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PubMed2005

Reach and posture hand preferences during arboreal feeding in Sifakas (Propithecus sp.): a test of the postural origins theory of behavioral lateralization.

Sixteen sifakas (11 Propithecus verreauxi coquereli, 2 Propithecus verreauxi verreauxi form majori, and 3 Propithecus tattersalli) were videotaped as they fed on leaves in an arboreal context. The hand used to feed and the hand used to maintain postural stability was coded. For each subject, the lateral bias of the hand used to feed was opposite the hand used in postural support. Seven sifakas displayed no bias for feeding or posture-related hand use, 7 sifakas displayed significant feeding-related reach preferences for pulling branches to the mouth (5 left- and 2 right-hand preferences), and 9 sifakas exhibited significant hand preferences for postural support (2 left-, 7 right-hand preferent). Although these data do not strongly support the postural origins theory of behavioral lateralization, the modal preference pattern for sifakas that displayed significant hand preferences for posture and feeding involve a left bias for feeding and a right bias for postural support. s reserved).

Animals↗
PubMed1992

Homology modelling of integrin EF-hands. Evidence for widespread use of a conserved cation-binding site.

Integrin alpha-subunits contain three or four peptide sequences that are similar to the EF-hand, a 13-residue bivalent cation-binding motif found in calmodulin and parvalbumin. The integrin sequences differ from classical EF-hands in that they lack a co-ordinating residue at position 12. One hypothesis to explain integrin-ligand binding is that aspartate-containing recognition sequences in integrin ligands, which bind at or near to the EF-hand-like sequences, may take the place of the missing residue and co-ordinate directly to the bound cation. In this report, homology modelling of integrin EF-hand-like sequences has been performed using the X-ray structure of calmodulin as a template in order to assess the functional activity of the integrin sequences. In the calmodulin-integrin hybrid structures, integrin EF-hand-like sequences were able to retain cations whereas control sequences did not. Structural analyses demonstrated that the integrin sequences in the hybrid proteins closely resembled conventional EF-hands. The integrin sequences are therefore highly likely to bind Ca2+ ions in vivo, a prerequisite for the ligand-binding model. Database searching with a matrix derived from known integrin EF-hand-like sequences has been used to identify other proteins containing the integrin EF-hand-like motif. Annexin V (anchorin CII), atrial natriuretic peptide receptors and the 70 kDa heat-shock protein were identified by the matrix; the functions of these proteins are known from previous studies to be bivalent cation-dependent. These findings suggest that the integrin EF-hand-like sequence may be a more common motif than originally thought.

Amino Acid Sequence↗
PubMed2001

Postpartum maternal oxytocin release by newborns: effects of infant hand massage and sucking.

BACKGROUND: Newborns placed skin-to-skin with their mothers show an inborn sequence of behavior similar to that seen in other mammals. The purpose of this study was to make a detailed exploration of hand movements and sucking behavior in healthy term newborns who were placed skin-to-skin on their mothers' chests, and to study maternal oxytocin release in relation to these behaviors. METHODS: Ten vaginally delivered infants whose mothers had not been exposed to maternal analgesia were video-recorded from birth until the first breastfeeding. Video protocols were developed based on observations of the videotapes. Each infant's hand, finger, mouth, and tongue movements, positions of the hand and body, and sucking behavior were assessed every 30 seconds. Maternal blood samples were collected every 15 minutes, and oxytocin levels were analyzed by radioimmunoassay. A statistical test for establishing the relationship between maternal oxytocin levels and infants' hand movements or sucking behavior was developed. RESULTS: Infants used their hands to explore and stimulate their mother's breast in preparation for the first breastfeeding. A coordinated pattern of infant hand and sucking movements was also identified. When the infants were sucking, the massagelike hand movements stopped and started again when the infants made a sucking pause. Periods of increased massagelike hand movements or sucking of the mother's breast were followed by an increase in maternal oxytocin levels (p < 0.005). CONCLUSIONS: The findings indicate that the newborns use their hands as well as their mouths to stimulate maternal oxytocin release after birth, which may have significance for uterine contraction, milk ejection, and mother-infant interaction.

Adult↗
PubMed1996

Inactivation of EF-hands makes GCAP-2 (p24) a constitutive activator of photoreceptor guanylyl cyclase by preventing a Ca2+-induced "activator-to-inhibitor" transition.

