Modification of digital music files for use in human temporary threshold shift studies

An exposure that is reproducible across clinical/laboratory environments, and appealing to subjects, is described here. Digital music files are level-equated within and across songs such that playlists deliver an exposure that is consistent across time. Modified music is more pleasant to listen to than pure tones or shaped noise, and closely follows music exposures subjects may normally experience. Multiple therapeutics reduce noise-induced hearing loss in animals but human trial design is complicated by limited access to noise-exposed subject populations. The development of standard music exposure parameters for temporary threshold shift studies would allow comparison of protection across agents with real-world relevant stimuli in human subjects.

Inertia and memory in ambiguous visual perception

Perceptual multistability during ambiguous visual perception is an important clue to neural dynamics. We examined perceptual switching during ambiguous depth perception using a Necker cube stimulus, and also during binocular rivalry. Analysis of perceptual switching time series using variance-sample size analysis, spectral analysis and time series shuffling shows that switching times behave as a 1/f noise and possess very long range correlations. The long memory feature contrasts sharply with the traditional satiation models of multistability, where the memory is not incorporated, as well as with recently published models of multistability and neural processing, where memory is excluded. On the other hand, the long memory feature favors the concept of "dynamic core" or coalition of neurons, where neurons form transient coalitions. Perceptual switching then corresponds to replacement of one coalition of neurons by another. The inertia and memory measures the stability of a coalition: a strong and stable coalition has to be won over by another similarly strong and stable coalition, resulting in long switching times. The complicated transient dynamics of competing coalitions of neurons may be addressable using a combination of functional imaging, measurement of frequency-tagged magnetoencephalography and frequency-tagged encephalography, simultaneous recordings of groups of neurons in many areas of the brain, and concepts from statistical mechanics and nonlinear dynamics theory.

Education in end-of-life care: bridging disciplinary and institutional boundaries

This paper describes the development of an interdisciplinary, interinstitutional seminar in palliative care for South Dakota students in medicine, nursing, pharmacy, chaplaincy, and social work. Student outcomes from six seminars conducted during 2001-2004 are reported, and recommendations for future educational efforts are outlined.

Inhibitory neurophysiological deficit as a phenotype for genetic investigation of schizophrenia

Many investigators have proposed that biological endophenotypes might facilitate the genetic analysis of schizophrenia. A deficit in the inhibition of the P50 evoked response to repeated auditory stimuli has been characterized as a neurobiological deficit in schizophrenia. This deficit is linked to a candidate gene locus, the locus of the alpha7-nicotinic cholinergic receptor subunit gene on chromosome 15q14. Supportive evidence has been found by other investigators, including: 1) linkage of schizophrenia to the same locus; 2) linkage of bipolar disorder to the locus; and 3) replication of the existence of this neurobiological deficit and its relation to broader neuropsychological deficits in schizophrenia. It is certain that there are many genetic factors in schizophrenia and bipolar disorder; what is needed is a complete and precise description of the contribution of each individual factor to the pathophysiology of these illnesses.

CADASIL: neuropsychological findings in three generations of an affected family

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary brain disease with a variety of neurologic and psychiatric manifestations. We studied 3 members of a family who each had leukoencephalopathy on neuroimaging studies and a characteristic mutation for CADASIL in the notch 3 region of chromosome 19q12. In all 3 cases, neurobehavioral impairment dominated the clinical picture, and a pattern of psychiatric dysfunction heralding cognitive decline emerged. Neuropsychological evaluation revealed diverse deficits, but a profile of frontal lobe dysfunction, declarative memory impairment suggestive of a retrieval deficit, and relatively preserved language was evident. These cases provide a cross-sectional study of the evolution of CADASIL, and suggest that, as in other diseases characterized by white matter dementia, psychiatric dysfunction may occur initially, followed by pervasive cognitive dysfunction later in the course of the disease. CADASIL should be considered in young adults with unexplained leukoencephalopathy on neuroimaging studies, and in those with neurobehavioral dysfunction and a suggestive family history.

Magnetization measurements of magnetic two-dimensional electron gases

We directly measure the magnetization of both the conduction electrons and Mn2+ ions in (Zn,Cd,Mn)Se two-dimensional electron gases (2DEGs) by integrating them into ultrasensitive micromechanical magnetometers. The interplay between spin and orbital energy in these magnetic 2DEGs causes Landau level degeneracies at the Fermi energy. These Landau level crossings result in novel features in the de Haas-van Alphen oscillations, which are quantitatively reproduced by a simple model.

Smooth pursuit eye movements in schizophrenia and attentional dysfunction: adults with schizophrenia, ADHD, and a normal comparison group

BACKGROUND

Smooth pursuit eye movement (SPEM) abnormalities are found in schizophrenia. These deficits often are explained in the context of the attentional and inhibitory deficits central to schizophrenia psychopathology. It remains unclear, however, whether these attention-associated eye movement abnormalities are specific to schizophrenia or are a nonspecific expression of attentional deficits found in many psychiatric disorders. Adult attention-deficit/hyperactivity disorder (ADHD) is an alternative disorder with chronic attentional and inhibitory dysfunction. Thus, a comparison of SPEM in adult schizophrenia and adult ADHD will help assess the specificity question.

METHODS

SPEM is recorded during a 16.7 degrees per second constant velocity task in 17 adults with ADHD, 49 adults with schizophrenia, and 37 normal adults; all groups included individuals between ages 25-50 years.

RESULTS

Smooth pursuit gain and the frequency of anticipatory and leading saccades are worse in schizophrenic subjects, with normal and ADHD subjects showing no differences on these variables.

