Disruption of TNF-α signaling improves osteoblastic differentiation of adipose-derived mesenchymal stem cells and bone repair

Adipose tissue is an attractive source of mesenchymal stem cells (at-MSCs), but their low osteogenic potential limits their use in bone regeneration. Adipose tissue plays a role in pro-inflammatory diseases by releasing cytokines with a catabolic effect on bone, such as tumor necrosis factor-alpha (TNF-α). Thus, we hypothesized that endogenous TNF-α could have a negative effect on at-MSC differentiation into osteoblasts. Short interfering RNAs (siRNAs) targeting TNF-α receptors (siR1, siR2, and si1R/R2) were transfected into at-MSCs, and cell differentiation was assessed by measuring the expression of bone markers, ALP activity, and mineralized matrix. Scrambled was used as Control. Knockout at-MSCs (KOR1/R2) was injected in mice calvaria defects, and bone formation was evaluated by microtomography and histological analysis. Data were compared by Kruskal-Wallis or analysis of variance (5%). The expression of bone markers confirmed that at-MSCs differentiate less than bone marrow MSCs. In silenced cells, the expression of Alp, Runx2, and Opn was generally higher compared to Control. ALP, RUNX2, and OPN were expressed at elevated levels in silenced groups, most notably at-MSCs-siR1/R2. ALP was detected at high levels in at-MSCs-siR1/R2 and in-MSCs-siR1, followed by an increase in mineralized nodules in at-MSCs-siR1/R2. As the morphometric parameters increased, the groups treated with KOR1/R2 exhibited slight bone formation near the edges of the defects. Endogenous TNF-α inhibits osteoblast differentiation and activity in at-MSCs, and its disruption increases bone formation. While opening a path of investigation, that may lead to the development of new treatments for bone regeneration using at-MSC-based therapies.

Abstract 2175: Gene signature predicts pathological complete response in triple negative breast cancer patients: NACATRINE trial

In triple negative breast cancer (TNBC), achieving pathological complete response (pCR) is associated with improved survival outcomes. However, only one-third of patients receiving neoadjuvant chemotherapy (NAC) achieve pCR. Recognizing molecular markers that predict response to chemotherapy and selecting patients who can benefit from NAC in clinical practice has been a challenge in many studies. This exploratory analysis of the NACATRINE trial aimed to identify biomarkers that predict pCR TNBC patients receiving NAC.

The NACATRINE trial is a Brazilian, phase II, single-center, randomized, open-label study that compared adding carboplatin to sequential neoadjuvant therapy based on anthracycline and taxane for TNBC. We evaluated gene expression in untreated samples to associate with the response to systemic therapy. RNA was extracted from the tissue biopsy, and the nCounter Breast Cancer panel analyzed gene expression. Gene counts were normalized by housekeeping. For statistical significance, the t-test was used with a p-value <0.05 and fold-change ≥2.

Of the 66 patients included in the gene expression profile analysis, 24 (36.4%) had pCR, and 42 (63.6%) had residual disease. Thirty-seven genes were differentially expressed when associated with pCR in the carboplatin arm and twenty-seven in the non-carboplatin arm (p-value <0.001). We performed a linear regression model to evaluate gene performance, and the area under the curve (AUC) was calculated to assess the predictive value of differentially expressed genes. Eleven genes (KCNB1, FGF1, SNAI1, CXCL9, FGL2, HAS1, CXCL8, VEGFD, HEMK1, MS4A2, and NFKBIZ) in the carboplatin arm (AUC 0.938) and eight genes (ALDH1A1, FZD8, HIST1H3H, CXADR, WDR77, PRKACB, JUN, and CDK6) in the non-carboplatin arm (AUC 0.943) was associated with pCR. Overall survival (OS) was higher among patients who had downregulated KCNB1, FGF1, and SNAI1 (HR = 4.43, 95% CI 1.00 - 1.58; p=0.04; HR = 4.92, 95% CI 1.10 - 2.83; p= 0.03; HR = 4.86, 95% CI 1.38 - 1.11; p= 0.01) respectively. Similarly, upregulated of ALDH1A1, CXCL9 and FGL2 were associated with a better prognosis (HR = 0.17, 95% CI 0.05 - 0.50; p= 0.003; HR = 0.15, 95% CI 0.04 - 0.50; p = 0.004; HR = 0.21, 95% CI 0.07 - 0.60; p = 0.009), respectively.

We identified potentially beneficial gene expression signatures (OS and pCR) for neoadjuvant chemotherapy, suggesting that these markers validated in a prospective study can be used in selecting patients for neoadjuvant chemotherapy in TNBC.

Citation Format: Ana J. Freitas, Caroline R. Nunes, Rhafaela L. Causin, Iara V. Santana, Marco A. Oliveira, Stéphanie Calfa, Cristiano P. Souza, Márcia M. Marques. Gene signature predicts pathological complete response in triple negative breast cancer patients: NACATRINE trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2175.

Nestin and NG2 transgenes reveal two populations of perivascular cells stimulated by photobiomodulation

Pericytes and glial cells are known to collaborate in dental pulp tissue repair. Cell-based therapies that stimulate these stromal components may be of therapeutic relevance for partially vital dental pulp conditions. This study aimed to examine the early effect of photobiomodulation (PBM) in pericytes from experimentally injured pulp tissue. To accomplish this, we used the Nestin-GFP/NG2-DsRed mice, which could allow the identification of distinct pericyte phenotypes. We discovered the presence of two pericytes subsets within the dental pulp, the Nestin ⁺ NG2⁺ (type-2) and Nestin^- NG2⁺ (type-1). Upon injury, PBM treatment led to a significant increase in Nestin⁺ cells and pericytes. This boost was mainly conferred by the more committed pericyte subset (NestinNG2⁺ ). PBM also stimulated terminal blood vessels sprouting adjacent to the injury site while maintaining signs of pulp vitality. In vitro, PBM induced VEGF upregulation, improved dental pulp cells proliferation and migration, and favored their mineralization potential. Herein, different subsets of perivascular cells were unveiled in the pulp tissue. PBM enhanced not only NG2⁺ cells but nestin-expressing progenitors in the injured dental pulp.

