Transcriptomic Response in the Spleen after Whole-Body Low-Dose X-Ray Irradiation.

As the use of medical radiation procedures continues to rise, it is imperative to further our understanding of the effects of this exposure. The spleen is not known as a particularly radiosensitive organ, although its tolerance to radiation is not well understood. Low-dose radiation exposure has been implicated in beneficial responses, particularly in cell death and DNA damage repair. In this study, adult male rats received 2, 20, 200 mGy or 4 Gy whole-body X-ray irradiation and the transcriptional response in the spleen was analyzed at 0.5, 4 and 24 h postirradiation. We analyzed expression of genes involved in apoptosis, cell cycle progression and DNA damage repair. As expected, 4 Gy irradiated animals demonstrated elevated expression of genes related to apoptosis at 0.5, 4 and 24 h postirradiation in the spleen. These animals also showed upregulation of DNA damage repair genes at 24 h postirradiation. Interestingly, the spleens of 20 mGy irradiated animals showed reduced apoptosis and cell cycle arrest compared to the spleens of sham-irradiated animals. These results further reveal that the cellular response in the spleen to whole-body irradiation differs between low- and high-dose irradiation.

Pharmacologic strategies to reduce cardiovascular disease in type 2 diabetes mellitus: focus on SGLT-2 inhibitors and GLP-1 receptor agonists.

Patients with type 2 diabetes mellitus (T2D) present an increased risk for cardiovascular (CV) complications. In addition to improvement in glycaemic control, glucose-lowering therapies, such as glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-dependent glucose cotransporter (SGLT)-2 inhibitors, have been shown to significantly reduce CV events. In 2008, the US Food and Drug Administration mandated that all new glucose-lowering drugs undergo CV outcomes trials (CVOTs) to determine their CV safety. These trials have largely demonstrated no major CV safety concerns. Most notably, the GLP-1RAs and SGLT-2 inhibitors have been found to be not only safe, but also cardioprotective compared to placebo. The SGLT-2 inhibitors have opened a new perspective for clinicians treating patients with T2D and established CV disease in light of their 'pleiotropic' effects, specifically on heart failure, while GLP-1RAs seem to present more favourable effects on atherosclerotic events. In this review, we discuss the role of GLP-1RAs and SGLT-2 inhibitors to reduce CV risk in T2D patients and suggest an individualized therapeutic approach in this population based on the presence of metabolic and CV comorbidities.

Leukocytes in expressed breast milk of asthmatic mothers.

OBJECTIVE: Infants are born immunologically immature. However, breastfeeding mothers retain an immunological link to their infants. While it is generally accepted that infants are at an immunological advantage when compared with formula-fed infants, the benefit of long-term exclusive breastfeeding by atopic mothers remains controversial. Inconsistency in the conferral of benefit may be due to differences in the immunological constituents passed to the recipient infant. The aim of this investigation was to examine the profile of human milk cells and cytokines from asthmatic compared to non-asthmatic mothers. METHODS: Twenty-five exclusively breastfeeding mothers with a clinical diagnosis of asthma were postpartum age matched in a double-control 2:1 design with 50 non-asthmatic controls. Each mother provided a single milk sample which was assayed for cell differential by flow cytometry, for ex vivo cytokine production in culture and for aqueous phase cytokines. RESULTS: Milks from asthmatic mothers differed from non-asthmatics in that they contained a higher proportion of polymorphonuclear (PMN) cells and lower proportion of lymphocytes, predominantly CD3+/CD4+ T helper cells, reflected by a decrease in the chemokine CCL5 in the milk aqueous phase. More PMN and lymphocytes from asthmatic mothers expressed the adhesion molecule CD11b and lymphocytes the IgE receptor CD23, than those from non-asthmatic mothers. CONCLUSIONS: Changes to human milk leucocyte prevalence, activation state and cytokines due to maternal asthma may result in changes to immunological priming in the infant. Consequently, the protective effect of long-term breastfeeding may be altered in these mother-infant pairs.

Accuracy of casts generated from dual-arch impressions.

