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Biomedical subjects

B H Smith

Publications and source records attributed to B H Smith.

At least 55 records · Page 3Linked to original sources
PubMed1998

Equivalent effects of stimulant treatment for attention-deficit hyperactivity disorder during childhood and adolescence.

OBJECTIVE: To compare the therapeutic effect size of methylphenidate on attention-deficit hyperactivity disorder (ADHD) during childhood versus adolescence. METHOD: A retrospective follow-up study of 16 individuals with diagnosed ADHD who completed double-blind, placebo-controlled, crossover studies of methylphenidate 0.3 mg/kg during two separate summer treatment programs. The programs were completed when the subjects were children (aged 8 to 11 years) and adolescents (aged 12 to 14.5 years). Dependent variables include objective measures of academic performance and social behavior and ratings completed by counselors and teachers. RESULTS: Effect sizes ranged from very large to small, with most effects in the moderate to large range. Across the 12 dependent variables, t tests found that only 3 showed statistically significant changes in effect size from childhood to adolescence. Putative changes in effect sizes can be dismissed for methodological reasons. CONCLUSION: Stimulant medication is equally effective with children and adolescents with ADHD if they are engaged in similar activities. Treatment providers should rigorously examine environmental causes to problems before prescribing higher doses of stimulants to adolescents with ADHD who exhibit a worsening in functioning.

Achievement↗
PubMed1998

Visual modulation of olfactory learning in honeybees.

We use classical conditioning of the honeybee (Apis mellifera) proboscis extension reflex with a visual (A) and an olfactory (X) conditioned stimulus in a blocking paradigm. Typically, learning about one element (X) of a compound (AX) is decreased (blocked) if the other component (A) has previously been rewarded alone. Our results show that visual pretraining did not produce blocking in honeybees: instead, forward pairings of A with a reward increased subsequent learning about X relative to a backward pairing control. This finding violates the independence assumption, which holds that elements of inter-modal compound stimuli change associative strength independently of each other. Furthermore, it is at odds with common theories of conditioning that predict blocking and assume that the elements of a compound stimulus rely on one common internal reinforcing signal. Taking the functional anatomy of the honeybee brain into account, we suggest that vision and olfaction may not rely on the same internal reinforcing signal; compound interactions might thus reflect the wiring of the honeybee nervous system and the biological significance of different sensory modalities during natural behaviour.

Animals↗
PubMed1998

An analysis of synthetic processing of odor mixtures in the honeybee (Apis mellifera).

Both sensory transduction and central processing of odor mixtures can give rise to several different kinds of interaction, which can influence how well individual components are perceived and processed. In particular, odor mixtures are believed to give rise to 'configural' or 'synthetic' properties that are not characteristic of the components. However, the exact nature of these effects, particularly with regard to their expression in behavior, remains to be examined in detail. Here we use feature-negative and transwitching conditioning paradigms to show that honeybees can use configural cues in odor processing. However, the nature of these configural cues is not similar to that predicted by some models of conditioning. We propose that configural models may be capable of accounting for a substantial portion of odor mixture processing.

Animals↗
PubMed1998

GPs, schoolgirls and sex. A cross cultural background comparison of general practitioner attitudes towards contraceptive service provision for young adolescent females in Scotland.

No previous studies have examined the influences of cultural background on the provision of contraceptive services to females under 16 years of age. A research project was undertaken to investigate any differences between general practitioners trained in the United Kingdom and those trained in the Indian sub-continent in relation to contraceptive service provision to females under 16 years of age. A self-completion postal questionnaire survey was distributed to 230 unrestricted principal general practitioners across Scotland. Subjects were identified from the Medical Register. Half of the sample consisted of all those working in Scotland who had been trained in the Indian sub-continent. The other half were a comparable group that had been trained in the United Kingdom and were selected by quasi-random quota sampling. The response rate was 57 per cent (131/230). General practitioners in the study who had trained in the Indian sub-continent were found to be significantly less likely to provide contraceptive services to a female under 16 years of age than those who had trained in the United Kingdom. Cultural background may be influential in general practitioner provision of contraceptive services to females below the legal age of consent for sexual intercourse. In order to obtain more conclusive evidence a larger study is necessary. Such investigations must be undertaken with appropriate sensitivity and social awareness.

Adolescent↗
PubMed1998

Literature in our medical schools.

