Platelet-rich plasma enhances the differentiation of dental pulp progenitor cells into odontoblasts.

AIM: To investigate the effects of PRP on odontoblastic differentiation using dental pulp progenitor cells derived from the dental papilla of rat incisors. METHODOLOGY: Monolayer cultures of odontoblastic lineage KN-3 cells were incubated with PRP for various time periods. The expression of dentine sialophosphoprotein (DSPP) and dentine matrix protein-1 (DMP-1) was determined using real-time reverse transcription-polymerase chain reaction and Western blot analyses. To further clarify the role of PRP in odontogenesis, KN-3 cells were stimulated with PRP in the presence of ascorbic acid and ß-glycerophosphate. The cells were stained for alkaline phosphatase (ALP), and ALP activity was quantified in cell lysates. The formation of mineralized nodules was assessed by alizarin red staining. Statistical analysis was performed by one-way analysis of variance. RESULTS: PRP increased the mRNA and protein expressions of odontoblastic markers, such as DSPP and DMP-1. Furthermore, PRP stimulated the ALP activity and mineralized nodule formation induced by ascorbic acid and ß-glycerophosphate in a time-dependent manner. CONCLUSIONS: PRP enhances odontoblastic differentiation of KN-3 cells. These results indicate that PRP could be a potential candidate for use in the regeneration of dentine-pulp complex.

Effect of local environment, fibrin, and basic fibroblast growth factor incorporation on a canine autologous model of bioengineered cartilage tissue.

We developed a technique to form a bioabsorbable synthetic polymer (polyglycolic acid, PGA) combined with a natural polymer (fibrin) to serve as a scaffold to help retain seeded cells and improve the seeding efficiency of chondrocytes in an implantable construct. This approach was evaluated in a canine autologous implant model of bioengineered cartilage. The implantation site (subcutaneous or intrafascial) and the use of basic fibroblast growth factor (b-FGF) were also evaluated with this system. The intrafascial implantation site yielded optimal results, especially when used in conjunction with fibrin and a b-FGF sustained-release system incorporated into the complex. A thicker, more sustained cartilagenous layer was formed, with a more vascularized outer fibrous supporting tissue layer. This combined approach of implant environment selection, natural polymer for cell retention, and growth factor supplementation offers a more optimized method for generating bioengineered auricular cartilage.

Characterization of dental epithelial progenitor cells derived from cervical-loop epithelium in a rat lower incisor.

Dental epithelial progenitor cells differentiate into various cell types during development of tooth germs. To study this mechanism, we produced immortalized dental epithelial progenitor cells derived from the cervical-loop epithelium of a rat lower incisor. The expression patterns of cytokeratin 14, nerve growth factor receptor p75, amelogenin, Notch2, and alkaline phosphatase were examined by immunohistochemistry in both lower and higher cell densities. The patterns of each were compared in the dental epithelium of rat lower incisors. The results demonstrated that these cells could produce ameloblast lineage cells, stratum intermedium cells, stellate reticulum, and outer enamel epithelium. Furthermore, fibroblast growth factor 10 stimulated proliferation of dental progenitor cells and subsequently increased the number of cells expressing alkaline phosphatase. These results suggest that fibroblast growth factor 10 plays a role in coupling mitogenesis of the cervical-loop cells and the production of stratum intermedium cells in rat incisors.

Transient co-localization of c-Jun N-terminal kinase and c-Jun with heat shock protein 70 in pulp cells during apoptosis.

The c-Jun N-terminal kinase (JNK) pathway and heat-shock proteins (HSPs) are involved in stress-induced apoptosis. Here we examined the association of JNK, c-Jun, and anti-apoptotic HSPs with pulp apoptosis during wound healing. In normal pulp, c-Jun was activated only in a few pulp cells, but JNK was not. HSP70 was expressed in the cytoplasm of pulp cells. One day after injury, active JNK and c-Jun were detected in apoptotic pulp cells, whereas HSP70 was detected in non-apoptotic cells. We also found the translocation of HSP70 into nuclei of pulp cells, and co-localization with active JNK and c-Jun. Four days after injury, active JNK and c-Jun disappeared in pulp cells, and HSP70 was relocalized from nuclei to the cytoplasm. These results suggest that the JNK pathway may be one of the compartments inducing apoptosis in pulp cells, and that HSP70 may have an inhibitory role in the apoptosis of pulp cells during wound healing.

Event-related brain potentials during selective attention to depth and form in global stereopsis.

