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Background: Immune checkpoint inhibitors (ICIs) have revolutionized non-small cell lung cancers (NSCLCs) treatment, but only 20-30% of patients benefit from these treatments. Currently, PD-L1 expression in tumor cells is the only clinically approved predictor of ICI response in lung cancer, but concerns arise due to its low negative and positive predictive value. Recent studies suggest that CXCL13+ T cells in the tumor microenvironment (TME) may be a good predictor of response. We aimed to assess if CXCL13+ cell localization within the TME can predict ICI response in advanced NSCLC patients. Methods: This retrospective study included 65 advanced NSCLC patients treated with Nivolumab/Pembrolizumab at IUCPQ or CHUM and for whom a pretreatment surgical specimen was available. Good responders were defined as having a complete radiologic response at 1 year, and bad responders were defined as showing cancer progression at 1 year. IHC staining for CXCL13 was carried out on a representative slide from a resection specimen, and CXCL13+ cell density was evaluated in tumor (T), invasive margin (IM), non-tumor (NT), and tertiary lymphoid structure (TLS) compartments. Cox models were used to analyze progression-free survival (PFS) and overall survival (OS) probability, while the Mann-Whitney test was used to compare CXCL13+ cell density between responders and non-responders. Results: We showed that CXCL13+ cell density localization within the TME is associated with ICI efficacy. An increased density of CXCL13+ cells across all compartments was associated with a poorer prognostic (OS; HR = 1.22; 95%CI = 1.04-1.42; p = 0.01, PFS; HR = 1.16; p = 0.02), or a better prognostic when colocalized within TLSs (PFS; HR = 0.84, p = 0.03). Conclusion: Our results support the role of CXCL13+ cells in advanced NSCLC patients, with favorable prognosis when localized within TLSs and unfavorable prognosis when present elsewhere. The concomitant proximity of CXCL13+ and CD20+ cells within TLSs may favor antigen presentation to T cells, thus enhancing the effect of PD-1/PD-L1 axis inhibition. Further validation is warranted to confirm the potential relevance of this biomarker in a clinical setting.

