A Study to Evaluate and Compare the Shear Bond Strength of Resilient Liners with Heat Cure Denture Base Resins, with and without the Effect of Saliva: An in vitro Study

Aim: To evaluate and compare the shear bond strength of resilient liners with heat cure denture base resins in the presence or absence of saliva. Materials and methods: Two commercially available heat polymerized acrylics and three commercially available denture liners were immersed in artificial saliva for 7 days and 14 days, respectively. A total of 180 (Acralyn-H, No.90 and Lucitone - 199, No.90) specimens were prepared. Total of 90 overlapping joint specimens were prepared, 45 of them using Acralyn H (AGroup) and rest 45 using Lucitone-199 (L-Group). The specimens were tested for flexural strength with a 3-point bending test on an Instron universal testing machine. The results were analyzed with a one-way analysis of variance (ANOVA). Results: The mean difference in shear bond strength (SBS) at different time intervals was found to be statistically significant (p < 0.001). Lucitone-199 recorded a significantly higher mean SBS compared to Acralyn H (p < 0.001). Further, significant differences between GC and Densply, GC and Aswin liners, and between Dentsply and Aswin were noted (p < 0.001). Difference between baseline and 7 days time interval, as well as, between baseline and 14 days time interval with respect to the mean SBS of these materials were significant (p < 0.001). Also, the mean difference in SBS between 7 days time interval and 14 days time interval was statistically significant (p < 0.001). Among the three different liners, GC yielded a higher mean SBS compared to Aswin and Dentsply at all the three time intervals. The mean SBS recorded in Dentsply and Aswin was almost same at 14 days time interval, but at baseline and 7 days, it was higher in Aswin compared to Dentsply. Conclusion: Lucitone-199 recorded a higher mean SBS compared to Acralyn H. As the time interval increases, the mean SBS recorded in both the denture base materials decrease. Among the three different liners, GC yields a higher mean SBS compared to Aswin and Dentsply at all the three time intervals. Clinical significance: The most common reason for failures of resilient linings in removable dentures is the separation of these linings from the denture base. Therefore, poor adhesive bond properties are one of the serious defects of the material in clinical practice. Keywords: Heat cure resins, Methyl methacrylacte, Polymethylmethacrylate, Percentage of cohesive, Failure, Shear bond strength. How to cite this article: Rao CS, Reddy SS, Prasad GM, Reddy KS, Rao NV, Naik MS. A Study to Evaluate and Compare the Shear Bond Strength of Resilient Liners with Heat Cure Denture Base Resins, with and without the Effect of Saliva: An in vitro Study. J Contemp Dent Pract 2012;13(3):394-400. Source of support: Nil Conflict of interest: None declared.     

Polyvalent mechanical bacterial lysate for the prevention of recurrent respiratory infections: a meta-analysis

BackgroundRespiratory tract infections are common and remain a major source of morbidity, mortality and economic cost worldwide, despite advances in modern medicine. One treatment approach is to non-specifically increase the immune response or augment innate defense mechanisms through the use of bacterial lysates. Polyvalent Mechanical Bacterial Lysate (PMBL) is a bacterial lysate made from a wide range of pathogenic bacteria, including all of the most commonly occurring pathogens of the upper and lower respiratory tract obtained by mechanical lysis.AimTo test the available evidence that PMBL is able to prevent respiratory tract infections.MethodsA number of studies investigating randomized comparisons of PMBL (active) with placebo or no treatment (control) were selected for analysis. The primary outcome measure was the prevention of exacerbations or acute respiratory tract infection. The results were expressed as relative risk (RR) and the number of patients needed to treat for one to benefit (NNTB).ResultsData from 2557 patients from 15 randomized clinical trials (RCTs) was investigated. PMBL induced a significant reduction of infections vs placebo (RR ?0.513; 95% CI; ?0.722 – ?0.303; p = 0.00). The NNTB was 1.15. The RR was always in favor of PMBL (in recurrent respiratory infections other than COPD, chronic bronchitis and tuberculosis, RR ?0.502; 95% CI ?0.824 – ?0.181; in children RR ?2.204; 95% CI ?3.260 – ?1.147; in COPD or chronic bronchitis, RR ?0.404; 95% CI ?0.864–0.057; in tuberculosis, RR ?0.502; 95% CI ?0.890 – ?0.114).ConclusionsThe results of the present meta-analysis suggest that PBML is effective in both in children and in adults in preventing respiratory tract infections. Our current meta-analysis shows that there is a trend with PBML toward clinically significant results in patients with COPD but it did not quite achieve statistical significance due to the small number of COPD studies.     

miR-15a/16 reduces retinal leukostasis through decreased pro-inflammatory signaling

Background

Hyperglycemia is a significant risk factor for diabetic retinopathy and induces increased inflammatory responses and retinal leukostasis, as well as vascular damage. Although there is an increasing amount of evidence that miRNA may be involved in the regulation in the pathology of diabetic retinopathy, the mechanisms by which miRNA mediate cellular responses to control onset and progression of diabetic retinopathy are still unclear. The purpose of our study was to investigate the hypothesis that miR-15a/16 inhibit pro-inflammatory signaling to reduce retinal leukostasis.

Methods

We generated conditional knockout mice in which miR-15a/16 are eliminated in vascular endothelial cells. For the in vitro work, human retinal endothelial cells (REC) were cultured in normal (5 mM) glucose or transferred to high glucose medium (25 mM) for 3 days. Transfection was performed on REC in high glucose with miRNA mimic (hsa-miR-15a-5p, hsa-miR-16-5p). Statistical analyses were done using unpaired Student t test with two-tailed p value. p?<?0.05 was considered significant. Data are presented as mean?±?SEM.

