Enteral absorption of insulin in rats from mucoadhesive chitosan-coated liposomes

Whole muscle contractile characteristics and fatigue resistance were studied in male patients with chronic heart failure (n = 6) and in healthy control subjects (n = 6). Maximum voluntary isometric strength in the major muscle groups of leg (plantar flexors and knee extensors) and arm (elbow extensors and elbow flexors), was found to be similar for both groups of subjects. However, a faster isometric twitch time course was observed in the plantar flexor and knee extensor muscles of heart failure chronic patients. The poor resistance to fatigue in the knee extensors of chronic heart failure patients was confirmed in the present study, but using twitch interpolation this was shown not to be due to poor activation. The plantar flexors of chronic heart failure patients also showed a tendency to be less resistant to fatigue, even when the muscle was activated by direct electrical stimulation. The present study shows that independent of muscle strength, patients with chronic heart failure may possess muscles that are faster to contract and less resistant to fatigue. However, it seems this increased fatigability is not due to poor muscle activation.     

A comparison of the contractile properties of the muscles of the lower extremities in man

The physiological features of two antagonistic muscle groups, the dorsiflexors and plantar flexors of the ankle, have been compared in 11 healthy subjects aged 15-17 years (+/- SE; 16 +/- 1.2 years). Contractile properties of plantar flexors of the foot, namely of tibialis anterior (TA) and extensors triceps surae (TS) have been estimated by mechanical parameters of voluntary and electrically evoked contractions. All test subjects exhibited tolerance to supramaximal force of electric stimulation of n. tibialis and n. peroneus profundus at a frequency of 150 impulses.s-1 (for TS) and 150 impulses.s-1 and 250 impulses.s-1 (for TA). TA displayed high velocity and force-velocity properties (p < 0.05-0.001); TS had high force parameters (p < 0.05-0.01). The magnitude of force deficiency observed during voluntary contraction of these muscles is lower in TA and higher in TS (p < 0.05). The results permit supposing that differences in contractile properties of the muscles under study depend on a various specific contribution of peripheral and CNS factors.     

Effect of N-acylethanolamines with different acyl-chains on DPPC multilamellar liposomes

Relationships between lower extremity strength and stride characteristics were studied in 24 patients with post-polio syndrome. Maximum isometric torques were measured in the ankle plantar flexors, hip and knee extensors, and hip abductors. Gait velocity, stride length, and cadence were recorded during free and fast walking. Step-wise regression analysis was performed to determine which muscle groups best predicted ambulatory function. Plantar flexion torque was the best predictor of velocity (r = .55 free walking and r = .76 fast) and cadence (r = .46 free and r = .58 fast). The combination of plantar flexion and hip abduction torques was the best predictor of fast stride length (r = .78). These findings emphasize the important role of the plantar flexor muscles in gait. Knee extension torque was the poorest predictor for each of the gait parameters. Several patients demonstrated gait deviations that minimized the penalty of quadriceps weakness. Without a contracture or an orthosis, however, no adequate substitution exists for weak plantar flexion.     

Therapeutic intervention and signaling

To examine the effects of rapid dehydration on isometric muscular strength and endurance, seven men were tested at baseline (control) and after a dehydration (dHST) and a euhydration (eHST) heat stress trial. The dHST consisted of intermittent sauna exposure until 4% of body mass was lost, whereas the eHST consisted of intermittent sauna exposure (same duration as dHST) with water replacement. Peak torque was determined for the knee extensors and elbow flexors during three isometric maximal voluntary contractions. Time to fatigue was determined by holding a maximal voluntary contraction until torque dropped below 50% peak torque for 5 s. Strength and endurance were assessed 3.5 h after the HSTs (no food or water intake). Body mass was decreased 3.8+/-0.4% post dHST and 0.4+/-0.3% post eHST. Plasma volume was decreased 7.5+/-4.6% and 5.7+/-4.4%, 60 and 120 min post dHST, respectively. A small (1.6 mEq x L[-1]) but significant increase was found for serum Na+ concentration 60 min post dHST but had returned to predehydration level 120 min post dHST. Serum K+ and myoglobin concentrations were not affected by HSTs. Peak torque was not different (P > 0.05) among control, dHST, and eHST for the knee extensors (Mean (Nm)+/-SD, 285+/-79, 311+/-113, and 297+/-79) and elbow flexors (79+/-12, 83+/-15, and 80+/-12). Time to fatigue was not different (P > 0.05) among control, dHST and eHST for the knee extensors (Mean (s)+/-SD. 42.4+/-11.5, 45.3+/-7.6, and 41.8+/-6.0) and elbow flexors (48.2+/-8.9, 44.0+/-9.4, and 46.0+/-6.4). These results provide evidence that isometric strength and endurance are unaffected 3.5 h after dehydration of approximately 4% body mass.     

