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PubMed2003

Effects of leg movements on the synaptic activity of descending statocyst interneurons in crayfish, Procambarus clarkii.

Crustacean postural control is modulated by behavioral condition. In this study, we investigated how the responses of descending statocyst interneurons were affected during leg movements. Intracellular recording was made from an animal whose statoliths had been replaced with ferrite grains so that statocyst receptors could be activated by magnetic field stimulation. We identified 14 morphological types of statocyst-driven descending interneurons. Statocyst-driven descending interneurons always showed an excitatory response to statocyst stimulation on either ipsilateral or contralateral side to the axon. The response of each statocyst-driven descending interneuron to statocyst stimulation was differently modulated by leg movements in different conditions. During active leg movements, six statocyst-driven descending interneurons were activated regardless of whether a substrate was provided or not. In other two statocyst-driven descending interneurons, the excitatory input during leg movements was stronger when a substrate was provided than when it was not. One statocyst-driven descending interneuron received an excitatory input only during leg movements on a substrate, whereas another statocyst-driven descending interneuron did not receive any input during leg movements both on a substrate and in the air. These results suggest that the descending statocyst pathways are organized in parallel, each cell affected differently by behavioral conditions.

Action Potentials↗
PubMed2004

Sensing the effect of body load in legs: responses of tibial campaniform sensilla to forces applied to the thorax in freely standing cockroaches.

Sense organs in the legs that detect body weight are an important component in the regulation of posture and locomotion. We tested the abilities of tibial campaniform sensilla, receptors that can monitor forces in the cockroach leg, to encode variations in body load in freely standing animals. Small magnets were attached to the thorax and currents were applied to a coil below the substrate. Sensory and motor activities were monitored neurographically. The tibial sensilla could show vigorous discharges to changing forces when animals stood upon their legs and actively supported the body weight. Firing of individual afferents depended upon the orientation of the receptor's cuticular cap: proximal sensilla (oriented perpendicular to the leg axis) discharged to force increases while distal receptors (parallel to the leg) fired to decreasing forces. Proximal sensillum discharges were prolonged and could encode the level of load when increases were sustained. Firing of the trochanteral extensor motoneuron was also strongly modulated by changing load. In some postures, sensillum discharges paralleled changes in motor frequency consistent with a known interjoint reflex. These findings demonstrate that tibial campaniform sensilla can monitor the effects of body weight upon the legs and may aid in generating support of body load.

Animals↗
PubMed2005

Quality of life of people with venous leg ulcers: a comparison of the discriminative and responsive characteristics of two generic and a disease specific instruments.

BACKGROUND: Venous leg ulcers are an important source of morbidity in society. Measuring the impact of leg ulcers on quality of life is important within clinical and economic evaluations. In this study we report a validation study of the leg ulcer disease specific Hyland questionnaire and compare its discriminative and responsive characteristics to general health quality of life measures: the SF-12 and EQ-5D. METHODS: HRQoL of venous leg ulcer patients from 9 UK regions was measured using SF-12, EQ-5D and Hyland, at baseline and every three months for 1 year. Psychometric analysis was used to confirm the validity of the Hyland questionnaire. Quarterly scores for all instruments were calculated. Effect size and standardised mean difference were used to investigate the responsiveness to ulcer healing and discriminative abilities of the instruments. RESULTS: Three hundred and eighty seven individuals were recruited into the VenUS I study. Baseline health related quality of life data from the study participants suggested a two factor solution for the Hyland. This questionnaire was associated with small and moderate ability to discriminate individuals according to age, mobility, initial ulcer size and ulcer duration. SF-12 and EQ-5D had good evaluative properties; both instruments were responsive to changes in HRQoL after ulcer healing. High levels of bodily pain were reported in the SF-12 questionnaire, whilst only minor ulcer related discomfort was reported in the Hyland. DISCUSSION: SF-12 and EQ-5D are suitable for exploring dimensions of health related quality of life in people with chronic venous leg ulceration. The responsiveness to healing of the Hyland questionnaire is unclear. We would recommend the use of generic instruments for the measurement of HRQoL in patients with venous leg ulcers.