A subpopulation of human Adark spermatogonia behaves as the reserve stem cell

Human spermatogonial stem cells (SSCs) are an essential source to maintain spermatogenesis as an efficient process for daily sperm production with high self-renewal capacity along adulthood. However, the phenotype and the subpopulation that represent the real reserve SSC for the human testis remain unknown. Moreover, although SSC markers have been described for undifferentiated spermatogonia (Adark and Apale), the existence of a specific subtype that could be identified as the actual/true SSC has not yet been fully determined. Herein we evaluated spermatogonial morphology, kinetics, positioning regarding blood vasculature in relation to protein expression (UTF1, GFRA1, and KIT) as well as proliferative activity (MCM7) and identified a small subpopulation of Adark with nuclear rarefaction zone (AdVac) that behaves as the human reserve SSC. We show that AdVac is the smallest human spermatogonial population (10%), staying quiescent (89%) and positioned close to blood vessels throughout most of the stages of the seminiferous epithelium cycle (SEC) and divides only at stages I and II. Within this AdVac population, we found a smaller pool (2% of A undifferentiated spermatogonia) of entirely quiescent cells exhibiting a high expression of UTF1 and lacking GFRA1. This finding suggests them as the real human reserve SSC (AdVac UTF1+/GFRA1-/MCM7-). Additionally, Adark without nuclear vacuole (AdNoVac) and Apale have similar kinetic and high proliferative capacity throughout the SEC (47%), indicating that they are actively dividing undifferentiated spermatogonia. Identification of human stem cells with evident reserve SSC functionality may help further studies intending to sort SSCs to treat male diseases and infertility.

Knowledge, attitudes, and practices of undergraduate students concerning Regenerative Endodontics

BACKGROUND

Knowledge, attitudes, and beliefs of the students are important for the Tissue Engineering in Endodontic practice. The opinion of these future dentists would ultimately will decide the endurance of REPs as routine procedures in endodontic practice. The aim of this study was to perform a survey to identify the knowledge, attitudes, and practices of undergraduate students about regenerative endodontic procedures (REPs).

METHODS

The questionnaire was obtained after cross-cultural adaptation of a questionnaire previously applied in USA and was applied to two hundred forty-eight undergraduates. Data were statistically analyzed.

RESULTS

Most of the students (82.9%) agreed that regenerative therapy should be incorporated to dentistry and 87.5% of them believed that stem cells banks would be useful for the tissue regeneration. Most participants (58.1%) would like to obtain an internship/tutoring that addresses REPs and 80.8% of participants think that the major obstacle to a patient accepting a REP was the expected high cost of the treatment. The freshmen students were more optimistic about offering stem cell treatments to their patients (P≤0.05).

CONCLUSIONS

The undergraduates were very optimistic about the future of REPs, stem cell banking, and tissue engineering. Although seniors demonstrated less enthusiasm towards REPs than the freshman, most students are willing to recommend these treatments to their patients.

Prevalence and predictors of weight loss maintenance: a retrospective population-based survey of European adults with overweight and obesity

BACKGROUND

The prevalence of weight loss attempts has increased worldwide, although the extent to which sustained weight loss is achieved is unknown. There is insufficient research into weight loss maintenance (WLM) in individuals with overweight or obesity who have recently lost clinically significant amounts of weight (≥5%), particularly in the European general population. The present study aimed to determine the prevalence and retrospective predictors of WLM in population-based samples of European adults with overweight or obesity who had made a recently completed weight loss attempt.

METHODS

Participants (N = 2000) in UK, Denmark and Portugal completed an online survey about loss and regain in their most recent completed weight loss attempt, features of their attempt (duration, self-weighing, lapses, strategies), as well as loss of control and binge eating. Multiple regression analysis was used to determine factors retrospectively associated with WLM in those who achieved clinically significant weight loss (n = 1272).

RESULTS

Mean (SD) self-reported weight loss was 9% (8%) and mean (SD) regain was 96.3% (9%) of participants' start weight. Twenty-three percent of the total sample had maintained weight loss of ≥5% for at least 1 month. Controlling for weight loss and time since attempt, predictors of better WLM were avoidance of a temporary lapse, infrequent/absent loss of control and binge eating, and use of a greater number of dietary strategies for WLM (r²  = 0.338, P < 0.001).

PRINCIPAL CONCLUSIONS

Factors associated with recent successful WLM indicate the importance of the continued use of dietary and other strategies for WLM, particularly in the face of a lapse, as well as the need to manage dysfunctional eating behaviours.

The effect of profession on burnout in hospital staff

Background

A high level of burnout has been described in health professionals. However, literature regarding other hospital employees is scarce.

Aims

To assess the prevalence of burnout in different professional groups of hospital staff and how the professional category is associated with levels of burnout.

Methods

Employees of a University Hospital in Portugal completed a self-administered online questionnaire in 2014-2015. We used the Portuguese version of the Maslach Burnout Inventory-Human Services Survey and scored three dimensions of burnout (emotional exhaustion, depersonalization, personal accomplishment) as low, average or high. We estimated odds ratios (OR) and 95% confidence intervals (95% CI) by logistic regression, adjusting for age, sex, use of anxiolytic/antidepressant drugs and job satisfaction.

Results

There was a 10% response rate; 368 questionnaires were available for analysis. High levels of burnout due to emotional exhaustion were observed in all professional categories. Nurses, administrative staff and technicians more frequently scored higher levels of emotional exhaustion (59%, 50% and 50%, respectively) and lack of personal accomplishment (41%, 52% and 38%, respectively) than physicians and healthcare assistants. Not all professionals scored highly for depersonalization. Emotional exhaustion scores were significantly lower in healthcare assistants than nurses (adjusted OR 0.26, 95% CI 0.10-0.64).

Conclusions

Burnout affects all professional categories of hospital staff. Future studies should use larger, more representative samples of hospital staff, perform longitudinal analyses and analyse data on specifics of each professional category and other potential confounders.

Screening of hydrogel-based scaffolds for dental pulp regeneration-A systematic review

OBJECTIVE

The aim of this systematic review was to evaluate the most appropriate hydrogel scaffold type (natural, synthetic or hybrid) to be applied with stem cells for dental pulp regeneration. The findings should help clinicians make an informed choice about the appropriate scaffold to be applied for this approach.

DESIGN

Three electronic databases were searched (Medline, Web of Science and Scopus). The review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA).

RESULTS

From 4990 potentially relevant studies initially identified, 18 papers fulfilled the eligibility criteria and were considered for this review. Natural scaffolds were applied in most studies. Collagen was the most studied scaffold. In 5 of 10 studies, only growth factors were added to the constructs. Even without growth factors, these scaffolds containing stem cells were able to support the formation of dentin. The synthetic scaffolds were the least studied. Only 4 studies were selected, and in 3 of them, the same scaffold (Puramatrix) was evaluated. Puramatrix by itself was unable to form dental pulp when dental pulp stem cells were not present. Synthetic and hybrid hydrogels were unable to attract stem cells from the host. The presence of growth factors in these constructs seems to be of relevance since dental pulp tissue formation was achieved only when the hybrid scaffold was applied with growth factors.

CONCLUSION

All types of hydrogel-based scaffolds, when containing mesenchymal stem cells, are able to form connective tissue with different degrees of similarity to dental pulp. However, current data is too heterogeneous to compare and identify the advantages of any specific scaffold.

