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PubMed1996

The relationship between arm-span measurement and height with special reference to gender and ethnicity.

OBJECTIVE: The relationship between height and arm-span measurement in both sexes and different ethnic groups was studied in order to assess the use of the arm-span measurement as a suitable proxy indicator for height. SETTING: School of Biological and Molecular Sciences, Oxford Brookes University. SUBJECTS: Five hundred and fifty-three subjects (272 male and 281 female) aged 23.3 years (s.d. 5.5). RESULTS: Correlation coefficients (r = 0.73-0.89) indicated a clear association between arm-span measurements and height in all groups. However, arm-span was found to be significantly different (P < 0.01) from height in two ethnic groups, the Afro-Caribbean's of both sexes and Asian males. This suggests that arm-span measurements may be an inappropriate proxy for height in certain populations. CONCLUSION: The arm-span measurement and height relationship is significantly different in Afro-Caribbean and Asian males. This suggests that any future studies attempting to use arm-span measurement as a proxy for height must consider these ethnic differences.

Adult↗
PubMed1998

The design of arm pressure covers to alleviate pain in high G maneuvers.

HYPOTHESIS: Arm pain has been noted especially when increased coverage anti-G suits are worn in combination with PBG (pressure breathing during G) in high G centrifuge test runs. Arm pain has forced the termination of test runs and has the potential to cause a serious decrement in a pilot's ability to function effectively during high-G flight. Based on the theory that arm pain is caused by fluid pooling in the arm, four new pressure cover systems for the arm were designed and tested. METHODS: Seven test subjects wore each design in a series of runs in a dynamic flight simulator (DFS). Subjects experienced both gradual and rapid onset rate runs with G levels ranging from +3.0 G to +9.0 G. Data were collected on the maximum G's achieved, pain location, and pain intensity. Subjective responses on the comfort and function of each design and overall arm cover design preferences were also obtained via a questionnaire. RESULTS: Analysis of the DFS data, using a two-factor ANOVA (subjects, designs), revealed that each of the new designs provided significantly better protection from arm pain than the control condition (no protection) and that each of the designs significantly improved the maximum G level attained during rapid onset acceleration in the range of +1 G. CONCLUSION: No positive correlation was found between subject ranking of the four new design concepts at the conclusion of the study in terms of the pain reduction they provided and the pain levels reported during DFS testing.

Adult↗
PubMed1999

Assessment of inner dynein arm structure and possible function in ciliary and flagellar axonemes.

The construction and assessment of a three-dimensional computer-generated model of inner dynein arms on a 96-nm repeat unit of an axonemal doublet is described. The model is based on published electron micrographs of axonemes from Tetrahymena cilia and eel sperm, which were prepared using several different techniques: negative stain, freeze etch, and thin section. The inner arm structure is represented as three inner dynein arm complexes containing four inner dynein arms (IDAs), three dyads, and one single-headed arm, each capable of bridging the interdoublet gap. The IDA structures in the model have been correlated with the domains containing dynein heavy-chain isoforms mapped by several authors using genetic analyses of Chlamydomonas mutants. The model is consistent with micrographic evidence from axonemes of cilia and flagella from other organisms that led previously to conflicting structural interpretations. In this reconciling interpretation, the different alignments of the IDAs relative to the corresponding outer dynein arms observed in micrographs of differently prepared samples, result from the IDAs being arrested at different stages of their cycles of activity in each preparation. By interpolating between these positions of arrest, cycles of activity are proposed for each of the IDAs during which the arms attach to the neighbouring doublet microtubule and drive it tipwards.

Animals↗
PubMed1998

The reactivation of demembranated human spermatozoa lacking outer dynein arms is independent of pH.

The effect of pH, Mg-ATP, and free calcium on activity of the inner dynein arm was investigated using demembranated human spermatozoa lacking the outer dynein arms (LODA). The results were compared with those obtained for demembranated-reactivated normal spermatozoa to evaluate the functional properties of the inner and outer dynein arms in axonemal motility. The reactivation of Triton X-100-demembranated LODA spermatozoa was analysed at various pHs and concentrations of Mg-ATP and calcium using video recordings. The percentage of reactivated LODA spermatozoa as a function of Mg-ATP concentration was not dependent on pH, whereas reactivation of normal human spermatozoa is pH dependent. This suggests that there may be a pH-dependent regulatory mechanism associated with the outer dynein arms. A delay in the principal bend propagation of normal and LODA reactivated cells was found at pH 7.1. This disappeared at pH 7.8 in normal but not in LODA populations. This suggests a role for outer dynein arms in the initiation of the propagation of flagellar bends at alkaline pH. The level of LODA and normal sperm reactivation both depended on the calcium concentration in the medium. At lower free calcium concentrations, the reactivation level and beat frequency of reactivated cells were higher. Our results suggest a functional difference between outer and inner dynein arms of human spermatozoa based on a differential pH sensitivity. Moreover, calcium seems to exert its regulatory action elsewhere than on the outer dynein arms.

