The influence of linear acceleration on optokinetic nystagmus in human subjects

The influence of linear acceleration on optokinetic nystagmus (OKN) was studied in human subjects. Linear acceleration was applied to the subjects by means of the parallel swing and also by the transfer of the subjects in one direction, either right or left. The cortical form of OKN increased the frequency, amplitude, and eye speed of the slow phase. Of the three, the increase in eye speed was the most pronounced. The subcortical form of OKN was not only increased but was also disturbed by the linear acceleration. When the compensatory eye movement with linear acceleration and the slow phase of OKN were in the same direction, the nystagmus increased remarkably. Contrarily, when the two directions were opposed to each other, nystagmus was inhibited. These results proved that the otolithic organs are not only able to promote but also to inhibit visual function.     

Analysis of developmental processes possibly related to human dental sexual dimorphism in permanent and deciduous canines

Analysis of published odontometric data on human dental sexual dimorphism indicates that this characteristic is most clearly expressed by the canine teeth. Review of the several processes involved in coronal odontogenesis suggests that such dimorphism is related to an absolutely longer period of amelogenesis for both deciduous and permanent dentitions.     

Training new, nonnative speech contrasts: A comparison of the prototype and perceptual fading techniques.

Trained 12 unilingual Canadian francophone listeners (aged 17–23 yrs) to identify the English voiceless and voiced linguadental "th" fricatives, /θ/ and /δ/, using synthetic exemplars of each phoneme. Results show that training with appropriately selected prototype stimuli could produce a linguistically meaningful improvement in a listener's ability to identify new, non-native speech sounds, both natural and synthetic. However, it was not clear whether such training with a single prototype improved performance as effectively as the fading technique used by D. G. Jamieson and D. E. Morosan (see record 1988-00265-001). (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The prototypical pride expression: Development of a nonverbal behavior coding system.

This research provides a systematic analysis of the nonverbal expression of pride. Study 1 manipulated behavioral movements relevant to pride (e.g., expanded posture and head tilt) to identify the most prototypical pride expression and determine the specific components that are necessary and sufficient for reliable recognition. Studies 2 and 3 tested whether the 2 conceptually and empirically distinct facets of pride ("authentic" and "hubristic"; J. L. Tracy & R. W. Robins, 2007a) are associated with distinct nonverbal expressions. Results showed that neither the prototypical pride expression nor several recognizable variants were differentially associated with either facet, suggesting that for the most part, authentic and hubristic pride share the same signal. Together these studies indicate that pride can be reliably assessed from nonverbal behaviors. In the Appendix, the authors provide guidelines for a pride behavioral coding scheme, akin to the Emotion Facial Action Coding System (EMFACS; P. Ekman & E. Rosenberg, 1997) for assessing "basic" emotions from observable nonverbal behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The impact of previous leaders on the evaluation of new leaders: An alternative to prototype matching.

In 2 studies, this research demonstrated the existence of leader transference, a cognitive process whereby mental representations of previous leaders are activated and used for evaluation when new, similar leaders are encountered. The 1st study demonstrated that exposure to a new leader who was similar to a past leader led to erroneous generalization of leader characteristics and associated underlying attributions. The 2nd study showed that expectations of just treatment and abuse were also subject to transfer from old to new, similar leaders, although positive and negative affective responses were not. Results suggested that individuals exposed to a leader who was not reminiscent of an old leader were more likely to use a general leader prototype to form leader expectations, whereas individuals exposed to a leader who was similar to an old leader activated a significant other mental representation for use in making judgments. These results have implications for individual- and relational-level processes as characterized by implicit leadership theory and leader-member exchange theory as well as macro theories of leader succession and organizational culture change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Partial characterization of in vivo chemotactic activity: comparison to human C5a

Spontaneous eosinophil chemotactic activity (SECA) can mediate the directed movement of human eosinophils and neutrophils. Preliminary characterization of SECA has been carried out. SECA is nondialyzable and heat-stable (56 degrees C, 30 min). Chromatography on Sephadex G-75 demonstrated that SECA had elutional and functional properties similar to C5a (prepared from endotoxin-activated normal sera). Polyacrylamide gel electrophoresis (PAGE) with the use of 15% bisacrylamide gels of lyophilized, chemotactically active column fractions demonstrated a single protein band of identical electrophoretic mobility from either SECA or C5a preparations. Enzymatic hydrolysis with carboxypeptidase B, a known inhibitor of C5a activity, significantly decreased chemotactic activities of C5a and SECA. The addition of purified anti-C5 to either SECA or C5a significantly inhibited chemotactic activity. SECA is naturally occurring chemotactic activity identical to human C5a. Thus C5a may be an important source of in vivo chemotactic activity in various inflammatory disorders.     

