Three-dimensional reproducibility of natural head position.

INTRODUCTION: Although natural head position has proven to be reliable in the sagittal plane, with an increasing interest in 3-dimensional craniofacial analysis, a determination of its reproducibility in the coronal and axial planes is essential. This study was designed to evaluate the reproducibility of natural head position over time in the sagittal, coronal, and axial planes of space with 3-dimensional imaging. METHODS: Three-dimensional photographs were taken of 28 adult volunteers (ages, 18-40 years) in natural head position at 5 times: baseline, 4 hours, 8 hours, 24 hours, and 1 week. Using the true vertical and horizontal laser lines projected in an iCAT cone-beam computed tomography machine (Imaging Sciences International, Hatfield, Pa) for orientation, we recorded references for natural head position on the patient's face with semipermanent markers. By using a 3-dimensional camera system, photographs were taken at each time point to capture the orientation of the reference points. By superimposing each of the 5 photographs on stable anatomic surfaces, changes in the position of the markers were recorded and assessed for parallelism by using 3dMDvultus (3dMD, Atlanta, Ga) and software (Dolphin Imaging & Management Solutions, Chatsworth, Calif). RESULTS: No statistically significant differences were observed between the 5 time points in any of the 3 planes of space. However, a statistically significant difference was observed between the mean angular deviations of 3 reference planes, with a hierarchy of natural head position reproducibility established as coronal > axial > sagittal. CONCLUSIONS: Within the parameters of this study, natural head position was found to be reproducible in the sagittal, coronal, and axial planes of space. The coronal plane had the least variation over time, followed by the axial and sagittal planes.

Utilizing the Regional Acceleratory Phenomenon and Dental Implant Anchorage for Distalization and Intrusion of a Mesially Tipped Mandibular Molar: A Case Report.

INTRODUCTION: Introduction of a surgical insult in conjunction with orthodontic therapy has been shown to accelerate treatment in minor tooth movement and comprehensive orthodontic cases by induction of the regional acceleratory phenomenon (RAP). When applying this concept to a molar tipped into an adjacent edentulous site, a dental implant can be planned to anchor the movement. CASE PRESENTATION: A generally and periodontally healthy 25-year-old patient presented missing tooth #19, with tooth #18 mesially tipped into the first molar crown space. A dental implant was placed in the #19 position. Following osseointegration, the implant anchored orthodontic movement of the adjacent tooth, which was initiated in conjunction with third molar extraction. CONCLUSION: Favorable biomechanics for molar uprighting can be achieved using an osseointegrated implant and a customized orthodontic device. The presented technique facilitates implant site development without delaying placement of the fixture and simplifies fabrication of a harmonious and anatomic implant-supported restoration. Induction of the RAP may hasten treatment completion.

Correction to: Phylogenetic Insight into Zika and Emerging Viruses for a Perspective on Potential Hosts.

The article Phylogenetic Insight into Zika and Emerging Viruses for a Perspective on Potential Hosts, written by Diana S. Weber, Karen A. Alroy, and Samuel M. Scheiner, was originally published Online First without open access.

Phylogenetic Insight into Zika and Emerging Viruses for a Perspective on Potential Hosts.

Global viral diversity is substantial, but viruses that contribute little to the public health burden or to agricultural damage receive minimal attention until a seemingly unimportant virus becomes a threat. The Zika virus (ZIKV) illustrated this, as there was limited information and awareness of the virus when it was identified as a public health emergency in February 2016. Predicting which virus may pose a future threat is difficult. This is in part because significant knowledge gaps in the basic biology and ecology of an emerging virus can impede policy development, delay decision making, and hinder public health action. We suggest using a phylogenetic framework of pathogens and their infected host species for insight into which animals may serve as reservoirs. For example, examining flaviviruses closely related to ZIKV, the phylogenetic framework indicates New World monkeys are the most likely candidates to be potential reservoirs for ZIKV. Secondarily, mammals that are in close proximity to humans should be considered because of the increased opportunity for pathogen exchange. The increase in human-mediated environmental change is accelerating the probability of another previously overlooked virus becoming a significant concern. By investing in basic science research and organizing our knowledge into an evolutionary framework, we will be better prepared to respond to the next emerging infectious disease.

Laparoscopic surgery: an excellent approach in elderly patients.