Adenosine Triphosphate↗
PubMed2000

Accuracy of muscle moment arms estimated from MRI-based musculoskeletal models of the lower extremity.

OBJECTIVE: Biomechanical models that compute the lengths and moment arms of soft tissues are broadly applicable to the treatment of movement abnormalities and the planning of orthopaedic surgical procedures. The goals of this study were to: (i) develop methods to construct subject-specific biomechanical models from magnetic resonance (MR) images, (ii) create models of three lower-extremity cadaveric specimens, and (iii) quantify the accuracy of muscle-tendon lengths and moment arms estimated using these models. MATERIALS AND METHODS: Models describing the paths of the medial hamstrings and psoas muscles for a wide range of body positions were developed from MR images in one joint configuration by defining kinematic models of the hip and knee, and by specifying "wrapping surfaces" that simulate interactions between the muscles and underlying structures. Our methods for constructing these models were evaluated by comparing hip and knee flexion moment arms estimated from models of three specimens to the moment arms determined experimentally on the same specimens. Because a muscle's moment arm determines its change in length with joint rotation, these comparisons also tested the accuracy with which the models could estimate muscle-tendon lengths over a range of hip and knee motions. RESULTS: Errors in the moment arms calculated with the models, averaged over functional ranges of hip and knee flexion, were less than 4 mm (within 10% of experimental values). CONCLUSION: The combination of MR imaging and graphics-based musculoskeletal modeling provides an accurate and efficient means of estimating muscle-tendon lengths and moment arms in vivo.

Biomechanical Phenomena↗
PubMed1981

The mechanochemical cycle of the dynein arm.

A dynein arm attachment cycle produces sliding between adjacent doublet microtubules (N and N + 1) of cilia. In intact axonemes, in the absence of ATP, almost all arms appear attached at both ends (rigor). When ATP is added, most arms detach from doublet N + 1. In ATP and vanadate, the arms do not return to rigor, suggesting that ATP hydrolysis is required for re-extension and reattachment of the dynein arm, but not for detachment. Using solutions containing dynein to decorate dynein-less axonemal doublets, we confirm this interpretation. In the absence of ATP, both sides of each doublet decorate with arms. Addition of ATP, ATP and vanadate or AMP-PNP causes immediate arm detachment, but only in the first instance, where extensive ATP hydrolysis can occur, does decoration eventually reappear. Dynein decorates heterologous axonemal doublets and brain microtubules, as well as homologous doublets, suggesting that this mechanochemical cycle may have general applicability in microtubule-based cell motility.

Adenosine Triphosphatases↗
PubMed1978

Regenerative ability of double-half and half upper arms in the newt, Notophthalmus viridescens.

The upper arms of adult newts (Notophthalmus viridescens) were surgically manipulated to create double-half dorsal, double-half ventral, double-half anterior, and double-half posterior upper arms, and longitudinal half-dorsal, half-ventral, half-anterior, and half-posterior upper arms. Amputation through the double-half upper arms usually failed to elicit normal distal regeneration, despite the fact that an apparently normal regeneration blastema was initially formed. Instead, regeneration in these cases was limited to the formation of a variable number of small cartilage elements. On the basis of these results it is concluded that a complete limb circumference is required for distal transformation in newts, in addition to the well-established requirements for a wound epidermis, adequate innervation and dedifferentiation leading to blastema formation. A model for the sequential generation of new parts of the limb pattern during distal transformation from a complete circumference is presented. This model can also account for the occurrence of normal early stages of regeneration in double-half upper arms. Half upper arms which were amputated immediately were shown to develop single, complete regenerates. If amputation of half upper arms was delayed three or more weeks to permit complete wound healing, a supernumerary limb from the lateral wound surface sometimes developed in addition to a complete, single limb from the distal amputation surface.

Amputation, Surgical↗
PubMed2006

Variation in external rotation moment arms among subregions of supraspinatus, infraspinatus, and teres minor muscles.

