The spindle shows remarkable diversity, and changes in an integrated fashion, as cells vary over evolution. Here, we provide a mechanistic explanation for variations in the first mitotic spindle in ...nematodes. We used a combination of quantitative genetics and biophysics to rule out broad classes of models of the regulation of spindle length and dynamics, and to establish the importance of a balance of cortical pulling forces acting in different directions. These experiments led us to construct a model of cortical pulling forces in which the stoichiometric interactions of microtubules and force generators (each force generator can bind only one microtubule), is key to explaining the dynamics of spindle positioning and elongation, and spindle final length and scaling with cell size. This model accounts for variations in all the spindle traits we studied here, both within species and across nematode species spanning over 100 million years of evolution.
The Society of Radiologists in Ultrasound convened a multidisciplinary panel of experts in the field of vascular ultrasonography (US) to come to a consensus regarding Doppler US for assistance in the ...diagnosis of carotid artery stenosis. The panel's consensus statement is believed to represent a reasonable position on the basis of analysis of available literature and panelists' experience. Key elements of the statement include the following: (a) All internal carotid artery (ICA) examinations should be performed with gray-scale, color Doppler, and spectral Doppler US. (b) The degree of stenosis determined at gray-scale and Doppler US should be stratified into the categories of normal (no stenosis), <50% stenosis, 50%-69% stenosis, > or =70% stenosis to near occlusion, near occlusion, and total occlusion. (c) ICA peak systolic velocity (PSV) and presence of plaque on gray-scale and/or color Doppler images are primarily used in diagnosis and grading of ICA stenosis; two additional parameters, ICA-to-common carotid artery PSV ratio and ICA end-diastolic velocity may also be used when clinical or technical factors raise concern that ICA PSV may not be representative of the extent of disease. (d) ICA should be diagnosed as (i) normal when ICA PSV is less than 125 cm/sec and no plaque or intimal thickening is visible; (ii) <50% stenosis when ICA PSV is less than 125 cm/sec and plaque or intimal thickening is visible; (iii) 50%-69% stenosis when ICA PSV is 125-230 cm/sec and plaque is visible; (iv) > or =70% stenosis to near occlusion when ICA PSV is greater than 230 cm/sec and visible plaque and lumen narrowing are seen; (v) near occlusion when there is a markedly narrowed lumen at color Doppler US; and (vi) total occlusion when there is no detectable patent lumen at gray-scale US and no flow at spectral, power, and color Doppler US. (e) The final report should discuss velocity measurements and gray-scale and color Doppler findings. Study limitations should be noted when they exist. The conclusion should state an estimated degree of ICA stenosis as reflected in the above categories. The panel also considered various technical aspects of carotid US and methods for quality assessment and identified several important unanswered questions meriting future research.
Purpose
To demonstrate proof‐of‐concept of a T2*‐sensitized oxygen‐enhanced MRI (OE‐MRI) method at 3T by assessing signal characteristics, repeatability, and reproducibility of dynamic lung OE‐MRI ...metrics in healthy volunteers.
Methods
We performed sequence‐specific simulations for protocol optimisation and acquired free‐breathing OE‐MRI data from 16 healthy subjects using a dual‐echo RF‐spoiled gradient echo approach at 3T across two institutions. Non‐linear registration and tissue density correction were applied. Derived metrics included percent signal enhancement (PSE), ∆R2* and wash‐in time normalized for breathing rate (τ‐nBR). Inter‐scanner reproducibility and intra‐scanner repeatability were evaluated using intra‐class correlation coefficient (ICC), repeatability coefficient, reproducibility coefficient, and Bland–Altman analysis.
Results
Simulations and experimental data show negative contrast upon oxygen inhalation, due to substantial dominance of ∆R2* at TE > 0.2 ms. Density correction improved signal fluctuations. Density‐corrected mean PSE values, aligned with simulations, display TE‐dependence, and an anterior‐to‐posterior PSE reduction trend at TE1. ∆R2* maps exhibit spatial heterogeneity in oxygen delivery, featuring anterior‐to‐posterior R2* increase. Mean T2* values across 32 scans were 0.68 and 0.62 ms for pre‐ and post‐O2 inhalation, respectively. Excellent or good agreement emerged from all intra‐, inter‐scanner and inter‐rater variability tests for PSE and ∆R2*. However, ICC values for τ‐nBR demonstrated limited agreement between repeated measures.
Conclusion
Our results demonstrate the feasibility of a T2*‐weighted method utilizing a dual‐echo RF‐spoiled gradient echo approach, simultaneously capturing PSE, ∆R2* changes, and oxygen wash‐in during free‐breathing. The excellent or good repeatability and reproducibility on intra‐ and inter‐scanner PSE and ∆R2* suggest potential utility in multi‐center clinical applications.
Evolution of minimally invasive bariatric surgery Gould, Jon C.; Needleman, Bradley J.; Ellison, E.Christopher ...
