Prevalence of the three categories of handedness among Malawian school children

A cross sectional study of prevalence of left, right and mixed handedness was made on 512 Malawian school children (240 boys and 272 girls) aged 6-17 years. Handedness was assessed using questionnaire incorporating questions on hand preferred for eight unimanual activities. Interviews with guardians, pupils and teachers were conducted to assess the pressure experienced by children to use right hand for unimanual activities. The overall prevalence of left-, right- and mixed-handers was 3.9%, 90.4% and 5.7%, respectively. Association between handedness and age or gender of children was nonsignificant. 96.2% of guardians and 92.7% of teachers were insistent upon use of right hand for unimanual tasks. Most of non-right handed children indicated that they had experienced pressure to use right hand for unimanual activities but they were still using left hand for one or more manual tasks. 28 pupils indicated that they stopped using left hand under the pressure from guardians and teachers.     

The development of asymmetry: the sidedness of drug-induced limb abnormalities is reversed in situs inversus mice

We are studying the development of handedness, in particular the relationships between handed structures with bilateral symmetry, for example the limbs, and those with lateral asymmetry, such as the heart, lungs and gut. Asymmetric (unilateral) developmental limb abnormalities can be induced by chemical treatment of mouse embryos, either in utero by acetazolamide, or in culture by misonidazole. We have examined these effects in mice homozygous for the iv gene. The development of bilateral symmetry in iv/iv mice is normal, but the control of asymmetry appears to be random, that is 50% develop normally (situs solitus), 50% with laterally inverted viscera (situs inversus). We find that the handedness of induced asymmetric limb defects is highly correlated with embryonic visceral situs. Right limb defects are induced in situs solitus embryos, left-sided defects in situs inversus. This suggests that the mechanism of induction of asymmetric defects is not related to any intrinsic difference between the development of left and right limbs, but is connected to visceral asymmetry. In addition, the high correlation of limb defects with situs was observed in culture as well as in utero suggesting that the maternal environment plays no role in the development of asymmetry.     

The association between maternal nutrient intake during pregnancy and the risk of sporadic unilateral retinoblastoma among offspring

Previous studies have associated maternal diet during pregnancy with the development of sporadic unilateral retinoblastoma (RB), but few studies have focused on the role of individual nutrients. The aim of this study is to investigate the association between maternal nutrient intake during pregnancy and the development of sporadic unilateral RB in the offspring.A modified food frequency questionnaire, with additional questions on supplement use, was completed via a phone interview. Cases were recruited from hospitals and controls were comprised of friends and relatives of the patient without a history of cancer. Overall, 168 sporadic unilateral RB cases and 145 controls were included in case-control study. We performed logistic regression to estimate odds ratios (ORs) and 95 % confidence intervals (CI), adjusting for child’s age, child’s sex, parental race/ethnicity, maternal education, total calorie intake during pregnancy, maternal age at birth, maternal smoking during pregnancy, pre-pregnancy body mass index, maternal weight gain during pregnancy, paternal age at birth, and maternal multivitamin use in the year before pregnancy.In the adjusted model, the interquartile (IQR) increase in vitamin A intake, which was measured in retinol activity equivalent (RAE; OR: 0.64, 95 % CI: 0.46–0.90), and vitamin D intake (OR: 0.62, 95 % CI: 0.42–0.91) significantly reduced the risk of sporadic unilateral RB.These findings suggest that a higher intake of vitamins A and D can be a protective factor for sporadic unilateral RB. Further analyses in consideration of multi-exposures such as parental occupational exposures are warranted to discover the complex etiology of sporadic unilateral RB. In addition, the role of nutritional epigenetics for how maternal nutrient intake influences the risk of sporadic unilateral RB in the offspring still needs to be explored.     

Disruption of rolandic gamma-band functional connectivity by seizures is associated with motor impairments in children with epilepsy

Although children with epilepsy exhibit numerous neurological and cognitive deficits, the mechanisms underlying these impairments remain unclear. Synchronization of oscillatory neural activity in the gamma frequency range (>30 Hz) is purported to be a mechanism mediating functional integration within neuronal networks supporting cognition, perception and action. Here, we tested the hypothesis that seizure-induced alterations in gamma synchronization are associated with functional deficits. By calculating synchrony among electrodes and performing graph theoretical analysis, we assessed functional connectivity and local network structure of the hand motor area of children with focal epilepsy from intracranial electroencephalographic recordings. A local decrease in inter-electrode phase synchrony in the gamma bands during ictal periods, relative to interictal periods, within the motor cortex was strongly associated with clinical motor weakness. Gamma-band ictal desychronization was a stronger predictor of deficits than the presence of the seizure-onset zone or lesion within the motor cortex. There was a positive correlation between the magnitude of ictal desychronization and impairment of motor dexterity in the contralateral, but not ipsilateral hand. There was no association between ictal desynchronization within the hand motor area and non-motor deficits. This study uniquely demonstrates that seizure-induced disturbances in cortical functional connectivity are associated with network-specific neurological deficits.     

