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PubMed2000

Critical determinants of Ca(2+)-dependent inactivation within an EF-hand motif of L-type Ca(2+) channels.

L-type (alpha(1C)) calcium channels inactivate rapidly in response to localized elevation of intracellular Ca(2+), providing negative Ca(2+) feedback in a diverse array of biological contexts. The dominant Ca(2+) sensor for such Ca(2+)-dependent inactivation has recently been identified as calmodulin, which appears to be constitutively tethered to the channel complex. This Ca(2+) sensor induces channel inactivation by Ca(2+)-dependent CaM binding to an IQ-like motif situated on the carboxyl tail of alpha(1C). Apart from the IQ region, another crucial site for Ca(2+) inactivation appears to be a consensus Ca(2+)-binding, EF-hand motif, located approximately 100 amino acids upstream on the carboxyl terminus. However, the importance of this EF-hand motif for channel inactivation has become controversial since the original report from our lab implicating a critical role for this domain. Here, we demonstrate not only that the consensus EF hand is essential for Ca(2+) inactivation, but that a four-amino acid cluster (VVTL) within the F helix of the EF-hand motif is itself essential for Ca(2+) inactivation. Mutating these amino acids to their counterparts in non-inactivating alpha(1E) calcium channels (MYEM) almost completely ablates Ca(2+) inactivation. In fact, only a single amino acid change of the second valine within this cluster to tyrosine (V1548Y) supports much of the functional knockout. However, mutations of presumed Ca(2+)-coordinating residues in the consensus EF hand reduce Ca(2+) inactivation by only approximately 2-fold, fitting poorly with the EF hand serving as a contributory inactivation Ca(2+) sensor, in which Ca(2+) binds according to a classic mechanism. We therefore suggest that while CaM serves as Ca(2+) sensor for inactivation, the EF-hand motif of alpha(1C) may support the transduction of Ca(2+)-CaM binding into channel inactivation. The proposed transduction role for the consensus EF hand is compatible with the detailed Ca(2+)-inactivation properties of wild-type and mutant V1548Y channels, as gauged by a novel inactivation model incorporating multivalent Ca(2+) binding of CaM.

Amino Acid Motifs↗

PubMed1998

Methodology of motor skill and laterality: new test of hand preference in Macaca nemestrina.

Ten female pig-tailed macaques (Macaca nemestrina) were tested for hand preference and hand skill (i.e., speed of performance and error rate). The experimental task was naturalistic, calling for adaptive manual skills and fine manipulation: the monkeys had to remove small food rewards embedded in a vertical array, and precision opposition of thumb and forefinger was needed to extract each pellet. Each monkey was tested 10 times on 10 different days. The results indicated individual hand preference rather than population-level handedness; however, a tendency toward right predominance was found. The results on hand skill showed a relation between error rate and hand preference, as the preferred hand made fewer errors. A different and unexpected finding was obtained when skill was evaluated in terms of speed of performance: in adult subjects the left hand was quicker than the right. Therefore, different kinds of skill showed different patterns in relation to hand preference.

Animals↗

PubMed1992

Five tests of hand skill.

Four group tests of hand skill, square marking (SQUARES), dotting between targets (DOTS), line drawing between targets (LINES) and punching holes through targets (HOLES), were given to samples of undergraduates and schoolchildren, most of whom were also tested individually on a peg moving task (PEGS). Findings for PEGS were shown to be comparable to those of previous samples. Each new task was compared with PEGS for a standard measure of hand skill asymmetry (R-L%) using 4 criteria of comparison. For 3 criteria there was good agreement: correlations were statistically significant, hand preference subgroups were similar for rank order and the extent of asymmetry was more strongly associated with left hand scores than with right hand scores. This last finding was true for all of 12 comparisons for differing tests and samples, indicating that the finding is unlikely to be an artefact of score transformations as suggested by Bishop (1990a, 1990b). The fourth criterion of comparison, the distribution of R-L% scores, differed between the tasks. All of the new tasks found larger differences between the hands than PEGS. Whereas the shape of the distribution was unimodal for PEGS, as in previous studies, the distributions for DOTS and HOLES were clearly bimodal. Possible reasons for the larger between hand differences for some tasks are considered. It is suggested that the main difference between PEGS (and also to a lesser extent LINES) in comparison with DOTS and HOLES lies in the demand characteristics of the testing situation. Tasks which merely invite subjects to mark as many targets as possible in a unit of time may underestimate the skill of the nonpreferred hand.

Adolescent↗

PubMed1978

Differential finger movements and hand preference.

