Insight into the Mechanisms Driving the Self-Assembly of Functional Interfaces: Moving from Lipids to Charged Amphiphilic Oligomers

Polymer-stabilized liquid/liquid interfaces are an important and growing class of bioinspired materials that combine the structural and functional capabilities of advanced synthetic materials with naturally evolved biophysical systems. These platforms have the potential to serve as selective membranes for chemical separations and molecular sequencers and to even mimic neuromorphic computing elements. Despite the diversity in function, basic insight into the assembly of well-defined amphiphilic polymers to form functional structures remains elusive, which hinders the continued development of these technologies. In this work, we provide new mechanistic insight into the assembly of an amphiphilic polymer-stabilized oil/aqueous interface, in which the headgroups consist of positively charged methylimidazolium ionic liquids, and the tails are short, monodisperse oligodimethylsiloxanes covalently attached to the headgroups. We demonstrate using vibrational sum frequency generation spectroscopy and pendant drop tensiometery that the composition of the bulk aqueous phase, particularly the ionic strength, dictates the kinetics and structures of the amphiphiles in the organic phase as they decorate the interface. These results show that H-bonding and electrostatic interactions taking place in the aqueous phase bias the grafted oligomer conformations that are adopted in the neighboring oil phase. The kinetics of self-assembly were ionic strength dependent and found to be surprisingly slow, being composed of distinct regimes where molecules adsorb and reorient on relatively fast time scales, but where conformational sampling and frustrated packing takes place over longer time scales. These results set the stage for understanding related chemical phenomena of bioinspired materials in diverse technological and fundamental scientific fields and provide a solid physical foundation on which to design new functional interfaces.

Author Correction: Dynamical nonlinear memory capacitance in biomimetic membranes

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Assembly and Characterization of Biomolecular Memristors Consisting of Ion Channel-doped Lipid Membranes

The ability to recreate synaptic functionalities in synthetic circuit elements is essential for neuromorphic computing systems that seek to emulate the cognitive powers of the brain with comparable efficiency and density. To date, silicon-based three-terminal transistors and two-terminal memristors have been widely used in neuromorphic circuits, in large part due to their ability to co-locate information processing and memory. Yet these devices cannot achieve the interconnectivity and complexity of the brain because they are power-hungry, fail to mimic key synaptic functionalities, and suffer from high noise and high switching voltages. To overcome these limitations, we have developed and characterized a biomolecular memristor that mimics the composition, structure, and switching characteristics of biological synapses. Here, we describe the process of assembling and characterizing biomolecular memristors consisting of a 5 nm-thick lipid bilayer formed between lipid-functionalized water droplets in oil and doped with voltage-activated alamethicin peptides. While similar assembly protocols have been used to investigate biophysical properties of droplet-supported lipid membranes and membrane-bound ion channels, this article focuses on key modifications of the droplet interface bilayer method essential for achieving consistent memristor performance. Specifically, we describe the liposome preparation process and the incorporation of alamethicin peptides in lipid bilayer membranes, and the appropriate concentrations of each constituent as well as their impact on the overall response of the memristors. We also detail the characterization process of biomolecular memristors, including measurement and analysis of memristive current-voltage relationships obtained via cyclic voltammetry, as well as short-term plasticity and learning in response to step-wise voltage pulse trains.

Memristive Ion Channel-Doped Biomembranes as Synaptic Mimics

Solid-state neuromorphic systems based on transistors or memristors have yet to achieve the interconnectivity, performance, and energy efficiency of the brain due to excessive noise, undesirable material properties, and nonbiological switching mechanisms. Here we demonstrate that an alamethicin-doped, synthetic biomembrane exhibits memristive behavior, emulates key synaptic functions including paired-pulse facilitation and depression, and enables learning and computing. Unlike state-of-the-art devices, our two-terminal, biomolecular memristor features similar structure (biomembrane), switching mechanism (ion channels), and ionic transport modality as biological synapses while operating at considerably lower power. The reversible and volatile voltage-driven insertion of alamethicin peptides into an insulating lipid bilayer creates conductive pathways that exhibit pinched current-voltage hysteresis at potentials above their insertion threshold. Moreover, the synapse-like dynamic properties of the biomolecular memristor allow for simplified learning circuit implementations. Low-power memristive devices based on stimuli-responsive biomolecules represent a major advance toward implementation of full synaptic functionality in neuromorphic hardware.

Evaporation-induced monolayer compression improves droplet interface bilayer formation using unsaturated lipids

In this article, we report on a new experimental methodology to enable reliable formation of droplet interface bilayer (DIB) model membranes with two types of unsaturated lipids that have proven difficult for creating stable DIBs. Through the implementation of a simple evaporation technique to condition the spontaneously assembled lipid monolayer around each droplet, we increased the success rates of DIB formation for two distinct unsaturated lipids, namely 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), from less than 10% to near 100%. Separately, using a pendant drop tensiometer, we learned that: (a) DOPC and POPC monolayers do not spontaneously assemble into their tightest possible configurations at an oil-water interface, and (b) reducing the surface area of a water droplet coated with a partially packed monolayer leads to a more tightly packed monolayer with an interfacial tension lower than that achieved by spontaneous assembly alone. We also estimated from Langmuir compression isotherms obtained for both lipids that the brief droplet evaporation procedure prior to DIB formation resulted in a 6%-16% reduction in area per lipid for DOPC and POPC, respectively. Finally, the increased success rates of formation for DOPC and POPC DIBs enabled quantitative characterization of unsaturated lipid membrane properties including electrical resistance, rupture potential, and specific capacitance.

Ankle Motion after External Fixation of Tibial Fractures

Loss of ankle movement is a complication of severe tibial fractures. This can be exacerbated if the foot is allowed to drop into equinus, particularly when an external fixator is employed. The range of ankle motion following external fixation of tibial fractures as compared to the opposite normal ankle was studied in 40 of 55 patients treated over a ten-year period. Nine were excluded due to other causes of ankle stiffness, leaving 31 cases for analysis. The mean follow up was 2 years 7 months (range 1 year to 8 years 3 months), and union had occurred by a mean of 35 weeks (range 9–100 weeks).

The mean loss of ankle movement was 8° of plantar-flexion and 12° of dorsiflexion (overall loss 20°), the difference between the two being highly significant (P> 0.001, t test). Loss of ankle motion closely paralleled the degree of soft tissue trauma, being 6° for closed fractures and 22° for open fractures (0.05 > P> 0.02). Ankle function is therefore at risk when a severe tibial fracture is treated by external fixation, and appropriate measures should be taken to preserve movement and prevent an equinus contracture.