STATEMENT OF PROBLEM: Dual-arch trays are often used to make simultaneous impressions of a prepared tooth and the opposing teeth. Many dentists are concerned with the accuracy of the casts generated from this type of impression. PURPOSE: The purpose of this investigation was to compare the accuracy of stone casts of a prepared tooth generated using 2 types of dual-arch impression tray/impression material combinations. MATERIAL AND METHODS: The maxillary left first molar on a dentoform mounted on an articulator was prepared for a full-coverage gold crown. Ten impressions were made with either a plastic (P) or metal (M) tray and a polyether (PE) or vinyl polysiloxane (VPS) impression material. Each impression was cast in improved dental stone, and the buccolingual dimension of the die was measured at the midpoint of the buccal and lingual gingival margins. The prepared tooth (T) served as the control. The data were analyzed using a 2-factor analysis of variance (ANOVA) alpha=.05. RESULTS: The P/VPS combination (10.673 mm) produced the largest die, followed by P/PE (10.602), T (10.508), M/PE (10.484), and M/VPS (10.472). The 2-factor ANOVA showed a significant difference between the tray types but not between the impression materials. CONCLUSION: The metal trays produced dies smaller than the tooth, and the plastic trays produced dies that were larger.

Overview of articulation materials and methods for the prosthodontic patient.

STATEMENT OF PROBLEM: Many methods and materials are available for registering the centric relation position, with various degrees of accuracy. Once the centric relation position is recorded, many instruments are available for cast articulation. These articulators range from simple to complex devices that generate different mandibular movements depending on the sophistication of the instrument. PURPOSE: This review evaluated the methods and materials used to record the centric relation position and eccentric maxillomandibular relations, and to compare the articulators available for mounting casts. METHODS: A MEDLINE search was completed (from 1966-present) along with personal searches of selected journals to find additional publications that addressed these materials, methods of registration, and available instrumentation. CONCLUSION: Potential applications of this review are as follows: (1) to allow the reader to examine the various methods for recording the centric relation position that have been studied and described, and (2) to observe how the accuracy of recording materials have changed over time. The reader will also realize the types of simple and complex articulators that exist, along with the different degrees of simulated mandibular movements that may be accomplished.

Achieving results through transformational leadership.

Transformational leaders must balance capable management with transformational skills that create shared vision, inspire others to embrace it, and empower them to lead implementation efforts. This balancing act requires leaders to be grounded in their personal values, live a balanced life, and continuously learn. A case example demonstrates how a former nurse executive, now a chief operating officer of one of the nation's top 100 integrated health systems, puts these concepts into action.

An in vitro study of implant--tooth-supported connections using a robot test system.

Many unsolved problems in dental implant research concern the interfacial stress distributions between the implant components, as well as between the implant surface and contacting bone. To obtain a mechanical understanding of how vertical and horizontal occlusal forces are distributed in this context, it is crucial to develop in vitro testing systems to measure the force transmission between dental implants and attached prostheses. A new approach to such testing, involving a robotic system, is described in this investigation. The system has been designed to produce simulated mandibular movements and occlusal contact forces so that various implant designs and procedures can be thoroughly tested and evaluated before animal testing or human clinical trials. Two commonly used fixed prosthesis designs used to connect an implant and a tooth, a rigid connection and a nonrigid connection, were fabricated and used for experimental verification. The displacement and force distributions generated during simulated chewing activities were measured in vitro. Force levels, potentially harmful to human bone surrounding the connected dental implant and tooth, were analyzed. These results are useful in the design of prostheses and connecting components that will reduce failures and limit stress transfer to the implant/bone interface.

Tensile bond strengths of provisional luting agents used with an implant system.

STATEMENT OF PROBLEM: Retrievability of cemented implant-supported fixed prostheses is desirable. Retentive strengths of new provisional luting agents have not been reported. PURPOSE: This study compared the tensile bond strengths of 6 provisional luting agents when used with cemented superstructures and 1 implant system. MATERIAL AND METHODS: Ten castings were fabricated and randomly paired with abutment specimens. Castings were cemented and the assemblies were stored in distilled water at 37 degrees C for 48 hours. Tensile bond strength necessary to remove each casting was measured with a 500-kg load and a crosshead speed of 0.5 cm/min. Crown/abutment specimens were cleaned after testing, and the testing procedure was repeated for a total of 6 luting agents (n = 10). Data were analyzed with 1-way analysis of variance and Scheffé's analysis (alpha=.05). RESULTS: Tensile bond strengths ranged between 1.29 and 4.08 MPa. The lowest tensile bond strengths were found to be statistically similar between Temp Bond and Provilink luting agents. Neo-Temp luting agent exhibited the highest tensile bond strength (P <.01). CONCLUSIONS: Temp Bond and Provilink luting agents exhibited the lowest mean tensile bond strengths. Neo-Temp luting agent exhibited a tensile bond strength more than 3 times that of Temp Bond luting agent.