CONCLUSIONS

Many attention-associated SPEM abnormalities are not present in most subjects with ADHD, supporting the specificity of these findings to the attentional deficits seen in schizophrenia.

Eye movement task measures inhibition and spatial working memory in adults with schizophrenia, ADHD, and a normal comparison group

Schizophrenia and attention deficit/hyperactivity disorder (ADHD) are both associated with deficits in inhibition and working memory, although in ADHD the working memory deficit is hypothesized to be secondary to the inhibitory deficit. This similarity in cognitive processes has been paralleled by similarities across the two groups in the performance of working memory and inhibition tasks. The delayed oculomotor response task is an alternative task, which may allow greater separation of working memory from inhibitory components, and thus its use may provide additional information on primary vs. secondary deficits in these disorders. Ten young adult ADHD sufferers, 10 schizophrenic subjects, and 10 normal subjects were matched on age, gender, and education. Eye movements were recorded during delayed oculomotor response tasks with 1- and 3-s delays. Both the ADHD and the schizophrenic subjects demonstrated dis-inhibition (an increased percentage of premature saccades); however only schizophrenic subjects demonstrated an impaired working memory (decreased spatial accuracy of the remembered saccade). The results are consistent with the hypothesis that working memory is a primary deficit in schizophrenia, but secondary to the inhibitory deficit in ADHD.

The P50 auditory event-evoked potential in adult attention-deficit disorder: comparison with schizophrenia

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) and schizophrenia are both conceptualized as disorders of attention. Failure to inhibit the P50 auditory event-evoked response, extensively studied in schizophrenia, could also occur in ADHD patients, if these two illnesses have common underlying neurobiological substrates.

METHODS

This study examined the inhibition of the P50 auditory event-evoked potential in 16 unmedicated adults with ADHD, 16 schizophrenic outpatients, and 16 normal control subjects. Auditory stimuli were presented in a paired stimulus, conditioning-testing paradigm.

RESULTS

The amplitude of initial or conditioning P50 response did not differ between the three groups; however, significant effects of psychiatric diagnosis on the amplitude of the test response and the ratio of the test to the conditioning response amplitudes were observed. Schizophrenic patients' P50 ratios and test amplitudes were higher than both the ADHD and normal groups.

CONCLUSIONS

Adults with ADHD do not have the inhibitory deficit seen in patients with schizophrenia, suggesting that the mechanism of attentional disturbance in the two illnesses may be fundamentally different.

Familial transmission of risk factors in the first-degree relatives of schizophrenic people

Schizophrenia is a complex illness with multiple pathophysiologic factors that contribute to its psychopathology. One strategy to identify these factors is to observe them in isolation from each other, by characterizing their expression in the relatives of schizophrenic probands. By Mendel's second law, each genetic factor should be independently distributed in a sibship, so that each can be observed by itself, uncomplicated by the general problems of the illness. Such independently distributed phenotypes are obviously useful for genetic analyses; however, they can also be considered together, to model how various brain dysfunctions may combine to produce psychoses. In addition to a sensory gating deficit linked to the alpha 7-nicotinic acetylcholine receptor locus, schizophrenics and their families have a number of other deficits, including decreased hippocampal volume on magnetic resonance images and increased plasma levels of the dopamine metabolite homovanillic acid. Although such research is far from complete, a heuristic model combining a sensory gating deficit, decreased hippocampal neuron capacity, and increased dopaminergic neurotransmission is consonant with current understanding of the neuropsychology of schizophrenia.

Comparison of incremental and bolus dose inhaled allergen challenge in asthmatic patients

BACKGROUND

Attenuation of airway responses to inhaled allergen is increasingly used to evaluate anti-asthma drugs. Many studies use different allergen challenge methods and the presence of the late asthmatic response can be identified by a screening challenge with inhalation of incremental doses of allergen. Once defined, subsequent challenges are often administered as a constant dose based on the dose from the screening challenge. Previously, constant dose challenges have been employed but never validated.

OBJECTIVE

A comparative study of two methods of delivering inhaled allergen by evaluating the responses of an incremental dose allergen challenge and the same cumulative dose administered as a bolus over a single inhalation.

METHODS

Thirty-five male patients with mild allergic asthma underwent incremental dose challenge followed 3-6 weeks later by a bolus dose challenge. Bronchoconstrictor responses were expressed as the maximum percentage fall in FEV1 from baseline during the early (0-2 h) and late (4-10 h) asthmatic responses and area under the percentage change in FEV1-time curve (AUC).

RESULTS

There were no significant differences between the challenges. The mean +/- SEM fall in FEV1 following incremental and bolus dose challenge was 33.1 +/- 1.8% and 29.9 +/- 2.2% during the early response, and 36.9 +/- 2.4% and 34.0 +/- 3.1% during the late response, respectively. The mean +/- SEM AUC following incremental and bolus dose challenge was 35 +/- 3 and 33 +/- 3 Delta%FEV1/h for the AUC0-2 h, 147 +/- 12 and 139 +/- 16 Delta%FEV1/h for the AUC4-10 h, and 204 +/- 14 and 190 +/- 19 Delta%FEV1/h for the AUC0-10 h, respectively.

CONCLUSION

Bolus dose allergen challenge is a safe method to administer inhaled allergen in clinical trials with a valid response when compared with incremental dose allergen challenge.

