Biomedical subjects

S W Brown

Publications and source records attributed to S W Brown.

At least 37 records · Page 2Linked to original sources

PubMed1997

Internal and external distraction in the control of cold-pressor pain as a function of hypnotizability.

The effectiveness of different pain-distraction tasks was compared as a function of level of hypnotizability, using the cold-pressor pain-testing procedure. Selected high, medium, or low hypnotizable participants first underwent a 1-minute baseline immersion of a hand in ice water, with periodic pain ratings. Independent groups were then given 4-minute test immersions under one of five conditions. Analgesia suggestion and guided imagery were conceived to be internal distractors, whereas word memory and pursuit-rotor tasks were external distractors. Placebo-control groups were given permission to let their minds wander. All four experimental treatments reduced pain significantly for highly hypnotizable participants, compared to the control group, whereas none of the experimental treatments were effective for low hypnotizables. The different treatment instructions did not produce different preimmersion anxiety state ratings, so the treatment effects on pain ratings could not be explained in terms of their effects on anxiety. It appears that high hypnotizables are more effective than low hypnotizables at diverting attention to control pain, regardless of whether internal or external distractor tasks are used. Treatment effects on pain ratings did not change between 1 and 4 minutes of test immersion.

Adolescent↗

PubMed1997

Attentional resources in timing: interference effects in concurrent temporal and nontemporal working memory tasks.

Three experiments examined interference effects in concurrent temporal and nontemporal tasks. The timing task in each experiment required subjects to generate a series of 2- or 5-sec temporal productions. The nontemporal tasks were pursuit rotor tracking (Experiment 1), visual search (Experiment 2), and mental arithmetic (Experiment 3). Each nontemporal task had two levels of difficulty. All tasks were performed under both single- and dual-task conditions. A simple attentional allocation model predicts bidirectional interference between concurrent tasks. The main results showed the classic interference effect in timing. That is, the concurrent nontemporal tasks caused temporal productions to become longer (longer productions represent a shortening of perceived time) and/or more variable than did timing-only conditions. In general, the difficult version of each nontemporal task disrupted timing more than the easier version. The timing data also exhibited a serial lengthening effect, in which temporal productions became longer across trials. Nontemporal task performance showed a mixed pattern. Tracking and visual search were essentially unaffected by the addition of a timing task, whereas mental arithmetic was disrupted by concurrent timing. These results call for a modification of the attentional allocation model to incorporate the idea of specialized processing resources. Two major theoretical frameworks--multiple resource theory and the working memory model--are critically evaluated with respect to the resource demands of timing and temporal/nontemporal dual-task performance.

Adult↗

PubMed1996

Electrocardiograph QT lengthening associated with epileptiform EEG discharges--a role in sudden unexplained death in epilepsy?

EEG with co-registered electrocardiography was recorded during at least two interictal epileptiform EEG discharges in each of 11 patients who later suffered from sudden unexpected death in epilepsy (SUDEP), and from another 11 age and sex matched patients, also with uncontrolled tonic-clonic seizures, drawn from the same centre who were still alive at the time of investigation (non-SUDEPs). A corrected QT interval for rate (QTc) was obtained and a mean value calculated for the period immediately prior to discharge, during discharge and immediately post discharge. Mean QTc was also obtained interictally without discharge. There was a significant (P = 0.01) increase in the mean QTc during discharge compared to that measured interictally without discharge for the whole population of SUDEPs and non-SUDEPs, and this was maintained for the SUDEPs alone (P = 0.02) but did not hold for the non-SUDEP group alone. Although reaching statistical significance, increases in mean QTc in SUDEP patients only exceeded currently accepted upper limits in one case, and then only marginally. The clinical significance of these findings merits further investigation.

Adult↗

PubMed1996

Perceived self-control of seizures in young people with epilepsy.

Evidence now suggests that some people can exert some degree of control over seizure initiation and inhibition. In order to explore this further, 79 young people with epilepsy, attending specialist residential schools, were interviewed regarding awareness of seizure precipitants; recognition of seizure warnings; attempts at seizure inhibition, and ways of self-inducing seizures. Questionnaires with the same content were completed by residential care staff. Results show that many subjects claimed to identify seizure precipitants (63.3%), experienced warnings (70.9%), and had developed means of trying to inhibit seizure occurrence (50.6%). However, in each instance, staff reports were much lower (56.9%, 47.2%, and 22.2%, respectively), and one-to-one concordance was poor. A larger than expected percentage of self-induction was reported for both subjects (8.9%) and staff (9.7%). The implication of these results for both the investigation and treatment of epilepsy are discussed further.

