The Influence of PRP on Early Bone Formation in Membrane Protected Defects. A Histological and Histomorphometric Study in the Rabbit Calvaria

Platelet rich plasma (PRP) has been proposed to be a useful adjunct to bone grafting.

Early loading after 21 days of healing of nonsubmerged titanium implants with a chemically modified sandblasted and acid-etched surface: two-year results of a prospective two-center study

PURPOSE: The aim of this two-center study was to evaluate screw-type titanium implants with a chemically modified, sandblasted and acid-etched surface when placed in the posterior maxilla or mandible, and loaded 21 days after placement. MATERIAL AND METHODS: All 56 patients met strict inclusion criteria and provided informed consent. Each patient displayed either a single-tooth gap, an extended edentulous space, or a distal extension situation in the posterior mandible or maxilla. Eighty-nine dental implants (SLActive, Institut Straumann AG, Basel, Switzerland) were inserted according to an established nonsubmerged protocol and underwent undisturbed healing for a period of 21 days. Where appropriate, the implants were loaded after 21 days of healing with provisional restorations in full occlusion. Definitive metal ceramic restorations were fabricated and positioned on each implant after 6 months of healing. Clinical measurements regarding soft tissue parameters and radiographs were obtained at different time points up to 24 months after implant placement. RESULTS: Of the 89 inserted implants, two (2.2%) implants failed to integrate and were removed during healing, and two (2.2%) additional implants required a prolonged healing time. A total of 85 (95.6%) implants were therefore loaded without incident after 21 days of healing. No additional implant was lost throughout the study period, whereas one implant was lost to follow-up and therefore left unaccounted for further analysis. The remaining 86 implants all exhibited favorable radiographic and clinical findings. Based on strict success criteria, these implants were considered successfully integrated 2 years after insertion, resulting in a 2-year success rate of 97.7%. CONCLUSION: The results of this prospective two-center study demonstrate that titanium implants with a modified SLA surface can predictably achieve successful tissue integration when loaded in full occlusion 21 days after placement. Integration could be maintained without incident for at least 2 years of follow-up.

Effect of systemic tetracycline on the degradation of tetracycline-impregnated bilayered collagen membranes: an animal study

BACKGROUND: Premature collagen membrane degradation may compromise the outcome of osseous regenerative procedures. Tetracyclines (TTCs) inhibit the catalytic activities of human metalloproteinases. Preprocedural immersion of collagen membranes in TTC and systemic administration of TTC may be possible alternatives to reduce the biodegradation of native collagen membranes. AIM: To evaluate the in vivo degradation of collagen membranes treated by combined TTC immersion and systemic administration. MATERIALS AND METHODS: Seventy-eight bilayered porcine collagen membrane disks were divided into three groups and were immersed in 0, 50, or 100 mg/mL TTC solution. Three disks, one of each of the three groups, were implanted on the calvaria of each of 26 Wistar rats. Thirteen (study group) were administered with systemic TTC (10 mg/kg), while the remaining 13 received saline injections (control group). Calvarial tissues were retrieved after 3 weeks, and histological sections were analyzed by image analysis software. RESULTS: Percentage of remaining collagen area within nonimpregnated membranes was 52.26 ± 20.67% in the study group, and 32.74 ± 13.81% in the control group. Immersion of membranes in 100 mg/mL TTC increased the amount of residual collagen to 63.46 ± 18.19% and 42.82 ± 12.99% (study and control groups, respectively). Immersion in 50 mg/mL TTC yielded maximal residual collagen values: 80.75 ± 14.86% and 59.15 ± 8.01% (study and control groups, respectively). Differences between the TTC concentrations, and between the control and the study groups were statistically significant. CONCLUSIONS: Immersion of collagen membranes in TTC solution prior to their implantation and systemic administration of TTC significantly decreased the membranes' degradation.

Tripyrrolidinophosphoric acid triamide as an activator in samarium diiodide reductions

The electrochemical and spectrophotometric characterization of the complex formed from samarium diiodide and 4 equiv of tripyrrolidinophosphoric acid triamide (TPPA) is presented. Kinetic studies indicate that the SmI(2)/TPPA complex possesses reactivity greater than the complex formed between samarium diiodide and 4 equiv of HMPA. Examples of the use of SmI(2)/TPPA in synthesis are presented.

