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PubMed2000

Legged insects select the optimal locomotor pattern based on the energetic cost.

The gait transition in legged animals has attracted many researchers, and its relation to metabolic cost and mechanical work has been discussed in recent decades. We assumed that the energetic cost during locomotion is given by the sum of positive mechanical work and the heat energy loss that is proportional to the square of joint torque and examined the optimal locomotor pattern based on the energetic cost in a simple dynamical model of a hexapod by computer simulations. The obtained results well agree with characteristics in the locomotor patterns in legged animals; for example, the leg protraction time, step length, and the metabolic cost of transport are almost constant for many velocities, the leg cycling period decreases with velocity, and the energetic cost of locomotion induced by carrying loads linearly increases with mass loaded. This correspondence of the results of calculation to experimental results suggest that the heat energy loss for torque generation is proportional to the square of the torque during locomotion, and that the locomotor pattern in legged animals is highly optimized based on the energetic cost.

Animals↗
PubMed2003

Comparative analysis of leg and antenna development in wild-type and homeotic Drosophila melanogaster.

The insect leg and antenna are thought to be homologous structures, evolved from a common ancestral appendage. The homeotic transformations of antenna to leg in Drosophila produced by mutation of the Hox gene Antennapedia are position-specific, such that every particular antenna structure is transformed into a specific leg counterpart. This has been taken to suggest that the developmental programmes of these two appendages are still similar. In particular, the mechanisms for the specification of a cell's position within the appendage would be identical, only their interpretation would be different and subject to homeotic gene control. Here we explore the degree of conservation between the developmental programmes of leg and antenna in Drosophila and other dipterans, in wild-type and homeotic conditions. Most of the appendage pattern-forming genes are active in both appendages, and their expression domains are partially conserved. However, the regulatory relationships and interactions between these genes are different, and in fact cells change their expression while undergoing homeotic transformation. Thus, the positional information, and the mechanisms which generate it, are not strictly conserved between leg and antenna; and homeotic genes alter the establishment of positional clues, not only their interpretation. The partial conservation of pattern-forming genes in both appendages ensures a predictable re-specification of positional clues, producing the observed positional specificity of homeotic transformations.

Animals↗
PubMed2004

Selection on male size, leg length and condition during mate search in a sexually highly dimorphic orb-weaving spider.

Mate search plays a central role in hypotheses for the adaptive significance of extreme female-biased sexual size dimorphism (SSD) in animals. Spiders (Araneae) are the only free-living terrestrial taxon where extreme SSD is common. The "gravity hypothesis" states that small body size in males is favoured during mate search in species where males have to climb to reach females, because body length is inversely proportional to achievable speed on vertical structures. However, locomotive performance of males may also depend on relative leg length. Here we examine selection on male body size and leg length during mate search in the highly dimorphic orb-weaving spider Argiope aurantia, using a multivariate approach to distinguish selection targeted at different components of size. Further, we investigate the scaling relationships between male size and energy reserves, and the differential loss of reserves. Adult males do not feed while roving, and a size-dependent differential energy storage capacity may thus affect male performance during mate search. Contrary to predictions, large body size was favoured in one of two populations, and this was due to selection for longer legs. Male size was not under selection in the second population, but we detected direct selection for longer third legs. Males lost energy reserves during mate search, but this was independent of male size and storage capacity scaled isometrically with size. Thus, mate search is unlikely to lead to selection for small male size, but the hypothesis that relatively longer legs in male spiders reflect a search-adapted morphology is supported.

Animals↗
PubMed1983

Discharge patterns of reticulospinal neurons corresponding with quadrupedal leg movements in thalamic cats.

