Chemical defense, mycorrhizal colonization and growth responses in Plantago lanceolata L.

Allelochemicals defend plants against herbivore and pathogen attack aboveground and belowground. Whether such plant defenses incur ecological costs by reducing benefits from plant mutualistic symbionts is largely unknown. We explored a potential trade-off between inherent plant chemical defense and belowground mutualism with arbuscular mycorrhizal fungi (AMF) in Plantago lanceolata L., using plant genotypes from lines selected for low and high constitutive levels of the iridoid glycosides (IG) aucubin and catalpol. As selection was based on IG concentrations in leaves, we first examined whether IG concentrations covaried in roots. Root and leaf IG concentrations were strongly positively correlated among genotypes, indicating genetic interdependence of leaf and root defense. We then found that root AMF arbuscule colonization was negatively correlated with root aucubin concentration. This negative correlation was observed both in plants grown with monocultures of Glomus intraradices and in plants colonized from whole-field soil inoculum. Overall, AMF did not affect total biomass of plants; an enhancement of initial shoot biomass was offset by a lower root biomass and reduced regrowth after defoliation. Although the precise effects of AMF on plant biomass varied among genotypes, plants with high IG levels and low AMF arbuscule colonization in roots did not produce less biomass than plants with low IG and high AMF arbuscule colonization. Therefore, although an apparent trade-off was observed between high root chemical defense and AMF arbuscule colonization, this did not negatively affect the growth responses of the plants to AMF. Interestingly, AMF induced an increase in root aucubin concentration in the high root IG genotype of P. lanceolata. We conclude that AMF does not necessarily stimulate plant growth, that direct plant defense by secondary metabolites does not necessarily reduce potential benefits from AMF, and that AMF can enhance concentrations of root chemical defenses, but that these responses are plant genotype-dependent.

Genetic variation in defense chemistry in wild cabbages affects herbivores and their endoparasitoids.

Populations of wild Brassica oleracea L. grow naturally along the Atlantic coastlines of the United Kingdom and France. Over a very small spatial scale (i.e., <15 km) these populations differ in the expression of the defensive compounds, glucosinolates (GS). Thus far, very few studies have examined interactions between genetically distinct populations of a wild plant species and associated consumers in a multitrophic framework. Here, we compared the development of a specialist (Pieris rapae) and a generalist (Mamestra brassicae) insect herbivore and their endoparasitoids (Cotesia rubecula and Microplitis mediator, respectively) on three wild populations and one cultivar of B. oleracea under controlled greenhouse conditions. Herbivore performance was differentially affected by the plant population on which they were reared. Plant population influenced only development time and pupal mass in P. rapae, whereas plant population also had a dramatic effect on survival of M. brassicae. Prolonged development time in P. rapae corresponded with high levels of the indole GS, neoglucobrassicin, whereas reduced survival in M. brassicae coincided with high levels of the aliphatic GS, gluconapin and sinigrin. The difference between the two species can be explained by the fact that the specialist P. rapae is adapted to feed on plants containing GS and has evolved an effective detoxification system against aliphatic GS. The different B. oleracea populations also affected development of the endoparasitoids. Differences in food-plant quality for the hosts were reflected in adult size in C. rubecula and survival in M. mediator, and further showed that parasitoid performance is also affected by herbivore diet.

Effects of a hip belt on transverse plane trunk coordination and stability during load carriage.

This study examined the transverse plane kinematics of the pelvis, thorax and head while participants walked at a range of speeds on a treadmill under three load conditions: no load, with a loaded backpack with no hip belt and with a loaded backpack with a hip belt. Research has suggested that one mechanism for adapting to heavy loads carried with no hip belt is to reduce the amplitudes and relative phase of transverse plane pelvic and thoracic rotations, in order to minimize rotational torque on the loaded upper body. Transverse plane rotation amplitudes of the pelvis, thorax, backpack and head were calculated from 3D kinematic data for 12 healthy subjects, walking at speeds of 0.5, 0.9, 1.3 and 1.7 ms(-1). Relative phase relation and its variability were also computed for pelvis-thorax rotations and backpack-thorax rotations. Stability of the coordination pattern was estimated as an inverse function of the variability in relative phase. The backpack with the hip belt allowed significantly larger transverse plane rotation amplitudes, along with increased stability of the coordination pattern, than the backpack with no hip belt. Motion patterns of the backpack and thorax suggested that the backpack frame was used to assist with the deceleration and reversal of the loaded thorax, driven by the pelvis through the hip belt connection. Use of the frame in this way may have required less trunk muscle activation and allowed for improved pattern stability.

