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Biomedical subjects

A F Smith

Publications and source records attributed to A F Smith.

At least 19 recordsLinked to original sources
PubMed2000

Premedication for anxiety in adult day surgery.

BACKGROUND: Surgery is increasingly performed on a day-case basis. Many patients are anxious pre-operatively and might benefit from pharmacological anxiolysis. Drugs are sometimes not used, however, for fear of delaying discharge from hospital. OBJECTIVES: To asses the effect of anxiolytic premedication on time to discharge in adult patients undergoing day case surgery under general anaesthesia. SEARCH STRATEGY: Trials were identified by computerised searches of the Cochrane Controlled Trials Register, MEDLINE, EMBASE, by checking the reference lists of trials and review articles, by hand-searching three main anaesthesia journals and by contacting five researchers active in the field and the Product Information departments of the manufacturers of five commonly used premedicants. SELECTION CRITERIA: All randomised controlled trials comparing an anxiolytic drug(s) with placebo before general anaesthesia in adult day case surgical patients. DATA COLLECTION AND ANALYSIS: We collected data on anaesthetic drugs used, results of tests of psychomotor function where these were used to assess residual effect of premedication, and on times from end of anaesthesia to ability to walk unaided or readiness for discharge from hospital. Formal statistical synthesis of individual trials was not performed in view of the variety of drugs studied. MAIN RESULTS: Searching identified twenty-nine reports; fourteen studies, with data from a total of 1263 patients, were considered eligible for analysis. Only two studies specifically addressed the discharge question; both found no delay in premedicated patients. Three other studies used clinical criteria to assess fitness for discharge, though times were not given. Again, there was no difference from placebo. Four studies used both clinical measures and tests of psychomotor function as tests of recovery from anaesthesia. In none of these studies did the premedication appear to delay discharge, although performance on tests of psychomotor function was sometimes still impaired. Of the four studies which used tests of psychomotor function to assess recovery, three showed impaired recovery (after midazolam 7.5mg, midazolam 15mg or diazepam 15mg) which might possibly interfere with discharge from hospital. REVIEWER'S CONCLUSIONS: We have found no evidence of a difference in time to discharge from hospital in patients who received anxiolytic premedication. However, in view of the age and variety of anaesthetic techniques used, inferences for current day-case practice should be made with caution.

Adult↗
PubMed1999

Targeted expression of SV40 large T-antigen to visceral smooth muscle induces proliferation of contractile smooth muscle cells and results in megacolon.

Many pathological conditions result from the proliferation and de-differentiation of smooth muscle cells leading to impaired contractility of the muscle. Here we show that targeted expression of SV40 large T-antigen to visceral smooth muscle cells in vivo results in increased smooth muscle cell proliferation without de-differentiation or decreased contractility. These data suggest that the de-differentiation and proliferation of smooth muscle cells, seen in many pathological states, may be independently regulated. In the T-antigen transgenic mice the increased smooth muscle cell proliferation results in thickening of the distal colon. Consequently the distal colon becomes hyper-contractile and impedes the flow of digesta through the colon resulting in enlargement of the colon oral to the obstruction. These transgenic mice thus represent a novel model of megacolon that results from increased smooth muscle cell proliferation rather than altered neuronal innervation.

Animals↗
PubMed1999

Communication skills for anesthesiologists.

PURPOSE: To provide a simple, practical guide to communication skills which might be useful to practising anesthesiologists. SOURCE: Selected citations from the literature on patient-physician communication, and the personal observations of the authors based on their reading and experiences. PRINCIPAL FINDINGS: Basic communication skills are introduced, and then their application to clinical anesthesiology described. The possible benefits resulting from the enhancement of clinical communication are outlined. Strategies for tackling four commonly-encountered situations - handling others' feelings, imparting information, explaining complex concepts simply and breaking bad news - are presented. By taking a skills-oriented approach, we hope that readers will be encouraged to view this area of their work as one that can be improved upon with continued observation and practice. CONCLUSION: Communication skills can enhance medical practice and improve patient outcomes. We suggest that all anesthesiologists should give thought to their effectiveness in this area.

Anesthesiology↗
PubMed1999

Patient-controlled sedation using propofol: randomized, double-blind dose refinement.

