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Biomedical subjects

S Boyd

Publications and source records attributed to S Boyd.

At least 37 records · Page 2Linked to original sources
PubMed2000

Intracranial evidence for differential encoding of frequency and duration discrimination responses.

OBJECTIVE: To identify cortical areas involved in auditory detection and discrimination of frequency and duration stimuli in an awake child. DESIGN: Single case study recording intracranial auditory event-related potentials to auditory odd-ball stimuli varying in duration and/or frequency. RESULTS: N1 wave to detection was recorded maximally just above the Sylvian fissure 1 cm posterior to the mismatch negativity (MMN) response to discrimination. Frequency MMN overlapped with the N1 whereas duration MMN appeared 100 msec later. MMN to both duration and frequency appeared as an additive bifid response. CONCLUSIONS: It is suggested that feature-specific neuronal networks are activated after changes in sounds, which may underpin a fast parallel preattentive process (MMN).

Adolescent↗
PubMed2000

Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.

Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms. This is one of several efforts being made by the FDA, the electronic medical device industry and the EAS industry to mitigate the potential for EMI between EAS and medical devices.

Electromagnetic Fields↗
PubMed1999

Ultrastructural and electrophysiological correlation of the genotypes of NCL.

Several genetically different, but clinically similar childhood forms of neuronal ceroid lipofuscinosis are now recognized. Accurate diagnosis is important so that appropriate genetic advice can be given, molecular analysis can be undertaken, and prenatal testing can be considered. A combined clinical, electrophysiological, and histological (light and electron microscopy) approach offers the most reliable means of diagnosis in the majority of patients. Patients with an unusual presentation will also be identified.

Electroencephalography↗
PubMed1999

The significance of bilateral EEG abnormalities before and after hemispherectomy in children with unilateral major hemisphere lesions.

The rate of seizure relief following hemispherectomy varies between 50 and more than 80%. There has been particular debate concerning the significance of bilateral electroencephalography (EEG) abnormalities in influencing prognosis. This study was set out to determine the frequency of bilateral EEG abnormalities and their relationship to underlying pathology and outcome. We investigated 28 children with unilateral hemisphere lesions, who underwent hemispherectomy. Interictal and ictal EEGs before and after hemispherectomy were reviewed. Post-operative outcome with respect to seizures was noted. Bilateral EEG abnormalities were seen in 75%, but were more common in children with malformations of cortical development than in patients with acquired cerebral lesions, and were found more often in interictal than in ictal records. Post-operative EEG abnormalities were variable and did not consistently predict outcome. Short-term outcome was similar, irrespective of aetiology. With longer term follow-up, only 47% of children with developmental abnormalities were still seizure-free in contrast to 77% of children with acquired abnormalities. Although the incidence of bilateral EEG abnormalities in patients with major unilateral hemisphere lesions is high, these findings alone should not preclude further consideration for hemispherectomy. Our findings emphasise that the aetiology of the lesion plays a major role in determining outcome.

Adolescent↗
PubMed1999

Intracranial auditory detection and discrimination potentials as substrates of echoic memory in children.

In children, intracranial responses to auditory detection and discrimination processes have not been reported. We, therefore, recorded intracranial event-related potentials (ERPs) to both standard and deviant tones and/or syllables in 4 children undergoing pre-surgical evaluation for epilepsy. ERPs to detection (mean latency = 63 ms) and discrimination (mean latency = 334 ms) were highly localized to areas surrounding the Sylvian fissure (SF). These potentials reflect activation of different neuronal populations and are suggested to contribute to the scalp recorded auditory N1 and mismatch negativity (MMN).

Adolescent↗
PubMed1999

Quality of life after radical cystectomy for bladder cancer in patients with an ileal conduit, cutaneous or urethral kock pouch.

PURPOSE: Radical cystectomy for bladder cancer is associated with many changes in bodily function with sexual and urinary dysfunction most prevalent. However, little research has been done on how efforts to improve erectile function relate to quality of life. Also, the psychological benefits associated with continent urinary diversion have not been fully explored. We compared long-term quality of life outcomes among 3 urinary diversion groups, and between patients who had and had not received an inflatable penile prosthesis. MATERIALS AND METHODS: The 224 participating patients completed 4 self-reporting questionnaires, including the profile of mood states, and adapted versions of the sexual history form, body image dissatisfaction scale and quality of life questionnaire. We compared self-reports of emotional distress, global quality of life, sexuality, body image dissatisfaction, urinary diversion problems, and problems with social, physical and functional activities in patients with advanced bladder cancer who underwent urinary diversion, including an ileal conduit in 25, cutaneous Kock pouch in 93 and urethral Kock pouch in 103. Patients who had or had not received an inflatable penile prosthesis after cystectomy were also compared in regard to quality of life variables. RESULTS: Regardless of type of urinary diversion the majority of patients reported good overall quality of life, little emotional distress and few problems with social, physical or functional activities. Problems with urinary diversion and sexual functioning were identified as most common. After controlling for age analysis of variance showed no significant differences among urinary diversion subgroups in any quality of life area. However, t tests controlling for age indicated that penile prosthesis placement was significantly associated with better sexual function and satisfaction. CONCLUSIONS: Quality of life appears good in these long-term survivors of advanced bladder cancer. The type of urinary diversion does not appear to be associated with differential quality of life. Findings suggest that physicians may wish to discuss urinary diversion problems and sexual dysfunction as long-term correlates of radical cystectomy for bladder cancer. Furthermore, they may also wish to discuss the option of erectile aids in men with erectile dysfunction after cystectomy.