Adult↗
PubMed1989

Painful versus silent myocardial ischemia during leg and arm exercise testing in stable angina pectoris.

When 51 patients with proven coronary heart disease and stable angina pectoris underwent exercise testing, 22 experienced painful myocardial ischemia during both leg and arm exercise testing (group L + A), whereas 29 patients had such episodes only during the leg testing (group L). Upright bicycle exercise was performed with the legs first, followed 2 days later by arm testing. Exercise was stopped when typical anginal pain and greater than 1-mm ST horizontal depression occurred during leg testing, and when greater than 1-mm ST horizontal depression was noted during arm testing. Heart rate, systolic blood pressure and rate-pressure product for leg and arm testing, either at the beginning of anginal pain or at the time when 1-mm ST depression was noted, were similar. Two-dimensional echocardiography showed that the L group had higher (p less than 0.01) end-systolic volume at rest and decreased (p less than 0.05) ejection fraction during exercise. Coronary angiography showed that the L group had a greater (p less than 0.001) number of patients with 3-vessel disease, a decreased (p less than 0.001) ejection fraction and less patients with 1-vessel disease. In these patients, absence of anginal pain during arm exercise suggests defective segmental transmission of pain sensation related to severe coronary artery disease. Thus, arm testing, in addition to leg testing, seems to be a simple and useful tool for the detection of severe coronary disease.

Angina Pectoris↗
PubMed1993

Asymptomatic and electrically silent myocardial ischemia during upright leg cycle ergometry and treadmill exercise (clandestine myocardial ischemia).

The frequency of "clandestine" (electrically silent and asymptomatic, but scintigraphically evident) myocardial ischemia during treadmill and upright leg cycle ergometric studies was compared in 38 patients with coronary artery disease and reversible ischemia on both thallium-201 scintigraphy and exercise radionuclide angiography. A similar peak double product was attained in both studies. Angina pectoris was significantly more frequent with treadmill exercise than with leg cycling (29 vs 5%, p = 0.0079). An interpretable and positive exercise electrocardiogram occurred in 53% of treadmill tests, but in only 19% of leg cycle tests (p = 0.0025); in a group of 22 patients without scintigraphic ischemia, leg cycle testing had greater specificity (95 vs 64%, p = 0.0248). Ischemia was manifest by symptoms or an abnormal electrocardiogram in 59% of treadmill tests, but in only 18% of leg cycle tests (p = 0.0003). There were no differences between the exercise variables or the degree of scintigraphic abnormalities of the 22 patients with manifest ischemia and the 16 with clandestine ischemia. However, patients with previous coronary artery bypass surgery experienced clandestine ischemia more frequently than did those without bypass surgery (80 vs 33%, p = 0.0103). Thus, clandestine ischemia occurs more frequently during symptom-limited upright leg cycle ergometry (82%) than during treadmill exercise (42%). The symptomatic and electrical manifestations of exercise-induced ischemia have a critical dependence on the type of exercise used.

Adult↗
PubMed1985

Avoidance and escape components of leg position learning in the prothoracic and mesothoracic ganglia of the cockroach, P. americana.

Prothoracic and mesothoracic legs of headless cockroaches with only a ventral nerve cord were trained to lift their legs when shock occurred. The prothoracic leg showed both avoidance learning (a decrease over time in the frequency of leg extension) and escape learning (a decrease in extension duration following shock receipt). The mesothoracic leg showed avoidance learning as fast and as well as the prothoracic leg but was unable to support escape learning. Furthermore, the avoidance component of prothoracic learning showed longer-term retention of several hours whereas the escape component showed only shorter-term retention which did not last 15 minutes.

Animals↗
PubMed1993

Learning of leg position by cockroaches in response to light.

Learning by the cockroach Periplaneta americana was studied using an electronic device that turns off a light in response to leg position. Training and testing were modeled on the Horridge procedure, with the position of a leg of one cockroach (P) controlling stimulation of both itself and a yoked control (R) during training, and the legs of P and R controlling stimulation independently during testing. In addition, testing was followed by reversal, in which each cockroach had to avoid the trained position in order to prevent exposure to light. During half-hour training periods. P cockroaches learned to lift a mesothoracic leg to turn off light. This learning was most evident during reversal, when P cockroaches continued to keep the leg lifted and were therefore exposed to appreciably more light than were R cockroaches. Cockroaches were unable to learn to lower the mesothoracic leg to escape light with a similar procedure.

