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Biomedical subjects

M S Stanford

Publications and source records attributed to M S Stanford.

15 recordsLinked to original sources
PubMed2002

Antibiotics versus control for toxoplasma retinochoroiditis.

BACKGROUND: Acute toxoplasma retinochoroiditis causes transient symptoms of ocular discomfort and may lead to permanent visual loss. Antibiotic treatment primarily aims to reduce the risk of permanent visual loss, recurrent retinochoroiditis, and the severity and duration of acute symptoms. There is uncertainty about the effectiveness of antibiotic treatment. OBJECTIVES: The objective of this review was to compare the effects of antibiotics versus placebo or no treatment for toxoplasma retinochoroiditis. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register - CENTRAL/CCTR, which contains the Cochrane Eyes and Vision Group Specialised Register (Cochrane Library Issue 2, 2001), MEDLINE (1966 to August 2001), EMBASE (1980 to September 2001), Dissertation Abstracts (1861 to June 2001), LILACS (1982 to 1998), Pascal (1984 to March 2000), proceedings of the Association for Research in Vision and Ophthalmology (1980 to 2001), international symposia on uveitis, and reference lists of review articles. Pharmaceutical companies were contacted for unpublished trials. SELECTION CRITERIA: We included randomised controlled trials that compared any systemic antibiotic treatment against placebo or no treatment. Trials that included immunocompromised patients were excluded. DATA COLLECTION AND ANALYSIS: The primary outcomes for this review were visual acuity at least three months after treatment and risk of recurrent retinochoroiditis. Secondary outcomes were improvement in symptoms and signs of intraocular inflammation, size of lesion and adverse events. Effect measures were pooled using a random effects model. MAIN RESULTS: Three trials, which randomised a total of 173 participants, met the inclusion criteria. All trials were methodologically poor. None reported the effect of treatment on visual acuity. Two studies reported results for recurrent retinochoroiditis: one (124 participants) found a significant reduction in participants with chronic recurrent disease who were treated for 14 months: relative risk 0.28 (95% confidence interval 0.10 to 0.78); the other (20 participants) found no evidence of an effect in participants with acute toxoplasma retinochoroiditis (relative risk 1.00, 95% confidence interval 0.07 to 13.87). Two studies reported an improvement in intraocular inflammation in treated compared with untreated participants and one study reported no difference. Two studies found an increased risk of adverse events in treated participants. REVIEWER'S CONCLUSIONS: There is a lack of evidence to support routine antibiotic treatment for acute toxoplasma retinochoroiditis. There is weak evidence to suggest that long-term treatment of patients with chronic recurrent toxoplasma retinochoroiditis may reduce recurrence. Placebo controlled trials of patients with acute and chronic toxoplasma retinochoroiditis affecting any part of the retina are required to determine the effectiveness of antibiotic treatment.

Anti-Bacterial Agents↗
PubMed2001

A double-blind placebo-controlled crossover study of phenytoin in individuals with impulsive aggression.

The present study examines the behavioral and psychophysiological effects of phenytoin (PHT) in individuals who display impulsive-aggressive outbursts. In a double-blind placebo-controlled crossover design, individuals meeting previously established criteria for impulsive aggression were administered PHT and placebo during separate 6-week conditions. The efficacy measures used were the Overt Aggression Scale (OAS) and the Profile of Mood States (POMS). Psychophysiological measures (evoked potentials) were taken at baseline and at the end of each 6-week condition. Photic stimulation was used to evoke the mid-latency P1-N1-P2 waveform complex. Analysis indicated a significant decrease in the frequency of impulsive-aggressive outbursts during PHT administration compared to baseline and placebo. Analysis of the psychophysiological data showed significantly increased P1 amplitude and significantly longer N1 latency during PHT administration. In addition, a reduction in N1 amplitude during PHT administration was also suggested. These findings indicate reparation of physiological abnormalities previously observed in impulsive-aggressive individuals and imply more efficient sensory processing and effective orienting of attention. Taken together, these results provide insight as to the physiological mechanisms by which PHT serves to ameliorate impulsive-aggressive behavior.

