The expression and roles of inhibitor of DNA binding helix-loop-helix proteins in the developing and adult mouse retina.

Inhibitor of DNA binding (Id) proteins bind to and inhibit the function of basic helix-loop-helix (bHLH) transcription factors including those that regulate retinal development. However, little is known about the role of Id proteins in the growth and differentiation of the retina during development. The purpose of this study is to observe the expression of Id proteins in the developing and adult mouse retinas as the first step in investigating the functions of Id family members in the eye. The expression of Id1-4 was examined by real-time PCR, Western blot, and immunohistochemistry in wild-type and Id1/Id3 double-knockout mice. Id1-4 genes and proteins showed high expression levels in the retina at embryonic and early postnatal stages, whereas declined in the adult. Expression of Id proteins was observed in the inner neuroblastic layer (NBL) at embryonic (E) day 13.5 through 16.5. Id4 expression began at E18.5. By E18.5 and postnatal day 1, the expression of Id1-4 exhibited distinct yet overlapping patterns in the ganglion cell layer and inner part of NBL. In the adult, Ids were expressed in retinal ganglion cells, amacrine cells, bipolar cells, and horizontal cells. No Id expression was found in Müller cells. Id1 and Id3 double-knockout mice (Id1(-/-)/Id3(-/-)) showed smaller retinal size compared to wild-type or heterozygous littermates. However, histological analyses in Id1 and Id3 single-knockout retinas revealed no obvious defects in developmental phenotype. Our results indicate that the expression of the Id family may play an important role in regulating retinal progenitor cell proliferation and differentiation.

Biochemical characterization of the cell-biomaterial interface by quantitative proteomics.

Surface topography and texture of cell culture substrata can affect the differentiation and growth of adherent cells. The biochemical basis of the transduction of the physical and mechanical signals to cellular responses is not well understood. The lack of a systematic characterization of cell-biomaterial interaction is the major bottleneck. This study demonstrated the use of a novel subcellular fractionation method combined with quantitative MS-based proteomics to enable the robust and high-throughput analysis of proteins at the adherence interface of Madin-Darby canine kidney cells. This method revealed the enrichment of extracellular matrix proteins and membrane and stress fibers proteins at the adherence surface, whereas it shows depletion of extracellular matrix belonging to the cytoplasmic, nucleus, and lateral and apical membranes. The asymmetric distribution of proteins between apical and adherence sides was also profiled. Apart from classical proteins with clear involvement in cell-material interactions, proteins previously not known to be involved in cell attachment were also discovered.

Combined effect of brain-derived neurotrophic factor and LINGO-1 fusion protein on long-term survival of retinal ganglion cells in chronic glaucoma.

Glaucoma is a progressive neuropathy characterized by loss of vision as a result of retinal ganglion cell (RGC) death. There are no effective neuroprotectants to treat this disorder. Brain-derived neurotrophic factor (BDNF) is well known to transiently delay RGC death in ocular hypertensive eyes. The CNS-specific leucine-rich repeat protein LINGO-1 contributes to the negative regulation to some trophic pathways. We thereby examined whether BDNF combined with LINGO-1 antagonists can promote long-term RGC survival after ocular hypertension. In this study, intraocular pressure was elevated in adult rats using an argon laser to photocoagulate the episcleral and limbal veins. BDNF alone shows slight neuroprotection to RGCs after a long-term progress of 4 weeks following the induction of ocular hypertension. However, combination of BDNF and LINGO-1-Fc prevents RGC death in the same condition. We further identified that (1) LINGO-1 was co-expressed with BDNF receptor, TrkB in the RGCs, and (2) BDNF combined with LINGO-1-Fc activated more TrkB in the injured retina compared to BDNF alone. These results indicate that the combination of BDNF with LINGO-1 antagonist can provide long-term protection for RGCs in a chronic ocular hypertension model. TrkB may be the predominant mediator of this neuroprotection.

Metabolic syndrome and three of its components as risk factors for recurrent ischaemic stroke presenting as large-vessel infarction.

