Alpha-lipoic acid inhibits peridural fibrosis following laminectomy through the inactivation of TGF-β1, PDGF, PAI-1 and IL-6 expressions

AIM

The objective of this study was to investigate the antifibrotic effect of parenteral administration of alpha-lipoic acid (ALA), which has been reported to reduce fibrosis in the liver, oral mucosa, and peritoneum, in laminectomized rabbits as a potential candidate for the prevention of peridural fibrosis.

MATERIAL AND METHODS

Twelve adult New Zealand white male rabbits were divided into control (n=6) and ALA treatment groups (n=6). Laminectomy of the lumbar spine was performed in all animals, and ALA was administered intramuscularly in six rabbits composing the treatment group. Total RNA obtained from the paraffin-embedded tissues was analyzed for transforming growth factor-β1 (TGF-β1), plateletderived growth factor (PDGF), plasminogen activator inhibitor-1 (PAI-1) and interleukin-6 (IL-6).

RESULTS

mRNA investigations showed that TGF-β1, PDGF, PAI-1 and IL-6 gene expressions, which constitute strong evidence for the development of fibrosis, were significantly lower in the treatment group compared with the results obtained from the control group. According to the histological peridural grading, the ALA-treated group showed significantly less peridural fibrosis than the control group.

CONCLUSION

Intramuscular administration of ALA is a promising treatment for the prevention of peridural fibrosis in the postoperative period.

Association between frontal sinus development and persistent metopic suture

BACKGROUND

Frontal sinuses are 2 irregular cavities, placed between 2 lamina of frontal bone. Expansion continues during childhood and reaches full size after puberty. Persistent metopic suture is one of the factors that are related to abnormal frontal sinus development. In this study, we want to discuss about the coexistence of persistent metopic suture and abnormal frontal sinus development using radiological techniques.

MATERIALS AND METHODS

In this retrospectively planned study, images of 631 patients were examined, 217 (34.4%) of them were men and 414 (65.6%) of them were women. Brain computed tomography and magnetic resonance images were retrieved from the electronic archive for analysis.

RESULTS

In this study, frontal sinus development is categorised as right side atrophy, left side atrophy, bilateral atrophy and bilaterally developed sinuses. The presence of metopic suture was accepted as persistent metopic suture. Frontal sinus atrophy was found in 22.7% and persistent metopic sutures were found in 9.7% of overall.

CONCLUSIONS

In this study, no significant results were detected that were relatedto the frontal sinus agenesis or dismorphism associated with persistent metopicsuture. We conclude that, although publications propounding metopism thatleads to abnormal frontal sinus development are present in the literature, noreasonable explanation has been mentioned in these articles; and we believe thatthese findings are all incidental.

Preoperative and postoperative evaluation of somatosensorial evoked potentials of upper extremities in cervical intervertebral disc herniation

This study aims to determine the dysfunction caused by existing pathological condition in structures involved in the transfer of sensory functions of the neural system in cervical disc herniation, and to establish whether or not the level and degree of this anatomical damage can be anticipated by SEP (Somatosensorial Evoked Potentials). We compared the obtained SEP values for statistical significance using the Friedman Variation Analysis. In parameters with statistical significance, the Wilcoxon Signed Rank test was used to identify when significant improvements occurred. The study found that the statistical data of the latency of the N14 wave originating from the dorsal column nuclei of the medulla spinalis and dorsal column gray matter improved (p < 0.05) in the postoperative period compared with the preoperative values. Using the Wilcoxon Signed Rank test, we studied postoperative months separately in regard to the difference in the latency of the N14 wave, and found the statistically significant improvement to be marked particularly in months 3 and 6 postoperatively (p < 0.05). In conclusion, we suggest that SEP is a useful tool to check the functional condition of the dorsal spinal column. The benefit of the SEP utilization is the ability to determine the severity of the pathological condition preoperatively and follow the patient's functional postoperative improvement.

