Combined toxicity of heavy metal mixtures in liver cells.

With rapid industrialization, China is now facing great challenges in heavy metal contamination in the environment. Human exposure to heavy metals through air, water and food commonly involves a mixture consisting of multiple heavy metals. In this study, eight common heavy metals (Pb, Cd, Hg, Cu, Zn, Mn, Cr, Ni) that cause environmental contamination were selected to investigate the combined toxicity of different heavy metal mixtures in HL7702 cells. Toxicity (24 h LC50 ) of each individual metal on the cells ranked Hg > Cr = Cd > Cu > Zn > Ni > Mn > Pb; toxicity of the different mixtures ranked: M5 > M3PbHgCd > M5+Mn > M5+Cu > M2CdNi > M4A > M8-Mn > M8 > M5+Zn > M4B > M8-Cr > M8-Zn > M8-Cu > M8-Pb > M8-Cd > M8-Hg > M8-Ni > M3PbHgNi > M3CuZnMn. The cytotoxicity data of individual metals were successfully used to build the additive models of two- to eight-component metal mixtures. The comparison between additive model and combination model or partly additive model was useful to evaluate the combined effects in mixture. Synergistic, antagonistic or additive effects of the toxicity were observed in different mixtures. These results suggest that the combined effects should be considered in the risk assessment of heavy metal co-exposure, and more comprehensive investigations on the combined effects of different heavy metal mixtures are needed in the future. Copyright © 2016 John Wiley & Sons, Ltd.

Time-dependent changes in glucose and insulin regulation during intermittent hypoxia and continuous hypoxia.

Hypoxia manifests in many forms including the short repetitive intermittent hypoxia (IH) of sleep apnoea and the continuous hypoxia (CH) of altitude, both of which may impact metabolic function. Based on our own previous studies and the available literature, we hypothesized that whereas acute exposure to IH and CH would lead to comparable metabolic dysfunction, with longer-term exposure, metabolism would normalize to a greater extent with CH than IH. Studies were conducted in lean C57BL/6J mice exposed to either IH or CH for 1 day or 4 weeks and compared to either intermittent air (IA) or unhandled (UN) controls, respectively. We utilized the frequently sampled intravenous glucose tolerance test and minimal model analyses to determine insulin-dependent (insulin sensitivity; S (I)) and insulin-independent (glucose effectiveness; S (g)) glucose disposal, as well as the insulin response to glucose (acute insulin response to glucose; AIR(g)). Our data show that 1-day exposure impaired the glucose tolerance and caused reductions in S (g) and AIR(g) in both the IH and CH groups, but only IH caused a significant decrease in S (I) (7.5 ± 2.7 vs. 17.0 ± 5.3 µU ml(-1) min(-1); p < 0.05). After 4-week exposure, there was evidence of metabolic adaptation in both hypoxic groups, however, in the CH group, there was a supranormal increase in S (I) relative to both UN and IH groups. We conclude that in lean mice, the marked metabolic dysfunction that occurs with acute exposure to hypoxia is reversed to a greater extent with chronic CH exposure than chronic IH exposure.

Liver-specific ß-catenin knockout mice have bile canalicular abnormalities, bile secretory defect, and intrahepatic cholestasis.

UNLABELLED: Beta-catenin plays important roles in liver physiology and hepatocarcinogenesis. While studying the role of ß-catenin in diet-induced steatohepatitis, we recently found that liver-specific ß-catenin knockout (KO) mice exhibit intrahepatic cholestasis. This study was undertaken to further characterize the role of ß-catenin in biliary physiology. KO mice and wild-type (WT) littermates were fed standard chow or a diet supplemented with 0.5% cholic acid for 2 weeks. Chow-fed KO mice had higher serum and hepatic total bile acid levels and lower bile flow rate than WT mice. Expression levels of bile acid biosynthetic genes were lower and levels of major bile acid exporters were similar, which therefore could not explain the KO phenotype. Despite loss of the tight junction protein claudin-2, KO mice had preserved functional integrity of tight junctions. KO mice had bile canalicular morphologic abnormalities as evidenced by staining for F-actin and zona occludens 1. Electron microscopy revealed dilated and tortuous bile canaliculi in KO livers along with decreased canalicular and sinusoidal microvilli. KO mice on a cholic acid diet had higher hepatic and serum bile acid levels, bile ductular reaction, increased pericellular fibrosis, and dilated, misshapen bile canaliculi. Compensatory changes in expression levels of several bile acid transporters and regulatory genes were found in KO livers. CONCLUSION: Liver-specific loss of ß-catenin leads to defective bile canalicular morphology, bile secretory defect, and intrahepatic cholestasis. Thus, our results establish a critical role for ß-catenin in biliary physiology.