BACKGROUND AND PURPOSE: Although a clear protocol for reduction of recurrent ischaemic stroke (RIS) has been established, few studies have compared the stroke subtype distribution and risk factors between RIS and first-ever stroke (FES). METHODS: This one-year hospital-based study enrolled 587 FES and 475 RIS patients. Patients were categorized into four stroke subtypes according to a modified TOAST stroke subtype classification system. Risk factor profiles were compared between the two major stroke groups and between the corresponding four subtypes to discriminate the significant risk factors for RIS. RESULTS: A multivariate regression analysis identified hypertension (OR, 1.87; 95% CI, 1.34-2.62), diabetes mellitus (DM) (OR, 1.57; 95% CI, 1.22-2.02), low high-density lipoprotein (LHDL) (OR, 1.43; 95% CI, 1.08-1.88) and older age as significant RIS risk factors. The significance of the former three RIS factors was further recognized in its large-vessel subtype. Moreover, metabolic syndrome was significantly more common in the recurrent stroke group (P = 0.01), including its large-vessel subtype (P = 0.04). Progressively increasing odds ratios from 1.49 to 2.02, in accordance with increased number of diagnostic components of metabolic syndrome for recurrent large-vessel ischaemic stroke, were noted. CONCLUSIONS: Metabolic syndrome likely plays a crucial role in the development of RIS, including large-vessel infarction in modern-day Taiwan.

Protection offered by root-surface restorative materials against biofilm challenge.

The prevalence of root-surface caries is increasing. We hypothesized that some restorative materials are protective against cariogenic challenge on root surfaces. Our goal was to study the effects of different restorative materials on root surfaces incubated with an oral biofilm generated in an artificial mouth. A biofilm of Streptococcus mutans, Streptococcus sobrinus, Lactobacillus rhamnosus, and Actinomyces naeslundii was co-cultured for 21 days on 24 glass-ionomer cement, resin-modified glass-ionomer cement, or resin-composite-restored root surfaces. These surfaces were then examined with Fourier transform infrared spectroscopy and scanning electron energy-dispersive spectroscopy. Only glass-ionomer restorations showed a significant increase in log calcium-to-phosphorus ratio (P < 0.01), and a significantly lower log amide I-to-hydrogen phosphate ratio on the root surface after incubation in the artificial mouth. Glass-ionomer restoratives conferred a preventive effect on the root surfaces against initial cariogenic challenge with a mixed-species oral biofilm without therapeutic intervention.

Knowledge of and attitudes toward severe acute respiratory syndrome among a cohort of dental patients in Hong Kong following a major local outbreak.

OBJECTIVE: To assess the knowledge of and attitudes toward severe acute respiratory syndrome (SARS) among patients attending a teaching dental hospital and private dental practices in Hong Kong during a major local SARS outbreak. METHODS: 250 dental patients were interviewed by questionnaire and 213 were interviewed by phone. RESULTS: Less than one-third (30.0%) of the 463 respondents said they were not afraid of contracting the SARS coronavirus from their dentists and did not avoid dental treatment for that reason. Nearly three-fifths (56.7%) did not worry about contracting SARS from dental treatment. Fewer than 10% of the respondents thought that dentists ran a high risk of contracting SARS. From the patients' experiences, 85.2% and 21.7% of the dentists wore face masks and face shields, respectively, when delivering dental treatment. CONCLUSIONS: The majority of patients interviewed had confidence in their dentists, their treatment environments, and the infection control measures taken, and were not worried about contracting SARS in the dental setting. This perception is an improvement from that described in an earlier study, in which more than half of the patients were concerned about contracting an infection during dental treatment and perceived that the infection control measures undertaken by the dental profession to prevent infectious diseases were not satisfactory. Patients, however, demanded better infection control measures during the SARS outbreak.

Incipient caries lesions on cementum by mono- and co-culture oral bacteria.

