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SMA*

About: SMA* is a research topic. Over the lifetime, 6622 publications have been published within this topic receiving 160711 citations. The topic is also known as: Simplified Memory-Bounded A*.


Papers
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Journal ArticleDOI
15 Jan 2009-Nature
TL;DR: This is the first study to show that human induced pluripotent stem cells can be used to model the specific pathology seen in a genetically inherited disease and represents a promising resource to study disease mechanisms, screen new drug compounds and develop new therapies.
Abstract: Spinal muscular atrophy is one of the most common inherited forms of neurological disease leading to infant mortality. Patients have selective loss of lower motor neurons resulting in muscle weakness, paralysis and often death. Although patient fibroblasts have been used extensively to study spinal muscular atrophy, motor neurons have a unique anatomy and physiology which may underlie their vulnerability to the disease process. Here we report the generation of induced pluripotent stem cells from skin fibroblast samples taken from a child with spinal muscular atrophy. These cells expanded robustly in culture, maintained the disease genotype and generated motor neurons that showed selective deficits compared to those derived from the child’s unaffected mother. This is the first study to show that human induced pluripotent stem cells can be used to model the specific pathology seen in a genetically inherited disease. As such, it represents a promising resource to study disease mechanisms, screen new drug compounds and develop new therapies. The inherited disease spinal muscular atrophy (SMA), one of the most common neurological disorders causing death in childhood, is caused by mutations in both copies of the SMN1 gene. Little is known about SMA pathogenesis, partly because it is unique to humans who have two versions of this gene — SMN1 and SMN2; rodents and other lab model candidates have just one. Now a new technique has been developed that creates a tool for studying SMA disease pathology at the cellular level. Skin fibroblasts from a child with SMA (and for comparison from his unaffected mother) were used to generate induced pluripotent stem (iPS) cell lines. They form neural progenitor cultures that can produce differentiated neural tissue and motor neurons that maintain the disease phenotype. The cultures also responded to drugs known to elevate the mutated protein associated with the disease. Similar iPS technology may be of value in the study of other genetic disorders such as Huntington's disease. This paper generates an iPS cell line from patients with spinal muscular atrophy, an autosomal recessive genetic disorder that is one of the most common inherited forms of neurological disease in children.

1,495 citations

Journal ArticleDOI
TL;DR: The proposed slime mould algorithm has several new features with a unique mathematical model that uses adaptive weights to simulate the process of producing positive and negative feedback of the propagation wave of slime mould based on bio-oscillator to form the optimal path for connecting food with excellent exploratory ability and exploitation propensity.

1,443 citations

Journal ArticleDOI
Gary Goldberg1
TL;DR: It is suggested that the SMA has an important role to play in the intentional process whereby internal context influences the elaboration of action, and an anatomico-physiologic model of the medial premotor system is proposed which embodies the principles of cyclicity and reentrance.
Abstract: Though its existence has been known for well over 30 years, only recently has the supplementary motor area (SMA) and its role in the cortical organization of movement come to be examined in detail by neuroscientists. Evidence from a wide variety of investigational perspectives is reviewed in an attempt to synthesize a conceptual framework for understanding SMA function. It is suggested that the SMA has an important role to play in the intentional process whereby internal context influences the elaboration of action. It may be viewed as phylogenetically older motor cortex, derived from anterior cingulate periarchicortical limbic cortex, which, as a key part of a medial premotor system, is crucial in the “programming” and fluent execution of extended action sequences which are “projectional” in that they rely on model-based prediction. This medial system can be distinguished from a lateral premotor system postulated to have evolved over phylogeny from a different neural source. An anatomico-physiologic model of the medial premotor system is proposed which embodies the principles of cyclicity and reentrance in the process of selecting those neural components to become active in conjunction with the performance of a particular action. The postulated dynamic action of this model in the microgenesis of a discrete action is outlined. It is concluded that although there is a great deal to be learned about the SMA, a convergence of current evidence can be identified. Such evidence suggests that the SMA plays an important role in the development of the intention-to-act and the specification and elaboration of action through its mediation between medial limbic cortex and primary motor cortex.

1,153 citations

Book
01 Jan 2008
TL;DR: In this paper, the authors describe the transformation-induced plasticity in shape memory alloys and model the transformation induced plasticity of magnetic SMAs using return mapping algorithms using SMA models.
Abstract: to Shape Memory Alloys.- Thermomechanical Characterization of Shape Memory Alloy Materials.- Thermomechanical Constitutive Modeling of SMAs.- Numerical Implementation of an SMA Thermomechanical Constitutive Model Using return Mapping Algorithms.- Modeling of Transformation-Induced Plasticity in SMAs.- Extended SMA Modeling.- Modeling of Magnetic SMAs.

1,127 citations

Journal ArticleDOI
25 Jan 1996-Nature
TL;DR: A NAIP-mediated inhibition of apoptosis induced by a variety of signals is demonstrated, and three additional human complementary DNAs and a Drosophila melanogaster sequence that are also homologous to the baculovirus lAPs are identified.
Abstract: DYSREGULATION of apoptosis can result in inappropriate suppression of cell death, as occurs in the development of some cancers1, or in failure to control the extent of cell death, as is believed to occur in acquired immunodeficiency and certain neurodegenera-tive disorders, such as spinal muscular atrophy (SMA). Recently, we isolated a candidate gene, encoding neuronal apoptosis inhibitor protein (NAIP)2, for SMA. This gene is homologous to two baculovirus inhibitor of apoptosis proteins3,4(Cp-IAP and Op-IAP) and is partly deleted in individuals with type I SMA. A second SMA candidate gene encoding survival motor neuron (SMN), which is contiguous with the NAIP locus on 5ql3.1, was also reported5. Here we demonstrate a NAIP-mediated inhibition of apoptosis induced by a variety of signals, and have identified three additional human complementary DNAs and a Drosophila melanogaster sequence that are also homologous to the baculovirus lAPs. The four open reading frames (ORFs) possess three baculoviral inhibition of apoptosis protein repeat (BIR) domains and a carboxy-terminal RING zinc-finger. The human iap genes have a distinct but overlapping pattern of expression in fetal and adult tissues. These proteins significantly increase the number of known apoptotic suppressors.

1,101 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,060
20222,283
2021460
2020441
2019403
2018357