Animals↗
PubMed1993

An analog technique for recording leg position learning in the cockroach.

Past studies of shock avoidance learning in the cockroach have used an all-or-none method of recording leg position. Leg position was recorded indirectly in terms of the number of shocks the leg initiated. The measure of learning was the decrease in the number of times the leg initiated shock. An analog procedure is described that allows the pattern of leg behavior change to be assessed directly. Thus, the time course and relative magnitude of leg flexions and extensions prior to, during, and following shock can be studied. It will be possible to record peripheral motor nerve activity simultaneously with the behavior and to examine the excitatory and inhibitory interactions of individual neurons that may be involved in such learning.

Animals↗
PubMed1994

Leg position learning in the cockroach nerve cord using an analog technique.

The ultimate goal of this research is to correlate neural activity with leg behavior during learning. Contrary to previous studies of shock avoidance learning in the headless cockroach, in which an all-or-none method of recording was used, we have adopted a direct analog recording of leg position to measure learning in the prothoracic ganglion. This method provides a sensitive and continuous record of leg movement that can be correlated with the interactions of individual neurons that may be involved in such learning. Of the 10 prothoracic legs trained to flex to avoid shock, eight escaped shock by flexion within a maximum of 13 min and seven showed savings when retested. Only four of eight prothoracic legs trained to extend showed avoidance learning and all four showed savings. Electrical stimulation of nerves 3,4,5, and 6 innervating the prothoracic leg revealed which nerves were instrumental in the flexion and extension responses.

Animals↗
PubMed2004

Invasive treatment of chronic limb ischemia according to the Lower Extremity Grading System (LEGS) score: a 6-month report.

BACKGROUND: The invasive treatment of chronic lower extremity peripheral arterial disease (PAD) has become inconsistent. To standardize treatment at our institution, the Lower Extremity Grading System (LEGS) score was devised, based on arteriographic findings, symptoms, functional status, comorbid conditions, and technical factors. The scoring system was used to direct the invasive treatment approach in patients with lower extremity PAD. The purpose of this study was to prospectively assess outcomes of invasive treatment of lower extremity ischemia as directed by LEGS. METHODS: From March 2002 through December 2002, 332 limbs in 227 patients with indications for intervention were scored and treated according to the LEGS score and followed for 6 months. Of the 227 patients, 66.1% were male; median age was 65 years. Diabetes mellitus was present in 44.9% of patients, claudication in 48.5%, and limb-threatening ischemia in 51.5%. Results of treatment as directed by LEGS were judged with the treatment outcome measures of reconstruction patency, limb salvage, mortality, change in ambulatory status, change in independent living status, and change in the short-form health survey (SF-36). RESULTS: Of 332 limbs, 61.5% with a score of 10 to 19 underwent endovascular therapy; 34% with a score of 0 to 9 underwent open revascularization; and 4.5% with a score greater than 20 underwent primary limb amputation. Interventions for the entire cohort as directed by LEGS resulted in 6-month primary reconstruction patency of 82.4%; secondary reconstruction patency, 92.6%; limb salvage, 90%; survival, 89.1%; maintenance of ambulatory status, 85.6%; maintenance of independent living, 88.4%; and statistically significant improvement in health assessment, regardless of treatment type, as determined with the SF-36. There was no statistically significant variability when comparing results according to treatment (open surgery, 0-9 vs endovascular therapy, 10-19) or smaller score group categories (0-5, 6-9, 10-13, 14-19). CONCLUSIONS: At 6 months, treatment as directed by LEGS score resulted in acceptable outcomes. This project is the first reported prospectively confirmed standardization tool for treatment of lower extremity PAD, and, pending independent confirmation by others, provides a comparative baseline against which other standardization efforts can be measured.

