Structure of racemic duloxetine hydro-chloride

Duloxetine hydro-chloride (trade name Cymbalta) is marketed as a single enanti-omer (S)-N-methyl-3-(naphthalen-1-yl-oxy)-3-(thio-phen-2-yl)propyl-am-in-ium chloride, C₁₈H₂₀NOS⁺·Cl^-, which is twice as effective as the (R)-enanti-omer in serotonin uptake. Here, we report the crystal structure of duloxetine hydro-chloride in its racemic form (space group Pna2₁), where it shows significant differences in the mol-ecular conformation and packing in its extended structure compared to the previously reported (S)-enanti-omer crystal structure. Mol-ecules of this type, comprising aromatic groups with a single side chain terminated in a protonated secondary amine, are commonly found in active anti-depressants. A Cambridge Structural Database survey of mol-ecules with these features reveals a strong correlation between side-chain conformation and the crystal packing: an extended side chain leads to mol-ecules packed into separated layers of hydro-phobic and ionic hydro-philic phases. By comparison, mol-ecules with bent side chains, such as racemic duloxetine hydro-chloride, lead to crystal-packing motifs where an ionic hydro-philic phase is encapsulated within a hydro-phobic shell.

Type 2 diabetes and the clinically normal pulp - An in-vitro study

Aim

The aim of this study was to investigate the effect of type 2 diabetes (T2D) on clinically normal dental pulp tissue by using special stains and immunohistochemistry (IHC) to determine the morphology of the coronal pulp and distribution of immune markers in non‐T2D and T2D groups.

Methodology

Ethics approval for this in vitro pilot study was obtained from the University of Otago Human Ethics Committee (16/069). Twenty extracted permanent molar teeth diagnosed as having clinically normal pulp status were collected. Ten teeth were from participants with well‐controlled T2D and ten from participants without diabetes (non‐T2D). Each tooth was sectioned transversely at the cemento‐enamel junction before the crowns were decalcified and embedded in paraffin. Sections were stained with haematoxylin and eosin, Massons trichrome, and van Gieson stains for histological and morphological evaluation. IHC using anti‐CD4, anti‐CD68 and anti‐CD83 and anti‐IL1β, anti‐IL6, anti‐IL17, anti‐TNF‐α, anti‐TLR2, anti‐TLR4 and anti‐FOXP3 identified proteins of interest. Qualitative and semi‐quantitative analyses evaluated the morphology of the dental pulp and protein expression. Data analyses were performed with GraphPad Prism, using Student's t‐test and multiple regression using SPSS at p < .05.

Results

Special stains demonstrated morphological differences in the T2D dental pulp compared with non‐T2D. Qualitative analysis indicated that the pulp in the T2D samples was consistently less cellular, less vascular, showed evidence of thickened blood vessel walls, increased pulp calcification and collagen deposition. Semi‐quantitative analysis of IHC samples showed the T2D pulp had significantly increased expression of macrophage and dendritic cell markers CD68 (p < .001) and CD83 (p = .04), and there was significantly greater expression of inflammatory cytokines IL1β (p = .01), IL6 (p < .0001), IL17 (p < .0001) and TNF‐α (p = .01). T2D samples showed a significant increase in markers of innate inflammation, TLR2 (p < .001) and TLR4 (p < .001) and decreased expression of regulatory T‐cell marker, FOXP3 (p = .01). Multiple regression showed that age‐corrected differences were statistically significant.

Conclusion

Preliminary findings suggest that T2D may exert a similar response in the pulp to complications in other body sites. Hyperglycaemia is associated with changes in the morphology of the clinically normal dental pulp with altered immune cell and cytokine expression.

Potential application of immunotherapy for modulation of pulp inflammation: opportunities for vital pulp treatment

Caries results in the demineralization and destruction of enamel and dentine, and as the disease progresses, irreversible pulpitis can occur. Vital pulp therapy (VPT) is directed towards pulp preservation and the prevention of the progression of inflammation. The outcomes of VPT are not always predictable, and there is often a poor correlation between clinical signs and symptoms, and the events occurring at a molecular level. The inflamed pulp expresses increased levels of cytokines, including tumour necrosis factor (TNF)-α, interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-8, IL-17 and IL-23, which recruit and drive a complex cellular immune response. Chronic inflammation and sustained cytokine release can result in irreversible pulp damage and a decreased capacity for tissue healing. Other chronic inflammatory diseases, such as psoriasis, inflammatory bowel diseases and rheumatoid arthritis, are also characterized by an dysregulated immune response composed of relatively high cytokine levels and increased numbers of immune cells along with microbial and hard-soft tissue destructive pathologies. Whilst anti-cytokine therapies have been successfully applied in the treatment of these diseases, this approach is yet to be attempted in cases of pulp inflammation. This review therefore focuses on the similarities in the aetiology between chronic inflammatory diseases and pulpitis, and explores how anti-cytokine therapies could be applied to manage an inflamed pulp and facilitate healing. Further proof-of-concept studies and clinical trials are justified to determine the effectiveness of these treatments to enable more predictable outcomes in VPT.

