Tumour morphology as a predictor of outcome after local excision of rectal cancer

BACKGROUND

The aim of this study was to determine whether the morphology of rectal cancer predicts outcome following treatment by local excision, and whether morphology should therefore be added to the criteria presently used for case selection.

METHODS

The hospital notes and histological findings of 91 patients who had undergone a local surgical procedure for rectal cancer were reviewed retrospectively. Eight patient and tumour characteristics including morphology were analysed with respect to 5-year survival, local recurrence and cancer-specific death within 5 years. Morphology was divided into four types: polypoid, sessile, ulcerated and flat raised.

RESULTS

Survival and local recurrence were significantly better for patients with exophytic (polypoid and sessile) carcinomas than for those with non-exophytic (ulcerated and flat raised) lesions. Multivariate logistic regression analysis showed that age, depth of invasion, lymphatic invasion and venous invasion were significant predictors of outcome. The exophytic group included significantly more stage T1 and fewer T2 and T3 cancers, and a significantly smaller proportion of tumours that showed venous and lymphatic invasion than the non-exophytic group.

CONCLUSION

Morphology is a clinical guide to prognosis after local excision. Non-exophytic cancers are associated with high-risk histopathological features that render tumours of this type unsuitable for local excision.

West Nile virus encephalitis with myositis and orchitis

This report documents the hospital course and autopsy findings of a 43-year-old man with a renal allograft who died of West Nile virus (WNV) encephalitis. Central nervous system (CNS) findings were those of severe necrotizing and hemorrhagic encephalitis affecting gray matter regions limited to the diencepahlon, rhombencephalon, spinal cord, and limbic system. The bilateral process exhibited preferential involvement of motor neurons. Brain imaging obtained 6 days before death demonstrated an unusual pattern of involvement corresponding with the autopsy findings, confirming that imaging may be a specific diagnostic guide in WNV encephalitis. Extra-CNS findings include myositis with T-lymphocyte infiltration of nerve fibers, suggesting that the virus may reach the CNS via peripheral nerves. Orchitis with dense T-lymphocyte infiltration and syncytial cell formation thought to be due to WNV were also noted.

Membrane Cholesterol Regulates Smooth Muscle Phasic Contraction

The regulation of contractile activity in smooth muscle cells involves rapid discrimination and processing of a multitude of simultaneous signals impinging on the membrane before an integrated functional response can be generated. The sarcolemma of smooth muscle cells is segregated into caveolar regions-largely identical with cholesterol-rich membrane rafts-and actin-attachment sites, localized in non-raft, glycerophospholipid regions. Here we demonstrate that selective extraction of cholesterol abolishes membrane segregation and disassembles caveolae. Simultaneous measurements of force and [Ca2+]i in rat ureters demonstrated that extraction of cholesterol resulted in inhibition of both force and intracellular Ca2+ signals. Considering the major structural reorganization of cholesterol-depleted sarcolemma, it is intriguing to note that decreased levels of membrane cholesterol are accompanied by a highly specific inhibition of phasic, but not tonic contractions. This implies that signalling cascades that ultimately lead to either phasic or tonic response may be spatially segregated in the plane of the sarcolemma. Replenishment of cholesterol restores normal contractile behavior. In addition, the tissue function is re-established by inhibiting the large-conductance K(+)-channel. Sucrose gradient ultracentrifugation in combination with Western blotting analysis demonstrates that its alpha-subunit is associated with detergent-resistant membranes, suggesting that the channel might be localized within the membrane rafts in vivo. These findings are important in understanding the complex signalling pathways in smooth muscle and conditions such as premature labor and hypertension.

Antenatal Diagnostic Aspects of Unilateral Multicystic Kidney Dysplasia – Sensitivity, Specificity, Predictive Values, Differential Diagnoses, Associated Malformations and Consequences

OBJECTIVES

Unilateral multicystic kidney dysplasia (MCKD) is the second most common urinary tract abnormality diagnosed antenatally. Whilst an isolated unilateral MCKD has a good prognosis, a poor outcome must be expected when MCKD is associated with other complex abnormalities.

MATERIAL

Out of 11,176 cases, 693 fetuses were suspected of having urinary tract abnormalities. Urological findings were confirmed in 548 of them. Unilateral cystic kidney was diagnosed prenatally in 85 cases.

