Esophageal and biliary stents are indwelling devices used in the treatment of selected gastrointestinal and biliary disorders. Stenting is accepted as a standard procedure for palliation of malignant obstruction of the esophagus and biliary system. Review of the early and late complications associated with these devices is made with emphasis on the clinical and radiographic features. A suggested approach to diagnosis and treatment recommendations are made for each complication that the emergency department physician may encounter.

Assessment Centers (ACs) are a fantastic method to measure behavioral indicators of job performance in multiple diverse scenarios. Based upon a thorough job analysis, ACs have traditionally demonstrated very strong content and criterion-related validity. However, researchers have been puzzled for over three decades with the lack of evidence concerning construct validity. ACs are designed to measure critical job dimensions throughout multiple situational exercises. However, research has consistently revealed that different behavioral ratings within these scenarios are more strongly related to one another (exercise effects) than the same dimension rating across scenarios (dimension effects). That is, results from ACs suggest that we are unsure of what these behavioral measures represent. Over the last three decades, researchers have sought to illuminate why same dimension ratings are inconsistent across scenarios. However, these investigations have been limited to changes influencing the source of the ratings (e.g., assessors, trained raters). No approach has been taken to change the structure of the AC. This study breaks with tradition and introduces a structurally different AC: A Day-In-The Life AC (DITLAC). A DITLAC structure is designed to mimic that of a normal day on the job. In the present study, the construct validity between a DITLAC and a traditionally structured AC is compared with the argument that the DITLAC will demonstrate stronger construct validity evidence. In several cases, this was found to be true.

Endwall film cooling is a necessity in modern gas turbines for safe and reliable operation. Performance of endwall film cooling is strongly influenced by the hot gas flow field, among other factors. For example, aerodynamic design determines secondary flow vortices such as passage vortices and corner vortices in the endwall region. Moreover blockage presented by the leading edge of the airfoil subjects the incoming flow to a stagnating pressure gradient leading to roll-up of the approaching boundary layer and horseshoe vortices. In addition, for a number of heavy frame power generation gas turbines that use cannular combustors, the hot and turbulent gases exiting from the combustor are delivered to the first stage vane through transition ducts. Wakes induced by walls separating adjacent transition ducts located upstream of first row vanes also influence the entering main gas flow field. Furthermore, as hot gas enters vane passages, it accelerates around the vane airfoils. This flow acceleration causes significant streamline curvature and impacts lateral spreading endwall coolant films. Thus endwall flow field, especially those in utility gas turbines with cannular combustors, is quite complicated in the presence of vortices, wakes and strong favorable pressure gradient with resulting flow acceleration. These flow features can seriously impact film cooling performance and make difficult the prediction of film cooling in endwall. This study investigates endwall film cooling under the influence of pressure gradient effects due to stagnation region of an axisymmetric airfoil and in mainstream favorable pressure gradient. It also investigates the impact of wake on endwall film cooling near the stagnation region of an airfoil. The investigation consists of experimental testing and numerical simulation. Endwall film cooling effectiveness is investigated near the stagnation region on an airfoil by placing an axisymmetric airfoil downstream of a single row of inclined cylindrical holes. The holes are inclined at 35° with a length-to-diameter ratio of 7.5 and pitch-to-diameter ratio of 3. The ratio of leading edge radius to hole diameter and the ratio of maximum airfoil thickness to hole diameter are 6 and 20 respectively. The distance of the leading edge of the airfoil is varied along the streamwise direction to simulate the different film cooling rows preceding the leading edge of the airfoil. Wake effects are induced by placing a rectangular plate upstream of the injection point where the ratio of plate thickness to hole diameter is 6.4, and its distance is also varied to investigate the impact of strong and mild wake on endwall film cooling effectiveness. Blowing ratio ranged from 0.5 to 1.5. Film cooling effectiveness is also investigated under the presence of mainstream pressure gradient with converging main flow streamlines. The streamwise pressure distribution is attained by placing side inserts into the mainstream. The results are presented for five holes of staggered inclined cylindrical holes. The inclination angle is 30° and the tests were conducted at two Reynolds number, 5000 and 8000. Numerical analysis is employed to aid the understanding of the mainstream and coolant flow interaction. The solution of the computational domain is performed using FLUENT software package from Fluent, Inc. The use of second order schemes were used in this study to provide the highest accuracy available. This study employed the Realizable º-µ model with enhance wall treatment for all its cases. Endwall temperature distribution is measured using Temperature Sensitive Paint (TSP) technique and film cooling effectiveness is calculated from the measurements and compared against numerical predictions. Results show that the characteristics of average film effectiveness near the stagnation region do not change drastically. However, as the blowing ratio is increased jet to jet interaction is enhanced due to higher jet spreading resulting in higher jet coverage. In the presence of wake, mixing of the jet with the mainstream is enhanced particularly for low M. The velocity deficit created by the wake forms a pair of vortices offset from the wake centerline. These vortices lift the jet off the wall promoting the interaction of the jet with the mainstream resulting in a lower effectiveness. The jet interaction with the mainstream causes the jet to lose its cooling capabilities more rapidly which leads to a more sudden decay in film effectiveness. When film is discharged into accelerating main flow with converging streamlines, row-to-row coolant flow rate is not uniform leading to varying blowing ratios and cooling performance. Jet to jet interaction is reduced and jet lift off is observed for rows with high blowing ratio resulting in lower effectiveness.

