Correcting for regression dilution in INTERSALT.
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Blood Pressure↗
Biomedical subjects
P Elliott
Publications and source records attributed to P Elliott.
Evidence for "clusters of anophthalmia" is thin.
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Anophthalmos↗
Haemodynamic effects of rocuronium during fentanyl anaesthesia: comparison with vecuronium.
Haemodynamic variables were measured following administration of rocuronium 0.6 mg.kg-1 or vecuronium 0.08 mg.kg-1 (approximately equivalent to 2 x ED95 doses) in patients anaesthetized with fentanyl 50 micrograms.kg-1 and scheduled to undergo elective coronary artery bypass grafting. There were increases in stroke volume index (+15%) and cardiac index (+11%), and a decrease in pulmonary capillary wedge pressure (-25%) following administration of rocuronium (P < 0.05). The changes in heart rate (+7%), mean arterial pressure (-5%), systemic vascular resistance (-12%) and other measured or derived indices were insignificant. In comparison the administration of vecuronium was associated with decreases in heart rate (-7%), mean pulmonary artery pressure (-17%), central venous pressure (-15%) and the rate-pressure product (-9%) (P < 0.05). The changes in mean arterial pressure (-7%), cardiac index (-6%) and systemic vascular resistance (-8%) following vecuronium were insignificant. There were no differences in any of the variables between rocuronium and vecuronium. The absolute values of all variables were, however, within acceptable clinical limits. There was no evidence of histamine release in any patient. The present study shows that rocuronium 0.6 mg.kg-1 is associated with changes of only small magnitude in haemodynamic variables.
Androstanols↗
Glutamatergic and non-glutamatergic responses evoked in neonatal rat lumbar motoneurons on stimulation of the lateroventral spinal cord surface.
The effects on lumbar motoneurons of thoracic cord stimulation were investigated in the neonatal rat hemisected spinal cord in vitro using intracellular recording. Four responses were evoked--a fast, excitatory postsynaptic potential, a second component to the fast excitatory postsynaptic potential, a fast inhibitory postsynaptic potential and a slow excitatory postsynaptic potential. The fast (CNQX-sensitive) excitatory postsynaptic potential was probably monosynaptic, was blocked by CNQX, (10 microM) and showed a frequency-dependent run-down at stimulation frequencies between 0.1 and 1 Hz. A slower component to the fast excitatory postsynaptic potential ((+-)-2-amino-5- phosphono-valeric acid-sensitive excitatory postsynaptic potential) was blocked by (+-)-2-amino-5-phosphonovaleric acid (50 microM). Following fast excitatory postsynaptic potential blockade with both CNQX and (+-)-2-amino-5-phosphonovaleric acid, a fast inhibitory postsynaptic potential was revealed. This reversed at a membrane potential close to resting and was incompletely blocked by either bicuculline (30 microM) or strychnine (10 microM). The slow excitatory postsynaptic potential was a delayed depolarization associated with a small increase in input resistance (20%) and was insensitive to block by CNQX and/or (+/-)-2-amino-5-phosphonovaleric acid. It increased in amplitude on membrane depolarization and decreased on hyperpolarization and was potentiated by cocaine (3 microM) and citalopram (0.1 microM), but not by desipramine (5 microM). The slow excitatory postsynaptic potential was blocked by ketanserin (1 microM) and by LY 53857 (1 microM). It is concluded that a non-glutamatergic transmitter is involved in generating the slow excitatory postsynaptic potential possibly 5-hydroxytryptamine acting at 5-hydroxytryptamine 2 receptors.
2-Amino-5-phosphonovalerate↗
Propofol-fentanyl anaesthesia in cardiac surgery: a comparison in patients with good and impaired ventricular function.