Measurement models for ultrasonic nondestructive evaluation

The article reviews ways to use the electromechanical reciprocity relation to construct theoretical models of measurement processes in ultrasonic nondestructive evaluation. This relationship is important because it connects the change in the voltages measured at the electrical terminal of the transducer to the perturbation in the mechanical wavefield caused by the change in the propagation environment. It does so by mixing an unperturbed reference wavefield with one containing the perturbed wavefield. Two problems of progressive difficulty are explored. We begin by investigating the imaging of a one-dimensional sinusoidal fluid-solid interface using a cylindrically focused beam and continue by developing a model of the imaging of the mechanical properties of a two-dimensional, thin solid film using a confocal arrangement of point-focused transducers. This last problem uses an approximation to the thin solid film, which reduces its mechanical response to one similar to that of a membrane. Integral relations are given that can be used to form integral equations or to generate asymptotic approximations to the particle displacements and stresses in the film.

The effects of age on a smooth pursuit tracking task in adults with schizophrenia and normal subjects

BACKGROUND

Performance during a smooth pursuit eye movement (SPEM) task has been proposed as a marker of genetic risk for schizophrenia, although the precise component of SPEM tracking most associated with genetic risk remains undetermined. Normal adult aging is associated with deterioration on SPEM tasks; it remains unclear whether investigations of SPEM abnormalities will allow inclusion of older subjects in genetic studies. This study examines 1) the effect of normal aging on several components of SPEM performance; and 2) whether schizophrenic-normal differences found in young adults continue over a broad adult age span.

METHODS

SPEM was recorded during a 16.7 degrees per sec constant velocity task in 64 normal adults, ages 18 to 79 years, and 58 schizophrenic subjects, ages 18 to 70 years.

RESULTS

Smooth pursuit gain, the percent of total eye movements due to catch-up saccades, the frequency of large anticipatory saccades, and the frequency of leading saccades all deteriorate with increasing age. After correction for age, schizophrenic to control differences persist on most eye movement variables with the largest effect sizes for leading saccades (1.56) and smooth pursuit gain (1.17).

CONCLUSIONS

The tendency to use saccades to anticipate target motion, even in small steps (leading saccades), deserves further attention as a potential marker useful in genetic analyses.

Evidence for bilineal inheritance of physiological indicators of risk in childhood-onset schizophrenia

Childhood-onset schizophrenia is proposed to be associated with increased genetic loading compared with adult-onset schizophrenia because of its earlier age of onset and generally greater severity of symptoms. Diminished suppression of P50 auditory evoked responses to repeated stimuli and elevated anticipatory saccades during smooth pursuit eye movements are markers of genetic risk that are found in members of families with schizophrenia even in the absence of the full clinical disorder and appear to be transmitted in a single gene autosomal dominant fashion. Adult-onset schizophrenia is generally associated with one parent who demonstrates abnormal P50 sensory gating and elevated anticipatory saccades and one parent who is normal on the physiologic measures (i.e., unilineal inheritance). This study investigates whether childhood-onset schizophrenia is similarly unilineal or is associated with the inheritance of genetic risk factors from both parents (i.e., bilineal inheritance). Ten childhood-onset schizophrenic probands and their parents were studied. Their P50 sensory gating and anticipatory saccades were compared with adult-onset schizophrenic probands and their parents. Bilineality, measured as physiological impairment in both parents, occurred more frequently in childhood-onset probands than in adult-onset probands for both P50 sensory gating deficits (60% versus 13%) and elevated anticipatory saccades (60 versus 0%). Additionally, childhood-onset schizophrenic probands performed more poorly than adult-onset probands on the anticipatory saccade measure. This physiological evidence suggests that childhood-onset schizophrenia may be associated with increased genetic loading because of contributions of genetic risk from both parents.

Nonuniformity correction of infrared image sequences using the constant-statistics constraint

Using clues from neurobiological adaptation, we have developed the constant-statistics (CS) algorithm for nonuniformity correction of infrared focal point arrays (IRFPAs) and other imaging arrays. The CS model provides an efficient implementation that can also eliminate much of the ghosting artifact that plagues all scene-based nonuniformity correction (NUC) algorithms. The CS algorithm with deghosting is demonstrated on synthetic and real infrared (IR) sequences and shown to improve the overall accuracy of the correction procedure.

Anticipatory saccades during smooth pursuit eye movements and familial transmission of schizophrenia

BACKGROUND

Smooth pursuit eye movement (SPEM) abnormalities are a putative marker of genetic risk for schizophrenia. Accurate SPEM performance requires the subject to activate neural systems responsible for smooth pursuit tracking, while simultaneously suppressing activity of neurons responsible for saccadic movements that would move the eye ahead of the target. This study examined whether specific aspects of SPEM dysfunction cosegregate with genetic risk in parents of schizophrenic probands.

METHODS

Eighteen probands and their parents had SPEM recorded. Parents with an ancestral history of schizophrenia were hypothesized to be more likely than their spouses without such a history to carry a genetic risk for schizophrenia.

RESULTS

Ten families had a single parent with a positive ancestral history for schizophrenia. The frequency of anticipatory saccades, which were mostly small, and the fraction of total eye movement that they represented were the only measures that differentiated the more likely genetic carrier parents in these families from their spouses and age-matched normals.

CONCLUSIONS

Failure to suppress saccadic anticipation of target motion during smooth pursuit appears an aspect of SPEM dysfunction related to presumed genetic risk for schizophrenia.