Results

We demonstrated that high glucose conditions decreased expression of miR-15a/16 in cultured REC. Overexpression of miR-15a/16 with the mimic significantly decreased pro-inflammatory signaling of IL-1β, TNFα, and NF-κB in REC. In vivo data demonstrated that the loss of miR-15a/16 in vascular cells led to increased retinal leukostasis and CD45 levels, together with upregulated levels of IL-1β, TNFα, and NF-κB.

Conclusions

The data indicate that miR-15a/16 play significant roles in reducing retinal leukostasis, potentially through inhibition of inflammatory cellular signaling. Therefore, we suggest that miR-15a/16 offer a novel potential target for the inhibition of inflammatory mediators in diabetic retinopathy.

     

Inhibition of Enterococcus faecium adherence to collagen by antibodies against high-affinity binding subdomains of Acm

Strains of Enterococcus faecium express a cell wall-anchored protein, Acm, which mediates adherence to collagen. Here, we (i) identify the minimal and high-affinity binding subsegments of Acm and (ii) show that anti-Acm immunoglobulin Gs (IgGs) purified against these subsegments reduced E. faecium TX2535 strain collagen adherence up to 73 and 50%, respectively, significantly more than the total IgGs against the full-length Acm A domain (28%) (P < 0.0001). Blocking Acm adherence with functional subsegment-specific antibodies raises the possibility of their use as therapeutic or prophylactic agents.     

Dual and selective lipid inhibitors of cyclooxygenases and lipoxygenase: a molecular docking study

The side effects of non-steroidal anti-inflammatory drugs (NSAIDs) concern the public, the government, and pharmaceutical companies. NSAIDs act as inhibitors of cyclooxygenases which are the major cause of pain and inflammation in our body. However, the inhibition of cyclooxygenases could divert arachidonic acid metabolism toward the lipoxygenase pathway leading to other forms of inflammation and tissue damage. Hence a common inhibitor that could block the action of both cyclooxygenases and lipoxygenase is of interest in medicinal chemistry research. Further, the inhibition of both cyclooxygenases-1 and 2 would result in more side effects, since blocking the action of cyclooxygenase-1 would cause gastrointestinal disturbance. Therefore, there is a need to find an inhibitor that acts on cyclooxygenase-2 and lipoxygenase without disturbing the action of cyclooxygenase-1. A molecular docking study with eight lipid ligands was conducted to find the common and selective inhibitors of these three enzymes. Docking with extra precision mode and standard precision mode was performed to find the suitable docking method using the Glide software tool. Docking with extra precision mode yielded better results than with standard precision mode. The docking results are validated using a receiver operator characteristic curve. Further, molecular dynamic simulations were performed for the docked complexes of lowest binding energies. The confirmations obtained from molecular dynamic simulations are more stable and credible than the docked confirmations. Docosahexaenoic acid, eicosapentaenoic acid, 2-arachidonyl glycerol, and anandamide are identified as dual inhibitors of cyclooxygenases and lipoxygenase. α-Tocotrienols are shown to be selective inhibitors of cyclooxygenase-2 and lipoxygenase.     

Endovascular management of axillofemoral bypass graft stump syndrome

OBJECTIVE: Upper extremity embolic complications of occluded axillofemoral bypass grafts are infrequent. However, traditional management of dissection of axillary anastomosis for removal of the stump can be challenging. We report two patients with critical upper extremity ischemia secondary to stump syndrome and its successful management with endovascular techniques. METHODS: One hundred fifty-two patients underwent axillofemoral bypass grafting over 10 years from 1991-2001. Two patients from this series had acute ischemia involving the ipsilateral upper extremity of occluded axillofemoral bypass graft. Duplex ultrasound scans revealed occlusion of the axillofemoral bypass graft and acute occlusion of ipsilateral upper extremity arteries. Both patients underwent brachial artery exploration and embolectomy. Completion angiograms revealed persistent axillofemoral bypass graft stump as the source of embolus. The stump was obliterated with a 10-mm/40-mm Wallgraft introduced through the same arteriotomy made for brachial embolectomy. Transesophageal echocardiography and magnetic resonance angiography of the arch and great vessels were performed to exclude other sources of origin for the embolus. RESULTS: Both patients remained symptom-free and with patent stent grafts, as seen on duplex scans at 3, 6, and 9 months of follow-up. CONCLUSIONS: Upper extremity embolism is a rare complication after occlusion of axillofemoral bypass grafts. The endovascular approach to obliterate the stump of occluded axillofemoral bypass grafts is minimally invasive and an effective alternative treatment of this rare condition.     

Programmed Cell Death (Apoptosis) and Its Role in the Pathogenesis of Lower Extremity Varicose Veins

p < 0.03). This increased apoptotic activity was not observed in media or intima of either vein group (p < 0.001). No significant difference in immunoreactivity to bcl-2 protein was observed in varicose vein specimens as compared to controls. Varicose vein specimens demonstrated increased nuclear expression of cyclin D1 whereas its cytoplasmic expression was significantly diminished (p≤0.02). These data show that programmed cell death is inhibited in varicose veins. Differential expression of cyclin D1 suggests that it may deregulate cell cycle events, thereby leading to varicosity formation.