Automatic Computation of Left Ventricular Volume Changes Over a Cardiac Cycle from Echocardiography Images by Nonlinear Dimensionality Reduction

Curve of left ventricular (LV) volume changes throughout the cardiac cycle is a fundamental parameter for clinical evaluation of various cardiovascular diseases. Currently, this evaluation is often performed manually which is tedious and time consuming and suffers from significant interobserver and intraobserver variability. This paper introduces a new automatic method, based on nonlinear dimensionality reduction (NLDR) for extracting the curve of the LV volume changes over a cardiac cycle from two-dimensional (2-D) echocardiography images. Isometric feature mapping (Isomap) is one of the most popular NLDR algorithms. In this study, a modified version of Isomap algorithm, where image to image distance metric is computed using nonrigid registration, is applied on 2-D echocardiography images of one cycle of heart. Using this approach, the nonlinear information of these images is embedded in a 2-D manifold and each image is characterized by a symbol on the constructed manifold. This new representation visualizes the relationship between these images based on LV volume changes and allows extracting the curve of the LV volume changes automatically. Our method in comparison to the traditional segmentation algorithms does not need any LV myocardial segmentation and tracking, particularly difficult in the echocardiography images. Moreover, a large data set under various diseases for training is not required. The results obtained by our method are quantitatively evaluated to those obtained manually by the highly experienced echocardiographer on ten healthy volunteers and six patients which depict the usefulness of the presented method.     

Leadership Identity Development Through Reflection and Feedback in Team-Based Learning Medical Student Teams

Problem: Studies on leadership identity development through reflection with Team-Based Learning (TBL) in medical student education are rare. We assumed that reflection and feedback on the team leadership process would advance the progression through leadership identity development stages in medical students within the context of classes using TBL. Intervention: This study is a quasi-experimental design with pretest–posttest control group. The pretest and posttest were reflection papers of medical students about their experience of leadership during their TBL sessions. In the intervention group, TBL and a team-based, guided reflection and feedback on the team leadership process were performed at the end of all TBL sessions. In the other group, only TBL was used. The Stata 12 software was used. Leadership Identity was treated both as a categorical and quantitative variable to control for differences in baseline and gender variables. Chi-square, t tests, and linear regression analysis were performed. Context: The population was a cohort of 2015–2016 medical students in a TBL setting at Tehran University of Medical Sciences, School of Medicine. Teams of four to seven students were formed by random sorting at the beginning of the academic year (intervention group n = 20 teams, control group n = 19 teams). Outcome: At baseline, most students in both groups were categorized in the Awareness and Exploration stage of leadership identity: 51 (52%) in the intervention group and 59 (55%) in the control group: uncorrected χ²(3) = 15.6, design-based F(2.83, 108) = 4.87, p = .003. In the posttest intervention group, 36 (36%) were in exploration, 33 (33%) were in L-identified, 20 (20%) were in Leadership Differentiated, and 10 (10%) were in the Generativity. None were in the Awareness or Integration stages. In the control group, 3 (20%) were in Awareness, 56 (53%) were in Exploration, 35 (33%) were in Leader Identified, 13 (12%) were in Leadership Differentiated. None were in the Generativity and Integration stages. Our hypothesis was supported by the data: uncorrected χ²(4) = 18.6, design-based F(3.77, 143) = 4.46, p = .002. The mean of the leadership identity in the pretest, intervention group equaled 1.93 (SD = 0.85) and the pretest, control group mean was 2.36 (SD = 0.86), p = .004. The mean of the posttest, intervention group was 3.04 (SD = 0.98) and posttest, control group mean was 2.54 (SD = 0.74), T = ?4.00, design df = 38, p < .001, and adjusted on baseline and gender T = ?8.97, design df = 38, p < .001. Lessons Learned: Reflection and feedback on the team leadership process in TBL advances the progression in stages of leadership identity development in medical students. Although the TBL strategy itself could have an impact on leadership identity development, this study demonstrates that when a reflection and feedback on leadership intervention are added, there is much greater impact.     

Tumor-resident adenosine-producing mesenchymal stem cells as a potential target for cancer treatment

Clinical and Experimental Medicine - The development of new therapies based on tumor biology is one of the main topics in cancer treatment.&nbsp;In this regard, investigating the...     

Mechanism of mast cell adhesion to human tenocytes in vitro

Mast cells and fibroblasts are two key players involved in many fibrotic and degenerative disorders. In the present study we examined the nature of binding interactions between human mast cells and tendon fibroblasts (tenocytes). In the mast cell‐fibroblast co‐culture model, mast cells were shown to spontaneously bind to tenocytes, in a process that was partially mediated by α5β1 integrin receptors. The same receptors on mast cells significantly mediated binding of these cells to tissue culture plates in the presence of tenocyte‐conditioned media; the tenocyte‐derived fibronectin in the media was shown to also play a major role in these binding activities. Upon binding to tenocytes or tissue culture plates, mast cells acquired an elongated phenotype, which was dependent on α5β1 integrin and tenocyte fibronectin. Additionally, tenocyte‐derived fibronectin significantly enhanced mRNA expression of the adhesion molecule, THY1, by mast cells. Our data suggests that α5β1 integrin mediates binding of mast cells to human tenocyte and to tenocyte‐derived ECM proteins, in particular fibronectin. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:9–16, 2015.