Guanylyl cyclase activator proteins GCAP-1 and GCAP-2 (Dizhoor et al. , 1995, Gorczyca et al., 1995) are members of a recently identified subclass of EF-hand type Ca2+-binding proteins that respond to Ca2+ differently than any other known members of the EF-hand superfamily. GCAPs acquire an activating conformation only in their Ca2+-free form. Free Ca2+ concentrations corresponding to levels in dark-adapted vertebrate photoreceptors inhibit the ability of GCAPs to activate photoreceptor guanylyl cyclases (RetGCs). We studied the effects of mutations that block binding of Ca2+ to the EF-hands of GCAP-2. Unlike other EF-hand proteins, which fail to activate their target when their EF-hands are inactivated by mutations, GCAP-2 with any single EF-hand inactivated remains active and is 3-6 times less sensitive to the inhibitory effect of Ca2+. Inactivation of any two or all three EF-hands produces active forms of GCAP-2 that are insensitive to inhibition by physiological intracellular concentrations of Ca2+. Unexpectedly we also found that activation of RetGCs by a Ca2+-insensitive mutant is inhibited by Ca2+-loaded wild type GCAP-2. We propose the following. 1) GCAP-2 can exist in two extreme functional forms: an apo form that activates RetGCs and a Ca2+-loaded form that blocks activation of RetGCs. 2) All three EF-hands of GCAP-2 contribute to the inhibitory effect of Ca2+. 3) Inactivation of two or three EF-hands is sufficient to shift the "activator-inhibitor" transition outside the physiological range of intracellular free Ca2+.

Amino Acid Sequence↗
PubMed1991

Human strength capabilities during one-handed maximum voluntary exertions in the fore and aft plane.

Maximal static strengths were determined for one-handed exertions in all directions in the fore and aft plane. Data from 12 males and 10 females (mean age 30.7 yrs, standard deviation (SD) = 8.9 yrs, n = 22) were obtained with handle heights of 1.0 and 1.75 m. Twelve of the subjects also performed two-handed exertions at the same handle heights. The ratio of mean strengths of females to that of males ranged from 0.50 to 0.83 (for absolute forces) and from 0.63 to 1.00 for forces normalized to body weight. The ratios of one-handed to two-handed strengths ranged from 0.64 to 1.04. Two-handed strengths commonly exceeded one-handed strengths at the lower handle height, but showed fewer significant strength differences (p less than 0.05) according to direction at 1.75 m. Both female/male and one-handed/two-handed strength ratios were found to be dependent on direction of exertion and handle height. The observed strength dependencies upon number of hands (one or two-handed), direction of exertion, handle height and sex are discussed. The strength data have implications for use in biomechanical models and task analysis.

Adult↗
PubMed2003

Sex and handedness differences in eye-hand visual reaction times in handball players.

Sex and handedness differences in the eye-dominant hand, the right eye-right hand and the left eye-left hand visual reaction times were studied in 270 right-handed and 56 left -handed young handball players. Reaction time was assessed by a software package. All visual reaction times were longer in women than in men. In the eye-dominant hand and the left eye- left hand visual reaction times, the left-handers had a superiority over the right handers, but there was no difference between the right eye-right hand visual reaction times of the right- and left-handers. In right-handers, all visual reaction times were longer in women than in men, but there was no sex difference in left-handers. The results suggest that left-handed players have probably an intrinsic neurological advantage.

Adolescent↗
PubMed1999

Performance Asymmetries in Computer Mouse Control of Right-Handers, and Left-Handers with Left- and Right-Handed Mouse Experience.

Precision and general computer mouse aiming performance by right-handers (RH-RM) and left-handers with right-handed mouse experience (LH-RM) and by left-handers with left-handed mouse experience (LH-LM) were compared. A number of performance measures, such as reaction time, time to reach a target, time to click on target, and cursor trajectory, were analyzed. Superficially, specific hand experience seemed to dictate performance asymmetries, but a closer look revealed interactions between hand preference and hand performance. That finding has implications for theories of handedness. In addition, precision and general directional aiming with the mouse cursor showed a clear right hand superiority in reaction time in both RH-RM and LH-RM subjects, whereas LH-LM subjects showed no lateral asymmetries. Finally, the overall time taken for the task, averaged across groups and conditions, favored the experienced hand by some 180 ms. In practical terms, that is not a large difference, especially because the difference will be reduced with practice. Thus, the use of the inexperienced hand can be advocated when there is a need to forestall or ameliorate repetitive stress in the experienced hand.

Journal Article↗
PubMed2005

Manual skill, hand skill asymmetry, and neuropsychological test performance in schoolchildren with spastic cerebral palsy.

