Osseous Tissue Engineering in the Management of Mandibular Osteoradionecrosis - An Evaluative Study.

Introduction: Osteoradionecrosis (ORN), a non-infectious, necrotic condition of the bone, occurs as a major complication of radiotherapy to the irradiated site. Simple irrigation of the involved bone to partial or complete resection of the involved bones is being employed in its conventional management. Osseous tissue engineering (OTE) provides a new strategy by regenerating bone cells along with biocompatible scaffolds and micromolecules to produce an engineered osseous tissue. Materials and Methods: In this study, mandibular ORN following radiation secondary to oropharyngeal squamous cell carcinoma was included. OTE with composite engineered tissue containing a mixture of autologous culture expanded dental pulp stem cells (DPSCs), autologous uncultured bone marrow aspiration concentrate (BMAC) and autologous platelet-rich plasma (PRP) loaded in ß-tricalcium phosphate (ß-TCP) or hydroxyapatite (HA) sponge scaffold was used in the mandibular defect and the surrounding tissues. An assessment of clinical, radiological and functional attributes was done. Results: A total of six cases with a mean age of 58.6 years were included in the study. We noted significant improvement in the mean post-operative score for pain and mouth opening; functional improvement in eating solid/liquid food, tongue movement, speech and deglutition were observed. The aesthetics was measured with Vancouver score and revealed a significance at P < 0.05; also lip competency and occlusion were noted in all the patients. No major complications were noticed until a mean follow-up of 28 months. Discussion: Tissue engineering with a regenerative cocktail of autologous culture expanded DPSCs, autologous uncultured BMAC and autologous PRP loaded in HA or ß-TCP utilised in the surgical reconstruction of the mandible is an effective treatment modality in the management of mandibular ORN following irradiation.

New constraints of terrestrial and oceanic global gross primary productions from the triple oxygen isotopic composition of atmospheric CO2 and O2.

Representations of the changing global carbon cycle under climatic and environmental perturbations require highly detailed accounting of all atmosphere and biosphere exchange. These fluxes remain unsatisfactory, as a consequence of only having data with limited spatiotemporal coverage and precision, which restrict accurate assessments. Through the nature of intimate coupling of global carbon and oxygen cycles via O2 and CO2 and their unique triple oxygen isotope compositions in the biosphere and atmosphere, greater insight is available. We report analysis of their isotopic compositions with the widest geographical and temporal coverage (123 new measurements for CO2) and constrain, on an annual basis, the global CO2 recycling time (1.5 ± 0.2 year) and gross primary productivities of terrestrial (~ 170-200 PgC/year) and oceanic (~ 90-120 PgC/year) biospheres. Observed inter-annual variations in CO2 triple oxygen isotopic compositions were observed at a magnitude close to the largest contrast set by the terrestrial and oceanic biospheres. The seasonal cycles between the east and west Pacific Ocean were found to be drastically different. This intra-annual variability implies that the entire atmospheric CO2 turnover time is not much longer than the tropospheric mixing time (less than ~ 5 months), verifying the derived recycling time. The new measurements, analyses, and incorporation of other global data sets allow development of an independent approach, providing a strong constraint to biogeochemical models.

Floating boat method for carbonate stable isotopic ratio determination in a GasBench II peripheral.

RATIONALE: Efficient high-precision stable isotope ratio determination using the GasBench II peripheral for carbonates involves loading of a reaction vial with carbonate powder and injection of phosphoric acid of high density for carbonate digestion. Herein, we present an alternative method, which bypasses the need for acid dosing with an automated pump. The advantages of the new method include minimization of clogging within capillaries caused by the acid, acid spillage, and diffusive fractionation due to repeated piercing of the septa. METHODS: The alternative method involves the use of low-cost boats preloaded with carbonate powder introduced into an Exetainer vial preinjected with phosphoric acid and placed within the compartment of a heated block maintained at a constant temperature in the GasBench II. RESULTS: The new method yielded an improvement in precision for δ13 CVPDB and δ18 OVPDB values during replicate analyses of NBS 19, with an overall precision of ±0.04‰ and ±0.06‰, respectively. The accuracy and precision of analysis using the conventional method and the floating boat method were statistically re-evaluated using a bootstrap error analysis and Monte Carlo simulation methods. CONCLUSIONS: The proposed floating boat method of acid digestion showed significant improvement in analytical procedure and overall precision. This method is easily adoptable in other laboratories and is free from frequent issues of needle clogging and irregular fractionation due to diffusion facilitated by repeated puncturing of septa, and can serve as an alternative method for high-precision carbonate stable isotope analysis.

Assessing bone mineral changes in response to vitamin D supplementation using natural variability in stable isotopes of Calcium in Urine.

