Effects of Material Properties on Bacterial Adhesion and Biofilm Formation

Adhesion of microbes, such as bacteria and fungi, to surfaces and the subsequent formation of biofilms cause multidrug-tolerant infections in humans and fouling of medical devices. To address these challenges, it is important to understand how material properties affect microbe-surface interactions and engineer better nonfouling materials. Here we review the recent progresses in this field and discuss the main challenges and opportunities. In particular, we focus on bacterial biofilms and review the effects of surface energy, charge, topography, and stiffness of substratum material on bacterial adhesion. We summarize how these surface properties influence oral biofilm formation, and we discuss the important findings from nondental systems that have potential applications in dental medicine.

BH3-only molecule Bim mediates β-cell death in IRS2 deficiency

Irs2-deficient mice develop type 2-like diabetes due to a reduction in β-cell mass and a failure of pancreatic islets to undergo compensatory hyperplasia in response to insulin resistance. In order to define the molecular mechanisms, we knocked down Irs2 gene expression in mouse MIN6 insulinoma cells. Insulin receptor substrate 2 (IRS2) suppression induced apoptotic cell death, which was associated with an increase in expression of the BH3-only molecule Bim. Knockdown (KD) of Bim reduced apoptotic β-cell death induced by IRS2 suppression. In Irs2-deficient mice, Bim ablation restored β-cell mass, decreased the number of TUNEL-positive cells, and restored normal glucose tolerance after glucose challenge. FoxO1 mediates Bim upregulation induced by IRS2 suppression, and FoxO1 KD partially inhibits β-cell death induced by IRS2 suppression. These results suggest that Bim plays an important role in mediating the increase in β-cell apoptosis and the reduction in β-cell mass that occurs in IRS2-deficient diabetes.

Activation-induced necroptosis contributes to B-cell lymphopenia in active systemic lupus erythematosus

B-cell abnormality including excessive activation and lymphopenia is a central feature of systemic lupus erythematosus (SLE). Although activation threshold, auto-reaction and death of B cells can be affected by intrinsical and/or external signaling, the underlying mechanisms are unclear. Herein, we demonstrate that co-activation of Toll-like receptor 7 (TLR7) and B-cell receptor (BCR) pathways is a core event for the survival/dead states of B cells in SLE. We found that the mortalities of CD19(+)CD27(-) and CD19(+)IgM(+) B-cell subsets were increased in the peripheral blood mononuclear cells (PBMCs) of SLE patients. The gene microarray analysis of CD19(+) B cells from active SLE patients showed that the differentially expressed genes were closely correlated to TLR7, BCR, apoptosis, necroptosis and immune pathways. We also found that co-activation of TLR7 and BCR could trigger normal B cells to take on SLE-like B-cell characters including the elevated viability, activation and proliferation in the first 3 days and necroptosis in the later days. Moreover, the necroptotic B cells exhibited mitochondrial dysfunction and hypoxia, along with the elevated expression of necroptosis-related genes, consistent with that in both SLE B-cell microarray and real-time PCR verification. Expectedly, pretreatment with the receptor-interacting protein kinase 1 (RIPK1) inhibitor Necrostatin-1, and not the apoptosis inhibitor zVAD, suppressed B-cell death. Importantly, B cells from additional SLE patients also significantly displayed high expression levels of necroptosis-related genes compared with those from healthy donors. These data indicate that co-activation of TLR7 and BCR pathways can promote B cells to hyperactivation and ultimately necroptosis. Our finding provides a new explanation on B-cell lymphopenia in active SLE patients. These data suggest that extrinsic factors may increase the intrinsical abnormality of B cells in SLE patients.

Role of BH3-only molecules Bim and Puma in β-cell death in Pdx1 deficiency

Mutations in pancreatic duodenal homeobox-1 (PDX1) are associated with diabetes in humans. Pdx1-haploinsufficient mice develop diabetes due to an increase in β-cell death leading to reduced β-cell mass. For definition of the molecular link between Pdx1 deficiency and β-cell death, Pdx1-haploinsufficient mice in which the genes for the BH3-only molecules Bim and Puma had been ablated were studied on a high-fat diet. Compared with Pdx1(+/-) mice, animals haploinsufficient for both Pdx1 and Bim or Puma genes showed improved glucose tolerance, enhanced β-cell mass, and reduction in the number of TUNEL-positive cells in islets. These results suggest that Bim and Puma ablation improves β-cell survival in Pdx1(+/-) mice. For exploration of the mechanisms responsible for these findings, Pdx1 gene expression was knocked down in mouse MIN6 insulinoma cells resulting in apoptotic cell death that was found to be associated with increased expression of BH3-only molecules Bim and Puma. If the upregulation of Bim and Puma that occurs during Pdx1 suppression was prevented, apoptotic β-cell death was reduced in vitro. These results suggest that Bim and Puma play an important role in β-cell apoptosis in Pdx1-deficient diabetes.

dsRNA uptake and persistence account for tissue-dependent susceptibility to RNA interference in the migratory locust, Locusta migratoria

RNA interference (RNAi) by introducing double-stranded RNA (dsRNA) is a powerful approach to the analysis of gene function in insects; however, RNAi responses vary dramatically in different insect species and tissues, and the underlying mechanisms remain poorly understood. The migratory locust, a destructive insect pest and a hemimetabolic insect with panoistic ovaries, is considered to be a highly susceptible species to RNAi via dsRNA injection, but its ovary appears to be completely insensitive. In the present study, we showed that dsRNA persisted only briefly in locust haemolymph. The ovariole sheath was permeable to dsRNA, but injected dsRNA was not present in the follicle cells and oocytes. The lack of dsRNA uptake into the follicle cells and oocytes is likely to be the primary factor that contributes to the ineffective RNAi response in locust ovaries. These observations provide insights into tissue-dependent variability of RNAi and help in achieving successful gene silencing in insensitive tissues.