RESULTS

The study results in a total of 107 cases with proven MCKD. Eighty-five pregnancies with a prenatal diagnosis of MCKD were analysed. The antenatal diagnosis of MCKD was confirmed in 56 cases. Fifty-one children were found to have unilateral MCKD where this had not been explicitly suspected from antenatal scanning.

CONCLUSION

Unilateral MCKD is a malformation with an excellent prognosis for child survival and global renal function if encountered in isolation. However, our analysis of live infants and autopsy cases demonstrates a high proportion of severe associated malformations of the urinary tract and other organ systems.

The structure and reactivity of anchored nanoparticles on a reducible support

We have used scanning tunnelling microscopy (STM) to study the structure and reactivity of metal nanoparticles on a TiO2(110) surface. We have deposited two metals (Pt and Ru) using different techniques, metal vapour deposition (MVD) for Pt and metal organic chemical vapour deposition (MOCVD) for Ru. Pt was deposited onto a (1 x 3) reconstructed surface and is found to sinter at temperatures above 873 K, where the onset of nanoparticle mobility is expected. The effect that Pt has on the rate of re-oxidation of a more reduced titania sample with a (1 x 1) terminated surface was studied. At 673 K no preferential re-growth around the particles is observed and this has been attributed to the desorption characteristics of oxygen from Pt surfaces. The results are compared to those obtained from Pd covered TiO2 where such preferential growth has previously been observed. Ru was deposited using a carbonyl precursor, Ru3(CO)12, and is found to adsorb preferentially on the (1 x 2) rows of a surface consisting of both (1 x 1) and (1 x 2) added row structures. Upon annealing the compound is initially de-carbonylated to leave Ru nanoparticles on the surface, which can then sinter with increasing temperature. These particles have been alloyed with Pt and their re-oxidation characteristics studied. The alloy particles alter the oxygen desorption characteristics from that of the constituent elements (Pt and Ru) and consequently an enhancement in the rate of re-oxidation of a TiO2(110) surface at 673 K is observed.

Nanoscale proteomics

Efforts to develop a liquid chromatography (LC)/mass spectrometry (MS) technology for ultra-sensitive proteomics studies (i.e., nanoscale proteomics) are described. The approach combines high-efficiency nanoscale LC (separation peak capacity of approximately 10(3); 15-microm-i.d. packed capillaries with flow rates of 20 nL min(-1), the optimal separation linear velocity) with advanced MS, including high-sensitivity and high-resolution Fourier transform ion cyclotron resonance MS, to perform both single-stage MS and tandem MS (MS/MS) proteomic analyses. The technology enables broad protein identification from nanogram-size proteomics samples and allows the characterization of more abundant proteins from sub-picogram-size samples. Protein identification in such studies using MS is demonstrated from <75 zeptomole of a protein. The average proteome measurement throughput is approximately 50 proteins h(-1) using MS/MS during separations, presently requiring approximately 3 h sample(-1). Greater throughput (approximately 300 proteins h(-1)) and improved detection limits providing more comprehensive proteome coverage can be obtained by using the "accurate mass and time" tag approach developed in our laboratory. This approach provides a dynamic range of at least 10(6) for protein relative abundances and an improved basis for quantitation. These capabilities lay the foundation for studies from single or limited numbers of cells.

Achievement of dietary fatty acid intakes in long-term controlled intervention studies: approach and methodology

OBJECTIVE

To describe the calculations and approaches used to design experimental diets of differing saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) compositions for use in a long-term dietary intervention study, and to evaluate the degree to which the dietary targets were met.

DESIGN, SETTING AND SUBJECTS

Fifty-one students living in a university hall of residence consumed a reference (SFA) diet for 8 weeks followed by either a moderate MUFA (MM) diet or a high MUFA (HM) diet for 16 weeks. The three diets were designed to differ only in their proportions of SFA and MUFA, while keeping total fat, polyunsaturated fatty acids (PUFA), trans-fatty acids, and the ratio of palmitic to stearic acid, and n-6 to n-3 PUFA, unchanged.

RESULTS

Using habitual diet records and a standardised database for food fatty acid compositions, a sequential process of theoretical fat substitutions enabled suitable fat sources for use in the three diets to be identified, and experimental margarines for baking, spreading and the manufacture of snack foods to be designed. The dietary intervention was largely successful in achieving the fatty acid targets of the three diets, although unintended differences between the original target and the analysed fatty acid composition of the experimental margarines resulted in a lower than anticipated MUFA intake on the HM diet, and a lower ratio of palmitic to stearic acid compared with the reference or MM diet.

