The effect of sodium hypochlorite and ethylenediaminetetraacetic acid irrigation, individually and in alternation, on tooth surface strain

Aim  To evaluate the effect of irrigation regimens on tooth surface strain using saline, sodium hypochlorite (3% and 5% NaOCl) and ethylenediaminetetraacetic acid (17% EDTA), individually and in alternating combinations.
Methodology  Single-rooted premolar teeth with single canals prepared to standardized dimensions were grouped by anatomical features and randomly distributed amongst six experimental groups ( n  = 12 each). The six groups were: (1) saline; (2) 5% NaOCl; (3) 3% NaOCl; (4) 17% EDTA; (5) 3% NaOCl and 17% EDTA; (6) 5% NaOCl and 17% EDTA. All groups underwent four (group 1) or five (groups 2, 3, 4, 5, 6) sequential 30-min irrigation periods following each of which the tooth was subjected to a standard regime of cyclic, nondestructive, occlusal loading. Tooth surface strain was measured during each loading cycle using electrical strain gauges mounted cervico-proximally. The data were analysed by Hierarchical anova and post hoc multiple comparisons.
Results  Irrigation with 5% NaOCl alone or alternating with 17% EDTA significantly ( P  < 0.001) increased the peak strain values for each of the irrigation periods compared with that of saline (group 1). The data for the other groups revealed no significant differences compared with those of saline. The strain increase after the fourth irrigation cycle was significantly higher for group 6 than for group 2. The measured canal morphology and dentine thickness parameters did not prove to have a significant effect on tooth surface strain.
Conclusions  Irrigation with 5% NaOCl acting alone or alternated with 17% EDTA (used in 30 min cycles), significantly increased tooth surface strain. The alternated regimen showed significantly greater changes in tooth surface strain than NaOCl alone. Irrigation with 3% NaOCl and 17% EDTA individually or in combination did not significantly alter the tooth surface strain.     

Impact of preoperative serum sodium concentration in living donor liver transplantation

Background and Aims: The importance of hyponatremia in deceased donor liver transplantation (DDLT) has been recently discussed frequently. However, its impact on the outcomes in living donor liver transplantation (LDLT) has not yet been elucidated. The current study was designed to demonstrate the impact of pre‐transplant sodium concentration on postoperative clinical outcomes. Methods: One hundred and thirty‐four patients who underwent LDLT for end‐stage liver diseases were examined to evaluate the significance of pre‐transplant hyponatremia (Na ≤ 130 mEq/L) on the short‐term clinical outcomes and the efficacy of the Model for End‐Stage Liver Disease and serum sodium (MELD‐Na) score using the sodium concentration and original MELD score. Results: The preoperative sodium and MELD score for all patients were 133.9 mEq/L (range: 109–142) and 16.2 (range: 6–38), respectively. According to a multivariate analysis, not only the MELD score (P = 0.030) but also the sodium concentration (P = 0.005) were found to be significant predictive factors for short‐term graft survival. Preoperative hyponatremia was a significant risk factor for the occurrence of sepsis (P < 0.001), renal dysfunction (P < 0.001) and encephalopathy (P = 0.026). The MELD‐Na score was 19.6 (range: 6–51) and the area under the receiver–operator curve of that (c‐statistics: 0.867) was higher than MELD score and sodium concentration (c‐statistics: 0.820 and 0.842, respectively). Conclusion: Preoperative hyponatremia was a significant risk for postoperative complications and short‐term graft loss. The addition of sodium concentration to MELD score might therefore be an effective predictor for post‐transplant short‐term mortality in LDLT.     

