Higher non-HDL-cholesterol to HDL-cholesterol ratio linked with increased nonalcoholic steatohepatitis.

BACKGROUND: Non-HDL-cholesterol to HDL-cholesterol (non-HDL-c/HDL-c) ratio is a feasible predictor for coronary heart disease, metabolic syndrome, and insulin resistance. Patients with nonalcoholic steatohepatitis (NASH) have an increased risk of developing cardiovascular problems and type 2 diabetes. However, the predictive role of non-HDL-c/HDL-c ratio in NASH hasn't been investigated yet. METHODS: We conducted a retrospective cohort study. A total of 3489 eligible subjects were selected in the present study. Prevalence and characteristics of NASH were demonstrated. Conditional logistic regression was used to analyze the association between non-HDL-c/HDL-c ratio and risks of NASH. Associations between non-HDL-c/HDL-c ratio and serum aminotransferase levels were also investigated. RESULTS: The overall prevalence of NASH was 6.13%, higher in male (6.89%) than that in female (5.04%). Interestingly, the prevalence of NASH showed a positive correlation with the elevation of non-HDL-c/HDL-c ratio (Pearson's Chi-squared test, linear trend 0.010, p <  0.05). The risk of NASH increased approximately 1.8-fold among subjects with higher non-HDL-c/HDL-c ratio. After adjustment for confounding factors, higher non-HDL-c/HDL-c ratio was still associated with a 54.4% increased risk of NASH. Male had higher risk of NASH than female when their non-HDL-c/HDL-c ratio increased. The risk of NASH in subjects with BMI more than 24 was 3 times higher than that in subjects with BMI less than 24. Every one unit increase in Non-HDL-c/HDL-c ratio was associated with 64.5% increase in ALT/AST level (p <  0.05) after adjustment for confounding factors. CONCLUSIONS: Our study provided strong evidence that subjects with higher non-HDL-c/HDL-c ratio had a higher risk of NASH, which suggested that non-HDL-c/HDL-c ratio might be a feasible predictor for NASH.

Berberine increases adipose triglyceride lipase in 3T3-L1 adipocytes through the AMPK pathway.

BACKGROUND: Obesity is closely related to the metabolism of triacylglycerol (TG) in adipocytes. Adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) are rate-limiting enzymes that control the hydrolysis of TG. Effects on ATGL and HSL to increase lipolysis may counteract obesity. Berberine (BBR) is a compound derived from the Chinese medicine plant Coptis chinensis. In the present study we show the effects of BBR on ATGL and HSL and explore the potential underlying mechanisms of these effects. METHODS: The TG content in cells was measured using a colorimetric assay. The expressions of HSL, ATGL and GPAT3 were evaluated by Western-blotting. The expression of ATGL was also evaluated by real-time PCR and radioimmunoassay. Compound C, an inhibitor of AMP-activated protein kinase (AMPK), was used to explore the possible pathway that involved in the effect of BBR on ATGL. RESULTS: TG content of differentiated 3T3-L1 cells was significantly decreased by more than 10% after treated with BBR. In differentiated 3T3-L1 adipocytes, BBR increased the expression of p-HSL and ATGL, and these effects were time-depended (p <0.01). The effect of BBR on ATGL expression could be abolished by Compound C which suggested that AMPK pathway was involved in the effects of BBR on p-HSL and ATGL. CONCLUSIONS: BBR could increase the expression of ATGL and therefore stimulate basal lipolysis in mature adipocytes through the associated mechanisms related to the AMPK pathway.

Vaspin as a Risk Factor of Insulin Resistance in Obstructive Sleep Apnea-Hypopnea Syndrome in an Animal Model.

