O2: TOWARDS A LIVING BIOBANK OF SURGICALLY-RELEVANT 3-DIMENSIONAL GLIOBLASTOMA STEM CELL MODELS TO EVALUATE NOVEL THERAPEUTICS AND INTERROGATE INTRATUMOURAL HETEROGENEITY

Introduction

Glioblastoma is the most common cancer arising within the brain. Despite surgery, followed by DNA-damaging chemoradiotherapy, average survival remains between 12-15 months. Unacceptable survival rates underline the need to develop preclinical research models which recapitulate features underpinning therapeutic resistance in patients, such as intratumoural heterogeneity and treatment resistant glioblastoma stem cell (GSC) subpopulations which demonstrate elevated DNA damage response (DDR) activity.

Method

Tumour specimens from patients were used to generate 2D and 3D scaffold-based GSC models, with a range of preclinical survival and molecular assays used to interrogate cancer biology and assess therapeutic responses.

Result

We have developed a ‘living biobank’ of 20+ ex-vivo GSC models which reflect key clinicopathological diversity. These models include residual disease models based on careful macrodissection of rare en-blocpartial lobectomy specimens to liberate parallel GSC lines from the tumour core and adjacent infiltrated brain, to represent cells typically left behind after surgery. Therapeutic strategies targeting fundamental DDR processes demonstrate preclinical efficacy, for example dual inhibition of ATR and the FA DNA damage repair pathways elicits profound radiosensitisation (sensitiser enhancement ratio of 3.23 (3.03-3.49, 95%-CI)) with evidence of delayed DNA damage repair on single-cell gel electrophoresis. Finally, characterisation of our surgically-relevant resected and residual models reveals numerous divergent properties including elevated stem cell marker expression in residual models (p=0.0021), which may partially explain treatment resistance in disease left behind after surgery.

Conclusion

Our living biobank represents a useful resource for preclinical glioblastoma research and demonstrates the value of partnership between surgeons and laboratory-based scientists.

Take-home message

Our living biobank represents a useful resource for preclinical glioblastoma research and demonstrates the value of partnership between surgeons and laboratory-based scientists.

Comparative Evaluation of Preemptive Analgesia of Dextromethorphan and Ibuprofen in Third Molar Surgeries

Introduction:

Postoperative pain following third molar removal is one of the most common and unpleasant complications encountered in routine surgical practice. Various methods have been advocated to minimize the postoperative pain: preemptive analgesia is one of those found to be effective.

Objective:

The aim of this study was to compare the preemptive analgesic efficacy of Dextromethorphan (DM) and Ibuprofen in the third molar surgeries.

Material and Methods:

Thirty-six patients reporting to our institution were included in the study. Patients were randomized into three groups of 12 patients each to receive either DM 30 mg, ibuprofen 100 mg, or placebo in the form of multivitamin syrup, 90 min before the procedure. The difficulty of removal of the teeth was assessed using Campbell difficulty score. The study objectives were to evaluate the time elapsed since surgery after which the patient took their first dose of aceclofenac, to evaluate the postoperative pain using visual analog scale score, and to record the number of aceclofenac tablets consumed postoperatively.

Results:

The results of the study revealed that preemptive DM was significantly better than ibuprofen and placebo in the duration of time that elapsed before the patients consumed their first analgesic postoperatively. Preemptive DM also reduced the total number of aceclofenac tablets consumed on the day of surgery and on the 1^st postoperative day, but the difference was not statistically significant. Between the two drugs, DM is better suited for providing preemptive analgesia. No side effects at a dose of 30 mg of DM were noted in any of the patients.

Conclusion:

DM premedication is a viable preemptive analgesic in reducing postoperative pain.

Incidence of distal caries in mandibular second molars due to impacted third molars: Nonintervention strategy of asymptomatic third molars causes harm? A retrospective study

Background:

Removal of impacted third molars is the most common oral surgical procedure. Many investigators have questioned the necessity of removal in patients who are free of symptoms or associated pathologies.

Aim:

The aim of this retrospective study was to evaluate the incidence of caries on distal aspect of mandibular second molars in patients referred for corresponding third molar assessment and to identify its association with angular position and depth of the impacted mandibular third molars based on the classification of Pell and Gregory.

Methodology:

Records of 150 patients with impacted third molar presenting to the Department of Oral and Maxillofacial Surgery, Sri Rajiv Gandhi College of Dental Sciences and Hospital, were assessed retrospectively. The radiographic angulation and depth of mandibular third molar impaction were determined and compared to determine the relationship with incidence of caries on the distal surface of the second molar.