Case-control study of risk factors for human infection with influenza A(H7N9) virus in Jiangsu Province, China, 2013

We describe a case-control study performed in Jiangsu, China, to evaluate risk factors for human infection with novel avian influenza A(H7N9) virus. Twenty-five cases and 93 controls matched by age, sex, and location were included in the study. Direct contact with poultry or birds in the two weeks before illness onset, chronic medical conditions (hypertension excluded), and environment-related exposures were significantly associated with A(H7N9) infection.

NF-κB–inducing kinase (NIK) promotes hyperglycemia and glucose intolerance in obesity by augmenting glucagon action

The canonical inhibitor of nuclear factor κB kinase subunit β (IKK-β)–nuclear factor of κ light polypeptide gene enhancer in B cells 1 (NF-κB1) pathway has been well documented to promote insulin resistance; however, the noncanonical NF-κB–inducing kinase (NIK)–NF-κB2 pathway is not well understood in obesity. Additionally, the contribution of counter-regulatory hormones, particularly glucagon, to hyperglycemia in obesity is unclear. Here we show that NIK promotes glucagon responses in obesity. Hepatic NIK was abnormally activated in mice with dietary or genetic obesity. Systemic deletion of Map3k14, encoding NIK, resulted in reduced glucagon responses and hepatic glucose production (HGP). Obesity is associated with high glucagon responses, and liver-specific inhibition of NIK led to lower glucagon responses and HGP and protected against hyperglycemia and glucose intolerance in obese mice. Conversely, hepatocyte-specific overexpression of NIK resulted in higher glucagon responses and HGP. In isolated mouse livers and primary hepatocytes, NIK also promoted glucagon action and glucose production, at least in part by increasing cAMP response element-binding (CREB) stability. Therefore, overactivation of liver NIK in obesity promotes hyperglycemia and glucose intolerance by increasing the hyperglycemic response to glucagon and other factors that activate CREB.

Acute and chronic thoracic aortic disease: surgical considerations

Acute thoracic aortic aneurysm is one of the most life-threatening vascular disorders recognized to date. The majority of these aortic ruptures rapidly end in mortality, with 50% of patients suffering death before reaching the hospital. Thus, acute management through surgical intervention is often indicated, especially in cases of ascending aortic rupture. Physical examination is critical in making the diagnosis, as clinical signs and symptoms often vary depending on the location of the dissection. Clinicians should have a low threshold for including thoracic aortic dissection in their differential diagnosis, especially when a patient presents with acute onset chest or back pain. In this report, we discuss the different categories of aortic dissections and the current treatment modalities for each. These include endovascular aortic repair, which has become a viable treatment modality in certain cases of type B dissection. Offering a less invasive approach, the technique known as thoracic endovascular repair currently affords a treatment option to a patient population who would have otherwise been deemed non-surgical candidates. Hybrid thoracic endovascular aortic repair has also become a pertinent surgical technique, and successful outcomes have been demonstrated when it is employed to repair ascending aortic aneurysms. We also describe our Acute Aortic Treatment Center, a rapid multicentric triage system for the management of acute aortic pathologies, which has resulted in significant improvements in patient outcomes.

BID, BIM, and PUMA are essential for activation of the BAX- and BAK-dependent cell death program

Although the proteins BAX and BAK are required for initiation of apoptosis at the mitochondria, how BAX and BAK are activated remains unsettled. We provide in vivo evidence demonstrating an essential role of the proteins BID, BIM, and PUMA in activating BAX and BAK. Bid, Bim, and Puma triple-knockout mice showed the same developmental defects that are associated with deficiency of Bax and Bak, including persistent interdigital webs and imperforate vaginas. Genetic deletion of Bid, Bim, and Puma prevented the homo-oligomerization of BAX and BAK, and thereby cytochrome c-mediated activation of caspases in response to diverse death signals in neurons and T lymphocytes, despite the presence of other BH3-only molecules. Thus, many forms of apoptosis require direct activation of BAX and BAK at the mitochondria by a member of the BID, BIM, or PUMA family of proteins.

