Time-space-resolved origami hierarchical electronics for ultrasensitive detection of physical and chemical stimuli

Recent years have witnessed thriving progress of flexible and portable electronics, with very high demand for cost-effective and tailor-made multifunctional devices. Here, we report on an ingenious origami hierarchical sensor array (OHSA) written with a conductive ink. Thanks to origami as a controllable hierarchical framework for loading ink material, we have demonstrated that OHSA possesses unique time-space-resolved, high-discriminative pattern recognition (TSR-HDPR) features, qualifying it as a smart sensing device for simultaneous sensing and distinguishing of complex physical and chemical stimuli, including temperature, relative humidity, light and volatile organic compounds (VOCs). Of special importance, OSHA has shown very high sensitivity in differentiating between structural isomers and chiral enantiomers of VOCs – opening a door for wide variety of unique opportunities in several length scales.

Developing portable, disposable and cost-effective electronics for multifunctional sensing is desirable. Here, the authors present origami-based hierarchical electronics with time-space-resolved high-discriminative pattern recognition (TSR-HDPR) features for multifunctional detection of complex physical and chemical stimuli.

Preliminary Report of a Community Survey of Panic Attacks and Panic Disorder

This study looked at the prevalence of panic attacks and panic disorder in a British population. Three thousand people (aged 18–65) registered with a Leicester general practice were sent a postal questionnaire which screened for panic attacks. Where appropriate this was followed by a diagnostic interview. Preliminary results are reported for the first 1500 subjects sampled. Panic attacks are a common experience in the study population (7.5% of responders experienced them around the time of the interview). Panic disorder was diagnosed in about 3% of responders.

Metabolic fate of dietary terpenes fromEucalyptus radiata in common ringtail possum (Pseudocheirus peregrinus)

Arboreal marsupials consume terpenes in quantities that are toxic to other mammals, indicating that they possess special detoxification mechanisms. The metabolic fate of dietary terpenes was studied in the common ringtail possum (Pseudocheirus peregrinus). Three animals were fedEucalyptus radiata leaf for 10 days. Leaf consumption increased over three days to an average steady state of about 10-15 mmol total terpenes per day. GCMS analysis identified six urinary terpene metabolites, which were dicarboxylic acids, hydroxyacids, or lactones. Another nine metabolites could only be shown to be terpene-derived but of unknown structure. The amounts excreted were estimated by GC-FID, using response factors based on carbon content. Total 24-hr excretion of terpene-derived metabolites increased to 6.2-7.6 mmol on days 5-10, while glucuronic acid excretion remained constant at about 1.5 mmol. No other conjugates of terpene metabolites were found. The strategy used by the possum to detoxify dietary terpenes seems to be to polyoxygenate the molecules forming highly polar, acidic metabolites that can be readily excreted. Conjugation is minimal, perhaps to conserve carbohydrate and amino acids.

Three-dimensional simulations of liquid bridges between two cylinders: forces, energies, and torques

We present numerical simulations of three-dimensional liquid bridges between two identical smooth and chemically homogeneous cylinders held at a fixed distance and angle one with respect to the other. Despite the limited range of parameters studied, an analysis of resultant forces, energies, and torques reveals a rich level of detail. For large enough separations between the cylinders, the bridges appear symmetric and stable in shape and are found to yield a negligible torque on the cylinders. The force of adhesion is found to be positive in this case (the cylinders are attracted one to the other). A reduction in the distance between the cylinders reveals different behavior depending on the particular value of the set of parameters considered. For example, it appears that while relatively low contact angle systems favor attractive (positive) forces and stable symmetric bridges for small separation distances, larger contact angles lead to the coexistence of stable asymmetric and (apparently) unstable symmetric solutions, mostly (and respectively) associated with near-zero and negative (repulsive) forces of adhesion. In addition, while the larger values of contact angles studied here (90 degrees, 110 degrees) are associated with barely detectable torques, smaller values of contact angle are found to be associated with torques acting to rotate cylinders into a position where they are parallel one with respect to the other.

