Guaiacol, which is a phenolic compound with a methoxy group and used in traditional dental pulp sedation, has the property of inducing cell proliferation. To clarify these mechanisms of guaiacol, this study examined the hydroxyl radical (^·OH) scavenging effects of guaiacol in vitro. Generation of ^·OH was carried out by the Fenton reaction using mixture of ascorbic acid, H₂O₂, and Fe(III)-EDTA, and ^·OH was detected by measuring the ^·OH-mediated production of degradation products of deoxyribose, which reacts with 2-thiobarbituric acid (TBA) and is relatively stable for a long time. At concentrations of 10^-10 M to 10^-3 M, guaiacol inhibited the TBA reactive substance (TBA-RS) formation in a dose-dependent manner. Phenol and formaldehyde were also found to inhibit the TBA-RS formation, but their inhibitory activities were lower than that of guaiacol. The concentrations of guaiacol, phenol, and formaldehyde needed to cause 50% inhibition of TBA-RS formation were approximately 5 × 10^-6, 5 × 10^-5, and 2 × 10^-3 M, respectively. In this reaction system, guaiacol showed no chelating reaction with ferrous ion and did not directly react with H₂O₂. Guaiacol also exhibited radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, but its scavenging activity was lower than that toward ^·OH. These results suggest that guaiacol is a potent scavenger of reactive oxygen radicals and that its radical scavenging activity may be associated with its effect on cell proliferation.

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Assessment of the mucin subclasses in the gastric juices of severe chronic rheumatoid arthritis (RA) patients was compared with non-RA cases which received the eradication treatment of Helicobacter pylori (H. pylori). Gastric juice samples were obtained from 8 RA patients (5 for H. pylori-negative and 3 for H. pylori-positive) and 5 control subjects in which we confirmed the successful eradication of H. pylori. The gastric luminal mucins were extracted and isolated by the ethanol precipitation method. These mucin solutions were digested with chymotrypsin, dialyzed, lyophilized, and redissolved. The obtained specimen was applied to an ion exchange column containing DEAE-Sepharose CL-6B and eluted with a discontinuous salt gradient in three salt steps. The gastric luminal mucins were divided into three fractions based on the distinctive sialic acid content. The proportion of acidic mucin rich in sialic acid from the gastric juice of RA patients without the H. pylori infection was significantly lower than those RA patients with H. pylori or the control subjects. A decrease in the acidic mucin content after eradication of H. pylori was commonly observed in all the control subjects. Our investigation raises the possibility that the gastric mucosae of RA patients have resistance against H. pylori infection. And the analysis of the composition in the gastric luminal mucin may be a very useful tool for the evaluation of gastric homeostasis in RA patients.

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In the course of cloning of bovine cDNA for proline-rich protein (PRP) P-B from bovine tooth germ cDNA, we found that one clone with 662 bp contained a 5'-terminal 393 bp (1-393 bp) sequence essentially identical to that of human P-B cDNA (154-546 in D29833) and bovine P-B cDNA (1-356 bp in AB192573) and a sequence of 233 bp (394-626 bp) highly homologous to the segment of E. coli K12 genomic DNA (365511-365744 in NC000913). Although the latter sequence is contained in the vector pT7Blue, which we used, our results show that this chimeric structure in bovine tooth germ P-B cDNA is not an artifact formed during the cloning process, but intrinsic to the bovine genome since the chimeric structure was detected in bovine tooth germ and bovine genomic DNA.

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Bone tissue, with its dynamic microenvironment featuring osteoclastic bone resorption, angiogenesis and matrix degradation, appears to facilitate proliferation of tumor cells after the onset of bone metastasis. In this study, we examined metastatic lesions in the femora of BALB/c nu/nu mice two weeks after intracardiac injection with human breast carcinoma MDA-231 cells. Histopathological observations showed the metastatic lesions close to the chondro-osseous junction, and revealed MDA-231 cells loosely intermingled with different cell types such as osteoblasts, fibroblastic stromal cells, osteoclasts and endothelial cells. In the metastatic nest, many tartrate resistant acid phosphatase (TRAPase)-positive osteoclasts accumulated in direct contact with or were close to alkaline phosphatase (ALPase)- or receptor activator of NF-κB ligand (RANKL)-positive osteoblastic cells. It seems likely that osteoclastogenesis is mediated through cell-to-cell contacts with ALPase- and RANKL-expressing osteoblastic cells. Formation of many capillaries lacking complete basal membranes and pericytes ratified the results of in situ hybridization, which revealed intense expression of VEGF in tumor nests, and therefore, indicated ongoing tumor-induced angiogenesis. The tumor cells possessed matrix metallo-proteinases (MMPs)-1 and -9, and frequently extended their stout cytoplasmic processes into fragmented fibrillar components of the growth plate cartilage, implicating degradation of cartilaginous matrix. Thus, osteolytic bone metastasis has demonstrated pathological features as tumor-induced angiogenesis and degradation of extracellular matrix, in addition to osteoclastogenesis. This complex interplay between tumor cells and host tissues may enable and nourish the e tablishment of a microenvironment that facilitates tumor progression.

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Spontaneous contractions of the intestine are thought to play an important role in the gastrointestinal motility, including peristalsis. In the present study, we investigated mechanisms for regulation of the frequency of spontaneous contractions, using longitudinal muscle strips in rat distal colon. Atropine significantly decreased the frequency of spontaneous contractions, indicating that neuromuscular transmission via muscarinic receptors increases the frequency of spontaneous contractions. SB-204070, 5-HT₄ receptor antagonist also significantly decreased the frequency of spontaneous contractions, indicating that the activation of 5-HT₄ receptors also increases the frequency of spontaneous contractions. In conclusion, it is suggested that muscarinic and 5-HT₄ receptors participate in the regulation of the frequency of spontaneous contractions in the longitudinal muscle in rat distal colon, and that the frequency of spontaneous contraction is controlled by the enteric neurons.

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We have evaluated the effect of natural human interferon (IFN)-α on the growth of chlamydia trachomatis in human epithelial cells in vitro and revealed that IFN-α has reduced both growth and infectivity of C. trachomatis. The effect of IFN-α was reversed by the addition of exogenous L-tryptophan and iron to the culture medium, suggesting that antichlamydial effect of IFN-α was caused by depletion of intracellular tryptophan and iron, both of which are essential for chlamydial growth. When IFN-α was combined with another antichlamydial cytokines, IFN-γ and tumor necrosis factor (TNF)-α, the effect was synergistically enhanced. Therefore, IFN-α would act coordinately with other cytokines such as IFN-γ and TNF-α, and play an important role in host defense against infection and in the establishment of persistent chlamydial infection of host, in which the organism remains viable, but in a culture-negative state.

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