Evaluations of boar gonad development, spermatogenesis with regard to semen characteristics, libido and serum testosterone levels based on large White Duroc x Chinese Erhualian crossbred boars

Chinese Erhualian pigs are known for prolificacy with distinct reproductive traits compared with Western commercial breeds. In this study, a four-generation intercross resource population was constructed using White Duroc boars and Chinese Erhualian sows as founder animals, and a total of 14 male reproductive traits were recorded in 411 F2/F3 boars including the testis and epididymis weights, the seminiferous tubular diameter and spermatogenesis at 60, 90 and 300 days of age, semen characteristics, serum testosterone concentration and libido level at 300 days of age. The White Duroc-Erhualian boars showed remarkable segregations in the traits measured except for the seminiferous tubular diameter and had high ratio (13.9%) of the abnormality of spermatogenesis, providing a good experimental population for detecting quantitative trait loci affecting these male reproductive traits. Furthermore, the correlations among nine male reproductive traits at 300 days of age indicated that the testis weight and the body weight were strongly correlated with the sperm production, supporting the two traits as important parameters for boar selection to increase sperm production and ultimately improve boar fertility. The libido level in the White Duroc-Erhualian boars that was evaluated by a new and easily recorded scoring system showed a significant correlation with serum testosterone concentration. Yet, both libido and serum testosterone concentration were not correlated with the sperm production. Results of this study provided new information on the male reproductive physiology and genetics in Chinese Erhualian and White Duroc boars.

SH2B regulation of growth, metabolism, and longevity in both insects and mammals

SH2B1 is a key regulator of body weight in mammals. Here, we identified dSH2B as the Drosophila homolog of SH2B1. dSH2B bound to Chico and directly promoted insulin-like signaling. Disruption of dSH2B decreased insulin-like signaling and somatic growth in flies. dSH2B deficiency also increased hemolymph carbohydrate levels, whole-body lipid levels, life span, and resistance to starvation and oxidative stress. Systemic overexpression of dSH2B resulted in opposite phenotypes. dSH2B overexpression in fat body decreased lipid and glucose levels, whereas neuron-specific overexpression of dSH2B decreased oxidative resistance and life span. Genetic deletion of SH2B1 also resulted in growth retardation, obesity, and type 2 diabetes in mice; surprisingly, life span and oxidative resistance were reduced in SH2B1 null mice. These data suggest that dSH2B regulation of insulin-like signaling, growth, and metabolism is conserved in SH2B1, whereas dSH2B regulation of oxidative stress and longevity may be conserved in other SH2B family members.

The Arabidopsis gene SIGMA FACTOR-BINDING PROTEIN 1 plays a role in the salicylate- and jasmonate-mediated defence responses

The chloroplast-localized SIB1 protein was previously identified by its interaction with SIGMA FACTOR 1 (SIG1), a component of the RNA polymerase machinery responsible for transcription of plastid genes. The physiological function of SIB1 is little known. We found that expression of SIB1 is induced by infection with Pseudomonas syringae, suggesting its possible involvement in the defence response. The sib1 loss-of-function mutation compromises induction of some defence-related genes triggered by pathogen infection and the treatments with salicylic acid (SA) and jasmonic acid (JA), two key signalling molecules in the defence response. Conversely, constitutive over-expression of SIB1 causes the plants to hyper-activate defence-related genes following pathogen infection or the SA and JA treatments, leading to enhanced resistance to infection by P. syringae. SIB1 is a member of the large plant-specific VQ motif-containing protein family, and might act as a link to connect defence signalling with chloroplast function.

Stepwise activation of BAX and BAK by tBID, BIM, and PUMA initiates mitochondrial apoptosis

While activation of BAX/BAK by BH3-only molecules (BH3s) is essential for mitochondrial apoptosis, the underlying mechanisms remain unsettled. Here we demonstrate that BAX undergoes stepwise structural reorganization leading to mitochondrial targeting and homo-oligomerization. The alpha1 helix of BAX keeps the alpha9 helix engaged in the dimerization pocket, rendering BAX as a monomer in cytosol. The activator BH3s, tBID/BIM/PUMA, attack and expose the alpha1 helix of BAX, resulting in secondary disengagement of the alpha9 helix and thereby mitochondrial insertion. Activator BH3s remain associated with the N-terminally exposed BAX through the BH1 domain to drive homo-oligomerization. BAK, an integral mitochondrial membrane protein, has bypassed the first activation step, explaining why its killing kinetics are faster than those of BAX. Furthermore, death signals initiated at ER induce BIM and PUMA to activate mitochondrial apoptosis. Accordingly, deficiency of Bim/Puma impedes ER stress-induced BAX/BAK activation and apoptosis. Our study provides mechanistic insights regarding the spatiotemporal execution of BAX/BAK-governed cell death.

The VDAC2-BAK rheostat controls thymocyte survival

The proapoptotic proteins BAX and BAK constitute the mitochondrial apoptotic gateway that executes cellular demise after integrating death signals. The lethal BAK is kept in check by voltage-dependent anion channel 2 (VDAC2), a mammalian-restricted VDAC isoform. Here, we provide evidence showing a critical role for the VADC2-BAK complex in determining thymocyte survival in vivo. Genetic depletion of Vdac2 in the thymus resulted in excessive cell death and hypersensitivity to diverse death stimuli including engagement of the T cell receptor. These phenotypes were completely rescued by the concurrent deletion of Bak but not that of Bax. Thus, the VDAC2-BAK axis provides a mechanism that governs the homeostasis of thymocytes. Our study reveals a sophisticated built-in rheostat that likely fine-tunes immune competence to balance autoimmunity and immunodeficiency.

