Consistency between the ACGIH TLV for hand activity and proposed action levels for wrist velocity and forearm muscular load based on objective measurements: an example from the assembly industry.

Objectives. This study aimed to investigate the consistency between results of the American Conference for Governmental Occupational Hygienists (ACGIH) threshold limit value (TLV) for hand activity and proposed action levels of objective measurements in risk assessments of work-related musculoskeletal disorders. Methods. Wrist velocities and forearm muscular load were measured for 11 assemblers during one working day. Simultaneously, each assembler's hand activity level (HAL) during three sub-cycles was rated twice on two separate occasions by two experts, using a HAL scale. Arm/hand exertion was also rated by the assemblers themselves using a Borg scale. In total, 66 sub-cycles were assessed and assigned to three exposure categories: A) below ACGIH action limit (AL) (green); B) between AL and TLV (yellow); and C) above TLV (red). The median wrist velocity and the 90th percentile of forearm muscular load obtained from the objective measurements corresponding to the sub-cycles were calculated and assigned to two exposure categories: A) below or C) above the proposed action level. Results. The agreement between ACGIH TLV for hand activity and the proposed action level for wrist velocity was 87%. Conclusions. The proposed action level for wrist velocity is highly consistent with the TLV. Additional studies are needed to confirm the results.

Effects of cleaning spray use on eyes, airways, and ergonomic load.

BACKGROUND: Cleaning workers are exposed to chemicals and high physical workload, commonly resulting in airway problems and pain. In this study the response in the upper airways and the physical workload following airborne and ergonomic exposure of cleaning spray was investigated. METHODS: A survey was answered by professional cleaning workers to investigate their use of cleaning sprays and the perceived effects on eyes, airways and musculoskeletal pain. A human chamber exposure study was then conducted with 11 professional cleaning workers and 8 non-professional cleaning workers to investigate the airborne exposure, acute effects on eyes and airways, and physical load during cleaning with sprays, foam application and microfiber cloths premoistened with water. All cleaning products used were bleach, chlorine, and ammonia free. The medical assessment included eye and airway parameters, inflammatory markers in blood and nasal lavage, as well as technical recordings of the physical workload. RESULTS: A high frequency of spray use (77%) was found among the 225 professional cleaning workers that answered the survey. Based on the survey, there was an eight times higher risk (p < 0.001) of self-experienced symptoms (including symptoms in the nose, eyes and throat, coughing or difficulty breathing) when they used sprays compared to when they cleaned with other methods. During the chamber study, when switching from spray to foam, the airborne particle and volatile organic compound (VOC) concentrations showed a decrease by 7 and 2.5 times, respectively. For the whole group, the peak nasal inspiratory flow decreased (-10.9 L/min, p = 0.01) during spray use compared to using only water-premoistened microfiber cloths. These effects were lower during foam use (-4.7 L/min, p = 0.19). The technical recordings showed a high physical workload regardless of cleaning with spray or with water. CONCLUSION: Switching from a spraying to a foaming nozzle decreases the exposure of both airborne particles and VOCs, and thereby reduces eye and airway effects, and does not increase the ergonomic load. If the use of cleaning products tested in this study, i.e. bleach, chlorine, and ammonia free, cannot be avoided, foam application is preferable to spray application to improve the occupational environment.

Action Levels for the Prevention of Work-Related Musculoskeletal Disorders in the Neck and Upper Extremities: A Proposal.

There are several well-known risk factors for work-related musculoskeletal disorders (MSDs). Despite this knowledge, too many people still work in harmful conditions. The absence of occupational exposure limits (OELs) for physical workload impedes both supervision and preventive work. To prevent myalgia, tendon disorders, and nerve entrapments in the upper musculoskeletal system, we propose action levels concerning work postures, movement velocities and muscular loads recorded by wearable equipment. As an example, we propose that wrist velocity should not exceed 20°/s as a median over a working day. This has the potential to reduce the prevalence of carpal tunnel syndrome (CTS) in highly exposed male occupational groups by 93%. By reducing upper arm velocity in highly exposed female groups to the suggested action level 60°/s, the prevalence of pronounced neck/shoulder myalgia with clinical findings (tension neck syndrome) could be reduced by 22%. Furthermore, we propose several other action levels for the physical workload. Our ambition is to start a discussion concerning limits for physical workload, with the long-term goal that OELs shall be introduced in legislation. Obviously, the specific values of the proposed action levels can, and should, be discussed. We hope that quantitative measurements, combined with action levels, will become an integral part of systematic occupational health efforts, enabling reduction and prevention of work-related MSDs.