CONCLUSIONS

This study has revealed important theoretical considerations that should be taken into account when designing diets of specific fatty acid composition, as well as practical issues of implementation.

Extracranial-intracranial bypass in cerebral ischemia

While the utility of extracranial-intracranial (EC-IC) bypass versus medical therapy for typical stroke indications was cast in doubt in the mid-1980s, EC-IC bypass has continued to be useful for maintaining cerebral circulation in specific cases. A case report demonstrates the utility of EC-IC bypass using PET and SPECT scanning technologies to assess cerebral hemodynamics. While further studies will better define the patient population, there is a subset of stroke patients that benefit from cerebral revascularization.

PH-induced changes in calcium: functional consequences and mechanisms of action in guinea pig portal vein

The effects of changing extracellular (pH(o)) and intracellular pH (pH(i)) on force and the mechanisms involved in the guinea pig portal vein were investigated to better understand the control of tone in this vessel. When pH(o) was altered, the effects on force and calcium were the same irrespective of whether force had been produced spontaneously by high-K depolarization or by norepinephrine; alkalinization increased tone, and acidification reduced it. Because pH(o) changes also lead to changes in pH(i), we determined whether the effects on force could be explained by these induced pH(i) changes. It was found, however, that only with spontaneous activity did intracellular alkalinization increase force. In depolarized preparations, force was decreased, and, with norepinephrine, force was initially decreased and then increased. Thus the effects of pH(o) cannot be explained solely by changes in pH(i). The role of the sarcoplasmic reticulum (SR) and surface membrane Ca(2+)-ATPase on the mechanism were investigated and shown not to be involved. Therefore, it is concluded that both pH(o) and pH(i) can have powerful modulatory effects on portal vein tone, that these effects are not identical, and that they are likely to be due to effects of pH on ion channels rather than the SR or plasma membrane Ca(2+)-ATPase.

Characterisation of the ionic currents in freshly isolated rat ureter smooth muscle cells: evidence for species-dependent currents

To better understand excitability, and hence contraction, the ionic currents underlying the action potential were identified and characterised in enzymatically isolated smooth muscle cells of the rat ureter. Using the whole-cell patch-clamp, under voltage-clamp conditions with K(+) in the pipette, three types of responses occurred to depolarisation: (1) sustained outward current and spontaneous transient outward currents (STOCs); (2) inward current; and (3) fast outward current. Investigation using different voltage protocols and pharmacological blockers and agonists revealed the presence of three outward and two inward currents. The outward currents were: (1) a sustained BK current, sensitive to low concentrations of tetraethylammonium (TEA) and featuring bursts of STOCs superimposed on it; (2) a fast, transient, A-type K current sensitive to 4-aminopyridine; and (3) a TEA and Ca(2+)-insensitive, late K(+) rectifier current. The inward currents were: (1) a fast L-type Ca(2+) channel current sensitive to nifedipine, Cd(2+) and potentiated by Ba(2+); and (2) a Ca(2+)-sensitive Cl(-) channel, which was inhibited by niflumic acid and Ba(2+), and produced a large tail current upon repolarisation at the end of the voltage step. The I- V relationships and peak amplitudes of all the currents are described. The finding of a K(+) rectifier and Ca(2+)-activated Cl(-) channel distinguish the rat ureteric cells from those of the guinea-pig. Thus, as well as the previously established difference in sarcoplasmic reticulum Ca(2+)-release mechanisms, there is also a species difference in ion channel expression in this tissue. We relate these currents to their possible contribution to the characteristically extremely long lasting action potential in the rat ureter.

Devolved budgetary responsibility in primary care. A cross-country assessment of the impact on efficiency

General Practitioners and primary care physicians have a pivotal role in the allocation of health care resources in most countries. With increasing costs of care, they have therefore become a significant focus for healthcare reform in the pursuit of increased efficiency. For example, the United Kingdom (UK), United States of America (USA), New Zealand (NZ), Germany and The Netherlands, have all pursued reforms introducing explicit budgetary responsibilities for primary care. While there is a common set of objectives underlying such budgetary responsibilities, different versions have been introduced to reflect specific health environments. As most of these reforms were introduced in the early to middle 1990s, it is timely to examine their impact on efficiency. This paper therefore provides an econometric assessment of the effect of budgetary arrangements in the UK, USA, NZ, Germany and The Netherlands on the growth of primary care expenditure and flow-on costs (as proxied by pharmaceutical expenditure), as proxy indicators for efficiency. The results suggest that for all countries there is some support for efficiency improvements through the implementation of budgets for primary care.