     

From the Cover: Warming enabled upslope advance in western US forest fires

Increases in burned area and large fire occurrence are widely documented over the western United States over the past half century. Here, we focus on the elevational distribution of forest fires in mountainous ecoregions of the western United States and show the largest increase rates in burned area above 2,500 m during 1984 to 2017. Furthermore, we show that high-elevation fires advanced upslope with a median cumulative change of 252 m (−107 to 656 m; 95% CI) in 34 y across studied ecoregions. We also document a strong interannual relationship between high-elevation fires and warm season vapor pressure deficit (VPD). The upslope advance of fires is consistent with observed warming reflected by a median upslope drift of VPD isolines of 295 m (59 to 704 m; 95% CI) during 1984 to 2017. These findings allow us to estimate that recent climate trends reduced the high-elevation flammability barrier and enabled fires in an additional 11% of western forests. Limited influences of fire management practices and longer fire-return intervals in these montane mesic systems suggest these changes are largely a byproduct of climate warming. Further weakening in the high-elevation flammability barrier with continued warming has the potential to transform montane fire regimes with numerous implications for ecosystems and watersheds.

Fire is an integral component of most forested lands and provides significant ecological services (1). However, burned area, fire size, the number of large fires, and the length of fire season have increased in the western United States in recent decades (2, 3). Increasing fire activity and the expansion of wildland urban interface (4) collectively amplified direct and indirect fire-related loss of life and property (5, 6) and contributed to escalating fire suppression costs (7). While increased biomass due to a century of fire exclusion efforts is hypothesized to have partially contributed to this trend (8), climate change is also implicated in the rise of fire activity in the western United States (9–11).Although increases in forest fire activity are evident in all major forested lands in the western United States (2, 12, 13), an abundance of moisture—due to snowpack persistence, cooler temperatures, and delayed summer soil and fuel drying—provides a strong buffer of fire activity (13) and longer fire-return intervals (14) at high elevations. Recent studies, however, point to changing fire characteristics across many ecoregions of the western United States (15), including high-elevation areas of the Sierra Nevada (16), Pacific Northwest, and Northern Rockies (12, 17). These studies complement documented changes in montane environments including amplified warming with elevation (18), widespread upward elevational shift in species (19), and increased productivity in energy-limited high-elevation regions that enhance fuel growth and connectivity (20). These changes have been accompanied by longer snow-free periods (21), increased evaporative demand (9), and regional declines in fire season precipitation frequency (11) across the western United States promoting increased fuel ignitability and flammability that have well-founded links to forest burned area. A warmer climate is also conducive to a higher number of convective storms and more frequent lightning strikes (22).In this study, we explore changes in the elevational distribution of burned forest across the western United States and how changes in climate have affected the mesic barrier for high-elevation fire activity. We focus on changes in high-elevation forests that have endured fewer direct anthropogenic modifications compared to drier low-elevation forests that had frequent low-severity fires prior to European colonization and have been more subject to changes in settlement patterns as well as fire suppression and harvest (23, 24); we also pose the following questions: 1) Has the elevational distribution of fire in the western US forests systematically changed? and 2) What changes in biophysical factors have enabled such changes in high-elevation fire activity? We explore these questions across 15 mountainous ecoregions of the western United States using records from large fires (>405 ha) between 1984 and 2017 [Monitoring Trends in Burn Severity (MTBS) (25)], a 10-m–resolution digital elevation model, and daily high-spatial–resolution surface meteorological data [gridMET (26)].We focus on the trends in Z₉₀—defined as the 90th percentile of normalized annual elevational distribution of burned forest in each ecoregion. Here, the term “normalized” essentially refers to the fraction of forest area burned by elevation. We complement this analysis by examining trends in burned area by elevational bands and using quantile regression of normalized annual forest fire elevation. We then assess the interannual relationships between Z₉₀ and vapor pressure deficit (VPD) and compare the upslope advance in montane fire to elevational climate velocity of VPD during 1984 to 2017. Specifically, we use VPD trends and VPD–high-elevation fire regression to estimate VPD-driven changes in Z₉₀ and BA₉₀— defined as annual burned area above the 90th percentile of forest elevational distribution in each ecoregion—during 1984 to 2017.     

Pulmonary and extra-pulmonary manifestations of sarcoidosis

Background:

Sarcoidosis is a systemic multi-organ granulomatous disease of unknown etiology that is characterized by the presence of granuloma in various organs. The clinical features of sarcoidosis are heterogeneous but pulmonary involvement is cardinal manifestations. The aim of this study was to determine radiologic, clinical and laboratory findings of patients with sarcoidosis.

