Recycling of dissolved iron in the North Pacific Subtropical Gyre

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hawco, N. J., Yang, S.-C., Pinedo-Gonzalez, P., Black, E. E., Kenyon, J., Ferron, S., Bian, X., & John, S. G. Recycling of dissolved iron in the North Pacific Subtropical Gyre. Limnology and Oceanography, 67(11), (2022): 2448-2465, https://doi.org/10.1002/lno.12212.The importance of iron as a limiting nutrient in the open ocean is widely recognized, but there is substantial uncertainty about the rate that it cycles in the marine environment. Here, we combine measurements from the water column, sediment traps, and incubations to constrain Fe turnover during summer at Station ALOHA in the North Pacific Subtropical Gyre. Using low levels of 57Fe–58Fe double spike, measured with high precision by multi-collector inductively coupled plasma mass spectrometry, we find Fe uptake rates of 30–60 pM d−1 throughout the euphotic zone. Dissolved Fe turnover times are estimated at 10–15 d in the mixed layer and 1–3 d near the deep chlorophyll maximum. Aerosol Fe supply inferred from a thorium isotope mass balance indicates that the dissolved Fe residence time is approximately 6 months in the upper euphotic zone (0–75 m), relative to external sources, and 2 months in the lower euphotic zone (75–150 m). To reconcile these observations, the average Fe atom must be recycled over 25 times at Station ALOHA in both the upper and lower euphotic zones (an “Fe ratio” equal to 0.04 and 0.03, respectively), a level of conservation that has only been documented in Fe-limited regions thus far. At steady state, this scenario requires an aerosol Fe solubility of 4.5%, which is similar to dissolution experiments from Pacific Ocean aerosols. Our results suggest that the oligotrophic ocean is capable of recycling iron efficiently even when these ecosystems are not demonstrably iron-limited.This work was also supported by the Simons Foundation (602538 and 823167 to N.J.H., 329108 to S.G.J) and National Science Foundation grants 2022969 to N.J.H. and 1911990 to S.F

Association of vitamin D deficiency and subclinical diabetic peripheral neuropathy in type 2 diabetes patients

BackgroundDiabetic peripheral neuropathy (DPN) contributes to disability and imposes heavy burdens, while subclinical DPN is lack of attention so far. We aimed to investigate the relationship between vitamin D and distinct subtypes of subclinical DPN in type 2 diabetes (T2DM) patients.MethodsThis cross-sectional study included 3629 T2DM inpatients who undertook nerve conduction study to detect subclinical DPN in Zhongshan Hospital between March 2012 and December 2019. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D (25(OH)D) level < 50 nmol/L.Results1620 (44.6%) patients had subclinical DPN and they were further divided into subgroups: distal symmetric polyneuropathy (DSPN) (n=685), mononeuropathy (n=679) and radiculopathy (n=256). Compared with non-DPN, DPN group had significantly lower level of 25(OH)D (P < 0.05). In DPN subtypes, only DSPN patients had significantly lower levels of 25(OH)D (36.18 ± 19.47 vs. 41.03 ± 18.47 nmol/L, P < 0.001) and higher proportion of vitamin D deficiency (78.54% vs. 72.18%, P < 0.001) than non-DPN. Vitamin D deficiency was associated with the increased prevalence of subclinical DPN [odds ratio (OR) 1.276, 95% confidence interval (CI) 1.086-1.501, P = 0.003] and DSPN [OR 1. 646, 95% CI 1.31-2.078, P < 0.001], independent of sex, age, weight, blood pressure, glycosylated hemoglobin, T2DM duration, calcium, phosphorus, parathyroid hormone, lipids and renal function. The association between vitamin D deficiency and mononeuropathy or radiculopathy was not statistically significant. A negative linear association was observed between 25(OH)D and subclinical DSPN. Vitamin D deficiency maintained its significant association with subclinical DSPN in all age groups.ConclusionsVitamin D deficiency was independently associated with subclinical DSPN, rather than other DPN subtypes

The Potential Mechanisms of Berberine in the Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a globally observed metabolic disease with high prevalence both in adults and children. However, there is no efficient medication available yet. Increased evidence indicates that berberine (BBR), a natural plant product, has beneficial effects on NAFLD, though the mechanisms are not completely known. In this review, we briefly summarize the pathogenesis of NAFLD and factors that influence the progression of NAFLD, and focus on the potential mechanisms of BBR in the treatment of NAFLD. Increase of insulin sensitivity, regulation of adenosine monophosphate-activated protein kinase (AMPK) pathway, improvement of mitochondrial function, alleviation of oxidative stress, LDLR mRNA stabilization, and regulation of gut microenvironment are the major targets of BBR in the treatment of NAFLD. Additionally, reduction of proprotein convertase subtilisin/kexin 9 (PCSK9) expression and DNA methylation are also involved in pharmacological mechanisms of berberine in the treatment of NAFLD. The immunologic mechanism of BBR in the treatment of NAFLD, development of berberine derivative, drug combinations, delivery routes, and drug dose can be considered in the future research