Pharmacokinetics of 1,8-cineole, a dietary toxin, in the brushtail possum (Trichosurus vulpecula): Significance for feeding

1,8-Cineole (cineole) is a Eucalyptus leaf toxin that defends against predation by herbivores such as the brushtail possum (Trichosurus vulpecula). The aim of the current study was to characterize the pharmacokinetics of cineole in the possum to improve understanding about how possums can avoid cineole toxicity when eating a Eucalyptus diet. Nine male possums were trapped in the wild and acclimated to captivity; a subcutaneous port was then implanted for venous blood sampling. Cineole was administered intravenously (10 and 15 mg kg(-1)) via a lateral tail vein and orally (30, 100 and 300 mg kg(-1)) by gavage, and blood concentrations of cineole and its metabolites were determined by gas chromatography. Cineole had a large terminal volume of distribution (V(z) = 27 l kg(-1)) and a high clearance (43 ml min(-1) kg(-1)), equal to hepatic blood flow. The terminal half-life was approximately 7 h. Oral bioavailability was low (F = 0.05) after low doses, but increased tenfold with dose, probably due to saturable first-pass metabolism. These findings indicate that when possums feed on a cineole diet, they eat until the cineole consumed is sufficient to saturate pre-systemic metabolism, leading to a rapid rise in bioavailability and cineole blood levels, and a cessation of the feeding bout. This is the first report on the pharmacokinetics of a dietary toxin in a wild herbivore, and provides insights into the interactions between the blood concentration of a plant secondary metabolite and the browsing behaviour of a herbivore.

Corresponding-states laws for protein solutions

The solvent around protein molecules in solutions is structured and this structuring introduces a repulsion in the intermolecular interaction potential at intermediate separations. We use Monte Carlo simulations with isotropic, pair-additive systems interacting with such potentials. We test if the liquid-liquid and liquid-solid phase lines in model protein solutions can be predicted from universal curves and a pair of experimentally determined parameters, as done for atomic and colloid materials using several laws of corresponding states. As predictors, we test three properties at the critical point for liquid-liquid separation: temperature, as in the original van der Waals law, the second virial coefficient, and a modified second virial coefficient, all paired with the critical volume fraction. We find that the van der Waals law is best obeyed and appears more general than its original formulation: A single universal curve describes all tested nonconformal isotropic pair-additive systems. Published experimental data for the liquid-liquid equilibrium for several proteins at various conditions follow a single van der Waals curve. For the solid-liquid equilibrium, we find that no single system property serves as its predictor. We go beyond corresponding-states correlations and put forth semiempirical laws, which allow prediction of the critical temperature and volume fraction solely based on the range of attraction of the intermolecular interaction potential.

Multiple extrema in the intermolecular potential and the phase diagram of protein solutions

Recent experiments have revealed several surprising features of the phase equilibria in protein solutions: liquid-liquid phase separation which is, in some cases, metastable with respect to the liquid-solid equilibrium, and in others-unobservable; widely varying crystallization enthalpies, including completely athermal crystallization; the co-existence of several crystalline polymorphs; and others. Other studies have shown that the solvent molecules at the hydrophobic and polar patches on the protein molecular surfaces are structured, introducing repulsive forces at surface separations equal to several water molecule sizes. In search of a causal link between the latter and former findings, we apply Monte Carlo simulation techniques in the investigation of phase diagrams associated with globular biological molecules in solution. We account for the solvent structuring via short-range isotropic two-body intermolecular potentials exhibiting multiple extrema. We show that the introduction of a repulsive maximum or a secondary attractive minimum at separations longer than the primary attractive minimum has dramatic effects on the phase diagram: liquid-liquid separation curves are driven to lower or higher temperatures, the sensitivity of the solubility curve (liquidus) to temperature, i.e., the enthalpy of crystallization, is significantly reduced or enhanced, metastable liquid-liquid separation may become stable and vice versa, and both low- and high-density crystalline phases are observed. The similarity of these features of the simulated phase behavior to those observed experimentally suggests that at least some of the mysteries of the protein phase equilibria may be due to the structuring of the solvent around the protein molecular surfaces. Another conclusion is that at least some of the dense liquids seen in protein solutions may be stable and not metastable with respect to a solid phase.

Partial wetting of chemically patterned surfaces: the effect of drop size

Partial wetting of chemically heterogeneous substrates is simulated. Three-dimensional sessile drops in equilibrium with smooth surfaces supporting ordered chemical patterns are considered. Significant features are observed as a result of changing the drop volume. The number of equilibrated drops is found either to remain constant or to increase with growing drop volume. The shape of larger drops appears to approach that of a spherical cap and their three-phase contact line seems, on a larger scale, more circular in shape than that of smaller drops. In addition, as the volume is increased, the average contact angle of drops whose free energy is lowest among all equilibrium-shaped drops of the same volume appears to approach the angle predicted by Cassie. Finally, contrary to results obtained with two-dimensional drops, contact angle hysteresis observed in this system is shown to exhibit a degree of volume dependence in the advancing and receding angles. Qualitative differences in the wetting behavior associated with the two different chemical patterns considered here, as well as differences between results obtained with two-dimensional and three-dimensional drops, can possibly be attributed to variations in the level of constraint imposed on the drop by the different patterns and by the dimensionality of the system.