Objectives: Venous thrombotic events (VTEs) are a frequent complication of non-small cell lung cancer (NSCLC) and are associated with increased morbidity. Immune checkpoint inhibitors (ICIs) are revolutionizing the management of NSCLC, but little is known about their impact on thrombosis. This study aims to define the incidence and clinical relevance of VTEs in NSCLC patients receiving these treatments., Methods: A retrospective multicentric cohort study including 593 patients from three centers in Canada and France was performed. The cumulative incidence of VTEs after ICIs was estimated using competing risk analysis, and the association of these events with survival and response to treatment was determined. Finally, univariate and multivariate tests were performed to identify VTE risk factors., Results: The cumulative incidence of VTEs in the cohort was 14.8% (95% CI = 7.4-22.2%) for an incidence rate of 76.5 (95% CI = 59.9-97.8) thrombosis per 1000 person-years, with most thromboses occurring rapidly after treatment initiation. VTEs were not correlated with overall survival, progression-free survival, or objective response to ICIs. Age ˂ 65 years old (HR = 2.00; 95% CI = 1.11-3.59) and tumors with PD-L1 1-49% (HR = 3.36; 95% CI = 1.19-9.50) or PD-L1 ≥ 50% (HR = 3.22; 95% CI = 1.21-8.57) were associated with more VTEs after 12 months of ICI initiation. Also, a delay of less than 12 months from diagnosis to the first ICI treatment (HR = 2.06; 95% CI = 1.09-3.89) and active smoking (HR = 2.00; 95% CI = 1.12-3.58) are probable risk factors of VTEs., Conclusion: This study suggests that the incidence of VTEs in NSCLC patients treated with ICIs is comparable to what is reported in other cohorts of patients treated with chemotherapy. In our cohort, VTEs were not associated with a decreased survival or response to therapy. Patient age < 65 and tumors with PD-L1 ≥ 1% were associated with a higher risk of VTEs under ICIs., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Importance: Adults with sickle cell disease (SCD) disproportionally experience early cognitive decline; however, guidance on the optimal screening strategy for cognitive dysfunction is lacking, and several available tools are biased by language, educational level, socioeconomic status, and race/ethnicity. The Rowland Universal Dementia Assessment Scale (RUDAS) was specifically designed for cognitive screening in multicultural populations., Objective: To ascertain the prevalence of suspected dementia in adults with SCD using the RUDAS, and to identify whether age, sex, educational level, several biological variables, and SCD complications were associated with RUDAS scores., Design, Setting, and Participants: This multicenter, bilingual, cross-sectional study was conducted in 2 SCD comprehensive care centers in Canada (Centre Hospitalier de l'Université Montréal in Montréal and University Health Network in Toronto). Participants were adults aged 18 years or older and were enrolled in the study between July 1, 2018, and July 30, 2019. All outpatients were eligible and offered study participation, unless they had an acute medical condition that required inpatient care or they were unable to follow study instructions., Interventions: The RUDAS was administered by trained personnel in either French or English, according to the patient's language preference. A questionnaire on social determinants of health was also administered, and participants underwent screening for anxiety and depression., Main Outcomes and Measures: Proportion of participants with RUDAS scores that were suggestive of dementia and the RUDAS score. Any score lower than 23 points was suggestive of dementia, a score between 23 and 27 points indicated a possible association with mild neurocognitive disorder, and a score higher than 27 points was normal., Results: A total of 252 adult patients with SCD were included (136 women [54.0%]; mean [range] age, 34.8 [18-75] years). Overall, 29 patients (11.5%) had RUDAS scores that were suggestive of dementia, and this proportion increased with age (15 [8.7%] in the 18-39 years age group, 10 [14.5%] in the 40-59 years age group, and 4 [36.4%] in the ≥60 years age group). The RUDAS scores were not associated with sex, language, SCD genotype, and SCD complications. The highest level of education was significantly associated with the RUDAS score; however, the association was small (η2 = 0.02; 95% CI, 0.00-0.07; P = .02). In a multivariable analysis, lower glomerular filtration rate (r = 0.40; 95% CI, 0.29-0.50; P < .001) and increasing age (r = -0.37; 95% CI, -0.47 to -0.26; P < .001), but not SCD genotype or disease severity, were associated with lower RUDAS scores., Conclusions and Relevance: This study found that using the RUDAS revealed a high prevalence of suspected dementia in adult patients with SCD that was associated with worsening kidney function and age. Cognition should be screened in all adult patients with SCD, regardless of age, disease severity, and SCD genotype; further validation of the RUDAS is ongoing.

Purpose: Bracing is the treatment of choice for idiopathic scoliosis (IS), unfortunately factors underlying brace response remain unknown. Clinicians are currently unable to identify patients who may benefit from bracing, and therefore, better molecular stratification is critically needed. The aim of this study is to evaluate IS patient outcomes at skeletal maturity in relation to biological endophenotypes, and determine specific endophenotypes associated to differential bracing outcomes. This is a retrospective cohort with secondary cross-sectional comparative studies., Methods: Clinical and radiological data were collected from 563 IS patients, stratified into biological endophenotypes (FG1, FG2, FG3) based on a cell-based test. Measured outcomes were maximum Cobb angle at skeletal maturity, and if severe, spinal deformity (≥ 45°) or surgery was attained. Treatment success/failure was determined by standard progression thresholds (Cobb ≥ 45° or surgery; Cobb angle progression ≥ 6°). Multivariable analyses were performed to evaluate associations between endophenotypes and clinical outcome., Results: Higher Cobb angles at maturity for FG1 and FG2 patients were observed (p = 0.056 and p = 0.05), with increased likelihood of ≥ 45° and/or surgery for FG1 (OR = 2.181 [1.002-4.749] and FG2 (OR = 2.141 [1.038-4.413]) compared to FG3. FG3 was 9.31 [2.58-33.61] and 5.63 [2.11-15.05] times more likely for bracing success at treatment termination and based on the < 6° progression criterion, respectively, compared to FG1., Conclusion: Associations between biological endophenotypes and outcomes suggest differences in progression and/or bracing response among IS patients. Outcomes were most favorable in FG3 patients. The results pave the way for establishing personalized treatments, distinguishing who may benefit or not from treatment.