BACKGROUND: In this study, we aimed to establish a chronic intermittent hypoxia model in rats and explore the possible role of vaspin in insulin sensitivity. METHODS: Healthy male Wistar rats were randomly divided into two groups: normal control group (NC) and chronic intermittent hypoxia group (CIH). The NC group was raised under physiological conditions and the CIH group was kept in the plexiglass chamber between 9 am and 5 pm undergoing intermittent hypoxic challenge for 8 hours/day for 8 weeks. Arterial blood pressure of rats (tail cannulation) was measured before and after the study. Fasting plasma glucose (FPG), total cholesterol (TC), triglycerides (TG), fasting insulin (FINS), vaspin, and leptin levels were measured. Vaspin mRNA expression in visceral adipose tissues was measured with Real Time-PCR. The protein levels of vaspin, Akt and phospho-Akt in visceral tissues were determined by Western-blot. RESULTS: At baseline, all the measurements in the CIH and NC groups were comparable. By the end of the experiment, the blood pressure of the CIH group was significantly higher than the NC group. The levels of FPG, FINS, TG, TC, leptin, and vaspin in the CIH group were significantly higher than in NC group. Plasma vaspin levels were correlated with FINS, HOMA-IR, and TG levels. Vaspin expression in both mRNA and protein levels in visceral adipose tissues of the CIH group were clearly higher than the NC group. Phospho-Akt protein level was decreased in visceral adipose tissues of the CIH group compared to the NC group. CONCLUSIONS: In the chronic intermittent hypoxia rat model, the expression of vaspin in visceral adipose tissues and plasma were increased, which were correlated with insulin resistance.

Therapeutic Effect of Metformin on Chemerin in Non-Obese Patients with Non-Alcoholic Fatty Liver Disease (NAFLD).

BACKGROUND: Chemerin is an important risk factor of insulin resistance. Non-alcoholic fatty liver has typical characteristics of insulin resistance. The aim of this study was to explore the potential role of chemerin in NAFLD. METHODS: 45 subjects included 22 control subjects (A group) and 23 subjects diagnosed with non-alcoholic fatty liver disease (B group) participated in the study. 23 patients in the NAFLD group received oral daily metformin at a dose of 20 mg/kg/day for 24 weeks follow-up. Chemerin and insulin resistance markers were determined at baseline and 24 weeks. RESULTS: The levels of WHR, BMI, FINS, HOMA-IR, TG, ALT, AST, and Chemerin in B group were significantly higher than A group. After 24 weeks of metformin treatment, the levels of WHR, AST, ALT, TG, chemerin and HOMA-IR were significantly reduced (p < 0.05) and other indexes were not changed significantly. Correlation analysis indicated that serum chemerin concentrations were positively correlated with BMI, WHR, HOMA-IR, FINS, TG, ALT, and AST levels. Logistic regression analysis showed chemerin, TG, and ALT were independent variables associated with NAFLD. CONCLUSIONS: These findings showed a significant increase of chemerin level in NAFLD patients. Metformin treatment can improve NAFLD and decrease the level of chemerin. Chemerin, TG, and ALT were independent variables associated with NAFLD.

Changes of lipin1ß expression in gestational diabetes mellitus.

BACKGROUND: Lipin1ß is an adipokine proposed to be associated with insulin resistance (IR). Pregnancy is a physiologic state of progressive IR. The objective of the present study was to investigate the role of lipin1ß in the development of GDM. METHODS: A total of 40 pregnant women (22 normal and 18 with GDM) who delivered healthy infants at full-term (> 37 weeks gestation) were included. The mRNA and protein levels of lipin1ß in adipose tissues were determined by real-time RT-PCR and Western-blot. Plasma glucose, lipids, insulin, and estradiol (E2) levels were measured routinely at fasting state, and HOMA-IR was calculated accordingly. RESULTS: The lipin1ß expression in both mRNA and protein levels in SAT and VAT was lower in GDM patients than controls. Lipin1ß mRNA in VAT was negatively correlated with BMI (r = -0.505, p < 0.05), FINS (r = -0.539, p < 0.05), HOMA-IR (r = -0.574, p < 0.01), TG (r = -0.471, p < 0.05), and E2 (r = -0.564, p < 0.01). Lipin1ß mRNA expression in SAT was similar with VAT. Lipin1ß mRNA was not correlated with body weight gain or blood pressure. These results indicated that the lipin1ß expression in adipose tissues is down-regulated in patients with GDM. CONCLUSIONS: Lipin1ß might play a role in the pathogenesis of insulin resistance in GDM.

The essential oils chemical compositions and antimicrobial, antioxidant activities and toxicity of three Hyptis species.

