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Aim of study: This study evaluates the potential of the Google Earth Engine tool, supported by fine-scale information obtained by Unmanned Aerial Vehicle, to apply and characterize the dynamics of the successional stages of the Amazon Forest in the state of Rondônia over ten years. Area of study: The study was carried out in the state of Rondônia located in the North Region of Brazil (Western Amazon). Material and methods: The data and its by-products were derived from the Landsat Level 1 - TOA collection of the United States Geological Survey, specifically Landsat 5 and 8. The mapping also used Phantom 4 Pro UAV images. We used the supervised classifier Random Forest to map the primary forest/advanced regeneration, medium regeneration, initial regeneration, and classes, and, subsequently, we crossed and quantified the successional advance and vegetation loss. Main results: It was observed that the state lost forest area even with the successional advance that occurred throughout the period, implying that the forest succession was insufficient in the face of forest deforestation. Research highlights: This study contributed to understanding the dynamics of the Amazon Forest, which goes through a process of deforestation and forest regeneration simultaneously.

A preocupação com as mudanças climáticas globais tem motivado diversos pesquisadores a encontrar métodos eficazes para a quantificação de biomassa florestal e carbono estocado em florestas tropicais, uma vez que, estas atuam de forma mitigatória e compensatória desses efeitos. O sensoriamento remoto tem sido utilizado de forma eficaz e com grande potencial para a estimativas em larga escala, com destaque para dados de Radar de Abertura Sintética (SAR) e imagens multiespectrais. Os estudos já desenvolvidos com essa finalidade utilizaram diversas técnicas para associar a biomassa acima do solo (AGB) com os dados obtidos por sensoriamento remoto, entretanto, a aplicação da regressão robusta ainda não está sendo utilizada para tal finalidade. Sendo assim, o objetivo do presente estudo é avaliar o desempenho da regressão robusta comparando com a regressão linear que é tradicionalmente utilizada, além de avaliar o potencial da utilização dos dados oriundos do satélite Sentinel 1 e 2. Neste âmbito, foram utilizadas imagens multiespectrais (Sentinel 2), imagem SAR (Sentinel 1) e como variável resposta a AGB obtida a partir de dados Light Detection and Ranging (LiDAR). A AGB foi estimada por dois métodos de regressão: robusta e linear. Os modelos de regressão robusta e linear apresentaram desempenho semelhante, com R²aj. variando entre 0,33 a 0,34, erro padrão da estimativa de 48 Mg.ha-1 e raiz do erro médio quadrático de 16%. Conclui-se que não houve diferença significativa entre a regressão linear e a regressão robusta para esse conjunto de dados, indicando que a regressão não é influenciada por possíveis outliers e que existe potencial na utilização de dados oriundos do satélite Sentinel.

The aim of this study was to evaluate the effect of the root of vetiver grass (Chrysopogon zizanioides (L.) Robert) on the soil Resistance to penetration (RP) in the margins of the lower São Francisco River. Vetiver grass seedlings were planted on the riverbank margins in order to increase soil resistance to erosion processes, and RP assessments were made at soil depths of 0-0.20, 0.20-0.40, and 0.40-0.60 m in different situations (near the plants and within rows). RP data was obtained using an automated penetrometer. Gravimetric moisture data was also collected, as well as particle size data by densimetry, and root density data by the monolith method. The results of the RP, moisture, and root density studies were subjected to analysis of variance (p

Precise assessments of forest species’ composition help analyze biodiversity patterns, estimate wood stocks, and improve carbon stock estimates. Therefore, the objective of this work was to evaluate the use of high-resolution images obtained from Unmanned Aerial Vehicle (UAV) for the identification of forest species in areas of forest regeneration in the Amazon. For this purpose, convolutional neural networks (CNN) were trained using the Keras–Tensorflow package with the faster_rcnn_inception_v2_pets model. Samples of six forest species were used to train CNN. From these, attempts were made with the number of thresholds, which is the cutoff value of the function; any value below this output is considered 0, and values above are treated as an output 1; that is, values above the value stipulated in the Threshold are considered as identified species. The results showed that the reduction in the threshold decreases the accuracy of identification, as well as the overlap of the polygons of species identification. However, in comparison with the data collected in the field, it was observed that there exists a high correlation between the trees identified by the CNN and those observed in the plots. The statistical metrics used to validate the classification results showed that CNN are able to identify species with accuracy above 90%. Based on our results, which demonstrate good accuracy and precision in the identification of species, we conclude that convolutional neural networks are an effective tool in classifying objects from UAV images.

Purpose: Wearable sensors are used to measure head impact exposure in sports. The Head Impact Telemetry (HIT) System is a helmet-mounted system that has been commonly utilized to measure head impacts in American football. Advancements in sensor technology have fueled the development of alternative sensor methods such as instrumented mouthguards. The objective of this study was to compare peak magnitude measured from high school football athletes dually instrumented with the HIT System and a mouthpiece-based sensor system., Methods: Data was collected at all contact practices and competitions over a single season of spring football. Recorded events were observed and identified on video and paired using event timestamps. Paired events were further stratified by removing mouthpiece events with peak resultant linear acceleration below 10 g and events with contact to the facemask or body of athletes., Results: A total of 133 paired events were analyzed in the results. There was a median difference (mouthpiece subtracted from HIT System) in peak resultant linear and rotational acceleration for concurrently measured events of 7.3 g and 189 rad/s 2 . Greater magnitude events resulted in larger kinematic differences between sensors and a Bland Altman analysis found a mean bias of 8.8 g and 104 rad/s 2 , respectively., Conclusion: If the mouthpiece-based sensor is considered close to truth, the results of this study are consistent with previous HIT System validation studies indicating low error on average but high scatter across individual events. Future researchers should be mindful of sensor limitations when comparing results collected using varying sensor technologies., (© 2024. The Author(s).)