Adult↗
PubMed2001

Impact of threat relevance on P3 event-related potentials in combat-related post-traumatic stress disorder.

The purpose of this study was to examine electrophysiological response to trauma-relevant stimuli in combat-related post-traumatic stress disorder (PTSD). Study design incorporated comparison of 10 Vietnam War veterans with PTSD diagnosis to 10 Vietnam War veterans with no mental disorder diagnosis on P3 components in a series of two oddball tasks (trauma-relevant threat, trauma-irrelevant threat) counterbalanced for order. Each task included high probability emotionally neutral distractor words and low probability neutral target words, but differed in the content of low probability threat words. Whereas threat words in the trauma-relevant oddball task pertained directly to combat trauma, threat words in the trauma-irrelevant oddball task were socially threatening words. Results revealed that, in comparison to healthy combat veterans, those diagnosed with PTSD demonstrated: (a) attenuated P3 response to neutral target items at selected electrode sites across both oddball tasks; and (b) increased responsivity to trauma-relevant combat stimuli but not to trauma-irrelevant social-threat stimuli at frontal electrode sites (F3, F4). Results are consistent with resource allocation models of PTSD, which suggest that PTSD is characterized by attentional bias to threat stimuli at the expense of attention to emotionally neutral information.

Affect↗
PubMed2001

Mid-latency evoked potentials in self-reported impulsive aggression.

The present study was conducted to examine psychophysiological differences in arousability among individuals who display impulsive aggressive outbursts. Amplitude and latency for the mid-latency evoked potentials (P1, N1 and P2) were obtained at scalp electrode sites. The evoking stimuli were three intensities (low, medium, high) of photic stimulation. Compared to non-aggressive controls, impulsive aggressive subjects showed significantly reduced P1 amplitude, which is indicative of an inefficient sensory gating mechanism. In addition, these subjects exhibited significantly larger N1 amplitude implying an enhanced orienting of attention to stimuli. Impulsive aggressive subjects also exhibited shorter P1, N1 and P2 peak latency. These results suggest that impulsive aggressive individuals may display quicker orienting and processing of stimuli in an attempt to compensate for low resting arousal levels. Finally, impulsive aggressive subjects augmented the P1-N1 component more frequently than controls, which is consistent with previous studies examining impulsivity and sensation seeking. Together, these findings extend previous work concerning the underlying physiology of impulsive aggression. It has been suggested that impulsive aggressive individuals may attempt to compensate for low resting arousal levels by engaging in stimulus seeking behaviors. Accordingly, the present findings imply similar physiological compensatory responses as demonstrated by heightened orienting of attention, processing and arousability. In addition, a compromised sensory gating system in impulsive aggressors may exacerbate such circumstances, and lead to later cognitive processing deficits.

Aggression↗
PubMed2001

Personality and neurocognitive correlates of impulsive aggression in long-term survivors of severe traumatic brain injury.

This study addresses a common outcome of severe traumatic brain injury (TBI), disinhibited aggressive behaviour. This behaviour has been classified in aggression literature as 'impulsive aggression' (IA). The purpose was to: (1) characterize those TBI patients who are likely to be an aggression risk, and (2) determine if TBI patients with IA demonstrate personality style and neurocognitive performance similar to that seen in other IA groups. Participants were 45 survivors of severe TBI (26 of whom had persisting problems with IA), who were clients of a residential brain injury treatment facility. IA participants had a higher incidence of pre-morbid aggressive behaviour, were younger, had a shorter tenure in the programine, and were more impulsive, irritable, and antisocial than the non-aggressive control participants. Unlike past research, no neurocognitive differences were found. The results are discussed in terms of the conceptualization, identification, and treatment of persisting IA in severe TBI.

Adult↗
PubMed1999

Impulsive and premeditated aggression: a factor analysis of self-reported acts.