The effect of increased weight on peak pressures: implications for obesity and diabetic foot pathology

The purpose of this study was to determine if increased weight contributes to increased mean peak plantar foot pressures when foot function, deformity, and structure are controlled. Ten male and nine female volunteers without sensory neuropathy or other systemic disease were evaluated in the study. Using a repeated measures design, peak plantar foot pressures were compared using the Novel Pedar in-shoe pressure measurement system under three conditions. Baseline measurements were made while volunteers wore the standard test footwear, a thin-soled rubber oxford sneaker. The second and third test conditions involved pressure measurements with an additional 9.1 kg (20 lb) and 18.2 kg (40 lb), respectively, of weight evenly distributed in pockets on the front and back of a workout vest. There was a significant increase in mean peak plantar foot pressures under the metatarsal heads, heel, and midfoot for each incremental increase of weight (baseline vs. 9.1 kg, p < .05; 9.1 kg vs. 18.2 kg, p < .05). The authors conclude that increases in weight increased plantar foot pressures for the first metatarsal, lesser metatarsal, midfoot, and heel regions in both men and women.     

A model for the interaction of trifluoroethanol with peptides and proteins

Scaphoid or longitudinal arch pads are frequently prescribed pedorthics for foot and ankle rehabilitation. These pedorthics are reported to be effective in mechanically supporting the medial longitudinal arch while reducing plantar and medial soft tissue strain. The objective of this study was to measure alterations in ambulatory plantar pressure metrics in a group of adults secondary to scaphoid pad application. The biomechanical rationale of this study was that the geometry of foot contact would be altered secondary to foot inversion. Ten adult male subjects with biomechanically normal feet were evaluated during multiple trials. A Holter type microprocessor-based portable in-shoe plantar pressure data acquisition system was used to record the dynamic data. Pressures were recorded from eight discrete plantar locations at the hindfoot, midfoot, and forefoot regions of the insole. Statistically significant (p < or = 0.05) increases in peak pressures were seen laterally with scaphoid pad application, while significant decreases in peak pressures with pad usage occurred at the hallux and the calcaneal region of the foot. At the medial longitudinal arch, peak pressures increased from near 0 to 115.3 kPa, contact durations increased from near 0 to 438 ms, and pressure-time integrals increased from near 0 to 33.4 kPa.s.     

Palliative surgery in malignant obstructive jaundice: prognostic indicators of early mortality

The purpose of this study was to examine the effect of strapping on different components of motor performance of wrist and ankle joints. The subjects were 14 healthy volunteers (12 females, two males), aged 21-33 years, with no known previous injuries of the ankle and wrist joints. The measurements were made with the HPM/BEP system and Isokinetic Lido Active Multi-joint system. First, the subjects performed the test without strapping and then, on the following day, with strapped right wrist and ankle joints. The strapping of the wrist increased the simple reaction time by 9%, choice reaction time by 9% and decreased the wrist tapping speed by 21%. Wrist strength decreased in flexion (180 degrees/s) by 14% and ulnar deviation (180 degrees/s) by 8%. The strapping of the ankle increased the simple reaction time by 12%, choice reaction time by 9% and decreased foot tapping speed by 14%. Ankle strength in plantar flexion decreased in 60 degrees/s by 22% and 180 degrees/s by 14% and in inversion in 60 degrees/s by 28% and 180 degrees/s by 15%. These results suggest the strapping of ankle and wrist joints reduces motor performance in the above-mentioned directions as measured by the following parameters: simple reaction time, choice reaction time, tapping speed, and muscle strength.     