Schizophrenia, sensory gating, and nicotinic receptors

A series of human and animal investigations has suggested that altered expression and function of the alpha7-nicotinic cholinergic receptor may be responsible for the auditory sensory gating deficit characterized in schizophrenia patients and their relatives as diminished suppression of an auditory-evoked response (P50) to repeated stimuli. This finding, in conjunction with evidence for familial transmission of this sensory gating deficit, suggests a pathogenic role of the gene for the alpha7-nicotinic receptor in schizophrenia. This article considers the possible effects of this dysfunction in a broader context. Not only is this dysfunction consistent with difficulties in sensory gating, but it might also predispose patients to problems with learning efficiency and accuracy. Such learning problems could underlie schizophrenia patients' delusional thinking, hallucinations, and social dysfunction. In addition, heavy smoking in many schizophrenia patients is consistent with the high concentration of nicotine necessary to activate the receptor and with the receptor's extremely rapid desensitization. Finally, the receptor's possible role in cell growth and differentiation should be considered in connection with developmental deficits and other cellular abnormalities in schizophrenia.

Familial transmission of two independent saccadic abnormalities in schizophrenia

Difficulties with inhibiting inappropriate responses, i.e. disinhibition, and problems with spatial memory are both presumed to be a part of the phenotypic expression of the genetic risk for schizophrenia. Schizophrenic probands are impaired on saccadic eye movement tasks which require (a) response inhibition to prepotent stimuli and (b) generation of an accurate response to a remembered or calculated spatial location, but it is unknown how these deficits are inherited. Sixteen schizophrenic probands, their 32 parents, and two normal control groups completed a delayed oculomotor response and an antisaccade task. The parents with a positive ancestral family history for chronic psychosis (n = 8) were presumed to be more likely than their family history-negative spouses to be genetic carriers for schizophrenia. Probands and their positive family history parents had more failures of response inhibition than did normal control groups. However, it was the probands and their negative family history spouses who demonstrated impaired accuracy of the remembered- or antisaccades. Disinhibition may be closely tied to a specific genetic risk for schizophrenia. However, a second familial factor related to the maintenance or manipulation of spatial information may also contribute to the genetic risk of the full clinical disorder.

Comparison of salmeterol and albuterol-induced bronchoprotection against adenosine monophosphate and histamine in mild asthma

Short-acting beta(2)-agonists provide greater protection to bronchoconstriction induced by adenosine-5'-monophosphate (AMP) than does methacholine. Because AMP produces bronchoconstriction through release of mediators from mast cells, and methacholine directly constricts airway smooth muscle, this suggests that beta(2)-agonists stabilize mast cells in vivo. This in vivo property has not been demonstrated with long-acting beta(2)-agonists. We undertook two double-blind, randomized, crossover, placebo-controlled studies to investigate the effects of salmeterol and albuterol on airway responsiveness (AR) to AMP and histamine in patients with mild asthma. In the first study, 19 patients attended on four occasions to inhale salmeterol 50 micrograms or placebo 2 h before challenge with AMP or histamine. In the second study 16 patients (13 of whom had participated in the first study) were studied in a similar fashion but inhaled albuterol 400 micrograms or placebo 30 min prior to challenge. Salmeterol reduced AR to AMP and histamine by 3.4 +/- 0.3 and 3.9 +/- 0.3 doubling doses, respectively (NS). In contrast, albuterol demonstrated a greater protective effect on AMP than on histamine, reducing AR by 5.1 +/- 0.3 and 3.8 +/- 0.2 doubling doses, respectively (p < 0.005). Thus, in contrast to albuterol, salmeterol did not demonstrate mast-cell stabilizing properties in vivo at a time corresponding to maximal bronchodilatation. These findings might be explained by the unique pharmacologic profile of salmeterol in combination with the differential beta(2)-adrenoceptor pharmacology of bronchial mast cells and bronchial smooth muscle.

Neuropsychological dysfunction in parents of schizophrenics

Neuropsychological measures designed to examine aspects of attention, learning efficiency, and memory were investigated in 14 schizophrenic probands, their 28 parents, and 18 normal individuals. Probands performed at levels significantly below normals on measures of attention and of learning efficiency and performed below their parents on a subset of the same measures. Eight families had one parent with a personal or ancestral pedigree history consistent with schizophrenia; the other parent's personal and ancestral history was negative for schizophrenia. In these families, the probands were significantly different from the negative-history parents, but not the positive-history parents on an aggregate index of attention. Schizophrenics were significantly different from both the positive- and negative-history parents on an aggregate index of learning efficiency. These results extend previous findings of specific neuropsychological dysfunction in attention and learning in schizophrenics to show that some of the deficits are present in a subgroup of their parents, those who are likely carriers of genes conveying risk for schizophrenia. The data suggest that a heritable component of the neuropsychological deficit is a primary dysfunction in attention, and that a secondary or additional deficit in learning may be evident in family members who actually express the disorder of schizophrenia.

Modulation of ICAM-1 levels on U-937 cells and mouse macrophages by interleukin-1 beta and dexamethasone

Differentiation of U-937 cells with phorbol ester (10 nM) induced a time-dependent (24 h or 48 h) increase of adhesion molecules and lipocortin 1 expression on the cell surface. Stimulation with interleukin-1 beta for a further 16 h increased the levels of intercellular adhesion molecule-1, and this effect was inhibited by co-incubation with 0.1-1 microM dexamethasone. The effect of the glucocorticoid was not modified by addition of a specific anti-lipocortin 1 monoclonal antibody (mAb 1A, 5 micrograms/ml). This opposite modulatory role of interleukin-1 and dexamethasone on intercellular adhesion molecule-1 expression was also, for the first time, observed in vivo using mouse peritoneal macrophages: a four-fold increase in intercellular adhesion molecule-1 expression was measured after local administration of the cytokine (5 micrograms/kg) and this effect was greatly inhibited (> 70%) by co-injection with 1 microgram dexamethasone. In conclusion, modulation of intercellular adhesion molecule-1 expression by glucocorticoids is an effect independent endogenous lipocortin 1, and it is an in vivo feature of these potent anti-inflammatory drugs.

