The Neanderthal lower arm

Neanderthal forearms have been described as being very powerful. Different individual features in the lower arm bones have been described to distinguish Neanderthals from modern humans. In this study, the overall morphology of the radius and ulna is considered, and morphological differences among Neanderthals, Upper Paleolithic Homo sapiens and recent H. sapiens are described.Comparisons among populations were made using a combination of 3D geometric morphometrics and standard multivariate methods. Comparative material included all available complete radii and ulnae from Neanderthals, early H. sapiens and archaeological and recent human populations, representing a wide geographical and lifestyle range.There are few differences among the populations when features are considered individually. Neanderthals and early H. sapiens fell within the range of modern human variation. When the suite of measurements and shapes were analyzed, differences and similarities became apparent. The Neanderthal radius is more laterally curved, has a more medially placed radial tuberosity, a longer radial neck, a more antero-posteriorly ovoid head and a well-developed proximal interosseous crest. The Neanderthal ulna has a more anterior facing trochlear notch, a lower M. brachialis insertion, larger relative mid-shaft size and a more medio-lateral and antero-posterior sinusoidal shaft. The Neanderthal lower arm morphology reflects a strong cold-adapted short forearm. The forearms of H. sapiens are less powerful in pronation and supination. Many differences between Neanderthals and H. sapiens can be explained as a secondary consequence of the hyper-polar body proportions of the Neanderthals, but also as retentions of the primitive condition of other hominoids.     

Three dimensional arm trajectories

Biological Cybernetics - Planar arm trajectories are characterized by a segmentation of the hand velocity profile and by a coupling between shape and speed. The question addressed in this paper is...     

Deletion long arm 13

Summary A case of interstitial deletion 13q is presented and compared with the previously presented nine cases of different terminal as well as interstitial deletion 13q.     

The inner arm fasciocutaneous flap

A fasciocutaneous flap raised on the inner surface of the upper arm has been used to release 16 burn scar contractures of the anterior axillary fold. It is a relatively quick and simple procedure that adequately corrects the contracture and does not have to followed by prolonged splinting.     

A comparison of blood pressure measurement over a sleeved arm versus a bare arm

Background

The measurement of blood pressure is a common clinical exam with important health consequences. We sought to determine whether the measurement of blood pressure over a sleeved arm varies from that taken on a bare arm.

Methods

We recruited 376 patients between 18 and 85 years of age from a family medicine clinic between September 2004 and November 2006. They all had their blood pressure recorded using the same automatic oscillometric device, with the cuff placed over their bare arms for the first reading. Each patient was then randomly assigned to either the bare-arm group, for which the second blood pressure reading was also taken on a bare arm, or the sleeved-arm group, for which the second reading was taken with the cuff placed over the patient''s sleeve.

Results

The mean age of the 376 participants was 61.6 years (standard deviation 15.0), 61% of the participants were male, 41% had hypertension and 11.7% had diabetes. We found no clinically important differences between the bare-arm group (n = 180) and the sleeved-arm group (n = 196) in age, sex or body mass index. The mean differences between the first and second readings for patients in the bare-arm group were 4.1 mm Hg (95% confidence interval [CI] 2.8 to 5.5) for systolic blood pressure and 0.1 mm Hg (95% CI –0.7 to 0.9) for diastolic blood pressure. The mean differences between the first and second readings for patients in the sleeved-arm group were 3.4 mm Hg (95% CI 2.1 to 4.7) for systolic blood pressure and 0.4 mm Hg (95% CI –0.4 to 1.3) for diastolic blood pressure. The between-group differences in these values was 0.76 mm Hg (95% CI –1.13 to 2.65) for systolic and –0.31 mm Hg (95% CI –1.48 to 0.86) for diastolic blood pressure; neither of these differences was clinically important or statistically significant.