CONTEXT: Hyptis suaveolens (Linn.) Poit., Hyptis rhomboidea Mart. et Gal., and Hyptis brevipes Poit., are three species of Hyptis Jacq. (Lamiaceae). Hyptis suaveolens is used for the treatment of fever, headache, gastrointestinal bloating and rheumatism in the traditional folk medicine; Hyptis rhomboidea for hepatitis, ulcer and swollen poison; and Hyptis brevipes for asthma and malaria. OBJECTIVE: To characterize chemical compositions of the oils from three Hyptis species and evaluate their potential antimicrobial, radical scavenging activities and toxicities against brine shrimp. MATERIALS AND METHODS: The oils were obtained by hydrodistillation, and their chemical compositions were investigated by gas chromatography-mass spectrometry (GC-MS). Minimum inhibitory concentrations (MICs) were determined using the tube double-dilution technique. The antioxidant activities were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and toxicities by the brine shrimp bioassay. RESULTS: Forty-seven, 33 and 28 constituents of oils isolated, respectively, from H. suaveolens, H. rhomboidea and H. brevipes were identified. Among the essential oils, the strongest antioxidant activity was exhibited by H. brevipes with an SC50 value of 2.019 ± 0.25 µg mL⁻¹. The H. brevipes oil exhibited the strongest antimicrobial activity (3.125-6.25 µg mL⁻¹) on pathogens employed in the assay. They all showed significant toxicities with median lethal concentration (LC50) values of 62.2 ± 3.07 µg mL⁻¹, 65.9 ± 6.55 µg mL⁻¹ and 60.8 ± 9.04 µg mL⁻¹, respectively. DISCUSSION AND CONCLUSIONS: The three Hyptis species oils possess strong antimicrobial activities and toxicities. Hyptis rhomboidea and H. brevipes showed considerable antioxidant activity compared to the positive control.

Changes in the central nervous system in diabetic neuropathy.

One of the most common chronic complications arising from diabetes is diabetic peripheral neuropathy. Depending on research statistics, approximately half of the people who have diabetes will suffer from diabetic peripheral neuropathy over time, which manifests as abnormal sensations in the distal extremities, and about 25%-50% of these patients have symptoms of neuralgia, called painful diabetic neuropathy. These patients often exhibit adverse emotional conditions, like anxiety or depression, which can reduce their quality of life. The pathogenesis of diabetic peripheral neuropathy is complex, and although persistent hyperglycemia plays a central role in the development of diabetic peripheral neuropathy, strict glycemic control does not eliminate the risk of diabetic peripheral neuropathy. This suggests the need to understand the role of the central nervous system in the development of diabetic peripheral neuropathy to modulate treatment regimens accordingly. Magnetic resonance imaging not only allows for the noninvasive detection of structural and functional alterations in the central nervous system, but also provides insight into the processing of abnormal information such as pain by the central nervous system, and most importantly, contributes to the development of more effective pain relief protocols. Therefore, this article will focus on the mechanisms and related imaging evidence of central alterations in diabetic peripheral neuropathy, especially in painful diabetic neuropathy.

A synthetic arabinose-inducible promoter confers high levels of recombinant protein expression in hyperthermophilic archaeon Sulfolobus islandicus.

Despite major progresses in genetic studies of hyperthermophilic archaea, recombinant protein production in these organisms always suffers from low yields and a robust expression system is still in great demand. Here we report a versatile vector that confers high levels of protein expression in Sulfolobus islandicus, a hyperthermophilic crenarchaeon. Two expression vectors, pSeSD and pEXA, harboring 11 unique restriction sites were constructed. They contain coding sequences of two hexahistidine (6×His) peptide tags and those coding for two protease sites, the latter of which make it possible to remove the peptide tags from expressed recombinant proteins. While pEXA employed an araS promoter for protein expression, pSeSD utilized P(araS-SD), an araS derivative promoter carrying an engineered ribosome-binding site (RBS; a Shine-Dalgarno [SD] sequence). We found that P(araS-SD) directed high levels of target gene expression. More strikingly, N-terminal amino acid sequencing of recombinant proteins unraveled that the protein synthesized from pEXA-N-lacS lacked the designed 6×His tag and that translation initiation did not start at the ATG codon of the fusion gene. Instead, it started at multiple sites downstream of the 6×His codons. Intriguingly, inserting an RBS site upstream of the ATG codon regained the expression of the 6×His tag, as shown with pSeSD-N-lacS. These results have yielded novel insight into the archaeal translation mechanism. The crenarchaeon Sulfolobus can utilize N-terminal coding sequences of proteins to specify translation initiation in the absence of an RBS site.