The PEA3 subfamily of Ets transcription factors synergizes with beta-catenin-LEF-1 to activate matrilysin transcription in intestinal tumors.

The matrix metalloproteinase matrilysin (MMP-7) is expressed in the tumor cells of a majority of mouse intestinal and human colonic adenomas. We showed previously that matrilysin is a target gene of beta-catenin-Tcf, the transcription factor complex whose activity is thought to play a crucial role in the initiation of intestinal tumorigenesis. Here we report that overexpression of a stable mutant form of beta-catenin alone was not sufficient to effect expression of luciferase from a matrilysin promoter-luciferase reporter plasmid. However, cotransfection of the reporter with an expression vector encoding the PEA3 Ets transcription factor, or its close relatives ER81 and ERM, increased luciferase expression and rendered the promoter responsive to beta-catenin-LEF-1 as well as to the AP-1 protein c-Jun. Other Ets proteins could not substitute for the PEA3 subfamily. Luciferase activity was induced up to 250-fold when PEA3, c-Jun, beta-catenin, and LEF-1 were coexpressed. This combination of transcription factors was also sufficient to induce expression of the endogenous matrilysin gene. Furthermore, all matrilysin-expressing benign intestinal tumors of the Min mouse expressed a member of the PEA3 subfamily, as did all human colon tumor cell lines examined. These data suggest that the expression of members of the PEA3 subfamily, in conjunction with the accumulation of beta-catenin in these tumors, leads to coordinate upregulation of matrilysin gene transcription, contributing to gastrointestinal tumorigenesis.

Stabilized beta-catenin immortalizes colonic epithelial cells.

The majority of colonic neoplasias contain mutations in either the adenomatous polyposis coli or the beta-catenin (beta-cat) gene, both of which result in elevated levels of cytoplasmic beta-cat. The oncogenic activity of beta-cat has been explored in vivo and in vitro with conflicting results. We tested the hypothesis that beta-cat is capable of immortalizing and transforming cultured epithelial cells that represent the precursors to colon cancer. A truncated form of beta-cat (deltaN89) was stably expressed in murine colonic epithelial cells that were conditionally immortalized by temperature-sensitive T antigen expression and contained a mutant ApcMin allele [Immorto-Min colonic epithelium (IMCE)]. IMCE cells, grown under nonpermissive conditions, were immortalized by expression of the truncated beta-cat protein as determined by sustained growth in culture and escape from senescence as measured by endogenous beta-galactosidase activity. IMCE neo cells at nonpermissive conditions underwent extensive apoptosis, an effect that was blocked by the expression of deltaN89 beta-catenin. IMCE beta-cat cells had significantly lower p19 and p53 protein levels compared to IMCE neo cells, suggesting that alterations in these two key genes may mediate the effects of beta-cat on both cellular senescence and apoptosis. IMCE beta-cat cells were also transformed as determined by growth in the absence of serum, anchorage-independent growth, and sustained tumor growth in nude mice. Stable beta-cat-expressing populations could not be generated in conditionally immortalized colonic epithelia cells with a wild-type Apc background. These studies demonstrated the immortalizing activity of stabilized beta-cat for the first time and extend the transforming ability of mutated beta-cat to a cell line representing a precursor to colorectal cancer.

Hemiplegic gait: a kinematic analysis using walking speed as a basis.

The kinematics of treadmill ambulation of stroke patients (N = 9) and healthy subjects (N = 4) was studied at a wide range of different velocities (i.e. 0.25-1.5 m s-1), with a focus on the transverse rotations of the trunk. Video recordings revealed, for both stroke patients and healthy subjects, similar relations between walking speed and stride length as well as stride frequency. The phase difference between pelvic and thoracic rotations (i.e. trunk rotation) and the total range of trunk rotation were almost linearly related to the walking speed. Healthy subjects showed a marked increase in pelvic rotation from 1 to 1.5 m s-1. Using dimensional analysis in a comparison between stroke patients and healthy subjects, invariances in the coordination of gait were found for stride length, stride frequency, pelvic rotation, and trunk rotation. Constant relations were obtained between, on the one hand, dimensionless velocity and, on the other, dimensionless stride length as well as stride frequency. Transitions were found between the velocities 0.75 and 1 m s-1 for dimensionless pelvic rotation and trunk rotation, indicating that, from this velocity range onwards, pelvic swing lengthens the stride: rotations of pelvis, thorax and trunk become tightly coordinated. On the basis of the dimensionless stride length, stride frequency, pelvic rotation and trunk rotation, deficits in the gait of stroke patients could be quantified. It is concluded that walking speed is an important control parameter, which should be used as a basic variable in the evaluation of the gait of stroke patients.