Dexamethasone Suppression Tests in the Context of a Double-Blind Trial of Electroconvulsive Therapy and Simulated ECT

Dexamethasone suppression tests (DST) were performed before and after trial treatment in the Leicestershire trial of electroconvulsive therapy (ECT) in practice. Twenty-six depressed patients were studied before treatment, and in 18, tests were repeated immediately after the completion of trial treatments. No consistent pattern of relationship was observed between DST results and response to real or simulated ECT, although the pretreatment relationship between DST results and clinical picture was in accord with the expectations of the literature.

A survey of attitudes to parent-doctor conflicts over treatment for children

AIMS

To investigate professional and public attitudes to the intervention of the law when parents and doctors disagree about the medical treatment of children.

METHODS

A cross-sectional survey of academic staff at the University of Otago. Random samples of academic medical practitioners and non-Health Sciences academic staff completed written questionnaires, including open and closed questions. Questions focussed on the Liam Williams-Holloway (W-H) and Tovia Laufau (TL) cases.

RESULTS

The response rate was 107/164 (65%) of eligible staff. Support for doctors seeking treatment orders was strong (77% in the W-H case, and in the TL case, 70% believed an order should have been sought). Women were less likely than men to support a treatment order, significantly in the W-H case. There were no significant differences between medical and non-medical respondents. Court processes were viewed as confrontational and a last resort only after mediation failed. Scientific evidence was rated as the most important consideration in treatment decisions, followed by likely outcome, establishment of trust between parents and doctors, and the age of the child.

CONCLUSIONS

Among this highly educated group there was strong support for seeking treatment orders in the child's best interests. But various mediation options were preferred and should be explored further. More evidence is needed on the success of treatment orders and on the attitudes of a more representative sample of the population.

Does excretion of secondary metabolites always involve a measurable metabolic cost? Fate of plant antifeedant salicin in common brushtail possum, Trichosurus vulpecula

Salicin was administered orally to six brushtail possums by incorporation in food for six days at three dose levels (0.05, 0.5, and 1.5% wet weight), giving mean +/- SD daily intakes of 0.31 +/- 0.09, 2.76 +/- 0.75, and 6.04 +/- 1.12 mmol salicin. Metabolites were identified by mass spectrometry and assayed by HPLC. Salicyl alcohol glucuronide accounted for 56-64% of urinary metabolites over the three doses, salicyluric acid 15-26%, salicin 10-18%, and there were smaller amounts of free (2-4%) and conjugated (0-6%) salicylic acid. beta,2-Dihydroxyphenylpropionic acid was a minor metabolite. The hydrolysis of dietary salicin enabled reconjugation of its aglycone, salicyl alcohol, with a more polar sugar, glucuronic acid, thus enhancing its renal excretion and resulting in little net loss of substrates for conjugation and a low measurable metabolic cost of excretion.

Panic in a general practice population: prevalence, psychiatric comorbidity and associated disability

BACKGROUND

Panic disorder and simple panic are known to be common disorders associated with various physical and psychological difficulties, but their prevalence rates as reported in the literature vary widely. This paper is the result of a survey of panic in a general practice population, and discusses prevalence rates, screening for panic and psychiatric comorbidity. Comparisons are made between subjects with and without panic with regard to their self-reported disability.

METHODS

A random sample of 2000 individuals from the patient list of a group general practice were sent a questionnaire screening for panic attacks and asking for levels of everyday functioning and disability. Patients who screened positive for panic were interviewed using the Structured Clinical Interview for DSM III R.

RESULTS

A total of 1152 people responded to the questionnaire. In this sample, the lifetime prevalence of panic was 8.6%, and well over half of these had single or multiple additional psychiatric diagnoses. People with panic were found to perceive themselves as significantly less physically and psychologically healthy. It was found that screening questions that focussed on the psychological symptoms of panic missed a significant proportion of subjects with panic, particularly men.

