Evidence for anatomical but not functional asymmetry in the hemidecorticate rat.

Studied 51 male Long-Evans rats with unilateral ablation of the left or right cerebral neocortex or left or right hippocampus using a battery of tests of spatial orientation, motor coordination, and social behavior, including Morris water task, radial arm maze, feeding, narrow beam traversing, puzzle latches, hoarding, grooming, nest building, running wheel activity, male–male interaction, and shock-induced aggression. Comparison of the brains of operated and control Ss confirmed previous suggestions that the right hemisphere of the rat is bigger and may have different connections than the left hemisphere. Despite the morphological asymmetries, comparison of the behavior of Ss with right and left hemidecortication and right and left hippocampal lesions failed to show a single instance of functional asymmetry in the rat brain. These behavioral results contrast with previous reports of functional asymmetry in the control of activity, orientation, and rotation. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual asymmetry in psychosis-prone college students: Evidence for left-hemisphere overactivation.

The hypothesis that psychosis-prone students demonstrate a pattern of exaggerated perceptual asymmetry across both left- and right-hemisphere dichotic-listening tasks (consonant-vowel [CV] and tonal contour discrimination) was investigated. Ss who scored high on the Perceptual Aberration or Magical Ideation scale or both (n?=?20) demonstrated a significantly exaggerated right-ear advantage on a CV task in relation to normal control Ss (n?=?27) but showed a reduced left-ear advantage on a tone task. The hypothesis of exaggerated functional lateralization across hemispheres in the psychosis-prone Ss was not supported, but the results are consistent with a hypothesis of left hemisphere overactivation in this sample. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny of cerebral dominance: Evidence from time-sharing asymmetry in children.

Used a dual-task procedure as a measure of speech lateralization in 151 normal, right-handed, 3–12 yr old children. Ss engaged in unimanual finger tapping with and without concurrent speech. It was hypothesized that if speech is left lateralized, talking should disrupt right-hand tapping (an instance of intrahemispheric interference) more than left-hand tapping (an instance of interhemispheric interference). Results for 2 different verbal tasks show the predicted overall asymmetry but no developmental trend in degree of asymmetry. The data suggest that lateralization is as marked in young children as in older children. About 70% of the Ss showed the predicted effect; there was no significant change in incidence as a function of grade level. Analyses of verbal production indicated that the performance asymmetry could not be attributed to an asymmetrical trade-off between talking and tapping. No sex differences in performance asymmetry were found. The results contradict the traditional model of progressive lateralization but corroborate the developmental invariance frequently observed using perceptual measures of language lateralization. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for association of HLA-A2 allele with onset age of Alzheimer's disease

Our earlier studies had suggested a possible association between the HLA-A2 allele and Alzheimer's disease (AD). In the present study we tested the hypothesis that A2 is associated with earlier AD onset. We performed two independent studies: a collaborative study with 111 patients and a confirmatory study with 96 patients. We found similar patterns of reduced age at onset as a function of A2 in both data sets. Overall, A2 was associated with a significant 3-year shift to earlier onset. The effects of A2 and epsilon 4 on age at onset appeared additive. Our results suggest A2, or a closely linked gene, modulates onset age of AD. Association with A2 would suggest an immune/inflammatory response mechanism for AD.     

Lateralization of perinatal cerebral insult and cognitive asymmetry: Evidence from neuroimaging.

The current investigation incorporated 2 studies. The objective of Study 1 was to explore lateralizalion of cerebral insult in the preterm neonate. To attain this goal, the radiological records of 148 premature infants with intracranial hemorrhage were retrospectively reviewed. Statistical analyses revealed that the lesion tended to be observed initially in the left hemisphere. Bilateral hemorrhage tended to be asymmetrical, with more pathological changes observed on the left. Study 2 examined the cognitive outcome of unilateral hemorrhage in a subsample of 20 children. Analyses revealed a link between lateralization of hemorrhage and pattern of cognitive asymmetry. Possible origins of increased left hemisphere vulnerability and implications of the reported cognitive changes for the onset of hemispheric specialization are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female choice for spot asymmetry in the Trinidadian guppy

