Effects of non-thermal atmospheric plasma treatment on dentin wetting and surface free energy for application of universal adhesives

Objectives

The study aims to evaluate the effects of non-thermal atmospheric plasma (NTAP) treatments on dentin wetting and surface free energy (SFE) and compare the effects of NTAP treatment, etch-and-rinse, and self-etch protocols for application of universal adhesives.

Materials and methods

Mid-coronal dentin of intact third molars was used to measure contact angles of distilled water, ethylene-glycol, and diiodomethane and calculate SFE following different NTAP preset treatments (feeding gas consisting of pure He, He + 1% O₂, He + 1.5% O₂), power input (1 or 3 W), and tip-to-surface distance (2, 4, or 8 mm). Contact angles of reference liquids and SFE of dentin following He + 1.5% O₂ at 3-W and 4-mm treatment was compared to phosphoric acid etching. Contact angles of Single Bond Universal (SBU; 3M ESPE) and Clearfil Universal Bond (CUB; Kuraray Noritake) were measured following NTAP, etch-and-rinse, and self-etch protocols.

Results

NTAP significantly reduced contact angles of reference liquids and increased dentin SFE compared to untreated dentin (p < 0.05). O₂ intensified the effect of He NTAP (p < 0.05). NTAP and phosphoric acid increased dentin polarity and Lewis base surface characteristics. Phosphoric acid increased contact angles of adhesives compared to the self-etch protocol (p < 0.05). NTAP resulted in lower adhesive contact angles than phosphoric acid, the difference being statistically significant for CUB (p < 0.05). Compared to the self-etch protocol, NTAP slightly reduced CUB contact angle but not that of SBU (p > 0.05).

Conclusions

He NTAP with and without O₂ increased dentin wetting and SFE, surpassing the effect of phosphoric acid and lowering adhesive contact angles. NTAP produced no apparent micro-morphological changes on dentin surface comparable to acid etching.

Clinical significance

NTAP treatment of dentin prior to adhesive application increases dentin wetting and surface free energy facilitating better adhesive distribution on dentin surface compared to phosphoric acid etching and similar to the “self-etch” application protocol.

     

The Impact of Community Diversity and Consolidated Inequality on Dropping Out of High School

Abstract: Data from the National Education Longitudinal Study were combined with census data at the zip code level to examine the impact of neighborhood racial and ethnic diversity and consolidated inequality, in addition to individual, family, and school factors, on the likelihood of dropping out of high school. Results indicate that while the effects for diversity and consolidated inequality did not support the stated hypotheses, main effects for family risk and prior academic achievement were significant and in the stated direction. Also, when controlling for individual, family, school, and neighborhood characteristics, African Americans were less likely than White students to drop out of school. Implications for contextual effects research and educational outcomes are discussed.     

Heart insufficiency in traumatic arteriovenous fistulas

Objective: To analyse the incidence, clinical presentation, and outcome of heart insufficiency in patients with chronic arteriovenous fistulas (AVF). Methodology: From 1991 to 2000 we treated 49 patients with traumatic AVF. The present study included 19 patients with AVF present for 6 months or longer, as it was presumed that these AVF will have an impact on cardiac overload. There were 16 male and three female patients with a mean age of 36 years (17–59). The time from injury to admission varied from 6 months to 33 years. Cardiological examination checked for dyspnoea and palpitation. ECG, chest X‐ray and ECHO‐cardiography were also performed. All AVF were deleted, magistral vessels reconstructed, non‐magistral obliterated, either surgically or by percutaneous embolization. Results: Mean follow up was 44.2 months (3–93). Serious heart insufficiency was seen in two patients only, with AVF in the subclavial vessels. Both suffered from serious heart disease prior to the therapeutic procedures that resulted in iatrogenic AVF, so it was difficult to connect heart insufficiency to the AVF alone. Despite surgical closure of AVF and intensive medical treatment, signs of heart insufficiency remained in both patients. Signs of cardiac overload were seen in six patients with long‐standing AVF in major vessels. Except for one patient who refused surgical closure of femoral AVF, the remaining five were symptom free for cardiac overload during the follow‐up period. Conclusion: In our series, heart insufficiency was an infrequent complication in long‐standing AVF, even when major vessels were involved.     

What some patients can eat during migraine attacks: therapeutic and conceptual implications

Although nausea and vomiting are diagnostic migraine symptoms, most patients can take tablets by mouth and a few say they can eat some food. This study was conducted to determine the proportion who could eat or drink, what was consumable and with what effect. One-hundred-and-nine migraineurs were asked what they could eat or drink at the beginning or height of their attacks; 59 could not take any food by mouth, but 50 could eat during the headache phase of their migraine attacks. Four ate normally, 5 took smaller amounts of their normal dietary intake, and 3 took lighter meals. Dry, carbohydrate foods were consumable by the remaining 38: a few had specific cravings, most stated the precise variety which, when eaten, reduced nausea, headache, other symptoms or length of attacks. Patients should therefore be encouraged to eat what they can tolerate, with their tablets taken as early as possible after the onset of attacks. Simultaneous nausea, tolerance or even craving for specific foods occur in other conditions, particularly high altitude headaches which share other features of migraine attacks. The observations in this paper support the notion that migraine is a central neuronal metabolic disturbance.     