Subconcussive, repetitive head impacts sustained in collision sports may negatively affect brain health. American football practices are controlled environments amenable to intervention. Engaging community members is essential for successful development, implementation, and sustainability of viable interventions. The objective of this study is to develop and pilot test an evidence-based intervention to reduce head impact exposure in youth American football (i.e., football), using a community-engaged approach. This manuscript describes the co-design of the intervention and associated implementation plan and the study protocol for evaluating the effectiveness and feasibility of the intervention and implementation plan. In the first part of this study, focus groups with parents and coaches, and individual interviews with organizational leaders associated with two teams at the middle school level were conducted. An anonymous survey assessing beliefs and perceptions of non-concussive head impacts was given to parents, coaches, and organizational leaders within the local youth football league. Following the football season, qualitative and quantitative data describing determinants of head acceleration events in football were shared with 12 stakeholders of coaches, league and school administrators, parents, an athletic trainer, and local university player development director. Together, we co-designed COACH (COmmunities Aligned to reduce Concussion and Head impact exposure) and implementation plan using a strategic planning approach. The preliminary effectiveness and feasibility were assessed in the second part of this study. Youth football players participating on the teams in year 1 (control teams) were fitted with mouthpiece-based head kinematic sensors which measure head acceleration events (HAEs). HAEs were collected and quantified during team activities. Preliminary effectiveness of the intervention to reduce HAEs was measured among two new teams pilot testing COACH with mouthpiece-based sensors, while simultaneously monitoring implementation of the intervention. We report our study design and evaluation, and opportunities and challenges with our approach. The results will inform a future full-scale pragmatic trial to assess the implementation and effectiveness of the intervention program. NCT04908930., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Stitzel and Urban hold a patent for the mouthpiece form factor described in the protocol., (© 2024 The Authors.)

Competing Interests: Matthew S. Krantz reports grants from the National Institutes of Health (T32, HL087738-17). Elizabeth J. Phillips reports grants from the National Institutes of Health (R01HG010863, R01AI152183, and U01AI154659) and from the National Health and Medical Research Council of Australia. She receives royalties from and consults for UpToDate. She consults for Janssen, Verve, Biocryst, Ramboll/Esperion, Lexicomp, Regeneron, AstraZeneca, and Novavax.

Background: Diffuse intimal hyperplasia and graft irregularity adversely affect the long-term patency of saphenous vein grafts (SVGs) and clinical outcomes of patients undergoing coronary artery bypass grafting (CABG). The VEST trial evaluated the efficacy of external graft support in limiting the development of intimal hyperplasia (IH) at 1 year postsurgery. In the present secondary analysis, we explored the associations between graft disease and IH and clinical events. We also examined risk factors for early graft occlusion., Methods: VEST is a within-patient randomized, multicenter trial that enrolled 224 patients with multivessel coronary disease undergoing CABG surgery, of whom 203 were evaluated by 1 year postsurgery. Intimal hyperplasia, lumen uniformity, graft stenosis, and graft perfusion were measured by intravascular ultrasound and angiography. Major cardiac and cerebrovascular events (MACCE; including death, myocardial infarction, stroke, and revascularization) were recorded over a median follow-up of 3 years., Results: Worse lumen uniformity, greater stenosis, and worse graft perfusion were associated with higher IH values and an increased incidence of clinical events. Consistent with previous findings, we identified endoscopic vein harvesting, female sex, and transit time flow measurement of pulsatility index and flow as risk factors for SVG occlusion during the first year postsurgery., Conclusions: In this secondary analysis of the VEST trial, we observed an association between intimal hyperplasia area and clinical measures of SVG disease at 1 year postsurgery. More severe SVG disease and larger areas of IH were associated with a higher incidence of 3-year MACCE. Ongoing follow-up to 5 years will further elucidate the impact of SVG disease on long-term clinical outcomes of CABG., (Copyright © 2022 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN) is a predominantly drug-induced disease, with a mortality rate of 15-20%, that engages the expertise of multiple disciplines: dermatology, allergy, immunology, clinical pharmacology, burn surgery, ophthalmology, urogynecology, and psychiatry. SJS/TEN has an incidence of 1-5/million persons per year in the United States, with even higher rates globally. One of the challenges of SJS/TEN has been developing the research infrastructure and coordination to answer questions capable of transforming clinical care and leading to improved patient outcomes. SJS/TEN 2021, the third research meeting of its kind, was held as a virtual meeting on August 28-29, 2021. The meeting brought together 428 international scientists, in addition to a community of 140 SJS/TEN survivors and family members. The goal of the meeting was to brainstorm strategies to support the continued growth of an international SJS/TEN research network, bridging science and the community. The community workshop section of the meeting focused on eight primary themes: mental health, eye care, SJS/TEN in children, non-drug induced SJS/TEN, long-term health complications, new advances in mechanisms and basic science, managing long-term scarring, considerations for skin of color, and COVID-19 vaccines. The meeting featured several important updates and identified areas of unmet research and clinical need that will be highlighted in this white paper., Competing Interests: KM was employed by Stevens-Johnson Syndrome Foundation. EJP reports grants from National Institutes of Health (R01HG010863, R01AI152183, U01AI154659) and from the National Health and Medical Research Council of Australia. She receives Royalties and consulting fees from UpToDate and has received consulting fees from Janssen, Verve, Biocryst, Regeneron, AstraZeneca and Novavax. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer OI declared a shared affiliation with the author AS to the handling editor at the time of review., (Copyright © 2023 Marks, Botta, Abe, Beachkofsky, Boothman, Carleton, Chung, Cibotti, Dodiuk-Gad, Grimstein, Hasegawa, Hoofnagle, Hung, Kaffenberger, Kroshinsky, Lehloenya, Martin-Pozo, Micheletti, Mockenhaupt, Nagao, Pakala, Palubinsky, Pasieka, Peter, Pirmohamed, Reyes, Saeed, Shupp, Sukasem, Syu, Ueta, Zhou, Chang, Becker, Bellon, Bonnet, Cavalleri, Chodosh, Dewan, Dominguez, Dong, Ezhkova, Fuchs, Goldman, Himed, Mallal, Markova, McCawley, Norton, Ostrov, Phan, Sanford, Schlundt, Schneider, Shear, Shinkai, Tkaczyk, Trubiano, Volpi, Bouchard, Divito and Phillips.)

Many head acceleration events (HAEs) observed in youth football emanate from a practice environment. This study aimed to evaluate HAEs in youth football practice drills using a mouthpiece-based sensor, differentiating between inertial and direct HAEs. Head acceleration data were collected from athletes participating on 2 youth football teams (ages 11-13 y) using an instrumented mouthpiece-based sensor during all practice sessions in a single season. Video was recorded and analyzed to verify and assign HAEs to specific practice drill characteristics, including drill intensity, drill classification, and drill type. HAEs were quantified in terms of HAEs per athlete per minute and peak linear and rotational acceleration and rotational velocity. Mixed-effects models were used to evaluate the differences in kinematics, and generalized linear models were used to assess differences in HAE frequency between drill categories. A total of 3237 HAEs were verified and evaluated from 29 football athletes enrolled in this study. Head kinematics varied significantly between drill categorizations. HAEs collected at higher intensities resulted in significantly greater kinematics than lower-intensity drills. The results of this study add to the growing body of evidence informing evidence-based strategies to reduce head impact exposure and concussion risk in youth football practices.