In an attempt to replicate a study by Kimura and Vanderwolf (1970), normal left-handed and right-handed subjects were asked to flex a single finger or pairs of fingers at the middle joint. Both hands were found to be equally proficient at this task and no differences between right- and left-handers were found. When left-handers were divided into inverters and non-inverters according to hand-writing posture, a left hand superiority was a found for the right-handed and the left-inverted subjects, while the left-non-inverters showed a right hand superiority. Paired finger flexion was found to be more useful in discriminating between the handedness groups. These findings support the idea that the neural mechanism for hand preference is not based on an asymmetry in the control of fine movement. They also support the theory that two separate groups of left-handers exist, and the they can be differentiated by their handwriting postures.

Adolescent↗

PubMed1984

Is there a "best hand" for braille?

Two experiments were conducted on lateral differences in Braille tasks with predominantly right-handed blind children. The hypothesis that hand advantages change with absolute proficiency levels was not supported for either letter discrimination, letter naming or word reading. Experiment 1 provided support for the hypothesis that hand advantages depend on a combination of tasks demands and individual strategy preferences associated with relative proficiency or retardation. Retarded readers were significantly faster with the left hand in letter discrimination, and adequate readers were significantly faster with the right hand in letter naming. Experiment 2 showed that for tasks which demanded lateral movements, two-handed reading was superior to reading by either hand alone, irrespective of absolute or relative reading proficiency. It was argued that there is no "best hand" as such for Braille, but that lateral advantages depend on specific interrelations between task demands, individual preferences and reading habits.

Adolescent↗

PubMed2002

Laparoscopic hand assisted radical cystectomy with ileal conduit urinary diversion.

PURPOSE: Hand assisted laparoscopy was originally described in the early 1990s. Since then many studies have shown that hand assisted techniques have the same advantages of laparoscopy including decreased need for postoperative narcotics and rapid return to routine activities. Laparoscopic techniques are advancing rapidly and intracorporeal laparoscopic cystectomy is reported. To our knowledge we report the first case of hand assisted, laparoscopic radical cystectomy with ileal conduit urinary diversion. MATERIALS AND METHODS: A 68-year-old male with rapidly recurring grade III transitional cell carcinoma elected to undergo hand assisted radical cystectomy. We performed a radical cystectomy with bilateral pelvic lymph node dissection removing the specimen through the hand port site. The ileal loop urinary diversion was constructed by pulling the small bowel through the hand port incision. We made another separate hole for the stoma and a drain was placed through a port site. The incisions were closed in the standard fashion. RESULTS: Operative time was 7 hours with 750 cc of blood loss and no complications. All surgical margins were negative. The patient did well and was discharged from the hospital on postoperative day 7 with return to normal activity without limitations at 4 weeks. CONCLUSIONS: To our knowledge this is the first reported case of hand assisted laparoscopic radical cystectomy with ileal loop diversion. Hand assistance facilitated this technically demanding surgery resulting in a good outcome without significant added operative time.

Aged↗

PubMed2002

Hand and gender differences in the organization of aiming in 5-year-old children.

The aim of the present study was to analyze the organization of aiming movements in right-handed children aged 5 years, depending on gender and hand used to perform the task. We first tested the hypothesis that aiming movements are predominantly organized in a feed-forward manner before the age of six. Using a direction pre-cueing protocol, we analyzed the effect of gender and hand used to perform the task on reaction time (RT), movement time (MT), spatial accuracy (SA) and acceleration profiles (APs) in children aged 5 years. Differences in RT between the uncued and pre-cued conditions suggest that the direction is actually specified prior to the execution of the movement at the age of five. However, the results also show significant hand and gender effects on MTs, spatial error and APs. Specifically, in girls, MT and kinematics profiles vary as a function of hand and target localization, whereas this is not the case in boys. In addition, SA is lower when aiming with the non-dominant hand in boys, but not in girls. These results suggest that multiple movement strategies are already available to the child at the age of five. Girls appear to be able to change movement strategy as a function of the constraints of the task, resulting in a stability of spatial accuracy (SA). On the contrary, the functional advantage of the right hand on MT and SA generally reported in right-handed males is not present in the boys at the age of five.

Biomechanical Phenomena↗

PubMed2000

The effect of situational factors on hand preferences for feeding in 177 captive chimpanzees (Pan troglodytes).