The overexpression in tumor cells of (proto)-oncogenic receptor tyrosine kinases such as epidermal growth factor receptor (EGFR) or ErbB2/neu (also known as HER-2) is generally thought to contribute to the development of solid tumors primarily through their effects on promoting uncontrolled cell proliferation. However, agents that antagonize the function of the protein products encoded by these (proto)-oncogenes are known to behave in vivo in a cytotoxic-like manner. This implies that such oncogenes may regulate critical cell survival functions, including angiogenesis. The latter could occur as a consequence of regulation of relevant growth factors by such oncogenes. We therefore sought to determine whether EGFR or ErbB2/neu may contribute to tumor angiogenesis by examining their effects on the expression of vascular endothelial cell growth factor (VEGF)/vascular permeability factor (VPF), one of the most important of all known inducers of tumor angiogenesis. We found that in vitro treatment of EGFR-positive A431 human epidermoid carcinoma cells, which are known to be heavily dependent on VEGF/VPF in vivo as an angiogenesis growth factor, with the C225 anti-EGFR neutralizing antibody caused a dose-dependent inhibition of VEGF protein expression. Prominent suppression of VEGF/VPF expression in vivo, as well as a significant reduction in tumor blood vessel counts, were also observed in established A431 tumors shortly after injection of the antibody as few as four times into nude mice. Transformation of NIH 3T3 fibroblasts with mutant ErbB2/neu, another EGFR-like oncogenic tyrosine kinase, resulted in a significant induction of VEGF/VPF, and the magnitude of this effect was further elevated by hypoxia. Moreover, treatment of ErbB2/neu-positive SKBR-3 human breast cancer cells in vitro with a specific neutralizing anti-ErbB2/neu monoclonal antibody (4D5) resulted in a dose-dependent reduction of VEGF/VPF protein expression. Taken together, the results suggest that oncogenic properties of EGFR and ErbB2/neu may, at least in part, be mediated by stimulation of tumor angiogenesis by up-regulating potent angiogenesis growth factors such as VEGF/VPF. These genetic changes may cooperate with epigenetic/environmental effects such as hypoxia to maximally stimulate VEGF/VPF expression. Therapeutic disruption of EGFR or ErbB2/neu protein function in vivo may therefore result in partial suppression of angiogenesis, a feature that could enhance the therapeutic index of such agents in vivo and endow them with anti-tumor effects, the magnitude of which may be out of proportion with their observed cytostatic effects in monolayer tissue culture.     

Defects in the determination of left-right asymmetry

Approximately 70% to 80% of Rh-positive adults and children with acute or chronic immune thrombocytopenic purpura or HIV-related thrombocytopenia respond to infusions of anti-D immunoglobulin. The speed of onset of response is slower than that seen with intravenous immunoglobulin. Anti-D immunoglobulin is well tolerated, with occasional adverse reactions similar to those seen in treatment with polyclonal intravenous immunoglobulin, but anemia requiring blood transfusion can occur. Response is generally better in younger patients and those who have responded to other forms of treatment. Inhibition of Fc receptor-mediated platelet destruction by anti-D immunoglobulin-opsonized erythrocytes is the most likely mechanism of action, although the relative ineffectiveness of a monoclonal anti-D immunoglobulin preparation in treatment of immune thrombocytopenic purpura suggests that other mechanisms may exist. Hepatitis C has been transmitted by intravenous anti-D immunoglobulin preparations when used in the prevention of Rh immunization, prior to the introduction of screening donor plasma for hepatitis C virus antibodies. However, an intravenous solvent-detergent-treated preparation is now available.     

Physical asymmetry of the crystallographic

The texture of a mill-produced, Nb-bearing, interstitial-free, hot-rolled sheet steel was evaluated at a number of sheet thickness positions. The texture was also studied following laboratory cold rolling and following recrystallization. A “nonsymmetric case” crystallite orientation distribution function analysis applicable to the analysis on nonsymmetric pole figures was used. While sheet steels are generally assumed to have orthotropic physical symmetry, it was found that an appreciable degree of physical asymmetry existed. The asymmetry was with respect to the rolling direction (RD) and normal direction (ND) mirror planes, while transverse direction (TD) mirror-plane symmetry existed.