To analyze the discharge patterns of the reticulospinal (R-S) neurons associated with four-limb movement, we recorded the unit spikes of 108 R-S neurons in 18 thalamic cats. (1) Unit spikes of R-S neurons exhibited alternating firings during leg movements, not only stepping on the treadmill but also upon passive flexion and extension movement by the experimenter's hand. (2) R-S neurons manifested firing patterns associated with diagonal, reciprocal and quadrupedal leg movements. About half of the neurons showed reciprocal patterns upon bilateral forelimb movements; spikes were increased when the ipsilateral forelimb was in a backward position; they were decreased when that leg was in a forward position. In contrast, the spikes were increased when the contralateral forelimb was placed forward and decreased when it was backward. About 15% of the R-S neurons showed discharge patterns correlated with quadrupedal leg movements. Firing increased when the left forelimb and right hindlimb were placed backward and the left hindlimb and right forelimb were forward. In contrast, when the position of all 4 limbs was reversed, firing rates decreased. (3) When brief touch stimulation was applied to the skin around the leg, bursting spikes were obtained; these were suppressed upon touching the skin of the contralateral limb. Even after transection of the muscle nerves, alternating firings were observed. (4) Local anesthesia to the shoulder joint resulted in a marked reduction of spontaneous discharges and alternating firings. (5) Our results indicate that afferents of joints and of cutaneous origins in individual limbs ascend to the brainstem reticular formation, that integrative action is organized as pattern generation in that region, and that this patterned information is sent to the spinal cord via the reticulospinal tracts.

Animals↗
PubMed1994

Cross-leg free muscle flaps for reconstruction of open fractures of the tibia.

In two patients in whom the injured leg was not suitable for reconstruction using a routine free tissue transfer, a cross-leg free muscle flap was used, i.e. the vessels of a free muscle flap were anastomosed to donor vessels on the uninjured leg and the muscle flap used to reconstruct a defect on the opposite leg. Both operations were successful, with the transferred muscle becoming well vascularized from the recipient bed at the site of injury. In both cases, use of the uninjured leg to transfer the free flap caused minimal morbidity.

Adolescent↗
PubMed1991

Sleep-related periodic leg movements (nocturnal myoclonus) due to spinal cord lesion.

Ten patients with involuntary leg movements due to myelopathy were studied clinically and polysomnographically. The clinical manifestation and polysomnographical findings of involuntary leg movements were identical to sleep-related periodic leg movement (PLM) (nocturnal myoclonus). Since 2 patients had complete transection of spinal cord due to injury or vascular accident, the spinal cord deprived of supraspinal influences was considered to generate the rhythm of PLM. Suppression of the leg movements during REM sleep was not obvious in the patients with complete transection of spinal cord. In addition, PLM alternated from one side to the other 1-4 times a night with intervals of 1-4 h in all patients. This alternation also seemed to be from the spinal cord. This PLM of spinal cord origin was different from spinal myoclonus in their clinical features although both were generated within the spinal cord. PLM of spinal cord origin showed a triple flexion of the ankle, knee and hip, and this was very similar to a flexor withdrawal reflex which all patients exhibited. Therefore, it was suggested that PLM of spinal cord origin has a common mechanisms with spinal automatism. Although all patients had extensor plantar responses, PLM preceded the paresis in three patients and the severity of paresis was variable. There was no laterality of left and right PLMs even in patients with weakness of the leg on one side. This suggested that PLM of spinal cord origin might be induced by the interruption of the tract which was separate from, but runs near the corticospinal tract.

Adult↗
PubMed1992

Volume loading of the heart by "leg up" position and head down tilting (-6 degrees) (HDT).

Head down tilting is widely used to increase preload and to induce intrathoracic blood pooling similar to microgravity. During daily routine, this venous pooling is performed by raising the legs up. In this study, both these approaches have been compared by invasive measurement using a right heart catheter. In patients with moderate coronary artery disease, diagnostic right heart catheterization was performed by the Swan-Genz-techniques. All measurements were performed with head down tilting (-6 degrees) and with "leg up" position. Patients then received Nitroglycerin to countermeasure the preload changes. Pressures in the pulmonary artery as well as in the wedge position increased significantly during leg up and HDT. However, changes were significantly more pronounced in the "leg up" position than during HDT. No changes were observed for arterial blood pressure, cardiac output, stroke volume and resistances. Nitroglycerin during HDT lowered blood pressure and pressures in the pulmonary artery and in PCW-position and reduced cardiac output significantly. Both approaches of volume loading of the heart induced significant changes and increases of preload. However, changes were more pronounced during the "leg up" position than during HDT. It is questioned whether HDT with -6 degrees is appropriate to truly reflect hemodynamic alterations during simulated weightlessness.