OBJECTIVES: There is increasing prevalence of root caries. We hypothesized different biofilms will cause varying demineralization in cementum. This study investigated the extent of demineralization of cementum by oral biofilm formed from three major cariogenic microorganisms: Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces israelii. Sound cementum tooth blocks were incubated with mono-, bi-, and tri-species combinations of the bacteria under investigation. MATERIALS AND METHODS: The matrix (amide I) and phosphate content of the lesions was analyzed by Fourier-transform infrared spectroscopy (FTIR), and calcium and phosphorus levels were analyzed by scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDX). RESULTS: The log[amide I:HPO(4)(2-) absorbance] values showed that A. israelii mono-culture caused significantly more demineralization than the other bacterial cultures. log[Ca:P] showed that all carious lesions were confined to the cementum. CONCLUSIONS: Oral biofilm arising from bacterial species A. israelii alone was the most cariogenic of those tested and produced the most demineralization in incipient carious lesions in cementum.

Sudden cardiac death associates with a large right atrium thrombus in a late survivor of heart transplantation.

A fatal circulatory collapse developed acutely in a patient six years after orthotopic heart transplantation. Autopsy revealed a large, fresh thrombus inside the right atrium which obstructed the orifice of the vena cava completely. The grafted coronary artery and pulmonary vessels were patent. There was no rejection or acute infarct in myocardium. Mildly immature organization was seen on the thrombus-adhered wall. Four chamber enlargement and a rapid decline of right ventricular hypokinesia were detected shortly before death although he did not show active cardiopulmonary symptom. Intracardiac thrombus formation is rather uncommon in late survivor. A synergic effect of atrial turbulence and ventricular hypokinesia in the right heart, superimposed by tissue organization, was proposed for thrombus formation. An empty cardiac output was favored for his mortality. These findings provide a strong evidence to suggest anticoagulation in case of complicated or highly risk of embolization such as turbulence or hypokinesia despite of an absence of active cardiopulmonary symptom.

Attitudes of dental and medical students in their first and final years of undergraduate study to oral health behaviour.

OBJECTIVE: To compare differences in attitude to oral health behaviour amongst medical and dental students when they were in years 1 and 5 of University study respectively. METHODS: Medical and dental students of Peking University in Beijing, China were invited to take part in this study. The original version of the Hiroshima University-Dental Behavioural Inventory (HU-DBI) was written in Japanese. After testing the validity of both English and Chinese versions, the revised Chinese version of the HU-DBI was administered to new medical and dental students. In their final year of University study, the same questionnaire was again administered. RESULTS: Significant differences were found for 13 of 21 items, reflecting an improvement in oral health attitudes and behaviour in final year dental students when compared with the time they were entrants. This difference was not found to be significant in the sample of medical students. CONCLUSIONS: There were significant differences in oral health attitudes and behaviours in dental students between entrance to University and the final year of their study. The same was not found to be true for medical students.

Levels and value of platelet activity in patients with severe internal carotid artery stenosis.

BACKGROUND: Turbulent blood flow caused by arterial stenosis can induce platelet activation and aggregation, which subsequently participate in arterial thromboembolic events. OBJECTIVE: To test the hypothesis that platelet activation (expressed by CD62p) is enhanced in cerebral vs systemic circulation in patients with severe internal carotid artery (ICA) stenosis. METHODS: Platelet CD62p expression was prospectively measured using flow cytometry in 35 consecutive symptomatic patients with severe ICA stenosis and in 20 at-risk control subjects who underwent both coronary and cerebral angiographic studies due to angina pectoris and suspicious vertebral artery or intracranial artery stenosis. The CD62p expression was also evaluated in 20 healthy subjects. Blood samples were first drawn from the right internal jugular vein (cerebral circulation) and right femoral vein (systemic circulation) before extra- and intracerebral angiographic examination of both patients and at-risk control subjects and again at 40 minutes after ICA stenting. Clopidogrel was administered to the patients following the second blood sampling. RESULTS: Systemic CD62p expression was higher in patients than in both the healthy and at-risk control subjects (both p < 0.0001). Additionally, cerebral CD62p expression was higher in patients than in at-risk control subjects (p < 0.0001) prior to intervention. Moreover, CD62p expression was higher in cerebral circulation than in systemic circulation in the patients (p < 0.0001) before ICA stenting. However, CD62p expression was less enhanced in cerebral circulation than in systemic circulation after ICA stenting (p < 0.0001). Furthermore, CD62p expression was decreased after 3 months of follow-up (p < 0.0001). CONCLUSIONS: Compared to systemic CD62p expression, cerebral CD62p expression was more enhanced prior to ICA stenting and was less enhanced after ICA stenting in patients with severe ICA stenosis.

