-FU system or the herpes simplex virus-thymidine kinase/ganciclovir system but a strong bystander effect was evidenced by both suicide gene systems in 9L cells. The expression level of connexin 43, a protein that constitutes gap junctions, was high in 9L but low in Colon 26 cells. A gap junction-permeable fluorescein dye could be transferred among 9L cells but hardly at all among Colon 26 cells. Taken together, the efficacy of the bystander effect in the UPRT/5-FU system can be affected by gap junction-mediated intercellular communication.

Animals↗

Textiloma (gossypiboma) mimicking recurrent intracranial tumor.

CONTEXT: Resorbable substances used to achieve hemostasis during neurosurgical procedures comprise 3 principal classes based on chemical composition: (1) gelatin sponge, (2) oxidized cellulose, and (3) microfibrillar collagen. Nonresorbable hemostatic aides include various forms of cotton and rayon-based hemostats (cottonoids and kites). Resorbable and nonresorbable hemostatic agents have been reported to cause symptomatic mass lesions, most commonly following intra-abdominal surgery. Histologic examination typically shows a core of degenerating hemostatic agent surrounded by an inflammatory reaction. Each agent exhibits distinctive morphologic features that often permit specific identification. Hemostat-associated mass lesions have been variously referred to as textilomas, gossypibomas, gauzomas, or muslinomas. OBJECTIVES: The aims of this study were to (1) identify cases of histologically proven cases of textiloma in neurosurgical operations, (2) characterize the specific hemostatic agent associated with textiloma formation, and (3) characterize the preoperative magnetic resonance imaging appearance of textiloma. DESIGN: Cases in which a textiloma constituted the sole finding on repeat surgery for recurrent brain tumor, or was a clinically significant component of a radiologically identified mass lesion together with residual tumor, constituted the study set. RESULTS: Five textilomas were identified and evaluated. The primary neoplasm was different in each case and included pituitary adenoma, tanycytic ependymoma, anaplastic astrocytoma, gliosarcoma, and oligodendroglioma. In all cases, preoperative magnetic resonance imaging suggested recurrent tumor. Textilomas included all categories of resorbable hemostatic agent. Other foreign bodies were present in some cases; the origin of these foreign bodies was traced to fibers shed from nonresorbable hemostatic material placed temporarily during surgery and removed before closure (cottonoids and kites). Inflammatory reactions included giant cells, granulomas, and fibroblastic proliferation. Microfibrillar collagen (Avitene) textilomas were associated with a striking eosinophil infiltration that was not seen with any other hemostatic agent. CONCLUSIONS: Hemostatic agents may produce clinically symptomatic, radiologically apparent mass lesions. When considering a mass lesion arising after intracranial surgery, the differential diagnosis should include textiloma along with recurrent tumor and radiation necrosis.

Adolescent↗

Synthesis and evaluation of [18F]1-amino-3-fluorocyclobutane-1-carboxylic acid to image brain tumors.

UNLABELLED: We have developed a new tumor-avid amino acid, 1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC), labeled with 18F for nuclear medicine imaging. METHODS: [18F]FACBC was prepared with high specific activity (no carrier added [NCA]) and was evaluated for its potential in tumor localization. A comparative study was performed for [18F]FACBC and [18F]2-fluorodeoxyglucose (FDG) in which the uptake of each agent in 9L gliosarcoma (implanted intracerebrally in Fisher 344 rats) was measured. In addition, the first human PET study of [18F]FACBC was performed on a patient with residual glioblastoma multiforme. Quantitative brain images of the patient were obtained by using a Siemens 921 47-slice PET imaging system. RESULTS: In the rat brain, the initial level of radioactivity accumulation after injection of [18F]FACBC was low (0.11 percentage injected dose per gram [%ID/g]) at 5 min and increased slightly to 0.26 %ID/g at 60 min. The tumor uptake exhibited a maximum at 60 min (1.72 %ID/g), resulting in a tumor-to-brain ratio increase of 5.58 at 5 min to 6.61 at 60 min. In the patient, the uptake of [18F]FACBC in the tumor exhibited a maximum concentration of 146 nCi/mL at 35 min after injection. The uptake of radioactivity in the normal brain tissue was low, 21 nCi/mL at 15 min after injection, and gradually increased to 29 nCi/mL at 60 min after injection. The ratio of tumor to normal tissue was 6 at 20 min after injection. The [18F]FACBC PET scan showed intense uptake in the left frontal region of the brain. CONCLUSION: The amino acid FACBC can be radiofluorinated for clinical use. [18F]FACBC is a potential PET tracer for tumor imaging.

Animals↗

[Comparative structural study of the glial blastomas of the central nervous system].

The objective of our work is to compare 2 diagnostics methods and demonstrate the similarities of the different Central Nervous System Glial Tumor Classifications. Immuno-marking techniques for gliofibrilar acid protein (GFAP), and special silver impregnations to compare the results according to the last histogenetic interpretations were used. 95 Gliomas were studied with hematoxiline-eosine and silver techniques, and in 58 randomized selected cases the technique for GFAP was also used. Both methods showed the same results in the diagnosis of Glial Tumors whose cells possess gliofibrils: Glioepitelioma (Ependymoma), Glioblastoma, Astroblastoma, and Astrocytoma. In the Oligodendrioglomas whose cells possess microtubules but not gliofibrils, the silver techniques marked these cells and their prolongations while the technique for GFAP did not. Regarding Gliomas, there are similarities by comparing the Del Río Ortega-Polak classification with those of the WHO and other authors. There are differences only in the "names" of some tumors or in their histogenetic interpretation, which are not substantial and are confined to the "Polar Espongioblastoma" and "Gliosarcoma". Therefore, we think that the recognition of the Del Río Hortega-Polak classification is justified.

Brain Neoplasms↗