This study examined the effect of situational factors on hand use for feeding in a sample of captive chimpanzees. Lateral bias in hand use was tested in biased and unbiased testing circumstances to assess strength and consistency in hand preference. For both unbiased and biased testing conditions, population-level right hand preferences were found for the sample. In the biased condition, subjects were more likely to overcome positional factors in order to feed with their right hand contrasted with the left. Overall, hand use in the biased and unbiased testing conditions was significantly positively correlated. In terms of strength of hand use, juveniles were found to be less lateralized than sub-adults and adults. Moreover, juvenile females were found to be more lateralized than juvenile males. Taken together, the data suggest that chimpanzee hand preferences for feeding are not constrained by situational factors and are relatively consistent in biased and unbiased testing conditions.

Aging↗

PubMed2000

The Krukenberg procedure: a surgical option for the treatment of double hand amputees in Sierra Leone.

BACKGROUND: For the past 9 years, Sierra Leone has struggled with a cruel civil war in which the civilian population has been the principal target. The International Committee of the Red Cross established a surgical mission in Netland Hospital, Freetown, and during this surgical mission, we treated crippled individuals who had had one or both hands amputated. We assessed the benefit of the Krukenberg procedure to restore manual dexterity in this group. In this operation, radius and ulna are separated and a pincer-like grasp is created. METHODS: From July 15, 1998, to Sept 9, 1998, we carried out the Krukenberg procedure on a group of double and single hand amputees. The main target group was double hand amputees, however, the procedure was initially done on three single hand amputees to assess the functional result. Between the original trauma and the operation, there had been an interval of 3 months or longer in all patients. Patients were followed up for 3 months after the procedure to assess gripping strength and self-sufficiency (feeding, personal hygiene, dressing, and manual dexterity). FINDINGS: 15 Krukenberg procedures were done on 11 patients: eight men and three women (mean age 42 years). Three had single hand amputation and eight had double hand amputation. In only two patients had sufficient time passed for the stumps to heal. Of ten patients who were followed up at 3 months, all could eat and drink by themselves. The simple dressing test was passed by all patients and 75% of the patients had recovered some dexterity. INTERPRETATION: The Krukenberg procedure is a surgical option to achieve some manual dexterity in double hand amputees, where resources for sophisticated hand prostheses are lacking.

Activities of Daily Living↗

PubMed2003

Hand differences in pegboard performance through development.

Handedness is often measured by comparing the relative performance of the two hands on a given task, such as peg moving. Studies of the development of manual skill have typically found that the difference between the hands for a peg-moving task does not fluctuate with age. The current study was conducted to examine age-related changes in manual performance, on the standard Annett pegboard. Ninety-eight right-handed individuals ranging in age from 5 to 24 performed three trials on the pegboard with each hand. Performance with each hand was reflected in movement time and as a laterality quotient. Analyses revealed a right-hand advantage in performance which was larger in the younger than the older participants. The smaller hand difference in the older participants appeared due to greater changes in performance with the non-preferred hand as a function of age.

Adult↗

PubMed2002

Teaching hand placement for chest compression--a simpler technique.

BACKGROUND: Simplification of the techniques and teaching of resuscitation are advocated as ways of improving skill acquisition and retention. A simple method for teaching hand placement for chest compression has been described but not validated. OBJECTIVE: The objective of this study was to determine if instructing trainees simply to place their hands in the centre of the chest results in better initial and retained accuracy of hand placement than the usual method of first identifying anatomical landmarks. METHODS: Volunteers received instruction in basic CPR, being taught hand placement either by the standard method (33 subjects) or the simplified method (32 subjects). They were tested for accuracy of hand position before training, immediately afterwards and 6 weeks later. RESULTS: After training both groups showed an improvement in accuracy of hand placement but there was no significant difference in the degree of improvement between the groups (P=0.345), nor in the level of accuracy achieved (P=0.178). Six weeks after training, the Standard Group demonstrated a statistically significant deterioration in accuracy (P=0.001), whereas the Simple Group did not (P=0.561). By this time, however, there was no longer any difference in accuracy of hand placement for either group compared with before training (Standard Group P=0.912; Simple Group P=0.140). On the positive side, the Simple Group took significantly less time (2.90 s) than the Standard Group (4.43 s) to change from ventilation to chest compression (P=0.000003). CONCLUSIONS: Simplifying the teaching of correct hand placement for chest compression does not appear to lead to improvement in acquisition or retention of the skill. However, it does result in a significant reduction in the length of the pauses between ventilation and chest compression.

Adult↗

PubMed2000

Human motor development and hand laterality: a kinematic analysis of drawing movements.