Retinal ganglion cells toxicity caused by photosensitising effects of intravitreal indocyanine green with illumination in rat eyes.

AIM: To investigate the effects of indocyanine green (ICG) with or without illumination on rat retinal ganglion cells (RGC) and retinal morphology. METHODS: Intravitreal injections of 1.0 mg/ml ICG solution were performed in rat eyes with or without subsequent illumination for 5 minutes. Eyes in the control group had intravitreal injections of balanced salt solution with illumination. Retrograde labelling of RGC with 6% Fluoro-Gold was performed 1 month later and RGC densities were compared between the three groups. Light microscopy with measurements of outer nuclear layer (ONL) and inner nuclear layer (INL) thicknesses were also performed and compared. RESULTS: Eyes with ICG without illumination showed insignificant reduction in RGC density compared with the control group (p = 0.28), whereas a significant decrease in RGC density was found in eyes that had ICG injection with illumination (p = 0.036). A significant increase in ONL thickness was also observed in the ICG with illumination treated eyes compared with the ICG without illumination and the control groups (p<0.001). No significant difference in INL thickness was observed between the three groups. CONCLUSIONS: Intravitreal injection of 0.1 mg/ml ICG in rat eyes followed by illumination resulted in photosensitising toxicity to RGC. Lower ICG concentration or illumination level should be considered when performing ICG assisted macular surgery.

Characterization of switch phenotypes in Candida albicans biofilms.

The aim of this study was to characterize switch phenotypes in Candida albicans biofilms. Cells of Candida albicans 192887g biofilms (24 h) were resuspended and these together with their planktonic counterparts were separately inoculated on Lee's medium agar supplemented with arginine and zinc, at 25 degrees C for 9 days, for colony formation. The different switch phenotypes, as reflected by varying colony morphologies, were then examined for their (i) stability under various growth conditions, (ii) carbohydrate assimilation profiles, (iii) susceptibility to the polyene antifungal, nystatin, (iv) adhering and biofilm-forming ability, (v) filamentation, and (vi) growth rate in yeast nitrogen base medium supplemented with 100 mM glucose. Our data showed that the frequency of phenotypic switching in C. albicans biofilms was approximately 1%. Compared with the planktonic yeasts, cells derived from candidal biofilms generated one of the phenotypes less frequently (Chi-square-tests: P = 0.017). The five phenotypes derived from the biofilm growth demonstrated differing profiles for carbohydrate assimilation, adhesion, biofilm formation, filamentation, and growth rate. These findings reported here, for the first time, imply that phenotypic switching in the candidal biofilms differs from that in the planktonic growth, and affects multiple biological attributes.

An exploratory study on cultural variations in oral health attitudes, behaviour and values of freshman (first-year) dental students.

OBJECTIVE: To identify similarities and differences in oral health attitudes, behaviour and values among freshman dental students. DESIGN: Cross-cultural survey of dental students. SETTING: 18 cultural areas. PARTICIPANTS AND METHODS: 904 first-year dental students completed the Hiroshima University-Dental Behavioural Inventory (HU-DBI) translated into their own languages. Individual areas were clustered by similarity in responses to the questions. RESULTS: The first group displayed an 'occidental-culture orientation' with the exception of Brazil (Cluster 1 comprised: Australia, United Kingdom, Ireland, Belgium and Brazil, Cluster 2: Germany, Italy, Finland and France). The second group displayed an 'oriental-cultural orientation' with the exception of Greece and Israel (Cluster 3 comprised: China and Indonesia, and Cluster 4: Japan, Korea, Israel, Hong Kong, Malaysia, Thailand and Greece). Australia and United Kingdom were the countries that were most alike. Ireland was the 'neighbour' to these countries. Greece and Malaysia had similar patterns of oral health behaviour although geographic conditions are very different. Although it was considered that in Hong Kong, occidental nations have affected the development of education, it remained in the oriental-culture group. Comparison with the data from the occidentals indicates that a higher percentage of the orientals put off going to the dentist until they have toothache (p < 0.001). Only a small proportion of the occidentals (8%) reported a perception of inevitability in having false teeth, whereas 33% of the orientals held this fatalistic belief (p = 0.001). CONCLUSIONS: Grouping the countries into key cultural orientations and international clusters yielded plausible results, using the HU-DBI.