Patients and Methods:

In a cross-sectional study, all patients visiting sarcoidosis clinic were enrolled in the study. Computed tomography (CT) scan was obtained and lab exams were obtained from patient and reports were recorded in data sheet.

Results:

Total of 55 patients with sarcoidosis were enrolled in the study. The average of age was 44.6 (range 25-62) years. Thirty-seven patients were male and 18 were female. The most common extra-pulmonary manifestation was arthritis (in 18% of cases) and then lupus pernio (12.8%) and uveitis (10.9%). Bilateral hilar adenopathy and para tracheal lymphadenopathy was observed in 39(70%) and 22 (40%) of patients. Parenchymal nodules (30%), bronchiectasia (25%), ground-glass opacification (18%) were the most common findings. Percentages of patients with dyspnea were 29% and percentages of patients with cough were 21%. Among abnormal lab tests, high urine calcium (Ca) were positive in 21% and high angiotensin-converting enzyme (ACE) in 16% of patients.

Conclusion:

Pulmonary involvements are both fibrosis and granulomatosis and the most common manifestations are parenchymal nodules, bronchiectasia and high-grade fibrosis. The most common extra-pulmonary involvement is arthritis. Lab tests are non-specific and have no correlation with duration or severity of disease.     

Optimal β-blocker for prevention of atrial fibrillation after on-pump coronary artery bypass graft surgery: Carvedilol versus metoprolol

BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass graft (CABG) surgery. It has been shown that prophylactic oral beta-blocker administration reduces the incidence of post-CABG AF. However, the optimal beta-blocker has not been identified. OBJECTIVE: This study sought to determine whether oral carvedilol (with its unique anti-inflammatory and antioxidant properties) is more effective than oral metoprolol for prevention of AF after CABG surgery. METHODS: Between April 2006 and December 2006, 120 patients (63 men, mean age 61 +/- 9.4 years) who were scheduled to undergo their first on-pump CABG were enrolled in this study. The patients were randomized in a prospective 1:1 manner to receive either oral carvedilol (n = 60) or oral metoprolol (n = 60). The end point of the study was the occurrence of the new-onset AF during the first 5 days after CABG. RESULTS: AF occurred in 29 of 120 patients (24.0%). The incidence of postoperative AF was 15.0% (9 of 60) in the carvedilol group and 33% (20 of 60) in the metoprolol group (P = .022). The carvedilol group was treated with mean daily dose of 46 +/- 9 mg and metoprolol group with mean daily dose of 93 +/- 11 mg. There were no differences between the study groups regarding any known preoperative, perioperative, or postoperative characteristics (all values were P >.05). No significant adverse effect was observed in either group. CONCLUSION: This prospective study suggested that oral carvedilol is more effective than oral metoprolol in the prevention of AF after on-pump CABG. It is well tolerated when started before and continued after the surgery. However, further prospective studies are needed to clarify this issue.     

Prevalence of fasciolosis and dicrocoeliosis in slaughtered sheep and goats in Amol Abattoir,Mazandaran, northern Iran

Objective

The liver flukes, Fasciola spp. and Dicrocoelium dendriticum, infect ruminants and other mammalian extensively and cause major diseases of livestock that produce considerable economic losses.

Methods

A survey of 2391 sheep and goats slaughtered at an abattoir in Amol region, northern Iran was used to determine the prevalence of the liver flukes infection based on season, sex and specie of the animals.

Results

The results revealed that the prevalence rate of Fasciola spp. and Dicrocoelium dendriticum was 6.6% and 4.3% respectively. Dicrocoeliosis was more dominant in female animals (7.1%) whereas there was no sex-related difference in the prevalence of Fasciola spp. in male and female animals. Furthermore, Fasciolosis was significantly more prevalent than dicrocoeliosis in both sheep and goats. The Seasonal prevalence of Fasciola spp. was highest (P<0.005) during spring (8.3%) followed in order by autumn (8.1%), winter (5.9%) and summer (4.0%) but Dicrocoeliosis did not follow any seasonal pattern.

Conclusions

According to this study, it can be concluded that Amol is regarded as an endemic region for Fasciola spp and D. dandriticum infection. Moreover, Fasciola spp. is the most widespread liver fluke found in sheep and goats which is more dominant in sheep than goats.     

A case report of T cell prolymphocytic leukemia and Kaposi sarcoma and a review of T cell prolymphocytic leukemia

T cell prolymphocytic leukemia (T-PLL) is a rare mature T cell lymphoproliferative disease. It has been associated with an aggressive course, a poor response to conventional chemotherapy and a short median survival. Here we present a rare case of concurrent T-PLL and Kaposi sarcoma who achieved a complete hematologic and cytogenetic remission after a very short course of treatment with alemtuzumab. A review of T-PLL was done. In this review, clinical features, laboratory features and current therapeutic strategies of T-PLL are presented.