CONCLUSION

The level of psychiatric comorbidity in this study mirrors that found by other investigators. The amount of perceived disability suffered by individuals with panic is considerable. This study may contribute to the argument that people with panic should be identified at an early stage, to prevent unnecessary investigation and ensure adequate treatment.

Characterization of murine vasopressor and vasodepressor prostaglandin E(2) receptors

Four E-prostanoid (EP) receptors, designated EP(1), EP(2), EP(3), and EP(4), mediate the cellular effects of prostaglandin E(2) (PGE(2)). The present studies pharmacologically characterize the vasopressor and vasodepressor EP receptors in wild-type mice (EP(2)(+/+) mice) and mice with targeted disruption of the EP(2) receptor (EP(2)(-/-) mice). Mean arterial pressure (MAP) was measured via a carotid artery catheter in anesthetized male mice. Intravenous infusion of PGE(2) decreased MAP in EP(2)(+/+) mice but increased MAP in EP(2)(-/-) mice. Infusion of EP(3)-selective agonists, including MB28767, SC46275, and sulprostone, increased MAP in both EP(2)(+/+) and EP(2)(-/-) mice. Pretreatment with SC46275 desensitized mice to the subsequent pressor effect of sulprostone, but the vasodepressor effect of PGE(2) in EP(2)(+/+) mice remained intact. Although PGE(2) alone increased MAP in EP(2)(-/-) mice, prior desensitization of the pressor effect with SC46275 allowed a residual vasodepressor effect of PGE(2) to be seen in the EP(2)(-/-) mice. An EP(4)-selective agonist (prostaglandin E(1)-OH) functioned also as a vasodepressor in both EP(2)(-/-) and EP(2)(+/+) mice. High levels of EP(3) receptor mRNA were detected in mouse aortas and rabbit preglomerular arterioles by nuclease protection, with lower expressions of EP(1), EP(2), and EP(4) mRNA. The findings suggest that combined vasodepressor effects of EP(2) and EP(4) receptors normally dominate, accounting for the depressor effects of PGE(2). In contrast, in EP(2)(-/-) mice, EP(4) receptor activity alone is insufficient to overcome the EP(3) vasopressor effect. These findings suggest that a balance between pressor and depressor PGE(2) receptors determines its net effect on arterial pressure and that these receptors may be important therapeutic targets.

Screening for osteoporosis using easily obtainable biometrical data: diagnostic accuracy of measured, self-reported and recalled BMI, and related costs of bone mineral density measurements

The aims of the present study were: to determine the diagnostic accuracy of objectively measured, self-reported and recalled body mass index (BMI) for osteoporosis and osteopenia; to determine the diagnostic costs, in terms of bone mineral density (BMD) measurements, per osteoporotic or osteopenic patient detected, using different BMI tests; and to determine the extent to which the results can be used within the framework of the current screening program for breast cancer in The Netherlands. Within the framework of a cross-sectional study on the prevalence of osteoporosis in the south of The Netherlands, 1155 postmenopausal women aged 50-80 years were asked for their present height and their weight at age 20-30 years. Subsequently their actual weight, height and BMD of the lumbar spine (DXA) were measured. The BMD cutoff was 0.800 g/cm2 for osteoporosis and 0.970 g/cm2 for low BMD (osteoporosis + osteopenia). After receiver operating characteristic analysis, age was cut off at 60 years and BMI at 27 kg/m2. Diagnostic accuracies of objectively measured, self-reported and recalled BMI were evaluated using predictive values (PV) and odds ratios. The resulting 'true positive' and 'false positive' rates were used to calculate diagnostic costs (i.e., DXA) for each osteoporotic patient or low-BMD patient detected. The prevalence of osteoporosis in the study population was 25%, that of low BMD 65%. Only the age-BMI tests 'age > or = 60, BMI < or = 27' showed PVs for osteoporosis (31-41%) and for low BMD (71-81%) that were higher than the prior probabilities for these conditions. Related odds ratios were 2.14-3.18 (osteoporosis) and 1.87-3.04 (low BMD). The objective BMI test detected 50% of the osteoporotic patients. Using the self-reported BMI test and the recalled BMI test, detection rates increased to 55% and 69%, respectively. Concomitant costs per osteoporotic patient detected rose by 24%. Detection of patients with a low BMD increased from 38% for objective BMI and 42% for self-reported BMI to 60% for recalled BMI. Related costs increased by 11%. If all women over 50 years of age (irrespective of their BMI) were to be referred for BMD measurement, costs per osteoporotic patient or low-BMD patient detected would be 304 and 116 Euros, respectively. Only in women over 60 years does a BMI below 27 kg/m2 provide a better prediction of the presence of osteoporosis or low BMD than could be expected solely on the basis of the relevant prevalences in postmenopausal women aged 50-80 years. If the use of BMI for the detection of osteoporotic or low-BMD patients is still considered, measuring weight and just asking for a person's height will do. Although age and BMI are the strongest risk factors for osteoporosis, they are of less significance when used for screening the population for osteoporosis. More research is needed before age and BMI can be included in any screening program. As regards practical considerations alone, measurements of BMD could be implemented within the screening program for breast cancer.