Joint Toxicity of a Multi-Heavy Metal Mixture and Chemoprevention in Sprague Dawley Rats.

To explore the joint toxicity and bio-accumulation of multi-heavy metals and potential chemoprevention strategies, Male Sprague Dawley (SD) rats (n = 30) were treated orally once a week for six months with 500mg/kg•bw of eight heavy metals which were commonly identified in aquatic products in the Ningbo area including chromium, manganese, nickel, copper, zinc, cadmium, mercury, and lead. At the same time, 200mg/kg•bw of epigallocatechin-3-gallate (EGCG), trisodium citrate dihydrate (TCD) or glutathione (GSH) were administered to evaluate their antagonistic effects against adverse effects of multi-heavy metal mixture. The Morris water maze test was used to evaluate spatial learning and memory in the treated rats. Then the rats were anesthetized by pentobarbital sodium (40 mg/kg•bw) to obtain blood samples for biochemical analysis and organs (heart, liver, spleen, lungs, kidneys, brain, testis) to be conducted for biopsy and organ coefficients. Inductively coupled plasma mass spectrometer (ICP-MS) was used to analyze the concentrations of heavy metals. Results indicated that six months of exposure to a multi-heavy metal mixture under this experimental dosage resulted in accumulation in organs and adverse effects on the blood, reproductive system, and liver function. EGCG, TCD or GSH all showed certain chemoprevention effects against the joint toxicity induced by the multi-heavy metal mixture and indicated alleviation and the potential mechanism that also included the promotion of excretion of metals to which animals were exposed.

CaMKIV regulates mitochondrial dynamics during sepsis.

Sepsis and shock states impose mitochondrial stress, and in response, adaptive mechanisms such as fission, fusion and mitophagy are induced to eliminate damaged portions of or entire dysfunctional mitochondria. The mechanisms underlying these events are being elucidated; yet a direct link between loss of mitochondrial membrane potential ΔΨm and the initiation of fission, fusion and mitophagy remains to be well characterized. The direct association between the magnitude of the ΔΨm and the capacity for mitochondria to buffer Ca2+ renders Ca2+ uniquely suited as the signal engaging these mechanisms in circumstances of mitochondrial stress that lower the ΔΨm. Herein, we show that the calcium/calmodulin-dependent protein kinase (CaMK) IV mediates an adaptive slowing in oxidative respiration that minimizes oxidative stress in the kidneys of mice subjected to either cecal ligation and puncture (CLP) sepsis or endotoxemia. CaMKIV shifts the balance towards mitochondrial fission and away from fusion by 1) directly phosphorylating an activating Serine616 on the fission protein DRP1 and 2) reducing the expression of the fusion proteins Mfn1/2 and OPA-1. CaMKIV, through its function as a direct PINK1 kinase and regulator of Parkin expression, also enables mitophagy. These data support that CaMKIV serves as a keystone linking mitochondrial stress with the adaptive mechanisms of mitochondrial fission, fusion and mitophagy that mitigate oxidative stress in the kidneys of mice responding to sepsis.

Frontline Science: Rev-Erbα links blue light with enhanced bacterial clearance and improved survival in murine Klebsiella pneumoniae pneumonia.

