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PubMed1977

Hand preference in autistic children and their parents.

Hand preference was tested in groups of between 40 and 50 autistic children and in sex-, age-, and ability-matched controls. Results were also compared with existing findings on normal children. Small differences occurred between the groups in the directions which would be predicted on the assumption that mental subnormality is associated with delayed development of normal patterns of handedness, and on the hypothesis that autistic children as a group will show a persistent slightly increased tendency to use the left hand. Parents of the autistic group were also assessed for handedness. Contrary to the prediction of slightly increased sinistrality in this group of subjects, some indication of increased dextrality occurred. Results were discussed in relation to possible genetic factors in the etiology of autism.

Adolescent↗
PubMed2004

Hand workload and the metacarpal cortical index. a study of middle-aged teachers and dentists.

We studied load-related predictors (handedness, occupation and workload history) of cortical bone mass as estimated by the metacarpal cortical index (MCI). After being randomly selected from trade-union registers, 295 female dentists and 248 teachers, aged 45-63 years (mean 54 years), participated in the study. The MCI was defined from the second metacarpal of both hands by analogue radiographs. Data regarding anthropometric measures, handedness, occupational exposure, number of pregnancies, hormonal therapy and contraceptive use, the presence of chronic diseases, dietary factors, smoking and leisure time physical activity were collected by questionnaire. Weight was measured. The dentists' workload was assessed in detail in 10-year periods. Multivariate methods were used in the statistical analysis. The metacarpal index averaged 0.62 in the right hand and 0.61 in the left hand (P = 0.02) among the right-handed subjects, while no differences by hand were observed among the left-handed or mixed-handed. The MCI of the teachers and dentists did not differ from each other, when we controlled for potential confounders. The MCI decreased similarly by age in both occupational groups. Among the dentists, workload history was inversely associated with the MCI in multivariate analyses by age group. Computer use was a positive predictor for MCI among dentists aged 55-63 years. Occupational factors seem to have contradictory effects on the MCI. Too heavy or one-sided manual work may be deleterious for cortical bone mass.

Age Factors↗
PubMed2003

Construction of a backcross progeny collection of dextral and sinistral individuals of a freshwater gastropod, Lymnaea stagnalis.

The handedness of gastropods is genetically determined, but the molecular nature of the gene responsible remains unknown. In order to identify the gene by a forward genetic approach, we carried out backcross breeding between dextral and sinistral inbred strains of a freshwater gastropod, Lymnaea stagnalis, cultivated in the laboratory. We used the dextral animals as donor "fathers" and the sinistral animals as recurrent "mothers". Each of the backcross progeny obtained was typed for the chirality of the next generation offspring oviposited by it, because the genotype for the handedness locus emerges as filial chirality. We constructed a collection of DNA and RNA specimens that included about 200 of the backcross F(2) progeny. Success in breeding was confirmed by the expected inheritance behavior of strain-specific DNA markers in the progeny.

Animals↗
PubMed2003

Laparoscopic cholecystectomy in situs inversus totalis: The importance of being left-handed.

Since laparoscopic cholecystectomy has become the standard procedure for the treatment of gallstone disease, several cases have been reported in patients with situs inversus. These cases require more technically demanding procedures due to the symmetrical disposition of the anatomy. Thus, handedness could influence the performance of these operations. The two of us (L.M.O.) and (J.M.B.), a right-handed and a left-handed surgeon, respectively, placed the instruments in reverse mode from that used in orthotopic patients. The right-handed surgeon felt more impairment when dissecting with his left hand and decided to cross the instruments within the abdomen. The left-handed surgeon was able to alternate the performance of the dissection maneuvers between the right and left hands. Surgical procedures are apparently designed for right-handed surgeons and can be approached by the left-handed in alternative ways. In fact, the accommodation of laparoscopic cholecystectomy to left-handedness has been described in the literature. The rare opportunity to operate in a symmetrical way allows the right-handed surgeon to understand the absence of comfort and ergonomy often experienced by left-handed colleagues.