Rationale: There are limited therapeutic options for patients with coronavirus disease (COVID-19)-related acute respiratory distress syndrome with inflammation-mediated lung injury. Mesenchymal stromal cells offer promise as immunomodulatory agents. Objectives: Evaluation of efficacy and safety of allogeneic mesenchymal cells in mechanically-ventilated patients with moderate or severe COVID-19-induced respiratory failure. Methods: Patients were randomized to two infusions of 2 million cells/kg or sham infusions, in addition to the standard of care. We hypothesized that cell therapy would be superior to sham control for the primary endpoint of 30-day mortality. The key secondary endpoint was ventilator-free survival within 60 days, accounting for deaths and withdrawals in a ranked analysis. Measurements and Main Results: At the third interim analysis, the data and safety monitoring board recommended that the trial halt enrollment as the prespecified mortality reduction from 40% to 23% was unlikely to be achieved ( n  = 222 out of planned 300). Thirty-day mortality was 37.5% (42/112) in cell recipients versus 42.7% (47/110) in control patients (relative risk [RR], 0.88; 95% confidence interval, 0.64-1.21; P  = 0.43). There were no significant differences in days alive off ventilation within 60 days (median rank, 117.3 [interquartile range, 60.0-169.5] in cell patients and 102.0 [interquartile range, 54.0-162.5] in control subjects; higher is better). Resolution or improvement of acute respiratory distress syndrome at 30 days was observed in 51/104 (49.0%) cell recipients and 46/106 (43.4%) control patients (odds ratio, 1.36; 95% confidence interval, 0.57-3.21). There were no infusion-related toxicities and overall serious adverse events over 30 days were similar. Conclusions: Mesenchymal cells, while safe, did not improve 30-day survival or 60-day ventilator-free days in patients with moderate and/or severe COVID-19-related acute respiratory distress syndrome.

Understanding characteristics of head acceleration events (HAEs) in youth football is vital in developing strategies to improve athlete safety. This study aimed to characterize HAEs in youth football using an instrumented mouthpiece. Youth football athletes (ages 11-13) participating on two teams were enrolled in this study for one season. Each athlete was instrumented with a mouthpiece-based sensor throughout the season. HAEs were verified on film to ensure that mouthpiece-based sensors triggered during contact. The number of HAEs, peak resultant linear and rotational accelerations, and peak resultant rotational velocity were quantified. Mixed effects models were used to evaluate differences in mean kinematic metrics among all HAEs for session type, athlete position, and contact surface. A total of 5,292 HAEs were collected and evaluated from 30 athletes. The median (95th percentile) peak resultant linear acceleration, rotational acceleration, and rotational velocity was 9.5 g (27.0 g), 666.4 rad s -2 (1863.3 rad s -2 ), and 8.5 rad s -1 (17.4 rad s -1 ), respectively. Athletes experienced six (22) HAEs per athlete per session (i.e., practice, game). Competition had a significantly higher mean number of HAEs per athlete per session and mean peak rotational acceleration. Peak resultant rotational kinematics varied significantly among athlete positions. Direct head impacts had higher mean kinematics compared to indirect HAEs, from body collisions. The results of this study demonstrate that session type, athlete position, and contact surface (i.e., direct, indirect) may influence HAE exposure in youth football., (© 2022. The Author(s) under exclusive licence to Biomedical Engineering Society.)

Importance: Intimal hyperplasia and subsequent saphenous vein graft failure may have significant adverse clinical effects in patients undergoing coronary artery bypass surgery. External support of saphenous vein grafts has the potential to prevent vein graft dilation and hence slow the rate of intimal hyperplasia and increase long-term vein patency., Objective: To determine efficacy, as measured by intimal hyperplasia, and safety of an external saphenous vein graft support device in patients undergoing a coronary bypass graft procedure., Design, Setting, and Participants: This within-patient randomized, open-label, multicenter study was conducted at 17 Cardiothoracic Surgical Trials Network centers in North America. Between January 2018 and February 2019, 224 patients with multivessel coronary artery disease undergoing isolated bypass surgery were enrolled. For each patient, 1 of 2 vein grafts was randomized to receive external support or no support., Interventions: External vein graft support or no support., Main Outcomes and Measures: The primary efficacy end point was intimal hyperplasia area assessed by intravascular ultrasound at 12 months postrandomization for each study graft. Secondary confirmatory end points were lumen diameter uniformity assessed by angiography and graft failure (≥50% stenosis) by quantitative coronary angiography. Major cardiac and cerebrovascular events were collected through month 12., Results: Among 224 patients (mean [SD] age, 65.8 [8.3] years; 178 [79.5%] male), 203 (90.6%) were eligible for intravascular ultrasound, of which 85 (41.9%) had at least 1 study graft occluded or severely diseased at 12 months (55 supported, 56 unsupported). After imputation of data missing because of graft occlusion or severe disease, the estimated mean (SE) intimal hyperplasia area was 5.11 (0.16) mm2 in supported grafts and 5.79 (0.20) mm2 in unsupported grafts (P = .07). In a sensitivity analysis of 113 patients with both grafts imaged, the mean intimal hyperplasia area was 4.58 (0.18) mm2 and 5.12 (0.23) mm2 in supported and unsupported grafts, respectively (P = .04). By 12 months, 5 patients (2.2%) died and 16 patients (7.1%) experienced a major cardiac or cerebrovascular event., Conclusions and Relevance: The 12-month difference in intimal hyperplasia area between supported and unsupported grafts did not achieve statistical significance. Cumulative mortality and major cardiac or cerebrovascular events rates were similar to those in other randomized coronary artery bypass trials. Further investigation to assess the effect of external graft support devices on long-term graft patency and clinical outcomes is warranted., Trial Registration: ClinicalTrials.gov Identifier: NCT03209609.