The haemodynamic effects of propofol-fentanyl anaesthesia for elective cardiac surgery were compared in 24 patients with good left ventricular function (ejection fraction > 45%, left ventricular end-diastolic pressure < 16 mmHg) and nine patients with impaired function. Anaesthesia was induced with fentanyl 25 micrograms.kg-1 and pancuronium 0.1 mg.kg-1 and was maintained with a variable rate propofol infusion, mean rate 2.61 mg.kg-1 x h-1 in the good ventricular function group and 2.71 mg.kg-1 x h-1 in the impaired function group. Additional fentanyl 7.5 micrograms.kg-1 was given before sternotomy. Ventilation to normocarbia was with air and oxygen (FIO2 0.6). Haemodynamic measurements were made before induction, after tracheal intubation, before and after sternotomy and before aortic cannulation. There were no significant differences between the groups in any haemodynamic variables during the study. Twenty minutes after intubation both groups showed a decrease from pre-induction values in mean arterial pressure (p < 0.05) and left ventricular stroke work index (p < 0.05), the reduction in left ventricular stroke work index remaining significant during the prebypass period in both groups. There were no significant changes in right or left sided filling pressures, systemic vascular resistance or heart rate. The technique decreased cardiac work and effectively controlled the autonomic responses to sternotomy in both groups. This study suggests that propofol may be a suitable adjunct to opioid anaesthesia in patients with impaired ventricular function having cardiac surgery.
Adolescent↗
Service in the snow. Maintaining care in rural California.
The amount of snow that falls in the Sierras is proof that all is not sunshine in rural northeastern California. Isolation and road closures were just two of the challenges that one home care agency was able to surmount with careful planning.
California↗
Global epidemiology.
Epidemiology is the study of the distribution and determinants of health and disease in human populations. Epidemiology on a global scale is severely constrained by the lack of data. In many countries, there are no comprehensive data on mortality or basic demographic data. Where data are available, findings on the relationship of environment to health across countries need to be interpreted with caution. For example, there is well-known variation in standards of medical practice and diagnosis, and in certification and coding, but there are also large differences in diet, the social environment and lifestyle--all of which strongly predict disease incidence. Inappropriate inference concerning aetiology made from such broad-scale studies may result in what has been termed the 'ecological fallacy'. A complementary approach is to collect and analyse data in standardized fashion as part of international collaborative studies. These can offer some important advantages over the more conventional single-centre design. Recent advances have meant that studies of environment and health can now--in some countries--be carried out using routine data at the small area level. Although problems of interpretation remain, they are generally less severe than in broad-scale studies. Examples of this approach are given.
Environmental Health↗
Blood pressure and life style in the People's Republic of China: three samples in the INTERSALT Study.
In INTERSALT, the International Cooperative Study on Electrolytes and Blood Pressure, three centres located in the People's Republic of China (PRC) had distinctive patterns of BP and of life style variables that, in INTERSALT overall, were found to relate to BP. The PRC centres had low body mass index (BMI) and alcohol consumption but high urinary sodium and sodium/potassium ratio (Na/K). Compared with 45 other INTERSALT centres, average BMI was 22.7 vs. 25.4 and alcohol consumption was 32% vs. 61%, with heavy drinking 3% vs. 14%. However, Na/K in the PRC was 6.7 vs. 3.2 in the other centres. This combination of factors may underlie the BP pattern observed. While mean BP in the PRC was lower than in the 45 centres (-7.0 mmHg SBP, -5.6 mmHg for DBP), this was counterbalanced by other findings. Upward slope of systolic pressure with age was 45% greater for the PRC than the other centres and 24% greater for diastolic pressure. As a result, although percentage hypertensive for ages 20-49 years for the PRC was half that in the 45 centres (6% vs. 12%), by age 50-59 years the prevalence was 31% in the PRC and 38% in the other centres. Hypertension prevalence in Tianjin, with highest Na/K in INTERSALT (7.6) was 40% for ages 50-59 years. While sample size in individual centres does not provide power to demonstrate aetiological relationships, these findings permit formulation of the following hypothesis: although lower body mass and lower alcohol intake may counteract to some degree impact of high salt intake, such intake over decades eventually takes its toll on BP.
Adult↗
Incidence of cancers of the larynx and lung near incinerators of waste solvents and oils in Great Britain.