Epidemiology for the equine practitioner

In this article, I have discussed the principles and methods of outbreak investigation, reinforcing important concepts with examples from the veterinary literature. The approach presented is applicable to outbreaks caused by any agent whether it is infectious versus noninfectious or contagious versus noncontagious. The solutions vary. The experience of others presented with similar situations may be especially helpful. Because of their nature, outbreaks are difficult to prepare for. When faced with a potential outbreak, the best strategy is to approach it scientifically, systematically, and with an open mind.

Omapatrilat versus lisinopril: efficacy and neurohormonal profile in salt-sensitive hypertensive patients

Omapatrilat, a vasopeptidase inhibitor, simultaneously inhibits neutral endopeptidase and ACE. The efficacy and hormonal profile of omapatrilat and lisinopril were compared in salt-sensitive hypertensive patients. On enrollment, antihypertensive medications were withdrawn, and patients received a single-blind placebo. On day 15, salt-sensitivity determinations were made. Salt-sensitive hypertensive patients returned within 5 to 10 days for baseline evaluations of ambulatory diastolic blood pressure, ambulatory systolic blood pressure, and atrial natriuretic peptide. Salt-sensitive hypertensive patients were randomized to receive double-blind omapatrilat (n=28) or lisinopril (n=33) at initial doses of 10 mg for 1 week, increasing to 40 and 20 mg, respectively, for an additional 3 weeks. Ambulatory blood pressure and urinary atrial natriuretic peptide were assessed at study termination. Both omapatrilat and lisinopril significantly reduced mean 24-hour ambulatory diastolic and systolic blood pressures; however, omapatrilat produced significantly greater reductions in mean 24-hour ambulatory diastolic blood pressure (P=0.008), ambulatory systolic blood pressure (P=0.004), and ambulatory mean arterial pressure (P=0.005) compared with values from lisinopril. Both drugs potently inhibited ACE over 24 hours. Omapatrilat significantly (P<0.001) increased urinary excretion of atrial natriuretic peptide over 0- to 24-hour (3.8-fold) and 12- to 24-hour (2-fold) intervals; lisinopril produced no change. Omapatrilat significantly (P<0.001) increased urinary excretion of cGMP over the 0- to 24- and 4- to 8-hour intervals compared with that from lisinopril. Neither drug had a diuretic, natriuretic, or kaliuretic effect. In conclusion, in salt-sensitive hypertensive patients, omapatrilat demonstrated the hormonal profile of a vasopeptidase inhibitor and lowered ambulatory diastolic and systolic blood pressures more than lisinopril.

Directly observed treatment for multidrug-resistant tuberculosis: an economic evaluation in the United States of America and South Africa

OBJECTIVE

To estimate the cost-effectiveness of directly observed treatment compared to conventional therapy in reducing the spread of multidrug-resistant tuberculosis, for an industrialised country (represented by the United States of America) and a developing country (South Africa).

METHODS

Monte Carlo analysis using published data on probability, cost and health impact.

RESULTS

In both countries, directly observed treatment is the dominant strategy, yielding cost savings and improved health outcomes. Cost savings for directly observed treatment relative to conventional therapy become more significant as more expensive second-line drugs are used in treatments.

CONCLUSIONS

The cost-effectiveness of directly observed treatment relative to conventional therapy is demonstrated for both the USA and South Africa. Cost savings are more pronounced (especially for South Africa) as the likelihood of multidrug-resistant tuberculosis increases and more expensive second-line therapies are used. Given that health care resources are more severely constrained in developing countries, the data contained in this study are useful in guiding the design of policies for the effective management of multidrug-resistant tuberculosis in settings with limited resources.

Controlled ion fragmentation in a 2-D quadrupole ion trap for external ion accumulation in ESI FTICR mass spectrometry

Undesired fragmentation of electrospray generated ions in an rf multipole traps can be problematic in many applications. Of special interest here is ion dissociation in a 2-D quadrupole ion trap external to a Fourier transform ion cyclotron resonance mass spectrometer (FTICR MS) used in proteomic studies. In this work, we identified the experimental parameters that determine the efficiency of ion fragmentation. We have found that under the pressure conditions used in this study there is a specific combination of the radial and axial potential well depths that determines the fragmentation threshold. This combination of rf and dc fields appears to be universal for ions of different mass-to-charge ratios, molecular weights, and charge states. Such universality allows the fragmentation efficiency of the trapped ions in the course of capillary liquid chromatography (LC) separation studied to be controlled and can increase the useful duty cycle and dynamic range of a FTICR mass spectrometer equipped with an external rf only 2-D quadrupole ion trap.