Alpha-lipoic acid reduces peridural fibrosis after laminectomy of lumbar vertebrae in rabbits

BACKGROUND

Peridural fibrosis is an inevitable healing process causing failed back surgery syndrome after lumbar spinal operations. In this study, alpha-lipoic acid (ALA), reported to reduce fibrosis in liver, oral mucosa, and peritoneum, investigated as a potential candidate for prevention of peridural fibrosis.

METHOD

Twelve adult New Zealand white male rabbits were divided into control (n = 5) and ALA groups (n = 7). Laminectomy of lumbar spine was performed and ALA was applied on the exposed dura mater topically in ALA group.

RESULTS

According to histological peridural grading, the ALA group (median grade 1) showed significantly less peridural fibrosis than the control group (median grade 3, p = 0.005).

CONCLUSIONS

ALA is a promising substance in the prevention of peridural fibrosis, especially in early preoperative and postoperative period.

Video endoscopy-assisted vestibular neurectomy: a new approach to the eighth cranial nerve

Disequilibrium, ranging from lightheadedness to severe vertigo, is frequently of great concern to the patients with a variety of inner ear diseases, and may cause occupational and social disability. Vestibular nerve section may be considered when vestibular symptoms are resistant to medical therapy and associated with serviceable hearing in the involved ear. During the last century, numerous authors described several routes for intracranial section of the eighth nerve, such as lateral suboccipital craniotomy, middle cranial fossa approach, and retrolabyrinthine approach to the vestibular fossa. Control of vertigo by all routes to the vestibular nerve has a success rate of 80% to 90%. The potential for endoscopic approach to intracranial cavities was recognized early in this century but, due to technical limitations, was largely abandoned after a few attempts. Advances in optics, and the introduction of very fine instruments made endoscopy worth reconsideration. Since the early 1980s, rigid endoscopes have been used in otorhinolaryngology for paranasal sinus surgery and the visualization of the facial and vestibulocochlear nerves during acoustic tumor surgery. We performed endoscopic section of the vestibular nerve through a retrolabyrinthine approach in two cadavers and in two patients with the symptoms of disequilibrium. In the literature survey, we could find no reports on vestibular neurectomy performed by endoscopic technique. We describe technical details of the approach, and conclude that the technique is safe and effective.

Induction of glioblastoma multiforme in nonhuman primates after therapeutic doses of fractionated whole-brain radiation therapy

OBJECT

To determine the acute and long-term effects of a therapeutic dose of brain radiation in a primate model, the authors studied the clinical, laboratory, neuroimaging, molecular, and histological outcomes in rhesus monkeys that had received fractionated whole-brain radiation therapy (WBRT).

METHODS

Twelve 3-year-old male primates (Macaca mulatta) underwent fractionated WBRT (350 cGy for 5 days/week for 2 weeks, total dose 3500 cGy). Animals were followed clinically and with laboratory studies and serial magnetic resonance (MR) imaging. They were killed when they developed medical problems or neurological symptoms, lesions appeared on MR imaging, or at study completion. Gross, histological, and molecular analyses were then performed. Nine (82%) of 11 animals that underwent long-term follow up (> 2.5 years) developed neurological symptoms and/or enhancing lesions on MR imaging, which were defined as glioblastoma multiforme (GBM), 2.9 to 8.3 years after radiation therapy. The GBMs were categorized as either unifocal (three) or multifocal (six), and were located in the supratentorial (six), infratentorial (two), or both (one) cranial regions. Histological examination revealed distant, noncontiguous tumor invasion within the white matter of all nine animals harboring GBMs. Novel interspecies comparative genomic hybridization (three animals) uniformly showed deletions in the GBMs that corresponded to chromosome 9 in humans.

CONCLUSIONS

The high rate of GBM formation (82%) following a therapeutic dose of WBRT in nonhuman primates indicates that radioinduction of these neoplasms as a late complication of this therapy may occur more frequently than is currently recognized in human patients. The development of these tumors while monitoring the monkeys' conditions with clinical and serial MR imaging studies, and access to the tumor and the entire brain for histological and molecular analyses offers an opportunity to gather unique insights into the nature and development of GBMs.