Atrial Function↗
PubMed1995

Surgical correction of leg alignment in unilateral knee osteoarthrosis reduces the load on the hip and knee joint bilaterally.

Seventeen patients with strictly unilateral medial knee osteoarthrosis that justified surgical treatment constituted the study group. No patient had any symptoms from the hip or ankle joints or from the other knee. Eight patients were operated with high tibial osteotomy and nine were operated with unicompartmental prosthetic replacement (Brigham model). The forces and the external moment about the hip, knee, and ankle joints of the involved and uninvolved leg were calculated before and 1 year after corrective surgery and compared to the external moment in 10 normal controls. Clinical examinations was performed and the hip-knee-ankle angle in the involved leg was determined from whole-leg weightbearing radiographs before and 1 year after surgery. The external moments about the hip, knee, and ankle joints and the knee moment arms at mid-stance in the frontal plane during gait were determined with a Kistler force plate and a videorecording system. All patients improved clinically after surgery. The mean hip-knee-ankle angle changed from 11 degrees of varus to 0 degrees. In the uninvolved leg the mid-stance adduction moments about the hip and knee joints were significantly increased compared to normal subjects in the control group before surgery, but reduced to a normal level 1 year after surgery. This reduction was mainly due to a significant reduction of the medially directed force. The moments about the ankle joints were not found to be changed by the knee deformity or by the corrective surgery. RELEVANCE: This study demonstrates that a varus malalignment in the osteoarthrotic knee is accompanied by increased load about the uninvolved hip and knee joint. One might expect a more rapid progression of degenerative changes in joint cartilage as a consequence of such increased load. The reduced load after surgical correction of leg alignment might be beneficial to patients with osteoarthrosis of their hip and knee joints.

Journal Article↗
PubMed1996

Maximum voluntary weight-bearing by the affected and unaffected legs in standing following stroke.

OBJECTIVE: To compare stroke patients to control subjects for ability to transfer body weight onto the affected and unaffected leg in standing; to investigate intra-session reliability. DESIGN: Comparative clinical study conducted within a single session. BACKGROUND: There is a paucity of quantitative data about maximum voluntary weight-bearing in patients during rehabilitation following stroke. METHODS: A Kistler force platform was used to quantify maximum amount of body weight transferred to a single limb in the lateral and forward directions during weight-shifting. Twelve control subjects matched by gender and age (median 64 years) were compared to 12 inpatient stroke patients after a median of 37 days post-onset. RESULTS: The median score for control subjects was approximately 95% of body weight to each leg in both directions. In contrast, stroke patients transferred less body weight (P<0.01) to the affected leg (65.5% lateral; 54.9% forward) and also to the unaffected leg (85.0% lateral; 80.1% forward). For the stroke patients, transfer of body weight was more challenging in the forward direction than the lateral direction on the affected leg (P<0.05). Relative to individual differences in the stroke group, error due to the repeated measurement process was low. CONCLUSION: The testing procedure was found to discriminate between stroke patients and control patients and had high retest reliability within a single session.

Journal Article↗
PubMed1990

Thermal enhancement of radiation-induced leg contracture.