Relative contribution of the selectins in the neutrophil recruitment caused by the chemokine cytokine-induced neutrophil chemoattractant (CINC)

Rat CINC induced a dose- and time-dependent accumulation of neurophils into murine air-pouches, a response which was inhibited by two selective H1-antagonists, mepyramine and triprolidine (approximately 60%). As pretreatment with fucoidin abolished CINC effect, the relative time-related contribution of selectins on this process was then investigated by using specific monoclonal antibodies (mAb). Anti-CD62L mAb gave a similar degree of inhibition of CINC-induced cell accumulation both at the 2h and 4h time-point (approximately 75%). Anti-CD62P mAb, but not the anti-CD62E mAb, inhibited PMN accumulation at 2h (65%), but only co-administration of these two mAbs inhibited the cell response to CINC at the 4h time-point (90%). Thus endogenous histamine, CD62L, CD62P, and CD62E, though to a different degree, are required for PMN extravasation observed in response to CINC administration.

Acute inflammatory response in the mouse: exacerbation by immunoneutralization of lipocortin 1

1. An immuno-neutralization strategy was employed to investigate the role of endogenous lipocortin 1 (LC1) in acute inflammation in the mouse. 2. Mice were treated subcutaneously with phosphate-buffered solution (PBS), non-immune sheep serum (NSS) or with one of two sheep antisera raised against LC1 (LCS3), or its N-terminal peptide (LCPS1), three times over a period of seven days. Twenty four hours after the last injection several parameters of acute inflammation were measured including zymosan-induced inflammation in 6-day-old air-pouches, zymosan-activated serum (ZAS)-induced oedema in the skin, platelet-activating factor (PAF)-induced neutrophilia and interleukin-1 beta (IL-1 beta)-induced corticosterone (CCS) release. 3. At the 4 h time-point of the zymosan inflamed air-pouch model, treatment with LCS3 did not modify the number of polymorphonuclear leucocytes (PMN) recruited: 7.84 +/- 1.01 and 7.00 +/- 0.77 x 10(6) PMN per mouse for NSS- and LCS3 group, n = 7. However, several other parameters of cell activation including myeloperoxidase (MPO) and elastase activities were increased (2.2 fold, P < 0.05, and 6.5 fold, P < 0.05, respectively) in the lavage fluids of these mice. Similarly, a significant increase in the amount of immunoreactive prostaglandin E2 (PGE2; 1.81 fold, P < 0.05) and IL-1 alpha (2.75 fold, P < 0.05), but not tumour necrosis factor-alpha (TNF-alpha), was also observed in LCS3-treated mice. 4. The recruitment of PMN into the zymosan inflamed air-pouches by 24 h had declined substantially (4.13 +/- 0.61 x 10(6) PMN per mouse, n = 12) in the NSS-treated mice, whereas high values were still measured in those treated with LCS3 (9.35 +/- 1.20 x 10(6) PMN per mouse, n = 12, P < 0.05). A similar effect was also found following sub-chronic treatment of mice with LCPS1: 6.48 +/- 0.10 x 10(6) PMN per mouse, vs. 2.77 +/- 1.20 and 2.64 +/- 0.49 x 10(6) PMN per mouse for PBS- and NSS-treated groups (n = 7, P < 0.05). Most markers of inflammation were also increased in the lavage fluids of LCS3-treated mice: MPO and elastase showed a 2.47 fold and 17 fold increase, respectively (P < 0.05 in both cases); TNF-alpha showed a 11.1 fold increase (P < 0.05) whereas the IL-1 alpha levels were not significantly modified. PGE2 was still detectable in most (5 out of 7) of the mice treated with LCS3 but only in 2 out of 7 of the NSS-treated mice. 5. Intradermal injection of 50% ZAS caused a significant increase in the 2 hoedema formation in the skin of LCS3-treated mice in comparison to PBS- and NSS-treated animals: 16.7 +/- 1.5 microliters vs. 10.8 +/- 1.2 microliters and 10.2 +/- 1.0 microliters, respectively (n = 14 mice per group, P < 0.05). ZAS-induced oedema had subsided by 24 h in control animals but a residual significant amount of extravasation was still detectable in LCS3-treated mice: 4.4 +/- 0.8 microliters (P < 0.05). 6. A recently described model driven by endogenous glucocorticoids is the blood neutrophilia observed following administration of PAF. In our experimental conditions, a single bolus of PAF (100 ng, i.v.) provoked a marked neutrophilia at 2 h (2.43 and 2.01 fold) in NSS- and PBS-treated mice (n = 11), respectively, which was significantly attenuated in the animals treated with LCS3: 1.26 fold increase in circulating PMN (n = 11, P < 0.01 vs. NSS- and PBS-groups). 7. Intraperitoneal injection of IL-1 beta (5 micrograms kg-1) caused a marked increase in circulating plasma CCS by 2 h, to a similar extent in all experimental groups. In contrast, measurement of CCS levels in the plasma of mice bearing air-pouches inflamed with zymosan revealed significant differences between LCS3 and NSS-treated mice at the 4 h time-point: 198 +/- 26 ng ml-1 vs. 110 +/- 31 ng ml-1 (n = 8, P < 0.05). 8. In conclusion, we found a remarkable exacerbation of the inflammatory process with respect to both humoral and cellular components in mice passively immunised agains

Endogenous corticosteroids mediate the neutrophilia caused by platelet-activating factor in the mouse