The effect of two types of maximal voluntary contraction and two electrode positions in field recordings of forearm extensor muscle activity during hotel room cleaning.

Purpose. This study aimed to investigate the effects of using hand grip or resisted wrist extension as the reference contraction, and two electrode positions, on field recordings of forearm extensor muscle activity. Materials and methods. Right forearm extensor muscle activity was recorded using two electrode pairs (over the most prominent part (position 2) and proximal to that (position 1)) during one working day in 13 female hotel housekeepers. Each subject performed the two maximal voluntary contractions (MVCs), and the electrical activity obtained during these (maximal voluntary electrical activity (MVE)) was used for normalization. Each set of recordings was analysed twice, once using hand grip as the MVC and once using resisted wrist extension. Results. Resisted wrist extension showed a higher group mean MVE than hand grip. Position 2 had higher correlation between MVE and force during the MVCs. The workload during cleaning was lower when using resisted wrist extension as reference than when using hand grip (24%MVE vs 46%MVE; p = 0.002 at position 2) for the 90th percentile. The workload (99th percentile) was overestimated in two subjects when using hand grip as reference. Conclusions. Problems associated with poorly activated forearm extensors can be overcome by using resisted wrist extension as reference.

Self-recordings of upper arm elevation during cleaning - comparison between analyses using a simplified reference posture and a standard reference posture.

BACKGROUND: To reduce ergonomic risk factors in terms of awkward and constrained postures and high velocities, it is important to perform adequate risk assessments. Technical methods provide objective measures of physical workload. These methods have so far mainly been used by researchers. However, if written instructions how to apply the sensors and how to adopt the reference posture are provided, together with triaxial accelerometers, it may be possible for employees to record their own physical workload. The exposure in terms of e.g. upper arm elevations could then easily be assessed for all workers in a workplace. The main aims of this study were: 1) to compare analyses for self-recording of upper arm elevation during work using a simplified reference posture versus using a standard reference posture, and 2) to compare the two reference postures. METHODS: Twenty-eight cleaners attached an accelerometer to their dominant upper arm and adopted a simplified reference according to a written instruction. They were thereafter instructed by a researcher to adopt a standard reference. Upper arm elevations were recorded for 2 or 3 days. Each recording was analysed twice; relative to the simplified reference posture and relative to the standard reference posture. The group means of the differences in recorded upper arm elevations between simplified and standard reference analyses were assessed using Wilcoxon signed ranks test. Furthermore, we calculated the group mean of the differences between the simplified reference posture and the standard reference posture. RESULTS: For arm elevation during work (50th percentile), the group mean of the differences between the two analyses was 0.2° (range -7 - 10°). The group mean of the differences between the two references was 9° (range 1 - 21°). The subjects were able to follow the instructions in the protocol and performed self-recording of upper arm elevation and velocity. CONCLUSIONS: The small difference between the two analyses indicates that recordings performed by employees themselves are comparable, on a group level, with those performed by researchers. Self-recordings in combination with action levels would provide employers with a method for risk assessment as a solid basis for prevention of work-related musculoskeletal disorders.

Assessments of Physical Workload in Sonography Tasks Using Inclinometry, Goniometry, and Electromyography.

BACKGROUND: Echocardiography involves strenuous postures of the upper limbs. This study explored the physical workload in the neck and upper limbs in sonographers performing echocardiography, and the extent to which the workload differs from than in other work tasks (other sonographic examinations, and nonsonographic tasks). METHODS: The physical load was assessed by inclinometry, goniometry, and electromyography methods in 33 female sonographers during authentic work using three different echocardiography techniques and other work tasks. RESULTS: Echocardiography was characterized by low velocities of the head, arms, and wrists, and a low proportion of muscular resting time in the forearms, in the transducer limb, and the computer limb. The transducer limb was more elevated in one of the techniques, but this technique also involved a higher proportion of muscular resting time of the trapezius muscle. We also found a high proportion of awkward wrist postures in the transducer wrist in all three techniques; in one due to prolonged flexion, and in the others due to prolonged extension. Other work tasks were less static, and were performed with higher upper arm and wrist velocities. CONCLUSION: None of the three echocardiography techniques was optimal concerning physical workload. Thus, to achieve more variation in physical load we recommend that the equipment be arranged so that the sonographer can alternate between two different techniques during the workday. We also propose alternation between echocardiography and nonsonographic tasks, in order to introduce variation in the physical workload. Clinical expertise should be used to achieve further improvements.

