Homozygous deletion of RAG1, RAG2 and 5' region TRAF6 causes severe immune suppression and atypical osteopetrosis.

Mutations of several genes have been implicated in autosomal recessive osteopetrosis (OP), a disease caused by impaired function and differentiation of osteoclasts. Severe combined immune deficiencies (SCID) can likewise result from different genetic mutations. We report two siblings with SCID and an atypical phenotype of OP. A biallelic microdeletion encompassing the 5' region of TRAF6, RAG1 and RAG2 genes was identified. TRAF6, a tumor necrosis factor receptor-associated family member, plays an important role in T cell signaling and in RANKL-dependent osteoclast differentiation and activation but its role in human OP has not been previously reported. The RAG proteins are essential for recombination of B and T cell receptors, and for the survival and differentiation of these cells. This is the first study to report a homozygous deletion of TRAF6 as a cause of human disease.

High frequency of autosomal-recessive DFNB59 hearing loss in an isolated Arab population in Israel.

Autosomal-recessive non-syndromic hearing impairment (DFNB) is usually of prelingual onset with a moderate to profound degree of hearing loss. More than 70 DFNB loci have been mapped and ~40 causative genes have been identified. Non-syndromic hearing impairment caused by mutations of DFNB59 (encoding pejvakin) has been described in a couple of families in which affected individuals presented with either auditory neuropathy or hearing loss of cochlear origin. We have identified and clinically evaluated three consanguineous families of Israeli Arab origin with prelingual non-syndromic hearing impairment and absent otoacoustic emissions in a total of eight affected individuals. All the families originate from the same village and bear the same family name. We have identified a c.406C>T (p.R136X) nonsense mutation in the DFNB59 gene in affected individuals from these families. Among the inhabitants of the village, we found an exceptionally high carrier frequency of ~1 in 12 individuals (7/85; 8.2%). The high prevalence of hearing impairment can be explained by a founder effect and the high consanguinity rate among the inhabitants of this village.

Globus pallidus stimulation activates the cortical motor system during alleviation of parkinsonian symptoms.

Studies of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonism in monkeys suggest that excessive inhibitory outflow from the internal segment of the globus pallidus (GPi) suppresses the motor thalamus, which reduces activation of the cerebral cortex motor system, resulting in the slowness and poverty of movement of Parkinson's disease (PD). This hypothesis is supported by reports of high rates of spontaneous neuronal discharges and hypermetabolism in GPi (ref. 4-7) and impaired activation of the supplementary motor area (SMA) and dorsolateral prefrontal regions in PD patients. Furthermore, lesion or chronic high-frequency electrical (likely inactivating) stimulation of GPi (ref. 10-14) is associated with marked improvements in akinesia and rigidity, and the impaired activation of SMA is reversed when the akinesia is treated with dopamine agonists. To test whether improvement in motor function with pallidal surgery can be attributed to increased activity in premotor cortical regions, we assessed the changes in regional cerebral blood flow (rCBF) and parkinsonian symptoms during disruption of GPi activity with high-frequency stimulation delivered through implanted brain electrodes. Positron emission tomography (PET) revealed an increase in rCBF in ipsilateral premotor cortical areas during GPi stimulation, which improved rigidity and bradykinesia. These results suggest that disrupting the excessive inhibitory output of the basal ganglia reverses parkinsonism, via a thalamic relay, by activation of brain areas involved in the initiation of movement.

Low daily MEWS scores as predictors of low-risk hospitalized patients.