Adolescent↗

PubMed1996

Autogenous regulation of the Bacillus subtilis glnRA operon.

Purified Bacillus subtilis GlnR was shown to bind with high affinity to a specific region that overlaps with the glnRA promoter site. The GlnR binding site includes four copies of a repeated sequence that may be the recognition site for the protein. GlnR inhibited transcription from the glnRA promoter in vitro.

Bacillus subtilis↗

PubMed1995

Physical abuse in Canadian runaway adolescents.

Recent studies with Canadian runaway youth have questioned the prevalence of abuse experienced by teenaged runaways and the causal contribution of such abuse to runaway experiences (Kufeldt, Duriux, Nimmo, & McDonald, 1992; Kufeldt, & Perry, 1989). This is a descriptive investigation of the physical abuse experienced in a sample of 195 Canadian adolescent runaways: the occurrence, nature and frequency of abuse, the age of onset and duration of abuse, the relationship between the victim and the perpetrator(s), and, who, if anyone, knew of the abuse. This investigation compared and contrasted the physical abuse experienced prior and subsequent to runaway experiences. In this sample, 86% of the population (74% of the males and 90% of the females) reported at least one physically abusive experience. The data reported suggest that this population of adolescents have been the victims of chronic, extreme abuse, experienced at a young age, often perpetrated by the biological parent (most often the mother), and was initiated prior to the first runaway episode. Female runaways were at greater risk than males for all types of abuse experience. Once youths left home, the physical abuse experiences decreased in frequency, but grew in severity, particularly for males.

Adolescent↗

PubMed1995

What resources? Addressing the needs of the epilepsy community.

Epilepsy is a condition which spans several disciplines within medicine, as well as having an impact on many non-medical areas such as employment and education. Services for epilepsy in the UK have not been developed according to any coherent strategy and remain fragmented and unevenly distributed. Successive attempts to address these shortcomings by publishing recommendations, even with government assistance, have not led to major improvements. Recent changes in the organization of health care services might at least present an opportunity to effect change by educational initiatives directed towards purchasers and providers. However, the absence of epilepsy from The Health of the Nation objectives represents a failure to get the message through to those with the ability to direct policy. The plethora of new, effective and expensive pharmaceutical treatments should lead to a raising of epilepsy awareness among the medical profession as a consequence of marketing activity, but this is already causing conflict with Family Health Service Associations (FHSAs) and others with equivalent lack of vision. I would suggest that only by politicizing the consumer can the change we seek be brought about.

Community Health Services↗

PubMed1995

Rechallenge with lamotrigine after initial rash.

Eight patients rechallenged with lamotrigine after initial exposure which resulted in a skin rash are reported. On reintroduction of the lamotrigine, six of the patients had no recurrence of the rash. Of the other two patients, one had the occurrence of a mild fluctuating and qualitatively different skin rash on rechallenge. The other patient had developed a dose-related rash on initial challenge resulting in a dose reduction. The first attempt to re-increase the dose resulted in reappearance of the rash which again disappeared on dose reduction. However a further attempt to re-increase the dose did not result in reappearance of a rash. It is suggested that patients who experience a rash but good therapeutic response to lamotrigine might be considered for re-dosing.

Adolescent↗

PubMed1995

Temporal-signal detection and individual differences in timing.