Dynamic range expansion applied to mass spectrometry based on data-dependent selective ion ejection in capillary liquid chromatography fourier transform ion cyclotron resonance for enhanced proteome characterization

The characterization of cellular proteomes is important for understanding biochemical processes ranging from cell differentiation to cancer development. In one highly promising approach, whole protein extracts or fractions are digested (e.g., with trypsin) and injected into a packed capillary column for subsequent separation. The separated peptides are then introduced on-line to an electrospray ionization source of a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer for the detection of peptide accurate mass tags that serve as biomarkers for their parent proteins. In this work, we report the use of data-dependent selective external ion ejection in conjunction with FTICR and on-line capillary LC separations for the enhanced characterization of peptide mixtures and a yeast extract proteome. The number of peptides identified in an LC-FTICR analysis of a yeast proteome digest employing data-dependent rf-only dipolar ejection of the most abundant ion species prior to ion accumulation was 40% higher than that detected in a separate LC-FTICR analysis using conventional nonselective ion accumulation.

Expression of transferrin receptor 2 in normal and neoplastic hematopoietic cells

Iron is essential for cell proliferation, heme synthesis, and a variety of cellular metabolic processes. In most cells, transferrin receptor-mediated endocytosis is a major pathway for cellular iron uptake. Recently, transferrin receptor 2 (TfR2), another receptor for transferrin, was cloned. High levels of expression of TfR2 messenger RNA (mRNA) occur in the liver, as well as in HepG2 (a hepatoma cell line) and K562 (an erythroid leukemia cell line). In this study, TfR2 mRNA expression was analyzed in hematological cell lines, normal erythroid cells at various stages of differentiation, and leukemia and preleukemia cells. High levels of TfR2 expression occurred in all of the erythroid cell lines that were examined. Erythroid-specific expression of TfR2 protein in bone marrow cells was confirmed by immunohistochemical staining. Expression of TfR2 mRNA was high in normal CD34(+) erythroid precursor cells, and levels decreased during erythroid differentiation in vitro. Levels of expression of TfR2-alpha mRNA were significantly higher in erythroleukemia (M6) marrow samples than in nonmalignant control marrow samples. In addition, relatively higher levels of TfR2-alpha mRNA expression occurred in some samples of myelodysplastic syndrome that had erythroid hyperplasia in bone marrow, acute myelogenous leukemia M1, M2, and chronic myelogenous leukemia. Expression profiles of normal members of the erythroid lineage suggest that TfR2-alpha may be a useful marker of early erythroid precursor cells. The clinical significance of TfR2-alpha expression in leukemia cells remains to be determined.

A dynamic ion cooling technique for FTICR mass spectrometry

A fast dynamic ion cooling technique based upon the adiabatic invariant phenomenon for Fourier transform ion cyclotron resonance mass spectrometry (FTICR) is presented. The method cools ions in the FTICR trap more efficiently, within a few hundred milliseconds without the use of a buffer gas, and results in a substantial signal enhancement. All performance aspects of the FTICR spectrum, e.g., peak intensities, mass resolution, and mass accuracy, improve significantly compared with cooling based on ion-ion interactions. The method may be useful in biological applications of FTICR, such as in proteomic studies involving extended on-line liquid chromatography (LC) separations, in which both the duty cycle and mass accuracy are crucially important.

Agonist-induced signaling, desensitization, and internalization of a phosphorylation-deficient AT1A angiotensin receptor