Capacitive Detection of Low-Enthalpy, Higher-Order Phase Transitions in Synthetic and Natural Composition Lipid Membranes

In-plane lipid organization and phase separation in natural membranes play key roles in regulating many cellular processes. Highly cooperative, first-order phase transitions in model membranes consisting of few lipid components are well understood and readily detectable via calorimetry, densitometry, and fluorescence. However, far less is known about natural membranes containing numerous lipid species and high concentrations of cholesterol, for which thermotropic transitions are undetectable by the above-mentioned techniques. We demonstrate that membrane capacitance is highly sensitive to low-enthalpy thermotropic transitions taking place in complex lipid membranes. Specifically, we measured the electrical capacitance as a function of temperature for droplet interface bilayer model membranes of increasing compositional complexity, namely, (a) a single lipid species, (b) domain-forming ternary mixtures, and (c) natural brain total lipid extract (bTLE). We observed that, for single-species lipid bilayers and some ternary compositions, capacitance exhibited an abrupt, temperature-dependent change that coincided with the transition detected by other techniques. In addition, capacitance measurements revealed transitions in mixed-lipid membranes that were not detected by the other techniques. Most notably, capacitance measurements of bTLE bilayers indicated a transition at ∼38 °C not seen with any other method. Likewise, capacitance measurements detected transitions in some well-studied ternary mixtures that, while known to yield coexisting lipid phases, are not detected with calorimetry or densitometry. These results indicate that capacitance is exquisitely sensitive to low-enthalpy membrane transitions because of its sensitivity to changes in bilayer thickness that occur when lipids and excess solvent undergo subtle rearrangements near a phase transition. Our findings also suggest that heterogeneity confers stability to natural membranes that function near transition temperatures by preventing unwanted defects and macroscopic demixing associated with high-enthalpy transitions commonly found in simpler mixtures.

Small-scale density variations in the lunar crust revealed by GRAIL

Data from the Gravity Recovery and Interior Laboratory (GRAIL) mission have revealed that ~98% of the power of the gravity signal of the Moon at high spherical harmonic degrees correlates with the topography. The remaining 2% of the signal, which cannot be explained by topography, contains information about density variations within the crust. These high-degree Bouguer gravity anomalies are likely caused by small-scale (10's of km) shallow density variations. Here we use gravity inversions to model the small-scale three-dimensional variations in the density of the lunar crust. Inversion results from three non-descript areas yield shallow density variations in the range of 100-200 kg/m3. Three end-member scenarios of variations in porosity, intrusions into the crust, and variations in bulk crustal composition were tested as possible sources of the density variations. We find that the density anomalies can be caused entirely by changes in porosity. Characteristics of density anomalies in the South Pole-Aitken basin also support porosity as a primary source of these variations. Mafic intrusions into the crust could explain many, but not all of the anomalies. Additionally, variations in crustal composition revealed by spectral data could only explain a small fraction of the density anomalies. Nevertheless, all three sources of density variations likely contribute. Collectively, results from this study of GRAIL gravity data, combined with other studies of remote sensing data and lunar samples, show that the lunar crust exhibits variations in density by ±10% over scales ranging from centimeters to 100's of kilometers.

Direct in situ measurement of specific capacitance, monolayer tension, and bilayer tension in a droplet interface bilayer

Thickness and tension are important physical parameters of model cell membranes. However, traditional methods to measure these quantities require multiple experiments using separate equipment. This work introduces a new multi-step procedure for directly accessing in situ multiple physical properties of droplet interface bilayers (DIB), including specific capacitance (related to thickness), lipid monolayer tension in the Plateau-Gibbs border, and bilayer tension. The procedure employs a combination of mechanical manipulation of bilayer area followed by electrowetting of the capacitive interface to examine the sensitivities of bilayer capacitance to area and contact angle to voltage, respectively. These data allow for determining the specific capacitance of the membrane and surface tension of the lipid monolayer, which are then used to compute bilayer thickness and tension, respectively. The use of DIBs affords accurate optical imaging of the connected droplets in addition to electrical measurements of bilayer capacitance, and it allows for reversibly varying bilayer area. After validating the accuracy of the technique with diphytanoyl phosphatidylcholine (DPhPC) DIBs in hexadecane, the method is applied herein to quantify separately the effects on membrane thickness and tension caused by varying the solvent in which the DIB is formed and introducing cholesterol into the bilayer. Because the technique relies only on capacitance measurements and optical images to determine both thickness and tension, this approach is specifically well-suited for studying the effects of peptides, biomolecules, natural and synthetic nanoparticles, and other species that accumulate within membranes without altering bilayer conductance.

Heating-enabled formation of droplet interface bilayers using Escherichia coli total lipid extract

Droplet interface bilayers (DIBs) serve as a convenient platform to study interactions between synthetic lipid membranes and proteins. However, a majority of DIBs have been assembled using a single lipid type, diphytanoylphosphatidylcholine (DPhPC). The work described herein establishes a new method to assemble DIBs using total lipid extract from Escherichia coli (eTLE); it is found that incubating oil-submerged aqueous droplets containing eTLE liposomes at a temperature above the gel-fluid phase transition temperature (Tg) promotes monolayer self-assembly that does not occur below Tg. Once monolayers are properly assembled via heating, droplets can be directly connected or cooled below Tg and then connected to initiate bilayer formation. This outcome contrasts immediate droplet coalescence observed upon contact between nonheated eTLE-infused droplets. Specific capacitance measurements confirm that the interface between droplets containing eTLE lipids is a lipid bilayer with thickness of 29.6 Å at 25 °C in hexadecane. We observe that bilayers formed from eTLE or DPhPC survive cooling and heating between 25 and 50 °C and demonstrate gigaohm (GΩ) membrane resistances at all temperatures tested. Additionally, we study the insertion of alamethicin peptides into both eTLE and DPhPC membranes to understand how lipid composition, temperature, and membrane phase influence ion channel formation. Like in DPhPC bilayers, alamethicin peptides in eTLE exhibit discrete, voltage-dependent gating characterized by multiple open channel conductance levels, though at significantly lower applied voltages. Cyclic voltammetry measurements of macroscopic channel currents confirm that the voltage-dependent conductance of alamethicin channels in eTLE bilayers occurs at lower voltages than in DPhPC bilayers at equivalent peptide concentrations. This result suggests that eTLE membranes, via composition, fluidity, or the presence of subdomains, offer an environment that enhances alamethicin insertion. For both membrane compositions, increasing temperature reduces the lifetimes of single channel gating events and increases the voltage required to cause an exponential increase in channel current. However, the fact that alamethicin insertion in eTLE exhibits significantly greater sensitivity to temperature changes through its Tg suggests that membrane phase plays an important role in channel formation. These effects are much less severe in DPhPC, where heating from 25 to 50 °C does not induce a phase change. The described technique for heating-assisted monolayer formation permits the use of other high transition temperature lipids in aqueous droplets for DIB formation, thereby increasing the types of lipids that can be considered for assembling model membranes.

Trends in orthopaedic antimicrobial prophylaxis in the UK between 2005 and 2011

INTRODUCTION

Antimicrobial prophylaxis remains the most powerful tool used to reduce infection rates in orthopaedics but the choice of antibiotic is complex. The aim of this study was to examine trends in antimicrobial prophylaxis in orthopaedic surgery involving the insertion of metalwork between 2005 and 2011.

METHODS

Two questionnaires (one in 2008 and one in 2011) were sent to all National Health Service trusts in the UK using the Freedom of Information Act.

