• The korean journal of orthodontics
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• v.10 no.1
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• pp.37-43
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• 1980

This study was undertaken to assess the effects of demethylchlortetracycline on bone growth of mandibular symphyseal region in rats. Demethylchlortetracycline at 30mg/kg body weight, respectively, were daily administered by mouth to the sewen female rats from 10th day of pregnancy to 13th day. Thirty six new-born rats from these experimental animals were used for histological examination at 1, 5, 10, 15, 20, 25 and 30 days. All these new-born rats were killed by an overdose of ether. Mandibular bodies were removed and fixed in $10\%$ neutral formalin,. Carney and aceton. Specimens were embedded, sectioned and stained with H-E, Van Gieson, PAS and prepared for alkaline phosphatase. The results were as follows; 1. Until erupting of incisors, hyaline cartilage was located in relatively large symphyseal space, but bone trabeculae of ossifying area at incisal side were arranged irregularly in experimental group. 2. During this period, PAS reaction was moderately positive, but alkaline phosphatase reaction was slightly positive. 3. By erupting or incisors, symphyseal space appeared narrower like control group, but alkaline phosphatase reaction tended to slow down. 4. By erupting of molars, symphyseal space appeared muck narrower, and cartilane plate was reduced and aealed off like control group. Alkaline phosphatase reaction tended to slow down severely.

• Microbiology and Biotechnology Letters
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• v.25 no.3
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• pp.317-321
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• 1997

The effect of ammonium ion concentration on the production of demethyl- chlortetracycline (DMCT) by a DMCT overproducing mutant, Streptomyces aureofaciens 27VR, and the optimal control of pH were studied. The optimum levels of pH control were 6.5-6.6 for 80-120 hr, 6.4- 6.5 for 121-150hr and 6.3-6.4 for 151-190hr. The optimum level of ammonium ion concentration during the pH control was lower than 20 mg%. Under the optimized culture condition, it was possible to produce DMCT with an 18% increase in productivity compared to that of standard culture condition in 190hrs of the fermentor operation.