GQIcombi application to subdue glioma via differentiation therapy.

Current therapy protocols fail to cure high-grade gliomas and prevent recurrence. Therefore, novel approaches need to be developed. A re-programing of glioma cell fate is an alternative attractive way to stop tumor growth. The two-step protocol applies the antiproliferative GQ bi-(AID-1-T) and small molecule inducers with BDNF to trigger neural differentiation into terminally differentiated cells, and it is very effective on GB cell cultures. This original approach is a successful example of the "differentiation therapy". To demonstrate a versatility of this approach, in this publication we have extended a palette of cell cultures to gliomas of II, III and IV Grades, and proved an applicability of that version of differential therapy for a variety of tumor cells. We have justified a sequential mode of adding of GQIcombi components to the glioma cells. We have shown a significant retardation of tumor growth after a direct injection of GQIcombi into the tumor in rat brain, model 101/8. Thus, the proposed strategy of influencing on cancer cell growth is applicable to be further translated for therapy use.

Experimental Reconstruction of the Optic Nerve with a Sural Nerve Graft: An in Vivo Experimental Study.

BACKGROUND: Neurosurgical interventions and trauma are common causes of damage to the optic nerve. This determines the relevance of research for solutions aimed at restoration of the nerve's anatomical integrity, electrical conductivity, and subsequently - restoration of its function. Restore a damaged (cut) optic nerve using n. suralis autograft in vivo. METHODS: The experiment involved reconstruction of the optic nerve through injury modulation, graft placement and restored nerve harvest and evaluation. Injury modulation included removal of a fragment of the optic nerve. Autograft harvesting and placement involved resection of a fragment of the sural (sensory) nerve and its subsequent anastomosis in place of the removed fragment of the optic nerve. As an experimental model, a rabbit of the "Burgundy" breed was used. The animal was previously examined for the presence of infectious and other diseases to confirm its health. RESULTS: Four months post operatively when stimulating the operated right eye, low-amplitude components altered in shape are registered. Thus, signs of mild restoration of electrical conductivity on the treated optic nerve were seen. CONCLUSIONS: Our initial experience shows the technical feasibility of reconstructing the optic nerve using an autograft, the possibility of axonal growth through the graft and, in the future, using this method for direct optic nerve reconstruction, as well as a bypass method for damage to the optic nerve with various tumor diseases of the optic nerve, tumors of the chiasmatic-sellar localization, orbital injuries.

The Bi-(AID-1-T) G-Quadruplex Has a Janus Effect on Primary and Recurrent Gliomas: Anti-Proliferation and Pro-Migration.

High-grade gliomas are considered an incurable disease. Despite all the various therapy options available, patient survival remains low, and the tumor usually returns. Tumor resistance to conventional therapy and stimulation of the migratory activity of surviving cells are the main factors that lead to recurrent tumors. When developing new treatment approaches, the effect is most often evaluated on standard and phenotypically depleted cancer cell lines. Moreover, there is much focus on the anti-proliferative effect of such therapies without considering the possible stimulation of migratory activity. In this paper, we studied how glioma cell migration changes after exposure to bi-(AID-1-T), an anti-proliferative aptamer. We investigated the effect of this aptamer on eight human glioma cell cultures (Grades III and IV) that were derived from patients' tumor tissue; the difference between primary and recurrent tumors was taken into account. Despite its strong anti-proliferative activity, bi-(AID-1-T) was shown to induce migration of recurrent tumor cells. This result shows the importance of studying the effect of therapeutic molecules on the invasive properties of glioma tumor cells in order to reduce the likelihood of inducing tumor recurrence.

Optical Differentiation of Brain Tumors Based on Raman Spectroscopy and Cluster Analysis Methods.

In the present study, various combinations of dimensionality reduction methods with data clustering methods for the analysis of biopsy samples of intracranial tumors were investigated. Fresh biopsies of intracranial tumors were studied in the Laboratory of Neurosurgical Anatomy and Preservation of Biological Materials of N.N. Burdenko Neurosurgery Medical Center no later than 4 h after surgery. The spectra of Protoporphyrin IX (Pp IX) fluorescence, diffuse reflectance (DR) and Raman scattering (RS) of biopsy samples were recorded. Diffuse reflectance studies were carried out using a white light source in the visible region. Raman scattering spectra were obtained using a 785 nm laser. Patients diagnosed with meningioma, glioblastoma, oligodendroglioma, and astrocytoma were studied. We used the cluster analysis method to detect natural clusters in the data sample presented in the feature space formed based on the spectrum analysis. For data analysis, four clustering algorithms with eight dimensionality reduction algorithms were considered.

