Work hour restrictions: impact on neurosurgical resident training at the University of Utah

Journal ArticleResident work hour restrictions imposed by the Accreditation Council for Graduate Medical Education became effective on July 1, 2003. To evaluate the effect of these regulations on resident operative experience, we reviewed and compared the surgical experience of junior and senior neurosurgical residents four years before and one year after the ACGME restrictions were implemented. Resident work hours since May 2003 and operative caseload during the study period were recorded in commercially available data systems. The mean number of hours worked per week by junior and chief residents decreased f r om 104 and 110 hours before the ACGME work hour restrictions to 81 and 84 hours afterward, respectively. During the four academic years before the work hour limitations took effect, the mean number of major cases performed each year was 802.5 for the chief residents and 849.3 for t he junior residents. Following the restrictions, little changed for t he chief residents. However, the junior residents averaged only 467 cases, a 45 percent decrease f r om t he previous years studied. The mean number of cases covered by each junior resident per month decreased by 30.5 percent after the work hour restrictions were instituted, and the mean number of cases covered per post-call junior resident in one month declined 47.8 percent, from 23 to 12. At our institution, the ACGME work hour restrictions have resulted in decreased resident work hours for all residents at t he expense of the operative experience for junior residents. The operative caseload for chief residents has not been affected

Sporadic osteochondroma of the cervical spine

Journal ArticleOsteochondroma is the most common benign tumor of bone, but axial skeleton involvement is uncommon and usually indicates a hereditary cause such as osteochondromatosis (hereditary multiple exostosis). 1 Approximately 7% of hereditary osteochondromas occur along the vertebral column, which is double the rate of vertebral column occurrences among sporadic cases.4 We present a rare pediatric case of a large sporadic osteochondroma arising from the C-3 lamina. A previously healthy 13-year-old girl with no family history of osteochondroma noticed a posterior neck mass that continued to enlarge over the following year. On examination, the mass was readily visible and nontender to palpation. The patient denied clumsiness of the hands or feet, paresthesias, or neck pain. No motor weakness, sensory disturbance, or hyperreflexia was noted. A lateral plain radiograph demonstrated a calcified mass arising dorsally from the posterior elements of the cervical spine between C-2 and C-4 (Fig. 1). Computerized tomography (CT) scans revealed that the mass was arising from the lamina of C-3 with bone remodeling of the C-2 and C-4 laminae (Fig. 2). Magnetic resonance imaging demonstrated a large multilobulated, cystic, and irregularly enhancing mass with calcified components, measuring 5.8 3 5.5 3 8.7 cm and causing mild cord compression at C3?4 (Fig. 2). The differential diagnosis for this rapidly growing spinal bone lesion included osteochondroma, osteoblastoma, osteosarcoma, and chondrosarcoma. The patient underwent a complete resection via a posterior midline cervical incision. At surgery, the tumor appeared lobulated, well-circumscribed, firm, and calcified (Fig. 3). The tumor and the C-3 lamina were removed. The results of a pathological examination were consistent with an osteochondroma. The postoperative CT scan demonstrated a gross-total resection with stable sagittal alignment

Efficacy of noninvasive cardiac imaging tests in diagnosis and management of stable coronary artery disease

Ify R Mordi,1,2 Athar A Badar,2 R John Irving,2 Jonathan R Weir-McCall,1 J Graeme Houston,1 Chim C Lang1,2 1Division of Molecular and Clinical Medicine, University of Dundee, Dundee, UK; 2Department of Cardiology, Ninewells Hospital and Medical School, Dundee, UK Abstract: The aim of this review was to discuss the current literature regarding the utility of noninvasive imaging in diagnosis and management of stable coronary artery disease (CAD) including recent data from large randomized trials assessing diagnosis and prognosis. Current guidelines recommend revascularization in patients with refractory angina and in those with potential prognostic benefit. Appropriate risk stratification through noninvasive assessment is important in ensuring patients are not exposed to unnecessary invasive coronary angiograms. The past 20 years have seen an unprecedented expansion in noninvasive imaging modalities for the assessment of stable CAD, with cardiovascular magnetic resonance and computed tomography complementing established techniques such as myocardial perfusion imaging, echocardiography and exercise electrocardiogram. In this review, we examine the current state-of-the-art in noninvasive imaging to provide an up-to-date analysis of current investigation and management options. Keywords: angina, noninvasive imaging, SPECT, stress echo, cardiovascular magnetic resonance, CT coronary angiograph

QED for a Fibrillar Medium of Two-Level Atoms

We consider a fibrillar medium with a continuous distribution of two-level atoms coupled to quantized electromagnetic fields. Perturbation theory is developed based on the current algebra satisfied by the atomic operators. The one-loop corrections to the dispersion relation for the polaritons and the dielectric constant are computed. Renormalization group equations are derived which demonstrate a screening of the two-level splitting at higher energies. Our results are compared with known results in the slowly varying envelope and rotating wave approximations. We also discuss the quantum sine-Gordon theory as an approximate theory.Comment: 32 pages, 4 figures, uses harvmac and epsf. In this revised version, infra-red divergences are more properly handle