This double-blind, randomized trial compared the onset of sedation with two patient-controlled sedation regimens, allowing a maximum of 16 or 25 mg min-1 propofol. Forty fit young patients presenting for elective surgery were asked to try to put themselves to sleep using the system. Onset times of sedative effect, slurred speech and amnesia were recorded. All patients achieved satisfactory sedation, and none became oversedated. Patients receiving 16 mg min-1 propofol were not reliably sedated within 5 min and took significantly longer to develop slurred speech and amnesia (P < 0.01 for both). We conclude that this maximum infusion rate does not produce amnesia or sedation rapidly enough to be clinically useful. A maximum infusion rate of 25 mg min-1 allowed rapid sedation in all patients without oversedation and may be an acceptable compromise between efficacy and safety.

Adolescent↗
PubMed1998

Exploratory thoughts on clinical trials with utilities.

We consider problems of choice of sample size and allocation in the clinical trials context when utilities are explicitly taken into account. In particular, we consider utilities of benefits and side-effects (and their trade-offs), as well as utility functions that trade-off scientific and ethical concerns.

Bayes Theorem↗
PubMed1998

Can some in-hospital cardio-respiratory arrests be prevented? A prospective survey.

The hospital cardiac arrest team is summoned in response to a sudden severe deterioration in a patient's condition. However, clinical experience suggests that some calls to general wards are preceded by a more gradual, possibly treatable decline. We undertook this study to define the extent of the problem and look for features that might enable prediction and prevention of cardiorespiratory arrest. We identified patients on general medical and surgical wards for whom cardiac arrest calls had been made. Their casenotes were examined for documentation of abnormal physical signs and laboratory test results in the 24 h before the call. We noted what doctors and nurses had done after abnormalities had been found. Over a 28-week period, calls were made for 47 patients on these wards. Twenty-four (51%) had premonitory signs. These patients were also less likely to survive to hospital discharge (P = 0.02). We conclude that some cardiorespiratory arrests are predictable. Wider appreciation of the significance of abnormal signs and laboratory test results could lead to prompter involvement of experienced clinicians and more aggressive therapy. Alternatively, as mortality is so high in this group of patients, more patients could be appropriately designated 'not for resuscitation'.

Aged↗
PubMed1998

The psychological refractory period: evidence for age differences in attentional time-sharing.

The authors report 2 psychological refractory period (PRP) experiments in which the stimulus onset asynchrony (SOA) between Task 1 and Task 2 was 150 ms, 250 ms, 600 ms, and 1,100 ms for both younger and older adults. H. Pashler's (1994a) response-selection bottleneck theory predicts that SOA manipulations should not affect Task 1 performance, but that reaction time (RT) for Task 2 should increase as the SOA between the 2 tasks decreases (i.e., the classical PRP effect). In Experiment 1 (Task 1 = tone discrimination, Task 2 = dot location), older adults showed a larger PRP effect than younger adults did, although Task 1 RT was affected by SOA, suggesting that participants were grouping their responses on some trials. That is, participants were holding their response for Task 1 until they had completed processing Task 2, and then they responded to both tasks almost simultaneously. However, a subset of participants (11 younger adults and 11 older adults) who showed no evidence of response grouping on Task 1 continued to show a larger PRP effect for older adults on Task 2. In Experiment 2 (Task 1 = dot location, Task 2 = simultaneous letter matching), older adults continued to show a larger PRP effect than younger adults for Task 2, and Task 1 performance was unaffected by SOA. Consequently, these experiments provide evidence that older adults (relative to younger adults) exhibit a decrement in time-sharing at the response-selection stage of processing. These results suggest that attentional time-sharing needs to be added to the list of topics examined in aging research on varieties of attention.

Adult↗
PubMed1998

A molar entropy model of age differences in spatial memory.

Two very-short-term-memory, spatial scanning aging experiments were conducted involving a graphics character as a target stimulus. On the probe portion of a trial, the stimulus was presented in the same position as it was on the target portion of the trial (i.e., a same trial) 50% of the time. However, on the remaining 50% of the trials, the probe stimulus was shifted (or transposed) 1, 2, or 3 positions to the right or left of the original presentation (target) position. In Experiment 1, exposure duration was manipulated. In Experiment 2, the number of potential target display positions was manipulated. For both experiments, older adults showed larger transposition distance effects than younger adults for errors. In the past (e.g., P.A. Allen, 1990, 1991), this effect has been attributed to higher levels of internal noise (entropy) in older than younger adults. This research provides converging operations to this contention by using statistical physics methods to rigorously compute the entropy in a molar neural network across age groups. After successfully fitting the statistical mechanics model to the data, the model is proved to have external validity by fitting a simplified version of it to an earlier spatial memory aging experiment reported by P. R. Bruce and J. F. Herman (1986). The results of both traditional reaction time and error rate analyses, as well as the entropy modeling analyses, indicated that older adults exhibited higher levels of entropy than did the younger adults and that this effect appeared to be generalized across processing stage.