Differentiation of glioblastoma tissues using spontaneous Raman scattering with dimensionality reduction and data classification.

The neurosurgery of intracranial tumors is often complicated by the difficulty of distinguishing tumor center, infiltration area, and normal tissue. The current standard for intraoperative navigation is fluorescent diagnostics with a fluorescent agent. This approach can be further enhanced by measuring the Raman spectrum of the tissue, which would provide additional information on its composition even in the absence of fluorescence. However, for the Raman spectra to be immediately helpful for a neurosurgeon, they must be additionally processed. In this work, we analyzed the Raman spectra of human brain glioblastoma multiforme tissue samples obtained during the surgery and investigated several approaches to dimensionality reduction and data classificatin to distinguish different types of tissues. In our study two approaches to Raman spectra dimensionality reduction were approbated and as a result we formulated new technique combining both of them: feature filtering based on the selection of those shifts which correspond to the biochemical components providing the statistically significant differences between groups of examined tissues (center of glioblastoma multiforme, tissues from infiltration area and normally appeared white matter) and principal component analysis. We applied the support vector machine to classify tissues after dimensionality reduction of registered Raman spectra. The accuracy of the classification of malignant tissues (tumor edge and center) and normal ones using the principal component analysis alone was 83% with sensitivity of 96% and specificity of 44%. With a combined technique of dimensionality reduction we obtained 83% accuracy with 77% sensitivity and 92% specificity of tumor tissues classification.

5-ALA-guided tumor resection during awake speech mapping in gliomas located in eloquent speech areas: Single-center experience.

Background: Achieving maximal functionally safe resection of gliomas located within the eloquent speech areas is challenging, and there is a lack of literature on the combined use of 5-aminolevulinic acid (5-ALA) guidance and awake craniotomy. Objective: The aim of this study was to describe our experience with the simultaneous use of 5-ALA fluorescence and awake speech mapping in patients with left frontal gliomas located within the vicinity of eloquent speech areas. Materials and methods: A prospectively collected database of patients was reviewed. 5-ALA was administered at a dose of 20 mg/kg 2 h prior to operation, and an operating microscope in BLUE400 mode was used to visualize fluorescence. All patients underwent surgery using the "asleep-awake-asleep" protocol with monopolar and bipolar electrical stimulation to identify the proximity of eloquent cortex and white matter tracts and to guide safe limits of resection along with fluorescence guidance. Speech function was assessed by a trained neuropsychologist before, during, and after surgery. Results: In 28 patients operated with cortical mapping and 5-ALA guidance (12 Grade 4, 6 Grade 3, and 10 Grade 2 gliomas), Broca's area was identified in 23 cases and Wernicke's area was identified in 5 cases. Fluorescence was present in 14 cases. Six tumors had residual fluorescence due to the positive speech mapping in the tumor bed. Transient aphasia developed in 14 patients, and permanent aphasia developed in 4 patients. In 6 patients operated with cortical and subcortical speech mapping and 5-ALA guidance (4 Grade 4, 1 Grade 3, and 1 Grade 2 gliomas), cortical speech areas were mapped in 5 patients and subcortical tracts were encountered in all cases. In all cases, resection was stopped despite the presence of residual fluorescence due to speech mapping findings. Transient aphasia developed in 6 patients and permanent aphasia developed in 4 patients. In patients with Grade 2-3 gliomas, targeted biopsy of focal fluorescence areas led to upgrading the grade and thus more accurate diagnosis. Conclusion: 5-ALA guidance during awake speech mapping is useful in augmenting the extent of resection for infiltrative high-grade gliomas and identifying foci of anaplasia in non-enhancing gliomas, while maintaining safe limits of functional resection based on speech mapping. Positive 5-ALA fluorescence in diffuse Grade 2 gliomas may be predictive of a more aggressive disease course.

Reparative properties of human glioblastoma cells after single exposure to a wide range of X-ray doses.