Aged↗
PubMed2006

Twisted growth and organization of cortical microtubules.

In plants, directional cell expansion greatly contributes to the final shape of mature cells, and thus to organ architecture. A particularly interesting mode of cell expansion is helical growth in which the growth axis is continuously tilted either to the right or to the left as the cell grows. Fixed handedness of helical growth raises fundamental questions on the possible origin of left-right asymmetry. Twisting mutants of Arabidopsis thaliana offer unique opportunities to study the cellular basis of helical growth. Most of the twisting mutants with fixed handedness have been shown to have defects in microtubule functions, whereas mutants that twist in non-fixed directions appear to be defective in auxin response or transport. Good correlations have been found between the tilted growth direction and alignment of cortical microtubule arrays in twisting mutants with compromised microtubule functions. The present challenge is to understand how particular array patterns are organized during progression of the interphase in rapidly expanding cells. Molecular and cell biological studies on twisting mutants will lead to better understanding on how wild-type plant cells utilize the microtubule cytoskeleton to initiate and rigorously maintain straight growth.

Microtubules↗
PubMed2006

Hand preferences in captive orangutans (Pongo pygmaeus).

The strength of the evidence for population-level handedness in the great apes is a topic of considerable debate, yet there have been few studies of handedness in orangutans. We conducted a study of manual lateralization in a captive group of eight orangutans (Pongo pygmaeus) ranking the degrees of manual preference according to a defined framework. We analyzed five behavioral patterns: eat (one- and two-handed), make/modify tool, oral tool-use, and manual tool-use. Although some individuals showed significant manual preferences for one or more tasks, at the group-level both one-handed and two-handed eating, oral tool-use, and make/modify tool were ranked at level 1 (unlateralized). Manual tool-use was ranked at level 2, with four subjects demonstrating significant hand preferences, but no group-level bias to the right or left. Four subjects also showed hand specialization to the right or left across several tasks. These results are consistent with most previous studies of manual preference in orangutans. The emergence of manual lateralization in orangutans may relate to more complex manipulative tasks. We hypothesize that more challenging manual tasks elicit stronger hand preferences.

Animals↗
PubMed2005

Affecting factors in second language learning.

The present study investigated the influence of sex, handedness, level in second language (L2) and Faculty choice on the performance of phonological, syntactical and semantic tasks in L2. Level in L2 and sex were the most affecting factors. Subjects who achieved higher scores on L2 tasks had strong second language aptitude skills since they were those who had obtained a professional degree in the second language. Females performed better than males in syntax and semantics which is explained by the general female superiority on verbal tasks based on differences in hemispheric specialization for language functions between the sexes. Handedness and Faculty choice on the part of the participants had an impact on our results but only when combined with other factors.

Cognition↗
PubMed1986

A controlled magnetic resonance imaging study of corpus callosum thickness in schizophrenia.

Two previous postmortem studies reported an increased thickness of the corpus callosum in schizophrenic patients compared to psychiatric controls. We report an in vivo study of the corpus callosum in schizophrenic patients (n = 38) and healthy controls (n = 41) using magnetic resonance (MR) brain imaging. A significant increase in mean callosal thickness was found in the middle and anterior, but not the posterior, parts of the callosal body. However, when the patients and controls were compared by gender and handedness, schizophrenic men were found not to differ from control men in callosal thickness, regardless of handedness, whereas schizophrenic women were found to have a highly significant increase in callosal middle and anterior thickness compared to control women. The data suggest that increased callosal thickness in schizophrenia is gender related, a factor that is not considered by postmortem studies. The implications of increased callosal dimensions in female schizophrenics are discussed.

Adult↗
PubMed1989

Hand preference in psychotic twins.