The relationship between self-efficacy and resting blood pressure in spousal Alzheimer's caregivers

Objective. To examine whether high levels of self-efficacy for problem-focused coping were significantly related to several resting BP measures in spousal Alzheimer's disease caregivers. Design. Cross-sectional. Methods. Participants included 100 older caregivers (mean age = 73.8 ± 8.14 years) providing in home care for a spouse with Alzheimer's disease. All participants completed a 13-item short form of the Coping Self-Efficacy Scale and underwent an in-home assessment where a visiting nurse took the average of three serial BP readings. Multiple regression was used to examine the relationship between self-efficacy and mean arterial pressure (MAP), systolic BP (SBP), diastolic BP (DBP), and pulse pressure (PP) after controlling for age, gender, smoking history, body mass index, the care recipient's clinical dementia rating, diabetes, alcohol use, and the use of antihypertensive medications. Results. Overall, high levels of self-efficacy for problem-focused coping were associated with lower MAP, SBP, and PP. Self-efficacy for problem-focused coping was marginally associated with resting DBP, but not significant. In addition, we conducted secondary analyses of the other two self-efficacy scales to explore the relationship between each dimension and MAP. We found that there were no significant relationships found between MAP and self-efficacy for stopping unpleasant thoughts/emotions or self-efficacy for getting social support. Conclusions. The present study adds to the current body of literature by illustrating the possibility that higher self-efficacy can have physiological advantages, perhaps by buffering chronic stress's impact on resting BP. Another contribution of the current study is its attempt to understand the role of each individual component of self-efficacy. These findings invite future research to investigate whether caregivers might experience cardiovascular benefits from interventions aimed at enhancing self-efficacy.

Analysis of new bone formation induced by periosteal distraction in a rat calvarium model

Background: A controlled, gradual distraction of the periosteum is expected to result in the formation of new bone. Purpose: This study was designed to estimate the possibility of new bone formation by periosteal distraction in a rat calvarium model. Material and Methods: Sixteen animals were subjected to a 7-day latency period and distraction rate at 0.4 mm/24 hours for 10 days. Two experimental groups with seven rats each were killed at 10 and 20 days of consolidation period and analyzed by means of microcomputed tomography, histologically and histomorphometry. Results: In the central regions underneath the disk device, signs of both bone apposition and bone resorption were observed. Peripheral to the disc, new bone was consistently observed. This new bone was up to two and three times thicker than the original bone after a 10- and 20-day consolidation period, respectively. Signs of ongoing woven bone formation indicated that the stimulus for new bone formation was still present. There were no statistically significant differences regarding bone density, bone volume, and total bone height between the two groups. Conclusion: The periosteal distraction model in the rat calvarium can stimulate the formation of considerable amounts of new bone.

Synthesis of (-)-dactylolide and 13-desmethylene-(-)-dactylolide and their effects on tubulin

An efficient new synthesis has been elaborated for non-natural (-)-dactylolide ((-)-2) and its 13-desmethylene analogue 4, employing a HWE-based macrocyclization approach with beta-keto-phosphonate/aldehyde 19 and the respective 13-desmethylene derivative as the key intermediates. Both (-)-2 and 4 as well as the corresponding C20 alcohols inhibit human cancer cell proliferation with IC(50) values in the sub-micromolar range and induce the polymerization of tubulin in vitro.

Stereoselective synthesis of a monocyclic peloruside a analogue

The stereoselective synthesis of the monocyclic peloruside A analogue 4 has been achieved, following a new efficient approach for the introduction of the side chain, involving a late-stage addition of vinyl lithium species 7a to aldehyde 8. Further key steps are a highly diastereoselective allyltitanation reaction and a RCM-based macrocyclization.

Musical Training Induces Functional Plasticity in Human Hippocampus

Training can change the functional and structural organization of the brain, and animal models demonstrate that the hippocampus formation is particularly susceptible to training-related neuroplasticity. In humans, however, direct evidence for functional plasticity of the adult hippocampus induced by training is still missing. Here, we used musicians' brains as a model to test for plastic capabilities of the adult human hippocampus. By using functional magnetic resonance imaging optimized for the investigation of auditory processing, we examined brain responses induced by temporal novelty in otherwise isochronous sound patterns in musicians and musical laypersons, since the hippocampus has been suggested previously to be crucially involved in various forms of novelty detection. In the first cross-sectional experiment, we identified enhanced neural responses to temporal novelty in the anterior left hippocampus of professional musicians, pointing to expertise-related differences in hippocampal processing. In the second experiment, we evaluated neural responses to acoustic temporal novelty in a longitudinal approach to disentangle training-related changes from predispositional factors. For this purpose, we examined an independent sample of music academy students before and after two semesters of intensive aural skills training. After this training period, hippocampal responses to temporal novelty in sounds were enhanced in musical students, and statistical interaction analysis of brain activity changes over time suggests training rather than predisposition effects. Thus, our results provide direct evidence for functional changes of the adult hippocampus in humans related to musical training.

