The effects of different pilot-drilling methods on the mechanical stability of a mini-implant system at placement and removal: a preliminary study

Objective: To investigate the effects of different pilot-drilling methods on the biomechanical stability of self-tapping mini-implant systems at the time of placement in and removal from artificial bone blocks. Methods: Two types of artificial bone blocks (2-mm and 4-mm, 102-pounds per cubic foot [102-PCF] polyurethane foam layered over 100-mm, 40-PCF polyurethane foam) were custom-fabricated. Eight mini-implants were placed using the conventional motor-driven pilot-drilling method and another 8 mini-implants were placed using a novel manual pilot-drilling method (using a manual drill) within each of the 2-mm and 4-mm layered blocks. The maximum torque values at insertion and removal of the mini-implants were measured, and the total energy was calculated. The data were statistically analyzed using linear regression analysis. Results: The maximum insertion torque was similar regardless of block thickness or pilot-drilling method. Regardless of the pilot-drilling method, the maximum removal torque for the 4-mm block was statistically higher than that for the 2-mm block. For a given block, the total energy at both insertion and removal of the mini-implant for the manual pilot-drilling method were statistically higher than those for the motor-driven pilot-drilling method. Further, the total energies at removal for the 2-mm block was higher than that for the 4-mm block, but the energies at insertion were not influenced by the type of bone blocks. Conclusions: During the insertion and removal of mini-implants in artificial bone blocks, the effect of the manual pilot-drilling method on energy usage was similar to that of the conventional, motor-driven pilot-drilling method. (Korean J Orthod 2011;41(5):354-360)Supported by a grant from Kyung Hee University in 2010 (KHU-20100696).

Titanium dioxide nanoparticles oral exposure to pregnant rats and its distribution

Background: Titanium dioxide (TiO2) nanoparticles are among the most manufactured nanomaterials in the industry, and are used in food products, toothpastes, cosmetics and paints. Pregnant women as well as their conceptuses may be exposed to TiO2 nanoparticles; however, the potential effects of these nanoparticles during pregnancy are controversial, and their internal distribution has not been investigated. Therefore, in this study, we investigated the potential effects of oral exposure to TiO2 nanoparticles and their distribution during pregnancy. TiO2 nanoparticles were orally administered to pregnant Sprague-Dawley rats (12 females per group) from gestation days (GDs) 6 to 19 at dosage levels of 0, 100, 300 and 1000 mg/kg/day, and then cesarean sections were conducted on GD 20. Results: In the maternal and embryo-fetal examinations, there were no marked toxicities in terms of general clinical signs, body weight, food consumption, organ weights, macroscopic findings, cesarean section parameters and fetal morphological examinations. In the distribution analysis, titanium contents were increased in the maternal liver, maternal brain and placenta after exposure to high doses of TiO2 nanoparticles. Conclusion: Oral exposure to TiO2 during pregnancy increased the titanium concentrations in the maternal liver, maternal brain and placenta, but these levels did not induce marked toxicities in maternal animals or affect embryo-fetal development. These results could be used to evaluate the human risk assessment of TiO2 nanoparticle oral exposure during pregnancy, and additional comprehensive toxicity studies are deemed necessary considering the possibility of complex exposure scenarios and the various sizes of TiO2 nanoparticles

Prospective Analysis on the Relation between Pain and Prostate Volume during Transrectal Prostate Biopsy

OBJECTIVE: We wanted to assess the relationship between pain and the prostate volume during transrectal ultrasound (TRUS) guided biopsy. MATERIALS AND METHODS: Between July and September 2006, 71 patients scheduled for TRUS biopsy of the prostate were considered for inclusion to this study. These patients underwent periprostatic neurovascular bundle block with lidocaine prior to biopsy. Pain was assessed using a Visual Analogue Scale (VAS) during periprostatic neurovascular bundle block (VAS 1), during biopsy (VAS 2), and 20 minutes after biopsy (VAS 3). The mean pain scores were analyzed in the large prostate group (prostate volume > 40 cc) and the small prostate group (prostate volume< or =40 cc). P values < 0.05 were considered significant. RESULTS: The mean prostate volume was 42.2 cc (standard deviation: 8.6). The mean pain scores of VAS 1, 2 and 3 were 4.70+/-1.61, 3.15+/-2.44 and 1.05+/-1.51, respectively. In the large prostate group, the mean pains scores of VAS 1, 2 and 3 were 4.75+/-1.76, 3.51+/-2.76 and 1.29+/-1.70, respectively, whereas in the small prostate group, the means pain scores were 4.66+/-1.46, 2.77+/-2.0, and 0.80+/-1.26, respectively. Although there were no statistical differences of VAS 1, the larger prostate group revealed higher pain scores of VAS 2 and 3 compared with the small prostate group (p < 0.05). CONCLUSION: Patients with larger prostate volumes tend to feel more pain during and after TRUS guided prostate biopsy. Our findings suggest that additional analgesic strategies may be necessary when the patients with larger prostate undergo TRUS guided prostate biopsy.This work was supported by a grant from the Korea Research Foundation, which is funded by the Korean Government (MOEHRD, Basic Research Promotion Fund) (KRF-2006-331-E00248)

Thyroid Transcription Factor-1 Facilitates Cerebrospinal Fluid Formation by Regulating Aquaporin-1 Synthesis in the Brain

In the brain, aquaporin-1 (AQP-1), a water channel for high osmotic water permeability, is mainly expressed in the apical membrane of the ventricular choroid plexus and regulates formation of cerebrospinal fluid (CSF). Although the physiology of AQP-1 has been the subject of several publications, much less is known about the trans-acting factors involved in the control of AQP-1 gene expression. Here we report that TTF-1, a homeodomain-containing transcriptional regulator, is coexpressed with AQP-1 in the rat brain choroid plexus and enhances AQP-1 gene transcription by binding to conserved core TTF-1-binding motifs in the 5'-flanking region of the AQP-1 gene. Intracerebroventricular administration of an antisense TTF-1 oligodeoxynucleotide significantly decreased AQP-1 synthesis and reduced CSF formation. In addition, blockade of TTF-1 synthesis increased survival of the animals following acute water intoxication-induced brain edema. These results suggest that TTF-1 is physiologically involved in the transcriptional control of AQP-1, which is required for CSF formation