Site-specific immune response to implanted gliomas

OBJECT

Immunotherapy for glioblastoma has been uniformly ineffective. The immunological environment of the brain, with its low expression of major histocompatibility complex (MHC) molecules and limited access for inflammatory cells and humoral immune effectors due to the blood-brain barrier (BBB), may contribute to the failure of immunotherapy. The authors hypothesize that brain tumors are protected from immune surveillance by an intact BBB at early stages of development. To investigate the immunological characteristics of early tumor growth, the authors compared the host response to a glioma implanted into the brain and into subcutaneous tissue.

METHODS

Samples of tumors growing in the brain or subcutaneously in rats were obtained for 7 consecutive days and were examined immunohistochemically for MHC Class I & II molecules, and for CD4 and CD8 lymphocyte markers. Additionally, B7-1 costimulatory molecule expression and lymphocyte-specific apoptosis were examined.

CONCLUSIONS

On Days 3 and 4 after implantation, brain tumors displayed significantly lower MHC Class II expression and lymphocytic infiltration (p < 0.05). After Day 5, however, no differences were detected. The MHC Class II expressing cells within the brain tumors appeared to be infiltrating microglia. Minimal B7-1 expression combined with lymphocyte-specific apoptosis were detected in both brain and subcutaneous tumors. Low MHC Class II expression and low lymphocytic infiltration at early time points indicate the importance of the immunologically privileged status of the brain during early tumor growth. These characteristics disappeared at later time points, possibly because the increasing perturbation of the BBB alters the specific immunological environment of the brain. The lack of B7-1 expression combined with lymphocyte apoptosis indicates clonal anergy of glioma-infiltrating lymphocytes regardless of implantation site.

Reconstituted basement membrane (matrigel) enhances the growth of human glioma cell lines in nude mice

Transplantation of human cancers into immunologically deficient mice is widely used to study potential therapeutic interventions in vivo. For brain tumor research, however, several factors limit more widespread application of this animal model. First, only a minority of human glioma-derived cell lines are tumorigenic in nude mice. In addition, even for tumorigenic cell lines, tumor take is variable and growth is often slow for tumors derived from cell inoculums. Reconstituted components of tumor basement membrane (matrigel) have been found to improve the growth in nude mice of several types of human tumors originating outside the central nervous system when premixed with the tumor cells before subcutaneous inoculation. We investigated the ability of matrigel to enhance the growth in nude mice of tumors derived from the human glioma cell lines U-251 MG, U-373 MG, SNB-78 and SNB-101. Athymic nude mice (NIH Swiss background, nu/nu genotype) were inoculated subcutaneously with 1.0 x 10(6) tumor cells alone or after premixing with an equal volume of liquid matrigel. U-251 and U-373 cells were tumorigenic, with palpable tumors present by about 2 to 3 weeks. Co-injection of these cell lines with matrigel resulted in higher tumor-take rates, from 6/10 to 8/8 animals for U-251 at 60 days, and from 9/12 to 11/11 animals for U-373 at 60 days. Matrigel also enhanced tumor growth, with tumors at 45 days significantly larger than those formed in the absence of matrigel, for both cell lines (p < 0.01). SNB-78 and SNB-101 cells did not give rise to progressively enlarging solid tumors with or without matrigel. Matrigel enhances the growth of tumorigenic human gliomas in athymic nude mice. This technique provides a model with more consistent tumor take and more rapid growth kinetics for human glioma cell lines that are tumorigenic in nude mice.