Results:

According to this study results, 37.5% cases show caries on the distal aspect of mandibular second molars. The incidence of caries with mesioangular impacted third molars was 55%. A majority of these mesioangular cases were Level B and Class I as per the Pell and Gregory classification.

Conclusion:

The prophylactic extraction of mandibular third molars is indicated if the angulation is between 30° and 70° and is justified by incidence of distal caries in the second molars.

Multidisciplinary Approach in Management of a Large Cystic Lesion in Anterior Maxilla - A Case Report

Management of large cystic lesion requires a multidisciplinary approach. In this case report a large radicular cyst is managed by conventional root canal treatment with triple antibiotic paste followed by surgical enucleation. In this case, patient presented with a 4 cm symptomatic swelling of the palate adjacent to teeth 21, 22 and 23. The swelling was soft on palpation and the overlying mucosa was of normal color. Radiographically, a well-defined unilocular radiolucency with corticated margins was seen. A full-thickness flap was reflected and revealed a large cyst-like lesion that had perforated the lingual cortical plate. The lesion was enucleated and submitted for microscopic examination. The biopsy report confirmed the diagnosis as radicular cyst.The patient was recalled after 6 months, and no symptoms or signs were noted. Radiograph showed the healing lesion.

Lymphoblastic leukaemia presenting as a carotid-cavernous fistula

A carotid-cavernous fistula is a life-threatening condition characterised by an abnormal communication between the carotid arterial vessels and the cavernous venous system. Although these fistulae can arise spontaneously, they mainly occur after trauma, especially road traffic accidents, falls and penetrating cranial or orbital injuries. The mainstay of treatment involves endovascular embolization, but in those patients where this is not possible or where embolization fails, direct surgical intervention and ligation of the artery may be necessary. Here we describe an interesting case of a suspected carotid-cavernous fistula which turned out to be cavernous sinus syndrome secondary to lymphoma.

A three-dimensional pharmacophore modelling of ITK inhibitors and virtual screening for novel inhibitors

Interleukin-2-inducible T-cell kinase (ITK) is a key member of the Tec family of non-receptor tyrosine kinases, and has been found to be a novel target for a number of inflammatory and autoimmune diseases. A three-dimensional pharmacophore model has been generated for protein ITK from its known inhibitors. The best HypoGen model consisted of four pharmacophore features: one hydrogen bond acceptor, one hydrogen bond donor and two hydrophobic rings. This model showed a correlation coefficient of 0.947, a root mean square deviation of 0.914 and a configuration cost of 16.866. The model was validated using test set prediction and Fischer's test. A test set containing 204 compounds showed an r(2) of 0.745 between estimated activity and activity measured experimentally. Fisher's test gave a confidence level of 95%. The best pharmacophore model (Hypo1) was then employed for virtual screening (3D database searching), including Lipinsiki's filter, to obtain a pool of more drug-like molecules. The molecular pool thus retrieved was subjected to docking analysis with a study protein to remove any molecules showing false positive activity for ITK.

Ascorbic Acid Increases the Number of Dopamine Neurons In Vitro and in Transplants to the 6-OHDA-Lesioned Rat Brain

The inadequate survival of dopamine neurons following intracerebral transplantation is in part attributed to the generation of reactive oxygen species and subsequent oxidative stress. To address this, we investigated whether the antioxidant ascorbic acid (vitamin C) had any effect on the yields of dopamine neurons derived from E14 rat ventral mesencephalic cells in vitro and in grafts. Following in vitro differentiation in medium containing ascorbic acid at concentrations ranging from 20 to 100 μM, significantly more neurons were immunopositive for the marker of mesencephalic dopamine neurons, tyrosine hydroxylase (TH), when compared to standard differentiation conditions containing no ascorbic acid. Mesencephalic cell suspensions supplemented with 100 μM ascorbic acid were also transplanted into unilateral 6-OHDA-lesioned rats and behavioral rotation was assessed at 2, 4, and 6 weeks posttransplantation. Grafts pretreated with ascorbic acid contained significantly more surviving dopamine neurons compared to nontreated grafts. However, no significant difference in rotation score was observed, with both groups showing a reversal and overcompensation of rotational bias. In addition, no evidence of neurogenesis of nigral dopamine neurons was observed in transplant groups. While the increased number of dopamine neurons observed in our study following ascorbic acid treatment may reflect a selective survival effect, our in vitro results suggest that ascorbic acid may act to increase the number dopamine neurons, both in culture and following transplantation, by stimulating dopaminergic differentiation of neural precursors from the fetal ventral mesencephalon.

