Proliferative verrucous leukoplakia: a general dental practitioner-focused clinical review.

Proliferative verrucous leukoplakia (PVL) is a distinct type of oral leukoplakia which has the potential to enlarge or develop into new areas of leukoplakia coupled with areas of a warty surface texture. PVL is usually diagnosed from the fifth decade onwards and is more common in female patients. The most frequent sites involved tend to be gingivae, followed by buccal mucosa and lateral border of tongue. It is one of the oral potentially malignant conditions with a high risk of malignant transformation. It is important for general dental practitioners (GDPs) to identify such lesions to facilitate referral for further investigation and diagnosis. Management is challenging with long-term monitoring and surgical excision when appropriate; however, PVL tends to recur following surgical excision. This article provides an up-to-date review tailored for GDPs on the present knowledge of PVL and illustrates the management challenges with clinical cases.

Oral hairy leukoplakia in healthy immunocompetent patients: a small case series.

BACKGROUND: Oral hairy leukoplakia (OHL) is caused by the Epstein-Barr virus (EBV) and usually presents in patients with human immunodeficiency virus (HIV) infection and systemic immunosuppression. It is rarely seen in patients who are immunocompetent. It is clinically characterised as an asymptomatic, soft, white and corrugated lesion that cannot be scraped from the surface it adheres to. METHODS: Immunocompetent patients with OHL attending Bristol Dental Hospital within the last 6 months were identified. EBV infection was demonstrated using EBV in situ hybridization. Clinical features and medical history were determined by reviewing medical records. CASE REPORT: Four cases of OHL in immunocompetent individuals were identified. All lesions were located on the lateral borders of the tongue. DISCUSSION: OHL should be considered as a differential diagnosis for white patches on the lateral borders of the tongue in apparently healthy immunocompetent patients, even when they do not have a typical corrugated appearance. OHL should no longer be regarded as pathognomonic for HIV infection or systemic immunosuppression.

Functional characterization of a novel somatic oncogenic mutation of PIK3CB.

Class I phosphoinositide 3-kinase (PI3K) enzymes have attracted considerable attention as drug targets in cancer therapy over the last 20 years. The signaling pathway triggered by class I PI3Ks is dysregulated in a range of tumor types, impacting cell proliferation, survival and apoptosis. Frequent oncogenic mutations of PIK3CA have previously been discovered. In contrast, reports of PIK3CB mutations have been limited; however, in most cases, those that have been identified have been shown to be activating and oncogenic. The functional characterization of a PIK3CB catalytic domain mutant, p110ßE1051K, first discovered by others in castrate-resistant prostate cancer (mCRPC), is outlined in this report; our data suggest that p110ßE1051K is a gain-of-function mutation, driving PI3K signaling, tumorigenic cell growth and migration. Tumor cells expressing p110ßE1051K are sensitive to p110ß inhibition; its characterization as an oncogenic driver adds to the rationale for targeting p110ß and indicates a continuing need to further develop specific PI3K inhibitors for clinical development in cancer therapy.

Lipopolysaccharide-induced M2 to M1 macrophage transformation for IL-12p70 production is blocked by Candida albicans mediated up-regulation of EBI3 expression.

Macrophages are heterogeneous cell populations that are present in all tissues. Macrophages can be divided into classically activated inflammatory macrophages (M1) and alternatively activated anti-inflammatory macrophages (M2). It has been generally accepted that M1 macrophages are polarised in an inflammatory environment to produce pro-inflammatory cytokines, whilst M2 macrophages are involved in anti-inflammation and aid tissue repair in wound healing. Bacterial endotoxin (lipopolysaccharide; LPS) is a potent factor in infection, which induces M1 macrophages resulting in higher levels of iNOS, TNFα and IL-12p70 which dictate inflammatory T cell responses. M2 macrophages can be transformed into M1 macrophages following LPS stimulation to promote inflammation. Candida albicans is a commensal fungal microorganism, which has been suggested to induce immune tolerance; however, the mechanism of C. albicans-induced immune tolerance has not been investigated in detail. IL-35 is a recently identified anti-inflammatory cytokine which is a heterodimeric protein consisting of the Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35. IL-35 shares the protein subunit p35, with IL-12p70. IL-12p70 is the most potent cytokine to induce Th1 responses during inflammation. In this study, we demonstrate that heat-killed C. albicans (HKC) strongly suppressed LPS-induced IL-12p70 production in M2 macrophages. Candida albicans induced a high level of EBI3 expression in M2 macrophages, which served as a mechanism for IL-12p70 suppression by competitive binding of the common protein subunit (p35) of IL-35 and IL-12p70. To demonstrate that EBI3 expression had the ability to block IL-12p70 production intracellularly, a Chinese Hamster Ovary (CHO) cell line with biscistronic expression of IL-12p40 and p35 was constructed, followed by ectopic over-expression of EBI3. The over-expression of EBI3 in the IL-12p70 producing cell line effectively suppressed IL-12p70 production. IL-35 secretion was also detected in the cell line, with suppressed IL-12p70 production by immune-precipitation Western blotting. However, this secretion was not evident in M2 macrophages following stimulation by HKC. This can be explained by the constitutive expression of IL-35 receptors (gp130 and IL-12Rß2) in M2 macrophages for cytokine consumption. Our results have indicated that C. albicans can suppress host inflammatory responses in mucosal skin by suppressing LPS-induced IL-12p70 production. Lower IL-12p70 production may avoid an unnecessary Th1 response in order to retain immune tolerance, which may be one of the mechanisms by which C. albicans achieves a successful commensal lifestyle without having a detrimental effect on the host's health.