Reliability of F-scan in-shoe measurements of plantar pressure

Research by our group and others indicates that many amputations of the lower limb occur after foot ulceration in patients with diabetes. It has been proposed that diabetic foot ulcers are mainly caused by repetitive trauma in areas of high plantar pressure during walking. Recent technology permits in-shoe measurement of plantar pressure. We assessed the reliability of the F-Scan in-shoe system for measurement of plantar pressure (Tekscan Inc., Boston, MA) in 51 subjects from a cohort of 977 diabetic veterans enrolled in a prospective study of risk factors for foot ulceration and amputation (the Seattle Diabetic Foot Study). Subjects were tested twice, wearing their own shoes. We used the coefficient of variation (CV) and the intra-class correlation coefficient (ICC) to estimate the reliability of F-Scan measurements of pressure. Peak pressure over the metatarsal heads proved to have the best indices of reliability, with CVs of 0.150 and 0.155, and ICCs of 0.755 and 0.751. Coefficients of variation for the heel, whole foot, and hallux ranged from 0.148 to 0.240, with ICCs ranging from 0.493 to 0.832. By published standards, peak pressures over the metatarsal heads and right hallux met the criteria for excellent reliability. Our ICCs for high pressures under the foot, heel, metatarsal heads, and hallux, and for peak pressures under the heel and left hallux represented fair-to-good reliability. No F-Scan plantar measurements could be judged by these criteria as having poor reliability. This clinical study found that for elderly patients with diabetes who were wearing their own shoes and were tested on two different days with different insoles, the F-Scan insole system was generally reliable for measurements of high pressure and peak pressure.     

The association between callus formation, high pressures and neuropathy in diabetic foot ulceration

The presence of an ulcer beneath callus on the diabetic foot has been a well-documented and common clinical finding. We have conducted a prospective study to examine whether callus can be used to predict plantar intrinsic neuropathic diabetic foot ulcer formation. Sixty-three diabetic patients (43 male, 25 Type 1), median age 62 years (IQ range 52, 67), median diabetes duration 17 years (IQ range 8,25) participated in the study. All had neuropathy and peak plantar foot pressures (measured using a dynamic optical pedobarograph) > or = 10 kg cm-2. Calluses and previous ulcers were documented and classified. All ulcers occurring prior to and during the study were recorded, re-examination was 15.4 (range 10-22) months from baseline. Seven ulcers (6 patients) occurred during the study. Pressures were higher in the ulcer than non-ulcer sub-group (p = 0.04) with a relative risk of developing an ulcer of 4.7 for an area of elevated plantar pressure. This compares with a relative risk of 11.0 for an ulcer developing under an area of callus, and a relative risk of 56.8 for an ulcer developing on a site of previous ulceration. This study confirms that a history of previous ulceration is the highest risk factor for ulceration and demonstrates, for the first time, that the presence of plantar callus is highly predictive of subsequent ulceration. Careful history taking and examination of the foot to detect the presence of callus require no special training or equipment and callus should be recognized as a 'high risk' factor for foot ulceration.     

Running shoes for relief of plantar pressure in diabetic patients

There is a causal relationship between diabetic foot ulceration, elevated plantar pressure, and severe sensory neuropathy. Cushioned footwear intended to relieve plantar pressure is well established for prevention and healing of plantar ulcers. The aim of the present study was to investigate whether pressure relief by means of a running shoe with optimized forefoot pressure damping is comparable to that of a custom-made soft insole placed into an in-depth shoe. The in-shoe pressures were compared to an in-depth shoe with the original cork insole and with a leather-soled Oxford shoe. The maximum reduction of plantar pressure in the running shoe was 47% under the 2nd and 3rd metatarsal heads, 29% at the first metatarsal head, and 32% at the great toe in comparison to the Oxford shoe. This was surpassed only by the custom-made insole, which reduced pressures at the metatarsal heads by 50%. The specially designed running shoe yielded the same pressure relief at the central metatarsal heads as the custom-made insole. Such shoes are likely to be very useful in preventing diabetic foot ulceration in high-risk patients as a comparatively affordable and immediately available device.     

Healing times of diabetic ulcers in the presence of fixed deformities of the foot using total contact casting

In a diabetic foot, ulcers can lead directly to the loss of a limb, and they may be life threatening if the patient is not provided effective intervention directed at healing. This study reports on the healing times of diabetic neuropathic plantar ulcers in the presence of fixed deformities of the foot using the ambulatory method of total contact casting (TCC). In this study, 21 subjects with chronic diabetes mellitus, plantar ulcers, and fixed deformities of the foot were put in casts, and their progress was followed until the ulcers were completely healed. Results indicated that all of the ulcers healed. The average time to healing was 67 +/- 29 days. Ulcers located in the forefoot, midfoot, and rearfoot healed in an average of 35 +/- 12 days, 73 +/- 28 days, and 90 +/- 12 days, respectively. The location of the ulcer and the presence and location of a fixed deformity of the foot strongly correlated with and was predictive of healing time using TCC. The location of the ulcers and the location of the fixed deformities of the foot should always be considered by providers of rehabilitation who treat diabetic neuropathic foot ulcers using TCC.     