To elucidate the discriminating processes of surface depth and boundary form in global stereopsis, event-related brain potentials (ERPs) were investigated by the detection of combinations of the attributes in random sequences. The attentional relevance of depth or form was associated with selection negativities (SNs) over the lateral occipito-temporal regions initiating at about 200 ms post-stimulus. The initial SNs were elicited irrespective of relevance to the other feature; the following parts increased only for stimuli with crossed disparity having the relevant dimension of the other feature, suggesting the independent selection of stereoscopic depth and form followed by the perceptual integration into an object.

Integrated neural representation of sound and temporal features in human auditory sensory memory: an event-related potential study.

The present study explored the effect of varying stimulus onset asynchrony (SOA) on the pre-attentive detection of frequency changes indexed by the mismatch negativity (MMN). Reading subjects were presented with sequences of tones delivered at two SOAs. Each sequence included either one or both of the two SOAs. In sequences with two SOAs, the order of the SOAs was alternated or sequenced randomly. The MMN amplitude was larger in sequences with one SOA than in those with two. The order of SOAs (alternate or random) had no effect on the MMN. These results revealed that the processings of frequency and SOA are not independent, suggesting that sound features and the timing of stimulation delivering the sound can be encoded into a functionally integrated representation.

Reversed discriminatory responses of heart rate during human REM sleep.

This study investigated the transfer of conditioned responses (CR) from wakefulness to sleep in humans, particularly focusing on an inverse relationship between wakefulness and rapid eye movement (REM) sleep. Eight subjects underwent classical differential conditioning during wakefulness using heart rate (HR) as a measure. After the conditioning, an extinction series was presented during stage 2 or REM sleep. Results showed: 1) that the direction of the evoked-HR response depended on the behavioral state (deceleration during wakefulness and acceleration during sleep), 2) a significant discrimination to the conditioned stimuli (CS) was observed during REM sleep but not during stage 2 sleep, and 3) the discriminatory CR was reversed during REM sleep. These facts suggest a difference in information processing during wakefulness and sleep, in particular REM sleep.

Classical conditioning during human NREM sleep and response transfer to wakefulness.

To assess learning abilities during human NREM sleep stages, five subjects underwent simple classical conditioning during stages 2-4 using heart rate (HR) as a measure. Results show (a) significant conditioning effect was observed during slow wave sleep (SWS; stage 3 + 4) but not during stage 2; (b) some evidence was obtained to support the view that conditioning effect during sleep transferred to wakefulness.

Visual evoked potentials elicited by subjective contour figures.

In order to investigate the relationship between the appearance of illusory figures and the wave form of visual evoked potentials (VEPs), 8 different visual pattern stimuli were presented to 8 normal subjects. Four of the stimuli (experimental stimuli) produced subjective figures and contours (squares and discs). The 4 other stimuli (reference stimuli), although equal to the experimental stimuli in the amount of physical energy, did not produce the illusion of squares or discs. Electrodes were placed on the scalp at central and occipital locations. Three prominent peaks in the occipital record were observed in all subjects. An amplitude difference of VEP N180 (N2) between the subjective figures and the reference stimuli was found in the values for each subject. Enhancement of the VEP of the illusory figure stimuli was observed for a specific component (N2), whereas the amplitude values at the central components and the occipital P120 (P2) and P280 (P3) were almost the same as the reference values. The VEP (N2 component) amplitude enhancement at the occipital area for subjective figure stimuli suggests that illusory contour formation takes place at higher levels in the visual system. This was known from experiments using dichoptic presentation.

Evaluation of endorectal ultrasound for the assessment of wall invasion of rectal cancer. Report of a case.

To accurately assess the depth of cancer invasion, endorectal ultrasound was performed using a radial scanner (Aloka, 7.5 MHz) in 145 patients with rectal cancer. High-resolution ultrasound clearly depicted five- or seven-layer echographic structures in the normal rectal wall, and demonstrated cancer as a hypoechoic lesion. These layer structures provided an important feature in determining the depth of cancer invasion. Rectal cancers of 122 patients were examined thoroughly by endorectal ultrasound. In 95 of these patients (77.9 percent), ultrasonic assessment of the depth of cancer invasion as classified in four groups was correct, corresponding accurately to the microscopic findings. Ultrasonography overestimated the depth of cancer invasion in 21 patients, however, and underestimated it in six patients. This study indicated that a cause of the overestimation was inflammatory cell infiltration around cancer, and that one possible cause of underestimation was microscopically minimal invasion of cancer. Although there are certain limitations of endorectal ultrasound, this ultrasound technique will provide valuable information to determine the preoperative staging of rectal cancer.