BACKGROUND: The Modified Early Warning System (MEWS) is a well-validated tool used by hospitals to identify patients at high risk for an adverse event to occur. However, there has been little evaluation into whether a low MEWS score can be predictive of patients with a low likelihood of an adverse event. AIM: The present study aims to evaluate the MEWS score as a method of identifying patients at low risk for adverse events. DESIGN: Retrospective cohort study of 5676 patient days and analysis of associated MEWS scores, medical comorbidities and adverse events. The primary outcome was the association of average daily MEWS scores in those who had an adverse event compared with those who did not. RESULTS: Those with an average MEWS score of >2 were over 9 times more likely to have an adverse event compared with those with an average MEWS score of 1-2, and over 15 times more likely to have an adverse event compared to those with an average MEWS score of <1. CONCLUSIONS: Our study shows that those with average daily MEWS scores <2 are at a significantly lower likelihood of having an adverse event compared with a score of >2, deeming them 'low-risk patients'. Formal recognition of such patients can have major implications in a hospital setting, including more efficient resource allocation in hospitals and better patient satisfaction and safety by adjusting patient monitoring according to their individual risk profile.

Prism adaptation: control of intermanual transfer by distribution of practice.

Correction of errors in localizing movements produced by laterally displacing vision by means of wedge prisms has been termed "prism adaptation." Intermanual transfer of prism adaptation from an exposed to an unexposed hand, with subject's head immobilized, has been reported not to occur. However, it was found that a standard learning variable, distribution of practice, controls the occurrence or nonoccurrence of transfer. When practice is massed, there is no transfer of adaptation; when it is spaced, the transfer is extensive. Spacing of practice also influences the amount of aftereffect displayed by the exposed hand.

Deafferentation in monkeys: effect on conditioned grasp response.

A preliminary technique was developed for conditioning grasp response in monkeys, for use in studying the effect of damage to the central nervous system on skilled movement. That subjects were able to learn this response with a deafferented hand, in the absence of vision, indicated that purposive movements of the distal musculature are less under the control of peripheral feedback than had been generally believed.

Summated cortical evoked response testing in the deafferented primate.

Dorsal rhizotomy from C(2) or C(3) to T(4) in the primate results in failure to elicit summated cortical responses from systematic stimulation of the appropriate peripheral nerves. Under these conditions there is thus no evidence of sensory input into the cerebral cortex. A nonclassical mechanism must therefore be operational to explain the extensive purposive movements observed in the deafferented animals.

Behavioral development after forelimb deafferentation on day of birth in monkeys with and without blinding.

Four infant monkeys underwent somatosensory deafferentation of both forelimbs within hours after birth. Ambulation, climbing, and reaching toward objects developed spontaneously in each case. Thumb-forefinger prehension could be trained by operant shaping methods. Two infants deafferented at birth and blinded by eyelid closure were retarded in motor development by only 1 to 2 weeks. Results indicate that topographic sensory feedback and autogenetic spinal reflexes are not necessary after birth for the development of most types of movement performed by the forelimb musculature in monkeys.

Increased cortical representation of the fingers of the left hand in string players.

Magnetic source imaging revealed that the cortical representation of the digits of the left hand of string players was larger than that in controls. The effect was smallest for the left thumb, and no such differences were observed for the representations of the right hand digits. The amount of cortical reorganization in the representation of the fingering digits was correlated with the age at which the person had begun to play. These results suggest that the representation of different parts of the body in the primary somatosensory cortex of humans depends on use and changes to conform to the current needs and experiences of the individual.

Massive cortical reorganization after sensory deafferentation in adult macaques.

After limited sensory deafferentations in adult primates, somatosensory cortical maps reorganize over a distance of 1 to 2 millimeters mediolaterally, that is, in the dimension along which different body parts are represented. This amount of reorganization was considered to be an upper limit imposed by the size of the projection zones of individual thalamocortical axons, which typically also extend a mediolateral distance of 1 to 2 millimeters. However, after extensive long-term deafferentations in adult primates, changes in cortical maps were found to be an order of magnitude greater than those previously described. These results show the need for a reevaluation of both the upper limit of cortical reorganization in adult primates and the mechanisms responsible for it.

The CC2D1A, a member of a new gene family with C2 domains, is involved in autosomal recessive non-syndromic mental retardation.