Platelet-activating factor (PAF; 100 ng i.v.) transiently modified the number of circulating neutrophils in the mouse, inducing a fast neutropenia (2 min) followed by a late onset neutrophilia (2 h). The potential involvement in PAF-induced neutrophilia of granulocytotic agents such as interleukin-1 and tumor necrosis factor-alpha could be excluded on the basis of the ineffectiveness of interleukin-1 receptor antagonist and of a specific monoclonal antibody anti-murine tumor necrosis factor-alpha. PAF granulocytosis was preceded by a significant rise in plasma corticosterone at 20 min. The involvement of endogenous corticosteroids was confirmed by the experiments with adrenalectomized mice and in animals pretreated with the steroid antagonist RU486 (11 beta-(4-dimethyl amino-phenyl) 17 beta-hydroxy, 17 alpha(prop-1-ynyl) estra 4,9-dien-3-one), where PAF-induced neutrophilia was greatly reduced (approximately 50%). Moreover, sustained increase in plasma corticosterone by administration of adrenocorticotropic hormone was paralleled by an intense neutrophilia. We show evidence that endogenous corticosterone acts through the glucocorticoid-inducible protein lipocortin 1.

Learning to ignore: psychophysics and computational modeling of fast learning of direction in noisy motion stimuli

The effects of practice on the discrimination of direction of motion in briefly presented noisy dynamic random dot patterns are investigated in several forced-choice psychophysical tasks. We found that the percentage of correct responses on any specific task increases linearly with repetition of trials within roughly 200 trials from about chance to a performance of 90% or better. The level of performance remained constant or improved over several days, and in most instances it did not transfer when stimulus parameters changed. We used a modified Radial Basis Function (RBF) representation to model the psychophysical tasks. The performance of the model is functionally similar to the psychophysical results. We propose a Hebbian learning algorithm which deactivates the inputs from neurons responding to motion noise in the stimulus. Our computational model suggests that to solve this task in biological systems, neurons (perhaps in MT) improve their performance by 'learning to ignore' noise in the image.

Alteration of neutrophil trafficking by a lipocortin 1 N-terminus peptide

Sialidase, fucoidin and a peptide corresponding to most of lipocortin 1 N-terminus, termed LC1-(Ac2-26)-peptide, induced an intense 2 h neutrophilia whereas a monoclonal antibody to murine CD11b induced an effect by 1 h. The neutropenic response stimulated by platelet-activating factor (PAF) was significantly reduced in the presence of sialidase, fucoidin, LC1-(Ac2-26)-peptide and monoclonal antibody anti-CD11b. Neutrophil migration into a 6-day-old mouse air-pouch induced by interleukin-1 was inhibited by all the pharmacological agents. In vitro, PAF up-regulated CD11b expression on the neutrophil surface but neither human or mouse LC1-(Ac2-26)-peptide inhibited this response. CD11b up-regulation on neutrophils occurred after PAF administration in vivo and was maximal at 2 min. LC1-(Ac2-26)-peptide mimics the action of agents interfering with leucocyte rolling and adhesion in vivo, however, does not inhibit CD11b up-regulation in vitro suggesting other phenomena are important in the activity of this peptide.

Effects of bilingualism on verbal learning and memory in Hispanic adults

The effect of bilingualism on qualitative aspects of verbal learning and memory was investigated. Equivalent list learning tests in English and Spanish were carefully constructed, and compared across two bilingual Hispanic groups of Mexican origin that differed in their level of English proficiency ("balanced" and "nonbalanced" bilinguals) and a group of monolingual English-speaking non-Hispanic subjects. Groups were matched for age, education, and gender composition. Nonbalanced bilinguals assessed in English utilized semantic clustering to the same extent as monolinguals, but learned fewer words overall, and demonstrated lower retention scores compared to monolinguals. Comparisons of groups assessed in their dominant languages, however, revealed no significant differences on any of the learning and memory indices examined. In addition to comparisons with standard clinical memory indices, assessment issues concerning bilingual individuals are addressed.

Schizophrenia and nicotinic receptors

Patients with schizophrenia often cannot respond to important features of their environment and filter out irrelevant stimuli. This dysfunction could be related to an underlying defect in inhibition--i.e., the brain's ability to alter its sensitivity to repeated stimuli. One of the neuronal mechanisms responsible for such inhibitory gating involves the activation of cholinergic nicotinic receptors in the hippocampus. These receptors are diminished in many specimens of hippocampal brain tissue obtained postmortem from schizophrenic patients. In living schizophrenic patients, stimulation of cholinergic receptors by nicotine transiently restores inhibitory gating of evoked responses to sensory stimuli. Many people with schizophrenia are heavy smokers, but the properties of the nicotinic receptor favor only short-term activation, which may explain why cigarette smoking is only a transient symptomatic remedy. This paper reviews the clinical phenomenology of inhibitory gating deficits in people with schizophrenia, the neurobiology of such gating mechanisms, and the evidence that some individuals with the disorder may have a heritable deficit in the nicotinic cholinergic receptors involved in this neurobiological function. Inhibitory gating deficits are only partly normalized by neuroleptic drugs and are thus a target for new therapeutic strategies for schizophrenia.