Comparing two methods to record maximal voluntary contractions and different electrode positions in recordings of forearm extensor muscle activity: Refining risk assessments for work-related wrist disorders.

BACKGROUND: Wrist disorders are common in force demanding industrial repetitive work. Visual assessment of force demands have a low reliability, instead surface electromyography (EMG) may be used as part of a risk assessment for work-related wrist disorders. For normalization of EMG recordings, a power grip (hand grip) is often used as maximal voluntary contraction (MVC) of the forearm extensor muscles. However, the test-retest reproducibility is poor and EMG amplitudes exceeding 100% have occasionally been recorded during work. An alternative MVC is resisted wrist extension, which may be more reliable. OBJECTIVE: To compare hand grip and resisted wrist extension MVCs, in terms of amplitude and reproducibility, and to examine the effect of electrode positioning. METHODS: Twelve subjects participated. EMG from right forearm extensors, from four electrode pairs, was recorded during MVCs, on three separate occasions. RESULTS: The group mean EMG amplitudes for resisted wrist extension were 1.2-1.7 times greater than those for hand grip. Resisted wrist extension showed better reproducibility than hand grip. CONCLUSIONS: The results indicate that the use of resisted wrist extension is a more accurate measurement of maximal effort of wrist extensor contractions than using hand grip and should increase the precision in EMG recordings from forearm extensor muscles, which in turn will increase the quality of risk assessments that are based on these.

Validity of a small low-cost triaxial accelerometer with integrated logger for uncomplicated measurements of postures and movements of head, upper back and upper arms.

Repetitive work and work in constrained postures are risk factors for developing musculoskeletal disorders. Low-cost, user-friendly technical methods to quantify these risks are needed. The aims were to validate inclination angles and velocities of one model of the new generation of accelerometers with integrated data loggers against a previously validated one, and to compare meaurements when using a plain reference posture with that of a standardized one. All mean (n = 12 subjects) angular RMS-differences in 4 work tasks and 4 body parts were <2.5° and all mean median angular velocity differences <5.0 °/s. The mean correlation between the inclination signal-pairs was 0.996. This model of the new generation of triaxial accelerometers proved to be comparable to the validated accelerometer using a data logger. This makes it well-suited, for both researchers and practitioners, to measure postures and movements during work. Further work is needed for validation of the plain reference posture for upper arms.

Cross-sectional associations between occupational factors and musculoskeletal pain in women teachers, nurses and sonographers.

BACKGROUND: It is usually assumed that musculoskeletal pain is associated with both the physical workload and the psychosocial work environment, as well as with personal and lifestyle factors. This study aims to ascertain the prevalence of musculoskeletal pain in women with varying or different occupational exposures, and to explore the associations between musculoskeletal pain and the occupational and personal factors. METHODS: A questionnaire on physical, psychosocial and individual factors was answered by 1591 women in five occupational groups with contrasting occupational exposures (teachers, anaesthetic, theatre, and assistant nurses, and sonographers). The outcome measure was musculoskeletal pain (in a new model based on frequency and intensity of complaints the preceding year) from the neck, shoulders, hands, lower back and feet. RESULTS: Neck pain was equally frequent among teachers, assistant nurses and sonographers, and less frequent in anaesthetic and theatre nurses. The sonographers experienced the highest prevalence of shoulder pain, while the assistant nurses were the most affected in the wrists and hands, lower back, and feet. The teachers reported the highest scores in most of the psychosocial dimensions. The theatre nurses scored highest in strenuous work postures and movements (mechanical exposure index, MEI), and the assistant nurses in physical activity and lifting (physical exposure index, PHYI). Multivariable models in the total population showed that both the physical workload and the psychosocial work environment were associated with pain in all body regions, though different factors affected different regions. Pain in the neck, shoulders, hands and lower back was strongly associated with a high MEI and high job demands, while pain in the feet was associated with a high PHYI and a high BMI. A young age was associated with pain in the neck, and an older age was associated with pain in the hands and feet. Lack of time for personal recovery was associated with pain in the shoulders and lower back. CONCLUSIONS: The occupational groups were affected differently and need different protective measures. For the teachers, the psychosocial work environment should be improved. The surgical staff and sonographers require measures to mitigate lifting and constrained postures.

Working spectacles for sorting mail.