Synergistic antitumor efficacy of suicide/ePNP gene and 6-methylpurine 2'-deoxyriboside via Salmonella against murine tumors

Some anaerobes and facultative anaerobes have been used in tumor-specific gene therapy by reason of their selective growth in tumors. In this work, we aimed to evaluate the anticancer efficacy of attenuated Salmonella typhimurium as a carrier to deliver the Escherichia coli purine nucleoside phosphorylase (ePNP) gene for GDEPT (gene-directed enzyme-prodrug therapy). A live attenuated purine-auxotrophic strain of S. typhimurium (SC36) was used to carry the pEGFP-C1-ePNP vector that contains a green fluorescent protein (GFP) and an ePNP gene under the control of the human cytomegalovirus (CMV) promoter. The function of the ePNP expression vector was confirmed in vitro using the enzymic conversion of 6-methylpurine 2'-deoxyriboside (MePdR) into 6-methylpurine. We also observed a high bystander effect induced by the ePNP/MePdR system with a very low proportion (1%) of ePNP-positive cells. The killing effect and increased apoptosis induced by SC/ePNP (SC36 carrying the ePNP expression vector) infection were detected by cytotoxicity assay and PI staining flow cytometry analysis, in combination with MePdR administration. Furthermore, SC/ePNP was administered orally into mice bearing melanomas or pulmonary tumors, and its anti-tumor effect was evaluated. When the tumor was huge (500 mm(3)) at the beginning of MePdR administration, SC/ePNP plus MepdR significantly inhibited tumor growth by about 59-80% and prolonged survival of mice. Complete tumor regression and long-term cure were achieved by MePdR administration, even when the tumor was large (100 mm(3)) at the beginning of MePdR treatment. Our data support a hopeful view that tumor-targeting SC36 could improve antitumor efficacy of the ePNP/MePdR system due to its preferential accumulation and anticancer activity in tumors.

Bax and Bak do not exhibit functional redundancy in mediating radiation-induced endothelial apoptosis in the intestinal mucosa

PURPOSE

To address in vivo the issue of whether Bax and Bak are functionally redundant in signaling apoptosis, capable of substituting for each other.

METHODS AND MATERIALS

Mice were exposed to whole-body radiation, and endothelial cell apoptosis was quantified using double immunostaining with TUNEL and anti-CD31 antibody. Crypt survival was determined at 3.5 days after whole-body radiation by the microcolony survival assay. Actuarial animal survival was calculated by the product-limit Kaplan-Meier method, and autopsies were performed to establish cause of death.

RESULTS

Radiation exposure of Bax- and Bak-deficient mice, both expressing a wild-type acid sphingomyelinase (ASMase) phenotype, indicated that Bax and Bak are both mandatory, though mutually independent, for the intestinal endothelial apoptotic response. However, neither affected epithelial apoptosis at crypt positions 4-5, indicating specificity toward endothelium. Furthermore, Bax deficiency and Bak deficiency each individually mimicked ASMase deficiency in inhibiting crypt lethality in the microcolony assay and in rescuing mice from the lethal gastrointestinal syndrome.

CONCLUSIONS

The data indicate that Bax and Bak have nonredundant functional roles in the apoptotic response of the irradiated intestinal endothelium. The observation that Bax deficiency and Bak deficiency also protect crypts in the microcolony assay provides strong evidence that the microvascular apoptotic component is germane to the mechanism of radiation-induced damage to mouse intestines, regulating reproductive cell death of crypt stem cell clonogens.

Neuronal SH2B1 is essential for controlling energy and glucose homeostasis

SH2B1 (previously named SH2-B), a cytoplasmic adaptor protein, binds via its Src homology 2 (SH2) domain to a variety of protein tyrosine kinases, including JAK2 and the insulin receptor. SH2B1-deficient mice are obese and diabetic. Here we demonstrated that multiple isoforms of SH2B1 (alpha, beta, gamma, and/or delta) were expressed in numerous tissues, including the brain, hypothalamus, liver, muscle, adipose tissue, heart, and pancreas. Rat SH2B1beta was specifically expressed in neural tissue in SH2B1-transgenic (SH2B1(Tg)) mice. SH2B1(Tg) mice were crossed with SH2B1-knockout (SH2B1(KO)) mice to generate SH2B1(TgKO) mice expressing SH2B1 only in neural tissue but not in other tissues. Systemic deletion of the SH2B1 gene resulted in metabolic disorders in SH2B1(KO) mice, including hyperlipidemia, leptin resistance, hyperphagia, obesity, hyperglycemia, insulin resistance, and glucose intolerance. Neuron-specific restoration of SH2B1beta not only corrected the metabolic disorders in SH2B1(TgKO) mice, but also improved JAK2-mediated leptin signaling and leptin regulation of orexigenic neuropeptide expression in the hypothalamus. Moreover, neuron-specific overexpression of SH2B1 dose-dependently protected against high-fat diet-induced leptin resistance and obesity. These observations suggest that neuronal SH2B1 regulates energy balance, body weight, peripheral insulin sensitivity, and glucose homeostasis at least in part by enhancing hypothalamic leptin sensitivity.