Signal-detection procedures were used in three experiments to examine sensitivity and bias in time judgments and to evaluate individual differences in timing. The task required subjects to judge whether visual stimuli were presented for a certain target duration (the 'signal') or for a slightly longer duration. In experiment 1, subjects performed versions of the task involving both short (2 s) and long (12 s) target stimuli. Analyses of sensitivity and bias measures (d' and beta) provided evidence for consistency in timing performance within individuals. In experiment 2, subjects were tested on a detection task with 5, 10, or 15 s targets, followed by a temporal-reproduction task involving stimulus durations ranging from 3 to 17 s. Subjects with high temporal sensitivity showed less error in their reproductions than subjects with low temporal sensitivity. In experiment 3, subjects were pretested on a detection task with a 12 s target and then performed a temporal-production task where they attempted to generate a series of 12 s intervals under either control or informational feedback conditions. Feedback improved accuracy and reduced variability in temporal productions. However, the low-temporal-sensitivity subjects were more variable in their responses under both conditions than were the high-sensitivity subjects. The results point to the utility of a temporal-signal-detection task both as a means for studying individual differences in timing and as a pretesting technique for assigning subjects to high-sensitivity and low-sensitivity groups to reduce error in time-judgment data.

Analysis of Variance↗

PubMed1995

Time, change, and motion: the effects of stimulus movement on temporal perception.

The effects of stimulus motion on time perception were examined in five experiments. Subjects judged the durations (6-18 sec) of a series of computer-generated visual displays comprised of varying numbers of simple geometrical forms. In Experiment 1, subjects reproduced the duration of displays consisting of stationary or moving (at 20 cm/sec) stimulus figures. In Experiment 2, subjects reproduced the durations of stimuli that were either stationary, moving slowly (at 10 cm/sec), or moving fast (at 30 cm/sec). In Experiment 3, subjects used the production method to generate specified durations for stationary, slow, and fast displays. In Experiments 4 and 5, subjects reproduced the duration of stimuli that moved at speeds ranging from 0 to 45 cm/sec. Each experiment showed that stimulus motion lengthened perceived time. In general, faster speeds lengthened perceived time to a greater degree than slower speeds. Varying the number of stimuli appearing in the displays had only limited effects on time judgments. Other findings indicated that shorter intervals tended to be overestimated and longer intervals underestimated (Vierordt's law), an effect which applied to both stationary and moving stimuli. The results support a change model of perceived time, which maintains that intervals associated with more changes are perceived to be longer than intervals with fewer changes.

Acceleration↗

PubMed1995

Establishing percentiles for junior tennis players based on physical fitness testing results.

An important aspect of this study was the establishment of a data base. A broad data base allows for data on certain parameters to be greatly expanded and will also enhance the use and interpretation of statistical methods. A longitudinal study of these variables may also assist in monitoring the players' progress over a period of time, and can provide a useful supplement to subjective coaching appraisals. The means and standard deviation for each test were calculated according to the USTA age and gender groups, that is, 12s, 14s, and 16s for each separate gender. Additionally, the mean and standard deviations for the ages, heights, and weights of each grouping were also calculated. Once the means and standard deviations were calculated, percentile tables were developed for each of the USTA groupings (by age and gender). The percentiles for each USTA test are presented in Appendix 1. A percentile is defined as the point on the distribution below which a given percentage of the scores is found. Percentiles can provide a norm-referenced interpretation of an individual score within a distribution that often consists of scores from a comparable group of individuals. Using the USTA protocol, players and coaches now have a set of normative data by which individual player's fitness scores may be compared with participants of the USTA Area Training Centers (See appendix 1). From the test results, coaches and players can determine which fitness areas need to be improved for athletes on an individual basis. Specific training programs can then be designed based on an athlete's fitness testing results. Proper interpretation of the USTA fitness testing data base results can lead to an easy way to determine the relative position of a given fitness score in the distribution, recognizing weaker areas for the purpose of injury prevention and performance enhancement. Each player can be given a profile detailing their percentile rank relative to other area training center participants in their age group. Results of these fitness scores can prove to be of great assistance to coaches in designing proper training programs and may also give physicians some indication which weaknesses may potentially lead to injury. The sample player shown in Figure 1 and Table 2 is a right-handed female player ranked in the 12-years-old-and-under division. Her results clearly indicate very high scores in the agility and speed categories; however, her scores in the strength and power areas were significantly lower than other area training center participants in her age group.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1994

Production of recombinant hirudin by high cell density fed-batch cultivations of a Saccharomyces cerevisiae strain: physiological considerations during the bioprocess design.