Adult↗
PubMed1999

Paradoxic reaction to lamotrigine in a child with benign focal epilepsy of childhood with centrotemporal spikes.

UNLABELLED: A girl aged 5 years developed nocturnal seizures (mouth twitching, salivation, anarthria, with right arm jerking and occasional secondary generalisation), with frequent focal sharp waves over the left centrotemporal region in her EEG, suggesting benign childhood epilepsy with centrotemporal spikes (BECTS). Seizures became diurnal and frequent, not modified by carbamazepine (CBZ) or valproate (VPA) but responding to VPA and lamotrigine (LTG) with recommended dosage schedules for this combination. Her school performance then deteriorated insidiously, with poor memory and concentration, clumsiness, stuttering, and emotional lability. After 4 months, new episodes, < or =10 per day, occurred. These lasted a few seconds; she stared into space, her jaw dropped, her head dropped to the right, and her eyelids flickered. She usually maintained awareness. Attacks were often provoked by blowing or sneezing. Ictal EEG showed anterior-predominant 3/s sharp-slow wave complexes lasting < or =8 s, with bilateral rolandic discharges interictally. Withdrawal of LTG resulted in rapid improvement in cognitive function and gradual remission of the new attacks. CONCLUSIONS: This appears to be a paradoxic reaction to LTG in the setting of BECTS.

Acute Disease↗
PubMed1999

Sturge-Weber syndrome: cerebral haemodynamics during seizure activity.

The aim of this study was to examine the haemodynamic response to seizures in three infants with Sturge-Weber syndrome by measuring regional cerebral blood flow using transcranial Doppler sonography and 99mTc HMPAO SPECT. Time-locked video/digital EEG recording was carried out for ictal studies. MRI was performed in all subjects. SPECT showed hemispheric hypoperfusion interictally in all three patients and also ictally in one of the three; a small region of hyperperfusion was seen on the same ictal scan in the latter, ie. the patient with interictal and ictal hypoperfusion. In the two older children middle cerebral artery velocity (MCAV) was reduced by between 29 and 62% in the middle cerebral artery of the predominantly affected hemisphere compared with the contralateral side. During seizures, increases of 6 to 30% in MCAV were recorded for the clinically seizing hemisphere compared with 24 to 170% for the contralateral side in four of the seizures recorded. In one infant, MCAV fell bilaterally during a seizure that generalized (-18 and -43% in the predominantly affected and contralateral side respectively). Sequential recordings in one infant suggested that, with time, the haemodynamic response to seizures of the unaffected hemisphere may decrease. These findings suggest that the venous malformation in SWS is associated with an impairment of the cerebral haemodynamic response to seizure activity.

Cerebral Cortex↗
PubMed1998

Breakdowns on the path of chronic illness: opportunities for learning.

An unusual case of calciphylaxis, presenting at the onset of end-stage renal disease and evolving into an extended and arduous hospital stay, is described. The medical approach to this case is addressed briefly, but the main focus of this paper is to describe, in the words of various participants, the events and interactions that occurred and to learn from this description how our management of such cases breaks down. When confronted by difficult circumstances, it is common for us to react emotionally in ways that are automatic and based on our own personal histories and behavior patterns. Such automatic reactions prevent us from seeing and understanding what we really need to know about a given situation and leave us vulnerable to discouragement and internal suffering when clinical events do not go well (A. Nierenberg, personal communication, April 1998). The result is often exasperation with patients and families, as well as emotionally laden interactions that do not forward problem solving. In retrospect, the appearance of such breakdowns is not only predictable in the course of chronic illness, but offers us the opportunity to observe our automatic reactions, to re-evaluate our approach, and to redesign our actions. We have written this review, not to find error or blame, but rather to emphasize that we are learning to view these breakdowns as signals first to step back from our automatic reactions and then to listen and communicate clearly as a means to navigating the best pathway through difficult and discouraging clinical challenges.

Calciphylaxis↗
PubMed1997

Epileptic nystagmus in infancy.

Epileptic nystagmus (EN) is a rare form of nystagmus that occurs only during epileptic seizures. We report an infantile case in which EN was first noted at 10 days of age. Electronystagmography showed a right-beating nystagmus with predominantly linear slow phases that traversed the midline. Neuro-imaging revealed dysplasia of the left middle temporal gyrus extending posteriorly into the parieto-occipital cortex. The right hemisphere and subcortical structures appeared normal. Perfusion studies demonstrated interictal hypoperfusion with ictal hyperperfusion in the left temporal lobe. Electrocorticography demonstrated spiking over the left temporal-parieto-occipital region. Following extensive surgical resection of this area and weaning of anti-convulsants, the child has remained seizure-free without nystagmus. This case demonstrates the cortical origin of EN, and shows that infant cortex has functioning efferent connections to brainstem oculomotor centres from 10 days of age.