Effect of environmental factors on risk of injury of child pedestrians by motor vehicles: a case-control study.

OBJECTIVE--To identify and assess contribution of environmental risk factors for injury of child pedestrians by motor vehicles. DESIGN--Community based case-control study. Environmental characteristics of sites of child pedestrian injury were compared with the environmental characteristics of selected comparison sites. Each comparison site was the same distance and direction from home of control child as was the injury site from home or relevant case child. Two control sites were selected for each injury site. SETTING--Auckland region of New Zealand. SUBJECTS--Cases were 190 child pedestrians aged < 15 who were killed or hospitalised after collision with a motor vehicle on a public road during two years and two months. Controls were 380 children randomly sampled from population and frequency matched for age and sex. MAIN OUTCOME MEASURE--Traffic volume and speed and level of parking on curbs at injury sites and comparison sites. RESULTS--Risk of injury of child pedestrians was strongly associated with traffic volume: risk of injury at sites with highest traffic volumes was 14 times greater than that at least busy sites (odds ratio 14.30; 95% confidence interval 6.98 to 29.20), and risk increased with increasing traffic volume. High density of curb parking was also associated with increased risk (odds ratio 8.12; 3.32 to 19.90). Risk was increased at sites with mean speeds over 40 km/h (odds ratio 2.68; 1.26 to 5.69), although risk did not increase further with increasing speed. CONCLUSION--Reducing traffic volume in urban areas could significantly reduce rates of child pedestrian injury. Restricting curb parking may also be effective.     

Filamentous organisms in benign and malignant gastric cytology brushings

Review of 143 gastric brushing specimens from two centres in patients with a subsequent histological diagnosis on biopsy or gastrectomy specimens revealed filamentous organisms (FOs) in a large number of benign and malignant gastric brushings. The presence of FOs in significant numbers of brushings of benign gastric lesions contradicts the previously reported strong association of FOs with only gastric carcinoma, and questions the importance of finding these organisms in gastric brushing and biopsy material.     

Sensorimotor dysfunctions as primary features of autism spectrum disorders

Motor impairments in autism spectrum disorders(ASD) have received far less research attention than core social- communication and cognitive features. Yet, behavioral, neurophysiological, neuroimaging and histopathological studies have documented abnormal motor system development in the majority of individuals with ASD suggesting that these deficits may be primary to the disorder. There are several unique advantages to studying motor development in ASD. First, the neurophysiological substrates of motor skills have been well-characterized via animal and human lesion studies. Second, many of the single-gene disorders associated with ASD also are characterized by motor dysfunctions. Third, recent evidence suggests that the onset of motor dysfunctions may precede the emergence of social and communication deficits during the first year of life in ASD. Motor deficits documented in ASD indicate disruptions throughout the neuroaxis affecting cortex, striatum, the cerebellum and brainstem. Questions remain regarding the timing and development of motor system alterations in ASD, their association with defining clinical features, and their potential for parsing heterogeneity in ASD. Pursuing these questions through neurobiologically informed translational research holds great promise for identifying gene-brain pathways associated with ASD.     

Interaction of fraternal birth order and handedness in the development of male homosexuality

The present study investigated evidence for an interaction between two of the best established etiologic factors, or markers of etiologic factors, in the literature on male homosexuality: fraternal birth order and hand preference. By combining five samples, the authors produced study groups of 1774 right-handed heterosexuals, 287 non-right-handed heterosexuals, 928 right-handed homosexuals, and 157 non-right-handed homosexuals. The results showed a significant (P = 0.004) handedness by older brothers interaction, such that (a) the typical positive correlation between homosexuality and greater numbers of older brothers holds only for right-handed males, (b) among men with no older brothers, homosexuals are more likely to be non-right-handed than heterosexuals; among men with one or more older brothers, homosexuals are less likely to be non-right-handed than heterosexuals, and (c) the odds of homosexuality are higher for men who have a non-right hand preference or who have older brothers, relative to men with neither of these features, but the odds for men with both features are similar to the odds for men with neither. These findings have at least two possible explanations: (a) the etiologic factors associated with non-right-handedness and older brothers-hypothesized to be hyperandrogenization and anti-male antibodies, respectively-counteract each other, yielding the functional equivalent of typical masculinization, and (b) the number of non-right-handed homosexuals with older brothers is smaller than expected because the combination of the older brothers factor with the non-right-handedness factor is toxic enough to lower the probability that the affected fetus will survive.     