Adult↗
PubMed2006

Delta and Hairy establish a periodic prepattern that positions sensory bristles in Drosophila legs.

In vertebrates and invertebrates, spatially defined proneural gene expression is an early and essential event in neuronal patterning. In this study, we investigate the mechanisms involved in establishing proneural gene expression in the primordia of a group of small mechanosensory bristles (microchaetae), which on the legs of the Drosophila adult are arranged in a series of longitudinal rows along the leg circumference. In prepupal legs, the proneural gene achaete (ac) is expressed in longitudinal stripes, which comprise the leg microchaete primordia. We have previously shown that periodic ac expression is partially established by the prepattern gene, hairy, which represses ac expression in four of eight interstripe domains. Here, we identify Delta (Dl), which encodes a Notch (N) ligand, as a second leg prepattern gene. We show that Hairy and Dl function concertedly and nonredundantly to define periodic ac expression. We also explore the regulation of periodic hairy expression. In prior studies, we have found that expression of two hairy stripes along the D/V axis is induced in response to the Hedgehog (Hh), Decapentaplegic (Dpp) and Wingless (Wg) morphogens. Here, we show that expression of two other hairy stripes along the orthogonal A/P axis is established through a distinct mechanism which involves uniform activation combined with repressive influences from Dpp and Wg. Our findings allow us to formulate a general model for generation of periodic pattern in the adult leg. This process involves broad and late activation of ac expression combined with refinement in response to a prepattern of repression, established by Hairy and Dl, which unfolds progressively during larval and early prepupal stages.

Animals↗
PubMed1988

Effects of intermittent pneumatic leg compression for prevention of postoperative deep venous thrombosis with special reference to fibrinolytic activity.

The mechanism of intermittent pneumatic leg compression for prevention of postoperative deep venous thrombosis was investigated. The incidence of postoperative deep venous thrombosis was studied using iodine-125 fibrinogen in 64 patients with malignant disease who had intermittent pneumatic leg compression for 48 hours postoperatively. Changes in euglobulin lysis time and B beta 15-42 peptide were investigated before and after operation in 16 patients with benign disease, in 27 patients with malignant disease who did not have postoperative intermittent pneumatic leg compression, and in another 29 patients with malignant disease who had postoperative intermittent pneumatic leg compression. The overall incidence of deep venous thrombosis was 6.25 percent. A prolongation of euglobulin lysis time was found postoperatively in all three groups, which was significant in malignant disease groups, although less significant in the group with intermittent pneumatic leg compression when compared with the benign disease group. Preoperatively, a significant increase in B beta 15-42 peptide was found in patients with malignant disease when compared with patients with benign disease. Postoperatively, the B beta 15-42 level increased in the same pattern in all groups and no significant differences in the levels were found among them. A significant shortening of euglobulin lysis time by intermittent pneumatic leg compression, in addition to its hemodynamic effects, is considered an important factor in the prevention of postoperative deep venous thrombosis.

Female↗
PubMed2002

Understanding muscle coordination of the human leg with dynamical simulations.

Muscles coordinate multijoint motion by generating forces that cause reaction forces throughout the body. Thus, a muscle can redistribute existing segmental energy by accelerating some segments and decelerating others. In the process, a muscle may also produce or absorb energy, in which case its summed energetic effect on the segments is positive or negative, respectively. This Borelli Lecture shows how dynamical simulations derived from musculoskeletal models reveal muscle-induced segmental energy redistribution and muscle co-functions and synergies. Synergy occurs when co-excited muscles distribute segmental energy differently to execute the motor task. In maximum height jumping, high vertical velocity at lift-off occurs desirably at full body extension because biarticular leg muscles redistribute the energy produced by the uniarticular leg muscles. In pedaling, synergistic ankle plantarflexor force generation during leg extension allows the high energy produced by the uniarticular hip and knee extensors to be delivered to the crank. An analogous less-powerful flexor synergy exists during leg flexion. Hamstrings reduce crank deceleration during the leg extension-to-flexion transition by not only producing energy but delivering it to the crank through its contribution to the tangential (accelerating) crank force, though this hamstrings function occurs at the opposite (flexion-extension) transition when pedaling backwards. In walking, the eccentric quadriceps activity in early stance not only decelerates the leg but also accelerates the trunk. In mid-stance, the uni- and biarticular plantarflexors, by having opposite segmental energetic effects, act in synergy to support the whole body, so segmental potential and kinetic energy exchange can occur. To conclude, the extraction of unmeasurable variables from dynamical simulations emulating task kinematics, kinetics, and EMGs shows how the production of force and energy by individual muscles contribute to the energy flow among the individual segments during task execution.