Early and late damage in the normal tissues of the legs of mice was compared following treatment with radiation alone or radiation followed immediately by hyperthermia. Hyperthermia was given by immersing the hind leg in a water bath at 43.0 degrees, 43.3 degrees, or 43.5 degrees C for 1 hr. Damage was assayed by measuring leg contracture at various intervals from 5 to 365 days after treatment. At 5 days after treatment, only hyperthermia-induced contracture was observed. At 10 and 20 days, contracture increased with radiation dose in heated legs, but little contracture had developed in mice treated with radiation alone. By 45 through 365 days, however, contracture correlated with radiation dose both in mice treated with radiation alone as well as in those treated with radiation and hyperthermia. The greatest differential in the slopes of the dose response curves, suggesting hyperthermic radiosensitization, was seen 20 days after treatment. Nevertheless, at 365 days, contracture was still significantly greater in the mice treated with radiation and hyperthermia (43.5 degrees bath) than in the irradiated controls. Thermal enhancement ratios (TERs) were calculated from LCD50 values (LCD50 = radiation dose that would give a stated level of leg contracture in 50% of the mice). For greater than or equal to 3 mm contracture, TERs were 4.1 to 7.9 at 30 days, depending on bath temperature, but only 1.1 to 1.5 at 365 days. For an isoeffect of greater than or equal to 7 mm contracture, TERs were 1.9 to 5.3 at 30 days, and 0.8 to 1.8 at 365 days. Thus, contracture was enhanced more at 20 to 30 days after treatment with radiation and hyperthermia than at 120 through 365 days. Radiation damage not only appeared earlier in mice treated with hyperthermia than in those treated with radiation alone, but after the highest temperature tested (43.5 degrees bath), contracture was greater from 5 through 365 days after treatment than in controls treated with radiation alone.

Animals↗
PubMed2006

Comparison of different sampling techniques and enumeration methods for the isolation and quantification of Campylobacter spp. in raw retail chicken legs.

Comparable quantitative data of Campylobacter spp. on chicken products are a major data lack for quantitative risk assessment approaches. The objective of this study was to compare two different sampling techniques for the isolation and enumeration of Campylobacter spp. in chicken and to evaluate a suitable enumeration method comparing the most probable number (MPN) technique to the direct plating method. For this, 90 packages containing at least two raw chicken legs were examined for the comparison of sampling techniques, rinsing one leg and homogenizing 25 g of skin of the other leg of each package; both sample preparation types were examined by direct plating method and MPN technique in 40 out of 90 packages. Of the skin samples, 70% (63/90), and of the rinse samples, 77% (69/90), were Campylobacter-positive. Enumeration of Campylobacter spp. by direct plating revealed a median of log 4 cfu/leg surface in skin samples (S.D.=0.6) and a median of log 4.3 cfu/leg surface in rinse samples (S.D.=0.9) of the rinse samples; 73% (37/51) had higher numbers of Campylobacter spp. than the skin samples although the difference was not significant (p=0.08). The correlation coefficient of Campylobacter counts in skin and rinse samples was 0.43. The prevalence of Campylobacter spp. in rinse samples was 58% (23/40). In 5% (2/40) of the rinse samples, numbers of Campylobacter spp. could be detected only by the MPN technique due to the lower detection limit compared to the direct plating method. The MPN technique turned out to be unsuitable for the enumeration of Campylobacter spp. in skin samples because a layer formation on the top of the incubated MPN-tubes leads to irregular MPN results. Out of 80% (16/20) of the compared rinse samples, the direct plating detected higher numbers of Campylobacter spp., with a median count of log 4.2 cfu/leg surface (S.D.=1) compared the MPN technique where a median of log 4 cfu/leg surface (S.D.=1.1) was obtained. The difference was not significant (p=0.05). A highly positive correlation coefficient of 0.9 was observed between the direct plating and the MPN technique. Both sampling methods, rinsing the chicken leg and homogenizing the skin, are suitable for the detection and quantification of Campylobacter spp.; the direct plating method was superior to the MPN technique for enumerating Campylobacter spp. in raw chicken legs at retail level because enumeration is more rapid and less laborious.

Animals↗
PubMed2006

Conservative versus surgical treatment of venous leg ulcers: a prospective, randomized, multicenter trial.