Although aggression research in general has been hampered by a lack of objective measurements of aggressive acts, two types of aggressive acts, impulsive vs. premeditated, have been studied extensively in recent years. These two types of aggression have been primarily measured by structured or semi-structured interviews. The current study was designed to assess the construct validity of these two types of aggression using a self-report questionnaire which included items gleaned from the content of interviews used in past studies. For this study, 216 college students assessed their own aggressive acts rather than answering general questions about aggression. The students were not significantly different from normative sample groups on self-report measures of impulsiveness, aggression, and anger/hostility. A PCA factor analysis with a promax rotation of the items on the self-report questionnaire identified four factors: impulsive aggression; mood on the day the act occurred; premeditated aggression; and agitation. Thus, impulsive and premeditated aggression are independent constructs which exist in varying degrees among these 'normal' persons in a non-clinical sample. Impulsive aggression was characterized in part by feelings of remorse following the acts and by thought confusion. Premeditated aggression was related to social gain and dominance.

Adult↗
PubMed1999

P300 under standard and surprise conditions in self-reported impulsive aggression.

1. The purpose of the present study was to determine the cognitive psychophysiological correlates of impulsive aggression in a "high" functioning sample: college students. 2. Visual P300 was measured during a standard oddball task and a surprise task that included unexpected low probability stimuli. 3. Results indicated significantly reduced P300 amplitude and prolonged latency for impulsive aggressive subjects to target stimuli on the standard task. Target amplitude differences where further augmented under conditions involving unexpected stimuli although no significant latency differences were observed. The topography of P300 amplitude to unexpected stimuli differed from that of the target. 4. Topographic group differences found for unexpected stimuli are suggestive of cognitive processing deficits previously demonstrated using neuropsychological techniques in impulsive aggressive individuals.

Adolescent↗
PubMed1999

Cognitive and emotional sequelae of cerebellar infarct: a case report.

The cerebellum has long been the subject of scientific investigation, but its role in nonmotor functions has only recently begun to receive serious consideration. Despite the growing literature linking the cerebellum to nonmotor/cognitive functions in humans, some controversy remains concerning the cerebellum's role in these processes. We present a patient who developed both specific language processing and verbal memory deficits and emotional changes in the context of normal intelligence following a bilateral cerebellar ischemic stroke. Despite having multiple localized cerebellar lesions, this patient had no significant motor problems, nor was there radiological evidence of focal forebrain lesions to which the cognitive and emotional effects might be attributed. The role of the cerebellum in cognition and the relevance of cerebellum-associated cognitive/emotional dysfunction to the practicing clinician are discussed.

Journal Article↗
PubMed1998

Auditory P300 and self-reported impulsive aggression.

1. The purpose of the present study was to determine the cognitive psychophysiological correlates of impulsive aggression in a population considered "normal" by societal standards: college students. 2. Auditory event-related potentials were acquired on all subjects during a standard oddball task. The stimuli consisted of a random sequence of two tones, a frequent 1,000 Hz tone and a rare 2,000 Hz tone. Tones were presented in a ratio of 80/20. 3. Results of the study demonstrated that impulsive aggressive subjects show significantly lower P300 amplitude at frontal electrode sites when compared to nonaggressive controls. 4. These findings are consistent with the psychophysiological findings in impulsive aggressive incarcerated criminals and support the notion of a specific behavioral syndrome associated with spontaneous aggressive outbursts.

Adolescent↗
PubMed1997

Neuropsychological and cognitive psychophysiological substrates of impulsive aggression.

The purpose of this study was to test whether subjects who commit impulsive vs non-impulsive aggression differ on measurements of personality, neuropsychology, and cognitive psychophysiology, and whether these differences can yield information regarding the etiology of impulsive aggression. Subjects were two groups of prison inmates, distinguished by their committal of impulsive or nonimpulsive aggression, and matched noninmate controls. All inmates met DSM III-R criteria for an antisocial personality disorder but for no other disorder. Impulsiveness, anger, and peak P300 latencies did not differ between the inmate groups, but verbal symbol decoding and peak P300 amplitudes did. Impulsiveness and verbal skills were inversely correlated. Impulsiveness was inversely correlated with, and verbal skills positively correlated with P300 amplitudes. The results indicate that aggression is not homogenous, even among antisocial persons, and that impulsive aggression is related to neuropsychological and cognitive psychophysiological measures of information processing beyond those factors related to criminality alone.