Advanced characterization of biomineralization at plaque layer and inside rice roots amended with iron- and silica-enhanced biochar

Application of iron (Fe)- and silica (Si)-enhanced biochar compound fertilisers (BCF) stimulates rice yield by increasing plant uptake of mineral nutrients. With alterations of the nutrient status in roots, element homeostasis (e.g., Fe) in the biochar-treated rice root was related to the formation of biominerals on the plaque layer and in the cortex of roots. However, the in situ characteristics of formed biominerals at the micron and sub-micron scale remain unknown. In this study, rice seedlings (Oryza sativa L.) were grown in paddy soil treated with BCF and conventional fertilizer, respectively, for 30 days. The biochar-induced changes in nutrient accumulation in roots, and the elemental composition, distribution and speciation of the biomineral composites formed in the biochar-treated roots at the micron and sub-micron scale, were investigated by a range of techniques. Results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) showed that biochar treatment significantly increased concentrations of nutrients (e.g., Fe, Si, and P) inside the root. Raman mapping and vibrating sample magnetometry identified biochar particles and magnetic Fe nanoparticles associated with the roots. With Fe plaque formation, higher concentrations of FeO_x^- and FeO_xH^- anions on the root surface than the interior were detected by time-of-flight secondary ionization mass spectrometry (ToF-SIMS). Analysis of data from scanning electron microscopy energy-dispersive spectroscopy (SEM-EDS), and from scanning transmission electron microscopy (STEM) coupled with EDS or energy electron loss spectroscopy (EELS), determined that Fe(III) oxide nanoparticles were accumulated in the crystalline fraction of the plaque and were co-localized with Si and P on the root surface. Iron-rich nanoparticles (Fe-Si nanocomposites with mixed oxidation states of Fe and ferritin) in the root cortex were identified by using aberration-corrected STEM and in situ EELS analysis, confirming the biomineralization and storage of Fe in the rice root. The findings from this study highlight that the deposition of Fe-rich nanocomposites occurs with contrasting chemical speciation in the Fe plaque and cortex of the rice root. This provides an improved understanding of the element homeostasis in rice with biochar-mineral fertilization.

Synthetic Bilayers on Mica from Self-Assembly of Hydrogen-Bonded Triazines

This study describes organic thin films prepared under a range of conditions from a model series of bis-N-alkyl chloro-triazines functionalized with short alkyl chains from ethyl to hexyl. The pure films were characterized using atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). When cast on mica, these compounds assemble as crystalline sheets made up of a synthetic bilayer along the crystallographic ab-plane with an internal hydrogen-bonded domain between external alkyl chains. These micron-scale surfaces stack along the c-axis, and increasing the alkyl chain length results in changes to the crystal morphology from needles to nanoscale plates. Thicker films produce nanoscale, pyramidal stacks of bilayers. Compared to atomically flat mica, a rougher, unetched silicon substrate produced irregular domains in the secondary bilayer. Films of mixtures comprising the ethyl derivative with butyl, pentyl, or hexyl derivative were imaged using time-of-flight secondary-ion mass spectrometry (ToF-SIMS) that indicated a trend toward a constant stoichiometry with increasing alkyl chain length. AFM of mixed films on mica showed single bilayers of height <2 nm, with an acceptable correlation to the XRD measurements, supporting a constant stoichiometry. These materials permit easy modification of mica to a micron-scale, atomically flat hydrophobic surface, and the use of mixtures with different alkyl chain lengths suggests a method to improve the quality of functional organic thin films.

Anthranilamide-based Short Peptides Self-Assembled Hydrogels as Antibacterial Agents

In this study, we describe the synthesis and molecular properties of anthranilamide-based short peptides which were synthesised via ring opening of isatoic anhydride in excellent yields. These short peptides were incorporated as low molecular weight gelators (LMWG), bola amphiphile, and C3-symmetric molecules to form hydrogels in low concentrations (0.07-0.30% (w/v)). The critical gel concentration (CGC), viscoelastic properties, secondary structure, and fibre morphology of these short peptides were influenced by the aromaticity of the capping group or by the presence of electronegative substituent (namely fluoro) and hydrophobic substituent (such as methyl) in the short peptides. In addition, the hydrogels showed antibacterial activity against S. aureus 38 and moderate toxicity against HEK cells in vitro.

FoxP3+ regulatory T cells, interleukin 17 and mast cells in chronic inflammatory periodontal disease

BACKGROUND AND OBJECTIVE

T cells are known to play a pivotal role in periodontal disease; however, less is known about the T-helper subsets of regulatory T cells (Tregs) and Th17 cells. The aim of this study was to investigate the cell types expressing FoxP3 and interleukin (IL)-17A within periodontal disease tissues and to determine gene and protein expression profiles associated with periodontitis.

MATERIAL AND METHODS

A total of 10 healthy/gingivitis and 10 chronic periodontitis tissues were investigated. Immunohistochemistry and immunofluorescence techniques were used to identify the FoxP3 and IL17-positive cells and to determine the cell types respectively. Gene expression was determined using semi-quantitative polymerase chain reaction array technology that allowed the analysis of 84 pathway-focused genes known to be associated with Tregs and Th17 cells. Transforming growth factor (TGF)-β1, IL10 and IL17A protein levels were determined using enzyme-linked immunosorbent assay.

RESULTS

Double immunofluorescence labeling revealed that all FoxP3⁺ cells were CD4⁺ , while IL17⁺ cells were neither CD4⁺ nor CD8⁺ but were tryptase⁺ , suggestive of mast cells. More FoxP3⁺ cells than IL17⁺ cells were found in all the tissues examined and overall there were few IL17⁺ cells. Statistically significant increases in gene expression were found for STAT5A, STAT3, SOCS1, TGFβ1 and IL10 in the chronic periodontitis specimens predominantly infiltrated with B cells and plasma cells when compared with healthy/gingivitis specimens predominantly infiltrated with T cells. Protein analysis demonstrated higher levels of the TGFβ1 and IL10 cytokines in periodontitis tissues and in B-cell and plasma cell predominant gingival tissues than in healthy/gingivitis tissues and T-cell predominant gingival tissues. IL17A gene and protein expression was not detected in any of the tissues.