RESULTS

In total, 87% of trusts that perform orthopaedic surgery responded. The use of cefuroxime more than halved between 2005 and 2011 from 80% to 36% and 78% to 26% in elective surgery and trauma surgery respectively. Combination therapy with flucloxacillin and gentamicin rose from 1% to 32% in elective and 1% to 34% in trauma surgery. Other increasingly popular regimes include teicoplanin and gentamicin (1% to 10% in elective, 1% to 6% in trauma) and co-amoxiclav (3% to 8% in elective, 4% to 14% in trauma). The majority of changes occurred between 2008 and 2010. Over half (56%) of the trusts stated that Clostridium difficile was the main reason for changing regimes.

CONCLUSIONS

In 2008 a systematic review involving 11,343 participants failed to show a difference in surgical site infections when comparing different antimicrobial prophylaxis regimes in orthopaedic surgery. Concerns over C difficile and methicillin resistant Staphylococcus aureus have influenced antimicrobial regimes in both trauma and elective surgery. Teicoplanin would be an appropriate choice for antimicrobial prophylaxis in both trauma and elective units but this is not reflected in its current level of popularity.

Targeted mapping of Cdu1, a major locus regulating grain cadmium concentration in durum wheat (Triticum turgidum L. var durum)

Some durum wheat (Triticum turgidum L. var durum) cultivars have the genetic propensity to accumulate cadmium (Cd) in the grain. A major gene controlling grain Cd concentration designated as Cdu1 has been reported on 5B, but the genetic factor(s) conferring the low Cd phenotype are currently unknown. The objectives of this study were to saturate the chromosomal region harboring Cdu1 with newly developed PCR-based markers and to investigate the colinearity of this wheat chromosomal region with rice (Oryza sativa L.) and Brachypodium distachyon genomes. Genetic mapping of markers linked to Cdu1 in a population of recombinant inbred substitution lines revealed that the gene(s) associated with variation in Cd concentration resides in wheat bin 5BL9 between fraction breakpoints 0.76 and 0.79. Genetic mapping and quantitative trait locus (QTL) analysis of grain Cd concentration was performed in 155 doubled haploid lines from the cross W9262-260D3 (low Cd) by Kofa (high Cd) revealed two expressed sequence tag markers (ESMs) and one sequence tagged site (STS) marker that co-segregated with Cdu1 and explained >80% of the phenotypic variation in grain Cd concentration. A second, minor QTL for grain Cd concentration was also identified on 5B, 67 cM proximal to Cdu1. The Cdu1 interval spans 286 kbp of rice chromosome 3 and 282 kbp of Brachypodium chromosome 1. The markers and rice and Brachypodium colinearity described here represent tools that will assist in the positional cloning of Cdu1 and can be used to select for low Cd accumulation in durum wheat breeding programs targeting this trait. The isolation of Cdu1 will further our knowledge of Cd accumulation in cereals as well as metal accumulation in general.

"It's crucial they're treated as patients": ethical guidance and empirical evidence regarding treating doctor-patients

Ethical guidance from the British Medical Association (BMA) about treating doctor-patients is compared and contrasted with evidence from a qualitative study of general practitioners (GPs) who have been patients. Semistructured interviews were conducted with 17 GPs who had experienced a significant illness. Their experiences were discussed and issues about both being and treating doctor-patients were revealed. Interpretative phenomenological analysis was used to evaluate the data. In this article data extracts are used to illustrate and discuss three key points that summarise the BMA ethical guidance, in order to develop a picture of how far experiences map onto guidance. The data illustrate and extend the complexities of the issues outlined by the BMA document. In particular, differences between experienced GPs and those who have recently completed their training are identified. This analysis will be useful for medical professionals both when they themselves are unwell and when they treat doctor-patients. It will also inform recommendations for professionals who educate medical students or trainees.

Managing osteoporosis in patients with fragility fractures: did the British Orthopaedic Association guidelines have any impact?

INTRODUCTION

The incidence of fragility fractures could double in the next 50 years. Effective treatments for osteoporosis exist and the British Orthopaedic Association (BOA) has guidelines governing how to manage underlying osteoporosis in patients with fragility fractures. This study assessed how well two trauma units treat underlying osteoporosis and whether the BOA guidelines made any impact.

PATIENTS AND METHODS

Case notes of patients with a fracture of their proximal femur admitted during January and February in 2003, 2004 and 2005 were reviewed. The results were analysed for differences between site and year.

RESULTS

A total of 602 case notes were reviewed. There was a significant difference in the number of patients discharged on osteoporosis medication between the two sites (27% at LRI, 8% at KGH; P < 0.001), but not between 2003 and 2005 (22% and 16%; P = 0.16). Of the patients started on treatment, 83% were started on calcium and/or vitamin D(3) supplements.

CONCLUSIONS

The number of patients who had their underlying osteoporosis addressed was low and the type of treatment sub-optimal. This suggests the BOA guidelines have not made an impact and further work is required to improve the management of these patients.

What do patients really want to know in an informed consent procedure? A questionnaire-based survey of patients in the Bath area, UK

BACKGROUND

Medical decision making is based on patient autonomy and informed consent, which is an integral part of medical ethics, risk management and clinical governance. Consent to treatment has been extensively discussed, but the viewpoint of patients is not well represented. A new consent form was introduced by the Department of Health in 2001.

AIMS

To determine the information most important to patients, to facilitate evidence-based guidelines and to provide a valid and reliable consent-procedure-satisfaction questionnaire.

METHODS

An anonymous quantitative survey was carried out, asking 100 patients 15 questions regarding procedures they may need to undergo, using a Visual Analogue Scale to test the importance of each question.

RESULTS AND DISCUSSION

In total there were 77 respondents and the mean age was 48.8 (SD 17.63, range 20-82) years. There were 52% women and 48% men. Major complications, such as not undergoing the procedure, future management and long-term effect on work, all scored a median of 95%. Least concerns were related to technical details of the procedure and minor complications (median 64% and 63%, respectively). All other questions were still considered important (median 79-93%). No significant differences were observed between sex, age and professional groups, but a significant difference was observed between the education groups. Qualifications of the doctor did not correlate to any other question.

CONCLUSIONS

This questionnaire is proposed as a basis for informed consent guidelines to health workers and for measures of satisfaction with the consent procedure.

Open label extension studies: research or marketing?

