Relationship between body mass index and local quality of mandibular bone structure in elderly individuals

BACKGROUND: Human bones decrease in density and increase in porosity beginning at about the third decade of life. The objective of this study was to determine whether mandibular bone mineral density (BMD) and some linear radiomorphometric measurements on dental panoramic radiograph (DPR) are correlated with different categories of body mass index (BMI) in elderly individuals. METHODS: Cortical width at gonion (GI), at antegonion (AI), and below mental foramen (MI) and the appearance of the cortex of the lower border of the mandible distal to the mental foramina due to resorptive changes (mandibular cortical index [MCI]) were measured bilaterally on the mandible on 136 DPRs of elderly individuals. Using DPRs and copper stepwedge, mandibular BMD was investigated densitometrically. All BMD values were expressed in equivalents of the actual stepwedge thickness. The patients with BMIs from 20 to 25 kg/m(2) were classified as category 1 (the generally accepted range of normal BMI), and the patients with BMIs higher than 25 were classified as category 2 (heavy individuals with a heavy skeleton and a large amount of fat in the body). RESULTS: The results revealed statistically significant differences in all measured indices between different BMI categories (p <.05 for MI; p <.001 for GI and AI). Statistically significant differences were also found in BMD values between different BMI categories (p <.05); the differences were more pronounced in women. The patients with MCI category 3 had significantly lower BMD values in comparison to MCI category 2 (p <.01). Intraobserver agreement in GI, AI, MI measurement, and MCI assessments was excellent. CONCLUSIONS: Heavy people have higher BMD and higher values in linear radiomorphometric measurements than lighter people.     

Configuration optimization and experimental accuracy evaluation of a bone-attached,parallel robot for skull surgery

Purpose

Minimally invasive cochlear implantation is a novel surgical technique which requires highly accurate guidance of a drilling tool along a trajectory from the mastoid surface toward the basal turn of the cochlea. The authors propose a passive, reconfigurable, parallel robot which can be directly attached to bone anchors implanted in a patient’s skull, avoiding the need for surgical tracking systems. Prior to clinical trials, methods are necessary to patient specifically optimize the configuration of the mechanism with respect to accuracy and stability. Furthermore, the achievable accuracy has to be determined experimentally.

Methods

A comprehensive error model of the proposed mechanism is established, taking into account all relevant error sources identified in previous studies. Two optimization criteria to exploit the given task redundancy and reconfigurability of the passive robot are derived from the model. The achievable accuracy of the optimized robot configurations is first estimated with the help of a Monte Carlo simulation approach and finally evaluated in drilling experiments using synthetic temporal bone specimen.

Results

Experimental results demonstrate that the bone-attached mechanism exhibits a mean targeting accuracy of \((0.36\pm 0.12)\) mm under realistic conditions. A systematic targeting error is observed, which indicates that accurate identification of the passive robot’s kinematic parameters could further reduce deviations from planned drill trajectories.

Conclusion

The accuracy of the proposed mechanism demonstrates its suitability for minimally invasive cochlear implantation. Future work will focus on further evaluation experiments on temporal bone specimen.

     

The role of CNI-1493 in the function of primary microglia with respect to amyloid-β

Amyloid-β (Aβ) oligomer toxicity is a crucial factor in the development of Alzheimer's disease. Therefore, the aim of therapeutic research is to target the modification of secretase activity, increase Aβ degradation, reduce Aβ formation, and modulate Aβ-induced neuroinflammation. Recently, the p38 MAP kinase inhibitor CNI-1493 has been shown to reduce plaque load and has led to an improvement in memory performance in a transgenic mouse model. We examined the role of CNI-1493 in the microglial inflammatory response to Aβ using both a microglia cell line as well as primary microglia isolated from mesocortices. MTT assays were performed to quantify cell viability. FACS analysis was used to measure phagocytosis. We used ELISA to analyse cytokine concentrations in response to CNI-1493 treatment. Western-blot/Dot-blot techniques were used to show the interaction of CNI-1493 with Aβ-oligomers as well as to measure apoptosis in microglia cells. RT-PCR was used to analyze secretase expression, and secretase function was determined using fluorimetric assays. CNI-1493 is able to prevent oligomer formation as well as apoptosis in microglia. A significant reduction was found in the Aβ-induced release of IL-6 and TNF-α in the presence of CNI-1493. Phagocytosis is an essential Aβ removal mechanism and was enhanced by CNI-1493 in primary microglia. CNI-1493 also influenced the α-secretase product C83 with an increase in the treated cells, while a simultaneous reduction in Aβ secretion was also observed. We hypothesize that CNI-1493 not only reduces neuroinflammation and consequent neurodegeneration, but also leads to a shift in AβPP-processing towards the non-amyloidogenic pathway. Therefore, CNI-1493 is a promising candidate for the treatment of AD.     

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa

OBJECTIVES: Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice. STUDY DESIGN: The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture. METHODS: Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically. RESULTS: Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm). CONCLUSIONS: This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.