Improved survival of young donor age dopamine grafts in a rat model of Parkinson's disease

In an attempt to improve the survival of implanted dopamine cells, we have readdressed the optimal embryonic donor age for dopamine grafts. In a rat model of Parkinson's disease, animals with unilateral 6-hydroxydopamine lesions of the median forebrain bundle received dopamine-rich ventral mesencephalic grafts derived from embryos of crown to rump length 4, 6, 9, or 10.5 mm (estimated embryonic age (E) 11, E12, E13 and E14 days post-coitus, respectively). Grafts derived from 4 mm embryos survived poorly, with less than 1% of the implanted dopamine cells surviving. Grafts derived from 9 mm and 10.5 mm embryos were similar to those seen in previous experiments with survival rates of 8% and 7% respectively. The best survival was seen in the group that received 6 mm grafts, which were significantly larger than all other graft groups. Mean dopamine cell survival in the 6 mm group (E12) was 36%, an extremely high survival rate for primary, untreated ventral mesencephalic grafts applied as a single placement, and more than fivefold larger than the survival rate observed in the 10.5 mm (E14) group. As E12 ventral mesencephalic tissues contain few, if any, differentiated dopamine cells we conclude that the large numbers of dopamine cells seen in the 6 mm grafts must have differentiated post-implantation. We consider the in vivo conditions which allow this differentiation to occur, and the implications for the future of clinical trials based on dopamine cell replacement therapy.

Embryonic neural progenitor cells: the effects of species, region, and culture conditions on long-term proliferation and neuronal differentiation

One of the major obstacles to the use of neural stem/progenitor cells in neuronal replacement therapy is the limited ability of these cells to generate sufficient numbers of specific neuronal phenotypes either in the culture dish or after transplantation in animal models of neurodegenerative disease. It is not yet fully understood whether embryonic neural stem and progenitor cells show species-specific or regional identities, or if current culture paradigms select for a particular subset of stem cells/progenitors with similar proliferation and differentiation capacities. To investigate this issue, we isolated embryonic neural progenitors derived from the developing rat and mouse central nervous system for in vitro culture to assess the regional, species-specific, and temporal effects on both cell proliferation and generation of neurons. Neurosphere cultures were derived from E13-15 mouse or rat developing striatum (medial, lateral, or whole ganglionic eminence), ventral mesencephalon, and cortex. We compared basic fibroblast growth factor and epidermal growth factor for their influence on cell proliferation and neuronal differentiation under defined differentiation paradigms. Seeding density and conditioned media were also tested for their effects on maintenance of cell proliferation over protracted time periods. Results showed that embryonic neural stem/progenitor cells maintained defined patterns of proliferation and neuronal differentiation, with both declining with time in vitro. Proliferation rate was more dependent on species and region than the neurotrophins or conditions used for culture. These results suggest that the appropriate selection of embryonic neural stem cells and culture conditions may be crucial for the optimization of their neurogenic potential.

Efficacy and tolerability assessment of cefprozil in children with acute otitis media

Young children contract as many as six to eight upper respiratory tract viral infections per year, and these infections frequently lead to secondary bacterial infections such as acute otitis media and sinusitis. Cefprozil is an orally active third generation cephalosporin which has demonstrated activity against the gram-positive organisms Streptococcus pyogenes, pneumoniae and agalactiae and against methicilin-susceptible Staphylococcus aureus. Cefprozil is also active against various gram-ves and certain anaerobic organisms, and is stable to hydrolysis by a number of b-lactamases. Present study is an effort to study the efficacy and safety of cefprozil in children with acute otitis media. Three hundred and thirty four children aged 6 months through 12 years with clinical symptoms and tympanic membrane signs of AOM received cefprozil 30 mg/kg/day in two divided doses per day for 10 days. Clinically, 96.6% patients were cured, 2.4% improved and there was failure of therapy in 1% of the patients. There was no need for any rescue medication and any change in antibiotic in any patient. A satisfactory bacteriological outcome was (i.e. cure, presumed cure, and cure plus reinfection with a different pathogen) was achieved in 95% of patients. In conclusion, cefprozil is a well tolerated and effective drug for acute otitis media in children. Moreover, its expanded spectrum of activity, ability to achieve adequate concentrations in tissues, suitability for twice-daily dosing, and proven tolerability suggest that it is a better alternative to agents conventionally used in acute otitis media.