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1.
Chemosphere ; 296: 133934, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35176295

ABSTRACT

Synthetic rubber emissions from automobile tires are common in aquatic ecosystems. To assess potential impacts on exposed organisms, early life stages of the estuarine indicator species Inland Silverside (Menidia beryllina) and mysid shrimp (Americamysis bahia) were exposed to three tire particle (TP) concentrations at micro and nano size fractions (0.0038, 0.0378 and 3.778 mg/L in mass concentrations for micro size particles), and separately to leachate, across a 5-25 PSU salinity gradient. Following exposure, M. beryllina and A. bahia had significantly altered swimming behaviors, such as increased freezing, changes in positioning, and total distance moved, which could lead to an increased risk of predation and foraging challenges in the wild. Growth for both A. bahia and M. beryllina was reduced in a concentration-dependent manner when exposed to micro-TP, whereas M. beryllina also demonstrated reduced growth when exposed to nano-TP (except lowest concentration). TP internalization was dependent on the exposure salinity in both taxa. The presence of adverse effects in M. beryllina and A. bahia indicate that even at current environmental levels of tire-related pollution, which are expected to continue to increase, aquatic ecosystems may be experiencing negative impacts.


Subject(s)
Ecosystem , Water Pollutants, Chemical , Animals , Crustacea , Fishes , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicity
2.
J Autism Dev Disord ; 51(11): 3959-3969, 2021 Nov.
Article in English | MEDLINE | ID: mdl-33420938

ABSTRACT

Mindfulness-based approaches have been shown to be effective in improving the mental health of parents of youth and adults with autism and other developmental disabilities, but prior work suggests that geography and caregiving demands can make in-person attendance challenging. The purpose of this study was to evaluate the feasibility, acceptability and preliminary outcomes of a mindfulness-based group intervention delivered to parents virtually. It was feasible to deliver this manualized intervention. Twenty-one of 39 parents completed the intervention and completers reported high satisfaction ratings. Parents reported reduced levels of distress, maintained at 3-month follow-up, and increased mindfulness. Changes reported following intervention were similar to changes reported in a prior study of parents competing an in person mindfulness group.


Subject(s)
Autism Spectrum Disorder , Autistic Disorder , Mindfulness , Adolescent , Adult , Autistic Disorder/therapy , Humans , Parents
3.
Parasitology ; 145(8): 1095-1104, 2018 07.
Article in English | MEDLINE | ID: mdl-29262879

ABSTRACT

The Pacific oyster Crassostrea gigas contributes significantly to global aquaculture; however, C. gigas culture has been affected by ostreid herpesvirus-1 (OsHV-1) and variants. The dynamics of how the virus maintains itself at culture sites is unclear and the role of carriers, reservoirs or hosts is unknown. Both wild and cultured mussels Mytilus spp. (Mytilus edulis, Mytilus galloprovincialis and hybrids) are commonly found at C. gigas culture sites. The objective of this study was to investigate if Mytilus spp. can harbour the virus and if viral transmission can occur between mussels and oysters. Mytilus spp. living at oyster trestles, 400-500 m higher up the shore from the trestles and up to 26 km at non-culture sites were screened for OsHV-1 and variants by all the World Organization for Animal Health (OIE) recommended diagnostic methods including polymerase chain reaction (PCR), quantitative PCR (qPCR), histology, in situ hybridization and confirmation using direct sequencing. The particular primers that target OsHV-1 and variants, including OsHV-1 microVar (µVar), were used in the PCR and qPCR. OsHV-1 µVar was detected in wild Mytilus spp. at C. gigas culture sites and more significantly the virus was detected in mussels at non-culture sites. Cohabitation of exposed wild mussels and naïve C. gigas resulted in viral transmission after 14 days, under an elevated temperature regime. These results indicate that mussels can harbour OsHV-1 µVar; however, the impact of OsHV-1 µVar on Mytilus spp. requires further investigation.


