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PubMed1984

A study of correlations and estimation of stature from hand length, hand breadth and sole length.

An attempt is made to find out possible correlations amongst hand length, hand breadth (stretched) and sole length and to derive a regression formula to estimate stature from them. The study was based on the measurement of 100 Nigerian adult male medical students of the Jos Medical School, Nigeria, between the ages of 20-30 years. The results show that there are significant correlations between the stature of an individual and hand length, hand breadth and sole length.

Adult↗
PubMed1982

[Slow brain potentials in writing: the correlation between writing hand and speech dominance in right-handed humans].

1. Slow cerebral potential shifts were recorded from the scalp over both cerebral hemispheres by retrograde summation while 23 right-handers were writing. Averaging included writing errors, but eliminated eye movements and other artifacts. Repeated writing of the same word or sentence was compared to writing different dictated words, to drawings, and to other control experiments. 2. Surface negative readiness potentials (Bereitschaftspotential) appeared about 1 s before writing, which was similar to those preceding other voluntary movements. 3. During writing, the writing potentials in different cortical regions began with a negative increase of the Bereitschaftspotential, usually followed by a plateau or positive waves. One or several biphasic potentials persisted for another 2 s after writing had ceased. 4. The writing potentials had rather constant forms in the same individual, but showed large interindividual variations of form and polarity. The largest initial negativity (with both ear lobes serving as reference) occurred at the vertex and the left motor region contralateral to the writing hand. 5. The left hemispheric preponderance of writing potentials, maximal at the precentral region contralateral to the writing hand, was less marked when writing with the left hand. An interaction of the writing hand and language dominance is assumed. 6. Writing the same word or short sentence repeatedly caused potentials of larger amplitude than the preceding readiness potentials. Writing dictated words or drawing figures after verbal stimuli that require language processing caused larger potentials in the left hemisphere than did repeated word writing. 7. The fact that negative potentials with larger left hemispheric amplitudes appear after verbal stimuli may indicate that language information is processed in the speech-dominant hemisphere before and during writing or drawing. 8. By variously combining bipolar leads, the lateral differences of the potential fields can be more clearly distinguished than by using only unipolar leads with ear reference.

Adult↗
PubMed1991

A molecular switch: subunit rotations involved in the right-handed to left-handed transitions of Salmonella typhimurium flagellar filaments.

Using the combined techniques of cryoelectron microscopy and image analysis, we generated three-dimensional reconstructions of flagellar filaments from straight, right-handed (SJW1655-R) and straight, left-handed (SJW1660-L) Salmonella typhimurium mutants, both of which have the same parental strain (SJW1103). In the filaments from SJW1655, all flagellin subunits have the same conformation (R), while in filaments from SJW1660, the subunits are all in the alternate (L) conformation. The difference between the two three-dimensional density maps reveal the structural changes that accompany switching of the flagellin subunits between the two conformations. In going from the R to L state, the subunit undergoes a rotation 30 degrees clockwise about a radial axis and 38 degrees clockwise about a vertical axis, and suffers a 50 degrees bend of the outer, relative to the inner, subunit domain. The intersubunit spacing, along the 11-start protofilaments, changes from 51.6 A in the right-handed filament to 52.1 A in the left-handed filament. In order to produce the correct corkscrew shape in native filaments, the change in contacts that produces this shortening of 0.5 A must occur among the inner domains at a radius of about 30 A. We suggest that the changes in the middle domains of the subunit are the switch that forces changes in the inner domains.

Cell Movement↗
PubMed1988

Cued dichotic listening with right-handed, left-handed, bilingual and learning-disabled children.