Bilateral hand skill assessment with a computerised version of the Peg Moving Task, and neuropsychological testing, were performed in 30 children aged 7 to 8 years with spastic cerebral palsy (CP) and without mental retardation, diplegia (n = 10), right hemiplegia (n = 10), or left hemiplegia (n = 10), and in 30 controls. Compared to controls: (i) 30% of the hemiplegic children showed impairment of the unaffected hand and 70% of the diplegic children showed impairment in both hands; (ii) children with CP were impaired only in oral repetition and in visual-motor tasks. Results of neuropsychological testing were not significantly different between the three groups of children with CP. Right minus left asymmetry in hand skill was not related to neuropsychological testing; however, degree of impairment of the right hand was associated with phonological and metaphonological skills, and of the left hand with visuospatial and counting performance. Hand skill was related to the ability to perform many daily living manual activities. It is concluded that impairment of hand function, rather than the side of the more affected hand, is related to neuropsychological deficits in children with cerebral palsy.

Activities of Daily Living↗
PubMed2001

Hand preferences in sign-learning students with autistic disorder.

The purpose of the study was fourfold: (a) to document the hand preferences of nonspeaking individuals with autism as they produced signs and nonsign actions; (b) to find out if sign-language proficiency in such individuals is associated with directionality or consistency of signing hand preference; (c) to explore the link between hand preference for signing and standardised measures of cognitive and motor development; (d) to compare the hand preferences (sign and nonsign actions) of such individuals to sign-learning children with normal cognitive functioning. In this study, the hand preferences of 14 nonspeaking students with autistic disorder were determined from videotape records of their sign production and nonsign actions. In their sign production, four students strongly favoured their right hands, four had a distinct left-hand preference, and six did not significantly favour either hand. There was little evidence linking sign-language proficiency, cognitive maturity, or motor development to strongly lateralised signing or handedness in general in these students. Compared with the hand preferences of the children in the two comparison groups, the autistic students were markedly less lateralised with respect to signing, but not nonsign actions.

Journal Article↗
PubMed1997

Psychomotor skills for endoscopic manipulations: differing abilities between right and left-handed individuals.

OBJECTIVE: The objective of this study was to compare the psychomotor aptitudes relevant to endoscopic manipulations between right-handed and left-handed subjects. SUMMARY BACKGROUND DATA: There has been little research on the psychomotor performance in relation to minimal access surgery and there are no psychomotor tests to evaluate aspects of psychomotor abilities relevant to endoscopic manipulations. METHODS: A microprocessor-controlled psychomotor tester was developed for objective evaluation of endoscopic performance. The task involved negotiating ten target holes with a probe under videoscopic imaging. Subjects consisted of two groups of 10 medical students: right- and left-handed. After a prestudy familiarization session, each subject performed two test runs with one hand, followed by two runs with the other hand. These test runs were repeated 1 week later. The outcome measures were the total execution time, force on backplate, angular deviations, error rate, and first-time accuracy. RESULTS: A significant difference in the error rate and first time accuracy was observed between subjects (p < 0.001 and p < 0.001, respectively) and between the dominant and nondominant hands (p < 0.001 and p < 0.025, respectively), with no significant change with practice. Right-handed subjects performed better with either hand in terms of error rate (p < 0.001) and first time accuracy (p < 0.001). Practice improved the execution time (p < 0.001) and the degree of angular deviations (p < 0.02). CONCLUSIONS: Right-handed subjects perform less errors and exhibit better first time accuracy. The parameters that improve with practice reflect the positive effect of training, whereas others, such as errors rate and first time accuracy which do not, reflect innate abilities.

Endoscopy↗
PubMed1991

Proportional myoelectric hand control: an evaluation.

The authors review the principle of proportional myoelectric control, in which the motor voltage of a prosthetic hand varies in direct proportion to the EMG signal, giving the amputee control over speed and force of grip. This type of myoelectric control is contrasted with digital myoelectric control, in which the system is fully on or off, giving the amputee no control over speed of hand opening and closing, and the grip force is increased only by increasing the time of the sustained EMG signal. A survey was conducted of 33 patients wearing the proportional myoelectric hand. Patients rated quickness of opening and closing; control over speed and force; effort required to open and close; and comfort, convenience, and cosmesis of the hand; as well as giving it an overall rating in comparison with their previous terminal device. The ratings were made on a 5-level scale, so that they could be quantified. Patient responses were grouped according to previous experience with a terminal device type: group A: digital myoelectric hand; group B: body-powered terminal device; group C: no terminal device. Differences in group means were compared using Student's t test. Previous digital hand wearers gave significantly higher ratings to the proportionally controlled hand overall, especially for its quickness, control of speed and force, and the effort required to open and close the hand. Former body-powered terminal device wearers rated the proportionally controlled hand significantly better on control over speed and force and on cosmesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2003

Laparoscopic radical nephrectomy: incorporating advantages of hand assisted and standard laparoscopy.