Subject(s)
Crassostrea/virology , DNA Viruses/isolation & purification , Herpesviridae Infections/veterinary , Mytilus/virology , Animals , Aquaculture , DNA Primers , DNA Viruses/genetics , DNA, Viral , Disease Reservoirs/virology , Herpesviridae Infections/transmission , Real-Time Polymerase Chain Reaction
4.
Trop Anim Health Prod ; 49(2): 317-322, 2017 Feb.
Article in English | MEDLINE | ID: mdl-27924415

ABSTRACT

A survey was conducted into respiratory infectious diseases of poultry on a chicken breeder farm run by the Ethiopian Institute of Agricultural Research (EIAR), located in Debre Zeit, Ethiopia. Oropharyngeal swabs were collected from 117 randomly selected birds, and blood was taken from a subset of 73 of these birds. A combination of serological and molecular methods was used for detection of pathogens. For the first time in Ethiopia, we report the detection of variant infectious bronchitis virus (793B genotype), avian metapneumovirus subtype B and Mycoplasma synoviae in poultry. Mycoplasma gallisepticum was also found to be present; however, infectious laryngotracheitis virus was not detected by PCR. Newcastle disease virus (NDV) was not detected by PCR, but variable levels of anti-NDV HI antibody titres shows possible exposure to virulent strains or poor vaccine take, or both. For the burgeoning-intensive industry in Ethiopia, this study highlights several circulating infectious respiratory pathogens that can impact on poultry welfare and productivity.


Subject(s)
Coronavirus Infections/veterinary , Mycoplasma Infections/veterinary , Paramyxoviridae Infections/veterinary , Poultry Diseases/epidemiology , Animals , Antibodies, Viral/blood , Chickens , Coronavirus Infections/epidemiology , Enzyme-Linked Immunosorbent Assay/veterinary , Ethiopia/epidemiology , Infectious bronchitis virus/immunology , Infectious bronchitis virus/isolation & purification , Metapneumovirus/immunology , Metapneumovirus/isolation & purification , Mycoplasma Infections/epidemiology , Mycoplasma gallisepticum/genetics , Mycoplasma gallisepticum/isolation & purification , Mycoplasma synoviae/genetics , Mycoplasma synoviae/isolation & purification , Oropharynx/microbiology , Oropharynx/virology , Paramyxoviridae Infections/epidemiology , Polymerase Chain Reaction/veterinary , Poultry Diseases/blood , Poultry Diseases/microbiology , Poultry Diseases/virology
5.
Pathology ; 44(7): 611-6, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23149378

ABSTRACT

AIMS: To assess oestrogen receptor (ER)α, ERß, and progesterone receptor (PR) expression in stage I ovarian adult-type granulosa cell tumours (AGCTs) and correlate the findings with clinical outcome. METHODS: ERα, ERß and PR immunohistochemistry was performed on 56 primary, stage I AGCTs. Twelve cases (21%) recurred and hormone receptor staining was compared in the corresponding primary and metastatic tumours. RESULTS: All primary AGCTs expressed ERß and PR, usually with strong and diffuse staining, whereas only 20% of tumours were focally ERα positive. There was no correlation between ERα or PR expression and outcome. However, primary AGCTs with low ERß expression had a significantly higher risk of recurrence. In contrast, all metastatic tumours exhibited strong ERß staining. No relationship between ER staining and tumour morphology was identified but there was more consistent PR expression in cells at the tumour-stromal interface. CONCLUSIONS: Primary AGCTs typically show an ERα negative and ERß/PR positive immunophenotype. Low ERß expression is an adverse prognostic factor in primary AGCT but metastatic tumours often show up-regulation of ERß. Local microenvironmental factors may influence PR expression. Hormone receptor expression in AGCT may become increasingly relevant due to developments in selective therapy.