Study Design: Feasibility study to compare the effectiveness of 2 brace design and fabrication methods for treatment of adolescent idiopathic scoliosis: a standard plaster-cast method and a computational method combining computer-aided design and fabrication and finite element simulation., Objectives: To improve brace design using a new brace design method., Summary of Background Data: Initial in-brace correction and patient's compliance to treatment are important factors for brace efficiency. Negative cosmetic appearance and functional discomfort resulting from pressure points, humidity, and restriction of movement can cause poor compliance with the prescribed wearing schedule., Methods: A total of 15 consecutive patients with brace prescription were recruited. Two braces were designed and fabricated for each patient: a standard thoracolumbo-sacral orthosis brace fabricated using plaster-cast method and an improved brace for comfort (NewBrace) fabricated using a computational method combining computer-aided design and fabrication software (Rodin4D) and a simulation platform. Three-dimensional reconstructions of the torso and the trunk skeleton were used to create a personalized finite element model, which was used for brace design and predict correction. Simulated pressures on the torso and distance between the brace and patient's skin were used to remove ineffective brace material situated at more than 6 mm from the patient's skin. Biplanar radiographs of the patient wearing each brace were taken to compare their effectiveness. Patients filled out a questionnaire to compare their comfort., Results: NewBraces were 61% thinner and had 32% less material than standard braces with equivalent correction. NewBraces were more comfortable (11 of 15 patients) or equivalent to (4 of 15 cases) standard braces. Simulated correction was simulated within 5° compared with in-brace results., Conclusions: This study demonstrates the feasibility of designing lighter and more comfortable braces with correction equivalent to standard braces. This design platform has the potential to further improve brace correction efficiency and its compliance., (Copyright © 2014 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.)

Background: A numerical based brace design platform, including biomechanical simulation, Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) was developed to rationalize braces for the treatment of adolescent idiopathic scoliosis. The objective of this study was to test the feasibility of the approach and assess the effectiveness of braces issued from this platform as compared to standard brace design., Methods: The biomechanical finite element model was built using the 3D reconstruction of the trunk skeleton from bi-planar radiographs and of the torso surface from surface topography. The finite element model is linked to a CAD/CAM software (Rodin4D), allowing the iterative design and simulation of the correction provided by the brace, as well as predicting pressures exerted on the torso. The resulting brace design was then fabricated using a numerical controlled carver. A brace designed using this platform (New Brace) as well as a standard thoraco-lumbo-sacral orthosis (Standard Brace) were built for six scoliotic patients. Both brace effectiveness was assessed using radiographs and compared to the simulations., Findings: The New Brace corrected on average the spine deformities within 5° of Cobb angle of the simulated correction and with a similar correction as compared to the Standard Brace (average correction of 16° vs. 11° (MT); P=0.1 and 13° vs. 16° (TL/L); P=0.5 for the Standard Brace and the New Brace respectively). The two braces had a similar 10° lordosing effect of the thoracic curve. The coronal balance was quite similar (7.3 vs. 6.8mm balance improvement respectively for New Brace vs. Standard Brace)., Interpretation: These first clinical results showed the feasibility of building computer-assisted braces, equivalent to standard orthosis. An extended study on more cases is under way to fully assess this new design paradigm, which in the long term would allow improving brace design and rationalize the conservative treatments of scoliosis., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The molecules involved in vertebrate tendon formation during development remain largely unknown. To date, only two DNA-binding proteins have been identified as being involved in vertebrate tendon formation, the basic helix-loop-helix transcription factor Scleraxis and, recently, the Mohawk homeobox gene. We investigated the involvement of the early growth response transcription factors Egr1 and Egr2 in vertebrate tendon formation. We established that Egr1 and Egr2 expression in tendon cells was correlated with the increase of collagen expression during tendon cell differentiation in embryonic limbs. Vertebrate tendon differentiation relies on a muscle-derived FGF (fibroblast growth factor) signal. FGF4 was able to activate the expression of Egr genes and that of the tendon-associated collagens in chick limbs. Egr gene misexpression experiments using the chick model allowed us to establish that either Egr gene has the ability to induce de novo expression of the reference tendon marker scleraxis, the main tendon collagen Col1a1, and other tendon-associated collagens Col3a1, Col5a1, Col12a1, and Col14a1. Mouse mutants for Egr1 or Egr2 displayed reduced amounts of Col1a1 transcripts and a decrease in the number of collagen fibrils in embryonic tendons. Moreover, EGR1 and EGR2 trans-activated the mouse Col1a1 proximal promoter and were recruited to the tendon regulatory regions of this promoter. These results identify EGRs as novel DNA-binding proteins involved in vertebrate tendon differentiation by regulating type I collagen production.