Resonant frequencies of arms and legs identify different walking patterns.

The present study is aimed at investigating changes in the coordination of arm and leg movements in young healthy subjects. It was hypothesized that with changes in walking velocity there is a change in frequency and phase coupling between the arms and the legs. In addition, it was hypothesized that the preferred frequencies of the different coordination patterns can be predicted on the basis of the resonant frequencies of arms and legs with a simple pendulum model. The kinematics of arms and legs during treadmill walking in seven healthy subjects were recorded with accelerometers in the sagittal plane at a wide range of different velocities (i.e., 0.3-1. 3m/s). Power spectral analyses revealed a statistically significant change in the frequency relation between arms and legs, i.e., within the velocity range 0.3-0.7m/s arm movement frequencies were dominantly synchronized with the step frequency, whereas from 0.8m/s onwards arm frequencies were locked onto stride frequency. Significant effects of walking speed on mean relative phase between leg and arm movements were found. All limb pairs showed a significantly more stable coordination pattern from 0.8 to 1.0m/s onwards. Results from the pendulum modelling demonstrated that for most subjects at low-velocity preferred movement frequencies of the arms are predicted by the resonant frequencies of individual arms (about 0.98Hz), whereas at higher velocities these are predicted on the basis of the resonant frequencies of the individual legs (about 0.85Hz). The results support the above-mentioned hypotheses, and suggest that different patterns of coordination, as shown by changes in frequency coupling and phase relations, can exist within the human walking mode.

Effects of walking velocity on relative phase dynamics in the trunk in human walking.

The nature of coordination changes and stability features in the relative phase dynamics of the trunk were examined in seven healthy subjects, while walking velocity on a treadmill was gradually increased and decreased. Predictions from Schöner et al (J. Theor. Biol. 142, 359-391, 1990) regarding transition mechanisms in quadrupedal walking generalized to pelvis-thorax phase relations in bipedal walking, in that more continuous transitions with and without loss of stability were observed when walking velocity was manipulated as a control parameter. Relative phase changed from more in-phase (about 25 degrees) at lower velocities to more out-of-phase (about 110 degrees) at higher velocities. Stability analysis of relative phase demonstrated the existence of more than one stable coordination pattern ('multistability'). Total ranges of motion in pelvis, thorax, and trunk, as well as stride length were larger at the decreasing velocity range was compared to the increasing velocity range, showing dependence on direction of control parameter manipulation ('hysteresis effect'). The nature of these transitions identifies phase relations in the trunk in human walking as lower symmetry dynamics, a finding consistent with the proposed dynamics of the quadrupedal walking mode. These results suggest the existence of different coordination patterns (multistability) in the human bipedal walking mode and question traditional distinctions in only two modes (walking and running) in human gait.

How do load carriage and walking speed influence trunk coordination and stride parameters?

To determine the effects of load carriage and walking speed on stride parameters and the coordination of trunk movements, 12 subjects walked on a treadmill at a range of walking speeds (0.6-1.6 m s(-1)) with and without a backpack containing 40% of their body mass. It was hypothesized that compared to unloaded walking, load carriage decreases transverse pelvic and thoracic rotation, the mean relative phase between pelvic and thoracic rotations, and increases hip excursion. In addition, it was hypothesized that these changes would coincide with a decreased stride length and increased stride frequency. The findings supported the hypotheses. Dimensionless analyses indicated that there was a significantly larger contribution of hip excursion and smaller contribution of transverse plane pelvic rotation to increases in stride length during load carriage. In addition, there was a significant effect of load carriage on the amplitudes of transverse pelvic and thoracic rotation and the relative phase of pelvic and thoracic rotation. It was concluded that the shorter stride length and higher stride frequency observed when carrying a backpack is the result of decreased pelvic rotation. During unloaded walking, increases in pelvic rotation contribute to increases in stride length with increasing walking speed. The decreased pelvic rotation during load carriage requires an increased hip excursion to compensate. However, the increase in hip excursion is insufficient to fully compensate for the observed decrease in pelvis rotation, requiring an increase in stride frequency during load carriage to maintain a constant walking speed.