In an attempt to replicate the influential study of Boklage (1977), hand preference for writing was examined in a new series of 30 monozygotic (MZ) and 30 dizygotic (DZ) twin pairs in whom the proband had suffered a functional psychosis. In contrast to the original report, no increased rate of left-handedness was found in MZ compared to DZ twins, or psychotic compared with nonpsychotic twins. In particular, no relationship between within-pair left-handedness and discordance for psychosis emerged. Possible reasons for the disagreement between the two studies are examined.

Adult↗
PubMed1991

Patterns of manual dominance in patients with neuroleptic-induced movement disorders.

To explore the association between patterns of manual dominance and extrapyramidal symptoms we examined 32 chronic schizophrenic inpatients at Camarillo State Hospital for signs of tardive dyskinesia (TD) and neuroleptic-induced parkinsonism (NIP) using clinical rating scales (Abnormal Involuntary Movement Scale and Columbia Unified Parkinsons Disease Rating Scale) and specialized electromechanical instruments. Manual dominance was assessed using an eight-item hand preference demonstration test. Patients were divided into dextral (consistent use of right hand) and nondextral (any use of the left hand) groups. Dextrals showed a higher prevalence of TD than nondextrals on clinical rating measures (p less than 0.01). Orofacial ultrasound measures of TD revealed a similar association between TD and handedness. The two handedness groups did not differ on either the clinical or electromechanical measures of NIP. Interestingly, 28 of the 32 patients showed greater left than right facial movement. It is hypothesized that patients with more standard patterns of manual dominance may be at higher risk for TD than those with atypical patterns.

Adult↗
PubMed1992

The prevalence of autoantibodies among right and left handed schizophrenic patients and control subjects.

Sera from schizophrenic patients (n = 186) and healthy control subjects (n = 346) were tested for the presence of seven common autoantibodies by standard immunological methods. The association between handedness and autoantibodies was tested in a multi-way contingency table using a log-linear model. For men, but not women, nondextrals (patients and controls) were twice as likely to test positive for autoantibodies than dextrals (p = 0.0002). Although more women (33%) than men (24%) tested positive for autoantibodies, handedness was not a distinguishing factor among women. These data suggest that sinistrality and gender are associated with autoantibodies in a subgroup of schizophrenic patients and healthy control subjects.

Adult↗
PubMed1995

The relationship of minor physical anomalies and other putative indices of developmental disturbance in schizophrenia to abnormalities of cerebral structure on magnetic resonance imaging.

Minor physical anomalies, together with obstetric complications, family history, and handedness status, were assessed to explore putative neurodevelopmental disturbance(s) in patients with schizophrenia whose cerebral structure had been examined previously by magnetic resonance imaging. Minor physical anomalies were related to negative symptoms in males and to premorbid intellectual function in females, but not to ventricular volume; however, three patients with evident neurodevelopmental anomalies of the ventricular system showed prominent minor physical anomalies. In exploratory analyses, obstetric complications were associated with left ventricular asymmetry, and a positive family history with inverse profiles of asymmetry in males vs. females; non-right-handedness was associated with increased ventricular volume in males but with poorer premorbid intellectual function in females. This nexus of relationships and their gender specificities suggest early dysmorphogenesis in schizophrenia that is related to sexual dimorphism.

Abnormalities, Multiple↗
PubMed1990

Asymmetric distribution of brain monoamines in left- and right-handed mice.

Biogenic amine distributions analyzed in the cerebral neocortex, striatum, anterior hypothalamus, and bulbospinal region, were compared between both hemispheres of left- and right-handed mice. The handedness of mice was determined using a paw preference test. The animals were tested 5 times, once every two weeks, and the biochemical analysis was performed two weeks after the last behavioral evaluation. The results indicated that (1) asymmetrical monoaminergic concentrations exist in the mouse brain. Monoamine contents were found to be higher in the right parietal cortex and anterior hypothalamus than in the left ones; (2) besides the behavioral expression of handedness, left- and right-handed subpopulations of mice differ according to asymmetrical distributions of cortical and bulbospinal NE contents as well as DA turnover of the tuberoinfundibular system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

A factor analysis of the human's corpus callosum.