MicroRNA-27a-5p regulation by promoter methylation and MYC signaling in prostate carcinogenesis

Upregulation of MYC and miRNAs deregulation are common in prostate cancer (PCa). Overactive MYC may cause miRNAs’ expression deregulation through transcriptional and post-transcriptional mechanisms and epigenetic alterations are also involved in miRNAs dysregulation. Herein, we aimed to elucidate the role of regulatory network between MYC and miRNAs in prostate carcinogenesis. MYC expression was found upregulated in PCa cases and matched precursor lesions. MicroRNA’s microarray analysis of PCa samples with opposed MYC levels identified miRNAs significantly overexpressed in high-MYC PCa. However, validation of miR-27a-5p in primary prostate tissues disclosed downregulation in PCa, instead, correlating with aberrant promoter methylation. In a series of castration-resistant PCa (CRPC) cases, miR-27a-5p was upregulated, along with promoter hypomethylation. MYC and miR-27a-5p expression levels in LNCaP and PC3 cells mirrored those observed in hormone-naíve PCa and CRPC, respectively. ChIP analysis showed that miR-27a-5p expression is only regulated by c-Myc in the absence of aberrant promoter methylation. MiR-27a-5p knockdown in PC3 cells promoted cell growth, whereas miRNA forced expression in LNCaP and stable MYC-knockdown PC3 cells attenuated the malignant phenotype, suggesting a tumor suppressive role for miR-27a-5p. Furthermore, miR-27a-5p upregulation decreased EGFR/Akt1/mTOR signaling. We concluded that miR-27a-5p is positively regulated by MYC, and its silencing due to aberrant promoter methylation occurs early in prostate carcinogenesis, concomitantly with loss of MYC regulatory activity. Our results further suggest that along PCa progression, miR-27a-5p promoter becomes hypomethylated, allowing for MYC to resume its regulatory activity. However, the altered cellular context averts miR-27a-5p from successfully accomplishing its tumor suppressive function at this stage of disease.

Efficacy of a randomized controlled self-regulation based physical activity intervention for chronic fatigue: Mediation effects of physical activity progress and self-regulation skills

OBJECTIVE

Examine the medium-term effects of a brief physical activity (PA) self-regulation (SR) based intervention (4-STEPS program) for chronic fatigue, and explore the mediating effects of PA related variables and SR skills.

METHODS

A two-arm randomized controlled trial (Usual Care vs 4-STEPS) was carried out. The 4-STEPS program consisted of Motivational Interviewing and SR-skills training. Fatigue severity (primary outcome) and impact, PA, health-related quality of life (HrQoL), and somatic and psychological distress were assessed at baseline, post-treatment (12weeks) and 12months follow-up.

RESULTS

Ninety-one patients (45 intervention and 46 controls) were included. At follow-up, there were significant treatment effects on fatigue severity (g=0.72) and fatigue impact, leisure-time PA, and physical and psychological HrQoL. No significant effects were found for number of daily steps and somatic and psychological distress. Fatigue severity at follow-up was partially mediated by post-treatment progress on a personal PA goal (effect ratio=18%).

CONCLUSION

Results suggest that a brief intervention, focusing on the formulation and pursuit of personal PA goals and the use of SR skills, produces sustained benefits for fatigue severity. Despite these promising results, dropout was high and the intervention was not beneficial for all secondary outcomes.

Prevalence of personal weight control attempts in adults: a systematic review and meta-analysis

The purpose of this systematic review and meta-analysis was to estimate the prevalence of personal weight control attempts (weight loss and/or maintenance) worldwide and to identify correlates, personal strategies used and the underlying motives. We included epidemiological/observational studies of adults (≥18 years) reporting prevalence of weight control attempts in the past-year. Seventy-two studies (n = 1,184,942) met eligibility criteria. Results from high quality studies showed that 42% of adults from general populations and 44% of adults from ethnic-minority populations reported trying to lose weight, and 23% of adults from general populations reported trying to maintain weight annually. In general population studies, higher prevalence of weight loss attempts was observed in the decade of 2000-2009 (48.2%), in Europe/Central Asia (61.3%) and in overweight/obese individuals and in women (p < 0.01). Of the 37 strategies (grouped in 10 domains of the Oxford Food and Activity Behaviours Taxonomy) and 12 motives reported for trying to control weight, exercising and dieting (within the energy compensation and restraint domains, respectively) and wellbeing and long-term health were the most prevalent. To our knowledge, this is the first systematic review to investigate weight control attempts worldwide. Key strategies and motives were identified which have implications for future public health initiatives on weight control.

MicroRNA profiling in human breast cancer cell lines exposed to the anti-neoplastic drug cediranib

Cediranib, a pan-tyrosine kinase inhibitor is showing promising results for the treatment of several solid tumours. In breast cancer, its effects remain unclear, and there are no predictive biomarkers. Several studies have examined the expression profiles of microRNAs (miRNAs) in response to different chemotherapy treatments and found that the expression patterns may be associated with the treatment response. Therefore, our aim was to evaluate the cellular behaviour and differential expression profiles of miRNAs in breast cancer cell lines exposed to cediranib. The biological effect of this drug was measured by viability, migration, invasion and cell death in in vitro assays. Signaling pathways were assessed using a human phospho-receptor tyrosine kinase array. Furthermore, using a miRNA array and quantitative real-time PCR (qRT‑PCR), we assessed the relative expression of miRNAs following cediranib treatment. The breast cancer cell lines exhibited a distinct cytotoxic response to cediranib treatment. Cediranib exposure resulted in a decrease in the cell migration and invasion of all the breast cancer cell lines. Treatment with cediranib appeared to be able to modulate the activation of several RTKs that are targets of cediranib such as EGFR and a new potential target ROR2. Furthermore, this drug was able to modulate the expression profile of different microRNAs such as miR-494, miR-923, miR-449a, miR-449b and miR-886-3 in breast cancer cell lines. These miRNAs are reported to regulate genes involved in important molecular processes, according to bioinformatics prediction tools.

Gingival Mesenchymal Stem Cell (GMSC) Delivery System Based on RGD-Coupled Alginate Hydrogel with Antimicrobial Properties: A Novel Treatment Modality for Peri-Implantitis

PURPOSE

Peri-implantitis is one of the most common inflammatory complications in dental implantology. Similar to periodontitis, in peri-implantitis, destructive inflammatory changes take place in the tissues surrounding a dental implant. Bacterial flora at the failing implant sites resemble the pathogens in periodontal disease and consist of Gram-negative anaerobic bacteria including Aggregatibacter actinomycetemcomitans (Aa). Here we demonstrate the effectiveness of a silver lactate (SL)-containing RGD-coupled alginate hydrogel scaffold as a promising stem cell delivery vehicle with antimicrobial properties.