BACKGROUND: The prevalence of venous leg ulcers is as high as 1% to 1.5%, and the total costs of this disease are 1% of the total annual health care budget in Western European countries. Treatment modalities are conservative or surgical. Subfascial endoscopic perforating vein surgery (SEPS) combined with superficial vein ligation is performed in many centers to address vein incompetence in patients with chronic venous leg ulcers. Several reports describe good healing and low recurrence rates, although a randomized trial to compare surgical treatment including SEPS and treatment of the superficial venous system to conservative modalities has never been performed. Therefore, a prospective, randomized, multicenter trial was conducted to study whether ambulatory compression therapy with venous surgery is a better treatment than just ambulatory compression therapy in venous leg ulcer patients. METHODS: Patients with an active (open) venous leg ulcer (CEAP C6) qualified for the study. The study consisted of two treatment groups. All patients were treated by standardized ambulatory compression therapy, and half of the patients received SEPS. Concomitant superficial venous incompetence was also treated in the second group. For allocation to both treatment groups, each patient was assigned by a computer program at the randomization center. The primary goal of the study was to compare the ulcer-free period during follow-up in both study groups. Secondary end points were ulcer healing and recurrence rates. RESULTS: From April 1997 until January 2001, 200 ulcerated legs (170 patients) were included in the study in 12 centers in The Netherlands. A total of 97 ulcers were allocated to the surgical group and 103 to the conservative group. Patient characteristics were similar in the two treatment groups at baseline, with the exception of a higher proportion in the conservative group of diabetes mellitus. Healing rates were 83% in the surgical group and 73% in the conservative group (not significant; median time to healing, 27 months). Recurrence rates were the same in both treatment groups (22% surgical vs 23% conservative). During follow-up of a mean of 29 months (median, 27 months) in the surgical group and 26 months (median, 24 months) in the conservative group, we found that in the surgical group, the ulcer-free rate was 72%, whereas in the conservative group this rate was 53% (P = .11; Mann-Whitney test). Patients with recurrent ulceration or medially located ulcers in the surgical group had a longer ulcer-free period than those treated in the conservative group (P = .02 for both). A first-time ulcer and one of the centers also had a positive effect on the ulcer-free period during follow-up (P < .001 and P = .02), independent of the treatment group. Deep vein incompetence did not affect the ulcer-free period. CONCLUSIONS: In conclusion, we suggest that patients with medial and/or recurrent ulceration should receive surgery combined with ambulatory compression therapy. A dedicated center should provide care for those patients.

Aged↗
PubMed1998

Etiology and diagnosis of bilateral leg edema in primary care.

PURPOSE: To identify the causes of bilateral leg edema in a primary care setting, and to determine the ability of primary care providers to arrive at the correct diagnosis using the information available at the initial clinical encounter. PATIENTS AND METHODS: Fifty-eight ambulatory adult patients with bilateral leg edema were enrolled at an inner city family practice during a 3-year period. Historical information, physical examination findings, and clinical impressions of primary care providers were compared with the results of laboratory evaluations consisting of echocardiograms, venous duplex ultrasound leg scans, serum albumin levels, and when appropriate, 24-hour urinalyses. RESULTS: Forty-five patients (78%) completed the study. The initial clinical impression was venous insufficiency in 32 (71%) patients and congestive heart failure in 8 (18%) patients. In actuality, 15 (33%) patients had a cardiac condition as a cause of their leg edema, and 19 (42%) had pulmonary hypertension. All of the patients with heart disease, and almost all of those with pulmonary hypertension, were age 45 years or older. Only 10 (22%) of the subjects had venous insufficiency. Renal conditions, medication use, and hypoalbuminemia were less common. CONCLUSIONS: Utilizing clinical information only, many patients with cardiopulmonary pathology were incorrectly diagnosed as having more benign conditions, most commonly venous insufficiency. Echocardiographic evaluation, including an estimation of pulmonary artery pressure, may be advisable in many patients with bilateral leg edema, especially if they are at least 45 years old.

Clinical Competence↗
PubMed1998

In vivo accuracy of two radiographic systems in the detection of Björk-Shiley convexo-concave heart valve outlet strut single leg separations.