Association of newborn blood lead concentration with neurodevelopment outcome in early infancy

BackgroundIn utero exposure to toxic metal substances can cause severe neurodevelopmental deficits in developing fetus and infant.MethodsWe evaluated the association of newborn umbilical cord blood lead concentration with early neurodevelopmental performance (cognitive, receptive language, expressive language, fine motor, gross motor and social-emotional development). The Bayley Scale of Infants Developments-III (BSID-III) was used to perform neurodevelopment outcomes at an average age of 6.5 months. In this prospective study, total of 167 mother-child pairs were enrolled from Western Rajasthan, India. Association between risk factors of lead contamination and newborn umbilical cord blood lead levels was observed. Multivariate regression was performed to see the association of cord blood lead level with infant neurodevelopment outcome.ResultsThe obtained newborn umbilical cord blood lead concentration 5.0–10.5 μg/dL was negatively associated with the sub-scale score of gross motor development (β-coefficient with 95 % CI; −0.29 (−5.0–0.11), p = 0.04). However, no associations were found with the score of cognitive, language, gross motor, and social-emotional development. The umbilical cord blood lead concentration <5.0 μg/dL was also not associated with the BSID-III scores. The mother's regular intake of calcium supplements during the antenatal period was significantly associated with a lower umbilical cord blood lead level (p-value 0.031).ConclusionThe data suggest that newborn umbilical cord blood lead concentration 0.5–10.5 μg/dL has a negative association with early gross motor development during infancy.     

Amniotic fluid brain-specific proteins are biomarkers for spinal cord injury in experimental myelomeningocele

Myelomeningocele (MMC), the most severe form of spina bifida (SB), causes neurological deficit. Injury to the spinal cord is thought to begin in utero. We investigated whether brain-specific proteins (BSPs) would enable us to monitor the development of MMC-related tissue damage during pregnancy in an animal model with naturally occurring SB (curly tail/loop tail mouse; n = 256). Amniotic fluid levels of neurofilament heavy chain (NfH), glial acidic fibrillary protein (GFAP) and S100B were measured by standard ELISA techniques. The amniotic fluid levels of all BSPs were similar in SB and control mice on embryonic day (E) 12.5 and 14.5, whereas a significant increase was observed for GFAP in SB mice on E16.5. Levels of all BSPs were significantly increased in SB mice on E18.5. The rapid increase in GFAP, paralleled by a moderate increase in NfH and S100B, suggests that spinal cord damage starts to accelerate around E16.5. The macroscopic size of the MMC was related to NfH level on E16.5 and E18.5, suggesting that axonal degeneration is most severe in large MMC. Amniotic fluid BSP measurements may provide important information for balancing the risks and benefits to mother and child of in utero surgery for MMC.     

Hand Dominance and Age Have Interactive Effects on Motor Cortical Representations

Older adults exhibit more bilateral motor cortical activity during unimanual task performance than young adults. Interestingly, a similar pattern is seen in young adults with reduced hand dominance. However, older adults report stronger hand dominance than young adults, making it unclear how handedness is manifested in the aging motor cortex. Here, we investigated age differences in the relationships between handedness, motor cortical organization, and interhemispheric communication speed. We hypothesized that relationships between these variables would differ for young and older adults, consistent with our recent proposal of an age-related shift in interhemispheric interactions. We mapped motor cortical representations of the right and left first dorsal interosseous muscles using transcranial magnetic stimulation (TMS) in young and older adults recruited to represent a broad range of the handedness spectrum. We also measured interhemispheric communication speed and bimanual coordination. We observed that more strongly handed older adults exhibited more ipsilateral motor activity in response to TMS; this effect was not present in young adults. Furthermore, we found opposing relationships between interhemispheric communication speed and bimanual performance in the two age groups. Thus, handedness manifests itself differently in the motor cortices of young and older adults and has interactive effects with age.     

