Periodontal regeneration: focus on growth and differentiation factors.
Several growth and differentiation factors have shown potential as therapeutic agents to support periodontal wound healing/regeneration, although optimal dosage, release kinetics, and suitable delivery systems are still unknown. Experimental variables, including delivery systems, dose, and the common use of poorly characterized preclinical models, make it difficult to discern the genuine efficacy of each of these factors. Only a few growth and differentiation factors have reached clinical evaluation. It appears that well-defined discriminating preclinical models followed by well-designed clinical trials are needed to further investigate the true potential of these and other candidate factors. Thus, current research is focused on finding relevant growth and differentiation factors, optimal dosages, and the best approaches for delivery to develop clinically meaningful therapies in patient-centered settings.

title: The critical-size supraalveolar peri-implant defect model: reproducibility in histometric data acquisition of alveolar bone formation and osseointegration.
abstract: The objective of this report is to present the reproducibility of outcomes assessments in the Critical-Size Supraalveolar Peri-Implant Defect Model.



Two examiners without specific experience in histological analysis and one experienced examiner performed the histometric evaluation. A comprehensive training program in data acquisition and histological analysis was established, the inexperienced examiners underwent approximately 12 h of training over multiple sessions. A custom-designed image analysis software macro and a computer-based image system were used to analyse digital images generated by a microscope camera system. Nine parameters for newly formed and resident bone were evaluated. Examiners performed histometric analysis using 36 histologic sections selected from critical-size supraalveolar peri-implant defects in 12 male Hound Labrador Mongrel dogs. Buccal and lingual measurements were performed in 72 sites. Intra- and inter-examiner reproducibility were evaluated using the concordance correlation coefficient (CCC) and means +/- SD of the differences. Systematic errors were evaluated using an F-test for equality of means and variances.



Intra-examiner reproducibility was high for all parameters evaluated, the lowest CCC observed being 0.87. Inter-examiner reproducibility was also high, most CCCs exceeding 0.90. Minor systematic errors for intra- and inter-examiner comparisons were occasionally observed. The results imply a high temporal stability because recordings were performed 3 months apart. Measurement errors were stable throughout the range of observations for all parameters.



High examiner reproducibility and temporal stability can be achieved for histometric data acquisition using the Critical-Size Supraalveolar Peri-Implant Defect Model. Examiner reproducibility should be routinely assessed, reported, and accounted for to assure the quality of evidence generated by preclinical studies.

title: Genetic reconstruction of mouse spermatogonial stem cell self-renewal in vitro by Ras-cyclin D2 activation.
abstract: Spermatogonial stem cells (SSCs) undergo self-renewal division and support spermatogenesis. Although several cytokines coordinate to drive SSC self-renewal, little is known about the mechanisms underlying this process. We investigated the molecular mechanism by reconstructing SSC self-renewal in vitro without exogenous cytokines. Activation of Ras or overexpression of cyclins D2 and E1, both of which were induced by Ras, enabled long-term self-renewal of cultured spermatogonia. SSCs with activated Ras responded properly to differentiation signals and underwent spermatogenesis, whereas differentiation was abrogated in cyclin transfectants after spermatogonial transplantation. Both Ras- and cyclin-transfected cells produced seminomatous tumors, suggesting that excessive self-renewing stimulus induces oncogenic transformation. In contrast, cells that overexpressed cyclin D1 or D3 failed to make germ cell colonies after transplantation, which indicated that cyclin expression pattern is an important determinant to long-term SSC recolonization. Thus, the Ras-cyclin D2 pathway regulates the balance between tissue maintenance and tumorigenesis in the SSC population.

title: Measurement issues across different cultures.
abstract: The purposes of this methodologic paper are to (1) describe theoretical background in conducting research across different cultures; (2) address measurement issues related to instrument administration; and (3) provide strategies to deal with measurement issues.



A thorough review of the literature was conducted. A theoretical background is provided, and examples of administering instrument in studies are described.



When applying an instrument to different cultures, both equivalence and bias need to be established. Three levels of equivalence, i.e., construct equivalence, measurement unit equivalence, and full score comparability, need to be explained to maintain the same concept being measured. In this paper, sources of bias in construct, method, and item are discussed. Issues related to instrument administration in a cross-cultural study are described.



