Activity Patterns In Relation Research Articles

Patterns of cell signaling pathway activation that characterize mammary development

Previous work has detailed the histological and biochemical changes associated with mammary development and remodeling. We have now made use of gene expression profiling, and in particular of the previously described signatures of cell signaling pathway activation, to explore the events associated with mammary gland development. We find that there is elevated E2F-specific pathway activity prior to lactation and relatively low levels of other important signaling pathways, such as RAS, MYC and SRC. Upon lactation and continuing into the involution phase, these patterns reverse with a dramatic increase in RAS, SRC and MYC pathway activity and a decline in E2F activity. At the end of involution, these patterns return to that of the adult non-lactating mammary gland. The importance of the changes in E2F pathway activity, particularly during the proliferative phase of mammary development, was confirmed through the analysis of mice deficient for various E2F proteins. Taken together, these results reveal a complex pattern of pathway activity in relation to the various phases of mammary gland development.

Digestive Enzyme Assays In The Gut Of Oreochromis Niloticus Linnaeus 1757, Parachanna (Channa) Obscura Gunther 1861 And Gymnarchus Niloticus Cuvier 1829

Digestive enzyme assays in the different gut regions (oesophagus, stomach, caecum, duodenum, ileum, and rectum) of three commercial African freshwater fish species: Nile tilapia Oreochromis niloticus, African snakehead fish Parachanna obscura, and African long knife fish, Gymnarchus niloticus, revealed an array of glycosidases (amylase, sucrase, maltase, lactase, and cellulase); proteases (chymotrypsin, pepsin, and trypsin) and lipases. The pattern of distribution and relative activity of the enzymes showed that the fishes are capable of digesting carbohydrates, proteins and lipids such that they complemented the different dietary habits of the three fish species. Enzyme activity was not detected in the oesophagus and rectum of the three fish species. The relative distribution and activity of the various enzymes were possibly induced by the nutritional requirements of the fishes.

Variability of Spanish adolescents’ physical activity patterns by seasonality, day of the week and demographic factors

In this study, we examined the variability of physical activity (and inactivity) patterns in relation to gender, age, type of school, day of the week, and season of the year among a sample of Spanish adolescents aged 12–16 years. Levels of physical activity engagement, “who” was active/inactive, and “when” they were active/inactive were addressed. A Spanish translation and modification of Cale's Four by One-Day Physical Activity Questionnaire was administered by interviewer to 323 participants to measure estimated energy expenditure. Activity was assessed for two weekdays and two weekend days on two occasions during the autumn and two occasions during the winter. In an effort to better describe adolescents’ active/inactive lifestyles, energy expenditures were translated into physical activity categories (i.e. active, moderately active, inactive, and very inactive). Results revealed that mean adolescent total daily energy expenditure was 41.46 kcal·kg−1·day−1 (s=7.05), which corresponded to the “active” category. Factorial and mixed analyses of variance showed statistically significant differences in energy expenditure by gender, season, day of the week, and type of school (P<0.001). Female adolescents spent less daily energy than their male counterparts and, consequently, they were less active overall, even though they were more moderately active than boys. Participants were more active in winter than in autumn, which was largely due to the accumulation of time engaged in more lifestyle activities than differences in strenuous exercise. Adolescents were also less active on weekdays than during weekends. An interaction effect emerged for day of the week and type of school with adolescents attending public (or state) schools presenting higher daily energy expenditures than those from private schools during weekends (P<0.01). The results suggest that girls may prefer less vigorous forms of activity. They also indicate that adolescents are investing time in physical activity when they have the freedom to participate or not (i.e. weekends), in particular those from public schools. We suggest that differences in gender, seasonality, and weekends versus weekdays, together with the choice of lifestyle activities, should be considered when designing activity promotion strategies among Spanish adolescents.