MATERIALS AND METHODS

Gingival mesenchymal stem cells (GMSCs) or human bone marrow mesenchymal stem cells (hBMMSCs) were encapsulated in SL-loaded alginate hydrogel microspheres. Stem cell viability, proliferation, and osteo-differentiation capacity were analyzed.

RESULTS

Our results showed that SL exhibited antimicrobial properties against Aa in a dose-dependent manner, with 0.50 mg/ml showing the greatest antimicrobial properties while still maintaining cell viability. At this concentration, SL-containing alginate hydrogel was able to inhibit Aa growth on the surface of Ti discs and significantly reduce the bacterial load in Aa suspensions. Silver ions were effectively released from the SL-loaded alginate microspheres for up to 2 weeks. Osteogenic differentiation of GMSCs and hBMMSCs encapsulated in the SL-loaded alginate microspheres were confirmed by the intense mineral matrix deposition and high expression of osteogenesis-related genes.

CONCLUSION

Taken together, our findings confirm that GMSCs encapsulated in RGD-modified alginate hydrogel containing SL show promise for bone tissue engineering with antimicrobial properties against Aa bacteria in vitro.

p73 is required for ependymal cell maturation and neurogenic SVZ cytoarchitecture

The adult subventricular zone (SVZ) is a highly organized microenvironment established during the first postnatal days when radial glia cells begin to transform into type B-cells and ependymal cells, all of which will form regenerative units, pinwheels, along the lateral wall of the lateral ventricle. Here, we identify p73, a p53 homologue, as a critical factor controlling both cell-type specification and structural organization of the developing mouse SVZ. We describe that p73 deficiency halts the transition of the radial glia into ependymal cells, leading to the emergence of immature cells with abnormal identities in the ventricle and resulting in loss of the ventricular integrity. p73-deficient ependymal cells have noticeably impaired ciliogenesis and they fail to organize into pinwheels, disrupting SVZ niche structure and function. Therefore, p73 is essential for appropriate ependymal cell maturation and the establishment of the neurogenic niche architecture. Accordingly, lack of p73 results in impaired neurogenesis. Moreover, p73 is required for translational planar cell polarity establishment, since p73 deficiency results in profound defects in cilia organization in individual cells and in intercellular patch orientation. Thus, our data reveal a completely new function of p73, independent of p53, in the neurogenic architecture of the SVZ of rodent brain and in the establishment of ependymal planar cell polarity with important implications in neurogenesis. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 730-747, 2016.

Cytotoxicity, genotoxicity and antibacterial effectiveness of a bioceramic endodontic sealer

AIM

To compare the characteristics of bioceramic endodontic sealer Endosequence BC sealer with those of AH Plus sealer.

METHODOLOGY

Cytotoxicity and genotoxicity were analysed on human gingival fibroblasts submitted to cell culture medium conditioned by sealers using the MTT reduction assay and micronucleus formation test (MNT), respectively. Cells grown on fresh medium served as controls. Cell viabilities were measured at 1, 3, 5 and 7 days. The antibacterial activity was analysed on an Enterococcus faecalis strain (ATCC 29212) using both on agar diffusion test (ADT) and a direct contact test (DCT). The inhibition zones in ADT were measured after 48 h and the colony-forming units counting in the DCT after 1, 24, 72 and 168 h. Data were compared by anova and Tukey's test and MNT by Fisher's exact test (P < 0.05).

RESULTS

Cultures submitted to Endosequence BC sealer had a significantly higher number of viable cells (P < 0.01) and less micronucleus formation (P < 0.05) than AH Plus sealer. Endosequence BC sealer exhibited significantly smaller inhibition zones (6.00 ± 0.03 mm) than AH Plus sealer (10.31 ± 0.21 mm) (P < 0.05). Moreover, Endosequence BC sealer had significantly smaller antibacterial activity than AH Plus sealer up to 1 h of direct contact (P < 0.05). On other exposure times, both materials had similar antibacterial effectiveness (P > 0.05).

CONCLUSIONS

Bioceramic-based sealer had less cytotoxicity and genotoxicity and similar antibacterial effect against E. faecalis in comparison with AH Plus sealer.

Pluronic F-127 hydrogel as a promising scaffold for encapsulation of dental-derived mesenchymal stem cells

Dental-derived mesenchymal stem cells (MSCs) provide an advantageous therapeutic option for tissue engineering due to their high accessibility and bioavailability. However, delivering MSCs to defect sites while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated tissue regeneration. Here, we tested the osteogenic and adipogenic differentiation capacity of dental pulp stem cells (DPSCs) in a thermoreversible Pluronic F127 hydrogel scaffold encapsulation system in vitro. DPSCs were encapsulated in Pluronic (®) F-127 hydrogel and stem cell viability, proliferation and differentiation into adipogenic and osteogenic tissues were evaluated. The degradation profile and swelling kinetics of the hydrogel were also analyzed. Our results confirmed that Pluronic F-127 is a promising and non-toxic scaffold for encapsulation of DPSCs as well as control human bone marrow MSCs (hBMMSCs), yielding high stem cell viability and proliferation. Moreover, after 2 weeks of differentiation in vitro, DPSCs as well as hBMMSCs exhibited high levels of mRNA expression for osteogenic and adipogenic gene markers via PCR analysis. Our histochemical staining further confirmed the ability of Pluronic F-127 to direct the differentiation of these stem cells into osteogenic and adipogenic tissues. Furthermore, our results revealed that Pluronic F-127 has a dense tubular and reticular network morphology, which contributes to its high permeability and solubility, consistent with its high degradability in the tested conditions. Altogether, our findings demonstrate that Pluronic F-127 is a promising scaffold for encapsulation of DPSCs and can be considered for cell delivery purposes in tissue engineering.

Regulatory feedback loop between TP73 and TRIM32

The p73 transcription factor is one of the members of the p53 family of tumor suppressors with unique biological functions in processes like neurogenesis, embryonic development and differentiation. For this reason, p73 activity is tightly regulated by multiple mechanisms, including transcription and post-translational modifications. Here, we identified a novel regulatory loop between TAp73 and the E3 ubiquitin ligase tripartite motif protein 32 (TRIM32). TRIM32, a new direct p73 transcriptional target in the context of neural progenitor cells, is differentially regulated by p73. Although TAp73 binds to the TRIM32 promoter and activates its expression, TAp73-induced TRIM32 expression is efficiently repressed by DNp73. TRIM32 in turn physically interacts with TAp73 and promotes its ubiquitination and degradation, impairing p73-dependent transcriptional activity. This mutual regulation between p73 and TRIM32 constitutes a novel feedback loop, which might have important implications in central nervous system development as well as relevance in oncogenesis, and thus emerges as a possible therapeutic target.