Detection of Toxoplasma gondii-specific antibodies in dogs. A comparative study of immunoenzymatic, immunofluorescent and haemagglutination titers

A surgical technique using an advancement plantar skin flap to maintain the resection gap closure when performing central ray resections is described and illustrated. The concept, applicable to central polydactyly or polysyndactyly of the foot, was developed with goals of providing a skin tether to maintain a normally narrow foot as well as to improve the appearance of the surgical scar.     

H-reflex and F-wave potentials in leg and arm muscles

The systematic analyses of secondary muscle potentials of H-reflex and F-wave type were done in multicentric study. The examinations were carried out in healthy volunteers with 9 muscles analysed on the legs and 9 on the lower arms and hands. The H-reflex potential was found regularly in thigh muscles (vastus medialis 100%, biceps femoris 97%, semitendinosus 93%). Less frequently but still with high incidence it appeared in posterior lower leg muscles (soleus 93%, caput mediale gastrocnemii 73%). In anterior tibial muscle and extensor digitorum brevis it did not appear at all. Only exceptionally it was found in short peroneal muscle (3%) and occasionally, only on proximal nerve stimulation, in flexor hallucis brevis. The similar distribution pattern was found in lower arm and hand muscles with analysis on both sides. In flexor digitorum superficialis (73-70%) and flexor carpi radialis (73-57%) the percentage of H-potential muscles was the highest, in flexor carpi ulnaris (47-40%) lesser but still remarkable. Brachioradialis (37-30%) and extensor digitorum communis (27-27%) percentage decreased further. The even more distal, pronator quadratus (21-20%) and abuctor digiti minimi (17-17%) presented as muscles with low incidence of H-reflex positivity. In extensor indicis proprius (3%) the lowest H-potential incidence was found and in opponens pollicis no H-potential at all. F-waves if evaluated as "F-frequency" follow the similar distribution pattern. The lowest "F-frequency" was found on the legs in anterior tibial, short peroneal and extensor digitorum brevis muscles. In the last one more than one half of stimuli failed to evoke the F-potential. Those are the muscles in which H-potentials almost never appeared. The highest "F-frequency" was recorded in thigh, posterior lower leg muscle and flexor hallucis brevis. Some of the examinees displayed in almost all examined muscles H-potential (6 of 30), the others (9 of 30) had it in neither one or in a single muscle. It looks like as if a kind of H-reflex or F-wave individuals exist. If the H- or F-potentials distribution pattern got projected on the homunculus in quadrupedal position the following idea appears. The thigh muscles, the plantar flexors of the feet and hand and finger flexors are first of all tonic muscles mostly involved in standing or holding. The extensors of the foot/toes, respectively of hand/fingers interrupt phasically the sustained action of standing by lifting the foot/hand from the ground. The muscles with mostly tonic function produce much H-reflexes, transitional forms or at least F-wave with high "F-frequency". Is that a kind of phylogenetical remnants, better developed in the motorically less differentiated legs? Have the H-reflex muscles if compared with F-wave muscles different motor units structure? Have they different motoneurons, with different liability to produce recurrent discharges?     

Tendon transfer for equinovarus deformed foot caused by cerebrovascular disease

Surgical correction was performed on 125 patients who had equinovarus deformity caused by a cerebrovascular accident and who needed an ankle foot orthosis for walking. The operative procedures involved anterior transfer of the long toe flexors (flexor hallux longus and flexor digitorum longus; long toe flexor group) or lateral transfer of the anterior tibial tendon (anterior tibial tendon group), combined with lengthening of the Achilles tendon. On evaluation more than 2 years after surgery, 83 of 110 patients of the long toe flexor group and eight of 15 patients of the anterior tibial tendon group were able to walk without a brace. Five patients of the anterior tibial tendon group who had shown strong contraction of the anterior tibial muscle during the swing phase before surgery, needed a brace because of a drop foot after surgery. Thus, lateral transfer of the anterior tibial tendon was abandoned in 1984. Recurrence of varus deformity was seen in approximately 15% of the patients in both groups. Anterior transfer of the long toe flexors, using them as dorsiflexor tendons or for tenodesis, seemed to produce better results.     