Subject(s)
Estrogen Receptor alpha/metabolism , Estrogen Receptor beta/metabolism , Granulosa Cell Tumor/pathology , Neoplasm Recurrence, Local/pathology , Ovarian Neoplasms/pathology , Receptors, Progesterone/metabolism , Adult , Aged , Aged, 80 and over , Female , Granulosa Cell Tumor/metabolism , Humans , Immunohistochemistry , Middle Aged , Neoplasm Recurrence, Local/metabolism , Ovarian Neoplasms/metabolism , Ovary/metabolism , Ovary/pathology , Prognosis , Tumor Microenvironment , Up-Regulation
6.
Exp Brain Res ; 213(1): 27-34, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21735247

ABSTRACT

In the antisaccade task, healthy participants often make errors by saccading towards the sudden onset target, despite instructions to saccade to the mirror image location. One interesting and relatively unexplored feature of antisaccade performance is that participants are typically unaware of a large proportion of the errors they make. Across two experiments, we explored the extent to which error awareness is altered by manipulations known to affect antisaccade error rate. In experiment 1, participants performed the antisaccade task under standard instructions, instructions to respond as quickly as possible or instructions to delay responding. Delay instructions significantly reduced antisaccade error rate compared to the other instructions, but this reduction was driven by a decrease only in the number of errors that participants were aware of-the number of errors of which participants were unaware remained constant across instruction condition. In experiment 2, participants performed antisaccades alone, or concurrently with two different distractor tasks-spatial tapping and random number generation task. Both the dual task conditions increased the number of errors of which participants were aware, but again, unaware error rates remained unchanged. These results are discussed in the light of recent models of antisaccade performance and the role of conscious awareness in error correction.


Subject(s)
Awareness/physiology , Psychomotor Performance/physiology , Saccades/physiology , Adult , Analysis of Variance , Female , Humans , Male , Memory, Short-Term/physiology , Neuropsychological Tests , Photic Stimulation/methods , Reaction Time/physiology , Time Factors , Young Adult
7.
Genes Brain Behav ; 9(6): 621-7, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20497232

ABSTRACT

Neuregulin 1 (NRG1) has been identified as one of the leading candidate genes for schizophrenia. However, its functional mechanisms and its effects on neurocognition remain unclear. In this study, we used two well-established oculomotor endophenotypes, the antisaccade (AS) and smooth pursuit eye movement (SPEM) tasks, to investigate the functional mechanisms of a single nucleotide polymorphism (SNP) in NRG1 (rs3924999) at the neurocognitive level in a healthy volunteer sample. A total of 114 healthy Caucasian volunteers completed genotyping for NRG1 rs3924999 and infrared oculographic assessment of AS and SPEM (at target velocities of 12 degrees , 24 degrees and 36 degrees per second). Additionally, self-report questionnaires of schizotypy, neuroticism, attention deficit hyperactivity and obsessive-compulsive traits were included. A significant effect of rs3924999 genotype, with gender as a covariate, was found for AS amplitude gain (P < 0.01), with an increasing number of A alleles being associated with increasingly hypermetric performance. No statistically significant associations were found for other AS and SPEM variables or questionnaire scores. These findings indicate that NRG1 rs3924999 affects spatial accuracy on the AS task, suggesting an influence of the gene on the neural mechanisms underlying visuospatial sensorimotor transformations, a mechanism that has been previously found to be impaired in patients with schizophrenia and their relatives.


Subject(s)
Neuregulin-1/genetics , Polymorphism, Single Nucleotide , Pursuit, Smooth/genetics , Saccades/genetics , Adolescent , Adult , Alleles , Female , Genotype , Humans , Male , Psychomotor Performance/physiology
8.
Vaccine ; 28(2): 548-60, 2009 Dec 11.
Article in English | MEDLINE | ID: mdl-19835825

ABSTRACT

Herpes simplex virus type 2 (HSV2) is the most common causative agent of genital herpes, with infection rates as high as 1 in 6 adults. The present studies were done to evaluate the efficacy of a liposomal HSV2 gD(1-306) vaccine (L-gD(1-306)-HD) in an acute murine HSV2 infection model of intravaginal (female) or intrarectal (male or female) challenge. Two doses of L-gD(1-306)-HD containing 60 microg gD(1-306)-HD and 15 microg monophosphoryl lipid A (MPL) per dose provided protection against HSV2 intravaginal challenge (86-100% survival, P< or =0.0003 vs. control liposomes; P=0.06 vs. L-gD(1-306)-HD without MPL). Both male and female mice (BALB/c and C57BL/6) immunized with L-gD(1-306)-HD/MPL were significantly protected against HSV2 intrarectal challenge, with higher survival rates compared to controls (71-100%, P< or =0.007). L-gD(1-306)-HD/MPL also provided increased survival when compared to a liposomal peptide vaccine, L-gD(264-285)-HD/MPL (male BALB/c, P