A delay discounting procedure for rhesus monkeys

Delay discounting is important in drug abuse research as drug abusers often discount delayed rewards more than non drug users; however, ethical limitations in human research necessitate complimentary studies with other species. An advantage of studying delay discounting in monkeys is that current technologies allow for imaging monkeys while they are performing behavioral tasks. Thus it would be possible to detect delay discounting related brain activation patterns and observe how behavior and activation patterns change as a result of drug exposure, provided suitable tasks are available. Two adult rhesus monkeys have been tested on a delay discounting task in which reinforcer contingencies (i.e. changes in delay to reinforcer delivery) are systematically altered. Subjects were first put on a 2‐choice task where responding on one lever produced a large juice reinforcer (1.25 ml) and responding on the other lever produced a small juice reinforcer (0.125 or 0.25 ml). Once subjects made at least 90% of responses on the lever associated with the larger reinforcer, lever contingencies were switched across days until subjects reliably made at least 90% of responses on the lever that produced that large reinforcer. Next, subjects were tested on a delay discounting task with repeated opportunities to respond for an immediate small juice reinforcer or a large juice reinforcer that was delivered after an increasing delay (0–60 s). Responding for the large reinforcer decreased with increasing delays to its delivery; both monkeys responded predominantly for the large reinforcer more when delays were removed for individual daily sessions. This procedure appears suitable for future studies to assess the effects of drugs of abuse on delay discounting and its underlying neural circuitry.

The Carpenter BeeXylocopa pubescensas an Agricultural Pollinator in Greenhouses

Many greenhouse crops depend on bees for pollination. Global declines of honeybee populations, and their limited efficiency in pollinating some greenhouse food-plants, motivate the search for additional pollinators. We evaluated the carpenter bee X. pubescens, a local species to Israel, as a pollinator of greenhouse-grown honey dew melons, in comparison to honeybees. We recorded the bees’ daily and seasonal activity patterns in relation to floral nectar levels, frequencies and durations of flower visits, and fruit quantity and quality. The bees’ daily foraging schedule on melon did not correlate with nectar yield and nectar production patterns by the flowers. Visit durations per flower were shorter for X. pubescens than for honeybees. Pollination by both bees resulted in similar fruit mass and seed numbers, but X. pubescens pollination increased fruit set threefold as compared to honeybee pollination. We conclude that X. pubescens can effectively pollinate melons in enclosures.

An fMRI study of brain activation in a visual adaptation task: activation limited to sensory guidance

Previous neuroimaging studies yielded different patterns of brain areas activated during sensorimotor adaptation, when sensory conflicts are introduced, e.g. by manipulating visual information. We propose that possible reasons might be the lack to control for adaptation or the change in motor performance. In consequence, it was not possible to distinguish between adaptation-related and error-related brain activations. We have developed a sensorimotor adaptation task which controls for these errors using two types of visual distortion and thus is suited to disambiguate sensorimotor adaptation from the related activation patterns. Twenty healthy subjects were scanned by fMRI during a tracking task, while adapting to a visual distortion, which depended either on hand position or on hand velocity. In either case, adaptation was interleaved with a control condition, designed such that the time-course of tracking errors approximated that under visual distortion. We found that adaptation-related neural activation was limited to the left supramarginal and angular gyrus under the position-dependent distortion, but extended bilaterally in the supramarginal gyrus, as well as in the left middle and right superior frontal gyrus under the velocity-dependent distortion. Our findings confirm that equating the errors under both conditions will yield an anatomically more restricted activation pattern compared with other studies. The additional recruitment in right parietal and bilateral frontal areas under the velocity-dependent distortion might reflect a higher computational demand, or the involvement of different adaptive mechanisms.

A validation of the post concussion symptom scale in the assessment of complex concussion using cognitive testing and functional MRI

Background:Clinical assessment of cerebral concussion relies on the presence and duration of post concussive symptoms (PCS). Given that these PCS are subjective reports and not always specific to concussion, their...

Diet, physical activity, and adiposity in children in poor and rich neighbourhoods: a cross-sectional comparison

BackgroundObesity in Canadian children increased three-fold in twenty years. Children living in low-income neighborhoods exercise less and are more overweight than those living in more affluent neighborhoods after accounting for family socio-economic status. Strategies to prevent obesity in children have focused on personal habits, ignoring neighborhood characteristics. It is essential to evaluate diet and physical activity patterns in relation to socio-economic conditions to understand the determinants of obesity. The objective of this pilot study was to compare diet, physical activity, and the built environment in two Hamilton area elementary schools serving socio-economically different communities.MethodsWe conducted a cross-sectional study (November 2005-March 2006) in two public elementary schools in Hamilton, Ontario, School A and School B, located in low and high socioeconomic areas respectively. We assessed dietary intake, physical activity, dietary restraint, and anthropometric measures in consenting children in grades 1 and higher. From their parents we assessed family characteristics and walkability of the built environment.Results160 children (n = 48, School A and n = 112, School B), and 156 parents (n = 43, School A and n = 113, School B) participated in this study. The parents with children at School A were less educated and had lower incomes than those at School B. The School A neighborhood was perceived to be less walkable than the School B neighborhood. Children at School A consumed more baked foods, chips, sodas, gelatin desserts, and candies and less low fat dairy, and dark bread than those at School B. Children at School A watched more television and spent more time in front of the computer than children studying at School B, but reported spending less time sitting on weekdays and weekends. Children at both schools were overweight but there was no difference in their mean BMI z-scores (School A = 0.65 versus School B = 0.81, p-value = 0.38).ConclusionThe determinants of overweight in children may be more complex than imagined. In future intervention programs researchers may consider addressing environmental factors, and customizing lifestyle interventions so that they are closer to community needs.