Headaches in civil servants: effect on work and leisure

Headaches in a group of civil servants and their effects on work and leisure activities, the medication taken, and numbers consulting their general practitioners during a year were assessed by a self administered questionnaire sent to 1000 civil servants in sections of a government department in London. The response rate was 74.7%. Altogether 77% of the respondents reported having had headaches in the previous 12 months. There was a higher prevalence in women (88%) than men (70%) and a significant decrease with increasing age. Women also had more frequent and severe headaches than men: 34% reported that headaches had interfered with work, either by impaired performance, making them leave work early, or by stopping them coming into work. About half of those who reported having severe headaches denied that they had affected their work, indicating difficulty in interpreting the term "severe." Nevertheless, 22% said that headaches interfered with their leisure activities as well as work which may be regarded as further evidence that the condition was truly disabling. Eighty per cent of those with headaches took medication, but within the past year only 11% had consulted their general practitioner and only 2.2% had been referred for further specialist opinion. Of the 22% who had not had a headache during the previous 12 months, 5.6% had never had a headache. In this group there was a larger proportion of men, a higher proportion with increasing age, and a higher proportion in non-desk working grades. Differentiation of the causes of headaches was not attempted in this survey but it is concluded that the extent to which they interfere with work and leisure is an important guide to their severity. It is suggested that the occupational health services may have an important role in assessing the causes of headaches and instituting preventive measures that benefit both the worker and industry.     

Tetracycline-regulated gene expression following direct gene transfer into mouse skeletal muscle

For most experimental and therapeutic applications of gene transfer, regulation of the timing and level of gene expression is preferable to constitutive gene expression. Among the systems that have been developed for pharmacologically controlled gene expression in mammalian cells, the bacterial tetracycline (tet)-responsive system has the advantage that it is dependent on a drug (tet) that is both highly specific and non-toxic. The tet-responsive system has been previously used to modulate expression of cell cycle regulatory proteins in cultured cells, reporter genes in plants and transgenic mice and reporter genes directly injected into the heart. Here we show that orally or parenterally administered tet regulates expression of tet-responsive plasmids injected directly into mouse skeletal muscle. Reporter gene expression was suppressed by two orders of magnitude in the presence of tet, and that suppression was reversed when tet was withdrawn. These data show that skeletal muscle offers an accessible and well characterized target tissue for tet-controlled expression of genesin vivo, suggesting applications to developmental studies and gene therapy.     

Human monoclonal antibodies against amyloid-beta from healthy adults

Two anti-amyloid-beta human antibody-producing cell lines were established from amyloid-beta (Abeta)-selected lymphocytes from peripheral blood of healthy adults. ELISA and Western blot analysis showed that the monoclonal antibodies bound with high affinity to the 43 amino acid-long amyloid-beta peptide. The antigen epitope of these antibodies encountered within amino acids 1-16 of the amyloid-beta peptide. The antibodies did not bind to several immunoglobulin light chain amyloids (AL) and amylin. One of the monoclonals was tested by immunohistochemistry for the binding to frozen sections of brains derived from patients with Alzheimer's disease. It specifically and intensively stained diffuse and core amyloid-beta plaques; whereas, sections from normal brains were not stained. Concomitant staining with a commercial mouse anti-amyloid-beta monoclonal antibody co-localized with that of the human antibody. Simultaneous staining with the human antibody and Congo red implied that the antibody binds primarily to an early immature form of beta-amyloid. Human monoclonal antibodies, which resemble physiologically normal non-pathogenic and possibly protective antibodies in healthy adults, might be attractive candidates for immune therapy of Alzheimer's disease.     

Mechanisms of cold sensitivity of paramyotonia congenita mutation R1448H and overlap syndrome mutation M1360V

Missense mutations of the human skeletal muscle voltage-gated Na⁺ channel (hSkM1) cause a variety of neuromuscular disorders. The mutation R1448H results in paramyotonia congenita and causes cold-induced myotonia with subsequent paralysis. The mutation M1360V causes an overlapping syndrome with both K⁺-induced muscle weakness and cold-induced myotonia. The molecular mechanisms of the temperature dependence of these disorders are not well understood. Therefore we investigated physiological parameters of these Na⁺ channel mutations at different temperatures. Channel proteins were recombinantly expressed in human embryonic kidney cells and studied electrophysiologically, using the whole-cell patch-clamp technique. We compared the wild-type (WT) channel with both mutants at different temperatures. Both mutations had slower inactivation and faster recovery from inactivation compared to WT channels. This effect was more pronounced at the R1448H mutation, leading to a larger depolarization of the cell membrane causing myotonia and paralysis. The voltage dependence of activation of R1448H was shifted to more negative membrane potentials at lower temperature but not at the M1360V mutation or in the WT. The window current by mutation R1448H was increased at lower temperatures. The results of this study may explain the stronger cold-induced clinical symptoms resulting from the R1448H mutation in contrast to the M1360V mutation.