Salt-sensitive hypertension and reduced fertility in mice lacking the prostaglandin EP2 receptor

Prostaglandins (PGs) are ubiquitous lipid mediators derived from cyclooxygenase metabolism of arachidonic acid that exert a broad range of physiologic activities, including modulation of inflammation, ovulation and arterial blood pressure. PGE2, a chief cyclooxygenase product, modulates blood pressure and fertility, although the specific G protein-coupled receptors mediating these effects remain poorly defined. To evaluate the physiologic role of the PGE2 EP2 receptor subtype, we created mice with targeted disruption of this gene (EP2-/-). EP2-/- mice develop normally but produce small litters and have slightly elevated baseline systolic blood pressure. In EP2-/- mice, the characteristic hypotensive effect of intravenous PGE2 infusion was absent; PGE2 infusion instead produced hypertension. When fed a diet high in salt, the EP2-/- mice developed profound systolic hypertension, whereas wild-type mice showed no change in systolic blood pressure. Analysis of wild-type and EP2-/- mice on day 5 of pregnancy indicated that the reduced litter size of EP2-/- mice is due to a pre-implantation defect. This reduction of implanted embryos could be accounted for by impaired ovulation and dramatic reductions in fertilization observed on day 2 of pregnancy. These data demonstrate that the EP2 receptor mediates arterial dilatation, salt-sensitive hypertension, and also plays an essential part in female fertility.

Recovered memories of childhood sexual abuse. Implications for clinical practice

BACKGROUND

The growth in the USA of 'recovered memory therapy' for past sexual abuse has caused great public and professional concern. It became apparent that the polarisation of views and fierce controversy within the American psychiatric community was in danger of bringing psychotherapy into disrepute and it seemed important to examine objectively the scientific evidence before such polarisation developed in the UK.

METHOD

A small working group reviewed their own experience, visited meetings and centres with expertise in this field, interviewed 'retractors' and accused parents, and then began a comprehensive review of the literature.

RESULTS

There is a vast literature but little acceptable research. Opinions are expressed with great conviction but often unsupported by evidence.

CONCLUSIONS

The issue of false or recovered memories should not be allowed to confuse the recognition and treatment of sexually abused children. We concluded that when memories are 'recovered' after long periods of amnesia, particularly when extraordinary means were used to secure the recovery of memory, there is a high probability that the memories are false, i.e. of incidents that had not occurred. Some guidelines which should enable practitioners to avoid the pitfalls of memory recovery are offered.

Simulated Contact Angle Hysteresis of a Three-Dimensional Drop on a Chemically Heterogeneous Surface: A Numerical Example

A public domain software package is employed in the quasi-steady-state simulation of contact angle hysteresis. Three-dimensional sessile drops in equilibrium with a model chemically heterogeneous smooth solid surface are considered; evolving drop shapes, as a function of incremental changes in their volume, are investigated. Results are presented for a model system in which the intrinsic contact angle is assumed to vary along the surface in a periodic manner. Throughout the simulation, calculated contact angles show reasonable agreement with the local intrinsic contact angle values, and the computed drop shapes are found to be constant mean curvature surfaces. Significant hysteresis in the liquid-fluid interface curvature and average contact angle is found; a complete hysteresis loop is simulated. Advancing and receding contact angles exhibit the "stick-slip" behavior observed in experiments as well as in previous 2-D simulations.