The wavelength of light is a critical determinant of light's capacity to entrain adaptive biological mechanisms, such as enhanced immune surveillance, that precede and prepare us for the active circadian day, a time when the risk of encountering pathogen is highest. Light rich in the shorter wavelength visible blue spectrum maximally entrains these circadian rhythms. We hypothesized that exposure to blue light during sepsis will augment immunity and improve outcome. Using a clinically relevant Klebsiella pneumoniae acute lower respiratory tract infection model, we show that blue spectrum light shifts autonomic tone toward parasympathetic predominance and enhances immune competence, as characterized by accelerated pathogen clearance that is accompanied by reduced alveolar neutrophil influx, inflammation, and improved survival. Blue light functioned through an optic-cholinergic pathway and expansion of splenic Ccr2+ monocytes to increase control of the infection and improve survival. The "keystone" mediating these effects is the circadian clock protein Rev-Erbα, and biochemical activation with Rev-Erbα agonist SR9009 enhanced mononuclear cell phagocytosis in vitro and recapitulated the enhanced pathogen elimination in vivo observed with blue light. These findings underscore the potential therapeutic value of blue light and modulating Rev-Erbα to enhance host immunity against infection.

Hyperinsulinemia predicts survival in a hyperglycemic mouse model of critical illness.

OBJECTIVES: : The mechanisms by which correcting hyperglycemia with exogenous insulin improves mortality and morbidity in critically ill patients remain unclear. We designed this study to test the hypothesis that relative endogenous insulin deficiency is associated with adverse outcomes in critical illness related to hyperglycemia. DESIGN: : Prospective controlled animal study. SETTING: : University research laboratory. SUBJECTS: : Male C57BL/6J mice, 8-12 wks old. INTERVENTIONS: : Spontaneously breathing mice were instrumented with chronic indwelling arterial and venous catheters. After a postoperative recovery period, endotoxemia was initiated with intra-arterial lipopolysaccharide (1 mg/kg) in the presence of dextrose infusion (100 microL/hr). Insulin secretion was blocked with diazoxide (2.5-30 mg/kg/day). Mice were monitored continuously for 48 hrs with blood sampled serially for blood glucose and plasma insulin determinations. MEASUREMENTS AND MAIN RESULTS: : In both saline- and glucose-infused mice, lipopolysaccharide administration induced transient hemodynamic instability without significant impact on mortality. In the saline-infused group, lipopolysaccharide administration caused a transient reduction in blood glucose and in circulating insulin. However, in glucose-infused mice, lipopolysaccharide induced a large and unexpected increase in circulating insulin without significant alteration in blood glucose. Blockade of insulin secretion in response to lipopolysaccharide in the presence of exogenous glucose precipitated marked hyperglycemia and resulted in >90% mortality. In a subanalysis of animals matched for the degree of hyperglycemia, nonsurvivors had markedly lower insulin levels compared with survivors (3.5 +/- 0.8 ng/dL vs. 9.3 +/- 1.4 ng/dL; p < .004). CONCLUSIONS: : Endogenous insulin deficiency in the face of hyperglycemia is associated with mortality in a mouse model of lipopolysaccharide-induced critical illness.

Dynamic arterial blood gas analysis in conscious, unrestrained C57BL/6J mice during exposure to intermittent hypoxia.

Rodent models of chronic intermittent hypoxia (IH) are commonly used to investigate the pathophysiological sequelae that result from hypoxic exposure in patients experiencing obstructive sleep apnea (OSA). Despite the widespread use of IH models, little attention has been paid to carefully defining the degree of oxyhemoglobin desaturation that occurs during each hypoxic period. Therefore, we developed a rapid blood sampling technique to determine the arterial blood gas changes that occur in conscious unrestrained mice during a single IH event and hypothesized that the arterial Po(2) (Pa(O(2))) at the nadir level of the inspired oxygen profile causes oxyhemoglobin saturation to fall to between 80% and 90%. Mice were exposed to 120-180 cycles of IH at a rate of 60 cycles/h, and arterial blood samples were withdrawn (<3 s) at baseline and at 10-s time intervals over the course of a single IH cycle. The IH regimen caused a decline in the fraction of inspired oxygen from room air levels to a transient nadir of 6.0 +/- 0.2% over the 30-s hypoxic period. The Pa(O(2)) and arterial oxyhemoglobin saturation reached a nadir of 47 +/- 2 mmHg and 85 +/- 2% at 30 s, respectively. Arterial Pco(2) decreased to a nadir of 26 +/- 2 mmHg at 30 s, associated with a rise in arterial pH to 7.46 +/- 0.2. We conclude that the magnitude of oxyhemoglobin desaturation that is induced in our murine model of IH is consistent with the degree of hypoxic stress that occurs in moderate to severe clinical OSA.