Radiation therapy induces double-stranded DNA breaks in tumor cells, which leads to their death. A fraction of glioblastoma cells repair such breaks and reinitiate tumor growth. It was necessary to identify the relationship between high radiation doses and the proliferative activity of glioblastoma cells, and to evaluate the contribution of DNA repair pathways, homologous recombination (HR), and nonhomologous end joining (NHEJ) to tumor-cell recovery. We demonstrated that the GO1 culture derived from glioblastoma cells from Patient G, who had previously been irradiated, proved to be less sensitive to radiation than the Sus\fP2 glioblastoma culture was from Patient S, who had not been exposed to radiation before. GO1 cell proliferation decreased with radiation dose, and MTT decreased to 35% after a single exposure to 125 Gγ. The proliferative potential of glioblastoma culture Sus\fP2 decreased to 35% after exposure to 5 Gγ. At low radiation doses, cell proliferation and the expression of RAD51 were decreased; at high doses, cell proliferation was correlated with Ku70 protein expression. Therefore, HR and NHEJ are involved in DNA break repair after exposure to different radiation doses. Low doses induce HR, while higher doses induce the faster but less accurate NHEJ pathway of double-stranded DNA break repair.

A Combined Effect of G-Quadruplex and Neuro-Inducers as an Alternative Approach to Human Glioblastoma Therapy.

Cancer cell reprogramming based on treatment with G-quadruplex, having antiproliferative power, along with small molecules able to develop iPSCs into neurons, could create a novel approach to diminish the chance of glioblastoma recurrence and circumvent tumor resistance to conventional therapy. In this research, we have tested several combinations of factors to affect both total cell cultures, derived from tumor tissue of patients after surgical resection and two subfractions of this cell culture after dividing them into CD133-enriched and CD133-depleted populations (assuming CD133 to be a marker of glioblastoma stem-like cells). CD133+ and CD133- cells exhibit different responses to the same combinations of factors; CD133+ cells have stem-like properties and are more resistant. Therefore, the ability to affect CD133+ cells provides a possibility to circumvent resistance to conventional therapy and to build a promising strategy for translation to improve the treatment of patients with glioblastoma.

PROGNOSTIC SIGNIFICANCE OF METABOLISM INDICATORS OF CONNECTIVE TISSUE IN PATIENTS WITH UPPER URINARY TRACT OBSTRUCTION.

OBJECTIVE: The aim: The aim of the study was a comparative analysis of indicators characterizing the state of connective tissue in patients with hydronephrosis due to upper urinary tract obstruction, with the presence and absence of recurrence after surgery. PATIENTS AND METHODS: Materials and methods: Levels of free and bound hydroxyproline, as well as the key mediator of fibrogenesis transforming growth factor-ß1 in serum of patients with congenital and acquired obstructions were determined. Ratio peptide-bound and free hydroxyproline were calculated. Groups were divided according to the presence or absence of recurrence of the stricture for a period of 4.5 years after surgery. RESULTS: Results: Imbalance of the destructive and synthetic processes in extracellular matrix of connective tissue that is characterized by a higher content of fractions of hydroxyproline and transforming growth factor-ß1 in the serum were identified. It is shown that the most pronounced changes are observed in patients with relapsing. In patients with a congenital obstruction and a recurrent course of the disease, the highest activation of the collagen metabolism was observed, which was evidenced by the high levels peptide-bound and protein-bound hydroxyproline, relative to these indicators in patients with acquired obstruction (as with the presence and absence of relapses). CONCLUSION: Conclusions: The increase in the ratio of peptide-bound/free hydroxyproline and the level of transforming growth factor-ß1 in the blood of patients with stage II-III hydronephrosis on the 21st day after surgery may be a prognostic marker for the development of disease recurrence.

Radiochemical Synthesis of 4-[18F]FluorobenzylAzide and Its Conjugation with EGFR-Specific Aptamers.