BACKGROUND: The molecular basis of autosomal recessive non-syndromic mental retardation (NSMR) is poorly understood, mostly owing to heterogeneity and absence of clinical criteria for grouping families for linkage analysis. Only two autosomal genes, the PRSS12 gene on chromosome 4q26 and the CRBN on chromosome 3p26, have been shown to cause autosomal recessive NSMR, each gene in only one family. OBJECTIVE: To identify the gene causing autosomal recessive NSMR on chromosome 19p13.12. RESULTS: The candidate region established by homozygosity mapping was narrowed down from 2.4 Mb to 0.9 Mb on chromosome 19p13.12. A protein truncating mutation was identified in the gene CC2D1A in nine consanguineous families with severe autosomal recessive NSMR. The absence of the wild type protein in the lymphoblastoid cells of the patients was confirmed. CC2D1A is a member of a previously uncharacterised gene family that carries two conserved motifs, a C2 domain and a DM14 domain. The C2 domain is found in proteins which function in calcium dependent phospholipid binding; the DM14 domain is unique to the CC2D1A protein family and its role is unknown. CC2D1A is a putative signal transducer participating in positive regulation of I-kappaB kinase/NFkappaB cascade. Expression of CC2D1A mRNA was shown in the embryonic ventricular zone and developing cortical plate in staged mouse embryos, persisting into adulthood, with highest expression in the cerebral cortex and hippocampus. CONCLUSIONS: A previously unknown signal transduction pathway is important in human cognitive development.

Constraint-induced movement therapy: characterizing the intervention protocol.

Constraint-induced movement therapy (CI therapy) is a rehabilitation treatment approach that improves more-affected extremity use following a stroke, especially in the life situation. The originators of the approach describe CI therapy as consisting of a family of therapies including a number of treatment components and subcomponents. When thinking of CI therapy, rehabilitation researchers and clinicians frequently cite a restraining mitt on the less affected arm as the main active ingredient behind improvements in motor function. However, substantial data suggest that restraint makes actually a relatively small contribution to treatment outcome. This paper provides a detailed description of the multiple treatment elements included in the CI therapy protocol as used in our research laboratory. Our aim is to improve understanding of CI therapy and the research supporting its use.

Neuroplasticity and constraint-induced movement therapy.

Recent years have seen a proliferation of animal and human studies that have associated significant changes in regional brain physiology with sustained altered environmental or somatic stimuli. The behavioral consequences in such instances can be adaptive or maladaptive. As would be expected, constraint-induced movement therapy (CI therapy), which has been found to be beneficial for chronic stroke hemiparesis, has been repeatedly associated with significant plastic brain changes in a variety of studies that have included transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), or other approaches. In some instances, the initial degree of brain reorganization occurred in parallel with the improvement in spontaneous, real-world use by the more-affected hand, which suggests that plastic brain changes in some manner support therapeutic effects. However, the studies are also inconsistent with respect to whether the reorganization changes occur more in the lesioned vs unlesioned hemisphere. Interpreting the physiological outcomes post-treatment is compromised by inconsistencies in study design in the nature of treatment administered, participant recruitment, imaging modality, and extent of follow-up. Improved understanding of the biological basis for neuroplasticity in CI therapy may be obtained through rigorous control of study approaches and through evaluating treatment changes with more than one modality in the same patients concurrently. New quantitative structural brain imaging techniques may allow measuring morphological changes following CI therapy to test hypotheses of regional brain recruitment in use-dependent therapy while avoiding the variability of functional imaging and mapping techniques and the difficulties and assumptions imposed by requiring active limb movement during scanning.

The learned nonuse phenomenon: implications for rehabilitation.