BACKGROUND: Sorting mail into racks for postmen is visually demanding work. This can result in backward inclination of their heads, especially more pronounced for those who use progressive addition lenses. OBJECTIVE: To evaluate the effects of customized working spectacles on the physical workload of postmen. METHODS: Twelve male postmen sorted mail on two occasions: once using their private progressive spectacles and once using customized sorting spectacles with inverted progressive lenses. Postures and movements of the head, upper back, neck, and upper arms were measured by inclinometry. The muscular load of the trapezius was measured by surface electromyography. RESULTS: With the customized sorting spectacles, both the backward inclination of the head and backward flexion of the neck were reduced (3°), as well as the muscular load of the right upper trapezius, compared to sorting with private spectacles. However, with the sorting spectacles, there was a tendency for increased neck forward flexion, and increased sorting time. CONCLUSION: The reduction in work load may reduce the risk for developing work-related musculoskeletal disorders due to the positive reduction of the backward inclination of the head. But the tendency for increased neck forward flexion may reduce the positive effects. However, the magnitude of the possible reduction is difficult to predict, especially since quantitative data on exposure-response relationships are unknown. Alternative working spectacles with inverted near progressive lenses ought to be evaluated. They should still result in a positive reduced backward inclination of the head and may not cause any increased forward flexion.

Discrepancies in pain presentation caused by adverse psychosocial conditions as compared to pain due to high physical workload?

Disorders in the musculoskeletal system have been associated with a high physical workload as well as psychosocial and individual factors. It is however not obvious which of these factors that is most important to prevent. Musculoskeletal disorders in neck and upper extremity was assessed by interview and clinical examination in 79 teachers and 93 assisting nurses, all females. Psychosocial work environment was assessed by questionnaire. The physical workload was recorded by technical measurements of postures, movements and muscular load, in 9 teachers and 12 nurses. The physical workload was lower among the teachers, but they had a more demanding psychosocial work environment. Among the nurses, but not in the teachers, the neck-shoulder disorders were associated with a high body mass index (BMI). The teachers reported neck-shoulder complaints to a higher extent than the nurses, but had much lower prevalence of diagnoses in the clinical examination (12% vs. 25%; POR 0.3 CI 0.1 - 1.2; adjusted for age and BMI). The results suggest that adverse psychosocial conditions among the teachers give rise to a different kind of pain in the neck-shoulder region than from physical overload, troublesome but not as severe as the one afflicting the nurses.

Evidence for dimeric BACE-mediated APP processing.

beta-Secretase (BACE) is an aspartyl protease, which proteolytically processes amyloid precursor protein, making BACE an interesting pharmacological target in Alzheimer's disease. To study the enzymatic function of BACE, we mutated either of the two aspartic acid residues in the active site of BACE. This rendered BACE functionally inactive without affecting the degree of glycosylation or endosomal localization. In contrast, substituting both active site aspartic acid residues produced a functionally inactive, endoplasmic reticulum-retained and partially glycosylated BACE. Interestingly, co-expression of the two single active site mutants partially restored beta-site cleavage of amyloid precursor protein, and the restored activity was inhibited with similar dose-dependency and potency as wildtype BACE by a small molecule inhibitor raised against BACE. In sum, our data suggest that two different active site mutants can complement each other in a partially functional BACE dimer and mediate APP processing.

High levels of Notch signaling down-regulate Numb and Numblike.

Inhibition of Notch signaling by Numb is critical for many cell fate decisions. In this study, we demonstrate a more complex relationship between Notch and the two vertebrate Numb homologues Numb and Numblike. Although Numb and Numblike at low levels of Notch signaling negatively regulated Notch, high levels of Notch signaling conversely led to a reduction of Numb and Numblike protein levels in cultured cells and in the developing chick central nervous system. The Notch intracellular domain but not the canonical Notch downstream proteins Hes 1 and Hey 1 caused a reduction of Numb and Numblike. The Notch-mediated reduction of Numblike required the PEST domain in the Numblike protein and was blocked by the proteasome inhibitor MG132. Collectively, these observations reveal a reciprocal negative regulation between Notch and Numb/Numblike, which may be of relevance for stabilizing asymmetric cell fate switches and for tumor development.

Prolonged labour associated with lower expression of syndecan 3 and connexin 43 in human uterine tissue.