Central nervous system tumors related to gliomas are of neuroectodermal origin and cover about 30% of all primary brain tumors. Glioma is not susceptible to any therapy and surgical attack remains one of the main approaches to its treatment. Preoperative tumor imaging methods, such as positron emission tomography (PET), are currently used to distinguish malignant tissue to increase the accuracy of glioma removal. However, PET is lacking a specific visualization of cells possessing certain molecular markers. Here, we report an application of aptamers to enhancing specificity in imaging tumor cells bearing the epidermal growth factor receptor (EGFR). Glioblastoma is characterized by increased EGFR expression, as well as mutations of this receptor associated with active division, migration, and adhesion of tumor cells. Since 2021, EGFR has been included into the WHO classification of gliomas as a molecular genetic marker. To obtain conjugates of aptamers GR20 and GOL1-specific to EGFR, a 4-[18F]fluorobenzylazide radiotracer was used as a synthon. For the production of the synthon, a method of automatic synthesis on an Eckert & Ziegler research module was adapted and modified using spirocyclic iodonium ylide as a precursor. Conjugation of 4-[18F]fluorobenzylazide and alkyne-modified aptamers was carried out using Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) with/without the TBTA ligand. As a result, it was possible to obtain 18F-labelled conjugates with 97% radiochemical purity for [18F]FB-GR20 and 98% for [18F]FB-GOL1. The obtained conjugates can be used for further studies in PET analysis on model animals with grafted glioblastoma.

Neuroinductive properties of mGDNF depend on the producer, E. Coli or human cells.

The glial cell line-derived neurotrophic factor (GDNF) is involved in the survival of dopaminergic neurons. Besides, GDNF can also induce axonal growth and creation of new functional synapses. GDNF potential is promising for translation to treat diseases associated with neuronal death: neurodegenerative disorders, ischemic stroke, and cerebral or spinal cord damages. Unproductive clinical trials of GDNF for Parkinson's disease treatment have induced to study this failure. A reason could be due to irrelevant producer cells that cannot perform the required post-translational modifications. The biological activity of recombinant mGDNF produced by E. coli have been compared with mGDNF produced by human cells HEK293. mGDNF variants were tested with PC12 cells, rat embryonic spinal ganglion cells, and SH-SY5Y human neuroblastoma cells in vitro as well as with a mouse model of the Parkinson's disease in vivo. Both in vitro and in vivo the best neuro-inductive ability belongs to mGDNF produced by HEK293 cells. Keywords: GDNF, neural differentiation, bacterial and mammalian expression systems, cell cultures, model of Parkinson's disease.

RNA Aptamers for Theranostics of Glioblastoma of Human Brain.

Conventional approaches for studying and molecular typing of tumors include PCR, blotting, omics, immunocytochemistry, and immunohistochemistry. The last two methods are the most used, as they enable detecting both tumor protein markers and their localizations within the cells. In this study, we have investigated a possibility of using RNA aptamers, in particular, 2'-F-pyrimidyl-RNA aptamer ME07 (48 nucleotides long), specific to the receptor of epidermal growth factor (EGFR, ErbB1, Her1), as an alternative to monoclonal antibodies for aptacytochemistry and aptahistochemistry for human glioblastoma multiforme (GBM). A specificity of binding of FAM-ME07 to the receptor on the tumor cells has been demonstrated by flow cytometry; an apparent dissociation constant for the complex of aptamer - EGFR on the cell has been determined; a number of EGFR molecules has been semi-quantitatively estimated for the tumor cell lines having different amount of EGFR: A431 (106 copies per cell), U87 (104 copies per cell), MCF7 (103 copies per cell), and ROZH, primary GBM cell culture derived from patient (104 copies per cell). According to fluorescence microscopy, FAM-ME07 interacts directly with the receptors on A431 cells, followed by its internalization into the cytoplasm and translocation to the nucleolus; this finding opens a possibility of ME07 application as an escort aptamer for a delivery of therapeutic agents into tumor cells. FAM-ME07 efficiently stains sections of GBM clinical specimens, which enables an identification of EGFR-positive clones within a heterogeneous tumor; and providing a potential for further studying animal models of GBM.

Covalent Bi-Modular Parallel and Antiparallel G-Quadruplex DNA Nanocostructs Reduce Viability of Patient Glioma Primary Cell Cultures.