This study evaluated head impact exposure (HIE) metrics in relation to individual-level determinants of HIE. Youth (n = 13) and high school (n = 21) football players were instrumented with the Head Impact Telemetry (HIT) system during one season. Players completed the Trait-Robustness of Self-Confidence Inventory (TROSCI), Sports Climate Questionnaire (SCQ), and Competitive Aggressiveness and Anger Scale (CAAS), measuring self-confidence, perceived coach support, and competitive aggressiveness, respectively. Relationships between HIE metrics (number of impacts, median and 95th percentile accelerations, and risk-weighted exposure (RWE)) and survey scores were evaluated using linear regression analysis. For middle school athletes, TROSCI scores were significantly negatively associated with the number of competition impacts and the mean number of impacts per player per competition. SCQ scores were significantly positively associated with median linear acceleration during practice. CAAS scores were not significantly associated with biomechanical metrics at either level of play. Perceived coach support and self-confidence might influence HIE among middle school football players. Football athletes' competitive aggressiveness may have less influence their HIE than other factors.

Background: Coronary artery bypass grafting (CABG) is the most common revascularization approach for the treatment of multi-vessel coronary artery disease. While the internal mammary artery is nearly universally used to bypass the left anterior descending coronary artery, autologous saphenous vein grafts (SVGs) are still the most frequently used conduits to grafts the remaining coronary artery targets. Long-term failure of these grafts, however, continues to limit the benefits of surgery., Methods: The Cardiothoracic Surgical Trials Network trial of the safety and effectiveness of a Venous External Support (VEST) device is a randomized, multicenter, within-patient trial comparing VEST-supported versus unsupported saphenous vein grafts in patients undergoing CABG. Key inclusion criteria are the need for CABG with a planned internal mammary artery to the left anterior descending and two or more saphenous vein grafts to other coronary arteries. The primary efficacy endpoint of the trial is SVG intimal hyperplasia (plaque + media) area assessed by intravascular ultrasound at 12 months post randomization. Occluded grafts are accounted for in the analysis of the primary endpoint. Secondary confirmatory endpoints are lumen diameter uniformity and graft failure (>50% stenosis) assessed by coronary angiography at 12 months. The safety endpoints are the occurrence of major adverse cardiac and cerebrovascular events and hospitalization within 5 years from randomization., Conclusions: The results of the VEST trial will determine whether the VEST device can safely limit SVG intimal hyperplasia in patients undergoing CABG as treatment for coronary atherosclerotic disease., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Tricuspid regurgitation is common in patients with severe degenerative mitral regurgitation. However, the evidence base is insufficient to inform a decision about whether to perform tricuspid-valve repair during mitral-valve surgery in patients who have moderate tricuspid regurgitation or less-than-moderate regurgitation with annular dilatation., Methods: We randomly assigned 401 patients who were undergoing mitral-valve surgery for degenerative mitral regurgitation to receive a procedure with or without tricuspid annuloplasty (TA). The primary 2-year end point was a composite of reoperation for tricuspid regurgitation, progression of tricuspid regurgitation by two grades from baseline or the presence of severe tricuspid regurgitation, or death., Results: Patients who underwent mitral-valve surgery plus TA had fewer primary-end-point events than those who underwent mitral-valve surgery alone (3.9% vs. 10.2%) (relative risk, 0.37; 95% confidence interval [CI], 0.16 to 0.86; P = 0.02). Two-year mortality was 3.2% in the surgery-plus-TA group and 4.5% in the surgery-alone group (relative risk, 0.69; 95% CI, 0.25 to 1.88). The 2-year prevalence of progression of tricuspid regurgitation was lower in the surgery-plus-TA group than in the surgery-alone group (0.6% vs. 6.1%; relative risk, 0.09; 95% CI, 0.01 to 0.69). The frequencies of major adverse cardiac and cerebrovascular events, functional status, and quality of life were similar in the two groups at 2 years, although the incidence of permanent pacemaker implantation was higher in the surgery-plus-TA group than in the surgery-alone group (14.1% vs. 2.5%; rate ratio, 5.75; 95% CI, 2.27 to 14.60)., Conclusions: Among patients undergoing mitral-valve surgery, those who also received TA had a lower incidence of a primary-end-point event than those who underwent mitral-valve surgery alone at 2 years, a reduction that was driven by less frequent progression to severe tricuspid regurgitation. Tricuspid repair resulted in more frequent permanent pacemaker implantation. Whether reduced progression of tricuspid regurgitation results in long-term clinical benefit can be determined only with longer follow-up. (Funded by the National Heart, Lung, and Blood Institute and the German Center for Cardiovascular Research; ClinicalTrials.gov number, NCT02675244.)., (Copyright © 2021 Massachusetts Medical Society.)

Hop powdery mildew, caused by the ascomycete fungus Podosphaera macularis , is a consistent threat to sustainable hop production. The pathogen utilizes two reproductive strategies for overwintering and perennation: (i) asexual vegetative hyphae on dormant buds that emerge the following season as infected shoots; and (ii) sexual ascocarps (chasmothecia), which are discharged during spring rain events. We demonstrate that P. macularis chasmothecia, in the absence of any asexual P. macularis growth forms, are a viable overwintering source capable of causing early season infection two to three orders of magnitude greater than that reported for perennation via asexual growth. Two epidemiological models were defined that describe (i) temperature-driven maturation of P. macularis chasmothecia; and (ii) ascosporic discharge in response to duration of leaf wetness and prevailing temperatures. P. macularis ascospores were confirmed to be infectious at temperatures ranging from 5 to 20°C. The organism's chasmothecia were also found to adhere tightly to the host tissue on which they formed, suggesting that these structures likely overwinter wherever hop tissue senesces within a hop yard. These observations suggest that existing early season disease management practices are especially crucial to controlling hop powdery mildew in the presence of P. macularis chasmothecia. Furthermore, these insights provide a baseline for the validation of weather-driven models describing maturation and release of P. macularis ascospores, models that can eventually be incorporated into hop disease management programs.