Surgery,
October 2002, 2002-Oct, 2002-10-00, 20021001, Volume:
132, Issue:
4
Journal Article
Peer reviewed
Background. Minimally invasive Roux-en-Y gastric bypass is a procedure that is being performed with increasing frequency. It is an advanced laparoscopic procedure with a steep learning curve. With ...experience, it can be performed in a reasonable amount of time with minimal morbidity. Methods. We first performed minimally invasive gastric bypass with the hand-assisted laparoscopic surgery (HALS) technique. After significant experience with HALS, we changed our approach to completely laparoscopic (LS). Our technique for all cases involves a circular stapled gastrojejunostomy with a 25-mm anvil passed transgastrically. Results. From June 1998 to January 2002, 304 patients underwent minimally invasive gastric bypass. Our first 81 cases were with HALS, and the rest were LS. The incidence of early major and minor perioperative complications for the entire series was 5.6% and 7.9%, respectively. Early reoperation (less than 30 days) was required in 4.6% of all patients. There was 1 leak (1.2%) in the HALS group and 4 anastomotic leaks (1.8%) in the LS group. Other measured outcomes were similar in each group with the exception of wound hernia (16% HALS vs 0.9% LS). Weight loss after 1 year was 44% for HALS and 56% for LS. We have not had any deaths in our series. Conclusions. HALS may have certain advantages in selected patients and early in a surgeon's experience with minimally invasive gastric bypass. With experience, good results are possible with either approach. (Surgery 2002;132:565-72.)
To demonstrate proof-of-concept of a T
*-sensitized oxygen-enhanced MRI (OE-MRI) method at 3T by assessing signal characteristics, repeatability, and reproducibility of dynamic lung OE-MRI metrics in ...healthy volunteers.
We performed sequence-specific simulations for protocol optimisation and acquired free-breathing OE-MRI data from 16 healthy subjects using a dual-echo RF-spoiled gradient echo approach at 3T across two institutions. Non-linear registration and tissue density correction were applied. Derived metrics included percent signal enhancement (PSE), ∆R
* and wash-in time normalized for breathing rate (τ-nBR). Inter-scanner reproducibility and intra-scanner repeatability were evaluated using intra-class correlation coefficient (ICC), repeatability coefficient, reproducibility coefficient, and Bland-Altman analysis.
Simulations and experimental data show negative contrast upon oxygen inhalation, due to substantial dominance of ∆R
* at TE > 0.2 ms. Density correction improved signal fluctuations. Density-corrected mean PSE values, aligned with simulations, display TE-dependence, and an anterior-to-posterior PSE reduction trend at TE
. ∆R
* maps exhibit spatial heterogeneity in oxygen delivery, featuring anterior-to-posterior R
* increase. Mean T
* values across 32 scans were 0.68 and 0.62 ms for pre- and post-O
inhalation, respectively. Excellent or good agreement emerged from all intra-, inter-scanner and inter-rater variability tests for PSE and ∆R
*. However, ICC values for τ-nBR demonstrated limited agreement between repeated measures.
Our results demonstrate the feasibility of a T
*-weighted method utilizing a dual-echo RF-spoiled gradient echo approach, simultaneously capturing PSE, ∆R
* changes, and oxygen wash-in during free-breathing. The excellent or good repeatability and reproducibility on intra- and inter-scanner PSE and ∆R
* suggest potential utility in multi-center clinical applications.
Venous ultrasound is the standard imaging test for patients suspected of having acute deep venous thrombosis (DVT). There is variability and disagreement among authoritative groups regarding the ...necessary components of the test. Some protocols include scanning the entire lower extremity, whereas others recommend scans limited to the thigh and knee supplemented with serial testing. Some protocols use gray-scale ultrasound alone, whereas others include Doppler interrogation. Point-of-care ultrasound is recommended in some settings, and there is heterogeneity of these protocols as well. Heterogeneity of recommendations can lead to errors including incorrect application of guidelines, confusion among requesting physicians, and incorrect follow-up. In October 2016, the Society of Radiologists in Ultrasound convened a multidisciplinary panel of experts to evaluate the current evidence to develop recommendations regarding ultrasound protocols for DVT and the terminology used to communicate results to clinicians. Recommendations were made after open discussion and by unanimous consensus.The panel recommends a comprehensive duplex ultrasound protocol from thigh to ankle with Doppler at selected sites rather than a limited or complete compression-only examination. This protocol is currently performed in many facilities and is achievable with standard ultrasound equipment and personnel. The use of these recommendations will increase the diagnosis of calf DVT and provide better data to explain the presenting symptoms. The panel recommends a single point-of-care protocol that minimizes underdiagnoses of proximal DVT.The panel recommends the term chronic postthrombotic change to describe the residual material that persists after the acute presentation of DVT to avoid potential overtreatment of prior thrombus.Adoption of a single standardized comprehensive duplex ultrasound and a single point-of-care examination will enhance patient safety and clinicians’ confidence.