Physical Activity Participation by Presence and Type of Functional Deficits in Older Women: The Women's Health and Aging Studies

Physical activity is important for maintaining functional independence of older persons, especially for those with existing functional deficits. Since such deficits may pose barriers to activity, it would be instructive to examine activity patterns in relation to specific types of deficits to determine the amount and type of physical activity older women pursue. This study sought to identify categories of functional deficits associated with activity levels and evaluated the potential for older women to increase their physical activity levels. Community-dwelling women, aged 70-79 years, from the Women's Health and Aging Studies I and II (N = 710), were assessed for self-reported physical activity, functional deficits and chronic conditions, along with objective measures of muscle strength. Both type (household chores, exercise, and recreational activity) and amount of physical activity (min/wk) were examined. Meeting physical activity recommendations was defined as > or =150 minutes per week of moderate intensity physical activity, and inactivity was defined as no weekly moderate intensity physical activity. Hierarchical categories of functional deficits were based on self-reported difficulty in four functional domains (i.e., mobility/exercise tolerance, upper extremity, higher functioning, and self-care), and self-reports ranged from no difficulty to difficulty in all four domains. The prevalence of inactivity and meeting activity recommendations were 14.4% and 12.7%, respectively. Severity of functional deficits was associated with increased risk of inactivity (adjusted odds ratios [ORs(adj)] = 3.14-17.61) and reduced likelihood of meeting activity recommendations (ORs(adj) =.11-.40). Even among those with higher functioning or self-care difficulties, 30% reported walking for exercise. There was evidence that older women with functional deficits can remain physically active. However, for some of these women, meeting the recommended levels of activity may be unrealistic. Efforts to increase physical activity levels among older adults should include treatment or management of functional deficits, chronic conditions, and poor strength.

Activation mapping as a percentage of local excitation: fMRI stability within scans, between scans and across field strengths

Functional magnetic resonance imaging (fMRI) does not typically yield highly reproducible maps of brain activation. Maps can vary significantly even with constant scanning parameters and consistent task performance conditions (Liu et al., Magn. Reson. Med., 2004, 52:751-760). Reproducibility is even more of a problem when comparing fMRI signal magnitude and spatial extent of activation across scans involving different task performance levels, scan durations, pulse sequences or magnetic field strengths. In this report, the consistency of fMRI was reexamined by considering the relative spatial and temporal distribution of fMRI blood oxygen level dependent (BOLD) activation signals separately from the absolute magnitude of the activation signal in each brain area. Subjects repeatedly performed the same simple motor task but under a variety of imaging conditions, using both spiral and standard echo-planar pulse sequences and at 1.5- and 4.0-T magnetic field strengths. The results demonstrate that the absolute amplitude of BOLD statistical activation signals varied significantly across time and scanning conditions, but the relative spatial pattern of BOLD activation was highly reproducible across all conditions. Analysis of realistic simulated fMRI data sets indicates that stability of relative activation patterns could provide a useful tool for assessing the accuracy of fMRI maps.

Activity patterns of bushbuck (Tragelaphus scriptus) in Queen Elizabeth National Park

Activity patterns and time budgets of bushbuck (Tragelaphus scriptus) were studied in a free-ranging population in Queen Elizabeth National Park, Uganda from August 2000 to January 2002. We investigated differences in activity patterns in relation to daytime, season, sun radiation, moonlight, age and sex. Bushbuck were found to show peak activities around sunrise and at dawn. No difference in the mean activity rates was found between the dry and wet season. Daytime activity was not predicted by differences in sun radiation, nor was nighttime activity predicted by the presence or absence of moonlight. We found the activity of adult territorial males to be strongly positively correlated with that of females, whereas the activity of young-adult non-territorial males was not significantly correlated with the activity of females. This suggests that young-adult males shift their peak activity to phases when adult territorial males are less active.