Comparing predictive validity of four ballistic swing phase models of human walking.

It is unclear to what extent ballistic walking models can be used to qualitatively predict the swing phase at comfortable walking speed. Different study findings regarding the accuracy of the predictions of the swing phase kinematics may have been caused by differences in (1) kinematic input, (2) model characteristics (e.g. the number of segments), and (3) evaluation criteria. In the present study, the predictive validity of four ballistic swing phase models was evaluated and compared, that is, (1) the ballistic walking model as originally introduced by Mochon and McMahon, (2) an extended version of this model in which heel-off of the stance leg is added, (3) a double pendulum model, consisting of a two-segment swing leg with a prescribed hip trajectory, and (4) a shank pendulum model consisting of a shank and rigidly attached foot with a prescribed knee trajectory. The predictive validity was evaluated by comparing the outcome of the model simulations with experimentally derived swing phase kinematics of six healthy subjects. In all models, statistically significant differences were found between model output and experimental data. All models underestimated swing time and step length. In addition, statistically significant differences were found between the output of the different models. The present study shows that although qualitative similarities exist between the ballistic models and normal gait at comfortable walking speed, these models cannot adequately predict swing phase kinematics.

Coordination between arm and leg movements during locomotion.

To evaluate the contrasting dynamical and biomechanical interpretations of the 2:1 frequency coordination between arm and leg movements that occurs at low walking velocities and the 1:1 frequency coordination that occurs at higher walking velocities, the authors conducted an experiment in which they quantified the effect of walking velocity on the stability of the frequency and phase coordination between the individual limb movements. Spectral analyses revealed the presence of 2:1 frequency coordination as a constant feature of the data in only 3 out of 8 participants at walking velocities ranging from 1.0 to 2.0 km/h, in spite of the fact that the eigenfrequencies of the arms were rather similar across participants. The degree of interlimb coupling, as indexed by weighted coherence and variability of relative phase, was lower for the arm movements and for ipsilateral and diagonal combinations of arm and leg movements than for the leg movements. Furthermore, the coupling between all pairs of limb movements was found to increase with walking velocity, whereas no clear signs were observed that the switches from 2:1 to 1:1 frequency coordination and vice versa were preceded by loss of stability. Therefore, neither a purely biomechanical nor a purely dynamical model is optimally suited to explain these results. Instead, an integrative model involving elements of both approaches seems to be required.

Transverse plane kinetics during treadmill walking with and without a load.

OBJECTIVE: The purpose of this experiment was to determine the effects of wearing a backpack on transverse plane upper and lower body torque. BACKGROUND: During unloaded walking the upper and lower body counter-rotate to reduce the net angular momentum of the body. There is less counter-rotation while carrying a load, suggesting a more rigid link between the upper and lower body. We predicted that load carriage would result in an increase in upper body torque. Because the upper and lower body may be more rigidly linked during load carriage, we also predicted an increase in lower body torque. METHODS: Twelve subjects (5 male, 7 female, mean age=26) walked with and without a backpack containing 40% of their body mass on a treadmill at speeds from 0.6 to 1.6 ms(-1). Kinematic data were sampled for 30 s at each speed, upper and lower body torque were calculated from angular acceleration and moment of inertia. RESULTS: Higher levels of upper and lower body torque were observed during load carriage than during unloaded walking. However, the increase in upper body torque was 225%, while upper body moment of inertia increased by 400%. CONCLUSIONS: The differences in torque between loaded and unloaded walking suggest that a goal of loaded walking is to minimize upper body torque, which may reduce the likelihood of injury. RELEVANCE: Knowledge of the effects of load carriage on upper and lower body torque, and related changes in coordination may provide insight into injury reduction mechanisms during load carriage.

Disorders in trunk rotation during walking in patients with low back pain: a dynamical systems approach.