Leptin signalling reduces the severity of cardiac dysfunction and remodelling after chronic ischaemic injury.

AIMS: Leptin is elevated under conditions of both obesity and heart failure (HF), and activation of leptin receptor (ObR) signalling is known to increase in vivo cardiac contractility and to have anti-hypertrophic effects on the left ventricle (LV). However, it is unknown whether ObR signalling is altered in cardiomyocytes after myocardial infarction (MI) leading to HF, or if a deficiency in ObR signalling leads to worse HF. METHODS AND RESULTS: In separate experimental protocols, C57BL/6J and leptin-deficient (ob/ob) mice underwent open-chest surgery to induce permanent left coronary artery ligation (CAL) or had a sham operation. Subgroups of ob/ob mice examined were lean (food-restricted), obese (food-ad libitum), and leptin repleted. Four weeks post-surgery, cardiac structure and function was examined by echocardiography, and the activation of cardiac leptin signalling was characterized through quantitative PCR, western blotting, and DNA-binding activities. CAL produced echocardiographic evidence of HF in C57BL/6J mice, elevated circulating leptin, increased cardiomyocyte leptin and ObR expression, and activated myocardial signal transducer and activator of transcription-3 (STAT3). In leptin-deficient ob/ob mice, whether lean or obese, CAL caused increased hypertrophy and dilation, decreased contractility of the LV, and worsened survival relative to wildtype or leptin-repleted mice after CAL. In ob/ob mice, activation of cardiac STAT3 signalling after CAL is enhanced in the presence of leptin and parallels the induction of the STAT3-responsive genes, tissue-inhibitor of metalloproteinase-1 and heat shock protein-70. CONCLUSION: These data demonstrate that HF increases ObR signalling in cardiomyocytes and that activation of ObR signalling improves functional outcomes in chronic ischaemic injury leading to HF.

In vitro combination characterization of the new anticancer plant drug beta-elemene with taxanes against human lung carcinoma.

Beta-elemene has recently raised interest in P.R. China as a novel antitumor plant drug isolated from the Chinese medicinal herb Zedoary. To explore potentially useful combinations of beta-elemene with taxanes in the clinic, we characterized the effects of beta-elemene combined with taxanes in human lung cancer cells using a median effect analysis, micronucleus assay, apoptotic detection, and determination of gene expression in the signaling pathways of apoptosis. The synergistic analysis indicated that the interactions of beta-elemene with paclitaxel or docetaxel ranged from slight synergism to synergism. Combinations of beta-elemene with docetaxel induced much stronger synergistic interactions in p53 mutant H23 cells and p53 null H358 cells than in p53 wild-type H460 and A549 cells. Similar synergistic interactions were observed by micronucleus assay, apoptotic detection, and determination of apoptotic gene expression. Our findings indicate that the synergistic effects achieved with combinations of beta-elemene and taxanes are related to the augmented cytotoxic efficacy of taxanes owing to the action of beta-elemene. In H460 and A549 cells, dose-dependent upregulation of p53 protein expression was observed in cultures treated with docetaxel alone and with docetaxel plus beta-elemene, whereas no significant change in p53 expression was observed in any of the treatment groups in H23 cells. Fas revealed no alteration of expression with any of the treatments in this study. However, the combination treatments induced increased cytochrome c release from mitochondria, significant caspase-8 and -3 cleavage, and downregulation of Bcl-2 and Bcl-XL expression. These results suggest that, although p53 plays an important role in taxane-induced cell death, apoptosis induced by beta-elemene or in combination with docetaxel thereof seems to be initiated through a p53- and Fas-independent pathway via mitochondria in our lung cancer cells. The suppression of specific 'survival' gene expression appears to be the key action leading to the synergistic effect of combination treatments with beta-elemene and taxanes. Finally, the beta-elemene-induced alteration of cell membrane permeability, which has potential to result in enhanced cellular uptake of taxanes, may also contribute to the synergistic interactions of the combination treatments.

Protection by nitrite against the ischemic effects induced by acute myocardial infarction in mice.