A strong inorganic acid-initiated methacrylate polymerization strategy for room temperature preparation of monolithic columns for capillary electrochromatography.

A facile strong inorganic acid-initiated methacrylate polymerization strategy was developed for fabricating monolithic columns at room temperature. The prepared monoliths were characterized by FTIR spectrometry, mercury intrusion porosimeter and SEM, while their performance was evaluated by CEC for the separation of various types of compounds including alkyl benzenes, polycyclic aromatic hydrocarbons, nonsteroidal anti-inflammatory drugs, anilines, and nitrophenol isomers. The column-to-column and batch-to-batch reproducibility for the prepared monoliths in terms of the RSD of EOF flow velocity, retention factor, and the minimum plate height of naphthalene ranged from 3.4 to 12.4%. The fabricated monoliths gave excellent performance for the separation of the test neutral compounds with the theoretical plates of 170,000-232,000 plates per meter for thiourea, and 77,400-112,300 plates per meter for naphthalene. The proposed strong inorganic acid-initiated methacrylate polymerization strategy is a promising alternative for fabricating organic polymer-based monoliths.

Novel compound variants of the AR and MAP3K1 genes are related to the clinical heterogeneity of androgen insensitivity syndrome.

Androgen insensitivity syndrome (AIS; OMIM 300068) is the most frequent cause of 46, XY disorders of sex development (DSD). However, the correlation between genotype and phenotype has not been determined. We conducted a systematic analysis of the clinical characteristics, hormone levels, ultrasonography data and histopathology of a 46, XY Chinese patient with AIS. The family was followed up for nearly 8 years. We applied whole-exome sequencing (WES) for genetic analysis of the pedigree and performed bioinformatic analysis of the identified variants. Human embryonic kidney 293T/17 (HEK293T/17) cells were transiently transfected with wild-type or mutant AR and MAP3K1 plasmid. Cell lysates were used to analyze androgen receptor (AR) production. A novel hemizygous AR variant (c.2070C>A, p. His690Glu) and a rare heterozygous MAP3K1 variant (c.778C>T, p. Arg260Cys) were identified by WES in the proband and her mother. Bioinformatic analysis predicted these two variants to be pathogenic. Multiple amino acid sequence alignments showed that p. His690 and p. Arg260 are conserved among various species. His690Glu is a mutation that decreased the AR production, whereas the Arg260Cys mutation increased the AR production. The novel compound variants of the AR and MAP3K1 genes also increased the production of AR protein. Thus, the phenotype of the patient may be caused by defects in both the AR and MAP3K1 signaling pathways. Compound variants of the AR and MAP3K1 genes resulted in a specific phenotype in this patient with AIS. WES might reveal genetic variants that explain the heterogeneity of AIS.

Lipin1 Is Involved in the Pathogenesis of Diabetic Encephalopathy through the PKD/Limk/Cofilin Signaling Pathway.

Diabetic encephalopathy is a type of central diabetic neuropathy resulting from diabetes mainly manifested as cognitive impairments. However, its underlying pathogenesis and effective treatment strategies remain unclear. In the present study, we investigated the effect of Lipin1, a phosphatidic acid phosphatase enzyme, on the pathogenesis of diabetic encephalopathy. We found that in vitro, Lipin1 exerts protective effects on high glucose-induced reductions of PC12 cell viability, while in vivo, Lipin1 is downregulated within the CA1 hippocampal region in a type I diabetes rat model. Increased levels of Lipin1 within the CA1 region are accompanied with protective effects including amelioration of dendritic spine and synaptic deficiencies, phosphorylation of the synaptic plasticity-related proteins, LIM kinase 1 (p-limk1) and cofilin, as well as increases in the synthesis of diacylglycerol (DAG), and the expression of phosphorylated protein kinase D (p-PKD). These effects are associated with the rescue of cognitive disorders as shown in this rat model of diabetes. In contrast, knockdown of Lipin1 within the CA1 region enhanced neuronal abnormalities and the genesis of cognitive impairment in rats. These results suggest that Lipin1 may exert neuroprotective effects involving the PKD/Limk/Cofilin signaling pathway and may serve as a potential therapeutic target for diabetic encephalopathy.