Stimulus predictability reduces responses in primary visual cortex

In this functional magnetic resonance imaging study we tested whether the predictability of stimuli affects responses in primary visual cortex (V1). The results of this study indicate that visual stimuli evoke smaller responses in V1 when their onset or motion direction can be predicted from the dynamics of surrounding illusory motion. We conclude from this finding that the human brain anticipates forthcoming sensory input that allows predictable visual stimuli to be processed with less neural activation at early stages of cortical processing.

Neuroelectromagnetic correlates of perceptual closure processes

Perceptual closure refers to the coherent perception of an object under circumstances when the visual information is incomplete. Although the perceptual closure index observed in electroencephalography reflects that an object has been recognized, the full spatiotemporal dynamics of cortical source activity underlying perceptual closure processing remain unknown so far. To address this question, we recorded magnetoencephalographic activity in 15 subjects (11 females) during a visual closure task and performed beamforming over a sequence of successive short time windows to localize high-frequency gamma-band activity (60–100 Hz). Two-tone images of human faces (Mooney faces) were used to examine perceptual closure. Event-related fields exhibited a magnetic closure index between 250 and 325 ms. Time-frequency analyses revealed sustained high-frequency gamma-band activity associated with the processing of Mooney stimuli; closure-related gamma-band activity was observed between 200 and 300 ms over occipitotemporal channels. Time-resolved source reconstruction revealed an early (0–200 ms) coactivation of caudal inferior temporal gyrus (cITG) and regions in posterior parietal cortex (PPC). At the time of perceptual closure (200–400 ms), the activation in cITG extended to the fusiform gyrus, if a face was perceived. Our data provide the first electrophysiological evidence that perceptual closure for Mooney faces starts with an interaction between areas related to processing of three-dimensional structure from shading cues (cITG) and areas associated with the activation of long-term memory templates (PPC). Later, at the moment of perceptual closure, inferior temporal cortex areas specialized for the perceived object are activated, i.e., the fusiform gyrus related to face processing for Mooney stimuli.

Prosthetic Rehabilitation, Implant Survival and Quality of Life 2 to 5 Years after Resection of Oral Tumors

Background: After oral tumor resection, structural and functional rehabilitation by means of dental prostheses is complex, and positive treatment outcome is not always predictable. Purpose: The objective of the study was to report on oral rehabilitation and quality of life 2-5 years after resection of malignant oral tumors. Materials and Methods: Data of 46 patients (57 ± 7 years) who underwent oral tumor surgery were available. More than 50% of tumors were classified T3 or T4. Open oro-nasal defects resulted in 12 patients and full mandibulary block resections in 23 patients. Comprehensive planning, implant placement, and prosthetic rehabilitation followed an interdisciplinary protocol. Analysis comprised tumor location, type of prostheses, implant survival, and quality of life. Results: Because of advanced tumor status, resections resulted in marked alteration of the oral anatomy requiring complex treatment procedures. Prosthetic rehabilitation comprised fixed and removable prostheses, with 104 implants placed in 28 patients (60%). Early implant loss was high (13%) and cumulative survival rate of loaded implants was <90% after 5 years. Prosthetic plans had to be modified because of side effects of tumor therapy, complications with implants and tumor recurrence. The majority of patients rated quality of life favorable, but some experienced impaired swallowing, dry mouth, limited mouth opening, appearance, and soreness. Conclusions: Some local effects of tumor therapy could not be significantly improved by prosthetic rehabilitation leading to functional and emotional disability. Many patients had passed away or felt too ill to fill the questionnaires. This case series confirms the complex anatomic alterations after tumor resection and the need for individual treatment approaches especially regarding prosthesis design. In spite of disease-related local and general restrictions, most patients gave a positive assessment of quality of life.