Comparison of viscoelastic flows in two- and three-dimensional serpentine channels.

Polymer solutions in the dilute regime play a significant role in industrial applications. Due to the intricate rheological properties of these highly viscoelastic fluids, especially in complex flow geometries, a thorough numerical analysis of their flow dynamics is imperative. In this research, we present a numerical investigation of purely elastic instability occurring in two- and three-dimensional serpentine channels under conditions where fluid inertia is negligible and across a broad spectrum of polymer relaxation times. Our findings reveal a strong qualitative agreement between the existing experimental results obtained from dilute solutions of flexible polymers in microfluidic devices and the numerical simulations conducted in two and three dimensions using the Oldroyd-B model. Spatial flow observations and statistical analysis of temporal flow features indicate that this purely elastic turbulent flow exhibits nonhomogeneous, non-Gaussian, and anisotropic characteristics across all scales. Additionally, our comparison of two- and three-dimensional simulations demonstrates that the elastic instability is primarily driven by the curvature of the streamlines induced by the flow geometry, rather than the weak secondary flow in the azimuthal direction. Therefore, our two-dimensional numerical simulations successfully replicate, at least qualitatively, the features observed in three-dimensional experiments. Furthermore, spectral analysis suggests that, in comparison to elastic turbulence in the dilute regime, the range of scales for the excited fluctuations is narrower.

Statistical properties of two-dimensional elastic turbulence.

We numerically investigate the spatial and temporal statistical properties of a dilute polymer solution in the elastic turbulence regime, i.e., in the chaotic flow state occurring at vanishing Reynolds and high Weissenberg numbers. We aim at elucidating the relations between measurements of flow properties performed in the spatial domain with the ones taken in the temporal domain, which is a key point for the interpretation of experimental results on elastic turbulence and to discuss the validity of Taylor's hypothesis. To this end, we carry out extensive direct numerical simulations of the two-dimensional Kolmogorov flow of an Oldroyd-B viscoelastic fluid. Static pointlike numerical probes are placed at different locations in the flow, particularly at the extrema of mean flow amplitude. The results in the fully developed elastic turbulence regime reveal large velocity fluctuations, as compared to the mean flow, leading to a partial breakdown of Taylor's frozen-field hypothesis. While second-order statistics, probed by spectra and structure functions, display consistent scaling behaviors in the spatial and temporal domains, the third-order statistics highlight robust differences. In particular the temporal analysis fails to capture the skewness of streamwise longitudinal velocity increments. Finally, we assess both the degree of statistical inhomogeneity and isotropy of the flow turbulent fluctuations as a function of scale. While the system is only weakly nonhomogenous in the cross-stream direction, it is found to be highly anisotropic at all scales.

Pleomorphic Adenoma of the Cheek: A Case Report.

Pleomorphic adenoma (PA) is the most common benign tumor affecting both major and minor salivary glands. Parotid gland is the most commonly affected major salivary gland. Among minor salivary glands, palate is the most commonly affected site followed by lips, cheeks, gingiva, floor of the mouth, and tongue. PA of buccal minor salivary glands is a very rare occurrence both in adults and children. In this report, we present a case of PA of buccal minor salivary gland in an adult patient who was successfully treated by wide local surgical excision, and after a follow-up period of one year there was no recurrence. A review of literature of PA of cheek is also presented.

Particle-laden two-dimensional elastic turbulence.

The aggregation properties of heavy inertial particles in the elastic turbulence regime of an Oldroyd-B fluid with periodic Kolmogorov mean flow are investigated by means of extensive numerical simulations in two dimensions. Both the small- and large-scale features of the resulting inhomogeneous particle distribution are examined, focusing on their connection with the properties of the advecting viscoelastic flow. We find that particles preferentially accumulate on thin highly elastic propagating structures and that this effect is the largest for intermediate values of particle inertia. We provide a quantitative characterization of this phenomenon that allows to relate it to the accumulation of particles in filamentary highly strained flow regions producing clusters of correlation dimension close to 1. At larger scales, particles are found to undergo turbophoretic-like segregation. Indeed, our results indicate a close relationship between the profiles of particle density and fluid velocity fluctuations. The large-scale inhomogeneity of the particle distribution is interpreted in the framework of a model derived in the limit of small, but finite, particle inertia. The qualitative characteristics of different observables are, to a good extent, independent of the flow elasticity. When increased, the latter is found, however, to slightly reduce the globally averaged degree of turbophoretic unmixing.

Immunotherapy approach with recombinant survivin adjuvanted with alum and MIP suppresses tumor growth in murine model of breast cancer.