Tissue content of alpha-tocopherol and oxidative stability of broilers receiving dietary alpha-tocopheryl acetate supplement for various periods pre-slaughter

1. The effects of dietary alpha-tocopheryl acetate on the alpha-tocopherol status of chicken plasma and tissues were investigated. The rate of iron-ascorbate-induced lipid peroxidation was also studied. 2. One hundred and forty four chicks were divided into 6 groups: one control group was fed a basal diet of 30 mg alpha-tocopheryl acetate/kg food for the duration of the trial. A supplemental diet of 200 mg alpha-tocopheryl acetate was fed to each of the other 5 groups for 1,2,3,4 or 5 weeks prior to slaughter. 3. Supplementation resulted in an increase in alpha-tocopherol in plasma and all tissues examined. Saturation levels of alpha-tocopherol were observed in plasma after 1 week of feeding and in tissues within 3 to 4 weeks of feeding. 4. Supplementation with alpha-tocopheryl acetate for up to 4 weeks pre-slaughter resulted in significant reductions in susceptibility to induced lipid peroxidation. 5. Overall, the results show that feeding 200 mg alpha-tocopheryl acetate/kg food to chicks for at least 4 weeks prior to slaughter is necessary to optimise muscle content and stability against lipid peroxidation.

Validation of the Dutch translation of the Inflammatory Bowel Disease Questionnaire (IBDQ): a health-related quality of life questionnaire in inflammatory bowel disease

Health-related quality of life assessment can benefit several groups involved with health care. The aim of our study was to assess construct validity, reliability, discriminant ability and sensitivity to change of the Dutch translation of the Inflammatory Bowel Disease Questionnaire (IBDQ), a disease-specific quality-of-life questionnaire. A group of 120 IBD patients completed the IBDQ and two Visual Analogue Scales concerning general well-being and bowel function twice. Fifty-two patients also completed the Short-Form 36 twice. Disease activity was assessed once. Correlations between the IBDQ scores and the global assessments were reasonably high and the IBDQ was shown to be discriminative. High intraclass correlation coefficients between both measurements of the IBDQ were observed in patients who reported no change in bowel complaints. In contrast, significant differences were found between both moments in patients who reported change. The Dutch IBDQ proved to be valid, discriminative and reliable.

Simulation of Contact Angle Hysteresis on Chemically Heterogeneous Surfaces

A quasi-steady-state simulation of contact angle hysteresis is presented. The model system consists of a two-dimensional drop on a smooth but chemically heterogeneous solid surface. The changes in the free energy of the system, the contact angle, and the size of the base of the drop are followed as its volume increases or decreases. The simulated contact angle hysteresis, including discontinuous changes in the contact angle and the size of the base of the drop, are shown to be very similar to typical experimental observations. In addition, the dependence of receding and advancing angles on the energy available for overcoming energy barriers is illustrated.

Quantitative urinary excretion of unmetabolised N tau-[Me-14C] methylhistidine by the common ringtail possum (Pseudocheirus peregrinus) marsupialia

Six common ringtail possums (Pseudocheirus peregrinus) were intravenously injected with a standard dose of radioactive 3-Methylhistidine (N tau-[Me-14C]MeH). The dose was rapidly and quantitatively excreted by the possums. More than 90% of radioactivity was recovered within 3 days. Thin layer chromatography and mass spectroscopy showed that 97% of recovered radioactivity was associated with unmetabolised N tau-[Me-14C]MeH. These data satisfy two key requirements for the validity of urinary 3-Methylhistidine (N tau-3MeH) excretion as an index of muscle protein catabolism, in P. peregrinus.

Coupling of the alpha 2A-adrenergic receptor to multiple G-proteins. A simple approach for estimating receptor-G-protein coupling efficiency in a transient expression system

It is now widely appreciated that G-protein-coupled cell-surface receptors can modulate distinct signal transduction pathways via coupling to different GTP-binding proteins. In the present study, we have used a transient co-expression approach to study the coupling of a single alpha 2-adrenergic receptor (alpha 2AAR) population to three different G protein subtypes (Gi, Gq, and Gs) acting on two different cellular effectors in HEK 293 cells. In all cases, the affinity of the receptor for the alpha 2A-adrenergic agonist, UK14304, is unchanged (KD approximately equal to 670 nM). However, there is a dramatic difference in the EC50 of UK14304 in eliciting inhibition of endogenous adenylyl cyclase via endogenous Gi (0.09 nM) versus activation of phospholipase C via co-transfected Gq (50 nM) or stimulation of endogenous adenylyl cyclase via co-transfected Gs (70 nM) in HEK 293 cells. These findings are consistent with the interpretations that the alpha 2AAR preferentially interacts with Gi rather than Gs or Gq. When the alpha 2AAR was mutated at Asp79, a residue highly conserved among G-protein-coupled receptors, the mutant D79N alpha 2AAR lost the ability to couple to Gq and Gs and, although it was able to couple to inhibition of cyclase via pertussis toxin-sensitive pathways (Gi), it did so with a lower potency than observed for the wild-type alpha 2AAR (EC50 = 7.2 nM). The most straightforward interpretation of these data is that the D79N mutation in the alpha 2AAR reduces the efficiency of coupling of the alpha 2AAR to all G-proteins, thus eliminating signal transduction through those pathways less efficiently coupled to the alpha 2AAR. Since the transient expression assays described permit manipulation of the structure of both the receptor or the G-protein, the present strategies could be exploited to delineate the complementary domains specifying the affinity and/or efficacy of receptor coupling to distinct GTP-binding proteins.

