Sorption and solubility testing of orthodontic bonding cements in different solutions

To evaluate and compare the solubility and sorption of orthodontic bonding cements after immersion in different solutions, five different cements were used: a fluoride-containing resin composite, a light-cured glass ionomer cement, a light-cured resin composite, a paste-paste chemically cured resin composite, and a liquid-paste chemically cured resin composite. Five different solutions were employed: distilled water, artificial saliva, an alcohol-free mouthrinse solution (Orthokin), a 5% alcohol mouthrinse solution (Perioaid), and a 75% ethanol/water solution. Five disc specimens (15 mm x 0.85 mm) were used for each experimental condition. Materials were handled following manufacturers' instructions and were ground wet with silicon carbide paper. Solubility and sorption of the materials were calculated by means of weighing the samples before and after immersion and desiccation. Data were analyzed by two-way ANOVA and Student-Newman-Keuls test (p < 0.05). The light-cured glass ionomer cement showed the lowest solubility and the highest sorption values. When using alcohol-containing solutions as storage media, solubility of the paste-paste chemically cured resin composite increased, and sorption values for the tested chemically cured resin composites were also increased. The use of alcohol-free mouthrinses does not affect sorption and solubility of orthodontic cements. The chemically cured (paste-paste) composite resin cement, requiring a mixing procedure, was the most affected by immersion in alcohol-containing solutions.     

Differential effect of in vitro degradation on resin-dentin bonds produced by self-etch versus total-etch adhesives

OBJECTIVE: To evaluate the effect of an in vitro challenge (NaOCl immersion) on microtensile bond strength (MTBS) of five adhesive systems to dentin. METHODS: Flat dentin surfaces from 40 molars were bonded with three total-etch adhesives (Single Bond, Prime&Bond NT and the experimental Prime&Bond XP), and two self-etching agents (Clearfil SE Bond and Etch&Prime 3.0). Composite build-ups were constructed with Tetric Ceram. Teeth were then sectioned into beams of 1.0 mm2 cross-sectional area. Half of the beams were immersed in 10% NaOCl aqueous solution for 5 h. Each beam was tested in tension in an Instron machine at 0.5 mm/min. Data were analyzed by 2-way ANOVA and multiple comparisons tests (p < 0.05). RESULTS: Clearfil SE Bond and Single Bond attained higher MTBS than the other three adhesives. Prime&Bond NT and Prime&Bond XP performed equally, and Etch&Prime resulted in the lowest MTBS. After NaOCl immersion, MTBS decreased in all groups. The highest MTBS values were obtained for Clearfil SE Bond and Prime&Bond XP. Scaning electron microscopy observation of debonded sticks evidenced dissolution and microstructural alterations of intertubular dentin, except when Clearfil SE Bond was used. CONCLUSIONS: Resin-dentin bonds are prone to chemical degradation. The extent of the resin degradation is adhesive system specific. Chemical degradation of the nonresin infiltrated collagen fibers does also exist in total-etch adhesives. Both processes may reduce long-term resin-dentin bond strength.     

Balancing high accrual and ethical recruitment in paediatric oncology: a qualitative study of the 'look and feel' of clinical trial discussions

Background  

High accrual to clinical trials enables new treatment strategies to be tested rapidly, accurately and with generalisability. Ethical standards also must be high so that participation is voluntary and informed. However, this can be difficult to achieve in trials with complex designs and in those which are closely embedded in clinical practice. Optimal recruitment requires a balance of both ethical and accrual considerations. In the context of a trial of stratified treatments for children with acute lymphoblastic leukaemia (UKALL2003) we examined how recruitment looked to an observer and how it felt to the parents, to identify how doctors' communication could promote or inhibit optimal recruitment.     