Role of inducible nitric oxide synthase expressed by alveolar macrophages in high mobility group box 1--induced acute lung injury

OBJECTIVE AND DESIGN

The role of inducible nitric oxide synthase (iNOS) expressed by alveolar macrophages in acute lung injury induced by high mobility group box 1 (HMGB1) was explored.

TREATMENTS

Primary rat alveolar macrophages (PRAMs) were stimulated with HMGB1 to analyze iNOS expression. Alveolar macrophages and iNOS were inhibited by gadolinium chloride and 1400W in rats challenged by HMGB1 intratracheally.

METHODS

Western Blot was applied to assay iNOS expression in PRAMs. Indices for acute lung injury in rats were measured. Immunocytochemistry was used to localize iNOS in squarebronchoalveolar lavage (BAL) cells. The enzyme activities of iNOS and constitutive nitric oxide synthase (cNOS) for BAL cells were determined.

RESULTS

A time- and concentration-dependent response of iNOS expression in PRAMs to HMGB1 induction was observed. Intratracheal instillation of HMGB1 produced persistently exacerbated acute lung inflammation, induction of iNOS in alveolar macrophages and increased lung nitric oxide production in rats. Abrogation of iNOS or macrophages attenuated lung inflammation, nitric oxide in BAL fluid, and iNOS activity of BAL cells, but had no significant effect on cNOS activity of BAL cells in rats challenged by HMGB1.

CONCLUSIONS

Inducible nitric oxide synthase expressed by alveolar macrophages facilitates the development of HMGB1-induced acute lung injury.

Differential role of SH2-B and APS in regulating energy and glucose homeostasis

SH2-B and APS, two members of a pleckstrin homology and SH2 domain-containing adaptor family, promote both insulin and leptin signaling in a similar fashion in cultured cells. In addition, APS mediates insulin-stimulated activation of the c-Cbl/CAP/TC10 pathway in cultured adipocytes. Here we characterized genetically modified mice lacking SH2-B, APS, or both to determine the physiological roles of these two proteins in animals. Disruption of the SH2-B gene resulted in obesity, hyperglycemia, hyperinsulinemia, and glucose intolerance. Conversely, deletion of the APS gene did not alter adiposity, energy balance, and glucose metabolism. Energy intake, energy expenditure, fat content, body weight, and plasma insulin, leptin, glucose, and lipid levels were similar between APS(-/-) and WT littermates fed either normal chow or a high-fat diet. Moreover, deletion of APS failed to alter insulin and glucose tolerance. APS(-/-)/SH2-B(-/-) double knockout mice also developed energy imbalance, obesity, hyperleptinemia, hyperinsulinemia, hyperglycemia, and glucose intolerance; however, plasma leptin and insulin levels were significantly lower in APS(-/-)/SH2-B(-/-) than in SH2-B(-/-) mice. These results suggest that SH2-B, but not APS, is a key positive regulator of energy and glucose metabolism in mice.

Controlled cortical impact injury affects dopaminergic transmission in the rat striatum

The therapeutic benefits of dopamine (DA) agonists after traumatic brain injury (TBI) imply a role for DA systems in mediating functional deficits post-TBI. We investigated how experimental TBI affects striatal dopamine systems using fast scan cyclic voltammetry (FSCV), western blot, and d-amphetamine-induced rotational behavior. Adult male Sprague-Dawley rats were injured by a controlled cortical impact (CCI) delivered unilaterally to the parietal cortex, or were naïve controls. Amphetamine-induced rotational behavior was assessed 10 days post-CCI. Fourteen days post-CCI, animals were anesthetized and underwent FSCV with bilateral striatal carbon fiber microelectrode placement and stimulating electrode placement in the medial forebrain bundle (MFB). Evoked DA overflow was assessed in the striatum as the MFB was electrically stimulated at 60 Hz for 10 s. In 23% of injured animals, but no naïve animals, rotation was observed with amphetamine administration. Compared with naïves, striatal evoked DA overflow was lower for injured animals in the striatum ipsilateral to injury (p < 0.05). Injured animals exhibited a decrease in V(max) (52% of naïve, p < 0.05) for DA clearance in the hemisphere ipsilateral to injury compared with naïves. Dopamine transporter (DAT) expression was proportionally decreased in the striatum ipsilateral to injury compared with naïve animals (60% of naïve, p < 0.05), despite no injury-related changes in vesicular monoamine transporter or D2 receptor expression (DRD2) in this region. Collectively, these data appear to confirm that the clinical efficacy of dopamine agonists in the treatment of TBI may be related to disruptions in the activity of subcortical dopamine systems.