OBJECTIVE: This research was aimed to investigate the correct dose of nitrite that would act as a protection against the ischemic effects induced by acute myocardial infarction (AMI). METHODS: Mice were randomly divided into a sham-operation group (sham), an AMI operation group (AMI), and a nitrite pretreatment+AMI operation group (N+AMI). Seven days before the AMI operation, mice in the N+AMI group were pretreated with sodium nitrite in drinking water. RESULTS: One week after the AMI operation, serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities in both AMI and N+AMI group were significantly higher than those in the sham group, but there were no significant differences between AMI and N+AMI mice. Contents of inducible nitric oxide synthase (iNOS) in the noninfarct area of the left ventricle in the N+AMI mice were significantly higher than those in the AMI mice, with no difference in the infarct area. Coagulation necrosis in the cardiomyocytes was observed in both AMI and N+AMI mice; however, it was less severe in the N+AMI mice. Western blot analyses showed that nitrite pretreatment resulted in up-regulation of antiapoptotic factors Bcl-2 and p21waf1/cip1 signal proteins, but down-regulation of the proapoptotic factor Bax signal protein. Furthermore, nitrite pretreatment also showed significant alleviation of AMI-induced signal protein expressions of inflammatory factors of NF-K B and oxidative factors of Hsp 70 and HO-1. CONCLUSION: These results suggest that nitrite show certain protective effects against the ischemic effects induced by AMI in mice, which might be attributed to the synthesis of NO induced by iNOS through up-regulation of antiapoptotic factors and down-regulation of proapoptotic and inflammatory factors.

Joint Toxicity of Different Heavy Metal Mixtures after a Short-Term Oral Repeated-Administration in Rats.

The systemic toxicity of different combinations of heavy metal mixtures (HMMs) was studied according to equivalent proportions of the eight most common detectable heavy metals found in fish consumption in the Ningbo area of China. The ion mass proportions of Zn, Cu, Mn, Cr, Ni, Cd, Pb, and Hg were 1070.0, 312.6, 173.1, 82.6, 30.0, 13.3, 6.6, and 1.0, respectively. In this study, 10 experimental groups were set as follows: M8 (Pb + Cd + Hg + Ni + Cu + Zn + Mn + Cr); M5 (Pb + Cd + Hg + Ni + Cr); M4A (Pb + Cd + Hg + Ni); M4B (Cu + Zn + Mn + Cr); M3 (Cu + Zn + Mn); Cr; Cu; Zn; Mn; and control. Sprague Dawley (SD) rats were orally treated with a single dose of each group every three days (10 times in total) for 34 days. After Morris water maze test, blood and tissue samples were collected to obtain biochemical, histopathological and western blot analysis. Results show abnormalities could be observed in different treatment groups, the M4B combination had the most significant change compared to all other groups. In conclusion, combination HMMs may have adverse effects on the hematologic, hepatic, renal and neurobehavioral function, and may also disturb electrolyte and lipid balance. Why M4B combination generated much higher toxic effects than any other combination mixtures or individual heavy metal needs to be further evaluated.

Mechanism of N-acetyl-cysteine inhibition on the cytotoxicity induced by titanium dioxide nanoparticles in JB6 cells transfected with activator protein-1.

The present study investigated the mechanism of N-acetyl-cysteine (NAC) inhibition on the cytotoxicity induced by titanium dioxide (TiO2) nanoparticles (NPs) using murine epidermal JB6 cells transfected with activator protein-1 (AP-1), JB6-AP-1 cells. Confocal microscopy was performed to localize TiO2 NPs in cultured cells. The level of reactive oxygen species (ROS) present in cells was evaluated by staining with 2',7'-dichlorodihydrofluorescein diacetate and dihydroethidium. AP-1 gene expression levels in the cells were detected using the luciferase assay. Confocal microscopy indicated that TiO2 NPs passed through the cell membrane into the cytoplasm; however, they did not penetrate the nuclear membrane. The present findings indicated that NAC markedly inhibited ROS generation and significantly inhibited cytotoxicity (P<0.05) induced by TiO2 NPs. Furthermore, alternative studies have demonstrated that AP-1 luciferase activity induced by TiO2 NPs may be significantly inhibited by NAC. In conclusion, the ability for NAC to inhibit the cytotoxicity induced by TiO2 NPs may primarily occur by blocking ROS generation in the cultured cells.