Despite many relevant benefits, the study of literature has been rejected by medical schools this century. However, the role of literature and the arts is coming to the fore again in many branches of medicine, including education, leading to a broader approach to medical practice than the purely scientific approach. This is likely to enrich the profession and individuals therein. As well giving as a wider general education, areas of medical training and practice that a literary education will benefit directly include critical reading and appraisal, communication skills, history taking, 'surrogate experience', understanding the role of the physician, ethics, and self-expression. Many of these are central to our understanding of good medical practice.

Communication↗
PubMed1997

Impaired odour discrimination on desynchronization of odour-encoding neural assemblies.

Stimulus-evoked oscillatory synchronization of neural assemblies has been described in the olfactory and visual systems of several vertebrates and invertebrates. In locusts, information about odour identity is contained in the timing of action potentials in an oscillatory population response, suggesting that oscillations may reflect a common reference for messages encoded in time. Although the stimulus-evoked oscillatory phenomenon is reliable, its roles in sensation, perception, memory formation and pattern recognition remain to be demonstrated--a task requiring a behavioural paradigm. Using honeybees, we now demonstrate that odour encoding involves, as it does in locusts, the oscillatory synchronization of assemblies of projection neurons and that this synchronization is also selectively abolished by picrotoxin, an antagonist of the GABA(A) (gamma-aminobutyric acid) receptor. By using a behavioural learning paradigm, we show that picrotoxin-induced desynchronization impairs the discrimination of molecularly similar odorants, but not that of dissimilar odorants. It appears, therefore, that oscillatory synchronization of neuronal assemblies is functionally relevant, and essential for fine sensory discrimination. This suggests that oscillatory synchronization and the kind of temporal encoding it affords provide an additional dimension by which the brain could segment spatially overlapping stimulus representations.

Animals↗
PubMed1997

Olfactory conditioning in the honey bee, Apis mellifera: effects of odor intensity.

Any odor-guided behavior might require generalization and/or discrimination over a wide range of odorant intensities. Proboscis extension conditioning (PEC) and electroantennogram (EAG) assays were used to investigate stimulus-intensity dynamics during olfactory processing in the honey bee. Experiments that tested generalization involved conditioning to one odorant concentration and either testing with a different odorant or with different concentrations of the same odorant. At low training concentrations, responses to either a novel odorant or to higher concentrations of the same odorant resulted in strong generalization. At higher training concentrations, significantly less generalization was observed to a novel odorant or to lower concentrations of the same odor. EAG analyses indicate that asymmetric generalization could arise due to long-term adaptation of peripheral receptor neurons. Discrimination experiments showed that relatively higher odorant concentrations associated with an appetitive reinforcer could usually be discriminated from a lower concentration that was associated with punishment, but not vice versa. Although sensory modulation in peripheral (sensory) processes might be sufficient to account for discrimination of a high from a low concentration, discrimination of low from high concentrations point to the involvement of central processes.

Animals↗
PubMed1997

A computational model of the response of honey bee antennal lobe circuitry to odor mixtures: overshadowing, blocking and unblocking can arise from lateral inhibition.

Recent studies of learning about elements of odorant mixtures in honey bees identified several types of interactions between mixture components, such as overshadowing and blocking. The latter phenomenon in particular indicates at least a limited ability of subjects to identify the most salient element of a binary mixture. Here we show that the circuitry in the antennal lobes, the first neuropil in which synaptic interaction affects sensory processing, could give rise to both effects given the incorporation of modifiable synapses onto inhibitory circuitry. The neural model of the antennal lobe that we present incorporates identified cell types and includes a biologically realistic modulatory neuron with which modifiable Hebb-like synaptic interactions take place. A learning rule that incorporates modifiable connections from output (projection) neurons onto the modulatory neuron is sufficient to account for behavioral results on generalization and overshadowing. A second type of excitatory connection from the modulatory neuron onto local inhibitory interneurons is necessary to reproduce behavioral results from blocking and unblocking. We suggest that the neural representations of odor mixtures in the antennal lobe can be modified by previous exposure to one of the mixture components. These results provide testable hypotheses that will guide future behavioral and physiological analyses.

Algorithms↗
PubMed1997

The Chronic Pain Grade questionnaire: validation and reliability in postal research.