An analysis of the functional role of a diacidic motif (Asp236-Asp237) in the third intracellular loop of the AT1A angiotensin II (Ang II) receptor (AT1-R) revealed that substitution of both amino acids with alanine (DD-AA) or asparagine (DD-NN) residues diminished Ang II-induced receptor phosphorylation in COS-7 cells. However, Ang II-stimulated inositol phosphate production, mitogen-activated protein kinase, and AT1 receptor desensitization and internalization were not significantly impaired. Overexpression of dominant negative G protein-coupled receptor kinase 2 (GRK2)K220M decreased agonist-induced receptor phosphorylation by approximately 40%, but did not further reduce the impaired phosphorylation of DD-AA and DD-NN receptors. Inhibition of protein kinase C by bisindolylmaleimide reduced the phosphorylation of both the wild-type and the DD mutant receptors by approximately 30%. The inhibitory effects of GRK2K220M expression and protein kinase C inhibition by bisindolylmaleimide on agonist-induced phosphorylation were additive for the wild-type AT1-R, but not for the DD mutant receptor. Agonist-induced internalization of the wild-type and DD mutant receptors was similar and was unaltered by coexpression of GRK2K220M. These findings demonstrate that an acidic motif at position 236/237 in the third intracellular loop of the AT1-R is required for optimal Ang II-induced phosphorylation of its carboxyl-terminal tail by GRKs. Furthermore, the properties of the DD mutant receptor suggest that not only Ang II-induced signaling, but also receptor desensitization and internalization, are independent of agonist-induced GRK-mediated phosphorylation of the AT1 receptor.

Exclusive amplification of cDNA template (EXACT) RT-PCR to avoid amplifying contaminating genomic pseudogenes

Genomic DNA contamination within RNA samples has important implications for RT-PCR, particularly if there is a pseudogene related to the gene under investigation, because amplification from pseudogenes and reverse-transcribed cDNA can be very difficult to distinguish. Methods to remove DNA contamination cannot guarantee the absolute absence of DNA from the sample without a loss of RNA quantity or quality, which can be crucial for small amounts of RNA or for the investigation of transcripts with a low level of expression. Here, we describe a general technique for RT-PCR that applies a sequence to the 5' tail of reverse-transcribed cDNA that is not present in genomic DNA and uses this for annealing the reverse PCR primer to exclude genomic DNA amplification in unmodified RNA samples.

Blockade of rat alpha3beta4 nicotinic receptor function by methadone, its metabolites, and structural analogs

The opioid agonist properties of (+/-)-methadone are ascribed almost entirely to the (-)-methadone enantiomer. To extend our knowledge of the pharmacological actions of methadone at ligand-gated ion channels, we investigated the effects of the two enantiomers of methadone and its metabolites R-(+)-2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium perchlorate (EDDP) and R-(+)-2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline hydrochloride (EMDP), as well as structural analogs of methadone, including (-)-alpha-acetylmethadol hydrochloride (LAAM) and (+)-alpha-propoxyphene, on rat alpha3beta4 neuronal nicotinic acetylcholine receptors (nAChRs) stably expressed in a human embryonic kidney 293 cell line, designated KXalpha3beta4R2. (+/-)-methadone inhibited nicotine-stimulated 86Rb+ efflux from the cells in a concentration-dependent manner with an IC50 value of 1.9 +/- 0.2 microM, indicating that it is a potent nAChR antagonist. The (-)- and (+)-enantiomers of methadone have similar inhibitory potencies on nicotine-stimulated 86Rb+ efflux, with IC50 values of approximately 2 microM. EDDP, the major metabolite of methadone, is even more potent, with an IC50 value of approximately 0.5 microM, making it one of the most potent nicotinic receptor blockers reported. In the presence of (+/-)-methadone, EDDP, or LAAM, the maximum nicotine-stimulated 86Rb+ efflux was markedly decreased, but the EC50 value for nicotine stimulation was altered only slightly, if at all, indicating that these compounds block alpha3beta4 nicotinic receptor function by a noncompetitive mechanism. Consistent with a noncompetitive mechanism, (+/-)-methadone, its metabolites, and structural analogs have very low affinity for nicotinic receptor agonist binding sites in membrane homogenates from KXalpha3beta4R2 cells. We conclude that both enantiomers of methadone and its metabolites as well as LAAM and (+)-alpha-propoxyphene are potent noncompetitive antagonists of alpha3beta4 nAChRs.

The relative sensitivity of willingness-to-pay and time-trade-off to changes in health status: an empirical investigation

This paper directly compares the relative sensitivity of time-trade-off (TTO) and willingness-to-pay (WTP) values obtained for various levels of change in health status. This was achieved by administering a TTO and WTP survey to a population of 50 subjects, assessing their valuation of various degrees of change in health status. It was found that, overall, WTP is more sensitive than TTO in distinguishing between different dimensions of health at the same nominal level of health status (only four WTP values not significantly different, compared with eight TTO values). In addition, WTP was also more sensitive to differences in quality of life between different levels of health within each dimension (all values significantly different from each other, with TTO yielding three insignificant relationships). These results tentatively suggest, therefore, that WTP seems to be a more sensitive measure of change in health status than TTO.