HYPOTHESIS: A review of the literature will show that laparoscopy is safe and effective for the treatment of surgical diseases in elderly patients. DATA SOURCES: An electronic search using the PubMed and MEDLINE databases was performed using the term laparoscopy in elderly patients. Literature published in the English language in the past decade was reviewed. Pertinent references from articles and books not identified by the search engines were also retrieved. Relevant surgical textbooks were also reviewed. STUDY SELECTION: All relevant studies that could be obtained regardless of the study design were included. DATA EXTRACTION: All studies that contained material applicable to the topic were considered. Data on patient characteristics and surgical outcomes were abstracted. DATA SYNTHESIS: Sixteen studies evaluated laparoscopic cholecystectomy in the elderly. Compared with open cholecystectomy, elderly patients undergoing the laparoscopic procedure had a lower incidence of complications and a shorter hospitalization. In the 4 studies reporting the results of laparoscopic antireflux surgery in the elderly, the morbidity, mortality, and length of hospital stay were similar to those of younger patients. The elderly had equally good postoperative symptom relief. Ten reports of laparoscopic colon resection in the elderly demonstrated earlier return of bowel function, shorter hospitalization, and less cardiopulmonary morbidity. CONCLUSIONS: Despite underlying comorbidities, individuals older than 65 years tolerate laparoscopic procedures extremely well. Complications and hospitalization are lower than in open procedures. Surgeons need to inform primary care physicians of the excellent result of laparoscopic procedures in the elderly to encourage earlier referrals.

Extensive sampling of polar bears (Ursus maritimus) in the Northwest Passage (Canadian Arctic Archipelago) reveals population differentiation across multiple spatial and temporal scales.

As global warming accelerates the melting of Arctic sea ice, polar bears (Ursus maritimus) must adapt to a rapidly changing landscape. This process will necessarily alter the species distribution together with population dynamics and structure. Detailed knowledge of these changes is crucial to delineating conservation priorities. Here, we sampled 361 polar bears from across the center of the Canadian Arctic Archipelago spanning the Gulf of Boothia (GB) and M'Clintock Channel (MC). We use DNA microsatellites and mitochondrial control region sequences to quantify genetic differentiation, estimate gene flow, and infer population history. Two populations, roughly coincident with GB and MC, are significantly differentiated at both nuclear (F ST = 0.01) and mitochondrial (ΦST = 0.47; F ST = 0.29) loci, allowing Bayesian clustering analyses to assign individuals to either group. Our data imply that the causes of the mitochondrial and nuclear genetic patterns differ. Analysis of mtDNA reveals the matrilineal structure dates at least to the Holocene, and is common to individuals throughout the species' range. These mtDNA differences probably reflect both genetic drift and historical colonization dynamics. In contrast, the differentiation inferred from microsatellites is only on the scale of hundreds of years, possibly reflecting contemporary impediments to gene flow. Taken together, our data suggest that gene flow is insufficient to homogenize the GB and MC populations and support the designation of GB and MC as separate polar bear conservation units. Our study also provide a striking example of how nuclear DNA and mtDNA capture different aspects of a species demographic history.

Gene flow on ice: the role of sea ice and whaling in shaping Holarctic genetic diversity and population differentiation in bowhead whales (Balaena mysticetus).

Sea ice is believed to be a major factor shaping gene flow for polar marine organisms, but it remains unclear to what extent it represents a true barrier to dispersal for arctic cetaceans. Bowhead whales are highly adapted to polar sea ice and were targeted by commercial whalers throughout Arctic and subarctic seas for at least four centuries, resulting in severe reductions in most areas. Both changing ice conditions and reductions due to whaling may have affected geographic distribution and genetic diversity throughout their range, but little is known about range-wide genetic structure or whether it differed in the past. This study represents the first examination of genetic diversity and differentiation across all five putative stocks, including Baffin Bay-Davis Strait, Hudson Bay-Foxe Basin, Bering-Beaufort-Chukchi, Okhotsk, and Spitsbergen. We also utilized ancient specimens from Prince Regent Inlet (PRI) in the Canadian Arctic and compared them with modern stocks. Results from analysis of molecular variance and demographic simulations are consistent with recent and high gene flow between Atlantic and Pacific stocks in the recent past. Significant genetic differences between ancient and modern populations suggest PRI harbored unique maternal lineages in the past that have been recently lost, possibly due to loss of habitat during the Little Ice Age and/or whaling. Unexpectedly, samples from this location show a closer genetic relationship with modern Pacific stocks than Atlantic, supporting high gene flow between the central Canadian Arctic and Beaufort Sea over the past millennium despite extremely heavy ice cover over much of this period.

Major histocompatibility complex variation at three class II loci in the northern elephant seal.

Northern elephant seals were hunted to near extinction in the 19th century, yet have recovered remarkably and now number around 175,000. We surveyed 110 seals for single-strand conformation polymorphism (SSCP) and sequence variation at three major histocompatibility (MHC) class II loci (DQA, DQB and DRB) to evaluate the genetic consequences of the population bottleneck at these loci vs. other well-studied genes. We found very few alleles at each MHC locus, significant variation among breeding sites for the DQA locus, and linkage disequilibrium between the DQB and DRB loci. Northern elephant seals are evidently inbred, although there is as yet no evidence of correlative reductions in fitness.