Hydrofluoric acid etched stainless steel wire for solid-phase microextraction.

Stainless steel wire has been widely used as the substrate of solid-phase microextraction (SPME) fibers to overcome the shortcomings of conventional silica fibers such as fragility, by many researchers. However, in previous reports various sorbent coatings are always required in conjunction with the stainless steel wire for SPME. In this work, we report the bare stainless steel wire for SPME without the need for any additional coatings taking advantage of its high mechanical and thermal stability. To evaluate the performance of stainless steel wire for SPME, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, chlorobenzene, n-propylbenzene, aniline, phenol, n-hexane, n-octane, n-decane, n-undecane, n-dodecane, chloroform, trichloroethylene, n-octanol, and butanol were tested as analytes. Although the stainless steel wire had almost no extraction capability toward the tested analytes before etching, it did exhibit high affinity to the tested PAHs after etching with hydrofluoric acid. The etched stainless steel wire gave a much bigger enhancement factor (2541-3981) for the PAHs than the other analytes studied (< or = 515). Etching with hydrofluoric acid produced a porous and flower-like structure with Fe(2)O(3), FeF(3), Cr(2)O(3), and CrF(2) on the surface of the stainless steel wire, giving high affinity to the PAHs due to cation-pi interaction. On the basis of the high selectivity of the etched stainless steel wire for PAHs, a new SPME method was developed for gas chromatography with flame ionization detection to determine PAHs with the detection limits of 0.24-0.63 microg L(-1). The precision for six replicate extractions using one SPME fiber ranged from 2.9% to 5.3%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 4.3-8.8%. One etched stainless steel wire can stand over 250 cycles of SPME without significant loss of extraction efficiency. The developed etched stainless steel wire is very stable, highly selective, and reproducible for the SPME of PAHs.

In situ hydrothermal growth of metal-organic framework 199 films on stainless steel fibers for solid-phase microextraction of gaseous benzene homologues.

Metal-organic frameworks (MOFs) have received great attention due to their fascinating structures and intriguing potential applications in various fields. Herein, we report the first example of the utilization of MOFs for solid-phase microextraction (SPME). MOF-199 with unique pores and open metal sites (Lewis acid sites) was employed as the coating for SPME fiber to extract volatile and harmful benzene homologues. The SPME fiber was fabricated by in situ hydrothermal growth of thin MOF-199 films on etched stainless steel wire. The MOF-199-coated fiber not only offered large enhancement factors from 19,613 (benzene) to 110,860 (p-xylene), but also exhibited wide linearity with 3 orders of magnitude for the tested benzene homologues. The limits of detection for the benzene homologues were 8.3-23.3 ng L(-1). The relative standard deviation (RSD) for six replicate extractions using one SPME fiber ranged from 2.0% to 7.7%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 3.5%-9.4% (RSD). Indoor air samples were analyzed for the benzene homologues using the SPME with the MOF-199-coated fiber in combination with gas chromatography-flame ionization detection. The recoveries for the spiked benzene homologues in the collected indoor air samples were in the range of 87%-106%. The high affinity of the MOF-199-coated fiber to benzene homologues resulted from the combined effects of the large surface area and the unique porous structure of the MOF-199, the pi-pi interactions of the aromatic rings of the analytes with the framework 1,3,5-benzenetricarboxylic acid molecules, and the pi-complexation of the electron-rich analytes to the Lewis acid sites in the pores of MOF-199.

Abnormal Glucose Metabolism and Insulin Resistance Are Induced via the IRE1α/XBP-1 Pathway in Subclinical Hypothyroidism.