A review of events that expose children to elemental mercury in the United States: [review] / Uma revisão dos eventos que expõem as crianças ao elemento mercúrio nos Estados Unidos: [revisão]

Concern for children exposed to elemental mercury prompted the Agency for Toxic Substances and Disease Registry and the Centers for Disease Control and Prevention to review the sources of elemental mercury exposures in children, describe the location and proportion of children affected, and make recommendations on how to prevent these exposures. In this review, we excluded mercury exposures from coal-burning facilities, dental amalgams, fish consumption, medical waste incinerators, or thimerosal-containing vaccines. We reviewed federal, state, and regional programs with data on mercury releases along with published reports of children exposed to elemental mercury in the United States. We selected all mercury-related events that were documented to expose (or potentially expose) children. Primary exposure locations were at home, at school, and at others such as industrial property not adequately remediated or medical facilities. Exposure to small spills from broken thermometers was the most common scenario; however, reports of such exposures are declining. The information reviewed suggests that most releases do not lead to demonstrable harm if the exposure period is short and the mercury is properly cleaned up. Primary prevention should include health education and policy initiatives.

Uma preocupação pela exposição de crianças ao elemento mercúrio estimulou a Agência para Substâncias Tóxicas e Registro de Doenças e os Centros para Controle e Prevenção de Doenças a rever as fontes de exposição a este elemento por crianças, descrever a locação e proporção de crianças afetadas e fazer recomendações de como prevenir essas exposições. Nesta análise, foi excluída a exposição a mercúrio em instalações de queima de carvão, amálgamas dentários, consumo de peixes, incineradores de lixo hospitalar ou vacinas contendo timerosal. Analisamos programas regionais, estaduais e federais com dados sobre liberação de mercúrio, juntamente com relatórios de crianças expostas ao elemento nos Estados Unidos. Selecionamos todos os eventos relacionados ao mercúrio que documentaram exposição (ou potencial exposição) de crianças. As principais localidades de exposição foram em casa, na escola e outras como indústrias não adequadas ou instalações médicas. A exposição a pequenos derramamentos de termômetros quebrados foram o cenário mais comum; todavia, relatos de tais exposições estão diminuindo. A informação analisada sugere que a maior parte dos comunicados não conduz a danos demonstráveis se o período de exposição for curto e o mercúrio for devidamente limpo. A prevenção primária deve incluir educação em saúde e iniciativas de políticas.

Human aflatoxin albumin adducts quantitatively compared by ELISA, HPLC with fluorescence detection, and HPLC with isotope dilution mass spectrometry.

Essential to the conduct of epidemiologic studies examining aflatoxin exposure and the risk of heptocellular carcinoma, impaired growth, and acute toxicity has been the development of quantitative biomarkers of exposure to aflatoxins, particularly aflatoxin B(1). In this study, identical serum sample sets were analyzed for aflatoxin-albumin adducts by ELISA, high-performance liquid chromatography (HPLC) with fluorescence detection (HPLC-f), and HPLC with isotope dilution mass spectrometry (IDMS). The human samples analyzed were from an acute aflatoxicosis outbreak in Kenya in 2004 (n = 102) and the measured values ranged from 0.018 to 67.0, nondetectable to 13.6, and 0.002 to 17.7 ng/mg albumin for the respective methods. The Deming regression slopes for the HPLC-f and ELISA concentrations as a function of the IDMS concentrations were 0.71 (r(2) = 0.95) and 3.3 (r(2) = 0.96), respectively. When the samples were classified as cases or controls, based on clinical diagnosis, all methods were predictive of outcome (P < 0.01). Further, to evaluate assay precision, duplicate samples were prepared at three levels by dilution of an exposed human sample and were analyzed on three separate days. Excluding one assay value by ELISA and one assay by HPLC-f, the overall relative SD were 8.7%, 10.5%, and 9.4% for IDMS, HPLC-f, and ELISA, respectively. IDMS was the most sensitive technique and HPLC-f was the least sensitive method. Overall, this study shows an excellent correlation between three independent methodologies conducted in different laboratories and supports the validation of these technologies for assessment of human exposure to this environmental toxin and carcinogen.