An FTIR study of the effects of artificial saliva on the physical characteristics of the glass ionomer cements used for art.

OBJECTIVE: To investigate the physical and chemical changes of five esthetic restorative materials in an artificial saliva using Fourier transform infrared spectroscopy (FTIR). METHODS: The materials included two glass polyalkenoate (ionomer) cements, one polyacid-modified resin composite, and two resin composites. Five fresh and 20 aged specimens for each material were immersed in 2 ml of artificial saliva at 37 degrees C for 1 week, 2 weeks, 1 month, and 2 months. They were examined by laser surface profilometer and FTIR. RESULTS: Surface roughness average (Ra) value showed significant differences among the physical properties of glass ionomers, polyacid-modified resin composite, and resin composites. SIGNIFICANCE: FTIR spectra showed that a major chemical changes in Fuji IX GP Fast glass ionomer cement in P-NH2 group bonding (900-1000 cm(-1)) that may explain the previously reported increase in microhardness after immersion. There was no direct correlation between surface roughness and spectral changes of the materials tested.

The use of new probes and stains for improved assessment of cell viability and extracellular polymeric substances in Candida albicans biofilms.

Phenotypic and genotypic cell differentiation is considered an important feature that confers enhanced antifungal resistance in candidal biofilms. Particular emphasis has been placed in this context on the viability of biofilm subpopulations, and their heterogeneity with regard to the production of extracellular polymeric substances (EPS). We therefore assessed the utility of two different labeled lectins Erythrina cristagalli (ECA) and Canavalia ensiformis (ConA), for EPS visualization. To evaluate the viability of candidal biofilms, we further studied combination stains, SYTO9 and propidium iodide (PI). The latter combination has been successfully used to assess bacterial, but not fungal, viability although PI alone has been previously used to stain nuclei in fungal cells. Candida albicans biofilms were developed in a rotating disc biofilm reactor and observed in situ using confocal scanning laser microscopy (CSLM). Our data indicate that SYTO9 and PI are reliable vital stains that may be used to investigate C. albicans biofilms. When used together with ConA, the lectin ECA optimized EPS visualization and revealed differential production of this material in mature candidal biofilms. The foregoing probes and stains and the methodology described should help better characterize C. albicans biofilms in terms of cell their viability, and EPS production.

Developmental expression patterns and localization of DNA-binding protein inhibitor (Id3) in the mouse retina.

Id3 (inhibitor of DNA binding/differentiation), a member of the Id helix-loop-helix protein family, has long been studied as a positive regulator of proliferation and a negative regulator of differentiation. In this study, we examined the expression pattern and cellular phenotypes of Id3 in postnatal and adult mouse retina. Id3 was mainly expressed in the early postnatal inner retina. From the late postnatal development towards adulthood, Id3 expression was confined to the ganglion cell layer and the inner nuclear layer. Colocalization analysis showed that Id3 positive cells were identified as retinal ganglion cells and amacrine cells. The differential expression profiles of Id3 provide the groundwork for the elucidation of its possible role in retinal development.

Coaggregation profiles of the microflora from root surface caries lesions.