Microwave disinfection of denture base materials colonized with Candida albicans.

STATEMENT OF PROBLEM: Infection of denture materials with Candida albicans is common and contributes to denture stomatitis. PURPOSE: This 3-phase investigation examined: (1) the efficacy of microwave irradiation against C albicans colonized on 3 soft denture liners and 1 heat-polymerized denture base resin, and (2) the effect of this irradiation on the hardness of the materials tested. MATERIAL AND METHODS: In phase 1, an experimental protocol was developed. Sterilized specimens from 2 denture base soft liners and 1 heat-polymerized acrylic resin denture base material (n = 45 each) were inoculated with C albicans. Two thirds of the specimens were irradiated in a 60 Hz microwave oven for 5 minutes (dry). C albicans growth was then assessed with streaked blood agar plates and thioglycollate broth. One third of the specimens were not irradiated and served as controls. Pretest and posttest Shore A hardness values were obtained and compared. For phase 2, 15 specimens from each material group were subjected to irradiation (while immersed in water) for 5 minutes; and, 15 from each material were subjected to 10- and 15-minute irradiation (dry), with subsequent sterility and change in hardness assessments completed as described in phase 1. In phase 3, 15 specimens from each material group were subjected to repeated 5-minute irradiation cycles (while immersed in water), and changes in hardness were examined. RESULTS: Only the 5-minute irradiated specimens immersed in water were effectively sterilized, as verified by the thioglycollate assay. The effect of repeated 5-minute irradiation cycles resulted in a significant change in hardness of the PermaSoft specimens. CONCLUSIONS: Five-minute irradiation, while immersed in water, killed all C albicans present on the materials tested; and, repeated 5-minute irradiation significantly affected the hardness of only the PermaSoft material.

In vitro mechanical property comparison of four resins used for fabrication of provisional fixed restorations.

PURPOSE: This study recorded and compared the flexural elastic moduli and moduli of rupture of four materials (Provipont DC resin, Triad provisional restorative material, Jet acrylic resin, and a 50:50 mixture of Jet acrylic resin and orthodontic resin) used to make provisional restorations. MATERIAL AND METHODS: Thirty-nine identical 63 x 10 x 3 mm specimens were made from each of the four materials. After 24 hours, 30 days, and 60 days of water storage at 37 degrees C (13 specimens each), standard three-point bend tests were conducted on an Instron universal testing machine at a crosshead speed of 0.5 cm/minute. Stress strain curves were generated, and values for the flexural elastic moduli and moduli of rupture were calculated. Data were subjected to two-way and one-way analyses of variance (alpha = 0.05). RESULTS: Provipont DC resin exhibited significantly higher flexural elastic moduli and moduli of rupture values at the 24-hour test time. However, Provipont DC resin exhibited the greatest decrease in these values over time.

Shear bond strengths of a two-paste system resin luting agent used to bond alloys to enamel.

STATEMENT OF PROBLEM: Adhesive resin luting agents are used to successfully bond the metal surfaces of fixed prostheses to teeth. Panavia 21 luting agent is a new addition to the series of Panavia adhesive resin luting agents. PURPOSE: This investigation measured the shear bond strengths of two types of alloy specimens (Olympia and Rexillium III) bonded to prepared human enamel (etched and unetched) with Panavia 21. MATERIAL AND METHODS: After a simulated porcelain firing sequence, the alloy specimens were bonded to the teeth and subjected to shear testing after water storage for 2 weeks, thermocycling for 500 cycles, and water storage for an additional 2 weeks. Data were analyzed with a two-way analysis of variance (alpha = 0.05). RESULTS: The shear bond strengths of Rexillium III and tinplated Olympia specimens bonded to prepared and unetched enamel were significantly lower than for specimens bonded to prepared and etched enamel with Panavia 21 luting agent.