Indiana University-Purdue University Indianapolis (IUPUI) / External apical root resorption (EARR) is a common complication of orthodontic treatment. Genetic factors account for approximately 50% of the variation in EARR. Data have indicated variation in histological root resorption associated with orthodontic force (RRAOF) among different inbred strains of mice. Differences in expression of RANKL and OPG were investigated in two strains of mice with different susceptibility to RRAOF using irnmunohistochemistry. Increased localization of RANKL was detected in the tissues surrounding the root of the susceptible strain compared to the resistant strain and the controls. In contrast, increased localization of OPG was found in the tissues surrounding the roots in the resistant A/J strain compared to the susceptible DBA/2J strain. We conclude that differences in the expression of these key bone resorption mediators play a role in determining RRAOF susceptibility. Changes in serum TRAP 5b level in response to orthodontic force were investigated among female A/J, DBA/2J and BALB/cJ mice. The three strains differed in their TRAP positive cell numbers as well as their serum TRAP 5b level at baseline and when treated. A significant increase in the serum TRAP 5b level with treatment was only detected in the RRAOF susceptible DBA/2J strain, and not in RRAOF resistant strains. Our analysis indicates that differences in osteoclast/odontoclast activity play a role in susceptibility to RRAOF that is genetically determined. Serum TRAP 5b levels have a potential role in screening for individuals with greater susceptibility to root resorption. RRAOF was determined for male and female mice of the A/J, DBA/2J and BALB/cJ strains, as well as A/J x DBA/2J and A/J x BALB/cJ crosses. Sex differences were observed among the BALB/cJ strain only, with females more resistant to RRAOF when compared to males. Fis from the A/J x BALB/cJ cross were resistant suggesting that the A/J have dominant resistance alleles, while Fis from the A/J x DBA/2J cross had RRAOF intermediate between their parental A/J and DBA/2J mice, suggesting a polygenic trait. We concluded that the mode of inheritance of RRAOF in mice was polygenic in nature.