Subtyping of panic disorder by symptom profile

During Phase II of the Cross-National Panic Study, descriptions of the patient's last severe panic attack were collected for 1168 patients. Statistical analysis indicated that patients could be divided into two groups, characterised by the presence or absence of prominent respiratory symptoms. The two groups did not differ on demographic variables or coexisting diagnoses, but they did differ on psychopathology on entry to the study and treatment outcome. The group with prominent respiratory symptoms suffered more spontaneous panic attacks and responded to imipramine, whereas the group without prominent respiratory symptoms suffered more situational panic attacks and responded more to alprazolam. It is important to distinguish spontaneous and situational panic attacks, to aid choice of treatment.

Panic disorder: clinical perspectives

The evolution of the concept of panic disorder is described and its utility in identifying treatment strategies outlined. Some data are provided which may account for the female preponderance in diagnosed cases. In discussing the continuing role of benzodiazepines the curious history of their progressive restriction in Britain is described. Component and cluster analysis of the phenomena associated with panic attacks provides unexpected support for Klein's theory linking the disorder with an evolved alarm mechanism for suffocation. Current concepts on treatment are briefly reviewed.

Who benefits from electroconvulsive therapy? Combined results of the Leicester and Northwick Park trials

This paper describes the results obtained by combining data from the Northwick Park and Leicester randomised controlled trials of ECT. Patients who suffered from depression in which retardation and delusions were features and who received real ECT had a significantly improved outcome at the end of four weeks of treatment (as measured by improvement in the HRSD) in comparison with those who received simulated ECT. However, this treatment effect was not detectable at six-month follow-up. Patients who were neither retarded nor deluded did not benefit significantly from real as opposed to simulated ECT.

Synthesis of a yohimbine-agarose matrix useful for large-scale and micropurification of multiple alpha 2-receptor subtypes

We have provided a detailed protocol for the synthesis of a yohimbine-agarose matrix that has been shown to be effective for isolation of the alpha 2A-adrenergic receptor from human platelet and purification of the alpha 2A-adrenergic receptor to apparent homogeneity from porcine brain cortex using chromatography on only two sequential yohimbine-agarose columns. In addition, this affinity matrix also interacts with alpha 2 receptors of the alpha 2B subtype extracted from cultured NG108-15 cells. Finally, this affinity matrix has proven useful for monitoring posttranslational modifications of the receptor in digitonin extracts of metabolically labeled cells. Thus, this affinity matrix can be exploited for the purification of multiple alpha 2-adrenergic receptor subtypes on both a macro- and microscale and should be of value to any laboratory exploring the molecular basis for alpha 2-adrenergic functions.

Monovalent cation and amiloride analog modulation of adrenergic ligand binding to the unglycosylated alpha 2B-adrenergic receptor subtype

The unglycosylated alpha 2B subtype of the alpha 2-adrenergic receptor found in NG-108-15 cells possesses allosteric regulation of adrenergic ligand binding by monovalent cations and 5-amino-substituted amiloride analogs. These findings demonstrate that allosteric modulation of adrenergic ligand binding is not a property unique to the alpha 2A subtype. The observation that amiloride analogs as well as monovalent cations can modulate adrenergic ligand binding to the nonglycosylated alpha 2B subtype indicates that charge shielding due to carbohydrate moieties does not play a role in this allosteric modulation but, rather, these regulatory effects result from interactions of cations and amiloride analogs with the protein moiety of the receptor. Furthermore, the observation that both alpha 2A and alpha 2B receptor subtypes are modulated by amiloride analogs suggests that structural domains that are conserved between the two are likely to be involved in this allosteric modulation.