Open label extension studies allow continued prescribing of unlicensed drugs after a randomised trial, but it is unclear whether patients or drug companies are benefiting the most

The effect of high dose atorvastatin therapy on lipids and lipoprotein subfractions in overweight patients with type 2 diabetes

Few data are available on the effects of high dose statin therapy on lipoprotein subfractions in type 2 diabetes. In a double blind randomised placebo-controlled trial we have studied the effects of 80 mg atorvastatin over 8 weeks on LDL, VLDL and HDL subfractions in 40 overweight type 2 diabetes patients. VLDL and LDL subfractions were prepared by density gradient ultracentrifugation. Triglycerides, cholesterol, total protein and phospholipids were measured and mass of subfractions calculated. HDL subfractions were prepared by precipitation. Atorvastatin 80 mg produced significant falls in LDL subfractions (LDL(1) 66.2 mg/dl:36.6 mg/dl, LDL(2) 118:56.6 mg/dl, LDL(3) 36.9:19.9 mg/dl all P < 0.01 relative to placebo) and VLDL subfractions (VLDL(1) 55:22.1 mg/dl, VLDL(2) 40.1:19.1 mg/dl, VLDL(3) 52.6:30 mg/dl all P < 0.01 relative to placebo). There was no change in the proportion of LDL present as LDL(3). There was a reduction in the proportion of VLDL as VLDL(1) and a reciprocal increase in the proportion as VLDL(3). Changes in VLDL subfractions were associated with changes in lipid composition, particularly a reduction in cholesterol ester and a reduction in the cholesterol ester/triglyceride ratio. Effects on HDL subfractions were largely neutral. High dose atorvastatin produces favourable effects on lipoprotein subfractions in type 2 diabetes which may enhance antiatherogenic potential.

Reverse genetic analysis of the glutathione metabolic pathway suggests a novel role of PHGPX and URE2 genes in aluminum resistance in Saccharomyces cerevisiae

We have taken a systematic genetic approach to study the potential role of glutathione metabolism in aluminum (Al) toxicity and resistance, using disruption mutants available in Saccharomyces cerevisiae. Yeast disruption mutants defective in phospholipid hydroperoxide glutathione peroxidases (PHGPX; phgpx1 Delta, phgpx2 Delta, and phgpx3Delta), were tested for their sensitivity to Al. The triple mutant, phgpx1 Delta/2Delta/3Delta, was more sensitive to Al (55% reduction in growth at 300 microM Al) than any single phgpx mutant, indicating that the PHGPX genes may collectively contribute to Al resistance. The hypersensitivity of phgpx3Delta to Al was overcome by complementation with PHGPX3, and all PHGPX genes showed increased expression in response to Al in the wild-type strain (YPH250), with maximum induction of approximately 2.5-fold for PHGPX3. Both phgpx3Delta and phgpx1Delta/2Delta/3Delta mutants were sensitive to oxidative stress (exposure to H(2)O(2) or diamide). Lipid peroxidation was also increased in the phgpx1Delta/2Delta/3Delta mutant compared to the parental strain. Disruption mutants defective in genes for glutathione S-transferases (GSTs) (gtt1Delta and gtt2Delta), glutathione biosynthesis (gsh1Delta and gsh2Delta), glutathione reductase (glr1Delta) and a glutathione transporter (opt1Delta) did not show hypersensitivity to Al relative to the parental strain BY4741. Interestingly, a strain deleted for URE2, a gene which encodes a prion precursor with homology to GSTs, also showed hypersensitivity to Al. The hypersensitivity of the ure2Delta mutant could be overcome by complementation with URE2. Expression of URE2 in the parental strain increased approximately 2-fold in response to exposure to 100 microM Al. Intracellular oxidation levels in the ure2Delta mutant showed a 2-fold (non-stressed) and 3-fold (when exposed-to 2 mM H(2)O(2)) increase compared to BY4741; however, the ure2Delta mutant showed no change in lipid peroxidation compared to the control. The phgpx1Delta/2Delta/3Delta and ure2Delta mutants both showed increased accumulation of Al. These findings suggest the involvement of PHGPX genes and a novel role of URE2 in Al toxicity/resistance in S. cerevisiae.

Arterial stiffness and central blood pressure, as determined by pulse wave analysis, in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is associated with increased cardiovascular mortality for reasons which are insufficiently understood. Chronic inflammation may impair vascular function and lead to an increase of arterial stiffness, an important determinant of cardiovascular risk.

OBJECTIVE

To investigate the augmentation index (AIx) as a measure of arterial stiffness in patients with RA, free of cardiovascular disease or risk factors, by means of a matched cohort pilot study.

METHOD

Patients with a diagnosis of RA, aged 50 years or younger, were screened for the absence of clinical cardiovascular disease and risk factors, such as smoking, hypercholesterolaemia, hypertension, and excessive systemic steroid use. Suitable subjects were assessed by non-invasive radial pulse wave analysis to determine their AIx. These data were compared with those from healthy controls, matched closely for sex, age, mean peripheral blood pressure, heart rate, and height.

RESULTS

14 suitable patients (11 female; mean (SD) age 42 (6) years, mean RA duration 11 (6) years; mean C reactive protein 19 (15) mg/l, no clinical systemic rheumatoid vasculitis) and matched controls were identified. The RA group had a higher mean (SD) AIx and mean (SD) central blood pressure (BP) than the control group: AIx 26.2 (6.7) v 18.9 (10.8)%, p=0.028; mean central BP 91.3 (7.8) v 88.2 (8.9) mm Hg, p<0.0001, by two tailed, paired t test.

CONCLUSIONS

This preliminary study suggests that RA is associated with increased arterial stiffness and central BP, independently of clinically manifest cardiovascular disease or risk factors. This may contribute to the increased cardiovascular mortality in RA.

Distribution of hydrogen in the near surface of Mars: evidence for subsurface ice deposits

Using the Gamma-Ray Spectrometer on the Mars Odyssey, we have identified two regions near the poles that are enriched in hydrogen. The data indicate the presence of a subsurface layer enriched in hydrogen overlain by a hydrogen-poor layer. The thickness of the upper layer decreases with decreasing distance to the pole, ranging from a column density of about 150 grams per square centimeter at -42 degrees latitude to about 40 grams per square centimeter at -77 degrees. The hydrogen-rich regions correlate with regions of predicted ice stability. We suggest that the host of the hydrogen in the subsurface layer is ice, which constitutes 35 +/- 15% of the layer by weight.

Vacuolar H+-ATPase, but not mitochondrial F1F0-ATPase, is required for aluminum resistance in Saccharomyces cerevisiae

It was recently shown that vacuolar ATPase and mitochondrial F1F0-ATPase activities are induced by aluminum (Al) in an Al-resistant cultivar of wheat, suggesting that induction of these enzymes could be an adaptive trait involved in Al resistance. To test this hypothesis, we used the Saccharomyces cerevisiae model system. In yeast, unlike wheat, the activity, transcript and protein levels of mitochondrial F1F0-ATPase, but not vacuolar ATPase, are induced by Al, while plasma membrane P-ATPase activity is inhibited. However, yeast vacuolar ATPase mutant strains are hypersensitive to Al, while F1F0-ATPase mutant strains exhibit wild-type growth. These data suggest that vacuolar ATPase activity is involved in Al resistance, with ATP required for this activity supplied by mitochondrial F1F0-ATPase or fermentation.