Bicycling↗
PubMed2004

[Exercise-induced acute bilateral isolated anterolateral compartment syndrome of the leg: a case report of a rare condition].

Acute compartment syndrome of the leg is generally a consequence of trauma. Exercise-induced acute compartment syndrome of the leg is an exceptional clinical entity observed in the context of a chronic compartment syndrome or as an isolated acute syndrome subsequent to an intense effort. Our patient was a young athlete with no history of exercise-induced leg pain. Following a soccer game, he developed an acute leg syndrome involving the anterolateral compartment of both legs. The diagnosis was not suggested by the patient's history (no notion of chronic compartment syndrome) nor the natural history of the condition but was retained on the basis of the clinical presentation and course then confirmed by intramuscular pressure measurements. Emergency treatment by fasciotomy under general anesthesia in the operating room led to cure with no sequela. The fasciotomy was closed on day 9 with simple skin sutures. Surgeons should be aware that acute exercise-induced compartment syndrome (with the risk of severe functional consequences) may be the cause of unexplained intense leg pain. The diagnosis is established on the basis of clinical findings and measurement of intramuscular pressures. Pain is the cardinal sign, sometimes associated with sensorial deficit. The compartment is hard and painful at palpation. Passive stretching exacerbates the pain. Compartment pressure is required for certain diagnosis, most Authors accepting > 30mmHg as a positive test. Emergency fasciotomy is required.

Acute Disease↗
PubMed2001

Spatial regulation of DELTA expression mediates NOTCH signalling for segmentation of Drosophila legs.

The Notch (N) signalling pathway is recruited for segregation of cell fates in a number of Drosophila tissue types. We show here that N dependent segmentation of Drosophila legs is regulated by a dynamic pattern of expression of its ligand, DELTA (DL). During third larval instar and early stages of pupation, high levels of DL expression is seen in stripes of cells in the leg imaginal discs which later form the proximal borders of leg joints. These domains also displayed heightened Dl enhancer activity. During subsequent stages of pupation, following segmentation of the leg primordium, DL expression becomes uniform throughout these segments barring the joints. We further show that regulatory Dl mutations or mis-expression of DL abolish leg segmentation. Domains of N signalling for segmentation of legs of flies are thus set up by a stringent spatial regulation of expression of its ligand at the segment border. Further, a comparable role of DL in antennal development reveals a common paradigm of DL-N signalling for segmentation of appendages in flies.

Animals↗
PubMed1999

Measuring health-related quality of life in patients with venous leg ulcers.

INTRODUCTION: The effect on quality of life by healing leg ulcers is not known and no validated disease-specific tool is available for measuring health-related quality of life (HRQoL) for people with venous leg ulcers. The objective of this paper was to compare four generic instruments [MOS 36-Item Short-Form Health Survey (SF-36); EuroQol (EQ); McGill Short Form Pain Questionnaire (SF-MPQ) and the Frenchay Activities Index (FAI)] used for measuring HRQoL in people with venous leg ulcers, and to offer guidance on the most appropriate tool for researchers. METHODS: Two hundred and thirty-three patients with venous leg ulcers were recruited as part of a randomised controlled trial of the cost-effectiveness of community leg ulcer clinics. Subjects completed questionnaires containing the four instruments on three occasions (initial assessment, 3 and 12 months). The discriminative and evaluative properties of the four instruments were compared. RESULTS: All four instruments were acceptable to patients, taking a mean of 19.3 (SD 6.3) min to complete. At initial assessment, the SF-MPQ had poorer discriminative properties than the other three instruments and was not able to distinguish between the different patient groups in relation to age and ulcer duration. The FAI was good at discriminating between the different patient groups (at initial assessment) in relation to age, mobility and ulcer size. At the three-month follow-up, the SF-MPQ was more responsive than the other measures and detected changes in HRQoL, whereas the EQ and SF-36 did not. At 12 months, the SF-MPQ still identified differences and the SF-36 and EQ also did at this stage. CONCLUSION: In the absence of a validated condition-specific tool for measuring changes in general health status for patients with venous leg ulcers, we make the following recommendations. For evaluating the outcome of interventions with a short-term follow-up (three months) in a clinical study we recommend the SF-MPQ and for 12-month follow-up in a clinical study the SF-36, with or without the SF-MPQ.