Characterisation of the in vitro activity of the depsipeptide histone deacetylase inhibitor spiruchostatin A.

We recently completed the total synthesis of spiruchostatin A, a depsipeptide natural product with close structural similarities to FK228, a histone deacetylase (HDAC) inhibitor (HDI) currently being evaluated in clinical trials for cancer. Here we report a detailed characterisation of the in vitro activity of spiruchostatin A. Spiruchostatin A was a potent (sub-nM) inhibitor of class I HDAC activity in vitro and acted as a prodrug, requiring reduction for activity. Spiruchostatin A was a potent (low nM) inhibitor of the growth of various cancer cell lines. Spiruchostatin A-induced acetylation of specific lysine residues within histones H3 and H4, and increased the expression of p21(cip1/waf1), but did not induce acetylation of alpha-tubulin. Spiruchostatin A also induced cell cycle arrest, differentiation and cell death in MCF7 breast cancer cells. Like FK228, spiruchostatin A was both an inducer and substrate of the ABCB1 drug efflux pump. Whereas spiruchostatin A and FK228-induced protracted histone acetylation, hydroxamate HDI-induced short-lived histone acetylation. Using a subset of HDI-target genes identified by microarray analysis, we demonstrated that these differences in kinetics of histone acetylation between HDI correlated with differences in the kinetics of induction or repression of specific target genes. Our results demonstrate that spiruchostatin A is a potent inhibitor of class I HDACs and anti-cancer agent. Differences in the kinetics of action of HDI may be important for the clinical application of these compounds.

The first biologically active synthetic analogues of FK228, the depsipeptide histone deacetylase inhibitor.

The FK228 and spiruchostatin bicyclic depsipeptide natural products are among the most potent histone deacetylase (HDAC) inhibitors known. Although FK228 is in advanced clinical trials, the complexity of the natural products has precluded mechanistic studies and the discovery of structure-activity relationships. By total synthesis, we have prepared the first depsipeptide analogues. Our results prove that the dehydrobutyrine residue in FK228 is not essential, and other residues can be substituted without loss of HDAC inhibitory activity. Conformational restriction by the macrocyclic scaffold is important, as a linear peptide was inactive. The intramolecular disulfide formed with a cysteine side chain can be removed provided the zinc-binding thiol is protected to ensure good cellular availability. Like the natural products, the analogues are selective against class I isoforms, with nanomolar inhibition of class I HDAC1 and significantly less potency against class II HDAC6.

Effect of phosphate on bacterioferritin-catalysed iron(II) oxidation.

The iron(III) mineral cores of bacterioferritins (BFRs), as isolated, contain a significant component of phosphate, with an iron-to-phosphate ratio approaching 1:1 in some cases. In order to better understand the in vivo core-formation process, the effect of phosphate on in vitro core formation in Escherichia coli BFR was investigated. Iron cores reconstituted in the presence of phosphate were found to have iron-to-phosphate ratios similar to those of native cores, and possessed electron paramagnetic resonance properties characteristic of the phosphate-rich core. Phosphate did not affect the stoichiometry of the initial iron(II) oxidation reaction that takes place at the intrasubunit dinuclear iron-binding sites (phase 2 of core formation), but did increase the rate of oxidation. Phosphate had a more significant effect on subsequent core formation (the phase 3 reaction), increasing the rate up to five-fold at pH 6.5 and 25 degrees C. The dependence of the phase 3 rate on phosphate was complex, being greatest at low phosphate and gradually decreasing until the point of saturation at approximately 2 mM phosphate (for iron(II) concentrations <200 microM). Phosphate caused a significant decrease in the absorption properties of both phase 2 and phase 3 products, and the phosphate dependence of the latter mirrored the observed rate dependence, suggesting that distinct iron(III)-phosphate species are formed at different phosphate concentrations. The effect of phosphate on absorption properties enabled the observation of previously undetected events in the phase 2 to phase 3 transition period.