Size and scale issues present a complexity problem in visualizing detailed 3D models built from sensor data. A model of Leonardo da Vinci's Mona Lisa, with its thin pictorial layer, illustrates the need for intuitive real-time processing tools that are seamlessly integrated with a multiresolution visualization environment.

The combinatorial action of separate cis-acting elements controls the cell-specific expression of type I collagen genes. In particular, we have shown that two short elements located between -3.2 and -2.3 kb and named TSE1 and TSE2 are needed for expression of the mouse COL1a1 gene in tendon fibroblasts. In this study, we analyzed the trans-acting factors binding to TSE1 and TSE2. Gel shift experiments showed that scleraxis (SCX), which is a basic helix-loop-helix transcription factor that is expressed selectively in tendon fibroblasts, binds TSE2, preferentially as a SCX/E47 heterodimer. In transfection experiments, overexpression of SCX and E47 strongly enhanced the activity of reporter constructs harboring either four copies of TSE2 cloned upstream of the COL1a1 minimal promoter or a 3.2-kb segment of the COL1a1 proximal promoter. Analysis of TSE1 showed that it contains a consensus binding site for NFATc transcription factors. This led us to show that the NFATc4 gene is expressed in tendons of developing mouse limbs and in TT-D6 cells, a cell line that has characteristics of tendon fibroblasts. In gel shift assays, TSE1 bound NFATc proteins present in nuclear extracts from TT-D6 cells. In transfection experiments, overexpression of NFATc transactivated a reporter construct harboring four copies of TSE1 cloned upstream of the COL1a1 minimal promoter. By contrast, inhibition of the nuclear translocation of NFATc proteins in TT-D6 cells strongly inhibited the expression of the COL1a1 gene. Taken together, these results suggest that SCX and NFATc4 cooperate to activate the COL1a1 gene specifically in tendon fibroblasts.

Dysfunctional beliefs and attitudes about sleep are presumed to play an important mediating role in perpetuating insomnia. The present study evaluated the impact of cognitive-behavioral and pharmacological treatments for insomnia on sleep-related beliefs and attitudes and the relationship between those changes and sleep improvements. The participants were older adults with chronic and primary insomnia. They received cognitive-behavior therapy (CBT), pharmacotherapy (PCT), combined CBT+PCT (COMB), or a medication placebo (PLA). In addition to daily sleep diaries and sleep laboratory measures, the participants completed the dysfunctional beliefs and attitudes about sleep scale (DBAS) at baseline and posttreatment, and at 3-, 12- and 24-month follow-up assessments. The results showed that CBT and COMB treatments produced greater improvements of beliefs and attitudes about sleep at posttreatment than PCT and PLA. Reductions of DBAS scores were significantly correlated with improvements of sleep efficiency as measured by daily sleep diaries and by polysomnography. In addition, more adaptive beliefs and attitudes about sleep at posttreatment were associated with better maintenance of sleep improvements at follow-ups. These findings highlight the importance of targeting sleep-related beliefs and attitudes in the treatment of insomnia.

Objective: To evaluate the prevalence of insomnia and the treatments used by patients attending general practice clinics., Design: Survey of outpatients., Setting: Quebec city, Que. metropolitan area., Participants: Two hundred eighteen patients recruited in waiting rooms of general practice clinics., Main Outcome Measures: Participants completed a survey on sleep and use of substances for insomnia, a questionnaire documenting their medical history and use of health care services, and three indices measuring presence of worry and symptoms of anxiety and depression., Result: Close to 38% of respondents suffered from insomnia: 26.2% had chronic insomnia and 11.4% had short-term insomnia. Prevalence was higher among women and people 35 to 54 years old. Among respondents who used substances to help them sleep, those 55 years and older consumed more prescription and medications (benzodiazepines); those 35 to 54 years old used mainly natural products; and those 16 to 34 years old consumed mainly over-the-counter medications. Respondents suffering from insomnia made heavier use of health care services and reported more worry and symptoms of anxiety and depression than those who slept well., Conclusion: Patients attending general practice clinics have a high prevalence of insomnia. Physicians must be on the lookout for these sleep disturbances so they can offer appropriate treatment.