Endoscopic palliation and survival in malignant biliary obstruction

Malignant biliary obstruction is a common problem that is regarded as having a poor prognosis and is usually managed with palliation. Our aim was to investigate the survival of 182 consecutive subjects with malignant biliary obstruction where management was palliative with an [corrected] endoscopically placed biliary stent. We undertook a retrospective longitudinal study with date of death or confirmed survival of at least 23 months, as the primary end point. Diagnosis and blood indices from the 24 hr prior to first ERCP were obtained from hospital records. Of the 182 eligible subjects follow-up of date of death or confirmed survival of at least 23 months was obtained in 181 (99.5%). Of these 181 patients, 37 (20.4%) survived for more than one year. Histological confirmation was obtained in 47 of 182 subjects (25.8%). Increased age at first ERCP predicted increased survival (P < 0.05). In conclusion, in patients with malignant biliary obstruction, where management was endoscopic and palliative, 20.4% survived for more than one year with increased age at diagnosis being the only significant predictive marker.

An evaluation of the absolute and relative stability of alexithymia in patients with major depression

BACKGROUND

Previous studies demonstrating an association between alexithymia and depression have led to the proposal that alexithymia may be a state-dependent phenomenon rather than a stable and enduring personality trait. Several longitudinal studies have provided support for a trait view of alexithymia, but most of these studies evaluated absolute stability only (i.e., the extent to which alexithymia scores change over time) and did not examine the relative stability of alexithymia (i.e., the extent to which relative differences among individuals remain the same over time) in the context of changes in illness symptomatology. The present study evaluated both absolute stability and relative stability of alexithymia in depressed patients who experienced a marked reduction in the severity of depressive symptoms.

METHODS

Forty-six psychiatric outpatients with major depression were assessed for alexithymia and depression with the 20-item Toronto Alexithymia Scale and the Hamilton Rating Scale for Depression at the start of treatment (baseline) and after 14 weeks of treatment (follow-up) with antidepressant medication. Paired t tests and correlational analyses were performed to evaluate absolute stability and relative stability in alexithymia. Hierarchical regression analyses were then used to assess the degree to which the relative stability in alexithymia scores was related to the severity of depressive symptoms, and the degree to which changes in alexithymia scores could be attributed to changes in depression scores.

RESULTS

Alexithymia scores changed significantly from baseline to follow-up, indicating a general lack of absolute stability. There was, however, strong evidence of relative stability, as alexithymia scores at baseline correlated significantly with alexithymia scores at follow-up and were also a significant predictor of follow-up alexithymia scores, after partialling the effects of depression severity.

CONCLUSIONS

Although alexithymia scores may change in the presence of large changes in the severity of depressive symptoms, the finding of relative stability of alexithymia supports the view that this construct is a stable personality trait rather a state-dependent phenomenon.

Bedside tracer gas technique accurately predicts outcome in aspiration of spontaneous pneumothorax

BACKGROUND

There is no technique in general use that reliably predicts the outcome of manual aspiration of spontaneous pneumothorax. We have hypothesised that the absence of a pleural leak at the time of aspiration will identify a group of patients in whom immediate discharge is unlikely to be complicated by early lung re-collapse and have tested this hypothesis by using a simple bedside tracer gas technique.

METHODS

Eighty four episodes of primary spontaneous pneumothorax and 35 episodes of secondary spontaneous pneumothorax were studied prospectively. Patients breathed air containing a tracer (propellant gas from a pressurised metered dose inhaler) while the pneumothorax was aspirated percutaneously. Tracer gas in the aspirate was detected at the bedside using a portable flame ioniser and episodes were categorised as tracer gas positive (>1 part per million of tracer gas) or negative. The presence of tracer gas was taken to imply a persistent pleural leak. Failure of manual aspiration and the need for a further intervention was based on chest radiographic appearances showing either failure of the lung to re-expand or re-collapse following initial re-expansion.

RESULTS

A negative tracer gas test alone implied that manual aspiration would be successful in the treatment of 93% of episodes of primary spontaneous pneumothorax (p<0.001) and in 86% of episodes of secondary spontaneous pneumothorax (p=0.01). A positive test implied that manual aspiration would either fail to re-expand the lung or that early re-collapse would occur despite initial re-expansion in 66% of episodes of primary spontaneous pneumothorax and 71% of episodes of secondary spontaneous pneumothorax. Lung re-inflation on the chest radiograph taken immediately after aspiration was a poor predictor of successful aspiration, with lung re-collapse occurring in 34% of episodes by the following day such that a further intervention was required.

CONCLUSIONS

National guidelines currently recommend immediate discharge of patients with primary spontaneous pneumothorax based primarily on the outcome of the post-aspiration chest radiograph which we have shown to be a poor predictor of early lung re-collapse. Using a simple bedside test in combination with the post-aspiration chest radiograph, we can predict with high accuracy the success of aspiration in achieving sustained lung re-inflation, thereby identifying patients with primary spontaneous pneumothorax who can be safely and immediately discharged home and those who should be observed overnight because of a significant risk of re-collapse, with an estimated re-admission rate of 1%.

Bedside tracer gas technique accurately predicts outcome in aspiration of spontaneous pneumothorax

BACKGROUND

There is no technique in general use that reliably predicts the outcome of manual aspiration of spontaneous pneumothorax. We have hypothesised that the absence of a pleural leak at the time of aspiration will identify a group of patients in whom immediate discharge is unlikely to be complicated by early lung re-collapse and have tested this hypothesis by using a simple bedside tracer gas technique.

METHODS

Eighty four episodes of primary spontaneous pneumothorax and 35 episodes of secondary spontaneous pneumothorax were studied prospectively. Patients breathed air containing a tracer (propellant gas from a pressurised metered dose inhaler) while the pneumothorax was aspirated percutaneously. Tracer gas in the aspirate was detected at the bedside using a portable flame ioniser and episodes were categorised as tracer gas positive (>1 part per million of tracer gas) or negative. The presence of tracer gas was taken to imply a persistent pleural leak. Failure of manual aspiration and the need for a further intervention was based on chest radiographic appearances showing either failure of the lung to re-expand or re-collapse following initial re-expansion.

RESULTS

A negative tracer gas test alone implied that manual aspiration would be successful in the treatment of 93% of episodes of primary spontaneous pneumothorax (p<0.001) and in 86% of episodes of secondary spontaneous pneumothorax (p=0.01). A positive test implied that manual aspiration would either fail to re-expand the lung or that early re-collapse would occur despite initial re-expansion in 66% of episodes of primary spontaneous pneumothorax and 71% of episodes of secondary spontaneous pneumothorax. Lung re-inflation on the chest radiograph taken immediately after aspiration was a poor predictor of successful aspiration, with lung re-collapse occurring in 34% of episodes by the following day such that a further intervention was required.

CONCLUSIONS

National guidelines currently recommend immediate discharge of patients with primary spontaneous pneumothorax based primarily on the outcome of the post-aspiration chest radiograph which we have shown to be a poor predictor of early lung re-collapse. Using a simple bedside test in combination with the post-aspiration chest radiograph, we can predict with high accuracy the success of aspiration in achieving sustained lung re-inflation, thereby identifying patients with primary spontaneous pneumothorax who can be safely and immediately discharged home and those who should be observed overnight because of a significant risk of re-collapse, with an estimated re-admission rate of 1%.