CONCLUSION

Based on the findings of this study, we suggest that the source of low levels of IL17A in periodontal tissues is mast cells not Th17 cells and that Tregs may have a more prominent role in the pathogenesis of periodontal disease than Th17 cells.

Microstructural and associated chemical changes during the composting of a high temperature biochar: Mechanisms for nitrate, phosphate and other nutrient retention and release

Recent studies have demonstrated the importance of the nutrient status of biochar and soils prior to its inclusion in particular agricultural systems. Pre-treatment of nutrient-reactive biochar, where nutrients are loaded into pores and onto surfaces, gives improved yield outcomes compared to untreated biochar. In this study we have used a wide selection of spectroscopic and microscopic techniques to investigate the mechanisms of nutrient retention in a high temperature wood biochar, which had negative effects on Chenopodium quinoa above ground biomass yield when applied to the system without prior nutrient loading, but positive effects when applied after composting. We have compared non-composted biochar (BC) with composted biochar (BCC) to elucidate the differences which may have led to these results. The results of our investigation provide evidence for a complex series of reactions during composting, where dissolved nutrients are first taken up into biochar pores along a concentration gradient and through capillary action, followed by surface sorption and retention processes which block biochar pores and result in deposition of a nutrient-rich organomineral (plaque) layer. The lack of such pretreatment in the BC samples would render it reactive towards nutrients in a soil-fertilizer system, making it a competitor for, rather than provider of, nutrients for plant growth.

Glyoxylamide-based self-assembly hydrogels for sustained ciprofloxacin delivery

Glyoxylamide-based hydrogels have high ciprofloxacin (CIP) loading capacity and demonstrate a sustained release profile of over 15 days.

Controlling the distance between hydrogen-bonded chloro-s-triazine tapes: crystal engineering using N-alkyl chains and the influence of temperature

Precise control of tape spacing in hydrogen-bonded alkyl-chain substituted chloro-s-triazines is demonstrated at 150–298 K, with some unexpected behaviour from the odd-number carbon derivatives.

Polymorphs of Neutral Red, a Redox-Mediating Phenazine in Biological Systems

Neutral red 1 is a heterocyclic phenazine that, as a crystalline solid, has been observed to accelerate microbial methane generation from coal. Scale-up to an industrial process will require large quantities of neutral red crystals, hence an understanding of any polymorphic behaviour is essential for careful control of this process. A room-temperature structure of 1 (Form I) has been reported previously, and this study describes a new polymorph (Form II) crystallising from aqueous solution at 50°C, or transforming from Form I over an incubation time of one week at 70°C. Single-crystal X-ray diffraction has been used to study the molecular arrangements and intermolecular interactions in the new polymorph, and compared with those found in the room temperature form. Both polymorphs have been characterised using Raman and infrared spectroscopy, and a synthetic mixture of polymorphs successfully imaged using Raman spectroscopy. Raman imaging is proposed as a quality control method for small quantities of sample to ensure the correct polymorph is produced as a feedstock for this new methanogenesis process.

Preliminary findings from the Oranga Niho dental student outplacement project

OBJECTIVES

To examine stakeholder perspectives of the Bachelor of Dental Surgery 2012-2013 clinical outplacement programme with Māori Oral Health Providers (MOHPs) and inform the programme's ongoing development.

DESIGN

A mixed methods kaupapa Māori action research project.

SETTING

Six North Island MOHPs and the University of Otago Faculty of Dentistry.

PARTICIPANTS AND METHODS

Online questionnaires were used to conduct a pre- and post-outplacement survey of dental students and a twice-yearly survey of all MOHP-based clinical supervisors. Paper questionnaires were used to survey adult clients and caregivers of child clients that the students treated. Data were analysed descriptively and thematically.

MAIN OUTCOME MEASURES

68 (61%) of the 112 eligible students completed the pre- and post-outplacement questionnaires; 31 clinical supervisor questionnaire responses were received representing all six MOHPs; and 426 client and 130 caregiver questionnaire responses were received from five MOHPs.

RESULTS

79% of students felt well prepared for outplacement and 75% indicated that they would consider working for a MOHP in future. Of the clinical supervisors, 93% indicated that the students were adequately prepared for outplacement, and 68%, that they would recommend one or more students for employment. However, 58% associated the outplacements with decreased productivity. More than 97% of adult clients and caregivers of child clients were pleased with the care that the students provided.

CONCLUSION

Recommendations for strengthening the outplacement programme included: increasing communication between the Faculty, MOHPs and students; addressing the financial cost of the programme to the MOHPs; and providing more support for clinical supervisors.

α-Hemoglobin-stabilizing protein (AHSP) perturbs the proximal heme pocket of oxy-α-hemoglobin and weakens the iron-oxygen bond

α-Hemoglobin (αHb)-stabilizing protein (AHSP) is a molecular chaperone that assists hemoglobin assembly. AHSP induces changes in αHb heme coordination, but how these changes are facilitated by interactions at the αHb·AHSP interface is not well understood. To address this question we have used NMR, x-ray absorption spectroscopy, and ligand binding measurements to probe αHb conformational changes induced by AHSP binding. NMR chemical shift analyses of free CO-αHb and CO-αHb·AHSP indicated that the seven helical elements of the native αHb structure are retained and that the heme Fe(II) remains coordinated to the proximal His-87 side chain. However, chemical shift differences revealed alterations of the F, G, and H helices and the heme pocket of CO-αHb bound to AHSP. Comparisons of iron-ligand geometry using extended x-ray absorption fine structure spectroscopy showed that AHSP binding induces a small 0.03 Å lengthening of the Fe-O2 bond, explaining previous reports that AHSP decreases αHb O2 affinity roughly 4-fold and promotes autooxidation due primarily to a 3-4-fold increase in the rate of O2 dissociation. Pro-30 mutations diminished NMR chemical shift changes in the proximal heme pocket, restored normal O2 dissociation rate and equilibrium constants, and reduced O2-αHb autooxidation rates. Thus, the contacts mediated by Pro-30 in wild-type AHSP promote αHb autooxidation by introducing strain into the proximal heme pocket. As a chaperone, AHSP facilitates rapid assembly of αHb into Hb when βHb is abundant but diverts αHb to a redox resistant holding state when βHb is limiting.