Low‐fluoride toothpaste and deciduous enamel demineralization under biofilm accumulation and sucrose exposure

Cury JA, do Amaral RC, Tenuta LMA, Del Bel Cury AA, Tabchoury CPM. Low‐fluoride toothpaste and deciduous enamel demineralization under biofilm accumulation and sucrose exposure. Eur J Oral Sci 2010; 118: 370–375. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci Because low‐fluoride toothpaste (500 p.p.m. F) has not clearly been shown to be effective for controlling caries in caries‐active children, this experimental in situ study was conducted to evaluate whether its effect, when compared with a conventional toothpaste (1,000–1,500 p.p.m. F), would depend on the cariogenic challenge. During four phases of 14 d each, 14 volunteers used 500 or 1,100 p.p.m. F toothpaste and wore palatal appliances containing deciduous enamel slabs, on which biofilm was accumulated and exposed to 20% sucrose solution at frequencies increasing from two to eight times per day. The F concentration was determined in the biofilm formed, and enamel demineralization was assessed by surface hardness loss (%SHL) and integrated area of hardness × lesion depth (ΔS). The F uptake by enamel was also determined. Fluoride in biofilm fluid and solids was statistically higher when conventional F toothpaste was used. The toothpastes did not differ statistically in terms of %SHL, ΔS, and F in enamel, but only the conventional F toothpaste significantly reduced caries‐lesion progression according to the frequency of sucrose exposure. The findings suggest that the high‐F availability in biofilm, resulting from the use of conventional toothpaste compared with low‐F toothpaste, may be important for reducing caries‐lesion progression in conjunction with a high frequency of sucrose exposure.     

Regulated sodium transport in the renal connecting tubule (CNT) via the epithelial sodium channel (ENaC)

The aldosterone-sensitive distal nephron (ASDN) includes the late distal convoluted tubule 2, the connecting tubule (CNT) and the collecting duct. The appropriate regulation of sodium (Na⁺) absorption in the ASDN is essential to precisely match urinary Na⁺ excretion to dietary Na⁺ intake whilst taking extra-renal Na⁺ losses into account. There is increasing evidence that Na⁺ transport in the CNT is of particular importance for the maintenance of body Na⁺ balance and for the long-term control of extra-cellular fluid volume and arterial blood pressure. Na⁺ transport in the CNT critically depends on the activity and abundance of the amiloride-sensitive epithelial sodium channel (ENaC) in the luminal membrane of the CNT cells. As a rate-limiting step for transepithelial Na⁺ transport, ENaC is the main target of hormones (e.g. aldosterone, angiotensin II, vasopressin and insulin/insulin-like growth factor 1) to adjust transepithelial Na⁺ transport in this tubular segment. In this review, we highlight the structural and functional properties of the CNT that contribute to the high Na⁺ transport capacity of this segment. Moreover, we discuss some aspects of the complex pathways and molecular mechanisms involved in ENaC regulation by hormones, kinases, proteases and associated proteins that control its function. Whilst cultured cells and heterologous expression systems have greatly advanced our knowledge about some of these regulatory mechanisms, future studies will have to determine the relative importance of the various pathways in the native tubule and in particular in the CNT.     

Biological response of human bone marrow mesenchymal stem cells to fluoride‐modified titanium surfaces

Objectives: The aim of the present study was to examine the behaviour of human bone marrow‐derived mesenchymal stem cells (BM‐MSC) to fluoride‐modified grit‐blasted (F‐TiO) titanium surfaces compared with grit‐blasted ones (TiO). Material and methods: Implant surfaces were analysed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). BM‐MSC were isolated from healthy donors and grown on the implant surfaces. Cell adhesion and proliferation, type I collagen (Col I) synthesis, osteoblastic differentiation (in terms of alkaline phosphatase activity, osteocalcin synthesis and extracellular matrix mineralization) were assessed. Furthermore, the ability to affect the osteoblastic/osteoclastic balance in terms of osteoprotegerin (OPG) and activator of nuclear factor κ B ligand (RANKL) ratio was investigated. Results: F‐TiO surface showed higher S_a values (P<0.05) and the presence of nano‐scale structures at the AFM and SEM analysis. Comparable cell morphology and similar adhesion values on both surfaces were detected at early time, whereas higher proliferation values on F‐TiO samples were observed at 7 and 10 days. Increased Col I and OPG levels for cells grown on F‐TiO were found, whereas RANKL was not detectable in any of the conditioned media. BM‐MSC showed a similar expression of early and late osteogenic markers on both TiO and F‐TiO surfaces. Conclusions: The results of the present study show that the chemical and micro/nano‐scale modifications induced by fluoride treatment of TiO‐grit blasted surfaces stimulate the proliferation and the extracellular matrix synthesis by BM‐MSC, as well as the increase of OPG synthesis, thus preventing osteoclast activation and differentiation. To cite this article:
Guida L, Annunziata M, Rocci A, Contaldo M, Rullo R, Oliva A. Biological response of human bone marrow mesenchymal stem cells to fluoride‐modified titanium surfaces.
Clin. Oral Impl. Res. 21 , 2010; 1234–1241.
doi: 10.1111/j.1600‐0501.2010.01929.x     

