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Browsing by Author "Christen, Arden G."
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Item Effects of nicotine on osteogenesis(2001) Sanoudos, Mattheos; Roberts, W. Eugene; Christen, Arden G.; Garetto, Lawrence P.; Hartsfield, James K.; Olson, Byron L.The purpose of this study was to demonstrate the inhibiting effects of systemically administered nicotine on osteogenesis and angiogenesis. The orthopedic expansion of a suture is a non-invasive method directly related to orthodontic treatment. This study examined the actions of nicotine related to the vascularly related osteogenic response elicited by orthopedic expansion. Sixty seven male,6-8 week old, Sprague-Dawley received 2 different dosages of nicotine (6 and 12 mg/kg/day), for a period of 14 days. Nicotine was delivered subcutaneously with the use of Alzet® Osmotic minipumps. Control animals received minipumps filled with saline. Fluorochrome labels were administered during the two-week period to mark bone formation. Ten days after minipump implantation a second surgery was performed and ring-type elastic separators were placed between the maxillary central incisors of forty-six animals. Twenty-three and ninety-five hours after expansion the animals were injected BrdU and terminated 1 hour later. The maxillae were demineralized and embedded in paraffin. The femurs and tibias were cleaned from soft tissue and embedded in methyl methacrylate. The results of this study indicate that nicotine has a dose-dependent inhibiting effect on both the osteogenic and angiogenic process in the expanded suture. After 96 hours of expansion these effects are only partially reversed. Nicotine inhibits vascular invasion and depresses osteoblast recruitment. The study indicated that there may also be a direct suppression of osteoblasts, but the principal anti-osteogenic effect of nicotine is an inhibition of the vascular proliferation and osteoblast histogenesis, associated with mechanically induced osteogenesisItem Gender Differences: Smokers With and Without Substance Abuse History(Office of the Vice Chancellor for Research, 2013-04-05) Bennett, Sonia M.; Romito, Laura M.; Christen, Arden G.Previous research suggests that individuals with chemical dependence history experience more intense nicotine addiction, and during smoking cessation may be more likely to demonstrate increased negative affect and unfavorable scores on psychometric assessments. It is unknown how men and women may differ in their susceptibilities to such undesirable outcomes. From 1992-2004, The Indiana University Nicotine Dependence Program (IUNDP) treated over 1200 patients using a Mayo Clinic-based protocol which assesses the behavioral, social, and physiological aspects of nicotine dependence. The IUNDP was instituted at Fairbanks Hospital’s addictions center to address tobacco use among the patients and staff. Charts of individuals who completed nicotine dependence treatment (1992-2011) were selected from IU School of Dentistry and Fairbanks Hospital for retrospective analysis. Chart selection criteria consisted of the availability of complete pre-and post quit measures for a minimum of four total appointments and two post-quit appointments. Reviewed were 107 charts from patients without a history of chemical dependence (ND) and 123 from those with a chemical dependence history (CD), including 120 men and 110 women. Student researchers used a standardized protocol to capture 16 tobacco use and demographic variables and 12 post-quit measures. Comparisons between CD and ND groups were made using Pearson chi-square tests for binary data, Wilcoxon rank sum tests for all other data, and Wilcoxon signed rank tests for changes between time periods. Despite similarities among CD and ND smokers, males and females appear to face distinct challenges. Results suggest CD males are significantly more negative in mood, and are more likely to have increased withdrawal symptoms at the end of treatment. Males were also more likely to experience adverse events with NRT. Both CD males and females experienced more increased appetite than their ND counterparts. Females scored higher on addiction-related sensorimotor manipulation and may have increased propensity for psychological dependence.Item Longitudinal Determination of Mutans Streptococci Strain Differences by Pulsed Field Gel Electorphoresis in Orthodontic Patients(1997) Jordan, Christopher N.; LeBlanc, Donald J.; Christen, Arden G.; Hartsfield, James K., Jr.; Miller, Chris H.; Olson, Byron L.Results of numerous studies have positively correlated the Dentocult® SM test(Ivoclar Vivadent, Amherst, New York) with conventional plating techniques for the enumeration of mutans streptococci in saliva. However, similar studies have not been conducted on saliva samples collected from patients