Reports

Abstract

In the past, vertical intrusive movement of teeth has been considered difficult and most routine clinical vertical movement of teeth has been confined to extrusion. It has been suggested that attempts at intrusion may result in an increased incidence of root resorption and also in occasional devitalization.

The displacement and resulting stress fields associated with such treatment can be successfully studied using the finite element method. In the case being considered initial movements are known to be small; therefore, the assumption in the study that the material behaves linear-elastically is considered to be reasonable.

This study of vertical tooth movement demonstrated that the maximum cervical margin stress in the periodontal ligament was 0·0046 N/mm², whilst the highest apical stress was 0·00205 N/mm² when intrusive and extrusive forces of 1 Newton were applied to the buccal surface of the crown of a tooth model. These stresses were evaluated in the light of previous studies and found to be within the suggested clinical optimum level. However, the periodontal stress distribution following orthodontic loading within this three-dimensional finite element model was found to be highly complex.     

Biology of the estrogen receptor,GPR30, in triple negative breast cancer

Background

Triple-negative (TN) breast cancer lacks a known signaling pathway amenable to targeted therapy. The authors hypothesized that the G protein–coupled receptor GPR30 may be present in TN breast cancer and serve a role for tumor growth.

Methods

A retrospective pathology study and chart review were conducted. All patients aged ≤49 years from 2000 to 2008 were included (n = 24). Concurrent patients aged ≥50 years were randomly selected. Paraffin sections were stained for GPR30 and reviewed by a pathologist blinded to estrogen receptor and progesterone receptor status. Disease-free survival was analyzed versus age and receptor status. Means were compared using 2-sample t tests and proportions using chi-square analysis.

Results

Twenty-seven patients tested GPR30 positive and 21 GPR30 negative. Seventeen of 18 TN cancers tested positive for GPR30 (P < .0001). Recurrence at a mean follow-up of 36 months was 22.2% in the GPR30-positive group and 9.5% in the GPR30-negative group.

Conclusions

GPR30 is prevalent in TN breast cancer and associated with young age and possibly recurrence.     

Postoperative fluid collections after colon resection: the utility of clinical assessment

Background

Computed tomography (CT) scans often identify postoperative fluid collections of uncertain clinical relevance.

Methods

Consecutive adult patients undergoing colorectal resection and postoperative CT scan from January 1, 2000 to December 31, 2008, at a university teaching hospital were identified from a prospective database. A host of clinical and CT findings were recorded. Fisher's exact test and logistic regression with univariate and multivariate analysis were used to assess the predictive value of clinical and radiologic variables.

Results

Nine hundred six patients had a colon resection during the study period. Fifty-four patients had a postoperative fluid collection, of which 36 were found to be abscesses. Only high clinical suspicion of an abscess predicted the presence of an abscess (P = .009); of the radiologic criteria, only proximity to the anastomosis was predictive (P = .05).

Conclusions

Clinical judgment is superior to radiologic and individual clinical parameters. This finding has the potential to prevent many unnecessary procedures.     

CCN2 is transiently expressed by keratinocytes during re-epithelialization and regulates keratinocyte migration in vitro by the ras-MEK-ERK signaling pathway

Background

CCN2 (previously known as connective tissue growth factor) is a multifunctional matricellular protein that has numerous effects on cell life and cell interactions with the connective tissue. Although the importance of CCN2 for the fibrotic process in wound healing has been well studied, the involvement of CCN2 in keratinocyte function has not yet been explored. Therefore, the aim of the present study was to investigate the role of CCN2 in the epidermis during wound healing.

Materials and methods

Immunohistochemistry was done on sections from full-thickness porcine wounds. The effect of CCN2 on the migration of cultured human keratinocytes exposed to scratch wounds, the effect on phosphorylation of extracellular signal-related kinases (ERK), and the effect of adding inhibitors to the ERK/mitogen-activated protein kinase pathway to human keratinocytes were studied.

Results

The CCN2 protein was transiently expressed in vivo at the leading keratinocyte edge during re-epithelialization of full-thickness porcine wounds. In vitro, exogenous addition of CCN2 to human keratinocyte cultures regulated keratinocyte migration and resulted in phosphorylation of ERK. The addition of inhibitors of ERK/mitogen-activated protein kinase counteracted the effect of CCN2 on migration.

Conclusions

CCN2 was transiently expressed at the leading keratinocyte edge in vivo. The biologic importance of this was supported in vitro, because CCN2 regulated human keratinocyte migration through activation of the Ras-mitogen-activated protein kinase kinase-ERK signal transduction pathway.     

A look at the thoracic surgery workforce in Canada: how demographics and scope of practice may impact future workforce needs

Background

The purpose of this study is to describe the demographics, training and practice characteristics of physicians performing thoracic surgery across Canada to better assess workforce needs.

Methods

We developed a questionnaire using a modified Delphi process to generate questionnaire items. The questionnaire was administered to all Canadian thoracic surgeons via email (n = 102) or mail (n = 35).

Results

In all, 97 surgeons completed the survey (71% response rate). The mean age of respondents was 47.7 (standard deviation 9.1) years; 10.3% were older than 60. Ninety respondents (88.7%) were men, 95 (81.1%) practised in English and 93 (76%) were born in Canada. Most (90.4%) had a medical school affiliation, with an equal proportion practising in community or university teaching hospitals. Only 18% of respondents reported working fewer than 60 hours per week, and 34% were on call more than 1 in 3. Three-quarters of work hours were devoted to clinical care, with the remaining time split among research, administration and teaching. Malignant lung disease accounted for 61.2% of practice time, with the remaining time equally split between benign and malignant thoracic diseases. Preoperative testing (49.4%) and insufficient operating time (49.5%) were the most common factors delaying delivery of care. More than 80% of respondents reported being satisfied with their careers, with 62.1% planning on retiring after age 60.

Conclusion

This survey characterizes Canadian thoracic surgeons by providing specific demographic, satisfaction and scope of practice information. Despite challenges in obtaining adequate resources for providing timely care, job satisfaction remains high, with a balanced workforce supply and demand anticipated for the foreseeable future.     

Get Up, Get Out, Get Moving: An Interactive Tool for Education at Your Local School

Background

Childhood obesity is a growing problem in America. Orthopaedic surgeons have an opportunity to interact with communities to educate children about healthy eating and physical activity. The American Academy of Orthopedic Surgeons (AAOS) Leadership Fellows Program [1] Class of 2012 created a presentation for AAOS members to bring to local schools. The goal was to teach the children about the potential complications of childhood obesity and the benefits of healthy living.

Questions/purposes

We describe a program in which orthopaedic surgeons gave presentations to elementary school students about healthy eating and activity and the effects that extra weight can have on their bones.

Methods

Each of the five members of the Leadership Fellows Program [1] 2012 class (JW, EM, MP, MR, MF) presented to a school in his or her hometown. The program was presented to 210 fifth grade children throughout the country. Before and after the presentation, students took a six-question multiple-choice quiz and answers compared to assess improvement in knowledge.

Results

The average number of answers correct before the presentation was 4.5 out of six, and the average after the presentation was six of six. The presentations were well received, and the students and their teachers invited each presenter back the next year.

Conclusions

The improvement in quiz scores demonstrated interest among the students in that they paid attention and understood the content. The children appeared enthusiastic to learn about this subject, and the schools were enthusiastic to include the curriculum.