Objective: Treatment of tuberculosis is a time-consuming and expensive process, often complicated by patient non-adherence. Directly observed therapy (DOT), an out-patient management strategy designed to ensure adherence, is not widely used because it is perceived to be too expensive. This study compared costs of tuberculosis treatment in DOT to the same factors in traditional therapy., Design: A retrospective economic evaluation of 659 tuberculosis cases was reported to a major metropolitan county public health department between 1980 and 1994. Out-patient costs, in-patient costs and the cost impact of relapse and acquired resistance were estimated in 1995 dollars., Results: Treatment costs were lower with DOT: $15,670 per case for in-patient care and $700 per case for out-patient care (P < 0.001). These cost differences resulted from shorter therapy duration (334 vs 550 days), fewer patient hospitalizations (58 vs 75%) and shorter hospital stays (26 vs 55 days per hospitalized patient). Relapse or acquired resistance occurred in 10.9% of patients and accounted for 35.7% of cost with traditional therapy, as compared to 1.2% of patients and 6.0% of cost with observed therapy., Conclusions: Directly observed therapy is less costly than traditional therapy.

The present study's main objective is to examine whether problem orientation and problem-solving skills differ according to generalized anxiety disorder (GAD) symptom level or clinical status (seeking help for GAD). Its secondary goal is to examine whether two cognitive variables (intolerance of uncertainty and beliefs about worry) vary according to GAD symptom level or clinical status. Three groups of subjects participated in the study: (a) nonclinical moderate worriers (N = 15), (b) nonclinical subjects meeting GAD criteria by questionnaire (N = 14), and (c) GAD patients (N = 14). Problem orientation and problem-solving skills were measured with the Social Problem-Solving Inventory (D'Zurilla & Nezu, 1990) and the Problem-Solving Inventory (Heppner & Petersen, 1982), whereas the cognitive variables were assessed with the Intolerance of Uncertainty questionnaire (Freeston, Rhéaume, Letarte, Dugas, & Ladouceur, 1994) and the Why Worry? questionnaire (Freeston, Rhéaume et al., 1994). The results show that problem orientation, intolerance of uncertainty, and beliefs about worry were similar in subjects meeting GAD criteria by questionnaire and GAD patients, whereas moderate worriers had different scores on these variables. Thus, these variables are more highly affected by GAD symptom level than by clinical status. The results also show that problem-solving skills were unaffected by symptom level and clinical status, thereby indicating that knowledge of problem-solving skills is unrelated to both GAD symptom level and GAD clinical status. The findings are discussed in terms of their theoretical and clinical implications.

Insomnia is a widespread problem impairing daytime functioning and carrying important social and economic costs. No valid instrument exists in French to assess sleep difficulties. Two studies assess the French translation of three insomnia measures. The Pittsburgh Sleep Quality Index (PSQI), the Sleep Impairment Rating Scales (SIRS) and the Beliefs and Attitudes about Sleep (BAS) questionnaires were selected according to their clinical utility. Study one established the inferential translation of the preliminary versions with six expert judges. The empirical equivalence of the original and translated versions were confirmed with bilingual nonclinical sample. Study two assessed the fidelity and convergent validity of these instruments with a nonclinical French sample. The results showed adequate internal consistency; test-retest fidelity for a two-week interval was acceptable. The findings on convergent validity are also appropriate. While future research is necessary to confirm their psychometric properties, these questionnaires are good measures to assess insomnia in a research or clinical context.

Background: Tuberculosis has reemerged as an important public health problem, and the frequency of drug resistance is increasing. A major reason for the development of resistant infections and relapse is poor compliance with medical regimens. In Tarrant County, Texas, we initiated a program of universal directly observed treatment for tuberculosis. We report the effect of the program on the rates of primary and acquired drug resistance and relapse among patients with tuberculosis., Methods: We collected information on all patients with positive cultures for Mycobacterium tuberculosis in Tarrant County from January 1, 1980, through December 31, 1992. Through October 1986, patients received a traditional, unsupervised drug regimen. Beginning in November 1986, nearly all patients received therapy under direct observation by health care personnel., Results: A total of 407 episodes in which patients received traditional treatment for tuberculosis (January 1980 through October 1986) were compared with 581 episodes in which therapy was directly observed (November 1986 through December 1992). Despite higher rates of intravenous drug use and homelessness and an increasing rate of tuberculosis during this 13-year period, the frequency of primary drug resistance decreased from 13.0 percent to 6.7 percent (P < 0.001) after the institution of direct observation of therapy, and the frequency of acquired resistance declined from 14.0 percent to 2.1 percent (P < 0.001). The relapse rate decreased from 20.9 percent to 5.5 percent (P < 0.001), and the number of relapses with multidrug-resistant organisms decreased from 25 to 5 (P < 0.001)., Conclusions: The administration of therapy for M. tuberculosis infection under direct observation leads to significant reductions in the frequency of primary drug resistance, acquired drug resistance, and relapse.

