Retinoic acid (RA) regulates the growth of human salivary gland adenocarcinoma cell line (HSG), through mediation of a retinoic acid receptor (RAR) expressed in the nuclei of HSG cells. In the process of induction of biological effects of RAR, the binding of RAR to a retinoic acid response element (RARE) on the promoter of the target gene is essential.

In this study, we first examined the DNA binding properties of the in vitro-transcribed and -translated human RAR α and RXR α, retinoid X receptor α/9-cis RAR α, using a gel-mobility- shift assay. Then, the DNA binding ability of the nuclear extract of HSG cells was investigated in vitro to examine whether RAR expressed in HSG cells has a biological function.

In vitro-translated RARαor RXRαdid not bind to [γ-³²P] ATP-labeled β RARE, a naturally occurring RARE found on the 5’-promoter of RAR β. However, RAR α bound to [³²P] β RARE in the presence of RXR α, suggesting that RAR α requires RXR α as a coregulator when it binds to β RARE. The binding was competed by an excess amount of unlabeled β RARE but not by a glucocorticoid response element (GRE), indicating that the binding was specific.

On the contrary, the nuclear extract of HSG cells bound to [³²P] β RARE by itself, and the binding was found to be specific in competition analysis using an excess amount of unlabeled β RARE and GRE. When the anlount of the nuclear extract used for the binding was increased, the band was broadened, indicating the heterogeneity of the binding.

These findings suggest that the nuclear extract of HSG cells contain molecules belonging to the RXR family, and these molecules cooperate with RAR of HSG cells in the process of transactivations which induce various biological functions of RAR.

The aim of this study is to investigate how masticatory patterns appearing characteristically at each masticatry movement are related to the function of masticatory muscles and to the maxillofacial morphology. The masticatory patterns of 60 adult male volunteers were into 8 types divided by multivariate statistical analysis using variables obtained from thier EMG and MKG recordings during jelly mastication. The function of masticatory muscles represented by the biting force and the resistance of muscles to fatigue, as well as the thickness of the masseter muscle and maxillofacial morphology were compared among of the 8 groups.The results showed that the masticatory pattern with fewer chewing strokes, shorter chewing time and smaller EMG integration tended to have a higher biting efficiency, while that with frequent chewing strokes,10nger chewing time and larger EMG integration, to have a lower biting efficiency.However, no distinct differences were found among the various groups in the changes in power spectrum median frequency and resistance to fatigue. The thickness of masseter muscle tended to be thinner in subjects with frequent chewing strokes and longer chewing time, but no clear differences were found among the other groups. No differences were observed in the maxillofacial morphology among the various groups.In conclusion, the difference in masticatory pattern can influence the biting intervals or phasic movements. However, this difference dose not necessarily influence the function represented by the resistance to fatigue or the tonic movements and maxillofacial morphology.

To investigate the glucose-demanding property of tumor cell, the change of in glucose uptake was applied to the evaluation of the efficacy of cencer chemotherapy in-bred WHT/Ht mice treated with 2-deoxy-2-[¹⁸F] fluoro-D-glucose (¹⁸FDG), short-lived position emission. The mice were divided into 3 groups: bleomycin (BLM) treated, BLM nontreated and normal groups. In the BLM-treated mice, BLM was inlected(0.1,1.0, or 10㎎/kg body weight) i.p. from 24 hours after inoculation 1 X 10⁶ tumor cells, daily for 7 days, and ¹⁸FDG was injected on the 4th day after the final BLM treatment. The BLM-nontreated group was treated with 18FDG on the 4th,7th or l lth day after inoculation. ¹⁸FDG was used i.v. at a dose of 20μCi/0.1 ml in all group. The radioactivities in tumor tissues, organs (liver, muscle, and skin) and blood of normal mice were measured with gamma-counter at 20,40,60 and 80 minites after the inlection of ¹⁸FDG and the uptake rate in each group was calculated by the following formula.

% Dose/g = tissue radioactivity/injected dose X 1/tissue weight X 100

The uptake of ¹⁸FDG in the liver, muscle, blood and skin were decreased gradually with tilne in the normal group but were increased in BLM-nontreated group. In the BLM-treated mice, the uptake ratio of ¹⁸FDG in the tumor was lower by injection 1.0㎎/kg than by inlection of 0.1 and 10.0 ㎎/kg. The patterns of ¹⁸FDG uptake in the BLM-treated mice were similar but differed from that in the BLM-nontreated mice.

The above findings clearly indicated that the uptake of ¹⁸FDG could be a useful index of tumor activity and suggested the practical applicability of positoron ernission tomography (PET)-¹⁸FDG to the evaluation of the efficacy of cancer chemotherapy.

Some kinds of prostaglandin (PGs) such as PGE₁, PGE₂ and PGF_2α are known to regulate the secretion and/or synthesis of many biologically active substances in mouse submandibular glands. This study was undertaken to investigate the effects of prostaglandins, especially PGE₂ which is the main PG synthesized in the submandibular glands, on submandibular esteroprotease, p-tosyl-L-arginine methyl esterase (TAMEase).

Injection of PGE₂ in male mice increased the activity of TAMEase of the submandibular glands after 20 minutes, and the increased level was maintained for 24-48 hours. PGF_2α also increased the TAMEase activity after 24 hours. SDS-polyacrylamide gel electrophoresis (PAGE) under reduced conditions and immunoblotting analyses revealed that the intensity of the 27.5 kilo dalton (kDa)-band of TAMEase molecules recognized by anti-mouse TAMEase rabbit antibody was increased l hour after administration of PGE₂ and the increased level continued for 24 hours. Moreover, an increase in TAMEase molecules was induced by other prostaglandins such as PGE₁, PGF_1α, PGF_2α, and PGI₂. As TAMEase is known to be a secreted protein, the TAMEase activity in saliva was measured before and after the injection of PGE₂- The TAMEase activity in saliva decreased l hour after the injection of PGE₂ in contrast with the increase in glandular TAMEase activity, suggesting the inhibition of TAMEase secretion from submandibular gland into saliva by PGE₂- To confirm the inhibition of the secretion of TAMEase by PGE₂ or PGF_2α, histological and immunohistochemical analyses were performed. Hematoxilin-eosin staining showed the accumulation of secretory granules in convoluted duct cells 10 minutes after the injection of PGE₂ or PGF_2α and the duct 10 minutes after the injection of PGs.

Immunohistochemical study showed that the abundant granules in the apical portion of the convoluted duct cells were positive to anti-TAMEase antibody. The storage of secretory granules in the convoluted duct cells was still observed even 24 hours after the injection.

These findings suggested that the increased levels of TAMEase activity and TAMEase molecules in the submandibular glands induced by the administration of PGs were due to the inhibition of the secretion of TAMEase molecules from the submandibular gland into saliva.