Adolescent↗
PubMed1998

A 310-bp minimal promoter mediates smooth muscle cell-specific expression of telokin.

A cell-specific promoter located in an intron of the smooth muscle myosin light chain kinase gene directs transcription of telokin exclusively in smooth muscle cells. Transgenic mice were generated in which a 310-bp rabbit telokin promoter fragment, extending from -163 to +147, was used to drive expression of simian virus 40 large T antigen. Smooth muscle-specific expression of the T-antigen transgene paralleled that of the endogenous telokin gene in all smooth muscle tissues except uterus. The 310-bp promoter fragment resulted in very low levels of transgene expression in uterus; in contrast, a transgene driven by a 2.4-kb fragment (-2250 to +147) resulted in high levels of transgene expression in uterine smooth muscle. Telokin expression levels correlate with the estrogen status of human myometrial tissues, suggesting that deletion of an estrogen response element (ERE) may account for the low levels of transgene expression driven by the 310-bp rabbit telokin promoter in uterine smooth muscle. Experiments in A10 smooth muscle cells directly showed that reporter gene expression driven by the 2.4-kb, but not 310-bp, promoter fragment could be stimulated two- to threefold by estrogen. This stimulation was mediated through an ERE located between -1447 and -1474. Addition of the ERE to the 310-bp fragment restored estrogen responsiveness in A10 cells. These data demonstrate that in addition to a minimal 310-bp proximal promoter at least one distal cis-acting regulatory element is required for telokin expression in uterine smooth muscle. The distal element may include an ERE between -1447 and -1474.

Animals↗
PubMed1997

An analysis of review articles published in four anaesthesia journals.

PURPOSE: To see if the authors of review articles in anaesthesia journals are making use of systematic methods in their preparation. METHODS: Twenty-five review articles published in 1995 in four major anaesthesia journals were analysed and compared with standard guidelines for the appraisal of reviews. RESULTS: Of the 25 articles, only 14 stated a clear purpose. Only two revealed the search strategy used to identity articles for the review. None of the reviews featured any type of quality assessment of the primary studies included, or stated what criteria, if any, were used to determine what material was included or excluded. Useful areas for future research were highlighted in only seven reviews. CONCLUSION: There is little evidence that reviews currently accepted for publication in anaesthesia journals have been prepared systematically.

Anesthesiology↗
PubMed1997

A Bayesian approach to validating STR multiplex databases for use in forensic casework.

A previous paper in this journal has described the conventional statistical analysis of three databases (Caucasian, Afro-Caribbean and Asians from the Indian subcontinent) where individuals are typed at six short tandem repeat (STR) loci. This paper presents a Bayesian analysis of the same data and the approach is centred on the concept of estimating coancestry coefficients from mixed databases. Posterior distributions for the three databases are presented and the discussed and the consequences of implementing bootstrap estimation procedures are also shown.

Bayes Theorem↗
PubMed1997

Word frequency effects at brief exposure durations: comment on Paap and Johansen (1994).

K. R. Paap and L. S. Johansen (1994) proposed that word frequency effects do not occur on a lexical decision task (LDT) when postmasked target exposure duration is sufficiently brief because such a task prevents verification--their hypothesized locus of the word frequency effect. In making this assertion, they proposed that the activation interpretation of A. R. Dobbs, A. Friedman, and J. Lloyd (1985) and of P. A. Allen, M. McNeal, and D. Kvak (1992) was flawed. However, evidence that Paap and Johansen's conclusions were wrong and that their experimental design contained flaws is provided here. In Experiment 1 of the present study, word frequency effects were evident on an LDT at the 75% accuracy level proposed by Paap and Johansen as being sufficiently low to prevent verification. In Experiment 2 the mental lexica of participants from the same population as that used for Experiment 1 contained very-low-frequency words. Thus, the present results are consistent with an activation locus.

Analysis of Variance↗