Successful Implementation of Image-Guided Pencil-Beam Scanning Proton Therapy in Medulloblastomas

Medulloblastoma is the most common malignant brain tumour in children, while much rarer in adults. Although the prognosis and outcomes have greatly improved in the era of modern multidisciplinary management, long-term treatment-induced toxicities are common. Craniospinal irradiation followed by a boost to the primary and metastatic tumour sites forms the backbone of treatment. Proton therapy has been endorsed over conventional photon-based radiotherapy due to its superior dosimetric advantages and subsequently lower incidence and severity of toxicities. We report here our experience from South-East Asia's first proton therapy centre of treating 40 patients with medulloblastoma (38 children and adolescents, 2 adults) who received image-guided, intensity-modulated proton therapy with pencil-beam scanning between 2019 and 2023, with a focus on dosimetry, acute toxicities, and early survival outcomes. All patients could complete the planned course of proton therapy, with mostly mild acute toxicities that were manageable on an outpatient basis. Haematological toxicity was not dose-limiting and did not prolong the overall treatment time. Preliminary data on early outcomes including overall survival and disease-free survival are encouraging, although a longer follow-up and data on long-term toxicities are needed.

Lifetime Measurements of Excited States in ^{172}Pt and the Variation of Quadrupole Transition Strength with Angular Momentum

Lifetimes of the first excited 2^{+} and 4^{+} states in the extremely neutron-deficient nuclide ^{172}Pt have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+})=0.55(19) was found, similar to a handful of other such anomalous cases observed in the entire Segré chart. The observation adds to a cluster of a few extremely neutron-deficient nuclides of the heavy transition metals with neutron numbers N≈90-94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios observed in these cases. Such low values cannot, e.g., be explained within the framework of the geometrical collective model or by algebraic approaches within the interacting boson model framework. It is proposed that the group of B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios in the extremely neutron-deficient even-even W, Os, and Pt nuclei around neutron numbers N≈90-94 reveal a quantum phase transition from a seniority-conserving structure to a collective regime as a function of neutron number. Although a system governed by seniority symmetry is the only theoretical framework for which such an effect may naturally occur, the phenomenon is highly unexpected for these nuclei that are not situated near closed shells.

Electrophilic and nucleophilic pathways in ligand oxide mediated reactions of phenylsulfinylacetic acids with oxo(salen)chromium(V) complexes

The mechanism of oxidative decarboxylation of phenylsulfinylacetic acids (PSAA) by oxo(salen)Cr(V)⁺ ion in the presence of ligand oxides has been studied spectrophotometrically in acetonitrile medium. Addition of ligand oxides (LO) causes a red shift in the λ _max values of oxo(salen) complexes and an increase in absorbance with the concentration of LO along with a clear isobestic point. The reaction shows first-order dependence on oxo(salen)-chromium(V)⁺ ion and fractional-order dependence on PSAA and ligand oxide. Michaelis-Menten kinetics without kinetic saturation was observed for the reaction. The order of reactivity among the ligand oxides is picoline N-oxide > pyridine N-oxide > triphenylphosphine oxide. The low catalytic activity of TPPO was rationalized. Both electron-withdrawing and electron-donating substituents in the phenyl ring of PSAA facilitate the reaction rate. The Hammett plots are non-linear upward type with negative ρ value for electron-donating substituents, (ρ ^- = -0.740 to -4.10) and positive ρ value for electron-withdrawing substituents (ρ ⁺ = +0.057 to +0.886). Non-linear Hammett plot is explained by two possible mechanistic scenarios, electrophilic and nucleophilic attack of oxo(salen)chromium(V)⁺-LO adduct on PSAA as the substituent in PSAA is changed from electron-donating to electron-withdrawing. The linearity in the log k vs. E _ox plot confirms single-electron transfer (SET) mechanism for PSAAs with electron-donating substituents.

Spectroscopic investigation on kinetics, thermodynamics and mechanism for electron transfer reaction of iron(III) complex with sulphur centered radical in stimulated biological system

Electron transfer reactions of biological organic sulphides with several metal ions to generate sulphide radical cations are a great concern in biochemical process. To understand the mechanism, a stimulated biological system having model compounds, iron(III)-bipyridyl complex with thio-diglycolic acid (TDGA) was investigated. Spectroscopic study reveals the kinetics and thermodynamics of the reaction in aqueous perchloric acid medium. The reaction follows first and fractional order of 0.412 with respect to [Fe(bpy)3](3+) and TDGA, respectively. The oxidation is insensitive to variation in [H(+)] but slightly decreases with increase in ionic strength ([I]). Addition of acrylamide, a radical scavenger has no effect on the rate of the reaction. The high negative value of ΔS(#) (-74.3±1.09 J K(-1) mol(-1)) indicates the complex formed has a definite orientation higher than the reactants. Based on the above results, a suitable reaction mechanism for this reaction is proposed.