A rotator cuff tear causes morphologic changes in rotator cuff muscles and tendons and reduced shoulder strength. The mechanisms by which these changes affect joint strength are not understood. This study's purpose was to empirically determine rotation moment arms for subregions of supraspinatus, infraspinatus, and for teres minor, and to test the hypothesis that subregions of the cuff tendons increase their effective moment arms through connections to other subregions. Tendon excursions were measured for full ranges of rotation on 10 independent glenohumeral specimens with the humerus abducted in the scapular plane at 10 and 60 degrees . Supraspinatus and infraspinatus tendons were divided into equal width subregions. Two conditions were tested: tendon divided to the musculotendinous junction, and tendon divided to the insertion on the humerus. Moment arms were determined from tendon excursion via the principle of virtual work. Moment arms for the infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly greater when the tendon was only divided to the musculotendinous junction versus division to the humeral head. Moment arms across subregions of infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly different. A difference in teres minor moment arm was not found for the two cuff tendon conditions. Moment arm differences between muscle subregions and for tendon division conditions have clinical implications. Interaction between cuff regions could explain why some subjects retain strength after a small cuff tear. This finding helps explain why a partial cuff repair may be beneficial when a complete repair is not possible. Data presented here can help differentiate between cuff tear cases that would benefit from cuff repair and cases for which cuff repair might not be as favorable.

Biomechanical Phenomena↗
PubMed1997

Combined lesions of perirhinal and entorhinal cortex impair rats' performance in two versions of the spatially guided radial-arm maze.

The present study examined the effects of combined lesions of the entorhinal and perirhinal cortex (PRER) on performance of two versions of the spatially guided eigh-tarm radial maze. In the first version, all arms were baited and in each session the rats were allowed to explore the maze freely until they retrieved all of the reinforcers. PRER subjects were profoundly impaired in performance of this task, making fewer correct choices and more total errors than control subjects. In the second task, a delayed nonmatching to sample version of the radial-arm maze, each daily session was separated into two phases. In the first, predelay phase, four arms were open and the remaining four arms were blocked with clear Plexiglas barriers; subjects were permitted to visit each of the four arms and retrieve the reinforcers. In the second, postdelay phase, the subject was placed on the maze with free access to all eight of the arms, but only those arms that were blocked in the predelay phase contained reinforcers. Delays of either 10 min or 30 s separated the pre- and postdelay phases. PRER subjects were significantly impaired in their performance of this task at both delays, making fewer correct choices and more errors than controls; the magnitude of this deficit was not dependent on length of delay. These data suggest that, along with the hippocampal formation, the entorhinal and perirhinal cortices actively participate in the acquisition and performance of appetitively motivated spatial memory tasks.

Analysis of Variance↗
PubMed1993

Role of the cerebellum in visuomotor coordination. I. Delayed eye and arm initiation in patients with mild cerebellar ataxia.

The initiation of coupled eye and arm movements was studied in six patients with mild cerebellar dysfunction and in six age-matched control subjects. The experimental paradigm consisted of 40 deg step-tracking elbow movements made under different feedback conditions. During tracking with the eyes only, saccadic latencies in patients were within normal limits. When patients were required to make coordinated eye and arm movements, however, eye movement onset was significantly delayed. In addition, removal of visual information about arm versus target position had a pronounced differential effect on movement latencies. When the target was extinguished for 3 s immediately following a step change in target position, both eye and arm onset times were further prolonged compared to movements made to continuously visible targets. When visual information concerning arm position was removed, onset times were reduced. Eye and arm latencies in control subjects were unaffected by changes in visual feedback. The results of this study clearly demonstrate that, in contrast to earlier reports of normal saccadic latencies associated with cerebellar dysfunction, initiation of both eye and arm movements is prolonged during coordinated visuomotor tracking thus supporting a coordinative role for the cerebellum during oculo-manual tracking tasks.

Adult↗
PubMedDate not supplied

Feasibility of C-arm-supported CT fluoroscopy in percutaneous abscess drainage procedures.