Autoimmune regulator (Aire) controls the expression of microRNAs in medullary thymic epithelial cells

The autoimmune regulator (Aire) is a transcription factor that controls the ectopic expression of a large set of peripheral tissue antigen (PTA) genes in medullary thymic epithelial cells (mTECs). Recent evidence has demonstrated that Aire releases stalled RNA polymerase II (RNA Pol II) from blockage at the promoter region of its target genes. Given that, in addition to messenger RNAs (mRNA), RNA Pol II also transcribes microRNAs (miRNAs), we raised the hypothesis that Aire might play a role as an upstream controller of miRNA transcription. To test this, we initially analyzed the expression profiles of 662 miRNAs in control and Aire-silenced (siRNA) murine mTEC 3.10 cells using microarrays. The bioinformatics programs SAM and Cluster-TreeView were then used to identify the differentially expressed miRNAs and their profiles, respectively. Thirty Aire-dependent miRNAs were identified in the Aire-silenced mTECs, of which 18 were up- and 12 were down-regulated. The down-regulated miR-376 family was the focus of this study because its members (miR-376a, miR-376b and miR-376c) are located in the genome within the Gm2922 open-reading frame (ORF) gene segment on the chromosome 12F1. The T-boxes (TTATTA) and G-boxes (GATTGG), which represent putative RNA Pol II promoter motifs, were located in a portion spanning 10 kb upstream of the ATG codon of Gm2922. Moreover, we found that Gm2922 encodes an mRNA, which was also down-regulated in Aire-silenced mTECs. These results represent the first evidence that Aire can play a role as a controller of transcription of miRNAs located within genomic regions encompassing ORF and/or mRNA genes.

N-terminal valine adduct from the anti-HIV drug abacavir in rat haemoglobin as evidence for abacavir metabolism to a reactive aldehyde in vivo

BACKGROUND AND PURPOSE

The aim of this study was to obtain evidence for the activation of the nucleoside reverse transcriptase inhibitor abacavir to reactive aldehyde metabolites in vivo. Protein haptenation by these reactive metabolites may be a factor in abacavir-induced toxic events.

EXPERIMENTAL APPROACH

The formation of N-terminal valine adducts from the abacavir-derived aldehydes was investigated in the haemoglobin of Wistar rats treated with eight daily doses (120 mg·kg(-1)) of abacavir. The analyses were conducted by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry upon comparison with synthetic standards.

KEY RESULTS

An N-terminal valine haemoglobin adduct derived from an α,β-unsaturated aldehyde metabolite of abacavir was identified in vivo for the first time.

CONCLUSIONS AND IMPLICATIONS

This preliminary work on abacavir metabolism provides the first unequivocal evidence for the formation of an α,β-unsaturated aldehyde metabolite in vivo and of its ability to form haptens with proteins. The methodology described herein can be used to assess the formation of this metabolite in human samples and has the potential to become a valuable pharmacological tool for mechanistic studies of abacavir toxicity. In fact, the simplicity of the method suggests that the abacavir adduct with the N-terminal valine of haemoglobin could be used to investigate abacavir-induced toxicity for accurate risk/benefit estimations.

Single session of Nd:YAG laser intracanal irradiation neutralizes endotoxin in dental root dentin

Endotoxins released in the dental root by Gram-negative microorganisms can be neutralized by calcium hydroxide, when this medication is applied inside the root canal for at least seven days. However, several clinical situations demand faster root canal decontamination. Thus, for faster endotoxin neutralization, endodontists are seeking additional treatments. The in vitro study tested whether or not intracanal Nd:YAG laser irradiation would be able to neutralize endotoxin within the human dental root canal in a single session. Twenty-four human teeth with one root were mounted between two chambers. After conventional endodontic treatment, root canals were contaminated with Escherichia coli endotoxin. Then they were irradiated or not (controls) in contact mode with an Nd:YAG laser (1.5 W, 15 Hz, 100 mJ and pulse fluency of 124  J/cm2). The endotoxin activity was measured using the limulus lysate technique and data were statistically compared (p≤0.05). The concentration of active endotoxin measured in the negative control group was significantly lower than that of the positive control group (p=0.04). The concentrations of endotoxin in both irradiated groups were significantly lower than that of the positive control group (p=0.027) and similar to that of negative control group (p=0.20). A single session of intracanal Nd:YAG laser irradiation is able to neutralize endotoxin in the dental root tissues.

Mitochondrial swelling and incipient outer membrane rupture in preapoptotic and apoptotic cells

Outer mitochondrial membrane (OMM) rupture was first noted in isolated mitochondria in which the inner mitochondrial membrane (IMM) had lost its selective permeability. This phenomenon referred to as mitochondrial permeability transition (MPT) refers to a permeabilized inner membrane that originates a large swelling in the mitochondrial matrix, which distends the outer membrane until it ruptures. Here, we have expanded previous electron microscopic observations that in apoptotic cells, OMM rupture is not caused by a membrane stretching promoted by a markedly swollen matrix. It is shown that the widths of the ruptured regions of the OMM vary from 6 to 250 nm. Independent of the perforation size, herniation of the mitochondrial matrix appeared to have resulted in pushing the IMM through the perforation. A large, long focal herniation of the mitochondrial matrix, covered with the IMM, was associated with a rupture of the OMM that was as small as 6 nm. Contextually, the collapse of the selective permeability of the IMM may precede or follow the release of the mitochondrial proteins of the intermembrane space into the cytoplasm. When the MPT is a late event, exit of the intermembrane space proteins to the cytoplasm is unimpeded and occurs through channels that transverse the outer membrane, because so far, the inner membrane is impermeable. No channel within the outer membrane can expose to the cytoplasm a permeable inner membrane, because it would serve as a conduit for local herniation of the mitochondrial matrix. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.

In vitro and in vivo evaluation of the biocompatibility of a calcium phosphate/poly(lactic-co-glycolic acid) composite

This study assess the effects of bioceramic and poly(lactic-co-glycolic acid) composite (BCP/PLGA) on the viability of cultured macrophages and human dental pulp fibroblasts, and we sought to elucidate the temporal profile of the reaction of pulp capping with a composite of bioceramic of calcium phosphate and biodegradable polymer in the progression of delayed dentine bridge after (30 and 60 days) in vivo. Histological evaluation of inflammatory infiltrate and dentin bridge formation were performed after 30 and 60 days. There was similar progressive fibroblast growth in all groups and the macrophages showed viability. The in vivo study showed that of the three experimental groups: BCP/PLGA composite, BCP and calcium hydroxide (Ca(OH)(2)) dentin bridging was the most prevalent (90 %) in the BCP/PLGA composite after 30 days, mild to moderate inflammatory response was present throughout the pulp after 30 days. After 60 days was observed dentine bridging in 60 % and necrosis in 40 %, in both groups. The results indicate that understanding BCP/PLGA composite is biocompatible and by the best tissue response as compared to calcium hydroxide in direct pulp capping may be important in the mechanism of delayed dentine bridge after 30 and 60 days.