The conditions for the high cell density fed-batch culture of a Saccharomyces cerevisiae strain producing recombinant hirudin (rHV2-Lys47) have been established. A Leu+ derivative of S. cerevisiae c13ABYS86 was used as the host strain transformed with an expression plasmid containing the gene encoding rHV2-Lys47 and driven by the MF alpha 1 promoter. In order to develop the fed-batch culture protocol, the recombinant strains' physiology was first of all investigated in chemostat culture. The maximum respiratory capacity of the recombinant strain was observed to be between dilution rates of 0.2 and 0.26 h-1, which is typical for laboratory strains as compared to values published for baker's yeasts. Furthermore, maximum biomass yield and product secretion were observed at a dilution rate of approx. 0.15 h-1. The plasmid segregational stability of the recombinant strain showed that the expression plasmid was stable, irrespective of the dilution rates used, for more than 80 generations of growth between dilution rates of 0.043 h-1 and 0.3 h-1. The chemostat data was used to define a fed-batch process. The fed-batch results demonstrated a biomass production of 60 g l-1 CDW and a high production level of recombinant hirudin of 500 mg l-1. Stability of the expression of the gene coding for rHV2-Lys47 was maintained during all the studied fed-batch conditions. The plasmid copy number in the fed-batch remained constant at approx. 43 at a specific growth rate of 0.12 h-1, whereas it increased by 60-95% at a lower dilution rate (mu = 0.06 h-1). Although a variation of the plasmid copy number could be expected, it was postulated from the experimental data that the observed amplification could have been influenced by an environmental effect due to an accumulation of medium components in the supernatant. The results presented here illustrate the importance of a well-balanced medium when considering the production of a recombinant protein in a high cell density cultivation process with high production levels.

Base Sequence↗

PubMed1994

Coroners' autopsy reporting of sudden unexplained death in epilepsy (SUDEP) in the UK.

Sudden Unexplained Death due to Epilepsy (SUDEP) is not uncommon. The incidence may be difficult to ascertain due to variations in reporting the cause of death investigated by coroners. To study this, we used a cuttings service to identify all cases of SUDEP reported in the UK press during 1992. These cases had been investigated by a number of different pathologists and coroners. Post-mortem reports, witness statements and other relevant information were examined in 40 cases. Inconsistencies were observed both in investigations performed and observations made at time of death. Varying degrees of detail concerning 'type' and history of epilepsy were found. In 70% of cases, type of epilepsy was either not known or not referred to. Similar inconsistencies were found with details of medication, position of body, toxicology reporting and detailed examination of organs, particularly the brain. Attributed cause of death varied considerably, with epilepsy stated as primary cause of death in less than half of the sample. Disparity was noted also in coroner's verdicts, with no distinct pattern emerging in relation to attributed cause of death. The wide variation in practice of individual coroners and pathologists in the investigation and registering of sudden deaths raises issues of quality assurance. As the majority of these deaths are unwitnessed, we rely on these investigations and the statements of officials in the process of registering deaths. If we are to build a profile of people who are at risk of SUDEP, epilepsy must be stated on the death certificate. Until this happens, many more of these deaths will go unrecorded.

Adolescent↗

PubMed1994

Some issues in non-convulsive status epilepticus in children and adolescents with learning difficulties.

Individuals with learning difficulties commonly suffer from concomitant conditions; epilepsies constitute up to 35%. The prevalence of epileptic syndromes in learning disabled people is less well documented. Non-convulsive status epilepticus (NCSE) occurs with many epileptic syndromes. It can present with insidious or paroxysmal change of neurovegetative, behavioural, cognitive or affective symptoms which can mistakenly be attributed to other causes. NCSE of generalized epilepsy syndromes can show localizing features and NCSE of localization-related epilepsy can show generalized epileptiform discharge patterns. We reviewed 14 residents' (< 20 years, all learning disabled) EEG recordings in inter-ictal stages and in NCSE and conclude that the current nosological grouping of NCSE does not ensure appropriate categorization in a significant number of cases. We developed a revised NCSE classification: (I) Generalized epileptic syndromes: (a) with no evidence of lateralization inter-ictally or in NCSE; (b) with evidence of lateralization in NCSE only. (II) Localization-related epileptic syndromes: (a) with evidence of lateralization/focal activity in NCSE; (b) with evidence of generalized EEG patterns when in NCSE only; (c) with transient forms: same individual shows generalized and lateralized/focal NCSE activity in different EEGs. We suggest our system be tested in larger studies for its sensitivity, reliability and validity.