Subject(s)
Genitalia/virology , Herpes Genitalis/immunology , Herpes Genitalis/prevention & control , Herpes Simplex Virus Vaccines/immunology , Herpesvirus 2, Human/immunology , Rectum/virology , Animals , Female , Herpes Simplex Virus Vaccines/administration & dosage , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL
9.
Brain Cogn ; 68(3): 327-40, 2008 Dec.
Article in English | MEDLINE | ID: mdl-19028265

ABSTRACT

The saccadic eye movement system provides researchers with a powerful tool with which to explore the cognitive control of behaviour. It is a behavioural system whose limited output can be measured with exceptional precision, and whose input can be controlled and manipulated in subtle ways. A range of cognitive processes (notably those involved in working memory and attention) have been shown to influence saccade parameters. Researchers interested in the relationship between cognitive function and psychiatric disorders have made extensive use of saccadic eye movement tasks to draw inferences as to the cognitive deficits associated with particular psychopathologies. The purpose of this review is to provide researchers with an overview of the research literature documenting cognitive involvement in saccadic tasks in healthy controls. An appreciation of this literature provides a solid background against which to interpret the deficits on saccadic tasks demonstrated in patient populations.


Subject(s)
Cognition/physiology , Eye Movements/physiology , Psychomotor Performance/physiology , Saccades/physiology , Visual Perception/physiology , Attention/physiology , Humans , Memory/physiology , Motion Perception/physiology , Reaction Time/physiology
10.
Psychol Med ; 38(1): 79-88, 2008 Jan.
Article in English | MEDLINE | ID: mdl-17532864

ABSTRACT

BACKGROUND: The impact of co-morbid substance use in first-episode schizophrenia has not been fully explored. METHOD: This naturalistic follow-up of a cohort of 152 people with first-episode schizophrenia examined substance use and clinical outcome in terms of symptoms and social and neuropsychological function. RESULTS: Data were collected on 85 (56%) of the patient cohort after a median period of 14 months. Over the follow-up period, the proportion of smokers rose from 60% at baseline to 64%. While 30% reported lifetime problem drinking of alcohol at baseline, only 15% had problem drinking at follow-up. Furthermore, while at baseline 63% reported lifetime cannabis use and 32% were currently using the drug, by the follow-up assessment the latter figure had fallen to 18.5%. At follow-up, persistent substance users had significantly more severe positive and depressive symptoms and greater overall severity of illness. A report of no lifetime substance use at baseline was associated with greater improvement in spatial working memory (SWM) at follow-up. CONCLUSIONS: Past substance use may impede recovery of SWM performance in people with schizophrenia in the year or so following first presentation to psychiatric services. The prevalence of substance use other than tobacco tends to diminish over this period, in the absence of specific interventions. Persistent substance use in first-episode schizophrenia is associated with more severe positive and depressive symptoms but not negative symptoms, and should be a target for specific treatment intervention.


