PDGF-D, a new protease-activated growth factor

Platelet-derived growth factor (PDGF) has been directly implicated in developmental and physiological processes, as well as in human cancer, fibrotic diseases and arteriosclerosis. The PDGF family currently consists of at least three gene products, PDGF-A, PDGF-B and PDGF-C, which selectively signal through two PDGF receptors (PDGFRs) to regulate diverse cellular functions. After two decades of searching, PDGF-A and B were the only ligands identified for PDGFRs. Recently, however, database mining has resulted in the discovery of a third member of the PDGF family, PDGF-C, a functional analogue of PDGF-A that requires proteolytic activation. PDGF-A and PDGF-C selectively activate PDGFR-alpha, whereas PDGF-B activates both PDGFR-alpha and PDGFR-beta. Here we identify and characterize a new member of the PDGF family, PDGF D, which also requires proteolytic activation. Recombinant, purified PDGF-D induces DNA synthesis and growth in cells expressing PDGFRs. In cells expressing individual PDGFRs, PDGF-D binds to and activates PDGFR-beta but not PDGFR-alpha. However, in cells expressing both PDGFRs, PDGF-D activates both receptors. This indicates that PDGFR-alpha activation may result from PDGFR-alpha/beta heterodimerization.

Identification of a novel human fibroblast growth factor and characterization of its role in oncogenesis

The fibroblast growth factor (FGF) family of signaling molecules has been implicated in normal developmental and physiological processes, as well as in human malignancy. Using a homology-based genomic DNA mining process, we identified a human gene encoding a novel member of the FGF family, that we designate FGF-20. The FGF-20 cDNA was isolated, and its sequence confirmed the gene prediction. FGF-20 is expressed in normal brain, particularly the cerebellum, and in some cancer cell lines. Recombinant FGF-20 protein induces DNA synthesis in a variety of cell types and is recognized by multiple FGF receptors. Ectopic expression of FGF-20 in NIH 3T3 cells renders the cells transformed in vitro and tumorigenic in nude mice. These results underscore the utility of mining genomic DNA databases and reveal FGF-20 to be a novel oncogene that may play a role in human cancer.

Comparison of acetaminophen, ibuprofen, and nabumetone therapy in rats with pulpal pathosis

The purpose of this study was to determine if daily treatment with acetaminophen, ibuprofen, or nabumetone would alter prostaglandin E2 (PGE2)/leukotriene B4 (LTB4) synthesis in exposed, infected dental pulp and periradicular tissue in rats. Dental pulp of the bilateral first and second mandibular molars were exposed for 15 or 24 days. Rats were divided into four groups. A daily pharmacological oral dose of one of the medications or the suspending solution alone was administered to the designated group. Eicosanoids were extracted from pulpal and periradicular tissues and assayed. PGE2 was significantly elevated in pulp-exposed, nontreated rats and was significantly reduced in the ibuprofen- and nabumetone-treated groups. LTB4 was significantly increased in all pulp-exposed groups at 15 days when compared with control nonexposed groups. Results showed that only ibuprofen reduced LTB4 in the exposed dental pulp at 24 days, although it did not do so at 15 days. Repetitive treatment with acetaminophen did not suppress PGE2/LTB4 in pulp-exposed molars.

Differential effect of TGF-beta 1 and PDGF on proliferation of periodontal ligament cells and gingival fibroblasts