PURPOSE: We present an approach to laparoscopic radical nephrectomy and intact specimen extraction, which incorporates hand assisted and standard laparoscopic techniques. MATERIALS AND METHODS: A refined approach to laparoscopic radical nephrectomy is described and our experience is reviewed. A low, muscle splitting Gibson incision is made just lateral to the rectus muscle and the hand port is inserted. A trocar is placed through the hand port and pneumoperitoneum is established. With the laparoscope in the hand port trocar 2 additional trocars are placed under direct vision. The laparoscope is then repositioned through the middle trocar and standard laparoscopic instruments are used through the other 2 trocars including the one in the hand port. If at any time during the procedure the surgeon believes the hand would be useful or needed, the trocar is removed from the hand port and the hand is inserted. RESULTS: This approach has been applied to 7 patients. Mean estimated blood loss was 200 cc (range 50 to 300) and mean operative time was 276.7 minutes (range 247 to 360). Mean specimen weight was 767 gm. (range 538 to 1,170). Pathologically 6 specimens were renal cell carcinoma (grades 2 to 4) and 1 was oncocytoma. Mean length of hospital stay was 3.71 days (range 2 to 7). There were no major complications. CONCLUSIONS: We believe that this approach enables the surgeon to incorporate the advantages of the hand assisted and standard laparoscopic approaches.

Blood Loss, Surgical↗
PubMed2003

Choroidal vascular reaction to hand-grip stress in subjects with vasospasm and its relevance in glaucoma.

PURPOSE: To assess the impact of vascular dysregulation on choroidal blood flow response to the hand-grip test and the relevance of this response to glaucoma. METHODS: Eighty healthy volunteers underwent a hand-grip test while choroidal blood flow was measured by means of laser Doppler flowmetry. Blood pressure, heart rate, and intraocular pressure (IOP) were monitored. Choroidal blood flow changes were compared between subjects with a positive history of cold hands and control subjects by means of analysis of variance. The relationship of the vascular response to the level of IOP at which progressive damage occurred was analyzed in 21 patients with primary open-angle glaucoma who had progressive damage despite normal or normalized IOP. RESULTS: Blood pressure and heart rate increased and IOP decreased in response to a hand-grip test. Healthy subjects with a positive history of cold hands (n = 36) demonstrated a decrease in choroidal blood flow during the hand-grip test (mean +/- SD: 13.5 +/- 5.8, 12.2 +/- 6.8, and 13.4 +/- 6.9 AU, at baseline, during the test, and 3 minutes after release, respectively), whereas control subjects (n = 44) demonstrated an inverse (12.5 +/- 8.3, 13.7 +/- 9.4, and 11.9 +/- 7.1 AU, respectively) response pattern (P = 0.039). Glaucoma patients with a decrease of at least 10% in choroidal blood flow during the hand-grip test had lower IOP (14.67 +/- 3.83 and 13.50 +/- 2.59 mm Hg in the right and the left eyes, respectively) compared (P = 0.032) with those without such a decrease (16.54 +/- 3.85 and 16.92 +/- 2.95 mm Hg in the right and the left eyes, respectively). CONCLUSIONS: A hand-grip test elicits a different blood flow response in subjects with vasospasm compared with control subjects. Damage by glaucoma in patients with a decrease in choroidal blood flow during a hand-grip test may progress at a relatively lower IOP.

Adult↗
PubMed1999

Superior temporal gyrus volume abnormalities and thought disorder in left-handed schizophrenic men.

OBJECTIVE: Studies of schizophrenia have not clearly defined handedness as a differentiating variable. Moreover, the relationship between thought disorder and anatomical anomalies has not been studied extensively in left-handed schizophrenic men. The twofold purpose of this study was to investigate gray matter volumes in the superior temporal gyrus of the temporal lobe (left and right hemispheres) in left-handed schizophrenic men and left-handed comparison men, in order to determine whether thought disorder in the left-handed schizophrenic men correlated with tissue volume abnormalities. METHOD: Left-handed male patients (N = 8) with DSM-III-R diagnoses of schizophrenia were compared with left-handed comparison men (N = 10) matched for age, socioeconomic status, and IQ. Magnetic resonance imaging (MRI) with a 1.5-T magnet was used to obtain scans, which consisted of contiguous 1.5-mm slices of the whole brain. MRI analyses (as previously defined by the authors) included the anterior, posterior, and total superior temporal gyrus in both the left and right hemispheres. RESULTS: There were three significant findings regarding the left-handed schizophrenic men: 1) bilaterally smaller gray matter volumes in the posterior superior temporal gyrus (16% smaller on the right, 15% smaller on the left); 2) a smaller volume on the right side of the total superior temporal gyrus; and 3) a positive correlation between thought disorder and tissue volume in the right anterior superior temporal gyrus. CONCLUSIONS: These results suggest that expression of brain pathology differs between left-handed and right-handed schizophrenic men and that the pathology is related to cognitive disturbance.