Combined toxicity and underlying mechanisms of a mixture of eight heavy metals.

With the rapid development of modernization and industrialization in China, a large quantity of heavy metals, including zinc, copper, lead, cadmium and mercury, have been entering the atmosphere, soil and water, the latter being the primary route of pollution. In the present study, in vitro experiments were performed to examine the joint toxicity and the underlying mechanisms of the eight most common heavy metals contaminating offshore waters on the eastern coast of Ningbo region. Using a cell cycle assay, cell apoptosis and reactive oxygen species (ROS) detection methods, the present study demonstrated that the heavy metal mixture arrested JB6 cells at the S phase, induced the generation of ROS and cell apoptosis. A luciferase assay indicated that the levels of activator protein­1 and nuclear factor­κB transcription factors were upregulated. Upregulation of the protein levels of C­jun and p65 were detected in the JB6 cells by western blot analysis; these two genes have important roles in cell carcinogenesis. These results provide a useful reference for further investigations on the combined toxicity of the exposure to multiple heavy metals.

Inhibition of Nickel Nanoparticles-Induced Toxicity by Epigallocatechin-3-Gallate in JB6 Cells May Be through Down-Regulation of the MAPK Signaling Pathways.

With the rapid development in nanotechnology, nickel nanoparticles (Ni NPs) have emerged in the application of nanomedicine in recent years. However, the potential adverse health effects of Ni NPs are unclear. In this study, we examined the inhibition effects of epigallocatechin-3-gallate (EGCG) on the toxicity induced by Ni NPs in mouse epidermal cell line (JB6 cell). MTT assay showed that Ni NPs induced cytotoxicity in a dose-dependent manner while EGCG exerted a certain inhibition on the toxicity. Additionally, EGCG could reduce the apoptotic cell number and the level of reactive oxygen species (ROS) in JB6 cells induced by Ni NPs. Furthermore, we observed that EGCG could down-regulate Ni NPs-induced activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) activation in JB6 cells, which has been shown to play pivotal roles in tumor initiation, promotion and progression. Western blot indicated that EGCG could alleviate the toxicity of Ni NPs through regulating protein changes in MAPK signaling pathways. In summary, our results suggest that careful evaluation on the potential health effects of Ni NPs is necessary before being widely used in the field of nanomedicine. Inhibition of EGCG on Ni NPs-induced cytotoxicity in JB6 cells may be through the MAPK signaling pathways suggesting that EGCG might be useful in preventing the toxicity of Ni NPs.

Correction: Inhibition of Nickel Nanoparticles-Induced Toxicity by Epigallocatechin-3-Gallate in JB6 Cells May Be through Down-Regulation of the MAPK Signaling Pathways.

[This corrects the article DOI: 10.1371/journal.pone.0150954.].

In vitro and in vivo evaluation of the toxicities induced by metallic nickel nano and fine particles.

Nickel nanoparticles (Ni NPs) have been applied in various fields along with the rapid development of nanotechnology. However, the potential adverse health effects of the Ni NPs are unclear. To investigate the cyto- and genotoxicity and compare the differences between the Ni NPs and the nickel fine particles (Ni FPs), Sprague-Dawley (SD) rats and A549 cells were treated with different doses of Ni NPs or FPs. Intra-tracheal instillation of Ni NPs and FPs caused acute toxicity in the lungs, liver and kidneys of the SD rats. Even though the histology of the lungs showed hyperplastic changes and the protein expression of HO-1 and Nrf2 detected by western blot showed lung burden overload, no significant increase was observed to the expression level of oncoprotein C-myc. The results from cell titer-Glo assay and comet assay indicated that Ni NPs were more potent in causing cell toxicity and genotoxicity in vitro than Ni FPs. In addition, Ni NPs increased the expression of C-myc in vitro, but these increases may not have been due to oxidative stress since no significant dose-dependent changes were seen in HO-1 and Nrf2 expressions. Although Ni NPs have the potential to cause DNA damage in A549 cells in vitro, the molecular mechanisms that led to these changes and their tumorigenic potential is still debatable. In short, Ni NPs were more potent in causing cell toxicity and genotoxicity in vitro than Ni FPs, and intra-tracheal instillation of Ni NPs and FPs caused toxicity in organs of the SD rats, while it showed similar to the effects for both particle types. These results suggested that both Ni NPs and FPs have the potential to be harmful to human health, and Ni NPs may have higher cyto- and genotoxic effects than Ni FPs under the same treatment dose.