Identification of SH2-B as a key regulator of leptin sensitivity, energy balance, and body weight in mice

Leptin regulates energy balance and body weight by activating its receptor LEPRb and multiple downstream signaling pathways, including the STAT3 and the IRS2/PI 3-kinase pathways, in the hypothalamus. Leptin stimulates activation of LEPRb-associated JAK2, which initiates cell signaling. Here we identified SH2-B, a JAK2-interacting protein, as a key regulator of leptin sensitivity, energy balance, and body weight. SH2-B homozygous null mice were severely hyperphagic and obese and developed a metabolic syndrome characterized by hyperleptinemia, hyperinsulinemia, hyperlipidemia, hepatic steatosis, and hyperglycemia. The expression of hypothalamic orexigenic NPY and AgRP was increased in SH2-B(-/-) mice. Leptin-stimulated activation of hypothalamic JAK2 and phosphorylation of hypothalamic STAT3 and IRS2 were significantly impaired in SH2-B(-/-) mice. Moreover, overexpression of SH2-B counteracted PTP1B-mediated inhibition of leptin signaling in cultured cells. Our data suggest that SH2-B is an endogenous enhancer of leptin sensitivity and required for maintaining normal energy metabolism and body weight in mice.

Information theory in prediction of cleavage sites of signal peptides

Information theory is used to analyze the character of signal peptide quantitatively, especially residents. On the basis of the above analysis, a method named simplified information-matrix has been developed to predict the cleavage sites of signal peptides. A comparison between the results of weight-matrix and simplified information-matrix is presented.

Gene expression in Escherichia coli biofilms

DNA microarrays were used to study the gene expression profile of Escherichia coli JM109 and K12 biofilms. Both glass wool in shake flasks and mild steel 1010 plates in continuous reactors were used to create the biofilms. For the biofilms grown on glass wool, 22 genes were induced significantly (p< or =0.05) compared to suspension cells, including several genes for the stress response ( hslS, hslT, hha, and soxS), type I fimbriae ( fimG), metabolism ( metK), and 11 genes of unknown function ( ybaJ, ychM, yefM, ygfA, b1060, b1112, b2377, b3022, b1373, b1601, and b0836). The DNA microarray results were corroborated with RNA dot blotting. For the biofilm grown on mild steel plates, the DNA microarray data showed that, at a specific growth rate of 0.05/h, the mature biofilm after 5 days in the continuous reactors did not exhibit differential gene expression compared to suspension cells although genes were induced at 0.03/h. The present study suggests that biofilm gene expression is strongly associated with environmental conditions and that stress genes are involved in E. coli JM109 biofilm formation.

Tumor necrosis factor expression in arterial walls of diabetic rats

Immunohistochemistry was used to detect tumor necrosis factor (TNF-alpha) expression in arterial wall of diabetic rats. It was found that endothelial cells were swollen and markedly proliferative in these vessels and accordingly TNF-alpha showed strong positive immunohistochemical reaction in endothelial cells or extracellular intimal matrix of such vessels, which might be caused by the expression and release of TNF-alpha from monocytes and arterial wall cells stimulated by AGEs. These findings suggested that increased TNF-alpha expression might be associated with vascular damage and remodeling in diabetes.

[Changes in chloroquine resistance of Plasmodium falciparum in Hainan province]

AIM

To observe the variation in resistance of Plasmodium falciparum after the cessation of chloroquine medication.

METHODS

WHO standard in vitro microtest and in vivo test were used.

RESULTS

In vitro test showed that the rate of chloroquine-resistant P. falciparum dropped from 97.9% in 1981 to 26.7% in 1997 (P < 0.001). The mean concentration of chloroquine for complete inhibition of schizont formation declined from 10.46 +/- 7.14 pmol/ul blood in 1981 to 1.63 +/- 1.47 pmol/microliter blood in 1997(P < 0.001). In vivo test showed that the rate of chloroquine-resistant P. falciparum decreased from 84.2% in 1981 to 18.4% in 1997(P < 0.001). The proportion of R III cases to the total resistant cases dropped from 53.1% in 1981 to 14.3% in 1997.

CONCLUSION

A tendency of progressive decline of resistance of the parasite was revealed after the cessation of chloroquine medication.

Effects of salvianolic acids on endothelial cells against damage induced by cholestane-3beta-5alpha-6beta-triol

OBJECTIVE

To investigate the effects of salvianolic acids on human umbilical vein endothelial cells (HUVEC) against damage induced by cholestane-3beta-5alpha-6beta-triol (chol-triol).

METHODS

The viability of HUVEC was measured by MTT method. The apoptosis of HUVEC induced by chol-triol was detected by flow cytometry and TUNEL assay. The production of malondialdehyd (MDA) in HUVEC was tested by thiobarbaturic acid (TBA) assay.

RESULTS

The viability of HUVEC treated with chol-triol 100 micro mol/L decreased by 39.8% while salvianolic acids 100 micro g/ml increased by 27.9%. The apoptotic rate of HUVEC measured by PI staining increased from 6% - 8% to 17% - 20% after chol-triol treatment for 12 h. Salvianolic acids 100 micro g/ml reduced the apoptotic rate to 10% - 14% after treatment HUVEC for 1 h prior to chol-triol treatment. In another experiment, chol-triol increased the number of TUNEL-positive cells 5 times, but salvianolic acids 10 micro g/ml and 100 micro g/ml reduced the number of TUNEL-positive cells by 36.9% and 61.2%, respectively. The production of MDA in HUVEC increased by 120.7% after chol-triol treatment for 12 h. Salvianolic acids 10 micro g/ml and 100 micro g/ml also decreased the concentration of MDA by 28.7% and 39.8%, respectively.