Indiana University-Purdue University Indianapolis (IUPUI) / It has been proposed that the accumulation of microdamage in bone of aging individuals may play a causative and synergistic role in increased fracture incidence. If microdamage production were somehow increased, or reparative remodeling was somehow decreased, the scales may tip towards pathologic fracture. It is known that bisphosphonates increase microdamage accumulation in ribs, lumbar vertebrae, and ilium. The specific aim of this study was to histomorphometrically quantify the microdamage effect of the bisphosphonates alendronate and risedronate therapy on alveolar bone surrounding the first mandibular molar in the dog to determine if this response differs from that in non-bisphosphonate treated dogs. Thirty-four dogs were randomly assigned in two test, and one control groups. Test groups received pharmacologically equivalent doses of either alendronate (11 dogs) or risedronate (11 dogs). The control group (12 dogs) received subcutaneous injections of saline solution. The mandibular right first molar was analyzed for this study. Histomorphometric measurements were made using a x150 Nikon Optiphot-2 fluorescence microscope equipped with brightfield sources (Nikon, Inc.) using the semi-automatic Bioqant digitizing system (R & M Biometrics). There was no significant differences in cortical bone area across treatment groups for any of the regions, nor were any expected. Overall, there was almost twice as much crotical bone found in the Middle (Combined) regions compared with the Coronal (Combined) regions. The precent cortical area was universally high across all treatment groups averaging in the mid-90% range. The Apical region averaged 96.05%, followed by the Coronal region with 95.04% and the Middle region with 93.80%. The number of labeled osteons per cortical area in the alendronate and risedronate groups both tended to be lower relative to the control group (0.92/mm2 and 0.93/mm2 vs. 1.26mm2, respectively), but were not significantly different. On average, the coronal regions had nearly three times the LOn/CtAr as the Middle and Apical regions (1.90/mm2 vs. 0.63/mm2 and 0.57/mm2 respectively). Only in one region was MAR statistically higher in the Coronal (1mm) region, relative to all other regions compared. The Middle region demonstrated a low MAR. The WTh was significantly higher in the risedronate and alendronate groups than that of the control group for the Coronal region. This illustrates that with respect to the bisphosphonates, there is more formation and less resorption. In one region of a significantly lower WTh for the alendronate group relative to the risedronate group was noted. This implies a more potent inhibition in the risedronate treated groups. The WTh for the entire Coronal was statistically lower than every Middle measurement, but was not different than observed in the Apical region. This would tend to signify that in the Coronal, the turnover rate is more of a rapid nature, and therefore the osteons are not as large, while in the Apical, there were so many missing values due to the low rate of turnover, the numbers are skewed to the low end. In the Coronal (Combined) region, the risedronate (108.79 days) group exhibiting a significantly higher FP than the alendronate (62.88 days) and the control (56.13 days) groups. This would imply an increased potency of risedronate over alendronate. Regionally, the FP was significantly lower in the Coronal, relative to Middle or Apical. This is consistent with a more rapid turnover in the Coronal regions observed earlier. The Acf for alendronate (6.41/mm2 per day) and risedronate (5.69/mm2 per day) both tended to be lower by approximately 40% when compared with the control group (10.11/mm2 per day). Overall, the Acf for the Coronal region was 14.15/mm2 per day vs. 2.98/mm2 per day for the Middle and 9.13/mm2 per day for the Apical regions. This shows a significantly increased amount of turnover events taking place not just in the Coronal region, but in the region immediately adjacent to the tooth in the Coronal region. In no region did bone formation differ significantly when treated with bisphosphonates. The Coronal (1mm) region was statistically greater than every region it was measured against, individual and combined. Based on this observation, the second hypothesis that within the first molar alveolar site, bisphosphonate therapy with alendronate, and risedronate would inhibit remodeling more in the coronal region than in the middle and apical region, is rejected. When measuring microdamage accumulation (CrDn), only in the Middle (1mm) region was a significant difference across treatment groups notes. There were no other statistical differences across groups for any other regions. This observation demonstrates that bisphosphonate treatment does not increase the accumulation of microcracks in the dentate alveolar bone. Therefore, the first hypothesis that within the dentate mandible, bisphosphonate therapy with alendronate and risedronate would increase microdamage accumulation around the first molar compound to control, is rejected. When CrDn was compared by region, significant differences were noted. As expected, the Coronal (1mm) region demonstrated a significantly increased CrDN compared with the Apical and Middle regions. Coupled with the information that the BFR is increased in the Coronal and Middle (1-3mm) regions would argue for a reparative function of remodeling in the Coronal and outer Middle regions, which is in response to microdamage accumulation. Significant differences were observed in the Middle (1mm) and Middle (Combined) regions, with the alendronate group demonstrating an increased CrSDn relative to control. There was no statistical difference across treatment groups for any of the regions studied. When compared by regions, the Coronal (1mm) was statistically higher than all regions it was measured against. The Middle regions demonstrated elevated CrSDn relative to the apical region, which displayed the lowest CrSDn values of all regions. One final measure of microdamage is mean crack length. There were no statistically significant differences across any groups for any regions. The only significant differences, when observed across regions, was in reference to the Middle (1mm) region, which was significantly larger than the Coronal (1mm), Coronal (Combined), and the Middle (1-3mm) region. Otherwise, there is no observable trend, and no significant difference between regions. In conclusion, this study found that there was no an increase in microdamage in the dentate mandible of the dogs with bisphosphonate therapy, thereby rejecting the first hypothesis. While there were isolated regions of remodeling inhibition, the hypothesis that bisphosphonate therapy would inhibit remodeling more in the coronal region than in the middle and apical region is rejected. Therefore, based on the findings of this study, we conclude that bisphosphonates do inhibit remodeling in the dentate alveolus generally, but inhibition is not localized to any particular region. Finally, the administration of bisphosphonates do not result in an increase in microdamage accumulation in the dentate alveolus of dogs.