Thermodynamics of Zn2+ binding to Cys2His2 and Cys2HisCys zinc fingers and a Cys4 transcription factor site

The thermodynamics of Zn(2+) binding to three peptides corresponding to naturally occurring Zn-binding sequences in transcription factors have been quantified with isothermal titration calorimetry (ITC). These peptides, the third zinc finger of Sp1 (Sp1-3), the second zinc finger of myelin transcription factor 1 (MyT1-2), and the second Zn-binding sequence of the DNA-binding domain of glucocorticoid receptor (GR-2), bind Zn(2+) with Cys(2)His(2), Cys(2)HisCys, and Cys(4) coordination, respectively. Circular dichroism confirms that Sp1-3 and MyT1-2 have considerable and negligible Zn-stabilized secondary structure, respectively, and indicate only a small amount for GR-2. The pK(a)'s of the Sp1-3 cysteines and histidines were determined by NMR and used to estimate the number of protons displaced by Zn(2+) at pH 7.4. ITC was also used to determine this number, and the two methods agree. Subtraction of buffer contributions to the calorimetric data reveals that all three peptides have a similar affinity for Zn(2+), which has equal enthalpy and entropy components for Sp1-3 but is more enthalpically disfavored and entropically favored with increasing Cys ligands. The resulting enthalpy-entropy compensation originates from the Zn-Cys coordination, as subtraction of the cysteine deprotonation enthalpy results in a similar Zn(2+)-binding enthalpy for all three peptides, and the binding entropy tracks with the number of displaced protons. Metal and protein components of the binding enthalpy and entropy have been estimated. While dominated by Zn(2+) coordination to the cysteines and histidines, other residues in the sequence affect the protein contributions that modulate the stability of these motifs.

Does performance in selection processes predict performance as a dental student?

OBJECTIVE

This study investigated associations between the performance of dental students in each of the three components of the selection procedure [academic average, Undergraduate Medicine and Health Sciences Admission Test (UMAT) and structured interview], socio-demographic characteristics and their academic success in an undergraduate dental surgery programme.

MATERIALS AND METHODS

Longitudinal review of admissions data relating to students entering dental education at the University of Otago, New Zealand, between 2004 and 2009 was compared with academic performance throughout the dental programme.

RESULTS AND DISCUSSION

After controlling for variables, pre-admission academic average, UMAT scores and interview performance did not predict performance as a dental student. Class place in second year, however, was a strong predictor of class place in final year. Multivariate analysis demonstrated that the best predictors of higher class placement in the final year were New Zealand European ethnicity and domestic (rather than international) student status. Other socio-demographic characteristics were not associated with performance. These interim findings provide a sound base for the ongoing study.

CONCLUSION

The study found important socio-demographic differences in pre-admission test scores, but those scores did not predict performance in the dental programme, whether measured in second year or in final year.

Antigen recognition and presentation in periapical tissues: a role for TLR expressing cells?

Bacteria are the prime cause of periapical diseases and root canal microbiology is a well-researched area of endodontics. Antigen-presenting cells (APCs) are present in periapical lesions of endodontic origin and play a substantial role in recognizing, processing and presenting pathogenic antigens to the adaptive immune system such as an effective and long-lasting immune response is generated against the specific pathogens. Toll-like receptors (TLRs) are germ-line encoded pathogen recognition receptors (PRR) expressed by various APCs which induce their maturation, lead to gene transcription in the nucleus and the production of several pro- and anti-inflammatory cytokines. Thirteen TLRs have been discovered, 10 of which have been identified in humans so far. Preliminary studies of dental pulp tissue have demonstrated various cell types expressing different TLRs in response to commonly encountered microorganisms. However, there is little information available regarding the expression and function of the various TLRs in human periapical lesions. This review discusses the interactions of various APCs in periapical lesions and the possible roles of different TLRs and APCs in pulp/periapical pathogen recognition and presentation to the adaptive immune system in the initiation and sustaining of periapical diseases.

Calibre-persistent labial artery: often misdiagnosed as a mucocoele

The authors present five cases of calibre-persistent labial artery (CPLA) all of which were diagnosed clinically as a labial mucocoele. The purpose of this article is to bring this rarely reported lesion to the attention of clinicians.