G-quadruplex oligonucleotides (GQs) exhibit specific anti-proliferative activity in human cancer cell lines, and they can selectively inhibit the viability/proliferation of cancer cell lines vs. non-cancer ones. This ability could be translated into a cancer treatment, in particular for glioblastoma multiform (GBM), which currently has a poor prognosis and low-efficiency therapeutic treatments. A novel bi-modular GQ, bi-(AID-1-T), a twin of the previously described three-quartet AID-1-T, was designed and studied in terms of both its structure and function. A covalent conjugation of two AID-1-Ts via three thymidine link, TTT, did not interfere with its initial GQ structure. A comparison of bi-(AID-1-T) with its mono-modular AID-1-T, mono-modular two-quartet HD1, and bi-modular bi-HD1, as well as conventional two-quartet AS1411, was made. Among the five GQs studied, bi-(AID-1-T) had the highest anti-proliferative activity for the neural cancer cell line U87, while not affecting the control cell line, human embryonic fibroblasts. GQs, for the first time, were tested on several primary glioma cultures from patient surgical samples. It turned out that the sensitivity of the patient primary glioma cultures toward GQs varied, with an apparent IC50 of less than 1 µM for bi-(AID-1-T) toward the most sensitive G11 cell culture (glioma, Grade III).

Mapping and Quantification of Non-Coding RNA Originating from the rDNA in Human Glioma Cells.

Ribosomal DNA is one of the most conserved parts of the genome, especially in its rRNA coding regions, but some puzzling pieces of its noncoding repetitive sequences harbor secrets of cell growth and development machinery. Disruptions in the neat mechanisms of rDNA orchestrating the cell functioning result in malignant conversion. In cancer cells, the organization of rRNA coding genes and their transcription somehow differ from that of normal cells, but little is known about the particular mechanism for this switch. In this study, we demonstrate that the region ~2 kb upstream of the rDNA promoter is transcriptionally active in one type of the most malignant human brain tumors, and we compare its expression rate to that of healthy human tissues and cell cultures. Sense and antisense non-coding RNA transcripts were detected and mapped, but their secondary structure and functions remain to be elucidated. We propose that the transcripts may relate to a new class of so-called promoter-associated RNAs (pRNAs), or have some other regulatory functions. We also hope that the expression of these non-coding RNAs can be used as a marker in glioma diagnostics and prognosis.

Bone remodeling features in elderly and senile patients with the proximal femur fractures after hip replacement.

OBJECTIVE: The aim of this study is to identify the dependence of the result of surgical treatment of patients of elderly and senile age with fractures of the proximal femur on the characteristics of the response cytokine-mediated regulatory response to trauma and surgery. PATIENTS AND METHODS: Materials and methods: In 74 patients after hip arthroplasty, serum levels of bone metabolism markers were determined using enzyme-linked immunosorbent assay. Patients were divided into 2 groups depending on the results of treatment. RESULTS: Results: It was found that compared with group 2 (treatment outcome is worse) in group 1 (treatment outcome is better) there was a greater number of correlations. In group 1, correlations were found between OPG and RANKL (r = 0.88; p = 0.000), OPG and OPG/RANKL (r = 0.44; p = 0.006), TGF-ß1 and OPG/RANKL (r = 0.66; p = 0.000) , IL-6 and OPG (r = 0.67; p = 0.000), IL-6 and RANKL (r = 0.53; p = 0.001), IL-6 and OPG/RANKL (r = 0.39; p = 0.016). In group 2, only between OPG and OPG/RANKL (r = 0.72; p = 0.000), RANKL and OPG/RANKL (r = -0.53; p = 0.0007). In patients of group 2, there was a decrease in the level of OPG relative to the control and a less significant increase in TGF-ß1 and IL-6 relative to group 1. CONCLUSION: Conclusion: The prognosis of the results of treatment of patients with proximal femur fractures is largely determined by the nature of the adaptive response to injury and theimplant, the synchronism of the mechanism of stress remodeling of the bone. A less favorable prognosis after arthroplasty is associated with exacerbation of the initial metabolic disorders in the bone tissue due to severe cytokine-mediated dysfunction of the regulatory pathways.

Pyrene-Modified DNA Aptamers with High Affinity to Wild-Type EGFR and EGFRvIII.