Interleukin-1 beta-converting enzyme mediates cisplatin-induced apoptosis in malignant glioma cells

Increasing the susceptibility of tumor cells to apoptotic cell death following chemotherapy is of importance to the outcome of cancer treatment. Although the tumor suppressor gene p53 is required for efficient induction of apoptosis by chemotherapeutic agents, it is not the only apoptosis mediator gene. The molecular mechanisms mediating apoptosis following chemotherapy via p53-dependent or p53-independent pathways remain unclear. We show here that cis-diamminedichloroplatinum (cisplatin) induces the expression of interleukin-1 beta-converting enzyme (ICE), a mammalian homologue of the Caenorhabditis elegans cell death gene ced-3, in murine and human malignant glioma cells during apoptosis regardless of their p53 status. Furthermore, overexpression of the murine ICE gene induces apoptosis in these tumor cells. The apoptosis induced by cisplatin treatment or murine ICE overexpression can be suppressed by the tetrapeptide ICE inhibitor Ac-YVAD-CMK or the apoptosis inhibitors bcl-2 or bcl-2-related bcl-XL gene. These findings suggest that ICE may mediate apoptosis induced by chemotherapy, and its induction could represent a novel approach for the effective treatment of malignant glioma.

Convection-enhanced delivery of macromolecules in the brain

For many compounds (neurotrophic factors, antibodies, growth factors, genetic vectors, enzymes) slow diffusion in the brain severely limits drug distribution and effect after direct drug administration into brain parenchyma. We investigated convection as a means to enhance the distribution of the large and small molecules 111In-labeled transferrin (111In-Tf; M(r), 80,000) and [14C]sucrose (M(r), 359) over centimeter distances by maintaining a pressure gradient during interstitial infusion into white matter to generate bulk flow through the brain interstitium. The volume of distribution (Vd) containing > or = 1% concentration of infusion solution increased linearly with the infusion volume (Vi) for 111In-Tf(Vd/Vi, 6:1) and [14C]sucrose (Vd/Vi, 13:1). Twenty-four hours after infusion, the distribution of 111In-Tf was increased and more homogeneous, and penetration into gray matter had occurred. By using convection to supplement simple diffusion, enhanced distribution of large and small molecules can be obtained in the brain while achieving drug concentrations orders of magnitude greater than systemic levels.

Efficacy of direct intratumoral therapy with targeted protein toxins for solid human gliomas in nude mice

Targeted protein toxins are a new class of reagents with the potential for great tumor selectivity and cytotoxic potency. Two such compounds were studied: 1) Tf-CRM107, a conjugate of human transferrin (Tf) and diphtheria toxin with a point mutation (CRM107); and 2) 454A12-rRA, a conjugate of a monoclonal antibody (454A12) to the human Tf receptor and recombinant ricin A chain (rRA). Both compounds are potent and specific in killing human glioblastoma cell lines in vitro. The authors investigated the activity of these reagents administered intratumorally against solid U251 MG human gliomas in vivo. Nude mice with established U251 MG flank tumors (0.5 to 1.0 cm in diameter) were randomly assigned to be treated with 100-microliters intratumoral injections of Tf-CRM107 (10 micrograms) or 454A12-rRA (10 micrograms), equimolar doses of CRM107 (4.3 micrograms), 454A12 antibody (7.5 micrograms), or rRA (1.5 micrograms), or phosphate-buffered saline (PBS) every 2 days for a total of four doses. Tumor volume and animal weight were assessed by a blinded observer before each treatment and biweekly for 30 days after initiating therapy. With Tf-CRM107 administration, tumor regression of greater than 95% occurred by Day 14 (p < 0.01) and tumors did not recur by Day 30. Treatment with 454A12-rRA caused a 30% decrease in tumor volume by Day 14 (p < 0.01). Treatment with equimolar doses of the unconjugated targeted protein toxin components CRM107, 454A12, or rRA caused significant U251 MG tumor growth inhibition, but the effects were less potent than the antitumor effects of the conjugates. This study also characterized the dose-response effect of Tf-CRM107 on tumor growth and tumor weight on Day 30. Nude mice with established U251 MG flank tumors (0.5 to 1.0 cm in diameter) were treated with 100-microliters intratumoral injections of 10, 1.0, or 0.1 microgram of Tf-CRM107 or PBS every 2 days for a total of four doses. All three doses of Tf-CRM107 significantly inhibited tumor growth by Day 14 (p < 0.01) and at Day 30 (p < 0.05), with a significant dose-response relationship. This study demonstrated in vivo efficacy of the targeted toxins Tf-CRM107 and 454A12-rRA against a human glioma. With intratumoral administration, the effect of Tf-CRM107 was tumor-specific and in some animals curative. Regional therapy with these potent tumor-specific agents using direct intratumoral infusion should limit systemic toxicity and may be efficacious against brain tumors.

