Visuomotor adaptive improvement and aftereffects are impaired differentially following cerebellar lesions in SCA and PICA territory

The aim of the present study was to elucidate the contribution of the superior and posterior inferior cerebellum to adaptive improvement and aftereffects in a visuomotor adaptation task. Nine patients with ischemic lesions within the territory of the posterior inferior cerebellar artery (PICA), six patients with ischemic lesions within the territory of the superior cerebellar artery (SCA) and 17 age-matched controls participated. All subjects performed center-out reaching movements under 60° rotation of visual feedback. For the assessment of aftereffects, we tested retention of adaptation and de-adaptation under 0° visual rotation. From this data we also quantified five measures of motor performance. Cerebellar lesion-symptom mapping was performed using magnetic resonance imaging subtraction analysis. Adaptive improvement during 60° rotation was significantly degraded in PICA patients and even more in SCA patients. Subtraction analysis revealed that posterior (Crus I) as well as anterior cerebellar regions (lobule V) showed a common overlap related to deficits in adaptive improvement. However, for aftereffect measures as well as for motor performance variables only SCA patients, but not PICA patients showed significant differences to control subjects. Subtraction analysis showed that affection of lobules V and VI were more common in patients with impaired retention and de-adaptation, respectively. Data shows that areas both within the superior and posterior inferior cerebellum are involved in adaptive improvement. However, only the superior cerebellum including lobules V and VI appears to be important for aftereffects and therefore true adaptive ability

Diagnosis of acute myeloid leukemia according to the WHO classification in the Japan Adult Leukemia Study Group AML-97 protocol

We reviewed and categorized 638 of 809 patients who were registered in the Japan Adult Leukemia Study Group acute myeloid leukemia (AML)-97 protocol using morphological means. Patients with the M3 subtype were excluded from the study group. According to the WHO classification, 171 patients (26.8%) had AML with recurrent genetic abnormalities, 133 (20.8%) had AML with multilineage dysplasia (MLD), 331 (51.9%) had AML not otherwise categorized, and 3 (0.5%) had acute leukemia of ambiguous lineage. The platelet count was higher and the rate of myeloperoxidase (MPO)-positive blasts was lower in AML with MLD than in the other WHO categories. The outcome was significantly better in patients with high (≥50%) than with low (<50%) ratios of MPO-positive blasts (P < 0.01). The 5-year survival rates for patients with favorable, intermediate, and adverse karyotypes were 63.4, 39.1, and 0.0%, respectively, and 35.5% for those with 11q23 abnormalities (P < 0.0001). Overall survival (OS) did not significantly differ between nine patients with t(9;11) and 23 with other 11q23 abnormalities (P = 0.22). Our results confirmed that the cytogenetic profile, MLD phenotype, and MPO-positivity of blasts are associated with survival in patients with AML, and showed that each category had the characteristics of the WHO classification such as incidence, clinical features, and OS

Nanoscale stiffness topography reveals structure and mechanics of the transport barrier in intact nuclear pore complexes

The nuclear pore complex (NPC) is the gate for transport between the cell nucleus and the cytoplasm. Small molecules cross the NPC by passive diffusion, but molecules larger than ∼5 nm must bind to nuclear transport receptors to overcome a selective barrier within the NPC1. Although the structure and shape of the cytoplasmic ring of the NPC are relatively well characterized2, 3, 4, 5, the selective barrier is situated deep within the central channel of the NPC and depends critically on unstructured nuclear pore proteins5, 6, and is therefore not well understood. Here, we show that stiffness topography7 with sharp atomic force microscopy tips can generate nanoscale cross-sections of the NPC. The cross-sections reveal two distinct structures, a cytoplasmic ring and a central plug structure, which are consistent with the three-dimensional NPC structure derived from electron microscopy2, 3, 4, 5. The central plug persists after reactivation of the transport cycle and resultant cargo release, indicating that the plug is an intrinsic part of the NPC barrier. Added nuclear transport receptors accumulate on the intact transport barrier and lead to a homogenization of the barrier stiffness. The observed nanomechanical properties in the NPC indicate the presence of a cohesive barrier to transport and are quantitatively consistent with the presence of a central condensate of nuclear pore proteins in the NPC channel

