K. Seto

PROLONGED ENDOCHONDRAL BONE HEALING IN SENESCENCE IS SHORTENED BY LOW-INTENSITY PULSED ULTRASOUND IN A MANNER DEPENDENT ON COX-2

To test whether mechanical loading produces faster healing in aged mice, fractured femurs of aged 1-year-old mice were subjected to low-intensity pulsed ultrasound (LIPUS), a treatment that is routinely used to help heal fractures in humans. Cyclooxygenase-2 knockout mice (COX-2(-/-)), which lack an immediate early mediator of mechanical stimulation, were also studied by histochemistry, microcomputed tomography and quantitative polymerase chain reaction to determine the role of COX-2. The healing in the aged COX-2(-/-) mice is slow during the endochondral bone remodeling (>30 d), a period generally prolonged in senescence. For aged wild-type mice, LIPUS halved the endochondral phase to about 10 d, whereas that was not the case for aged COX-2(-/-) mice, which showed no apparent shortening of the prolonged endochondral-phase healing time. Injecting prostaglandin E(2) receptor agonists, however, rescued the COX-2(-/-) callus from insensitivity to LIPUS. In conclusion, COX-2 is a limiting factor in the delayed endochondral bone healing and is induced by LIPUS, which normalizes healing rate to the wild-type level.

Regional differences of type II collagen synthesis in the human temporomandibular joint disc: immunolocalization study of carboxy-terminal type II procollagen peptide (chondrocalcin)

The purpose of this study was to determine the regional differences of distribution of the carboxy-terminal type II procollagen peptide (pCOL-II-C; chondrocalcin) as markers of cartilaginous expression in the human temporomandibular joint (TMJ) disc. Twelve human TMJ discs without morphologic abnormalities were obtained from 12 fresh cadavers. All specimens were analysed for pCOL-II-C expression using polyclonal rabbit anti-human pCOL-II-C antibody in avidin-biotin-peroxidase complex staining. The results were demonstrated that the percentage of pCOL-II-C immunoreactive disc cells was significantly higher in the outer part (the articular surfaces) than in the inner part (the deep central areas) of the disc. These findings suggest that the tissue heterogeneity of cartilaginous expression reflects the functional demands of the remodelling process in the human TMJ disc.

Isolation and serological typing of ureaplasma in human saliva

Ureaplasmas were detected in the saliva of 3.5 per cent (12/342) of subjects. A total of 60 isolated strains did not revert to bacterial forms on repeated subculture in antibacterial agent-free media, failed to grow in serum-free media, were inhibited by digitonin and hydrolysed urea but not glucose or arginine. Twenty-five strains were divided into serotypes: I (5), II (3), III (5), IV (4) and VI (8 strains). Ureaplasmas of serotype I, II, III, IV and VI were harboured by 2, 1, 1, 1 and 3 subjects respectively and the remaining 4 subjects harboured 2 different serotypes. Ureaplasma-positive subjects were young and middle-aged and, except for 1 subject with mandibular arthrosis, suffered from periodontitis, pericoronitis, gingivitis and maxillary sinusitis. These accounted for only 6.1 per cent (11/180) of the series of subjects examined.