Interpretation

We found that there was no significant difference in blood pressure recorded over a sleeve or on a bare arm. For practical purposes, the decision to measure blood pressure on a bare arm or over a sleeved arm should be left to the judgment of the health care professional taking the blood pressure.The measurement of blood pressure is one of the most common examinations undertaken in family practice and has important health and management consequences for the patient. Accurate assessment of blood pressure, therefore, is very important. Current guidelines outline standards for obtaining accurate and reproducible blood pressure measurements.¹ These standards include guidelines for the sizes of blood pressure cuffs and the position of the patient''s arm, as well as a recommendation that the patient be seated for 5 minutes before his or her blood pressure is taken. In addition, it has been recommended that blood pressure be measured over the patient''s bare arm.¹ However, the current recommended method to determine blood pressure² has several limitations (e.g., high variability of blood pressure at different times of day or if measured only once, loss of proper technique post-training).Three previous studies have assessed whether blood pressure varies significantly when taken over a sleeved arm compared with a bare arm. Details of the literature review are described in Appendix 1, available online at www.cmaj.ca/cgi/content/full/178/5/585/DC2. In one study, involving 36 patients, Holleman et al³ found no significant differences in systolic or diastolic blood pressure readings taken over the sleeved or bare arm of each patient. However, this study was limited because of its small sample and because blood pressure measurements were taken on both arms simultaneously. A study by Kahan et al,⁴ involving 201 patients, compared blood pressure measurements taken over a sleeved arm, a bare arm and below a rolled-up sleeve. They found that the degree of clothing under the sphygmomanometer cuff did not have a clinically important effect on the reading. Although they found no significant difference in the effect of clothing on blood pressure readings, the study was limited by their design of measuring blood pressure below a rolled-up sleeve. The third study, conducted by Liebl et al,⁵ was published while our study was in progress. Their study, which involved 201 patients, compared blood pressure measurements taken over a sleeved arm and a bare arm with both sphygmomanometric and oscillometric devices. They concluded no significant difference in readings between the sleeved and bare-arm groups. In contrast to previous studies, we sought to determine whether the measurement of blood pressure over a sleeved arm varies from that taken over a bare arm through the use of a control group in which patients'' blood pressure was taken only over a bare arm.     

Ambulatory measurement of arm orientation

In order to evaluate the impact of neuromuscular disorders affecting the upper extremities, the functional use of the arm need to be evaluated during daily activities. A system suitable for measuring arm kinematics should be ambulatory and not interfere with activities of daily living. A measurement system based on miniature accelerometers and gyroscopes is adequate because the sensors are small and do not suffer from line of sight problems. A disadvantage of such sensors is the cumulative drift around the vertical and the problems with aligning the sensor with the segment. A method that uses constraints in the elbow to measure the orientation of the lower arm with respect to the upper arm is described. This requires a calibration method to determine the exact orientation of each of the sensors with respect to the segment. Some preliminary measurements were analyzed and they indicated a strong reduction in orientation error around the vertical. It seemed that the accuracy of the method is limited by the accuracy of the sensor to segment calibration.     

Reciprocal translocation between Y chromosome long arm euchromatin and the short arm of chromosome 1

A case with an apparently balanced reciprocal translocation between the long arm of the Y chromosome and the short arm of chromosome 1 t(Y;1)(q11.2;p34.3) is described. The translocation was found in a phenotypically normal male ascertained by infertility and presenting for intra-cytoplasmatic sperm injection treatment. Histological examination of testicular biopsies revealed spermatogenic failure. Chromosome painting with probes for chromosome 1 and for the euchromatic part of the Y chromsome confirmed the translocation of euchromatic Y chromosomal material onto the short arm of chromosome 1 and of a substantial part of the short arm of chromosome 1 onto the Y chromosome. Among the Y/autosome translocations, the rearrangements involving long arm euchromatin of the Y chromosome are relatively rare and mostly associated with infertility. Microdeletion screening at the azoospermia locus revealed no deletions, suggesting another mechanism causing infertility in this translocation carrier.     