Subject(s)
Schizophrenia/epidemiology , Substance-Related Disorders/epidemiology , Adult , Alcohol-Related Disorders/diagnosis , Alcohol-Related Disorders/epidemiology , Cohort Studies , Comorbidity , Depressive Disorder/diagnosis , Depressive Disorder/epidemiology , Diagnosis, Dual (Psychiatry) , Female , Follow-Up Studies , Humans , London/epidemiology , Male , Marijuana Abuse/diagnosis , Marijuana Abuse/epidemiology , Neuropsychological Tests/statistics & numerical data , Prevalence , Psychiatric Status Rating Scales/statistics & numerical data , Schizophrenia/diagnosis , Severity of Illness Index , Social Adjustment , Substance-Related Disorders/diagnosis , Tobacco Use Disorder/diagnosis , Tobacco Use Disorder/epidemiology
11.
Psychopharmacology (Berl) ; 195(2): 245-53, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17676402

ABSTRACT

INTRODUCTION: The antisaccade task provides a powerful tool with which to investigate the cognitive and neural systems underlying goal-directed behaviour, particularly in situations when the correct behavioural response requires the suppression of a prepotent response. Antisaccade errors (failures to suppress reflexive prosaccades towards sudden-onset targets) are increased in patients with damage to the dorsolateral prefrontal cortex, and in patients with schizophrenia. Nicotine has been found to improve antisaccade performance in patients with schizophrenia and healthy controls. This performance enhancing effect may be due to direct effects on the cholinergic system, but there has been no test of this hypothesis. MATERIALS AND METHODS: In a double blind, double dummy, placebo-controlled design, we compared the effect of nicotine and modafinil, a putative indirect noradrenergic agonist, on antisaccade performance in healthy non-smokers. RESULTS AND DISCUSSION: Both compounds reduced latency for correct antisaccades, although neither reduced antisaccade errors. These findings are discussed with reference to the pharmacological route of performance enhancement on the antisaccade task and current models of antisaccade performance.


Subject(s)
Benzhydryl Compounds/pharmacology , Central Nervous System Stimulants/pharmacology , Nicotine/pharmacology , Nicotinic Agonists/pharmacology , Saccades/drug effects , Adult , Analysis of Variance , Attention/drug effects , Double-Blind Method , Humans , Male , Memory/drug effects , Modafinil , Reaction Time/drug effects , Task Performance and Analysis
12.
Exp Brain Res ; 163(3): 306-13, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15654587

ABSTRACT

Attentional processes have traditionally been closely linked to the production of saccadic eye movements, but their role in the control of smooth pursuit eye movements remains unclear. In two experiments we used dual task paradigms to vary the attentional resources available for pursuit eye tracking. In both experiments we found that attentionally demanding secondary tasks impaired smooth pursuit performance, resulting in decreased velocity and increased position error. These findings suggest that attention is important for the maintenance of accurate smooth pursuit, and do not support the hypothesis that pursuit is a relatively automatic function that proceeds optimally in the absence of attentional control. These results add weight to the suggestion that a similar functional architecture underlies both pursuit and saccadic eye movements.


Subject(s)
Attention/physiology , Psychomotor Performance/physiology , Pursuit, Smooth/physiology , Adult , Female , Humans , Male , Space Perception/physiology , Volition/physiology
13.
Phys Rev E Stat Nonlin Soft Matter Phys ; 70(3 Pt 1): 031301, 2004 Sep.
Article in English | MEDLINE | ID: mdl-15524515

ABSTRACT

In this paper, the effects of interparticle force on mixing, segregation, and stratification in dry granular materials are investigated. Avalanche segregation, stratification and also segregation in rotating drums are examined. A series of binary mixtures of granular materials is prepared which consists of spherical iron particles and a nonmagnetic material. By placing each mixture in a magnetic field, the induced magnetic interparticle force could be altered and the effects on particle segregation observed. Using this technique, the effects of altering interparticle force on both avalanche and radial segregation are examined. It is found that altering interparticle force could induce mixed materials to segregate and also induce segregating granular materials to mix. We also report a complete reversal of segregation and stratification as interparticle force was increased. These results have important implications for the mixing of cohesive powders.