Subclinical hypothyroidism (SCH) and diabetes mellitus are closely related and often occur together in individuals. However, the underlying mechanism of this association is still uncertain. In this study we re-analyzed the data of a mature database (NHANES, 1999 ~ 2002) and found that both fasting plasma glucose levels and the proportion of hyperglycemic subjects among SCH patients were higher than that found in euthyroid controls. SCH was also associated with a 2.29-fold increased risk for diabetes. Subsequently, we established an SCH mouse model and subjected it to an oral glucose tolerance test (OGTT) and an insulin tolerance test (ITT). SCH mice exhibited impaired glucose and insulin tolerance. Increased HOMA-IR and decreased ISI indexes, indicating insulin resistance (IR), were also observed in the SCH state. Hepatic ERp29 and Bip, as well as IRE1α and XBP-1s, were induced significantly in SCH mice, suggesting the induction of endoplasmic reticulum (ER) stress, particularly involving the IRE1α/XBP-1s pathway. Interestingly, when we relieved ER stress using 4-phenyl butyric acid, abnormal glucose metabolism, and IR status in SCH mice were improved. Our findings suggest that ER stress, predominantly involving the IRE1α/XBP-1s pathway, may play a pivotal role in abnormal glucose metabolism and IR in SCH that may help develop potential strategies for the prevention and treatment of diabetes.

A capillary electrophoresis assay for recombinant Bacillus subtilis protoporphyrinogen oxidase.

Protoporphyrinogen oxidase (PPO) is a flavin adenine dinucleotide (FAD)-containing enzyme in the tetrapyrrole biosynthetic pathway that leads to the formation of both heme and chlorophylls, which has been identified as one of the most important action targets of commercial herbicides. The literature reports gave different PPO-catalytic kinetic parameters for the substrate protoporphyrinogen IX (K(m) of 0.1 to 10.4 miocroM) with different sources of PPO using fluorescent or HPLC methods. Herein we assayed the enzymatic activity of recombinant Bacillus subtilis PPO by using capillary electrophoresis (CE), a method with high separation efficiency, easy automation, and low sample consumption. The Michaelis constant and maximum reaction velocity were determined as 7.0+/-0.6 miocroM and 0.38+/-0.02 miocromol min(-1)miocrog(-1), respectively. The interaction between PPO and acifluorfen, a commercial PPO-inhibiting herbicide, was measured as the inhibition constant 186.9+/-9.3 miocroM EM, Cyrillic. The relationship between cofactor FAD and PPO activity can also be quantitatively studied by this CE method. The CE method used here should also be a convenient, reliable method for PPO study.

Multiwalled carbon nanotubes coated fibers for solid-phase microextraction of polybrominated diphenyl ethers in water and milk samples before gas chromatography with electron-capture detection.

Determination of polybrominated diphenyl ethers (PBDEs) in environmental samples has raised great concerns due to the widespread use of PBDEs and their potential risk to humans. Solid-phase microextraction (SPME) is a fast, simple, cost-effective, and green sample preparation technique and is widely used for environmental analysis, but reports on the application of SPME for determination of PBDEs are very limited, and only a few publications dealing with commercial SPME fibers are available for extraction of PBDEs. Herein, we report a novel SPME method using multiwalled carbon nanotubes (MWCNTs) as the SPME fiber coating for gas chromatography with electron-capture detection (GC-ECD) of PBDEs in environmental samples. The MWCNTs coating gave much higher enhancement factors (616-1756) than poly (5% dibenzene-95% dimethylsiloxane) coating (139-384) and activated carbon coating (193-423). Thirty-minute extraction of 10 mL of sample solution using the MWCNTs coated fiber for GC-ECD determination yielded the limits of detection of 3.6-8.6 ng L(-1) and exhibited good linearity of the calibration functions (r(2)>0.995). The precision (RSD%, n=4) for peak area and retention time at the 500 ng L(-1) level was 6.9-8.8% and 0.6-0.9%, respectively. The developed method was successfully applied for the analysis of real samples including local river water, wastewater, and milk samples. The recovery of the PBDEs at 500 ng L(-1) spiked in these samples ranged from 90 to 119%. No PBDEs were detected in the river water and skimmed milk samples, whereas in the wastewater sample, 134-215 ng L(-1) of PBDEs were found. The PBDEs were detected in all whole fat milk samples, ranging from 13 to 484 ng L(-1). In a semiskimmed milk sample, only BDE-47 was found at 21 ng L(-1).