The venous anatomy of experimental left varicocele: comparison with naturally occurring left varicocele in the human

OBJECTIVE: To determine the effect of experimental left varicocele on the anatomy of the veins serving the rat testis and to compare that anatomy to known patterns of vascular drainage from the human testis with and without varicocele. DESIGN: Vascular maps were made of the effluent vessels from the rat testis in control animals and those with a 30-day experimental left varicocele. Consensus maps were arrived at and these were compared to published reports of the pertinent venous anatomy in humans with and without varicocele. SETTING: Research laboratory. RESULTS: The major route of blood leaving the rat testis was confirmed to be the spermatic vein, but nine common collaterals were also found to exist. Four of these collaterals became more pronounced with experimental varicocele as did several dilated perineal veins. These latter vessels all led to the iliac vein. The vasculature of the rat experimental varicocele model shares some important anatomical features with human varicocele anatomy. CONCLUSIONS: Varicocele in humans and in the rat model causes a redistribution of blood flow from a route primarily out the spermatic vein to routes leading to the iliac vein. The redistribution is similar but not identical.     

The role of stimulus comparison in human perceptual learning: Effects of distractor placement.

Within-subjects procedures were used to assess the influence of stimulus comparison on perceptual learning in humans. In Experiment 1, participants received intermixed (A, A′, A, A′,…) or blocked (B, B,…, B′, B′,…) exposure to pairs of similar female faces. In a subsequent same/different discrimination task, participants were more accurate when the test involved A and A′ than when it involved B and B′ (or novel faces: C and C′). This perceptual learning effect was reduced by placing a visual distractor (*: either another face or a checkerboard) between successive presentations of the faces during the exposure stage (e.g., A – * – A′). The attenuation of the intermixed versus blocked difference was particularly marked when faces were used as the distractor. In Experiment 2, this reduction in perceptual learning was more marked when * was positioned between the pairs of intermixed faces (i.e., A – * – A′) than when it preceded and succeeded those faces (i.e., * – A – A′ – *). These results provide the first direct evidence that the opportunity to compare stimuli plays a causal role in supporting perceptual learning. They also support the specific view that perceptual learning reflects an interaction between a short-term habituation process, that ordinarily biases processing away from the frequently presented common elements and toward their less frequently presented unique elements, and a long-term representational process that reflects this bias. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A comparison of the covalent binding of clozapine and olanzapine to human neutrophils in vitro and in vivo

Covalent binding of a reactive metabolite of clozapine to neutrophils or their precursors is thought to play a role in the development of clozapine-induced agranulocytosis. Immunoblotting studies with an anti-clozapine antiserum detected covalent binding of clozapine to human neutrophils in vitro when HOCl was used to generate clozapine reactive metabolite (major clozapine adducts of 31, 49, 58, 78, 86, 126, 160, and 204 kDa). In addition, incubating neutrophils with clozapine and H2O2 (major clozapine adducts of 49 and 58 kDa) or clozapine, H2O2, and human myeloperoxidase (major clozapine adducts of 31, 49, 58, and 126 kDa) also resulted in covalent binding of clozapine to the neutrophils. The covalent binding of clozapine to neutrophils was inhibited by extracellular glutathione when HOCl, but not H2O2 was used to generate reactive metabolite. We found that the antiserum against clozapine also recognized olanzapine, an antipsychotic drug that forms a similar reactive metabolite to clozapine but has not been associated with induction of agranulocytosis. Repeating the in vitro experiments with olanzapine revealed that the major olanzapine-modified polypeptides had molecular masses of 96, 130-170, and 218 kDa. Only relatively low levels of 31, 49, and 58 kDa adducts were observed. Clozapine-modified polypeptides also were detected in neutrophils from patients being treated with clozapine. A major 58-kDa clozapine-modified polypeptide was detected in all patients tested. In contrast, no drug-modified polypeptides were detected in neutrophils from patients taking olanzapine. The differences in covalent binding exhibited by the two compounds and, in particular, the lack of olanzapine binding to human neutrophils in vivo may help to explain the difference in toxicity of these two drugs.     

Susceptibility of human proximal tubular cells to hypoxia: effect of hypoxic preconditioning and comparison to glomerular cells

Three elements are crucial for the programmed frameshifting in translation of dnaX mRNA: a Shine-Dalgarno (SD)-like sequence, a double-shift site, and a 3' structure. The conformation of the mRNA containing these three elements was investigated using chemical and enzymatic probes. The probing data show that the structure is a specific stem-loop. The bottom half of the stem is more stable than the top half of the stem. The function of the stem-loop was further investigated by mutagenic analysis. Reducing the stability of the bottom half of the stem strongly effects frameshifting levels, whereas similar changes in the top half are not as effective. Stabilizing the top half of the stem gives increased frameshifting beyond the WT efficiency. The identity of the primary RNA sequence in the stem-loop is unimportant, provided that the overall structure is maintained. The calculated stabilities of the variant stem-loop structures correlate with frameshifting efficiency. The SD-interaction and the stem-loop element act independently to increase frameshifting in dnaX.     