Neurological sequelae in twins born after assisted conception: controlled national cohort study

Objective To compare neurological sequelae in twins born after assisted conception with singletons after assisted conception and naturally conceived twins and to assess neurological sequelae in children conceived after in vitro fertilisation (IVF) compared with intracytoplasmic sperm injection (ICSI).Design Controlled, national register based, cohort study.Participants Twins (n = 3393) and singletons (n = 5130) conceived by using assisted reproductive technologies and naturally conceived twins (n = 10 239) born in Denmark between 1995 and 2000. The children''s age at time of follow up was 2-7 years.Data sources Children were identified by cross linkage of the national medical birth registry and the national registry for in vitro fertilisation. Neurological and psychiatric diagnoses were retrieved from the national patients'' registry and the Danish psychiatric central registry.Main outcome measures Neurological sequelae, defined as cerebral palsy, mental retardation, severe mental developmental disturbances, and retarded psychomotor development. Further we made separate analyses on the specific cerebral palsy diagnosis.Results The crude prevalence rates per 1000 of neurological sequelae in twins and singletons after assisted conception and in naturally conceived twins were 8.8, 8.2, and 9.6, and of cerebral palsy 3.2, 2.5, and 4.0, respectively. In twins after assisted conception compared with control twins, the odds ratios of neurological sequelae and specifically of cerebral palsy, adjusted for child sex and year of birth, were 0.9 (95% confidence interval 0.6 to 1.4) and 0.8 (0.4 to 1.6), respectively. The corresponding odds ratios for twins after assisted conception compared with singletons after assisted conception were 1.1 (0.7 to 1.7) for neurological sequelae and 1.3 (0.6 to 2.9) for cerebral palsy. The odds ratio of neurological sequelae in children conceived by ICSI was 0.9 (0.5 to 1.7) ν children conceived by IVF.Conclusions Twins from assisted conception have a similar risk of neurological sequelae as their naturally conceived peers and singletons from assisted conception. Children born after ICSI have the same risk of neurological sequelae as children born after IVF.     

Motor asymmetry of the forelimbs of the rat

Preference was studied of one of the forelimbs during performance of different manipulating movements in white rats. High degree of "handedness" was observed in all studied movements. However it was not absolute--no animals performed all movements by one and the same limb. Degree and character of "handedness" were different for different movements, though the number of "righthanded" rats in most tests as a whole exceeded the number of "lefthanded" ones. The "handedness" depends on the individuality of the animal, the character of the motor task, learning and interference of different motor tasks during training.     

Pertussis immunisation and serious acute neurological illness in children.

The first 1000 cases notified to the National Childhood Encephalopathy Study were analysed. The diagnoses included encephalitis/encephalopathy, prolonged convulsions, infantile spasms, and Reye''s syndrome. Eighty-eight of the children had had a recent infectious disease, including 19 with pertussis. Only 35 of the notified children (3.5%) had received pertussis antigen within seven days before becoming ill. Of 1955 control children matched for age, sex, and area of residence, 34 (1.7%) had been immunised with pertussis vaccine within the seven days before the date on which they became of the same age as the corresponding notified child. The relative risk of a notified child having had pertussis immunisation within that time interval was 2.4 (p less than 0.001). Of the 35 notified children, 32 had no previous neurological abnormality. A year later two had died, nine had developmental retardation, and 21 were normal. A significance association was shown between serious neurological illness and pertussis vaccine, though cases were few and most children recovered completely.     

Early development (5 to 48 months) in Williams syndrome. A study of 14 children.

At what age do children with Williams syndrome (WS) achieve major developmental milestones? Is their early development harmonious or are some of the typical discrepancies described in older children already noticeable? To address these questions we analysed information gathered over a five year period on 14 children with WS. Each child was evaluated at least twice between the ages of 5 and 48 months, using the Bayley Scales of Infant Development and during more informal observation sessions. Parents and professionals were also interviewed. This analysis provided us with an outline for "developmental norms" for children with WS and allowed us to conclude that, even before the age of 4 years, children with WS display a typical profile in their abilities. Expressive language skills are less delayed in contrast to the important delay in language comprehension and fine motor skills.     