OBJECTIVE: Modified cineradiographic systems have been used clinically to detect partially broken outlet struts in normally functioning Björk-Shiley convexo-concave heart valves. Almost all such valves were explanted, presuming that full failure would likely follow. Inasmuch as the clinical setting only rarely permits examination of normally rated valves, the accuracy of radiographic detection cannot be clinically defined. This study uses the clinical radiographic technique in sheep implanted with known-status convexo-concave valves, comparing its accuracy and that of a newly developed, geometric image magnification radiography system. METHODS: Twenty-one sheep with mitral convexo-concave valves were studied on both systems. Five were used for extensive training. When operators were expert with both systems, images of four intact valves and 12 valves with outlet strut single leg separations, along with a seventeenth single leg separation valve used for calibration, were integrated into 112 image sets organized into a balanced incomplete block design for evaluation by eight trained, blinded reviewers. RESULTS: Cineradiography sensitivity was 24% versus 31% for direct image magnification. The odds ratio for detection of single leg separation by direct image magnification versus cineradiography was 2.0 (95% confidence interval, 0.76 to 5.9; p = 0.13). Cineradiography specificity was 93% versus 90% for direct image magnification. Sensitivity and specificity varied markedly by reviewer, with sensitivity ranging from 8% to 55% and specificity from 51% to 100% for the combined technologies. CONCLUSIONS: The data support the need for more intensive training for convexo-concave valve imaging and further investigation of unconventional radiographic technologies. Clinical cineradiography of convexo-concave valves may detect as little as 25% of valves having a single leg separation, underestimating the prevalence of single leg separations and thereby implying more rapid progression to full fracture than is actually the case.

Animals↗
PubMed2000

Behaviour and leg injuries in dairy cows kept in cubicle systems with straw bedding or soft lying mats.

In order to reduce straw input, soft lying mats are used increasingly instead of straw bedding in cubicle systems for dairy cows. This study aimed at comparing different types of soft lying mats with straw bedding regarding cow behaviour and leg injuries. Data were collected on five farms with straw bedding and on 13 farms using four types of soft lying mats consisting of different materials. On each farm, lying behaviour of 10 cows was recorded automatically during 3 days by means of a pneumatically operated resting sensor fitted in a belt. In addition, standing up and lying down behaviour of cows was quantified by direct observations, and all cows on a given farm were checked once for leg injuries.There were no significant differences between cows kept in cubicle systems with soft lying mats and straw bedding regarding the total time spent lying per day and the number of lying bouts per day. Standing up and lying down behaviour also did not differ between cows with access to soft lying mats and straw bedding. Leg injuries were most frequent in the tarsal and carpal joints. Cows kept in cubicle systems with soft lying mats had a significantly higher incidence of both hairless patches more than 2 cm in diameter (P<0.001) and scabs or wounds less than 2 cm in diameter (P<0.001) located in the tarsal joints than cows in cubicle systems with straw bedding. With the carpal joints, on the other hand, the incidence of leg injuries did not differ significantly between these two housing conditions. In conclusion, the results of this study indicate that soft lying mats are equivalent to straw bedding in terms of cow behaviour but less favourable with respect to leg injuries located in the tarsal joints.

Journal Article↗
PubMed1997

Sensori-sensory afferent conditioning with leg movement: gain control in spinal reflex and ascending paths.

Studies are reviewed, predominantly involving healthy humans, on gain changes in spinal reflexes and supraspinal ascending paths during passive and active leg movement. The passive movement research shows that the pathways of H reflexes of the leg and foot are down-regulated as a consequence of movement-elicited discharge from somatosensory receptors, likely muscle spindle primary endings, both ipsi- and contralaterally. Discharge from the conditioning receptors in extensor muscles of the knee and hip appears to lead to presynaptic inhibition evoked over a spinal path, and to long-lasting attenuation when movement stops. The ipsilateral modulation is similar in phase to that seen with active movement. The contralateral conditioning does not phase modulate with passive movement and modulates to the phase of active ipsilateral movement. There are also centrifugal effects onto these pathways during movement. The pathways of the cutaneous reflexes of the human leg also are gain-modulated during active movement. The review summarizes the effects across muscles, across nociceptive and non-nociceptive stimuli and over time elapsed after the stimulus. Some of the gain changes in such reflexes have been associated with central pattern generators. However, the centripetal effect of movement-induced proprioceptive drive awaits exploration in these pathways. Scalp-recorded evoked potentials from rapidly conducting pathways that ascend to the human somatosensory cortex from stimulation sites in the leg also are gain-attenuated in relation to passive movement-elicited discharge of the extensor muscle spindle primary endings. Centrifugal influences due to a requirement for accurate active movement can partially lift the attenuation on the ascending path, both during and before movement. We suggest that a significant role for muscle spindle discharge is to control the gain in Ia pathways from the legs, consequent or prior to their movement. This control can reduce the strength of synaptic input onto target neurons from these kinesthetic receptors, which are powerfully activated by the movement, perhaps to retain the opportunity for target neuron modulation from other control sources.