Stimulus-response coupling in sponge cell aggregation: Evidence for calcium as an intracellular messenger

Aggregation of dissociated sponge cells has been proposed as a model for cell-cell recognition mediated by a specific proteoglycan aggregation factor (Microciona aggregation factor). To test whether sponge cells undergo stimulus-response coupling in which intracellular Ca is a messenger, aggregation of mechanically dissociated cells was studied. Changes in light transmission through cell suspensions paralleled aggregation as judged by microscopy. In the presence, but not absence, of Ca (>5 mM) partially purified Microciona aggregation factor aggregated both living and glutaraldehyde-fixed cells. Evidence for a messenger role of Ca was the following: (i) Addition of Ca to Ca-depleted cells induced aggregation that varied with [Ca]. (ii) Addition of Ca ionophores (A23187 and ionomycin) caused aggregation that varied with [Ca] and far exceeded that provoked by Ca alone. Glutaraldehyde-fixed cells did not respond to ionophores with or without Ca. (iii) Calcium antagonists inhibited aggregation. These included inhibitors of the Ca-calmodulin complex (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride and 1-[bis(p-chlorophenyl)methyl]-3-[2,4-dichloro-beta-(2,4-dichlorobenzyloxyl)phenylethyl]imidazolinium chloride), Ca channel blockers (La, Co, Cd, and verapamil), and three nonsteroidal anti-inflammatory agents (indomethacin, ibuprofen, and piroxicam). Results indicated not only that early events of sponge aggregation can be quantified by continuous recording but that aggregation is not simply due to passive agglutination of inert cells by an extracellular proteoglycan. Rather, sponge cells recognize surface ligands to which they respond by Ca-dependent stimulus-response coupling.

An unusual presentation of oropharyngeal mucosal plasmacytosis related to toothpaste

OBJECTIVE

We present the case of a 59-year-old Chinese patient with an unusual presentation of mucosal plasmacytosis involving the oropharynx, related to the use of toothpaste.

METHOD

Case presentation and review of English medical literature involving mucosal plasmacytosis.

RESULTS

Mucosal plasmacytosis is an uncommon disease process and has been associated with hypersensitivity reactions. Most cases involve the gingival mucosa, although there have been reports of cases involving other oral mucosal sites and the upper aerodigestive tract. Our case provides an example of oropharyngeal plasmacytosis related to toothpaste. A resolution of signs and symptoms followed withdrawal of the suspected allergens.

CONCLUSION

Mucosal plasmacytosis is a benign inflammatory process that may appear to be more sinister on clinical examination. Skin patch testing is a useful adjunct in confirming the diagnosis.

Thermodynamics of the As(III)-thiol interaction: arsenite and monomethylarsenite complexes with glutathione, dihydrolipoic acid, and other thiol ligands

Colorimetric (near-UV absorption spectroscopy) and calorimetric (isothermal titration calorimetry) methods have been used to quantify the equilibrium and thermodynamics of arsenite and monomethylarsenite (MMA) coordinating to glutathione (GSH) and the dithiols dimercaptosuccinic acid (DMSA), dihydrolipoic acid (DHLA), and dithiothreitol (DTT). We found that both arsenite and MMA form moderately stable complexes (beta = 10(6)-10(7)) with GSH; that arsenite forms a particularly stable 2:3 complex (beta approximately 10(18)) with the biological cofactor DHLA; that MMA has a somewhat higher affinity than arsenite for thiol ligands; and that entropic factors modulate the overall stability of As(III) complexes with thiols, which are favored by the exothermic formation of As(III)-thiolate bonds. The implications of these results for arsenic toxicity are discussed.

Molecular Mechanism of AHSP-Mediated Stabilization of α-Hemoglobin

Hemoglobin A (HbA), the oxygen delivery system in humans, comprises two alpha and two beta subunits. Free alpha-hemoglobin (alphaHb) is unstable, and its precipitation contributes to the pathophysiology of beta thalassemia. In erythrocytes, the alpha-hemoglobin stabilizing protein (AHSP) binds alphaHb and inhibits its precipitation. The crystal structure of AHSP bound to Fe(II)-alphaHb reveals that AHSP specifically recognizes the G and H helices of alphaHb through a hydrophobic interface that largely recapitulates the alpha1-beta1 interface of hemoglobin. The AHSP-alphaHb interactions are extensive but suboptimal, explaining why beta-hemoglobin can competitively displace AHSP to form HbA. Remarkably, the Fe(II)-heme group in AHSP bound alphaHb is coordinated by the distal but not the proximal histidine. Importantly, binding to AHSP facilitates the conversion of oxy-alphaHb to a deoxygenated, oxidized [Fe(III)], nonreactive form in which all six coordinate positions are occupied. These observations reveal the molecular mechanisms by which AHSP stabilizes free alphaHb.

Epithelial-mesenchymal interactions in experimental oral mucosal carcinogenesis

In an effort to come to a better understanding of human oral mucosal carcinogenesis, an animal model was used in which the carcinogen 4-nitroquinoline-1-oxide was applied to rat palatal mucosa for varying periods of time. Histological and histometric analyses showed that there were quantifiable differences in the palatal epithelium to which carcinogen had been applied in comparison with control tissue. Tissue recombination experiments, using various combinations of the palatal mucosa and analysed after recovery from transplantation to hypothymic BALB/c mice, showed that control epithelium recombined with connective tissue from carcinogen-treated mucosa was altered, indicating that the underlying connective tissue modified histomorphological aspects of the epithelium in the later stages of carcinogenesis.

Determination of the structures of antiinflammatory copper(II) dimers of indomethacin by multiple-scattering analyses of X-ray absorption fine structure data