The influence of age and dental status on elevator and depressor muscle activity

The objective of this study was to determine whether the muscle activity at various mandibular positions is affected by age and dental status. Thirty edentulous subjects (E), 20 young dentate individuals (G1) and 20 older dentate individuals (G2) participated in this study. Surface electromyographic (EMG) recordings were obtained from the anterior temporal (T), masseter (M) and depressor muscles (D). Muscle activity was recorded during maximal voluntary contraction (MVC), maximal opening (O(max)) and in six different mandibular positions. One way anova and the Bonferroni tests were used to determine the differences between groups. Significant differences between the three tested groups were found at MVC and O(max) for all examined muscles (P < 0.001). The differences in muscle activity in dentate subjects of different age were found in protrusion for depressor muscles (P < 0.05) and in lateral excursive positions for the working side temporal (P < 0.05) and non-working side masseter and depressor muscle (P < 0.05). There was a significant effect regarding the presence of natural teeth or complete dentures in protrusion and maximal protrusion for all muscles (P < 0.05) and in lateral excursive positions for non-working side temporal (P < 0.05) and working side masseter muscle (P < 0.05). Muscle activity at various mandibular positions depends greatly on the presence of the prosthetic appliance, as edentulous subjects had to use higher muscle activity levels (percentages of maximal EMG value) than age matched dentate subjects in order to perform same mandibular movement. Different elevator muscles were preferentially activated in the edentulous subjects when compared with dentate group in lateral excursive positions of the mandible. The pattern of relative muscle activity was not changed because of ageing.

アシハラガニおよびハマガニにおける巣穴外活動の季節変化と日周変化

Helice tridens and Chasmagnathus convexus are grapsid crabs living in tidal flats . Both species construct burrows in the upper intertidal and supratidal zones, although they use also waterside areas in lower tidal zones during low tide. In this study, temporal variations in above-ground density and food items of the two species in different habitats (i.e., burrow areas and waterside areas) were investigated in the Shigenobu and Awai River estuaries of Ehime Prefecture, southwestern Japan, to examine the crabs' seasonal and diel activity patterns in relation to their food habits . Monthly investigations showed that above-ground densities of both species increased from spring and peaked in summer, and the densities were positively correlated with underground temperature. Diel activity patterns differed between the two species. Chasmagnathus convexus tended to be nocturnally active in both burrow and waterside areas . On the other hand, H. tridens exhibited high diurnal activity in their burrow areas during cool seasons (March, October), while at other times they tended to be active nocturnally in both the burrow and waterside areas . Helice tridens consumed various food items such as surface sediment, macroalgae, reeds, and macrozoobenthos. These crabs mainly consumed surface sediment in burrow areas, whereas they frequently consumed macroalgae in waterside areas, where their foraging activity was greater. Food and habitat use of C. convexus differed from those of H . tridens; they primarily consumed reeds in burrow areas and rarely foraged in waterside areas. Overall results suggest that the differences in diel activity pattern between the two species are related to their different food habits and spatial variation in food availability.

Multisensory plasticity in congenitally deaf mice: How are cortical areas functionally specified?

The neocortex of congenitally deaf mice was examined using electrophysiological recording techniques combined with cortical myeloarchitecture. Our results indicate that relative activity patterns across sensory systems during development contribute to modality assignment of cortical fields as well as the size of cortical fields. In congenitally deaf mice, “auditory cortex” contained neurons that responded to somatosensory, visual, or both somatosensory and visual stimulation; the primary visual area contained a larger proportion of neurons that responded to somatosensory stimulation than in normal animals, and the primary visual area had significantly increased in size. Thus, cortical architecture and functional specification were de-correlated. When results are considered in the light of molecular studies and studies in which peripheral activity is altered in development, it becomes clear that similar types of changes to the neocortex, such as alterations in cortical field size, can be achieved in more than one way in the developing and evolving neocortex.