This study used cued dichotic listening to investigate differences in language lateralization among right-handed (control), left-handed, bilingual, and learning-disabled children. A sample of 60 subjects ranging in age from 7-13 yr were administered a CVC dichotic paradigm with three experimental conditions (free recall, directed left, directed right). A three-factor ANOVA design conducted on the data revealed that control, bilingual, and learning-disabled children produced the expected REA suggestive of left hemisphere dominance for language processing whereas left-handed children produced an LEA suggestive of right hemisphere superiority for language processing. The cued attention data derived from groups as well as from individual subjects suggested that in comparison with control children, left-handed children were greatly susceptible to attentional manipulation similar to learning-disabled children only in the opposite hemisphere. Bilingual children were found to have a REA much like control children although recall accuracy was depressed. Further, lambda (lambda) analyses conducted on individual subjects indicated that the magnitude and degree of perceptual asymmetry varied widely among individuals of various anomaly groups. These findings lend support to the hypothesis that attentional factors play a larger role in unilateral processing for some anomalous groups of children (i.e. left-handers and learning-disabled) while not affecting others (i.e. controls and bilinguals).

Attention↗
PubMed2006

A hand-over-hand diffusing model for myosin-VI molecular motors.

Single molecules of dimeric myosin-VI have been demonstrated to be able to move processively towards the pointed end of actin filament with a mean step size of approximately 36 nm. Here we present a hand-over-hand diffusing mechanism for this unidirectional movement. Based on this mechanism, its dynamical behaviors such as the step-size distribution, dwell-time distributions and mean dwell time at various ATP and ADP concentrations and under various loads are studied in detail. The calculated results show good agreement with previous experimental results. The processive movement of mutant myosin-V with its neck domains truncated to only one IQ motif can also be explained by using this hand-over-hand diffusing model.

Actins↗
PubMed1990

Right hand agraphia and left hand apraxia following callosal damage in a right-hander.

A right-handed Japanese man showed agraphia more marked with the right hand, apraxia confined to the left hand, and right ear extinction on dichotic listening, following damage to the anterior two-thirds of the corpus callosum, the rostral and lower parts of the right medial frontal lobe and a small portion of the left medial frontal lobe. The symptoms were attributed to hemispheric disconnection, on the assumption that the right hemisphere was dominant for language and the left for limb praxis. This case provides good evidence for dissociated lateralization of language and limb praxis in some right-handed individuals. The study of writing performance suggested the following hypotheses: (1) motor engrams for limb praxis and writing may be dissociated, and (2) motor engrams for writing Kana (phonogram) and Kanji (ideogram) letters are represented on both hemispheres, although the hemisphere nondominant for language seems unable to combine graphemes into a correct meaningful sequence.

Agraphia↗
PubMed2004

Myosin VI walks hand-over-hand along actin.

Myosin VI is a molecular motor that can walk processively on actin filaments with a 36-nm step size. The walking mechanism of myosin VI is controversial because it takes very large steps without an apparent lever arm of required length. Therefore, myosin VI is argued to be the first exception to the widely established lever arm theory. It is therefore critical to directly demonstrate whether this motor walks hand-over-hand along actin despite its short lever arm. Here, we follow the displacement of a single myosin VI head during the stepping process. A single head is displaced 72 nm during stepping, whereas the center of mass previously has been shown to move 36 nm. The most likely explanation for this result is a hand-over-hand walking mechanism. We hypothesize the existence of a flexible element that would allow the motor to bridge the observed 72-nm distance.

Actins↗
PubMed2006

On the hand-over-hand mechanism of kinesin.

We present here a simple theoretical model for conventional kinesin. The model reproduces the hand-over-hand mechanism for kinesin walking to the plus end of a microtubule. A large hindering force induces kinesin to walk slowly to the minus end, again by a hand-over-hand mechanism. Good agreement is obtained between the calculated and experimental results on the external force dependence of the walking speed, the forward/backward step ratio, and dwell times for both forward and backward steps. The model predicts that both forward and backward motions of kinesin take place at the same chemical state of the motor heads, with the front head being occupied by an ATP (or ADP,Pi) and the rear being occupied by an ADP. The direction of motion is a result of the competition between the power stroke produced by the front head and the external load. The other predictions include the external force dependence of the chemomechanical coupling ratio (e.g., the stepping distance/ATP ratio) and the walking speed of kinesin at force ranges that have not been tested by experiments. The model predicts that the chemomechanical coupling remains tight in a large force range. However, when the external force is very large (e.g., approximately 18 pN), kinesin slides in an inchworm fashion, and the translocation of kinesin becomes loosely coupled to ATP turnovers.