Effect of body roll amplitude and arm rotation speed on propulsion of arm amputee swimmers

Only a limited amount of research has gone into evaluating the contribution made by the upper arm to the propulsion of elite swimmers with an amputation at elbow level. With assistance of computational fluid dynamics (CFD) modelling, the swimming technique of competitive arm amputee swimmers can be assessed through numerical simulations which test the effect of various parameters on the effectiveness of the swimming propulsion.This numerical study investigates the effect of body roll amplitude and of upper arm rotation speed on the propulsion of an arm amputee swimmer, at different mean swimming speeds. Various test cases are simulated resulting in a thorough analysis of the complex body/fluid interaction with a detailed quantitative assessment of the effect of the variation of each parameter on the arm propulsion. It is found that a body roll movement with an amplitude of 45° enhances greatly the propulsive contribution from the upper arm with an increase of about 70% in the propulsive force compared to the no roll condition. An increase in the angular velocity of the upper arm also leads to a concomitant increase in the propulsive forces produced by the arm.Such results have direct implications for competitive arm amputee front crawl swimmers and for those who coach them. One important message that emerges in this present work is that there exists, for any given swimming speed, a minimum angular velocity at which the upper arm must be rotated to generate effective propulsion. Below this velocity, the upper arm will experience a net resistive drag force which adversely affects swimming performance.     

Force production and spatial arm coordination profile in arm crawl swimming in a fixed position

This study analyzed the relationship between mechanical force production and spatial arm position of the swimming movement for each side of the swimmer. Eight internationally recognized male swimmers performed fix positioned arm only swimming with a dynamometer synchronized with underwater cameras. The upper arm positions (α in side, β in frontal view) and the elbow angles (γ in 3D) were determined at the moment where the force production reached the peak (Fmax) and the maximal values of rate of force development (RFDmax). RFDmax and α values showed significant differences between the sides (P<0.05). To show the motion integration structure of the performance, Multiple Regression Analysis (MRA) was employed separately for both sides. For the criterion variable, the impulse of force (ImpF50%) was calculated. The defined parameters as the mechanical and spatial predictor system were used for the model. The results of the MRA showed that the predictor system yielded the model structure of the variables that explain the criterion variables for ImpF50% by the dominant (P=0.007) and by the nondominant side (P=0.001), respectively. The alternate contribution of the variables to the models can objectively express the performance difference between the two sides of the swimmer.     

Cellular and molecular mechanisms of arm regeneration in crinoid echinoderms: the potential of arm explants

 Crinoid echinoderms can provide a valuable experimental model for studying all aspects of regenerative processes from molecular to macroscopic level. Recently we carried out a detailed study into the overall process of arm regeneration in the crinoid Antedon mediterranea and provided an interpretation of its basic mechanisms. However, the problem of the subsequent fate of the amputated arm segment (explant) once isolated from the animal body and of its possible regenerative potential have never been investigated before. The arm explant in fact represents a simplified and controlled regenerating system which may be very useful in regeneration experiments by providing a valuable test of our hypotheses in terms of mechanisms and processes. In the present study we carried out a comprehensive analysis of double-amputated arm explants (i.e. explants reamputated at their distal end immediately after the first proximal amputation) subjected to the same experimental conditions as the regenerating donor animals. Our results showed that the explants undergo similar regenerative processes but with some significant differences to those mechanisms described for normal regenerating arms. For example, whilst the proximal-distal axis of arm growth is maintained, there are differences in terms of the recruitment of cells which contribute to the regenerating tissue. As with normal regenerating arms, the present work focuses on (1) timing and modality of regeneration in the explant; (2) proliferation, migration and contribution of undifferentiated and/or dedifferentiated/transdifferentiated cells; (3) putative role of neural growth factors. These problems were addressed by employing a combination of conventional microscopy and immunocytochemistry. Comparison between arm explants and regenerating arms of normal donor adults indicates an extraordinary potential and regenerative autonomy of crinoid tissues and the cellular plasticity of the phenomenon. Received: 9 March 1998 / Accepted: 5 June 1998     