Research on monkeys with a single forelimb from which sensation is surgically abolished demonstrates that such animals do not use their deafferented limb even though they possess sufficient motor innervation to do so, a phenomenon labeled learned nonuse. This dissociation also occurs after neurological injury in humans. Instruments that measure these two aspects of motor function are discussed. The effects of a neurological injury may differ widely in regard to motor ability assessed on a laboratory performance test in which movements are requested and actual spontaneous use of an extremity in real-world settings, indicating that these parameters need to be evaluated separately. The methods used in Constraint-Induced Movement therapy (CI therapy) research to independently assess these two domains are reliable and valid. We suggest that these tests have applicability beyond studies involving CI therapy for stroke and may be of value for determining motor status in other types of motor disorders and with other types of treatment. The learned nonuse formulation also predicts that a rehabilitation treatment may have differential effects on motor performance made on request and actual spontaneous amount of use of a more affected upper extremity in the life situation. CI therapy produces improvements in the former, but focuses attention on the latter and, in fact, spontaneous use of the limb is where this intervention has by far its greatest effect. The evidence suggests that this result is driven by use of a ''transfer package'' of techniques, which can be used with other therapies to increase the transfer of improvements made in the clinic to the life situation. The use of CI therapy in humans began with the upper extremity after stroke and was then extended for the upper extremity to cerebral palsy in young children (8 months to 8 years old) and traumatic brain injury. A form of CI therapy was developed for the lower extremities and was used effectively after stroke, spinal cord injury, and fractured hip. Adaptations of CI therapy have also been developed for aphasia (CI aphasia therapy), focal hand dystonia in musicians and phantom limb pain. The range of these applications suggests that CI therapy is not only a treatment for stroke, for which it is most commonly used, but for learned nonuse in general, which manifests as excess motor disability in a number of conditions which until now have been refractory to treatment.

Differential activation in somatosensory cortex for different discrimination tasks.

Maps of the body surface in somatosensory cortex have been shown to be highly plastic, altering their configuration in response to changes in use of body parts. The current study investigated alterations in the functional organization of the human somatosensory cortex resulting from massed practice. Over a period of 4 weeks, subjects were given synchronous tactile stimulation of thumb (D1) and little finger (D5) for 1 hr/d. They had to identify the orientation of the stimuli. Neuroelectric source localization based on high-resolution EEG revealed that, when subjects received passive tactile stimulation of D1 or D5, the representations of the fingers in primary somatosensory cortex were closer together after training than before. There was also an apparently correlative tendency to anomalously mislocalize near-threshold tactile stimuli equally to the distant finger costimulated during training rather than preferentially to the finger nearest to the finger stimulated in a post-training test. However, when the stimulus discrimination had to be made, neuroelectric source imaging revealed that the digital representations of D1 and D5 were further apart after training than before. Thus, the same series of prolonged repetitive stimulations produced two different opposite effects on the spatial relationship of the cortical representations of the digits, suggesting that differential activation in the same region of somatosensory cortex is specific to different tasks.

Progressive transneuronal changes in the brainstem and thalamus after long-term dorsal rhizotomies in adult macaque monkeys.

This study deals with a potential brainstem and thalamic substrate for the extensive reorganization of somatosensory cortical maps that occurs after chronic, large-scale loss of peripheral input. Transneuronal atrophy occurred in neurons of the dorsal column (DCN) and ventral posterior lateral thalamic (VPL) nuclei in monkeys subjected to cervical and upper thoracic dorsal rhizotomies for 13-21 years and that had shown extensive representational plasticity in somatosensory cortex and thalamus in other experiments. Volumes of DCN and VPL, number and sizes of neurons, and neuronal packing density were measured by unbiased stereological techniques. When compared with the opposite, unaffected, side, the ipsilateral cuneate nucleus (CN), external cuneate nucleus (ECN), and contralateral VPL showed reductions in volume: 44-51% in CN, 37-48% in ECN, and 32-38% in VPL. In the affected nuclei, neurons were progressively shrunken with increasing survival time, and their packing density increased, but there was relatively little loss of neurons (10-16%). There was evidence for loss of axons of atrophic CN cells in the medial lemniscus and in the thalamus, with accompanying severe disorganization of the parts of the ventral posterior nuclei representing the normally innervated face and the deafferented upper limb. Secondary transneuronal atrophy in VPL, associated with retraction of axons of CN neurons undergoing primary transneuronal atrophy, is likely to be associated with similar withdrawal of axons from the cerebral cortex and should be a powerful influence on reorganization of somatotopic maps in the somatosensory cortex.