The Small Area Health Statistics Unit (SAHSU) is a new independent facility for the investigation of disease near industrial installations in the UK. SAHSU analysed the incidence of cancers of the larynx and lung near the incinerator of waste solvents and oils at Charnock Richard, Coppull, Lancashire (which operated between 1972 and 1980) and nine other similar incinerators in Great Britain, after reports of a cluster of cases of cancer of the larynx near the Charnock Richard site. Postcoded cancer registration data were available for 1974-84 in England and Wales and 1975-87 in Scotland. Lag periods of 5 and 10 years were used between start-up (or first registration) of the incinerators and cancer incidence. Standardised observed/expected (O/E) ratios were assessed within 3 km and 3-10 km of each site and then aggregated over all sites. Expected values were based on national rates (regionally adjusted) with and without stratification by Carstairs' index, a measure of the socioeconomic profile of areas that uses census data for enumeration districts. Data were also assessed over a range of circles up to 10 km to test for trend in O/E ratios with distance. For Charnock Richard, none of the O/E ratios within 3 km or from 3-10 km differed significantly from unity, for either cancer or lag period. In the analysis of all sites with stratification by Carstairs' index, none of these O/E ratios differed significantly from unity for the two cancers. There was no evidence of decreasing risk with distance from the sites of either cancer. We conclude that the apparent cluster of cases of cancer of the larynx reported near Charnock Richard was unlikely to be due to its former incinerator.
Cluster Analysis↗
[Sudden and unexpected death--for the sake of research. A gruesome chapter from the history of anatomy of Edinburgh].
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Anatomy↗
Estimation of the potency of ORG 9426 using two different modes of nerve stimulation.
The potency of ORG 9426, a new nondepolarising muscle relaxant, has been estimated using two different modes of nerve stimulation in patients anaesthetised with thiopentone, nitrous oxide-oxygen and intravenous fentanyl. The force of contraction of adductor pollicis was measured following a single twitch (ST) at 0.1 Hz or a train-of-four (TOF) mode of stimulation at 2 Hz every ten seconds. Dose-response curves were constructed using a single-dose method. The ED50, ED90 and ED95 were 147,272 and 305 micrograms.kg-1 respectively using the ST mode and 125,230 and 257 micrograms.kg-1 using the TOF mode of stimulation. The ED50S were not significantly different but the differences between ED90S and ED95S were significant (P less than 0.05) indicating greater sensitivity of the neuromuscular junction using TOF stimulation. The results of this study suggest that the information obtained by single-twitch stimulation is not the same as that obtained from the first response of the TOF stimulation, suggesting apparently increased sensitivity (and apparently greater potency) with the TOF mode of stimulation. Org 9426 appears to be a drug with relatively low potency.
Adolescent↗
Discrimination between myocardial infarct and ventricular tachycardia patients using magnetocardiographic trajectory plots and iso-integral maps.
Magnetocardiograms were recorded from 30 normal (N) subjects, 15 myocardial infarct (MI) patients, and 15 ventricular tachycardia (VT) patients. Discrimination between the groups was affected by iso-integral magnetic field mapping (MFM) and trajectory plotting of MFM extrema. Iso-integral MFM for the QRST, QRS, and ST-T intervals was created for each test group member. A polarity score, based on the number of extrema features present, was assigned to each iso-integral MFM. Differences in group mean integral of QRST map polarity scores were significant (p less than 0.05) between MI and N, between VT and N (p less than 0.005), and between MI and VT (p less than 0.05) subjects. integral of ST-T map polarity scores were significantly (p less than 0.0001) different between VT and N and between MI and VT (p less than 0.001) subjects. Discrimination between MI and VT patients, based on polarity score difference, was 56% accurate using integral of QRS maps and 73% accurate using integral of ST-T maps. For each subject, time-normalized MFM was used to construct trajectory plots of the maxima and minima in the QRS and ST-T intervals. Discrimination between MI and VT patients was based upon intergroup differences in fragmented trajectory plots. When the number of discrete trajectories and/or the total number (F) of trajectory points at which discrete trajectories coexist were considered, QRSmin trajectory plots were significantly (p less than 0.05) different for VT and N, but not for MI and N subjects. The significant (p less than 0.05) difference between MI and VT trajectory plots enabled 76% accuracy for MI and VT identification. ST-Tmax trajectory plots show significantly (p less than 0.0001) higher F values for VT patients facilitating accurate (87%) discrimination between MI and VT patients. These results suggest that the abnormalities of repolarization processes, displayed by MFM as multipolar integral of ST-T maps and/or as fragmented trajectory plots of ST-T extrema, may be useful indicators of the arrhythmia substrate/processes that characterize VT and vulnerable MI patients.