The Principle and Application of “On Peak Zero” Correction in MC-ICP-MS Analysis

BACKGROUND: Multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) has been widely applied to accurate and precise measurements of isotope ratios due to its high sample throughput, strong ionization ability of ICP sources and high mass resolution. For decades, the standard-sample bracketing (SSB) method has been used to correct for instrumental mass bias during the measurement to achieve accurate results. When the content of the target isotope in samples is low, the measurement results are easily influenced by the background signals. "On Peak Zero" correction deducts the background signal from the total signal, which is an effective method to eliminate the background interference and has been widely used, but no research has been conducted to systematically explore the mathematical principles behind this correction.OBJECTIVES: To establish a mathematical model for the "On Peak Zero" correction, and verify its confidence by applying it to isotope measurements of different concentrations of Li, S, Fe, Sr, Nd and Pb standard solutions.METHODS: In this study, a mathematical model of the influence by the background signal on isotopic composition was established by mathematical reasoning and approximate substitution. Standard solutions of different concentrations of Li, S, Fe, Sr, Nd and Pb were prepared for the application of the "On Peak Zero" method through experimental analysis. Two types of blank signals were subtracted separately from the aggregate signals to simulate isotope measurements without and with "On Peak Zero" correction.RESULTS: The results indicate that the lower the concentration of the target element, the greater is the blank solution signal influence on the accuracy of the sample to be tested, and the "On Peak Zero" method can better eliminate the influence of the blank solution on the sample measurements. The simulation results based on this model were consistent with the real experimental results in this study.CONCLUSIONS:The mathematical model and the data explain well the effect of background concentration on the experimental isotope values, and are useful for understanding the application of the "On Peak Zero" method in MC-ICP-MS isotope analysis

Dissolved concentrations of nickel and copper from bottle samples collected on Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from October to November 2018

Dataset: GP15 Dissolved Ni and Cu - Leg 2This dataset contains dissolved concentrations of nickel (Ni) and copper (Cu) from bottle samples. The samples were collected during the U.S. GEOTRACES PMT cruise aboard the R/V Roger Revelle (RR1815 from October 24th to November 23rd of 2018). The dataset also includes station number, date, time, latitude, longitude, event number, event description, sample number, depth, and data quality flag. The data from Leg 1 of this transect, RR1814, are available as a related dataset. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/885335NSF Division of Ocean Sciences (NSF OCE) OCE-173689

Concentrations of dissolved cadmium, nickel, manganese, lanthanum, cerium, praseodymium, and neodymium from the Eastern Tropical North Pacific Ocean on R/V Revelle cruise RR1804-1805 (OMZ Nutrient Cycling project)

Dataset: ETNP dissolved Cd, Ni, Mn, and light rare earth elements (La, Ce, Pr, and Nd)Oxygen deficient zones (ODZs) play an important role in the distribution and cycling of trace metals in the ocean, as important sources of metals including Fe and Mn to the ocean, and also as possible sinks of chalcophile elements such as Cd. The Eastern Tropical North Pacific (ETNP) ODZ is one of the three largest ODZs worldwide. Here we present results from two sectional surveys through the ETNP ODZ (23N-14N, 105W-130W) conducted during two cruises of the R/V Roger Revelle, RR1804 and RR1805, from March to April 2018, providing a high-resolution concentrations of dissolved Cd, Ni, Mn, La, Ce, Pr, and Nd in seawater. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/872434NSF Division of Ocean Sciences (NSF OCE) OCE-163633

Dissolved concentrations of nickel and copper from bottle samples collected on Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018

Dataset: GP15 Dissolved Ni and Cu - Leg 1This dataset contains dissolved concentrations of nickel (Ni) and copper (Cu) from bottle samples. The samples were collected during the U.S. GEOTRACES PMT cruise aboard the R/V Roger Revelle (RR1814 from September 18th to October 21st of 2018). The dataset also includes station number, date, time, latitude, longitude, event number, event description, sample number, depth, and data quality flag. The data from Leg 2 of this transect, RR1815, are available as a related dataset. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/885319NSF Division of Ocean Sciences (NSF OCE) OCE-173689

Endoscopic Endonasal Dacryocystorhinostomy with Ostial Stent Intubation Following Nasolacrimal Duct Stent Incarceration

Purpose: To study the feasibility of endoscopic endonasal dacryocystorhinostomy (EE-DCR) with novel lacrimal ostial stent (LOS) intubation for patients with chronic dacryocystitis with incarceration of a previously implanted nasolacrimal duct stent (NDS). Methods: According to surgical procedure, 166 patients (167 eyes) were divided into two groups: EE-DCR with LOS intubation was performed on 126 patients (127 eyes) in the EE-DCR group; while external dacryocystorhinostomy (E-DCR) with silicone tube intubation was performed on 40 patients (40 eyes) in the E-DCR group. The LOS or silicone tube was retained for 3-6 months. All patients were followed up for 12-36 months. Success rate of tear drainage reconstruction (TDR) and complications were retrospectively compared. Results: Excluding patients with early detachment of the LOS or the silicone tube, or with incomplete follow-up period, 117 patients (117 eyes) in the EE-DCR group and 36 patients (36 eyes) in the E-DCR group were included. The mean surgical time was 45.8 ± 11.5 min in the EE-DCR group and 68.1 ± 23.8 min in the E-DCR group (p < 0.001). Intraoperatively, the lacrimal sac was observed to become very small and its walls were thin, hyperemic and fragile, firmly attaching to the NDS by fibrous bands in all eyes. Upon final review, success rate of TDR was 83.8% (98/117) in the EE-DCR group, while 58.3% (21/36) in the E-DCR group (p < 0.01). Failure of TDR due to ostial closure by excessive fibrosis occurred in 14 out of 19 patients in the EE-DCR group, significantly less than the 11 out of 15 patients with failed TDR in the E-DCR group (χ 2  = 6.959, p < 0.01). No significant difference existed in failures due to granuloma occluding the ostium or common canaliculus obstruction. Conclusion: EE-DCR with LOS intubation may be an effective procedure to manage the special subgroup of patients with chronic dacryocystitis with incarcerations of a previously implanted NDS