Adenosine Diphosphate↗
PubMed1989

Hand dominance and implications for left-handed operation of controls.

This review paper argues that the consequences of control performance among left-handed operators, who may represent a sizeable portion of the population, should not be disregarded as a design issue. Principally, the control panel designer may err in assuming that left-handers, given enough time and effort, will simply 'learn' to operate a complex control intended for right-handed usage. This widely held position is unfounded in light of the available evidence; left-handers, as well as right-handers, consistently perform less well with the non-dominant hand as compared to the dominant one in a variety of behavioural tasks. The designer should be aware of the potential decrement in performance which may be associated with operation by the non-dominant hand, especially in critical control situations. A model for determining the relevance of the operator's handedness in the design and layout of controls is presented.

Equipment Design↗
PubMed2003

Pilot study: data-capturing consistency of two trans-tibial casting concepts, using a manikin stump model: a comparison between the hands-on PTB and hands-off ICECAST compact concepts.

The quality of fit of a trans-tibial patellar tendon bearing (PTB) socket may be influenced by consistency in casting, rectification or alignment. For this study two distinctive different data-capturing concepts were tested in relation to prosthetist performance. The hands-on PTB and hands-off ICECAST compact concept were studied and compared for inter- and intra-prosthetist consistency using a specially designed manikin stump model. A purpose designed digitiser was used to scan a selected surface area of the produced models, 5 for each concept, 10 in total. The extent of casting consistency at each of 936 locations per plaster model was calculated and the level of consistency was quantified. This study has shown that by using the manikin model there is a clear indication that the investigated hands-off concept produces more consistent results than the hands-on concept.

Amputation Stumps↗
PubMed1996

Attempts to switch the writing hand: relationships to age and side of hand preference.

The recent suggestion that left-handedness is a mortality risk factor has prompted extensive media attention and has renewed research interest in generational differences in hand preference incidence and training. It is argued that differential generational training effects (the modification hypothesis), rather than decreased survival fitness (the elimination hypothesis), account for the lower numbers of individuals classified as left-handers in contemporary samples over the age of 60 years. A total of 633 individuals (aged 13-83 years) were queried about attempts to switch hand preference. Forty-one (6.5%) described efforts to shift preference in the rightward direction; of these, 21 (3.3%) reported attempted rightward writing hand shifts. The percentage of older adult left-handers, who reported right shifts in writing, was greater than the percentage of younger left-handers who described such attempts. Comparisons between the group reporting right shifts and those reporting no shift experiences suggested that the age-related decrease in leftward preference was specific to a decrease in the incidence of left-hand writing among older adults.

Journal Article↗
PubMed2000

Serum levels of female sex hormones in left-handed and right-handed menopausal women.

The study covered 25 left-handed and 27 right-handed clinically healthy females aged between 47 and 55 years during normal menopause. It was carried out in the third year from the beginning of amenorrhoea. The levels of the follicle-stimulating hormone, luteinising hormone, proclactin, estradiol, and progesterone were determined by means of enzyme-immunological methods with IMX (Abbott, USA) and Serozyme I (Biochem Immunosystem Diagnostica, USA) apparatuses. It was established that in left-handed women the serum concentrations both of the follicle-stimulating hormone and luteinising hormone were significantly higher (P <.001), and those of prolactin, estradiol, and progesterone much lower (P <.001), as compared to the right-handed women.

Journal Article↗
PubMed2002

Distinguishing inchworm and hand-over-hand processive kinesin movement by neck rotation measurements.

The motor enzyme kinesin makes hundreds of unidirectional 8-nanometer steps without detaching from or freely sliding along the microtubule on which it moves. We investigated the kinesin stepping mechanism by immobilizing a Drosophila kinesin derivative through the carboxyl-terminal end of the neck coiled-coil domain and measuring orientations of microtubules moved by single enzyme molecules at submicromolar adenosine triphosphate concentrations. The kinesin-mediated microtubule-surface linkage was sufficiently torsionally stiff (>/=2.0 +/- 0.9 x 10(-20) Newton meters per radian2) that stepping by the hypothesized symmetric hand-over-hand mechanism would produce 180 degree rotations of the microtubule relative to the immobilized kinesin neck. In fact, there were no rotations, a finding that is inconsistent with symmetric hand-over-hand movement. An alternative "inchworm" mechanism is consistent with our experimental results.