Oncogenes: cause or consequence in the development of glial tumors

Recent developments in the field of oncogenes and growth stimulatory factors have provided limited but essential models in neuro-oncology. The observation in gliomas of platelet growth factor (PDGF)-like immunoreactivity fits with the autocrine secretion model, rising the possibility for the growth factor independence of the cancer cells. The discovery of the tumor suppressor genes, for which loss of function mutations are oncogenic as in the RB gene of the retinoblastoma and p53 gene, has introduced a new concept of oncogenesis which could be useful even in the cure of the neoplasms. Several oncogenes are amplified and/or expressed in brain tumors, some associated with polymorphism leading to abnormal protein products. Therefore, corresponding functions, such as production of deficient epidermal growth factor receptor (EGFR) encoded by erb-B, are impaired. Abnormal chromosomal patterns have been recognized in brain tumors and found mainly in chromosomes 7 and 22 on which oncogenes erb-B and sis are located, respectively. Location of proto-oncogenes, which are normally expressed in the brain, indicate that they share common distribution patterns mainly involving the cerebellum, hippocampus and olfactory bulbs. These proto-oncogenes may be regulated by physiological and pathological events. The concept of oncogene involvement in brain tumors must be extended to include the other factors such as G-proteins, growth factor receptors, membrane-associated and cytoplasmic protein kinases, which are all responsible for the control of the cell growth and their response to external signals including chemotherapeutic drigs.

Expression and modulation of major histocompatibility antigens on murine primary brain tumor in vitro

Lysis of tumor cells by activated cytotoxic lymphocytes requires their recognition of antigens associated with major histocompatibility complex molecules. The authors studied the constitutive expression of Class I and Class II major histocompatibility complex antigens on mouse brain-tumor cells and the capacity of different cytokines and cytokine combinations to alter this expression in vitro. Cells from the murine glioma 26 (GL26), glioma 261 (GL261), and ependymoblastoma A (EpA) cell lines were established in monolayer culture and treated for 48 hours with either alpha interferon, gamma interferon, tumor necrosis factor alpha, tumor necrosis factor alpha plus gamma interferon, or interleukin-2. They were then analyzed by flow cytometry for baseline and cytokine-altered major histocompatibility complex expression. All cell lines had a similar constitutive major histocompatibility complex pattern with low Class I antigen expression and no detectable Class II antigen expression. Alpha interferon substantially induced and up-regulated Class I antigen expression, but had no effect on Class II antigen expression. Gamma interferon also stimulated up-regulation of Class I antigen expression, generally doubling the anti-Class I antigen fluorescence of treated cells. Its effect on Class II antigen expression was more extensive. In the GL26 and GL261 cell lines the expression of Class II antigen determinants increased to 12 x and 14 x control values and as many as 75% of cells that had no detectable constitutive expression of Class II antigen expressed this antigen after priming with gamma interferon. The addition of tumor necrosis factor alpha to gamma interferon further increased Class II antigen expression on EpA tumor cells only. Interleukin-2 and tumor necrosis factor alpha alone had no effect on Class I or Class II antigen expression of any cell lines. It is concluded that Class I and Class II antigen expression in mouse glioma cell lines is induced and enhanced after treatment with certain cytokines in vitro. Use of these cell lines to create in situ primary brain tumors in C57BL/6 mice should provide an excellent animal system to study major histocompatibility complex modulation in brain tumor cells and to examine the potential impact of major histocompatibility complex up-regulation on the response of brain tumors to immunotherapy.