Effect of laser phototherapy on wound healing following cerebral ischemia by cryogenic injury

Laser phototherapy emerges as an alternative or auxiliary therapy for acute ischemic stroke, traumatic brain injury, degenerative brain disease, spinal cord injury, and peripheral nerve regeneration, but its effects are still controversial. We have previously found that laser phototherapy immunomodulates the response to focal brain damage. Following direct cortical cryogenic injury the effects of laser phototherapy on inflammation and repair was assessed after cryogenic injury (CI) to the central nervous system (CNS) of rats. The laser phototherapy was carried out with a 780 nm AlGaAs diode laser. The irradiation parameters were: power of 40 mW, beam area of 0.04 cm(2), energy density of 3 J/cm(2) (3s) in two points (0.12 J per point). Two irradiations were performed at 3 h-intervals, in contact mode. Rats (20 non-irradiated - controls and 20 irradiated) were used. The wound healing in the CNS was followed in 6 h, 1, 7 and 14 days after the last irradiation. The size of the lesions, the neuron cell viability percentages and the amount of positive GFAP labeling were statistically compared by ANOVA complemented by Tukey's test (p<0.05). The distribution of lymphocytes, leukocytes and macrophages were also analyzed. CI created focal lesions in the cortex represented by necrosis, edema, hemorrhage and inflammatory infiltrate. The most striking findings were: lased lesions showed smaller tissue loss than control lesions in 6 h. During the first 24 h the amount of viable neurons was significantly higher in the lased group. There was a remarkable increase in the amount of GFAP in the control group by 14 days. Moreover, the lesions of irradiated animals had fewer leukocytes and lymphocytes in the first 24 h than controls. Considering the experimental conditions of this study it was concluded that laser phototherapy exerts its effect in wound healing following CI by controlling the brain damage, preventing neuron death and severe astrogliosis that could indicate the possibility of a better clinical outcome.

p73 deficiency results in impaired self renewal and premature neuronal differentiation of mouse neural progenitors independently of p53

The question of how neural progenitor cells maintain its self-renewal throughout life is a fundamental problem in cell biology with implications in cancer, aging and neurodegenerative diseases. In this work, we have analyzed the p73 function in embryonic neural progenitor cell biology using the neurosphere (NS)-assay and showed that p73-loss has a significant role in the maintenance of neurosphere-forming cells in the embryonic brain. A comparative study of NS from Trp73−/−, p53KO, p53KO;Trp73−/− and their wild-type counterparts demonstrated that p73 deficiency results in two independent, but related, phenotypes: a smaller NS size (related to the proliferation and survival of the neural-progenitors) and a decreased capacity to form NS (self-renewal). The former seems to be the result of p53 compensatory activity, whereas the latter is p53 independent. We also demonstrate that p73 deficiency increases the population of neuronal progenitors ready to differentiate into neurons at the expense of depleting the pool of undifferentiated neurosphere-forming cells. Analysis of the neurogenic niches demonstrated that p73-loss depletes the number of neural-progenitor cells, rendering deficient niches in the adult mice. Altogether, our study identifies TP73 as a positive regulator of self-renewal with a role in the maintenance of the neurogenic capacity. Thus, proposing p73 as an important player in the development of neurodegenerative diseases and a potential therapeutic target.

Analysis in vitro of the cytotoxicity of potential implant materials. I: Zirconia-titania sintered ceramics

Zirconia (ZrO2) is a bioinert, strong, and tough ceramic, while titania (TiO2) is bioactive but has poor mechanical properties. It is expected that ZrO2-TiO2 mixed ceramics incorporate the individual properties of both ceramics, so that this material would exhibit better biological properties. Thus, the objective of this study was to compare the biocompatibility properties of ZrO2-TiO2 mixed ceramics. Sintered ceramics pellets, obtained from powders of TiO2, ZrO2, and three different ZrO2-TiO2 mixed oxides were used. Roughnesses, X-ray diffraction, microstructure through SEM, hardness, and DRIFT characterizations were performed. For biocompatibility analysis cultured FMM1 fibroblasts were plated on the top of disks and counted in SEM micrographs 1 and 2 days later. Data were compared by ANOVA complemented by Tukey's test. All samples presented high densities and similar microstructure. The H2O content in the mixed ceramics was more evident than in pure ceramics. The number of fibroblasts attached to the disks increased significantly independently of the experimental group. The cell growth on the top of the ZrO2-TiO2 samples was similar and significantly higher than those of TiO2 and ZrO2 samples. Our in vitro experiments showed that the ZrO2-TiO2 sintered ceramics are biocompatible allowing faster cell growth than pure oxides ceramics. The improvement of hardness is proportional to the ZrO2 content. Thus, the ZrO2-TiO2 sintered ceramics could be considered as potential implant material.

Laser phototherapy as topical prophylaxis against head and neck cancer radiotherapy-induced oral mucositis: comparison between low and high/low power lasers

BACKGROUND AND OBJECTIVE

Oral mucositis is a dose-limiting and painful side effect of radiotherapy (RT) and/or chemotherapy in cancer patients. The purpose of the present study was to analyze the effect of different protocols of laser phototherapy (LPT) on the grade of mucositis and degree of pain in patients under RT.

PATIENTS AND METHODS

Thirty-nine patients were divided into three groups: G1, where the irradiations were done three times a week using low power laser; G2, where combined high and low power lasers were used three time a week; and G3, where patients received low power laser irradiation once a week. The low power LPT was done using an InGaAlP laser (660 nm/40 mW/6 J cm(-2)/0.24 J per point). In the combined protocol, the high power LPT was done using a GaAlAs laser (808 nm, 1 W/cm(2)). Oral mucositis was assessed at each LPT session in accordance to the oral-mucositis scale of the National Institute of the Cancer-Common Toxicity criteria (NIC-CTC). The patient self-assessed pain was measured by means of the visual analogue scale.

RESULTS

All protocols of LPT led to the maintenance of oral mucositis scores in the same levels until the last RT session. Moreover, LPT three times a week also maintained the pain levels. However, the patients submitted to the once a week LPT had significant pain increase; and the association of low/high LPT led to increased healing time.

CONCLUSIONS

These findings are desired when dealing with oncologic patients under RT avoiding unplanned radiation treatment breaks and additional hospital costs.