Purpose
Dynamic lung oxygen‐enhanced MRI (OE‐MRI) is challenging due to the presence of confounding signals and poor signal‐to‐noise ratio, particularly at 3 T. We have created a robust pipeline ...utilizing independent component analysis (ICA) to automatically extract the oxygen‐induced signal change from confounding factors to improve the accuracy and sensitivity of lung OE‐MRI.
Methods
Dynamic OE‐MRI was performed on healthy participants using a dual‐echo multi‐slice spoiled gradient echo sequence at 3 T and cyclical gas delivery. ICA was applied to each echo within a thoracic mask. The ICA component relating to the oxygen‐enhancement signal was automatically identified using correlation analysis. The oxygen‐enhancement component was reconstructed, and the percentage signal enhancement (PSE) was calculated. The lung PSE of current smokers was compared with nonsmokers; scan–rescan repeatability, ICA pipeline repeatability, and reproducibility between two vendors were assessed.
Results
ICA successfully extracted a consistent oxygen‐enhancement component for all participants. Lung tissue and oxygenated blood displayed the opposite oxygen‐induced signal enhancements. A significant difference in PSE was observed between the lungs of current smokers and nonsmokers. The scan–rescan repeatability and the ICA pipeline repeatability were good.
Conclusion
The developed pipeline demonstrated sensitivity to the signal enhancements of the lung tissue and oxygenated blood at 3 T. The difference in lung PSE between current smokers and nonsmokers indicates a likely sensitivity to lung function alterations that may be seen in mild pathology, supporting future use of our methods in patient studies.
Morbid obesity precludes patients with end-stage heart failure from becoming cardiac transplant candidates. This study evaluates the safety and efficacy of laparoscopic sleeve gastrectomy (LSG) as a ...means to transplant candidacy in such patients.
Morbidly obese patients with end-stage heart failure, who were ineligible for cardiac transplantation and underwent LSG between 2008 and 2013, were reviewed retrospectively. Demographic characteristics, perioperative details, percentage of excess weight loss (%EWL), and status of transplant candidacy were analyzed.
Six patients (3 men) with end-stage heart failure and morbid obesity underwent LSG. Three patients (50%) had a left ventricular assist device (LVAD) in place at the time of surgery. Median age was 34 (31-66) years and mean preoperative body mass index (BMI) was 47.6±3.0 kg/m2. Median operative time was 90 (66-141) minutes, with a median length of stay of 7 (4-16) days. There were no perioperative deaths. One patient suffered a spontaneous flank hematoma. The same patient also had thrombosis of the LVAD pump at 3 weeks postoperatively, requiring an uneventful device exchange. At median follow-up of 22 (12-70) months, the mean %EWL was 51.4±10.3% with a decrease in BMI to 34.3±2.4 kg/m2 (P<.05). All patients had lost sufficient weight to become transplant eligible within 12 months of surgery. Two patients had undergone successful transplantation and another 2 were on the transplant list.
LSG appears to be a safe, technically feasible, and effective method for obtaining adequate weight loss in morbidly obese patients with end-stage heart failure and mechanical circulatory support, subsequently improving their access to cardiac transplantation. This is the largest case series to date of this high-risk group of patients undergoing LSG.
Background: Lead exposure shares many risk factors with delinquent behavior, and bone lead levels are related to self-reports of delinquent acts. No data exist as to whether lead exposure is higher ...in arrested delinquents. The goal of this study is to evaluate the association between lead exposure, as reflected in bone lead levels, and adjudicated delinquency.
Methods: This is a case-control study of 194 youths aged 12–18, arrested and adjudicated as delinquent by the Juvenile Court of Allegheny County, PA and 146 nondelinquent controls from high schools in the city of Pittsburgh. Bone lead was measured by K-line X-ray fluorescence (XRF) spectroscopy of tibia. Logistic regression was used to model the association between delinquent status and bone lead concentration. Covariates entered into the model were race, parent education and occupation, presence of two parental figures in the home, number of children in the home and neighborhood crime rate. Separate regression analyses were also conducted after stratification on race.
Results: Cases had significantly higher mean concentrations of lead in their bones than controls (11.0±32.7 vs. 1.5±32.1 ppm). This was true for both Whites and African Americans. The unadjusted odds ratio for a lead level ≥25 vs. <25 ppm was 1.9 (95% CL: 1.1–3.2). After adjustment for covariates and interactions and removal of noninfluential covariates, adjudicated delinquents were four times more likely to have bone lead concentrations >25 ppm than controls (OR=4.0, 95% CL: 1.4–11.1).
Conclusion: Elevated body lead burdens, measured by bone lead concentrations, are associated with elevated risk for adjudicated delinquency.
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