The Chronic Pain Grade questionnaire has been proposed as an interview-administered, multi-dimensional measure of chronic pain severity in selected populations with chronic pain in the United States of America. It has not previously been tested in the United Kingdom, in self-completion form or in an unselected general population. We undertook a postal survey to assess its reliability, validity and acceptability in these circumstances, using a general practice population in Scotland, with a practice population of 11202 patients. A random sample of 400 patients aged over 18 was drawn, stratified for age, gender and receipt or non-receipt of regular prescriptions for pain-relieving medication. The dimensions and sub-scales of the Chronic Pain Grade were compared with the SF-36 general health questionnaire and questions relating to duration of any pain and attempts to seek treatment for this. The methodological approach proposed by Streiner and Norman (1989) was used to assess validity and reliability. A response rate of 76% was achieved. Cronbach's alpha was > 0.9 and item-total correlations were all high, indicating good internal consistency and reliability. Validity was confirmed by psychometric testing, including confirmatory factor analysis. Good correlations with comparable dimensions of the SF-36 general health questionnaire confirmed convergent validity. Construct validity was confirmed by testing scores against duration of pain and treatment sought for pain. We concluded that the Chronic Pain Grade questionnaire is a useful, reliable and valid measure of severity of chronic pain. It translates well into UK English and is acceptable in general population postal research.

Chronic Disease↗
PubMed1997

An analysis of blocking in odorant mixtures: an increase but not a decrease in intensity of reinforcement produces unblocking.

Studies of blocking between elements from the same stimulus modality elucidate how animals analyze such mixtures. Proboscis-extension conditioning of honey bees was used to examine the role of unconditioned stimulus (US) intensity in blocking in odorant mixtures. Several predictions from theoretical accounts of blocking were tested. One-trial blocking was found when subjects were pretrained with a high but not a low US concentration. Increases in US intensity produced unblocking, but decreases did not. Furthermore, an equivalent level of unblocking was observed when the increase occurred on the 1st or 2nd mixture-phase trials. These results are consistent with studies of vertebrates in which US intensity is altered to produce unblocking. Extension of these studies to include variation in other US parameters and to intramodal blocking in vertebrates will be necessary to determine whether this correspondence to vertebrate blocking is robust.

Acyclic Monoterpenes↗
PubMed1997

Humanizing medicine: a special study module.

As medical schools begin to implement their new curricula under the guidance of Tomorrow's Doctors, the authors wish to raise some discussion on the form and content of the special study module (SSM) component. In order to do this they put forward in this paper proposals for an SSM in Medicine and Literature. This course has been designed jointly and will be run concurrently in three Scottish medical schools: Glasgow, Aberdeen and Dundee. Arguments for the course's acceptability to faculties of medicine and to students are discussed and its inclusion in the curriculum in terms of its educational impact, skills training, effect on personal development and broadening of the student's perspective are justified. The course structure, content and assessment procedures are described and a reading list proposed. The General Medical Council points out that SSMs should be seen as opportunities for innovation and this course demands a different educational approach from the standard objectives-led approach of most medical education. A process-led model is more appropriate as it stresses the way that students develop while taking the course rather than the end point reached at its finish.

Curriculum↗
PubMed1997

The olfactory memory of the honeybee Apis mellifera. III. Bilateral sensory input is necessary for induction and expression of olfactory blocking.

The associative learning phenomenon termed 'blocking' demonstrates that animals do not necessarily associate a conditioned stimulus (e.g. X) with reinforcement if X is coincident with a second conditioned stimulus (e.g. A) that had already been associated with the same reinforcement. Blocking therefore represents a tactic that animals can use to modulate associative learning in order to focus on the most predictive stimuli at the expense of novel ones. Using an olfactory blocking paradigm in the honeybee, we investigated the mechanistic basis for olfactory blocking. We show that removing input from one antenna eliminates the blocking of one odor by another. Since antennal sensory neurons only project to the ipsilateral antennal lobe in the honeybee, more central processing regions of the brain than the antennae must be crucial for establishing blocking. Further experiments show that this bilateral interaction between brain hemispheres is crucial during both the induction and the expression of blocking. This result implies that blocking involves an active inhibition of odor association and recall, and that this inhibition is mediated by a structure that spans both brain hemispheres. This interpretation is consistent with a role for identified bilateral modulatory neurons in the production of blocking.

Animals↗
PubMed1996

Long-term preservation of islets of Langerhans in hydrophilic macrobeads.