Microarray-based gene expression analysis of human osteoblasts in response to different biomaterials

Several biomaterials have been widely used in bone regeneration/substitution procedures in orthopedic and oral surgery. However, how these biomaterials alter osteoblast gene expression is poorly understood. We therefore attempted to address this question by using cDNA microarray technique to identify genes that are differentially regulated in osteoblasts exposed to biomaterials comprehending the biocompatibility spectrum of bioactive (bioglass and hydroxyapatite), bioinert (Ti and stainless steel), and biotolerant (polymethylmethacrylate). By using a cDNA microarray containing 687 human IMAGE sequences, we identified in primary cultures of osteoblastic cells differentiated from the human bone marrow and exposed to these biomaterials, genes whose expression was significantly upregulated or downregulated. Among the differentially expressed genes we have found those involved with cell cycle regulation, cell differentiation and proliferation, apoptosis, cell adhesion, bone mineralization and skeletal development. These results can be relevant to a better understanding of the molecular mechanism underlying the behavior of osteoblasts in bone regenerative procedures.

Cultured epithelial cells response to phototherapy with low intensity laser

BACKGROUND AND OBJECTIVES

Little is known about the intracellular response of epithelial cells to phototherapy. The aim of this in vitro study was to analyze the effect of phototherapy with low-energy lasers with different wavelengths and powers on cultured epithelial cell growth under different nutritional conditions.

STUDY DESIGN/MATERIALS AND METHODS

Epithelial cell cultures (Vero cell line) grown in nutritional deficit in culture medium supplemented with 2% fetal bovine serum (FBS) were irradiated with low-energy laser from one to three times with a GaAlAs laser (660 nm) and InGaAlP (780 nm), 40 and 70 mW, respectively, with 3 or 5 J/cm2. Cell growth was indirectly assessed by measuring the cell mitochondrial activity.

RESULTS

Nonirradiated cell cultures grown in nutritional regular medium supplemented with 10% FBS produced higher cell growth than all cultures grown in nutritional deficit irradiated or not. The overall cell growth of cultures grown under nutritionally deficit conditions was significantly improved especially when irradiated with 780 nm for three times.

CONCLUSIONS

Phototherapy with the laser parameters tested increases epithelial cell growth rate for cells stressed by growth under nutritionally deficient states. This cell growth improvement is directly proportional to the number of irradiations; however, was not enough to reach the full cell growth potential rate of Vero epithelial cell line observed when growing under nutritional regular condition.

Effect of Matrigel on adenoid cystic carcinoma cell line differentiation

Adenoid cystic carcinoma (ACC) is a frequent malignant salivary gland neoplasm presenting different growth patterns described as tubular, cribriform and solid, which represent distinct differentiation stages. Cell lines originated from ACCs grown inside three-dimensional environments have not been capable to reproduce all in vivo ACC growth patterns. As ACC cells in vivo present replicated basement membrane, to mimic this situation in vitro ACC cells (CAC2 cells) were grown on the top of a reconstituted basement membrane (Matrigel). Phenotype differences were assessed by light, fluorescence and transmission electron microscopy. The cultures grown on the top of Matrigel presented three-dimensional arrangement of cells intercepted by cellular cords. At these, cell nests pseudocyst formations were observed. This morphological structure entirely reproduced the cribriform growth pattern of ACC. We suggest that the cribriform differentiation of ACC in culture is dependent of proteins and growth factors associated in a bi-dimensional structure.

Effects of Er:YAG Laser on the Sealing of Glass Ionomer Cement Restorations of Bacterial Artificial Root Caries

OBJECTIVE

The aim of this study was to test the effect of Er:YAG laser irradiation on the marginal sealing of root cavities restored with two glass ionomer cements.

BACKGROUND DATA

For preventing secondary root caries, new technologies for dental caries removal, such as the Er:YAG laser irradiation, have been proposed.

METHODS

Forty-five human teeth were used. Artificial root caries were induced using a microbiological model (Streptococcus mutans). The lesions were removed by three different methods: conventional technique using burs (controls; groups 1 and 2); Er:YAG laser irradiation using dentine preparation parameters (250 mJ, 4 Hz, 80.6 J/cm2; groups 3 and 4); irradiation with the dentine preparation parameters followed by surface conditioning parameters (60 mJ, 2 Hz, 19.2 J/cm2; groups 6 and 7). After each preparation method, three teeth were prepared for scanning electron microscopy morphological observation. The remaining teeth were restored by conventional glass ionomer cement (G1, G3, and G5) or resin modified glass ionomer cement (G2, G4, and G6). After restoration, the samples were thermocycled (1,000 cycles) and prepared for microleakage test.

RESULTS

Scores of less infiltrated samples were observed in groups treated by Er:YAG laser, and the smallest infiltration occurred in the group treated by the dentine preparation parameter, followed by cavity restoration with resin-modified glass ionomer (p < 0.05).

CONCLUSION

Our results suggest that root caries removal by Er:YAG laser irradiation, followed by restoration with resin-modified glass ionomer cement, is a suitable choice for dental root caries restoration.

Irradiation at 780 nm increases proliferation rate of osteoblasts independently of dexamethasone presence

BACKGROUND AND OBJECTIVES

We have previously shown that phototherapy increases cell growth and impairs protein secretion of fibroblasts. Our objective was to study the effect of phototherapy on osteoblast-like cells in culture treated with dexamethasone.

STUDY DESIGN/MATERIALS AND METHODS

Rat calvaria osteoblast-like cells were previously treated or not with dexamethasone and then, they were irradiated or not with a GaAlAs diode laser (wavelength of 780 nm, 10 mW, 3 J/cm2). Adhesion, proliferation, and osteonectin synthesis were analyzed.

RESULTS

Phototherapy increased the proliferation rate of cells independently of dexamethasone presence. Adhesion and osteonectin synthesis were not significantly influenced by laser and/or dexamethasone.

CONCLUSIONS

Based on the conditions of this study we concluded that phototherapy acts as a proliferative stimulus on osteoblast-like cells, even under the influence of dexamethasone. Thus, we suggest that phototherapy can be of importance as co-adjuvant in bone clinical manipulation in order to accelerate bone regeneration.