Electroencephalography↗
PubMed1997

Validation of the MCMI-III PTSD scale among combat veterans.

The new MCMI-III Posttraumatic Stress Disorder (PTSD) scale was validated on 104 combat veterans who were divided into two groups, PTSD Treatment Group and Non-PTSD Treatment Group. PTSD status was carefully determined by clinical interview and therapists' reports. The Combat Exposure Scale, the Mississippi Scale for Combat-related PTSD, and the Impact of Events Scale were also given. Analysis showed that the MCMI-III PTSD scale had a low internal consistency, but that it significantly differentiated the two groups and significantly correlated to those on other PTSD self-report scales. This scale appeared to be influenced by an acquiescent response style. Further validation studies are needed.

Adult↗
PubMed1997

Instantaneous cloth-based enzyme immunoassay for the semi-quantitative visual determination of antibodies.

An antigen-coated cloth segment was placed onto a blotting pad. The cloth was blotted with one drop of an antibody sample, immediately washed with five drops of a washing solution, exposed to one drop of an anti-antibody-peroxidase conjugate, washed, and finally exposed to a peroxidase substrate. The colored peroxidase product was determined either visually or colorimetrically with the color intensity being correlated to the antibody concentration. This rapid assay would facilitate field serodiagnosis of human and animal diseases.

Animals↗
PubMed1996

Effects of Outward Bound Experience as an adjunct to inpatient PTSD treatment of war veterans.

There is a paucity of studies on Outward Bound Experiences (OBE) with adult psychiatric populations and, more notably, with trauma victims. This study evaluates the efficacy of OBE as an adjunct to specialized inpatient PTSD treatment with survivors of chronic combat-related PTSD (N = 219) at two Veterans Administration Medical Centers. On several measures of PTSD and general adaptation, results showed that the five-day OBE did not differ from standard treatment of PTSD survivors. Two other issues were addressed: identification of successful and non-successful subjects as a result of OBE, and exploration of objective versus subjective measures among this chronic group. Finally, as a post-study analysis, inferred curative components of the OBE were discussed as each appeared to impact on the participants.

Adult↗
PubMed1996

Assessment of older combat veterans with the clinician-administered PTSD scale.

A study of the posttraumatic stress disorder (PTSD) among older combat veterans of World War II and the Korean Conflict was conducted. The Clinician-Administered PTSD Scale (CAPS) was given to 125 older combat veterans, along with a computerized variant of the Structured Clinical Interview for DSM-III-R for PTSD, the SCID-DTREE. (The SCID-DTREE was itself validated against the full SCID). Results showed the CAPS to be a good discriminator of PTSD: Out of the 125 cases, only 9 were misclassified using the SCID-DTREE as the base measure, a 93% efficiency. An alpha on the full CAPS was .95. This suggests that the CAPS is an appropriate scale for use with older combat veterans.

Aged↗
PubMed1996

Electron microscopy and immunocytochemistry in the assessment of renal biopsy specimens: actual and optimal practice.

AIMS: To determine the variation in practice of British renal histopathologists in the use of immunohistochemistry and electron microscopy in the investigation of renal biopsy specimens; to attempt to identify a consensus on what acceptable practice should be; and to satisfy requests from laboratories which have found immunoperoxidase methods unreliable on renal biopsy specimens, by disseminating methods from laboratories which have had success. METHODS: A questionnaire was sent to all 58 laboratories which participate in the UK National Renal Pathology External Quality Assessment Scheme. RESULTS: A response rate of 88% was achieved. Most laboratories use immunocytochemistry and electron microscopy to investigate most renal biopsy specimens, but a few use these methods only rarely and one, never. There is a widespread wish to switch from immunofluorescence to immunoperoxidase, but this is frustrated by the unreliability of the method. This seems to be mainly because of the need to tailor the time of enzyme pretreatment to each biopsy specimen. CONCLUSIONS: The majority view is that electron microscopy and immunocytochemistry are necessary in the investigation of most native renal biopsy specimens, and the few pathologists who report renal biopsy specimens without these methods risk accusations of negligence. Difficulty in using fixed renal tissues for immunocytochemistry stem largely from variations in the requirement for enzyme pre-digestion. Even where immunoperoxidase methods are usually successful, the occasional use of immunofluorescence in parallel to check that false negatives are not occurring is advocated. In all cases it is wise to keep some frozen cortex in reserve in case there is an unexpected or inconsistent immunoperoxidase result.

Humans↗
PubMed1996

Personality scales as predictors of older combat veterans with posttraumatic stress disorder.

The sparse literature on Posttraumatic Stress Disorder among older combat veterans has not explored individual personality styles. 120 older combat veterans who were treatment-seeking in medical and psychiatric outpatient clinics, were assessed whether two personality styles (identified in other research as potentially reflective of PTSD) added to the problems of PTSD beyond the information associated with the stressors of combat and aging. Analyses indicated that the personality style, Sensitivity, was significantly related to PTSD beyond these other factors.

Aged↗