Refractive Errors Affect the Vividness of Visual Mental Images

The hypothesis that visual perception and mental imagery are equivalent has never been explored in individuals with vision defects not preventing the visual perception of the world, such as refractive errors. Refractive error (i.e., myopia, hyperopia or astigmatism) is a condition where the refracting system of the eye fails to focus objects sharply on the retina. As a consequence refractive errors cause blurred vision.We subdivided 84 individuals according to their spherical equivalent refraction into Emmetropes (control individuals without refractive errors) and Ametropes (individuals with refractive errors). Participants performed a vividness task and completed a questionnaire that explored their cognitive style of thinking before their vision was checked by an ophthalmologist. Although results showed that Ametropes had less vivid mental images than Emmetropes this did not affect the development of their cognitive style of thinking; in fact, Ametropes were able to use both verbal and visual strategies to acquire and retrieve information. Present data are consistent with the hypothesis of equivalence between imagery and perception.     

Molecular evidence and clinical importance of β‐arrestins expression in patients with acromegaly

β‐arrestins seem to have a role in endocytosis and desensitization of somatostatin receptor subtype 2 (sst2) and could be associated with the responsiveness to somatostatin receptor ligands (SRL) in patients with acromegaly. To investigate the in vivo correlation between β‐arrestins 1 and 2 with sst2, sst5 and dopamine receptor subtype 2 (D2) expressions, and the association of β‐arrestins with response to first‐generation SRL and invasiveness in somatotropinomas. β‐arrestins 1 and 2, sst2, sst5 and D2 mRNA expressions were evaluated by quantitative real‐time RT‐PCR on tumoral tissue of 96 patients. Moreover, sst2 and sst5 protein expressions were also evaluated in 40 somatotropinomas by immunohistochemistry. Response to SRL, defined as GH <1 μg/l and normal IGF‐I levels, was assessed in 40 patients. The Knosp‐Steiner criteria were used to define invasiveness. Median β‐arrestin 1, β‐arrestin 2, sst2, sst5 and D2 mRNA copy numbers were 478; 9375; 731; 156 ; and 3989, respectively. There was a positive correlation between β‐arrestins 1 and 2 (R = 0.444, P < 0.001). However, no correlation between β‐arrestins and sst2, sst5 (mRNA and protein levels) or D2 was found. No association was found between β‐arrestins expression and SRL responsiveness or tumour invasiveness. Although previous data suggest a putative correlation between β‐arrestins and sst2, our data clearly indicated that no association existed between β‐arrestins and sst2, sst5 or D2 expression, nor with response to SRL or tumour invasiveness. Therefore, further studies are required to clarify whether β‐arrestins have a role in the response to treatment with SRL in acromegaly.     

The problem of isolation of the X virus inhibitor from potato leaf sap

Using moving boundary electrophoresis in a veronal buffer, pH 8·5, of 0·05 ionic strength and at 4·3 mA, we succeeded in separating the inhibitor, which was obtained by fractionation on a Sephadex G-50 column, into four components. The two most substantial components represent 25% and 65% respectively from the separated proteins as a whole. The heterogeneity of the inhibitor was proved by analytical ultracentrifugation, too. The ionex chromatography was applied for the quantitative separation of the inhibitor. We used ionex chromatography on DEAE Cellulose the concentration gradient being 0–1m NaCl in a 0·01m phosphate buffer, pH 7·3, and on DEAE Sephadex A-50 using the same concentration gradient in a phosphate buffer, of 0·1 ionic strength and pH 7·3. In both cases four components were obtained. The most substantial component, representing 65% of the whole analysed material, was eluted at the concentration 0·15–0·3m NaCl, and was electrophoretically homogenous and showed the most effective inhibitory ability.     

The hierarchy of structural transitions induced in cytochrome c by anionic phospholipids determines its peroxidase activation and selective peroxidation during apoptosis in cells

Activation of peroxidase catalytic function of cytochrome c (cyt c) by anionic lipids is associated with destabilization of its tertiary structure. We studied effects of several anionic phospholipids on the protein structure by monitoring (1) Trp59 fluorescence, (2) Fe-S(Met80) absorbance at 695 nm, and (3) EPR of heme nitrosylation. Peroxidase activity was probed using several substrates and protein-derived radicals. Peroxidase activation of cyt c did not require complete protein unfolding or breakage of the Fe-S(Met80) bond. The activation energy of cyt c peroxidase changed in parallel with stability energies of structural regions of the protein probed spectroscopically. Cardiolipin (CL) and phosphatidic acid (PA) were most effective in inducing cyt c peroxidase activity. Phosphatidylserine (PS) and phosphatidylinositol bisphosphate (PIP2) displayed a significant but much weaker capacity to destabilize the protein and induce peroxidase activity. Phosphatidylinositol trisphosphate (PIP3) appeared to be a stronger inducer of cyt c structural changes than PIP2, indicating a role for the negatively charged extra phosphate group. Comparison of cyt c-deficient HeLa cells and mouse embryonic cells with those expressing a full complement of cyt c demonstrated the involvement of cyt c peroxidase activity in selective catalysis of peroxidation of CL, PS, and PI, which corresponded to the potency of these lipids in inducing cyt c's structural destabilization.     