In vitro evaluation of the cytotoxic effects of acid solutions used as canal irrigants

Solutions of EDTA and citric acid have been used as canal irrigants. These substances must be compatible with apical periodontal tissue. The aim of this study was to evaluate comparatively the cytotoxicity of a 17% EDTA solution and that of three solutions with different concentrations of citric acid (10, 15, and 25%) on cultured fibroblasts. The solutions were diluted to 0.1% and 0.5% in culture medium and then applied to NIH 3T3 cells. After 0, 6, 12, and 24 h (short-term assay; viability) and 1, 3, 5, and 7 days (long-term assay; survival), the cells were counted. The data were compared by ANOVA. In the short-term experiments, all solutions presented a percentage of cell viability similar to that of control cells, except for the 17% EDTA solution diluted to 0.5%. After the long-term assay, all groups presented a continuous and progressive cell growth except for the 17% EDTA solution and for the 25% citric acid solution at a 0.5% dilution. The citric acid solution did not impair cell growth and viability, proving to be noncytotoxic in vitro.

Cytotoxicity of substances leached or dissolved from pulp capping materials

AIM

To evaluate the cytotoxic effects of substances leached or dissolved from pulp capping materials on human pulp fibroblasts.

METHODOLOGY

The substances were applied to cell cultures in conditioned media. The experimental groups were: GI (control; n = 24)--cultures treated with fresh medium; GII (n = 24)--cultures treated with calcium hydroxide cement; GIII (n = 24)--cultures treated with adhesive resin and GIV (n = 24)--cultures treated with 37% orthophosphoric acid. The media were conditioned by placing the crude materials in contact with fresh culture medium for 1 h. The cytotoxicity analysis was performed using the Trypan blue dye exclusion assay at times of 0, 6, 12 and 24 h for cell viability assay, and at 1, 3, 5 and 7 days for survival assay. Data were treated by anova (P < 0.05) and Tukey's test (P < 0.05).

RESULTS

GI and II presented similar cell viability and cell growth. GIII and IV exhibited statistically significant lower percentages of cell viability: GIV only at the 0 h experimental time, whereas in GIII this viability markedly diminished reaching values of 10% by 12 h. Cell growth was impaired only in cultures of GIII.

CONCLUSIONS

Substances dissolved from the adhesive system tested were cytotoxic for human dental pulp fibroblasts in culture, whilst substances leached from calcium hydroxide were biocompatible.

The effect of the renewal of calcium hydroxide paste on the apexification and periapical healing of teeth with incomplete root formation

AIM

To evaluate the influence of renewing calcium hydroxide paste on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals.

METHODOLOGY

Forty premolars from four 6-month-old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedströem files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of one premolar in each dog were left empty (group 4-control), and those of the other nine teeth in each animal were filled with a calcium hydroxide-propylene glycol paste. All teeth were restored with reinforced zinc oxide cement (IRM) or IRM and amalgam (group 4). The paste was renewed and the teeth restored again 1 week later. Then, the nine teeth in each animal were divided into three experimental groups: group 1 - paste not changed; group 2 - paste renewed every 4 weeks for 5 months; and group 3 - paste renewed after 3 months had elapsed. The teeth were restored with IRM and amalgam (groups 1 and 3) or IRM (group 2). The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate six parameters: apical calcified tissue barrier, inflammatory reaction, bone and root resorption, paste extrusion and microorganisms. Results of experimental groups were analysed by Kruskal-Wallis nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%.

RESULTS

Significant differences (P < 0.05) were found in relation to the presence of bone resorption and paste in the periradicular area, the formation of a calcified tissue barrier at the apex, and the intensity of the apical inflammatory reaction. Bone resorption was more evident in group 1 (medicament not changed), and the presence of paste in the periodontal tissues was more common in groups 2 and 3. Renewal of the paste reduced the intensity of the inflammatory reaction (groups 2 and 3), but the formation of apical calcified tissue was more noticeable in the teeth where the paste had not been renewed.

CONCLUSIONS

Replacement of calcium hydroxide paste was not necessary for apexification to occur, however, it did reduce significantly the intensity of the inflammatory process. Monthly renewal of calcium hydroxide paste reduced significantly the occurrence of apexification.

Morphology of mitochondrial permeability transition: morphometric volumetry in apoptotic cells

Here we report on the mitochondrial permeability transition (MPT), which refers to the morphology of mitochondria whose inner membrane has lost its selective permeability. In all types of apoptotic cells so far examined, we found outer mitochondrial membranes that had been ruptured. These mitochondria present a swollen matrix covered by an inner membrane herniating into the cytoplasm through the breached outer membrane. Similarly ruptured outer mitochondrial membranes have been reported in studies on mitochondrial fractions induced to undergo MPT, carried out by others. Our observations were made on five types of rat tissue cells and six different cultured cell lines in the early stages of apoptosis. Samples from the cell lines HL-60, HeLa, WEHI-164, and a special batch of PC-12 cells were subjected to various apoptogenic agents and analyzed morphometrically. Nonapoptotic companion cells with unaltered nuclear structure (CUNS) were also analyzed. The mitochondrial volume in microm(3) and the volume fraction of the cytoplasm occupied by mitochondria in cells with typical nuclear signs of apoptosis and also in CUNS were evaluated. The volume of the mitochondria with ruptured membrane represents at least 69% (47-89%) of the total mitochondrial volume of the apoptotic cells. Thus, a considerable fraction of the cellular mitochondrial mass is or was in the state of permeability transition and probably involved in enhancement of the apoptotic program. In all samples, a fraction of the cells with normal nuclei possessed mitochondria with breached outer membranes as described above. In these cells, MPT occurred before the appearance of the typical nuclear phenotype of the apoptotic cells.

Analysis of the accuracy of linear measurements obtained by cone beam computed tomography (CBCT-NewTom)

OBJECTIVES

The conical beam computed tomography (CBCT) technique presents an innovation of tomographic imaging systems and subsequent volumetric image reconstruction for dentistry. When compared with other methods of tomographic imaging CBCT is characterized by rapid volumetric image acquisition from a single low radiation dose scan of the patient. The NewTom (NewTom 9000; Quantitative Radiology, Verona, Italy) is an example of such a CBCT machine dedicated to dental and maxillofacial imaging, particularly for surgical and/or prosthetics implant planning in the field of dentistry. The aim of this study was to evaluate the accuracy of the linear measurements obtained in CBCT images using a NewTom.

METHODS

Thirteen measurements were obtained in dry skulls (n = 8) between internal and external anatomical sites using a caliper. These were considered as real measurements. Then the dry skulls were submitted to CBCT imaging examinations. Radiographic distance measurements of the same dry skull anatomical sites were made using the NewTom QR-DVT 9000 software of the 2 mm-CTs axial section images and sagittal or coronal reconstructions. The data were compared by paired Student's t-test.

RESULTS

The results showed that the real measurements were always larger than those for the CBCT images, but these differences were only significant for measurements of the internal structures of the skull base.

CONCLUSIONS

The conclusion of this study is that, although the CBCT image underestimates the real distances between skull sites, differences are only significant for the skull base and therefore it is reliable for linear evaluation measurements of other structures more closely associated with dentomaxillofacial imaging.