Sciatic nerve conditioned medium depleted of pro-NGF modulates sodium currents and neurite outgrowth in PC12 cells

Excitability and axon/dendrite specification are the most distinctive features in the establishment of neuronal polarization. Conditioned medium from rat sciatic nerve (CM) induced a neuronal-like morphology in PC12 cells. Here we show that CM neuritogenic activity is limited to the induction of dendrites in PC12 cells. However, treatment of these cells with CM in combination with a generic inhibitor for tyrosine kinase receptors (k252a) promoted the enhancement of neurite length, development of axons and induction of sodium currents. On the other hand, specific inhibition of TrkA and p75^NTR receptors in CM-treated cells reduced the neurite length in comparison with cells treated only with CM, although the effect over the induction of sodium currents was continuously observed. These results suggested that CM had some components that, even though are able to start the morphological cell differentiation and produce short neurites (likely acting through TrkA and p75^NTR), can restrain further neurite extension. Depletion of pro-NGF isoforms from CM produced a similar effect as the exerted by k252a, TrkA and p75^NTR receptor inhibitors in CM-treated cells, inducing the elicitation of sodium currents. These results suggested that the effect of CM might be mediated through pro-NGF. The difference between the results obtained with the generic inhibitor for Trk receptors and the specific inhibitors for TrkA and p75^NTR receptors in CM-treated cells, suggested that alternative pathways could be used to regulate neurite elongation, axon specification and sodium currents in PC12 cells. These findings represent important clues to improve the understanding of the initiation of neuronal polarity.     

不同防治方法对龋病患儿口腔链球菌数量的影响

目的探讨不同防治方法对龋病患儿口腔链球菌细胞数量的影响。方法随机抽样法选取400名学龄前儿童为研究对象,根据不同防治方法将其分为对照组(健康宣教,222名)与观察组(氟防龋,178名),跟踪随访1年,间隔6个月行口腔检查1次,比较2组龋病新增率,并于防治前、防治后6个月、12个月、24个月通过实时荧光定量PCR法测定各组无龋病儿童链球菌细菌数量。结果观察组末次随访龋病新增率显著高于对照组(P0.05);与防治前比较,2组无龋病儿童防治后6个月、12个月总链球菌、口腔链球菌数量均显著减少(P0.05);与对照组比较,观察组防治后6个月总链球菌、口腔链球菌、唾液链球菌、变异链球菌数量显著少,差异有统计学意义(P0.05);与对照组比较,观察组防治后24个月变异链球菌数量比较差异无统计学意义(P0.05)。结论健康宣教、氟化物使用均能有效预防龋病发生,减少口腔链球菌细菌数量,其中氟防龋效果更明显。     

The Influence of Beta-Blocking Agents on Plasma Volume and Extracellular Volume in Ischaemic Heart Disease

Plasma volume and extracellular volume (sodium space) were found to be unchanged during treatment with propranolol (nine patients) and practolol (four patients) for well-compensated ischaemic heart disease. The volumes were determined before treatment and 2 days and 3 months after optimal dose for each patient was reached.