The aim of this study was to develop and test the reliability of an instrument to evaluate the quality of clinical teaching among dental school faculty. Fourth-year dental students' perspectives on effective clinical teaching were first collected in focus group meetings. An 11-item questionnaire to assess seven domains of clinical teaching was developed based on the collected student perspectives and a medical model. All 374 third- and fourth-year dental students at one U.S. dental school in 2015 were invited to evaluate four clinical instructors whom they felt were strong role models and four clinical instructors whom they felt would benefit from constructive criticism. The survey was completed by 139 students (37.2% response rate); they evaluated 96 dental instructors. The results showed that the survey demonstrated strong internal reliability, with Cronbach's alpha values of >0.95 for each of the seven domains. In addition, there was significant agreement between groups: the interclass correlation (ICC) ranged from 0.97 to 0.99. These results suggest that the clinical faculty evaluation instrument developed in this study is a reliable method that can be used to evaluate dental faculty members. This system can be a valuable guide for clinical faculty members and administrators in assessing and improving clinical teaching effectiveness., (© 2019 American Dental Education Association.)

Importance: Left ventricular assist device (LVAD) therapy improves myocardial function, but few patients recover sufficiently for explant, which has focused attention on stem cells to augment cardiac recovery., Objective: To assess efficacy and adverse effects of intramyocardial injections of mesenchymal precursor cells (MPCs) during LVAD implant., Design, Setting, and Participants: A randomized phase 2 clinical trial involving patients with advanced heart failure, undergoing LVAD implant, at 19 North American centers (July 2015-August 2017). The 1-year follow-up ended August 2018., Interventions: Intramyocardial injections of 150 million allogeneic MPCs or cryoprotective medium as a sham treatment in a 2:1 ratio (n = 106 vs n = 53)., Main Outcomes and Measures: The primary efficacy end point was the proportion of successful temporary weans (of 3 planned assessments) from LVAD support within 6 months of randomization. This end point was assessed using a Bayesian analysis with a predefined threshold of a posterior probability of 80% to indicate success. The 1-year primary safety end point was the incidence of intervention-related adverse events (myocarditis, myocardial rupture, neoplasm, hypersensitivity reactions, and immune sensitization). Secondary end points included readmissions and adverse events at 6 months and 1-year survival., Results: Of 159 patients (mean age, 56 years; 11.3% women), 155 (97.5%) completed 1-year of follow-up. The posterior probability that MPCs increased the likelihood of successful weaning was 69%; below the predefined threshold for success. The mean proportion of successful temporary weaning from LVAD support over 6 months was 61% in the MPC group and 58% in the control group (rate ratio [RR], 1.08; 95% CI, 0.83-1.41; P = .55). No patient experienced a primary safety end point. Of 10 prespecified secondary end points reported, 9 did not reach statistical significance. One-year mortality was not significantly different between the MPC group and the control group (14.2% vs 15.1%; hazard ratio [HR], 0.89; 95%, CI, 0.38-2.11; P = .80). The rate of serious adverse events was not significantly different between groups (70.9 vs 78.7 per 100 patient-months; difference, -7.89; 95% CI, -39.95 to 24.17; P = .63) nor was the rate of readmissions (0.68 vs 0.75 per 100 patient-months; difference, -0.07; 95% CI, -0.41 to 0.27; P = .68)., Conclusions and Relevance: Among patients with advanced heart failure, intramyocardial injections of mesenchymal precursor cells, compared with injections of a cryoprotective medium as sham treatment, did not improve successful temporary weaning from left ventricular assist device support at 6 months. The findings do not support the use of intramyocardial mesenchymal stem cells to promote cardiac recovery as measured by temporary weaning from device support., Trial Registration: clinicaltrials.gov Identifier: NCT02362646.

Complex and interacting selective pressures can produce bacterial communities with a range of phenotypes. One measure of bacterial success is the ability of cells or populations to proliferate while avoiding lytic phage infection. Resistance against bacteriophage infection can occur in the form of a metabolically expensive exopolysaccharide capsule. Here, we show that in Caulobacter crescentus, presence of an exopolysaccharide capsule provides measurable protection against infection from a lytic paracrystalline S-layer bacteriophage (CR30), but at a metabolic cost that reduces success in a phage-free environment. Carbon flux through GDP-mannose 4,6 dehydratase in different catabolic and anabolic pathways appears to mediate this trade-off. Together, our data support a model in which diversity in bacterial communities may be maintained through variable selection on phenotypes utilizing the same metabolic pathway.

Sclerotinia sclerotiorum population variability directly affects Sclerotinia stem rot (SSR) resistance breeding programs. In the north-central United States, however, soybean germplasm selection has often involved only a single isolate. Forty-four S. sclerotiorum isolates from Illinois, Michigan, Minnesota, Nebraska, Wisconsin, Poland, and across 11 different host species were evaluated for variation in isolate in vitro growth, in vitro oxalate production, and in planta aggressiveness on the susceptible soybean 'Williams 82'. Significant differences (P < 0.0001) were detected in isolate in planta aggressiveness, in vitro growth, and in vitro oxalate production. Furthermore, diverse isolate characteristics were observed within all hosts and locations of collection. Aggressiveness was not correlated to colony growth and was only weakly correlated (r = 0.26, P < 0.0001) to isolate oxalate production. In addition, the host or location of collection did not explain isolate aggressiveness. Isolate oxalic acid production, however, may be partially explained by the host (P < 0.05) and location (P < 0.01) of collection. Using a representative subset of nine S. sclerotiorum isolates and soybean genotypes exhibiting susceptible or resistant responses (determined using a single isolate), a significant interaction (P = 0.04) was detected between isolates and genotypes when SSR severity was evaluated. Our findings suggest that screening of S. sclerotiorum-resistant soybean germplasm should be performed with multiple isolates to account for the overall diversity of S. sclerotiorum isolates found throughout the soybean-growing regions of the United States.

Background: Trachoma is endemic in several Pacific Island states. Recent surveys across the Solomon Islands indicated that whilst trachomatous inflammation-follicular (TF) was present at levels warranting intervention, the prevalence of trachomatous trichiasis (TT) was low. We set out to determine the relationship between chlamydial infection and trachoma in this population., Methods: We conducted a population-based trachoma prevalence survey of 3674 individuals from two Solomon Islands provinces. Participants were examined for clinical signs of trachoma. Conjunctival swabs were collected from all children aged 1-9 years. We tested swabs for Chlamydia trachomatis (Ct) DNA using droplet digital PCR. Chlamydial DNA from positive swabs was enriched and sequenced for use in phylogenetic analysis., Results: We observed a moderate prevalence of TF in children aged 1-9 years (n = 296/1135, 26.1%) but low prevalence of trachomatous inflammation-intense (TI) (n = 2/1135, 0.2%) and current Ct infection (n = 13/1002, 1.3%) in children aged 1-9 years, and TT in those aged 15+ years (n = 2/2061, 0.1%). Ten of 13 (76.9%) cases of infection were in persons with TF or TI (p = 0.0005). Sequence analysis of the Ct-positive samples yielded 5/13 (38%) complete (>95% coverage of reference) genome sequences, and 8/13 complete plasmid sequences. Complete sequences all aligned most closely to ocular serovar reference strains., Discussion: The low prevalence of TT, TI and Ct infection that we observed are incongruent with the high proportion of children exhibiting signs of TF. TF is present at levels that apparently warrant intervention, but the scarcity of other signs of trachoma indicates the phenotype is mild and may not pose a significant public health threat. Our data suggest that, whilst conjunctival Ct infection appears to be present in the region, it is present at levels that are unlikely to be the dominant driving force for TF in the population. This could be one reason for the low prevalence of TT observed during the study., Competing Interests: All authors declare that they have no conflicts of interest.