Remobilization of cadmium in maturing shoots of near isogenic lines of durum wheat that differ in grain cadmium accumulation

Cadmium accumulation in grain of durum wheat (Triticum turgidum L. var. durum) represents a concern to consumers. In an effort to understand the regulation of Cd accumulation in maturing grain, the remobilization of 109Cd applied to stem and flag leaves was examined in two near-isogenic lines that differ in grain Cd accumulation. Absorbed 109Cd was primarily retained in the labelling flap (50-54% and 65-80% for stem and flag leaves, respectively). Cadmium exported from the stem flap initially (3 d) accumulated in the stem in a declining gradient towards the head. Subsequent remobilization of Cd deposited in the stem was associated with Cd accumulation in the grain. Cadmium exported from the flag leaf flap was primarily directed to the grain. Little (<1%) Cd accumulated in the glumes or rachis, and transport of Cd to shoot tissues below the flag leaf node was low (<1%). On average, 9% and 17% of absorbed 109Cd accumulated in the grain 14 d after labelling the stem and flag leaf, respectively. Irrespective of labelling position, the low Cd-accumulating isoline averaged 1.5-2-fold lower Cd accumulation per grain and Cd concentration in the grain than the high Cd-accumulating isoline. Cadmium accumulation in the grain was inversely correlated with Cd retention in the stem (stem labelled) and labelling flap (flag leaf labelled) for both isolines. Cadmium translocation to the grain was not inhibited by Zn when both were applied simultaneously (50 pM 109Cd; 0.5 microM 65Zn) to the flag leaf. These results show that elevated remobilization of Cd from the leaves and stem to the maturing grain may be partially responsible for the high accumulation of Cd in durum wheat grain.

A comparison of prophylactic antibiotic regimens against airborne orthopaedic wound contamination

Deep infection remains a major complication of joint replacement surgery despite advances in theatre design, surgical technique and antibiotic prophylaxis. Major randomized controlled trials to determine the most effective antibiotic prophylaxis are difficult to construct and interpret. In a conventional theatre, most orthopaedic intra-operative wound contamination arrives by the airborne route. This paper describes a unique method used to compare antibiotics against airborne bacteria. Seven antibiotics were incorporated into blood agar at concentrations equivalent to serum levels. Plates were then exposed to airborne theatre bacteria using a multiple synchronous collection technique. After incubation, the percentage kill was calculated for each antibiotic. At concentrations equivalent to serum level 1h post i.v. dose, all the antibiotics proved highly effective, with kill rates > 95%. Imipenem and co-amoxiclav significantly outperformed the other antibiotics with kill rates of 99.6% and 99.4%, respectively. At trough levels, the antibiotics achieved kill rates from 61% to 97.6%. Future randomized controlled trials comparing large numbers of antibiotics in the setting of an already low infection rate are inappropriate. This technique for comparing antibiotic prophylaxis in quick, inexpensive and repeatable. The superiority of imipenem is not unexpected, but of more interest is the effectiveness of co-amoxiclav over the presently favoured cefuroxime.

A model for analyzing the cost of the main clinical events after lung transplantation

BACKGROUND

The aim of this project was to model clinically important events experienced by lung transplant patients (from the day after transplant to 5 years or death) and costs associated with these events, and to assess the economic impact of different immunosuppression therapies.

METHODS

The population comprised 356 lung transplant patients (223 heart-lung, 102 single lung and 31 double lung) transplanted between April 1984 and December 1997. All patients received a cyclosporine-based triple-immunosuppression protocol. We designed a Markov model that included 3 time periods (0 to 6, 7 to 12, and 13 to 60 months), 5 clinical states (well, acute rejection, cytomegalovirus infection, non-cytomegalovirus infection and bronchiolitis obliterans syndrome), and death. For the well state, cost elements were immunosuppression, prophylaxis, and routine clinic visits. For all other states, cost elements were diagnosis, treatment, and bed days/visits. We excluded costs of the procedure.

RESULTS

The monthly costs associated with the well state decreased over time, from pound sterlings 1,778 ($2,658) in the first 6 months to pound sterlings 503 ($752) in months 7 to 12 and pound sterlings 350 ($523) after the first 12 months. The cost per event of the acute states remained reasonably constant over the 3 periods: pound sterlings 1,850 ($2,766) for rejection, pound sterlings 3,380 ($5,053) for cytomegalovirus, and pound sterlings 2,790 ($4,171) for other infections. The average cost per patient, discounted at 6%, over 5 years was pound sterlings 35,429 ($52,966) (95% range, pound1,435 [$2,145] to pound67,079 [$100,283]). This estimate is most sensitive to changes in immunosuppression. Substituting tacrolimus for cyclosporine increased 5-year costs by 5%; substituting mycophenolate mofetil for azathioprine increased 5-year costs by 26%.

CONCLUSIONS

This model is valuable in estimating the effect of new immunosuppression agents on the costs of follow-up care.

Induction of vacuolar ATPase and mitochondrial ATP synthase by aluminum in an aluminum-resistant cultivar of wheat

Two 51-kD aluminum (Al)-induced proteins (RMP51, root membrane proteins of 51 kD) were recently discovered in an aluminum-resistant cultivar of wheat (Triticum aestivum) cv PT741 (Basu et al., 1994a). These proteins segregate with the aluminum resistance phenotype in a segregating population arising from a cross between Al-resistant cv PT741 and Al-sensitive cv Katepwa (Taylor et al., 1997). The proteins have been purified by continuous elution electrophoresis and analyzed by peptide microsequencing. Sequence analysis of the purified peptides revealed that they are homologous to the B subunit of the vacuolar H+-ATPase (V-ATPase) and the alpha- and beta-subunits of the mitochondrial ATP synthase (F1F0-ATPase). To confirm that these ATPases are induced by Al, ATPase activity and transcript levels were analyzed under Al stress. Both V-ATPase and F1F0-ATPase activities were induced by Al and responded in a dose-dependent manner to 0 to 150 microM Al. In contrast, plasma membrane H+-ATPase (P-ATPase) activity decreased to 0.5x control levels, even when plants were exposed to 25 microM Al. Northern analysis showed that the transcript encoding the B subunit of V-ATPase increased by 2.2x in a dose-dependent manner, whereas levels of the transcript encoding the alpha-subunit of F1F0-ATPase remained constant. The effect of Al on ATPase activity in other cultivars was also examined. The Al-resistant cultivar, cv PT741, was the only cultivar to show induction of V- and F1F0-ATPases. These results suggest that the V-ATPase in cv PT741 is responding specifically to Al stress with the ATP required for its activity supplied by ATP synthase to maintain energy balance within the cell.

Effect of surgical training on outcome and hospital costs in coronary surgery

BACKGROUND

There is a perceived conflict between the need for service provision and surgical training within the National Health Service (NHS). Trainee surgeons tend to be slower (thereby reducing theatre throughput), and may have more complications (increasing hospital stay and costs).

OBJECTIVE

To quantify the effect of training on outcome and costs.