Surface related muscle activation patterns in men and women

Surface related muscle activation patterns in men and women

Estimating the relative abundance and temporal activity patterns of wood mice (Apodemus sylvaticus) by remote photography in mediterranean post-fire habitats

We investigated whether remote photography can be considered a valid method to assess the abundance and the temporal activity patterns of the wood mouse (Apodemus sylvaticus) in two Mediterranean post-fire habitats. We compared the results with those obtained by Sherman live-trapping, a conventional procedure to obtain information on the composition of small mammal communities. We observed a highly significant increase of abundance of wood mice in shrublands (early post-fire stage) in front of pinewoods (unburned during the last 50 years) with both capture methods (G = 104.83; p &lt; 0.0001; d.f. = 1). 81 out of 95 photographic contacts of wood mouse were recorded in shrublands (85.3%) and the remainder 14 contacts in pinewoods (14.7%), and 78 out of 90 captures with Sherman traps were obtained in shrublands (86.7%), and the remainder 12 in pinewoods (13.3%). Remote photography showed the same proportions of captures than live-trapping in the two habitats studied (G = 0.07; p = 0.79; d.f. = 1). Temporal activity patterns of wood mice were biphasic during winter in shrublands, with lower values of activity near sunset and sunrise, and maximum four hours after sunset anf five hours before sunrise. We conclude that remote photography, despite pseudoreplication (impossibility to diferentiate individuals in the photographs), can be considered a valid method to estimate wood mice abundance and activity patterns in the post-fire habitats studied.

BILATERAL MOTOR OUTPUTS FROM THE RETICULOSPINAL SYSTEM TO THE UPPER LIMBS DURING REACHING IN THE MONKEY.

Purpose/Hypothesis: This study describes the motor outputs and neural activity of the reticulospinal system in the monkey during reaching. The hypotheses are 1) that single sites in the reticular formation will produce bilateral motor outputs to the upper limbs and 2) that neural activity in the reticulospinal system will code for the preparation as well as the execution of upper limb movement during voluntary reaching. Number of Subjects: 2 young adult male Macaca fascicularis monkeys were the subjects. Materials/Methods: Subjects were trained to reach with the R or L arm to a target on the R or L side, depending on instructions given during a waiting period before each trial. An electrode positioning system was then surgically implanted, allowing daily access to the brainstem with tungsten microelectrodes in the awake, behaving animal. Single-pulse microstimula-tion at 10 Hz was applied to areas throughout the reticulospinal system in the brainstem as EMG was recorded throughout the shoulder girdle and upper limbs (24 muscles). Extracellular action potentials were also recorded from cells in this region. Neural activity patterns in relation to preparatory and movement-related periods of the task were analyzed as were averaged muscle responses to microstimulation. Results: Microstimulation of the reticulospinal system tended to inhibit extensors and facilitate flexors ipsilateral to the stimulus and produce the opposite effects contralaterally. Effects were strongest and most frequently elicited in the extensors and in the proximal muscles, especially the upper trapezius. Bilateral effects were the norm, though some sites did produce strictly ipsi or contralateral effects in the muscles studied. About 25% of the 196 neurons analyzed had activity related to preparation, 25% had activity related to preparation and to movement, and 50% had only movement-related activity. About 30% of the neurons had activity that was related to the arm used for reaching, and 30% (non-exclusive) had activity related to the target contacted. Only about 10% had activity that was unique to a certain hand-target combination. Conclusions: Reticulospinal neurons have motor output effects and neural activity patterns during movement that demonstrate a role in the control of voluntary reaching. Effects were observed in the shoulder girdle, shoulder, elbow, and even at the wrist. Characterization of the reticulospinal system as strictly for postural control or for control of locomotion may be oversimplified. This major descending system also contributes to the execution of discrete, skilled reaching movements. Clinical Relevance: The motor patterns emanating from the reticulospinal system are reminiscent of the limb movements associated with the ATNR and with synergies associated with recovery from stroke. The present findings lend strength to the long-held concept that the reticulospinal system may be an alternative pathway for voluntary motor control after stroke.

PHOSPHATASE ACTIVITY OF NON-HAIR FORMING CYANOBACTERIUM RIVULARIA AND ITS ROLE IN PHOSPHORUS DYNAMICS IN DEEPWATER RICE-FIELDS