Constraint-induced therapy of chronic aphasia after stroke.

Patients with chronic aphasia were assigned randomly to a group to receive either conventional aphasia therapy or constraint-induced (CI) aphasia therapy, a new therapeutic technique requiring intense practice over a relatively short period of consecutive days. CI aphasia therapy is realized in a communicative therapeutic environment constraining patients to practice systematically speech acts with which they have difficulty. Patients in both groups received the same amount of treatment (30 to 35 hours) as 10 days of massed-practice language exercises for the CI aphasia therapy group (3 hours per day minimum; 10 patients) or over a longer period of approximately 4 weeks for the conventional therapy group (7 patients). CI aphasia therapy led to significant and pronounced improvements on several standard clinical tests, on self-ratings, and on blinded-observer ratings of the patients' communicative effectiveness in everyday life. Patients who received the control intervention failed to achieve comparable improvements. Data suggest that the language skills of patients with chronic aphasia can be improved in a short period by use of an appropriate massed-practice technique that focuses on the patients' communicative needs.

Diminution of early environmental control through perinatal and prenatal somatosensory deafferentation.

Six monkeys subjected to forelimb deafferentation on day of birth (two blinded and four not blinded) spontaneously developed use of the affected limbs for support of body weight, ambulation, and clasping objects. The sighted animals also used them for climbing and reaching toward objects. Thumb-forefinger prehension did not emerge spontaneously but could be brought into existence through training. In another series of experiments, 5 of 11 monkey fetuses, exteriorized two-thirds of the way through gestation and given forelimb deafferentation, survived through caesarian delivery and at least 5 months of infancy. Although all were quadriparetic due to postoperative mechanical deformation of the cervical region, they were able to use the affected limbs to make postural adjustments and for standing and rudimentary ambulation. The results indicate that, after birth, neither spinal reflexes nor local somatosensory feedback and vision are necessary for the development of most types of movement performed by the forelimb musculature in monkeys. Continuance of the prenatal research should permit determination of the role of somatic sensation in the intrauterine development of behavior.

Chronic thalamic stimulation for treatment of dystonic paroxysmal nonkinesigenic dyskinesia.

The authors report the effect of chronic stimulation of the ventrointermediate (Vim) thalamus for treatment of dystonic paroxysmal nonkinesigenic dyskinesias (PNKD). A 37-year-old patient had a 4-year history of severe and painful PNKD of the right arm. Chronic stimulation through a stereotactically implanted monopolar electrode in the left Vim resulted in a decrease of the frequency, duration, and intensity of the dystonic paroxysmal movement disorder. The benefit of stimulation has been maintained over 4 years of follow-up.

The relationship of phantom limb pain to other phantom limb phenomena in upper extremity amputees.

In thirty-two unilateral upper extremity amputees with and without phantom limb pain, various phantom limb phenomena were investigated. In general, the incidence of non-painful phantom limb sensations was higher in patients with phantom limb pain than in pain-free amputees. Kinesthetic and kinetic phantom limb sensations were reported more frequently than exteroceptive cutaneous sensations. There was a significant positive correlation between phantom limb pain and stump pain. Patients more frequently assigned sensory than affective pain qualities to their phantom limb pain, whereas no differences between pain qualities were observed for stump pain. No support was found for a relationship between the presence of telescoping (i.e., shrinkage of the phantom limb) and phantom limb pain. These findings point to central as well as to peripheral factors contributing to phantom limb pain.