In Vitro Transformation of Primary Human CD34+ Cells by AML Fusion Oncogenes: Early Gene Expression Profiling Reveals Possible Drug Target in AML

Different fusion oncogenes in acute myeloid leukemia (AML) have distinct clinical and laboratory features suggesting different modes of malignant transformation. Here we compare the in vitro effects of representatives of 4 major groups of AML fusion oncogenes on primary human CD34+ cells. As expected from their clinical similarities, MLL-AF9 and NUP98-HOXA9 had very similar effects in vitro. They both caused erythroid hyperplasia and a clear block in erythroid and myeloid maturation. On the other hand, AML1-ETO and PML-RARA had only modest effects on myeloid and erythroid differentiation. All oncogenes except PML-RARA caused a dramatic increase in long-term proliferation and self-renewal. Gene expression profiling revealed two distinct temporal patterns of gene deregulation. Gene deregulation by MLL-AF9 and NUP98-HOXA9 peaked 3 days after transduction. In contrast, the vast majority of gene deregulation by AML1-ETO and PML-RARA occurred within 6 hours, followed by a dramatic drop in the numbers of deregulated genes. Interestingly, the p53 inhibitor MDM2 was upregulated by AML1-ETO at 6 hours. Nutlin-3, an inhibitor of the interaction between MDM2 and p53, specifically inhibited the proliferation and self-renewal of primary human CD34+ cells transduced with AML1-ETO, suggesting that MDM2 upregulation plays a role in cell transformation by AML1-ETO. These data show that differences among AML fusion oncogenes can be recapitulated in vitro using primary human CD34+ cells and that early gene expression profiling in these cells can reveal potential drug targets in AML

Fruit fracture biomechanics and the release of Lepidium didymum pericarp-imposed mechanical dormancy by fungi

Mechanical dormancy imposed by a hard fruit pericarp prevents premature seed germination. Here, the authors show that the pericarp of Lepidium didymum prevents germination by limiting water uptake and that dormancy can be released by fungal activity that weakens predetermined breaking zones in the fruit coat

Cognitive reserve, presynaptic proteins and dementia in the elderly

Differences in cognitive reserve may contribute to the wide range of likelihood of dementia in people with similar amounts of age-related neuropathology. The amounts and interactions of presynaptic proteins could be molecular components of cognitive reserve, contributing resistance to the expression of pathology as cognitive impairment. We carried out a prospective study with yearly assessments of N=253 participants without dementia at study entry. Six distinct presynaptic proteins, and the protein–protein interaction between synaptosomal-associated protein 25 (SNAP-25) and syntaxin, were measured in post-mortem brains. We assessed the contributions of Alzheimer's disease (AD) pathology, cerebral infarcts and presynaptic proteins to odds of dementia, level of cognitive function and cortical atrophy. Clinical dementia was present in N=97 (38.3%), a pathologic diagnosis of AD in N=142 (56.1%) and cerebral infarcts in N=77 (30.4%). After accounting for AD pathology and infarcts, greater amounts of vesicle-associated membrane protein, complexins I and II and the SNAP-25/syntaxin interaction were associated with lower odds of dementia (odds ratio=0.36–0.68, P<0.001 to P=0.03) and better cognitive function (P<0.001 to P=0.03). Greater cortical atrophy, a putative dementia biomarker, was not associated with AD pathology, but was associated with lower complexin-II (P=0.01) and lower SNAP-25/syntaxin interaction (P<0.001). In conclusion, greater amounts of specific presynaptic proteins and distinct protein–protein interactions may be structural or functional components of cognitive reserve that reduce the risk of dementia with aging