Survivin has received attention as a potential target for cancer immunotherapy because of its crucial role in oncogenesis. We undertook this study to evaluate the immunotherapeutic potential of combination of recombinant survivin along with adjuvant alum and immune modulator Mycobacterium indicus pranii (MIP). In vivo efficacy of the combination was studied in an invasive murine breast cancer model. Recombinant survivin protein was purified from Escherichia coli based expression system and characterized by western blotting. Purified survivin protein was combined with alum and MIP and was used for immunization of Balb/c mice. Antigen-primed animals were then challenged with syngeneic mammary tumor cells known as 4T-1. Balb/c mice spontaneously develop tumor when inoculated with 4T-1 cells. Antigen and adjuvant combination was immunogenic and significantly suppressed tumor growth in mice immunized with combination of recombinant survivin (10 µg), alum, and MIP. This is the first report that describes a combination immunotherapy approach using recombinant survivin, alum, and MIP in highly metastatic murine breast cancer model and holds promise for development of new biotherapeutics for cancer.

Combination immunotherapy with Survivin and luteinizing hormone-releasing hormone fusion protein in murine breast cancer model.

AIM: To investigate the therapeutic potential of two recombinant proteins, Survivin and luteinizing hormone-releasing hormone (LHRH) fusion protein [LHRH(6leu)-LTB] for immunotherapy of breast cancer. METHODS: Murine 4T-1 breast cancer model was used to evaluate the efficacy of recombinant proteins in vivo. Twenty four Balb/c mice were divided into 4 groups of 6 mice each. Recombinant Survivin and LHRH fusion protein, alone or in combination, were administered along with immunomodulator Mycobacterium indicus pranii (MIP) in Balb/c mice. Unimmunized or control group mice were administered with phosphate buffer saline. Each group was then challenged with syngeneic 4T-1 cells to induce the growth of breast tumor. Tumor growth was monitored to evaluate the efficacy of immune-response in preventing the growth of cancer cells. RESULTS: Preventive immunization with 20 µg recombinant Survivin and MIP was effective in suppressing growth of 4T-1 mouse model of breast cancer (P = 0.04) but 50 µg dose was ineffective in suppressing tumor growth. However, combination of Survivin and LHRH fusion protein was more effective in suppressing tumor growth (P = 0.02) as well as metastasis in vivo in comparison to LHRH fusion protein as vaccine antigen alone. CONCLUSION: Recombinant Survivin and MIP suppress tumor growth significantly. Combining LHRH fusion protein with Survivin and MIP enhances tumor suppressive effects marginally which provides evidence for recombinant Survivin and LHRH fusion protein as candidates for translating the combination cancer immunotherapy approaches.

Intra-oral reduction of zygomatic fractures.

Zygomatico-maxillary complex fractures present a challenging diagnostic and reconstructive task to the surgeon. Gillie's temporal approach has been a commonly used technique for zygomatic arch reduction, but surgeons have been commonly using a buccal sulcus approach for the reduction of zygomatic arch fractures as well as for combined zygomatico-maxillary complex fractures. This article outlines the use of Rowe's elevator (modification of Bristow's elevator) intra-orally to reduce zygomatic arch fractures and, if required, simultaneously plate the zygoma through the same approach. A retrospective analysis of 379 patients treated with this technique in the last 10 years has been presented along with a comprehensive treatment protocol including a description of its advantages over the Gillie's approach. Based on the inclusion criteria, the study group consisted of 327 patients. In 281 patients, the zygomatic complex was fractured, whereas 46 patients presented with a solitary zygomatic arch fracture. Two hundred and three cases were successfully treated with the buccal sulcus approach, whereas 124 cases required both the buccal sulcus and the extra-oral lateral orbital approaches. The described approach has advantages over Gillie's temporal approach by being simple, faster and cost-effective, can be performed under local anesthesia, and is more esthetic as it does not leave any scars.

Cone-beam Computed Tomography Volumetric Analysis and Comparison of Dentin Structure Loss after Retrieval of Separated Instrument by Using Ultrasonic EMS and ProUltra Tips.