Copper K-edge X-ray absorption spectroscopic (XAS) measurements were recorded for the veterinary antiinflammatory Cu(II) complexes of indomethacin (1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid = IndoH), of the general formula [Cu(2)(Indo)(4)L(2)] (L = N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-methylpyrrolidone (NMP), and water), and [Cu(2)(OAc)(4)(OH(2))(2)] at room temperature and 10 K. The bond lengths and bridging O-C-O angles of the dimeric Cu(II) cage (Cu(2)O(10)C(8)) obtained from the multiple-scattering (MS) fitting of the X-ray absorption fine structure (XAFS) using a centrosymmetric model of [Cu(2)(Indo)(4)(DMF)(2)] gave Cu.Cu = 2.62(2) A, mean Cu-O(Ac) = 1.95(2) A, Cu-O(L) = 2.15(2) A, bridging O-C-O = 125(1) degrees, Cu displacement from plane 0.19 A compared with the XRD data Cu.Cu = 2.630(1) A, mean Cu-O(Ac) = 1.959 A, Cu-O(L) = 2.143(5) A, bridging O-C-O angles = 123.2(5) degrees, Cu displacement from plane 0.20 A. The excellent agreement between the XAFS- and XRD-derived data allowed the structures of related [Cu(2)(Indo)(4)L(2)] (L = DMA, NMP) complexes to be determined. All display a similar Cu(2)O(10)C(8) coordination geometry, which is independent of the nature of the axial ligand. While XAFS analysis of [Cu(2)(Indo)(4)(OH(2))(2)] and [Cu(2)(OAc)(4)(OH(2))(2)] indicates a coordination geometry similar to that of [Cu(2)(Indo)(4)L(2)] (L = DMF, DMA, NMP), removal of symmetry restraints in the MS model is required to obtain axial bond lengths comparable to those derived in the XRD structures of the acetate complex. For the Indo complex, the fitted bond lengths with the lower symmetry model give a mean Cu-L(OH2) bond distance within experimental errors of the value for [Cu(2)(Indo)(4)(DMSO)(2)] (2.16(2) A) (XRD). The difficulty in refining the Cu-O(OH2) distance of [Cu(2)(OAc)(4)(OH(2))(2)] and [Cu(2)(Indo)(4)(OH(2))(2)] using a centrosymmetric MS model is attributed to a symmetry reduction due to hydrogen-bonding effects characteristic of the aqua adducts, as is observed in the XRD structure of the acetate complex.

Photosynthetic water oxidation: towards a mechanism

This mini-review outlines the current theories on the mechanism of electron transfer from water to P680, the location and structure of the water oxidising complex and the role of the manganese cluster. We discuss how our data fit in with current theories and put forward our ideas on the location and mechanism of water oxidation.

Tongue lesions: what can it be?

In the course of the examination of a patient their tongue is easily visualized and with the use of gauze can be gently dried, held with gauze and stretched for inspection of all aspects. This can be followed by palpation of both the tongue and the floor of mouth. In this manner, any altered tissue is likely to be detected and, with or without further investigations, a diagnosis established. Appropriate management can then be undertaken. A wide range of conditions may involve the tongue and this article outlines some of these using a classification based on aetiology.

Evidence for the presence of a component of the Mn complex of the photosystem II reaction centre which is exposed to water in the S(2) state of the water oxidation complex

The interaction of water oxidising photosystem II preparations with the aqueous environment has been investigated using electron spin echo envelope modulation spectroscopy in the presence of 2H(2)O. The spectra show interaction of 2H of 2H(2)O with the preparation in the S(2) state. The component interacting with water decays during 1-4 weeks storage at 77 K. No interaction of water with the classical multiline S(2) Mn signal, which is more stable on storage at 77 K, was detected. The results show that a component of the water oxidation complex, possibly involving the Mn centre, is accessible to water and may be the water binding site for photosynthetic water oxidation.

Determination of Fe-ligand bond lengths and the Fe-N-O bond angles in soybean ferrous and ferric nitrosylleghemoglobin a using multiple-scattering XAFS analyses

The NO adducts of leghemoglobin (Lb) are implicated in biological processes, but only the adduct with ferrous Lb (Lb(II)NO) has been characterized previously. We report the first characterization of ferric nitrosylleghemoglobin (Lb(III)NO) and XAS experiments performed on frozen aqueous solutions of Lb(II)NO and Lb(III)NO at 10 K. The XANES and electronic spectra of the NO adducts are similar in shape and energies to the myoglobin (Mb) analogues. The environment of the Fe atom has been refined using multiple-scattering (MS) analyses of the XAFS data. For Lb(II)NO, the MS analysis resulted in an averaged Fe-N(p)(pyrrole) distance of 2.02 A, an Fe-N(epsilon)(imidazole) distance of 1.98 A, an Fe-N(NO) distance of 1.77 A, and an Fe-N-O angle of 147 degrees. The Fe-N(NO) distance and Fe-N-O angle obtained from the analysis of Lb(II)NO are in good agreement with those determined crystallographically for [Fe(TPP)(NO)] (TPP, tetraphenylporphyrinato), with and without 1-methylimidazole (1-MeIm) as the sixth ligand, and the MS XAFS structures reported previously for the myoglobin (Mb(II)NO) analogue and [Fe(TPP)(NO)]. The MS analysis of Lb(III)NO yielded an average Fe-N(p) distance of 2.00 A, an Fe-N(epsilon) distance of 1.89 A, an Fe-N(NO) distance of 1.68 A, and an Fe-N-O angle of 173 degrees. These bond lengths and angles are consistent with those determined previously for the myoglobin analogue (Mb(III)NO) and the crystal structures of the model complexes, [Fe(III)(TPP)(NO)(OH(2))](+) and [Fe(OEP)(NO)](+) (OEP, octaethylporphyrinato). The final XAFS R values were 16.1 and 18.2% for Lb(II)NO and Lb(III)NO, respectively.

p53 expression in oral precancer and cancer

Expression of the p53 tumour suppressor gene is a frequent finding in human malignancies, including oral cancer, and it has been detected in some potentially malignant lesions. The results of the present project showed that 35 of the 41 (85 per cent) oral mucosal lesions with histological evidence of epithelial dysplasia expressed p53, but the presence or absence of p53 staining could not be used to predict the outcome of potentially malignant oral mucosal lesions.