PURPOSE: Evaluation of C-arm-supported CT fluoroscopy to facilitate percutaneous abscess drainage procedures. METHODS: Prospectively, 40 percutaneous drainage procedures were performed either with C-arm-supported CT fluoroscopy or with CT fluoroscopy alone. Hybrid imaging was performed on the CT couch after complementing a CT fluoroscopy scanner with a C-arm fluoroscopy unit. Procedure times, drainage revisions during follow-up, and postinterventional drainage periods were analyzed. RESULTS: When compared with exclusive CT fluoroscopic guidance, a median procedure time of 9 +/- 3.7 min versus 14.8 +/- 7.3 min was required for C-arm-supported CT fluoroscopy (p < 0.005, t-test). During follow-up, eight drainage catheters had to be revised within the exclusive CT fluoroscopy group, while only two revisions were necessary within the C-arm-supported CT fluoroscopy group. With C-arm-supported CT fluoroscopy, postinterventional drainage periods were reduced (median 13 vs 19 days; p < 0.001, t-test). CONCLUSION: Compared with exclusive cross-sectional image guidance, C-arm-supported CT fluoroscopy seems to improve placement of abscess drainage catheters to possibly reduce procedure times, drainage catheter revisions, and postinterventional drainage periods.

Abscess↗
PubMed1994

Comparison of thallium-201 single-photon emission computed tomographic scintigraphy with intravenous dipyridamole and arm exercise.

In patients who cannot perform treadmill exercise, both intravenous dipyridamole and arm exercise have been used with thallium-201 scintigraphy to detect significant coronary artery disease. However, no study has directly evaluated the results of intravenous dipyridamole and arm exercise thallium scintigraphy as compared with coronary angiography. It was the purpose of this study to compare intravenous dipyridamole and arm exercise thallium-201 single-photon emission computed tomographic (SPECT) scintigraphy for detection of significant coronary artery disease in patients who could not perform treadmill exercise. Data are presented for both intravenous dipyridamole and arm exercise thallium-201 SPECT scintigraphy in 18 men who could not perform treadmill exercise, and results are compared with those of coronary angiography. Ten of 11 (91%) patients with significant coronary artery disease were identified correctly, and the results of intravenous dipyridamole and arm exercise thallium scintigraphy were comparable. In patients without significant coronary artery disease, intravenous dipyridamole thallium images were interpreted correctly. However, initial arm exercise thallium images demonstrated a fixed inferior wall defect in two of seven patients without significant coronary artery disease. Images in one of these patients could not be retrieved from tape for further analysis. Review of the images in the other patient demonstrated relatively high background radioactivity, and when the images were displayed without background subtraction, the inferior wall was correctly interpreted as normal. We conclude that results of intravenous dipyridamole and arm exercise thallium-201 SPECT scintigraphy are comparable.

Coronary Angiography↗
PubMed1993

Spatial memory and stereotypic behaviour of animals in radial arm mazes.

The symmetric radial arm maze, described by Olton in 1976, has developed into an important tool for the study of spatial memory. In a typical test an animal is placed in the centre of the maze, which contains some small piece of food at the end of each arm. The sampling behaviour of the animal is then recorded. In such studies the score (number of choices of arms which still contain food) of the animal is normally compared with the score of an imaginary animal which changes arms entirely at random. In a new method of analysis the non-random score of the animal is split into two parts, one depending on memory and one on stereotypic choice behaviour. Even mild departures from randomness are shown to alter considerably the expected 'random' score in an eight-armed maze. The part of the score claimed to depend on memory was shown to increase when the animals learn to search the maze, the stereotypic part did not. The general effect from stereotypic choice behaviour is shown to result, in most animals, in an increase in the total score. In an eight-armed maze this increase may amount to more than 20% of the total non-random score, even in a well-trained animal. The effect is less pronounced in mazes with 16 arms. It has been proposed that hippocampal lesions produce a stereotypic behaviour. We propose, based on our analysis, that the stereotypic behaviour is not produced but revealed by hippocampal lesions which destroy almost completely the memory-guided behaviour masking the stereotypic behaviour in the intact animal.

Animals↗
PubMed1995

Variation of muscle moment arms with elbow and forearm position.

We hypothesized that the moment arms of muscles crossing the elbow vary substantially with forearm and elbow position and that these variations could be represented using a three-dimensional computer model. Flexion/extension and pronation/supination moment arms of the brachioradialis, biceps, brachialis, pronator teres, and triceps were calculated from measurements of tendon displacement and joint angle in two anatomic specimens and were estimated using a computer model of the elbow joint. The anatomical measurements revealed that the flexion/extension moment arms varied by at least 30% over a 95 degrees range of motion. The changes in flexion/extension moment arm magnitudes with elbow flexion angle were represented well by the computer model. The anatomical studies and the computer model demonstrate that the biceps flexion moment arm peaks in a more extended elbow position and has a larger peak when the forearm is supinated. Also, the peak biceps supination moment arm decreases as the elbow is extended. These results emphasize the need to account for the variation of muscle moment arms with elbow flexion and forearm position.