The effect of metal surface treatment on the shear bond strengths of base and noble metals bonded to enamel.

Adhesive resin luting agents provide a way for bonding metal surfaces to teeth through a combination of micromechanical retention to the rough metal surface and chemical adherence to metal oxides. The purpose of this study was to measure the effect of metal alloy surface treatments that would produce different textures and oxide layers on the shear bond strength of three alloys luted to etched enamel with one adhesive resin luting agent (Panavia). After a simulated porcelain firing sequence, high noble (Olympia), noble (Jelstar), and base metal (Rexillium III) alloy specimens were subjected to one of the following treatments: (1) sandblasting and simulated glazing, (2) simulated glazing only, (3) simulated glazing and sandblasting, or (4) simulated glazing, sandblasting, and tin plating. The specimens were bonded to extracted teeth and subjected to shear testing after water storage for 2 weeks, thermocycling for 500 cycles, and water storage for an additional 2 weeks. Data were analyzed with a two-way analysis of variance (alpha = 0.05). The base metal specimens and the tin-plated high noble and noble metal specimen groups exhibited similar mean shear bond strengths that were greater than the other groups. Those high noble and noble metal alloys sandblasted after simulated porcelain firing cycles and before the simulated glaze cycle exhibited nonsignificant increases in shear bond strengths compared with the groups that were either sandblasted after the simulated glaze cycle or not sandblasted at all.

Surgical guide fabrication for an angled implant.

This article describes the steps necessary for determining ideal implant abutment position and, subsequently, the optimum implant location that would make this abutment position possible. Procedures necessary for fabricating a surgical guide are explained for placing an ITI angled implant.

The effect of simulated function on the retention of bar-clip retained removable prostheses.

Patients wearing bar-clip retained removable prostheses may have loss of retention because of changes within the bar-clip assembly. This in vitro study recorded and compared the retention of one- and two-clip retained simulated mandibular complete denture prostheses before and after simulated function. Cast metal Hader bars and clip holders were used to make 10 one-clip and 10 two-clip specimen pairs. Tensile removal values before and after simulated function were recorded and compared by repeated-measures analysis of variance and Student tau tests (significance level 0.05). The results revealed that the use of two clips instead of one significantly increased retention of the simulated prosthesis. It was also found that there was a significant loss of retention after the specimens were placed on the bars and then removed once for both the one- and two-clip groups. Simulated function did not cause a significant change in retention for either group.

Transfer of gingival contours to a master cast.

This procedure provides a means for transferring intraorally formed gingival sulcular contours surrounding a single-tooth implant-supported provisional restoration to a master cast. When this procedure is used, the final fixed prosthesis may be made in the laboratory with gingival contours identical to those developed on the provisional restoration.

Mechanical considerations for the implant tooth-supported fixed partial denture.

The implant tooth-supported fixed partial denture presents a biomechanical design problem, because the implant is rigidly fixed within the alveolus, and the tooth is surrounded by a periodontal ligament that allows movement. Nonrigid fixed partial denture designs are advocated by some dentists as a method of compensating for this differential movement. Rigid fixed partial denture designs, however, are advocated by many clinicians. Studies have failed to show the advantage of one design over the other. This study developed an in vitro method for testing such prosthesis designs and measured movement of a natural tooth abutment during simulated function. The movement of the natural tooth abutment was not found to change substantially with the fixed partial denture designs tested.

Comparison of screw loosening, rotation, and deflection among three implant designs.

A common problem associated with single tooth implant restorations is abutment screw loosening. Manufacturers of implants have attempted to overcome this problem by incorporating antirotational design characteristics into their systems. Micromovement and torque levels required to loosen abutment screws for straight and angled antirotational screw-retained abutment/implant combinations from three different manufacturers were examined in this in vitro investigation. A custom-built machine was used and each sample was subjected to compressive horizontal reciprocal movements over a 25-degree incline for a simulated 1-month period. Data were generated that showed movements of the crown/abutment complex during force application. The amount of torque necessary to loosen the abutment screws before and after testing was also recorded and compared for each system. The results indicated no significant differences (p < 0.05) among all the straight and angled abutments for the variables studied.