Background: Malaria is the commonest imported infection in the UK. Malaria requiring ICU admission has a reported mortality of up to 25%. The relationship between ethnicity, immunity, and risk of malaria is complex. The Malaria Score for Adults (MSA) and Coma Acidosis Malaria (CAM) score have recently been proposed to risk stratify patients with malaria., Methods: Retrospective study of patients with WHO severe falciparum malaria admitted to ICU at the Hospital for Tropical Diseases, London, UK. The relationship between clinical variables and risk of death or a prolonged ICU stay were examined with logistic regression. The predictive value of the MSA and CAM score were calculated., Results: 124 patients were included. Cerebral malaria and acute kidney injury occurred earlier (median day 1) than acute respiratory distress syndrome (median day 3). Six patients had community acquired bacterial co-infection. Eight patients were co-infected with HIV, five of whom were newly diagnosed. The positive predictive value of a CAM score ≥2 or an MSA ≥5 for death were 12% and 22% respectively. Five patients died. No variable was significantly associated with risk of death. There were no significant differences between individuals raised in endemic countries compared to non-endemic countries., Conclusions: Mortality in patients managed in a specialist centre was low. Patients who died succumbed to complications associated with a prolonged stay on ICU rather than malaria per se. The clinical usefulness of the MSA and CAM score was limited. Co-infection with HIV was relatively common but compared to studies in children, bacteraemia was uncommon. The relationship between ethnicity and immunity to severe disease is complex.

The dimorphic bacterium Caulobacter crescentus has evolved marked phenotypic changes during its 50-year history of culture in the laboratory environment, providing an excellent system for the study of natural selection and phenotypic microevolution in prokaryotes. Combining whole-genome sequencing with classical molecular genetic tools, we have comprehensively mapped a set of polymorphisms underlying multiple derived phenotypes, several of which arose independently in separate strain lineages. The genetic basis of phenotypic differences in growth rate, mucoidy, adhesion, sedimentation, phage susceptibility, and stationary-phase survival between C. crescentus strain CB15 and its derivative NA1000 is determined by coding, regulatory, and insertion/deletion polymorphisms at five chromosomal loci. This study evidences multiple genetic mechanisms of bacterial evolution as driven by selection for growth and survival in a new selective environment and identifies a common polymorphic locus, zwf, between lab-adapted C. crescentus and clinical isolates of Pseudomonas aeruginosa that have adapted to a human host during chronic infection.

The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown. Pelvic loss in different natural populations of threespine stickleback fish has occurred through regulatory mutations deleting a tissue-specific enhancer of the Pituitary homeobox transcription factor 1 (Pitx1) gene. The high prevalence of deletion mutations at Pitx1 may be influenced by inherent structural features of the locus. Although Pitx1 null mutations are lethal in laboratory animals, Pitx1 regulatory mutations show molecular signatures of positive selection in pelvic-reduced populations. These studies illustrate how major expression and morphological changes can arise from single mutational leaps in natural populations, producing new adaptive alleles via recurrent regulatory alterations in a key developmental control gene.

Articular cartilage plays an essential role in health and mobility, but is frequently damaged or lost in millions of people that develop arthritis. The molecular mechanisms that create and maintain this thin layer of cartilage that covers the surface of bones in joint regions are poorly understood, in part because tools to manipulate gene expression specifically in this tissue have not been available. Here we use regulatory information from the mouse Gdf5 gene (a bone morphogenetic protein [BMP] family member) to develop new mouse lines that can be used to either activate or inactivate genes specifically in developing joints. Expression of Cre recombinase from Gdf5 bacterial artificial chromosome clones leads to specific activation or inactivation of floxed target genes in developing joints, including early joint interzones, adult articular cartilage, and the joint capsule. We have used this system to test the role of BMP receptor signaling in joint development. Mice with null mutations in Bmpr1a are known to die early in embryogenesis with multiple defects. However, combining a floxed Bmpr1a allele with the Gdf5-Cre driver bypasses this embryonic lethality, and leads to birth and postnatal development of mice missing the Bmpr1a gene in articular regions. Most joints in the body form normally in the absence of Bmpr1a receptor function. However, articular cartilage within the joints gradually wears away in receptor-deficient mice after birth in a process resembling human osteoarthritis. Gdf5-Cre mice provide a general system that can be used to test the role of genes in articular regions. BMP receptor signaling is required not only for early development and creation of multiple tissues, but also for ongoing maintenance of articular cartilage after birth. Genetic variation in the strength of BMP receptor signaling may be an important risk factor in human osteoarthritis, and treatments that mimic or augment BMP receptor signaling should be investigated as a possible therapeutic strategy for maintaining the health of joint linings., Competing Interests: The authors have declared that no conflicts of interest exist.

Hindlimb loss has evolved repeatedly in many different animals by means of molecular mechanisms that are still unknown. To determine the number and type of genetic changes underlying pelvic reduction in natural populations, we carried out genetic crosses between threespine stickleback fish with complete or missing pelvic structures. Genome-wide linkage mapping shows that pelvic reduction is controlled by one major and four minor chromosome regions. Pitx1 maps to the major chromosome region controlling most of the variation in pelvic size. Pelvic-reduced fish show the same left-right asymmetry seen in Pitx1 knockout mice, but do not show changes in Pitx1 protein sequence. Instead, pelvic-reduced sticklebacks show site-specific regulatory changes in Pitx1 expression, with reduced or absent expression in pelvic and caudal fin precursors. Regulatory mutations in major developmental control genes may provide a mechanism for generating rapid skeletal changes in natural populations, while preserving the essential roles of these genes in other processes.

