Prevalence of juvenile periodontitis in a circumpubertal population

A cross-sectional radiographic screening was performed on bite-wing pairs (BW) from 1872 10-12 year old schoolchildren in the Greater Worcester, Massachusetts area to assess the prevalence of juvenile periodontitis (JP). The 3-stage screening process entailed: (1) visual identification of possible cases based upon a visual assessment of BW for interproximal crestal bone levels greater than or equal to 2 mm from the cemento-enamel junction (CEJ) on greater than or equal to 1 permanent first molar; (2) identification of probable cases based upon BW from possible cases measured with a transparent ruler calibrated in millimeters; (3) finally, clinical confirmation of JP in consenting probable cases. A total of 1038 subjects were eligible to be included in the study (greater than or equal to 3 mesial sites readable). Of the 1038 eligible subjects, 117 possible and 103 probable cases were identified in stage 1 and stage 2, respectively. A total of 99 probable cases could be contacted and 43 were examined clinically. Two cases of JP were confirmed clinically in stage 3, yielding a prevalence rate of 4.6/1000. Specifically, this report defines a rate of JP in 10-12 year-old schoolchildren for the first time. In addition, these results indicate that BW can be used to identify children with JP from large data sets. However, further studies including complete clinical and radiographic examinations are necessary to determine whether this method is adequate for large epidemiologic studies.     

Plasticity of human motion processing mechanisms following surgery for infantile esotropia

Monocular oscillatory-motion visual evoked potentials (VEPs) were measured in prospective and retrospective groups of infantile esotropia patients who had been aligned surgically at different ages. A nasalward-temporal response bias that is present prior to surgery was reduced below pre-surgery levels in the prospective group. Patients in the retrospective group who had been aligned before 2 yr of age showed lower levels of response asymmetry than those who were aligned after age 2. The data imply that binocular motion processing mechanisms in infantile esotropia patients are capable of some degree of recovery, and that this plasticity is restricted to a critical period of visual development.     

The superoxide anion may mediate short- but not long-term effects of ultraviolet radiation on melanogenesis

Abstract The present study was carried out to examine the role of reactive oxygen species in mediating the melanogenic effects of UVR. B16 mouse melanoma cells responded to a single dose of UVR by showing increases in their melanin content. Although there was a small increase in melanin at 48-72 hours, which was associated with a rise in tyrosinase activity at 48 h, the greatest change occurred at 3 h and this was not associated with an increase in tyrosinase activity. This short-term response, unlike the more delayed melanogenic response, was reduced by superoxide dismut-ase (SOD). Xanthine oxidase (XO), which generates the superoxide anion (O₂). also increased the melanin content of B16 melanoma cells with effects at 3 h and 48 h. As with UVR, the delayed response was accompanied by an increase in tyrosinase activity but no such association was evident at 3 h. In addition, the short-term effect, like that seen with UVR, was reduced with SOD and to a lesser extent with catalase. In contrast to the effects found with XO, glucose oxidase, which generates hydrogen peroxide, had no effect on the melanin content or tyrosinase activity of the B16 cells. These results confirm previous observations that UVR is able to act directly on cells to bring about delayed increases in melanogenesis. They further demonstrate that UVR also stimulates melanogenesis through a more rapid action that is not associated with an activation of tyrosinase. This effect could be mediated by the O₂ which, rather than activating tyrosinase, could act by serving as a substrate for the enzyme.     

Reversing nerve-graft polarity in a rat model: the effect on function.

To evaluate the effect of nerve-graft polarity on function, a 1-cm segment of sciatic nerve was excised and reoriented in three groups of 20 adult Sprague-Dawley rats. In one group, the nerve was cut and anastomosed in the original orientation to act as a control. In the second group, the nerve-graft polarity was reversed 180 degrees. The final group underwent reversal of polarity 180 degrees and was rotated 180 degrees, (i.e., the posterior tibial nerve fascicles proximally were opposite to the peroneal nerve fascicles distally). Functional recovery was evaluated using Bain's modification of de Medinaceli's sciatic functional index (SFI). Rat-track analysis was performed over a 120-day period. Histologic correlation was also performed at the time of sacrifice. From our study, we concluded that reversing nerve-graft polarity, with or without rotation, does not influence subsequent function in this model.     

ADAMTS-4 activity on a proteoglycan vs. a polypeptide is controlled by the ancillary domains

Introduction In combination with the catalytic domain, the ancillary domains of the ADAMTS' are proposed to regulate activity via interactions with sulfated GAGs, the extracellular matrix (ECM) and cell surface. Interactions with both GAGs and the ECM have been attributed to the thrombospondin (TSP) type 1 motifs and spacer region ( Kuno and Matsushima 1998 ; Flannery et al. 2002 ). ADAMTS‐1, ‐4 and ‐5, all undergo cleavage within their respective spacer regions ( Flannery et al. 2002 ; Rodriguez‐Manzaneque et al. 2000 ; Georgiadis et al. 2002 ), an event which has been reported to increase activity towards the interglobular domain of aggrecan and decrease the heparin affinity of ADAMTS‐4 ( Flannery et al. 2002 ; Gao et al. 2002 ). Materials and methods V5‐ and His‐tagged recombinant human ADAMTS‐4 constructs terminating after the catalytic (?DTS), disintegrin‐like (?TS), TSP (?S) or spacer region (Full) were expressed in High‐Five cells. Proteoglycanase activities of the resultant proteins were assayed with solution digests of aggrecan and a polyacrylamide‐entrapped aggrecan particle assay. Proteolytic activity was measured using a novel, nonglycosylated, reporter substrate assay. Results All forms of ADAMTS‐4 were active to varying degrees in the reporter substrate assay. Digestion of aggrecan in solution digests was apparent in all proteins with the exception of the catalytic domain in isolation (?DTS). Activity towards aggrecan decreased with increasing truncation of the protein. Discussion Removal of the cysteine‐rich‐spacer domain and further C‐terminal truncations decrease the activity of ADAMTS‐4 towards aggrecan, whilst the proteolytic activity remains intact. Cleavages releasing the ancillary domains of ADAMTS' may therefore alter the catalytic activity of these enzymes against proteoglycans and also nonglycosylated polypeptides. More information is required about potential substrates for the processed forms of ADAMTS‐4.