Regeneration of periodontal tissues requires orchestration of several cell types. Two cell types, gingival fibroblastic cells (gingival fibroblasts) and cells from the periodontal ligament (PDL cells), were studied to compare the effects of supplemental addition of TGF-beta 1 and PDGF on proliferation. Cells obtained from healthy donors were cultured in 10% FBS supplemented with either 10 ng/ml TGF-beta 1, 20 ng/ml PDGF, or both. Thymidine incorporation was measured after 24, 48, or 72 hours. Data from PDL (analyzed by ANOVA) showed the following relations: at 24 hours TGF beta 1/PDGF = PDGF > TGF-beta 1 = control; at 48 hours TGF beta 1/PDGF > TGF-beta 1 > PDGF > control; at 72 hours TGF beta 1/PDGF > TGF-beta 1 > PDGF = control. Gingival fibroblast cultures showed the following relations: at 24 and 48 hours TGF beta 1/PDGF = PDGF > TGF-beta 1 = control; at 72 hours, TGF beta 1/PDGF = PDGF > control with TGF beta 1 not different from control or factor combinations. Both TGF-beta 1 and TGF-beta 1/PDGF showed a significantly greater increase in proliferation of PDL cells than in gingival fibroblasts at 48 and 72 hours (Student t test P < 0.05). In contrast, PDGF stimulated proliferation of gingival fibroblasts was significantly greater than PDL cells at 72 hours (P < 0.05). Thus, supplementation of complete cultures (containing 10% FBS) with TGF-beta 1 alone or combined with PDGF stimulates proliferation of PDL cells to a significantly greater extent than proliferation of gingival fibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence and histology of human accessory parotid glands

The parotid glands of 228 Japanese human cadavers were examined to determine the incidence and histological features of accessory parotid glands. The incidence was found to be 56% with no differences between right and left sides or between sexes. Thirty parotid glands and their associated accessory glands were examined histologically: eight of these accessory glands were found to be mixed secretory glands (i.e., containing both serous and mucous acini). Thus, the pattern of differentiation of a significant fraction of accessory glands differs from that of the main parotid gland: it appears that mixed acini, present in the early stages of development, persist into later life, and their presence may be related to tumors developing at these sites.

A comparison of techniques for cleaning endodontic files after usage: a quantitative scanning electron microscopic study

One-hundred ten new endodontic files were used to prepare canals and were then cleaned using three different techniques: (a) gauze soaked with alcohol, (b) sponge soaked with alcohol, and (c) ultrasonic bath. The cleaning ability of each of these techniques immediately after use and after 1 h of delay were compared. Identical areas on each file were examined by using a custom-made jig. Morphometric analysis of debris was carried out using a Bioquant image analysis system. Sponge/alcohol was the worst cleaning method; this was significantly different from the other two techniques. The gauze/alcohol and ultrasonic bath were similar. The 1-h delay before instrument cleaning did not affect the ability of any of the techniques tested. None of the methods tested were able to totally clean the files.

Exercise-induced myocardial capillary growth in the spontaneously hypertensive rat

Spontaneously hypertensive rats (SHR) were studied to test the hypothesis that endurance exercise training can stimulate capillary growth and offset the decrement associated with the development of myocardial hypertrophy. The exercise group (SHR-T) was trained on a treadmill for 10 weeks at 70-90% maximum VO2 and compared to nontrained SHR and normotensive Wistar-Kyoto (WKY) at 16 weeks of age. Thus, the training program coincided with the development of hypertension and hypertrophy in SHR. Image analysis was used to study capillaries in one micron thick left ventricular tissue samples from perfuse-fixed hearts. Training did not affect left ventricular mass or blood pressure, but reversed the characteristic decrements in capillary surface area (CSA), volume (CV), and numerical density (CD). CSA and CV were most markedly affected by exercise, as mean values for these parameters increased by 31 and 40%, respectively, compared to SHR. The magnitude of these changes approximated the magnitude of hypertrophy as evidenced by left ventricular weight/body weight ratios (42% in SHR and 37% in SHR-T). Anatomical intercapillary distance was also normalized by training (means +/- SEM): SHR-T, 11.65 +/- 0.31; SHR, 13.97 +/- 0.37; WKY, 11.19 +/- 0.37. These data indicate that exercise stimulates capillary growth in the face of developing hypertension and its related left ventricular hypertrophy.

Effect on dimensional accuracy when reattaching fractured lone standing teeth of a cast

1. Ninety-five percent of the variation in position of reattached lone standing incisor and premolar stone teeth was within the limits of physiologic tooth movement. 2. No significant differences resulted from the use of Class I or Class II stones, the technical experience of the operator, or the diameter of the neck of the tooth. 3. There were significant differences between Duco cement and Eastman 910 used between the tooth fragments, but none between Duco cement used between the tooth fragments and Eastman 910 used on the fracture line. However, with all three techniques, most of the changes were within the physiologic limits of healthy tooth movement.