This study examines the developmental profiles of basic 'open-loop' drawing movements on the non-dominant hand (ND) in comparison with the dominant hand (D). Fifty-three right-handed children aged 7-14 years and 15 adults aged 27-43 years were examined. Each subject drew lines and circles of different sizes at maximum velocity with a pressure-sensitive pen on a computer graphics tablet. Small lines were drawn at 90 degrees to the axis of the forearm (lines using wrist movements (LWM)) and along the axis of the forearm (lines using elbow movements (LEM)). Larger lines were drawn at 90 degrees to the axis of the forearm (LEM). At both extremities, the movement frequencies of the proximally generated drawing movements increased in a parallel fashion at different levels. In LWM, the right-left-differences (RLD) were high in 7- to 8-year-old children; until puberty, the ND hand reached almost the performance of the D hand. In contrast, the RLD of the LFM increased at the same time. As adulthood approaches, frequencies of all drawings increased further while the LWM on the ND side remained stable. In adults, there were similar RLD for all line drawings involving predominantly flexion and extension movements. When drawing circles, the RLD were highest, though stable in all age groups. Hand laterality of pen use changes over time; these changes are dependent on complexity (combined/sequential cf. flexion-extension muscle activation) and on topography (proximal cf. distal movements). Distinct developmental profiles of motoneuronal populations of the cortex may be responsible for the distinct hand laterality effects and the decreasing variability of motor patterns. The drawing abilities and developmental changes on the untrained ND hand indicate that effector-specific practice plays a minor role.

Adolescent↗

PubMed1997

Computerized data collection in the operating room during coronary artery bypass surgery: a comparison to the hand-written anesthesia record.

OBJECTIVE: To investigate variability between hand-written and computerized anesthesia records and evaluate any associated bias. DESIGN AND MEASUREMENTS: A computer system that was used to collect intraoperative data for a study of hemodynamic management during coronary artery bypass graft surgery is described. The system collected and recorded hemodynamic data automatically downloaded from the anesthesia monitor as well as surgical events and drug administration data entered through menu options. The system then combined, summarized, and graphed the data as well as formatted it for export to a commercially available database program. In a sample of 14 patients, blood pressure data collected by the computer system was compared with the blood pressure data charted in the hand-written anesthesia record. MAIN RESULTS: Although general linear models controlling for within-patient variation and randomization assignment for mean arterial pressure range on cardiopulmonary bypass showed a significant relationship; low R2 values indicated that much of the variability could not be explained and that there was, therefore, poor agreement between the two records. Furthermore, a systematic bias in the hand-written anesthesia record was found when the computer system record was compared with the hand-written record and to the difference of the two records, so that extremes seen in the computer system record tended to be minimized in the hand-written anesthesia record. CONCLUSIONS: Because of the lack of explained variability between the computer system and hand-written anesthesia records and the bias in the hand-written anesthesia record, the hand-written anesthesia record should not be relied on as a source of accurate data for research purposes.

Anesthesia↗

PubMed2001

Hand preference and motor functioning in children with autism.

This study examined three theories that have been proposed to explain the high rates of ambiguous hand preference in young children with autism. Twenty children with autism were matched with 20 children with developmental delays and 20 normally developing children. The groups were compared on measures of hand preference and motor skills. Results indicated that the lack of development of a hand preference in children with autism was not a direct function of their cognitive delay, as the children with developmental delays showed a dissimilar pattern of hand preference. The lack of a definite hand preference in the children with autism was also not due to a lack of motor skill development, as the children with developmental delays displayed similar levels of gross and fine motor skills without the accompanying lack of a definite hand preference. The finding that children with autism with a definite hand preference displayed better performance on motor, language, and cognitive tasks than children with autism who did not display a definite hand preference, however, provided support for the bilateral brain dysfunction hypothesis.

Autistic Disorder↗

PubMed1998

Bipedal posture and hand preference in humans and other primates.

Hand preference for quadrupedal and bipedal reaching in humans and rhesus macaques (Macaca mulatta) was examined, and the data were compared with postural reaching data that have been reported for 8 other primate species. Population-level biases were found toward use of the right hand for quadrupedal and bipedal reaching in humans and use of the left hand for quadrupedal reaching in rhesus macaques. Rhesus macaques showed a significant shift toward greater use of the right hand for bipedal vs. quadrupedal reaching. Comparisons with other species showed significant variance in the direction and strength of hand preference across reaching postures. The study noted right-hand biases for bipedal reaching in humans, great apes, and tufted capuchins and shifts toward greater use of the right hand for bipedal vs. quadrupedal reaching in great apes, tufted capuchins, and rhesus macaques. These results suggest that posture alters both the direction and strength of primate hand preference and that bipedalism may have facilitated species-typical right-handedness in humans.