The embryonic telencephalon is patterned into several areas that give rise to functionally distinct structures in the adult forebrain. Previous studies have shown that BMP4 and BMP2 can induce features characteristic of the telencephalic midline in cultured explants, suggesting that the normal role of BMP4 in the forebrain is to pattern the medial lateral axis of the telencephalon by promoting midline cell fates. To test this hypothesis directly in vivo, the Bmp4 gene was efficiently disrupted in the telencephalon using a CRE/loxP approach. Analysis of Bmp4-deficient telencephalons fails to reveal a defect in patterning, cell proliferation, differentiation, or apoptosis. The absence of a phenotype in the Bmp4-deficient telencephalon along with recent genetic studies establishing a role for a BMP4 receptor, BMPRIA, in telencephalic midline development, demonstrate that loss of Bmp4 function in the telencephalon can be compensated for by at least one other Bmp gene, the identity of which has not yet been determined., (Copyright 2003 Wiley-Liss, Inc.)

The treatment results in 85 patients with T1N0M0 squamous cell carcinoma of the glottic larynx who were treated with primary radiation therapy were reviewed to analyze for local control. After a minimum follow-up period of 2 years, 13 patients had local recurrence of disease, which yielded a local control rate of 84.7%. Local control was then reassessed as a function of substages (T1a and T1b) and dose fractionation. No difference in local control was seen in T1a and T1b neoplasms. However, after undergoing standard once-a-day fractionation, patients treated with fractions of 200 cGy had a local control rate of 96%, while those receiving 180 cGy had a local control rate of 79% (P = .05). Mean total dose for each patient group was comparable, and the median number of days of treatment interruption was the same for both groups. These data corroborate the recent findings of other authors regarding the importance of fraction size in facilitating local control of early-stage glottic cancer.

Four patients with a diagnosis of Merkel cell carcinoma initially underwent surgery followed by radiotherapy. Recurrent disease prompted use of radiation in three cases. The three cases of recurrent disease illustrate the aggressiveness of Merkel cell carcinoma and also provide further documentation of the radiosensitivity of this tumor. Additionally, these cases suggest that surgery alone frequently is inadequate to achieve local control of disease.

The tissue culture of human colonic carcinoma with and without feeder layers of confluent C3H 10T1/2 mouse fibroblast was compared. In a series of 27 different tumor specimens, 21 long-term cultures (6 mos. or more) were obtained by utilizing feeder layers. Only 3 long-term cultures were obtained from the same set of specimens when feeder layers were not employed. Several of the long-term cultures were established as cell lines weaned from fibroblast feeder layers. These lines could be classified into 3 groups based upon their expression of several biological properties including tumorigenicity in nude mice, degree of differentiation of the tumors growing in nude mice, growth in semisolid medium, morphology in vitro and production of carcinoembryonic antigen in vitro.

The initiation of a cultured human colon carcinoma line on a feeder layer of confluent fibroblasts is described. Attempts to initiate cultures without fibroblast feeder layers were not successful. Two sub-lines (designated HCT C and HCT C Col) were isolated and weaned from cells growing on the surface of the feeder layer. The sub-lines had different morphologies, secreted different levels of carcinoembryonic antigen (CEA) into the medium of confluent cultures and had slightly different karyotypes. Both sub-lines grew in semi-solid medium and formed xenografts when injected s.c. into athymic nude mice. Analysis of radioiodinated cell membrane components indicated small, but significant differences between the sub-lines.

A 72-year-old man originally seen for anemia and thrombocytopenia was determined to have chronic lymphocytic leukemia (CLL). Bone marrow examination at the time of CLL diagnosis revealed a small but significant population of atypical blasts. Cytogenetic analysis of the bone marrow aspirate disclosed chromosomal abnormalities (-7, +8) suggestive of a myelodysplastic syndrome. Shortly after treatment of the CLL, there was proliferation of the previously noted blast population, which cytochemical studies demonstrated to be of the myeloid series thus indicating acute myeloid leukemia superimposed on CLL. This report presents microscopic, cytogenetic, immunophenotypic, and cytochemical evidence to document the evolution of acute myeloid leukemia in the bone marrow of a patient with CLL after one course of chemotherapy.

Methylcholanthrene-transformed AKR-2B mouse embryonal fibroblasts (AKR-MCA cells) were examined for cell surface alterations after growth in culture medium containing N,N-dimethylformamide (DMF) using the lactoperoxidase-glucose oxidase radioiodination procedure with subsequent electrophoresis. DMF has been shown to induce maturational changes in a variety of transformed cells in vitro and has been reported to produce a more normal phenotype when applied to cultured AKR-MCA cells. The electrophoretic profile of 125I-labeled surface proteins from AKR-MCA cells exhibited a prominent peak of labeled material with a molecular weight of approximately 85,000. After growth of AKR-MCA cells in medium containing DMF, the Mr 85,000 peak was substantially reduced, while there was a large increase in Mr 200,000 to 250,000 radioiodinated surface material. This cell surface labeling pattern was virtually identical to that of the nontransformed AKR-2B fibroblasts from which AKR-MCA cells were derived. The cell surface alterations observed upon exposure of AKR-MCA cells to DMF occurred as a function of time of growth in DMF and DMF concentration. Growth of AKR-MCA cells in DMF resulted in a steady increase in cell surface 125I incorporation up to the fourth day of exposure to DMF. At this time, the incorporation level was 22.9-fold greater than that for untreated AKR-MCA cells. Incorporation of radiolabel was decreased after the fifth and sixth days of AKR-MCA exposure to DMF. This trend was also manifested by AKR-2B fibroblasts grown in the presence of DMF. The data suggest that there was increased expression of the Mr 200,000 to 250,000 surface protein on both AKR-2B and AKR-MCA cells when grown in DMF. DMF also inhibited morphological transformation and the cell surface changes associated with transformation of AKR-2B cells by exogenous transforming growth factors.