undergoing orthodontic therapy. The hypotheses to be tested in this study were therefore threefold: first, that the Dentocult system is an accurate and reliable method for the determination of salivary counts of mutans streptococci when used with orthodontic patients; second, that a trend (either a general increase or decrease) in levels of mutans streptococci would be seen in orthodontic patients; and third, that because a new surface is presented due to orthodontic appliances, different strains of mutans streptococci, possibly exogenously acquired, might account for increased levels of mutans streptococci, should an increase be seen. Therefore, isolates of these bacteria obtained before and after therapy were examined by Pulsed Field Gel Electrophoresis (PFGE) for detection of strain differences. Two baseline saliva samples, and a saliva, tooth plaque, and appliance plaque sample at 1,2,3, and 4 months after commencement of full orthodontic banding and bonding were obtained from 26 patients in the Indiana University School of Dentistry graduate orthodontic clinic for bacterial enumeration and PFGE analyses. Dentocult was found to correlate extremely well with conventional plating techniques, utilizing Mitis salivarius agar supplemented with bacitracin (MSB), when salivary levels of mutans streptococci were either extremely high(> 10 6 CFU/ml saliva) (91 % correlation) or quite low ( <10 5 CFU/ml saliva) ( 100% correlation). For salivary levels of mutans streptococci between these limits, the percent agreement was not as substantial (49% correlation). Salivary levels >10 6 CFU/ml saliva of mutans streptococci was used as an indicator of caries risk. An increase in the numbers of patients at risk for the development of dental caries was seen at the 2 month sample collection point. Thereafter, the number of patients at risk decreased, so that at completion of the study, the number of patients at risk for caries development was down to near that observed prior to treatment. Fermentation reactions and PFGE analyses were completed for all baseline saliva samples, and all 4 month saliva, tooth plaque, and appliance plaque samples. Fermentative data indicated that 86/102 (84%) of the samples obtained were Streptococcus mutans, and that there were no Streptococcus sobrinus isolates present. The remaining isolates 14/102 (16%) were not characterized further, and were assumed to be viridans streptococci. Results of PFGE indicated that the same, or no more than two different strains of S. mutans predominated in the saliva and plaque of most of the patients examined.Item Microhardness, Strains and Microdamage in Bone Surrounding Endosseous Implants Subjected to Bending Fatigue Loads(1999-05) Huja, Sarandeep Singh; Roberts, W. Eugene; Burr, David B.; Christen, Arden G.; Katona, Thomas R.; Garetto, Lawrence P.; McDonald, James L., Jr.Intense remodeling occurs in lamellar bone adjacent to osseointegrated endosseous implants. The purpose of this study was to compare microdamage accumulation subsequent to fatigue loading of bone that surrounds an endosseous implant at (a) immediate placement (non-adapted bone) and (b) following a 12 week period of healing (adapted bone). It was hypothesized that there would be less microdamage in the compliant adapted bone than in the older non-adapted bone adjacent to endosseous implants after being subjected to a fatigue protocol. Preliminary studies to measure the microhardness of bone surrounding implants and three dimensional finite element models to quantify the strain environment were required. In addition, a new fluorescent method to quantify microdamage was developed. Titanium endosseous implants (4 mm diameter) were placed into dog mid-femoral diaphyses and allowed to heal for 12 weeks. Block sections of bone, each containing one implant, were cut antero-posteriorly to obtain an implant containing lateral cortex. The medial cortex was used to produce non-adapted specimens by placing a 4 mm diameter titanium rod. Specimens were divided into two groups. Control (n=14 each for adapted and non-adapted, 0 N) and experimental specimens (n=13 adapted and n=14 non-adapted) were loaded in bending for 150,000 cycles at 2 Hz. Specimens were bulk stained with basic fuschin. Histomorphometric methods were used to evaluate crack numerical density, crack surface density and percent damaged area. Microdamage in the non-adapted and adapted specimens was compared using repeated measures ANOVA and Tukey's method at a 95% confidence level. Statistically significant differences (p<0.0001) existed for all measurements between the non-adapted and adapted specimens on the compressive cortices with adapted bone accumulating less microdamage than non-adapted bone. This study suggests that the more compliant adapted bone adjacent to the endosseous implant is relatively resistant to the