Adult↗

PubMed1993

Are age trends in adult hand preference best explained by developmental shifts or generational differences?

Hand use in the performance of six everyday activities was analyzed as a function of age in a sample of 654 adults. An unskilled grasping tasks showed the largest shift toward consistent right-handedness as a function of age; skilled manipulation tasks, such as writing, exhibited weaker age-related trends. Analysis of individual preference patterns showed decreases in mixed right hand use (defined as a right-hander who occasionally uses the left hand) and increases in consistent right hand use in older adults. There was also a weaker age-related reduction in mixed left hand use but the numbers of consistent left-handers remained a small, constant percentage of the sample across all age groups. These results are congruent with the predictions of two developmental hypotheses offered to explain trends in adult hand preference. These are, first, a postulated age trend toward hand preference consistency and, second, a practice effect related to an environment arranged to favor right hand use.

Adolescent↗

PubMed2006

Phacoemulsification with nondominant hand.

PURPOSE: Evaluation of on axis phacoemulsification surgery through temporal incision using nondominant hand with surgeon sitting at the head end, inpatients with against-the-rule astigmatism. METHODS: Eighty eyes of 80 patients who underwent phacoemulsification through a temporal clear corneal tunnel for age-related cataract and against-the-rule astigmatism were enrolled and divided into four equal groups. In Group 1A, the surgeon was sitting at the head end for the left eye performing surgery with the left hand (nondominant hand). In group 1B, the surgeon was seated at the temporal side and surgery was performed in the left eye with dominant right hand. In group 2A, the surgeon was sitting at the head end for the right eye and performed surgery holding the phacoemulsification hand piece in his right hand. In group 2B, the surgeon sat on the temporal side of the right eye and performed phacoemulsification with his right hand. The patients were followed up on day 7, 1 month, and 3 months. Parameters evaluated included average phaco power, effective phaco time, uncorrected and best-corrected visual acuity, keratometry, intraocular pressure, surgically induced astigmatism, pachymetry, and endothelial cell counts. RESULTS: The phaco time and phaco power among the four groups were comparable (phaco time: P=0.368; phaco power: P=0.294). The four groups were also comparable on parameters like surgically induced astigmatism (P=0.674), change in postoperative keratometric astigmatism (P=0.584), endothelial cell loss (0.921), change in ultrasonic pachymetry (P=0.476), and intraocular pressure (P=0.942). No intraoperative or postoperative complications were observed in any of the groups. The mean uncorrected visual acuity at 3 months in group 1 was 0.723+/-0.21; in group 2 it was 0.756+/-0.21; in group 3 it was 0.748+/-0.22, and in group 4 it was 0.732+/-0.23. The best-corrected visual acuity was 0.96+/-0.10, 0.97+/-0.11, 0.95+/-0.13, and 0.96+/-0.10 in the four groups at 3 months. CONCLUSION: Phacoemulsification surgery can be successfully performed with nondominant hand with a good surgical outcome. The technique gives an alternative approach where surgeon does not have to shift the position to perform on-axis phacoemulsification.

Aged↗

PubMed1999

Single-handed practices--their contribution to an undergraduate teaching network in the first year of the new curriculum.

OBJECTIVES: The new curriculum at King's College School of Medicine and Dentistry, which commenced in September 1996, requires all medical undergraduates to have a general practice placement throughout the 5 years of their medical education. DESIGN: This paper discusses recruitment, training and support of teaching practices for the new curriculum, reviews the distribution of single-handed general practices in the network and, via a selection of monitoring and evaluation procedures, discusses the implications of a policy which is inclusive of single-handed practices. The findings relate to the experience of the first semester of the first year of the new curriculum. It also examines the contributions that single-handed practices have made to the teaching network and the kind of support needed, if single-handed practices are to continue to contribute to the King's teaching network. SETTING: King's College School of Medicine and Dentistry. SUBJECTS: Medical undergraduates. RESULTS: The findings of this paper revealed that over a third of general practice provision is via single-handed practices in South-east London. Within the undergraduate teaching network, 10% of practices are single-handed. Students are welcomed and receive a learning experience comparable to those students in larger practices. Attendance at training events has proved difficult for some of these tutors, but the extra input from the department, in order to address this deficit, has not been onerous. Indeed, single-handed practices have not been unique with regard to difficulties in attendance at training events. CONCLUSIONS: The study concludes that single-handed practices can make satisfactory provision for undergraduates in the new curriculum and there is no evidence from this study to suggest otherwise.

Curriculum↗