Diagnosis, Differential↗
Serotonin and L-norepinephrine as mediators of altered excitability in neonatal rat motoneurons studied in vitro.
The actions of serotonin on the membrane properties of motoneurons and on the synaptic responses evoked by stimulating the segmental dorsal root have been investigated using intracellular recording in a neonatal rat hemisected spinal cord preparation in vitro. Superfusion with serotonin produced concentration-dependent depolarizations (EC50 32.1 microM) with an apparent increase in input resistance and increase in motoneuron excitability. During serotonin depolarizations an increase in membrane noise was seen. At higher serotonin concentrations repetitive firing was induced. Sensitivity to serotonin was enhanced by blockade of neuronal uptake with citalopram, when the EC50 was 1.4 microM. The depolarization was mimicked by alpha-methyl-5-hydroxytryptamine (EC50 11.7 microM). Serotonin depolarizations were blocked by ketanserin (0.1 and 1 microM), ritanserin (1 microM), spiperone (0.1 and 1 microM) and LY 53857 (1 microM). A norepinephrine-induced depolarization of motoneurons, which was mimicked by L-phenylephrine and antagonized by prazosin, is probably mediated by an alpha 1-adrenoceptor. An inhibitory action of serotonin was also apparent. The frequency and amplitude of spontaneous postsynaptic potentials and the response following dorsal root stimulation were markedly reduced. This action was mimicked by 5-carboxamidotryptamine and 8-hydroxy-2-(n-dipropylamino)tetralin, but was not antagonized by ketanserin (1 microM), ritanserin (1 microM), methiothepin (1 microM), metergoline (1 microM), spiperone (1-10 microM) or 21-009 (1-10 microM). It is proposed that the depolarization and increase in excitability of spinal motoneurons is mediated by a serotonin (5-HT2) receptor subtype.
Animals↗
Variance imputation for overviews of clinical trials with continuous response.
Overviews of clinical trials are an efficient and important means of summarizing information about a particular scientific area. When the outcome is a continuous variable, both treatment effect and variance estimates are required to construct a confidence interval for the overall treatment effect. Often, only partial information about the variance is provided in the publication of the clinical trial. This paper provides heuristic suggestions for variance imputation based on partial variance information. Both pretest-posttest (parallel groups) and crossover designs are considered. A key idea is to use separate sources of incomplete information to help choose a better variance estimate. The imputation suggestions are illustrated with a data set.
Analysis of Variance↗
Muscle pains and biochemical changes following suxamethonium administration after six pretreatment regimens.
The incidence of muscle pains and changes in serum concentrations of potassium, calcium and creatine kinase following suxamethonium were investigated after no pretreatment or pretreatment with intravenous tubocurarine 0.05 mg.kg-1, intravenous chlorpromazine 0.1 mg.kg-1, alphatocopherol (vitamin E) 600 mg in three divided doses orally, aspirin 600 mg orally or intravenous calcium chloride 5 mg.kg-1 in groups of 20 patients each. The incidence of myalgia was reduced significantly by tubocurarine, chlorpromazine and alphatocopherol. However, the increase in creatine kinase was attenuated only in the groups of patients who received tubocurarine and chlorpromazine. The changes in serum potassium and calcium concentrations were within acceptable limits. The intubating conditions were not as good in the patients who received tubocurarine as in the other groups. Effectiveness of chlorpromazine in preventing both the myalgia and the biochemical changes suggests the involvement of phospholipases in the pathogenesis of suxamethonium-induced muscle damage.
Adolescent↗
Postoperative oxygenation in the elderly following general or local anaesthesia for ophthalmic surgery.