BACKGROUND: Prolonged labour is associated with greater morbidity and mortality for mother and child. Connexin 43 is a major myometrial gap junction protein found in human myometrium. Syndecan 3 seems to prevail in the human uterus among heparan sulphate proteoglycans, showing the most significant increase during labour. The aims of the present study were to investigate syndecan 3 and connexin 43 mRNA expressions and protein distributions in human uterine tissue during normal and prolonged labour. METHODS: Uterine isthmic biopsies were collected from non-pregnant (n = 7), term pregnant women not in labour (n = 14), in normal labour (n = 7) and in prolonged labour (n = 7). mRNA levels of syndecan 3 and connexin 43 were determined by real time RT-PCR. The localization and expression were demonstrated by immunohistochemistry and confocal microscopy. RESULTS: In women with prolonged labour, the mRNA expressions of syndecan 3 and Connexin 43 were considerably lower than the expression level at normal labour (p < 0.05). In term-pregnant tissue, the expression of syndecan 3 and connexin 43 did not differ significantly compared to non-pregnant and normal labour. The immunoreactivity of syndecan 3 was strong at normal labour, in contrast to prolonged labour, where both a weaker expression and an irregular distribution were detected. The immunoreactivity of connexin 43 increased until term and further stronger staining occurred at normal labour. At prolonged labour, the immunoreactivity was weaker and more unevenly distributed. At labour, a co-localization of syndecan 3 and connexin 43 could be demonstrated in the smooth muscle by confocal microscopy. CONCLUSION: The high expression of syndecan 3 and connexin 43 and their co-localization to the smooth muscle bundles during normal labour, together with the significant reduction in prolonged labour, may indicate a role for these proteins in the co-ordination of myometrial contractility.

Functional and phenotypical comparison of myofibroblasts derived from biopsies and bronchoalveolar lavage in mild asthma and scleroderma.

BACKGROUND: Activated fibroblasts, which have previously been obtained from bronchoalveolar lavage fluid (BALF), are proposed to be important cells in the fibrotic processes of asthma and scleroderma (SSc). We have studied the motility for BALF derived fibroblasts in patients with SSc that may explain the presence of these cells in the airway lumen. Furthermore, we have compared phenotypic alterations in activated fibroblasts from BALF and bronchial biopsies from patients with mild asthma and SSc that may account for the distinct fibrotic responses. METHODS: Fibroblasts were cultured from BALF and bronchial biopsies from patients with mild asthma and SSc. The motility was studied using a cell migration assay. Western Blotting was used to study the expression of alpha-smooth muscle actin (alpha-SMA), ED-A fibronectin, and serine arginine splicing factor 20 (SRp20). The protein expression pattern was analyzed to reveal potential biomarkers using two-dimensional electrophoresis (2-DE) and sequencing dual matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-TOF). The Mann-Whitney method was used to calculate statistical significance. RESULTS: Increased migration and levels of ED-A fibronectin were observed in BALF fibroblasts from both groups of patients, supported by increased expression of RhoA, Rac1, and the splicing factor SRp20. However, these observations were exclusively accompanied by increased expression of alpha-SMA in patients with mild asthma. Compared to BALF fibroblasts in mild asthma, fibroblasts in SSc displayed a differential protein expression pattern of cytoskeletal- and scavenger proteins. These identified proteins facilitate cell migration, oxidative stress, and the excessive deposition of extracellular matrix observed in patients with SSc. CONCLUSION: This study demonstrates a possible origin for fibroblasts in the airway lumen in patients with SSc and important differences between fibroblast phenotypes in mild asthma and SSc. The findings may explain the distinct fibrotic processes and highlight the motile BALF fibroblast as a potential target cell in these disorders.

CLAC binds to aggregated Abeta and Abeta fragments, and attenuates fibril elongation.

Deposition of amyloid beta-peptide (Abeta) into amyloid plaques is one of the invariant neuropathological features of Alzheimer's disease. Proteins that codeposit with Abeta are potentially important for the pathogenesis, and a recently discovered plaque-associated protein is the collagenous Alzheimer amyloid plaque component (CLAC). In this study, we investigated the molecular interactions between Abeta aggregates and CLAC using surface plasmon resonance spectroscopy and a solid-phase binding immunoassay. We found that CLAC binds to Abeta with high affinity, that the central region of Abeta is necessary and sufficient for CLAC interaction, and that the aggregation state of Abeta as well as the presence of negatively charged residues is important. We also show that this binding results in a reduced rate of fibril elongation. Taken together, we suggest that CLAC becomes involved at an intermediate stage in the pathogenesis by binding to Abeta fibrils, including fibrils formed from peptides with truncated N- or C-termini, and thereby slows their growth.