Osteoporosis is a chronic disease of public health importance, particularly in low and middle income countries. Measuring the bone mineral balance (BMB) in a non-invasive manner, and its response to different interventions, is critical to the definition of optimal strategies for its prevention and management. In this study, we demonstrate the usefulness of natural variability in calcium isotopes (δ44/40Ca) of urine and the derived BMB estimates as a biomarker of bone health and its responsiveness to interventions. Vitamin D3 is commonly used as a supplement for the prevention and treatment of osteoporosis, along with calcium supplements. We studied the effect of a short term vitamin D3 supplementation on changes in urine δ44/40Ca and the derived BMB. δ44/40Ca before and after the vitamin D3 supplementation yielded a statistically significant change (p = 0.050) with a positive δ44/40Ca enrichment. The mean derived BMB was net positive (0.04 ± 0.05) in comparison to a net negative value for the control group (-0.03 ± 0.01). These results indicate the potential usefulness of urinary natural δ44/40Ca and the derived BMB, which, along with bone mineral density could be used as a sensitive marker for precision in the prevention and treatment of osteoporosis.

Temperature and Monsoon Tango in a Tropical Stalagmite: Last Glacial-Interglacial Climate Dynamics.

High-resolution paleoclimate data on stable isotopes in a stalagmite were coupled to glycerol dialkyl glycerol tetraethers (GDGTs). The Indian Summer Monsoon (ISM) transitioned from limited rainfall during the Last Glacial Maximum (LGM) to intense precipitation during early Holocene (22 to 6 ka). This was associated with changes in stalagmite growth, abundance of branched (br) and isoprenoid (iso) GDGTs, as well as δ18O, δ13C, Sr/Ca and GDGT-derived signals providing both temperature and moisture information. The reconstructed mean annual air temperature (MAAT) of the most modern stalagmite sample at ~19 °C, matches the surface and cave MAAT, but was ~4 °C lower during LGM. Warming at the end of LGM occurred before ISM strengthened and indicate 6 ka lag consistent with sea surface temperature records. The isotope records during the Younger Dryas show rapid progressions to dry conditions and weak monsoons, but these shifts are not coupled to TEX86. Moreover, change to wetter and stronger ISM, along with warmer Holocene conditions are not continuous indicating a decoupling of local temperatures from ISM.

Role of water contamination within the GC column of a GasBench II peripheral on the reproducibility of 18O/16O ratios in water samples.

The GasBench II peripheral along with MAT 253 combination provides a more sensitive platform for the determination of water isotope ratios. Here, we examined the role of adsorbed moisture within the gas chromatography (GC) column of the GasBench II on measurement uncertainties. The uncertainty in (18)O/(16)O ratio measurements is determined by several factors, including the presence of water in the GC. The contamination of GC with water originating from samples as water vapour over a longer timeframe is a critical factor in determining the reproducibility of (18)O/(16)O ratios in water samples. The shift in isotope ratios observed in the experiment under dry and wet conditions correlates strongly with the retention time of analyte CO(2), indicating the effect of accumulated moisture. Two possible methods to circumvent or minimise the effect of adsorbed water on isotope ratios are presented here. The proposed methodology includes either the regular baking of the GC column at a higher temperature (120 °C) after analysis of a batch of 32 sample entries or conducting the experiment at a low GC column temperature (22.5 °C). The effects of water contamination on long-term reproducibility of reference water, with and without baking protocol, have been described.

Tracing the source of bottled water using stable isotope techniques.

The Indian Summer Monsoon (ISM) precipitation recharges ground water aquifers in a large portion of the Indian subcontinent. Monsoonal precipitation over the Indian region brings moisture from the Arabian Sea and the Bay of Bengal (BoB). A large difference in the salinity of these two reservoirs, owing to the large amount of freshwater discharge from the continental rivers in the case of the BoB and dominating evaporation processes over the Arabian Sea region, allows us to distinguish the isotopic signatures in water originating in these two water bodies. Most bottled water manufacturers exploit the natural resources of groundwater, replenished by the monsoonal precipitation, for bottling purposes. The work presented here relates the isotopic ratios of bottled water to latitude, moisture source and seasonality in precipitation isotope ratios. We investigated the impact of the above factors on the isotopic composition of bottled water. The result shows a strong relationship between isotope ratios in precipitation (obtained from the GNIP data base)/bottled water with latitude. The approach can be used to predict the latitude at which the bottled water was manufactured. The paper provides two alternative approaches to address the site prediction. The limitations of this approach in identifying source locations and the uncertainty in latitude estimations are discussed. Furthermore, the method provided here can also be used as an important forensic tool for exploring the source location of bottled water from other regions.