Evaluation of proton density fat fraction (PDFF) obtained from a vendor-neutral MRI sequence and MRQuantif software.

OBJECTIVE: To validate the proton density fat fraction (PDFF) obtained by the MRQuantif software from 2D chemical shift encoded MR (CSE-MR) data in comparison with the histological steatosis data. METHODS: This study, pooling data from 3 prospective studies spread over time between January 2007 and July 2020, analyzed 445 patients who underwent 2D CSE-MR and liver biopsy. MR derived liver iron concentration (MR-LIC) and PDFF was calculated using the MRQuantif software. The histological standard steatosis score (SS) served as reference. In order to get a value more comparable to PDFF, histomorphometry fat fraction (HFF) were centrally determined for 281 patients. Spearman correlation and the Bland and Altman method were used for comparison. RESULTS: Strong correlations were found between PDFF and SS (rs = 0.84, p < 0.001) or HFF (rs = 0.87, p < 0.001). Spearman's coefficients increased to 0.88 (n = 324) and 0.94 (n = 202) when selecting only the patients without liver iron overload. The Bland and Altman analysis between PDFF and HFF found a mean bias of 5.4% ± 5.7 [95% CI 4.7, 6.1]. The mean bias was 4.7% ± 3.7 [95% CI 4.2, 5.3] and 7.1% ± 8.8 [95% CI 5.2, 9.0] for the patients without and with liver iron overload, respectively. CONCLUSION: The PDFF obtained by MRQuantif from a 2D CSE-MR sequence is highly correlated with the steatosis score and very close to the fat fraction estimated by histomorphometry. Liver iron overload reduced the performance of steatosis quantification and joint quantification is recommended. This device-independent method can be particularly useful for multicenter studies. CLINICAL RELEVANCE STATEMENT: The quantification of liver steatosis using a vendor-neutral 2D chemical-shift MR sequence, processed by MRQuantif, is well correlated to steatosis score and histomorphometric fat fraction obtained from biopsy, whatever the magnetic field and the MR device used. KEY POINTS: • The PDFF measured by MRQuantif from 2D CSE-MR sequence data is highly correlated to hepatic steatosis. • Steatosis quantification performance is reduced in case of significant hepatic iron overload. • This vendor-neutral method may allow consistent estimation of PDFF in multicenter studies.

Occurrence of 1153 organic micropollutants in the aquatic environment of Vietnam.

The rapid increase in the number and volume of chemical substances being used in modern society has been accompanied by a large number of potentially hazardous chemicals being found in environmental samples. In Vietnam, the monitoring of chemical substances is mainly limited to a small number of known pollutants in spite of rapid economic growth and urbanization, and there is an urgent need to examine a large number of chemicals to prevent impacts from expanding environmental pollution. However, it is difficult to analyze a large number of chemicals using existing methods, because they are time consuming and expensive. In the present study, we determined 1153 substances to grasp a pollution picture of microcontaminants in the aquatic environment. To achieve this objective, we have used two comprehensive analytical methods: (1) solid-phase extraction (SPE) and LC-TOF-MS analysis, and (2) SPE and GC-MS analysis. We collected 42 samples from northern (the Red River and Hanoi), central (Hue and Danang), and southern (Ho Chi Minh City and Saigon-Dongnai River) Vietnam. One hundred and sixty-five compounds were detected at least once. The compounds detected most frequently (>40 % samples) at µg/L concentrations were sterols (cholesterol, beta-sitosterol, stigmasterol, coprostanol), phthalates (bis(2-ethylhexyl) phthalate and di-n-butyl phthalate), and pharmaceutical and personal care products (caffeine, metformin). These contaminants were detected at almost the same detection frequency as in developed countries. The results reveal that surface waters in Vietnam, particularly in the center of large cities, are polluted by a large number of organic micropollutants, with households and business activities as the major sources. In addition, risk quotients (MEC/PNEC values) for nonylphenol, sulfamethoxazole, ampicillin, acetaminophen, erythromycin and clarithromycin were higher than 1, which indicates a possibility of adverse effects on aquatic ecosystems.

The synthesis of highly phosphorylated nucleotides, RNA and protein by Streptomyces aureofaciens.

During the sudden decrease in RNA synthesis in Streptomyces aureofaciens, i.e. around the 6th hour of cultivation, synthesis of adenosine and guanosine tetraphosphates and pentaphosphates begins. The synthesis of these nucleotides is highest during the onset of chlortetracycline production, around the 20th hour of cultivation and continues. During this phase of growth of S. aureofaciens, RNA and protein synthesis are reduced by about one order of magnitude as compared to the rate which can be observed at the beginning of cultivation, but the synthesis is not inhibited by exogenous CTC.

High prevalence of thyroid autoantibodies in a prospective series of patients with chronic hepatitis C before interferon therapy.

After describing two cases of Hashimoto's thyroiditis associated with chronic hepatitis C, we set up a prospective study to assess the prevalence of thyroid autoantibodies (thyroglobulin and thyroid microsomal autoantibodies) in 72 chronic hepatitis C patients (43 men and 29 women; mean age = 51 +/- 2.1 yr) before interferon therapy admitted between January and December 1991 to our liver unit. Thyroid autoantibodies were systematically assayed in 60 chronic HBsAg-positive patients (34 men and 26 women; mean age = 50 +/- 2.2 yr), who served as controls. Antibody to hepatitis C virus was detected with a second-generation enzyme immunoassay and then confirmed with a recombinant immunoblot assay and a supplemental enzyme immunoassay using two beads. In chronic hepatitis C patients, no men had thyroid autoantibodies. Nine of 29 women (31%) had thyroid autoantibodies. Among them, six (20.7%) had high titers of thyroid autoantibodies, and two had hypothyroidism. In all nine of these women, hepatitis C virus viremia was detected on nested polymerase chain reaction (with primers located in the 5' untranslated region). One year later, titers of thyroid autoantibodies had increased in one patient. Three other patients progressed to hypothyroidism. We judged four of 29 patients (13.8%) to have Hashimoto's thyroiditis on the basis of their high titers of thyroid autoantibodies and biological features of hypothyroidism. In the control group, only one man had thyroid microsome autoantibodies, at a very low titer (1:100). The association between chronic hepatitis C and presence of thyroid autoantibodies is clearly confirmed (p = 0.021) by this study.

Fluid replacement in dengue shock syndrome: a randomized, double-blind comparison of four intravenous-fluid regimens.

Dengue hemorrhagic fever and dengue shock syndrome (DSS) are major causes of childhood morbidity and mortality in many tropical countries. Increased intravascular permeability leading to shock is the cardinal feature of DSS. Fluid resuscitation to counteract massive plasma leakage is the mainstay of treatment. A double-blind, randomized trial comparing four intravenous-fluid regimens for acute resuscitation of 50 children with DSS was conducted. Colloids (dextran 70 or the protein digest gelafundin 35,000) restored cardiac index and blood pressure and normalized hematocrit more rapidly than crystalloids (Ringer's lactate or 0.9%-weight/volume saline). Dextran 70 provided the most rapid normalization of the hematocrit and restoration of the cardiac index, without adverse effects, and may be the preferred solution for acute resuscitation in DSS. Further large-scale double-blind trials are required to provide an evidence-based approach to the management of DSS.