oxytetracycline--anhydrous and Hypertrophy

The role of bone morphogenetic protein-5 (BMP-5) in regulating chondrocytic activity during endochondral ossification was examined in the mouse proximal tibial growth plate. Short ear mice homozygous for the SEA/Gn point mutation in the coding region for BMP-5 (King, J. A. et al. Dev Biol 166:112122; 1994) and heterozygous long ear littermates were examined at 5 and 9 weeks of age (n = 9/group, four groups). Animals were injected with oxytetracycline to estimate the rate of growth and with bromodeoxyuridine to identify proliferative chondrocytes. Age-related changes in chondrocytic stereological and kinetic parameters were compared by image analysis of 1-microm-thick growth plate sections. The number of proliferative chondrocytes did not vary with age in either genotype, but proliferative phase duration increased significantly (approximately 67%) with age in the long ear mice, whereas no change was detected in the short ear mice. The number of hypertrophic chondrocytes increased significantly (approximately 27%) in the short ears, whereas this number decreased significantly (approximately 40%) in the long ears. There was a small, but significant, increase in hypertrophic phase duration (approximately 45%) in short ear mice, but no change was detected in the long ears. These results indicate that BMP-5 deficiency prevents age-related decelerations in chondrocytic proliferation and initiation of hypertrophic differentiation, suggesting a role of BMP-5 in inhibiting these processes.

Topics: Animals; Bone Development; Bone Morphogenetic Protein 5; Bone Morphogenetic Proteins; Bromodeoxyuridine; Cell Count; Cell Differentiation; Cell Division; Chondrocytes; Disease Models, Animal; Female; Growth Plate; Hypertrophy; Image Processing, Computer-Assisted; Mice; Mice, Knockout; Oxytetracycline; Tibia

In this study, we tested the hypothesis that hypertrophic cell volume varies directly with the rate of longitudinal bone growth. The volume of hypertrophic chondrocytes (using stereological techniques) and longitudinal bone growth per 24 h (using oxytetracycline labeling techniques) were measured in the proximal and distal radial growth plates and the proximal and distal tibial growth plates of 21- and 35-day-old hooded rats and 21- and 35-day-old Yucatan pigs. We demonstrated a high coefficient of correlation (rats 0.98, pigs 0.83) between the final volume of hypertrophic chondrocytes and the rate of longitudinal bone growth over a wide range of growth rates and volumes of hypertrophic chondrocytes. In addition, we demonstrated a positive linear relationship between the rate of longitudinal bone growth and the final volume of hypertrophic chondrocytes. The slope of the regression line was different for rats than for pigs. The relationship was independent of the location of the growth plate in the animal and the age of the animal. The data suggest that mechanisms regulating volume changes in hypertrophic chondrocytes may exist and that chondrocytic volume increase is a major determinant of the rate of longitudinal bone growth. However, the relative contribution of cellular hypertrophy to longitudinal bone growth may be different in rats than in pigs.

Topics: Animals; Bone Development; Cartilage; Female; Growth Plate; Hypertrophy; Least-Squares Analysis; Male; Oxytetracycline; Radius; Rats; Regression Analysis; Swine; Tibia

Addition of penicillin, Terramycin, or kanamycin to the drinking water of adult mice rapidly induced in them an enlargement of the cecum. In all animals, this occurred within 12 hr after the beginning of drug administration-the effect being most pronounced with penicillin. The cecums remained enlarged and generally continued to increase in size as long as the antibacterial drugs were administered. The increase in wet weight of the cecums was due primarily to an accumulation of water in the lumens during the first 24-48 hr of drug administration. At that time, there were no detectable histological changes in any case, but the bacteriological picture differed from drug to drug. The cecums were free of bacteria in animals receiving penicillin, fusiform-shaped bacteria and bacteroides were present in those receiving Terramycin, and lactobacilli and bacteroides in those receiving kanamycin. After the initial 48 hr, an abundant and complex secondary microflora developed in all treated animals, its composition being characteristic for each type of antibacterial drug. When penicillin was administered for 2 wk, the cecal weights and microbial populations did not return to normal levels for over 14 days after discontinuance of the drug. This recovery period could be shortened to 10 days by giving the mice food contaminated with cecal homogenates prepared from normal animals. A period of 7 or 8 days was required for the cecal weights and microflora to reach normal levels when the administration of penicillin lasted only 24 hr; this period could not be shortened by giving the animals contaminated food. The effects of drugs on the size and bacterial contents of the cecum have been discussed in the light of earlier findings concerning the characteristics of the huge cecums uniformly found in germfree mice. Taken together, these observations support the hypothesis that certain elements of the intestinal microflora-not yet completely identified-play an essential role in maintaining the integrity of the water-transport mechanism in the intestinal epithelium.

Topics: Animals; Cecum; Germ-Free Life; Hypertrophy; Kanamycin; Male; Mice; Organ Size; Oxytetracycline; Penicillins; Water-Electrolyte Balance

Topics: Blood; gamma-Globulins; Glycoproteins; Hepatectomy; Hyperplasia; Hypertrophy; Kidney Diseases; Liver Diseases; Necrosis; Neoplasms; Neoplasms, Experimental; Oxytetracycline; Rats; Research; Wounds and Injuries