Phosphatase activity of Rivularia strains II and I isolated from a deepwater rice field was studied. When grown under conditions of P-limitation the strains did not form hair and showed great variations in induction time and pattern of enzyme activity in relation to growth. Phosphomonoesterase activity (PMEase) was induced earlier in the Rivularia strain I which was maintained in high phosphate concentration in the medium before the study. Rivularia strain II on the other hand showed induction of PMEase activity after 3-4 days and this strain was maintained in low phosphorus concentrations in the medium before the study. The comparison of Km and Vmax values early in the growth phase showed that affinity of both PMEase (phosphomonester) and PDEase (phosphodiester) for the substrate was higher in early growth phase rather than in later stages suggesting that there is presence of more than one phosphatase enzymes in these organisms. The observations from the above study have important implications in rice fields where constant fluctuations in nutrients can be observed - especially by phosphorus in its most available form phosphate. Equal enzyme activity in both light and dark for the two strains (non hair-forming) implies that phosphatase activity may not be affected by changes in light regimes in rice fields which do occur due to the plant growth. This can in turn contribute significantly to maintain the growth of cyanobacteria for prolonged periods even under unfavorable conditions of phosphorus depletions. These strains of Rivularia can therefore biotechnologically exploited as bio- fertilizers (phosphatic fertilizer) when there is phosphorus deficiency. During the unfavorable conditions of phosphorus deficiency, phosphatase activity may play a significant role in providing phosphate for its own growth and for the rice plants.

Assessing child time – activity patterns in relation to indoor cooking fires in developing countries: A methodological comparison

Indoor air pollution, caused by the indoor burning of biomass fuels, has been associated with an increased risk of child acute respiratory infections in developing countries. The amount of time that children spend in proximity to fires is a crucial determinant of the health impact of indoor air pollution. Researchers are reliant on social scientific methods to assess exposure based on child location patterns in relation to indoor fires. The inappropriate use of methods could lead to misclassification of exposure. The aim of this paper is to compare two methods (observations and questionnaire interview) with video analysis (which is thought to offer a more accurate assessment of exposure) in rural South African villages. Compared to video analysis, results show that observations may underestimate the amount of time that children spend very close (within 1.5 m) to fires. This is possibly due to reactivity caused by the presence of an observer. The questionnaire interview offers a more accurate assessment of the amounts of time that children spend within 1.5 m of fires at the expense of a detailed behavioural analysis. By drawing on the strengths and weaknesses of each, this paper discusses the appropriateness of methods to different research contexts.

Demystifying Tissue Factor.

Tissue factor (TF) is an integral membrane protein, which is the key initiator of blood coagulation in vivo. Due to the limited availability of natural TF, recombinant proteins of various lengths and origins have been extensively used in research and clinical laboratories worldwide. Experimental results acquired with recombinant TF proteins are frequently used for the understanding of the coagulation processes occurring in vivo, although there is a lack of data confirming the structural and functional identity of natural TF proteins from various sources and recombinant ones. In the current study, human TF from cultured monocytes and purified from placenta were compared with three different species of recombinant TF: 1–218 (extracellular domain only), 1–242 (lacking cytoplasmic domain) and 1–263 (full-length). Anti-TF mAbs gave 93–98% inhibition of TF activity for all TF species tested, in both natural and relipidated preparations. It was established that purified placental TF has a higher affinity for factor VIIa (Kd 0.13 nM) than recombinant counterparts 1–242 and 1–263 (Kd 0.50–0.80 nM). Similarly, placental TF is more efficient in factor X activation by the extrinsic Xase than recombinant TF 1–242 (the second order rate constants are 3.0x107 and 0.7x107 M−1s−1, respectively). We explored the use of these TF species as well as monocyte TF (purified/relipidated and present on LPS-stimulated monocytes) for the initiation of thrombin generation in two in vitro models of blood coagulation. At equimolar concentrations (5 pM; determined by immunoassay), when evaluated in synthetic plasma reconstituted with 2x108/ml platelets, recombinant TF 1-263 provided an initiation phase of ~4 min. Placental TF and relipidated monocyte TF had similar profiles of thrombin generation with an initiation phase of ~3 min. In contrast, 0.5 pM TF on LPS-stimulated monocytes gave an initiation phase of ~1 min. Even at 0.05 pM concentration, monocyte TF was as active as any relipidated protein at 5.0 pM. A similar pattern of relative TF activity was observed in whole blood and plasma PT clotting assays. TF on stimulated monocytes gave the highest activity, exceeding that of any relipidated protein by 100–200-fold. Recombinant TF 1–242 was more active than recombinant TF 1–263 and placental TF in the PT assay but less active in synthetic plasma and whole blood. The lowest overall activity was observed for relipidated monocyte TF. Our data suggest that TF proteins from different sources are different with respect to their functional properties.