Animals↗
PubMed1999

Tissue-specific distribution of breast-muscle-type and leg-muscle-type troponin T isoforms in birds.

In order to show the tissue-specific distribution of troponin T (TnT) isoforms in avian skeletal muscles, their expression was examined by electrophoresis of the breast and leg muscles of seven avian species and immunoblotting with the antiserum against fast skeletal muscle TnT. It has been reported in the chicken that breast-muscle-type (B-type) and leg-muscle-type (L-type) TnT isoforms are expressed specifically in the adult breast and leg muscles, respectively. Their differential expression patterns were confirmed in all birds examined in this study. The expression of a segment encoded by the exon x series of TnT was also examined by immunoblotting with the antiserum against a synthetic peptide derived from the exon x3 sequence, because the segment has been shown to be included exclusively in the B-type, but not in the L-type TnT. The expression of the segment was found only in the breast muscle, but not in the leg muscle of all birds examined. TnT cDNA sequences from the duck breast and leg muscles were determined and showed that only B-type TnT had an exon x-related sequence, suggesting that the expression of B-type TnT containing the exon x-derived segment is conserved consistently in the birds.

Amino Acid Sequence↗
PubMed2002

Selective low-level leg muscle training alleviates dyspnea in patients with heart failure.

OBJECTIVES: The purpose of this study was to demonstrate in patients with moderate to severe heart failure that exertional dyspnea can be alleviated by improving muscle function. BACKGROUND: Dyspnea is a frequent limiting symptom in patients with chronic heart failure (CHF). This sensation may originate from activation of receptors in the musculature rather than the lung. METHODS: To investigate whether dyspnea could be alleviated by selective changes in leg muscle function, we performed isolated lower-limb training in 17 patients with severe CHF. Eight patients learned guided imagery relaxation techniques and served as an active control group. Exercise training consisted of three months of low-level bicycle and treadmill exercise such that minute ventilation was <25 l/min. Leg calisthenics were also performed. Maximal and submaximal exercise performance, respiratory and quadriceps muscle strength and endurance and quality-of-life and dyspnea scales were measured before and after each intervention. Metabolic stress testing (VO(2)), pulmonary function tests and isokinetic strength testing were also performed. RESULTS: In the active control group, no changes in leg muscle function, pulmonary function, maximal and submaximal exercise performance or quality-of-life questionnaires were observed. In the training group, peak torque of leg flexors (pre: 39 +/- 15 ft-lb; post: 50 +/- 13 ft-lb; p < 0.002) increased and the fatigue ratio decreased, indicating improved strength and endurance of the leg muscles. Maximal inspiratory and expiratory mouth pressures and maximum voluntary ventilation were unchanged. Peak VO(2) was increased (pre:12 +/- 2.2 ml/kg/min; post: 14 +/- 2.6 ml/kg/min) as well as the duration of exercise at 70% peak VO(2) increased (pre: 11.5 +/- 3.1 min; post: 21.5 +/- 5.4 min; p < 0.003). Perceived dyspnea during the submaximal testing was decreased. Minnesota Living with Heart Failure Score, Guyatt Dyspnea Scale, and the Transitional Dyspnea Index were all improved with training (all p < 0.05). CONCLUSIONS: We concluded that improvement of limb muscle function alleviates dyspnea and improves exercise performance in patients with CHF.

Adult↗