Thyroid-stimulating hormone inhibits adipose triglyceride lipase in 3T3-L1 adipocytes through the PKA pathway.

Thyroid-stimulating hormone (TSH) has been shown to play an important role in the regulation of triglyceride (TG) metabolism in adipose tissue. Adipose triglyceride lipase (ATGL) is a rate-limiting enzyme controlling the hydrolysis of TG. Thus far, it is unclear whether TSH has a direct effect on the expression of ATGL. Because TSH function is mediated through the TSH receptor (TSHR), TSHR knockout mice (Tshr-/- mice) (supplemented with thyroxine) were used in this study to determine the effects of TSHR deletion on ATGL expression. These effects were verified in 3T3-L1 adipocytes and potential underlying mechanisms were explored. In the Tshr-/- mice, ATGL expression in epididymal adipose tissue was significantly increased compared with that in Tshr+/+ mice. ATGL expression was observed to increase with the differentiation process of 3T3-L1 preadipocytes. In mature 3T3-L1 adipocytes, TSH significantly suppressed ATGL expression at both the protein and mRNA levels in a dose-dependent manner. Forskolin, which is an activator of adenylate cyclase, suppressed the expression of ATGL in 3T3-L1 adipocytes. The inhibitory effects of TSH on ATGL expression were abolished by H89, which is a protein kinase A (PKA) inhibitor. These results indicate that TSH has an inhibitory effect on ATGL expression in mature adipocytes. The associated mechanism is related to PKA activation.

Thyrotropin and obesity: increased adipose triglyceride content through glycerol-3-phosphate acyltransferase 3.

Epidemiological evidence indicates that thyrotropin (TSH) is positively correlated with the severity of obesity. However, the mechanism remains unclear. Here, we show that TSH promoted triglyceride (TG) synthesis in differentiated adipocytes in a thyroid hormone-independent manner. Mice with subclinical hypothyroidism, which is characterized by elevated serum TSH but not thyroid hormone levels, demonstrated a 35% increase in the total white adipose mass compared with their wild-type littermates. Interestingly, Tshr KO mice, which had normal thyroid hormone levels after thyroid hormone supplementation, resisted high-fat diet-induced obesity. TSH could directly induce the activity of glycerol-3-phosphate-acyltransferase 3 (GPAT3), the rate-limiting enzyme in TG synthesis, in differentiated 3T3-L1 adipocytes. However, following either the knockdown of Tshr and PPARγ or the constitutive activation of AMPK, the changes to TSH-triggered GPAT3 activity and adipogenesis disappeared. The over-expression of PPARγ or the expression of an AMPK dominant negative mutant reversed the TSH-induced changes. Thus, TSH acted as a previously unrecognized master regulator of adipogenesis, indicating that modification of the AMPK/PPARγ/GPAT3 axis via the TSH receptor might serve as a potential therapeutic target for obesity.

On-line coupling of flow injection displacement sorption preconcentration to high-performance liquid chromatography for speciation analysis of mercury in seafood.

A simple and cost-effective method for speciation analysis of trace mercury in seafood was developed by on-line coupling flow injection microcolumn displacement sorption preconcentration to high-performance liquid chromatography (HPLC) with UV detection. The methodology involved the presorption of the Cu-PDC (pyrrolidine dithiocarbamate) chelate onto a microcolumn packed with a cigarette filter sorbent, simultaneous preconcentration of Hg(II), methylmercury (MeHg), ethylmercury (EtHg), and phenylmercury (PhHg) onto the microcolumn through a displacement reaction with the presorbed Cu-PDC, and their subsequent elution from the microcolumn for on-line HPLC separation. Interferences from heavy metal ions with lower stability of their PDC chelates relative to Cu-PDC were minimized without the need of any masking agents. With the consumption of 4.0 ml of sample solution, the enrichment factors were about 80. The detection limits were 10-25 ng g(-1) (as Hg) in fresh tissue. Precision (R.S.D. (%), n = 5) ranged from 2 to 3% at the 500 microg l(-1) (as Hg) level. The developed technique was validated by analyzing a certified reference material (DORM-2, dogfish-muscle), and was shown to be useful for mercury speciation in real seafood samples.