Several obstacles have hindered the successful transplantation of islets of Langerhans to human patients in efforts to cure type I diabetes mellitus. One problem is the necessity for short- and long-term storage of islets after isolation and before transplantation. Current long-term storage methods, such as incubation in a physiological medium and cryopreservation, are suboptimal, resulting in significant loss of viable islet mass or function. Better storage methods are needed. In this study we examined the long-term storage of rat islets in macrobeads composed of agarose and collagen. Islets isolated from Wistar-Furth rats were placed into macrobeads (1000 islets/macrobead) and maintained in culture for periods of up to 189 days at 37 degrees C. Insulin released from the cultured macrobeads remained constant for periods of at least 154 days. In one group, insulin release was 1050 mU/24 hr/4 beads on day 3 and 1040 mU/24 hr/4 beads on day 154. In another group, insuling release was 1305 Xenotransplantation of Wistar Furth islet macrobeads, stored for 10 to 112 days at 37 degrees C, degrees C into 42 B6AF/1 mice with streptozotocin-induced diabetes resulted in a return to euglycemia in the recipients within 24 hr. Thereafter, euglycemia was maintained for more than 100 days in 32/42 of the recipients, and removal of the macrobeads caused a return to hyperglycemia within 48 hr in all animals. In addition, a group of 7 mice receiving macrobeads containing 1000 islets stored for 84 days had normal glucose tolerance tests (compared with those of 7 nontreated, nontransplanted mice with streptozotocin-induced diabetes and 7 normal mice), demonstrating that the islets in the macrobeads were functioning as they would in an intact pancreas. Finally, 5 macrobeads transplanted after initial storage of 112 days, removed from the first recipient after 100 days or more, stored again for 4 days in vitro, and retransplanted into 5 other diabetic mice also restored and maintained euglycemia for at least 45 days. Our results indicate that collagen-agarose macrobeads are capable of preserving rat pancreatic islets for extended periods without loss of in vitro insulin release capability or ability to achieve and maintain euglycemia in vivo. As such they should be useful for human islet transplantation efforts.

Animals↗
PubMed1996

Emergency contraception: a survey of women's knowledge and attitudes.

OBJECTIVES: To assess women's knowledge and attitudes in relation to emergency contraception and to identify ways in which these might be improved. DESIGN: Postal survey: questionnaire seeking level of knowledge of emergency contraception, and attitudes to use, publicity and availability. POPULATION: A stratified random sample of 2000 Grampian women aged 18 to 47. Women were identified through the Community Health Index. RESULTS: Most women (94%) were aware of emergency contraception and identified an appropriate source. Fewer (39%) knew the correct timing for its use. These figures were generally higher among younger, single women. The popular media represented the commonest source of information, and GPs and Family Planning Clinics were cited rarely. Increased advertising was considered desirable by 71% (mainly older women); only 36% (mainly younger, single women) considered over-the-counter availability desirable. Reasons for these responses and factors influencing them were explored. CONCLUSIONS: Knowledge of emergency contraception is greatest among those most likely to use it, but deficient mainly in relation to the correct timing for its use and to intrauterine methods. Publicity should concentrate on the timing of its use. The popular media are an important publicity vehicle, but health professionals appear to be under-used. Many women hold opinions on advertising and over-the-counter availability of emergency contraception which will have to be considered if deregulation proceeds.

Adolescent↗
PubMed1996

Cholesterol testing by general practitioners in Grampian: patterns and outcomes.

Initiation, distribution, concomitants and follow-up of cholesterol testing were studied in Grampian. Data were examined for 4979 patients, representing all patients in one year from those general practices who made exclusive use of the clinical chemistry laboratory for cholesterol testing. A random sample of 215 patients was studied in further detail. Age and sex distribution, results of cholesterol tests and their follow-up, nature and results of associated biochemical tests, test initiation, testing rates by practice, and prescription rates of lipid lowering agents by practice were measured. Cholesterol testing was mostly in line with current knowledge of cardiovascular risk, and associated with further cardiovascular and biochemical assessment. There was a 90-fold range in practice cholesterol testing rates, and a similarly wide range in prescription rates of lipid lowering agents; there was a significant correlation between these. Rates and results of follow-up testing suggests a "rule of halves" for cholesterol testing.

Adolescent↗