Handedness of a Motor Program in C. elegans Is Independent of Left-Right Body Asymmetry

Complex animals display bilaterally asymmetric motor behavior, or “motor handedness,” often revealed by preferential use of limbs on one side. For example, use of right limbs is dominant in a strong majority of humans. While the mechanisms that establish bilateral asymmetry in motor function are unknown in humans, they appear to be distinct from those for other handedness asymmetries, including bilateral visceral organ asymmetry, brain laterality, and ocular dominance. We report here that a simple, genetically homogeneous animal comprised of only ∼1000 somatic cells, the nematode C. elegans, also shows a distinct motor handedness preference: on a population basis, males show a pronounced right-hand turning bias during mating. The handedness bias persists through much of adult lifespan, suggesting that, as in more complex animals, it is an intrinsic trait of each individual, which can differ from the population mean. Our observations imply that the laterality of motor handedness preference in C. elegans is driven by epigenetic factors rather than by genetic variation. The preference for right-hand turns is also seen in animals with mirror-reversed anatomical handedness and is not attributable to stochastic asymmetric loss of male sensory rays that occurs by programmed cell death. As with C. elegans, we also observed a substantial handedness bias, though not necessarily the same preference in direction, in several gonochoristic Caenorhabditis species. These findings indicate that the independence of bilaterally asymmetric motor dominance from overall anatomical asymmetry, and a population-level tendency away from ambidexterity, occur even in simple invertebrates, suggesting that these may be common features of bilaterian metazoans.     

Birth spacing and child mortality in a Caribbean population.

Ten independent variables were used to predict death before the first birthday for 4411 births that took place from 1878 to 1976 to 978 women of native ancestry on the island of St. Barthélemy. Significant predictors of death include the death of the mother within a year, the birth year, multiple birth, whether the preceding child also died before 1 year of age, and whether the next child was conceived before the index child was 1 year old. Unlike most prior studies, birth-spacing variables were only weakly related to death in the first year. The relative absence of contraceptive techniques to control birth spacing in the study population and the use of vital records rather than survey data distinguish this project from others and may account at least partly for the unusual findings.     

早期干预对早产儿脑损伤预后的临床观察

目的：探讨早期联合干预对脑损伤早产儿智能及运动发育的影响。方法：80例存在脑损伤的早产儿随机分为干预组与对照组,每组各40例,对照组给予常规治疗与保健指导,干预组在此基础上联合神经节苷脂治疗与早期康复训练,定期随访两年,观察比较患儿纠正胎龄40周时神经行为评分（NBNA）,智力及运动发育情况。结果：干预组患儿纠正胎龄40周NBNA评分为33．04±1．12．对照组NBNA评分为30．95±0．88,两组间差异有统计学意义（P〈0．05）;干预组MDI与PDI指数分别于9月龄始和6月龄始显著高于对照组（P〈0．01或0．05）;1岁时进行Gesell智力发育检查,干预组大运动、精细动作、适应性、语言、个人一社会交往等五个能区情况均明显好于对照组（P〈0．01）;干预组17．5％的后遗症发生率显著低于对照组32．5％的发生率（P〈0．01）。结论：联合旱期干预治疗可有效促进脑损伤早产儿神经系统功能修复,改善智能及运动发育,减少后遗症发生。     

Pulsed subcutaneous electrical stimulation in spinal cord injury: preliminary results

The treatment of long-term, stable para- and quadriplegics with pulsed electrical stimulation for pain control resulted in, anecdotally, a significant number of these individuals showing increased motor function as well as sensory awareness. This small pilot study was conducted in order to assess the hypothesis that pulsed electrical fields can effect diseased neurological function. Thirteen para- and quadriplegic subjects with 18 months of stable neurological signs and symptoms were exposed daily to pulsed electrical stimulation for a 6-month period and assessed for any improvement in motor function or sensory perception. The hypothesis is that pulsed electromagnetic fields can normalize viable but dysfunctional neuronal structures. Results were encouraging.     

Development of the system of cognitive functions in right- and left-handed boys aged six to seven years: A study taking into consideration specific features of early ontogeny

Characteristics of early ontogeny and the formation of cognitive functions of left-and right-handed boys six to seven years of age have been studied with the genesis of handedness taken into account. A comparative analysis of cognition in right-and left-handed children has been performed using a unified approach to the history of early ontogeny with special emphasis on cognitive functions. The negative effect of pathological pregnancies and births, as well as disturbances in early ontogeny, on the development of cognitive functions in both left-and right-handed boys has been shown. The most “vulnerable” functions in right-handed boys with a history of various pathologies are the organization of activity and visuospatial perception; in left-handed boys, these are fine motor skills and speech development. In the absence of pathologies in the medical history, significantly higher indices of the organization of activity and visuomotor coordination have been found in right-handed boys and significantly higher indices of visuospatial perception, in left-handed boys.