Peripheral oxygen saturation was recorded on the pre-operative night (between 2400 and 0600 h), the immediate postoperative period (first 60 min) and the first postoperative night (2400 to 0600 h) in 18 elderly patients aged 70 years or over presenting for elective ophthalmic surgery. Nine patients had surgery performed under general anaesthesia employing muscle relaxants and controlled ventilation and nine under local anaesthesia using a peribulbar block. The median (interquartile range) percentage of time during which the patients had an oxygen saturation of less than 90% was 0 (0-0.2) and 0.04 (0-0.4) on the pre-operative night, 0.7 (0-1.4) and 0.3 (0-1.2) in the immediate postoperative period, and 0.05 (0-0.16) and 0 (0-0.3) on the postoperative night in the general and local anaesthesia patients respectively. There were no significant differences between general and local anaesthesia in respect of these data and the overall incidence of significant desaturation was low. The present study could not demonstrate any adverse effect of general anaesthesia on oxygen saturation in patients undergoing minimally invasive surgery.
Aged↗
Onset and duration of action of vecuronium in the elderly: comparison with adults.
The onset and duration of action of vecuronium were studied in young adult (n = 30; mean age 34 +/- 11.1 (s.d.) yr), middle-aged (n = 20; mean age 60 +/- 5.8 yr) and elderly patients (n = 30; mean age 80 +/- 4.6 yr) anaesthetised with thiopentone, nitrous oxide in oxygen and halothane. Neuromuscular block was monitored by applying the train-of-four (TOF) stimulation at 2 Hz to the ulnar nerve every 12 s. Half the patients in each group received 0.08 and the other half 0.12 mg kg-1 of the relaxant. The time to return of T1 (first response in the TOF sequence) to 25% of control was 28 +/- 5.2 (s.d.), 34 +/- 7.1 and 39 +/- 10.2 min following 0.08 mg kg-1 dose (P less than 0.05 between the elderly and young adults) and 45 +/- 9.2, 48 +/- 6.2 and 69 +/- 19.2 min following 0.12 mg kg-1 dose, respectively, in the three age groups (P less than 0.05 between the elderly and the other two groups). The recovery indices (time for 25-75% recovery of T1) after the 0.08 mg kg-1 was 9.6 +/- 3.4, 13.6 +/- 5.1 and 17.4 +/- 6.1 min, respectively (P less than 0.05 between the elderly and young adults). There was no significant difference in any of the parameters between the young adults and the middle-aged. The onset of block at each dose was not significantly different between the three age groups; however, the time to maximum effect was significantly shorter with the higher dose in the young and the middle-aged, but not in the elderly. Regression analysis of the data between age and the duration of action and recovery index suggested a significant prolongation (P less than 0.05) of these parameters in the elderly.
Adult↗
The Small Area Health Statistics Unit: a national facility for investigating health around point sources of environmental pollution in the United Kingdom.
STUDY OBJECTIVE: The Small Area Health Statistics Unit (SAHSU) was established at the London School of Hygiene and Tropical Medicine in response to a recommendation of the enquiry into the increased incidence of childhood leukaemia near Sellafield, the nuclear reprocessing plant in West Cumbria. The aim of this paper was to describe the Unit's methods for the investigation of health around point sources of environmental pollution in the United Kingdom. DESIGN: Routine data currently including deaths and cancer registrations are held in a large national database which uses a post code based retrieval system to locate cases geographically and link them to the underlying census enumeration districts, and hence to their populations at risk. Main outcome measures were comparison of observed/expected ratios (based on national rates) within bands delineated by concentric circles around point sources of environmental pollution located anywhere in Britain. MAIN RESULTS: The system is illustrated by a study of mortality from mesothelioma and asbestosis near the Plymouth naval dockyards during 1981-87. Within a 3 km radius of the docks the mortality rate for mesothelioma was higher than the national rate by a factor of 8.4, and that for asbestosis was higher by a factor of 13.6. CONCLUSIONS: SAHSU is a new national facility which is rapidly able to provide rates of mortality and cancer incidence for arbitrary circles drawn around any point in Britain. The example around Plymouth of mesothelioma and asbestosis demonstrates the ability of the system to detect an unusual excess of disease in a small locality, although in this case the findings are likely to be related to occupational rather than environmental exposure.
Asbestosis↗