Indiana University-Purdue University Indianapolis (IUPUI) / According to one theory of root resorption, occlusal trauma during orthodontic tooth movement damages the cementum covering the root dentin. The body detects the exposed dentin and seeks to remove it, and the result is root resorption. This experiment will explore an aspect of this theory by quantifying the amount and location of damage in mechanically fatigued teeth. Nine dog mandibles were sectioned at the mandibular symphysis. Each half was mounted in orthodontic resin with the incisors upright and exposed. The block was inserted into a jig and placed into a servohydraulic mechanical testing machine. The left central incisor was fatigue loaded with a 2Hz, 10-90 N sinusoidal force for 100,000 cycles (approximately 14 hours). The right central incisor served as the control. Both specimens were scanned with a micro-CT unit, stained with basic fuchsin, and then sectioned along the sagittal plane. Because the experimental and control specimens were stained before sectioning, only microdamage due to the loading process would be evident in the sections. Microdamage which occurred during the sectioning process would not be stained. Central sections through the long axes of the samples were examined for the presence of microdamage with a light microscope and a micro-CT unit. Based on preliminary findings, two types of staining patterns were measured and recorded. The first was called "diffuse stain" and consisted of large stained areas in the dentinal tubules. Diffuse stain was not associated with any visible features at the dentinocemental junction. The second type of staining pattern was called "stained defects." Stained defects were stained irregularities at the dentinocemental junction. For statistical analysis, the roots were divided into buccal-cervical, buccal-middle, buccal-apical, lingual-cervical, lingual-middle, and lingual-apical regions. Comparisons between the fatigued and non-fatigued teeth for differences in area, length, and depth were made under the generalized estimating equation (GEE) framework applied to normally-distributed data. Because the measurements were not normally distributed, a rank transformation of the measurements was performed before conducting the analyses. Comparisons between the fatigued and non-fatigued teeth for differences in presence or absence of stain or defects were made using Cochran-Mantel-Haenszel tests. Repeatability of the measurements was assessed using intraclass correlation coefficients (ICCs), paired t-tests, and Bland-Altman plots. The ICC's ranged from 0 .85 to 1.00, thus making the repeatability of the measurements generally very good. The statistical analysis showed there were no significant differences between the experimental and control teeth for stained defects or diffuse staining for length, depth, or area measurements. However, analyses comparing the distribution of stained defects and diffuse stain within the control and experimental specimens showed significant differences in the distribution of stained defects within the experimental specimens. In the experimental specimens, the stained defects were distributed in a gradient, with the most in the apical region and progressing to the least amount in the cervical region. In the control specimens, there was only a difference in the stained defects between the cervical and apical regions. This distribution is consistent with the biomechanical model which shows increasing stress moving from the cervical region towards the apex. These results show that the test and control specimens differed in how the stained defects were distributed throughout the root, even though there were no differences in the amount of staining between the control and experimental specimens. Whole tooth and histologic slides were scanned with the micro-CT unit, but the dentinocemental junction could not be delineated enough to make any measurements. No data could be collected regarding microdamage in this area using the micro-CT unit. It was recommended that future studies use a tomography unit with better resolution, use a larger samples size, employ a contrast agent when trying to visualize microdamage with the micro-CT unit, and incorporate a way to measure the intensity of the staining in addition to the location and size.

In the tuberculosis patients, Mycobacterium tuberculosis can stimulate production of hydrogen peroxide in the host as a result of immune response. The H2O2 accumulate in pulmonary cells, causing oxidative stress that could lead to the cancer. We select TB patients for this study which investigates the effects of quercetin as there is an increased incidence of latent TB among the migrant population in the past few years and TB can increase the risk of cancer. Sperm and lymphocytes were treated with DNA damage inducers and quercetin (10µM, 25µM and 100µM), the responses evaluated using the Comet and micronucleus techniques. The gene expressions of COX1, COX2, P53 and Bcl-2 and catalase protein expression were investigated using the qPCR and Western blot techniques. The results showed that a substantial reduction of DNA damage in lymphocytes from TB patients and sperm from healthy donors from * P ≤ 0.0283 to *** P≤0.001in the Comet assay. In the MNi assay, the effect of quercetin in lymphocytes was more significant in reduce DNA damage, whereas the DNA damage induced by a food mutagen was significant, from *p 0.0405 to ***p 0.001. The qPCR showed significance down-regulation of COX1 and Bcl-2 gene expression, rated between *p 0.045 and **p 0.0074. However, the catalase protein was up-regulated by the nano form of quercetin when using lymphocytes from TB patients and showed significant changes at *p 0.0236. In conclusion, the nano form was found to be more efficient at the reduction of DNA damage in the Comet and micronucleus assays. Also, it down-regulated COX1 and Bcl-2 and up-regulated the catalase proteins indicating a possible role for quercetin, in genoprotection to TB through its enzyme modulating effect. / Libyan Embassy

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