Six cultured human colon cancer cell lines possessing different biological characteristics were enzymatically radiolabeled in situ with 125I and 3H, and the labeled cell surface proteins and glycoproteins were compared. The electrophoretic patterns of labeled cell surface material suggest correlations between biological properties and cell surface proteins. Highly aggressive cell lines (as assessed by in vitro parameters) had predominant peaks of 125I-labeled proteins between molecular weights 66,000 and 92,500. The major peak of radioiodinated material from the more indolent cell lines occurred between molecular weights 31,000 and 45,000. The profile of one 125I-labeled intermediately aggressive cell line was similar to the profiles of the more aggressive lines, whereas another intermediate line exhibited a profile different from those of both indolent and aggressive lines. Electrophoresis of tritiated material indicated that essentially all of the recovered labeled glycoprotein was of relatively high molecular weight (92,000-180,000) in the indolent lines, whereas the intermediate and highly aggressive lines had patterns with significant peaks between molecular weights 45,000 and 92,500.

The cell surfaces of human colon cancer cells before and after exposure to N,N-dimethylformamide (DMF) were probed using radioiodination and immunofluorescent labeling techniques. Growth of the human colon carcinoma cell line HCT MOSER in DMF-supplemented culture medium resulted in monolayer culture growth and marked cell morphology alterations consisting of cellular flattening and elongation. Accompanying the morphology alterations were distinct changes in the cell surface protein composition as determined by 125I labeling and electrophoresis. The cell surface changes associated with growth of HCT MOSER cells in the presence of DMF were dependent upon time of exposure to DMF and DMF concentration. Furthermore, removal of DMF-treated HCT MOSER cells from DMF-containing growth medium caused reversion of both cell morphology and cell surface composition to a state comparable to that of cells not exposed to DMF. The HCT MOSER cell surface alterations produced by DMF included a reduction of radioiodinated surface proteins with molecular weights of 87,000, 120,000, and 180,000 and an increase of a 125I-labeled surface protein with a molecular weight of 200,000-250,000. Appearance of a surface protein of approximately 200,000 molecular weight and assumption of a fibroblast-like morphology by DMF-treated HCT MOSER cells suggested that this approximately 200,000 molecular weight material might be fibronectin. Immunofluorescent labeling with anti-human fibronectin showed that HCT MOSER cells grown in DMF did manifest an anti-fibronectin immunoreactive material that was only transiently associated with the cell surface before being released. DMF-treated HCT MOSER cultures continued to express surface carcinoembryonic antigen, indicating that the presence of material immunoreactive with anti-human fibronectin was not secondary to proliferation of a contaminating fibroblast population. The response of HCT MOSER cells to DMF paralleled in many ways that previously reported for methylcholanthrene-transformed AKR-2B (AKR-MCA) fibroblasts. However, unlike AKR-MCA cells, HCT MOSER cells did not exhibit an increase in 125I incorporation per microgram DNA as a function of time of exposure to DMF, which suggests that the surface protein with a molecular weight of approximately 200,000 induced by DMF was not retained on the cell surface.

AKR-2B mouse fibroblasts were treated with 50 micrograms/ml of crude transforming growth factor (TGF) of human origin. Cell surface proteins of treated cells were radioiodinated and compared to untreated cells at various times after the addition of TGF. Treated cells showed a severalfold increase (approximately 6-fold) in cell surface 125I incorporation relative to normal cells at 24 h. Electrophoretic comparison of treated and untreated cells showed large increases in the labelling of cell surface proteins of mol. wt. 50,000-90,000 from TGF-exposed cells between 10 and 24 h post treatment. By 48 h post treatment, the electrophoretic profiles of TGF-exposed cells had returned to a pattern similar to that of untreated cells. However, even after a 48 h exposure to TGF, the cells retained a transformed morphology indicating that the electrophoretic alterations were not simply due to the morphological transformation induced by TGF. The electrophoretic pattern of TGF-treated cells at 24 h post treatment was similar to that of AKR-2B cells permanently transformed by treatment with methylcholanthrene, but was clearly distinct from that induced by treatment of normal AKR-2B cells with epidermal growth factor (EGF). EGF induced an increase in a protein of mol. wt. 60,000 in the electrophoretic profiles taken 24 h post treatment. As with TGF, the appearance of electrophoretic profiles of EGF-treated cells returned to "normal" by 48 h. Again, these alterations did not appear to be dependent upon morphological changes since EGF-treated cells showed a morphological transformation similar to that of cells treated with TGF, and this was maintained throughout the 48 h experimental period.

Three sets of experiments lend support to the hypothesis that there are at least three processes of imagery: (1) figural, in which a quasi-visual or other sensory representation of an object is made; (2) symbolic in which an abstract concepts is illustrated or symbolized by some imaginal representation; and (3) mimetic, in which a human experience is given a complex imaginal representation involving both envisionment and enactment or miming. Two types of scales for measuring stylistic differences in these three, processes are presented in detail. One type of scale is drawn from subjects' ratings of the ease and speed with which images are aroused by concrete, abstract, or personal words respectively. The other type of scale is drawn from subjects' ratings of the vividness of images aroused by various phrases specifically written to tap one or other of the hypothesized imagery processes. Two experiments are described in which the three processes are differentially activated by instructions as well as by type of stimulus material. In both experiments the expected interaction effects (between instructions and type of material) are found with p <.001.

A human colon carcinoma cell line resistant to mitomycin C (MMC) was obtained by repeated exposure of a previously described sensitive parental line, HCT 116, to MMC in vitro. Xenografts grown from the MMC-resistant phenotype were not inhibited in MMC-treated animals, while MMC treatment produced growth inhibition in parental cell xenografts. The MMC-resistant phenotype exhibited a greater amount of a Mr 148,000 cell surface protein than did the parental line. The increase in this Mr 148,000 cell surface protein correlated positively with the degree of MMC resistance. Alkaline elution of filter-bound DNA from resistant cells exposed to MMC in vitro showed a decrease in DNA cross-link formation such that a 10-fold higher MMC concentration was required to produce similar cross-link formation in the resistant cell as compared to the parental cell. The development of MMC resistance was not associated with in vitro cross-resistance to other natural product cytotoxic drugs. This model for resistance to MMC will be useful in future studies to define the mechanisms for MMC action and resistance in human colon carcinoma cells.

The specific interaction between human N-acetylhexosaminidase and concanavalin A was evaluated with respect to temperature, time, pH and concentration of specific ligand in incubation mixtures containing the enzyme and insolubilized lectin. Elution of the enzyme from insolubilized concanavalin A is dependent on both temperature and concentration of alpha-methyl mannoside. Conditions for a high yield of the enzyme from chromatography on insolubilized concanavalin A are described.