Molecular Machines in the Synapse: Overlapping Protein Sets Control Distinct Steps in Neurosecretion

Activity regulated neurotransmission shapes the computational properties of a neuron and involves the concerted action of many proteins. Classical, intuitive working models often assign specific proteins to specific steps in such complex cellular processes, whereas modern systems theories emphasize more integrated functions of proteins. To test how often synaptic proteins participate in multiple steps in neurotransmission we present a novel probabilistic method to analyze complex functional data from genetic perturbation studies on neuronal secretion. Our method uses a mixture of probabilistic principal component analyzers to cluster genetic perturbations on two distinct steps in synaptic secretion, vesicle priming and fusion, and accounts for the poor standardization between different studies. Clustering data from 121 perturbations revealed that different perturbations of a given protein are often assigned to different steps in the release process. Furthermore, vesicle priming and fusion are inversely correlated for most of those perturbations where a specific protein domain was mutated to create a gain-of-function variant. Finally, two different modes of vesicle release, spontaneous and action potential evoked release, were affected similarly by most perturbations. This data suggests that the presynaptic protein network has evolved as a highly integrated supramolecular machine, which is responsible for both spontaneous and activity induced release, with a group of core proteins using different domains to act on multiple steps in the release process

Aspergillus Myosin-V Supports Polarized Growth in the Absence of Microtubule-Based Transport

In the filamentous fungus Aspergillus nidulans, both microtubules and actin filaments are important for polarized growth at the hyphal tip. Less clear is how different microtubule-based and actin-based motors work together to support this growth. Here we examined the role of myosin-V (MYOV) in hyphal growth. MYOV-depleted cells form elongated hyphae, but the rate of hyphal elongation is significantly reduced. In addition, although wild type cells without microtubules still undergo polarized growth, microtubule disassembly abolishes polarized growth in MYOV-depleted cells. Thus, MYOV is essential for polarized growth in the absence of microtubules. Moreover, while a triple kinesin null mutant lacking kinesin-1 (KINA) and two kinesin-3s (UNCA and UNCB) undergoes hyphal elongation and forms a colony, depleting MYOV in this triple mutant results in lethality due to a severe defect in polarized growth. These results argue that MYOV, through its ability to transport secretory cargo, can support a significant amount of polarized hyphal tip growth in the absence of any microtubule-based transport. Finally, our genetic analyses also indicate that KINA (kinesin-1) rather than UNCA (kinesin-3) is the major kinesin motor that supports polarized growth in the absence of MYOV

Synaptic E3 Ligase SCRAPPER in Contextual Fear Conditioning: Extensive Behavioral Phenotyping of Scrapper Heterozygote and Overexpressing Mutant Mice

SCRAPPER, an F-box protein coded by FBXL20, is a subunit of SCF type E3 ubiquitin ligase. SCRAPPER localizes synapses and directly binds to Rab3-interacting molecule 1 (RIM1), an essential factor for synaptic vesicle release, thus it regulates neural transmission via RIM1 degradation. A defect in SCRAPPER leads to neurotransmission abnormalities, which could subsequently result in neurodegenerative phenotypes. Because it is likely that the alteration of neural transmission in Scrapper mutant mice affect their systemic condition, we have analyzed the behavioral phenotypes of mice with decreased or increased the amount of SCRAPPER. We carried out a series of behavioral test batteries for Scrapper mutant mice. Scrapper transgenic mice overexpressing SCRAPPER in the hippocampus did not show any significant difference in every test argued in this manuscript by comparison with wild-type mice. On the other hand, heterozygotes of Scrapper knockout [SCR (+/−)] mice showed significant difference in the contextual but not cued fear conditioning test. In addition, SCR (+/−) mice altered in some tests reflecting anxiety, which implies the loss of functions of SCRAPPER in the hippocampus. The behavioral phenotypes of Scrapper mutant mice suggest that molecular degradation conferred by SCRAPPER play important roles in hippocampal-dependent fear memory formation