Adenosine Triphosphate↗
PubMed2003

Kinesin walks hand-over-hand.

Kinesin is a processive motor that takes 8.3-nm center-of-mass steps along microtubules for each adenosine triphosphate hydrolyzed. Whether kinesin moves by a "hand-over-hand" or an "inchworm" model has been controversial. We have labeled a single head of the kinesin dimer with a Cy3 fluorophore and localized the position of the dye to within 2 nm before and after a step. We observed that single kinesin heads take steps of 17.3 +/- 3.3 nm. A kinetic analysis of the dwell times between steps shows that the 17-nm steps alternate with 0-nm steps. These results strongly support a hand-over-hand mechanism, and not an inchworm mechanism. In addition, our results suggest that kinesin is bound by both heads to the microtubule while it waits for adenosine triphosphate in between steps.

Adenosine Triphosphate↗
PubMed2005

Differential labeling of myosin V heads with quantum dots allows direct visualization of hand-over-hand processivity.

The double-headed myosin V molecular motor carries intracellular cargo processively along actin tracks in a hand-over-hand manner. To test this hypothesis at the molecular level, we observed single myosin V molecules that were differentially labeled with quantum dots having different emission spectra so that the position of each head could be identified with approximately 6-nm resolution in a total internal reflectance microscope. With this approach, the individual heads of a single myosin V molecule were observed taking 72-nm steps as they alternated positions on the actin filament during processive movement. In addition, the heads were separated by 36 nm during pauses in motion, suggesting attachment to actin along its helical repeat. The 36-nm interhead spacing, the 72-nm step size, and the observation that heads alternate between leading and trailing positions on actin are obvious predictions of the hand-over-hand model, thus confirming myosin V's mode of walking along an actin filament.

Actins↗
PubMed1995

A difference in heights and weights between right-handed and left-handed bowlers at cricket.

Right-handed pitchers have been shown to be significantly taller and heavier than left-handed pitchers. An analysis of 113 professional cricketers in England showed a similar difference between right-handed and left-handed bowlers. On average the right-handers were 1.05 in. taller and 8.30 lb. heavier than the left-handers, differences which were close to significance at the 5% level with this small n.

Animals↗
PubMed1998

No transfer of visuomotor learning of button-pressing from right to left hands in right-handed four-year-olds.

To assess the underlying mechanism of visuomotor learning in children and its relation to the cerebral lateralization, intermanual transfer of learning was examined on a button-press task. The main experiment examined transfer of learning from one hand to the other for 36 right-handed 4-yr.-olds, 19 5-yr.-olds, and 8 adults. The experiment consisted of three phases. In the first and second of three phases, the subject performed the task with the right [(or left) hand, then with the left (or right)]. All age groups exhibited transfer from the left to the right hands; however, the 4-yr.-olds showed no transfer from the right to the left, whereas the other age groups showed transfer from the right to the left as well as left to right. Results were discussed in relation to the underlying mechanism of learning and hemispheric organization, and a new interpretation was proposed.

Adult↗
PubMedDate not supplied

Motor stability in visuomotor control of repetitive hand movements and its differential cerebral control in right-handed subjects.

The stability of asymmetric motor control was studied in right-handed subjects. Hand skill was assessed by a peg moving task in ten trials. The mean peg moving time (PMT) and its standard deviation (SD) were calculated for each hand. Standard deviation was taken as an index of the stability of visuomotor control. The mean rate of a repetitive movement (mean PMT) did not always show an association with its stability (SDs). This depended upon familial sinistrality, sex, and cerebral lateralization such as eye and foot preferences of the subjects. The left-right differences in movement stabilities also showed different contributions of the right and left brains of the subjects depending upon these factors. It was suggested that these factors should be taken into consideration in studies concerning the hemispheric control of especially corrective components of skilled movements of hands.

Adult↗