We have recently developed a computer program for measuring midsagittal sections of the human corpus callosum, similar to one used for the rat. Callosal area, perimeter, axis length, and 99 widths for 104 subjects were entered into a factor analysis in order to define regional clusters. Seven width factors were obtained. Regional widths were found to be sensitive to Sex X Handedness interactions in the anterior body, with right-handed females and left-handed males being larger. In the posterior body males had wider callosa than females. A further analysis within the 'isthmus' region compared consistent and non-consistent right-handed males and females. Consistent right-handed males and both female groups had smaller callosa than non-consistent right-handed males. These findings confirmed the use of consistency of handedness as an important independent variable with respect to human callosal morphology.

Adult↗
PubMed1991

The relationship of hand preference to anatomy of the corpus callosum in men.

Area of the midsagittal section of the corpus callosum, particularly in the region of the isthmus, was found previously to be greater in non-consistent-right-handed than consistent-right-handed men in a sample of 15 postmortem cases. Seven cases were obtained subsequent to this analysis. The new cases showed the same association previously observed between hand preference and area of the corpus callosum and its isthmus. In addition, a high negative correlation was found between isthmal area and a quantitative score of the direction and magnitude of hand preference. In the new cases, handedness was predicted better than chance using statistical functions of callosal anatomy derived from the previous group of 15 cases. These results support a relationship between variation in callosal anatomy and handedness in men and the hypothesis of a relationship between callosal morphology and functional asymmetry. The lack of such a relationship among women suggests that the developmental mechanisms leading to callosal anatomical variation in relation to lateralization are influenced by sex hormones. Methodological issues in the use of magnetic resonance imaging for the quantitative study of callosal anatomy are discussed.

Autopsy↗
PubMed1989

Diverse supernumerary structures develop after inverting the anteroposterior limb axis of the anuran.

Contralateral limb bud graftings were performed on tadpoles of the anuran Bufo bufo. The anteroposterior axis was inverted while the larvae were at stage IV or V (e.g., between 22-30 days after fertilization). Eighty-four tadpoles were operated on, 10 of which were used as controls. At anterior or posterior location 104 supernumerary structures developed in toto. They were collected and whole-mount examined after being stained with Alcian blue. They were further prepared for serial sectioning, mounting, and staining with hematoxylin and eosin. The majority of these supernumerary structures were found to be normal limbs of the stump handedness in agreement with all models and experiments on the urodeles axolotl and newt. However, some of the structures were clearly abnormal: double symmetric or of mixed handedness. This result is consistent with a prediction of a hierarchical polar coordinate model. The fact that no such structures have been found in the experiments on the urodeles may be due to the expected low probability for their appearance and the fact that only few such limbs have been sectioned and analyzed as yet.

Alcian Blue↗
PubMed1982

Hemispheric differences in split-brain monkeys learning sequential comparisons.

Twelve split-brain rhesus monkeys were tested for differences in the abilities of their two cerebral hemispheres to learn discriminations based on the comparison of sequentially-presented visual stimuli. Overall there was no generalized advantage for either the left or right hemisphere. There was, however, a significant correlation between each monkey's handedness and the hemisphere that learned more readily; the more proficient hemisphere tended to be contralateral to the preoperatively preferred hand. This result raises the possibility that handedness in monkeys may be more closely related to cognitive processing than is usually believed.

Animals↗
PubMed1985

The role of familial sinistrality in cerebral organization.

The literature on the relationship between familial sinistrality (FS) and laterality is conflicting. A large scale investigation employing multiple measures of laterality assessment and rigorous methods of handedness and FS determination was conducted with a normal population of left- and right-handers. The results failed to find a relationship between FS and hemispheric representation of speech despite the fact that a robust relationship was found between handedness and hemispheric speech specialization. Possible reasons for these null findings are discussed.

Adolescent↗