Sequential measurement of 13 C, 15 N, and 34 S isotopic composition on nanomolar quantities of carbon, nitrogen, and sulfur using nano-elemental analysis/isotope ratio mass spectrometry.

RATIONALE: We report modifications to a commercial elemental analyzer-isotope ratio mass spectrometer that permit high-precision isotopic analysis of nanomoles of carbon (C), nitrogen (N), and sulfur (S) on a single sample without chemical or cryogenic trapping of gases. The sample size required for measurement by our system is about two orders of magnitude less than that for conventional analyses. METHODS: Our system builds on the analytical advancements offered by the EA IsoLink IRMS System and employs simple modifications to reduce the diameter of the flow path (reactors, water trap, and transfer lines), enhance peak separation (gas chromatography capillary column), and improve sample transfer to the ion source of the mass spectrometer (reduced flow rates). RESULTS: Conventional precision (<0.2‰) can be achieved down to c. 500 nmol C, N, and S for samples analyzed without modification of the commercial system. Further reduction in sample size (<50 nmol C, N, and S) was achieved with minor modifications. There is a significant carbon blank and a small nitrogen blank that can be measured directly and a sulfur blank that can be calculated using regression. Only 30 nmol of N, 22 nmol of C, and 12 nmol of S are needed to achieve better than 1‰ precision (1σ) from a single measurement. Larger samples and more replicate measurements provide better precision. CONCLUSIONS: The nano-EA method described here reduces sample size requirements by two orders of magnitude compared to traditional approaches and improves the accuracy and precision of isotope measurements on sample sizes less than 1 µmol. These advancements simplify the analytical technique and broaden the range and type of samples amenable to EA analysis.

Sequential measurement of δ15 N, δ13 C and δ34 S values in archaeological bone collagen at the Scottish Universities Environmental Research Centre (SUERC): A new analytical frontier.

RATIONALE: The use of multi-isotopic analysis (δ15 N, δ13 C and δ34 S values) of archaeological bone collagen to assist in the interpretation of diet, movement and mobility of prehistoric populations is gradually increasing, yet many researchers have traditionally avoided investigating sulphur due to its very low concentrations (<0.3%) in mammalian collagen. For this reason, and as a consequence of analytical detection limits, sulphur is usually measured separately from carbon and nitrogen, which leads to longer analytical times and higher costs. METHODS: A Thermo Scientific™ EA IsoLink™ isotope ratio mass spectrometry (IRMS) system, with the ability to rapidly heat a gas chromatography (GC) column and concentrate the sample gas online without cryo-trapping, was used at the Radiocarbon Laboratory at the Scottish Universities Environmental Research Centre (SUERC). Optimisation of the GC temperature and carrier gas flow rate in the elemental analyser resulted in improved signal-to-noise (S/N) ratio and sensitivity for SO2 . This allowed for routine sequential N2 , CO2 and SO2 measurements on small samples of bone collagen. RESULTS: Improvements in sample gas transfer to the mass spectrometer allows for sequential δ15 N, δ13 C and δ34 S values to be measured in 1-1.5 mg samples of bone collagen. Moreover, the sensitivity and S/N ratio of the sample gas, especially SO2 , is improved, resulting in precisions of ±0.15‰ for δ15 N values, ±0.1‰ for δ13 C values and ±0.3‰ for δ34 S values. Previous instrumentation allowed for the analysis of ~30 unknown samples before undertaking maintenance; however, ~150 unknown samples can now be measured, meaning a 5-fold increase in sample throughput. CONCLUSIONS: The ability to sequentially measure δ15 N, δ13 C and δ34 S values rapidly in archaeological bone collagen is an attractive option to researchers who want to build larger, more succinct datasets for their sites of interest, at a much-reduced analytical cost and without destroying larger quantities of archaeological material.

Safety of Repeated Injections of Sodium Hyaluronate (SUPARTZ) for Knee Osteoarthritis: A Systematic Review and Meta-Analysis.

OBJECTIVE: Though there is no consensus on its efficacy, knee osteoarthritis is symptomatically managed with intra-articular hyaluronic acid (IAHA). Recent reports suggest that IAHA may delay the need for total knee replacement, with the magnitude of delay proportional to the number of injection series. However, the safety of repeated injection series is reported to vary between commercial products. This report describes a systematic review of safety data on repeated treatment courses of SUPARTZ. DESIGN: We performed a systematic search of MEDLINE, Cochrane database, EMBASE, Web of Science, Google Scholar, and unpublished data. We included all human randomized controlled trials or observational studies with adverse event (AE) data for SUPARTZ in knee osteoarthritis. Two independent reviewers extracted data and evaluated study quality. Data were analyzed separately for the first and subsequent series of injections. RESULTS: The primary sources for repeated-injection data on SUPARTZ were a postmarket registry (N = 7404), 4 prospective studies (N = 127 total), and a retrospective study (N = 220). None of the sources reported increased frequency or severity of AEs with repeated injections. In the registry, 95% of multiple-injection-series patients who reported an AE did so during the first series. None of the AEs was serious, and most resolved spontaneously without medical intervention. The overall adverse event rate after repeat courses of SUPARTZ was 0.008 (95% confidence interval: 0.001-0.055). CONCLUSIONS: Multiple courses of SUPARTZ injections appear to be at least as safe, and probably safer, than the first course. This study supports the safety of repeat courses of SUPARTZ injections for knee osteoarthritis.

Overexpression of CREB reduces CRE-mediated transcription: behavioral and cellular analyses in transgenic mice.

The CREB transcription factor mediates neuronal plasticity in many systems, but the relationship between CREB levels and CRE-mediated transcription in individual neurons in vivo is unclear. In FVB/N nontransgenic mice, we observed that Purkinje cells showed low basal levels of Ser(133)-phosphorylated CREB protein yet displayed strong CRE-directed transcription. Transgenic mice overexpressing CREB in Purkinje cells and dentate gyrus granule cells showed a decreased CRE-lacZ signal in the same cells, indicating repression of ATF/CREB family function. Dentate region long-term potentiation was not altered by these changes in CREB expression. CREB transgenic mice demonstrated an inability to perform the rotarod task, without signs of overt ataxia. Our results demonstrate that the level of phosphorylated CREB protein is not a reliable indicator of CRE-mediated function. Furthermore, we conclude that CRE-mediated transcription may be linked to only a subset of cerebellum-mediated motor behaviors and may not be universally required for long-lasting synaptic potentiation.