Verruciform xanthoma and concomitant lichen planus of the oral mucosa. A report of three cases

Verruciform xanthomas are benign muco-cutaneous lesions of unknown aetiology. They have a papillated surface and histologically they are characterised by the presence of foam cells in connective tissue papillae between elongated parakeratinised epithelial rete ridges. Three cases are reported in which oral mucosal verruciform xanthoma and oral mucosal lichen planus occurred concomitantly.

Expression of p53 in oral mucosal hyperplasia, dysplasia and squamous cell carcinoma

OBJECTIVE

To assess p53 expression in a range of oral mucosal lesions and to relate the results to the clinical outcome in patients with dysplastic oral mucosal lesions and oral squamous cell carcinomas (OSCC).

MATERIALS AND METHODS

Archival tissue was available for eight cases of normal oral mucosa, 50 cases of oral mucosal hyperplasia, 41 cases of oral mucosal dysplasia and 48 cases of OSCC. The monoclonal antibody DO-7, reactive to p53 protein, was applied to paraffin-embedded sections using microwave pretreatment and immunohistochemical techniques.

RESULTS

The results showed that normal oral mucosa did not express p53. Positive nuclear staining was found in 18/50 (36%) cases of hyperplasia, 35/41 (85%) cases of dysplasia and 45/48 (94%) cases of OSCC. None of the p53 negative dysplasias progressed, while 19% of p53 positive cases of dysplasia recurred following excision and 11% of the cases underwent neoplastic transformation. Five out of 10 (50%) cases of severe dysplasia which were p53 positive resolved.

CONCLUSION

The proportion of cases with positive p53 expression increased from hyperplasia to dysplasia to OSCC. These results may indicate an involvement of p53 in neoplastic transformation as well as in proliferative events although the presence or absence of p53 staining could not be used to predict the outcome of potentially malignant oral mucosal lesions.

Expression of c-erbB-2 protein in keratinocytes of oral mucosal lichen planus and subsequent squamous cell carcinoma

Oral mucosal lichen planus (OMLP) is a well recognized mucosal disease with unknown etiology. Considerable controversy exists as to whether OMLP is intrinsically premalignant, or if the disorder facilitates the development of oral mucosal squamous cell carcinoma (OMSCC) by external factors. The aim of the present study was to investigate the expression of c-erbB-2 protein in the keratinocytes of initial biopsies or oral mucosal disorders diagnosed as OMLP with no evidence of epithelial dysplasia, and to compare the results with the expression of c-erbB-2 protein in subsequent biopsies obtained from the same patients. These results were compared with the findings from control groups (patients with dysplasia with no evidence of OMLP, patients with OMSCC with no evidence of OMLP and normal oral mucosa). The expression of the c-erbB-2 protein was evaluated by immunohistochemical staining of the gene product with the avidin-biotin-complex method using paraffin-embedded tissues sections. Five of the initial biopsies from patients with OMLP expressed the c-erbB-2 protein and one did not. None of the OMLP cases that subsequently showed evidence of dysplasia expressed the c-erbB-2 protein, and of the three OMSCC specimens from the patients with OMLP, two were negative and one expressed c-erbB-2 protein. The specimens from the control groups all expressed the c-erbB-2 protein. The results indicated the probability of the absence of c-erbB-2 staining being an indication of a potential for neoplastic transformation in OMLP with dysplastic changes.

Nuclear morphometry in experimental oral mucosal carcinogenesis

The area, perimeter and diameter of basal cell nuclei of rat palatal epithelium were measured and the deviation of the basal cell nuclear profile from the form of a sphere was assessed after the application of the carcinogen 4-nitroquinoline-1-oxide (4NQO). After a 24-week treatment-free period, designed to eliminate the irritant effect of the carcinogen, the rats were killed, the palatal mucosa was recovered and processed and the nuclear histometry was assessed with image analysis techniques. The basal cell nuclear area increased as the epithelium became dysplastic and then decreased as carcinoma developed, but there were significant variations in this parameter in the control groups. Basal cell nuclei from moderately or severely dysplastic epithelium, and from epithelium adjacent to areas of invasive carcinoma, were significantly less regular in profile by comparison with control nuclei. Variations in nuclear profile, but not nuclear area, perimeter or diameter, might reflect fundamental nuclear alterations of significance during the process of carcinogenesis.

Studies of the inflammatory process and malignant potential of oral mucosal lichen planus

Oral mucosal lichen planus (OMLP) is a well recognized mucosal disease with unknown aetiology. Considerable controversy exists as to whether OMLP is intrinsically premalignant, or if the disorder facilitates the development of oral mucosal squamous cell carcinoma (OMSCC) by external factors. The aim of the present studies was to investigate the expression of c-erbB-2 protein in the keratinocytes of the initial biopsies of oral mucosal disorders diagnosed as OMLP with no evidence of epithelial dysplasia and to compare the results with the expression of c-erbB-2 protein in subsequent biopsies obtained from the same patients. These results were compared with the findings from another 26 biopsies from patients with OMLP and control groups (patients with dysplasia with no evidence of OMLP, patients with OMSCC with no evidence of OMLP and normal oral mucosa). The expression of the c-erbB-2 protein was evaluated by immunohistochemical staining of the gene product with the avidin-biotin-complex method using both fresh frozen and paraffin-embedded tissue sections. Five of the initial biopsies from patients with OMLP expressed the c-erbB-2 protein and one did not. None of the OMLP cases that subsequently showed evidence of dysplasia expressed the c-erbB-2 protein and of the OMSCC specimens from the patients with OMLP, 2 were negative and 1 expressed c-erbB-2 protein. Within the other group of OMLP specimens 3 (3/26) were negative for c-erbB-2 staining. The specimens from the control groups all expressed the c-erbB-2 protein. The results indicated the probability of the absence of c-erbB-2 staining being an indication of a potential for neoplastic transformation in OMLP with dysplastic changes.