Bacterial coaggregation reactions between different species and the auto aggregation of the same species are associated with the initiation and development of dental plaque and biofilms. As no such data is available on isolates from root caries lesions, we evaluated, by a visual, semi-quantitative scoring system and a spectrophotometric, quantitative assay, the coaggregation of 22 different wild-type microbial species comprising ten bacterial genera and a single Candida spp. The quantitative coaggregation assay we used proved to be a more sensitive method than the semi-quantitative, visual evaluation as the results yielded the percent coaggregation. Fusobacterium nucleatum, Lactobacillus acidophilus, Streptococcus bovis II/2 and Gemella morbillorum were observed having higher degrees of autoaggregation than the other examined strains. Significant levels of inter-species coaggregation was seen between: (1) Actinomyces spp. and Veillonella spp.; (2) Actinomyces israelii and Peptostreptococcus prevotii; (3) Campylobacter gracilis and Actinomyces spp.; (4) Prevotella intermedia and nine different species; and (5) Fusobacterium nucleatum and six other species. The single Candida albicans isolate did not coaggregate to a significant extent with any of the 21 bacterial isolates studied. Scanning electron microscopy observation of the coaggregation interactions between bacterial pairs having strong coaggregation reactions revealed varying adhesive patterns. Our findings on coaggregation amongst these isolates imply existence of multiple interactions between the coaggregation-inducing bacterial species in root caries. In particular, Actinomyces spp., Veillonella spp., Prevotella spp. and Fusobacterium spp. appear to play a significant role in this context.

Prosthodontic management of older severe hypodontia patients in general dental practice: a case series.

Although a detailed understanding of the etiology of hypodontia is lacking, there is a need for awareness among dental professionals of the social and psychological consequences of severe hypodontia, as well as knowledge of those affected by hypodontia have ongoing dental treatment needs. Although, there may be a need for immediate referral of children to different specialists for optimal multidisciplinary treatment planning, most older patients with severe hypodontia can be treated by general practitioners. Practitioners therefore need to be aware of the ramifications of the condition and be capable of providing adequate oral health care for these patients and referring them for additional services when necessary. A case-report series is used to illustrate routine prosthodontic treatments that can be offered to older patients in general dental practice.

Molecular evaluation of residual endodontic microorganisms after instrumentation, irrigation and medication with either calcium hydroxide or Septomixine.

BACKGROUND AND OBJECTIVE: The correct choice of antimicrobial agents as inter-appointment medicaments is as important as the instrumentation and irrigation to remove pathogens from infected root canals. Calcium hydroxide [Ca(OH)2] and framycetin sulfate (Septomixine) are common endodontic medicaments. Therefore, we evaluated the efficacy of either calcium hydroxide or Septomixine in eliminating residual intra-canal bacteria, particularly Actinomyces spp., during inter-appointment interval in endodontic therapy using molecular methods. METHODS: A total of 31 single-rooted teeth with primary root canal infections were studied immediately after opening the canals and subsequently after instrumentation, irrigation with sterile saline and 1-week medication with either Ca(OH)2 (n = 25) or Septomixine (n = 6). Whole bacterial genomic DNA was isolated directly from samples and PCR with universal primers performed to detect total intra-canal bacteria. The variable regions of 16S rDNA of bacteria were amplified and labeled with digoxigenin for further hybridization to detect Actinomyces spp. A total of seven oligonucleotide probes specific for A. bovis, A. gerencseriae, A. israelii, A. meyeri, catalase-negative A. naeslundii (genospecies 1 and 2), catalase-positive A. naeslundii genospecies 2 and A. odontolyticus were used to detect Actinomyces spp. in 22 of 31 medicated root canals [Ca(OH)2: n = 17; Septomixine: n = 5]. RESULTS: The PCR results showed that 25 of 31 examined canals were positively detected with residual microorganisms after instrumentation, irrigation with sterile saline and 1-week medication with either Ca(OH)2 (n = 20) or Septomixine (n = 5). Thus, only six canals [Ca(OH)2: n = 5, Septomixine: n = 1] were aseptic after treatment. Hybridization results showed higher detection frequency of both A. odontolyticus and A. gerencseriae after treatment. Significant correlation was found between exposed pulp before treatment and positive detection of Actinomyces spp., particularly A. odontolyticus on the second visit (P < 0.05). CONCLUSION: The conventional, 1-week medication of either Ca(OH)2 or Septomixine in endodontic therapy may not effectively inhibit residual bacterial growth in all root canals during inter-appointment intervals. Further investigations using, for instance quantitative real-time PCR analyses, are required to substantiate the present findings.