Nucleic acid aptamers have been proven to be a useful tool in many applications. Particularly, aptamers to epidermal growth factor receptor (EGFR) have been successfully used for the recognition of EGFR-expressing cells, the inhibition of EGFR-dependent pathways, and targeted drug delivery into EGFR-positive cells. Several aptamers are able to discriminate wild-type EGFR from its mutant form, EGFRvIII. Aptamers to EGFR have hairpin-like secondary structures with several possible folding variations. Here, an aptamer, previously selected to EGFRvIII, was chosen as a lead compound for extensive post-SELEX maturation. The aptamer was 1.5-fold truncated, the ends of the hairpin stem were appended with GC-pairs to increase thermal stability, and single pyrene modification was introduced into the aptamer to increase affinity to the target protein. Pyrene modification was selected from extensive computer docking studies of a library of thousands of chemicals to EGFR near the EGF-binding interface. The resulting aptamers bound extracellular domains of both variants of EGFR: EGFRwt and EGFRvIII with subnanomolar apparent dissociation constants. Compared with the initial aptamer, affinity to EGFRwt was increased up to 7.5-fold, whereas affinity to EGFRvIII was increased up to 4-fold.

Study of possibility of cell recognition in brain tumors.

The brain has an exceptionally high requirement for energy metabolism, with glucose serving as the exclusive energy source. Cancers, including glioblastoma, have a high glucose uptake and rely on aerobic glycolysis for energy metabolism. The alternation of high-efficiency oxidative phosphorylation to a low-efficiency aerobic glycolysis pathway (Warburg effect) provides macromolecules for biosynthesis and proliferation. Current research indicates that the specific metabolism in the tumor tissue and normal brain tissue in the glioma allows the use of 5-aminolevulinic acid (5 ALA)-induced protoporphyrin IX (PpIX) and methylene blue (MB) to monitor and correct the development of the tumor. The focus is on the detection of the differences between tumor cells and tumor-associated macrophages/microglia using spectroscopic and microscopic methods, based on the fluorescent signals and the difference in the drug accumulation of photosensitizers (PSs). Since 5 ALA has long been used effectively in the clinic for fluorescent surgical navigation, it was employed as an agent to identify the localization of tumor tissue and study its composition, particularly tumor and immune cells (macrophages), which have also been shown to actively accumulate PpIX. However, since PpIX is photodynamically active, it can be considered effective as the main target of tumor tissue for further successful photodynamic therapy. MB was employed to visualize resident microglia, which is important for their activation/deactivation to prevent the reprogramming of the immune cells by the tumor. Thus, using two drugs, it is possible to prevent crosstalk between tumor cells and the immune cells of different geneses.

Bimodular Antiparallel G-Quadruplex Nanoconstruct with Antiproliferative Activity.

Oligonucleotides with an antiproliferative activity for human cancer cells have attracted attention over the past decades; many of them have a G-quadruplex structure (GQ), and a cryptic target. In particular, DNA oligonucleotide HD1, a minimal GQ, could inhibit proliferation of some cancer cell lines. The HD1 is a 15-nucleotide DNA oligonucleotide that folds into a minimal chair-like monomolecular antiparallel GQ structure. In this study, for eight human cancer cell lines, we have analyzed the antiproliferative activities of minimal bimodular DNA oligonucleotide, biHD1, which has two HD1 modules covalently linked via single T-nucleotide residue. Oligonucleotide biHD1 exhibits a dose-dependent antiproliferative activity for lung cancer cell line RL-67 and cell line of central nervous system cancer U87 by MTT-test and Ki-67 immunoassay. The study of derivatives of biHD1 for the RL-67 and U87 cell lines revealed a structure-activity correlation of GQ folding and antiproliferative activity. Therefore, a covalent joining of two putative GQ modules within biHD1 molecule provides the antiproliferative activity of initial HD1, opening a possibility to design further GQ multimodular nanoconstructs with antiproliferative activity-either as themselves or as carriers.

Fluorescence Diagnosis in Neurooncology: Retrospective Analysis of 653 Cases.