A role for endogenous histamine in interleukin-8-induced neutrophil infiltration into mouse air-pouch: investigation of the modulatory action of systemic and local dexamethasone

1. When injected into a 6-day-old mouse air-pouch, human recombinant interleukin-8 (IL-8; 0.03-3 micrograms) induced, in a dose-dependent fashion, an accumulation of neutrophils which could be reliably assessed 4 h after the injection. No protein extravasation was measured above the values obtained with the vehicle alone (carboxymethylcellulose, CMC, 0.5% w/v in phosphate-buffered solution, PBS). 2. The IL-8 effect (routinely evaluated at 1 microgram dose) was inhibited neither by local administration of actinomycin D (1 microgram) nor by systemic treatment with indomethacin (1 mg kg-1, i.v.), BWA4C (5 mg kg-1, p.o.), methysergide (6 mg kg-1, i.p.) and RP67580 (2 mg kg-1, i.p.). 3. Treatment of mice with the H1 antagonist, mepyramine (1-10 mg kg-1, i.p.) resulted in a dose-dependent inhibition of the cell accumulation elicited by the chemokine, with a maximal reduction of approximately 50-60%. The mepyramine effect was not due to a non specific reduction of neutrophil function, since treatment with this drug (6 mg kg-1, i.p.) did not modify the cell infiltration measured in response to a challenge with interleukin-1 beta (20 ng) or with the vehicle CMC to any extent. Moreover, treatment of mice with mepyramine did not modify cell counts in a peripheral blood film with respect to controls. Two other H1 antagonists, chemically unrelated to mepyramine, diphenhydramine (9 mg kg-1, i.p.) and triprolidine (0.5 mg kg-1, i.p.), inhibited IL-8-induced migration to a similar extent (approximately 50-60%), whereas the H2 antagonist, ranitidine (5 mg kg-1, i.p.) was without effect. 4. The concept that endogenous histamine could be involved in the IL-8 effect was strengthened in two ways: (i) addition of histamine (0.2-2 microg) to a small dose of IL-8 (0.3 microg) potentiated the cell elicitation induced by the chemokine without having any effect on its own; (ii) IL-8-induced neutrophil accumulation was greatly impaired in animals depleted of mast cell amines by sub-chronic (5 day) treatment with compound 48/80 according to an established protocol.5. The glucocorticoid dexamethasone (Dex; 1-50 microg per mouse, i.v., corresponding approximately to 0.03-1.5 mg kg-1, given i.v. 2 h prior to challenge with IL-8) potently inhibited neutrophil infiltration with an approximate ED50 of 5 microg per mouse (~ 0.3 mg kg-1 , i.v.). Passive immunisation of mice with a polyclonal sheep serum raised against the steroid-inducible anti-inflammatory protein lipocortin 1 (LCl)abolished the inhibitory action of Dex whereas a control serum was without effect.6. Local administration of Dex at a dose which was ineffective when given systemically (1 microg) also reduced neutrophil migration induced by IL-8, either alone or in combination with histamine. This local inhibition (~50%), also seen with hydrocortisone (30 microg), was prevented by the concomitant administration of the steroid antagonist RU38486 (10 microg) indicating the involvement of glucocorticoid receptor in the response.7. These findings characterize further the mechanisms underlying PMN recruitment induced by IL-8 in vivo, and point to a role for histamine. The anti-inflammatory action of the glucocorticoids, as in some other models, appears to be LCl-dependent when these drugs are given systemically and LCl independent when the steroids are given locally.

Lipocortin-1 fragments inhibit neutrophil accumulation and neutrophil-dependent edema in the mouse. A qualitative comparison with an anti-CD11b monoclonal antibody

The activity of the steroid-inducible protein lipocortin-1 (LC1; with a primary sequence of 346 amino acids; also called annexin 1), a fragment corresponding to amino acids 1-188 and a short peptide from the N-terminus (amino acid 2-26) were tested for anti-inflammatory actions in three models of acute inflammation in the mouse in comparison with a mAb anti-CD11b (alpha CD11b). In the mouse air-pouch model LC1, fragment 1-188 and peptide Ac2-26 exhibited powerful inhibitory effects (ED50 approximately 5.2, 38 and 88 micrograms/mouse, respectively) on leukocyte migration elicited by IL-1. LC1 was approximately 200 times more potent than Ac2-26 on a molar basis although both gave maximal inhibitions, in contrast fragment 1-188 only produced a partial dose-response curve. LC1 was approximately 20 times more potent on a molar basis in this assay than the alpha CD11b mAb. Peptide Ac2-26 and the mAb alpha CD11b also blocked cell migration into the air-pouch induced by IL-8 with approximately the same potency. In the mouse skin edema and zymosan peritonitis assays Ac2-26 was inhibitory (ED50 of 200 micrograms/mouse) but less so than the alpha CD11b antibody (ED50 approximately 0.5 mg/mouse). Both LC1 (10 micrograms) and Ac2-26 (200 micrograms) completely blocked FMLP-induced neutropenia in the mouse. Studies using an inactivated LC1 preparation, which binds to the same high affinity binding sites as the biologically active material, indicated that the short peptide acts on the same sites as the native LC1. This study confirms the activity of LC1 in another model of experimental inflammation and suggests that it acts partly through inhibition of leukocyte activation with an overall effect qualitatively comparable to the blocking of CD11b portion of a beta 2-integrin complex. It also shows that peptides derived from the N-terminal domain of LC1 may mimic the activity of the full length molecule and points the way for a new family of anti-inflammatory substances that inhibit leukocyte trafficking.