Polyhydramnios with bidirectional fetal ductus arteriosus flow in a fetus with congenital diaphragmatic hernia: case report

The etiology of polyhydramnios may be attributed to either increased production of amniotic fluid (fetal polyuria or high-output cardiac failure) or decreased fetal swallowing (obstruction or neurological impairment). Although idiopathic polyhydramnios occurs in nearly half of all cases, it is often associated with fetal abnormalities. Fetal ductus arteriosus flow is normally from right to left. We report a case of antenatally detected bidirectional fetal ductus arteriosus flow diagnosed concomitantly with polyhydramnios. Amnioreduction was performed due to severe maternal symptoms, which resulted in correction of the fetal ductus arteriosus flow. Postnatal diagnosis of a Morgagni diaphragmatic hernia indicates that our sonographic findings collectively may have been a diagnostic clue.     

p.R254Q mutation in the aquaporin‐2 water channel causing dominant nephrogenic diabetes insipidus is due to a lack of arginine vasopressin‐induced phosphorylation

Vasopressin regulates human water homeostasis by re‐distributing homotetrameric aquaporin‐2 (AQP2) water channels from intracellular vesicles to the apical membrane of renal principal cells, a process in which phosphorylation of AQP2 at S256 by cAMP‐dependent protein kinase A (PKA) is thought to be essential. Dominant nephrogenic diabetes insipidus (NDI), a disease in which the kidney is unable to concentrate urine in response to vasopressin, is caused by AQP2 gene mutations. Here, we investigated a reported patient case of dominant NDI caused by a novel p.R254Q mutation. Expressed in oocytes, AQP2‐p.R254Q appeared to be a functional water channel, but was impaired in its transport to the cell surface to the same degree as AQP2‐p.S256A, which mimics non‐phosphorylated AQP2. In polarized MDCK cells, AQP2‐p.R254Q was retained and was distributed similarly to that of unstimulated wt‐AQP2 or AQP2‐p.S256A. Upon co‐expression, AQP2‐p.R254Q interacted with, and retained wt‐AQP2 in intracellular vesicles. In contrast to wild‐type AQP2, forskolin did not increase AQP2‐p.R254Q phosphorylation at S256 or its translocation to the apical membrane. Mimicking constitutive phosphorylation in AQP2‐p.R254Q with the p.S256D mutation, however, rescued its apical membrane expression. These date indicate that a lack of S256 phosphorylation is the sole cause of dominant NDI here, and thereby, p.R254Q is a loss of function instead of a gain of function mutation in dominant NDI. © 2009 Wiley‐Liss, Inc.     

Association of hepatitis A virus infection with allergic sensitization in a population with high prevalence of hepatitis A virus exposure

BACKGROUND: An inverse association between allergic sensitization and markers of exposure to food-borne and orofecal infections (particularly hepatitis A virus, HAV) has been reported. The prevalence of HAV exposure and allergic sensitization vary widely in different areas, and vary along with age within a given area. AIM: To investigate the association between HAV exposure and allergic sensitization in adults from a mostly rural area of Spain. METHODS: An age-stratified random sample of 720 subjects was drawn from the population older than 18 years of A-Estrada, Spain. From 697 eligible subjects, 469 (67.2%, median age 54 years, range: 18-92) participated in the study. Positive skin prick tests to a panel of aeroallergens defined allergic sensitization. Positive serum HAV antibodies (assayed in 465 subjects) defined HAV exposure. RESULTS: The prevalence of HAV exposure was 83.6% (95% CI: 80.7-86.5). The prevalence of allergic sensitization was lower in subjects with HAV exposure than in patients without it (25.0%vs 40.0%, OR 0.44, 95% CI: 0.25-0.77, P=0.004), but this association became substantially altered after adjusting for age, which was closely linked to both allergic sensitization and HAV exposure (adjusted OR 1.15, 95% CI: 0.60-2.19, P=0.66). CONCLUSIONS: In a population with high prevalence of HAV exposure, no significant association between HAV exposure and allergic sensitization is observed after controlling for the confounding effect of age.