DESIGN

Data on 2740 consecutive isolated coronary artery bypass (CABG) operations were analysed retrospectively. Redo and emergency procedures were excluded. The seniority of the operating surgeon was related to operating times, risk stratified outcome, and overall hospital costs.

SETTING

Regional cardiothoracic surgery unit.

MAIN OUTCOME MEASURES

Postoperative mortality; hospital costs.

RESULTS

Consultants, senior trainees, intermediate trainees, and junior trainees performed 1524, 759, 434, and 23 procedures, respectively. Trainees at the three different levels were directly supervised by a consultant in 55%, 95%, and 100% of cases. The unadjusted mortalities were 3.2%, 2.0%, 2.3%, and 4.3%, respectively (NS). There were no significant differences between the groups with respect to time in the intensive care unit and length of hospital stay. The mean cost per patient was pound6619, pound6572, pound6494, and pound6404 (NS).

CONCLUSIONS

Trainees performed 44.4% of all CABG operations. There was no detrimental effect on patient outcome, length of hospital stay, or overall hospital costs. There need be little conflict between service and training needs, even in hospitals with extensive training programmes.

They took the time ... they started to care: stories of African-American nursing students in intercultural caring groups

Socially responsible nurse educators articulate the need to explore opportunities for nursing students to participate in experiences that promote caring and respect for diversity. This research illuminates the experiences of 10 African-American nursing students who participated in caring groups while enrolled in a predominantly White nursing education program. Although the meanings embedded in the African-American students' stories revealed commonalities with those of European-American and international students, there were also some differences. The authors maintained a critical social consciousness to analyze and describe these commonalities and differences. This article discusses the constitutive patterns and themes that emerged from the data and addresses implications for nursing education and practice.

Using a continuous time hidden Markov process, with covariates, to model bed occupancy of people aged over 65 years

Previously, the application of a continuous time hidden Markov model with discrete states was used to model geriatric inpatient behaviour. This was itself built on research using a discrete deterministic model to represent the flow of geriatric patients around departments of geriatric medicine. This paper uses the continuous time hidden Markov models and includes the effect of covariates, age and sex, in the model. Fitting the models we can visually see that the two compartment models provides estimates that are much closer to those observed in the data. The addition of covariates provides us with evidence of a difference in length of stay between men and women. However, even significant alterations to the mean age of patients in the model does not effect the length of stay.

Inoue balloon mitral valvuloplasty: long-term clinical and echocardiographic follow-up of a predominantly unfavourable population

AIMS

To assess long-term outcome in a typical Western population of predominantly unfavourable patients undergoing Inoue balloon mitral valvuloplasty. Outcome amongst patients has only been undertaken in the medium term. Long-term echocardiographic data in particular are scarce.

METHODS

Inoue mitral valvuloplasty was attempted in 106 patients. There were six technical failures; the procedure was therefore completed in 100 patients, who underwent annual clinical and echocardiographic follow-up.

RESULTS

Patients were aged 63.5+/-10. 3 years. 82% were female. Unfavourable characteristics included age >65 (52%), NYHA class III or IV (87%), >/=1 significant co-morbidity (63%), atrial fibrillation (82%), previous surgical commissurotomy (25%) and echocardiographic score >8 (59%, mean 8.9+/-2.1). Mitral valve area increased from 0.98+/-0.23 to 1.54+/-0.31 cm(2). There were three major complications. Post-procedure, symptoms improved in 88% of patients. Haemodynamic success (mitral valve area increase >50%, final mitral valve area >1.5 cm(2), mitral regurgitation </=grade 2) was achieved in 61% of cases. Mean follow-up was 4.3+/-1. 4 years. Survival was 97%, 88% and 82% at 1, 3 and 6 years. Event-free survival (freedom from death, mitral valve replacement or repeat valvuloplasty) was 96%, 82% and 56% at 1, 3 and 6 years. Freedom from restenosis (loss of >50% gain in mitral valve area, mitral valve area <1.5cm (2)) was 98%, 92% and 75% at 1, 3 and 6 years. Pre-procedural predictors of event-free survival were male sex, absence of co-morbidities, lower echocardiographic score and smaller left atrial diameter.

CONCLUSIONS

In a Western population with predominantly unfavourable characteristics for mitral valvuloplasty, long-term outcome post-procedure is reasonable. A moderate increase in mitral valve area can be achieved at low procedural risk, and the subsequent rate of restenosis is low. Nonetheless, 6 years after the procedure, half of the patients will have required further intervention or died. For fitter patients willing to accept significant operative risk, mitral valve replacement remains a valuable alternative.

Quantitative assessment of the effect of 0.05% chlorhexidine on rat articular cartilage metabolism in vitro and in vivo

Wound infection remains a problem. Syringe and needle jet lavage of chlorhexidine gluconate 0.05% removed or killed 99.8% of contaminating bacteria within 1 minute in a wound model. In clinical use, however, possible toxicity to articular cartilage is a concern. In an established intact rat patella model in vitro, 1 minute of exposure to chlorhexidine 0.05% and chlorhexidine jet lavage did not significantly alter cartilage metabolism. A 1-hour exposure decreased metabolic activity. In vivo, a 30-minute exposure with or without rinsing produced no impairment of metabolic activity 6 weeks later, suggesting that cartilage has the potential for biological recovery. However, injecting and leaving chlorhexidine 0.05% in the joints was detrimental to the metabolic activity of the articular cartilage as assessed 6 weeks later. Thus, chlorhexidine gluconate 0.05% could be used on normal articular cartilage. Any potential damage from prolonged exposure can be avoided by rinsing after 1 minute.

Direct measurement of aluminum uptake and distribution in single cells of Chara corallina

Quantitative information on the uptake and distribution of Al at the cellular level is required to understand mechanisms of Al toxicity, but direct measurement of uptake across the plasma membrane has remained elusive. We measured rates of Al transport across membranes in single cells of Chara corallina using the rare (26)Al isotope, an emerging technology (accelerator mass spectrometry), and a surgical technique for isolating subcellular compartments. Accumulation of Al in the cell wall dominated total uptake (71-318 microgram m(-2) min(-1)), although transport across the plasma membrane was detectable (71-540 ng m(-2) min(-1)) within 30 min of exposure. Transport across the tonoplast was initially negligible, but accelerated to rates approximating uptake across the plasma membrane. The avacuolate protoplasm showed signs of saturation after 60 min, but continued movement across the plasma membrane was supported by sequestration in the vacuole. Saturation of all compartments was observed after 12 to 24 h. Accumulation of Al in the cell wall reflected variation in [Al(3+)] induced by changes in Al supply or complexing ligands, but was unaffected by pH. In contrast, transport across the plasma membrane peaked at pH 4.3 and increased when [Al(3+)] was reduced by complexing ligands. Cold temperature (4 degrees C) reduced accumulation in the cell wall and protoplasm, whereas 2,4-dinitrophenol and m-chlorocarbonylcyanidephenyl hydrazone increased membrane transport by 12- to 13-fold. Our data suggest that the cell wall is the major site of Al accumulation. Nonetheless, membrane transport occurs within minutes of exposure and is supported by subsequent sequestration in the vacuole. The rapid delivery of Al to the protoplasm suggests that intracellular lesions may be possible.