Partial duplication of 17 long arm

Three subjects from 2 unrelated families with partial duplication of 17q, derived from a reciprocal parental translocation between chromosomes 11 and 17 with different breakpoints, are described. A female patient from one family with a 46,XX,-11,+der(11),t(11;17)(q24;q23.2)pat chromosome complement had died at 2 months of age. In the second family, a male propositus and a subsequent fetus, identified by cytogenetic prenatal diagnosis, showed a 46,XY,-11,+der(11),t(11;17)(q2505,q24.3) mat chromosome complement. Twelve other cases involving partial duplication of chromosome 17 have been reported, 11 of these derived from a balanced translocation, and 1 was a duplication. All these cases showed psychomotor and mental retardation, cranial contour anomalies, micrognathia, bulbous nose, short neck, skeletal anomalies, and CNS defects. The phenotypic and clinical observations in the three subjects of this report are compared with previously reported findings.     

Impedance imaging in upper arm fractures

We used the Aberdeen impedance imaging system to drive a constant current of 1 mA on a 10 kHz sine wave into the upper arm encircled by an elastic belt of 16 equi-spaced strip electrodes. The system was used to examine a normal upper arm, an upper arm with a recent humeral fracture and an upper arm with a clinically united fracture. We approximated the human upper arm to a circular cylinder and assumed bilateral symmetry of normal human limbs. We measured transverse limb resistivity ratios and reconstructed static two-dimensional images of the spatial distribution of log(resistivity) by the equipotential back projection technique using a homogeneous muscle equivalent saline reference. Our results indicate that impedance osteography provides unique information about the changing electrical characteristics at the fracture site. This information could prove a useful adjunct to clinical and radiological tests for fracture union.     

Biological arm motion through reinforcement learning

The present paper discusses an optimal learning control method using reinforcement learning for biological systems with a redundant actuator. It is difficult to apply reinforcement learning to biological control systems because of the redundancy in muscle activation space. We solve this problem with the following method. First, we divide the control input space into two subspaces according to a priority order of learning and restrict the search noise for reinforcement learning to the first priority subspace. Then the constraint is reduced as the learning progresses, with the search space extending to the second priority subspace. The higher priority subspace is designed so that the impedance of the arm can be high. A smooth reaching motion is obtained through reinforcement learning without any previous knowledge of the arms dynamics.     

Motor control of voluntary arm movements

The motor control of pointing and reaching-to-grasp movements was investigated using two different approaches (kinematic and modelling) in order to establish whether the type of control varies according to modifications of arm kinematics. Kinematic analysis of arm movements was performed on subjects' hand trajectories directed to large and small stimuli located at two different distances. The subjects were required either to grasp and to point to each stimulus. The kinematics of the subsequent movement, during which subject's hand came back to the starting position, were also studied. For both movements, kinematic analysis was performed on hand linear trajectories as well as on joint angular trajectories of shoulder and elbow. The second approach consisted in the parametric identification of the black box (ARMAX) model of the controller driving the arm movement. Such controller is hypothesized to work for the correct execution of the motor act. The order of the controller ARMAX model was analyzed with respect to the different experimental conditions (distal task, stimulus size and distance). Results from kinematic analysis showed that target distance and size influenced kinematic parameters both of angular and linear displacements. Nevertheless, the structure of the motor program was found to remain constant with distane and distal task, while it varied with precision requirements due to stimulus size. The estimated model order of the controller confirmed the invariance of the control law with regard to movement amplitude, whereas it was sensitive to target size.     

Fragile site long arm chromosome 16

Summary A fragile site at the long arms (q21) of chromosome 16 was found in two persons, each of whom became the parent of a child with a de novo structural chromosome abnormality—a balanced autosomal translocation and an autosomal deletion. The question of an increased risk of structural chromosome abnormalities in the offspring of persons with fragile site long arm 16 is discussed.