Collagenous Alzheimer amyloid plaque component assembles amyloid fibrils into protease resistant aggregates.

Recently, a novel plaque-associated protein, collagenous Alzheimer amyloid plaque component (CLAC), was identified in brains from patients with Alzheimer's disease. CLAC is derived from a type II transmembrane collagen precursor protein, termed CLAC-P (collagen XXV). The biological function and the contribution of CLAC to the pathogenesis of Alzheimer's disease and plaque formation are unknown. In vitro studies indicate that CLAC binds to fibrillar, but not to monomeric, amyloid beta-peptide (Abeta). Here, we examined the effects of CLAC on Abeta fibrils using assays based on turbidity, thioflavin T binding, sedimentation analysis, and electron microscopy. The incubation of CLAC with preformed Abeta fibrils led to increased turbidity, indicating that larger aggregates were formed. In support of this contention, more Abeta was sedimented in the presence of CLAC, as determined by gel electrophoresis. Moreover, electron microscopy revealed an increased amount of Abeta fibril bundles in samples incubated with CLAC. Importantly, the frequently used thioflavin T-binding assay failed to reveal these effects of CLAC. Digestion with proteinase K or trypsin showed that Abeta fibrils, incubated together with CLAC, were more resistant to proteolytic degradation. Therefore, CLAC assembles Abeta fibrils into fibril bundles that have an increased resistance to proteases. We suggest that CLAC may act in a similar way in vivo.

Functional Notch signaling is required for BMP4-induced inhibition of myogenic differentiation.

The bone morphogenetic protein (BMP) and Notch signaling pathways are crucial for cellular differentiation. In many cases, the two pathways act similarly; for example, to inhibit myogenic differentiation. It is not known whether this inhibition is caused by distinct mechanisms or by an interplay between Notch and BMP signaling. Here we demonstrate that functional Notch signaling is required for BMP4-mediated block of differentiation of muscle stem cells, i.e. satellite cells and the myogenic cell line C2C12. Addition of BMP4 during induction of differentiation dramatically reduced the number of differentiated satellite and C2C12 cells. Differentiation was substantially restored in BMP4-treated cultures by blocking Notch signaling using either the gamma-secretase inhibitor L-685,458 or by introduction of a dominant-negative version of the Notch signal mediator CSL. BMP4 addition to C2C12 cells increased transcription of two immediate Notch responsive genes, Hes1 and Hey1, an effect that was abrogated by L-685,458. A 3 kb Hey1-promoter reporter construct was synergistically activated by the Notch 1 intracellular domain (Notch 1 ICD) and BMP4. The BMP4 mediator SMAD1 mimicked BMP activation of the Hey1 promoter. A synthetic Notch-responsive promoter containing no SMAD1 binding sites responded to SMAD1, indicating that DNA-binding activity of SMAD1 is not required for activation. Accordingly, Notch 1 ICD and SMAD1 interacted in binding experiments in vitro. Thus, the data presented here provide evidence for a direct interaction between the Notch and BMP signaling pathways, and indicate that Notch has a crucial role in the execution of certain aspects of BMP-mediated differentiation control.

Cross-talk between the Notch and TGF-beta signaling pathways mediated by interaction of the Notch intracellular domain with Smad3.

The Notch and transforming growth factor-beta (TGF-beta) signaling pathways play critical roles in the control of cell fate during metazoan development. However, mechanisms of cross-talk and signal integration between the two systems are unknown. Here, we demonstrate a functional synergism between Notch and TGF-beta signaling in the regulation of Hes-1, a direct target of the Notch pathway. Activation of TGF-beta signaling up-regulated Hes-1 expression in vitro and in vivo. This effect was abrogated in myogenic cells by a dominant-negative form of CSL, an essential DNA-binding component of the Notch pathway. TGF-beta regulated transcription from the Hes-1 promoter in a Notch-dependent manner, and the intracellular domain of Notch1 (NICD) cooperated synergistically with Smad3, an intracellular transducer of TGF-beta signals, to induce the activation of synthetic promoters containing multimerized CSL- or Smad3-binding sites. NICD and Smad3 were shown to interact directly, both in vitro and in cells, in a ligand-dependent manner, and Smad3 could be recruited to CSL-binding sites on DNA in the presence of CSL and NICD. These findings indicate that Notch and TGF-beta signals are integrated by direct protein-protein interactions between the signal-transducing intracellular elements from both pathways.