A study of extracellular matrix-cell adhesion peptidic epitopes related to human serum amyloid A (SAA)

Summary Serum amyloid A (SAA), an acute-phase protein, exists normally in the serum while complexed with high-density lipoprotein 3 (SAA-HDL₃). Its levels increase markedly during inflammatory diseases. The pentapeptide Tyr-Ile-Gly-Ser-Asp (YIGSR-like) and the tripeptide Arg-Gly-Asn (RGD-like), related to the cell adhesion domains of laminin and fibronectin, respectively, exist in SAA within close proximity (YIGSDKYFHARGNY; amino acid residues 29–42). A structure-function study of linear and head-to-tail cyclic peptides, related to the amino acid residues 29–42) and 70–76 (GRGAEDS) of human SAA, was performed in order to evaluate their ability to inhibit adhesion of human T-lymphocytes to surfaces coated with extracellular matrix purified from bovine corneal cells.     

Polymorphic Cytochromes P450 and Drugs Used in Psychiatry

1. The cytochrome P450 monooxygenases, CYP2D6, CYP2C19, and CYP2C9, display polymorphism. CYP2D6 and CYP2C19 have been studied extensively, and despite their low abundance in the liver, they catalyze the metabolism of many drugs.2. CYP2D6 has numerous allelic variants, whereas CYP2C19 has only two. Most variants are translated into inactive, truncated protein or fail to express protein.3. CYP2C9 is expressed as the wild-type enzyme and has two variants, in each of which one amino acid residue has been replaced.4. The nucleotide base sequences of the cDNAs of the three polymorphic genes and their variants have been determined, and the proteins derived from these genes have been characterized.5. An absence of CYP2D6 and/or CYP2C19 in an individual produces a poor metabolizer (PM) of drugs that are substrates of these enzymes.6. When two drugs that are substrates for a polymorphic CYP enzyme are administered concomitantly, each will compete for that enzyme and competitively inhibit the metabolism of the other substrate. This can result in toxicity.7. Patients can be readily phenotyped or genotyped to determine their CYP2D6 or CYP2C19 enzymatic status. Poor metabolizers (PMs), extensive metabolizers (EMs), and ultrarapid metabolizers (URMs) can be identified.8. Numerous substrates and inhibitors of CYP2D6, CYP2C19, and CYP2C9 are identified.9. An individual's diet and age can influence CYP enzyme activity.10. CYP2D6 polymorphism has been associated with the risk of onset of various illnesses, including cancer, schizophrenia, Parkinson's disease, Alzheimer's disease, and epilepsy.     

Eavesdropping in solitary large carnivores: Black bears advance and vocalize toward cougar playbacks

Large carnivore behavioral responses to the cues of their competitors are rarely observed, but may mediate competition between these top predators. Playback experiments, currently limited to interactions involving group‐living large carnivores, demonstrate that attending to cues indicative of the immediate presence of heterospecific competitors plays a substantial role in influencing competition among these species. Group‐living species vocalize regularly to signal to one another, and competitors can readily “eavesdrop” on these acoustic cues. Solitary large carnivores also vocalize to conspecifics, but much less frequently, reducing the ease with which heterospecific competitors can eavesdrop. Eavesdropping could nonetheless play a substantive role in mediating competition among solitary large carnivores if the benefits of responding to the acoustic cues of heterospecific competitors (reducing risk or locating resources) are sufficiently large. Behavioral interactions between solitary large carnivore species are almost never observed, and there have been no experimental tests of their reactions to cues indicative of the immediate presence of other solitary large carnivores. We used an automated playback system to test the responses of a solitary large carnivore (black bear, Ursus americanus) to vocalizations of their similarly solitary competitor (cougar, Puma concolor), presenting both cougar and control vocalizations to free‐living bears foraging along shorelines in British Columbia, Canada. Both mothers with cubs and solitary bears were significantly more likely to advance and vocalize toward cougar than control playbacks, mothers producing one or both of two distinct vocalizations and solitary bears producing just one. Cougars could either represent a potential risk to bears (particularly cubs), or a source of resources, as bears are known to regularly scavenge cougar kills. Our results are consistent with bears eavesdropping on cougars for both these reasons. As with group‐living species, eavesdropping may be common among solitary large carnivores, and may be an important driver of competition between these species.