Biomechanical Phenomena↗
PubMed1977

Dicentric yields induced by gamma-radiation and chromosome arm number in primates.

To evaluate the effect of the chromosome arm number on the yield of dicentric chromosomes, frequencies of gamma-ray-induced chromosome aberrations were examined with peripheral lymphocytes from three different primate species, Saimiri sciureus (arm number, 77), Macaca fascicularis (arm number, 83) and Nycticebus coucang (arm number, 99). Irradiated blood samples were cultured by the same standard technique as that commonly used for human lymphocytes. The yields of dicentrics and dicentrics plus rings at doses of 100, 200 and 300 rad of gamma-irradiation were not significantly different among the three species, in spite of the difference in the chromosome arm number. Furthermore, dose-response relationships for these species were consistent with that for man. Statistical analysis indicated that the expected dicentric yields calculated from the arm number model were significantly different from the observed yields at 200 and 300 rad doses (P less than 0.01). From these results it can be pointed out that there is no correlation between the yield of dicentrics and the effective chromosome arm number, and that the chromosomal radiosensitivity of these primates is essentially the same as that of man, at least in the lymphocyte system.

Animals↗
PubMed1980

Effects of scopolamine, pentobarbital, and amphetamine on radial arm maze performance in the rat.

Rats were trained to obtain food pellets from the end of each arm of an eight-arm radial maze. Baseline performance was characterized by very few entries into arms from which the food pellet had already been obtained. In Experiment 1, neither d-amphetamine (0.1-3.0 mg/kg) nor pentobarbital (1.0-10.0 mg/kg) affected choice accuracy, although the rate of arm-entry increased after d-amphetamine and decreased after pentobarbital. Scopolamine (0.1-1.0 mg/kg), on the other hand, reduced both accuracy and the rate of arm entry. In a second experiment, the effects of scopoalmine were replicated using a between-subjects design. Methylscopolamine (0.17, 1.0 mg/kg) was found to have little effect on performance. Multiple response criteria were also compared in the second experiment. Scopolamine was found to affect runs farther out the arm differently than it affected abbreviated arm entrances. A post-trial feeding test was also included to evaluate changes in reinforcer effectiveness, and showed that food continued to be a reinforcer after both scopolamine and methylscopolamine.

Animals↗
PubMed1982

The limited fragmentation of porcine haemolytic immunoglobulin M. Evidence that haemolytic activity depends on the number of Fab arms that can attach to the erythrocyte surface.

Methods previously developed in this laboratory for the proteolytic removal of limited numbers of Fab arms from the IgM molecule have been used to study haemolytic activity. The gradual removal of arms produced a rapid decrease in complement-mediated lysis of erythrocytes but had a much slower effect on their agglutination. Therefore a stage was reached at which molecules with four Fab arms gave good agglutination but did not cause cell lysis. The same result was obtained whether Fab arms were removed randomly by pepsin or in pairs by trypsin. Hence the non-lytic nature of these molecules was independent of the arrangement of their remaining Fab arms. A sharp decrease in haemolytic activity was also obtained under conditions of high antibody concentration when the IgM molecular could attach only a few of its Fab arms to the erythrocyte surface. Possible explanations for the dependence of haemolytic activity on the number of Fab arms discussed.

Animals↗
PubMed2005

Different rankings of inbred mouse strains on the Morris maze and a refined 4-arm water escape task.

The submerged platform or Morris water escape task is widely used to study genetic variation in spatial learning and memory, but interpretation is sometimes difficult because of wall hugging, jumping off the platform, floating or non-spatial swim strategies. We modified the task by introducing four wide arms into the circular tank and adding features that reduced, eliminated, or compensated for several competing behaviors. Three versions of the 4-arm task were evaluated in detail, and the third version yielded good results for six of eight inbred strains. Furthermore, the 4-arm task could be scored adequately without computerized video tracking. Although performance on the 4-arm task was generally superior to the Morris maze, the extent of the improvement was strain dependent. Two strains with retinal degeneration (C3H/HeJ, FVB/NJ) performed poorly on both the Morris and 4-arm mazes, whereas C57BL/6J and DBA/2J did well on both mazes. A/J performed poorly on the Morris task but became very proficient on the 4-arm maze, despite its strong tendency to hug the walls of the tank. The BALB/cByJ strain, on the other hand, exhibited the best probe trial performance on the Morris maze but was very slow in acquiring the 4-arm task. We conclude that no single task can reveal the full richness of spatially guided behavior in a wide range of mouse genotypes.

Analysis of Variance↗