This monthly series was developed from the AOA Task Force on AIDS Writers' Workshop, held August 16 to 18, 1991, in New York. The workshop was sponsored by an education grant from Burroughs Wellcome. It will provide brief clinical updates and perspectives on the human immunodeficiency virus (HIV). Readers may request tear sheets from the AOA editorial offices.

This monthly series was developed from the AOA Task Force on AIDS Writers' Workshop, held August 16 to 18, 1991, in New York. The workshop was sponsored by an education grant from Burroughs Wellcome. It will provide brief clinical updates and perspectives on the human immunodeficiency virus (HIV). Readers may request tear sheets from the AOA editorial offices.

This monthly series was developed from the AOA Task Force on AIDS Writers' Workshop, held August 16 to 18, 1991, in New York. The workshop was sponsored by an educational grant from Burroughs Wellcome. It will provide brief clinical updates and perspectives on the human immunodeficiency virus (HIV). Readers may request tear sheets from the AOA editorial offices.

Coumarin skin necrosis is a rare and usually unpredictable complication of coumarin therapy, occasionally leading to death. Onset is usually between the third and sixth day of coumarin therapy. The patient most commonly complains of pain in a region of abundant subcutaneous fat, with progression to erythema, petechiae, and gangrenous necrosis. Thrombosis of the dermal and the subcutaneous veins is demonstrated pathologically. We describe a case and review the pathogenesis, treatment, and prevention of this lesion.

Although there are no prospective studies regarding the frequency of postviral bronchial hyperreactivity syndrome, it is a common complication of upper and lower respiratory tract viral infections. The respiratory symptoms closely resemble those of asthma, but they are present for only 3 weeks to 3 months following the acute infection phase. Defining the mechanisms of this syndrome may provide insight into the pathogenesis of asthma. Postviral bronchial hyperreactivity syndrome is frequently misdiagnosed and inappropriately managed because many physicians are unfamiliar with this illness. Because of its characteristic history, diagnosis is straightforward when the physician knows what to look for, and response to therapy is excellent. This report presents a case history followed by a review of the proposed mechanisms of bronchial hyperreactivity following viral respiratory infections. The clinical features and criteria for diagnosing postviral bronchial hyperreactivity syndrome are also discussed.

The duration of handwashing was studied in two community hospitals (teaching and nonteaching). The duration in seconds of 180 handwashes by health care personnel and 52 handwashes by non-health care personnel were recorded. The mean duration for health care personnel was 8.62 +/- 0.29 SEM; the degree of patient contact did not influence the duration of handwashing. The duration of handwashing was two times longer in health care personnel vs. non-health care personnel (8.62 +/- 0.29 vs. 4.14 +/- 0.42; t = 7.7; p less than 0.001). Comparisons revealed no statistically significant difference in duration between personnel at teaching and nonteaching hospitals or among those in different occupations. The data indicate that the duration of handwashing among health care personnel is below the standard recommended by authorities in hospital infection control. This may be an important factor in the transmission and persistence of nosocomial infection in critical care units. The antimicrobial efficacy of handwashing agents should be reevaluated considering the actual duration of handwashing by health care personnel within the hospital environment or efforts should be made to increase the duration of handwashing.

We studied the association between the movement of operating room personnel and bacterial contamination of the operative field during 12 clean operations. Settle plates placed on the patient's chest and instrument table were exposed during the operation. As a control, settle plates were exposed in the same locations when no personnel and patients were in the room. Bacterial contamination of the aseptic field was categorized as disseminating (Group A: greater than 42 combined movements) and nondisseminating (Group B: less than 42 combined movements). There were 24 persons in each group. There was a highly significant difference between the two groups in the colony counts on settling plates. More vigorous movement was associated with increased bacterial contamination of the operative field. Low bacterial colony counts were found in the control plates, ruling out environmental sources of contamination. Bacterial fallout correlated with the movement of personnel. Measures to reduce excessive movement in the OR are recommended.