Studies on Polyaniline/Silver Molybdate Nanocomposites

Silver molybdate nanoparticles were successfully prepared by the hydrothermal process. Polyaniline–silver molybdate nanocomposites were prepared by in situ chemical oxidative polymerization technique. Silver molybdate nanoparticles and the polymer samples were characterized by conductivity studies, Fourier transform infrared spectra (FT-IR), UV-visible spectra, photoluminescence spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The electrical conductivity of PANI- Cl - increases when doped with silver molybdate nanoparticles and follows the percolation threshold.

Interdental spacing and dental caries in the primary dentition of 4-6 year old children

OBJECTIVE

There are various risk factors which play an essential role in the multifactorial disease "dental caries." Although absence of interdental spaces in the primary dentition may increase the risk of dental caries, not many studies have been carried out to assess this correlation. This study was performed to assess the relationship between interdental spacing and dental caries in primary dentition.

MATERIALS AND METHODS

Five hundred 4-6 year-old children were enrolled into this study. Dental caries was recorded using the criteria given by Warren et al. Following this, impressions were made for the upper and lower arches and dental casts were poured. Interdental spaces were measured on the dental casts using a digital verniercaliper. The data obtained were subjected to statistical analysis.

RESULTS

The number of sites with interdental spaces was higher in the maxillary arch in comparison to the mandibular arch. The highest number of interdental spaces was observed between the maxillary anteriors. The number of demineralized, but non-cavitated tooth surfaces (d(1))were higher than the number of cavitated tooth surfaces. This difference was significant in the mandibular anterior segment. Dental caries showed a negative correlation with interdental spacing. A significant correlation was found between dental caries and interdental spacing in the posterior segment of the mandibular arch.

CONCLUSION

This study showed that children with no interdental spacing in the primary dentition are at higher risk for dental caries.

Characterization of cryptic rearrangements, deletion, complex variants of PML, RARA in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is characterized by a reciprocal translocation t(15;17)(q22;q21) leading to the disruption of Promyelocytic leukemia (PML) and Retionic Acid Receptor Alpha (RARA) followed by reciprocal PML–RARA fusion in 90% of the cases. Fluorescence in situ hybridization (FISH) has overcome the hurdles of unavailability of abnormal and/or lack of metaphase cells, and detection of cryptic, submicroscopic rearrangements. In the present study, besides diagnostic approach we sought to analyze these cases for identification and characterization of cryptic rearrangements, deletion variants and unknown RARA translocation variants by application of D-FISH and RARA break-apart probe strategy on interphase and metaphase cells in a large series of 200 cases of APL. Forty cases (20%) had atypical PML–RARA and/or RARA variants. D-FISH with PML/RARA probe helped identification of RARA insertion to PML. By application of D-FISH on metaphase cells, we documented that translocation of 15 to 17 leads to 17q deletion which results in loss of reciprocal fusion and/or residual RARA on der(17). Among the complex variants of t(15;17), PML–RARA fusion followed by residual RARA insertion closed to PML–RARA on der(15) was unique and unusual. FISH with break-apart RARA probe on metaphase cells was found to be a very efficient strategy to detect unknown RARA variant translocations like t(11;17)(q23;q21), t(11;17)(q13;q21) and t(2;17)(p21;q21). These findings proved that D-FISH and break-apart probe strategy has potential to detect primary as well as secondary additional aberrations of PML, RARA and other additional loci. The long-term clinical follow-up is essential to evaluate the clinical importance of these findings.

Abstract P6-15-12: Preclinical Evaluation of a STAT3 Inhibitor in Breast Cancer

Breast cancer often arises from inappropriate activation of transcription factors involved in normal mammary development, such as the signal transducers and activators of transcription (STAT) family of transcription factors. STAT3, which plays an important role in mammary remodeling, is activated (as assessed by tyrosine phosphorylation) in approximately 70% of primary breast cancers, with many of these tumors being highgrade. Furthermore, inhibition of STAT3 leads to a loss of tumorigenicity of breast cancer cells. Therefore, targeting STAT3 in breast cancer would be a potentially beneficial form of therapy.

To identify small molecule STAT3 inhibitors, we developed a high throughput cell-based assay to identify compounds that inhibit STAT3- dependent transcriptional activity. We screened approximately 200,000 compounds, and specificity for STAT3 was ensured by eliminating molecules that inhibited either STAT1- or NF-kappaB-dependent transcriptional activity. From this screen, we identified 4-[4-(phenylmethyl) piperidin-1-yl] thieno[2,3-d]pyrimidine (PMPTP) (Probe ID ML116) as a potent inhibitor of STAT3 transcriptional activity, which has no effect on STAT1 or NF-kappaB-dependent transcriptional activity. Treatment with PMPTP of MDA-MB-468 breast cancer cells, which contain constitutively activated STAT3, leads to inhibition of expression of STAT3 target genes including bcl-x and mcl1. Furthermore, PMPTP is a potent inhibitor of viability of MDA-MB-468 breast cancer cells. By contrast, SK-BR-3 cells, which do not contain constitutively active STAT3, were only minimally affected. This suggests that PMPTP reduces the viability of cells that depend on constitutively active STAT3. PMPTP has no effect on STAT3 tyrosine or serine phosphorylation or STAT3 nuclear translocation, suggesting that PMPTP may be inhibiting STAT3 at the level of DNA binding or co-factor recruitment.