Researchers need to acknowledge various group differences in concept and/or language that include a specific set of symbols and norms. There is a need to question the philosophical and conceptual appropriateness of an assessment measure that has been conceptualized and operationalized in a different culture. Additionally, testing different response formats such as narrowing response range can be considered to reduce bias.

title: Detection of E. coli in beach water within 1 hour using immunomagnetic separation and ATP bioluminescence.
abstract: The contamination of beach waters occurs from the discharge of storm water and sanitary sewer overflows containing faecal material. Additional faecal material derives from discharge of animals and waterfowl. In order to protect public from exposure to faecal-contaminated water, it is required to test enteric indicators in beach water. The problem is that the traditional culture-based methods cannot meet this goal because it takes too long (>24 h), so the results are not available until a day later. A rapid method for testing beach water for Escherichia coli within 1 h has been developed. Immunomagnetic separation (IMS) and ATP bioluminescence were used for selective capture and quantification, respectively. This rapid method was compared to the current method (m-TEC) using beach water samples. The beach samples were prefiltered with a 20 microm pore size filter in order to remove algae, plant debris and large particles. The results showed that the prefiltration step did not trap the bacteria which were present in the original water samples. The prefiltered water was then passed through a 0.45 microm pore size filter for concentration. The deposited bacteria were resuspended and then mixed with superparamagnetic polystyrene beads (diameter of 0.6 microm) that were coated with E. coli antibodies. After IMS, the quantification of the E. coli was done by ATP bioluminescence. The results obtained with IMS-ATP bioluminescence correlated well with the plate count method (Rsq = 0.93). The detection limit of the assay was about 20 CFU/100 mL, which is well below the US EPA limits for recreational water. The entire procedure can be completed in less than 1 hour. The necessary equipment is portable and was tested on-site.

title: Factor structure investigation of perceived facilitators and barriers in end-of-life care among Korean nurses.
abstract: The aim of this study was to assess the validity and reliability of the Korean version of a questionnaire assessing facilitators/barriers in end-of-life care that was originally developed for nurses in the USA.



Back-translation was undertaken to produce the Korean version. A principal component analysis with varimax rotation and Cronbach's alpha was used to test factorial validity and reliability, respectively.



The analysis examined data from 383 nurses in a tertiary hospital in Korea. For end-of-life care facilitators, five factors accounted for 59% of the total variance. The factors were labeled "family preparedness", "support for nurses", "nurse-patient relationship", "transition after death", and "decision-making". Six factors, explaining 59% of the variance, were extracted for end-of-life care barriers. These factors were "misunderstanding patient's will", "preoccupied nursing workload", "lack of institutional support", "dealing with family's maladaptive coping", "visiting hours", and "communication about patient's status with family members". Cronbach's alpha was 0.89 for the 23 facilitator items and 0.90 for the 24 barrier items.



Overall, the findings demonstrate that the questionnaire has measurement properties in a sample of Korean nurses. Further studies are needed with different populations to reflect end-of-life care in various clinical settings.

title: Targeted cell immobilization by ultrasound microbeam.
abstract: Various techniques exerting mechanical stress on cells have been developed to investigate cellular responses to externally controlled stimuli. Fundamental mechanotransduction processes about how applied physical forces are converted into biochemical signals have often been examined by transmitting such forces through cells and probing its pathway at cellular levels. In fact, many cellular biomechanics studies have been performed by trapping (or immobilizing) individual cells, either attached to solid substrates or suspended in liquid media. In that context, we demonstrated two-dimensional acoustic trapping, where a lipid droplet of 125 µm in diameter was directed transversely toward the focus (or the trap center) similar to that of optical tweezers. Under the influence of restoring forces created by a 30 MHz focused ultrasound beam, the trapped droplet behaved as if tethered to the focus by a linear spring. In order to apply this method to cellular manipulation in the Mie regime (cell diameter > wavelength), the availability of sound beams with its beamwidth approaching cell size is crucial. This can only be achieved at a frequency higher than 100 MHz. We define ultrasound beams in the frequency range from 100 MHz to a few GHz as ultrasound microbeams because the lateral beamwidth at the focus would be in the micron range. Hence a zinc oxide (ZnO) transducer that was designed and fabricated to transmit a 200 MHz focused sound beam was employed to immobilize a 10 µm human leukemia cell (K-562) within the trap. The cell was laterally displaced with respect to the trap center by mechanically translating the transducer over the focal plane. Both lateral displacement and position trajectory of the trapped cell were probed in a two-dimensional space, indicating that the retracting motion of these cells was similar to that of the lipid droplets at 30 MHz. The potential of this tool for studying cellular adhesion between white blood cells and endothelial cells was discussed, suggesting its capability as a single cell manipulator.