Induction by 4-nitroquinoline-1-oxide of oral epithelial dysplasia and neoplasia in scurvy-prone osteogenic disorder Shionogi (ODS) rats

Carcinogenesis by 4-nitroquinoline-1-oxide (NQO) in the oral mucosa is a reliable method of obtaining oral mucosal squamous cell carcinoma (OMSCC) and allows examination of various stages of oral cancer development. In vivo and in vitro studies have indicated that L-ascorbic acid (AA) may have a role in cancer prevention. The Wistar "scurvy-prone" osteogenic disorder Shionogi (ODS) rat of the od/od substrain is unable to synthesize AA and requires supplementation for its survival. This study examined the effects of NQO on the oral mucosa of ODS and outbred Wistar rats. NQO (0.5%) was applied topically to the palatal mucosa of 72 male ODS and 36 outbred Wistar rats three times weekly for 4, 8, 12, 16, 20, and 24 wks. The ODS rats were divided so that 36 rats were given 2.5 g/l AA in the drinking water and 36 rats were given 0.33 g/l AA. Vehicle-treated and untreated control animals were included. The rats were killed two weeks after the final NQO application, and the tissues were examined. Epithelial dysplasia was assessed using a modified Smith and Pindborg (1969) index. The ordered categorical scores were analyzed appropriately. Plasma AA levels were checked in ODS and outbred rats at the start and end of the experiment. The results indicated that the oral mucosa of the ODS and outbred rats were susceptible to NQO but that the rate of dysplasia and OMSCC development differed between them, with more rapid changes being found in the ODS rats (p < or = 0.05). No significant difference was found in the dysplasia scores and in the rate of OMSCC development between ODS rats given 2.5 g/l of AA and ODS rats given 0.33 g/l of AA (p > 0.05). No epithelial changes were observed in the palatal mucosa of vehicle-treated and untreated controls. The plasma AA level mean (+/- SEM) was 56 +/- 6 microM for the outbred rats, 8 +/- 1 microM for the ODS rats given 0.33 g/l AA supplementation, and 29 +/- 2 microM for the ODS rats given 2.5 g/l AA. It was concluded that the chronic AA-deficient state in ODS rats played an insignificant role in oral carcinogenesis and that other factors, for example, genetic differences in susceptibility to NQO, contributed to the present findings.

The expression of c-erbB-2 protein in the keratinocytes of oral mucosal lichen planus

The expression of the c-erbB-2 protein was studied in the keratinocytes from patients with: (i) oral mucosal lichen planus (OLP) (n = 26); (ii) oral mucosal squamous cell carcinoma (OMSCC) which had arisen in mucosa affected by OLP (n = 5); and (iii) normal oral mucosa (n = 5). C-erbB-2 protein was expressed on the cell membranes of the keratinocytes of nucleated epithelium in the stratum spinosum. The antigenic determinant recognized represents the cytoplasmic domain of a cell surface receptor which binds an as yet uncharacterized heparin binding ligand of unknown function. The specimens from the five normal subjects showed positive immunohistochemical staining with the monoclonal c-erbB-2 protein antibody, the OMSCC specimens were negative, and 23 of 26 of the OLP specimens were positive. The lack of c-erbB-2 expression in the three OLP and in the five OMSCC specimens may indicate a genetic alteration, or masking of the expression of c-erbB-2. The absence of expression in OLP specimens might be an indicator of the possibility of future neoplastic transformation.

Oral mucosal ulceration due to cytomegalovirus associated with human immunodeficiency virus infection. Case report and brief review

Reports of oral lesions associated with cytomegalovirus (CMV) infection in human immunodeficiency virus (HIV) infected patients are uncommon. In this article a case of CMV infection associated with oral mucosal ulceration and a brief review of the subject is presented. Establishing the cause of ulceration is important in determining a definitive diagnosis and prescribing appropriate therapy. It is important to recognize that CMV associated oral mucosal ulceration may be the initial manifestation of human immunodeficiency virus (HIV) infection.

Giant cells in lesions of the oral region

Multinucleated giant cells form by several different mechanisms in a variety of disease processes. They play a role in the host immune response to chronic infections, react to foreign materials and are an integral part of a number of bone disorders. A selection of lesions of the oral regions that contain giant cells will be presented.

Direct immunofluorescence of oral mucosal biopsies: a comparison of fresh-frozen tissue and formalin-fixed, paraffin-embedded tissue

The diagnosis of some oral mucosal diseases can be facilitated by the use of direct immunofluorescence. Fresh frozen tissue is preferred when using this technique, however frequently the material received by the histopathology laboratory has been fixed in formalin. Enzyme digestion of tissue sections glued to glass slides prior to incubation with antibodies was shown in this study to give comparable results with direct immunofluorescence on fresh frozen tissue and can be used for diagnostic purposes when fresh frozen tissue is unavailable or not representative of the disease process.

Epithelial-mesenchymal interactions in experimental oral mucosal carcinogenesis: establishing a technique

The carcinogen 4-nitroquinoline-1-oxide was applied to the palatal mucosa of rats for varying periods of time. This tissue was separated into epithelial and connective components and then recombined in various combinations and implanted into hypothymic mice. Seventy-two per cent of the implants were recovered and were suitable for detailed histological analysis. The technique provides a suitable model for the assessment of epithelial-connective tissue interactions in experimental oral mucosal carcinogenesis.