Functional analysis of patients who have had a modified Van Nes rotationplasty

Electromyographic analysis of gait in eight patients who had had a modified Van Nes rotationplasty was performed to compare the activity of the flexors and extensors of the ankle on the side of the operation with that of the flexors and extensors of the knee on the normal, contralateral side. The resemblance in the activity of the extensors was more pronounced than that of the flexors. In three patients, the angle of flexion of the knee throughout the gait cycle was the same on the side of the rotationplasty as on the normal side. There was more symmetry in the swing phase than has been reported for patients who have had an above-the-knee amputation. The strength of the dorsiflexors of the ankle on the side of the rotationplasty was 68 percent and that of the flexors was 71 per cent when compared with that of the muscles of the normal ankle.     

A comparison of weightbearing pressures in various postoperative devices

Currently, there are a multitude of computerized gait analysis systems to evaluate weightbearing patterns in the foot. The following study utilizes the F-Scan System of foot pressure analysis. This system was applied to evaluate plantar pressures as they occur in various postoperative shoe gear and to determine which devices are most clinically beneficial in ambulatory surgery. A pressure sensor recorded plantar pressures in 20 feet wearing various types of postoperative shoe wear. Initially, a stockinette was used to simulate barefoot pressure, followed by a wooden postoperative shoe, a Darco postoperative shoe, a Darco closed postoperative shoe, a Darco "softie," a Darco wedge, an Equalizer Premium Walker, an Equalizer Low Top Walker, and an Aircast. The results demonstrated that the Equalizer Premium Walker was most efficient in reducing forefoot pressures, while the postoperative surgical shoes had variable results, noticeably with several increases in pressure being recorded.     

Resistance exercise prevents plantar flexor deconditioning during bed rest

Because resistance exercise (REX) and unloading induce opposing neuromuscular adaptations, we tested the efficacy of REX against the effects of 14 d of bed rest unloading (BRU) on the plantar flexor muscle group. Sixteen men were randomly assigned to no exercise (NOE, N = 8) or REX (N = 8). REX performed 5 sets x 6-10 repetitions to failure of constant resistance concentric/eccentric plantar flexion every other day during BRU. One-repetition maximum (1RM) strength was tested on the training device. The angle-specific torque-velocity relationship across 5 velocities (0, 0.52, 1.05, 1.75, and 2.97 rad.s-1) and the full range-of-motion power-velocity relationship were assessed on a dynamometer. Torque-position analyses identified strength changes at shortened, neutral, and stretched muscle lengths. Concentric and eccentric contractile work were measured across ten repetitions at 1.05 rad.s-1. Maximal neural activation was measured by surface electromyography (EMG). 1RM decreased 9% in NOE and improved 11% in REX (P < 0.05). Concentric (0.52 and 1.05 rad.s-1), eccentric (0.52 and 2.97 rad.s-1), and isometric angle-specific torques decreased (P < 0.05) in NOE, averaging 18%, 17%, and 13%, respectively. Power dropped (P < 0.05) in NOE at three eccentric (21%) and two concentric (14%) velocities. REX protected angle-specific torque and average power at all velocities. Concentric and eccentric strength decreased at stretched (16%) and neutral (17%) muscle lengths (P < 0.05) in NOE while REX maintained or improved strength at all joint positions. Concentric (15%) and eccentric (11%) contractile work fell in NOE (P < 0.05) but not in REX. Maximal plantar flexor EMG did not change in either group. In summary, constant resistance concentric/eccentric REX completely prevented plantar flexor performance deconditioning induced by BRU. The reported benefits of REX should prove useful in prescribing exercise for astronauts in microgravity and for patients susceptible to functional decline during bed- or chair-bound hospital stays.     

Biomechanics of the foot in diabetes mellitus. Some theoretical considerations

Although diabetes mellitus is a biochemical disease, it has biomechanical consequences for the lower extremity. Numerous alterations occur in the function of the foot and lower extremity in people with diabetes. This article evaluates biomechanical alterations of the foot in the presence of neuropathy in patients with diabetes in the context of several theoretical concepts. Further study of these hypotheses will result in a better understanding of how diabetes causes elevated plantar pressures and the potential of strategies to prevent these changes so that the burden of diabetic foot disease can be reduced.