OBJECTIVE: (1) To introduce an evaluation tool for the assessment of walking disorders in low back pain patients. (2) To investigate whether walking patterns in low back pain patients are different from those of control subjects. DESIGN: Relative phase measures of movement coordination are applied in the assessment of trunk function in a small group of patients with non-specific low back pain and in control subjects. BACKGROUND: Normal subjects change the coordination of pelvic and thoracic rotations from an in-phase to an out-of-phase pattern with increasing walking speed. Low back pain patients may have a reduced ability to counter rotate pelvis and thorax at higher walking speeds (from 1.0 m/s onwards) as a result of hyperstable coordination patterns. METHODS: Six patients with non-specific low back pain and six healthy control subjects walked on a treadmill at comfortable walking speeds and during a systematic variation of the treadmill velocity. Coordination of arm and leg movements as well as of pelvic and thoracic rotations was analyzed using a relative phase algorithm. RESULTS AND CONCLUSIONS: The comfortable walking speed was reduced in the patient group. In contrast to the control subjects, four of the six patients were not able to establish an out-of-phase coordination pattern between thorax and pelvis at higher walking speeds. This coincided with an increased stability of movement coordination, indicating guarded behavior. In addition, an increased asymmetry between the phase-relations of left and right side of the body was found in some of the patients.

Coordination and stability of one-legged hopping patterns in patients with anterior cruciate ligament reconstruction: preliminary results.

OBJECTIVES: To investigate whether the intralimb coordination of the lower extremity during one-legged hopping in patients with anterior cruciate ligament reconstruction is different and less stable compared to control subjects. DESIGN: Measures of coordination dynamics are applied to study the coordination and stability of movement patterns of the knee and ankle in patients and control subjects. BACKGROUND: Due to several factors, such as loss of proprioceptive function and muscle weakness, the intralimb coordination of the lower extremity might be altered. METHODS: Seven patients and 13 healthy control subjects were instructed to hop in place on one leg for 10 seconds at a comfortable frequency for each leg separately. RESULTS AND CONCLUSIONS: The one-legged hopping movement pattern of patients with anterior cruciate ligament reconstruction one-year post-operative is different and less stable compared to healthy subjects, and thus is still impaired. RELEVANCE: This paper shows that patients, one year after reconstruction of the anterior cruciate ligament, have a different coordination pattern of the lower limb compared to a matched control group. Intersegmental coordination and stability, features that are often observed by eye during a rehabilitation process, are objectified in this study.

The transfer of scanning training effects in visual inattention after stroke: five single-case studies.

The transfer effects of scanning training of right-brain-damaged stroke patients with visual inattention have been studied. Five patients were treated according to a B-C-B-D design. The first B phase lasted for 2, 4, or 6 weeks, whereas the other intervention phases had a fixed duration of 2 weeks. During all phases physical therapy was given. Additionally, occupational therapy was applied during the B phases, training on a scanning apparatus during the C phase, and training on reading tasks during the D phase. At least three times in each intervention phase, performance was measured using a computerized visual scanning test, a line bisection test, and a letter cancellation test. In addition, wheelchair navigation was assessed. For four out of the five patients a significant positive effect of visual scanning training on visual scanning behaviour was found. This effect, however, appeared to be restricted to the task which was specifically trained. Over the group as a whole no evidence could be found for any transfer of visual scanning training effects to the domain of gross motor skills.

Physiotherapy after stroke: more is better?

Physiotherapy is an established component of stroke rehabilitation but uncertainties remain about the most appropriate intensity of therapy input. We conducted a systematic review of the randomised trials of physiotherapy after stroke where qualitatively similar therapy regimens were provided at different levels of intensity. A heterogeneous group of seven randomised trials (597 patients) was identified. Dichotomous outcomes (death or the combined poor outcome of death or deterioration) were analysed by use of the odds ratio and 95% confidence interval. Patients subjected to more intensive physiotherapy input showed a non-significant reduction in case fatality (odds ratio 0.60; 95% CI 0.33-1.09) and a significant reduction (OR 0.54; 95% CI 0.34-0.85; p < 0.01) in the combined poor outcome of death or deterioration by the end of follow-up. Two statistical techniques were used to identify patterns within the continuous data. Firstly, impairment and disability scores were converted to a standardised measure of 0-100 and the weighted mean difference (WMD) between the scores in the intensive and conventional physiotherapy groups were then calculated. Modest improvements were observed in both the impairment (WMD+5; 95% CI-1-11) and disability scores (WMD+5; 95% CI 0-10) recorded at the initial review (median 3 months post-stroke), but not at the final review (median 1 year post-stroke). Secondly, Fisher's inverse chi-squared test was used to combine the p values from individual trials; this confirmed the above findings (p < 0.05 at initial review; p > 0.05 at final review). More intensive physiotherapy input was associated with a reduction in the combined poor outcome of death or deterioration and may enhance the rate of recovery. These observations warrant further investigation.