CONCLUSION

Salvianolic acids has protective effect on endothelial cells against damage induced by chol-triol.

Short-term exposure to melatonin differentially affects the functional sensitivity and trafficking of the hMT1 and hMT2 melatonin receptors

The hormone melatonin mediates a variety of physiological functions in mammals through activation of pharmacologically distinct MT(1) and MT(2) G protein-coupled melatonin receptors. We therefore sought to investigate how the receptors were regulated in response to short melatonin exposure. Using 2-[(125)I]iodomelatonin binding, cAMP functional assays, and confocal microscopy, we demonstrated robust differences in specific 2-[(125)I]iodomelatonin binding, receptor desensitization, and cellular trafficking of hMT(1) and hMT(2) melatonin receptors expressed in Chinese hamster ovary (CHO) cells after short (10-min) exposure to melatonin. Exposure to melatonin decreased specific 2-[(125)I]iodomelatonin binding to CHO-MT(2) cells (70.3 +/- 7.6%, n = 3) compared with vehicle controls. The robust decreases in specific binding to the hMT(2) melatonin receptors correlated both with the observed functional desensitization of melatonin to inhibit forskolin-stimulated cAMP formation in CHO-MT(2) cells pretreated with 10 nM melatonin (EC(50) of 159.8 +/- 17.8 nM, n = 3, p < 0.05) versus vehicle (EC(50) of 6.0 +/- 1.2 nM, n = 3), and with the arrestin-dependent internalization of the receptor. In contrast, short exposure of CHO-MT(1) cells to melatonin induced a small decrease in specific 2-[(125)I]iodomelatonin binding (34.2 +/- 13.0%, n = 5) without either desensitization or receptor internalization. We conclude that differential regulation of the hMT(1) and hMT(2) melatonin receptors by the hormone melatonin could underlie temporally regulated signal transduction events mediated by the hormone in vivo.

Polysaccharide sulfate 916 inhibits neutrophil-endothelial adhesion

OBJECTIVE

To study the effect of polysaccharide sulfate 916 (PS916) on neutrophil-endothelial cell adhesion.

METHODS

Cell adhesion was evaluated by testing neutrophil myeloperoxidase activity. Expression of adhesion molecule in human umbilical vein endothelial cell (HUVEC) was measured by ELISA. The neutrophil activation rate induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP) was tested by nitroblue tetrazolium (NBT) reduction.

RESULTS

Tumor necrosis factor alpha (TNFalpha, 50 - 800 U/ml) increased the adherence of neutrophil to TNFalpha-stimulated HUVEC in a concentration and time dependent manner. PS916 (0.01 - 1.0 mg/ml) dose-dependently inhibited the adherence of neutrophils to TNFalpha-stimulated HUVEC. fMLP increased the activation rate of neutrophils independent of concentration. PS916 also inhibited the adherence of fMLP-activated neutrophils to HUVEC. Moreover, PS916 inhibited adhesion molecule expression in TNFalpha-stimulated HUVEC.

CONCLUSIONS

PS916 inhibited neutrophil-endothelial adhesion. The mechanism of its action was partially related to suppressing the expressions of intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1).

Inhibition of biofilm formation and swarming of Bacillus subtilis by (5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone

AIMS

(5Z)-4-Bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone(furanone) of the marine alga Delisea pulchra was synthesized, and its inhibition of swarming motility and biofilm formation of Bacillus subtilis was investigated.

METHODS AND RESULTS

Furanone was found to inhibit both the growth of B. subtilis and its swarming motility in a concentration-dependent way. In addition, as shown by confocal scanning laser microscopy, furanone inhibited the biofilm formation of B. subtilis. At 40 microg ml(-1), furanone decreased the biofilm thickness by 25%, decreased the number of water channels, and reduced the percentage of live cells by 63%.

CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY

Natural furanone has potential for controlling the multicellular behaviour of Gram-positive bacteria.

Effect of polysaccharide sulfate 916 on the production of nitric oxide in ECV304 cells induced by cytokines and H(2)O(2)

OBJECTIVE

To investigate the effect of polysaccharide sulfate 916 (PS916) on the production of nitric oxide (NO) in ECV304 cells induced by tumor necrosis factor-alpha (TNF alpha), interleukin-1 beta (IL-1 beta) and H(2)O(2) in vitro.

METHODS

Production of NO in ECV304 cells was measured by the Griess method and the proliferation of cells was tested by the MTT method. The activity of NO synthase was detected spectrophotometrically.

RESULTS

Production of NO in ECV304 cells decreased after treatment with 40 ng/ml IL-1 beta and 40 ng/ml TNF alpha, but increased in the presence of H(2)O(2) 0.1 mmol/L. PS916 significantly enhanced NO production in ECV304 cells in a dose-dependent manner in the TNF alpha and IL-1 beta treated groups and decreased it in the H(2)O(2) treated group. Proliferation of ECV304 cells was inhibited by TNFalpha and H(2)O(2) and no effect was found in the IL-1 beta treated group. PS916 increased the proliferation of cells treated with TNFalpha and H(2)O(2) dose-dependently. In vitro, PS916 has no effect on the activity of NO synthase.