14.
Acta Psychiatr Scand ; 108(6): 439-46, 2003 Dec.
Article in English | MEDLINE | ID: mdl-14616225

ABSTRACT

OBJECTIVE: Little is known about factors that mediate adherence with medication during the early stages of antipsychotic treatment in schizophrenia. This study sought to identify factors that may be associated with medication adherence in first-episode schizophrenia. METHOD: In 101 patients, adherence was assessed along with potentially relevant variables, including attitudes toward medication, insight, substance misuse, side effects and psychopathology. RESULTS: In a linear regression analysis, negative attitudes toward medication and a relative lack of insight contributed significantly towards poor adherence. Although poorly adherent patients had significantly higher scores on negative and disorganization syndromes, these did not contribute significantly towards adherence. Adverse medication side effects, subjective well-being and substance misuse showed no significant association with adherence. CONCLUSION: At the initiation of drug treatment, attitudes toward medication and insight appear more relevant to medication adherence than side effects. Adherence appears to reflect a complex interaction of influences, which may change over time.


Subject(s)
Antipsychotic Agents/therapeutic use , Patient Compliance , Schizophrenia/drug therapy , Adolescent , Adult , Catchment Area, Health , Female , Forecasting , Humans , London/epidemiology , Male , Middle Aged , Schizophrenia/epidemiology , Schizophrenic Psychology , Severity of Illness Index
15.
Neuropsychologia ; 40(12): 1891-901, 2002.
Article in English | MEDLINE | ID: mdl-12207988

ABSTRACT

Recent accounts have proposed that orbitofrontal cerebral cortex mediates the control of behavior based on emotional feedback and its somatic correlates. Here, we describe the performance of a patient with circumscribed damage to orbitofrontal cortex during a task that requires switching between sensory-motor mappings, contingent on the occurrence of positive and negative reward feedbacks. In this test, normal subjects and other patients with prefrontal damage show an increase in latencies for eye movements towards locations at which a negative feedback was presented on the preceding trial. In contrast, our patient does not show this reward-dependent inhibition of return effect on saccades. She was also found to make an increased rate of ocular refixations during visual search and used a disorganized search strategy in a token foraging task. These findings suggest that orbital regions of the prefrontal cortex mediate an inhibitory effect on actions directed towards locations that have been subject to negative reinforcement. Further, this mechanism seems to play a role in controlling natural search and foraging behavior.


Subject(s)
Orbit/physiology , Prefrontal Cortex/physiology , Saccades/physiology , Adult , Aged , Craniotomy , Discrimination, Psychological/physiology , Eye Movements/physiology , Female , Gambling/psychology , Humans , Magnetic Resonance Imaging , Male , Memory, Short-Term/physiology , Meningioma/pathology , Meningioma/surgery , Middle Aged , Neuropsychological Tests , Orbit/pathology , Prefrontal Cortex/pathology , Psychomotor Performance/physiology , Reading , Reinforcement, Psychology , Reward , Tomography, X-Ray Computed , Visual Perception/physiology
16.
Schizophr Res ; 55(3): 249-57, 2002 Jun 01.
Article in English | MEDLINE | ID: mdl-12048148

ABSTRACT

A considerable body of evidence suggests that the dorsolateral prefrontal cortex is dysfunctional in schizophrenia. However, relatively few studies have explored the involvement of other areas of the frontal cortex. Research suggests that the orbitofrontal cortex (OFC) plays an important role in decision making processes. We assessed the decision making cognition of first-episode and chronic schizophrenic patients with a novel task sensitive to orbitofrontal dysfunction. Both first-episode and chronic patients with schizophrenia took longer than matched controls to make decisions, and both groups were also impaired on a measure of risk adjustment. The impairment in these measures was more severe in the chronic patients than in the first-episode patients, and only the chronic patients made significantly fewer optimal decisions than controls. These results contribute to increasing evidence of orbitofrontal dysfunction in schizophrenia, and suggest that disease progression or the effects of long term antipsychotic medication may influence performance on this task.