Cognition Disorders↗
PubMed2006

Hand, an evolutionarily conserved bHLH transcription factor required for Drosophila cardiogenesis and hematopoiesis.

The Hand gene family encodes highly conserved basic helix-loop-helix (bHLH) transcription factors that play crucial roles in cardiac and vascular development in vertebrates. In Drosophila, a single Hand gene is expressed in the three major cell types that comprise the circulatory system: cardioblasts, pericardial nephrocytes and lymph gland hematopoietic progenitors, but its function has not been determined. Here we show that Drosophila Hand functions as a potent transcriptional activator, and converting it into a repressor blocks heart and lymph gland formation. Disruption of Hand function by homologous recombination also results in profound cardiac defects that include hypoplastic myocardium and a deficiency of pericardial and lymph gland hematopoietic cells, accompanied by cardiac apoptosis. Targeted expression of Hand in the heart completely rescued the lethality of Hand mutants, and cardiac expression of a human HAND gene, or the caspase inhibitor P35, partially rescued the cardiac and lymph gland phenotypes. These findings demonstrate evolutionarily conserved functions of HAND transcription factors in Drosophila and mammalian cardiogenesis, and reveal a previously unrecognized requirement of Hand genes in hematopoiesis.

Animals↗
PubMed1995

An analysis of the reinforcing properties of hand mouthing.

Hand mouthing often has been described as a stereotypic response that is maintained by nonsocial (automatic) reinforcement; however, data supporting this conclusion can be found in relatively few studies. This series of studies presents an experimental analysis of conditions associated with the maintenance of hand mouthing. In Experiment 1, a functional analysis was conducted for 12 individuals who engaged in chronic hand mouthing, to determine whether the behavior is usually maintained independent of social contingencies. Results obtained for 10 subjects were consistent with an automatic reinforcement hypothesis; the remaining 2 subjects' hand mouthing was maintained by social-positive reinforcement. Based on these results, Experiment 2 was designed to identify the specific reinforcing properties of hand mouthing. Each of 4 subjects was provided with a toy that substituted for hand mouthing, and preference for a specific topography of toy manipulation (hand-toy contact or mouth-toy contact) was measured. Results indicated that hand stimulation was the predominant reinforcer for all subjects. Experiment 3 provided an extension of Experiment 2 in that the same responses were measured across a variety of toys presented to each of 5 subjects. Results again indicated that hand stimulation was the predominant reinforcer for all subjects. Implications of these results are discussed with relevance to treatment.

Adult↗
PubMed1999

The association between switching hand preference and the declining prevalence of left-handedness with age.

OBJECTIVES: This study determined the prevalence of left-handedness and of switching hand preference among innately left-handed subjects. METHODS: Subjects of Swiss nationality (n = 1692), participating in a population-based survey in Geneva, Switzerland, completed a questionnaire on innate hand preference and current hand preference for writing. RESULTS: From 35 to 44 years of age to 65 to 74 years of age, the prevalence of innate left-handedness declined from 11.9% to 6.2% (trend P = .007). In these same age groups, the proportion of innately left-handed subjects who switched to the right hand for writing increased from 26.6% to 88.9% (trend P = .0001). CONCLUSIONS: Across generations, we found an increase in the prevalence of switching hand preference among innately left-handed subjects. This phenomenon could be explained by social and parental pressure to use the right hand.

Adult↗
PubMed2000

A longitudinal study of hand preference in chimpanzees (Pan troglodytes).

A longitudinal study of hand preferences was assessed in a sample of 53 captive chimpanzees. Four measures of laterality assessed during the first 3 months of life were correlated with three measures of hand preferences assessed when the subjects were between 2 and 5 years of age. In addition, the effect of rearing environment on juvenile hand preferences was assessed in a larger sample of 83 chimpanzees. Overall, some early asymmetries were predictive of juvenile hand preferences, notably head orientation and hand-to-hand activities, and a defensive grasping response. No significant effects of rearing on hand preferences were found but males were more right-handed than females for two of the three juvenile measures. The results are discussed within the context of different developmental models of hand preference in humans.

Animals↗