imposed fatigue loads. The rapidly turning over bone may prevent microdamage accumulation and propagation, thus allowing for the successful adaptation of these implants.Item Puffing Topography and Interpersonal Bonding Behavior Observed Among Recovering Drug Addicts Versus General Smokers(Office of the Vice Chancellor for Research, 2013-04-05) Kunkel, Patrick O.; Hoffman, Rachel A.; Romito, Laura M.; Christen, Arden G.Smokers can inherently manipulate nicotine doses on a puff-by-puff basis. The character of smoking behavior may be determined by using complex forms of smoking topography in laboratory settings or by unobtrusively observing the time spent smoking a single cigarette, the number of puffs taken, interpuff intervals and smokers’ behaviors. The purpose of this study was to observe and compare smoking topography and interpersonal bonding behaviors of recovering drug addicts to that of general smokers in a natural setting (introduction). Following a variable chemical substance detox/treatment period, Fairbanks addiction treatment patients spend 3-12 weeks in follow-up treatment in two groups: Partial Hospitalized Patients (PHP) and Intensive Outpatients (IOP). PHP and IOP form tight interpersonal bonds and friendships with each other. Patients are periodically released and they meet and smoke together at an approved outdoor smoking area. From a distance, PHP and IOP (20 men and 20 women) cigarette puffing behaviors were unobtrusively observed and recorded. Two calibrated investigators, using a stop watch monitored the exact time of lighting and the extinguishing of each cigarette. For each subject, the number of puffs taken was recorded and the interpuff interval was calculated. The same protocol was followed for a population of general smokers observed on the campus of IUPUI (methods). The mean interpuff intervals were IUPUI men: 25.2 seconds (SD 11.93); IUPUI women: 30.9 seconds (SD 16.0); Fairbanks men: 16.2 seconds (SD 6.21); and Fairbanks women: 21.1 seconds (SD 6.51). There was a statistically significant difference in interpuff intervals between the general smokers and the recovering addicts (p<0.001) and this effect was not dependent upon gender. Behavioral observations between general smokers versus recovering addicts will be presented (results). Smokers who were recovering from chemical drug addiction smoked more intensely than the general smoking population and their smoking behaviors were often quite different (conclusions).Item Relationship of Wound Healing and Angiogenesis to the Cell Kinetics of the Initial Osteogenic Response in Orthopedically Expanded Anterior Maxillary Suture in the Rat(1994-07) Chang, Hwai-nan; Roberts, W. Eugene; Chen, Jie; Christen, Arden G.; Garetto, Lawrence P.; Katona, Thomas R.; Lee, Chao-Hung; McDonald, JamesFollowing sutural expansion, wound healing and angiogenesis precede bone formation. The purpose of this study was to examine angiogenic and subsequent osteogenic responses during a 96 hour time-course following sutural expansion. Fifty rats were divided into: (1) control group that received only angiogenic induction via injection of 5 ng/gm recombinant human endothelial cell growth factor (rhECGF); (2) experimental group that received orthopedic expansion and rhECGF; (3) sham group that received expansion and NaCl injection; and (4) baseline group that received no expansion or injection. Both experimental and sham groups were subdivided further to conduct experiments of 1, 2, 3, and 4 days. All rats were injected with 3H-thymidine (1.0 μCi/gm) 1 hour before euthanasia to label DNA of S-phase cells. The premaxilla was dissected free and demineralized. Sections (4 μm thick) were stained with hematoxylin and eosin. Angiogenesis and cell migration were analyzed using a previously established cell kinetics model. The cells were divided into four categories according to nuclear volume: A cells (40-79 μm3), B cells (80-119 μm3), C cells (120-169 μm 3), and D cells (~169 μm3). ANOVA was used to test the hypothesis that enhancement of angiogenesis stimulates reestablishment of osteogenic capability. Blood vessel number, area and endothelial cell labeled index significantly increased in experimental groups, but no difference was found between control and baseline groups (i.e., rhECGF treatment alone). Labeled-pericyte index and activated pericyte's numbers in the experimental group were also higher than in the sham groups. Compared to sham groups, A+A' cell numbers were significantly higher during the first two days in the experimental groups, followed by a rapid decrease at days three and four; C+D cell number peaked at day three. These results demonstrate that supplemental rhECGF enhances angiogenesis in expanded suture but not in nonexpanded suture. Data also suggest that pericytes may serve as a bridge between angiogenesis and osteogenesis.