Braggoriton--Excitation in Photonic Crystal Infiltrated with Polarizable Medium

Light propagation in a photonic crystal infiltrated with polarizable molecules is considered. We demonstrate that the interplay between the spatial dispersion caused by Bragg diffraction and polaritonic frequency dispersion gives rise to novel propagating excitations, or braggoritons, with intragap frequencies. We derive the braggoriton dispersion relation and show that it is governed by two parameters, namely, the strength of light-matter interaction and detuning between the Bragg frequency and that of the infiltrated molecules. We also study defect-induced states when the photonic band gap is divided into two subgaps by the braggoritonic branches and find that each defect creates two intragap localized states inside each subgap.Comment: LaTeX, 8 pages, 5 figure

Effect of deposit feeders on migration of 137Cs in lake sediments

Illite clay particles with adsorbed 137Cs were added as a submillimeter layer to the surface of silt-clay sediments contained in rectangular Plexiglas cells stored in a temperature-regulated aquarium, in order to trace the effect of the oligochaete, Tubifex tubifex, and the amphipod, Pontoporeia hoyi, on mass redistribution near the sediment-water interface. A well-collimated NaI gamma detector scanned each sediment column (~10 cm deep) at daily or weekly intervals for six months, depicting the time evolution of radioactivity with and without added benthos. In a cell with tubificids (~5 x 104 m-2), which feed below 3 cm and defecate on surface sediments, the labeled layer was buried at a rate of 0.052 +/- 0.007 cm/day (20[deg]C). When labeled particles entered the feeding zone, 137Cs reappeared in surface sediments creating a bimodal activity profile. In time, the activity tended toward a uniform distribution over the upper 6 cm, decreasing exponentially below to undetectable levels by 9 cm. In a cell with amphipods (~1.6 x 104 m-2) uniform activity developed rapidly (~17 days) down to a well-defined depth (1.5 cm). The mixing of sediments by Pontoporeia is described by a simple quantitative model of eddy diffusive mixing of sediment solids. The value of the diffusion coefficient, 4.4 cm2/yr (7[deg]C) was computed from a least squares fit of theoretical to observed profile broadening over time. In a cell without benthos, small but measurable migration of 137Cs indicated an effective molecular diffusion coefficient of 0.02 cm2/yr.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23642/1/0000606.pd

Assessment of a size-based method for enriching circulating tumour cells in colorectal cancer

Circulating tumour cells (CTC) from solid tumours are a prerequisite for metastasis. Isolating CTCs and understanding their biology is essential for developing new clinical tests and precision oncology. Currently, CellSearch is the only FDA (U.S. Food and Drug Administration)-approved method for CTC enrichment but possesses several drawbacks owing to a reliance on the epithelial cell adhesion molecule (EpCAM) and a resource-intensive nature. Addressing these shortcomings, we optimised an existing size-based method, MetaCell, to enrich CTCs from blood of colorectal cancer (CRC) patients. We evaluated the ability of MetaCell to enrich CTCs by spiking blood with CRC cell lines and assessing the cell recovery rates and WBC depletion via immunostaining and gene expression. We then applied MetaCell to samples from 17 CRC patients and seven controls. Recovery rates were \u3e85% in cell lines, with \u3e95% depletion in WBCs. MetaCell yielded CTCs and CTC clusters in 52.9% and 23.5% of the patients, respectively, without false positives in control patients. CTCs and cluster detection did not correlate with histopathological parameters. Overall, we demonstrated that the MetaCell platform enriched CRC cells with high recovery rates and high purity. Our pilot study also demonstrated the ability of MetaCell to detect CTCs in CRC patients

Imaging in Vascular Access

This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is the most commonly used modality in VA because it is cheaper (relative to other modalities), accessible, non-ionising, and does not require the use of contrast agents. DSA is predominantly only performed when an intervention is indicated. MRI is limited by its cost and the time required for image acquisition that mainly confines it to the realm of research where high resolution is required. CT’s short acquisition times and high resolution make it useful as a problem-solving tool in complex cases, although accessibility can be an issue. All four imaging modalities have advantages and disadvantages that limit their use in this particular patient cohort. Current imaging in VA comprises an integrated approach with each modality providing particular uses dependent on their capabilities. MRI and CT, which currently have limited use, may have increasingly important future roles in complex cases where detailed analysis is required

Optodynamic simulation of β-adrenergic receptor signalling

Optogenetics has provided a revolutionary approach to dissecting biological phenomena. However, the generation and use of optically active GPCRs in these contexts is limited and it is unclear how well an opsin-chimera GPCR might mimic endogenous receptor activity. Here we show that a chimeric rhodopsin/β(2) adrenergic receptor (opto-β(2)AR) is similar in dynamics to endogenous β(2)AR in terms of: cAMP generation, MAP kinase activation and receptor internalization. In addition, we develop and characterize a novel toolset of optically active, functionally selective GPCRs that can bias intracellular signalling cascades towards either G-protein or arrestin-mediated cAMP and MAP kinase pathways. Finally, we show how photoactivation of opto-β(2)AR in vivo modulates neuronal activity and induces anxiety-like behavioural states in both fiber-tethered and wireless, freely moving animals when expressed in brain regions known to contain β(2)ARs. These new GPCR approaches enhance the utility of optogenetics and allow for discrete spatiotemporal control of GPCR signalling in vitro and in vivo