Aged↗
PubMed1987

Decrease in human quadriceps muscle protein turnover consequent upon leg immobilization.

Quadriceps muscle protein turnover was assessed in the post-absorptive state in six men immediately after the end of unilateral leg immobilization (37 +/- 4 days) in a plaster cast after tibial fracture. A primed-constant intravenous infusion of L-[1-13C]leucine was administered over 7 h. Quadriceps needle biopsies, taken bilaterally at the end of the infusion, were analysed for muscle protein leucine enrichment with 13C. Quadriceps muscle protein synthetic rate, calculated from the fractional incorporation of [13C]leucine into protein compared with the average enrichment of blood alpha-ketoisocaproate, was 0.046 +/- 0.012%/h in the uninjured leg, but was only 0.034 +/- 0.007%/h in the quadriceps of the previously fractured leg (P less than 0.05, means +/- SD). Muscle RNA activity (i.e. protein synthetic rate per RNA) fell from 0.27 +/- 0.08 microgram of protein synthesized h-1 microgram-1 of RNA in the control leg to 0.14 +/- 0.03 microgram of protein synthesized h-1 microgram-1 of RNA in the immobilized leg (P less than 0.02). Immobilization was associated with a significant atrophy of type I muscle fibres (mean diameter 69.5 +/- 21 microns immobilized, 81.1 +/- 18 microns control, P less than 0.05), but no significant change occurred in type II fibre diameter. Mean quadriceps fibre volume calculated from the values for fibre diameter and percentage of each fibre type, was smaller in the injured leg by 10.6%; this value was near to the calculated difference in muscle thigh volume (calculated from thigh circumference and skin-fold thickness) which was less by 8.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

Elevated expression of extracellular matrix metalloproteinase inducer (CD147) and membrane-type matrix metalloproteinases in venous leg ulcers.

BACKGROUND: Matrix metalloproteinases (MMPs) contribute to matrix remodelling in venous leg ulcers. Extracellular MMP inducer (EMMPRIN; CD147) has been reported to increase MMP expression, and membrane type 1 MMP (MT1-MMP) has been implicated in the activation of MMPs. OBJECTIVES: To examine whether and to what degree EMMPRIN, MMP-2, MT1-MMP and membrane type 2 MMP (MT2-MMP) are expressed in venous leg ulcers as well as the association with MMP activity. METHODS: EMMPRIN, MMP-2, MT1-MMP and MT2-MMP were analysed by zymography and immunohistochemistry in biopsies from healthy skin and lesional tissue from venous leg ulcers. RESULTS: Zymography provided direct evidence of increased proteolytic activity of MMP-2 in lesional skin in comparison with healthy controls. Immunostaining showed intense expression of EMMPRIN, MMP-2, MT1-MMP and MT2-MMP in dermal structures of venous leg ulcers, whereas only EMMPRIN and MMP-2 showed elevated expression in perivascular regions. Our findings indicate that venous leg ulcers are characterized by elevated expression of EMMPRIN, MMP-2, MT1-MMP and MT2-MMP. The immunohistological findings of skin alterations reflect the dynamic process of activation of soluble and membrane-bound MMPs, which may be highly induced by EMMPRIN. CONCLUSIONS: These data suggest for the first time that membrane-bound MMPs may favour enhanced turnover of the extracellular matrix and support unrestrained MMP activity in venous leg ulcers.

Antigens, CD↗