Lipocortin-1 fragments inhibit neutrophil accumulation and neutrophil-dependent edema in the mouse. A qualitative comparison with an anti-CD11b monoclonal antibody

The activity of the steroid-inducible protein lipocortin-1 (LC1; with a primary sequence of 346 amino acids; also called annexin 1), a fragment corresponding to amino acids 1-188 and a short peptide from the N-terminus (amino acid 2-26) were tested for anti-inflammatory actions in three models of acute inflammation in the mouse in comparison with a mAb anti-CD11b (alpha CD11b). In the mouse air-pouch model LC1, fragment 1-188 and peptide Ac2-26 exhibited powerful inhibitory effects (ED50 approximately 5.2, 38 and 88 micrograms/mouse, respectively) on leukocyte migration elicited by IL-1. LC1 was approximately 200 times more potent than Ac2-26 on a molar basis although both gave maximal inhibitions, in contrast fragment 1-188 only produced a partial dose-response curve. LC1 was approximately 20 times more potent on a molar basis in this assay than the alpha CD11b mAb. Peptide Ac2-26 and the mAb alpha CD11b also blocked cell migration into the air-pouch induced by IL-8 with approximately the same potency. In the mouse skin edema and zymosan peritonitis assays Ac2-26 was inhibitory (ED50 of 200 micrograms/mouse) but less so than the alpha CD11b antibody (ED50 approximately 0.5 mg/mouse). Both LC1 (10 micrograms) and Ac2-26 (200 micrograms) completely blocked FMLP-induced neutropenia in the mouse. Studies using an inactivated LC1 preparation, which binds to the same high affinity binding sites as the biologically active material, indicated that the short peptide acts on the same sites as the native LC1. This study confirms the activity of LC1 in another model of experimental inflammation and suggests that it acts partly through inhibition of leukocyte activation with an overall effect qualitatively comparable to the blocking of CD11b portion of a beta 2-integrin complex. It also shows that peptides derived from the N-terminal domain of LC1 may mimic the activity of the full length molecule and points the way for a new family of anti-inflammatory substances that inhibit leukocyte trafficking.

Neurophysiological and neuropsychological evidence for attentional dysfunction in schizophrenia

The behavior of the P50 wave of the auditory evoked potential in a paired stimulus or conditioning-testing paradigm has been used as a measure of sensory gating disturbance in schizophrenia. Schizophrenics fail to decrement the P50 response to the second stimulus of the pair, so that the ratio of the test to the conditioning amplitude is elevated over normal values. The aim of this study was to compare this neurophysiological measure to neuropsychological measures of attention and memory. As expected, schizophrenics performed worse than controls on most measures. The time to complete a digit cancellation test, a measure of sustained attention, was found to be particularly longer in schizophrenics than in control subjects. Furthermore, the increased time to complete this task correlated with the increased ratio of the amplitude of the test P50 response to the conditioning response in the schizophrenics. Thus, a neurophysiological defect in sensory gating may relate to a disorder in sustained attention in schizophrenia. Although the P50 wave may come from the hippocampus, neuropsychological measures of verbal learning and memory were not correlated with alterations in the P50 ratio.

Numerical analysis of the acoustic signature of a surface-breaking crack

The boundary element method is used to calculate the acoustic signature, produced by a line focus scanning acoustic microscope, of an elastic object containing a surface-breaking crack. The acoustic signature has a vertical (z) and horizontal (x) dependence. A model of the microscope developed earlier is used and extended to take account of the crack. The mathematical formulation of the scattering problem for the cracked object leads to hypersingular integral equations. A suitable technique is employed to solve such equations by the boundary element method. An electromechanical reciprocity identity is used to relate the received voltage to the acoustic wavefields collected by the lens. The acoustic wavefield scattered from the cracked object is investigated, and curves are presented that display the acoustic signature, as functions of (x ,z), for cracks of various depths and orientations. A method to measure the depth of a surface-breaking crack using the acoustic signature is suggested.

Wave analysis of the acoustic material signature for the line focus microscope

A model is presented for the computation of the acoustic material signature for a line focus scanning acoustic microscope, based on a boundary element calculation and an electromechanical reciprocity identity. This identity is used to relate the voltage at the terminals of the microscope's transducer to the acoustic wavefields at the interface between the specimen and the coupling fluid. A Gaussian beam, launched in the buffer rod, is tracked through the lens and its matching layer. A model for the matching layer that is convenient for use with the boundary element technique is presented. The wavefields scattered from the surface of the specimen, including the leaky Rayleigh wave, are then calculated. Knowing the wavefields incident on and scattered from the specimen, the acoustic signature is calculated using the reciprocity relation. Results are presented for a defect free halfspace, and are compared with those of an analytical model and an experimental measurement.

A two-dimensional analog VLSI circuit for detecting discontinuities in early vision

A large number of computer vision algorithms for finding intensity edges, computing motion, depth, and color, and recovering the three-dimensional shape of objects have been developed within the framework of minimizing an associated "energy" or "cost" functional. Particularly successful has been the introduction of binary variables coding for discontinuities in intensity, optical flow field, depth, and other variables, allowing image segmentation to occur in these modalities. The associated nonconvex variational functionals can be mapped onto analog, resistive networks, such that the stationary voltage distribution in the network corresponds to a minimum of the functional. The performance of an experimental analog very-large-scale integration (VLSI) circuit implementing the nonlinear resistive network for the problem of two-dimensional surface interpolation in the presence of discontinuities is demonstrated; this circuit is implemented in complementary metal oxide semiconductor technology.

DataVoice: a microcomputer-based general purpose voice-controlled data-collection system

An integrated system of hardware and software has been developed to combine the input of coordinate data from a digitizing pad with voice input for object identification or classification. The menu and voice-controlled software generates a sequential ASCII file which contains an object identification section and a data section. Rules for data entry and analysis programs have been developed for several applications. These are being tested and include general stereological analyses, bone, kidney and skin histomorphometry, boundary analyses, neuron classification and malignancy grading.