Objective: This study is to analyze fluorescence sensitivity in the diagnosis of brain and spinal cord tumors. Material and methods: The authors conducted a multicenter retrospective analysis of data on 653 cases in 641 patients: 553 of them had brain tumors and 88 spinal cord tumors. Brain tumor resection was performed in 523 patients, of whom 484 were adults and 39 children. The analyzed series was presented by 320 gliomas, 101 meningiomas, and 72 metastases. A stereotactic biopsy was performed in 20 patients and endoscopic surgery in 10 patients. In all cases, 20 mg/kg of 5-Aminolaevulinic acid was administered orally 2-h before surgery. All surgical interventions were performed with a microscope BLUE 400 to visualize fluorescence, while endoscopic surgery-with an endoscope equipped with a fluorescent module. Fluorescence spectroscopy was conducted in 20 cases of stereotactic biopsies and in 88 cases of spinal cord tumors. Results: Among adult brain tumors operated by microsurgical techniques, meningiomas showed the highest 5-ALA fluorescence sensitivity 94% (n = 95/101), brain metastases 84.7% (n = 61/72), low-grade gliomas 46.4% (n = 26/56), and high-grade gliomas 90.2% (n = 238/264). In children the highest 5-ALA visible fluorescence was observed in anaplastic astrocytomas 100% (n = 4/4) and in anaplastic ependymomas 100% (n = 4/4); in low-grade gliomas it made up 31.8% (n = 7/22). As for the spinal cord tumors in adults, the highest sensitivity was demonstrated by glioblastomas 100% (n = 4/4) and by meningiomas 100% (n = 4/4); Fluorescence was not found in gemangioblastomas (n = 0/6) and neurinomas (n = 0/4). Fluorescence intensity reached 60% (n = 6/10) in endoscopic surgery and 90% (n = 18/20) in stereotactic biopsy. Conclusion: 5-ALA fluorescence diagnosis proved to be most sensitive in surgery of HGG and meningioma (90.2 and 94.1%, respectively). Sensitivity in surgery of intracranial metastases and spinal cord tumors was slightly lower (84.7 and 63.6%, correspondingly). The lowest fluorescence sensitivity was marked in pediatric tumors and LGG (50 and 46.4%, correspondingly). Fluorescence diagnosis can also be used in transnasal endoscopic surgery of skull base tumors and in stereotactic biopsy.

The Role of 5-ALA in Low-Grade Gliomas and the Influence of Antiepileptic Drugs on Intraoperative Fluorescence.

Objectives: Intraoperative tumor visualization with 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence is widely applied for improved resection of high-grade gliomas. However, visible fluorescence is present only in a minority of low-grade gliomas (LGGs) according to current literature. Nowadays, antiepileptic drugs (AEDs) are frequently administered to LGG patients prior to surgery. A recent in-vitro study demonstrated that AEDs result in significant reduction of PpIX synthesis in glioma cells. The aim of this study was thus to investigate the role of 5-ALA fluorescence in LGG surgery and the influence of AEDs on visible fluorescence. Patients and Methods: Patients with resection of a newly diagnosed suspected LGG after 5-ALA (25 mg/kg) administration were initially included. During surgery, the presence of visible fluorescence (none, mild, moderate, or bright) within the tumor and intratumoral fluorescence homogeneity (diffuse or focal) were analyzed. Tissue samples from fluorescing and/or non-fluorescing areas within the tumor and/or the assumed tumor border were collected for histopathological analysis (WHO tumor diagnosis, cell density, and proliferation rate). Only patients with diagnosis of LGG after surgery remained in the final study cohort. In each patient, the potential preoperative intake of AEDs was investigated. Results: Altogether, 27 patients with a histopathologically confirmed LGG (14 diffuse astrocytomas, 6 oligodendrogliomas, 4 pilocytic astrocytomas, 2 gemistocytic astrocytomas, and one desmoplastic infantile ganglioglioma) were finally included. Visible fluorescence was detected in 14 (52%) of 27. In terms of fluorescence homogeneity (n = 14), 7 tumors showed diffuse fluorescence, while in 7 gliomas focal fluorescence was noted. Cell density (p = 0.03) and proliferation rate (p = 0.04) was significantly higher in fluorescence-positive than in fluorescence-negative samples. Furthermore, 15 (56%) of 27 patients were taking AEDs before surgery. Of these, 11 patients (73%) showed no visible fluorescence. In contrast, 10 (83%) of 12 patients without prior AEDs intake showed visible fluorescence. Thus, visible fluorescence was significantly more common in patients without AEDs compared to patients with preoperative AED intake (OR = 0,15 (CI 95% 0.012-1.07), p = 0.046). Conclusions: Our study shows a markedly higher rate of visible fluorescence in a series of LGGs compared to current literature. According to our preliminary data, preoperative intake of AEDs seems to reduce the presence of visible fluorescence in such tumors and should thus be taken into account in the clinical setting.