CONCLUSION

PS916 has a protective effect on ECV304 cells exposed to IL-1 beta, TNF alpha and H(2)O(2).

Molecular components of tolerance to opiates in single hippocampal neurons

We examined the effect of acute and chronic opioid treatment on synaptic transmission and mu-opioid receptor (MOR) endocytosis in cultures of naïve rat hippocampal neurons. Opioid agonists that activate MOR inhibited synaptic transmission at inhibitory but not excitatory autapses. [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO), morphine, and methadone were all effective at blocking inhibitory transmission. These same drugs also reduced the amplitude of voltage-dependent Ca(2+) currents in inhibitory but not excitatory neurons. Chronic treatment with all three opioids reduced the subsequent effects of a challenge with either the same drug or one of the others in individual autaptic neurons. Chronic treatment with DAMGO or methadone produced internalization of enhanced yellow fluorescent protein-tagged MOR expressed in hippocampal neurons within hours, whereas morphine produced internalization much more slowly, even when accompanied by overexpression of beta-arrestin-2. We conclude that DAMGO, methadone, and morphine all produce tolerance in single hippocampal neurons. Morphine-induced tolerance does not necessarily seem to involve receptor endocytosis.

A prokaryotic voltage-gated sodium channel

The pore-forming subunits of canonical voltage-gated sodium and calcium channels are encoded by four repeated domains of six-transmembrane (6TM) segments. We expressed and characterized a bacterial ion channel (NaChBac) from Bacillus halodurans that is encoded by one 6TM segment. The sequence, especially in the pore region, is similar to that of voltage-gated calcium channels. The expressed channel was activated by voltage and was blocked by calcium channel blockers. However, the channel was selective for sodium. The identification of NaChBac as a functionally expressed bacterial voltage-sensitive ion-selective channel provides insight into both voltage-dependent activation and divalent cation selectivity.

Inhibition of biofilm formation and swarming of Escherichia coli by (5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone

The quorum-sensing disrupter (5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone (furanone) of the alga Delisea pulchra was found to inhibit the swarming motility of Escherichia coli completely at 13 microg cm-2 (also at 20 microg ml-1) but did not inhibit its growth rate at 13-52 microg cm-2 or from 20 to 100 microg ml-1. Swimming was not inhibited by the furanone at 20-40 microg ml-1. In addition, confocal scanning laser microscopy revealed that this furanone at 60 microg ml-1 inhibited the biofilm formation of E. coli, as it decreased its thickness by 55%, reduced the number of water channels and decreased the percentage of live cells by 87%. This suggests that natural furanone may be used as a new method to control bacterial biofilms that does not involve toxicity. Furanone at 10 microg ml-1 also inhibited by 3300-fold the quorum sensing of Vibrio harveyi via autoinducer 1 (AI-1) and inhibited by 5500-fold that of V. harveyi via of autoinducer 2 (AI-2) as well as inhibited by 26-600-fold the quorum sensing of E. coli via AI-2; hence, this furanone is a non-specific intercellular signal antagonist.

A voltage-gated ion channel expressed specifically in spermatozoa

Calcium ions play a primary role in the regulation of sperm cell behavior. We report finding a voltage-gated ion channel (CatSper2) that is expressed in male germ cells but not in other cells. The putative channel contains 6 transmembrane segments, making it more similar to the voltage-gated potassium channels, but the ion selectivity pore domain sequence resembles that of a Ca(v) channel. The mRNA is expressed during the meiotic or postmeiotic stages of spermatogenesis, and the protein is localized to the sperm flagellum, suggesting a role in the regulation of sperm motility. The mRNA for the channel is present in mouse, rat, and human sperm cells, and the gene is found on chromosome 2 E5-F1 in the mouse and 15q13 in the human. Recently, another voltage-gated channel (CatSper) that has features similar to the one reported here was discovered. It also is expressed within the flagellum and is required for normal fertility of mice. However, expression of CatSper2 alone or coexpression with CatSper in cultured cells, or attempts to coimmunoprecipitate the two proteins from germ cells failed to demonstrate that these two unique but similar alpha-like subunits form either a homo- or heterotetramer. It is possible, therefore, that two independent alpha subunits, different from other known voltage-gated channels, regulate sperm motility.

A sperm ion channel required for sperm motility and male fertility

Calcium and cyclic nucleotides have crucial roles in mammalian fertilization, but the molecules comprising the Ca2+-permeation pathway in sperm motility are poorly understood. Here we describe a putative sperm cation channel, CatSper, whose amino-acid sequence most closely resembles a single, six-transmembrane-spanning repeat of the voltage-dependent Ca2+-channel four-repeat structure. CatSper is located specifically in the principal piece of the sperm tail. Targeted disruption of the gene results in male sterility in otherwise normal mice. Sperm motility is decreased markedly in CatSper-/- mice, and CatSper-/- sperm are unable to fertilize intact eggs. In addition, the cyclic-AMP-induced Ca2+ influx is abolished in the sperm of mutant mice. CatSper is thus vital to cAMP-mediated Ca2+ influx in sperm, sperm motility and fertilization. CatSper represents an excellent target for non-hormonal contraceptives for both men and women.