Subject(s)
Cognition Disorders/etiology , Decision Making , Schizophrenia/complications , Analysis of Variance , Case-Control Studies , Chronic Disease , Humans , London , Prospective Studies , Reaction Time , Risk Adjustment , Schizophrenic Psychology
17.
Neuropsychologia ; 40(10): 1729-36, 2002.
Article in English | MEDLINE | ID: mdl-11992660

ABSTRACT

In the antisaccade paradigm, subjects are instructed to fixate a central point, and then move their eyes towards a position in space in the opposite direction but equidistant to a peripheral, sudden onset target. Antisaccade errors occur when subjects are "distracted" by the target and make a saccade towards it. These errors are more common in patients with schizophrenia but the underlying cause remains unclear. To determine whether antisaccade errors simply reflect a general inability to maintain fixation or are the consequence of a more specific deficit in the strategic control of internally generated actions, patients with first-episode schizophrenia and healthy controls performed three saccadic paradigms which shared the core feature of requiring a prepotent saccade to be suppressed, but varied in their concurrent cognitive demands. We found that both groups showed an increase in errors as the cognitive demands increased across task. However, this increase was significantly steeper in the schizophrenic patients than in the controls. We also found that schizophrenic patients were as able as controls to inhibit prepotent saccades towards a target in a paradigm with no other cognitive demands. Possible explanations of these results include reduced working memory resources and impaired motor preparation in schizophrenia.


Subject(s)
Saccades , Schizophrenia/physiopathology , Schizophrenic Psychology , Adult , Attention , Female , Fixation, Ocular , Humans , Male , Schizophrenia/diagnosis , Task Performance and Analysis
19.
Phys Rev Lett ; 87(24): 244301, 2001 Dec 10.
Article in English | MEDLINE | ID: mdl-11736504

ABSTRACT

We present a study of the influence of interparticle cohesive forces on the packing of spheres. This is achieved by changing the external magnetic field on iron spheres in the millimeter size range. The force of cohesion between two spheres is measured by opposing magnetic and gravitational force. The void fraction of the bed resulting from many spheres being poured into a container at a given magnetic field is measured. The void fraction of the packed spheres as a function of interparticle force is thus established. We find that the void fraction is determined only by the ratio of interparticle force to particle weight, regardless of particle size. This is shown to be a universal effect, not limited to magnetic systems.

20.
Psychopharmacology (Berl) ; 157(3): 284-91, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11605084

ABSTRACT

RATIONALE: Smooth pursuit abnormalities have been observed in antipsychotic naive first-episode patients, suggesting that they are intrinsic to the illness. However, it is not clear whether these abnormalities are as severe as those observed in more chronic patients. In addition, although research suggests that there are no short-term effects of conventional antipsychotic medication, the effects of long-term antipsychotic medication on smooth pursuit eye movements are relatively unknown. OBJECTIVES: To determine the short and long term effects of antipsychotic medication on the smooth pursuit performance of first-episode and chronic patients with schizophrenia. METHODS: We compared the smooth pursuit performance of antipsychotic-treated and untreated first-episode and chronic schizophrenic patients with healthy controls using a comprehensive range of performance measures. This included velocity gain, the number, type and size of intrusive and corrective saccades, and the average time between the change in direction of the target and the change in direction of the eye movement, a measure of subjects' ability to predict target movement. RESULTS: Chronic schizophrenic patients had significantly reduced velocity gain, took longer to respond to the change in target direction and made more catch-up saccades than both first-episode schizophrenic patients and controls. First-episode patients were impaired relative to controls only on the measure of velocity gain. There were no differences between antipsychotic-naive and treated first-episode patients. Antipsychotic-free chronic patients were significantly less impaired on velocity gain than matched continuously treated chronic patients. These results were not influenced by group differences in age and symptom severity. CONCLUSIONS: These results show that: 1) the main index of smooth pursuit, velocity gain, is impaired early in the course of schizophrenia; 2) whereas velocity gain is unaffected by short-term (weeks) medication, it is worsened by chronic (years) treatment; 3) other indices of smooth pursuit, catch-up saccades and ability to predict target movement, are adversely influenced by illness chronicity rather than medication.


Subject(s)
Antipsychotic Agents/adverse effects , Pursuit, Smooth/drug effects , Schizophrenic Psychology , Adult , Antipsychotic Agents/therapeutic use , Chronic Disease , Female , Humans , Male , Prospective Studies , Schizophrenia/drug therapy , Time Factors
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