Glucose Induces Mouse ß-Cell Proliferation via IRS2, MTOR, and Cyclin D2 but Not the Insulin Receptor.

An important goal in diabetes research is to understand the processes that trigger endogenous ß-cell proliferation. Hyperglycemia induces ß-cell replication, but the mechanism remains debated. A prime candidate is insulin, which acts locally through the insulin receptor. Having previously developed an in vivo mouse hyperglycemia model, we tested whether glucose induces ß-cell proliferation through insulin signaling. By using mice lacking insulin signaling intermediate insulin receptor substrate 2 (IRS2), we confirmed that hyperglycemia-induced ß-cell proliferation requires IRS2 both in vivo and ex vivo. Of note, insulin receptor activation was not required for glucose-induced proliferation, and insulin itself was not sufficient to drive replication. Glucose and insulin caused similar acute signaling in mouse islets, but chronic signaling differed markedly, with mammalian target of rapamycin (MTOR) and extracellular signal-related kinase (ERK) activation by glucose and AKT activation by insulin. MTOR but not ERK activation was required for glucose-induced proliferation. Cyclin D2 was necessary for glucose-induced ß-cell proliferation. Cyclin D2 expression was reduced when either IRS2 or MTOR signaling was lost, and restoring cyclin D2 expression rescued the proliferation defect. Human islets shared many of these regulatory pathways. Taken together, these results support a model in which IRS2, MTOR, and cyclin D2, but not the insulin receptor, mediate glucose-induced proliferation.

Association between the Hygiene Index Values of Live Fresh Aquatic Products and Food-Borne Diarrhea in the Population of the Ningbo Area in China.

To investigate the association of the hygiene index values of live fresh aquatic products and food-borne diarrhea in the population of the Ningbo area in China. Volatile basic nitrogen (VBN), histamine (HIS), indole, tetrodotoxin (TTX), and paralytic, neurotoxic, amnesic and diarrhetic shellfish poisons (PSP, NSP, ASP, and DSP, respectively) in the samples of live fresh aquatic products and food-borne diarrhea cases in six studied districts were analyzed. Results indicate that the incidence rate of food-borne diarrhea is related to the hygiene index values. Aside from VBN, the main risk factors related to food-borne diarrhea in edible aquatic products include DSP (in marine fish, shrimp, and other shellfishes), NSP, and ASP (in marine shrimp and crab). Hygiene index values among different species were significantly different. No significant difference in the monitoring index values was found among the six different studied districts. The reported cases of food-borne diarrhea were positively associated with VBN and DSP in aquatic products in Haishu, Jiangbei, Zhenhai, and Beilun, as well as VBN and NSP in aquatic products in Jiangdong and Yinzhou. In conclusion, VBN, DSP, NSP, and ASP are important risk factors for the occurring of food-borne diarrhea in the population of the Ningbo area in China.

A Near Infrared Light Triggered Hydrogenated Black TiO2 for Cancer Photothermal Therapy.

White TiO2 nanoparticles (NPs) have been widely used for cancer photodynamic therapy based on their ultraviolet light-triggered properties. To date, biomedical applications using white TiO2 NPs have been limited, since ultraviolet light is a well-known mutagen and shallow penetration. This work is the first report about hydrogenated black TiO2 (H-TiO2 ) NPs with near infrared absorption explored as photothermal agent for cancer photothermal therapy to circumvent the obstacle of ultraviolet light excitation. Here, it is shown that photothermal effect of H-TiO2 NPs can be attributed to their dramatically enhanced nonradiative recombination. After polyethylene glycol (PEG) coating, H-TiO2 -PEG NPs exhibit high photothermal conversion efficiency of 40.8%, and stable size distribution in serum solution. The toxicity and cancer therapy effect of H-TiO2 -PEG NPs are relative systemically evaluated in vitro and in vivo. The findings herein demonstrate that infrared-irradiated H-TiO2 -PEG NPs exhibit low toxicity, high efficiency as a photothermal agent for cancer therapy, and are promising for further biomedical applications.