Accuracy of physical and occupational therapists' early predictions of recovery after severe middle cerebral artery stroke.

INTRODUCTION: The ability of physical therapists (PTs) and occupational therapists (OTs) to predict level of outcome accurately was investigated prospectively in 91 severely disabled stroke patients with a first-ever middle cerebral artery (MCA) stroke. METHODS: Within the second and fifth week after stroke onset, 364 predictions were made by 59 PTs and 47 OTs about walking ability, dexterity, activities of daily living (ADL), need for additional care in ADL, time required to achieve independent walking ability and maximal level of ADL, and destination of discharge at six months after stroke. The functional recovery patterns of stroke patients were assessed by an independent observer. The accuracy of the therapists' predictions was compared with that of derived prediction models. In addition, the influence of characteristics of patients and therapists on the accuracy of the predictions was investigated. RESULTS: Compared to observed outcomes at six months after stroke, therapists' lowest accuracies of prediction were found for the moment at which maximal ADL score was achieved (rs = 0.07; p = NS), and highest accuracy was for level of dexterity of the hemiplegic arm (rs = 0.78; p <0.01). Therapists' predictions of functional outcome at six months tended to be too pessimistic. No significant differences were observed for dexterity and walking ability when the predictions by PTs and OTs were compared with those of regression models, whereas significant differences were found for the accuracies of OTs' and PTs' first prediction of destination of discharge and second predictions of outcome in ADL and need for additional care in ADL. No significant differences were found between the accuracy of PTs' and OTs' predictions, and their ability to predict functional outcome was not significantly influenced by the characteristics of patient and therapists. CONCLUSIONS: At two and five weeks after stroke, OTs and PTs can accurately predict level of walking ability and dexterity at six months. The prediction of time required for achieving maximal level of recovery, destination of discharge, outcome of ADL as well as need for additional care in ADL leaves room for improvement.

Long term effects of intensity of upper and lower limb training after stroke: a randomised trial.

OBJECTIVE: To assess long term effects at 1 year after stroke in patients who participated in an upper and lower limb intensity training programme in the acute and subacute rehabilitation phases. DESIGN: A three group randomised controlled trial with repeated measures was used. METHOD: One hundred and one patients with a primary middle cerebral artery stroke were randomly allocated to one of three groups for a 20 week rehabilitation programme with an emphasis on (1) upper limb function, (2) lower limb function or (3) immobilisation with an inflatable pressure splint (control group). Follow up assessments within and between groups were compared at 6, 9, and 12 months after stroke. RESULTS: No statistically significant effects were found for treatment assignment from 6 months onwards. At a group level, the significant differences in efficacy demonstrated at 20 weeks after stroke in favour of the lower limb remained. However, no significant differences in functional recovery between groups were found for Barthel index (BI), functional ambulation categories (FAC),action research arm test (ARAT), comfortable and maximal walking speed, Nottingham health profile part 1(NHP-part 1), sickness impact profile-68 (SIP-68), and Frenchay activities index (FAI) from 6 months onwards. At an individual subject level a substantial number of patients showed improvement or deterioration in upper limb function (n=8 and 5, respectively) and lower limb function (n=19 and 9, respectively). Activities of daily living (ADL) scores showed that five patients deteriorated and four improved beyond the error threshold from 6 months onwards. In particular, patients with some but incomplete functional recovery at 6 months are likely to continue to improve or regress from 6 months onwards. CONCLUSIONS: On average patients maintained their functional gains for up to 1 year after stroke after receiving a 20 week upper or lower limb function training programme. However, a significant number of patients with incomplete recovery showed improvements or deterioration in dexterity, walking ability, and ADL beyond the error threshold.