INTRODUCTION: A separated instrument within the root canal may interfere in the successful outcome of endodontic treatment. The retrieval of fractured instruments might compromise the remaining tooth structure and subsequently resistance to tooth fracture. The aim of this study was to compare the change in volume of root canal and dentin thickness after retrieval of separated instrument by 2 different endodontic ultrasonic tips. METHODS: Each of the instruments (EMS Endochuck and ProUltra #6, #7, and #8 tips) was used to remove 40 separated rotary ProTaper F2 instruments from the mesiobuccal roots of mandibular molar under ×15 magnification. Cone-beam computed tomography analysis of the samples was done to evaluate the change in volume, dentin thickness, weight, time taken, and success. RESULTS: Paired sample t test showed statistically significant (P < .05) difference in volume before and after instrument retrieval in both the EMS group, where the increase was 112.52%, and in the ProUltra group, where the increase was by 55.35%. Intergroup comparison showed statistically significant (P < .05) decrease in dentin thickness; it was more for EMS as compared with ProUltra. Overall decrease in the mean weight of EMS group (18.42%) was more than that of ProUltra group (9.36%). The overall success rate for removal of fractured instrument in this study was 87.5%; however, the difference in success rate was not statistically significant. The mean time taken for retrieval by ProUltra system was 63.89 minutes, whereas it was significantly less (P < .05) for EMS system (50.22 minutes). CONCLUSIONS: Removal of separated instrument with EMS resulted in more significant tooth structure loss as compared to ProUltra.

Survivin: a unique target for tumor therapy.

Survivin is the smallest member of the Inhibitor of apoptosis (IAP) family of proteins, involved in inhibition of apoptosis and regulation of cell cycle. These functional attributes make Survivin a unique protein exhibiting divergent functions i.e. regulating cell proliferation and cell death. Expression pattern of Survivin is also distinctive; it is prominently expressed during embryonal development, absent in most normal, terminally differentiated tissues but upregulated in a variety of human cancers. Expression of Survivin in tumours correlates with not only inhibition of apoptosis and a decreased rate of cell death, but also resistance to chemotherapy and aggressiveness of tumours. Therefore, Survivin is an important target for cancer vaccines and therapeutics. Survivin has also been found to be prominently expressed on both human and embryonic stem cells and many somatic stem cell types indicating its yet unexplored role in stem cell generation and maintenance. Overall, Survivin emerges as a molecule with much wider role in cellular homeostasis. This review will discuss various aspects of Survivin biology and its role in regulation of apoptosis, cell division, chemo-resistance and tumour progression. Various molecular and immunotherapeutic approaches targeting Survivin will also be discussed.

Dental Pulp Status of Posterior Teeth in Patients with Oral and Oropharyngeal Cancer Treated with Concurrent Chemoradiotherapy.

INTRODUCTION: The absence of tooth sensitivity has been observed in patients who have undergone radiotherapy. The aim of this investigation was to evaluate the effects of concurrent chemoradiotherapy on the pulp status of posterior teeth in patients with malignant oral and oropharyngeal cancer. METHODS: Twenty-one patients diagnosed with malignant oral and oropharyngeal cancer undergoing concurrent chemoradiotherapy underwent cold thermal pulp sensitivity testing and electric pulp testing of 4 teeth, 1 from each quadrant, at 4 points in time (PT): before radiotherapy (PT1), after 30-35 Gy (PT2), at the end of radiotherapy at 66-70 Gy (PT3), and 4 months (PT4) after beginning radiotherapy. RESULTS: All 84 teeth tested positive to cold thermal pulp sensitivity testing at PT1 (100%) and 25 teeth at PT2. No tooth responded at PT3 and PT4 (100%). A statistically significant difference (P < .05) existed in the number of positive responses between different points in time. CONCLUSIONS: Radiotherapy decreased the number of teeth responding to pulp sensitivity testing after doses greater than 30-35 Gy.

Radiation-induced dental caries, prevention and treatment - A systematic review.

Treatment of head and neck cancers (HNCs) involves radiotherapy. Patients undergoing radiotherapy for HNCs are prone to dental complications. Radiotherapy to the head and neck region causes xerostomia and salivary gland dysfunction which dramatically increases the risk of dental caries and its sequelae. Radiation therapy (RT) also affects the dental hard tissues increasing their susceptibility to demineralization following RT. Postradiation caries is a rapidly progressing and highly destructive type of dental caries. Radiation-related caries and other dental hard tissue changes can appear within the first 3 months following RT. Hence, every effort should be focused on prevention to manage patients with severe caries. This can be accomplished through good preoperative dental treatment, frequent dental evaluation and treatment after RT (with the exception of extractions), and consistent home care that includes self-applied fluoride. Restorative management of radiation caries can be challenging. The restorative dentist must consider the altered dental substrate and a hostile oral environment when selecting restorative materials. Radiation-induced changes in enamel and dentine may compromise bonding of adhesive materials. Consequently, glass ionomer cements have proved to be a better alternative to composite resins in irradiated patients. Counseling of patients before and after radiotherapy can be done to make them aware of the complications of radiotherapy and thus can help in preventing them.