Importantly, PMPTP lowers the apoptotic potential of breast cancer cells thereby making them more susceptible to other forms of therapy. Building on this observation, we identified a number of beneficial combinations of PMPTP with cytotoxic drugs currently used in breast cancer therapy as well as novel anti-cancer agents. Additionally, we analyzed a number of structural analogues of PMPTP, and we identified two compounds that had approximately 4-fold increased potency in inhibiting the viability of breast cancer cells containing STAT3 activation.

Taken together, these findings identify PMPTP as a potential new form of therapy for breast cancers containing activated STAT3, which can be enhanced using conventional and non-conventional chemotherapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-15-12.

Treatment of crown dilaceration: an interdisciplinary approach

Trauma to primary teeth can result in a wide range of disturbances to the underlying permanent teeth, such as dilaceration. Root dilacerations occur more commonly than crown dilacerations. This paper is a report of an 11-year-old girl with a missing maxillary left anterior tooth. Past history revealed premature loss of primary maxillary anterior teeth due to trauma. Radiographic examination revealed crown dilaceration of permanent maxillary left central incisor. An interdisciplinary approach in the management of this child is presented herewith.

Papillon-Lefevre syndrome: a case report

Papillon-Lefevre syndrome is a rare autosomal recessive genetic disorder. The clinical manifestations include palmer planter hyperkeratosis with precocious progressive periodontal disease that results in premature exfoliation of primary and permanent dentitions. Patients are often edentulous at an early age. This is a case report of prosthodontic rehabilitation of a 15-year-old girl with Papillon-Lefevre syndrome.

Retention of a resin-based sealant and a glass ionomer used as a fissure sealant: a comparative clinical study

Sealing occlusal pits and fissures with resin-based sealants is a proven method of preventing occlusal caries. Retention of the sealant is very essential for its efficiency. This study evaluated the retention of glass ionomer used as a fissure sealant when compared to a self-cure resin-based sealant. One hundred and seven children between the ages of 6-9 years, with all four newly erupted permanent first molars were selected. Two permanent first molars on one side of the mouth were sealed with Delton, a resin-based sealant, and the contralateral two permanent first molars were sealed with Fuji VII glass ionomer cement. Evaluation of sealant retention was performed at regular intervals over 12 months, using Simonsen's criteria. At the end of the study period, the retention of the resin sealant was seen to be superior to that of the glass ionomer sealant.

Dentinogenesis imperfecta: a case report

Dentinogenesis imperfecta is an autosomal dominant disorder of tooth development characterized by the presence of opalescent dentin, resulting in a dusky blue to brownish discoloration of the teeth. This condition is genetically and clinically heterogeneous; it may affect only the teeth or it may be associated with the osteogenesis imperfecta. Dentinogenesis imperfecta has been subdivided into three types: type I is associated with osteogenesis imperfecta; in type II there is no associated osteogenesis imperfecta; and when the condition is associated with the Brandywine triracial isolate and large pulp chambers it is classified as type III. This report describes a 16-year-old female patient who showed the characteristic dental features of dentinogenesis imperfecta type II. The etiology and prevalence of the disorder, and a comprehensive treatment plan, will be briefly reviewed.

Witkop's tooth and nail syndrome: a multifaceted approach to dental management

Witkop's tooth and nail syndrome is a rare autosomal dominant disorder of ectodermal dysplasia characterized by hypodontia and nail dysplasia. Mutations in MSX-1 have been shown to be associated with this syndrome. There is failure of development and eruption of the dentition. Tooth shape may vary; the most common forms are conical and narrow crowns. The nails may be spoon shaped and slow growing and affect both finger and toe nails. The nail involvement is more severe in childhood. The present case describes a 14-year-old boy who showed the characteristic features of Witkop's syndrome. A multifaceted approach to the dental management of the patient is discussed.

Glass fiber-reinforced composite resin as a space maintainer: a clinical study

The aim of this study is to evaluate the use of glass fiber-reinforced composite resin (GFRCR) as a space maintainer and to compare it with a conventional band-and-loop space maintainer. A total of 30 children (23 boys and 7 girls) aged 6-8 years were selected for the study. Each of these children required maintenance of space due to premature loss of primary first molars in at least two quadrants. In one quadrant, a GFRCR space maintainer was applied and in the other quadrant a band-and-loop space maintainer was cemented. Patients were recalled at regular intervals over 12 months and retention of both the types of space maintainers was evaluated. The retention of the GFRCR space maintainer was found to be superior to that of the band-and-loop space maintainer, but this difference was not statistically significant.