Mathematical and connectionist models of human memory: a comparison

Recent convolution-based models of human memory (e.g. Lewandowsky & Murdock, 1989), have accounted for a wide range of data. However such models require the relevant mathematical operations to be provided to the network. Connectionist models, in contrast, have generally addressed different data, and not all architectures are appropriate for modelling single-trial learning. Furthermore, they tend to exhibit catastrophic interference in multiple list learning. In this paper we compare the ability of convolution-based models and DARNET (Developmental Associative Recall NETwork), to account for human memory data. DARNET is a connectionist approach to human memory in which the system gradually learns to associate vectors, in one trial, into a memory trace vector. Either of the vectors can than be retrieved. It is shown that the new associative mechanism can be used to account for a wide range of relevant experimental data as successfully as can convolution-based models with the same higher-level architectures. Limitations of the models are also addressed.     

Primary human herpesvirus 7 infection: a comparison of human herpesvirus 7 and human herpesvirus 6 infections in children

Atrial fibrillation is an important and independent risk factor for cerebrovascular disease and vascular dementia. There is increasing evidence that atrial fibrillation is associated with an increased risk of asymptomatic or silent cerebral infarction and as a result may confer an increased risk of progressive cognitive impairment on a person. In this study we sought to determine whether this hypothesis could be explored in a prospective case controlled design. Twenty seven patients with non-valvular atrial fibrillation (NVAF) and no history of stroke, transient ischaemic attack, dementia, and thyrotoxicosis were compared with 54 age and sex matched controls in sinus rhythm. All cases underwent clinical examination, ECG, and psychological assessment using a battery of nine neuropsychological tests. Between group analysis and a comparison of mean test scores of paired controls with cases were undertaken. The presence of atrial fibrillation was consistently associated with poorer performances on all the subtests of the neuropsychological battery. There was no association between duration of atrial fibrillation and performance. These results provide evidence to justify further examination of the hypothesis in a larger prospective study to determine whether antithrombotic therapy may protect against cognitive decline in patients at maximal risk of silent cerebral ischaemia and associated cognitive decline.     

Disturbed release of growth hormone in mature dogs: a comparison with congenital growth hormone deficiency

An acquired defect in growth hormone secretion in mature dogs has been associated with some forms of generalised alopecia. In an attempt to elucidate the pathogenesis of the disturbance in growth hormone release, the plasma concentrations of growth hormone and insulin-like growth factor I (IGF-I) were measured in two seven-year-old poodles with alopecia and, for comparison, in two young German sheperd dogs with congenital hyposomatotropism (pituitary dwarfism). In the poodles the basal concentrations of growth hormone were low, although often above the detection limit of the assay. The concentrations of IGF-I were in the reference range for healthy poodles. No growth hormone could be detected in the plasma of the German sheperd dogs and the concentrations of IGF-I were very low. Stimulation with clonidine and growth hormone releasing hormone (GHRH) before and after repeated injections of GHRH did not result in significant increases in growth hormone concentrations in plasma. The concentrations of growth hormone in the poodles fluctuated at low levels during the test period. In the German sheperd dogs the levels of growth hormone remained unmeasurable during the stimulation tests. It was concluded that in the two poodles the basal concentrations of growth hormone were sufficient to maintain normal IGF-I concentrations, and thus the release of growth hormone was considered appropriate. Based upon measurements of urinary corticoids and a review of the literature it is suggested that the lack of a growth hormone response to stimulation was due to the enhanced release of somatostatin as a result of mild and fluctuating hyperadrenocorticism.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparison of the enantioselectivities of human deoxycytidine kinase and human cytidine deaminase

The stereoselectivities of recombinant human deoxycytidine kinase (EC 2.7.1.74) (dCK) and of recombinant human cytidine deaminase (EC 3.5.4.5) (CDA) were investigated with respect to a series of cytidine analogs, most of them having the unnatural L-stereochemistry. The enantioselectivity of dCK was always low and generally favored the L-enantiomers in the case of beta-2',3'-dideoxycytidine (beta-ddC), 5-fluoro-beta-2',3'-dideoxycytidine (beta-FddC) and beta-cytidine (beta-riboC). Concerning beta-2'-deoxycytidine, dCK showed a preference for the D-enantiomer. All other examined beta-L-cytidine analogs, [1-beta-L-lyxofuranosyl cytosine (beta-L-lyxoC), l-beta-L-xylofuranosyl cytosine (beta-L-xyloC), and 5-fluoro-1-beta-L-xylofuranosyl cytosine (beta-L-Fxylo C)], were substrates of dCK regardless of the nature of the pentose. None of the studied alpha-L-anomers (alpha-L-riboC, alpha-L-araC, alpha-L-lyxoC, or alpha-L-xyloC) was a substrate of dCK. Contrasting with the relaxed enantioselectivity of dCK, CDA had a strict requirement for D-cytidine analogs since none of the already listed beta-L- or alpha-L analogs was a substrate or an inhibitor of the enzyme. The conjunction of the preceding stereochemical properties of dCK and CDA confers to L-cytidine analogs important potentialities in antiviral and anticancer therapies.