Removal of contamination in helium for precise SF6 -based Δ36 S measurements.

RATIONALE: Quantifications of quadruple sulfur isotopic compositions (δ34 S, Δ33 S, and Δ36 S) of sulfur-bearing compounds in nature are valuable for providing new insights into the Earth's evolution such as the crust-mantle cycle, oxygenation of atmosphere and oceans, and the origin and evolution of early life. SF6 -based isotope ratio mass spectrometry is the most widely used method of quantification, but Δ36 S measurements at high precision and accuracy have always been technically difficult due to the low abundance of 36 S (~0.01%). In this paper, we identify a major source of isobaric interferences (i.e., contamination in helium carrier gas in the gas chromatography purification step) and propose a simple strategy to solve this problem. METHODS: An SF6 fluorination and purification system was built. Laboratory SF6 reference gas and international Ag2 S standard (IAEA-S1) were used as reference materials to test our method. Contamination from helium carrier gas (99.999%) was purified by a simple two-step cryogenic method to allow for accurate and precise measurements of Δ36 S using the SF6 -based isotope ratio mass spectrometry method. RESULTS: Without proper purification of helium carrier gas, large errors in Δ36 S measurements were found. Measured Δ36 S values of SF6 with trace contamination from helium were >10‰ higher than expected values. Using a newly developed purification strategy, the difference in Δ36 S values of SF6 before and after passing through the gas chromatography is less than instrumental errors (<0.2‰). Our improved method yielded an overall Δ36 S precision for IAEA-S1 of 0.12‰ (n = 6). This precision is comparable to that found by other laboratories around the world. CONCLUSION: Our simple two-step cryogenic method significantly improved the accuracy and precision of Δ36 S measurements and is therefore recommended for future determination of quadruple sulfur isotopic compositions in natural samples.

Complications and hospitalization costs in patients with hypothyroidism following total hip arthroplasty.

BACKGROUND: Hypothyroidism is a common disease in the US population. The impact of hypothyroidism on perioperative complications of total hip arthroplasty is poorly understood. To examine risk factors and hospitalization costs in patients with hypothyroidism after total hip arthroplasty (THA) using a large-scale sample national database. METHODS: A case-control study was performed based on the national inpatient sample database from 2005 to 2014. With the use of propensity scores, patients with hypothyroidism were matched in a 1:1 ratio to those without hypothyroidism by age, gender, race, Elixhauser Comorbidity Index (ECI), and insurance type. Patient demographics, postoperative complications, length of stay (LOS), and hospital costs were compared between matched cohorts. Short-term complication rates after THA were compared using multivariate logistic analysis. RESULTS: The proportion of patients with hypothyroidism receiving THA was 12.97%. Linear regression analysis yielded that patients with hypothyroidism receiving THA were more likely to have postoperative acute anemia (odds ratio = 1.15; 95% confidence interval = 1.12-1.18) and higher mean hospital costs compared to the non-hypothyroid cohort. CONCLUSIONS: This present study demonstrates that hypothyroid patients undergoing THA have a higher risk of short-term complications. Furthermore, it significantly increased the total cost of hospitalization, which deserves more attention from orthopedic surgeons.

Effect of continuous nursing combined with salcatonin on postoperative pains in elderly patients after hip replacement.

OBJECTIVE: This study was designed to explore the effect of continuous nursing combined with salcatonin on the improvements of postoperative pain in elderly patients after hip replacement. METHODS: A total of 99 elderly patients treated by hip replacement in our hospital were divided into the control group (CG, n=49, routine nursing + salcatonin) and the study group (SG, n=50, continuous nursing + salcatonin). The visual analogue scale (VAS) during rest (RVAS), VAS during initiative movement (IVAS) and VAS during passive movement = (PVAS) at 3 d, 7 d, 10 d, 14 d and 30 d after operation, the Harris hip score (HHS), Barthel index and geriatric depression scale (GDS) at 1 month after operation, and the incidences of tumble and refracture during the postoperative 6-month follow-up were compared between the two groups. RESULTS: In comparison with the CG, except for higher HHS and Barthel index at 1 month after operation (P<0.05), the SG was associated with lower RVAS, IVAS and PVAS at 7 d, 10 d, 14 d and 30 d after operation (P<0.05), lower GDS at 1 month after operation, and lower incidences of tumble and refracture during the 6 months after operation (P<0.05). CONCLUSION: The combination of continuous nursing and salcatonin has achieved marked effects not only on mitigating the pains at the early stage after a hip replacement in elderly patients, but also on improving their joint functions and reducing the incidences of tumble and refracture in a long run.

Postmenopausal hormone and the risk of nephrolithiasis: A meta-analysis.

Menopause is reported to be associated with increased urinary calcium excretion, which may enhance the risk for the development of calcium kidney stones. However, it remains controversial about whether high level of postmenopausal hormone (PMH) is a risk factor for formation of nephrolithiasis. Several observational studies have shown that PMH is protective based on 24-hour urinary parameters. Recent clinical trials provided evidence to conclude that estrogen therapy increases the risk of nephrolithiasis in healthy postmenopausal women. Our study aimed to comprehensively assess clinical evidence on the relationship between postmenopausal hormone level and risk of nephrolithiasis. To conduct systematic review, we pooled total 98 potentially related articles in Cochrane library, Medline, and Embase. Three studies with a total of 71101 study participants that included two clinical trials, 4 stratified and potentially usable results by the status of menopause and type of PMH use derived from one prospective cohort study, and one case-control studies were selected to pool relative risk using random-effect model. How the difference in menopause status, whether naturally menopausal or surgically menopausal, influenced the pooled relative risk was included in the subgroup analysis. The study population aged from 45 to 70 years old. The follow-up year and adjusted confounders differed across different studies. The pooled relative risk for the 7 stratified studies was 0.91 (95 % confidence interval (CI): [0.72, 1.14]). In the menopausal status-specific analysis, the pooled relative risk for naturally menopausal women was 0.92 (95 % CI, [0.64, 1.27]; I2 = 82.74 %) whereas the pooled relative risk for surgically postmenopausal women is 0.90 (95 % CI, [0.63, 1.29]; I2 = 78.47 %). The above results suggested that there was no significant association between PMH and the risk of nephrolithiasis. The difference in menopausal status did not influence the relationship between PMH and the risk of kidney stone formation.