Adolescent↗

PubMed1994

Industrial production of heterologous proteins by fed-batch cultures of the yeast Saccharomyces cerevisiae.

This review concerns the issues involved in the industrial development of fed-batch culture processes with Saccharomyces cerevisiae strains producing heterologous proteins. Most of process development considerations with fed-batch recombinant cultures are linked to the reliability and reproducibility of the process for manufacturing environments where quality assurance and quality control aspects are paramount. In this respect, the quality, safety and efficacy of complex biologically active molecules produced by recombinant techniques are strongly influenced by the genetic background of the host strain, genetic stability of the transformed strain and production process factors. An overview of the recent literature of these culture-related factors is coupled with our experience in yeast fed-batch process development for producing various therapeutic grade proteins. The discussion is based around three principal topics: genetics, microbial physiology and fed-batch process design. It includes the fundamental aspects of yeast strain physiology, the nature of the recombinant product, quality control aspects of the biological product, features of yeast expression vectors, expression and localization of recombinant products in transformed cells and fed-batch process considerations for the industrial production of Saccharomyces cerevisiae recombinant proteins. It is our purpose that this review will provide a comprehensive understanding of the fed-batch recombinant production processes and challenges commonly encountered during process development.

Hirudins↗

PubMed1994

A mental health capitation program: I. Patient outcomes.

OBJECTIVE: The Monroe-Livingston demonstration project's capitation payment system (CPS) was evaluated to determine whether capitated funding of mental health care, compared with fee-for-service funding, could reduce hospitalization rates and improve functioning and symptoms for severely and persistently mentally ill adults without increasing the total cost of care. METHODS: The experiment was a communitywide prerandomized clinical trial involving 422 patients. Patients who were randomized into the experimental group were eligible for enrollment in a capitated funding program administered by one of five community mental health centers. Those randomized into the control group received standard fee-based services. Follow-up interviews with patients one and two years after enrollment in the study assessed changes in symptoms and functioning. Data files of the membership corporation that coordinated community mental health services for the CPS provided measures of study patients' use of inpatient mental health services. RESULTS: During the two-year follow-up period, patients in the experimental group had significantly fewer hospital inpatient days than patients in the control group, but the two groups had no significant differences in functioning or level of symptoms. CONCLUSIONS: The CPS successfully maintained severely ill patients in the community but did not improve their functioning or level of symptoms.

Adult↗

PubMed1994

Quality of life--a view from the playground.

The aims of treating epilepsy are to stop seizures, and to neutralize any associated cognitive or psychosocial penalty associated with epilepsy or its treatment. Inappropriate medication and/or continuance of seizures have deleterious effects on quality of life. The Epilepsy Task Force devised a 30-item questionnaire which was sent to children with epilepsy whose families are members of the British Epilepsy Association. The 896 replies which were received within the first two weeks have been analysed. Forty-two per cent of respondents had tonic-clonic seizures. Thirty-five per cent had had no seizures within the previous six months, but 29% reported seizures which occurred at least once a week. Although 42% didn't mind their seizures, the remaining respondents described their seizures as making them feel helpless, scared, panicky, frustrated and different from others. The most common medications were carbamazepine and sodium valproate. Side effects attributed to the medication included tiredness, difficulty in concentrating, dizziness, headache, irritability and weight gain. Thirty-six per cent said that their doctor had never explained about their epilepsy. The questionnaire included space for free-text comments and these were made by more than 400 respondents.

Adolescent↗

PubMed1994

Distinction between places and paths in rats' spatial representations.

Rats were trained on a 3-dimensional, 4-arm radial maze. In Experiment 1, Ss trained to climb to the single goal platform chose fewer novel routes to the goal than Ss trained to climb to the 4 spatially distinct platforms. In Experiment 2 a reinforcement contingency was imposed, requiring a novel route choice on each trial to receive reinforcement. Learning to associate route choice with reinforcement outcome was much more difficult for Ss tested with the single goal than for Ss tested with the 4 distinct goals. In Experiment 3 a partitioned central platform group learned the reinforcement contingency as quickly as the Ss given 4 spatially distinct platforms. In Experiment 4, distinctive floor inserts did not affect performance relative to no inserts.

Animals↗