Orthodontic tooth movement occurs as a result of resorption and formation of the alveolar bone due to an applied load, but the stimulus responsible for triggering orthodontic tooth movement remains the subject of debate. It has been suggested that the periodontal ligament (PDL) plays a key role. However, the mechanical function of the PDL in orthodontic tooth movement is not well understood as ...

Following a suggestion of Pratt, we consider propositional dynamic logic in which programs are nondeterministic finite automata o~¢er atomic programs and tests (i.e., flowcharts), rather than regular expressions. While the resulting version of PDL, call it APDL, is clearly equivalent in expressive power to PDL, it is also (in the worst case) exponentially more succinct. In particular, deciding ...

In this paper, we describe Parallel Dynamic Logic (PDL) which exhibits high speed, no charge sharing problem. PDL uses only parallel-connected transistors for logic evaluation and is a good candidate for high-speed low-voltage operation. It has less back-bias e ect compared to other logic styles which use stacked transistors. Furthermore, PDL needs no signal ordering nor tapering. PDL with spee...

We present a direct reduction of dynamic epistemic logic in the spirit of [4] to propositional dynamic logic (PDL) [17, 18] by program transformation. The program transformation approach associates with every update action a transformation on PDL programs. These transformations are then employed in reduction axioms for the update actions. It follows that the logic of public announcement, the lo...

Various ultrastructural studies on the periodontal ligament (PDL) microvasculature have been reported. However, the lack of a systematic classification has led to much confusion in the terminology used to define vessel types. On the basis of morphological criteria, the author proposes that 3 vessel types are present in the PDL: terminal arterioles (Type A vessels), capillaries (Types B-1 & B-2)...

INTRODUCTION Recently, a novel protein, follicular dendritic cell secreted protein (FDC-SP), has been identified in human periodontal ligament (PDL) tissue and a biomolecular study suggested that the expression of FDC-SP might be associated with the expression of the PDL phenotype. The purpose of this study was to test the effect of FDC-SP on the proliferation and phenotype of PDL cells. MATE...

Cyclic compressive force is an important mechanical stimulus on periodontal ligament (PDL). The differential expression of genes in PDL cells is thought to be involved in the remodeling of periodontal tissues subjected to mechanical stress. However, little is known about differentially expressed genes in PDL cells under cyclic compressive force. In our study, human PDL cells were subjected to 4...

Differences in the secretion of some vascular regulators, endothelin-1 (ET-1), prostacylin (PGI2), thromboxane A2 (TXA2) and nitric oxide (NO) associated with in vitro aging, were investigated in cultured endothelial cells isolated from normal human umbilical veins (HUVECs). HUVECs from different population doubling levels (PDLs) were cultured in a medium MCDB-104 supplemented with FBS and ECGF...

Growth differentiation factor 5 (GDF-5), a member of the transforming growth factor beta (TGF-β) superfamily expressed in periodontal tissues, promotes extracellular matrix (ECM) in periodontal ligament (PDL) cells. Matrix metalloproteinases (MMP) are proteolytic enzymes that degrade ECM and are expressed in PDL cells. To date, little is known about the regulation of MMP synthesis and secretion...

The purpose of the present study was to histopathologically and immunohistochemically investigate the distribution of proteoglycans in human periodontal ligament (PDL). Specimens from osteotomy and tooth extraction having healthy PDL were studied. Histologically, PDL consisted of fibrous tissues, involving a compact arrangement area and edematous or myxoid area. Immunohistochemically, versican ...