Clinical versus actual outcome in cardiac surgery: a post-mortem study

BACKGROUND

Clinical attribution of the cause of death can be misleading, with the only true outcome measure being post-mortem analysis. Despite this there is very little published data on post-mortems following cardiac surgery.

METHODS

Prospective consecutive post-mortem data were collected on 167 patients (84.4% of all in-hospital cardiac surgical deaths) in a single institution. Clinical diagnoses were compared with post-mortem findings.

RESULTS

The mean age at death was 69.8 with 67.6% male. The proportion undergoing coronary artery bypass graft (CABG) alone was 52.1%, valve surgery 18.6%, valve+CABG 19.2% and other procedures 10.1%. The mean time to death was 7.9 days (range 0-87). The causes of death were cardiac 67.7%, gastrointestinal 9.6%, respiratory 8.4%, haemorrhage/technical failure 4.8%, stroke (cerebrovascular accident) 3.6%, multiorgan failure 3.0%, sepsis 1.8%, malignancy 0. 6% and trauma 0.6%. Post-mortem revealed an unsuspected cause of death in 19 (11.4%). These were gastrointestinal (infarction nine, perforation two), cardiac three, adult respiratory distress syndrome two, technical two and pulmonary embolus one. In addition, an unsuspected lung cancer was found in 1 patient who died of cardiac causes. When cardiac deaths were compared with non-cardiac causes the Parsonnet score was higher 20.0 (+/-1.4) vs. 15.3 (+/-1.6), P=0. 07; and a greater proportion tended to have poor ejection fractions (34 vs. 15%), P=0.12. There was no significant difference between the groups in terms of age, sex, operation, hypertension, diabetes, creatinine and body mass.

CONCLUSIONS

Post-mortem can determine unsuspected diagnoses in a significant proportion of cases. Pre-operative risk factors do not correlate with eventual cause of death. Post-mortem still has an important role to play in cardiac surgery.

Recent developments in alexithymia theory and research

OBJECTIVE

To review recent developments in alexithymia theory and research that are relevant to the field of psychosomatic medicine.

METHOD

Articles were selected from the alexithymia literature published over the past decade that describe advances in the theoretical understanding of alexithymia or report empirical investigations of the relationships of the construct with emotion regulation and with somatic illness and disease. Empirical investigations of the neural correlates of alexithymia were reviewed also, as were studies that explore therapeutic attempts to modify alexithymic characteristics.

RESULTS

The salient features of the alexithymia construct are now thought to reflect deficits in the cognitive processing and regulation of emotions. This is supported by studies showing that alexithymia is associated with maladaptive styles of emotion regulation, low emotional intelligence, a bidirectional interhemispheric transfer deficit, and reduced rapid eye movement (REM) density (number of eye movements divided by number of REM periods). Although empirical evidence demonstrates that alexithymia is associated with several somatic disorders, more prospective studies are required to establish the direction of causality. Preliminary data suggest that psychotherapies involving specific techniques to enhance emotional awareness and integrate symbolic and subsymbolic elements of emotion schemas may be effective in reducing alexithymic characteristics.

CONCLUSION

Alexithymia is proving to be a heuristically useful construct for exploring the role of personality and emotions in the pathogenesis of certain somatic illnesses and diseases.

A Swedish translation of the 20-item Toronto Alexithymia Scale: cross-validation of the factor structure

The purpose of this study was to develop a new Swedish translation of the twenty-item Toronto Alexithymia Scale (TAS-20) and to examine if the theoretical structure that underlies the factor structure of the English version of the TAS-20 could be recovered in this Swedish translation of the instrument. A sample of 157 undergraduate students of psychology was tested. Using confirmatory factor analysis, the previously established three-factor TAS-20 model was found to be replicable in this sample. In addition, the Swedish translation of the TAS-20 showed adequate internal reliability. The present study also illustrates the importance of using back translation methodology when transposing psychometric instruments from one language to another.

Relation between alexithymia and the five-factor model of personality: a facet-level analysis

The relation between alexithymia and both the domain and the facet level of the five-factor model (FFM) of personality was examined in a sample of 101 university students by using the Twenty-Item Toronto Alexithymia Scale (TAS-20; Bagby, Taylor, & Parker, 1994) and the Revised NEO Personality Inventory (Costa & McCrae, 1992c). Consistent with the alexithymia construct, the TAS-20 was positively correlated with Neuroticism (N) and negatively correlated with Extraversion (E) and Openness (O), whereas no significant relations were found with Agreeableness (A) and Conscientiousness (C). Analysis of the lower order traits (i.e., facets) of the FFM revealed that depression for N; positive emotions and assertiveness for E; feelings and actions for O; altruism, tender-mindedness, and modesty for A; and competence for C predicted alexithymia. These results support the uniqueness of the alexithymia construct, which is represented by a cluster of traits across the dimensions and facets of the FFM.

Alexithymia and functional gastrointestinal disorders. A comparison with inflammatory bowel disease

BACKGROUND

Although the alexithymia construct was derived from observations of patients with classical psychosomatic diseases, empirical studies have found only a moderate association between alexithymia and inflammatory bowel disease (IBD). Indeed, there is some evidence that alexithymia may be associated more strongly with functional somatic symptoms than with the psychosomatic diseases. The present study examined the relationship between alexithymia and functional gastrointestinal disorders (FGIDs) in a group of 121 FGID patients, and compared the results with findings from a group of 116 IBD patients and a group of 112 healthy subjects.

METHOD

The subjects completed the 20-item Toronto Alexithymia Scale and the Hospital Anxiety and Depression Scale.

RESULTS

The FGID group was significantly more alexithymic than the IBD group, and the two gastrointestinal groups were more alexithymic than the normal healthy group. These differences remained even after controlling for the influence of education, gender, anxiety, depression and gastrointestinal symptoms.

CONCLUSIONS

The finding of a high rate of alexithymia (66%) in the group of FGID patients is consistent with the propensity of these patients to somatization and to high levels of poorly differentiated psychological distress.

Interhemispheric transfer deficit in alexithymia: an experimental study

OBJECTIVE

Previous research has demonstrated an association between alexithymia and a deficit in interhemispheric communication in Vietnam combat veterans with posttraumatic stress disorder. The purpose of this study was to evaluate this association in a nonclinical sample.

METHODS

The efficiency of interhemispheric transfer was assessed in 14 alexithymic and 15 nonalexithymic right-handed, male, undergraduate university students using a tactile finger localization task.

RESULTS

The nonalexithymic subjects were significantly more efficient at transferring information between the cerebral hemispheres than the alexithymic subjects.

CONCLUSIONS

This finding provides further evidence of an interhemispheric transfer deficit in alexithymia and suggests that an alexithymic cognitive style reflects poor integration of the information processing of the two cerebral hemispheres.