Adult↗
PubMed1997

The effects of phenytoin on impulsive and premeditated aggression: a controlled study.

Studies of the effects of phenytoin on aggression have produced equivocal results primarily because of a lack of (1) common objective criterion measures of aggressive acts across studies; (2) rigorous inclusion and exclusion criteria for selecting subjects; and (3) a nosologic basis for classifying different types of aggression. The current study was designed to remedy these deficiencies. Aggression was defined using a nosology that defines three types of aggression: (1) medically related; (2) premeditated; and (3) impulsive. The purpose of this study was to test the hypothesis that phenytoin will decrease impulsive aggressive acts but not have a significant influence on premeditated aggressive acts. Sixty inmates were divided into two groups on the basis of committing primarily impulsive aggressive acts or premeditated aggressive acts while in prison. Medical aggression was ruled-out by subject selection. The study used a double-blind, placebo-controlled, crossover design. As hypothesized, phenytoin (200 mg a.m. and 100 mg p.m.) significantly reduced impulsive aggressive acts but not premeditated aggressive acts. Event-related potentials (ERPs) measured information processing in the cortex during drug/placebo conditions. The amplitudes of P300 ERP waveforms among impulsive aggressive subjects were increased significantly during the phenytoin condition but not during the placebo condition. There were no significant changes in P300 ERP waveforms between drug/placebo conditions among nonimpulsive aggressive subjects.

Adult↗
PubMed1996

Verbal skills, finger tapping, and cognitive tempo define a second-order factor of temporal information processing.

Adolescents with academic and social problems are often characterized as impulsive, having poor verbal skills, and having poor motor coordination. Language and skilled movements have long been hypothesized to share a common neural basis. The purpose of this study was to test the hypothesis that verbal skills, fine motor tasks that require a continuous sequential response, and cognitive tempo (impulsiveness, time judgment) would interrelate to define a higher-order dimension of "temporal information processing." Subjects were 155 males of high school age. The results confirmed the basic hypothesis.

Adolescent↗
PubMed1995

Factor structure of the Barratt impulsiveness scale.

The purpose of the present study was to revise the Barratt Impulsiveness Scale Version 10 (BIS-10), identify the factor structure of the items among normals, and compare their scores on the revised form (BIS-11) with psychiatric inpatients and prison inmates. The scale was administered to 412 college undergraduates, 248 psychiatric inpatients, and 73 male prison inmates. Exploratory principal components analysis of the items identified six primary factors and three second-order factors. The three second-order factors were labeled Attentional Impulsiveness, Motor Impulsiveness, and Nonplanning Impulsiveness. Two of the three second-order factors identified in the BIS-11 were consistent with those proposed by Barratt (1985), but no cognitive impulsiveness component was identified per se. The results of the present study suggest that the total score of the BIS-11 is an internally consistent measure of impulsiveness and has potential clinical utility for measuring impulsiveness among selected patient and inmate populations.

Analysis of Variance↗
PubMed1993

In utero exposure to fluoxetine HCl increases hematoma frequency at birth.

The present study was undertaken to determine if fluoxetine HCl (Prozac, Dista Products Ltd., Liverpool, UK) might cause adverse vascular effects, such as hematomas, in rats exposed in utero. Gravid Sprague-Dawley rats were administered 5.62 mg/kg fluoxetine HCl by oral gavage beginning on day 7 of gestation and ending the day of birth. A control group received distilled water by oral gavage during gestation. At birth, offspring of both groups were assessed for visible adverse vascular effects. Fluoxetine HCl-exposed offspring showed a statistically higher frequency of skin hematomas when compared to water controls. This result is consistent with known adverse effects of fluoxetine and lends support to a recently published report that attempted to link fluoxetine HCl use to bleeding episodes in eight patients being treated for obsessive-compulsive disorder. The results of this study suggest caution in the prolonged use of this medication during pregnancy and in patients with predisposing conditions that may increase the chances of bleeding.

Animals↗